FN Thomson Reuters Web of Science™ VR 1.0 PT J AU Zhang, RY Leu, MT Molina, MJ AF Zhang, RY Leu, MT Molina, MJ TI Formation of polar stratospheric clouds on preactivated background aerosols SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NITRIC-ACID; ANTARCTIC STRATOSPHERE; PHYSICAL-CHEMISTRY; OZONE HOLE; SYSTEM; WINTER AB Results of laboratory simulations of the growth of nitric acid trihydrate, HNO3 . 3H(2)O, on sulfuric acid tetrahydrate, H2SO4 . 4H(2)O, are presented. The observations reveal that under typical stratospheric conditions uptake of HNO3 on H2SO4 . 4H(2)O substrate results in a surface coverage of approximately one monolayer or less, and that initial HNO3 . 3H(2)O nucleation requires a large supersaturation. We also observe that a H2SO4 . 4H(2)O substrate, onto which a HNO3 . 3H(2)O film has been deposited and subsequently evaporated, exhibits a remarkable enhancement in its nucleation ability for this nitric acid hydrate. In the stratosphere, PSC particles may experience repeated cycles of evaporation and condensation of HNO3 on preexisting background frozen sulfate aerosols. Hence, growth of HNO3 . 3H(2)O on preactivated aerosols provides one important mechanism for polar stratospheric cloud formation and denitrification. C1 MIT, DEPT EARTH ATMOSPHER & PLANETARY SCI, CAMBRIDGE, MA 02139 USA. MIT, DEPT CHEM, CAMBRIDGE, MA 02139 USA. RP Zhang, RY (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Zhang, Renyi/A-2942-2011 NR 26 TC 53 Z9 54 U1 2 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 15 PY 1996 VL 23 IS 13 BP 1669 EP 1672 DI 10.1029/96GL01133 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UT009 UT WOS:A1996UT00900031 ER PT J AU Mazuruk, K Su, CH Sha, YG Lehoczky, SL AF Mazuruk, K Su, CH Sha, YG Lehoczky, SL TI Viscosity of Hg0.84Zn0.16Te pseudobinary melt SO JOURNAL OF APPLIED PHYSICS LA English DT Article AB An oscillating-cup viscometer was developed to measure viscosity of molten HgZnTe ternary semiconductor alloys. Data were collected for the pseudobinary Hg0.84Zn0.16Te melt between 770 and 850 degrees C. The kinematic viscosity was found to vary from approximately 1.1 to 1.4x10(-3) cm(2) s(-1). A slow relaxation phenomena was also observed for temperatures from the melting point of 770 to similar to 800 degrees C. Possible mechanisms for this effect are discussed. (C) 1996 American Institute of Physics. C1 UNIV SPACE RES ASSOC,WASHINGTON,DC. RP Mazuruk, K (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 10 TC 8 Z9 8 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUN 15 PY 1996 VL 79 IS 12 BP 9080 EP 9083 DI 10.1063/1.362580 PG 4 WC Physics, Applied SC Physics GA UT341 UT WOS:A1996UT34100030 ER PT J AU Hendricks, JR Leben, RR Born, GH Koblinsky, CJ AF Hendricks, JR Leben, RR Born, GH Koblinsky, CJ TI Empirical orthogonal function analysis of global TOPEX/POSEIDON altimeter data and implications for detection of global sea level rise SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID GEOSAT ALTIMETRY; ATLANTIC-OCEAN; PACIFIC-OCEAN; VARIABILITY; TEMPERATURE AB Two years of TOPEX/POSEIDON altimeter data are examined to determine the dominant spatial features and timescales of sea surface height variability in the global oceans and to estimate the rate of global sea level rise. Empirical orthogonal function (EOF) decomposition of 69 cycles of TOPEX altimeter data into the significant modes of variability reveals dominant annual and interannual timescales. The annual modes include the hemispheric-scale changes in steric height due to seasonal heating variations, changes in the strength of the major current systems in the equatorial Pacific, and the reversing monsoonal circulation in the Indian Ocean. The interannual modes capture oscillations in the tropical Pacific characteristic of recent El Nino events. A a-year history of the change in mean sea level derived from TOPEX altimeter data reveals a rise of 5.2 mm/yr. By analyzing the contribution of each EOF mode to global mean sea level variations, we find that 82% of the rise in mean sea level is caused by a single interannual mode of variability. Altimeter data spanning only 2 years, however, are insufficient to resolve a complete El Nino-Southern Oscillation (ENSO) cycle which dominates the interannual EOF modes. Thus most of the rise in mean sea level derived from TOPEX altimetry is an artifact of incomplete temporal sampling of interannual variability. When a longer time series of TOPEX altimeter data is obtained and a complete ENSO cycle is observed, a significant reduction in the rate of global mean sea level rise estimated from TOPEX altimetry is expected. Most of the remaining rise in global mean sea level is explained by the annual EOF modes, suggesting a possible connection between sea level rise and changes in the steric component of sea surface height. C1 NASA, GODDARD SPACE FLIGHT CTR, OCEANS & ICE BRANCH, GREENBELT, MD 20771 USA. RP UNIV COLORADO, COLORADO CTR ASTRODYNAM RES, BOX 431, BOULDER, CO 80309 USA. RI Leben, Robert/F-3792-2010 OI Leben, Robert/0000-0003-1067-9515 NR 45 TC 56 Z9 58 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9275 EI 2169-9291 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JUN 15 PY 1996 VL 101 IS C6 BP 14131 EP 14145 DI 10.1029/96JC00922 PG 15 WC Oceanography SC Oceanography GA UR422 UT WOS:A1996UR42200011 ER PT J AU DAmelio, F Fox, RA Wu, LC Daunton, NG AF DAmelio, F Fox, RA Wu, LC Daunton, NG TI Quantitative changes of GABA-immunoreactive cells in the hindlimb representation of the rat somatosensory cortex after 14-day hindlimb unloading by tail suspension SO JOURNAL OF NEUROSCIENCE RESEARCH LA English DT Article DE immunocytochemistry; cerebral cortex; muscle; NIH-image ID GLUTAMIC-ACID DECARBOXYLASE; GABAERGIC NEURONS; MUSCLE AFFERENTS; CEREBRAL-CORTEX; MOTOR; ORGANIZATION; LIMB; CAT AB The present study was aimed at evaluating quantitatively gamma-aminobutyric acid (GABA) immunoreactivity in the hindlimb representation of the rat somatosensory cortex after 14 days of hindlimb unloading by tail suspension. A reduction in the number of GABA-immunoreactive cells with respect to the control animals was observed in layer Va and Vb, GABA-containing terminals were also reduced in the same layers, particularly those terminals surrounding the soma and apical dendrites of pyramidal cells in layer Vb, On the basis of previous morphological and behavioral studies of the neuromuscular system of hindlimb-suspended animals, it is suggested that the unloading due to hindlimb suspension alters afferent signaling and feedback information from intramuscular receptors to the cerebral cortex due to modifications in the reflex organization of hindlimb muscle groups. We propose that the reduction in immunoreactivity of local circuit GABAergic neurons and terminals is an expression of changes in their modulatory activity to compensate for the alterations in the afferent information. (C) 1996 Wiley-Liss, Inc. C1 SAN JOSE STATE UNIV FDN, SAN JOSE, CA USA. SAN JOSE STATE UNIV, SAN JOSE, CA 95192 USA. RP DAmelio, F (reprint author), NASA, AMES RES CTR, MAIL STOP 261-3, MOFFETT FIELD, CA 94035 USA. NR 35 TC 39 Z9 39 U1 0 U2 0 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0360-4012 J9 J NEUROSCI RES JI J. Neurosci. Res. PD JUN 15 PY 1996 VL 44 IS 6 BP 532 EP 539 PG 8 WC Neurosciences SC Neurosciences & Neurology GA UQ503 UT WOS:A1996UQ50300003 PM 8794944 ER PT J AU Jones, JH AF Jones, JH TI Chondrite models for the composition of the Earth's mantle and core SO PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Article; Proceedings Paper CT Discussion Meeting on Developments in High-Pressure, High-Temperature Research and the Study of the Earths Deep Interior CY JAN 25-26, 1995 CL LONDON, ENGLAND SP Royal Soc London ID TERRESTRIAL PLANETS; BULK COMPOSITION; CONSTRAINTS; CONSTITUTION; METEORITES; ORIGIN; RATIO; MOON AB The terrestrial planets of the inner Solar System are believed to be broadly chondritic in composition. Here I suggest that the lithophile element composition of the terrestrial mantle, as approximated by primitive lherzolites having high Al/Si ratios and low Mg/Si ratios, was established by nebular rather than indigenous processes. The implications of this model include: (i) the Mg/Si ratio of the upper mantle is an intrinsic property of the bulk Earth and does not reflect differentiation of a terrestrial magma ocean; (ii) the Moon probably did not form by a giant impact on to the Earth; (iii) refractory lithophile elements should be 2.5-3.0 chondrites in the bulk silicate Earth; and (iv) silicon is not a major constituent of the Earth's core. RP Jones, JH (reprint author), NASA, LYNDON B JOHNSON SPACE CTR, SN4, HOUSTON, TX 77058 USA. NR 50 TC 5 Z9 5 U1 1 U2 2 PU ROYAL SOC PI LONDON PA 6-9 CARLTON HOUSE TERRACE, LONDON SW1Y 5AG, ENGLAND SN 1364-503X J9 PHILOS T R SOC A JI Philos. Trans. R. Soc. A-Math. Phys. Eng. Sci. PD JUN 15 PY 1996 VL 354 IS 1711 BP 1481 EP 1494 DI 10.1098/rsta.1996.0059 PG 14 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UV111 UT WOS:A1996UV11100017 ER PT J AU Williams, JG Newhall, XX Dickey, JO AF Williams, JG Newhall, XX Dickey, JO TI Relativity parameters determined from lunar laser ranging SO PHYSICAL REVIEW D LA English DT Article ID EQUIVALENCE PRINCIPLE; MOON; EARTH; GRAVITY; SYSTEM; VERIFICATION; VARIABILITY; PRECESSION; EPHEMERIS; MASSES AB Analysis of 24 years of lunar laser ranging data is used to test the principle of equivalence, geodetic precession, the PPN parameters beta and gamma, and G over dot/G. Recent data can be fitted with a rms scatter of 3 cm. (a) Using the Nordtvedt effect to test the principle of equivalence, it is found that the Moon and Earth accelerate alike in the Sun's field. The relative accelerations match to within 5x10(-13). This limit, combined with an independent determination of gamma from planetary time delay, gives beta. Including the uncertainty due to compositional differences, the parameter beta differs from unity by no more than 0.0014; and, if the weak equivalence principle is satisfied, the difference is no more than 0.0006. (b) Geodetic precession matches its expected 19.2 marc sec/yr rate within 0.7%. This corresponds to a 1% test of gamma. (c) Apart from the Nordtvedt effect, beta and gamma can be tested from their influence on the lunar orbit. It is argued theoretically that the linear combination 0.8 beta+1.4 gamma can be tested at the 1% level of accuracy. For solutions using numerically derived partial derivatives, higher sensitivity is found. Both beta and gamma match the values of general relativity to within 0.005, and the linear combination beta+gamma matches to within 0.003, but caution is advised due to the lack of theoretical understanding of these sensitivities. (d) No evidence for a changing gravitational constant is found, with \G over dot/G\less than or equal to 8X10(-12)/yr. There is significant sensitivity to G over dot/G through solar perturbations on the lunar orbit. RP Williams, JG (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 65 TC 250 Z9 253 U1 1 U2 6 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD JUN 15 PY 1996 VL 53 IS 12 BP 6730 EP 6739 DI 10.1103/PhysRevD.53.6730 PG 10 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA UT168 UT WOS:A1996UT16800005 ER PT J AU Turner, MS White, M AF Turner, MS White, M TI Dependence of inflationary reconstruction upon cosmological parameters SO PHYSICAL REVIEW D LA English DT Article ID MICROWAVE BACKGROUND ANISOTROPY; COLD DARK-MATTER; TENSOR PERTURBATIONS; UNIVERSE; CONSTANT; MODELS; RADIATION; SCALE AB The inflationary potential and its derivatives determine the spectrum of scalar and tensor metric perturbations that arise from quantum fluctuations during inflation, The CBR anisotropy offers a promising means of determining the spectra of metric perturbations and thereby a means of constraining the inflationary potential. The relation between the metric perturbations and CBR anisotropy depends upon cosmological parameters-most notably the possibility of a cosmological constant. Motivated by some observational evidence for a cosmological constant (large-scale structure, cluster-baryon fraction, measurements of the Hubble constant, and age of the Universe) we derive the reconstruction equations and consistency relation to second order in the presence of a cosmological constant. We also clarify previous notation and discuss alternative schemes for reconstruction. C1 UNIV CHICAGO, ENRICO FERMI INST, DEPT ASTRON & ASTROPHYS, CHICAGO, IL 60637 USA. UNIV CHICAGO, ENRICO FERMI INST, DEPT PHYS, CHICAGO, IL 60637 USA. RP FERMILAB NATL ACCELERATOR LAB, NASA, FERMILAB ASTROPHYS CTR, BATAVIA, IL 60510 USA. RI White, Martin/I-3880-2015 OI White, Martin/0000-0001-9912-5070 NR 46 TC 54 Z9 54 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2470-0010 EI 2470-0029 J9 PHYS REV D JI Phys. Rev. D PD JUN 15 PY 1996 VL 53 IS 12 BP 6822 EP 6828 DI 10.1103/PhysRevD.53.6822 PG 7 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA UT168 UT WOS:A1996UT16800014 ER PT J AU Kanik, I Ajello, JM James, GK AF Kanik, I Ajello, JM James, GK TI Electron-impact-induced emission cross sections of neon in the extreme ultraviolet SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID OSCILLATOR-STRENGTHS; VACUUM ULTRAVIOLET; EXCITATION; IONIZATION; RESOLUTION; HELIUM; GASES; ATOMS AB We have measured the extreme ultraviolet (EW) spectrum of neon produced by electron impact excitation. The measurements were obtained under optically thin conditions, and at a spectral resolution of 0.5 nm full width at half maximum (FWHM). The most prominent features of the EUV spectrum between 45-80 nm are the resonance lines of Ne I at 73.6 and 74.4 nm and a multiplet of Ne II at 46.14 nm (the average value for the line centre of the two closely spaced ion lines at 46.07 and 46.22 nm). Absolute emission cross sections of these lines at 300 eV were measured and compared to other previous measurements. The measured emission cross section values at 300 eV for the Ne I lines at 73.6 and 74.4 nm are found to be 5.32 x 10(-18) cm(2) and 1.21 x 10(-18) cm(2) respectively, and for the Ne II multiplet at 46.14 nm is found to be 1.53 x 10(-18) cm(2) (sum of the 46.07 and 46.22 run line cross sections) with an uncertainty of 41%. In addition, excitation functions were measured for the Ne I resonance lines (0-400 eV) and Ne II ion line (0-1 keV). The excitation functions for the Ne I resonance lines were corrected for polarization because these are strongly polarized. RP Kanik, I (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 33 TC 16 Z9 16 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD JUN 14 PY 1996 VL 29 IS 11 BP 2355 EP 2366 DI 10.1088/0953-4075/29/11/023 PG 12 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA UQ636 UT WOS:A1996UQ63600023 ER PT J AU Andrews, L Chertihin, GV Thompson, CA Dillon, J Byrne, S Bauschlicher, CW AF Andrews, L Chertihin, GV Thompson, CA Dillon, J Byrne, S Bauschlicher, CW TI Infrared spectra and quantum chemical calculations of group 2 MO(2), O(2)MO(2), and related molecules SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID GAUSSIAN-BASIS SETS; MATRIX REACTIONS; ELECTRON CORRELATION; OXYGEN MOLECULES; METAL OZONIDE; ATOMS; ARGON; 1ST-ROW; ALKALI; IONS AB Laser-ablated group 2 metal atoms have been reacted with O-2 in condensing N-2 to complement earlier Ar studies owing to different relaxation dynamics of N-2 and Ar with respect to excited metal atoms and ionic product molecules. In the case of Ca + O-2, the reaction in condensing Ar gives primarily the B-3(2) Open bent OCaO dioxide product, but the reaction in condensing N-2 favors the (1)A(1) cyclic CaO2 peroxide species. Three fundamentals are observed with O-18 and Ca-44 substitution for CaO2, and isotopic frequencies are in excellent agreement with the predictions of quantum chemical calculations. Although DFT/B3LYP frequencies are slightly higher than MP2 and CASSCF values, a similar pattern is calculated. Ionic molecules interact more strongly with a nitrogen matrix than with argon, and calculations of N(2)MO(x) and ArMO(x) molecules can be used to explain matrix shifts. Several N(2)MO(2) species are formed spontaneously from MO(2) molecules in solid nitrogen, and a match is found for observed matrix and DFT calculated isotopic frequencies. By comparison, the new molecule ArBeO2 is identified in earlier argon matrix experiments. The new metal disuperoxide molecules, O(2)MO(2), are also identified here. Calcium disuperoxide, O2CaO2, is characterized as a D-2d species with +1.12 charge on Ca and -0.28 on each O, in contrast to calcium peroxide, CaO2, a C-2v molecule with +1.05 charge on Ca and -0.525 on each oxygen atom. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP Andrews, L (reprint author), UNIV VIRGINIA, DEPT CHEM, MCCORMICK RD, CHARLOTTESVILLE, VA 22901 USA. NR 40 TC 47 Z9 47 U1 0 U2 11 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD JUN 13 PY 1996 VL 100 IS 24 BP 10088 EP 10099 DI 10.1021/jp953763v PG 12 WC Chemistry, Physical SC Chemistry GA UQ844 UT WOS:A1996UQ84400014 ER PT J AU Nickolaisen, SL Sander, SP Friedl, RR AF Nickolaisen, SL Sander, SP Friedl, RR TI Pressure-dependent yields and product branching ratios in the broadband photolysis of chlorine nitrate SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID CLO; KINETICS; OZONE AB The photolysis of chlorine nitrate was studied using broadband flash photolysis coupled with long-path ultraviolet-visible absorption spectroscopy. Branching ratios for the Cl + NO3 and ClO + NO2 product channels were determined from time-dependent measurements of ClO and NO3 concentrations. Yields of the ClO and NO3 products displayed a dependence on the bath gas density and the spectral distribution of the photolysis pulse. Product yields decreased with increasing bath gas density regardless of the spectral distribution of the photolysis pulse; however, the decrease in product yield was much more pronounced when photolysis was limited to longer wavelengths. For photolysis in a quartz cell (lambda > 200 nm) the yield decreased by a factor of 2 over the pressure 10-100 Torr. In a Pyrex cell (lambda > 300 nm), the yield decreased by a factor of 50 over the same pressure range. When photolysis was limited to lambda > 350 nm, the yield decreased by a factor of 250. Branching ratios for the photolysis channels [ClONO2 + hv --> ClO + NO2 (1a) and ClONO2 + hv --> Cl + NO3 (1b)] were determined from the relative ClO and NO3 product yields at various pressures. Although the absolute product yield displayed a pressure dependence, the branching between the two channel was independent of pressure. The relative branching ratios (assuming negligible contributions from other channels) are 0.61 +/- 0.20 for channel 1a and 0.39 +/- 0.20 for channel 1b for photolysis with lambda > 200 nm and 0.44 +/- 0.08 for channel 1a and 0.56 +/- 0.08 for channel 1b for photolysis with lambda > 300 nm. The implications of these results for the chemistry of the lower stratosphere are discussed. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CALIF STATE UNIV LOS ANGELES,DEPT CHEM & BIOCHEM,LOS ANGELES,CA 90032. NR 30 TC 9 Z9 9 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD JUN 13 PY 1996 VL 100 IS 24 BP 10165 EP 10178 DI 10.1021/jp953612s PG 14 WC Chemistry, Physical SC Chemistry GA UQ844 UT WOS:A1996UQ84400025 ER PT J AU Prather, M Midgley, P Rowland, FS Stolarski, R AF Prather, M Midgley, P Rowland, FS Stolarski, R TI The ozone layer: The road not taken SO NATURE LA English DT Editorial Material ID ANTARCTIC OZONE; CHLORINE; DESTRUCTION; SINK C1 UNIV CALIF IRVINE,DEPT CHEM,IRVINE,CA 92717. AFEAS,D-70771 LEINFELDEN MUSBER,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Prather, M (reprint author), UNIV CALIF IRVINE,DEPT EARTH SYST SCI,IRVINE,CA 92717, USA. RI Stolarski, Richard/B-8499-2013 OI Stolarski, Richard/0000-0001-8722-4012 NR 14 TC 37 Z9 37 U1 0 U2 1 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD JUN 13 PY 1996 VL 381 IS 6583 BP 551 EP 554 DI 10.1038/381551a0 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UQ657 UT WOS:A1996UQ65700018 ER PT J AU Kaspi, VM Bailes, M Manchester, RN Stappers, BW Bell, JF AF Kaspi, VM Bailes, M Manchester, RN Stappers, BW Bell, JF TI Evidence from a processing pulsar orbit for a neutron-star birth kick SO NATURE LA English DT Article ID RADIO PULSARS; RELATIVISTIC GRAVITY; BINARY PULSAR; PSR 1913+16; CONSTRAINTS; SPIN AB BIRTH 'kicks' to neutron stars, resulting from asymmetric supernova explosions, have been proposed to explain the high velocities of pulsars(1,2), the existence of companionless, high-velocity massive stars(3,4), and a putative Galactic halo of neutron stars(5). The kick hypothesis has been controversial, because most of the evidence for kicks is indirect, and a physical mechanism to produce asymmetric explosions is as yet unknown(6). Here we report five years of radio observations of the pulsar PSR J0045 - 7319, which is in an eccentric orbit around a B star(7). The data show significant deviations from a simple keplerian orbit, which we interpret as arising from advance of the pulsar's periastron and spin-orbiting coupling(8). Both effects arise because of the B star's rotationally induced equatorial bulge, however spin-orbit coupling requires the B star's spin axis to be inclined with respect to the orbital angular momentum vector; we find that the inclination angle is between 25 and 41 degrees. In the likely event that the angular momenta were aligned before the supernova explosion, this misalignment provides direct evidence that the neutron star received a kick at birth. C1 CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. UNIV MELBOURNE,SCH PHYS,PARKVILLE,VIC 3052,AUSTRALIA. ANU,MT STROMLO & SIDING SPRING OBSERV,WESTON,ACT 2611,AUSTRALIA. UNIV MANCHESTER,NUFFIELD RADIO ASTRON LABS,JODRELL BANK,MACCLESFIELD SK11 9DL,CHESHIRE,ENGLAND. RP Kaspi, VM (reprint author), CALTECH,JET PROP LAB,IPAC,770 S WILSON AVE,PASADENA,CA 91125, USA. NR 29 TC 90 Z9 90 U1 0 U2 4 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD JUN 13 PY 1996 VL 381 IS 6583 BP 584 EP 586 DI 10.1038/381584a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UQ657 UT WOS:A1996UQ65700043 ER PT J AU Ray, RD Eanes, RJ Chao, BF AF Ray, RD Eanes, RJ Chao, BF TI Detection of tidal dissipation in the solid Earth by satellite tracking and altimetry SO NATURE LA English DT Article ID ENERGY-BALANCE; OCEAN TIDE AB THE rate at which tidal energy is dissipated in the solid Earth can constrain the anelastic properties of the Earth at frequencies much lower than those accessible with seismology. The dissipative properties of a system are usually expressed as a 'quality factor', Q; estimates(1-7) of the semi-diurnal solid-Earth Q range from 90 to 500. But observational constraints on this quantity are difficult to obtain, because dissipation by the body tide is masked by the much greater dissipation that occurs in the oceans(8,9). Here we show that recent accurate measurements of the ocean tide obtained by the Topex/Poseidon satellite altimeter(10), combined with nearly two decades of laser tracking of satellite orbit perturbations(11) (which are sensitive to the total planetary dissipation rate), permit an estimate of the solid-Earth dissipation rate at semi-diurnal period. We find that the body tide lags the principal lunar tidal potential by 0.16 +/- 0.09 degrees, implying a dissipation rate of 83 +/- 45 gigawatts and a solid-Earth Q of 370 at a period of 12.4 hours. The observed lag agrees well with Zschau's 'most probable' lag' of 0.21 degrees (deduced from observations of the Chandler wobble), and favours the higher values of Q estimated theoretically. C1 UNIV TEXAS,SPACE RES CTR,AUSTIN,TX 78712. RP Ray, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HSTX,CODE 926,GREENBELT,MD 20771, USA. RI Ray, Richard/D-1034-2012; Chao, Benjamin Fong/N-6156-2013 NR 32 TC 30 Z9 32 U1 0 U2 4 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD JUN 13 PY 1996 VL 381 IS 6583 BP 595 EP 597 DI 10.1038/381595a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UQ657 UT WOS:A1996UQ65700047 ER PT J AU Surpi, GC Harari, DD Frieman, JA AF Surpi, GC Harari, DD Frieman, JA TI Large-scale structure and the determination of H-O from gravitational lens time delays SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology, theory; distance scale; gravitational lensing; large-scale structure of universe ID DOUBLE QUASAR 0957+561; FERMAT PRINCIPLE; HUBBLE CONSTANT AB We analyze the effects of large-scale inhomogeneities upon the observables of a gravitational lens system, focusing on the issue of whether large-scale structure imperils the program to determine the Hubble parameter through measurements of time delays between multiple images in lens systems. We find that the lens equation in a spatially flat Robertson-Walker cosmology with scalar metric fluctuations is equivalent, to the leading order of approximation, to that for the same lensing system in the absence of fluctuations but with a different angular position of the source relative to the lens axis. Since the absolute position of the source is not observable, gravitational lens measurements cannot directly reveal the presence of large-scale structure. Large-scale perturbations do not modify the functional relationship between observable lens parameters and the Hubble parameter and therefore do not seriously affect the determination of H-0 from lens time delays. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP Surpi, GC (reprint author), UNIV BUENOS AIRES,FAC CIENCIAS EXACTAS & NAT,DEPT FIS,CIUDAD UNIV,PAB 1,RA-1428 BUENOS AIRES,DF,ARGENTINA. NR 24 TC 4 Z9 4 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP 54 EP 59 DI 10.1086/177299 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN840 UT WOS:A1996UN84000006 ER PT J AU Wang, Y Turner, EL AF Wang, Y Turner, EL TI Statistics of extreme gravitational lensing events .1. The zero shear case SO ASTROPHYSICAL JOURNAL LA English DT Article DE gravitational lensing ID STAR DISTURBANCES; FLUX VARIATIONS; GALAXIES; AMPLIFICATION; QUASARS; ORIGIN; LENSES AB For a given source and lens pair, there is a thin on-axis tubelike volume behind the lens in which the radiation flux from the source is greatly increased due to gravitational lensing. Any objects (such as dust grains) that pass through such a thin tube will experience strong bursts of radiation, i.e., extreme gravitational lensing events (EGLEs). We study the physics and statistics of EGLEs for the case in which finite source size is more important than shear. One of the several possible significant astrophysical effects is investigated with an illustrative calculation. C1 PRINCETON UNIV OBSERV,PRINCETON,NJ 08544. RP Wang, Y (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510, USA. RI Wang, Yun/B-5724-2011; Turner, Edwin/A-4295-2011 OI Wang, Yun/0000-0002-4749-2984; NR 15 TC 6 Z9 6 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP 114 EP 124 DI 10.1086/177303 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN840 UT WOS:A1996UN84000010 ER PT J AU Nandra, K George, IM Turner, TJ Fukazawa, Y AF Nandra, K George, IM Turner, TJ Fukazawa, Y TI Evidence for a highly ionized iron emission line in the quasar PG 1116+215 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, active; galaxies, nuclei; quasars, individual (PG 1116+215); X-rays, galaxies ID ACTIVE GALACTIC NUCLEI; X-RAY-SPECTRA; ACCRETION DISKS; ULTRAVIOLET EXCESS; COLD MATTER; CONTINUUM; REFLECTION; GALAXIES; AGN AB We present an ASCA spectrum of the radio-quiet quasar PG 1116+215 (z = 0.177), which shows evidence for line emission around the iron K-shell complex in the rest frame of the source. Such emission is common in Seyfert galaxies and is attributed to fluorescence in an accretion disk rotating around a central black hole. Unlike the Seyferts, however, the best-fit energy of the emission line in PG 1116+215 is higher than the 6.4 keV expected of neutral material. This implies that the accretion disk in this source is ionized. This may be expected, as the high ratio of UV/X-ray luminosity of this source indicates that it is radiating at a substantial fraction of the Eddington limit. C1 UNIV SPACE RES ASSOC,WASHINGTON,DC. UNIV TOKYO,DEPT PHYS,BUNKYO KU,TOKYO 113,JAPAN. RP Nandra, K (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 660,GREENBELT,MD 20771, USA. NR 45 TC 27 Z9 27 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP 165 EP 169 DI 10.1086/177308 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN840 UT WOS:A1996UN84000015 ER PT J AU Tingay, SJ Edwards, PG Costa, ME Lovell, JEJ MCCulloch, PM Jauncey, DL REynolds, JE Tzioumis, AK Migenes, V Gough, R King, EA Jones, DL Preston, RA Murphy, DW MEier, DL vanOmmen, TD StJohn, M Hoard, DW Nicolson, GD Wan, TS Shen, ZQ AF Tingay, SJ Edwards, PG Costa, ME Lovell, JEJ MCCulloch, PM Jauncey, DL REynolds, JE Tzioumis, AK Migenes, V Gough, R King, EA Jones, DL Preston, RA Murphy, DW MEier, DL vanOmmen, TD StJohn, M Hoard, DW Nicolson, GD Wan, TS Shen, ZQ TI VLBI observations of southern EGRET identifications .1. PKS 0208-512, PKS 0521-365, and PKS 0537-441 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, active; galaxies, jets; gamma rays, observations; techniques, interferometric ID RADIO-SOURCES AB We present high-resolution very long baseline interferometry images of three southern radio sources that the Energetic Gamma-Ray Experiment Telescope (EGRET), on board the Compton Gamma Ray Observatory, has identified as greater than 100 MeV gamma-ray sources. These are the first results in a continuing program of VLBI observations of southern EGRET identifications. For two of these sources, PKS 0208-512 (at 4.851 GHz) and PKS 0537-441 (at 4.851 and 8.418 GHz), the images represent first-epoch observations. For the remaining lower redshift object, PKS 0521-365, we present images from three epochs at 4.851 GHz and an image from one further epoch at 8.418 GHz, spanning approximately 1 yr. We discuss the need for further extensive VLBI observations of EGRET-identified radio sources. C1 INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. UNIV TASMANIA,HOBART,TAS 7001,AUSTRALIA. CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. CALTECH,JET PROP LAB,PASADENA,CA 91109. HARTEBEESTHOEK RADIO ASTRON OBSERV,KRUGERSDORP 1740,SOUTH AFRICA. SHANGHAI ASTRON OBSERV,SHANGHAI 200030,PEOPLES R CHINA. RP Tingay, SJ (reprint author), AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,WESTON,ACT 2611,AUSTRALIA. RI Tingay, Steven/B-5271-2013; van Ommen, Tas/B-5020-2012; King, Edward/A-1473-2012; Migenes, Victor/F-3157-2015 OI van Ommen, Tas/0000-0002-2463-1718; King, Edward/0000-0002-6898-2130; Migenes, Victor/0000-0002-7990-2191 NR 40 TC 27 Z9 27 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP 170 EP 176 DI 10.1086/177309 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN840 UT WOS:A1996UN84000016 ER PT J AU Hurley, K Li, P Smette, A Kouveliotou, C Fishman, G Laros, J Cline, T Fenimore, E Klebesadel, R Boer, M Pedersen, H Niel, M Sommer, M AF Hurley, K Li, P Smette, A Kouveliotou, C Fishman, G Laros, J Cline, T Fenimore, E Klebesadel, R Boer, M Pedersen, H Niel, M Sommer, M TI Possible association of a quiescent x-ray source with a gamma-ray burster SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays, bursts; X-rays, stars ID NEUTRON-STAR MODELS; ERROR BOXES; CONSTRAINTS AB We report on the first repeatedly detected statistically significant coincidence (chance probability approximate to 10(-2)-10(-3)) between an X-ray source and a gamma-ray burst error box. We present three ROSAT observations of the field of the gamma-ray burst of 1992 May 1. The first, a 2000 s target of opportunity observation, was carried out 18 days after the burst. A weak X-ray source was identified, but with too few photons to determine its spectral characteristics. The second, a 30 ks PSPC observation, resulted in the detection of 118 net photons over the 0.07-2.4 keV energy range. We find that the spectrum is consistent with thermal bremsstrahlung from a 7 x 10(6) K plasma with about 10(22) cm(-2) H I column density. The unabsorbed flux is similar to 9.4 x 10(-13) ergs cm(-2) s(-1) (corresponding absorbed flux 4.8 x 10(-14) ergs cm(-2) s(-1)). Analysis of the photon arrival times indicates that the source may be variable. Using the H I column density from the spectral fit, we set a lower limit to the source distance of at least several kpc; an extragalactic source cannot be ruled out. If the gamma-ray burst is indeed belated to the X-ray source, its total energy output would have been at least 2 x 10(37) ergs. The third observation, 6200 s with the HRI, defines a source error circle of 6'' radius. We discuss optical observations of this region, and consider various possibilities for the nature of the X-ray source. C1 KAPTEYN LAB,9700 AV GRONINGEN,NETHERLANDS. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV ARIZONA,DEPT PLANETARY SCI,TUCSON,AZ 85721. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. CTR ETUD SPATIALE RAYONNEMENTS,F-31029 TOULOUSE,FRANCE. MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. COPENHAGEN UNIV OBSERV,DK-1350 COPENHAGEN,DENMARK. RP Hurley, K (reprint author), UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720, USA. OI Boer, Michel/0000-0001-9157-4349 NR 38 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP 342 EP & DI 10.1086/177324 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN840 UT WOS:A1996UN84000031 ER PT J AU Corcoran, MF Stevens, IR Pollock, AMT Swank, JH Shore, SN Rawley, GL AF Corcoran, MF Stevens, IR Pollock, AMT Swank, JH Shore, SN Rawley, GL TI X-ray variability in V444 Cygni: Evidence for colliding winds? SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries, eclipsing; shock waves; stars, individual (V444 Cygni); stars, mass loss; X-rays, stars ID O-TYPE STARS; BINARY V444-CYGNI; STELLAR WINDS; MASS-LOSS; EMISSION; EVOLUTION; SYSTEMS; MODEL AB Phase-resolved ROSAT observations of the soft X-ray flux from the W-R + O star binary V444 Cyg confirm the orbital dependence of the flux suggested by Einstein IPC observations, showing a drop in flux around primary eclipse, when the W-R star is in front of the O star. The observed X-ray variability can be modeled as a wind eclipse of an X-ray source by the Wolf-Rayet wind. If most of the X-rays from the system are produced in a region of shock-heated gas formed by the wind collision between the two stars, then the shocked gas has a large physical extent (r similar to 140R(WR)) if the observed variability is produced solely by the eclipse of the region by the W-R wind. However, since the O star makes a significant contribution to the total X-ray flux from the system, the actual size of the shocked interaction region is probably much smaller. We discuss possible origins for the X-ray emission and conclude that it is probable that at least a fraction of the observed X-ray emission comes from the wind collision. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. UNIV BIRMINGHAM,SCH PHYS & SPACE RES,BIRMINGHAM B15 2TT,W MIDLANDS,ENGLAND. COMP & SCI CO LTD,SHEFFIELD S11 7EY,S YORKSHIRE,ENGLAND. INDIANA UNIV,DEPT PHYS & ASTRON,S BEND,IN 46634. APPL RES CORP,LANDOVER,MD 20785. RP Corcoran, MF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. RI Swank, Jean/F-2693-2012 NR 27 TC 18 Z9 18 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP 434 EP 441 DI 10.1086/177334 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN840 UT WOS:A1996UN84000041 ER PT J AU Xie, XF Mumma, MJ AF Xie, XF Mumma, MJ TI Monte Carlo simulation of cometary atmospheres: Application to comet P/Halley at the time of the Giotto spacecraft encounter .1. Isotropic model SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; cometary comae; comets, individual (P/Halley) ID EXPANSION VELOCITY; HYDROGEN COMA; HALLEY; GAS; WATER; OH; PHOTODISSOCIATION; DISSOCIATION; EXCITATION; EQUATIONS AB Isotropic and axisymmetric models of a cometary atmosphere, made up of H2O and its daughter radicals (H, OH, O, and H-2), have been established using the Monte Carlo particle transport method, Physical parameters of the gases considered were computed for an isotropic cometary coma with a gas production rate of 5 x 10(29) molecules s(-1) and heliocentric distances of 0.89 AU, corresponding to comet P/Halley at the Giotto flyby in 1986 March. The simulated velocity profile of water molecules is in good agreement with Giotto Neutral Mass Spectrometer (NMS) measurements over the entire range from the inner coma to the outer coma (800-34,000 km), when realistic semiclassical collision cross sections are used. The successful model for the velocity profile in the outer coma requires the inclusion of rotational cooling of water molecules in this transition region from the optically thick to optically thin. No evidence is found from our simulation for additional heating from the recondensation of icy grains in the inner coma with radial distances larger than 500 km. Our simulation demonstrates that selective photodestruction of slow water molecules in the inner coma contributes significantly to the increase of outflow velocity of parent species at radial distances larger than 20,000 km, at which photochemical heating ceases to be important. The simulation also shows clearly the evolution of velocity distributions for gas particles from being thermal in the inner coma to nonthermal in the outer coma; the critical distance is found to be 6000 km for water molecules (at a gas production rate of 5 x 10(29) molecules s(-1)). Outside the collision-dominated region (r > 10(4) km), hydrogen (H) has three peaks in its velocity distribution, one at 18 km s(-1), a second at 8 km s(-1), and a thermal component peaked at about 1-2 km s(-1), consistent with observational results. We show that a gas production rate of 4.5 x 10(29) molecules s(-1) gives the best fit to the Giotto NMS velocity measurements. RP Xie, XF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 693,GREENBELT,MD 20771, USA. RI mumma, michael/I-2764-2013 NR 51 TC 16 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP 442 EP 456 DI 10.1086/177335 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN840 UT WOS:A1996UN84000042 ER PT J AU Xie, XF Mumma, MJ AF Xie, XF Mumma, MJ TI Monte Carlo simulation of cometary atmospheres: Application to comet P/Halley at the time of the Giotto spacecraft encounter .2. Axisymmetric model SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; cometary comae; comets, individual (P/Halley) ID DUSTY GAS-JET; INNER COMA; EXPANSION VELOCITY; AUSTIN 1989C1; ZINNER 1984E; LEVY 1990C; OH RADIO; P-HALLEY; METHANOL; EMISSION AB An axisymmetric Monte Carlo model of a cometary atmosphere, composed of H2O and its daughter species H and OH, has been established and applied to comet 1P/Halley at the Giotto encounter. Results are presented for comae modeled with two gas density functions, represented by total water production rates Q(0) and water angular distributions f(theta) on the inner boundary (r = 500 km). In case (1), Q(0) = 6 x 10(29) molecules s(-1) and f(theta) = 1 + 0.5 cos theta, and in case (2), Q(0) = 5 x 10(29) molecules s(-1) and f(theta) = 1 + 0.9 cos theta, respectively. Our simulations clearly show that anisotropy of water is maintained at least to a radial distance of 2 x 10(5) km, but that the gas density becomes increasingly isotropic at larger radial distances. For daughter species, changes of angular distribution in the coma also depend on the ejection velocity: H becomes move or less isotropic in the outer coma due to its large ejection velocities, while OH preserves the initial angular distribution to a greater degree during its outward expansion due to a small mean ejection velocity of 1 km s(-1). The flattening of angular distributions leads to a reduced asymmetry in gas column density from the intermediate coma (r similar to a few thousand km from the nucleus) to the outer coma and could be partly responsible for reduced asymmetries seen in observed cometary data. We also show that (a) the outward expansion of H2O, H, and OH is mainly radial, with very small mean lateral velocities throughout the range from the inner boundary (r = 500 km) coma to the outer coma, and (b) the outflow velocities of H2O and OH increase with increasing local gas production rates, while that of H decreases with increasing local production rates. Furthermore, the gas production rate estimated from fitting the Giotto velocity measurements is a local one and does not represent the true total gas production rate. The retrieval of the latter requires information on the lag angle of outgassing and its angular distribution. Applications to trace volatiles (CH3OH, H2S) and to gaseous species having both direct and extended sources (CO, H2CO, CN) are discussed. RP Xie, XF (reprint author), NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, CODE 693, GREENBELT, MD 20771 USA. RI mumma, michael/I-2764-2013 NR 75 TC 34 Z9 34 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP 457 EP 475 DI 10.1086/177336 PN 1 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN840 UT WOS:A1996UN84000043 ER PT J AU Bennett, CL Banday, AJ Gorski, KM Hinshaw, G Jackson, P Keegstra, P Kogut, A Smoot, GF Wilkinson, DT Wright, EL AF Bennett, CL Banday, AJ Gorski, KM Hinshaw, G Jackson, P Keegstra, P Kogut, A Smoot, GF Wilkinson, DT Wright, EL TI Four-year COBE DMR cosmic microwave background observations: Maps and basic results SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology, observations ID RADIOMETER 1ST-YEAR MAPS; EXTRAGALACTIC OBJECTS; STATISTICAL-ANALYSIS; CATALOGS AB In this Letter we present a summary of the spatial properties of the cosmic microwave background radiation based on the full 4 yr of COBE Differential Microwave Radiometer (DMR) observations, with additional details in a set of companion Letters. The anisotropy is consistent with a scale-invariant power-law model and Gaussian statistics. With full use of the multifrequency 4 yr DMR data, including our estimate of the effects of Galactic emission, we find a power-law spectral index of n = 1.2 +/- 0.3 and a quadrupole normalization Q(rms-PS) = 15.31(-2.8)(+3.8) mu K. For n = 1 the best-fit normalization is Q(rms-PS/n=1) = 18 +/- 1.6 mu K. These values are consistent with both our previous 1 yr and 2 yr results. The results include use of the l = 2 quadrupole term; exclusion of this term gives consistent results, but with larger uncertainties. The final DMR 4 yr sky maps, presented in this Letter, portray an accurate overall visual impression of the anisotropy since the signal-to-noise ratio is similar to 2 per 10 degrees sky map patch. The improved signal-to-noise ratio of the 4 yr maps also allows for improvements in Galactic modeling and limits on non-Gaussian statistics. C1 UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,DEPT PHYS,SPACE SCI LAB,BERKELEY,CA 94720. UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90095. RP Bennett, CL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,HUGHES STX CORP,CODE 685,GREENBELT,MD 20771, USA. RI Kogut, Alan/D-6293-2012 NR 26 TC 707 Z9 707 U1 2 U2 12 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP L1 EP & DI 10.1086/310075 PN 2 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN841 UT WOS:A1996UN84100001 ER PT J AU Cavallo, RM Sweigart, AV Bell, RA AF Cavallo, RM Sweigart, AV Bell, RA TI The production of sodium and aluminum in globular cluster red giant stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE globular clusters, general; nuclear reactions, nucleosynthesis, abundances; stars, abundances; stars, late-type; stars, interiors; stars, Population II ID NITROGEN ABUNDANCES; OXYGEN ABUNDANCES; HALO GIANTS; M13; CARBON; ANOMALIES; M3 AB We study the production of Na and Al around the hydrogen shell of two red giant sequences of different metallicity in order to explain the abundance variations seen in globular cluster stars in a mixing scenario. Using detailed stellar models, together with an extensive nuclear reaction network, we have calculated the distribution of the various isotopic abundances around the hydrogen shell at numerous points along the red giant branch. These calculations anew for the variation in both temperature and density in the shell region as well as the timescale of the nuclear processing, as governed by the outward movement of the hydrogen shell. The reaction network uses updated rates over those of Caughlan & Fowler. We find evidence for the production of Na and Al occurring in the NeNa and MgAl cycles. In particular, Na is significantly enhanced throughout the region above the hydrogen shell. The use of the newer reaction rates causes a substantial increase in the production of Al-27 above the hydrogen shell through heavy leakage from the NeNa cycle and should have an important effect on the predicted surface abundances. We also find that the nuclear processing is considerably more extensive at lower metallicities. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP Cavallo, RM (reprint author), UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742, USA. OI Cavallo, Robert/0000-0002-7696-3650 NR 30 TC 66 Z9 66 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP L79 EP L82 DI 10.1086/310089 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN841 UT WOS:A1996UN84100019 ER PT J AU Gorski, KM Banday, AJ Bennett, CL Hinshaw, G Kogut, A Smoot, GF Wright, EL AF Gorski, KM Banday, AJ Bennett, CL Hinshaw, G Kogut, A Smoot, GF Wright, EL TI Power spectrum of primordial inhomogeneity determined from the four-year COBE DMR sky maps SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology, observations; large-scale structure of universe; methods, analytical; methods, statistical ID DIFFERENTIAL MICROWAVE RADIOMETER; COSMIC BACKGROUND-RADIATION AB Fourier analysis and power spectrum estimation of the cosmic microwave background anisotropy on an incompletely sampled sky developed by Gorski has been applied to the 4 yr COBE DMR 31.5, 53, and 90 GHz sky maps. Likelihood analysis using newly constructed Galaxy cuts (extended beyond \b\ = 20 degrees to excise the known foreground emission) and simultaneously correcting for the faint high-latitude Galactic foreground emission is conducted on the DMR sky maps pixelized in both ecliptic and Galactic coordinates. The Bayesian power spectrum estimation from the foreground-corrected 4 yr COBE DMR data renders n similar to 1.2 +/- 0.3 and Q(rms-PS) similar to 15.3(-2.8)(+3.7) mu K (projections of the two-parameter likelihood). The results are consistent with the Harrison-Zeldovich n =1 model of amplitude Q(rms-PS) similar to 18 mu K detected with significance exceeding 14 sigma (delta Q/Q less than or similar to 0.07). (A small power spectrum amplitude drop below the published 2 yr results is predominantly due to the application of the new, extended Galaxy cuts.) C1 MAX PLANCK INST ASTROPHYS,D-85740 GARCHING,GERMANY. UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,DEPT PHYS,BERKELEY,CA 94720. UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90095. RP Gorski, KM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,HUGHES STX CORP,CODE 685,GREENBELT,MD 20771, USA. RI Kogut, Alan/D-6293-2012 NR 16 TC 199 Z9 198 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP L11 EP & DI 10.1086/310077 PN 2 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN841 UT WOS:A1996UN84100003 ER PT J AU Hinshaw, G Banday, AJ Bennett, CL Gorski, KM Kogut, A Lineweaver, CH Smoot, GF Wright, EL AF Hinshaw, G Banday, AJ Bennett, CL Gorski, KM Kogut, A Lineweaver, CH Smoot, GF Wright, EL TI Two-point correlations in the COBE DMR four-year anisotropy maps SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology, observations ID DIFFERENTIAL MICROWAVE RADIOMETER AB The two-point temperature correlation function is evaluated from the 4 yr COBE DMR microwave anisotropy maps. We examine the two-point function, which is the Legendre transform of the angular power spectrum, and show that the data are statistically consistent from channel to channel and frequency to frequency. The most likely quadrupole normalization is computed for a scale-invariant power-law spectrum of CMB anisotropy, using a variety of data combinations. For a given data set, the normalization inferred from the two-point data is consistent with that inferred by other methods. The smallest and largest normalizations deduced from any data combination are 16.4 and 19.6 mu K, respectively, with a value similar to 18 mu K generally preferred. C1 OBSERV STRASBOURG,F-67000 STRASBOURG,FRANCE. UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,DEPT PHYS,SPACE SCI LAB,BERKELEY,CA 94720. UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90095. RP Hinshaw, G (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,HUGHES STX CORP,CODE 685,GREENBELT,MD 20771, USA. RI Kogut, Alan/D-6293-2012 NR 14 TC 101 Z9 101 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP L25 EP L28 DI 10.1086/310076 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN841 UT WOS:A1996UN84100006 ER PT J AU Hinshaw, G Banday, AJ Bennett, CL Gorski, KM Kogut, A Smoot, GF Wright, EL AF Hinshaw, G Banday, AJ Bennett, CL Gorski, KM Kogut, A Smoot, GF Wright, EL TI Band power spectra in the COBE DMR four-year anisotropy maps SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology, observations AB We employ a pixel-based likelihood technique to estimate the angular power spectrum of the COBE Differential Microwave Radiometer (DMR) 4 yr sky maps. The spectrum is consistent with a scale-invariant power-law form with a normalization, expressed in terms of the expected quadrupole anisotropy, of Q(rms-PS\n=1) = 18 +/- 1.4 mu K, and a best-fit spectral index of 1.2 +/- 0.3. The normalization is somewhat smaller than we concluded from the 2 yr data, mainly due to additional Galactic modeling. We extend the analysis to investigate the extent to which the ''small'' quadrupole observed in our sky is statistically consistent with a power-law spectrum. The most likely quadrupole amplitude ranges between 7 and 10 mu K, depending on the details of Galactic modeling and data selection, but in no case is there compelling evidence that the quadrupole is inconsistent with a power-law spectrum. We conclude with a likelihood analysis of the band power amplitude in each of four spectral bands between l = 2 and 40, and find no evidence for deviations from a simple power-law spectrum. C1 UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,DEPT PHYS,SPACE SCI LAB,BERKELEY,CA 94720. UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90095. RP Hinshaw, G (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,HUGHES STX CORP,CODE 685,GREENBELT,MD 20771, USA. RI Kogut, Alan/D-6293-2012 NR 19 TC 86 Z9 86 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP L17 EP L20 DI 10.1086/310074 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN841 UT WOS:A1996UN84100004 ER PT J AU Kogut, A Banday, AJ Bennett, CL Gorski, KM Hinshaw, G Smoot, GF Wright, EL AF Kogut, A Banday, AJ Bennett, CL Gorski, KM Hinshaw, G Smoot, GF Wright, EL TI Tests for non-Gaussian statistics in the DMR four-year sky maps SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology, observations; methods, statistical ID FLUCTUATIONS AB We search the high-latitude portion of the COBE Differential Microwave Radiometer (DMR) 4 yr sky maps for evidence of a non-Gaussian temperature distribution in the cosmic microwave background. The genus, three-point correlation function, and two-point correlation function of temperature maxima and minima are all in excellent agreement with the hypothesis that the CMB anisotropy on angular scales of 7 degrees or larger represents a random-phase Gaussian field. A likelihood comparison of the DMR sky maps to a set of random-phase non-Gaussian toy models selects the exact Gaussian model as most likely. Monte Carlo simulations show that the two-point correlation of the peaks and valleys in the maps provides the greatest discrimination among the class of models tested. C1 UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,DEPT PHYS,SPACE SCI LAB,BERKELEY,CA 94720. UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90095. RP Kogut, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,HUGHES STX CORP,CODE 685,GREENBELT,MD 20771, USA. RI Kogut, Alan/D-6293-2012 NR 15 TC 113 Z9 113 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP L29 EP L33 DI 10.1086/310078 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN841 UT WOS:A1996UN84100007 ER PT J AU Kogut, A Hinshaw, G AF Kogut, A Hinshaw, G TI Monte Carlo simulations of medium-scale cosmic microwave background anisotropy SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; nuclear reactions, nucleosynthesis, abundances ID RADIATION ANISOTROPY; STATISTICS AB Recent detections of cosmic microwave background (CMB) anisotropy at half-degree angular scales show considerable scatter in the reported amplitude, even at similar angular resolution. We use Monte Carlo techniques to simulate the current set of medium-scale CMB observations, including all relevant aspects of sky coverage and measurement technique. The scatter in the reported amplitudes is within the range expected for the standard cold dark matter (CDM) cosmological model and results primarily from the restricted sky coverage of each experiment. Within the context of standard CDM, current observations of CMB anisotropy support the detection of an acoustic peak in the CMB power spectrum consistent with baryon density 0.005 < Omega(b) < 0.078 (95% confidence) for Hubble constant H-0 = 50 km s(-1) Mpc(-1). Flat models (Omega(b) = 0) are rejected at more than 5 standard deviations. The uncertainties are approximately evenly divided between instrument noise and sample variance arising from the limited sky coverage. RP Kogut, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,HUGHES STX CORP,CODE 685,GREENBELT,MD 20771, USA. RI Kogut, Alan/D-6293-2012 NR 19 TC 6 Z9 6 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP L39 EP L41 DI 10.1086/310084 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN841 UT WOS:A1996UN84100009 ER PT J AU Kogut, A Banday, AJ Bennett, CL Gorski, KM Hinshaw, G Smoot, GF Wright, EL AF Kogut, A Banday, AJ Bennett, CL Gorski, KM Hinshaw, G Smoot, GF Wright, EL TI Microwave emission at high Galactic latitudes in the four-year DMR sky maps SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology, observations; Galaxy, general; ISM, general ID RADIO-CONTINUUM EMISSION; 408 MHZ; COBE AB We use the COBE(8) Differential Microwave Radiometers (DMR) 4 yr sky maps to model Galactic microwave emission at high latitudes (\b\ > 20 degrees). Cross-correlation of the DMR maps with Galactic template maps detects fluctuations in the high-latitude microwave sky brightness with the angular variation of the DIRBE far-infrared dust maps and a frequency dependence consistent with a superposition of dust and free-free emission. We find no significant correlations between the DMR maps and various synchrotron templates. On the largest angular scales (e.g., quadrupole), Galactic emission is comparable in amplitude to the anisotropy in the cosmic microwave background (CMB). The CMB quadrupole amplitude, after correction for Galactic emission, has amplitude Q(rms) = 10.7 mu K with random uncertainty 3.6 mu K and systematic uncertainty 7.1 mu K from uncertainty in our knowledge of Galactic microwave emission. C1 UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,DEPT PHYS,SPACE SCI LAB,BERKELEY,CA 94720. UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90095. RP Kogut, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,HUGHES STX CORP,CODE 685,GREENBELT,MD 20771, USA. RI Kogut, Alan/D-6293-2012 NR 15 TC 162 Z9 162 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP L5 EP & DI 10.1086/310072 PN 2 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN841 UT WOS:A1996UN84100002 ER PT J AU Woo, R AF Woo, R TI Detection of low-latitude plumes in the outer corona by Ulysses radio ranging measurements SO ASTROPHYSICAL JOURNAL LA English DT Article DE interplanetary medium; solar wind; Sun, corona ID POLAR PLUME AB Low-latitude plumes have been detected beyond the field of view of coronagraphs in the range of 23-42 R(0) in an equatorial coronal hole by Ulysses radio ranging measurements conducted in 1991 at 13 and 3.6 cm wavelengths. Exploiting the ranging measurement features of high sensitivity, wide dynamic range, high precision, high stability, and long duration, the plumes have been identified by the similarity between their transverse path-integrated density profiles and those of polar plumes observed in white-light measurements of the inner corona. Like the polar plumes, the low-latitude plumes are consistent with radial expansion and show a variation in path-integrated density of +/-10%. These results suggest that plumes are a feature common not exclusively to polar coronal holes but to coronal holes in general. RP Woo, R (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MS 238-725,PASADENA,CA 91109, USA. NR 30 TC 17 Z9 17 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP L95 EP L98 DI 10.1086/310086 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN841 UT WOS:A1996UN84100023 ER PT J AU Wright, EL Bennett, CL Gorski, K Hinshaw, G Smoot, GF AF Wright, EL Bennett, CL Gorski, K Hinshaw, G Smoot, GF TI Angular power spectrum of the cosmic microwave background anisotropy seen by the COBE DMR SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology, observations ID INFLATIONARY UNIVERSE; EXTRAGALACTIC OBJECTS; STATISTICAL-ANALYSIS; FLUCTUATIONS; CATALOGS AB The angular power spectrum estimator developed by Peebles and Hauser & Peebles has been modified and applied to the 4 yr maps produced by the COBE DMR. The power spectrum of the observed sky has been compared to the power spectra of a large number of simulated random skies produced with noise equal to the observed noise and primordial density fluctuation power spectra of power-law form, with P(k) proportional to k(n). The best-fitting value of the spectral index in the range of spatial scales corresponding to spherical harmonic indices 3 less than or equal to l less than or similar to 30 is an apparent spectral index n(app) = 1.13(-0.4)(+0.3) which is consistent with the Harrison-Zeldovich primordial spectral index n(pri) = 1. The best-fitting amplitude for n(app) = 1 is [Q(rms)(2)](0.5) = 18 mu K. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,HUGHES STX CORP,GREENBELT,MD 20771. UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,DEPT PHYS,SPACE SCI LAB,BERKELEY,CA 94720. UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. RP Wright, EL (reprint author), UNIV CALIF LOS ANGELES,POB 951562,LOS ANGELES,CA 90095, USA. NR 17 TC 56 Z9 56 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1996 VL 464 IS 1 BP L21 EP L24 DI 10.1086/310073 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN841 UT WOS:A1996UN84100005 ER PT J AU Zaman, KBMQ AF Zaman, KBMQ TI Axis switching and spreading of an asymmetric jet: The role of coherent structure dynamics SO JOURNAL OF FLUID MECHANICS LA English DT Article ID RECTANGULAR TRANSITION DUCT; FLOW; EVOLUTION; ENTRAINMENT; TURBULENCE; EXCITATION AB The effects of vortex generators and periodic excitation on vorticity dynamics and the phenomenon of axis switching in a free asymmetric jet are studied experimentally. Most of the data reported are for a 3 : 1 rectangular jet at a Reynolds number of 450 000 and a Mach number of 0.31. The vortex generators are in the form of 'delta tabs', triangular-shaped protrusions into the flow, placed at the nozzle exit. With suitable placement of the tabs, axis switching could be either stopped or augmented. Two mechanisms are identified governing the phenomenon. One, as described by previous researchers, is due to the difference in induced velocities for different segments of a rolled-up azimuthal vortical structure. The other is due to the induced velocities of streamwise vortex pairs in the flow. While the former mechanism, referred to here as the omega(theta)-dynamics, is responsible for a rapid axis switching in periodically forced jets, e.g. screeching supersonic jets, the effect of the tabs is governed mainly by the latter mechanism, referred to as the omega(x)-dynamics. Both dynamics can be active in a natural asymmetric jet; the tendency for axis switching caused by the omega(theta)-dynamics may be, depending on the streamwise vorticity distribution, either resisted or enhanced by the omega(z)-dynamics. While this simple framework qualitatively explains the various observations made on axis switching, mechanisms actually in play may be much more complex. The two dynamics are not independent as the flow field is replete with both azimuthal and streamwise vortical structures which continually interact. Phase-averaged measurements for a periodically forced case, over a volume of the how field, are carried out in an effort to gain insight into the dynamics of these vortical structures. The results are used to examine such processes as the reorientation of the azimuthal vortices, the resultant evolution of streamwise vortex pairs, as well as the redistribution of streamwise vortices originating from secondary flow within the nozzle. RP Zaman, KBMQ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. RI tian, hongzhou/M-7867-2015 OI tian, hongzhou/0000-0003-1402-3855 NR 35 TC 103 Z9 104 U1 0 U2 8 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JUN 10 PY 1996 VL 316 BP 1 EP 27 DI 10.1017/S0022112096000420 PG 27 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA UV269 UT WOS:A1996UV26900001 ER PT J AU Argus, DF Gordon, RG AF Argus, DF Gordon, RG TI Tests of the rigid-plate hypothesis and bounds on intraplate deformation using geodetic data from very long baseline interferometry SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID RIO-GRANDE RIFT; COLORADO PLATEAU; NORTH-AMERICA; ROTATION; CLOSURE; CIRCUIT; MOTION; ALASKA; POLES; MODEL AB The geodetic results of Ma et al. [1994] from very long baseline interferometry are used to assess rates of intraplate deformation. We analyze the resulting set of velocities of 18 plate-interior sites, nine on the North American plate, four western European sites on the Eurasian plate, three on the Pacific plate, and two on the Australian plate. We formulate three alternative error budgets based partly on the work of Ryan et al. [1993a]: an optimistic error budget, a conservative error budget, and an upper bound error budget. All three budgets assume the existence of a previously unmodeled error that is inversely proportional to the time span of observations at a site. Use of the conservative error budget indicates no significant motion between sites on any one of the four plates. Use of the upper bound error budget, designed to be precisely large enough to be consistent with rigid plates, places a usefully small upper bound on how fast any site might be moving relative to the rest of its plate. Speeds faster than 2 mm/yr are excluded at the 95% confidence level for seven of the 18 plate-interior sites. Adjustments of the site velocities for motion due to postglacial rebound as predicted from the model of Tushingham and Peltier [1991] give an insignificant improvement to the fit of the horizontal velocities to the rigid plate model. The velocities of six sites near the western margin of the interior of the North American plate were also analyzed. Use of the conservative error budget indicates that a site near Fairbanks (Alaska) has an upper bound of 3 mm/yr on its speed, a site in Nome (Alaska) has an upper bound on its speed of similar to 8 mm/yr, and a site in Penticton (British Columbia) has an upper bound on its speed of similar to 4 mm/yr. Of three sites on the Colorado Plateau, two move marginally significantly, and one moves insignificantly relative to stable North America. Upper limits on their speeds relative to stable North America range from 4 to similar to 5 mm/yr. We conclude that the data do not yet demonstrate significant velocities between sites in the stable interior of any one plate but do provide useful and small upper bounds of 2 mm/yr or less on the speeds of the best observed intraplate sites. Six sites near the western margin of the North American interior have upper bound speeds of 3 to 8 mm/yr. C1 RICE UNIV, DEPT GEOL & GEOPHYS, HOUSTON, TX 77251 USA. RP Argus, DF (reprint author), CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RI Argus, Donald/F-7704-2011 NR 35 TC 63 Z9 66 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD JUN 10 PY 1996 VL 101 IS B6 BP 13555 EP 13572 DI 10.1029/95JB03775 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UQ014 UT WOS:A1996UQ01400001 ER PT J AU Visscher, L Dyall, KG AF Visscher, L Dyall, KG TI Relativistic and correlation effects on molecular properties .1. The dihalogens F-2, Cl-2, Br-2, I-2, and At-2 SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID SPIN-ORBIT OPERATORS; GAUSSIAN-BASIS SETS; EFFECTIVE POTENTIALS; XE AB A benchmark study of a number of relativistic correlation methods is presented. Bond lengths, harmonic frequencies, and dissociation energies of the molecules F-2, Cl-2, Br-2, I-2, and At-2 are calculated at various levels of theory, using both the Schrodinger and the Dirac-Coulomb-(Gaunt) Hamiltonian. (C) 1996 American Institute of Physics. C1 UNIV GRONINGEN,CTR MAT SCI,9747 AG GRONINGEN,NETHERLANDS. NASA,AMES RES CTR,THERMOSCI INST,MOFFETT FIELD,CA 94035. RP Visscher, L (reprint author), UNIV GRONINGEN,PHYS CHEM LAB,NIJENBORGH 4,9747 AG GRONINGEN,NETHERLANDS. RI Visscher, Lucas/A-3523-2010 OI Visscher, Lucas/0000-0002-7748-6243 NR 28 TC 126 Z9 126 U1 0 U2 15 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUN 8 PY 1996 VL 104 IS 22 BP 9040 EP 9046 DI 10.1063/1.471636 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA UP202 UT WOS:A1996UP20200020 ER PT J AU Pradhan, AD Partridge, H AF Pradhan, AD Partridge, H TI Theoretical study of the B(3)Sigma(u)(-)-X(3)Sigma(g)(-) and B''(3)Pi(u)-X(3)Sigma(g)(-) band systems of S-2 SO CHEMICAL PHYSICS LETTERS LA English DT Article ID S2; FLUORESCENCE; LIFETIMES AB Multireference configuration-interaction (MRCI) wavefunctions and potential energy curves have been calculated for the X(3) Sigma(g)(-), and B-3 Sigma(u)(-), and B ''(3) Pi(u) states of S-2 using correlation consistent Gaussian basis sets. These wavefunctions are utilized to compute the transition dipole moments of the B-3 Sigma(u)(-)-X(3) Sigma(g)(-) and B ''(3) Pi(u)-X(3) Sigma(g)(-) systems. Oscillator strengths, transition probabilities, and radiative lifetimes are computed for the B-X and B ''-X systems and comparison is made with experimental data. RP Pradhan, AD (reprint author), NASA,AMES RES CTR,COMPUTAT CHEM BRANCH,MS 230-3,MOFFETT FIELD,CA 94035, USA. NR 28 TC 17 Z9 19 U1 1 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JUN 7 PY 1996 VL 255 IS 1-3 BP 163 EP 170 DI 10.1016/0009-2614(96)00363-6 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA UQ975 UT WOS:A1996UQ97500028 ER PT J AU Strelnitski, V Haas, MR Smith, HA Erickson, EF Colgan, SWJ Hollenbach, DJ AF Strelnitski, V Haas, MR Smith, HA Erickson, EF Colgan, SWJ Hollenbach, DJ TI Far-infrared hydrogen lasers in the peculiar star MWC 349A SO SCIENCE LA English DT Article ID RECOMBINATION LINE MASER; MWC-349 AB Far-infrared hydrogen recombination lines H15 alpha (169.4 micrometers), H12 alpha (88.8 micrometers), and H10 alpha (52.5 micrometers) were detected in the peculiar luminous star MWC 349A from the Kuiper Airborne Observatory. Here it is shown that at least H15 alpha is strongly amplified, with the probable amplification factor being greater than or about equal to 10(3) and a brightness temperature that is greater than or about equal to 10(7) kelvin. The other two lines also show signs of amplification, although to a lesser degree. Beyond H10 alpha the amplification apparently vanishes. The newly detected amplified lines fall into the laser wavelength domain. These lasers, as well as the previously detected hydrogen masers, may originate in the photoionized circumstellar disk of MWC 349A and constrain the disk's physics and structure. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SEARCH EXTRATERR INTELLIGENCE INST,MT VIEW,CA 94043. RP Strelnitski, V (reprint author), SMITHSONIAN INST,NATL AIR & SPACE MUSEUM,ASTROPHYS LAB,WASHINGTON,DC 20560, USA. RI Colgan, Sean/M-4742-2014 NR 41 TC 37 Z9 37 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD JUN 7 PY 1996 VL 272 IS 5267 BP 1459 EP 1461 DI 10.1126/science.272.5267.1459 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UP899 UT WOS:A1996UP89900040 PM 8633236 ER PT J AU Smith, GD Jaffe, RL AF Smith, GD Jaffe, RL TI Comparative study of force fields for benzene SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID MOLECULAR-DYNAMICS SIMULATION; LIQUID BENZENE; CRYSTAL-STRUCTURES; CONDENSED PHASES; MODEL; DIMER AB We have examined the ability of several atomic force fields of different forms to reproduce the structure and binding energy of benzene dimer as determined from quantum chemistry calculations, the experimental gasphase second virial coefficient of benzene, and thermodynamic and structural properties of liquid benzene. The force fields investigated were a united atom Lennard-Jones potential, a united atom Lennard-Jones potential with a point quadrupole, an anisotropic united atom model, and explicit (all) atom force fields with partial atomic charges and without partial atomic charges. These force fields which do not include electrostatic interactions predicted the planar sandwich structure (D-6h) to be the most stable dimer structure, in contrast to quantum chemistry calculations that indicate that the planar sandwich structure is a saddle point between stable parallel displaced (C-2h) geometries. Only the explicit atom + partial charge model predicted benzene dimer structures and energies that are in qualitative agreement with those from quantum chemistry calculations. A force field of this form for benzene is presented that accurately reproduces the gas-phase second virial coefficient of benzene and the thermodynamic properties of liquid benzene and does a reasonable job in reproducing the structure of liquid benzene and properties of benzene dimer as determined from quantum chemistry calculations. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Smith, GD (reprint author), UNIV MISSOURI,DEPT CHEM ENGN,COLUMBIA,MO 65211, USA. NR 24 TC 67 Z9 68 U1 0 U2 14 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD JUN 6 PY 1996 VL 100 IS 23 BP 9624 EP 9630 DI 10.1021/jp9535194 PG 7 WC Chemistry, Physical SC Chemistry GA UP706 UT WOS:A1996UP70600012 ER PT J AU Reddy, KSN Salvati, LM Dutta, PK Abel, PB Suh, KI Ansari, RR AF Reddy, KSN Salvati, LM Dutta, PK Abel, PB Suh, KI Ansari, RR TI Reverse micelle based growth of zincophosphate sodalite: Examination of crystal growth SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID IN-OIL MICROEMULSIONS; TEMPERATURE SYNTHESIS; SOLUBILIZED WATER; W/O MICROEMULSION; MICRO-EMULSIONS; ZEOLITE; PARTICLES; EXCHANGE; PH; SULFOSUCCINATE AB Formation of zincophosphates from zinc and phosphate containing reverse micelles (water droplets in hexane) has been examined. The frameworks formed resemble those made by conventional hydrothermal synthesis. Dynamics of crystal growth are however quite different and form the main focus of this study. In particular, the formation of zincophosphate with the sodalite framework was examined in detail. The intramicellar pH was found to have a strong influence on crystal growth. Crystals with a cubic morphology were formed directly from the micelles, without an apparent intermediate amorphous phase over a period of 4 days by a layer-by-layer growth at the intramicellar pH of 7.6. At a pH of 6.8, an amorphous precipitate rapidly sediments in hours. Sodalite was eventually formed from this settled phase via surface diffusion and reconstruction within 4 days. With a rotating cell, it was possible to minimize sedimentation and crystals were found to grow epitaxially from the spherical, amorphous particles. Intermediate pH's of 7.2 led to formation of aggregated sodalite crystals prior to settling, again without any indication of an intermediate amorphous phase. These diverse pathways were possible due to changes in intramicellar supersaturation conditions by minor changes in pH. In contrast, conventional syntheses in this pH range all proceeded by similar crystallization pathways through an amorphous gel. This study establishes that synthesis of microporous frameworks is not only possible in reverse micellar systems, but they also allow examination of possible crystallization pathways. C1 OHIO STATE UNIV,DEPT CHEM,COLUMBUS,OH 43210. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 67 TC 22 Z9 22 U1 0 U2 14 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD JUN 6 PY 1996 VL 100 IS 23 BP 9870 EP 9880 DI 10.1021/jp9600367 PG 11 WC Chemistry, Physical SC Chemistry GA UP706 UT WOS:A1996UP70600045 ER PT J AU Chandler, M AF Chandler, M TI Glacial cycles - Trees retreat and ice advances SO NATURE LA English DT Editorial Material RP Chandler, M (reprint author), COLUMBIA UNIV,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD JUN 6 PY 1996 VL 381 IS 6582 BP 477 EP 478 DI 10.1038/381477a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UP435 UT WOS:A1996UP43500034 ER PT J AU Riotto, A Roulet, E AF Riotto, A Roulet, E TI Vacuum decay along supersymmetric flat directions SO PHYSICS LETTERS B LA English DT Article ID FINITE TEMPERATURE; QUARK MASSES; FALSE VACUUM; BREAKING; MODEL; BEHAVIOR; BOUNDS; FATE AB It has been recently realized that within the Minimal Supersymmetric Standard Model, for certain patterns of superpartner masses, consistent with all the present experimental constraints, the scalar potential may develop at some scale Q(0) unbounded color/charge breaking directions involving the sfermion fields, and that these patterns are then excluded unless some new physics is invoked at or below the scale Q(0). We reanalyze this observation and point out that such patterns of superpartner masses at the weak scale are not ruled out when taking into account the probability of decay for the metastable color conserving minimum along these color breaking unbounded directions, It turns out that the color conserving minimum, although metastable, has a lifetime longer than the present age of the Universe and can survive both quantum tunneling and the effects of high temperatures in the early Universe, causing the color/charge breaking effects to be in practice not dangerous. C1 SISSA,ISAS,SCH ADV INT STUDIES,I-34014 TRIESTE,ITALY. RP Riotto, A (reprint author), FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510, USA. NR 25 TC 71 Z9 71 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0370-2693 J9 PHYS LETT B JI Phys. Lett. B PD JUN 6 PY 1996 VL 377 IS 1-3 BP 60 EP 66 DI 10.1016/0370-2693(96)00313-9 PG 7 WC Astronomy & Astrophysics; Physics, Nuclear; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA UT148 UT WOS:A1996UT14800011 ER PT J AU Burke, PJ Schoelkopf, RJ Prober, DE Skalare, A McGrath, WR Bumble, B LeDuc, HG AF Burke, PJ Schoelkopf, RJ Prober, DE Skalare, A McGrath, WR Bumble, B LeDuc, HG TI Length scaling of bandwidth and noise in hot-electron superconducting mixers SO APPLIED PHYSICS LETTERS LA English DT Article AB Mixing experiments have been performed at frequencies from 4 to 20 GHz on Nb thin-film superconducting hot-electron bolometers varying in length from 0.08 to 3 mu m. The intermediate frequency (IF) bandwidth is found to vary as L(-2), with L the bridge length, for devices shorter than root 12 L(e-ph) approximate to 1 mu m, with L(e-ph) the electron-phonon length. The shortest device has an IF bandwidth greater than 6 GHz, the largest reported for a low-T-c superconducting bolometric mixer. The conversion efficiencies range from -5 to -11 dB (single sideband, SSB). For short bridges, the mixer noise temperature is found to be as low as 100 K (double sideband, DSB), with little length dependence. The local oscillator power required is small, approximate to 10 nW. Such mixers are very promising for low-noise THz heterodyne receivers. (C) 1996 American Institute of Physics. C1 CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. RP Burke, PJ (reprint author), YALE UNIV,DEPT APPL PHYS & PHYS,15 PROSPECT ST,NEW HAVEN,CT 06520, USA. RI Schoelkopf, Robert/J-8178-2012; Burke, Peter/F-3308-2010 NR 11 TC 53 Z9 53 U1 1 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUN 3 PY 1996 VL 68 IS 23 BP 3344 EP 3346 DI 10.1063/1.116052 PG 3 WC Physics, Applied SC Physics GA UN635 UT WOS:A1996UN63500045 ER PT J AU Dornheim, MA AF Dornheim, MA TI Mission 77 highlights shuttle maneuverability SO AVIATION WEEK & SPACE TECHNOLOGY LA English DT Article RP Dornheim, MA (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU MCGRAW HILL INC PI NEW YORK PA 1221 AVENUE OF THE AMERICAS, NEW YORK, NY 10020 SN 0005-2175 J9 AVIAT WEEK SPACE TEC JI Aviat. Week Space Technol. PD JUN 3 PY 1996 VL 144 IS 23 BP 91 EP 92 PG 2 WC Engineering, Aerospace SC Engineering GA UP405 UT WOS:A1996UP40500038 ER PT J AU Landis, GA AF Landis, GA TI Dust obscuration of Mars solar arrays SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 45th International Astronautical Congress CY OCT 09-14, 1994 CL JERUSALEM, ISRAEL ID ATMOSPHERE AB The atmosphere of Mars contains a considerable amount of suspended dust. Over a period of time, this dust will settle out of the atmosphere and deposit onto the surfaces of solar arrays, resulting in degradation of performance. This paper attempts to quantify the amount of dust coverage expected and the amount of performance lost, using available data on Martian conditions. Since this amount of dust in the atmosphere varies, the degradation of array performance could be between 1 and 50% over a 30 day mission, and between 22 and 89% over a two-year mission. Sand and dust may also be deposited on a solar array by saltation. Copyright (C) 1996 Elsevier Science Ltd RP Landis, GA (reprint author), NASA,LEWIS RES CTR,OAI,21000 BROOKPK RD,M-S 302-1,CLEVELAND,OH 44135, USA. NR 26 TC 33 Z9 34 U1 0 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUN PY 1996 VL 38 IS 11 BP 885 EP 891 DI 10.1016/S0094-5765(96)00088-4 PG 7 WC Engineering, Aerospace SC Engineering GA WA107 UT WOS:A1996WA10700008 ER PT J AU Benson, J Payton, G AF Benson, J Payton, G TI Conversations with Gary Payton SO AEROSPACE AMERICA LA English DT Editorial Material C1 NASA,OFF SPACE ACCESS & TECHNOL,SPACE TRANSPORTAT DIV,WASHINGTON,DC 20546. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD JUN PY 1996 VL 34 IS 6 BP 14 EP 16 PG 3 WC Engineering, Aerospace SC Engineering GA UQ886 UT WOS:A1996UQ88600006 ER PT J AU Day, RM Bay, M AF Day, RM Bay, M TI XTE: Astronomy with autonomy SO AEROSPACE AMERICA LA English DT Article RP Day, RM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,SPACECRAFT PROGRAMS OFF,ENGN DIRECTORATE,GREENBELT,MD 20771, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD JUN PY 1996 VL 34 IS 6 BP 34 EP 39 PG 6 WC Engineering, Aerospace SC Engineering GA UQ886 UT WOS:A1996UQ88600011 ER PT J AU Fayyad, UM Djorgovski, SG Weir, N AF Fayyad, UM Djorgovski, SG Weir, N TI From digitized images to online catalogs - Data mining a sky survey SO AI MAGAZINE LA English DT Article AB The value of scientific digital-image libraries seldom lies in the pixels of images. For large collections of images, such as those resulting from astronomy sky surveys, the typical useful product is an online database cataloging entries of interest. We focus on the automation of the cataloging effort of a major sky survey and the availability of digital libraries in general. The SKICAT system automates the reduction and analysis of the three terabytes worth of images, expected to contain on the order of 2 billion sky objects. For the primary scientific analysis of these data, it is necessary to detect, measure, and classify every sky object. SKICAT integrates techniques for image processing, classification learning, database management, and visualization. The learning algorithms are trained to classify the detected objects and can classify objects too faint for visual classification with an accuracy level exceeding 90 percent. This accuracy level increases the number of classified objects in the final catalog threefold relative to the best results from digitized photographic sky surveys to date. Hence, learning algorithms played a powerful and enabling role and solved a difficult, scientifically significant problem, enabling the consistent, accurate classification and the ease of access and analysis of an otherwise unfathomable data set. C1 CALTECH,JPL,MACHINE LEARNING SYST GRP,PASADENA,CA 91125. RP Fayyad, UM (reprint author), MICROSOFT RES,REDMOND,CA, USA. NR 32 TC 12 Z9 12 U1 0 U2 1 PU AMER ASSOC ARTIFICIAL INTELL PI MENLO PK PA 445 BURGESS DRIVE, MENLO PK, CA 94025-3496 SN 0738-4602 J9 AI MAG JI AI Mag. PD SUM PY 1996 VL 17 IS 2 BP 51 EP 66 PG 16 WC Computer Science, Artificial Intelligence SC Computer Science GA UT195 UT WOS:A1996UT19500003 ER PT J AU Bayliss, A Maestrello, L McGreevy, JL Fenno, CC AF Bayliss, A Maestrello, L McGreevy, JL Fenno, CC TI Forward motion effects on jet noise, panel vibration, and radiation SO AIAA JOURNAL LA English DT Article ID BOUNDARY-CONDITIONS; LAYER; FLOWS AB A model of the interaction of sound from a spreading subsonic jet with a four-panel assembly is studied numerically in two dimensions. The effect of forward motion of the jet is allowed for by considering a uniform flowfield superimposed on a mean jet exit profile. The jet is initially excited by a pulselike source inserted into the how field. The pulse triggers instabilities associated with the inviscid instability of the jet shear layer. These instabilities generate sound, which in turn serves to excite the panels. The far-field acoustic radiation, the panel response, and the sound radiated from the panels are all computed and compared with computations with a static get. The results demonstrate that for a jet in forward motion there is a reduction in sound in downstream directions and an increase in sound in upstream directions, in agreement with experiments. Furthermore, the panel response and radiation for a jet in forward motion exhibit a downstream attenuation as compared with the static case. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. PHILADELPHIA COLL PHARM & SCI,DEPT MATH & PHYS,PHILADELPHIA,PA 19104. NATL RES COUNCIL,HAMPTON,VA 23681. RP Bayliss, A (reprint author), NORTHWESTERN UNIV,DEPT ENGN SCI & APPL MATH,EVANSTON,IL 60208, USA. RI Bayliss, Alvin/B-7337-2009 NR 32 TC 4 Z9 4 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 1996 VL 34 IS 6 BP 1103 EP 1110 DI 10.2514/3.13199 PG 8 WC Engineering, Aerospace SC Engineering GA UN638 UT WOS:A1996UN63800002 ER PT J AU Lee, HJ Saravanos, DA AF Lee, HJ Saravanos, DA TI Coupled layerwise analysis of thermopiezoelectric composite beams SO AIAA JOURNAL LA English DT Article ID VIBRATION CONTROL; INTELLIGENT STRUCTURES; ACTUATORS; ELEMENT; SENSORS; PLATE AB Previously developed discrete layer mechanics are extended to incorporate thermal effects to account for the complete coupled mechanical, electrical, and thermal response of piezoelectric composite beams, Thermal effects in both the elastic and piezoelectric media are captured at the material level. This unified representation leads to an inherent capability to model both the sensory and active responses of piezoelectric composite beams in thermal environments. Finite element equations are developed and implemented for a beam element with linear shape functions, Results from the current formulation are compared with results from a conventional thermoelastic finite element analysis and classical beam theory. Additional numerical studies demonstrate capabilities of the current formulation to predict the thermal deformation of composite beams, as well as the active compensation of these thermal deformations using piezoelectric structures, The corresponding sensory response and the resultant stress state in the piezoelectric composite beam are also presented. RP Lee, HJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 21 TC 61 Z9 61 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 1996 VL 34 IS 6 BP 1231 EP 1237 DI 10.2514/3.13217 PG 7 WC Engineering, Aerospace SC Engineering GA UN638 UT WOS:A1996UN63800020 ER PT J AU Akapo, SO Dimandja, JMD Matyska, MT Pesek, JJ AF Akapo, SO Dimandja, JMD Matyska, MT Pesek, JJ TI Improvement of gas chromatographic performance of cyelic siloxane bonded phases by incorporation of n-alkyl qroups SO ANALYTICAL CHEMISTRY LA English DT Article ID PERMANENT GASES; LOWER HYDROCARBONS; SOLID ADSORBENTS; INTERMEDIATE; SEPARATION; HYDROSILATION AB Cyclic siloxane-based silica columns of high retention capacity for light hydrocarbons were prepared by incorporation of octyl and octadecyl groups on the siloxane skeleton, Spectroscopic studies revealed the presence of the allyl groups on the silica surface, which results in high surface coverage of the packing materials, The retention characteristics of the columns are significantly higher than those of cyclic siloxane phases due to their high surface coverage and better solute-stationary phase interactions. in agreement with previous data for micropacked columns, the H vs u curves, on passing through the optimum region, remained substantially constant at high linear gas velocities, indicating their usefulness for fast analysis of light hydrocarbons at high now rates without any appreciable loss in column performance. Presumably due to greater availability of the bonded alkyl groups for interactions, a 10-component mixture of C-1-C-4 saturated and unsaturated hydrocarbons was sufficiently separated on the hexamethylcyclotrisiloxane-octadecylsilyl phase compared to the conventional octadecyldimethylsilyl phase, irrespective of the high carbon content of the latter. C1 SAN JOSE STATE UNIV,DEPT CHEM,SAN JOSE,CA 95192. NASA,AMES RES CTR,EXOBIOL BRANCH,MOFFETT FIELD,CA 94035. NR 24 TC 12 Z9 12 U1 1 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0003-2700 J9 ANAL CHEM JI Anal. Chem. PD JUN 1 PY 1996 VL 68 IS 11 BP 1954 EP 1959 DI 10.1021/ac960125f PG 6 WC Chemistry, Analytical SC Chemistry GA UN470 UT WOS:A1996UN47000027 PM 21619105 ER PT J AU Abrams, MC Goldman, A Gunson, MR Rinsland, CP Zander, R AF Abrams, MC Goldman, A Gunson, MR Rinsland, CP Zander, R TI Observations of the infrared solar spectrum from space by the ATMOS experiment SO APPLIED OPTICS LA English DT Article AB The final flight of the Atmospheric Trace Molecule Spectroscopy experiment as part of the Atmospheric Laboratory for Applications and Science (ATLAS-3) Space Shuttle mission in 1994 provided a new opportunity to measure broadband (625-4800 cm(-1), 2.1-16 mu m) infrared solar spectra at an unapodized resolution of 0.01 cm(-1) from space. The majority of the observations were obtained as exoatmospheric, near Sun center, absorption spectra, which were later ratioed to grazing atmospheric measurements to compute the atmospheric transmission of the Earth's atmosphere and analyzed for vertical profiles of minor and trace gases. Relative to the SPACELAB-3 mission that produced 4800 high Sun spectra (which were averaged into four grand average spectral, the ATLAS-3 mission produced some 40,000 high Sun spectra (which have been similarly averaged) with an improvement in signal-to-noise ratio of a factor of 3-4 in the spectral region between 1000 and 4800 cm(-1). A brief description of the spectral calibration and spectral quality is given as well as the location of electronic archives of these spectra. (C) 1996 Optical Society of America C1 UNIV DENVER,DENVER,CO 80208. CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. RP Abrams, MC (reprint author), NASA,LANGLEY RES CTR,SCI APPLICAT INT CORP,HAMPTON,VA 23681, USA. NR 16 TC 22 Z9 23 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUN 1 PY 1996 VL 35 IS 16 BP 2747 EP 2751 DI 10.1364/AO.35.002747 PG 5 WC Optics SC Optics GA UQ482 UT WOS:A1996UQ48200004 PM 21085422 ER PT J AU Abrams, MC Gunson, MR Chang, AY Rinsland, CP Zander, R AF Abrams, MC Gunson, MR Chang, AY Rinsland, CP Zander, R TI Remote sensing of the Earth's atmosphere from space with high-resolution Fourier-transform spectroscopy: Development and methodology of data processing for the Atmospheric Trace Molecule Spectroscopy experiment SO APPLIED OPTICS LA English DT Article ID LOWER STRATOSPHERE; UPPER TROPOSPHERE; MIDDLE AB The methodology of spectroscopic remote sensing with high-resolution Fourier-transform spectra obtained from low Earth orbit by the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment is discussed. During the course of the Atmospheric Laboratory for Applications and Science (ATLAS) shuttle missions (1992-1994) a flexible, yet reproducible, retrieval strategy was developed that culminated in the near-real-time processing of telemetry data into vertical profiles of atmospheric composition during the ATLAS-3 mission. The development, evolution, robustness, and validation of the measurements are presented and assessed with a summary comparison of trace-gas observations within the Antarctic polar vortex in November 1994. (C) 1996 Optical Society of America C1 CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. NR 18 TC 25 Z9 25 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUN 1 PY 1996 VL 35 IS 16 BP 2774 EP 2786 DI 10.1364/AO.35.002774 PG 13 WC Optics SC Optics GA UQ482 UT WOS:A1996UQ48200007 PM 21085425 ER PT J AU Abrams, MC Gunson, MR Lowes, LL Rinsland, CP Zander, R AF Abrams, MC Gunson, MR Lowes, LL Rinsland, CP Zander, R TI Pressure sounding of the middle atmosphere from ATMOS solar occultation measurements of atmospheric CO2 absorption lines SO APPLIED OPTICS LA English DT Article ID MOLECULE SPECTROSCOPY EXPERIMENT; TEMPERATURE PROFILES AB A method for retrieving the atmospheric pressure corresponding to the tangent point of an infrared spectrum recorded in the solar occultation mode is described and applied to measurements made by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier-transform spectrometer. Tangent pressure values are inferred from measurements of isolated CO2 lines with temperature-insensitive strengths by measuring the slant-column CO2 amount and by adjusting the viewing geometry until the calculated column matches the observed column. Tangent pressures are determined with a spectro-scopic precision of 1%-3%, corresponding to a tangent-point height precision of 70-210 m. The total uncertainty is limited primarily by the quality of the spectra and ranges between 4% and 6% (280-420 m) for spectra with signal-to-noise ratios of 300:1 and between 4% and 10% for spectra with signal-to-noise ratios of 100:1. The retrieval of atmospheric pressure increases the accuracy of the retrieved-gas concentrations by minimizing the effect of systematic errors introduced by climatological pressure data, ephemeris parameters, and the uncertainties in instrumental pointing. (C) 1996 Optical Society of America C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. UNIV LIEGE,INST ASTROPHYS,B-4000 COINTE OUGREE,BELGIUM. RP Abrams, MC (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 21 TC 6 Z9 6 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUN 1 PY 1996 VL 35 IS 16 BP 2810 EP 2820 DI 10.1364/AO.35.002810 PG 11 WC Optics SC Optics GA UQ482 UT WOS:A1996UQ48200011 PM 21085429 ER PT J AU Brown, LR Gunson, MR Toth, RA Irion, FW Rinsland, CP Goldman, A AF Brown, LR Gunson, MR Toth, RA Irion, FW Rinsland, CP Goldman, A TI 1995 atmospheric trace molecule spectroscopy (ATMOS) linelist SO APPLIED OPTICS LA English DT Review ID ABSORPTION CROSS-SECTIONS; DIODE-LASER MEASUREMENTS; HETERODYNE FREQUENCY MEASUREMENTS; AIR-BROADENING COEFFICIENTS; HIGH-RESOLUTION SPECTRA; ABSOLUTE ABSORPTION; NITRIC-ACID; ETHANE C2H6; NU-3 BAND; N2-BROADENING COEFFICIENTS AB The Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment uses a Fourier-transform spectrometer on board the Space Shuttle to record infrared solar occultation spectra of the atmosphere at 0.01-cm(-1) resolution. The current version of the molecular spectroscopic database used for the analysis of the data obtained during three Space Shuttle missions between 1992 and 1994 is described. It is an extension of the effort first described by Brown et al. [Appl. Opt. 26, 5154 (1987)] to maintain an up-to-date database for the ATMOS experiment. The three-part ATMOS compilation contains Line parameters of 49 molecular species between 0 and 10000 cm(-1), The main list, with nearly 700,000 entries, is an updated version of the HITRAN 1992 database. The second compilation contains supplemental line parameters, and the third set consists of absorption cross sections to represent the unresolvable features of heavy molecules. The differences between the ATMOS database and other public compilations are discussed. C1 CALTECH,DEPT CHEM ENGN,PASADENA,CA 91125. NASA,LANGLEY RES CTR,CHEM & DYNAM BRANCH,HAMPTON,VA 23665. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. RP Brown, LR (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 116 TC 63 Z9 63 U1 3 U2 10 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUN 1 PY 1996 VL 35 IS 16 BP 2828 EP 2848 DI 10.1364/AO.35.002828 PG 21 WC Optics SC Optics GA UQ482 UT WOS:A1996UQ48200013 PM 21085431 ER PT J AU Winkel, RJ Davis, SP Abrams, MC AF Winkel, RJ Davis, SP Abrams, MC TI Fourier transform spectroscopy of LaS in the infrared SO APPLIED OPTICS LA English DT Article DE Fourier transform spectroscopy; lanthanum sulfide; infrared spectrum AB We recorded the emission spectrum of diatomic lanthanum sulfide on the Los Alamos Fourier transform spectrometer. In the region 7500-16,000 cm(-1), we identified over 120 bands and assigned them to the A (2) Pi(r)-X (2) Sigma(+) and B (2) Sigma(+)-X (2) Sigma(+) transitions. Each of these bands is four headed, (C) 1996 Optical Society of America C1 UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. NASA,LANGLEY RES CTR,SAIC,HAMPTON,VA 23681. RP Winkel, RJ (reprint author), US MIL ACAD,DEPT PHYS,W POINT,NY 10996, USA. NR 6 TC 7 Z9 8 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUN 1 PY 1996 VL 35 IS 16 BP 2874 EP 2878 PG 5 WC Optics SC Optics GA UQ482 UT WOS:A1996UQ48200017 PM 21085435 ER PT J AU Smith, WH Hammer, PD AF Smith, WH Hammer, PD TI Digital array scanned interferometer: Sensors and results SO APPLIED OPTICS LA English DT Article ID SPECTROMETER AB Digital array scanned interferometers (DASI) blend characteristics of a grating spectrometer and a two-beam interferometer for acquisition of hyperspectra. DASI's posses field-widened capabilities that permit very high throughput. Aspects of DASI design, hyperspectra, and data processing methods are presented. In particular, we provide data showing that photon-noise-limited hyperspectra are achievable for DASI data. (C) 1996 Optical Society of America C1 MEDECO INC,NEW MELLE,MO 63365. NASA,AMES RES CTR,DIV EARTH SCI,MOFFETT FIELD,CA 94035. RP Smith, WH (reprint author), WASHINGTON UNIV,DEPT EARTH & PLANETARY SCI,ST LOUIS,MO 63130, USA. NR 12 TC 60 Z9 68 U1 3 U2 6 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUN 1 PY 1996 VL 35 IS 16 BP 2902 EP 2909 DI 10.1364/AO.35.002902 PG 8 WC Optics SC Optics GA UQ482 UT WOS:A1996UQ48200022 PM 21085440 ER PT J AU Jennings, DE AF Jennings, DE TI Folded-beam design for a Martin-Puplett interferometer with substrate polarizers SO APPLIED OPTICS LA English DT Article AB A polarizing interferometer requires a rotation of 45 degrees between the input polarizer and beam-splitter polarizer If substrate polarizers are used, however, the p polarization should be transmitted at both polarizers for highest efficiency. An out-of-plane configuration is presented that satisfies both criteria. RP Jennings, DE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY SYST BRANCH,CODE 693,GREENBELT,MD 20771, USA. RI Jennings, Donald/D-7978-2012 NR 6 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUN 1 PY 1996 VL 35 IS 16 BP 2910 EP 2912 DI 10.1364/AO.35.002910 PG 3 WC Optics SC Optics GA UQ482 UT WOS:A1996UQ48200023 PM 21085441 ER PT J AU Sandford, SP Luck, WS Rohrbach, WW AF Sandford, SP Luck, WS Rohrbach, WW TI Electromechanical linear actuators for Fourier transform spectrometers: A concept for extended range, high-resolution, solid-state actuators SO APPLIED OPTICS LA English DT Article AB A piezoelectric effect device is reported that provides highly controllable, extended linear motion in an easily usable package. Recent advances in materials, materials processing, and piezoelectric mechanics have been synthesized to demonstrate an all-solid-state electromechanical actuator for Fourier transform spectrometer mirror position control. This actuator is inherently linear and is therefore a major improvement in efficiency, size, and mass over motors and lead screws, which require conversion from rotary to linear actuation. Velocity control of 1% has been demonstrated over a range of 0.5 cm at a velocity of 1 cm/s. Scaling to a range of 4 cm and a velocity of 4 cm/s is discussed and currently appears feasible. RP Sandford, SP (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUN 1 PY 1996 VL 35 IS 16 BP 2923 EP 2926 DI 10.1364/AO.35.002923 PG 4 WC Optics SC Optics GA UQ482 UT WOS:A1996UQ48200025 PM 21085443 ER PT J AU Nayak, PP Joskowicz, L AF Nayak, PP Joskowicz, L TI Efficient compositional modeling for generating causal explanations SO ARTIFICIAL INTELLIGENCE LA English DT Article ID BEHAVIOR; CIRCUITS AB Effective problem solving requires building adequate models that embody the simplifications, abstractions, and approximations that parsimoniously describe the relevant system phenomena for the task at hand. Compositional modeling is a framework for constructing adequate device models by composing model fragments selected from a model fragment library. While model selection using compositional modeling has been shown to be intractable, it is tractable when all model fragment approximations are causal approximations. This paper addresses the reasoning and knowledge representation issues that arise in building practical systems for constructing adequate device models that provide parsimonious causal explanations of how a device functions. We make four important contributions. First, we present a representation of class level descriptions of model fragments and their relationships. The representation yields a practical model fragment library organization that facilitates knowledge base construction and supports focused generation of device models. Second, we show how the structural, behavioral, and functional contexts of the device define model adequacy and provide the task focus and additional constraints to guide the search for adequate models. Third, we describe a novel model selection algorithm that incorporates device behavior with order of magnitude reasoning and focuses model selection with component: interaction heuristics. Fourth, we present the results of our implementation that produces adequate models and causal explanations of a variety of electromechanical devices drawn from a library of 20 components and 150 model fragments. C1 HEBREW UNIV JERUSALEM,INST COMP SCI,IL-91904 JERUSALEM,ISRAEL. RP Nayak, PP (reprint author), NASA,AMES RES CTR,RECOM TECHNOL,MS 269-2,MOFFETT FIELD,CA 94035, USA. NR 37 TC 12 Z9 12 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0004-3702 J9 ARTIF INTELL JI Artif. Intell. PD JUN PY 1996 VL 83 IS 2 BP 193 EP 227 DI 10.1016/0004-3702(95)00024-0 PG 35 WC Computer Science, Artificial Intelligence SC Computer Science GA UU508 UT WOS:A1996UU50800001 ER PT J AU Moellenbrock, GA Fujisawa, K Preston, RA Gurvits, LI Dewey, RJ Hirabayashi, H Inoue, M Kameno, S Kawaguchi, M Iwata, T Jauncey, DL Migenes, V Roberts, DH Schilizzi, RT Tingay, SJ AF Moellenbrock, GA Fujisawa, K Preston, RA Gurvits, LI Dewey, RJ Hirabayashi, H Inoue, M Kameno, S Kawaguchi, M Iwata, T Jauncey, DL Migenes, V Roberts, DH Schilizzi, RT Tingay, SJ TI A 22 GHz VLBI survey of 140 compact extragalactic radio sources SO ASTRONOMICAL JOURNAL LA English DT Article ID COMPLETE SAMPLE; MILLIARCSECOND STRUCTURE; FLUX-DENSITY; EARTH ORBIT; 5 GHZ; SPECTRA; MILLIMETER; TELESCOPE; MAPS AB A sample of 140 compact, flat- or inverted-spectrum (alpha>-0.5, S(nu)similar to nu(alpha)) extragalactic radio sources with delta greater than or equal to-40 degrees and total flux density S(nu)greater than or similar to 1 Jy has been observed with VLBI at 22 GHz on baselines of 4,400-10,800 km (3.3-8.0X10(8) lambda) spanning the Pacific Ocean. Structural information on scales as small as similar to 150 mu as, in the form of brightness temperatures or lower limits, has been derived for the 136 sources that were detected. Twenty-one sources show evidence of structure with brightness temperature in the source frame greater than 10(12) K. This survey was motivated by the needs of the Space VLBI missions VSOP and RadioAstron currently being prepared for launch. Among the 84 sources detected on baselines longer than 7.0x10(8) lambda, 32 have fringe amplitudes greater than 1 Jy and 14 show evidence of structure with observed brightness temperature greater than 7.4X10(11) K, the 7 sigma detection threshold for a 1 Jy circular Gaussian source on a 25,000 km baseline between VSOP and a single VLBA antenna at 22 GHz. The data obtained in this ''Pre-Launch Survey'' should prove useful not only for these and future space VLBI missions, but also for statistical studies of active galactic nuclei (AGN) and for planning millimeter-VLBI experiments. Of particular interest is the prominence in the survey results of the 21 AGN that have been detected in gamma-rays by CGRO/EGRET [Thompson et al. ApJS, 101, 259 (1995)]. (C) 1996 American Astronomical Society. C1 INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. CALTECH,JET PROP LAB,PASADENA,CA 91109. JOINT INST VLBI EUROPE,7990 AA DWINGELOO,NETHERLANDS. NOBEYAMA RADIO OBSERV,MINAMI KAWACHI,NAGANO 38413,JAPAN. KASHIMA SPACE CTR,COMMUN RES LAB,KASHIMA,IBARAKI 314,JAPAN. CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. MT STROMLO & SIDING SPRING OBSERV,WESTON,ACT 2611,AUSTRALIA. RP Moellenbrock, GA (reprint author), BRANDEIS UNIV,DEPT PHYS,POB 9110,WALTHAM,MA 02254, USA. RI Tingay, Steven/B-5271-2013; Migenes, Victor/F-3157-2015 OI Migenes, Victor/0000-0002-7990-2191 NR 45 TC 54 Z9 55 U1 1 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 1996 VL 111 IS 6 BP 2174 EP 2186 DI 10.1086/117953 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN631 UT WOS:A1996UN63100005 ER PT J AU Howell, SB DeYoung, JA Mattei, JA Foster, G Szkody, P Cannizzo, JK AF Howell, SB DeYoung, JA Mattei, JA Foster, G Szkody, P Cannizzo, JK TI Superoutburst photometry of AL Comae Berenices SO ASTRONOMICAL JOURNAL LA English DT Article ID SU-URSAE MAJORIS; DWARF NOVA; CATACLYSMIC VARIABLES; WZ-SGE; U-GEM; OUTBURST; SUPERHUMPS; LATITUDE; MODEL; STARS AB Photometric observations obtained during the 1995 April - May superoutburst of the dwarf nova AL Comae Berenices are presented. This star shows rare, large-amplitude outbursts, the last definitely seen in 1975. During the 1995 outburst, as with that of 1961, there was a sharp, two-magnitude temporary minimum in the outburst light curve at about 28 days after maximum light. We offer an explanation for such temporary minima involving the migration of a cooling wave within the accretion disk. V and I band CCD time-series photometry taken throughout the two-month-long event, reveal a complex period structure with two dominant periods, one near 82 min and one near 41 min. Early in the outburst, photometric modulations of 81 and 86 min were seen and are likely to be related to superorbital modulations seen in other large outburst amplitude dwarf novae. Superhumps developed after similar to 10 days and show a quasi-stable, nonphase coherent period of 82.5 min. A low-amplitude 41 min period was present throughout, also appearing not to be phase coherent. We conclude that the two dominant periods seen are of related origin and we list several possible mechanisms for their cause. Previous quiescence observations of AL Com have shown periods near 87 and 41 min. (C) 1996 American Astronomical Society. C1 USN OBSERV,WASHINGTON,DC 20392. AMER ASSOC VARIABLE STAR OBSERVERS,CAMBRIDGE,MA 02138. UNIV WASHINGTON,DEPT ASTRON,SEATTLE,WA 98195. NASA,GODDARD SPACE FLIGHT CTR,LHEA,GREENBELT,MD 20771. RP Howell, SB (reprint author), PLANETARY SCI INST,ASTROPHYS GRP,620 N 6TH AVE,TUCSON,AZ 85705, USA. NR 52 TC 39 Z9 39 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 1996 VL 111 IS 6 BP 2367 EP 2378 DI 10.1086/117970 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN631 UT WOS:A1996UN63100022 ER PT J AU Huang, M Sion, EM Hubeny, I Cheng, FH Szkody, P AF Huang, M Sion, EM Hubeny, I Cheng, FH Szkody, P TI The accretion disk (belt?) during the quiescence of VW Hydri SO ASTRONOMICAL JOURNAL LA English DT Article ID U-GEMINORUM; MODEL AB We considered the contribution of an accretion disk to the UV spectrum of the dwarf nova (DN) VW Hydri during its quiescence, obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST). Our analysis indicates that the UV emitting area of the disk is a ring of width 0.06 R(WD), inclination angle i=60 degrees, rotating with Keplerian velocity on the white dwarf surface of 3350 km/s. The other parameters of the ring are log g=6.0, T-eff=28,000 K, C and Si enhanced to 20 and 15 times their solar abundances, respectively, and the abundance of all other heavy elements having solar values. The disk area outside this UV emitting region has a T-eff much lower than 10,000 K. Our modelling does not rule out that the ring could actually be a belt on the white dwarf. For the central while dwarf, our analysis yields a T-eff=22,000+/-1000 K, log g=8.0, with the abundance of all heavy elements 0.3 times their solar values. This disk contributes about 12% of the total far UV flux in the FOS far ultraviolet region. (C) 1996 American Institute of Physics. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV MARYLAND,DEPT ASTROPHYS,COLLEGE PK,MD 20742. UNIV SCI & TECHNOL CHINA,CTR ASTROPHYS,HEFEI 230026,ANHUI,PEOPLES R CHINA. UNIV WASHINGTON,DEPT ASTRON,SEATTLE,WA 98195. NR 17 TC 14 Z9 14 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 1996 VL 111 IS 6 BP 2386 EP 2390 DI 10.1086/117972 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN631 UT WOS:A1996UN63100024 ER PT J AU Singh, KP Drake, SA White, NE AF Singh, KP Drake, SA White, NE TI RS CVn versus Algol-type binaries: A comparative study of their x-ray emission SO ASTRONOMICAL JOURNAL LA English DT Article ID CANUM-VENATICORUM; SYSTEMS; STARS AB We have compiled a list of 59 RS CVn binaries and 29 Algol-type binaries with well-known orbital parameters and which have been observed with the ROSAT PSPC detector in order to find out whether there is any detectable influence of mass transfer on the x-ray emission properties of these two types of active binaries. If there were, one might expect the RS CVn binaries (which typically are expected to have negligible mass exchange) and the semidetached ''Algol'' binaries (which have well-established mass exchange between the two components) to exhibit systematic differences in the x-ray region. We have studied the statistical correlations between (a) the x-ray luminosity (L(x)) and the Roche-lobe filling fraction (Gamma(2)) for the active star, (b) L(x) and the rotation period (P), and (c) the x-ray surface flux (S-x) and P. In general, we find that the RS CVn and Algol binaries do not have similar L(x) distributions. There is a tendency for the Algol binaries to be similar to 3-4 times less luminous compared to RS CVns with the same period. This is the exact opposite of what might have been expected if mass transfer rates influenced x-ray emission levels, since in that case the Algol binaries would be more x-ray luminous than the RS CVn binaries. A highly significant correlation is found between log S-x and log P in both of the two types of binaries, while a weak correlation that is observed between log L(x) and log Gamma(2) in the RS CVn binaries is likely to be due to correlations of these quantities with the stellar radii. (C) 1996 American Astronomical Society. C1 UNIV SPACE RES ASSOC,WASHINGTON,DC 20036. RP Singh, KP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 6602,GREENBELT,MD 20771, USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 26 TC 39 Z9 39 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 1996 VL 111 IS 6 BP 2415 EP 2421 DI 10.1086/117975 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN631 UT WOS:A1996UN63100027 ER PT J AU Jensen, ELN Koerner, DW Mathieu, RD AF Jensen, ELN Koerner, DW Mathieu, RD TI High-resolution imaging of circumstellar gas and dust in UZ Tauri: Comparing binary and single-star disk properties SO ASTRONOMICAL JOURNAL LA English DT Article ID YOUNG STELLAR OBJECTS; MODEL SCATTERING ENVELOPES; MAIN-SEQUENCE STARS; POLARIZATION SURVEY; GG-TAURI; RU-LUP; EMISSION; SPECTRA; AURIGA; SEARCH AB We present lambda = 1.3 and 3 mm aperture synthesis imaging of the multiple T Tauri system UZ Tauri, UZ Tau is a hierarchical triple composed of a single star, UZ Tau E, 530 AU distant from a 50 AU binary, UZ Tan W. Both dust and gas emission from the close binary are at least a factor of four lower than from the single star. Since UZ Tau E and W have similar stellar masses, luminosities, and ages, we conclude that the mass of dust and gas associated with UZ Tau W is reduced solely by the influence of a close companion. The disk emission from UZ Tau E is best interpreted as a circumstellar disk similar to those around other single T Tauri stars. In a 1''-resolution aperture synthesis map, CO (2-->1) emission is coincident with the continuum peak and elongated with a size of 300 AU (FWHM); a velocity gradient is seen along the long axis, consistent with rotation in a gaseous disk. The emission is elongated at position angle 19 degrees, the same as the PA of previous polarization measurements. A disk model fit to the continuum spectral energy distribution (SED) of UZ Tau E yields a disk mass of 0.06 M.. In contrast, no CO emission is detected from UZ Tau W, and its 1.3 mm continuum emission is unresolved in a 1'' (FWHM) beam (corresponding to a 70 AU radius). The small extent of the emission and dynamical considerations imply that the 50 AU binary cannot be surrounded by any appreciable circumbinary disk; its mm-wave emission is from circumstellar disks around one or both components. The mass of the circumstellar material is in the range 0.002-0.04 M.; the large uncertainty is due to the unknown temperature and surface density distributions of the material, The properties of the UZ Tau E disk are similar to those inferred for the early solar nebula; such a disk could give rise to a planetary system like our own. The mass of the UZ Tau W disk(s) is only marginally consistent with a ''minimum mass solar nebula.'' The constraints on disk size in UZ Tau W indicate that reduced mm-wave flux may be linked to a disparity in the size of disks (and therefore of planetary systems) around single and binary stars. (C) 1996 American Astronomical Society. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CALTECH,PASADENA,CA 91125. RP Jensen, ELN (reprint author), UNIV WISCONSIN,DEPT ASTRON,475 N CHARTER ST,MADISON,WI 53706, USA. OI Jensen, Eric/0000-0002-4625-7333 NR 59 TC 49 Z9 49 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 1996 VL 111 IS 6 BP 2431 EP 2438 DI 10.1086/117977 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN631 UT WOS:A1996UN63100029 ER PT J AU Linfield, RP AF Linfield, RP TI IPM and ISM coherence and polarization effects on observations with low-frequency space arrays SO ASTRONOMICAL JOURNAL LA English DT Article ID DENSITY-FLUCTUATIONS; INTERSTELLAR-MEDIUM; SOLAR-WIND; SCINTILLATION; SCATTERING AB The effect of the interplanetary and interstellar media upon a low-frequency space array (300 kHz-30 MHz observing frequency, baseline lengths up to 100-200 km) has been quantified. A new feature of these calculations is the impact of angular broadening by the interstellar medium upon temporal coherence. Inclusion of this feature demonstrates that the media effects upon observations with such an array will be much less serious than indicated by earlier studies. The coherence loss from the interplanetary medium will be minor for a wide range of observing parameters. The differential Faraday rotation over a baseline is negligible, but the Faraday depolarization over even the smallest sources will be large at most observing frequencies. Therefore, the use of linear feeds will not result in degradation of imaging capability. (C) 1996 American Astronomical Society. RP Linfield, RP (reprint author), CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NR 26 TC 3 Z9 3 U1 2 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 1996 VL 111 IS 6 BP 2465 EP 2468 DI 10.1086/117981 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UN631 UT WOS:A1996UN63100033 ER PT J AU Rantakyro, FT Baath, LB Dallacasa, D Jones, DL Wehrle, AE AF Rantakyro, FT Baath, LB Dallacasa, D Jones, DL Wehrle, AE TI Multiband VLBI observations of CTA102 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE galaxies, active; galaxies, jets; quasars, CTA102 ID REFRACTIVE INTERSTELLAR SCINTILLATION; LOW-FREQUENCY VARIABILITY; RADIO-SOURCES; VARIABLE SOURCES; CTA-102 AB The source CTA 102, known to exhibit low frequency variability, has been observed at six epochs (three at lambda 32 cm, two at lambda 18 cm, and one at lambda 1.3 cm) with intercontinental VLBI arrays. On the basis of the changes observed in the structure, we believe that the flux density variations at these wavelengths are due to intrinsic processes and not due to interstellar scintillation. This source exhibits behaviour suggestive of being expanding with a very high apparent transverse velocity. C1 GOTHENBURG UNIV, DEPT ASTRON & ASTROPHYS, S-41296 GOTHENBURG, SWEDEN. ONSALA SPACE OBSERV, S-43992 ONSALA, SWEDEN. HALMSTAD UNIV, CTR IMAGING TECHNOL, S-30118 HALMSTAD, SWEDEN. CNR, IST RADIOASTRON, I-40129 BOLOGNA, ITALY. UNIV BOLOGNA, DIPARTMENTO ASTRON, I-40126 BOLOGNA, ITALY. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. CALTECH, JET PROP LAB, CTR INFRARED PROC & ANAL, PASADENA, CA 91125 USA. RP Rantakyro, FT (reprint author), CNR, IST RADIOASTRON, VIA GOBETTI 101, I-40129 BOLOGNA, ITALY. NR 28 TC 10 Z9 10 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUN PY 1996 VL 310 IS 1 BP 66 EP 74 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP694 UT WOS:A1996UP69400009 ER PT J AU Schaerer, D deKoter, A Schmutz, W Maeder, A AF Schaerer, D deKoter, A Schmutz, W Maeder, A TI Combined stellar structure and atmosphere models for massive stars .1. Interior evolution and wind properties on the main sequence SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars, atmospheres; early-type; evolution; fundamental parameters; Hertzsprung-Russell (HR) diagram; mass-loss ID RADIATION-DRIVEN WINDS; HOT LUMINOUS STARS; WOLF-RAYET STARS; TERMINAL VELOCITIES; EXPANDING ATMOSPHERES; O-STARS; OPACITY; SPECTRA; LINES AB We present the first ''combined stellar structure and atmosphere models'' (CoStar) for massive stars, which consistently treat the entire mass loosing star from the center out to the asymptotic wind velocity. The models use up-to-date input physics and state-of-the-art techniques to model both the stellar interior and the spherically expanding non-LTE atmosphere including line blanketing. Our models thus yield consistent predictions regarding not only the basic stellar parameters, including abundances, but also theoretical spectra along evolutionary tracks. On the same ground they allow us to study the influence of stellar winds on evolutionary models. In this first paper, we present our method and investigate the wind properties and the interior evolution on the main sequence (MS) at solar metallicity. The wind momentum and energy deposition associated with the MS evolution is given and the adopted wind properties are discussed. From our atmosphere calculations, which include the effect of multiple scattering and line overlap, we also derive theoretical estimates of mass loss driven by radiation pressure. These values are compared with the predictions from recent wind models of the Munich group (Pauldrach et al. 1990, 1994, Puls et al. 1995). While we find an overall agreement with most of their results, our estimates for the mass loss rates are larger for supergiants. Our rates are in better agreement with the observed values than those of Puls et al. (1995). A comparison between boundary conditions given by the conventional plane parallel and the new spherically expanding atmosphere approach is made. For the MS evolution the evolutionary tracks and the interior evolution are found to be basically unchanged by the new treatment of the outer layers. However, for stars close to the Eddington limit, a small uncertainty in the behaviour of the deep atmosphere is found which might marginally affect the evolution. Given the small spherical extension of the continuum forming layers in the considered evolutionary phases, the predicted stellar parameters differ negligibly from those obtained using plane parallel atmospheres. C1 ETH ZENTRUM, INST ASTRON, CH-8092 ZURICH, SWITZERLAND. NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, GREENBELT, MD 20771 USA. RP Schaerer, D (reprint author), OBSERV GENEVA, CH-1290 SAUVERNY, SWITZERLAND. RI Schmutz, Werner/B-4153-2014 OI Schmutz, Werner/0000-0003-1159-5639 NR 46 TC 53 Z9 53 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUN PY 1996 VL 310 IS 3 BP 837 EP 848 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UU581 UT WOS:A1996UU58100016 ER PT J AU Urry, CM Sambruna, RM Worrall, DM Kollgaard, RI Feigelson, ED Perlman, ES Stocke, JT AF Urry, CM Sambruna, RM Worrall, DM Kollgaard, RI Feigelson, ED Perlman, ES Stocke, JT TI Soft X-ray properties of a complete sample of radio-selected BL Lacertae objects SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL Lacertae objects, general; radio continuum, galaxies; X-rays, galaxies ID SPECTRAL VARIABILITY; ABSORPTION FEATURE; LAC OBJECTS; 5 GHZ; BLAZARS; EXOSAT; ROSAT; AGN AB We report the soft X-ray properties of the complete 1 Jy sample of 34 radio-selected BL Lacertae objects (RBLs) as measured with the ROSAT Position Sensitive Proportional Counter. The 0.1-2.0 keV spectra of RBLs are generally well described by a single power-law model modified at low energies by absorption in our Galaxy. In a few brighter cases, either a convex or concave spectrum was detected. The distribution of the X-ray photon indices for the RBL sample is quite broad, 1 < Gamma < 3, with a measurable intrinsic dispersion. Comparing the ROSAT spectral index distributions of RBLs and other blazars, we find that RBLs have soft X-ray spectra similar to the X-ray-selected BL Lacertae objects (XBLs) of the EMSS complete sample, and both are steeper than more luminous (and more distant) strong emission-line blazars. Sorting the sources according to the ratio of their radio to X-ray fluxes into low-frequency peaked BL Lacertae objects (LBLs, which are mostly RBLs) and high-frequency peaked BL Lacertae objects (HBLs, which are mostly XBLs), the soft X-ray spectral index distributions for the two classes. are statistically different, with LBLs being flatter than HBLs. The ROSAT spectra of RBLs are steeper than those obtained previously with the Einstein Observatory IPC at slightly higher energies, suggesting that for these objects a flatter (Compton) component emerges at or above similar to 1 keV. The ROSAT data confirm that RBLs are variable X-ray sources, on timescales as short as weeks or even hours. Spectral variability was detected for three of the six sources having more than two pointed observations. Two of these are flatter in the fainter state, in contrast to the trend seen in previous X-ray studies of BL Lac objects (mostly XBLs). C1 HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. PENN STATE UNIV,DEPT ASTRON & ASTROPHYS,UNIVERSITY PK,PA 16802. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV COLORADO,CTR ASTROPHYS & SPACE ASTRON,BOULDER,CO 80309. RP Urry, CM (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. RI Urry, Claudia/G-7381-2011; OI Urry, Claudia/0000-0002-0745-9792; Perlman, Eric/0000-0002-3099-1664 NR 79 TC 88 Z9 91 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1996 VL 463 IS 2 BP 424 EP 443 DI 10.1086/177259 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM945 UT WOS:A1996UM94500005 ER PT J AU Jones, BB Bertsch, DL Dingus, BL Esposito, JE Fichtel, CE Fierro, JM Hartman, RC Hunter, SD Kanbach, G Kniffen, DA Lin, YC MayerHasselwander, HA Mattox, JR Michelson, PF vonMontigny, C Nolan, PL Pohl, M Schneid, EJ Sreekumar, P Thompson, DJ Tompkins, WF Willis, TD AF Jones, BB Bertsch, DL Dingus, BL Esposito, JE Fichtel, CE Fierro, JM Hartman, RC Hunter, SD Kanbach, G Kniffen, DA Lin, YC MayerHasselwander, HA Mattox, JR Michelson, PF vonMontigny, C Nolan, PL Pohl, M Schneid, EJ Sreekumar, P Thompson, DJ Tompkins, WF Willis, TD TI Possible EGRET gamma-ray burst detection independent of BATSE triggering SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays, bursts; methods, statistical AB EGRET spark chamber data collected between 1991 April 22 and 1994 August 29 have been analyzed for gamma-ray burst events independent of BATSE triggering. To date, five gamma-ray bursts that are coincident with a trigger from the BATSE instrument have been detected in the EGRET spark chamber. The EGRET-detected bursts have high-energy power-law tails and, in some cases, long duration emission. Because BATSE is sensitive in a lower energy range (25-600 keV), there may be other high energy gamma-ray bursts detectable with EGRET (30 MeV-30 GeV) that do not trigger BATSE. Also, bursts with long-duration emission may be more easily detected with EGRET. Furthermore, burst events may have occurred while BATSE was temporarily inactive. Two previously detected gamma-ray bursts were independently detected, and one new possible detection was made on a timescale of 3 minutes, although the significance is subject to systematic errors. C1 STANFORD UNIV,DEPT PHYS,STANFORD,CA 94305. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. MAX PLANCK INST EXTRATERR PHYS,D-85748 GARCHING,GERMANY. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. RP Jones, BB (reprint author), STANFORD UNIV,WW HANSEN EXPT PHYS LAB,STANFORD,CA 94305, USA. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012; OI Thompson, David/0000-0001-5217-9135; Dingus, Brenda/0000-0001-8451-7450 NR 11 TC 6 Z9 6 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1996 VL 463 IS 2 BP 565 EP 569 DI 10.1086/177271 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM945 UT WOS:A1996UM94500017 ER PT J AU Koshut, TM Paciesas, WS Kouveliotou, C vanParadijs, J Pendleton, GN Fishman, GJ Meegan, CA AF Koshut, TM Paciesas, WS Kouveliotou, C vanParadijs, J Pendleton, GN Fishman, GJ Meegan, CA TI Systematic effects on duration measurements of gamma-ray bursts SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays, bursts ID RELATIVISTIC FIREBALLS AB The parameters T-90 and T-50 have recently been introduced as a measurement of the duration of gamma-ray bursts. We present here a description of the method of measuring T-90 and T-50 and its application to gamma-ray bursts observed with the Burst and Transient Source Experiment (BATSE) onboard the Compton Gamma-Ray Observatory (CGRO). We use simulated as well as observed time profiles to address some of the possible systematic effects affecting individual T-90 (T-50) measurements. We show that these systematic effects do not mimic those effects that would result from time dilation if the burst sources are at distances of several Gpc. We discuss the impact of these systematic effects on the T-90 (T-50) distributions for the gamma-ray bursts observed with BATSE. We distinguish between various types of T-90 (T-50) distributions, and discuss the ways in which distributions observed with different experiments can vary, even though the measurements for commonly observed bursts may be the same. We then discuss the distributions observed with BATSE and compare them to those observed with other experiments. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV SPACE RES ASSOC,COLUMBIA,MD 21044. UNIV AMSTERDAM,ASTRON INST ANTON PANNEKOEK,1098 SJ AMSTERDAM,NETHERLANDS. RP Koshut, TM (reprint author), UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899, USA. NR 21 TC 67 Z9 67 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1996 VL 463 IS 2 BP 570 EP 592 DI 10.1086/177272 PN 1 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM945 UT WOS:A1996UM94500018 ER PT J AU Digel, SW Grenier, IA Heithausen, A Hunter, SD Thaddeus, P AF Digel, SW Grenier, IA Heithausen, A Hunter, SD Thaddeus, P TI Diffuse high-energy gamma-ray emission beyond the solar circle: The Cepheus and Polaris flares and the Perseus arm SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic rays; diffuse radiation; gamma rays, observations; ISM, clouds; radio lines, ISM ID 1ST GALACTIC QUADRANT; MOLECULAR CLOUDS; OUTER GALAXY; RADIAL-DISTRIBUTION; MILKY-WAY; INTERSTELLAR GAS; CO OBSERVATIONS; SPIRAL ARM; IRAS AB We present a study of the diffuse, high-energy gamma-ray emission detected in the outer Galaxy toward the Cepheus flare by the EGRET instrument on the Compton Gamma Ray Observatory. The region studied (l = 100 degrees to 130 degrees, b = -5 degrees to 32 degrees) contains the prominent local clouds of the Cepheus and Polaris flares and the molecular cloud complex associated with Cas A and NGC 7538, the largest in the Perseus arm. Gas along the line of sight is partitioned into three distance ranges. The gamma-ray emissivity and N(H-2)/W-CO ratio in the local range are found to be (1.84 +/- 0.10) x 10(-26) s(-1) sr(-1) and (0.92 +/- 0.14) x 10(20) cm(-2) (K km s(-1))(-1), respectively, both derived for the energy range E > 100 MeV. In the Perseus arm, these quantities are (1.11 +/- 0.09) x 10(-26) s(-1) sr(-1) and (2.5 +/- 0.9) x 10(20) cm(-2) (K km s(-1))(-1). The decrease of emissivity from the solar circle to the Perseus arm is significant, although the variation of N(H-2)/W-CO, is not. No significant variations of these quantities within each distance range are found. The gamma-ray emissivity in the Perseus arm is much less than predicted by models that assume a simple coupling between cosmic-ray density and surface density of interstellar gas. The derived emissivity in the Perseus arm constrains the amount of molecular gas not detected in CO to be at most one-tenth the amount of atomic hydrogen. A bright, soft spectrum gamma-ray source in this held reported from analysis of COS B data is not seen by EGRET. The spectrum of the extragalactic isotropic emission toward Cepheus is consistent with findings from other regions that have been studied with EGRET data. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. CTR ETUD SACLAY,SERV ASTROPHYS,DAPNIA,DSM,F-91191 GIF SUR YVETTE,FRANCE. UNIV PARIS 07,OBSERV PARIS,EUROPA,F-92195 MEUDON,FRANCE. UNIV COLOGNE,INST PHYS 1,W-5000 COLOGNE 41,GERMANY. RP Digel, SW (reprint author), CTR ASTROPHYS,MS 72,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. RI Hunter, Stanley/D-2942-2012 NR 54 TC 48 Z9 48 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1996 VL 463 IS 2 BP 609 EP 622 DI 10.1086/177275 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM945 UT WOS:A1996UM94500021 ER PT J AU Godon, P AF Godon, P TI Accretion disk boundary layers in classical T Tauri stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; stars, formation; stars, pre-main-sequence ID FU-ORIONIS; EMISSION AB Results of one-dimensional time-dependent calculations of geometrically thin accretion disk boundary layers are presented for classical T Tauri stars for various values of M*, (0.8 and 1.0 M.), R* (1.6, 2.15, and 4.3 R.), and M (5 x 10(-9)-5 x 10(-7) M. yr(-1)). The results exhibit a thermal boundary layer (delta(BL)(th) approximate to 0.1-0.2R*) much larger than the dynamical one (delta(BL)(dyn) approximate to few percent), with characteristic low temperatures (T-BL(eff) approximate to 5-6 x 10(3) K). In the limit of very low mass accretion rates characteristic of T Tauri systems, the mid-plane temperature in the inner disk drops well below 10(4) K (a few approximate to 10(3) K at most). A very sharp transition region separates the hot ionized thermal boundary layer region from the cool neutral inner disk. For low values of the viscosity parameter (alpha approximate to 0.01), the medium is optically thin in the cool inner disk and slightly optically thick in the hot thermal boundary layer. This result explains the absence of optically thick material (the ''inner hole'') as observed in the central part of circumstellar disks around young stellar objects. For higher values of the viscosity parameter (alpha approximate to 0.1), the optical depth in the boundary layer region decreases (tau approximate to 1) and its temperature increases slightly, while the inner disk becomes partially ionized and optically more thick. RP Godon, P (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MS 238-332,PASADENA,CA 91109, USA. NR 30 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1996 VL 463 IS 2 BP 674 EP 680 DI 10.1086/177281 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM945 UT WOS:A1996UM94500027 ER PT J AU Saraswat, P Yoshida, A Mihara, T Kawai, N Takeshima, T Nagase, F Makishima, K Tashiro, M Leahy, DA Pravdo, S Day, CSR Angelini, L AF Saraswat, P Yoshida, A Mihara, T Kawai, N Takeshima, T Nagase, F Makishima, K Tashiro, M Leahy, DA Pravdo, S Day, CSR Angelini, L TI An ASCA observation of the x-ray binary GX 301-2 SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries, close; pulsars, individual (GX 301-2); X-rays, stars ID STELLAR WINDS; GX301-2; ABSORPTION; MODELS; STARS; FLUORESCENCE; SCATTERING; DEPENDENCE; GX-301-2; SPECTRUM AB The X-ray binary pulsar GX 301-2 was observed with the Advanced Satellite for Cosmology and Astrophysics (ASCA) on 1994 February 13-14, at the binary orbital phase between 0.277 and 0.308. The source was found to be in a low-intensity phase, with an intrinsic luminosity L(X) = 6.6 x 10(35) ergs s(-1) in the 0.7-10.0 keV energy band. This is roughly 2 orders of magnitude lower than the peak luminosity generally observed at periastron. The spectral analysis shows the presence of a strong low-energy excess below about 4 keV and high photoelectric absorption (similar to 6 x 10(23) cm(-2)). Part of the soft excess may be caused by the scattering of X-rays around a region of increased density by the less dense ambient stellar wind, which would explain the absence of pulsations in the low-energy excess. The spectrum also shows a strong, narrow fluorescent iron line and an absorption iron K edge. The average energy of the line is 6.400 +/- 0.008 keV and that of the edge is 7.183 +/- 0.013 keV (at the 90% confidence level). The iron line equivalent width is 228 +/- 18 eV. The partial covering model does not describe the low-energy excess adequately. It underestimates the continuum between 2.0 and 5.0 keV but overestimates it below 1.5 keV. This, together with the absence of pulsations in the low-energy excess, rules out the partial covering model as a good description of the continuum spectrum. In addition, the spectra from the solid-state imaging spectrometers (SIS) aboard ASCA reveal two new features. First, it is seen that the fit with the scattering model is not acceptable below 2 keV and suggests an additional component as cause for this residual soft excess. The ultrasoft component has been observed in the spectra of GX 301-2 for the first time and can be fitted well by thermal emission from a hot plasma with a temperature kT of similar to 0.8 keV. The ultrasoft component may arise because of emission from X-ray-induced shocks in the gas trailing the neutron star. A partial ionization model with a warm absorber in series with a neutral absorber, including scattering, does not account for the ultrasoft excess below 1.5 keV and can be ruled out. Second, it is also seen that the SIS spectrum is dominated by line features at 0.80, 1.73, 2.30, 2.98, and 3.68 keV. These can be identified with the fluorescent line emission from neutral or near-neutral Ne, Si, S, Ar, and Ca, respectively. This implies that the line emission is coming from cold (less than or equal to 10(5) K) gas. The pulse phase spectroscopy shows that the photon index, the iron line intensity, and the equivalent width vary with pulse phase. The large equivalent width variations are, however, mainly due to the changes in the underlying continuum intensity. C1 INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. UNIV TOKYO,FAC SCI,DEPT PHYS,BUNKYO KU,TOKYO 113,JAPAN. UNIV CALGARY,DEPT PHYS,CALGARY,AB T2N 1N4,CANADA. CALTECH,JET PROP LAB,PASADENA,CA 91109. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. RP Saraswat, P (reprint author), INST PHYS & CHEM RES,COSM RADIAT LAB,HIROSAWA 2-1,WAKO,SAITAMA 35101,JAPAN. RI Tashiro, Makoto/J-4562-2012; Mihara, Tatehiro/C-5536-2017 OI Mihara, Tatehiro/0000-0002-6337-7943 NR 39 TC 25 Z9 25 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1996 VL 463 IS 2 BP 726 EP 736 DI 10.1086/177285 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM945 UT WOS:A1996UM94500031 ER PT J AU Goodman, ML AF Goodman, ML TI Heating of the solar middle chromospheric network and internetwork by large-scale electric currents in weakly ionized magnetic elements SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; Sun, chromosphere; Sun, magnetic fields ID TRANSFORM SPECTROMETER OBSERVATIONS; QUIET SUN; CARBON-MONOXIDE; LIMB PROFILES; BIFURCATION; MILLIMETERS; ATMOSPHERE; ECLIPSE; MODEL; WAVES AB A two-dimensional, dissipative magnetohydrodynamic model is used to argue that a major source of in situ heating for the solar middle chromosphere is the resistive dissipation of large-scale electric currents flowing in magnetic elements. A magnetic element is an arch-shaped magnetic field configuration consisting of a central region of horizontally localized, mainly vertical magnetic field based in the photosphere, with field lines that diverge horizontally with increasing height, extend into the middle chromosphere, and then return to the photosphere as a relatively diffuse, weaker field. The currents that flow in these elements are carried by protons, and are large scale in that their scale height is hundreds of kilometers in the network and thousands of kilometers in the internetwork. Solutions to the model demonstrate that the resistive dissipation of large-scale electric currents flowing orthogonal to the magnetic field in magnetic elements embedded in a weakly ionized, strongly magnetized hydrogen gas may generate all of the thermal energy necessary to heat the middle chromosphere. The magnetic field is computed self-consistently with the electric field, pressure, and hydrogen and proton densities. Solutions to the model suggest that magnetic elements with horizontal extents up to several arcseconds may be confined to, and heat, the chromospheric network, while elements with the largest horizontal extents may span and heat the internetwork and be the building blocks of the chromospheric magnetic canopy. The model predicts that the heating rate per unit mass (q) is independent of height, peaked near but horizontally displaced from the center of a magnetic element, and for realistic model input parameters has an average value computed over the base area of the element close to the value 4.5 x 10(9) ergs g(-1) s(-1) predicted by semiempirical models of the chromosphere that also predict that q is independent of height in the middle chromosphere. The model predicts that the heating rate per unit volume is peaked near the horizontal midpoint of a magnetic element where the field is mainly horizontal. The model predicts that both heating rates are zero at the center and outer boundary of a magnetic element where the field is vertical. These model predictions for the spatial localization of the heating rates are consistent with observations that regions of enhanced emission are near but horizontally displaced from regions of vertical, high-magnitude magnetic field. C1 NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, PLANETARY MAGNETOSPHERES BRANCH, GREENBELT, MD 20771 USA. RP COMP SCI CORP, GREENBELT, MD 20771 USA. NR 43 TC 5 Z9 5 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1996 VL 463 IS 2 BP 784 EP 796 DI 10.1086/177290 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM945 UT WOS:A1996UM94500036 ER PT J AU Smith, SJ Zuo, M Chutjian, A Tayal, SS Williams, ID AF Smith, SJ Zuo, M Chutjian, A Tayal, SS Williams, ID TI Electron excitation cross sections for the C II transitions 2s(2)2p P-2(0)->2s2p(2) P-4, D-2, and S-2 SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic data; ultraviolet, general ID RESONANCE TRANSITIONS; ULTRAVIOLET LINES; IMPACT EXCITATION; GENERAL PROGRAM; FINE-STRUCTURE; CARBON AB Experimental and theoretical excitation cross sections are reported for the transitions 2s(2)2p 2P(0) --> 2s2p(2) P-4, 2(D) and S-2 in C II. The transition wavelengths (energies) are 2324 Angstrom, (5.34 eV), 1335 A (9.29 eV), and 1036 Angstrom,(11.97 eV), respectively. Use is made of electron energy-loss and merged beams methods. The energy range covered is from below each threshold (4-11 eV) to 15-24 eV. As in previous work with O II, care was taken to assess and minimize the metastable fraction in the C II beam, to account for contributions from nearby energy-loss features, and to collect the full angular range of inelastically scattered electrons. A comparison is made for each transition between experiment and new 8-state R-matrix calculations. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CLARK ATANTA UNIV,DEPT PHYS,ATLANTA,GA 30314. CLARK ATANTA UNIV,CTR THEORET STUDIES PHYS SYST,ATLANTA,GA 30314. QUEENS UNIV BELFAST,DEPT PURE & APPL PHYS,BELFAST BT7 1NN,ANTRIM,NORTH IRELAND. NR 36 TC 16 Z9 16 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1996 VL 463 IS 2 BP 808 EP 817 DI 10.1086/177292 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM945 UT WOS:A1996UM94500038 ER PT J AU Crary, DJ Kouveliotou, C vanParadijs, J vanderHooft, F vanderKlis, M Rubin, BC Scott, DM Finger, MH Harmon, BA AF Crary, DJ Kouveliotou, C vanParadijs, J vanderHooft, F vanderKlis, M Rubin, BC Scott, DM Finger, MH Harmon, BA TI Search for rapid X-ray variability from the black hole candidate GRO J1655-40 SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars, individual (GRO J1655-40); X-rays, stars AB We have examined 15 days of CGRO/BATSE data, obtained during the first outburst of the black hole candidate source GRO J1655-40, to search for rapid variability of its X-ray flux. We find no evidence for significant variability of GRO J1655-40 during our observations, with a 2 sigma upper limit to the fractional rms amplitude in the frequency range 0.03-0.488 Hz of 6.6%. We cannot, on the basis of our observations, determine the source state (low, high, or very high state) of GRO J1655-40. C1 UNIV SPACE RES ASSOC, HUNTSVILLE, AL 35806 USA. UNIV ALABAMA, DEPT PHYS, HUNTSVILLE, AL 35899 USA. UNIV AMSTERDAM, ASTRON INST ANTON PANNEKOEK, NL-1098 SJ AMSTERDAM, NETHERLANDS. CTR HIGH ENERGY ASTROPHYS, NL-1098 SJ AMSTERDAM, NETHERLANDS. RP Crary, DJ (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, CODE ES-84, HUNTSVILLE, AL 35812 USA. NR 21 TC 2 Z9 2 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1996 VL 463 IS 2 BP L79 EP L81 DI 10.1086/310063 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM946 UT WOS:A1996UM94600009 ER PT J AU Done, C Madejski, GM Smith, DA AF Done, C Madejski, GM Smith, DA TI NGC 4945: The brightest Seyfert 2 galaxy at 100 keV SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, individual (NGC 4945); galaxies, Seyfert; gamma rays, observations X-rays, galaxies ID ACTIVE GALACTIC NUCLEI; X-RAY-SPECTRA; INFRARED GALAXY; NGC-4945; NGC-1068; GINGA AB Seyfert 2 galaxies are generally heavily absorbed in soft X-rays, plausibly because of obscuration of the Seyfert nucleus by a thick molecular torus. With a high torus column, 10(23) greater than or equal to N-H greater than or equal to 10(25) cm(-2), the observed flux in the ''classical'' 2-10 keV X-ray band can be strongly suppressed, while at higher energies the photoelectric absorption becomes less important and the true nuclear luminosity can be seen. The high-energy bandpass of the Ginga X-ray telescope, extending to 20 keV, allowed several such objects to be discovered, and an extrapolation of the obscured nuclear spectra out to 100 keV suggested that NGC 4945 should be among the very brightest radio-quiet Seyferts in the sky at 100 keV, second only to NGC 4151. OSSE data reported here confirm this prediction, and we analyze these, together with archival Ginga and ASCA data, in order to present a broadband spectrum from 0.6-500 keV of this object. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UNIV LEICESTER, DEPT PHYS & ASTRON, LEICESTER LE1 7RH, LEICS, ENGLAND. RP Done, C (reprint author), UNIV DURHAM, DEPT PHYS, SOUTH RD, DURHAM DH1 3LE, ENGLAND. RI done, chris/D-4605-2016 OI done, chris/0000-0002-1065-7239 NR 42 TC 42 Z9 42 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1996 VL 463 IS 2 BP L63 EP L66 DI 10.1086/310056 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM946 UT WOS:A1996UM94600005 ER PT J AU Koester, D Finley, DS Allard, NF Kruk, JW Kimble, RA AF Koester, D Finley, DS Allard, NF Kruk, JW Kimble, RA TI Quasi-molecular satellites of Ly beta in the spectrum of the DA white dwarf Wolf 1346 SO ASTROPHYSICAL JOURNAL LA English DT Article DE line, profiles; stars, atmospheres; stars, individual (Wolf 1346); stars, white dwarfs; ultraviolet, stars ID MASS-DISTRIBUTION; 1600-A FEATURES; TEMPERATURE; 1400-A AB We present new FUV/UV observations of the DA white dwarf Wolf 1346 obtained with the Hopkins Ultraviolet Telescope. The atmospheric parameters of this object are estimated from a fit of model atmospheres to several optical spectra to be T-eff = 20,000 K, log g = 7.90. From the optical spectrum this star is a normal DA without any indications for chemical elements other than hydrogen. The hydrogen line Ly beta, however, shows a very unusual shape, with a steep red wing and two absorption features on this wing. The shape is reminiscent of the effects of quasi-molecular line broadening, as observed in Ly alpha in cooler DA white dwarfs. We show that this is indeed the correct explanation, by identifying four quasi-molecular satellites caused through perturbations by the H+ ion (H-2(+) quasi-molecule). The steep red wing is caused by the exponential decline of the line profile beyond the satellite most distant from the line center at 1078 Angstrom. C1 EUREKA SCI INC, OAKLAND, CA USA. OBSERV PARIS, MEUDON, FRANCE. JOHNS HOPKINS UNIV, CTR ASTROPHYS SCI, BALTIMORE, MD 21218 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP Koester, D (reprint author), CHRISTIAN ALBRECHTS UNIV KIEL, INST ASTRON & ASTROPHYS, GUTENBERGSTR 76-78, D-24098 KIEL, GERMANY. RI Kimble, Randy/D-5317-2012; Kruk, Jeffrey/G-4047-2012 NR 25 TC 23 Z9 23 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1996 VL 463 IS 2 BP L93 EP L96 DI 10.1086/310062 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM946 UT WOS:A1996UM94600012 ER PT J AU Teegarden, BJ Cline, TL Gehrels, N Palmer, D Ramaty, R Seifert, H Hurley, KH Landis, DA Madden, NW Malone, D Pehl, R Owens, A AF Teegarden, BJ Cline, TL Gehrels, N Palmer, D Ramaty, R Seifert, H Hurley, KH Landis, DA Madden, NW Malone, D Pehl, R Owens, A TI TGRS observation of the galactic center annihilation line SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays, observations ID CENTER REGION; RADIATION AB The Transient Gamma-Ray Spectrometer (TGRS) experiment is a high-resolution germanium detector launched on the WIND satellite on 1994 November 1. Although primarily intended to study gamma-ray bursts and solar flares, TGRS also has the capability of studying slower transients (e.g., X-ray novae) and certain steady sources. We present here results on the narrow 511 keV annihilation line from the general direction of the Galactic center accumulated over the period 1995 January through 1995 October. These results were obtained from the TGRS occultation mode, in which a lead absorber occults the Galactic center region for 1/4 of each spacecraft rotation, thus chopping the 511 keV signal. The occulted region is a band in the sky of width 16 degrees that passes through the Galactic center. We detect the narrow annihilation line from the Galactic center with flux = (1.64 +/- 0.09) x 10(-3) photons cm(-2) s(-1). The data are consistent with a single point source at the Galactic center, but a distributed source of extent up to similar to 30 degrees cannot be ruled out. No evidence for temporal variability on timescales longer than 1 month was found. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. LAWRENCE BERKELEY LABS,BERKELEY,CA 94720. UNIV LEICESTER,DEPT PHYS & ASTRON,LEICESTER LE1 7RII,LEICS,ENGLAND. RI Gehrels, Neil/D-2971-2012 NR 16 TC 21 Z9 21 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1996 VL 463 IS 2 BP L75 EP L78 DI 10.1086/310061 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM946 UT WOS:A1996UM94600008 ER PT J AU White, NE Angelini, L Ebisawa, K Tanaka, Y Ghosh, P AF White, NE Angelini, L Ebisawa, K Tanaka, Y Ghosh, P TI The spectrum of the 8.7 s X-ray pulsar 4U 0142+61 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; pulsars, individual (4U 0142+61); stars, neutron; X-rays, stars ID MAGNETIZED NEUTRON STARS; ACCRETION AB We investigate the properties of the 8.7 s X-ray pulsar 4U 0142+61 using new data obtained with the RSCA observatory and archival data from the Einstein and ROSAT observatories. New measurements of the pulse period from 1979 and 1994 confirm that 4U 0142+61 is spinning down on a timescale of 127,000 yr. The RSCA spectrum is featureless and requires two components consisting of a similar to 0.4 keV blackbody plus a power law with a photon index of similar to 3.7. The blackbody flux is similar to 40% the total and for a distance greater than 0.5 kpc covers more than 12% of the neutron star surface. This covering fraction is 2 orders of magnitude larger than expected for thin disk accretion onto a magnetized neutron star. These results suggest 4U 0142+61 is probably not a low-mass X-ray binary system, but rather is an isolated pulsar undergoing a combination of spherical and disk accretion. The observed properties seem consistent with the suggestion by van Paradijs, Taam, & van den Heuvel that this pulsar is powered by accretion from the remnant of a Thorne-Zytkow object (TZO). The ROSAT PSPC image shows a dust-scattering halo that is a factor of 2 less than predicted by the measured equivalent hydrogen column density of 8 x 10(21) cm(-2), suggesting half of the absorbing material is located in the vicinity of the pulsar and possibly the remains of the TZO envelope. C1 MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. TATA INST FUNDAMENTAL RES,THEORET ASTROPHYS GRP,BOMBAY 400005,MAHARASHTRA,INDIA. RP White, NE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 24 TC 68 Z9 68 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1996 VL 463 IS 2 BP L83 EP L86 DI 10.1086/310065 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM946 UT WOS:A1996UM94600010 ER PT J AU Smith, DA Herter, T Haynes, MP Beichman, CA Gautier, TN AF Smith, DA Herter, T Haynes, MP Beichman, CA Gautier, TN TI Starburst galaxies .2. Imaging and spectroscopy of a radio-selected sample SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE galaxies, kinematics and dynamics; galaxies, photometry; galaxies, starburst; infrared, galaxies ID INITIAL MASS FUNCTION; INFRARED GALAXIES; STANDARD STARS; M82; EVOLUTION; EMISSION; NUCLEUS; GHZ AB We present J-, H-, and K-band images and low-resolution K-band spectra of the 20 most luminous starburst galaxies from the survey of Condon, Frayer, & Broderick. Optical rotation curves are also shown for 10 of these galaxies. Near-infrared colors, optical depths, CO indices, and dynamical masses are calculated. The near-infrared colors of the starburst nuclei are significantly redder than those observed in ''normal'' galaxies. Together, the Br gamma and radio fluxes available for five of the galaxies imply that the starbursts are heavily obscured; an average extinction of A(V) similar to 25 is derived. Strong CO absorption features indicate that late-type evolved stars are present in many of the starbursts. The average dynamical mass of the starburst region is found to be (1.0 +/- 0.4) x 10(9) M.. C1 CORNELL UNIV,CTR RADIOPHYS & SPACE RES,ITHACA,NY 14853. CALTECH,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 45 TC 31 Z9 31 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUN PY 1996 VL 104 IS 2 BP 217 EP 250 DI 10.1086/192299 PG 34 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM568 UT WOS:A1996UM56800004 ER PT J AU Smith, EP Pica, AJ Bohlin, RC Cornett, RH Fanelli, MN Landsman, WB OConnell, RW Roberts, MS Smith, AM Stecher, TP AF Smith, EP Pica, AJ Bohlin, RC Cornett, RH Fanelli, MN Landsman, WB OConnell, RW Roberts, MS Smith, AM Stecher, TP TI Ultraviolet Imaging Telescope near-ultraviolet bright object catalog SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE catalogs; galaxies, photometry; ultraviolet, stars ID GALAXIES AB We present a photometric catalog of 2244 objects detected by the Ultraviolet Imaging Telescope in the near-ultraviolet (NUV; 1650 Angstrom < lambda < 290 Angstrom) during the Astro-1 Space Shuttle mission. Sources in the catalog are as faint as m(nuv) similar to 18.8, or f(nuv) similar to 1.1 x 10(-16) ergs s(-1) cm(-2) Angstrom(-1), but the survey is not complete to this level. Optical catalogs were used to cross identify sources and derive NUV - V colors. A majority of the objects (88%) do indeed have proposed optical identifications from catalogs, and most are stars. Our purpose in creating the catalog is to form a database useful for identifying very blue objects and performing Galactic UV stellar population studies. C1 SALISBURY STATE UNIV,DEPT PHYS,SALISBURY,MD 21801. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,GREENBELT,MD 20771. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. RP Smith, EP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 681,GREENBELT,MD 20771, USA. NR 24 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUN PY 1996 VL 104 IS 2 BP 287 EP 315 DI 10.1086/192301 PG 29 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UM568 UT WOS:A1996UM56800006 ER PT J AU Chen, TC Yen, MC Pfaendtner, J Sud, YC AF Chen, TC Yen, MC Pfaendtner, J Sud, YC TI A complementary depiction of the interannual variation of atmospheric circulation associated with ENSO events SO ATMOSPHERE-OCEAN LA English DT Article ID SEA-SURFACE TEMPERATURE; EAST-WEST CIRCULATIONS; SOUTHERN OSCILLATION; SCALE PRECIPITATION; EL-NINO; MODEL AB A Simple diagnostic scheme, which combines a low-pass temporal filter (with an 18-month cutoff time) with a regular empirical orthogonal function (EOF) analysis, is used to delineate the synchronous evolution of El Nino-Southern Oscillation-related (ENSO-related) modes in various variables of the ocean-atmosphere system, Based on the causal relation chain of diabatic heating, divergent circulation and rotational flow, the diagnostic scheme extracts ENSO modes from the following data sources: the Pacific sea surface temperature (SST), the past 14-years (1979-1992) of data generated by the Global Data Assimilation System of the National Meteorological Center, and a 10-year (1979-1988) general circulation model climate simulation made at the Goddard Laboratory for Atmospheres. The analysis reveals the following: (a) the eigencoefficient time series of the first eigenmodes of selected filtered variables, which explain about 40-50% of their total variance, synchronize with the filtered SST averaged over Area NINO-3; (b) the spatial structures of the first eigenmodes resemble the ensemble departures associated with ENSO events of these variables from their long term means; and (c) the results show that the proposed scheme can be easily applied to isolate and illustrate the lime evolution of ENSO modes which exist in the long term observational database as well as in climate simulations. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP Chen, TC (reprint author), IOWA STATE UNIV SCI & TECHNOL,DEPT GEOL & ATMOSPHER SCI,ATMOSPHER SCI PROGRAM,3010 AGRON BLDG,AMES,IA 50011, USA. NR 21 TC 2 Z9 2 U1 0 U2 1 PU CANADIAN METEOROLOGICAL OCEANOGRAPHIC SOC PI OTTAWA PA 150 LOUIS PASTEUR PVT., STE 112, MCDONALD BUILDING, OTTAWA ON K1N 6N5, CANADA SN 0705-5900 J9 ATMOS OCEAN JI Atmos.-Ocean PD JUN PY 1996 VL 34 IS 2 BP 417 EP 433 PG 17 WC Meteorology & Atmospheric Sciences; Oceanography SC Meteorology & Atmospheric Sciences; Oceanography GA VG166 UT WOS:A1996VG16600007 ER PT J AU Jacobson, MZ Lu, R Turco, RP Toon, OB AF Jacobson, MZ Lu, R Turco, RP Toon, OB TI Development and application of a new air pollution modeling system .1. Gas-phase simulations SO ATMOSPHERIC ENVIRONMENT LA English DT Article; Proceedings Paper CT International Specialty Conference on Regional Photochemical Measurement and Modeling Studies CY NOV 08-12, 1993 CL SAN DIEGO, CA SP Air & Waste Management Assoc, Amer Meteorol Soc, Amer Geophys Union, Amer Chem Soc, Div Environm Chem, Amer Assoc Aerosol Res DE air quality modeling; airshed modeling; Eulerian grid modeling; gas-phase photochemistry; SCAQS data ID BACKGROUND TROPOSPHERE 70-DEGREES-N-60-DEGREES-S; SCIENTIFIC AIRCRAFT MEASUREMENTS; EXPERIMENT JUNE 1984; STRATOZ-III; 0-12KM ALTITUDE; FORMULATION; DEPOSITION; MECHANISM; QUALITY; URBAN AB A new air pollution modeling system is discussed and applied. The system consists of GATOR, a gas, aerosol, transport, and radiation air quality model and MMTD, a mesoscale meteorological and tracer dispersion model. The gas-phase processes treated by GATOR include photochemistry, deposition, emissions, and gas-to-particle conversion. To solve stiff chemical rate equations, a sparse-matrix, vectorized Gear-type code (SMVGEAR) was used. The aerosol processes in GATOR include coagulation, aqueous chemistry, chemical equilibrium, condensational growth, dissolutional growth, evaporation, nucleation, emissions, deposition, and sedimentation. The transport processes include horizontal advection and diffusion and vertical convection and diffusion. Finally, the radiation algorithm calculates ultraviolet, visible, and infrared optical depths, mean intensities for photodissociation rates, and radiative heat fluxes for temperature calculations. The MMTD predicts winds, diffusion, temperature, pressure, humidity, soil moisture, and rainfall. These variables are fed to GATOR and radiative heating rates from GATOR are fed back to the MMTD. With the GATOR/MMTD system, gas-phase pollution was simulated for the Southern California Air Quality Study (SCAQS) days of 26-28 August 1987. Results were compared to surface measurements for many parameters. The model predicted normalized gross errors for ozone of 17.6% and 23.4% at 2:30 p.m. on the first and second days of simulation, respectively. Also, the normalized gross error during the first 12 h of simulation was 22%. Correct emissions and initial mixing ratios appear to be necessary for obtaining good results. Initial conditions outside the basin seem to affect results by the second and third days. Time-series plots, statistics, and a sensitivity test are discussed. Aerosol simulation results will be shown in a later work. Copyright (C) 1996 Elsevier Science Ltd C1 UNIV CALIF LOS ANGELES,DEPT ATMOSPHER SCI,LOS ANGELES,CA 90024. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP Jacobson, MZ (reprint author), STANFORD UNIV,DEPT CIVIL ENGN,STANFORD,CA 94305, USA. NR 69 TC 75 Z9 75 U1 0 U2 10 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 1352-2310 J9 ATMOS ENVIRON JI Atmos. Environ. PD JUN PY 1996 VL 30 IS 12 BP 1939 EP 1963 DI 10.1016/1352-2310(95)00139-5 PG 25 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA UH931 UT WOS:A1996UH93100004 ER PT J AU Demoz, BB Collett, JL Daube, BC AF Demoz, BB Collett, JL Daube, BC TI On the Caltech Active Strand Cloudwater Collectors SO ATMOSPHERIC RESEARCH LA English DT Article ID FOGWATER COLLECTORS; INSTRUMENT; SIZE AB A detailed analysis of several versions of the Caltech Active Strand Cloudwater Collector (CASCC) is conducted. Efficiency calculations, design considerations and procedures for cloud liquid water content estimation from the collection rates of these instruments are discussed. The size-fractionating CASCC is capable of simultaneous collection of samples representing two portions of the cloud drop size spectrum. Large drops are collected in an inlet stage while smaller drops are collected in a second stage. Theoretical calculations, which assume no aerodynamic interaction between adjacent rows of collection rods in the inlet, suggest the inlet should have a 50% size cut corresponding to a drop size of 23 mu m diameter. However, field test results suggest that focusing of the flow passing through a row of cylinders may increase the efficiency of collection on the subsequent cylinder row, thereby decreasing the overall size cut for the inlet. The CASCC2, a compact version of the original CASCC, is designed to sample the entire cloud drop spectrum. Comparison of the cloudwater collection rates of the CASCC2 and the size-fractionating CASCC showed good agreement when normalized by the flow rare through each collector. The Caltech Heated Rod Cloudwater Collector (CHRCC), designed for use in supercooled clouds, features a theoretical 50% lower size cut corresponding to a drop diameter of 9 mu m. Liquid water content values estimated from the CHRCC cloudwater collection rates correlated reasonably well with values measured with a Gerber Particle Volume Monitor (PVM-100) in both warm (r(2) = 0.83) and supercooled (r(2) = 0.71) cloud conditions. C1 COLORADO STATE UNIV,DEPT ATMOSPHER SCI,FT COLLINS,CO 80523. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,CLIMATE & RADIAT BRANCH,GREENBELT,MD 20771. HARVARD UNIV,DIV APPL SCI,CAMBRIDGE,MA 02138. RI Collett, Jeffrey/F-2862-2010; Demoz, Belay/N-4130-2014 OI Collett, Jeffrey/0000-0001-9180-508X; NR 19 TC 95 Z9 96 U1 2 U2 18 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0169-8095 J9 ATMOS RES JI Atmos. Res. PD JUN PY 1996 VL 41 IS 1 BP 47 EP 62 DI 10.1016/0169-8095(95)00044-5 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UX406 UT WOS:A1996UX40600003 ER PT J AU White, DD Montgomery, LD AF White, DD Montgomery, LD TI Pelvic blood pooling of men and women during lower body negative pressure SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID VOLUME CHANGES; RESPONSES; TOLERANCE; FITNESS AB Introduction: The objective of this study was to investigate possible gender differences in the hemodynamic responses of the lower body during lower body negative pressure (LBNP). Methods: In this study, 17 women (mean age = 56 yrs) and 15 men (mean age = 55 yrs) underwent a 15 min exposure to -50 mm Hg LBNP. A Beckman (BR-100) Impedance Plethysmograph was used to measure each subject's leg and pelvic blood flow and pooling during the LBNP test. Results: The women had an 83% greater increase in blood volume in the pelvic region than men as a result of the LBNP exposure. Women and men had similar increases in leg blood volume as a result of the 15 min exposure to -50 mm Hg. There was no significant gender difference in the decreased amount of blood flow to the leg or pelvic regions by the end of -50 mm Hg LBNP. Conclusions: These results demonstrate that women have greater blood pooling in the pelvic region compared to men when exposed to -50 mm Hg LBNP. These results should be considered when designing life-support equipment for men and women pilots and astronauts, especially the designing of anti-G and Space Shuttle re-entry garment. C1 NASA,AMES RES CTR,LOCKHEED MARTIN ENGN SERV,MOFFETT FIELD,CA 94035. ML LIFEGUARD EQUIPMENT LTD,RUTHIN,CLWYD,WALES. NR 21 TC 39 Z9 40 U1 0 U2 4 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD JUN PY 1996 VL 67 IS 6 BP 555 EP 559 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA UP130 UT WOS:A1996UP13000008 PM 8827137 ER PT J AU Stowe, RP Pierson, DL AF Stowe, RP Pierson, DL TI Spreadsheet Macro for setting up PCR assay tubes SO BIOTECHNIQUES LA English DT Article AB This article describes a Microsoft(R) Excel TM macro designed to calculate PCR master mix amounts based on variations in the DNA template amounts added to each tube, the total number of PCR assay tubes being set up or both. This macro uses a dynamic dialog box to quickly calculate and display the new component volumes after changes in one ol both of the variables. The PCR assay mix protocol can then be printed in a format suitable for record keeping. This macro was designed for use with the Windows TM version of Excel but will also run on Macintosh(R) computers. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP Stowe, RP (reprint author), KRUG LIFE SCI INC,1290 HERCULES,SUITE 120,HOUSTON,TX 77058, USA. NR 1 TC 4 Z9 4 U1 0 U2 1 PU EATON PUBLISHING CO PI NATICK PA 154 E. CENTRAL ST, NATICK, MA 01760 SN 0736-6205 J9 BIOTECHNIQUES JI Biotechniques PD JUN PY 1996 VL 20 IS 6 BP 1088 EP 1089 PG 2 WC Biochemical Research Methods; Biochemistry & Molecular Biology SC Biochemistry & Molecular Biology GA UP432 UT WOS:A1996UP43200023 PM 8780879 ER PT J AU Hyonk, JJ Martin, MD AF Hyonk, JJ Martin, MD TI CD it for yourself SO BYTE LA English DT Article RP Hyonk, JJ (reprint author), JET PROPULS LAB,PASADENA,CA, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BYTE PUBL INC PI PETERBOROUGH PA 70 MAIN ST, PETERBOROUGH, NH 03458 SN 0360-5280 J9 BYTE JI Byte PD JUN PY 1996 VL 21 IS 6 BP 105 EP & PG 5 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering SC Computer Science GA UL195 UT WOS:A1996UL19500039 ER PT J AU Potter, CS Davidson, EA Verchot, LV AF Potter, CS Davidson, EA Verchot, LV TI Estimation of global biogeochemical controls and seasonality in soil methane consumption SO CHEMOSPHERE LA English DT Article DE methane oxidation; soils; modeling; global change; land use ID TEMPERATE FOREST SOILS; ATMOSPHERIC METHANE; CARBON-DIOXIDE; NITROUS-OXIDE; TROPICAL DEFORESTATION; GRASSLAND SOILS; OXIDATION; MODEL; FERTILIZATION; DIFFUSION AB Uptake by soils is a relatively small flux in the global budget of atmospheric methane, but CH4 consumption rates in soils could be susceptible to changes in land use and climate. Global estimates of the soil sink for atmospheric CH4 are usually made by multiplying averages of small chamber measurements for various ecosystem types (or other strata) by estimates of the area covered by each stratum. Process-level models driven by gridded databases can also be used to make global flux estimates, to evaluate potential effects of changes in climate and land use, and to identify weaknesses in both data and mechanistic understanding. Methane uptake by soils is an appropriate process to model globally because the probable controls are simple relative to many other microbially mediated soil processes of trace gas production and consumption. Field experience suggests that diffusion of atmospheric CH4 into the soil is the primary factor limiting rates of CH4 oxidation in many soils. We have applied a modified version of Fick's first law based on theoretical computations for diffusivity in aggregated media, together with a soil water balance model run on a 1 degrees global grid, to make independent estimates of CH4 uptake by soils worldwide. Uptake rates were assumed to be zero in very dry desert soils that are mostly devoid of microbial activity, in frozen soils, and in wetlands that are usually CH4 sources. Our mechanistically based model supports a reference case for global net consumption of CH4 in soils of 17-23 Tg yr(-1), which is near the middle of previously reported ranges; and is close to our own mean estimate from extrapolation of flux means across ecosystem strata (21 Tg CH4 yr(-1)). A new inference of our modeling approach is that over 40% of the soil sink for CH4 occurs in warm and relatively dry ecosystems, such as semi-arid steppe, tropical savanna, tropical seasonal forest, and chaparral. This model prediction results from a favorable climate regime, high porosity in coarse-to-medium textured soils, and low moisture content that permits rapid gaseous diffusion in these semi arid and seasonally dry tropical ecosystems. Very few data on CH4 fluxes exist from these areas that can be used to compare with model predictions. Because of this paucity of data where uptake rates may be relatively high, and because humans have altered these landscapes extensively, our results suggest that more study is needed in seasonally dry ecosystems in order to understand the impacts of land-use change on soil sinks for methane. Copyright (C) 1996 Elsevier Science Ltd C1 WOODS HOLE RES CTR, WOODS HOLE, MA 02543 USA. RP Potter, CS (reprint author), NASA, AMES RES CTR, JOHNSON CONTROLS WORLD SERV INC, MAIL STOP 242-4, MOFFETT FIELD, CA 94035 USA. RI Davidson, Eric/K-4984-2013 OI Davidson, Eric/0000-0002-8525-8697 NR 84 TC 144 Z9 149 U1 3 U2 60 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-6535 J9 CHEMOSPHERE JI Chemosphere PD JUN PY 1996 VL 32 IS 11 BP 2219 EP 2246 DI 10.1016/0045-6535(96)00119-1 PG 28 WC Environmental Sciences SC Environmental Sciences & Ecology GA UQ381 UT WOS:A1996UQ38100011 ER PT J AU Nillen, JL Smith, SM AF Nillen, JL Smith, SM TI The use of chlorhexidine/npropyl gallate (CPG) as a urine preservative. SO CLINICAL CHEMISTRY LA English DT Meeting Abstract C1 KRUG LIFE SCI,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSOC CLINICAL CHEMISTRY PI WASHINGTON PA 2101 L STREET NW, SUITE 202, WASHINGTON, DC 20037-1526 SN 0009-9147 J9 CLIN CHEM JI Clin. Chem. PD JUN PY 1996 VL 42 IS 6 SU S BP 889 EP 889 PN 2 PG 1 WC Medical Laboratory Technology SC Medical Laboratory Technology GA UR522 UT WOS:A1996UR52200889 ER PT J AU DavisStreet, JE Nillen, JL Smith, SM AF DavisStreet, JE Nillen, JL Smith, SM TI Urine storage during space flight: A comparison of preservatives. SO CLINICAL CHEMISTRY LA English DT Meeting Abstract C1 KRUG LIFE SCI,HOUSTON,TX. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSOC CLINICAL CHEMISTRY PI WASHINGTON PA 2101 L STREET NW, SUITE 202, WASHINGTON, DC 20037-1526 SN 0009-9147 J9 CLIN CHEM JI Clin. Chem. PD JUN PY 1996 VL 42 IS 6 SU S BP 890 EP 890 PN 2 PG 1 WC Medical Laboratory Technology SC Medical Laboratory Technology GA UR522 UT WOS:A1996UR52200890 ER PT J AU Jorgenson, PCE Pletcher, RH AF Jorgenson, PCE Pletcher, RH TI An implicit numerical scheme for the simulation of internal viscous flow on unstructured grids SO COMPUTERS & FLUIDS LA English DT Article ID EULER EQUATIONS; MESHES AB The development of a cell-centered unstructured grid solution for the two-dimensional Navier-Stokes equations is described. A finite-volume approach is used to discretize the conservation law form of the compressible dow equations written in terms of primitive variables. Temporal preconditioning is employed so that low Mach number Rows can be solved economically. The equations are marched in time using either an implicit Gauss-Seidel iterative procedure or a solver based on a conjugate gradient-like method. A four color scheme is employed to vectorize the block Gauss-Seidel relaxation procedure. This increases the memory requirements minimally and decreases the computer time spent solving the resulting system of equations substantially. A factor of 7.6 speedup in the matrix solver is typical for the viscous equations. The grids are generated based on the method of Delaunay triangulation. Numerical results are obtained for inviscid flow over a bump in a channel at subsonic and transonic conditions for validation with structured solvers. Viscous results are computed For developing flow in a channel, a symmetric sudden expansion, periodic tandem cylinders in a cross-flow, and a four-port valve. Comparisons are made with available results obtained by other investigators. Published by Elsevier Science Ltd. C1 IOWA STATE UNIV,DEPT MECH ENGN,AMES,IA 50010. RP Jorgenson, PCE (reprint author), NASA,LEWIS RES CTR,INST COMPUTAT MECH PROP,CLEVELAND,OH 44135, USA. NR 30 TC 3 Z9 3 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD JUN PY 1996 VL 25 IS 5 BP 447 EP 466 DI 10.1016/0045-7930(96)00013-8 PG 20 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA VB224 UT WOS:A1996VB22400001 ER PT J AU Benfield, MC Minello, TJ AF Benfield, MC Minello, TJ TI Relative effects of turbidity and light intensity on reactive distance and feeding of an estuarine fish SO ENVIRONMENTAL BIOLOGY OF FISHES LA English DT Article DE vision; shading; scattering; predation; Fundulus grandis; Palaemonetes pugio ID RAINBOW-TROUT; PREY; PREDATION; BEHAVIOR; MODEL; RATES AB Gulf killifish Fundulus grandis were allowed to prey on daggerblade grass shrimp Palaemonetes pugio in clear water with bright light, turbid water containing bentonite clay, and clear water treatments where the light intensity was adjusted to match that in the bottom of the turbid tanks. Significantly fewer shrimp were consumed in the turbid tanks relative to the clear and shade treatments where predation rates did not differ significantly. The results suggested that the influence of suspended particles on predation rates was a consequence of light scattering and was not related to a decrease in light intensity. Reactive distances were subsequently determined for human observers viewing a small target in elongated tanks containing turbid water (7.3-60.5 NTU) under conditions of both low (8-10 mu E m(-2) s(-1)) and high illumination (153-1249 mu E m(-2) s(-1)).). Reactive distance was primarily governed by turbidity while light intensity had little influence except at low turbidities. The shape of the relationship between reactive distance and turbidity for humans resembled curves reported for a variety of fish species. C1 SE FISHERIES CTR, NATL MARINE FISHERIES SERV, GALVESTON, TX 77551 USA. RP Benfield, MC (reprint author), WOODS HOLE OCEANOG INST, DEPT BIOL, WOODS HOLE, MA 02543 USA. NR 25 TC 77 Z9 80 U1 5 U2 34 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0378-1909 J9 ENVIRON BIOL FISH JI Environ. Biol. Fishes PD JUN PY 1996 VL 46 IS 2 BP 211 EP 216 DI 10.1007/BF00005223 PG 6 WC Ecology; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA UV974 UT WOS:A1996UV97400011 ER PT J AU Kim, YH Noor, AK AF Kim, YH Noor, AK TI Buckling and postbuckling of composite panels with cutouts subjected to combined loads SO FINITE ELEMENTS IN ANALYSIS AND DESIGN LA English DT Article ID LAMINATED PLATES; CIRCULAR HOLES; BEHAVIOR; COMPRESSION; STABILITY AB A detailed study is made of the buckling and postbuckling responses of composite panels with central circular cutouts subjected to various combinations of mechanical and thermal loads. The panels are discretized by using a two-field degenerate solid element with each of the displacement components having a linear variation through the thickness of the panel. The fundamental unknowns consist of the average mechanical strains through the thickness, and the displacement components. The effects of geometric nonlinearities and laminated anisotropic material behavior are included. The stability boundary, postbuckling response and the hierarchical sensitivity coefficients are evaluated. The hierarchical sensitivity coefficients measure the sensitivity of the buckling and postbuckling responses to variations in the panel stiffnesses, and the material properties of both the individual layers and the constituents (fibers and matrix). Extensive numerical results are presented for composite panels with central circular cutouts subjected to combined edge shortening, edge shear and temperature change. The results show the effects of variations in the hole diameter; the aspect ratio of the panel; the laminate stacking sequence and the fiber orientation on the stability boundary, postbuckling response and sensitivity coefficients. RP Kim, YH (reprint author), UNIV VIRGINIA,NASA,LANGLEY RES CTR,CTR COMPUTAT STRUCT TECHNOL,HAMPTON,VA 23681, USA. NR 33 TC 6 Z9 6 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-874X J9 FINITE ELEM ANAL DES JI Finite Elem. Anal. Des. PD JUN PY 1996 VL 22 IS 2 BP 163 EP 185 DI 10.1016/0168-874X(95)00052-U PG 23 WC Mathematics, Applied; Mechanics SC Mathematics; Mechanics GA UQ936 UT WOS:A1996UQ93600003 ER PT J AU DeHart, JM Lofgren, GE AF DeHart, JM Lofgren, GE TI Experimental studies of group Al chondrules SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID UNEQUILIBRATED ORDINARY CHONDRITES; DYNAMIC CRYSTALLIZATION; TEXTURES; HISTORY; OLIVINE; METAMORPHISM; MELTS AB Dynamic crystallization and annealing experiments have been conducted using a group A1 chondrule bulk composition to examine the formation and alteration of mesostases that emit a bright yellow cathodoluminescence (CL). This type of mesostasis has only been observed in group A1 and A2 chondrules in the least altered chondritic meteorites. The dynamic crystallization experiments produce yellow luminescing mesostases only in experiments cooled to their final quench temperatures at the slowest cooling rates. The yellow CL is present only where low Ca pyroxene grows from the melt so the remaining liquid is enriched in normative anorthite and diopside. This composition is strongly associated with yellow luminescence in group A1 chondrule mesostases. Low temperature hydrothermal annealing experiments demonstrate that the yellow luminescence can only be destroyed and not enhanced or altered to blue luminescence by aqueous alteration, Annealing under dry conditions increased both the amount and intensity of the yellow luminescent material, Annealing experiments designed to further devitrify the mesostasis converted both yellow luminescing and nonluminescent mesostases to blue luminescing mesostases. These results confirm that yellow luminescing mesostases are the result of the thermal history group A1 chondrules experienced prior to accretion, and their alteration to blue luminescing mesostases is a direct result of their metamorphic history. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP DeHart, JM (reprint author), ENERGY LABS,254 N CTR ST,CASPER,WY 82601, USA. NR 31 TC 11 Z9 11 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD JUN PY 1996 VL 60 IS 12 BP 2233 EP 2242 DI 10.1016/0016-7037(96)00076-2 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UR780 UT WOS:A1996UR78000014 ER PT J AU Zebker, HA Rosen, P Hensley, S MouginisMark, PJ AF Zebker, HA Rosen, P Hensley, S MouginisMark, PJ TI Analysis of active lava flows on Kilauea volcano, Hawaii, using SIR-C radar correlation measurements SO GEOLOGY LA English DT Article ID SYNTHETIC APERTURE RADARS AB Precise eruption rates of active pahoehoe Lava flows on Kilauea volcano, Hawaii, have been determined using spaceborne radar data acquired by the Space Shuttle Imaging Radar-C (SLR-C). A coastal site downslope from the Pu'u O'o vent was imaged once per day, on each of the four days of October 7-10, 1994. Day-to-day decorrelation due to resurfacing was determined by interferometric combination of the data at 15 m resolution over a wide area. On successive days, new lava resurfaced 335 700 m(2), 368 775 m(2), and 356 625 m(2). Assuming an average pahoehoe flow thickness of 50 cm, a mean effusion rate for this period is approximately 2 m(3)/s. The radar observations show persistent surface activity at each site, rather than downslope migration of coherent lava flows. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV HAWAII,HAWAII INST GEOPHYS & PLANETOL,HONOLULU,HI 96822. RP Zebker, HA (reprint author), STANFORD UNIV,DEPT GEOPHYS,STANFORD,CA 94305, USA. NR 11 TC 54 Z9 54 U1 0 U2 4 PU GEOLOGICAL SOC AMERICA PI BOULDER PA PO BOX 9140 3300 PENROSE PLACE, BOULDER, CO 80301 SN 0091-7613 J9 GEOLOGY JI Geology PD JUN PY 1996 VL 24 IS 6 BP 495 EP 498 DI 10.1130/0091-7613(1996)024<0495:AOALFO>2.3.CO;2 PG 4 WC Geology SC Geology GA UQ197 UT WOS:A1996UQ19700004 ER PT J AU Pope, KO Ocampo, SC Kinsland, GL Smith, R AF Pope, KO Ocampo, SC Kinsland, GL Smith, R TI Surface expression of the Chicxulub crater SO GEOLOGY LA English DT Article ID YUCATAN PENINSULA; IMPACT CRATER AB Analyses of geomorphic, soil, and topographic data from the northern Yucatan Peninsula, Mexico, confirm that the buried Chicxulub impact crater has a distinct surface expression and that carbonate sedimentation throughout the Cenozoic has been influenced by the crater, Late Tertiary sedimentation was mostly restricted to the region within the buried crater, and a semicircular moat existed until at least Pliocene time. The topographic expression of the crater is a series of features concentric with the crater, The most prominent is an similar to 83-km-radius trough or moat containing sinkholes (the Cenote ring), Early Tertiary surfaces rise abruptly outside the moat and form a stepped topography with an outer trough and ridge crest at radii of similar to 103 and similar to 129 km, respectively, Two discontinuous troughs lie within the moat at radii of similar to 41 and similar to 62 km. The low ridge between the inner troughs corresponds to the buried peak ring, The moat corresponds to the outer edge of the crater floor demarcated by a major ring fault. The outer trough and the similar to 62-km-radius inner trough also mark buried ring faults, The ridge crest corresponds to the topographic rim of the crater as modified by postimpact processes, These interpretations support previous findings that the principal impact basin has a diameter of similar to 180 km, but concentric, low-relief slumping extends well beyond this diameter and the eroded crater rim may extend to a diameter of similar to 260 km. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV SW LOUISIANA,DEPT GEOL,LAFAYETTE,LA 70504. CALIF STATE UNIV FRESNO,FRESNO,CA 93710. RP Pope, KO (reprint author), GEO ECO ARC RES,2222 FOOTHILL BLVD,SUITE E-272,LA CANADA FLINTRIDGE,CA 91011, USA. NR 20 TC 56 Z9 58 U1 0 U2 3 PU GEOLOGICAL SOC AMERICA PI BOULDER PA PO BOX 9140 3300 PENROSE PLACE, BOULDER, CO 80301 SN 0091-7613 J9 GEOLOGY JI Geology PD JUN PY 1996 VL 24 IS 6 BP 527 EP 530 DI 10.1130/0091-7613(1996)024<0527:SEOTCC>2.3.CO;2 PG 4 WC Geology SC Geology GA UQ197 UT WOS:A1996UQ19700012 PM 11539331 ER PT J AU Singh, HB Thakur, AN Chen, YE Kanakidou, M AF Singh, HB Thakur, AN Chen, YE Kanakidou, M TI Tetrachloroethylene as an indicator of low Cl atom concentrations in the troposphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID AIR AB Tetrachloroethylene (C2Cl4), a largely man-made chemical pollutant, is known to react with Cl atoms at a rate that is some 300 times faster than with OH radicals (k(Cl)/k(OH) = 365 at 275 K). Analysis of C2Cl4 data, with the help of a global 2-D model and in conjunction with the OH field derived from CH3CCl3 observations, has been used to provide a sensitive means for evaluating Cl atom abundance in the troposphere. In the ''mean case'' scenario, that employs best available measurements, emissions and kinetic parameters, it is found that OH oxidation is adequate to balance the C2Cl4 budget and significant removal by Cl is not indicated (Cl less than or equal to 10(2) molec. cm(-3)). An ''upper limit'' analysis that takes into account possible uncertainties in measurements, source emissions (man-made and natural), and reaction rates, is performed to estimate that annually averaged Cl atom concentrations in the troposphere are <5-10x10(2) molec. cm(-3). If we assume that nearly all (80-100%) of the Cl atoms reside in the marine boundary layer (MEL), mean MBL concentrations are estimated to be <5-15x10(3) molec. cm(-3). This analysis implies that mean Cl concentrations in the MBL are below or near the lower end of the values inferred in recent studies (10(4)-10(6) molec. cm(-3)). We conclude that despite their high reactivity, Cl atoms are too few to compete with OH radicals (approximate to 10(6) molec. cm(-3)) in influencing the oxidizing capacity of the global troposphere. C1 CEA, CNRS, CTR FAIBLES RADIOACT, F-91198 GIF SUR YVETTE, FRANCE. RP Singh, HB (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Kanakidou, Maria/D-7882-2012 OI Kanakidou, Maria/0000-0002-1724-9692 NR 22 TC 123 Z9 124 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 1 PY 1996 VL 23 IS 12 BP 1529 EP 1532 DI 10.1029/96GL01368 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UP857 UT WOS:A1996UP85700020 ER PT J AU Wetzel, PJ Liang, X Irannejad, P Boone, A Noilhan, J Shao, YP Skelly, C Xue, YK Yang, ZL AF Wetzel, PJ Liang, X Irannejad, P Boone, A Noilhan, J Shao, YP Skelly, C Xue, YK Yang, ZL TI Modeling vadose zone liquid water fluxes: Infiltration, runoff, drainage, interflow SO GLOBAL AND PLANETARY CHANGE LA English DT Article; Proceedings Paper CT RICE and PILPS Moisture Workshop - Soil Moisture Simulation CY NOV, 1994 CL MACQUARIE UNIV, SYDNEY, AUSTRALIA SP Reg Interact Climate & Ecosyst, Proj Intercomparison Landsurface Parameterizat Schemes HO MACQUARIE UNIV AB Because of the large water storage capacity of soil relative to the atmosphere, changes in soil moisture storage can significantly affect the regional atmospheric budgets of water and energy on monthly, seasonal and longer time scales. Therefore proper modeling of soil liquid water processes is essential to a correct representation of the climate system. This study focuses on the class of summary models of liquid water fluxes in the vadose, or unsaturated zone of the soil, which are applicable to global or regional climate modeling studies, Fourteen such models are represented in this intercomparison study, Observational data from the HAPEX experiment provide validation, Because only limited observational data were available to constrain these models during their development and validation, the models have evolved very diverse treatments of the relevant processes: the basic Darcian (soil internal) and Hortonian (surface liquid flow) processes, as well as the boundary conditions of baseflow drainage and lateral interflow. The annual total local runoff is systematically underestimated by all but one of the participant models. This is one of the few significant biases between the consensus of participant models and the observations. The modeled runoff, averaged over the 14 models, differs from the budget estimate from observations by about 40%. During the period of runoff generation (late winter and early spring) the average model fails to deplete the soil water store as rapidly as is observed, a result consistent with the underprediction of runoff. One cannot rule out insufficient characterization of the field site soils as a primary cause of these discrepancies, Results suggest that model sources of the discrepancy are about equally likely to be related to the prediction of bare soil evaporation (discussed elsewhere in this issue) as they are to the parameterization of runoff and drainage processes. C1 PRINCETON UNIV,DEPT CIVIL ENGN & OPERAT RES,PRINCETON,NJ 08544. MACQUARIE UNIV,CLIMATE IMPACTS CTR,SYDNEY,NSW 2109,AUSTRALIA. SCI SYST & APPL INC,LANHAM,MD. METEO FRANCE,CNRM,TOULOUSE,FRANCE. JAMES COOK UNIV N QUEENSLAND,DEPT GEOG,TOWNSVILLE,QLD 4811,AUSTRALIA. CTR OCEAN LAND ATMOSPHERE STUDIES,CALVERTON,MD. UNIV ARIZONA,INST ATMOSPHER PHYS,TUCSON,AZ 85721. RP Wetzel, PJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,MESOSCALE ATMOSPHER PROC BRANCH,GREENBELT,MD 20771, USA. RI Yang, Zong-Liang/B-4916-2011; Shao, Yaping/G-3606-2013 OI Shao, Yaping/0000-0002-2041-5479 NR 9 TC 25 Z9 26 U1 1 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD JUN PY 1996 VL 13 IS 1-4 BP 57 EP 71 DI 10.1016/0921-8181(95)00037-2 PG 15 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA UT685 UT WOS:A1996UT68500005 ER PT J AU Boone, A Wetzel, PJ AF Boone, A Wetzel, PJ TI Issues related to low resolution modeling of soil moisture: Experience with the PLACE model SO GLOBAL AND PLANETARY CHANGE LA English DT Article; Proceedings Paper CT RICE and PILPS Moisture Workshop - Soil Moisture Simulation CY NOV, 1994 CL MACQUARIE UNIV, SYDNEY, AUSTRALIA SP Reg Interact Climate & Ecosyst, Proj Intercomparison Landsurface Parameterizat Schemes HO MACQUARIE UNIV ID GENERAL-CIRCULATION MODELS; HAPEX-MOBILHY; SURFACE PARAMETERIZATION; CLIMATE MODELS; LAND-SURFACES; VEGETATION; EVAPOTRANSPIRATION; EVAPORATION; SIMULATION AB This study documents the new PLACE soil hydrology model, and examines the effects of various parameterization schemes on the solution of the Richards equation. Richards equation is the basis upon which many of the land surface schemes participating in the PILPS experiments model soil water transport, Generally, the integration is carried out using a coarse model grid, which makes the solution more sensitive to particulars of the parameterization scheme. Parameterization schemes for the tower boundary condition, lateral interflow, and for moisture fluxes between model layers are tested in PLACE using both high and low resolution grids. Simulations were made using PILPS-HAPEX forcing data and soil and vegetation parameters. The soil hydrology model is validated against the annual observed HAPEX soil moisture profiles, The predicted evapotranspiration is also compared to a value computed from the PILPS-HAPEX forcing data using the Penman-Monteith equation. When testing a low-resolution soil grid typical of land surface schemes, predicted soil moisture was found to be highly sensitive to the interpolation method for computing vertical moisture fluxes between model layers. A new interpolation method for low resolution models is proposed and tested. It reproduces the high resolution model results more faithfully, over the entire range of soil moisture, than two methods commonly applied in the literature. Further tests demonstrate that by varying the parameterizations for lower boundary condition and the treatment of lateral flow (collectively called drainage), the predicted total annual evapotranspiration may range between 74% and 97% of the incident precipitation in this case. Both of these parameterizations involve one free parameter, and both are largely unconstrained by the available observations, Good overall agreement between the PLACE predicted and HAPEX observed soil moisture profiles was attained by varying these two PLACE drainage parameters over their respective ranges for a series of model simulations. Root-mean square error tests were then used to determine the set of parameters which corresponded to the best predicted soil moisture profile. However, the best predicted soil moisture profiles do not correspond with the best predicted evapotranspiration. This inconsistency occurs not only for PLACE, but, to varying degrees, for all of the land-surface schemes participating in PILPS-HAPEX. C1 NASA,GODDARD SPACE FLIGHT CTR,MESOSCALE ATMOSPHER PROC BRANCH,GREENBELT,MD 20771. RP Boone, A (reprint author), SCI SYST & APPL INC,5900 PRINCESS GARDEN PKWY,LANHAM,MD 20706, USA. NR 32 TC 39 Z9 41 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD JUN PY 1996 VL 13 IS 1-4 BP 161 EP 181 DI 10.1016/0921-8181(95)00044-5 PG 21 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA UT685 UT WOS:A1996UT68500012 ER PT J AU Li, CS Narayanan, V Harriss, RC AF Li, CS Narayanan, V Harriss, RC TI Model estimates of nitrous oxide emissions from agricultural lands in the United States SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Article ID SOILS; N2O AB The Denitrification-Decomposition (DNDC) model was used to elucidate the role of climate, soil properties, and farming practices in determining spatial and temporal variations in the production and emission of nitrous oxide (N2O) from agriculture in the United States. Sensitivity studies documented possible causes of annual variability in N2O flux for a simulated Iowa corn-growing soil. The 37 scenarios tested indicated that soil tillage and nitrate pollution in rainfall may be especially significant anthropogenic factors which have increased N2O emissions from soils in the United States. Feedbacks to climate change and biogeochemical manipulation of agricultural soil reflect complex interactions between the nitrogen and carbon cycles. A 20% increase in annual average temperature in degrees C produced a 33% increase in N2O emissions. Manure applications to Iowa corn crops enhanced carbon storage in soils, but also increased N2O emissions. A DNDC simulation of annual N2O emissions from all crop and pasture lands in the United States indicated that the value lies in the range 0.9 - 1.2 TgN. Soil tillage and fertilizer use were the most important farming practices contributing to enhanced N2O emissions at the national scale. Soil organic matter and climate variables were the primary determinants of spatial variability in N2O emissions. Our results suggest that the United States Government, and possibly the Intergovernmental Panel on Climatic Change (IPCC), have underestimated the importance of agriculture as a national and global source of atmospheric N2O. The coupled nature of the nitrogen and carbon cycles in soils results in complex feedbacks which complicate the formulation of strategies to reduce the global warming potential of greenhouse gas emissions from agriculture. C1 NASA,OFF MISSION PLANET EARTH,WASHINGTON,DC 20546. TECH RESOURCES INT INC,ROCKVILLE,MD 20852. RP Li, CS (reprint author), UNIV NEW HAMPSHIRE,COMP SYST RES CTR,INST STUDY EARTH OCEANS & SPACE,EOS MORSE HALL,DURHAM,NH 03824, USA. NR 31 TC 143 Z9 170 U1 5 U2 45 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0886-6236 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD JUN PY 1996 VL 10 IS 2 BP 297 EP 306 DI 10.1029/96GB00470 PG 10 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA UP378 UT WOS:A1996UP37800008 ER PT J AU Hou, TH Bryant, RG AF Hou, TH Bryant, RG TI Processing and properties of IM7/LARC(TM)-SCI composite SO HIGH PERFORMANCE POLYMERS LA English DT Article AB LARC(TM)-SCI (Langley Research Center - Semi-Crystaline polyImide) is an aromatic polyimide based on 3,4'-oxydianiline and 3,3',4,4'-biphenyl tetracarboxylic dianhydride. This polyimide was synthesized and evaluated for use as a neat resin and a matrix resin for advanced composites. Three 30% w/w solids polyamic acid/N-methypyrrolidone solutions were prepared using 2, 3 and 4% stoichiometric imbalances end-capped with phthalic anhydride to provide polyimides with theoretical number average molecular weights of approximately 22 800, 15 100 and 11 400 g mol(-1) respectively. Unidirectional IM7 carbon fibre prepreg was prepared from these three resins using the Langley multipurpose tape machine. Thermal and rheological properties and the solvent/volatile depletion rates along with crystallization kinetics were characterized for the resin scraps taken from the prepreg tapes. Processing characteristics of the LARC(TM)-SCI resin were thoroughly understood from these results, and a workable moulding cycle was designed for this composite. Composite laminates were moulded at 410 degrees C at either 200 or 300 psi, which consistently yielded good consolidation and high-quality panels as measured by C-scan, acid digestion and optical photomicrography. The composite mechanical properties were also obtained. Short beam shear strength was 15 ksi at RT. Longitudinal flexural strength was 295 ksi at RT and 200 ksi at 177 degrees C. Excellent fracture toughness of 6.9 in-lb/in(2) was obtained. Excellent values of transverse flexural strength and longitudinal tensile strength indicated a good translation of fibre properties int the composite. Un-notched longitudinal compression strength of 163 ksi was comparable to typical thermoplastic composites. An open hole compression strength of 55 ksi suggested good damage tolerance for this composite. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 11 TC 5 Z9 5 U1 0 U2 5 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD JUN PY 1996 VL 8 IS 2 BP 169 EP 184 DI 10.1088/0954-0083/8/2/002 PG 16 WC Polymer Science SC Polymer Science GA UV188 UT WOS:A1996UV18800002 ER PT J AU Kary, DM Dones, L AF Kary, DM Dones, L TI Capture statistics of short-period comets: Implications for Comet D/Shoemaker-Levy 9 SO ICARUS LA English DT Article ID RESTRICTED 3-BODY PROBLEM; SATELLITE CAPTURE; NUCLEUS; ASTEROIDS; EVOLUTION; DYNAMICS; ORIGIN AB Comet D/Shoemaker-Levy 9 orbited Jupiter for decades (P. W. Chodas and D. K. Yeomans 1995, Bull. Am. Astron. Sec. 27, 1111-1112; L. A. M. Benner and W. B. McKinnon 1995, Icarus 118, 155-168) and was tidally disrupted during the orbit before impact. To estimate the rate of such events and to infer the implications for the comet's previous orbit, we have performed numerical integrations of test particles with orbits similar to those of Jupiter-family comets. We follow the dynamical evolution of 49,000 synthetic comets for similar to 10(5) years and find 10,089 captures in which a comet completed more than one full orbit around Jupiter. Of these Jupiter-orbiting comets (''orbiters''), one in 112 undergoes a long capture, an event in which the comet orbits Jupiter for over 50 years. Captured bodies with mean orbital periods >3.5 years generally have jovicentric inclinations >120 degrees and large perijove distances, while bodies with shorter orbital periods have smaller inclinations and are more likely to approach Jupiter closely. Long captures are more likely to include very close approaches to Jupiter. For example, long captures make up roughly one event in 15 in which an orbiter passes within 2.4R(J) (Jupiter radii) of Jupiter's center (without immediately impacting the planet). Thus, if passage within similar to 2.4R(J) makes a comet observable by causing mass loss, the bias in favor of long capture events is a factor of eight over the general population of Jupiter-orbiting comets. About 15% of the comets that hit Jupiter are orbiting the planet at impact; approximately 1% impact after orbiting for more than 50 years. We infer that a l-km comet impacts Jupiter once every 30-500 years, with a most probable interval of 240 years. Comets in orbit about Jupiter impact once every (0.2-3.5) x 10(3) years; orbiting comets impact one orbit after tidal disruption once every (0.1-2) x 10(5) years. (C) 1996 Academic Press, Inc. C1 SAN JOSE STATE UNIV FDN,NASA,MOFFETT FIELD,CA 94035. RP Kary, DM (reprint author), UNIV CALIF SANTA BARBARA,DEPT PHYS,SANTA BARBARA,CA 93106, USA. NR 79 TC 34 Z9 34 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1996 VL 121 IS 2 BP 207 EP 224 DI 10.1006/icar.1996.0082 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP571 UT WOS:A1996UP57100002 ER PT J AU Asphaug, E Benz, W AF Asphaug, E Benz, W TI Size, density, and structure of Comet Shoemaker-Levy 9 inferred from the physics of tidal breakup SO ICARUS LA English DT Article ID DISRUPTION; PLANETESIMALS; NUCLEUS; BODIES; ORIGIN AB Detailed consideration of possible fragmentation mechanisms shows that Comet Shoemaker-Levy 9 (SL9) had negligible effective strength, even in comparison with tide and self-gravity, by the time it attained perijove in 1992, This reduces the tidal physics to a computable basis: we model the elongation of this ''rubble-pile,'' and the onset of the instability which created a chain of gravitationally bound clumps, using an N-body code with self-gravity and simple collisions, Gravitational clumping depends only on the density rho(c) of the progenitor (for a given orbit), and chain length then scales linearly with initial diameter d(c). We thus constrain from chain morphology that rho(c) approximate to 0.6 g cm(-3) and from chain length that d(c) approximate to 1.5 km, Our numerical results accurately match analytical derivations for the threshold of tidal breakup, and lead to general relations for erosion and disruption of strengthless or regolith-covered bodies, For a given random encounter, we show that a rubble-pile comet, or one mantled in deep regolith, is half as likely to be destroyed by tides as it is to impact an outer planet, Because of their similar density ratio, the same holds true for rubble-pile asteroids encountering terrestrial planets. Split comets such as SL9 near Saturn are unlikely: the required periapses intersect the planet. (C) 1996 Academic Press, Inc. C1 UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. OBSERV GENEVA,CH-1290 SAUVERNY,SWITZERLAND. RP Asphaug, E (reprint author), NASA,AMES RES CTR,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 79 TC 174 Z9 174 U1 0 U2 5 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1996 VL 121 IS 2 BP 225 EP 248 DI 10.1006/icar.1996.0083 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP571 UT WOS:A1996UP57100003 ER PT J AU Schenk, PM Asphaug, E McKinnon, WB Melosh, HJ Weissman, PR AF Schenk, PM Asphaug, E McKinnon, WB Melosh, HJ Weissman, PR TI Cometary nuclei and tidal disruption: The geologic record of crater chains on Callisto and Ganymede SO ICARUS LA English DT Article ID HISTORY; IMPACT AB Prominent crater chains on Ganymede and Callisto are most likely the impact scars of comets tidally disrupted by Jupiter and are not secondary crater chains, We have examined the morphology of these chains in detail in order to place constraints on the properties of the comets that formed them and the disruption process. In these chains, intercrater spacing varies by no more than a factor of 2 and the craters within a given chain show almost no deviation from linearity (although the chains themselves are on gently curved small circles). All of these crater chains occur on or very near the Jupiter-facing hemisphere, For a given chain, the estimated masses of the fragments that formed each crater vary by no more than an order of magnitude. The mean fragment masses for all the chains vary by over four orders of magnitude (W. B, McKinnon and P. M. Schenk 1995, Geophys. Res. Left. 13, 1829-1832), however. The mass of the parent comet for each crater chain is not correlated with the number of fragments produced during disruption but is correlated with the mean mass of the fragments produced in a given disruption event. Also, the larger fragments are located near the center of each chain. All of these characteristics are consistent with those predicted by disruption simulations based on the rubble pile cometary nucleus model (in which nuclei are composed on numerous small fragments weakly bound by self-gravity), and with those observed in Comet D/Shoemaker-Levy 9. Similar crater chains have not been found on the other icy satellites, but the impact record of disrupted comets on Callisto and Ganymede indicates that disruption events occur within the Jupiter system roughly once every 200 to 400 years, (C) 1996 Academic Press,Inc. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. WASHINGTON UNIV, DEPT EARTH & PLANETARY SCI, ST LOUIS, MO 63130 USA. WASHINGTON UNIV, MCDONNELL CTR SPACE SCI, ST LOUIS, MO 63130 USA. UNIV ARIZONA, LUNAR & PLANETARY LAB, TUCSON, AZ 85721 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP Schenk, PM (reprint author), LUNAR & PLANETARY INST, 3600 BAY AREA BLVD, HOUSTON, TX 77058 USA. NR 51 TC 25 Z9 26 U1 1 U2 5 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1996 VL 121 IS 2 BP 249 EP 274 DI 10.1006/icar.1996.0084 PG 26 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP571 UT WOS:A1996UP57100004 ER PT J AU Weissman, PR AF Weissman, PR TI If it quacks like a comet SO ICARUS LA English DT Article ID NUCLEI; P/HALLEY; HALLEY AB Some researchers have interpreted the failure to detect gas emission in the coma of Comet Shoemaker-Levy 9 as suggesting that the SL-9 fragments were not active as they orbited Jupiter. Detailed thermal modeling of the cometary fragments is performed to show that the expected gas production rates are significantly below the upper limits set by observers. Thus, the comet could easily have been active. Additional evidence is provided to suggest that the comet fragments were indeed active. Comet Shoemaker-Levy 9 was a comet. (C) 1996 Academic Press, Inc. RP Weissman, PR (reprint author), CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,MAIL STOP 183-601,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 36 TC 8 Z9 8 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1996 VL 121 IS 2 BP 275 EP 280 DI 10.1006/icar.1996.0085 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP571 UT WOS:A1996UP57100005 ER PT J AU Hahn, JM Rettig, TW Mumma, MJ AF Hahn, JM Rettig, TW Mumma, MJ TI Comet Shoemaker-Levy 9 dust SO ICARUS LA English DT Article AB Comet Shoemaker-Levy 9 (S-L 9) was imaged with the Hubble Space Telescope from January 1994, through solar opposition on April 29, and until impact in July 1994. As noted by several observers, no anti-sunward dust tails were detected east of the fragments after opposition (D. Jewitt and J. Chen 1994, Periodic Comet Shoemaker-Levy 9 (1993e), IAU Circular 5924; Z. Sekanina, P. W. Chodas, and D. K. Yeomans 1994, Astron. Astrophys. 289, 607-636; H. A. Weaver et al. 1994, Science 263, 787-791; G. P. Chernova, N. N. Kiselev, and K. Jockers 1995, in European SL-9/Jupiter Workshop (R. West and H. Bohnhardt, Eds.), pp. 11-16, ESO Conference and Workshop Proceedings No. 52), a fact from which some have concluded that the S-L 9 fragments were inactive (e.g., Sekanina ef al. 1994, Weaver et al. 1994, Chernova et al. 1995). However surface brightness profiles of the brighter fragments G(1), H, K, L, and S comae suggest the opposite. Images acquired during January and March 1994 show the brighter S-L 9 fragments' azimuthally averaged brightness profiles varied as rho(-1.1+/-0.1) in the inner rho less than or similar to 1'' comae and rho(-1.5+/-0.2) in the outer rho greater than or similar to 1'' comae, where rho is the projected distance from a coma photocenter. These profiles are consistent with active comet fragments surrounded by dust comae disturbed by radiation pressure. However inactive comet models, which assume the dust was created during a burst of activity immediately following breakup, produce comae that remain highly elongated along the fragment axis throughout their orbit. This type of coma morphology was not observed. Simulations of an active, dust-producing comet in S-L 9's orbit are presented. Comparisons of models with observations show that the dominant light-reflecting grains in the S-L 9 comae and tails had radii ranging between about 5 and 500 mu m emitted from the fragments at outflow velocities of order 1 m/sec. The models show radiation pressure swept the dust into tails which appeared west of the fragments both before and after solar opposition. As the fragments neared Jupiter in late June 1994, the combined effects of the jovian tide and radiation pressure distorted the dust tails into broad fans that consisted of grains larger than R greater than or similar to 100 mu m and were oriented along the Jupiter-comet direction. The smaller R less than or similar to 100 mu m grains were confined to narrower tails whose projected orientation near the nucleus were approximately in the direction of Jupiter. The additional light contributed by the smaller grains caused the S-L 9 dust to appear brighter on the jovian side than the trailing side of the dust fans. (C) 1996 Academic Press,Inc. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP Hahn, JM (reprint author), UNIV NOTRE DAME,DEPT PHYS,NOTRE DAME,IN 46556, USA. RI mumma, michael/I-2764-2013 NR 41 TC 12 Z9 12 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1996 VL 121 IS 2 BP 291 EP 304 DI 10.1006/icar.1996.0087 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP571 UT WOS:A1996UP57100007 ER PT J AU Mosser, B Galdemard, P Lagage, P Pantin, E Sauvage, M Lognonne, P Gautier, D Billebaud, F Livengood, T Kaufl, HU AF Mosser, B Galdemard, P Lagage, P Pantin, E Sauvage, M Lognonne, P Gautier, D Billebaud, F Livengood, T Kaufl, HU TI Impact seismology: A search for primary pressure waves following impacts A and H SO ICARUS LA English DT Article AB This paper reports part of the seismic observations performed after the impacts of Shoemaker-Levy 9 fragments A and H with the mid-IR camera TIMMI at the ESO 3.6-m telescope, Hodograms have been computed to search for the seismic signature of the primary waves crossing the planet within 2 hr following each impact, The hodogram analysis has been unable to detect any seismic signal, In order to put a limit on the kinetic energy of the fragments, the synthetic thermal signature of the primary wave has been calculated as a function of the incident energy, according to theoretical simulations, and taking into account observational conditions such as the point spread function, The non-detection implies that the kinetic energy of impacts A and H was less than 2 x 10(21) J, within the frame of the theoretical simulation of Lognonne et al, (Lognonne, Ph., B, Mosser, and F, Dahlen 1994, Icarus 110, 180-195.), The error bar is as large as one order of magnitude, according to other simulations, The seismic wave should have contributed to a non-negligible part of the heating of the region surrounding the impacts, but it is not yet possible to measure its contribution. (C) 1996 Academic Press, Inc. C1 CENS,CEA,DSM,DAPNIA,SAP,F-91191 GIF SUR YVETTE,FRANCE. INST PHYS GLOBE,DEPT SISMOL,F-75252 PARIS 05,FRANCE. OBSERV PARIS,DESPA,F-92195 MEUDON,FRANCE. EUROPEAN SPACE AGCY,ESTEC,DEPT SPACE SCI,NL-2200 AG NOORDWIJK,NETHERLANDS. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. EUROPEAN SO OBSERV,D-81827 GARCHING,GERMANY. RP Mosser, B (reprint author), INST ASTROPHYS PARIS,98B,BLVD ARAGO,F-70514 PARIS,FRANCE. RI Lognonne, Philippe/F-8846-2010; Livengood, Timothy/C-8512-2012 NR 25 TC 11 Z9 11 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1996 VL 121 IS 2 BP 331 EP 340 DI 10.1006/icar.1996.0091 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP571 UT WOS:A1996UP57100011 ER PT J AU Chanover, NJ Kuehn, DM Banfield, D Momary, T Beebe, RF Baines, KH Nicholson, PD Simon, AA Murrell, AS AF Chanover, NJ Kuehn, DM Banfield, D Momary, T Beebe, RF Baines, KH Nicholson, PD Simon, AA Murrell, AS TI Absolute reflectivity spectra of Jupiter: 0.25-3.5 micrometers SO ICARUS LA English DT Article ID SOLAR-RADIATION AB The world-wide observing campaign of the Comet P/Shoemaker-Levy 9 (SL9) impacts into Jupiter during July 1994 has led to an unprecedented quantity of imaging data, predominantly in the visible to near-infrared wavelength regime. In an effort to provide reference brightness values for Jupiter at all latitudes, we present a compilation of absolute reflectivity scans along the jovian central meridian during the impact epoch. Images from both Earth-orbiting and ground-based telescopes were photometrically calibrated and analyzed to provide as much spatial resolution and wavelength coverage as possible. This fundamental reference will be made available to the entire planetary science community as a means to photometrically reduce uncalibrated data from the SL9 impacts via the Planetary Data System (PDS). Until the entire data set is ingested into the PDS, it will be available through a World Wide Web site and the AAS CD-ROM series. (C) 1996 Academic Press, Inc. C1 PITTSBURG STATE UNIV,DEPT PHYS,PITTSBURG,KS 66762. CORNELL UNIV,DEPT ASTRON,ITHACA,NY 14853. CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. RP Chanover, NJ (reprint author), NEW MEXICO STATE UNIV,DEPT ASTRON,DEPT 4500,BOX 30001,LAS CRUCES,NM 88003, USA. RI Simon, Amy/C-8020-2012; OI Simon, Amy/0000-0003-4641-6186; Banfield, Don/0000-0003-2664-0164 NR 19 TC 20 Z9 20 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1996 VL 121 IS 2 BP 351 EP 360 DI 10.1006/icar.1996.0093 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP571 UT WOS:A1996UP57100013 ER PT J AU Banfield, D Gierasch, PJ Squyres, SW Nicholson, PD Conrath, BJ Matthews, K AF Banfield, D Gierasch, PJ Squyres, SW Nicholson, PD Conrath, BJ Matthews, K TI 2 mu m spectrophotometry of Jovian stratospheric aerosols - Scattering opacities, vertical distributions, and wind speeds SO ICARUS LA English DT Article ID INFRARED-ABSORPTION SPECTRA; H-2-HE PAIRS; TEMPERATURES; MODEL; BAND AB Narrow-band 2.0-2.35 mu m spectrophotometric observations of Jupiter at nine wavelengths were taken with the 5-m Hale Telescope at Palomar during the month following the impact of Comet P/Shoemaker-Levy 9, Spectra were obtained for the principal impact sites, and also for regions not affected by the comet impacts (the South Polar Region, North Equatorial Zone, South Equatorial Zone, and the Great Red Spot). A technique by which near-infrared reflection spectra can be inverted to yield vertical profiles of scatterer density is presented, For our wavelengths and bandwidths, the sensitivity of the inversions extends from pressure levels near 1 bar up to about 20 mbar. We find that all comet-induced aerosol clouds lie near or above the vertical limit of our sensitivity, i.e., 20 mbar, The lower limit of the clouds is around 50 mbar, The total scattering opacity of the clouds decreased by a factor of about 1.7 over the 35 days spanned by these observations, while the area covered by them increased by a factor of about 1.5, West et al, (West, R. A., E. Karkoschka, A, J, Friedson, M. Seymour, K, H, Baines, and H, B, Hammel 1995. Science 267, 1296-1301.) suggest particle coagulation during this time which fits with our observations, but particle fallout is also likely, All the aerosols comprise a volume the equivalent of a similar to 0.6-km radius sphere assuming a particle size of 0.25 mu m. We also measured the drift speeds of these clouds using two different techniques, One involved scaling down Voyager-measured cloud-top winds (Limaye, S. S. 1986, Icarus 65, 335-352.) and deforming early images to match later images, while the other involved directly cross-correlating longitudinally shifted images of spots from different times. Both techniques indicate wind speeds of order 5 m/sec, or similar to 30% of the tropospheric wind speeds measured by Voyager in this region. (C) 1996 Academic Press, Inc. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. CALTECH,PASADENA,CA 91125. RP Banfield, D (reprint author), CORNELL UNIV,DEPT ASTRON,ITHACA,NY 14853, USA. OI Banfield, Don/0000-0003-2664-0164 NR 17 TC 32 Z9 32 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1996 VL 121 IS 2 BP 389 EP 410 DI 10.1006/icar.1996.0095 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP571 UT WOS:A1996UP57100015 ER PT J AU Bjoraker, GL Stolovy, SR Herter, TL Gull, GE Pirger, BE AF Bjoraker, GL Stolovy, SR Herter, TL Gull, GE Pirger, BE TI Detection of water after the collision of fragments G and K of Comet Shoemaker-Levy 9 with Jupiter SO ICARUS LA English DT Article ID VAPOR; ABUNDANCE AB We observed Jupiter on 17-19 July 1994 using NASA's Kuiper Airborne Observatory (KAO) deployed out of Melbourne, Australia. The KAO Echelle Grating Spectrograph (KEGS) uses an array detector with 128 spectral elements and 20 spatial elements. The spectral resolution was 0.19 cm(-1), equivalent to a resolving power of 6800, We detected three H2O emission lines near 7.7 mu m as well as numerous emission features of CH4. At the peak of the fallback phase for the ejecta from the G and K fragments, we infer temperatures between 1000 and 1200 K at the 3-mu bar pressure level on Jupiter. The H2O lines at 7.7 mu m were visible for only about 10 to 20 min. We obtained line-of-sight abundances of H2O for both G and K of 1.0 to 1.5 x 10(18) cm(-2). The inferred mass of H2O in each fragment ranges from 1.4 to 2.8 x 10(12) g, equivalent to spheres of ice 140 to 180 m in diameter at unit density. This should be considered a lower limit to H2O as the 7.7-mu m data are sensitive only to the hottest component of water. The G and K impact sites exhibited remarkably similar spectra at the time of peak infrared emission about 14 min after impact. The inferred abundance of H2O at this time was comparable to that of CH4. We interpret the observed CH4 emission as due to heating of preexisting jovian CH4 in the upper stratosphere. Water in the impact sites can be explained by shock chemistry provided that the C/O ratio is less than 1. Our observations are consistent with a scenario in which oxygen-rich cometary material combines with jovian H-2 to produce H2O during the fallback phase. Combining our observations with spectra acquired from the Near Infrared Mapping Spectrometer on the Galileo spacecraft, we do not believe that the fragments reached the 6-bar level in order to excavate jovian water. (C) 1996 Academic Press, Inc. C1 CORNELL UNIV, DEPT ASTRON, ITHACA, NY 14853 USA. RP Bjoraker, GL (reprint author), NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, GREENBELT, MD 20771 USA. RI Bjoraker, Gordon/D-5032-2012 NR 25 TC 27 Z9 27 U1 0 U2 1 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1996 VL 121 IS 2 BP 411 EP 421 DI 10.1006/icar.1996.0096 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP571 UT WOS:A1996UP57100016 ER PT J AU Brooke, TY Orton, GS Crisp, D Friedson, AJ Bjoraker, GL AF Brooke, TY Orton, GS Crisp, D Friedson, AJ Bjoraker, GL TI Near-infrared spectroscopy of the Shoemaker-Levy 9 impact sites with UKIRT: CO emission from the L site and additional 5-mu m spectra SO ICARUS LA English DT Article ID VIBRATIONAL DEACTIVATION; GAS-COMPOSITION; JUPITER; ATMOSPHERE; ARSINE; SATURN AB CO emission lines in the 4.7-mu m fundamental vibrational band were detected from Jupiter at the Shoemaker-Levy 9 fragment L impact site on July 20, 1994 UT, 4 to 5 hr after impact. For an atmospheric model with a single temperature for the emitting CO, which is assumed to be in local thermodynamic equilibrium (LTE), the CO temperature is estimated to be T(CO) = 280 +/- 10 K. For this case, the CO column density is N(CO) = 1.2 x 10(17) cm(-2) and the estimated mass of CO in the L site is 1.6 x 10(13) g, with uncertainties of a factor five. The oxygen in this mass of CO can be plausibly explained as coming from material originally in the impactor, Larger amounts of cool CO below the emitting CO could have been present, however, The possible departure of the CO vibrational level populations from LTE and the effect on abundance estimates are discussed qualitatively. Spectra of other impact sites taken at times on the order of days after impact show no detectable changes in the CO absorption lines of impact sites vs nonimpact sites. (C) 1996 Academic Press, Inc. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Brooke, TY (reprint author), CALTECH,JET PROP LAB,MS 169-237,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Bjoraker, Gordon/D-5032-2012 NR 35 TC 11 Z9 11 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1996 VL 121 IS 2 BP 422 EP 430 DI 10.1006/icar.1996.0097 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP571 UT WOS:A1996UP57100017 ER PT J AU Kostiuk, T Buhl, D Espenak, F Romani, P Bjoraker, G Fast, K Livengood, T Zipoy, D AF Kostiuk, T Buhl, D Espenak, F Romani, P Bjoraker, G Fast, K Livengood, T Zipoy, D TI Stratospheric ammonia on Jupiter after the SL9 collision SO ICARUS LA English DT Article ID JOVIAN AURORAL STRATOSPHERE; ETHANE; TEMPERATURE; REGION; BAND; ABUNDANCES; PROBE AB We report results from measurements of NH3 emission lines from the stratosphere of Jupiter following the impacts of fragments of Comet P/Shoemaker-Levy 9. Measurements were taken at the NASA Infrared Telescope Facility on 29 July 1994 on two impact regions, Q1 and the RSG complex, similar to 8 days after the impacts, Emission line profiles were obtained near 11.2 mu m at sub-Doppler spectral resolution (lambda/Delta lambda similar to 10(6)). The measurements of the lineshapes permit the retrieval of NH3 abundance and provide constraints on its altitude distribution in the stratosphere. If a uniformly mixed altitude distribution is assumed above the tropopause, the retrieved NH3 mole fractions are 7.8 +/- 1.6 x 10(-9) for the Q1 impact region and 4 +/- 0.8 x 10(-9) for the RSG impact region. The total derived mass of NH3, similar to 4 x 10(12) g within our field of view, is approximately 20 times greater than that possible from cometary origin. Near the Q1 impact site, ammonia emission is found to originate primarily from altitudes above the 10 mbar level, with a mole fraction of 18 +/- 4 x 10(-9) corresponding to a column abundance of 2 +/- 0.4 x 10(16) cm(-2). Results are compared with other infrared and ultraviolet measurements and with recent photochemical models for jovian stratospheric NH3. These comparisons provide evidence for the presence of haze up to the 10 mbar level and provide an initial data set for study of the temporal behavior of NH3 in the stratosphere of Jupiter. (C) 1996 Academic Press, Inc. C1 UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. RP Kostiuk, T (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,PLANETARY SYST BRANCH,GREENBELT,MD 20771, USA. RI Livengood, Timothy/C-8512-2012; Romani, Paul/D-2729-2012; Bjoraker, Gordon/D-5032-2012; Kostiuk, Theodor/A-3077-2014 NR 34 TC 20 Z9 20 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1996 VL 121 IS 2 BP 431 EP 441 DI 10.1006/icar.1996.0098 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP571 UT WOS:A1996UP57100018 ER PT J AU Rubin, BC Fishman, GJ Harmon, BA Waite, JH Link, R Zhang, SN Brainerd, JJ Pendleton, GN Meegan, CA Paciesas, WS AF Rubin, BC Fishman, GJ Harmon, BA Waite, JH Link, R Zhang, SN Brainerd, JJ Pendleton, GN Meegan, CA Paciesas, WS TI Limits on hard X-ray emission from the Comet Shoemaker-Levy 9 impact on Jupiter SO ICARUS LA English DT Article ID JOVIAN AURORAL ELECTRONS AB Data from the burst and transient source experiment (BATSE) onboard the Compton Gamma-Ray Observatory (CGRO) have been used to set upper limits on emission in the 20-1800 keV energy range from the collision of Comet Shoemaker-Levy 9 with Jupiter. For an impulsive event of 1 sec duration we place a 4 sigma upper limit on the equivalent isotropic energy release of 5 x 10(20) ergs in the 20-50 keV energy band. The upper limit on steady emission observed during the week of the collision is 2 x 10(19) erg/sec (20-50 keV). We discuss the implications of these observations for impact effects on the jovian atmosphere. (C) 1996 Academic Press, Inc. C1 UNIV SPACE RES ASSOC,HUNTSVILLE,AL. SW RES INST,DEPT SPACE SCI,SAN ANTONIO,TX 77228. UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. RP Rubin, BC (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES-84,HUNTSVILLE,AL 35812, USA. NR 23 TC 0 Z9 0 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1996 VL 121 IS 2 BP 479 EP 483 DI 10.1006/icar.1996.0103 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP571 UT WOS:A1996UP57100023 ER PT J AU Hofland, LM Stofel, EJ Taenaka, RK AF Hofland, LM Stofel, EJ Taenaka, RK TI Galileo probe Li-SO2 battery cell life testing SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB Several hundred D-sized, Li-SO2 battery cells have been in a carefully controlled quiescent storage test for up to 14 years, starting at Honeywell but completing at the NASA Ames Research Center, in support of the Atmospheric Probe portion of the Galileo Mission to the planet Jupiter. This population of cells includes similar samples from 8 different manufacturing lots; the earliest from October 1981, the latest from October 1988. The baseline samples have been divided among several storage chambers, each having its own constant temperature, respectively, set between 0 degrees C to 40 degrees C. Non-invasive measurements have been made repeatedly of open circuit voltage and internal resistance (at 1000 Hz). At intervals, a small portion of the cells has been removed from storage and fully discharged under repetitive conditions, thus assessing ally storage related loss of discharge capacity. The results show that for storage up to 20 degrees C the cells have excellent stability. Above 20 degrees C noticeable degradation occurs. C1 HUGHES SPACE & COMMUN CO,EL SEGUNDO,CA 90245. RP Hofland, LM (reprint author), SVERDRUP TECHNOL INC,NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 3 TC 0 Z9 0 U1 2 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD JUN PY 1996 VL 11 IS 6 BP 14 EP 18 DI 10.1109/62.500205 PG 5 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA UN431 UT WOS:A1996UN43100004 ER PT J AU FallahAdl, H JaJa, J Liang, SL Townshend, J Kaufman, Y AF FallahAdl, H JaJa, J Liang, SL Townshend, J Kaufman, Y TI Fast algorithms for removing atmospheric effects from satellite images SO IEEE COMPUTATIONAL SCIENCE & ENGINEERING LA English DT Article ID RADIATIVE-TRANSFER AB Remote-sensing satellites collect vast amounts of earth data, but correcting for the atmospheric effects that contaminate the imagery is computationally intensive. Using previous codes, high-accuracy atmospheric correction of a standard regional image area would have taken years on a workstation. An improved algorithm takes 13 minutes. It also parallelizes well. C1 UNIV MARYLAND, INST ADV COMP STUDIES, COLLEGE PK, MD 20742 USA. NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. RI liang, shunlin/C-2809-2015 NR 21 TC 11 Z9 12 U1 0 U2 3 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1070-9924 J9 IEEE COMPUT SCI ENG JI IEEE Comput. Sci. Eng. PD SUM PY 1996 VL 3 IS 2 BP 66 EP 77 DI 10.1109/99.503316 PG 12 WC Computer Science, Theory & Methods; Engineering, Electrical & Electronic; Mathematics, Applied SC Computer Science; Engineering; Mathematics GA UR190 UT WOS:A1996UR19000022 ER PT J AU Sadr, R Shah, B Hinedi, S AF Sadr, R Shah, B Hinedi, S TI Design of wideband all-digital phase locked loops using multirate digital filter banks SO IEEE TRANSACTIONS ON COMMUNICATIONS LA English DT Article AB All-digital phase locked loops (DPLL's) have many advantages over analog loops. However, due to digital device limitations and costs, superwide PLL's with front-end bandwidths as high as one gigahertz are commonly implemented using analog parts. This article presents a new architecture that allows an all-digital implementation of superwide PLL's, The problem of operating digital components at high speed is avoided here (without reducing the front-end bandwidths) by inserting a multirate digital filter bank in front of the DPLL. The new design is shown to have steady-state and transient performance that is identical to a conventional DPLL. RP Sadr, R (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0090-6778 J9 IEEE T COMMUN JI IEEE Trans. Commun. PD JUN PY 1996 VL 44 IS 6 BP 663 EP 667 DI 10.1109/26.506382 PG 5 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA UQ224 UT WOS:A1996UQ22400007 ER PT J AU Jalink, A McAdoo, J Halama, G Liu, H AF Jalink, A McAdoo, J Halama, G Liu, H TI CCD mosaic technique for large-field digital mammography SO IEEE TRANSACTIONS ON MEDICAL IMAGING LA English DT Article ID CHARGE-COUPLED-DEVICE; RADIOGRAPHY; ARRAYS AB We present a novel technique for large-field digital mammography. The instrument uses a mosaic of electronic digital imaging [charge coupled device (CCD)] arrays, novel area scanning, and a radiation exposure and scatter reducing mechanism, The imaging arrays are mounted on a carrier platform in a checker-board pattern mosaic. To fill in the gaps between array-active areas the platform is repositioned three times and four X-ray exposures are made, The multiple image areas are then recombined by a digital computer to produce a composite image of the entire region, To reduce X-ray scatter and exposure, a lead aperture plate is interposed between X-ray source and patient, The aperture plate has a mosaic of square holes in alignment with the imaging array pattern and the plate is repositioned in synchronism with the carrier platform, We discuss proof-of-concept testing demonstrating technical feasibility of our approach, The instrument should be suitable for incorporation into standard mammography units, Unique features of the new technique are: large field coverage (18 x 24 cm); high spatial resolution (14-17 lp/mm); scatter rejection; and excellent contrast characteristics and lesion detectability under clinical conditions. C1 SCI APPLICAT INT CORP,HAMPTON,VA 23669. UNIV VIRGINIA,CHARLOTTESVILLE,VA 22903. RP Jalink, A (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 30 TC 23 Z9 23 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0278-0062 J9 IEEE T MED IMAGING JI IEEE Trans. Med. Imaging PD JUN PY 1996 VL 15 IS 3 BP 260 EP 267 DI 10.1109/42.500135 PG 8 WC Computer Science, Interdisciplinary Applications; Engineering, Biomedical; Engineering, Electrical & Electronic; Imaging Science & Photographic Technology; Radiology, Nuclear Medicine & Medical Imaging SC Computer Science; Engineering; Imaging Science & Photographic Technology; Radiology, Nuclear Medicine & Medical Imaging GA UN483 UT WOS:A1996UN48300004 PM 18215907 ER PT J AU BoricLubecke, O Pan, DS Itoh, T AF BoricLubecke, O Pan, DS Itoh, T TI DC instability of the series connection of tunneling diodes SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID OSCILLATIONS; GHZ AB An oscillator with a series connection of tunneling diodes produces significantly higher power than a single diode oscillator, However, a circuit with series-connected tunneling diodes biased simultaneously in the negative differential resistance (NDR) region of the I-V curve is de unstable, This de instability makes the series connection oscillator fundamentally different from a single diode oscillator. Associated with the de instability are the phenomena of minimum oscillation amplitude and frequency, Due to the minimum oscillation amplitude, it is critical to provide the impedance match between the oscillator circuit and the series connection at the desired oscillation amplitude level, An in depth, comprehensive analysis of the de instability is given here, Based on this analysis, a numerical procedure is developed to accurately predict the minimum oscillation amplitude and frequency, Time domain simulations which give further insight into series-connection oscillator behavior are discussed, The effect of increasing the number of diodes on the oscillator performance is explored as well, Based on numerical and simulation results, oscillators with several tunnel diodes connected in series were designed and tested, Experimental results that confirm the existence of the minimum oscillation amplitude are presented for oscillators with two, three, and four tunnel diodes. C1 UNIV CALIF LOS ANGELES,DEPT ELECT ENGN,LOS ANGELES,CA 90024. RP BoricLubecke, O (reprint author), NASA,JPL,PASADENA,CA 91109, USA. NR 21 TC 5 Z9 5 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1996 VL 44 IS 6 BP 936 EP 943 DI 10.1109/22.506454 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA UQ576 UT WOS:A1996UQ57600019 ER PT J AU Padin, S Woody, DP Stern, JA LeDuc, HG Blundell, R Tong, CYE Pospieszalski, MW AF Padin, S Woody, DP Stern, JA LeDuc, HG Blundell, R Tong, CYE Pospieszalski, MW TI An integrated SIS mixer and HEMT IF amplifier SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID RECEIVERS; NOISE AB Design details are given for a 205-270 GHz fixed-tuned SIS receiver in which the SIS mixer and HEMT IF amplifier are integrated into a single compact unit, The mixer and IF amplifier are connected with an inductor which provides the reactive part of the optimum input impedance for the HEMT. This simple coupling circuit gives an IF bandwidth of similar to 4 GHz. The receiver has a DSB noise temperature in the range 35-80K over the 205-270 GHz local oscillator band and 0.5-4.5 GHz IF band. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. RP Padin, S (reprint author), CALTECH,OWENS VALLEY RADIO OBSERV,PASADENA,CA 91125, USA. OI Tong, Edward/0000-0002-7736-4203 NR 10 TC 20 Z9 20 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1996 VL 44 IS 6 BP 987 EP 990 DI 10.1109/22.506643 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA UQ576 UT WOS:A1996UQ57600030 ER PT J AU Moran, A LaBell, K Gates, M Seidleck, C McGraw, R Broida, M Firer, J Sprehn, S AF Moran, A LaBell, K Gates, M Seidleck, C McGraw, R Broida, M Firer, J Sprehn, S TI Single event effect testing of the intel 80386 family and the 80486 microprocessor SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 3rd European Symposium on Radiation and Its Effects on Components and Systems (RADECS 95) CY SEP 18-22, 1995 CL ARCACHON, FRANCE SP CNES, RADECS Assoc, IEEE, Nucl & Plasma Sci Soc AB We present single event effect test results for the Intel 80386 microprocessor, the 80387 coprocessor, the 82380 peripheral device, and on the 80486 microprocessor. Both single event upset and latchup conditions were monitored. C1 HUGHES ST SYST,GREENBELT,MD 20771. JACKSON & TULL,GREENBELT,MD 20771. DAEDALIAN SYST CORP,GREENBELT,MD 20771. LYSTAD LTD,CROWNSVILLE,MD 21032. RP Moran, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 7351,GREENBELT,MD 20771, USA. NR 6 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1996 VL 43 IS 3 BP 879 EP 885 DI 10.1109/23.510728 PN 1 PG 7 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA UT042 UT WOS:A1996UT04200018 ER PT J AU Mouret, I Calvet, MC Calvel, P Tastet, P Allenspach, M LaBel, KA Titus, JL Wheatley, CF Schrimpf, RD Galloway, KF AF Mouret, I Calvet, MC Calvel, P Tastet, P Allenspach, M LaBel, KA Titus, JL Wheatley, CF Schrimpf, RD Galloway, KF TI Experimental evidence of the temperature and angular dependence in SEGR SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 3rd European Symposium on Radiation and Its Effects on Components and Systems (RADECS 95) CY SEP 18-22, 1995 CL ARCACHON, FRANCE SP CNES, RADECS Assoc, IEEE, Nucl & Plasma Sci Soc ID POWER MOSFETS AB The temperature and angular dependence of Single-Event Gate Rupture (SEGR) experiments show that a normal incident favors SEGR and elevated temperature is insignificant. Both the oxide and substrate response play a major role in determining the SEGR sensitivity. C1 AEROSPATIALE,LES MUREAUX,FRANCE. UNIV ARIZONA,TUCSON,AZ 85721. ALCATEL ESPACE,TOULOUSE,FRANCE. CTR NATL ETUD SPATIALES,F-31055 TOULOUSE,FRANCE. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. USN,CTR SURFACE WARFARE,CRANE,IN 47522. RR2,DRUMS,PA 18222. RP Mouret, I (reprint author), MOTOROLA SEMICOND,TOULOUSE,FRANCE. RI Schrimpf, Ronald/L-5549-2013 OI Schrimpf, Ronald/0000-0001-7419-2701 NR 11 TC 5 Z9 6 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1996 VL 43 IS 3 BP 936 EP 943 DI 10.1109/23.510737 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA UT042 UT WOS:A1996UT04200027 ER PT J AU Swift, G Katz, R AF Swift, G Katz, R TI An experimental survey of heavy ion induced dielectric rupture in Actel field programmable gate arrays (FPGAs) SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 3rd European Symposium on Radiation and Its Effects on Components and Systems (RADECS 95) CY SEP 18-22, 1995 CL ARCACHON, FRANCE SP CNES, RADECS Assoc, IEEE, Nucl & Plasma Sci Soc AB Irradiations and subsequent failure analyses were performed to investigate single event dielectric rupture (SEDR) in Actel FPGAs as a function of ion LET (linear energy transfer), angle, bias, temperature, feature size, and device. The small cross sections imply acceptably low risk for most spacecraft uses. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Swift, G (reprint author), CALTECH,JET PROP LAB,PASADENA,CA, USA. NR 7 TC 11 Z9 12 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1996 VL 43 IS 3 BP 967 EP 972 DI 10.1109/23.510741 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA UT042 UT WOS:A1996UT04200031 ER PT J AU Dale, CJ Marshall, PW Fritz, ME delaChapelle, M Carts, MA LaBel, KA AF Dale, CJ Marshall, PW Fritz, ME delaChapelle, M Carts, MA LaBel, KA TI System level radiation response of a high performance fiber optic data bus SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 3rd European Symposium on Radiation and Its Effects on Components and Systems (RADECS 95) CY SEP 18-22, 1995 CL ARCACHON, FRANCE SP CNES, RADECS Assoc, IEEE, Nucl & Plasma Sci Soc AB We present experimental determinations of the total ionizing dose response and the proton-induced Single Event Upset (SEU) sensitivity of components comprising a 200 Mbps star coupled fiber optic data bus. These results are compared with the in-situ response of the operating system under proton bombardment, resulting in excellent correlation of the system error rate with proton-induced bit errors in the receiver photodiode. Modeling and error rate predictions for orbital performance indicate robust tolerance to even harsh natural space environments. C1 SFA INC,LANDOVER,MD 20785. BOEING CORP,SEATTLE,WA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Dale, CJ (reprint author), USN,RES LAB,WASHINGTON,DC 20375, USA. NR 14 TC 3 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1996 VL 43 IS 3 BP 1030 EP 1037 DI 10.1109/23.510751 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA UT042 UT WOS:A1996UT04200041 ER PT J AU Adolphsen, J Barth, JL Stassinopoulos, EG Gruner, T Wennersten, M LaBel, KA Seidleck, CM AF Adolphsen, J Barth, JL Stassinopoulos, EG Gruner, T Wennersten, M LaBel, KA Seidleck, CM TI SEE data from the APEX cosmic ray upset experiment: Predicting the performance of commercial devices in space SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 3rd European Symposium on Radiation and Its Effects on Components and Systems (RADECS 95) CY SEP 18-22, 1995 CL ARCACHON, FRANCE SP CNES, RADECS Assoc, IEEE, Nucl & Plasma Sci Soc AB This paper presents additional results from the CRUX experiment on the US Air Force APEX satellite. The experiment monitors single event effects on 256 Kbit and 1 Mbit SRAMs. It is shown that trapped protons dominate the single event upset rates, as evidenced by correlation with measured proton flux peaks and with flux contours calculated with the AP8 model. The responses of some part type lots were surprising because of the wide variation exhibited in upset rates from device to device within a part type, and because of a wide disparity in upset rates, depending on logic state. The use of generic ground test data in error rate predictions for a mission may be acceptable, but may also result in answers whose inaccuracies are unknown and could be unacceptably large. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. HUGHES ST SYST,GREENBELT,MD 20706. RP Adolphsen, J (reprint author), UNISYS,LANHAM,MD 20706, USA. NR 16 TC 2 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1996 VL 43 IS 3 BP 1069 EP 1076 DI 10.1109/23.510757 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA UT042 UT WOS:A1996UT04200047 ER PT J AU Hamel, LA Macri, JR Doty, FP AF Hamel, LA Macri, JR Doty, FP TI Signal generation in CdZnTe strip detectors SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1995 Nuclear Science Symposium/Medical Imaging Conference (NSS/MIC) CY OCT 21-28, 1995 CL SAN FRANCISCO, CA AB The energy resolution of CdTe and CdZnTe detectors is usually limited by the poor transport properties of holes. Devices segmented into small pixels have been observed to exhibit improved energy resolutions. Simulations have shown that this small pixel effect is due to the fact that small pixels are mostly sensitive to carriers moving close to the pixel, within a distance of the order of the pixel size. In this paper, signals are calculated for CdZnTe strip detectors in order to determine to what extent a similar small electrode effect is produced by strips. The free carrier density distributions following the absorption of a gamma-ray are calculated by solving the continuity equations. Combined with the strip weighting field, this provides the signal induced in the strip. Simulations are made for various detector geometries and for both the anode and cathode strips. Simulated signals are compared with actual signals measured on CdZnTe detectors. C1 UNIV NEW HAMPSHIRE,DURHAM,NH 03824. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. ORBITAL SCI CORP,GREENBELT,MD 20771. DIGIRAD,SAN DIEGO,CA 92121. RP Hamel, LA (reprint author), UNIV MONTREAL,MONTREAL,PQ H3C 3J7,CANADA. NR 9 TC 23 Z9 24 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1996 VL 43 IS 3 BP 1422 EP 1426 DI 10.1109/23.507077 PN 2 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA UT044 UT WOS:A1996UT04400065 ER PT J AU Inderhees, SE Phlips, BF Kroeger, RA Johnson, WN Kinzer, RL Kurfess, JD Graham, B Gehrels, N AF Inderhees, SE Phlips, BF Kroeger, RA Johnson, WN Kinzer, RL Kurfess, JD Graham, B Gehrels, N TI Spectroscopy, imaging and Compton-scatter polarimetry with a germanium strip detector SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1995 Nuclear Science Symposium/Medical Imaging Conference (NSS/MIC) CY OCT 21-28, 1995 CL SAN FRANCISCO, CA ID GAMMA-RAY AB Germanium strip detectors combine the excellent energy resolution possible with germanium detectors with fine two-dimensional spatial resolution determined by orthogonal strip electrodes. We are testing a detector with an active volume of 5 x 5 x 1 cm(3) and a total of 50 electrodes, 25 on each side with a 2mm pitch. Potential astrophysics applications include use as a focal plane for a coded-aperture telescope in the energy range similar to 5-500 keV, as the focal plane of a grazing-incidence telescope in the similar to 5-100 keV band, or in a Compton scatter telescope. The utilization of germanium strip detectors for these applications requires proof of their performance capabilities in terms of energy and spatial resolution, and efficiencies for single and multi-pixel interactions. In this paper, we demonstrate the excellent spectroscopy and imaging performance of a 2mm pitch strip detector, and report on the results of Monte- Carlo simulations of photopeak efficiencies for single and multi-pixel interactions. These simulations show that 2-pixel interactions are a significant fraction of the photopeak efficiency in the 80 - 500 keV range. We demonstrate that these interactions can be used to measure linear polarization of a normally incident beam. C1 USN,RES LAB,WASHINGTON,DC 20375. GEORGE MASON UNIV,FAIRFAX,VA 22030. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Inderhees, SE (reprint author), UNIV SPACE RES ASSOC,WASHINGTON,DC, USA. RI Gehrels, Neil/D-2971-2012; Johnson, Neil/G-3309-2014 NR 23 TC 16 Z9 16 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1996 VL 43 IS 3 BP 1467 EP 1471 DI 10.1109/23.507085 PN 2 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA UT044 UT WOS:A1996UT04400073 ER PT J AU Phlips, BF Inderhees, SE Kroeger, RA Johnson, WN Kinzer, RL Kurfess, JD Graham, BL Gehrels, N AF Phlips, BF Inderhees, SE Kroeger, RA Johnson, WN Kinzer, RL Kurfess, JD Graham, BL Gehrels, N TI Performance of a compton telescope using position-sensitive germanium detectors SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1995 Nuclear Science Symposium/Medical Imaging Conference (NSS/MIC) CY OCT 21-28, 1995 CL SAN FRANCISCO, CA AB We describe the use of position sensitive planar germanium detectors in a Compton telescope/camera. This Compton telescope achieves the very good energy resolution (Delta Etotal < 4 keV) associated with germanium detectors and good position resolution (2 mm. By combining a 25 x 25 strip (2 mm pitch) detector with a 5 x 5 strip detector (9 mm pitch), we created a telescope with 625 x 25 pixel combinations. Using this detector pair, we have reconstructed positions with an angular resolution of similar to 1 degree FWHM and 15 arcminute centroiding. Point sources are identified with less than 100 full energy events with simple image reconstruction. The angular resolution is currently limited by the uncertainty in the absolute position of the detectors and the size of the second detector pixels. We show the expected angular resolution when the pixel size no longer dominates the angular resolution and discuss proposed applications. C1 USN,RES LAB,WASHINGTON,DC 20375. GEORGE MASON UNIV,FAIRFAX,VA 22030. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Phlips, BF (reprint author), UNIV SPACE RES ASSOC,WASHINGTON,DC, USA. RI Gehrels, Neil/D-2971-2012; Johnson, Neil/G-3309-2014 NR 6 TC 17 Z9 17 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1996 VL 43 IS 3 BP 1472 EP 1475 DI 10.1109/23.507086 PN 2 PG 4 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA UT044 UT WOS:A1996UT04400074 ER PT J AU Allbritton, GL Andersen, H Barnes, A Christian, ER Cummings, AC Dougherty, BL Jensen, L Lee, J Leske, RA Madden, MP Mewaldt, R Milliken, B Nahory, BW ODonnell, R Schmidt, P Sears, BR vonRosenvinge, TT Walton, JT Wiedenbeck, ME Wong, YK AF Allbritton, GL Andersen, H Barnes, A Christian, ER Cummings, AC Dougherty, BL Jensen, L Lee, J Leske, RA Madden, MP Mewaldt, R Milliken, B Nahory, BW ODonnell, R Schmidt, P Sears, BR vonRosenvinge, TT Walton, JT Wiedenbeck, ME Wong, YK TI Large diameter lithium compensated silicon detectors for the NASA Advanced Composition Explorer (ACE) mission SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1995 Nuclear Science Symposium / Medical Imaging Conference (NSS/MIC 95) CY OCT 21-28, 1995 CL SAN FRANCISCO, CA ID SI(LI) DETECTORS AB Fabrication of the 100 mm diameter, 3 mm thick Lithium-compensated silicon, Si(Li), detectors for the Cosmic Ray Isotope Spectrometer (CRIS) instrument on board the ACE satellite required development of: new float-zone silicon growing techniques, new Si(Li) fabrication procedures, and new particle beam testing sequences. These developments are discussed and results are presented that illustrate the advances made in realizing these CRIS Si(Li) detectors, which, when operational in the CRlS detector telescopes, will usher in a new generation of cosmic-ray isotope spectrometers. C1 TOPSIL SEMICOND MAT, FREDERIKSSUND, DENMARK. UNIV CALIF BERKELEY, LAWRENCE BERKELEY NATL LAB, BERKELEY, CA 94720 USA. NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. JET PROP LAB, PASADENA, CA 91109 USA. RP CALTECH, PASADENA, CA 91125 USA. RI Christian, Eric/D-4974-2012 OI Christian, Eric/0000-0003-2134-3937 NR 6 TC 4 Z9 4 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9499 EI 1558-1578 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1996 VL 43 IS 3 BP 1505 EP 1509 DI 10.1109/23.507093 PN 2 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA UT044 UT WOS:A1996UT04400081 ER PT J AU Soli, GA Garrett, HB Fossum, ER AF Soli, GA Garrett, HB Fossum, ER TI CMOS charged particle spectrometers SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1995 Nuclear Science Symposium/Medical Imaging Conference (NSS/MIC) CY OCT 21-28, 1995 CL SAN FRANCISCO, CA AB Integrated circuits, manufactured in CMOS technology, have been developed as diffusion-based charged particle spectrometers for space applications. Current designs are single-chip spectrometers capable of uniquely identifying and counting electrons and heavy ions. A four-chip spectrometer designed to count protons and heavy ions was flown on the Clementine spacecraft. The spectrometer proton data is compared to GOES-6 proton data for the 21 February 1994 solar proton event. RP Soli, GA (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. OI Fossum, Eric/0000-0002-6232-0515 NR 7 TC 2 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1996 VL 43 IS 3 BP 1516 EP 1520 DI 10.1109/23.507095 PN 2 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA UT044 UT WOS:A1996UT04400083 ER PT J AU Koenen, M Bruckner, J Fabian, U Kruse, H Wanke, H Schroeder, ANF Starr, R Evans, LG Trombka, JI Drake, DM Englert, PAJ Dempsey, J AF Koenen, M Bruckner, J Fabian, U Kruse, H Wanke, H Schroeder, ANF Starr, R Evans, LG Trombka, JI Drake, DM Englert, PAJ Dempsey, J TI Analysis of radiation damaged HPGe detectors with a new algorithm SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1995 Nuclear Science Symposium/Medical Imaging Conference (NSS/MIC) CY OCT 21-28, 1995 CL SAN FRANCISCO, CA ID FAST-NEUTRON DAMAGE AB After being irradiated by high-energy protons, the energy resolution of HPGe detectors degrade extensively. Resulting line shapes depend mostly on detector geometry and doping type. To improve the analysis of measured gamma-ray spectra of HPGe detectors, new algorithms were developed. Since trapping in radiation damaged HPGe detectors is predominantly hole trapping, the full energy peak is the integration of absorption events produced within the detector at various distances from the positive contact. Implementing that information into fit algorithms, peaks produced by detectors irradiated with 6 . 10(8) protons/cm(2) could be analyzed. The tailing structure at the low energy side was included in the algorithm. Analog algorithms were successfully applied to damaged coaxial detectors of either doping type. Using these algorithms, it was possible to evaluate transients in damaged detectors after having been exposed to room temperature. Also, the development of tail broadening could be examined. C1 UNIV COLOGNE,W-5000 COLOGNE,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. SAN JOSE STATE UNIV,SAN JOSE,CA 95192. CATHOLIC UNIV AMER,WASHINGTON,DC 20064. RP Koenen, M (reprint author), MAX PLANCK INST CHEM,POSTFACH 3060,D-55020 MAINZ,GERMANY. NR 16 TC 2 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1996 VL 43 IS 3 BP 1570 EP 1575 DI 10.1109/23.507105 PN 2 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA UT044 UT WOS:A1996UT04400093 ER PT J AU Hodson, RF Doughty, DC Allgood, DC Campbell, SA Wilson, WC Bickley, MH AF Hodson, RF Doughty, DC Allgood, DC Campbell, SA Wilson, WC Bickley, MH TI A content addressable memory for use in CEBAF's CLAS detector level 2 triggering system SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1995 Nuclear Science Symposium/Medical Imaging Conference (NSS/MIC) CY OCT 21-28, 1995 CL SAN FRANCISCO, CA AB A collaboration of researchers from CEBAF, CNU and NASA is designing a 256 x 32 specialized Content Addressable Memory (CANI) for the level 2 triggering system in CEBAF's CLAS detector. These integrated circuits will find tracks and the momentum and angle of each track. within 2 microseconds of an event. The custom CAM can operate as conventional memory, performing read and write operations, and can additionally perform independent byte compare operations across all words simultaneously. It is this compare feature which makes these CAMs attractive for identifying tracks passing through drift chambers by linking together segment number triplets within the CAM. Simulations have indicated that less than 16k triplets need to be stored for each sector of the detector. This implies the level 2 triggering can be performed with 64 CAM chips per sector, or 384 total. Each data channel into a sector CAM array is buffered in a FIFO and is designed to handle aggregate data rates up to 750 Mbs for three channels (one channel/superlayer). The architecture of the level 2 trigger and details of the CAM chip design are discussed along with a performance report on our prototype CAMs. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. CONTINUOUS ELECTRON BEAM ACCELERATOR FACIL CTR,NEWPORT NEWS,VA 23606. RP Hodson, RF (reprint author), CHRISTOPHER NEWPORT UNIV,NEWPORT NEWS,VA 23606, USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1996 VL 43 IS 3 BP 1675 EP 1679 DI 10.1109/23.507169 PN 2 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA UT044 UT WOS:A1996UT04400112 ER PT J AU Xi, N Tarn, TJ Bejczy, AK AF Xi, N Tarn, TJ Bejczy, AK TI Intelligent planning and control for multirobot coordination: An event-based approach SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article ID FORCE CONTROL; REDUNDANT MANIPULATORS; ROBOT MANIPULATORS; MOTION AB A new planning and control scheme for multirobot coordination is presented, First, the event-based planning and control theory is introduced, The most important step is the design of an event-based motion reference for the multirobot system, It drives the system to achieve the best possible coordination, Hybrid position/force controllers which are able to perform a large class of tasks are designed based on the combination of general task space with the well-known nonlinear feedback linearization technique, To improve the force control performance, the dynamics of joint motors have been considered in the force control, For a given task, a task projection operator can be found for each robot with the consideration of redundancy management, It projects the feedback linearized model to the actual task space, A distributed computing architecture is proposed to implement this scheme in a parallel computation, The event-based coordination scheme was experimentally implemented and tested for the coordinated control of two 6 DOF PUMA 560 robots with very good results. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP WASHINGTON UNIV, DEPT SYST SCI & MATH, ST LOUIS, MO 63130 USA. NR 48 TC 66 Z9 70 U1 0 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD JUN PY 1996 VL 12 IS 3 BP 439 EP 452 DI 10.1109/70.499825 PG 14 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA UN487 UT WOS:A1996UN48700008 ER PT J AU Ueng, SK Sikorski, C Ma, KL AF Ueng, SK Sikorski, C Ma, KL TI Efficient streamline, streamribbon, and streamtube constructions on unstructured grids SO IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS LA English DT Article; Proceedings Paper CT 6th Annual IEEE Conference on Visualization CY OCT 29-NOV 03, 1995 CL ATLANTA, GA SP IEEE Comp Soc Tech Comm Comp Graph AB Streamline construction is one of the most fundamental techniques for visualizing steady flow fields. Streamribbons and streamtubes are extensions for visualizing the rotation and the expansion of the flow. This paper presents efficient algorithms for constructing streamlines, streamribbons, and streamtubes on unstructured grids. A specialized Runge-Kutta method is developed to speed up the tracing of streamlines. Explicit solutions are derived for calculating the angular rotation rates of streamribbons and the radii of streamtubes. In order to simplify mathematical formulations and reduce computational costs, all calculations are carried out in the canonical coordinate system instead of the physical coordinate system. The resulting speed-up in overall performance helps explore large flow fields. C1 NASA, LANGLEY RES CTR, INST COMP APPLICAT SCI & ENGN, HAMPTON, VA 23681 USA. RP Ueng, SK (reprint author), UNIV UTAH, DEPT COMP SCI, SALT LAKE CITY, UT 84112 USA. NR 14 TC 31 Z9 34 U1 2 U2 3 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1077-2626 EI 1941-0506 J9 IEEE T VIS COMPUT GR JI IEEE Trans. Vis. Comput. Graph. PD JUN PY 1996 VL 2 IS 2 BP 100 EP 110 DI 10.1109/2945.506222 PG 11 WC Computer Science, Software Engineering SC Computer Science GA UX901 UT WOS:A1996UX90100002 ER PT J AU Kenwright, DN Lane, DA AF Kenwright, DN Lane, DA TI Interactive time-dependent particle tracing using tetrahedral decomposition SO IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS LA English DT Article; Proceedings Paper CT 6th Annual IEEE Conference on Visualization CY OCT 29-NOV 03, 1995 CL ATLANTA, GA SP IEEE Comp Soc Tech Comm Comp Graph DE particle tracing; scientific visualization; computational fluid dynamics; time-dependent; unsteady flow; streak line; curvilinear grid; tetrahedral decomposition AB Streak lines and particle traces are effective visualization techniques for studying unsteady fluid flows. For real-time applications, accuracy is often sacrificed to achieve interactive frame rates. Physical space particle tracing algorithms produce the most accurate results although they are usually too expensive for interactive applications. An efficient physical space algorithm is presented in this paper which was developed for interactive investigation acid visualization of large, unsteady, aeronautical simulations. Performance has been increased by applying tetrahedral decomposition to speed up point location and velocity interpolation in curvilinear grids. Preliminary results from batch computations [1] showed that this approach was up to six times faster than the most common algorithm which uses the Newton-Raphson method and trilinear interpolation. Results presented here show that the tetrahedral approach also permits interactive computation and visualization of unsteady particle traces. Statistics are given for frame rates and computation times on single and multiprocessors. The benefits of interactive feature detection in unsteady Rows are also demonstrated. RP NASA, AMES RES CTR, MRJ INC, MOFFETT FIELD, CA 94035 USA. NR 20 TC 30 Z9 32 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1077-2626 EI 1941-0506 J9 IEEE T VIS COMPUT GR JI IEEE Trans. Vis. Comput. Graph. PD JUN PY 1996 VL 2 IS 2 BP 120 EP 129 DI 10.1109/2945.506224 PG 10 WC Computer Science, Software Engineering SC Computer Science GA UX901 UT WOS:A1996UX90100004 ER PT J AU SankarRao, M Lau, KM Yang, S AF SankarRao, M Lau, KM Yang, S TI On the relationship between Eurasian snow cover and the Asian summer monsoon SO INTERNATIONAL JOURNAL OF CLIMATOLOGY LA English DT Article DE Eurasian snow cover; Asian monsoon; atmospheric circulation; interannual variability ID NINO SOUTHERN OSCILLATION; INDIAN MONSOON; APPARENT RELATIONSHIP; NORTHERN-HEMISPHERE; INTERANNUAL VARIABILITY; ADVANCE PERIOD; RAINFALL; ASSOCIATION; CLIMATE AB In this paper, we document the possible linkage between Eurasian snow cover and the Asian summer monsoon by analysing the National Oceanic and Atmospheric Administration snow data and the atmospheric circulation fields from the National Meteorological Center analyses. Using updated data, we confirm the inverse relationship between the Eurasian snow cover and Indian monsoon rainfall reported in previous studies. We find that the relationship becomes stronger in the partial correlation calculations excluding the El Nino years. It is found by comparing years of more snow cover with years of less snow cover that the atmosphere is colder over land and warmer over the oceans during the winter seasons with more snow. During the summer following the winter with more snow cover, the lower atmosphere is colder over the Asian continent, especially north of India. Associated with these temperature changes, a weaker Asian monsoon circulation appears. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP SankarRao, M (reprint author), NATL SCI FDN,CLIMATE DYNAM PROGRAM,4201 WILSON BLVD,ARLINGTON,VA 22230, USA. RI Yang, Song/B-4952-2009; Lau, William /E-1510-2012 OI Lau, William /0000-0002-3587-3691 NR 33 TC 78 Z9 84 U1 3 U2 5 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0899-8418 J9 INT J CLIMATOL JI Int. J. Climatol. PD JUN PY 1996 VL 16 IS 6 BP 605 EP 616 DI 10.1002/(SICI)1097-0088(199606)16:6<605::AID-JOC41>3.0.CO;2-P PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UW638 UT WOS:A1996UW63800001 ER PT J AU Choudhury, BJ AF Choudhury, BJ TI Comparison of two models relating precipitable water to surface humidity using globally distributed radiosonde data over land surfaces SO INTERNATIONAL JOURNAL OF CLIMATOLOGY LA English DT Article DE precipitable water; vapour pressure; dew point temperature; regression ID VAPOR; RADIATION; AFRICA; WEST AB Relationships between precipitable water (W; mm) and surface vapour pressure (e(0); hPa), and surface dew point temperature (t(d); degrees C) are evaluated using mean monthly radiosonde data for 24 months at 45 globally distributed locations both for individual locations and for the pooled data from all locations. The data selected cover a wide range of climatic conditions and complete seasonality for most of the locations. The physical basis of the models relating W to e(0) or t(d) is reviewed briefly. Two semi-empirical models, namely W = C(1)e(0) + C-2 and ln W = C(3)t(d) + C-4, gave highly significant correlations both for individual locations and for the pooled data (r(2) = 0.94, C-1 = 1.70, C-2 = -0.1, C-3 = 0.058, and C-4 = 2.42 for the pooled data), but examination of the residuals showed some inadequacy of these models for the pooled data. RP Choudhury, BJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,LAB HYDROSPHER PROC,HYDROL SCI BRANCH,GREENBELT,MD 20771, USA. NR 38 TC 10 Z9 10 U1 1 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0899-8418 J9 INT J CLIMATOL JI Int. J. Climatol. PD JUN PY 1996 VL 16 IS 6 BP 663 EP 675 DI 10.1002/(SICI)1097-0088(199606)16:6<663::AID-JOC29>3.0.CO;2-O PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UW638 UT WOS:A1996UW63800005 ER PT J AU Rovetta, A Sala, R Cosmi, F Wen, X Milanesi, S Sabbadini, D Togno, A Angelini, L Bejczy, AK AF Rovetta, A Sala, R Cosmi, F Wen, X Milanesi, S Sabbadini, D Togno, A Angelini, L Bejczy, AK TI A new telerobotic application: Remote laparoscopic surgery using satellites and optical fiber networks for data exchange SO INTERNATIONAL JOURNAL OF ROBOTICS RESEARCH LA English DT Article AB This article describes the significance in human, scientific and technical terns of the first experiment in telerobotic surgery carried out between the NASA Jet propulsion Laboratory in Pasadena, California, and the Telerobotics Laboratory of the Politecnico di Milano on 7 July 1993. An Italian robot in the Telerobotics Laboratory was remotely controlled by an Italian surgeon in the United States. The robot's task was to perform a surgical operation on a model containing a pig's organs, involving execution of a biopsy, aspiration of organic material, and two incisions in preparation of laparoscopy. Transmission was effected by means of a double satellite link with three transceiver stations: one in Italy, one close to New York, and one in Pasadena, and two geostationary satellites, the first over the Atlantic and the second over the United States. The route length of the signals was 150,000 km in each direction, and the two centers are 10,000 km apart. C1 UNIV ROMA LA SAPIENZA, IST CLIN CHIRURG, ROME, ITALY. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP Rovetta, A (reprint author), POLITECN MILAN, DEPT MECH, TELEROBOT LAB, I-20133 MILAN, ITALY. NR 31 TC 15 Z9 16 U1 7 U2 9 PU SAGE PUBLICATIONS LTD PI LONDON PA 1 OLIVERS YARD, 55 CITY ROAD, LONDON EC1Y 1SP, ENGLAND SN 0278-3649 J9 INT J ROBOT RES JI Int. J. Robot. Res. PD JUN PY 1996 VL 15 IS 3 BP 267 EP 279 DI 10.1177/027836499601500303 PG 13 WC Robotics SC Robotics GA UL982 UT WOS:A1996UL98200003 ER PT J AU Gorman, MR Prosser, WH AF Gorman, MR Prosser, WH TI Application of normal mode expansion to acoustic emission waves in finite plates SO JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME LA English DT Article C1 NASA,LANGLEY RES CTR,NONDESTRUCT MEASUREMENT SCI BRANCH,HAMPTON,VA 23681. RP Gorman, MR (reprint author), UNIV DENVER,DEPT PHYS,DENVER,CO 80208, USA. NR 11 TC 16 Z9 16 U1 0 U2 4 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0021-8936 J9 J APPL MECH-T ASME JI J. Appl. Mech.-Trans. ASME PD JUN PY 1996 VL 63 IS 2 BP 555 EP 557 DI 10.1115/1.2788905 PG 3 WC Mechanics SC Mechanics GA UU357 UT WOS:A1996UU35700050 ER PT J AU Caillat, T Kulleck, J Borshchevsky, A Fleurial, JP AF Caillat, T Kulleck, J Borshchevsky, A Fleurial, JP TI Preparation and thermoelectric properties of the skutterudite-related phase Ru0.5Pd0.5Sb3 SO JOURNAL OF APPLIED PHYSICS LA English DT Article AB A new skutterudite phase Ru0.5Pd0.5Sb3 was prepared. This new phase adds to a large number of already known materials with the skutterudite structure which have shown good potential for thermoelectric applications. Single phase, polycrystalline samples were prepared and characterized by x-ray analysis, electron probe microanalysis, density, sound velocity, thermal-expansion coefficient, and differential thermal analysis measurements. Ru0.5Pd0.5Sb3 has a cubic lattice, space group Im3 (T-h(5)), with a=9.298 Angstrom and decomposes at about 920 K. The Seebeck coefficient, the electrical resistivity, the Hall effect, and the thermal conductivity were measured on hot-pressed samples over a wide range of temperatures. Preliminary results show that Ru0.5Pd0.5Sb3 behaves as a heavily doped semiconductor with an estimated band gap of about 0.6 eV. The lattice thermal conductivity of Ru0.5Pd0.5Sb3 is substantially lower than that of the binary isostructural compounds CoSb3 and IrSb3. The unusually low thermal conductivity might be explained by additional hole and charge transfer phonon scattering in this material. The potential of this material for thermoelectric applications is discussed. (C) 1996 American Institute of Physics. RP Caillat, T (reprint author), CALTECH, JET PROP LAB, MS 277-207, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 22 TC 63 Z9 67 U1 0 U2 7 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUN 1 PY 1996 VL 79 IS 11 BP 8419 EP 8426 DI 10.1063/1.362516 PG 8 WC Physics, Applied SC Physics GA UN852 UT WOS:A1996UN85200042 ER PT J AU Racette, P Adler, RF Gasiewski, AJ Jakson, DM Zacharias, DS AF Racette, P Adler, RF Gasiewski, AJ Jakson, DM Zacharias, DS TI An airborne millimeter-wave imaging radiometer for cloud, precipitation, and atmospheric water vapor studies SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID 183 GHZ; MICROWAVE RADIOMETRY; MOISTURE PROFILES; RETRIEVAL; RAINFALL; OCEANS; CLEAR AB A six-channel airborne total-power Millimeter-wave Imaging Radiometer (MIR) was recently built to provide measurements of atmospheric water vapor, clouds, and precipitation The instrument is a cross-track scanner that has a 3-dB beamwidth of 3.5 degrees and an angular swath of 100 degrees. It measures radiation at the frequencies of 89, 150, 183.3 +/- 1, 183.3 +/- 3, 183.3 +/- 7, and 220 GHz. The inclusion of the 220-GHz receiver makes this instrument unique; no other instrument has made atmospheric radiation measurements using this combination of frequencies. The temperature sensitivities Delta T, based on the actual flight data with a 6.8-ms integration time, are found to be 0.44, 0.44, 1.31, 1.30, 1.02, and 1.07 K. The instrument has two external calibration loads maintained at the temperatures of 330 and 250 K (the ambient temperature at an aircraft altitude of 20 Bm). These calibration load temperatures are monitored precisely so that the radiometric measurements of the instrument could be made to better than 1 K of accuracy in the brightness temperature range of 240-300 K. Measurements made with a calibration target emmersed in liquid nitrogen indicate a measurement accuracy of 2-4 K for brightness temperatures below 100 K. The instrument has flown successfully aboard the National Aeronautics and Space Administration (NASA) ER-2 aircraft for more than 130 h. This paper is an overview of the system design, calibration, and measurement capabilities. C1 GEORGIA INST TECHNOL, DEPT ELECT ENGN, ATLANTA, GA 30332 USA. ZAX MILLIMETER WAVE CORP, SAN DIMAS, CA USA. RP Racette, P (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 975, GREENBELT, MD 20771 USA. NR 33 TC 46 Z9 49 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD JUN PY 1996 VL 13 IS 3 BP 610 EP 619 DI 10.1175/1520-0426(1996)013<0610:AAMWIR>2.0.CO;2 PG 10 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA UL668 UT WOS:A1996UL66800006 ER PT J AU Welch, RB AF Welch, RB TI On the origin of eye movement desensitization and reprocessing: A response to Rosen SO JOURNAL OF BEHAVIOR THERAPY AND EXPERIMENTAL PSYCHIATRY LA English DT Article AB Rosen argues that the eye movements experienced by Shapiro during the incident leading to her development of eye movement desensitization and reprocessing (EMDR) could not, as she later inferred, have been saccadic. The present author disputes Rosen's conclusion by showing that his arguments are based on a faulty understanding of the nature of saccadic eye movements or are irrelevant to Shapiro's claim. RP Welch, RB (reprint author), NASA,AMES RES CTR,MAIL STOP 239-11,MOFFETT FIELD,CA 94035, USA. NR 17 TC 5 Z9 5 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0005-7916 J9 J BEHAV THER EXP PSY JI J. Behav. Ther. Exp. Psychiatry PD JUN PY 1996 VL 27 IS 2 BP 175 EP 179 DI 10.1016/0005-7916(96)00013-4 PG 5 WC Psychology, Clinical; Psychiatry SC Psychology; Psychiatry GA VK839 UT WOS:A1996VK83900011 PM 8894916 ER PT J AU Moursi, AM Damsky, CH Lull, J Zimmerman, D Doty, SB Aota, SI Globus, RK AF Moursi, AM Damsky, CH Lull, J Zimmerman, D Doty, SB Aota, SI Globus, RK TI Fibronectin regulates calvarial osteoblast differentiation SO JOURNAL OF CELL SCIENCE LA English DT Article DE fibronectin; osteoblast differentiation; RGD sequence; fetal rat calvarial osteoblast ID HEPARIN-BINDING DOMAIN; EXTRACELLULAR-MATRIX; SIGNAL TRANSDUCTION; GENE-EXPRESSION; ALKALINE-PHOSPHATASE; CELL-INTERACTION; SARCOMA CELLS; BONE-CELLS; ADHESION; INTEGRIN AB The secretion of fibronectin by differentiating osteoblasts and its accumulation at sites of osteogenesis suggest that fibronectin participates in bone formation. To test this directly, we determined whether fibronectin-cell interactions regulate progressive differentiation of cultured fetal rat calvarial osteoblasts. Spatial distributions of alpha 5 integrin subunit, fibronectin, osteopontin (bone sialoprotein I) and osteocalcin (bone Gla-protein) were similar in fetal rat calvaria and mineralized, bone-like nodules formed by cultured osteoblasts. Addition of antifibronectin antibodies to cultures at confluence reduced subsequent formation of nodules to less than 10% of control values, showing that fibronectin is required for normal nodule morphogenesis. Anti-fibronectin antibodies selectively inhibited steady-state expression of mRNA for genes associated with osteoblast differentiation; mRNA levels for alkaline phosphatase and osteocalcin were suppressed, whereas fibronectin, type I collagen and osteopontin were unaffected. To identify functionally relevant domains of fibronectin, we treated cells with soluble fibronectin fragments and peptides. Cell-binding fibronectin fragments (type III repeats 6-10) containing the Arg-Gly-Asp (RGD) sequence blocked both nodule initiation and maturation, whether or not they contained a functional synergy site. In contrast, addition of the RGD-containing peptide GRGDSPK alone did not inhibit nodule initiation, although it did block nodule maturation. Thus, in addition to the RGD sequence, other features of the large cell-binding fragments contribute to the full osteogenic effects of fibronectin. Nodule formation and osteoblast differentiation resumed after anti-fibronectin antibodies or GRGDSPK peptides were omitted from the media, showing that the inhibition was reversible and the treatments were not cytotoxic. Outside the central cell-binding domain, peptides from the IIICS region and antibodies to the N terminus did not inhibit nodule formation. We conclude that osteoblasts interact with the central cell-binding domain of endogenously produced fibronectin during early stages of differentiation, and that these interactions regulate both normal morphogenesis and gene expression. C1 UNIV CALIF SAN FRANCISCO,DEPT STOMATOL,SAN FRANCISCO,CA 94143. UNIV CALIF SAN FRANCISCO,DEPT ANAT,SAN FRANCISCO,CA 94143. UNIV CALIF SAN FRANCISCO,DEPT MED,SAN FRANCISCO,CA 94143. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. HOSP SPECIAL SURG,NEW YORK,NY 10021. NIDR,BETHESDA,MD 20892. FU NIDCR NIH HHS [P50-DE10306, T32 DE07204] NR 50 TC 219 Z9 224 U1 1 U2 7 PU COMPANY OF BIOLOGISTS LTD PI CAMBRIDGE PA BIDDER BUILDING CAMBRIDGE COMMERCIAL PARK COWLEY RD, CAMBRIDGE, CAMBS, ENGLAND CB4 4DL SN 0021-9533 J9 J CELL SCI JI J. Cell Sci. PD JUN PY 1996 VL 109 BP 1369 EP 1380 PN 6 PG 12 WC Cell Biology SC Cell Biology GA UU359 UT WOS:A1996UU35900020 PM 8799825 ER PT J AU Dewitte, B Perigaud, C AF Dewitte, B Perigaud, C TI El Nino La Nina events simulated with Cane and Zebiak's model and observed with satellite or in situ data .2. Model forced with observations SO JOURNAL OF CLIMATE LA English DT Article ID SEA-SURFACE TEMPERATURE; TROPICAL PACIFIC-OCEAN; LATENT-HEAT FLUX; SOUTHERN OSCILLATION; ATMOSPHERE MODEL; ENSO; VARIABILITY; CIRCULATION; CONVERGENCE; ANOMALIES AB Various parameterizations derived from the observations are tested and proposed to improve the skill of the Cane and Zebiak's model in simulating the reality. The model is forced by FSU winds over the period 1980-1993. In particular, the way in which both the cold event and the easterlies in 1988 can be simulated better than with the parameterizations of the model is examined here. Introducing observed zonal current anomalies in the SST equation enhances the contrast between cold and warm anomalies in the eastern Pacific but does not induce a cold anomaly in 1988 in the central Pacific. This model deficiency is due to the parameterization of the temperature anomaly at 50 m, which precludes the temperature from being cold when the thermocline is shoaling. A new parameterization is determined based on the XBT subsurface temperature profiles. The SST simulated by the model is considerably improved with this new parameterization. When forced with observed SST, the atmospheric model simulates the observed easterlies in 1988. The model deficiency in simulating easterlies is therefore not due to the atmospheric component but to the oceanic one. However, the location of the simulated wind is always to the east of the observed ones because the atmospheric model simulates an internal heating term that is too tightly linked to the SST anomalies. The model performs better when it is forced by a combination of SST and cloud convection data. A new parameterization of anomalous convection heating is proposed based on convection data and introduced in the model to improve the wind simulation. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 51 TC 25 Z9 31 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD JUN PY 1996 VL 9 IS 6 BP 1188 EP 1207 DI 10.1175/1520-0442(1996)009<1188:ENLNES>2.0.CO;2 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UY340 UT WOS:A1996UY34000002 ER PT J AU Bell, TL Kundu, PK AF Bell, TL Kundu, PK TI A study of the sampling error in satellite rainfall estimates using optimal averaging of data and a stochastic model SO JOURNAL OF CLIMATE LA English DT Article ID NINO SOUTHERN OSCILLATION; TROPICAL RAINFALL; THRESHOLD METHOD; RADAR; AREA; MICROWAVE; INTEGRALS; SPACE AB A method of combining satellite estimates of rainfall into gridded monthly averages suitable for climatological studies is examined. Weighted averages of the satellite estimates are derived that minimize the mean squared error of the grid-box averages. A spectral model with nonlocal, scaling, diffusive behavior at small distances, tuned to tropical Atlantic (GATE) statistics, is developed to study the optimal weighting method. Using it, the effect of optimal weighting for averaging data similar to what will be provided by the Tropical Rainfall Measuring Mission (TRMM) satellite is examined. The improvement in the accuracy of the averages is found to be small except for higher-latitude grid boxes near the edges of the satellite coverage. The averages of data from a combination of TRMM and a polar orbiting instrument such as SSM/I, however, are substantially improved using the method. A simple formula for estimating sampling error for each grid box is proposed, requiring only the local rain rate and a measure of the sample volume provided by the satellite. RP Bell, TL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. RI Bell, Thomas/G-5425-2012; Kundu, Prasun/C-7212-2013 OI Kundu, Prasun/0000-0002-2284-9852 NR 31 TC 48 Z9 48 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD JUN PY 1996 VL 9 IS 6 BP 1251 EP 1268 DI 10.1175/1520-0442(1996)009<1251:ASOTSE>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UY340 UT WOS:A1996UY34000006 ER PT J AU Shuman, CA Fahnestock, MA Bindschadler, RA Alley, RB Stearns, CR AF Shuman, CA Fahnestock, MA Bindschadler, RA Alley, RB Stearns, CR TI Composite temperature record from the Greenland summit, 1987-1994: Synthesis of multiple automatic weather station records and SSM/I brightness temperatures SO JOURNAL OF CLIMATE LA English DT Article AB Air temperature (T-A) records from automatic weather stations (AWS) in central Greenland and associated Special Sensor Microwave/Imager (SSM/I) brightness temperature (T-B) data (37 GHz, vertical polarization) have been used to create a composite, daily, monthly, and annual average temperature record of the Greenland summit for the period 1987-1994. The record is derived primarily from near-surface temperatures from a single station; AWS Cathy (May 1987 to May 1989), which was moved 28 km and became AWS Kenton (starting in June 1989 and continuing). The Cathy daily average T-A record has been converted to the equivalent basis of Kenton by a technique based on the ratio of the contemporaneous daily average T-B data from the two locations. The accuracy of this technique has been statistically tested using 16 months of contemporaneous T-A and T-B data from the GISP2 and Kenton AWS. The resulting composite temperature record provides a multiyear dataset for comparison to other climate records from the Greenland summit. C1 UNIV MARYLAND,DEPT METEOROL,JOINT CTR EARTH SYST SCI,COLLEGE PK,MD 20742. PENN STATE UNIV,CTR EARTH SYST SCI,UNIVERSITY PK,PA 16802. UNIV WISCONSIN,SPACE SCI & ENGN CTR,MADISON,WI. RP Shuman, CA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,LAB HYDROSPHER PROC,OCEANS & ICE BRANCH,NRC,RRA,MAIL CODE 971,GREENBELT,MD 20771, USA. RI Fahnestock, Mark/N-2678-2013 NR 20 TC 16 Z9 16 U1 1 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD JUN PY 1996 VL 9 IS 6 BP 1421 EP 1428 DI 10.1175/1520-0442(1996)009<1421:CTRFTG>2.0.CO;2 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UY340 UT WOS:A1996UY34000018 ER PT J AU Geelen, G Greenleaf, JE Keil, LC AF Geelen, G Greenleaf, JE Keil, LC TI Drinking-induced plasma vasopressin and norepinephrine changes in dehydrated humans SO JOURNAL OF CLINICAL ENDOCRINOLOGY & METABOLISM LA English DT Article ID ATRIAL NATRIURETIC PEPTIDE; SECRETION; WATER; INHIBITION; THIRST; RELEASE; DOGS; OSMOLALITY; REDUCTION; VOLUME AB After 24-h water deprivation, five men (23-41 yr; 78 +/- 3.6 kg) consumed, within 4.0-6.2 min, 12 mL/kg of one of six fluid formulations (16.5 C) once a week over a period of 6 weeks: mater, hypotonic saline (0.045% Na+), isotonic saline (0.36% Na+), hypertonic glucose (9.7% glucose), and two commercial mildly hypertonic 9.7% carbohydrate drinks. Blood samples were drawn 5 min before and 3, 9, 15, 30, and 70 min after completion of drinking. Ingestion induced no significant change in plasma Na+, K+, osmotic, or protein concentrations; blood pressure; or heart rate. Plasma volume (PV) was increased (P < 0.05) between 30-70 min with isotonic saline and the two commercial drinks. Ingestion induced a decrease in plasma AVP (PAVP) at 3 min, which was maximal (P < 0.05) at 15 min with all drinks. Thus, the act of drinking, independent of the composition or osmolality of the fluid absorbed, leads to a prompt inhibition of PAVP secretion in man. With the exception of rehydration with isotonic saline, this prompt response was followed by a long lasting inhibition of PAVP. There was no change in PRA, plasma aldosterone, atrial natriuretic peptide, or epinephrine, but an increase in plasma norepinephrine occurred immediately after ingestion, which suggests, like that for PAVP depression, a drinking-stimulated neural mechanism. C1 NASA, AMES RES CTR, LAB HUMAN ENVIRONM PHYSIOL, MOFFETT FIELD, CA 94035 USA. RP Geelen, G (reprint author), UNIV LYON 1, FAC MED GRANGE BLANCHE, LAB PHYSIOL ENVIRONNEMENT, 8 AVE ROCKFELLER, F-69373 LYON 08, FRANCE. NR 29 TC 30 Z9 30 U1 1 U2 2 PU ENDOCRINE SOC PI CHEVY CHASE PA 8401 CONNECTICUT AVE, SUITE 900, CHEVY CHASE, MD 20815-5817 USA SN 0021-972X EI 1945-7197 J9 J CLIN ENDOCR METAB JI J. Clin. Endocrinol. Metab. PD JUN PY 1996 VL 81 IS 6 BP 2131 EP 2135 DI 10.1210/jc.81.6.2131 PG 5 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA UQ022 UT WOS:A1996UQ02200022 PM 8964840 ER PT J AU Feng, A McCoy, BJ Munir, ZA Cagliostro, DE AF Feng, A McCoy, BJ Munir, ZA Cagliostro, DE TI Water adsorption and desorption kinetics on silica insulation SO JOURNAL OF COLLOID AND INTERFACE SCIENCE LA English DT Article DE silica; hydrophobic and hydrophilic; hydrophilic; adsorption and desorption; kinetics; activation energy ID SURFACE-STRUCTURE; OXIDATION; POWDERS; CDS AB Silica is an important component of thermal insulation used in aerospace transport vehicles. Although normally hydrophilic and requiring rewaterproofing after flight, silica insulation has been reported to become hydrophobic on heating and cooling in a vacuum and, therefore, potentially hydrophobic after reentry. To understand and model these processes, the rates of desorption and adsorption of water on silica were studied by thermogravimetry, Fourier transform infrared spectrometry, and X-ray photoelectron spectroscopy. Silica powders with a high surface area were heated in vacuo in the temperature range 200-1000 degrees C, infrared absorbance spectra were obtained at various temperatures, and surface structure was examined by X-ray photoelectron spectroscopy. A kinetic sorption model was developed based on a Langmuir rate expression. Activation energies for adsorption and desorption were determined by fitting the experimental results numerically. The study found adsorption of water on the heat-treated silica occurs within seconds, implying hydrophobicity is lost rapidly after the heat-treated silica is exposed to water. (C) 1996 Academic Press, Inc. C1 UNIV CALIF DAVIS,DEPT CHEM ENGN & MAT SCI,DAVIS,CA 95616. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 31 TC 33 Z9 33 U1 3 U2 12 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9797 J9 J COLLOID INTERF SCI JI J. Colloid Interface Sci. PD JUN 1 PY 1996 VL 180 IS 1 BP 276 EP 284 DI 10.1006/jcis.1996.0300 PG 9 WC Chemistry, Physical SC Chemistry GA UP551 UT WOS:A1996UP55100035 ER PT J AU Meadows, KR Atkins, HL AF Meadows, KR Atkins, HL TI Towards a highly accurate implementation of the Kirchhoff approach for computational aeroacoustics SO JOURNAL OF COMPUTATIONAL ACOUSTICS LA English DT Article AB This paper describes the development of high-order Kirchhoff algorithms and confirms that high-order accuracy can be achieved with the Kirchhoff approach when high-order integration and interpolation are properly implemented. This paper also establishes guidelines for enhancing accuracy of a given order property when the Kirchhoff formula is applied to results obtained from a computational fluid dynamics (CFD) solution. Accuracy is shown to increase when the Kirchhoff surface size is minimized. Reduction of the Kirchhoff surface size also enhances efficiency of the calculation because the size of the relatively expensive CFD computation is reduced. The accuracy of the Kirchhoff approach is also enhanced by increasing the density of information along the Kirchhoff surface. This increase in information is necessary because evaluation of the Kirchhoff integrand at the retarded time demands higher spatial resolution than the integration of the time-dependent nonlinear equations of the CFD calculation. A procedure has been developed that addresses the Kirchhoff resolution requirements without sacrificing efficiency. The error reduction realized with this procedure matches that realized with CFD mesh refinement, with almost no increase in cost. RP Meadows, KR (reprint author), NASA,LANGLEY RES CTR,FLUID MECH & ACOUST DIV,AERODYNAM & ACOUST METHODS BRANCH,MAIL STOP 128,HAMPTON,VA 23681, USA. NR 9 TC 5 Z9 5 U1 0 U2 0 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA JOURNAL DEPT PO BOX 128 FARRER ROAD, SINGAPORE 9128, SINGAPORE SN 0218-396X J9 J COMPUT ACOUST JI J. Comput. Acoust. PD JUN PY 1996 VL 4 IS 2 BP 225 EP 241 DI 10.1142/S0218396X96000064 PG 17 WC Acoustics; Mathematics, Interdisciplinary Applications SC Acoustics; Mathematics GA VC881 UT WOS:A1996VC88100005 ER PT J AU Kim, BR Kalis, EM Salmeen, IT Kruse, CW Demir, I Carlson, SL RostamAbadi, M AF Kim, BR Kalis, EM Salmeen, IT Kruse, CW Demir, I Carlson, SL RostamAbadi, M TI Evaluating paint-sludge chars for adsorption of selected paint solvents SO JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE LA English DT Article ID ACTIVATED CARBON; REACTOR AB At Ford, a study had been carried out to investigate the technical feasibility of converting paint sludge to activated char and reusing the char in paint spray-booth water to capture paint solvents from spray-booth air. As part of the study several chars were made from a paint sludge and six dried paints to evaluate their effectiveness as adsorbents by conducting a series of liquid-phase adsorption experiments. Three commonly-used paint solvents and p-nitrophenol were selected as adsorbates. The three paint solvents were toluene, 2-methyl-1-propanol (iso-butanol), and 2-butoxyethanol (butylcellosolve). In this paper, the results of the pyrolysis and adsorption experiments are presented along with practical implications. The primary findings include the following: (1) Black-paint chars showed substantially larger surface area and higher adsorption capacity (based on total weight) than white-paint chars which had high ash contents due tb the white pigment, titanium dioxide; (2) the adsorption capacity of the paint-sludge char was between those of black-paint and white-paint chars, and was 5-20% that of a commercial activated carbon; (3) titanium dioxide in white-paint chars did not improve the chars' affinity for hydrophilic compounds such as 2-methyl-1-propanol and 2-butoxyethanol; (4) coal could be added to paint sludge to improve the quality of the resulting char and to reduce ash content; and (5) the pyrolysis of paint sludge could present an attractive opportunity for reusing and recycling a waste product for pollution abatement and as a vehicle component. C1 ILLINOIS STATE GEOL SURVEY,CHAMPAIGN,IL 61821. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Kim, BR (reprint author), FORD RES LAB,POB 2053,MD-3083 SRL,DEARBORN,MI 48121, USA. NR 15 TC 9 Z9 9 U1 2 U2 6 PU ASCE-AMER SOC CIVIL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2398 SN 0733-9372 J9 J ENVIRON ENG-ASCE JI J. Environ. Eng.-ASCE PD JUN PY 1996 VL 122 IS 6 BP 532 EP 539 DI 10.1061/(ASCE)0733-9372(1996)122:6(532) PG 8 WC Engineering, Environmental; Engineering, Civil; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA UM374 UT WOS:A1996UM37400012 ER PT J AU Birn, J Hesse, M Schindler, K AF Birn, J Hesse, M Schindler, K TI MHD simulations of magnetotail dynamics SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FIELD-ALIGNED CURRENTS; GENERAL MAGNETIC RECONNECTION; TAIL CURRENT DISRUPTION; NEAR-EARTH MAGNETOTAIL; SUBSTORM CURRENT WEDGE; SELF-CONSISTENT THEORY; GEOMAGNETIC TAIL; CURRENT SHEET; MAGNETOSPHERIC SUBSTORMS; PLASMOID EVOLUTION AB Resistive MHD simulations of large-scale magnetotail dynamics demonstrate that the same unstable mode causes plasmoid formation and ejection into the far tail and dipolarization and the formation of the substorm current wedge in the inner tail, consistent with the neutral line model of substorms. However, they have also modified some aspects of the model and added details that could not easily be inferred without the self-consistent approach. We review recent results that include the externally driven formation of a thin current sheet in the near tail, which eases the onset of instability and leads to a faster dynamic evolution. In contrast to earlier expectations, the field-aligned current generation and diversion takes place in the inner tail earthward of the reconnection site, resulting from shear and diversion of the earthward flow caused by reconnection farther out. Dipolarization starts most pronounced in the tail-dipole transition region, propagating both tailward and flankward. Strong electric fields and plasma heating also are most prominent in the inner tail. Three-dimensional simulations without mirror symmetries have generalized the picture of plasmoid formation and ejection, demonstrating a tangled geometry of helical flux ropes with different connections that change increasingly from the Earth to the magnetosheath. The interconnection with the magnetosheath may also play a role in generating plasmoid flux ropes with strong core fields. Mass, energy, and momentum gain of plasmoids results mainly from the accumulation of already accelerated plasma rather than from a sling shot effect acting on the entire plasmoid. C1 NASA,GODDARD SPACE FLIGHT CTR,ELECTRODYNAM BRANCH,GREENBELT,MD 20771. RUHR UNIV BOCHUM,D-44780 BOCHUM,GERMANY. RP Birn, J (reprint author), LOS ALAMOS NATL LAB,SPACE & ATMOSPHER SCI GRP,MS D466,LOS ALAMOS,NM 87545, USA. RI Hesse, Michael/D-2031-2012 NR 94 TC 67 Z9 70 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1996 VL 101 IS A6 BP 12939 EP 12954 DI 10.1029/96JA00611 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP353 UT WOS:A1996UP35300002 ER PT J AU Klimas, AJ Vassiliadis, D Baker, DN Roberts, DA AF Klimas, AJ Vassiliadis, D Baker, DN Roberts, DA TI The organized nonlinear dynamics of the magnetosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CHAOTIC TIME-SERIES; GEOMAGNETIC-ACTIVITY; CORRELATION DIMENSION; THERMAL CATASTROPHE; STRANGE ATTRACTORS; SPURIOUS DIMENSION; AURORAL OVAL; SOLAR-WIND; SUBSTORMS; AE AB The linear prediction filters computed by Bargatze et al. [1985] have resulted in a turning point in the study of solar wind-magnetosphere coupling. The evolution of the filters with varying activity provides a clear demonstration that the coupling is nonlinear. The filters have thus brought about the end of one era of linear correlative studies and the beginning of a new era of nonlinear dynamical studies. Two separate, but complementary, approaches have emerged in these dynamical studies, analogue modeling and data-based phase space reconstruction. The reconstruction research has evolved from the original autonomous method studies, which were not conclusive, to the more recent input-output studies that are more appropriate for the solar wind-driven magnetosphere and have produced more reliable results. At present it appears that the modeling and reconstruction approaches may be merged in future attempts to produce analogue models directly from the results of the input-output data-based methods. If this can be accomplished, it will constitute a major step forward toward the goal of a low-dimensional analogue model of the magnetospheric dynamics derived directly from data and interpreted in terms of magnetospheric physics. These developments are reviewed in three sections: autonomous data analysis methods, analogue models, and input-output data analysis methods. The introduction provides sufficient information to read each of these sections independently. C1 UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80302. UNIV SPACE RES ASSOC,SEABROOK,MD 20706. RP Klimas, AJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 92,GREENBELT,MD 20771, USA. RI Roberts, Dana/D-4625-2012 NR 73 TC 145 Z9 145 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1996 VL 101 IS A6 BP 13089 EP 13113 DI 10.1029/96JA00563 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP353 UT WOS:A1996UP35300009 ER PT J AU Norqvist, P Andre, M Eliasson, L Eriksson, AI Blomberg, L Luhr, H Clemmons, JH AF Norqvist, P Andre, M Eliasson, L Eriksson, AI Blomberg, L Luhr, H Clemmons, JH TI Ion cyclotron heating in the dayside magnetosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID LOW-FREQUENCY WAVES; TOPSIDE AURORAL IONOSPHERE; POLAR CUSP; MULTICOMPONENT PLASMA; RESONANT ABSORPTION; BOUNDARY-LAYER; ACCELERATION; CLEFT; TURBULENCE; REGION AB Observations of waves and particles obtained by the Freja satellite at altitudes around 1700 km in the dayside high-latitude magnetosphere are used to study ion energization. We find that ions, including O+, during several events of intense ion energization can be heated perpendicularly to the geomagnetic field to mean energies df up to about 20 eV via the process of cyclotron resonance by broadband waves around the ion gyrofrequencies. There is a good correlation between such broadband waves and the ion energization. The waves show no spectral features at the O+ gyrofrequency. The observed wave amplitudes are used as an input to a Monte Carlo simulation to obtain the observed ion energies. The waves around the ion gyrofrequencies may be generated either by field-aligned electrons or by nonlinear processes transferring energy from waves with lower frequencies. Not only the mean energy but also the shape of the particle distribution agrees with the cyclotron resonance heating mechanism. Other mechanisms, such as heating by lower hybrid waves or by a slowly varying electric field, are investigated but are found to be less important than cyclotron heating in this region of space. C1 ROYAL INST TECHNOL,DIV PLASMA PHYS,ALFVEN LAB,S-10044 STOCKHOLM,SWEDEN. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. SWEDISH INST SPACE PHYS,S-98128 KIRUNA,SWEDEN. SWEDISH INST SPACE PHYS,S-75591 UPPSALA,SWEDEN. TECH UNIV CAROLO WILHELMINA BRAUNSCHWEIG,INST GEOPHYS & METEOROL,D-38106 BRAUNSCHWEIG,GERMANY. RP Norqvist, P (reprint author), UMEA UNIV,SWEDISH INST SPACE PHYS,S-90187 UMEA,SWEDEN. RI Eriksson, Anders/C-2887-2009 NR 59 TC 62 Z9 62 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1996 VL 101 IS A6 BP 13179 EP 13193 DI 10.1029/95JA03596 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP353 UT WOS:A1996UP35300014 ER PT J AU Khazanov, GV Moore, TE Horwitz, JL Richards, PG Konikov, YV AF Khazanov, GV Moore, TE Horwitz, JL Richards, PG Konikov, YV TI Effect of anisotropic thermal conductivity on the temperature structure of the ionosphere-plasmasphere system SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAXWELLIAN TRANSPORT-EQUATIONS; POLAR WIND; FLOWS AB Anisotropic plasma hydrodynamics makes use of two heat fluxes representing the transfer of field-aligned and transverse (with respect to the external magnetic field) energies to describe thermal energy transfer. This is a considerably more complex treatment than isotropic plasma hydrodynamics in which only one heat flux component is considered. The present work analyzes the heal flux structure within the framework of anisotropic hydrodynamics and examines the effect of the anisotropic heat fluxes on the thermal plasma distribution both in the ionosphere and in the magnetically connected plasmasphere. The dependence of heat conductivities on the anisotropy parameter a=T-perpendicular to/T-parallel to is studied (T-perpendicular to and T-parallel to are transverse and field-aligned temperatures, respectively). The heat conductivities increase with field-aligned temperature (with decreasing value of a), thereby enhancing the thermal energy transfer. The analytical solution obtained for the heat conduction equation is used to examine the effect of the electron energy distribution anisotropy on the electron temperature in the plasmasphere. The dependence of heat conductivity on the parameter a has been shown to result in a variation of electron temperature compared with the isotropic case (a=1). The calculated plasmaspheric temperature values rise when a > 1 and fall when a < 1. The strongest effect of the temperature anisotropy on the derived value of the electron temperature occurs at high altitudes along a flux tube in the vicinity of the equatorial plane. Predictions of this simplified analytical model are compared to observations of temperature anisotropies in the ionosphere. Basic agreement in the magnitude and sense of the electron temperature anisotropy between the model and observations is found. C1 UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35807. INST TERR MAGNETISM IONOSPHERE & RADIOWAVE PROPAG,TROITSK 14092,MOSCOW REGION,RUSSIA. UNIV ALABAMA,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35807. RP Khazanov, GV (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 29 TC 7 Z9 7 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1996 VL 101 IS A6 BP 13399 EP 13406 DI 10.1029/96JA00889 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP353 UT WOS:A1996UP35300034 ER PT J AU Burlaga, LF Ness, NF AF Burlaga, LF Ness, NF TI Magnetic fields in the distant heliosphere approaching solar minimum: Voyager 1 and 2 observations during 1994 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID COSMIC-RAY MODULATION; MULTIFRACTAL STRUCTURE; SECTOR STRUCTURE; FLUCTUATIONS; STREAMS AB During 1994, Voyager 2 (V2) was at a heliocentric distance [R] = 43.4 AU and latitude [delta(s/c)] = 11.9 degrees S, while Voyager 1 (V1) was at [R] = 56.3 AU and [delta(s/c)] = 32.5 degrees N. The mean magnetic field strength observed by V1 during 1994 was 0.05 nT, the weakest and most distant magnetic field ever measured in situ. A bimodal distribution of azimuthal magnetic field directions was observed by V2, and a single-peaked distribution was observed by V1. Thus V2 was in the ''sector zone'' (the range of latitudes that contains the heliospheric current sheet), and V1 was in the unipolar region above it, consistent with the latitudes of the heliospheric current sheet obtained from an extrapolation of the neutral line computed from solar magnetic field observations. A lognormal distribution of the magnetic field strength (hourly averages) was observed for 95% of the V1 data and most of the V2 data. An approximately lognormal distribution of B is a general property of the heliospheric magnetic field, observed out to 58.1 AU and up to 32.6 degrees S latitude. During 1994 an exponential tail in the distribution of the magnetic field strength was observed by both V1 and V2 for fields stronger than average. An exponential tail in the magnetic field strength distribution was observed by V1 and V2 from 1983 to 1994 at latitudes from 11 degrees S to 33 degrees N and at distances from 13 to 58 AU. Thus an exponential tail of the distribution of magnetic field strengths is a basic property of the heliosphere beyond 13 AU. There was no significant latitudinal gradient in the exponential tail observed by V2 in the sector zone and observed by V1 above the sector zone during 1994. Multifractal structure in the large-scale fluctuations of the magnetic field strength was observed by V1 for periods from 8 hours to 256 hours equaling 10.7 days for the magnetic fields stronger than average. A multifractal spectrum is a general property of the large-scale magnetic field strength fluctuations, from 1983 through 1994 between 13 AU and 58 AU. There remains a need for a statistical theory of the solar wind that can account for these observations and for cosmic ray models that include the effect of multifractal magnetic field strength fluctuations. C1 UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716. RP Burlaga, LF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 629,GREENBELT,MD 20771, USA. NR 34 TC 23 Z9 23 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1996 VL 101 IS A6 BP 13473 EP 13481 DI 10.1029/96JA00523 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP353 UT WOS:A1996UP35300041 ER PT J AU Richardson, IG Wibberenz, G Cane, HV AF Richardson, IG Wibberenz, G Cane, HV TI The relationship between recurring cosmic ray depressions and corotating solar wind streams at <=1 AU: IMP 8 and Helios 1 and 2 anticoincidence guard rate observations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FORBUSH DECREASES; CURRENT SHEET; FLOW SYSTEMS; ACCELERATION; MODULATION; PROTONS; SPEED AB We examine the detailed relationship between recurrent cosmic ray depressions and corotating high-speed streams in the inner heliosphere near the ecliptic plane using counting rates from anticoincidence guards of instruments on the IMP 8, Helios 1, and Helios 2 spacecraft. These rates indicate the density of >60 MeV/amu ions with reasonable time resolution (similar to 15 min) and high counting statistics. Essentially all corotating streams are accompanied by significant particle depressions. The particle decrease commences most frequently (similar to 63% of events) at the leading edge of the stream which is typically colocated with the stream interface inside the corotating interaction region (CIR). If the depression starts ahead of the interface, there is usually an additional abrupt decrease at the interface. In similar to 61% of events the onset of the depression is closely associated with the onset of enhanced field turbulence which typically occurs near the stream leading edge. Minimum particle densities are generally found in the vicinity of the maximum solar wind speed in the high-speed stream. The density recovers during the declining phase of the stream. The observations are most consistent with modulation of the cosmic ray density in high-speed streams by the increase in solar wind speed. Enhanced scattering by turbulence in the CIR may also contribute near the onset of the depression, in particular in cases where the decrease commences ahead of the stream interface. The absence of a consistent relationship between the depressions and magnetic field enhancements suggests that localized particle drifts in the enhanced magnetic fields of CIRs do not produce the particle depressions. The observation of a depression is not dependent on the presence of a heliospheric current sheet crossing in the CIR, in contrast to previous reports. C1 CHRISTIAN ALBRECHTS UNIV KIEL,INST REINE & ANGEW KERNPHYS,D-24118 KIEL,GERMANY. UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. UNIV TASMANIA,DEPT PHYS,HOBART,TAS 7001,AUSTRALIA. RP Richardson, IG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 661,GREENBELT,MD 20771, USA. OI Richardson, Ian/0000-0002-3855-3634 NR 54 TC 52 Z9 52 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1996 VL 101 IS A6 BP 13483 EP 13496 DI 10.1029/96JA00547 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP353 UT WOS:A1996UP35300042 ER PT J AU Monacos, SP Morookian, JM Davis, L Bergman, LA Forouhar, S Sauer, JR AF Monacos, SP Morookian, JM Davis, L Bergman, LA Forouhar, S Sauer, JR TI All-optical WDM packet networks SO JOURNAL OF LIGHTWAVE TECHNOLOGY LA English DT Article AB This paper describes the components and subsystems for the inplementation of a multi-GHz optoelectronic data transport network using self-routing packets in a multi-hop network. The short packet payloads are compressed using optical wavelength division multiplexing techniques, and remain optical from source to destination while traversing the switching nodes, The routing is done with a lean, self-routing hot potato protocol in order to avoid the need for data storage at the switching nodes and to provide a fu;ed node latency equivalent to a few meters of fiber, Sustainable throughput both into and out of the electronic host at each node should exceed 10 Gb/s, Some technical details of the switching nodes and interfaces of the recirculating shuffle network, and the stepped wavelength laser arrays and testbed will be given. RP Monacos, SP (reprint author), JET PROP LAB,PASADENA,CA 91190, USA. NR 33 TC 8 Z9 9 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0733-8724 J9 J LIGHTWAVE TECHNOL JI J. Lightwave Technol. PD JUN PY 1996 VL 14 IS 6 BP 1356 EP 1370 DI 10.1109/50.511667 PG 15 WC Engineering, Electrical & Electronic; Optics; Telecommunications SC Engineering; Optics; Telecommunications GA UT346 UT WOS:A1996UT34600044 ER PT J AU Kleinrock, L Gerla, M Bambos, N Cong, J Gafni, E Bergman, L Bannister, J Monacos, SP Bujewski, T Hu, PC Kannan, B Kwan, B Leonardi, E Peck, J Palnati, P Walton, S AF Kleinrock, L Gerla, M Bambos, N Cong, J Gafni, E Bergman, L Bannister, J Monacos, SP Bujewski, T Hu, PC Kannan, B Kwan, B Leonardi, E Peck, J Palnati, P Walton, S TI The Supercomputer Supernet testbed: A WDM-based supercomputer interconnect SO JOURNAL OF LIGHTWAVE TECHNOLOGY LA English DT Article ID NETWORKS AB Current fiber optic networks effectively provide local connectivity among end user computing devices, and can serve as backbone fabric between LAN subnets across campus and metropolitan areas, However, combining both stream service (in which ATM excels) and low latency datagram service (in which cluster networks like Myrinet and POLO excel) has been difficult to realize, This paper describes a new wavelength division multiplexed (WDM) fiber optic network that supports both stream and datagram service and extends reach and functionality of low-latency, high bandwidth workstation clusters to a campus and MAN setting, The novel concept is based on combining the rich interconnect structure of WDM fiber optics with the fast, low-latency mesh of crossbar switches recently developed for workstation groups, This system, called the Supercomputer Supernet (SSN) achieves a high level of performance by replacing the point-to-point copper wire links with a parallel channel (WDM) fiber optic interconnect system, The novel scheme interconnects asynchronous wormhole routing switches used in parallel supercomputers via multi-channel WDM fiber optic links embedded in to an optical star (or tree) ''physical'' topology, WDM will be used to subdivide the very large fiber bandwidth into several channels, each of Gb/s bandwidth, WDM channels (supporting also time division multiplexing) will be established between modules, thus defining a dense ''virtual'' interconnection topology, which is dynamically reconfigurable and responds to changing traffic patterns, A pool of channels will be set aside for direct, end-to-end connections between crossbars, providing circuit-switched service for real-time traffic applications. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. AEROSP CORP,EL SEGUNDO,CA 90245. RP Kleinrock, L (reprint author), UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90024, USA. RI Leonardi, Emilio/A-1700-2011 OI Leonardi, Emilio/0000-0002-3070-4274 NR 25 TC 9 Z9 10 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0733-8724 J9 J LIGHTWAVE TECHNOL JI J. Lightwave Technol. PD JUN PY 1996 VL 14 IS 6 BP 1388 EP 1399 DI 10.1109/50.511669 PG 12 WC Engineering, Electrical & Electronic; Optics; Telecommunications SC Engineering; Optics; Telecommunications GA UT346 UT WOS:A1996UT34600046 ER PT J AU Johns, JWC Lu, Z Weber, M Sirota, JM Reuter, DC AF Johns, JWC Lu, Z Weber, M Sirota, JM Reuter, DC TI Absolute intensities in the nu(2) fundamental of N2O at 17 mu m SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID NITROUS-OXIDE; CM-1; CO2; SPECTROMETER; PARAMETERS; SPECTRUM; REGION AB Absolute intensity measurements have been made in the nu(2) fundamental band of nitrous oxide (N2O). The experiments were carried out independently in two laboratories and despite the fact that the two Fourier transform instruments are very different and required different data reduction techniques the results agree within the estimated experimental errors. The square of the transition dipole is found to be 4.7538(58) x 10(-3) D-2 and in addition there is a large Linear Herman-Wallis factor which gives rise to an R branch that is significantly stronger than the P branch. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP Johns, JWC (reprint author), NATL RES COUNCIL CANADA,STEACIE INST MOLEC SCI,100 SUSSEX DR,OTTAWA,ON K1A 0R6,CANADA. RI Weber, Mark/F-1409-2011 OI Weber, Mark/0000-0001-8217-5450 NR 31 TC 16 Z9 16 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD JUN PY 1996 VL 177 IS 2 BP 203 EP 210 DI 10.1006/jmsp.1996.0134 PG 8 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA UX327 UT WOS:A1996UX32700003 ER PT J AU Weber, M Sirota, JM Reuter, DC AF Weber, M Sirota, JM Reuter, DC TI l-Resonance intensity effects and pressure broadening of N2O at 17 mu m SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID TUNABLE-DIODE-LASER; Q-BRANCH; LINEAR-MOLECULES; NITROUS-OXIDE; NU-3 BAND; PARAMETERS; (N2O)-N-14-O-16; DEPENDENCE; LINEWIDTHS; 13.7-MU-M AB intensities of PR branch transitions in the three hotbands 2 nu(2)(2f) <-- nu(2)(1f), 2 nu(2)(2e) <-- nu(2)(1e), and 2 nu(2)(0e) <-- nu(2)(1e) have been measured using high resolution spectra recorded with the McMath FTS at the National Solar Observatory in Kitt Peak, Arizona. The two latter bands show intensity perturbations mostly due to rotational l-type doubling while the hot band ending in the (02(2f)0) state remains unperturbed. Based on mixing coefficients calculated from effective molecular constants, intensity perturbation factors were calculated which are shown to be equivalent to a quadratic term used in the Herman-Wallis factor expression. As part of the intensity retrieval, self-, N-2-, and He-broadening coefficients of N2O were determined in the nu(2) fundamental and the three hot bands, The Linewidths reported in this study have been combined with the best available literature data from other bands to retrieve temperature dependent relaxation rates due to rotationally inelastic collision based on a scaling law. (C) 1996 Academic Press, Inc. C1 NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771. RI Weber, Mark/F-1409-2011 OI Weber, Mark/0000-0001-8217-5450 NR 37 TC 18 Z9 18 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD JUN PY 1996 VL 177 IS 2 BP 211 EP 220 DI 10.1006/jmsp.1996.0135 PG 10 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA UX327 UT WOS:A1996UX32700004 ER PT J AU Eggleton, CD Pulliam, TH Ferziger, JH AF Eggleton, CD Pulliam, TH Ferziger, JH TI Numerical simulation of viscoelastic flow using flux difference splitting at moderate Reynolds numbers SO JOURNAL OF NON-NEWTONIAN FLUID MECHANICS LA English DT Article DE boundary layer; entry flow; viscoelastic ID COAL-WATER SUSPENSIONS; FINITE-ELEMENT; FLUIDS; HYPERBOLICITY; LIQUIDS AB An efficient numerical method for solving the Navier-Stokes equations is extended to allow solution of the equations of the Maxwell and Oldroyd B models of viscoelasticity at moderate Reynolds numbers where inertial terms cannot be ignored. The continuity equation is treated by the artificial compressibility method and the resulting set of equations is split into a hyperbolic set and one that contributes to the mixed character of the system. A flux difference splitting scheme is used to approximate the hyperbolic set and an implicit method is used to time march to steady state. The method is used to solve the channel entry problem. A grid refinement study is done in the entry region of the channel and the solution is matched to a downstream region solution. The latter is compared with the prediction of linear perturbation analysis. Very good agreement is found for the rate of development. Flow over a flat plate is studied and leading edge solutions are qualitatively compared to linear solutions, while the downstream solutions compare well quantitatively with predictions of boundary layer analysis. C1 STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305. NR 37 TC 8 Z9 8 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0377-0257 J9 J NON-NEWTON FLUID JI J. Non-Newton. Fluid Mech. PD JUN PY 1996 VL 64 IS 2-3 BP 269 EP 298 DI 10.1016/0377-0257(96)01431-0 PG 30 WC Mechanics SC Mechanics GA UY493 UT WOS:A1996UY49300008 ER PT J AU Lin, RQ Huang, NE AF Lin, RQ Huang, NE TI The Goddard coastal wave model .1. Numerical method SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID FLUX-CORRECTED TRANSPORT AB To select a wind wave model as the basis for developing a coupled wind wave-current model for coastal dynamics, the numerical schemes used in state-of-the-art wind wave models are examined analytically. The schemes used in the existing models contain serious numerical aliases leading to dissipation and dispersion. These numerical aliases could mistakenly be interpreted as part of the physical phenomena. To alleviate these shortcomings, a fourth-order semi-implicit scheme for transport-type models and a second-order semi-implicit scheme with a gradient-dependent directional filter for the conservation-type models are proposed. The traditional difficulty of a hyperbolic conservation law is surmounted by this directional filter. These new schemes and the new filter are insensitive to the sizes of the rime step and spatial grid and the magnitude of the group velocity; therefore, aliasing of the physical phenomena will not occur. Furthermore, the numerical dissipation and the dispersion of the new method are practically zero. Even though each computation step of these new schemes requires greater computing time, the total computing time is still considerably shorter than that in previous models because the time steps of the new schemes can be an order of magnitude greater than those used previously. C1 NASA, GODDARD SPACE FLIGHT CTR, HYDROSPHER PROC LAB, GREENBELT, MD 20771 USA. NR 20 TC 14 Z9 15 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-3670 EI 1520-0485 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD JUN PY 1996 VL 26 IS 6 BP 833 EP 847 DI 10.1175/1520-0485(1996)026<0833:TGCWMP>2.0.CO;2 PG 15 WC Oceanography SC Oceanography GA UU486 UT WOS:A1996UU48600001 ER PT J AU Lin, RQ Huang, NE AF Lin, RQ Huang, NE TI The Goddard coastal wave model .2. Kinematics SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID 3RD-GENERATION AB A new coastal wave model is being developed to study air-sea interaction processes in the coastal region. The kinematics of this model, which govern the wave propagation, are reported. This new model is based on the action conservation equation rather than on the energy transport equation; it also employs the full nonlinear dispersion relationship in water of arbitrary depth. With these improvements, it includes nonstationary wave-current interaction processes and functions in coastal regions with variable finite water depths. Numerical results show that these changes cause significant differences between the new model and the WAM model when waves encounter any steady or unsteady current, and when waves propagate over changing bottom topography in a shallow water region. Such conditions are very common and should not be neglected in the coastal regions. C1 NASA,GODDARD SPACE FLIGHT CTR,OCEANS LAB,GREENBELT,MD 20771. NR 18 TC 11 Z9 12 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD JUN PY 1996 VL 26 IS 6 BP 848 EP 862 DI 10.1175/1520-0485(1996)026<0848:TGCWMP>2.0.CO;2 PG 15 WC Oceanography SC Oceanography GA UU486 UT WOS:A1996UU48600002 ER PT J AU Whitten, RC AF Whitten, RC TI Tailhook 91 .2. Events at the Annual Tailhook Symposium - Assist-Inspect-Gen-Invest, Assist-Inspect-Gen-Dept-Inquir SO JOURNAL OF POLITICAL & MILITARY SOCIOLOGY LA English DT Book Review RP Whitten, RC (reprint author), NASA,USN RESERVE,WASHINGTON,DC, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU JOURNAL POLITICAL MILITARY SOCIOLOGY PI DE KALB PA DEPT SOCIOLOGY, NORTHERN ILLINOIS UNIV, DE KALB, IL 60115-2854 SN 0047-2697 J9 J POLIT MIL SOCIOL JI J. Polit. Mil. Soc. PD SUM PY 1996 VL 24 IS 1 BP 145 EP 149 PG 5 WC Political Science; Sociology SC Government & Law; Sociology GA VA946 UT WOS:A1996VA94600010 ER PT J AU Hovenier, JW Lumme, K Mishchenko, MI Voshchinnikov, NV Mackowski, DW Rahola, J AF Hovenier, JW Lumme, K Mishchenko, MI Voshchinnikov, NV Mackowski, DW Rahola, J TI Computations of scattering matrices of four types of non-spherical particles using diverse methods SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID DISCRETE-DIPOLE APPROXIMATION; ELECTROMAGNETIC SCATTERING; LIGHT-SCATTERING; SYSTEMS; SPHERES; GRAINS AB The scattering matrix as a function of scattering angle has been computed for four different homogeneous particles: a prolate spheroid, an oblate spheroid, a finite cylinder and a bisphere with touching components. The directions of the incident and scattered light beams, as well as the rotation axis of each particle, lie in the same plane. The particles considered have the same refractive index, volume and orientation of the rotation axis with respect to the incident light. The computations were performed with the (superposition) T-matrix method, the separation of variables method for spheroids and the discrete-dipole approximation. The results are presented in the form of tables and graphs. Their usefulness as benchmark results and some other aspects are also discussed. Copyright (C) 1996 Elsevier Science Ltd C1 UNIV HELSINKI OBSERV,SF-00130 HELSINKI,FINLAND. NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. ST PETERSBURG STATE UNIV,INST ASTRON,ST PETERSBURG,RUSSIA. AUBURN UNIV,DEPT MECH ENGN,AUBURN,AL 36849. CTR COMP SCI,ESPOO,FINLAND. RP Hovenier, JW (reprint author), FREE UNIV AMSTERDAM,DEPT PHYS & ASTRON,DE BOELELAAN 1081,1081 HV AMSTERDAM,NETHERLANDS. RI Voshchinnikov, Nikolai/J-3995-2013; Mackowski, Daniel/K-1917-2013; Mishchenko, Michael/D-4426-2012; Voshchinnikov, Nikolai/N-4665-2015 OI Voshchinnikov, Nikolai/0000-0001-8327-6894; Voshchinnikov, Nikolai/0000-0001-8327-6894 NR 33 TC 34 Z9 33 U1 1 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD JUN PY 1996 VL 55 IS 6 BP 695 EP 705 DI 10.1016/0022-4073(96)00067-2 PG 11 WC Optics; Spectroscopy SC Optics; Spectroscopy GA UT936 UT WOS:A1996UT93600001 ER PT J AU Margolis, JS AF Margolis, JS TI Hydrogen and helium broadening and pressure induced line shifts of (CH4)-C-13 in the nu(4) band SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID METHANE LINES; WIDTHS; CM-1; COEFFICIENTS; STRENGTHS; REGION AB Hydrogen and helium pressure induced broadening and line shifts of the nu(4) band of isotopic methane ((CH4)-C-13) have been measured at room temperature for many lines in the P, Q and R branches. The measurements were obtained using the Im Fourier Transform Spectrometer at the KPNO McMath Solar Telescope with a spectral resolution of 0.0065 cm(-1). Data were obtained for 266 absorption lines for a range of J values up to J = 16; the pressure broadening results are compared to similar measurements made for the common isotope (CH4)-C-12 and a small, but consistent variation is noted. Copyright (C) 1996 Published by Elsevier Science Ltd RP Margolis, JS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 15 TC 16 Z9 16 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD JUN PY 1996 VL 55 IS 6 BP 823 EP 836 DI 10.1016/0022-4073(95)00185-9 PG 14 WC Optics; Spectroscopy SC Optics; Spectroscopy GA UT936 UT WOS:A1996UT93600014 ER PT J AU Davis, A Marshak, A Wiscombe, W Cahalan, R AF Davis, A Marshak, A Wiscombe, W Cahalan, R TI Scale invariance of liquid water distributions in marine stratocumulus .1. Spectral properties and stationarity issues SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID CLOUDS; MODEL; CLIMATE; RAIN AB This study investigates the internal structure of marine stratocumulus (Sc) using the spatial fluctuations of liquid water content (LWC) measured along horizontal flights off the coast of southern California during the First ISCCP Regional Experiment (FIRE) in summer of 1987. The results of FIRE 87 data analyses are compared to similar ones for marine Sc probed during the Atlantic Stratocumulus Transition Experiment (ASTEX) in summer 1992 near the Azores. In this first of two parts, the authors use spectral analysis to determine the main scale-invariant regimes, defined by the ranges of scales where wavenumber spectra follow power laws; from there, they discuss stationarity issues. Although crucial for obtaining meaningful spatial statistics (e.g., in climate diagnostics), the importance of establishing stationarity - statistical invariance under translation - is often overlooked. The sequel uses multifractal analysis techniques and addresses intermittency issues, By improving our understanding of both nonstationarity and intermittency in atmospheric data, we are in a better position to formulate successful sampling strategies. Comparing the spectral responses of different instruments to natural LWC variability, the authors find scale breaks (characteristic scales separating two distinct power law regimes) that are spurious, being traceable to well-documented idiosyncrasies of the Johnson-Williams probe and forward scattering spectrometer probes. In data from the King probe, the authors find no such artifacts; all spectra are of the scale-invariant form k(-beta) with exponents beta in the range 1.1-1.7, depending on the flight. Using the whole FIRE 87 King LWC database, the authors find power-law behavior with beta = 1.36 +/- 0.06 from 20 m to 20 km. From a spectral vantage point, the ASTEX cloud system behaves statistically like a scaled-up version of FIRE 87: a similar exponent beta = 1.43 +/- 0.08 is obtained, but the scaling range is shifted to [60 m, 60 km], possibly due to the 2-3 times greater boundary layer thickness. Finally, the authors reassess the usefulness of spectral analysis: Its main shortcoming is ambiguity: very different looking stochastic processes can yield similar, even identical, spectra. This problem impedes accurate modeling of the LWC data and, ultimately, is why multifractal methods are required. Its main asset is applicability in stationary and nonstationary situations alike and, in conjunction with scaling, it can be used to detect nonstationary behavior in data. Having beta > 1, LWC fields in marine Sc are nonstationary within the scaling range and stationary only at larger scales. Nonstationarity implies long-range correlations, and we demonstrate the damage these cause when trying to estimate means and standard deviations with limited amounts of LWC data. RP Davis, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CLIMATE & RADIAT BRANCH,CODE 913,GREENBELT,MD 20771, USA. RI Cahalan, Robert/E-3462-2012; Wiscombe, Warren/D-4665-2012; Marshak, Alexander/D-5671-2012 OI Cahalan, Robert/0000-0001-9724-1270; Wiscombe, Warren/0000-0001-6844-9849; NR 44 TC 143 Z9 146 U1 0 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD JUN 1 PY 1996 VL 53 IS 11 BP 1538 EP 1558 DI 10.1175/1520-0469(1996)053<1538:SIOLWD>2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UP721 UT WOS:A1996UP72100003 ER PT J AU DelSole, T AF DelSole, T TI Can quasigeostrophic turbulence be modeled stochastically? SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID OSCILLATION AB Numerically generated data of quasigeostrophic turbulence in an equilibrated shear how are analyzed to determine the extent to which they can be modeled by a Markov model. The time lagged covariances are collected into a matrix, C-tau, and are substituted into the fluctuation-dissipation relation for a first-order Markov model with white noise forcing, CtauC0-1 = exp(A tau), to determine whether the relation is satisfied for a single dynamic operator A. The dynamic operator obtained by inverting the relation was found to depend on time lag. In particular, for small time lags (tau < 1 day), the eigenvectors and imaginary eigenvalues were independent of time lag, while the damping rates increased linearly with time lag. It is shown analytically that precisely this discrepancy occurs when the relation is applied to data generated by a red noise Markov model using a time lag that is small compared to the decorrelation time of the noise. Although a fourth-order Markov model with white noise can more accurately reproduce the covariances, the result of inverting the fluctuation-dissipation relation for such a model implies that the spectrum of the noise involves a superposition of stochastic processes of different spectral characteristics, in which case the effective dissipation and stochastic excitation cannot be completely solved by inverting such generalized fluctuation-dissipation relations. Projecting the data onto the dominant EOFs can distort the dynamic operator and introduce discrepancies even when the underlying data rigorously satisfies the fluctuation-dissipation relation. Despite this confounding factor, the consistency of the results at each order suggests that the effective dissipation is composed of low-order cross-stream gradients of streamfunction and that the excitation is correlated in the cross-stream direction within only a few Rossby radii. RP NASA, GODDARD SPACE FLIGHT CTR, DATA ASSIMILAT OFF, CODE 9103, GREENBELT, MD 20771 USA. NR 23 TC 36 Z9 36 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 EI 1520-0469 J9 J ATMOS SCI JI J. Atmos. Sci. PD JUN 1 PY 1996 VL 53 IS 11 BP 1617 EP 1633 DI 10.1175/1520-0469(1996)053<1617:CQTBMS>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UP721 UT WOS:A1996UP72100008 ER PT J AU Harrell, JA AF Harrell, JA TI Correction to constant-beamwidth one-octave bandwidth end-fire line array of loudspeakers (vol 43, pg 581, 1995) SO JOURNAL OF THE AUDIO ENGINEERING SOCIETY LA English DT Correction, Addition RP Harrell, JA (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AUDIO ENGINEERING SOC PI NEW YORK PA 60 E 42ND ST, NEW YORK, NY 10165-2520 SN 0004-7554 J9 J AUDIO ENG SOC JI J. Audio Eng. Soc. PD JUN PY 1996 VL 44 IS 6 BP 507 EP 507 PG 1 WC Acoustics; Engineering, Multidisciplinary SC Acoustics; Engineering GA UU682 UT WOS:A1996UU68200005 ER PT J AU Milman, M Redding, D Needels, L AF Milman, M Redding, D Needels, L TI Analysis of curvature sensing for large-aperture adaptive optics systems SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article AB We present an analysis of the curvature sensing method and the associated wave-front reconstruction problem for adaptive optics applications. The analysis includes characterizations of the nonlinear, diffraction, and noise effects for curvature sensing. Reconstruction properties are shown to be characterized in terms of the eigenvalues of a discretized Laplacian operator. A comparison of reconstruction performance for curvature and slope sensing is presented. Simulations based on the Keck telescope optical prescription are used to verify the analysis. (C) 1996 Optical Society of America RP Milman, M (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 18 TC 4 Z9 6 U1 3 U2 4 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0740-3232 J9 J OPT SOC AM A JI J. Opt. Soc. Am. A-Opt. Image Sci. Vis. PD JUN PY 1996 VL 13 IS 6 BP 1226 EP 1238 DI 10.1364/JOSAA.13.001226 PG 13 WC Optics SC Optics GA UM589 UT WOS:A1996UM58900011 ER PT J AU Gunapala, S Sundaram, M Bandara, S AF Gunapala, S Sundaram, M Bandara, S TI Quantum wells stare at long-wave IR scenes SO LASER FOCUS WORLD LA English DT Article AB Advances in growth at gallium arsenide semiconductors permits fabrication of quantum-well infrared photodetectors sensitive to long-wavelength infrared radiation. C1 CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91125 USA. RP Gunapala, S (reprint author), CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 0 TC 2 Z9 2 U1 1 U2 1 PU PENNWELL PUBL CO PI NASHUA PA 98 SPIT BROOK RD, NASHUA, NH 03062-2801 USA SN 0740-2511 J9 LASER FOCUS WORLD JI Laser Focus World PD JUN PY 1996 VL 32 IS 6 BP 233 EP + PG 6 WC Optics SC Optics GA V2888 UT WOS:000168852000045 ER PT J AU Morris, DS AF Morris, DS TI Seal predation at salmon farms in Maine, an overview of the problem and potential solutions SO MARINE TECHNOLOGY SOCIETY JOURNAL LA English DT Article AB Salmon aquaculture facilities in Downeast Maine are occasionally attacked by harbor seals and gray seals. The predators kill and injure valuable fish and may damage net-pens allowing farm-fish to escape. Industry proponents claim up to 10% of the industry's farmgate value is lost to seal predation. In addition to financial impacts, the escapement of cultured fish may pose a threat to indigenous Atlantic salmon stocks. Salmon growers in Maine employ a variety of predator control measures-netting systems, underwater acoustic devices and pyrotechnics-but no battery of protections seems to be 100% effective. In the past, those seals who could defeat deterrence strategies would be targeted for lethal, removal. Recent amendments to the Marine Mammal protection Act (MMPA), however now prohibit the killing of depredating seals. This paper provides an overview of the problem, surveys technological and non-technological solutions and mitigating measures, and describes the work of a stakeholder task force convened by the National Marine Fisheries Service to investigate the matter. RP Morris, DS (reprint author), NATL MARINE FISHERIES SERV,GLOUCESTER,MA 01930, USA. NR 18 TC 16 Z9 17 U1 0 U2 12 PU MARINE TECHNOLOGY SOC INC PI WASHINGTON PA C/O I CLAYION MATTHEWS, 1828 L ST, NW, 9TH FL, WASHINGTON, DC 20036 SN 0025-3324 J9 MAR TECHNOL SOC J JI Mar. Technol. Soc. J. PD SUM PY 1996 VL 30 IS 2 BP 39 EP 43 PG 5 WC Engineering, Ocean; Oceanography SC Engineering; Oceanography GA VG427 UT WOS:A1996VG42700006 ER PT J AU Bhat, K Chang, KJ Aggarwal, MD Wang, WS Penn, BG Frazier, DO AF Bhat, K Chang, KJ Aggarwal, MD Wang, WS Penn, BG Frazier, DO TI Synthesis and characterization of various Schiff bases for non-linear optical applications SO MATERIALS CHEMISTRY AND PHYSICS LA English DT Article DE aniline moiety; optical properties; salicylidenes; Schiff bases; substitution ID MOLECULES; SUSCEPTIBILITIES AB A series of salicylidenes have been synthesized to investigate non-linear optical properties. Attempts have been made to correlate second harmonic generation properties of these Schiff base compounds with ring substitution patterns, as well as the nature of the ring substituents. The result of double substitutions to the aniline moiety is also discussed. It is reported that meta substitution in the aniline moiety gives comparable values for second harmonic generation with respect to urea. C1 ALABAMA A&M UNIV,DEPT PHYS,NORMAL,AL 35762. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP Bhat, K (reprint author), ALABAMA A&M UNIV,DEPT CHEM,NORMAL,AL 35762, USA. NR 18 TC 33 Z9 33 U1 0 U2 2 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0254-0584 J9 MATER CHEM PHYS JI Mater. Chem. Phys. PD JUN PY 1996 VL 44 IS 3 BP 261 EP 266 DI 10.1016/0254-0584(96)80066-6 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA UU372 UT WOS:A1996UU37200010 ER PT J AU Sikora, M Sol, H Begelman, MC Madejski, GM AF Sikora, M Sol, H Begelman, MC Madejski, GM TI Radiation drag in relativistic active galactic nucleus jets SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE plasmas; radiation mechanisms, nonthermal; methods, analytical galaxies, active; galaxies, jets; galaxies, nuclei ID DOUBLE RADIO-SOURCES; ACCRETION DISKS; MODEL; COLLIMATION; INJECTION; BLAZARS; ENERGY; PLASMA AB We present the first comprehensive study of radiation drag imposed on both cold and relativistic plasma components in a jet propagating at relativistic speeds through a dense radiation field, Earlier work showed that radiation drag acting on the cold plasma alone drops very fast with distance from the central source and can affect the jet dynamics only very close to the central source (up to 10-30 gravitational radii), and only if the jet plasma is strongly dominated by electron-positron pairs. In the case of radiation drag acting on a jet through relativistic electrons/positrons, the distance dependence can be much flatter, actually being determined by the distance dependence of the injection rate of relativistic particles. However, we show that such radiation drag can be dynamically important only for magnetically dominated jets in which the injection luminosity of relativistic electrons/positrons exceeds the kinetic luminosity of the jet, Our studies are performed using a radiation tensor formalism, which is the most suitable and elegant method for calculating both forces and cooling rates resulting from Compton scattering of an ambient radiation field by relativistic plasma in a jet. Simple analytic formulae, derived using this method, allow one to make quick estimates of dynamical and radiative effects resulting from the interaction of relativistic jets with different external radiation held distributions. C1 DEPT ASTROPHYS RELATIVISTE & COSMOL,MEUDON,FRANCE. UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. NIST,BOULDER,CO 80309. UNIV COLORADO,DEPT ASTROPHYS PLANETARY & ATMOSPHER SCI,BOULDER,CO 80309. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Sikora, M (reprint author), NICHOLAS COPERNICUS ASTRON CTR,BARTYCKA 18,PL-00716 WARSAW,POLAND. NR 32 TC 67 Z9 68 U1 0 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUN 1 PY 1996 VL 280 IS 3 BP 781 EP 796 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP516 UT WOS:A1996UP51600014 ER PT J AU Hellier, C Mukai, K Ishida, M Fujimoto, R AF Hellier, C Mukai, K Ishida, M Fujimoto, R TI The X-ray spectrum of the intermediate polar AO Piscium SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE accretion, accretion discs; binaries, close; stars, individual, AO Psc; novae, cataclysmic variables; X-rays, stars ID LIGHT-CURVES; EX HYDRAE; ACCRETION; EMISSION; DWARFS AB An ASCA observation of AO Psc shows an X-ray lightcurve dominated by a sinusoidal spin pulse. There are absorption dips recurring with the orbital cycle, but otherwise no other periodic variations in the lightcurve. AO Psc is thus an ideal system for studying the spectral characteristics of the spin pulse. We find that the spectrum can be modelled as a 10-20 keV bremsstrahlung. To reproduce the spin pulse we require a leaky photoelectric absorber, increasing in both column and covering fraction from spin maximum to spin minimum. This absorber consists of at least two phases of different density. The derived parameters match well with the 'accretion curtain' model for intermediate polars. If the accretion flow is channelled on to an area similar to 10(-3) of the white dwarf surface, electron scattering in the highly ionized post-shock region is significant. However, we cannot rule out either disappearance of the lower pole or opacity due to dense blobs effecting similar spectral changes. We find evidence for cold, helium-like and hydrogen-like iron emission, and also helium-like argon emission, from which we derive a plasma temperature compatible with that from our continuum modelling. The thermal lines are unusually broad. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. RP Hellier, C (reprint author), UNIV KEELE,DEPT PHYS,KEELE ST5 5BG,STAFFS,ENGLAND. NR 34 TC 34 Z9 34 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUN 1 PY 1996 VL 280 IS 3 BP 877 EP 887 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP516 UT WOS:A1996UP51600023 ER PT J AU Halverson, J Garstang, M Scala, J Tao, WK AF Halverson, J Garstang, M Scala, J Tao, WK TI Water and energy budgets of a Florida mesoscale convective system: A combined observational and modeling study SO MONTHLY WEATHER REVIEW LA English DT Article ID TROPICAL SQUALL LINE; COPT 81 EXPERIMENT; MOISTURE BUDGETS; CLOUD CLUSTERS; NUMERICAL-SIMULATION; WEST-AFRICA; HEAT; PRECIPITATION; CUMULUS; PARAMETERIZATION AB Mesoscale water and energy budgets are diagnosed for a squall line during the Convection and Precipitation Electrification Experiment and combined with the results of the two-dimensional Goddard Cumulus Ensemble Model. The fine temporal and spatial resolution of cloud-scale processes contained in the model is used to reduce uncertainty in the diagnosed water budget residual and, thus, to arrive at a good estimate of storm-total rainfall. Profiles of cumulus heating (Q(1)) and drying (Q(2)) inferred from the sounding observations are in turn compared with the cloud-scale energy budget terms calculated from the model. This comparison reveals near-agreement in the magnitude and vertical distribution of the peak Q(1) and Q(2) and also the relative size of the heating and drying at different levels in the column. When the size of the mesoscale convective disturbance is approximately the same as the sounding observation network, it may be wrong to assume that the diagnosed vertical eddy heat transport accounts for most of the total eddy transport of moist static energy, F. The cloud model is used to resolve the relative contribution of the horizontal and vertical eddy flux convergence of heat and moisture, and thus it serves as a guide to interpreting the sounding-diagnosed total flux. The model results suggest that although the mean column vertical flux convergence is significantly larger than the column-mean horizontal flux convergence, the horizontal flux convergence does play a significant role in midlevels of the convective region. This flux convergence may be associated with a strong front-to-rear inflow that develops during the mature stage of the squall line. This study suggests that when combined with the independent results of a mesoscale cloud model, the sounding diagnostics can provide a sensitivity test for the Tropical Rainfall Measuring Mission measurements of rainfall and diabatic heating over the life cycle of an entire mesoscale convective system. RP Halverson, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,ATMOSPHERES LAB,CODE 912,GREENBELT,MD 20771, USA. NR 43 TC 10 Z9 10 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD JUN PY 1996 VL 124 IS 6 BP 1161 EP 1180 DI 10.1175/1520-0493(1996)124<1161:WAEBOA>2.0.CO;2 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UP593 UT WOS:A1996UP59300009 ER PT J AU Bloom, SC Takacs, LL DaSilva, AM Ledvina, D AF Bloom, SC Takacs, LL DaSilva, AM Ledvina, D TI Data assimilation using incremental analysis updates SO MONTHLY WEATHER REVIEW LA English DT Article ID DYNAMIC-INITIALIZATION; OPTIMAL EXCITATION; SCHEME; WAVES AB The IAU (incremental analysis updating) process incorporates analysis increments into a model integration in a gradual manner. It does this by using analysis increments as constant forcings in a model's prognostic equations over a 6-h period centered on an analysis time. A linear analysis of the IAU procedure shows it to have the attractive properties of a low-pass time filter. The IAU process affects the response of the model to the analysis increments, and it leaves the model state unaffected where there were no data to assimilate. This result is contrasted with a simple dynamical relaxation (or ''nudging'') scheme, which is shown, in this linear analysis, to have less desirable response characteristics, both from the analysis increments and from the background state of the model. The behavior of IAU in the context of the Goddard Earth Observing System (GEOS) Data Assimilation System is examined using a combination of large-scale diagnostics from month-long assimilations and derailed diagnostics from short assimilations. These studies indicate that IAU assimilations have improved observed-minus-forecast statistics and improved globally averaged precipitation by removing spinup effects. The detailed diagnostics of the behavior of the GEOS system with IAU corroborate the results of the linear analysis of the response behavior of IAU. C1 GEN SCI CORP,LAUREL,MD 20707. RP Bloom, SC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,DATA ASSIMILAT OFF,ATMOSPHERES LAB,CODE 9104,GREENBELT,MD 20771, USA. RI da Silva, Arlindo/D-6301-2012 OI da Silva, Arlindo/0000-0002-3381-4030 NR 21 TC 345 Z9 349 U1 0 U2 14 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD JUN PY 1996 VL 124 IS 6 BP 1256 EP 1271 DI 10.1175/1520-0493(1996)124<1256:DAUIAU>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UP593 UT WOS:A1996UP59300015 ER PT J AU Bogart, D AF Bogart, D TI Inconsistencies in widely used Monte Carlo methods for precise calculation of radial resonance captures in uranium fuel rods SO NUCLEAR SCIENCE AND ENGINEERING LA English DT Article AB Although resonance neutron captures for U-238 in water-moderated lattices are known to occur near moderator-fuel interfaces, the sharply attenuated spatial captures here have not been calculated by multigroup transport or Monte Carlo methods. Advances in computer speed and capacity have restored interest in applying Monte Carlo methods to evaluate spatial resonance captures in fueled lattices. Recently published studies have placed complete reliance on the ostensible precision of the Monte Carte approach without auxiliary confirmation that resonance processes were followed adequately or that the Monte Carlo method was applied appropriately. Other methods of analysis that have evolved from early resonance integral theory have provided a basis for an alternative approach to determine radial resonance captures in fuel rods. A generalized method has been formulated and confirmed by comparison with published experiments of high spatial resolution for radial resonance captures in metallic uranium rods. The same analytical method has been applied to uranium-oxide fuels. The generalized method defined a spatial effective resonance cross section that is a continuous function of distance from the moderator-fuel interface and enables direct calculation of precise radial resonance capture distributions in fuel rods. This generalized method is used as a reference for comparison with two recent independent studies that have employed different Monte Carlo codes and cross-section libraries. The Monte Carlo studies have been found to undercount reference radial resonance captures in the moderator-fuel interface region. The steep radial capture gradients within 0.50 mm of the interface account for the majority of resonance captures and take place where Monte Carlo spatial resolution is poor and the effects of resonance peaks on neutron flux are large. Inconsistencies in the Monte Carlo application or in how point wise cross-section libraries are sampled may exist. It is shown that refined Monte Carlo solutions with improved spatial resolution would not asymptotically approach the reference spatial capture distributions. It is suspected that the resolved resonance peak and off peak cross sections may not be represented or accounted for appropriately in the Monte Carte calculations and should be reviewed. If these inconsistencies were cleared up, use of the generalized method might very well challenge the need to perform further Monte Carlo studies of radial resonance captures for isolated uranium-oxide fuel rods. RP Bogart, D (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 14 TC 1 Z9 1 U1 0 U2 0 PU AMER NUCLEAR SOCIETY PI LA GRANGE PK PA 555 N KENSINGTON AVENUE, LA GRANGE PK, IL 60525 SN 0029-5639 J9 NUCL SCI ENG JI Nucl. Sci. Eng. PD JUN PY 1996 VL 123 IS 2 BP 228 EP 237 PG 10 WC Nuclear Science & Technology SC Nuclear Science & Technology GA UP972 UT WOS:A1996UP97200006 ER PT J AU Scholl, MS Padilla, GP Wang, YW AF Scholl, MS Padilla, GP Wang, YW TI Design of a high-resolution telescope for an imaging sensor to characterize a (Martian) landing site (vol 34, pg 3222, 1995) SO OPTICAL ENGINEERING LA English DT Correction, Addition C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Scholl, MS (reprint author), CTR INVEST OPT,APARTADO POSTAL 1-948,LEON 37000,GUANAJUATO,MEXICO. NR 1 TC 0 Z9 0 U1 0 U2 0 PU SOC PHOTO-OPT INSTRUM ENG PI BELLINGHAM PA PO BOX 10, BELLINGHAM, WA 98227-0010 SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD JUN PY 1996 VL 35 IS 6 BP 1799 EP 1799 DI 10.1117/1.601122 PG 1 WC Optics SC Optics GA UR464 UT WOS:A1996UR46400044 ER PT J AU Soding, A Glassmeier, KH Fuselier, SA Neubauer, FM Tsurutani, BT AF Soding, A Glassmeier, KH Fuselier, SA Neubauer, FM Tsurutani, BT TI Comparison of the wave energy transport at comets p/Halley and p/Giacobini-Zinner SO PLANETARY AND SPACE SCIENCE LA English DT Article ID SOLAR-WIND; ELSASSER VARIABLES; GIACOBINI-ZINNER; ALFVEN WAVES; HALLEY; PLASMA; MAGNETOMETER; PICKUP; IONS; GAS AB Using magnetic field, plasma density and flow observations from spacecraft flybys of two comets, variables are determined in order to study, wave propagation directions. The inbound path of the Giotto spacecraft flyby of comet p/Halley is investigated outside the bow shock (between 10:36 and 19:11 LUT on March 13, 1986, corresponding to distances from 3.3 x 10(6) to 1.2 x 10(6) km from the nucleus) and inbound path of the ICE spacecraft flyby of comet p/Giacobini-Zinner is investigated outside of the bow wave (between 00:00 and 9:24 UT and between 12:25 and 23:30 UT on September 11, 1985, corresponding to distances from 8.5 x 10(3) to 1.2 x 10(5) km from the nucleus and from 1.0 x 10(5) to 9.3 x 10(5) km from the nucleus respectively). The interaction of cometary pick-up-ions and the solar wind expected to generate waves which are assumed to be dominated by field-aligned propagating Alfven waves. This predicted wave propagation combined with wave modes generated by the ion cyclotron resonance instability are compared with observed wave properties. Three mhd-modes are possible: right-hand polarized waves propagating toward the Sun (RH(-)) and left-hand polarized waves propagating toward (LH(-)) and away from the Sun (LH(+)). Plasma conditions dictate that the RH(-) mode is the most unstable mode and satisfactory agreement is found between observed and predicted energy flow directions in regions outside the bow shock at Halley and the bow wave at Giacobini Zinner, where local cometary ion pick-up conditions dominate. Copyright (C) 1996 Elsevier Science Ltd C1 TECH UNIV CAROLO WILHELMINA BRAUNSCHWEIG,INST METEOROL & GEOPHYS,D-38106 BRAUNSCHWEIG,GERMANY. LOCKHEED PALO ALTO RES LABS,DEPT 9120,PALO ALTO,CA 94304. CALTECH,JPL,PASADENA,CA 91109. RP Soding, A (reprint author), UNIV COLOGNE,INST GEOPHYS & METEOROL,ALBERTUS MAGNUS PL,D-50923 COLOGNE,GERMANY. NR 21 TC 0 Z9 0 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD JUN PY 1996 VL 44 IS 6 BP 547 EP 553 DI 10.1016/0032-0633(96)00030-X PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW173 UT WOS:A1996UW17300005 ER PT J AU Illingsworth, ML Banks, BA Smith, JW Jayne, D Garlick, RG Rutledge, SK deGroh, KK AF Illingsworth, ML Banks, BA Smith, JW Jayne, D Garlick, RG Rutledge, SK deGroh, KK TI Plasma and beam facility atomic oxygen erosion of a transition metal complex SO PLASMA CHEMISTRY AND PLASMA PROCESSING LA English DT Article DE atomic oxygen; erosion; plasma; atomic beam facility; zirconium complex; weight loss; optical photography; profilometry; diffuse reflectance spectroscopy; total transmittance spectroscopy; scanning electron microscopy; wavelength dispersive X-ray spectroscopy; X-ray diffraction; X-ray photoelectron spectroscopy ID MOLECULAR-STRUCTURE; ELECTRON; CRYSTAL AB Glassy residues of the complex bis(N,N'-disalicylidene-1,2-phenylenediamino)zirconium(IV), Zr(dsp)(2), on glass slides were exposed to atomic oxygen in a plasma asher or an atomic beam facility for various amounts of time in order to study the erosion process, determine tire rate of erosion, and learn the chemical identity of the residue. The exposed films were characterized by weight loss, optical photography, profilometry, diffuse reflectance and total transmittance spectroscopy, scanning electron microscopy (SEM) with wavelength dispersive X-ray spectrometry (WDS), X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). Results indicate that these films erode much more slowly polyimide (Kapton(TM)) film under identical conditions, that tire erosion is very nonuniform, and that zirconium dioxide is the predominant product after extended exposure. This complex is currently being evaluated as a polymer additive. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP Illingsworth, ML (reprint author), ROCHESTER INST TECHNOL,DEPT CHEM,ROCHESTER,NY 14623, USA. NR 16 TC 7 Z9 7 U1 0 U2 1 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0272-4324 J9 PLASMA CHEM PLASMA P JI Plasma Chem. Plasma Process. PD JUN PY 1996 VL 16 IS 2 BP 209 EP 225 DI 10.1007/BF01570179 PG 17 WC Engineering, Chemical; Physics, Applied; Physics, Fluids & Plasmas SC Engineering; Physics GA UM013 UT WOS:A1996UM01300005 ER PT J AU Adelstein, BD Johnston, ER Ellis, SR AF Adelstein, BD Johnston, ER Ellis, SR TI Dynamic response of electromagnetic spatial displacement trackers SO PRESENCE-TELEOPERATORS AND VIRTUAL ENVIRONMENTS LA English DT Article AB Overall system latency-the elapsed time from input human motion until the immediate consequences of that input are available in the display-is one of the most frequently cited shortcoming of current virtual environment (VE) technology, Given that spatial displacement trackers are employed to monitor head and hand position and orientation in many VE applications the dynamic response intrinsic to these devices is an unavoidable contributor to overall system latency. In this paper, we describe a testbed and method for measurement of tracker dynamic response that use a motorized rotary swing arm to sinusoidally displace the VE sensor at a number of frequencies spanning the bandwidth of volitional human movement. During the tests, actual swing arm angle and VE sensor reports are collected and time stamped. By calibrating the time stamping technique, the tracker's internal transduction and processing time are separated from data transfer and host computer software execution latencies. We have used this testbed to examine several VE sensors-most recently to compare latency, gain, and noise characteristics of two commercially available electromagnetic trackers: Ascension Technology Corp.'s Flock of Birds(TM) and Polhemus Inc.'s Fastra(TM). C1 UNIV CALIF BERKELEY,BERKELEY,CA 94720. RP Adelstein, BD (reprint author), NASA,AMES RES CTR,MS 262-2,MOFFETT FIELD,CA 94035, USA. NR 22 TC 21 Z9 21 U1 0 U2 0 PU MIT PRESS PI CAMBRIDGE PA 55 HAYWARD ST JOURNALS DEPT, CAMBRIDGE, MA 02142 SN 1054-7460 J9 PRESENCE-TELEOP VIRT JI Presence-Teleoper. Virtual Env. PD SUM PY 1996 VL 5 IS 3 BP 302 EP 318 PG 17 WC Computer Science, Cybernetics; Computer Science, Software Engineering SC Computer Science GA VF835 UT WOS:A1996VF83500004 PM 11540397 ER PT J AU Aller, LH Hyung, S Feibelman, WA AF Aller, LH Hyung, S Feibelman, WA TI The spectrum of the planetary nebula NGC 6790 SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID LINE INTENSITIES; DISTANCES; CATALOG; SULFUR AB International Ultraviolet Explorer (IUE) and optical region spectroscopic observations are presented for the medium-excitation planetary nebula (PN) NGC 6790, which displays a rich spectrum permitting application of several diagnostic ratios and the calculation of a number of ionic concentrations, N(ion)/N(H+). NGC 6790 seems to be a relatively young object which may represent a stage of development only slightly beyond that of a PN such as Hb 12. The diagnostics for NGC 6790 suggest a rather large density range, although not one as great as that found in IC 4997. An attempt is made to calculate a plausible, simple spherically symmetrical model. We suggest that NGC 6790 may serve as a prototype ''standard'' for PN of intermediate age, density, and evolutionary development, Further modeling attempts would appear inappropriate until images of high spatial resolution become available. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP Aller, LH (reprint author), UNIV CALIF LOS ANGELES,DEPT PHYS & ASTRON,LOS ANGELES,CA 90095, USA. NR 34 TC 23 Z9 23 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD JUN PY 1996 VL 108 IS 724 BP 488 EP 499 DI 10.1086/133754 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UQ724 UT WOS:A1996UQ72400003 ER PT J AU Banks, HT Propst, G Silcox, RJ AF Banks, HT Propst, G Silcox, RJ TI A comparison of time domain boundary conditions for acoustic waves in wave guides SO QUARTERLY OF APPLIED MATHEMATICS LA English DT Article ID EQUATIONS AB We consider several types of boundary conditions in the context of time domain models for acoustic waves, Experiments with four different duct terminations (hardwall, free radiation, foam, wedge) were carried out in a wave duct from which reflection coefficients over a wide frequency range were measured. These reflection coefficients are used to estimate parameters in the time domain boundary conditions, and a comparison of the relative merits of the models in describing the data is presented. Boundary conditions that yield a good fit of the model to the experimental data were found for all duct terminations except the wedge. C1 GRAZ UNIV,INST MATH,A-8010 GRAZ,AUSTRIA. NASA,LANGLEY RES CTR,ACOUST DIV,HAMPTON,VA 23665. RP Banks, HT (reprint author), N CAROLINA STATE UNIV,CTR RES SCI COMPUTAT,RALEIGH,NC 27695, USA. NR 18 TC 2 Z9 2 U1 0 U2 0 PU AMER MATHEMATICAL SOC PI PROVIDENCE PA 201 CHARLES ST, PROVIDENCE, RI 02940-2213 SN 0033-569X J9 Q APPL MATH JI Q. Appl. Math. PD JUN PY 1996 VL 54 IS 2 BP 249 EP 265 PG 17 WC Mathematics, Applied SC Mathematics GA UL519 UT WOS:A1996UL51900004 ER PT J AU Nerney, S Schmahl, EJ Musielak, ZE AF Nerney, S Schmahl, EJ Musielak, ZE TI Limits to extensions of Burgers' equation SO QUARTERLY OF APPLIED MATHEMATICS LA English DT Article AB The vector Burgers' equation is extended to include pressure gradients and gravity. It is shown that within the framework of the Cole-Hopf transformation there are no physical solutions to this problem. This result is important because it clearly demonstrates that any extension of Burgers' equation to more interesting physical situations is strongly limited. C1 OHIO UNIV,LANCASTER,OH. UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. UNIV ALABAMA,DEPT MECH & AEROSP ENGN,HUNTSVILLE,AL 35899. RP Nerney, S (reprint author), NASA,MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL, USA. NR 5 TC 1 Z9 1 U1 0 U2 1 PU AMER MATHEMATICAL SOC PI PROVIDENCE PA 201 CHARLES ST, PROVIDENCE, RI 02940-2213 SN 0033-569X J9 Q APPL MATH JI Q. Appl. Math. PD JUN PY 1996 VL 54 IS 2 BP 385 EP 393 PG 9 WC Mathematics, Applied SC Mathematics GA UL519 UT WOS:A1996UL51900012 ER PT J AU Zeitlin, C Heilbronn, L Miller, J Schimmerling, W Townsend, LW Tripathi, RK Wilson, JW AF Zeitlin, C Heilbronn, L Miller, J Schimmerling, W Townsend, LW Tripathi, RK Wilson, JW TI The fragmentation of 510 MeV/nucleon iron-56 in polyethylene .2. Comparisons between data and a model SO RADIATION RESEARCH LA English DT Article ID 670A MEV NE-20; TRANSPORT-THEORY; DEPTH; WATER AB The results of a Monte Carlo model for calculating fragment fluences and LET spectra are compared to data taken with 600 MeV/nucleon iron ions incident on an accelerator beamline configured for irradiation of biological samples, with no target and with 2, 5 and 8 cm of polyethylene. The model uses a multi-generation nuclear fragmentation code, coupled with a formulation of ionization energy loss based on the Bethe-Bloch equation. In the region where the data are reliable and the experimental acceptance is well understood, many of the features of the experimental spectra are well replicated by the model. To obtain good agreement with the experimental data, the model must allow for at least two generations of fragment production in the target. (C) 1996 by Radiation Research Society C1 UNIV SPACE RES ASSOC,WASHINGTON,DC 20024. UNIV TENNESSEE,DEPT NUCL ENGN,KNOXVILLE,TN 37996. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP Zeitlin, C (reprint author), UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,BERKELEY,CA 94720, USA. RI Heilbronn, Lawrence/J-6998-2013 OI Heilbronn, Lawrence/0000-0002-8226-1057 NR 11 TC 22 Z9 22 U1 0 U2 2 PU RADIATION RESEARCH SOC PI OAK BROOK PA 2021 SPRING RD, STE 600, OAK BROOK, IL 60521 SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD JUN PY 1996 VL 145 IS 6 BP 666 EP 672 DI 10.2307/3579356 PG 7 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA UM958 UT WOS:A1996UM95800002 PM 8643825 ER PT J AU Hook, SJ Kahle, AB AF Hook, SJ Kahle, AB TI The micro Fourier Transform Interferometer (mu FTIR) - A new field spectrometer for acquisition of infrared data of natural surfaces SO REMOTE SENSING OF ENVIRONMENT LA English DT Article AB A lightweight, rugged, high-spectral-resolution interferometer has been built by Designs and Prototypes based on a set of specifications provided by the Jet Propulsion Laboratory and Dr. J. W. Salisbury (Johns Hopkins University). The instrument, the micro Fourier Transform Interferometer (mu FTIR), permits the acquisition of infrared spectra of natural surfaces. Such data can be used to validate low and high spectral resolution data acquired remotely from aircraft and spacecraft in the 3-5 mu m and 8-14 mu m atmospheric windows. The instrument has a spectral resolution of similar to 6 wavenumbers, weighs 16 kg including batteries and computer, and can be operated easily by two people in the field. Laboratory analysis indicates the instrument is spectrally calibrated to better than 1 wavenumber and the radiometric accuracy is < 0.5 K if the radiances from the blackbodies used for calibration bracket the radiance from the sample. Several examples of field spectra are provided for a variety of rock types, minerals, and vegetation. RP Hook, SJ (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MS 183-501,PASADENA,CA 91109, USA. NR 12 TC 51 Z9 54 U1 1 U2 7 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD JUN PY 1996 VL 56 IS 3 BP 172 EP 181 DI 10.1016/0034-4257(95)00231-6 PG 10 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA UX246 UT WOS:A1996UX24600003 ER PT J AU Bryan, K Caudill, LF AF Bryan, K Caudill, LF TI An inverse problem in thermal imaging SO SIAM JOURNAL ON APPLIED MATHEMATICS LA English DT Article DE inverse problems; nondestructive testing; first-kind integral equations ID TOMOGRAPHY AB This paper examines uniqueness and stability results for an inverse problem in thermal imaging. The goal is to identify an unknown boundary of an object by applying a heat flux and measuring the induced temperature on the boundary of the sample. The problem is studied in both the case in which one has data at every point on the boundary of the region and the case in which only finitely many measurements are available. An inversion procedure is developed and used to study the stability of the inverse problem for various experimental configurations. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681. UNIV KENTUCKY,DEPT MATH,LEXINGTON,KY 40506. RP Bryan, K (reprint author), ROSE HULMAN INST TECHNOL,DEPT MATH,5500 WABASH AVE,TERRE HAUTE,IN 47803, USA. NR 18 TC 40 Z9 40 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER PH#382-9800, PHILADELPHIA, PA 19104-2688 SN 0036-1399 J9 SIAM J APPL MATH JI SIAM J. Appl. Math. PD JUN PY 1996 VL 56 IS 3 BP 715 EP 735 DI 10.1137/S0036139994277828 PG 21 WC Mathematics, Applied SC Mathematics GA UN667 UT WOS:A1996UN66700003 ER PT J AU Ford, WF AF Ford, WF TI Clarification of ''turn performance of aircraft'' SO SIAM REVIEW LA English DT Article DE aircraft performance; load factor; lift AB A recent note analyzed the minimum turning radius of an airplane in terms of its airspeed and angle of bank. Unfortunately, some misconceptions concerning the underlying physics were introduced. This note is intended to clarify those areas. RP Ford, WF (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 1 TC 2 Z9 2 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER PH#382-9800, PHILADELPHIA, PA 19104-2688 SN 0036-1445 J9 SIAM REV JI SIAM Rev. PD JUN PY 1996 VL 38 IS 2 BP 309 EP 312 DI 10.1137/1038045 PG 4 WC Mathematics, Applied SC Mathematics GA UP962 UT WOS:A1996UP96200007 ER PT J AU ChristensenDalsgaard, J Dappen, W Ajukov, SV Anderson, ER Antia, HM Basu, S Baturin, VA Berthomieu, G Chaboyer, B Chitre, SM Cox, AN Demarque, P Donatowicz, J Dziembowski, WA Gabriel, M Gough, DO Guenther, DB Guzik, JA Harvey, JW Hill, F Houdek, G Iglesias, CA Kosovichev, AG Leibacher, JW Morel, P Proffitt, CR Provost, J Reiter, J Rhodes, EJ Rogers, FJ Roxburgh, IW Thompson, MJ Ulrich, RK AF ChristensenDalsgaard, J Dappen, W Ajukov, SV Anderson, ER Antia, HM Basu, S Baturin, VA Berthomieu, G Chaboyer, B Chitre, SM Cox, AN Demarque, P Donatowicz, J Dziembowski, WA Gabriel, M Gough, DO Guenther, DB Guzik, JA Harvey, JW Hill, F Houdek, G Iglesias, CA Kosovichev, AG Leibacher, JW Morel, P Proffitt, CR Provost, J Reiter, J Rhodes, EJ Rogers, FJ Roxburgh, IW Thompson, MJ Ulrich, RK TI The current state of solar modeling SO SCIENCE LA English DT Review ID ROSSELAND OPACITY TABLES; STELLAR ENVELOPES; CONVECTION ZONE; OSCILLATION FREQUENCIES; PULSATIONAL STABILITY; EVOLUTIONARY MODELS; HELIUM ABUNDANCE; NEUTRINO PROBLEM; EQUATION; SUN AB Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors and for the thermodynamic and radiative properties, on which the models depend, of matter under the extreme conditions found in the sun. Current models are in agreement with the helioseismic inferences, which suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the sun is not caused by errors in the models. However, the GONG data reveal subtle errors in the models, such as an excess In sound speed just beneath the convection zone. These discrepancies indicate effects that have so far not been correctly accounted for; for example, it is plausible that the sound-speed differences reflect weak mixing in stellar interiors, of potential importance to the overall evolution of stars and ultimately to estimates of the age of the galaxy based on stellar evolution calculations. C1 AARHUS UNIV, INST PHYS & ASTRON, DK-8000 AARHUS C, DENMARK. UNIV SO CALIF, DEPT PHYS & ASTRON, LOS ANGELES, CA 90089 USA. MOSCOW MV LOMONOSOV STATE UNIV, STERNBERG ASTRON INST, Moscow, RUSSIA. NATL OPT ASTRON OBSERV, NATL SOLAR OBSERV, TUCSON, AZ 85726 USA. TATA INST FUNDAMENTAL RES, BOMBAY 400005, MAHARASHTRA, INDIA. UNIV LONDON QUEEN MARY & WESTFIELD COLL, ASTRON UNIT, LONDON E1 4NS, ENGLAND. OBSERV COTE AZUR, F-06003 NICE, FRANCE. UNIV TORONTO, CANADIAN INST THEORET ASTROPHYS, TORONTO, ON M5S 1A1, CANADA. LOS ALAMOS NATL LAB, LOS ALAMOS, NM 87545 USA. YALE UNIV, DEPT ASTRON, NEW HAVEN, CT 06520 USA. UNIV VIENNA, INST ASTRON, A-1180 VIENNA, AUSTRIA. COPERNICUS CTR, WARSAW, POLAND. UNIV LIEGE, INST ASTROPHYS, B-4000 LIEGE, BELGIUM. UNIV CAMBRIDGE, INST ASTRON, CAMBRIDGE, ENGLAND. ST MARYS UNIV, DEPT PHYS & ASTRON, HALIFAX, NS B3H 3C3, CANADA. LAWRENCE LIVERMORE NATL LAB, LIVERMORE, CA 94550 USA. STANFORD UNIV, CTR SPACE SCI & ASTROPHYS, STANFORD, CA 94305 USA. NASA, GODDARD SPACE FLIGHT CTR, COMP SCI CORP, GREENBELT, MD 20771 USA. TECH UNIV MUNICH, INST MATH, W-8000 MUNICH, GERMANY. UNIV CALIF LOS ANGELES, DEPT PHYS & ASTRON, LOS ANGELES, CA 90095 USA. RP ChristensenDalsgaard, J (reprint author), AARHUS UNIV, THEORET ASTROPHYS CTR, DK-8000 AARHUS C, DENMARK. RI Basu, Sarbani/B-8015-2014; OI Basu, Sarbani/0000-0002-6163-3472; Chaboyer, Brian/0000-0003-3096-4161 NR 115 TC 709 Z9 712 U1 5 U2 26 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD MAY 31 PY 1996 VL 272 IS 5266 BP 1286 EP 1292 DI 10.1126/science.272.5266.1286 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UN472 UT WOS:A1996UN47200032 ER PT J AU Hill, F Stark, PB Stebbins, RT Anderson, ER Antia, HM Brown, TM Duvall, TL Haber, DA Harvey, JW Hathaway, DH Howe, R Hubbard, RP Jones, HP Kennedy, JR Korzennik, SG Kosovichev, AG Leibacher, JW Libbrecht, KG Pintar, JA Rhodes, EJ Schou, J Thompson, MJ Tomczyk, S Toner, CG Toussaint, R Williams, WE AF Hill, F Stark, PB Stebbins, RT Anderson, ER Antia, HM Brown, TM Duvall, TL Haber, DA Harvey, JW Hathaway, DH Howe, R Hubbard, RP Jones, HP Kennedy, JR Korzennik, SG Kosovichev, AG Leibacher, JW Libbrecht, KG Pintar, JA Rhodes, EJ Schou, J Thompson, MJ Tomczyk, S Toner, CG Toussaint, R Williams, WE TI The solar acoustic spectrum and eigenmode parameters SO SCIENCE LA English DT Article ID FREQUENCIES; OSCILLATIONS; CYCLE AB The Global Oscillation Network Group (GONG) project estimates the frequencies, amplitudes, acid linewidths of more than 250,000 acoustic resonances of the sun from data sets lasting 36 days. The frequency resolution of a single data set is 0.321 microhertz. For frequencies averaged over the azimuthal order m, the median formal error is 0.044 microhertz, and the associated median fractional error is 1.6 x 10(-5). For a 3-year data set, the fractional error is expected to be 3 x 10(-6). The GONG m-averaged frequency measurements differ from other helioseismic data sets by 0.03 to 0.08 microhertz. The differences arise from a combination of systematic errors, random errors, and possible changes in solar structure. C1 UNIV CALIF BERKELEY,DEPT STAT,BERKELEY,CA 94720. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. TATA INST FUNDAMENTAL RES,BOMBAY 400005,MAHARASHTRA,INDIA. NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,BOULDER,CO 80307. STANFORD UNIV,NASA,GODDARD SPACE FLIGHT CTR,CTR ASTROPHYS & SPACE SCI,STANFORD,CA. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV LONDON QUEEN MARY & WESTFIELD COLL,ASTRON UNIT,LONDON E1 4NS,ENGLAND. NATL OPT ASTRON OBSERV,NASA,GODDARD SPACE FLIGHT CTR,TUCSON,AZ 85726. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. CALTECH,PASADENA,CA 91125. UNIV SO CALIF,DEPT PHYS & ASTRON,LOS ANGELES,CA 90089. RP Hill, F (reprint author), NATL OPT ASTRON OBSERV,NATL SOLAR OBSERV,POB 26732,TUCSON,AZ 85726, USA. RI Duvall, Thomas/C-9998-2012; Stebbins, Robin/G-5009-2013; OI Stark, Philip/0000-0002-3771-9604 NR 27 TC 132 Z9 132 U1 0 U2 3 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 31 PY 1996 VL 272 IS 5266 BP 1292 EP 1295 DI 10.1126/science.272.5266.1292 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UN472 UT WOS:A1996UN47200033 ER PT J AU Hathaway, DH Gilman, PA Harvey, JW Hill, F Howard, RF Jones, HP Kasher, JC Leibacher, JW Pintar, JA Simon, GW AF Hathaway, DH Gilman, PA Harvey, JW Hill, F Howard, RF Jones, HP Kasher, JC Leibacher, JW Pintar, JA Simon, GW TI GONG observations of solar surface flows SO SCIENCE LA English DT Article ID SPHERICAL HARMONIC-ANALYSIS; STEADY PHOTOSPHERIC FLOWS; VELOCITY-FIELDS; ROTATION; SUN; FEATURES; CONVECTION; SHELL AB Doppler velocity observations obtained by the Global Oscillation Network Group (GONG) instruments directly measure the nearly steady flows in the solar photosphere. The sun's differential rotation is accurately determined from single observations. The rotation profile with respect to latitude agrees well with previous measures, but it also shows a slight north-south asymmetry. Rotation profiles averaged over 27-day rotations of the sun reveal the torsional oscillation signal-weak, jetlike features, with amplitudes of 5 meters per second, that are associated with the sunspot latitude activity belts. A meridional circulation with a poleward flow of about 20 meters per second is also evident, Several characteristics of the surface flows suggest the presence of large convection cells. C1 NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,BOULDER,CO 80303. UNIV NEBRASKA,DEPT PHYS,OMAHA,NE 68182. NATL SOLAR OBSERV,SOLAR RES BRANCH,GEOPHYS DIRECTORATE,PHILLIPS LAB,USAF,MAT COMMAND,SUNSPOT,NM 88349. NATL OPT ASTRON OBSERV,NATL SOLAR OBSERV,NASA,GODDARD SPACE FLIGHT CTR,SW SOLAR STN,TUCSON,AZ 85726. RP Hathaway, DH (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,SOLAR PHYS BRANCH,MAIL CODE ES82,HUNTSVILLE,AL 35812, USA. NR 37 TC 106 Z9 106 U1 0 U2 3 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 31 PY 1996 VL 272 IS 5266 BP 1306 EP 1309 DI 10.1126/science.272.5266.1306 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UN472 UT WOS:A1996UN47200036 ER PT J AU Mumma, MJ DiSanti, MA DelloRusso, N Fomenkova, M MageeSauer, K Kaminski, CD Xie, DX AF Mumma, MJ DiSanti, MA DelloRusso, N Fomenkova, M MageeSauer, K Kaminski, CD Xie, DX TI Detection of abundant ethane and methane, along with carbon monoxide and water, in comet C/1996 B2 Hyakutake: Evidence for interstellar origin SO SCIENCE LA English DT Article ID MONOCARBOXYLIC ACIDS; HALLEYS-COMET; AUSTIN 1989C1; P-HALLEY; P/HALLEY; FORMALDEHYDE; EMISSION; IDENTIFICATION; EXCITATION; METEORITE AB The saturated hydrocarbons ethane (C2H6) and methane (CH4) along with carbon monoxide (GO) and water (H2O) were detected in comet C/1996 B2 Hyakutake with the use of high-resolution infrared spectroscopy at the NASA Infrared Telescope Facility on Mauna Kea, Hawaii. The inferred production rates of molecular gases from the icy, cometary nucleus (in molecules per second) are 6.4 x 10(26) for C2H6, 1.2 x 10(27) for CH4, 9.8 x 10(27) for CO, and 1.7 x 10(29) for H2O. An abundance of C2H6 comparable to that of CH4 implies that ices in C/1996 B2 Hyakutake did not originate in a thermochemically equilibrated region of the solar nebula. The abundances are consistent with a kinetically controlled production process, but production of C2H6 by gas-phase ion molecule reactions in the natal cloud core is energetically forbidden. The high C2H6/CH4 ratio is consistent with production of C2H6 in icy grain mantles in the natal cloud, either by photolysis of CH4-rich ice or by hydrogen-addition reactions to acetylene condensed from the gas phase. C1 CATHOLIC UNIV AMER,DEPT PHYS,WASHINGTON,DC 20064. NASA,GODDARD SPACE FLIGHT CTR,WASHINGTON,DC 20064. UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. ROWAN COLL,DEPT CHEM & PHYS,GLASSBORO,NJ 08028. NASA,INFRARED TELESCOPE FACIL,HILO,HI 96720. RP Mumma, MJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI mumma, michael/I-2764-2013; Dello Russo, Neil/G-2727-2015; Magee-Sauer, Karen/K-6061-2015 OI Dello Russo, Neil/0000-0002-8379-7304; Magee-Sauer, Karen/0000-0002-4979-9875 NR 64 TC 238 Z9 239 U1 2 U2 20 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 31 PY 1996 VL 272 IS 5266 BP 1310 EP 1314 DI 10.1126/science.272.5266.1310 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UN472 UT WOS:A1996UN47200037 PM 8650540 ER PT J AU Patnaik, SN Coroneos, RM Guptill, JD Hopkins, DA AF Patnaik, SN Coroneos, RM Guptill, JD Hopkins, DA TI Comparative evaluation of different optimization algorithms for structural design applications SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article DE optimization; algorithms; structural; design; comparative; evaluation ID PERFORMANCE AB Non-linear programming algorithms play an important role in structural design optimization. Fortunately, several algorithms with computer codes are available. At NASA Lewis Research Centre, a project was initiated to assess the performance of eight different optimizers through the development of a computer code CometBoards. This paper summarizes the conclusions of that research. CometBoards was employed to solve sets of small, medium and large structural problems, using the eight different optimizers on a Cray-YMP8E/8128 computer. The reliability and efficiency of the optimizers were determined from the performance of these problems. For small problems, the performance of most of the optimizers could be considered adequate. For large problems, however, three optimizers (two sequential quadratic programming routines, DNCONG of IMSL and SQP of IDESIGN, along with Sequential Unconstrained Minimizations Technique SUMT) outperformed others. At optimum, most optimizers captured an identical number of active displacement and frequency constraints but the number of active stress constraints differed among the optimizers. This discrepancy can be attributed to singularity conditions in the optimization and the alleviation of this discrepancy can improve the efficiency of optimizers. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP Patnaik, SN (reprint author), OHIO AEROSP INST,CLEVELAND,OH 44142, USA. NR 43 TC 20 Z9 20 U1 1 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0029-5981 J9 INT J NUMER METH ENG JI Int. J. Numer. Methods Eng. PD MAY 30 PY 1996 VL 39 IS 10 BP 1761 EP 1774 DI 10.1002/(SICI)1097-0207(19960530)39:10<1761::AID-NME925>3.3.CO;2-H PG 16 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA UJ903 UT WOS:A1996UJ90300008 ER PT J AU Grun, E Baguhl, M Hamilton, DP Riemann, R Zook, HA Dermott, S Fechtig, H Gustafson, BA Hanner, MS Horanyi, M Khurana, KK Kissel, J Kivelson, M Lindblad, BA Linkert, D Linkert, G Mann, I McDonnell, JAM Morfill, GE Polanskey, C Schwehm, G Srama, R AF Grun, E Baguhl, M Hamilton, DP Riemann, R Zook, HA Dermott, S Fechtig, H Gustafson, BA Hanner, MS Horanyi, M Khurana, KK Kissel, J Kivelson, M Lindblad, BA Linkert, D Linkert, G Mann, I McDonnell, JAM Morfill, GE Polanskey, C Schwehm, G Srama, R TI Constraints from Galileo observations on the origin of Jovian dust streams SO NATURE LA English DT Article ID JUPITER; EJECTION; GRAINS AB THE Ulysses spacecraft detected streams of sub-micrometre-sized dust particles as it approached Jupiter in 1992(1,2), Although interplanetary space was known to contain dust, the presence of discrete streams was completely unexpected, The directions from which the dust grains struck the spacecraft strongly suggested that the source lay somewhere within the Jupiter system, Three origins were proposed, the comet Shoemaker-Levy 9 (ref, 3), Jupiter's gossamer ring(4), and the volcanoes on Io(5), but there was no definitive evidence for or against any of the options. Here we report the detection by the Galileo spacecraft of even more intense dust streams-including three intense dust storms of month-long duration, with impact rates up to 10 times higher than those observed by Ulysses, Our analysis of the data confirms that the dust streams originate near Jupiter; rye are able to rule out a cometary origin, but cannot yet determine conclusively whether the dust comes from Io or the ring. C1 UNIV MARYLAND,COLLEGE PK,MD 20742. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV FLORIDA,GAINESVILLE,FL 32611. CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309. UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90024. LUND OBSERV,LUND 221,SWEDEN. MAX PLANCK INST AERON,D-37191 KATLENBURG DUHM,GERMANY. UNIV KENT,CANTERBURY CT2 7NR,KENT,ENGLAND. MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. EUROPEAN SPACE TECHNOL CTR,2200 AG NOORDWIJK,NETHERLANDS. RP Grun, E (reprint author), MAX PLANCK INST KERNPHYS,D-69117 HEIDELBERG,GERMANY. RI Gustafson, Bo/B-9526-2011; Kivelson, Margaret/I-9019-2012; OI Kivelson, Margaret/0000-0003-3859-8581; Horanyi, Mihaly/0000-0002-5920-9226 NR 15 TC 40 Z9 40 U1 0 U2 2 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD MAY 30 PY 1996 VL 381 IS 6581 BP 395 EP 398 DI 10.1038/381395a0 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UN479 UT WOS:A1996UN47900042 ER PT J AU Khan, MA Krishnankutty, S Skogman, RA Kuznia, JN Olson, DT George, T AF Khan, MA Krishnankutty, S Skogman, RA Kuznia, JN Olson, DT George, T TI Vertical-cavity stimulated emission from photopumped InGaN/GaN heterojunctions at room temperature - Comment - Reply SO APPLIED PHYSICS LETTERS LA English DT Letter C1 CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. RP Khan, MA (reprint author), APA OPT INC,2950 NE 84TH LANE,BLAINE,MN 55449, USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD MAY 27 PY 1996 VL 68 IS 22 BP 3198 EP 3198 PG 1 WC Physics, Applied SC Physics GA UM643 UT WOS:A1996UM64300047 ER PT J AU Cess, RD Zhang, MH Ingram, WJ Potter, GL Alskseev, V Barker, HW Cohen-Solal, E Colman, RA Dazlich, DA Del Genio, AD Dix, MR Dymnikov, V Esch, M Fowler, LD Fraser, JR Galin, V Gates, WL Hack, JJ Kiehl, JT Le Treut, H Lo, KKW McAvaney, BJ Meleshko, VP Morcrette, JJ Randall, DA Roeckner, E Royer, JF Schlesinger, ME Sporyshev, PV Timbal, B Volodin, EM Taylor, KE Wang, W Wetherald, RT AF Cess, RD Zhang, MH Ingram, WJ Potter, GL Alskseev, V Barker, HW Cohen-Solal, E Colman, RA Dazlich, DA Del Genio, AD Dix, MR Dymnikov, V Esch, M Fowler, LD Fraser, JR Galin, V Gates, WL Hack, JJ Kiehl, JT Le Treut, H Lo, KKW McAvaney, BJ Meleshko, VP Morcrette, JJ Randall, DA Roeckner, E Royer, JF Schlesinger, ME Sporyshev, PV Timbal, B Volodin, EM Taylor, KE Wang, W Wetherald, RT TI Cloud feedback in atmospheric general circulation models: An update SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RADIATION BUDGET EXPERIMENT; CLIMATE FEEDBACK AB Six years ago, we compared the climate sensitivity of 19 atmospheric general circulation models and found a roughly threefold variation among the models; most of this variation was attributed to differences in the models' depictions of cloud feedback. In an update of this comparison, current models showed considerably smaller differences in net cloud feedback, with most producing modest values. There are, however, substantial differences in the feedback components, indicating that the models still have physical disagreements. C1 SUNY STONY BROOK, MARINE SCI RES CTR, INST TERR & PLANETARY ATMOSPHERES, STONY BROOK, NY 11794 USA. RUSSIAN ACAD SCI, DEPT NUMER MATH, MOSCOW 117334, RUSSIA. CANADIAN CLIMATE CTR, DOWNSVIEW, ON M3H 5T4, CANADA. METEOROL DYNAM LAB, F-75231 PARIS 05, FRANCE. BUR METEOROL, RES CTR, MELBOURNE, VIC 3001, AUSTRALIA. COLORADO STATE UNIV, FT COLLINS, CO 80523 USA. NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. CSIRO, DIV ATMOSPHER RES, MORDIALLOC, VIC 3195, AUSTRALIA. MAX PLANCK INST METEOROL, D-20146 HAMBURG, GERMANY. LAWRENCE LIVERMORE NATL LAB, PROGRAM CLIMATE MODEL DIAGNOSIS & INTERCOMPARISON, LIVERMORE, CA 94550 USA. NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. METEOROL OFF, HADLEY CTR CLIMATE PREDICT & RES, BRACKNELL RG12 2SY, BERKS, ENGLAND. METEO FRANCE, CTR NATL RECH METEOROL, F-31057 TOULOUSE, FRANCE. VOEIKOV MAIN GEOPHYS OBSERV, ST PETERSBURG 194018, RUSSIA. EUROPEAN CTR MEDIUM RANGE WEATHER FORECASTS, READING RG2 9AX, BERKS, ENGLAND. UNIV ILLINOIS, DEPT ATMOSPHER SCI, URBANA, IL 61801 USA. PRINCETON UNIV, NOAA, GEOPHYS FLUID DYNAM LAB, PRINCETON, NJ 08540 USA. RI alexeev, vladimir/B-2234-2010; Taylor, Karl/F-7290-2011; Del Genio, Anthony/D-4663-2012; Dix, Martin/A-2334-2012; Meleshko, Valentin/D-2157-2016; Randall, David/E-6113-2011; Sporyshev, Petr/P-7323-2015 OI alexeev, vladimir/0000-0003-3519-2797; Taylor, Karl/0000-0002-6491-2135; Del Genio, Anthony/0000-0001-7450-1359; Dix, Martin/0000-0002-7534-0654; Randall, David/0000-0001-6935-4112; Sporyshev, Petr/0000-0002-4047-8178 NR 8 TC 216 Z9 223 U1 3 U2 24 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 27 PY 1996 VL 101 IS D8 BP 12791 EP 12794 DI 10.1029/96JD00822 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN379 UT WOS:A1996UN37900001 ER PT J AU Burrage, MD Vincent, RA Mayr, HG Skinner, WR Arnold, NF Hays, PB AF Burrage, MD Vincent, RA Mayr, HG Skinner, WR Arnold, NF Hays, PB TI Long-term variability in the equatorial middle atmosphere zonal wind SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PARTIAL REFLECTION RADAR; SEMIANNUAL OSCILLATION; GRAVITY-WAVES; SEASONAL-VARIATION; MEAN WINDS; SATURATION; MESOSPHERE; STRATOPAUSE; DYNAMICS; MODEL AB The high resolution Doppler imager (HRDI) on the Upper Atmosphere Research Satellite (UARS) has provided measurements of the horizontal wind field in the stratosphere, mesosphere, and lower thermosphere since November 1991. This data set, which spans a period of more than 3 years, has facilitated an investigation of the long-term behavior of the background circulation on a nearly global basis. At middle and high latitudes the zonal circulation is characterized by an annual oscillation. At low latitudes (+/-30 degrees) the most prominent long-term variation above the stratopause is the mesosphere semiannual oscillation (MSAO), which maximizes near the equator at an altitude of between 80 and 85 km. Further analysis of the time series reveals an additional strong variation, with an amplitude near 30 ms(-1) and a period of about 2 years. This feature shows the same altitude and latitude structure as the MSAO and exhibits a phase relationship with the stratospheric quasi-biennial oscillation (QBO). Observations from the Christmas Island MF radar (2 degrees N, 130 degrees W) confirm the presence of this mesospheric QBO (MQBO). These observations support recent findings from a modeling study which generates an MQBO via the selective filtering of small-scale gravity waves by the underlying winds they traverse. C1 UNIV SPACE RES ASSOC, SEABROOK, MD 20706 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UNIV ADELAIDE, DEPT PHYS & MATH PHYS, ADELAIDE, SA 5001, AUSTRALIA. RP Burrage, MD (reprint author), UNIV MICHIGAN, SPACE PHYS RES LAB, 2455 HAYWARD ST, ANN ARBOR, MI 48109 USA. NR 35 TC 112 Z9 114 U1 2 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 27 PY 1996 VL 101 IS D8 BP 12847 EP 12854 DI 10.1029/96JD00575 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN379 UT WOS:A1996UN37900007 ER PT J AU Newman, PA Lait, LR Schoeberl, MR Seablom, M Coy, L Rood, R Swinbank, R Proffitt, M Loewenstien, M Podolske, JR Elkins, JW Webster, CR May, RD Fahey, DW Dutton, GS Chan, KR AF Newman, PA Lait, LR Schoeberl, MR Seablom, M Coy, L Rood, R Swinbank, R Proffitt, M Loewenstien, M Podolske, JR Elkins, JW Webster, CR May, RD Fahey, DW Dutton, GS Chan, KR TI Measurements of polar vortex air in the midlatitudes SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERE; MODEL; WAVES; TEMPERATURES; BREAKING AB The Stratospheric Photochemistry, Aerosols, and Dynamics Expedition (SPADE) was conducted in the spring of 1993 from Moffett Field, California (NASA Ames Research Center), utilizing the NASA high-altitude ER-2 aircraft. These northern midlatitude aircraft flights showed laminae containing high ozone concentrations, traceable to the April 1993 polar vortex breakup and corroborated by laminae of other trace gases such as CFCs, CH4, N2O, and CO2. These laminae are clearly traceable as polar vortex breakup fragments using Rossby-Ertel's potential vorticity and isentropic trajectory calculations. Laminae in stratospheric ozone pro-files are commonly observed in the northern hemisphere from fall to spring, and are hypothesized to originate from very low frequency transverse waves, and/or via Rossby wave breaking. On the basis of these results, the ozone laminae observed during SPADE were a result of Rossby wave breaking during the breakdown of the polar vortex. In addition, it is shown that conventional once-per-day meteorological analyses were adequate for representing the transport of this material into the lower stratosphere midlatitudes over the course of the spring vortex breakup. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NOAA, CLIMATE MONITORING & DIAGNOST LAB, BOULDER, CO 80303 USA. NOAA, AERON LAB, BOULDER, CO 80303 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. TASC INC, RESTON, VA 22090 USA. METEOROL OFF, BRACKNELL RG12 2SZ, BERKS, ENGLAND. RP Newman, PA (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 916, GREENBELT, MD 20771 USA. RI Newman, Paul/D-6208-2012; Rood, Richard/C-5611-2008; Fahey, David/G-4499-2013 OI Newman, Paul/0000-0003-1139-2508; Rood, Richard/0000-0002-2310-4262; Fahey, David/0000-0003-1720-0634 NR 65 TC 46 Z9 46 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 27 PY 1996 VL 101 IS D8 BP 12879 EP 12891 DI 10.1029/95JD03387 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN379 UT WOS:A1996UN37900010 ER PT J AU Otto, SR Jackson, TL Hu, FQ AF Otto, SR Jackson, TL Hu, FQ TI On the spatial evolution of centrifugal instabilities within curved incompressible mixing layers SO JOURNAL OF FLUID MECHANICS LA English DT Article ID GROWING BOUNDARY-LAYERS; GORTLER VORTICES; RECEPTIVITY PROBLEM AB It is known that certain configurations which possess curvature are prone to a class of instabilities which their 'flat' counterparts will not support. The main thrust of the study of these centrifugal instabilities has concentrated on curved solid boundaries and their effect on the fluid motion. In this article attention is shifted towards a fluid-fluid interface observed within a curved incompressible mixing layer. Experimental evidence is available to support the conjecture that this situation may be subject to centrifugal instabilities. The evolution of modes with wavelengths comparable with the layer's thickness is considered within moderately curved mixing layers. The high Taylor/Gortler number regime is also discussed which characterizes the ultimate fate of the modes. C1 NASA,LANGLEY RES CTR,ICASE,HAMPTON,VA 23681. OLD DOMINION UNIV,DEPT MATH & STAT,NORFOLK,VA 23529. RP Otto, SR (reprint author), UNIV BIRMINGHAM,SCH MATH & STAT,BIRMINGHAM B15 2TT,W MIDLANDS,ENGLAND. RI Hu, Fang/A-8206-2009 NR 24 TC 8 Z9 8 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD MAY 25 PY 1996 VL 315 BP 85 EP 103 DI 10.1017/S0022112096002340 PG 19 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA UQ488 UT WOS:A1996UQ48800005 ER PT J AU Leboeuf, RL Mehta, RD AF Leboeuf, RL Mehta, RD TI Vortical structure morphology in the initial region of a forced mixing layer: Roll-up and pairing SO JOURNAL OF FLUID MECHANICS LA English DT Article ID PLANE SHEAR-LAYER; 3-DIMENSIONAL EVOLUTION; STREAMWISE VORTICES; INSTABILITY; TRANSITION; CORE AB Detailed three-dimensional phase-averaged measurements of the spanwise and streamwise vorticity formation and evolution in a forced mixing layer have been obtained. A plane two-stream mixing layer with a velocity ratio (U-2/U-1) Of 0.6, a maximum Reynolds number (Re-delta) of about 3150 and laminar initial boundary layers was generated in a mixing layer wind tunnel. Acoustic forcing, consisting of a fundamental roll-up frequency and its subharmonic, was used to phase-lock the initial development and first pairing of the spanwise vortical structures. For the first time, phase-averaged measurements of all three velocity components have been obtained on a three-dimensional grid, yielding the spanwise and streamwise vorticity distributions without invoking Taylor's hypothesis. The phase-averaged results show that the streamwise vorticity first appears in the form of 'ribs' just upstream of the first spanwise vortex roll-up. At the same time, the first spanwise roller becomes kinked, thus also contributing to the streamwise vorticity. As a result, in cross-stream cuts through the spanwise rollers, the streamwise vorticity appears in a 'three-tier' arrangement with opposite-signed vorticity in the centre. In terms of phase-averaged quantities, the maximum streamwise vorticity in the initial ribs is equivalent to about 10-15% of the peak spanwise vorticity and the streamwise rib circulation is equivalent to about 5-10% of the spanwise circulation. Further downstream, the peak streamwise vorticity decreases with increasing distance, while the average circulation remains approximately constant. Downstream of the pairing, the streamwise vorticity levels in the spanwise rollers are reduced. However, the spanwise spacing of the streamwise vortices does not increase within the measurement domain. Phase-averaged Reynolds stress measurements show that relatively high stress levels (periodic and random) were generated in the cores of the spanwise vortices. C1 STANFORD UNIV, DEPT AERONAUT & ASTRONAUT, JIAA, STANFORD, CA 94305 USA. NASA, AMES RES CTR, FLUID MECH LAB, MOFFETT FIELD, CA 94035 USA. RP STANFORD UNIV, CTR TURBULENCE RES, NASA, AMES RES CTR, STANFORD, CA 94305 USA. NR 45 TC 16 Z9 18 U1 0 U2 2 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0022-1120 EI 1469-7645 J9 J FLUID MECH JI J. Fluid Mech. PD MAY 25 PY 1996 VL 315 BP 175 EP 221 DI 10.1017/S002211209600239X PG 47 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA UQ488 UT WOS:A1996UQ48800010 ER PT J AU Barnes, JR Haberle, RM Pollack, JB Lee, H Schaeffer, J AF Barnes, JR Haberle, RM Pollack, JB Lee, H Schaeffer, J TI Mars atmospheric dynamics as simulated by the NASA Ames general circulation model .3. Winter quasi-stationary eddies SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MARTIAN ATMOSPHERE AB A set of simulations with the NASA Ames Mars general circulation model (GCM) has been analyzed to define the basic properties and dynamics of quasi-stationary eddy circulations in the winter hemisphere. These circulations, differing substantially from those in low latitudes and the summer hemisphere, extend from the surface to the model top at similar to 47 km; typically, the largest geopotential and wind perturbations are found at the highest model level. Near the surface the eddies are of largest amplitude in lower latitudes, but above similar to 5-10 km the amplitudes are a maximum in middle and high latitudes. The vertical structure of the eddies is nearly equivalent barotropic; the phase variation in latitude is also relatively small. Zonal wavenumbers 1 and 2 dominate the stationary circulations, with wave 3 being of significance only at low levels (below similar to 10 km). The quasi-stationary eddies differ substantially in northern and southern winters, and undergo considerable changes with increasing dustiness in northern winter. The southern winter eddy circulation is dominated by zonal wavenumber 1, while the northern eddies have a strong wavenumber 2 component at low levels of dust loading; at high dust levels wavenumber 1 becomes dominant. This change may be at least partly the result of the dusty zonal-mean state becoming more responsive to wave 1 forcing. The standing eddies in a GCM simulation for L(s) similar to 0 degrees exhibit considerable similarity in basic structure and amplitude to those revealed by a recent analysis of Viking IRTM data [Banfield et al., 1996], though there are differences in the phases of the eddy patterns. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. STERLING SOFTWARE INC,PALO ALTO,CA 94303. RP Barnes, JR (reprint author), OREGON STATE UNIV,COLL OCEAN & ATMOSPHER SCI,CORVALLIS,OR 97331, USA. NR 27 TC 34 Z9 34 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAY 25 PY 1996 VL 101 IS E5 BP 12753 EP 12776 DI 10.1029/96JE00179 PG 24 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UN098 UT WOS:A1996UN09800004 ER PT J AU Casscells, W Hathorn, B David, M Krabach, T Vaughn, WK McAllister, HA Bearman, G Willerson, JT AF Casscells, W Hathorn, B David, M Krabach, T Vaughn, WK McAllister, HA Bearman, G Willerson, JT TI Thermal detection of cellular infiltrates in living atherosclerotic plaques: Possible implications for plaque rupture and thrombosis SO LANCET LA English DT Article ID CORONARY-ARTERY DISEASE; MYOCARDIAL-INFARCTION AB Background Atherosclerotic lesions are heterogeneous and prognosis cannot easily be predicted, intracoronary ultrasound and angioscopy, angiographic and necropsy studies suggest that the risk of plaque rupture correlates only weakly with the degree of stenosis. Most ruptured plaques are characterised by a large pool of cholesterol or necrotic debris and a thin fibrous cap with a dense infiltration of macrophages. The release of matrix-digesting enzymes by these cells is thought to contribute to plaque rupture. Other thromboses are found on non-ruptured but inflamed plaque surfaces, We postulated that both types of thrombotic events may be predicted by heat released by activated macrophages either on the plaque surface or under a thin cap. Methods To test the hypothesis, we measured the intimal surface temperatures at 20 sites in each of 50 samples of carotid artery taken at endarterectomy from 48 patients. The living samples were probed with a thermistor (24-gauge needle-tip; accuracy 0.1 degrees C; time contrast 0.15 s), The tissues were then fixed and stained. Findings Plaques showed several regions in which the surface temperatures varied reproducibly by 0.2-0.3 degrees C, but 37% of plaques had substantially warmer regions (0.4-2.2 degrees C). Points with substantially different temperatures could not be distinguished from one another by the naked eye; such points could also be very close to one another (<1 mm apart). Temperature correlated positively with cell density (r=0.68, p=0.0001) and inversely with the distance of the cell clusters from the luminal surface (r=-0.38, p=0.0006), Most cells were macrophages, Infrared thermographic images also revealed heterogeneity in temperature among the plaques. Interpretation Living atherosclerotic plaques show thermal heterogeneity, which raises the possibility that an infrared catheter or other techniques that can localise heat or metabolic activity might be able to identify plaques at high risk of rupture or thrombosis. C1 ST LUKES EPISCOPAL HOSP,TEXAS HEART INST,HOUSTON,TX. HERMANN HOSP,HOUSTON,TX. CALTECH,JET PROP LAB,PASADENA,CA. RP Casscells, W (reprint author), UNIV TEXAS,SCH MED,DEPT INTERNAL MED,DIV CARDIOL,6431 FANNIN,POB 20708,HOUSTON,TX 77225, USA. FU NHLBI NIH HHS [91HL07] NR 19 TC 242 Z9 253 U1 0 U2 4 PU LANCET LTD PI LONDON PA 42 BEDFORD SQUARE, LONDON, ENGLAND WC1B 3SL SN 0140-6736 J9 LANCET JI Lancet PD MAY 25 PY 1996 VL 347 IS 9013 BP 1447 EP 1449 DI 10.1016/S0140-6736(96)91684-0 PG 3 WC Medicine, General & Internal SC General & Internal Medicine GA UM485 UT WOS:A1996UM48500011 PM 8676628 ER PT J AU Saravanos, DA Hopkins, DA AF Saravanos, DA Hopkins, DA TI Effects of delaminations on the damped dynamic characteristics of composite laminates: Analysis and experiments SO JOURNAL OF SOUND AND VIBRATION LA English DT Article ID PLATE-THEORY; MICROMECHANICS; VIBRATION; BEAMS AB Analytical and experimental work is presented on the damped free vibration of delaminated laminates and beams. A laminate theory is developed in which the unknown kinematic perturbations induced by a delamination crack are treated as additional degrees of freedom. The generalized stiffness, inertia and damping matrices of the laminate are formulated. An analytical solution is developed for the prediction of natural frequencies, modes and modal damping in composite beams with delamination cracks. Evaluations of the mechanics on various cantilever beams with a central delamination are performed. Experimental results for the modal frequencies and damping of composite beams with a single delamination are also presented and correlations between analytical predictions and measured data are shown. The effects of delamination vary based on crack size, laminate configuration and mode order. The implications of the mechanics in developing delamination detection techniques are also discussed. (C) 1996 Academic Press Limited RP Saravanos, DA (reprint author), NASA,LEWIS RES CTR,STRUCT MECH BRANCH,MS 49-8,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 17 TC 81 Z9 86 U1 1 U2 7 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD MAY 23 PY 1996 VL 192 IS 5 BP 977 EP 993 DI 10.1006/jsvi.1996.0229 PG 17 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA UM321 UT WOS:A1996UM32100005 ER PT J AU Finger, MH Koh, DT Nelson, RW Prince, TA Vaughan, BA Wilson, RB AF Finger, MH Koh, DT Nelson, RW Prince, TA Vaughan, BA Wilson, RB TI Discovery of hard X-ray pulsations from the transient source GRO J1744-28 SO NATURE LA English DT Article ID NEUTRON STARS; RAPID BURSTER; MAGNETOSPHERE; ACCRETION; BINARIES; MODEL AB AN UNUSUAL astronomical source of hard X-ray bursts, GRO J1744 - 28, was discovered recently(1,2). The properties of this source differ markedly from those of other known high-energy burst sources-X-ray bursters, soft gamma-ray repeaters and gamma-ray bursters- suggesting that it may represent a new type of source. The bursts probably arise from unstable accretion of matter onto a compact object(2), such as a neutron star, but the nature of the object and the origin of the burst instability have not been revealed by observations of the bursts themselves. Here we report the detection of coherent X-ray pulsations, with a period of 467 milliseconds, from GRO J1744 - 28; these are the first persistent pulsations seem in a bursting X-ray source. These pulses and their timing indicate that the object is a magnetized neutron star, accreting gas from a low-mass companion star. The pulsation rate has been increasing during the period of our observations, indicating that an accretion disk has been formed and that the transfer of matter from the disk is spinning up the neutron star. The source of the instability that leads to the bursts remains unknown. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. CALTECH,SPACE RADIAT LAB,PASADENA,CA 91125. RP Finger, MH (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,ES-84,HUNTSVILLE,AL 35812, USA. NR 24 TC 67 Z9 67 U1 0 U2 2 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD MAY 23 PY 1996 VL 381 IS 6580 BP 291 EP 293 DI 10.1038/381291a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UM403 UT WOS:A1996UM40300046 ER PT J AU Nakajima, T Tonna, G Rao, RZ Boi, P Kaufman, Y Holben, B AF Nakajima, T Tonna, G Rao, RZ Boi, P Kaufman, Y Holben, B TI Use of sky brightness measurements from ground for remote sensing of particulate polydispersions SO APPLIED OPTICS LA English DT Article ID SIZE DISTRIBUTION; TROPOSPHERIC AEROSOLS; AIRBORNE MEASUREMENTS; OPTICAL-PROPERTIES; REFRACTIVE-INDEX; LIGHT-SCATTERING; PHASE FUNCTIONS; PARTICLES; SOLAR; ATMOSPHERES AB The software code SKYRAD.pack for retrieval of aerosol size distribution and optical thickness from data of direct and diffuse solar radiation is described; measurements are carried out with sky radiometers in the wavelength range 0.369-1.048 mu m. The treatment of the radiative transfer problem concerning the optical quantities is mainly based on the IMS (improved multiple and single scattering) method, which uses the delta-M approximation for the truncation of the aerosol phase function and corrects the solution for the first- and second-order scattering. Both linear and nonlinear inversion methods can be used for retrieving the size distribution. Improved calibration methods for both direct and diffuse radiation, the data-analysis procedure, the results from the proposed code, and several connected problems are discussed. The results can be summarized as follows: (a) the SKYRAD.pack code can retrieve the columnar aerosol features with accuracy and efficiency in several environmental situations, provided the input parameters are correctly given; (b) when data of both direct and diffuse solar radiation are used, the detectable radius interval for aerosol particles is approximately from 0.03 to 10 mu m; (c) besides the retrieval of the aerosol features, the data-analysis procedure also permits the determination of average values for three input parameters (real and imaginary aerosol refractive index, ground albedo) from the optical data; (d) absolute calibrations for the sky radiometer are not needed, and calibrations for direct and diffuse radiation can be carried out with field data; (e) the nonlinear inversion gives satisfactory results in a larger radius interval, without the unrealistic humps that occur with the linear inversion, but the results strongly depend on the first-guess spectrum; (f) aerosol features retrieved from simulated data showed a better agreement with the given data for the linear inversion than for the nonlinear inversion. (C) 1996 Optical Society of America C1 CNR, INST ATMOSPHER PHYS, I-00144 ROME, ITALY. UNIV CAGLIARI, DEPT PHYS, I-09124 CAGLIARI, ITALY. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. CHINESE ACAD SCI, ANHUI INST OPT & FINE MECH, HEFEI 23001, ANHUI, PEOPLES R CHINA. CNR, CAGLIARI RES AREA, I-09125 CAGLIARI, ITALY. RP Nakajima, T (reprint author), UNIV TOKYO, CTR CLIMATE SYST RES, MEGURO KU, 4-6-1 KOMABA, TOKYO 153, JAPAN. RI Nakajima, Teruyuki/H-2370-2013 OI Nakajima, Teruyuki/0000-0002-9042-504X NR 66 TC 308 Z9 335 U1 2 U2 14 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAY 20 PY 1996 VL 35 IS 15 BP 2672 EP 2686 DI 10.1364/AO.35.002672 PG 15 WC Optics SC Optics GA UM265 UT WOS:A1996UM26500027 PM 21085415 ER PT J AU Stompor, R Banday, AJ Gorski, KM AF Stompor, R Banday, AJ Gorski, KM TI Flat dark matter-dominated models with hybrid adiabatic plus isocurvature initial conditions SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology, theory; dark matter; large-scale structure of universe ID UNIVERSE; AXION AB We investigate the consequences of flat dark matter-dominated cosmogonies with hybrid isocurvature and adiabatic initial perturbations, and with a Harrison-Zel'dovich primordial spectrum normalized to the COBE-Differential Microwave Radiometer (DMR) 2 yr measurements. We show that, while the COBE-DMR data alone shows no preference for a specific admixture of these modes, acceptable combinations are strongly constrained by other observational data. Nevertheless, the character of the initial conditions cannot be uniquely resolved on that basis, and, in some cases, a suitable mixture of both modes still may be used in an attempt to avoid some of the observed problems of purely adiabatic models. Specifically, we consider critical density, cold dark matter (CDM) and mixed dark matter (MDM) models, In the latter case, we show that an isocurvature contribution of order similar to 50%-60% (when expressed in terms of the contribution to the present-day quadrupole) allows for a reasonably good fit to existing observational data. Low total density CDM-dominated models with any significant admixture of isocurvature mode are excluded, while CDM models with critical total density and hybrid initial conditions do not provide a significantly better fit to the data than purely adiabatic scalar models, and then only if the possibility of high-amplitude pairwise velocities on a 1 h(-1) Mpc scale is considered. C1 COPERNICUS ASTRON CTR,PL-00716 WARSAW,POLAND. HUGHES STX CORP,LANHAM,MD 20706. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. UNIV WARSAW OBSERV,PL-00478 WARSAW,POLAND. NR 34 TC 36 Z9 36 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1996 VL 463 IS 1 BP 8 EP 14 DI 10.1086/177219 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UL339 UT WOS:A1996UL33900002 ER PT J AU Kelson, DD Illingworth, GD Freedman, WF Graham, JA Hill, R Madore, BF Saha, A Stetson, PB Kennicutt, RC Mould, JR Hughes, SM Ferrarese, L Phelps, R Turner, A Cook, KH Ford, H Hoessel, JG Huchra, J AF Kelson, DD Illingworth, GD Freedman, WF Graham, JA Hill, R Madore, BF Saha, A Stetson, PB Kennicutt, RC Mould, JR Hughes, SM Ferrarese, L Phelps, R Turner, A Cook, KH Ford, H Hoessel, JG Huchra, J TI The Extragalactic Distance Scale Key Project .3. The discovery of cepheids and a new distance to M101 using the Hubble Space Telescope SO ASTROPHYSICAL JOURNAL LA English DT Article DE Cepheids; distance scale; galaxies, distances and redshifts; galaxies, individual (M101) ID FIELD PLANETARY CAMERA; BVRI CCD PHOTOMETRY; NEARBY GALAXIES; MAGELLANIC CLOUDS; CONSTANT; STARS; NGC-2403; STEPS AB We report on the discovery of 29 Cepheid variables in the galaxy M101 using the original Wide Field Camera (WFC) and the new Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope. We observed a field in M101 at 17 independent epochs in V (F555W), five epochs in I (F785LP/F814W), and one epoch in B (F439W), with a time interval baseline of 381 days. We have found Cepheids with periods ranging from 10 to 60 days. The data have been calibrated using WFPC2 observations with zero points derived from omega Cen, Pal 4, and NGC 2419 observations. This calibration has been verified by using the Medium Deep Survey (MDS) WFC photometric zero points, and groundbased secondary standards in V and I. The V calibrations agree to +/-0.06 mag, and the I calibrations agree to +/-0.04 mag. We have constructed V and I period-luminosity (PL) relations and have derived apparent distance moduli based on a distance modulus for the Large Magellanic Cloud (LMC) of 18.50 mag and a reddening of E(B-V) = 0.10 mag to the LMC Cepheids. Period-residual minimization was used to minimize the effects of Malmquist bias on the period-luminosity relation fitting process. Using a Galactic extinction law and the apparent V and I distance moduli, we have found a mean reddening for the M101 sample of E(B-V) = 0.03 mag and a true distance modulus to M101 of 29.34 +/- 0.17 mag, corresponding to a distance of 7.4 +/- 0.6 Mpc. The sources of error have been rigorously tracked through an error budget; systematic and random errors contribute roughly equally to the quoted error. The mean gas-phase metal abundances in the LMC and in the M101 outer field are similar so we expect metallicity effects to be minimal. These Cepheids will be used in conjunction with results from a Key Project search for Cepheids in an inner field, where the metallicity is larger by a factor of 5, to probe the effects of abundance on the Cepheid period-luminosity relation. C1 CARNEGIE INST WASHINGTON OBSERV,PASADENA,CA 91101. CARNEGIE INST WASHINGTON,DEPT TERR MAGNETISM,WASHINGTON,DC 20015. CALTECH,JET PROP LAB,NASA,INFRARED PROC & ANAL CTR,IPAC EXTRAGALACT DATABAS,PASADENA,CA 91125. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. DOMINION ASTROPHYS OBSERV,NATL RES COUNCIL,VICTORIA,BC V8X 4M6,CANADA. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,WESTON,ACT 2611,AUSTRALIA. JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,BALTIMORE,MD 21218. ROYAL GREENWICH OBSERV,CAMBRIDGE CB3 0EZ,ENGLAND. LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. RP Kelson, DD (reprint author), UNIV CALIF SANTA CRUZ,LICK OBSERV,UCO,SANTA CRUZ,CA 95064, USA. NR 66 TC 104 Z9 104 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1996 VL 463 IS 1 BP 26 EP & DI 10.1086/177221 PN 1 PG 41 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UL339 UT WOS:A1996UL33900004 ER PT J AU Ozel, ME Thompson, DJ AF Ozel, ME Thompson, DJ TI On the nature of unidentified 2EG sources at high latitudes SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, active; gamma rays, observations AB A study of the collective properties of the second EGRET catalog of high-energy gamma-ray sources shows several features. The number of sources detected is primarily limited by statistics. The high-latitude sources associated with AGNs are completely consistent with an isotropic, extragalactic distribution. The unidentified high-latitude sources include a Galactic component that represents nearby, low-luminosity gamma-ray sources having no clear identifications. C1 MARMARA RES CTR,DEPT SPACE SCI,GEBZE 41470,KOCAELI,TURKEY. RP Ozel, ME (reprint author), NASA,GODDARD SPACE FLIGHT CTR,LAB HIGH ENERGY ASTROPHYS,GREENBELT,MD 20771, USA. RI Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 12 TC 27 Z9 27 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1996 VL 463 IS 1 BP 105 EP 109 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UL339 UT WOS:A1996UL33900009 ER PT J AU Turner, TJ Netzer, H George, IM AF Turner, TJ Netzer, H George, IM TI Complex absorption in the Seyfert 1 galaxy ESO 055620-3820.2 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, individual, EXO 055620-3820.2; galaxies, Seyfert; X-rays, galaxies ID ACTIVE GALACTIC NUCLEI; X-RAY-PROPERTIES; NGC-4151; CONSTRAINTS; REFLECTION; QUASARS; AGN AB We report the results from an ASCA observation which yields the first contaminated hard X-ray spectrum of the Seyfert 1 galaxy EXO 055620-3820.2 We find the source spectrum to exhibit a complex structure below 2 keV, indicating that the continuum is attenuated either by an ionized absorber fully or partially covering the X-ray source, or a neutral absorber partially covering the source. While the X-ray data alone do not allow us to distinguish between these models, consideration of the optical properties of this highly reddened nucleus suggests that partial covering by neutral material is unlikely, as it implies an unusually large intrinsic optical flux. We find a good fit to the X-ray data, and consistency with the observed optical properties of the source, with either 96% of the source covered by a column of 3.1 x 10(22) cm(-2) Of low-ionization gas or full covering by a column of 3.6 x 10(22) cm(-2) of highly ionized gas. Both models required extinction of the optical continuum by dust in the host galaxy with A(v) similar to 2 mag. We find evidence for a column of neutral material associated with this dust. The partial-covering models leave a residual soft excess below 1 keV, and the possible origin of this soft emission is also discussed. We detect an iron K-shell emission line, which appears to be significantly broad, with an equivalent width (similar to 300 eV) exceeding that predicted from the absorbing material along the line of sight. The line is consistent with emission from neutral iron, and we find a FWHM for the line of 31,000-77,000 km s(-1), similar to several other Seyfert spectra reported recently. C1 TEL AVIV UNIV,RAYMOND & BEVERLY SACKLER FAC EXACT SCI,SCH PHYS & ASTRON,IL-69978 TEL AVIV,ISRAEL. TEL AVIV UNIV,RAYMOND & BEVERLY SACKLER FAC EXACT SCI,WISE OBSERV,IL-69978 TEL AVIV,ISRAEL. RP Turner, TJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 6602,GREENBELT,MD 20771, USA. NR 57 TC 18 Z9 18 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1996 VL 463 IS 1 BP 134 EP 143 DI 10.1086/177229 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UL339 UT WOS:A1996UL33900012 ER PT J AU Leighly, K Kunieda, H Awaki, H Tsuruta, S AF Leighly, K Kunieda, H Awaki, H Tsuruta, S TI X-ray spectral variability in NGC 7469 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, individual (NGC 7469); galaxies, Seyfert; X-rays, galaxies ID ACTIVE GALACTIC NUCLEI; SEYFERT-1 GALAXIES; COLD MATTER; GINGA; ULTRAVIOLET; REFLECTION; ABSORPTION; MCG-6-30-15; SIGNATURES; NGC-7469 AB We present analyses of two Ginga observations and two observations from the ROSAT database of NGC 7469, focusing on the spectral variability observed on timescales of days and longer. During the 3 day 1988 Ginya observation, the hardness ratio (8-21 keV/3.4-5.7 keV) increased significantly as the total flux decreased by 30%. As the spectrum is well fit by the reflection model and since the spectral variability dominates the higher energy band, this could be explained by either a variation in the power-law index or in the effective covering fraction of the reflecting material. This ambiguity is inherent in reflection modeling of Ginga spectra from moderate flux Seyfert 1 galaxies. Assuming that the power-law index did not change, we find that the reflected flux is consistent with being constant, suggesting that much of the reflecting material may be located more than 3 light-days from the continuum source with the molecular torus being a plausible site. This scenario is also supported by the report of a narrow rather than broad iron K alpha line in the ASCA data by Guainazzi et al. NGC 7469 was faint during the 1989 Ginga observation, but variability was observed with doubling timescale of 5 hr, and the spectrum was harder. A reflection component could not be constrained, and the change in the spectrum could be explained by an increase in neutral absorption. The brighter of two ROSAT spectra was significantly softer, and in both spectra there was evidence of spectral complexity, as has been previously reported by Turner, George, & Mushotzky and Brandt et al. The spectrum could be fit by a variety of two-component models, including a warm absorber model, an ionized disk model, and a thermal model with single-component blackbody spectrum, but joint fitting of the 1988 average Ginya spectrum and the nonsimultaneous ROSAT spectra favored thermal models, as other models required an anomalously high reflection ratio. This model is supported by the observation of a soft excess component and the lack of ionized absorption edges in the ASCA spectrum by Guainazzi et al. The long-term spectral variability could be explained by relative variability between the power-law and soft excess component normalizations, perhaps implying that hard X-ray reprocessing in thermal material does not dominate on long timescales. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NAGOYA UNIV, DEPT PHYS, NAGOYA, AICHI 464, JAPAN. KYOTO UNIV, DEPT PHYS, KYOTO 606, JAPAN. MONTANA STATE UNIV, DEPT PHYS, BOZEMAN, MT 59717 USA. NR 45 TC 12 Z9 12 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1996 VL 463 IS 1 BP 158 EP 168 DI 10.1086/177231 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UL339 UT WOS:A1996UL33900014 ER PT J AU Sloan, GC LeVan, PD LittleMarenin, IR AF Sloan, GC LeVan, PD LittleMarenin, IR TI Sources of the 13 micron feature associated with oxygen-rich circumstellar dust SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; infrared, stars; stars, AGB and post-AGB ID M STELLAR SPECTROPHOTOMETRY; LOW-RESOLUTION SPECTRA; SOLAR NEIGHBORHOOD; OPTICAL-PROPERTIES; EMISSION FEATURES; SILICATE GRAINS; MIRA VARIABLES; IRAS; STARS; GRAPHITE AB A search of the database of spectra from the IRAS Low-Resolution Spectrometer has revealed 13 mu m emission features in 187 sources, most of which are associated with stars embedded within oxygen-rich circumstellar dust shells. Our sample is very incomplete, but we estimate that 40%-50% of all sources with oxygen-rich dust on the asymptotic giant branch (AGB) exhibit emission features at 13 mu m. The similarities of the Galactic distribution, mean radial velocities, infrared colors, and other properties of the sample of 13 mu m sources compared to the parent population of variables on the AGB suggest that the carrier of the 13 mu m feature is commonly produced in oxygen-rich dust environments. A strikingly large fraction of SRb variables show 13 mu m features, approximately 75%-90%, which suggests that the formation and/or survival of the carrier of the 13 mu m feature may be enhanced by the unusual pulsational properties of these variables. C1 PHILIPS LABS,VTRP,ALBUQUERQUE,NM 87117. WELLESLEY COLL,WHITIN OBSERV,WELLESLEY,MA 02181. RP Sloan, GC (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 41 TC 57 Z9 58 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1996 VL 463 IS 1 BP 310 EP 319 DI 10.1086/177243 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UL339 UT WOS:A1996UL33900026 ER PT J AU Araya, RA Harding, AK AF Araya, RA Harding, AK TI On the 110 keV feature from A0535+26: Direct evidence for a near-critical magnetic field SO ASTROPHYSICAL JOURNAL LA English DT Article DE line, formation; magnetic fields; radiative transfer; stars, neutron; X-rays, stars ID SCATTERING; SPECTRA AB A recent high-resolution measurement of an absorption line at omega similar or equal to 110 keV in the phase-averaged spectrum of A0535+26 (Grove et al.) and the conspicuous absence of a previously reported harmonic feature at omega similar to 50 keV (Kendziorra et al.) are indicative of cyclotron scattering in a magnetic field of about 10(13) G. However, controversy has risen over whether a lower field scenario may account for the alleged absence or weakness of a lower energy fundamental harmonic feature. This work explores these two alternatives through the generation of theoretical cyclotron spectra. For lower field models, a cylindrical geometry of the line-forming region and the strong angle dependence of the cross section for resonant scattering conspire to fill in a first harmonic at omega similar or equal to 57 keV. Higher field models (B similar or equal to 10.75 TG), however, yield significantly better fits (chi(low)/(2) chi(high)(2) similar to 71), thus strengthening the case for a near-critical field (B-crit similar or equal to 44 TG). Phase-resolved OSSE spectra are not yet available but would greatly help in resolving this issue. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP Araya, RA (reprint author), JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,HOMEWOOD CAMPUS,BALTIMORE,MD 21218, USA. RI Harding, Alice/D-3160-2012 NR 16 TC 19 Z9 19 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1996 VL 463 IS 1 BP L33 EP L36 DI 10.1086/310051 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UL341 UT WOS:A1996UL34100009 ER PT J AU Hurley, K Li, P Vrba, F Luginbuhl, C Hartmann, D Kouveliotou, C Meegan, C Fishman, G Kulkarni, S Frail, D Bowyer, S Lampton, M AF Hurley, K Li, P Vrba, F Luginbuhl, C Hartmann, D Kouveliotou, C Meegan, C Fishman, G Kulkarni, S Frail, D Bowyer, S Lampton, M TI A possible x-ray counterpart to SGR 1900+14 SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma-rays, bursts; stars, neutron; supernova remnants AB The location of the soft gamma repeater SGR 1900+14 was recently reduced to two similar to 5 arcmin(2) alternate error boxes by the network synthesis method. We have used the ROSAT High Resolution Imager to observe the error box that is closest to the supernova remnant G42.8+0.6. A quiescent, steady, point X-ray source was found at alpha(2000) = 19(h)07(m)14(s).15, delta(2000) = 9 degrees 19'19 ''.06, whose unabsorbed flux is 3 x 10-(12) ergs cm(-2) s(-1). Its position is also consistent with a peculiar double infrared source described in a companion paper. We have also examined this region using the VLA,(1) and have obtained upper limits to the extreme ultraviolet flux of this object using the Extreme-Ultraviolet Explorer. C1 USN OBSERV,FLAGSTAFF,AZ 86002. CLEMSON UNIV,DEPT PHYS & ASTRON,CLEMSON,SC 29634. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. CALTECH,DEPT ASTRON,PASADENA,CA 91125. NATL RADIO ASTRON OBSERV,VLA,SOCORRO,NM 87801. UNIV CALIF BERKELEY,CTR EXTREME ULTRAVIOLET ASTROPHYS,BERKELEY,CA 94720. RP Hurley, K (reprint author), UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720, USA. NR 17 TC 28 Z9 28 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1996 VL 463 IS 1 BP L13 EP L16 DI 10.1086/310048 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UL341 UT WOS:A1996UL34100004 ER PT J AU Latter, WB Charnley, SB AF Latter, WB Charnley, SB TI Methanol in the circumstellar envelope of IRC+10 degrees 216 SO ASTROPHYSICAL JOURNAL LA English DT Article DE molecular processes; stars, carbon; stars, circumstellar matter; stars, late-type ID IRC + 10216; CARBON-BEARING MOLECULES; MILLIMETER; FORMALDEHYDE; ABUNDANCES; SPECTRUM; GIANTS; STARS; GHZ AB Millimeter-wave observations of the extremely carbon-rich circumstellar envelope of IRC +10 degrees 216 show several emission lines that we identify with rotational transitions of methanol. We describe our observations and the reasoning that led to this identification. We argue that shock chemistry, ion-molecule reactions, and grain surface reactions might all be potential sources of circumstellar methanol. Each of these pathways either requires or produces H2O in the envelope of IRC +10 degrees 216. C1 UNIV CALIF BERKELEY, DEPT ASTRON, BERKELEY, CA 94720 USA. RP Latter, WB (reprint author), NASA, AMES RES CTR, DIV SPACE SCI, MS 245-3, MOFFETT FIELD, CA 94035 USA. RI Charnley, Steven/C-9538-2012 NR 38 TC 14 Z9 14 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1996 VL 463 IS 1 BP L37 EP L40 DI 10.1086/310046 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UL341 UT WOS:A1996UL34100010 ER PT J AU Shore, SN Starrfield, S Sonneborn, G AF Shore, SN Starrfield, S Sonneborn, G TI The ultraviolet and X-ray view of the demise of nova V1974 Cygni SO ASTROPHYSICAL JOURNAL LA English DT Article DE novae, cataclysmic variables; ultraviolet, stars; X-rays, stars AB We present new data on the variations of the ultraviolet nitrogen lines during the late, optically thin stages of the outburst of V1974 Cygni. These show that, similar to 500 days after discovery, the ejecta reached maximum ionization and then started to recombine, coincident with the X-ray turnoff observed with ROSAT We derive densities for the ejecta at this stage and use these to discuss the development of the ejecta. The decline with time of the UV emission lines, especially He II lambda 1640, shows that the ejecta must have a linear velocity structure. This agrees with models for the ejection by an explosion and models that we have previously published for the line profiles. We then model the variations of the X-rays from this nova. We show that the ROSAT rise can be modeled by assuming a constant-luminosity central source, at approximately the Eddington limit for a massive white dwarf and an effective temperature of similar to 4 x 10(5) K, using only a decreasing X-ray optical depth within the ejecta, as previously noted by Krautter et al. This model can be generalized to explain the absence of X-ray emission during the early outburst stages of any nova. Last, we show that the final decline in the X-rays requires a substantial decrease in both the luminosity and temperature of the central star, in agreement with expectations for thermonuclear burnout on the surface of the white dwarf. C1 ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP Shore, SN (reprint author), INDIANA UNIV,DEPT PHYS & ASTRON,1700 MISHAWAKA AVE,S BEND,IN 46634, USA. NR 13 TC 27 Z9 27 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1996 VL 463 IS 1 BP L21 EP L24 DI 10.1086/310045 PN 2 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UL341 UT WOS:A1996UL34100006 ER PT J AU Barth, CA Farmer, CB Siskind, DE Perich, JP AF Barth, CA Farmer, CB Siskind, DE Perich, JP TI ATMOS observations of nitric oxide in the mesosphere and lower thermosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERE; MIDDLE AB The nitric oxide density in the Earth's atmosphere between 50 and 130 km was measured by the ATMOS (Atmospheric Trace Molecule Spectroscopy) experiment onboard the Spacelab 3 mission on April 30, 1985 and May 1, 1985, Three observations were made at geographic latitudes of 35 degrees N, 34 degrees N, and 29 degrees N which correspond to geomagnetic latitudes of 26 degrees N, 44 degrees N, and 39 degrees N. The ATMOS measurements of nitric oxide in the thermosphere were compared to SME measurements made during the same time period. The two techniques agree within the geophysical variability of thermospheric nitric oxide. The observations show that during a geomagnetic storm there is a strong latitudinal gradient in the nitric oxide density in the lower thermosphere. Comparison of the observations with a one-dimensional time-dependent model shows that at midlatitudes, nitric oxide is transported downward from the thermosphere into the mesosphere as low as 70 km but not downward into the stratosphere. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. USN, RES LAB, EO HULBURT CTR SPACE RES, WASHINGTON, DC 20375 USA. UNIV COLORADO, DEPT ASTROPHYS PLANETARY & ATMOSPHER SCI, BOULDER, CO 80309 USA. RP Barth, CA (reprint author), UNIV COLORADO, ATMOSPHER & SPACE PHYS LAB, CAMPUS BOX 590, BOULDER, CO 80309 USA. NR 20 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 20 PY 1996 VL 101 IS D7 BP 12489 EP 12494 DI 10.1029/96JD00553 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN558 UT WOS:A1996UN55800001 ER PT J AU Dessler, AE Kawa, SR Douglass, AR Considine, DB Kumer, JB Roche, AE Mergenthaler, JL Waters, JW Russell, JM Gille, JC AF Dessler, AE Kawa, SR Douglass, AR Considine, DB Kumer, JB Roche, AE Mergenthaler, JL Waters, JW Russell, JM Gille, JC TI A test of the partitioning between ClO and ClONO2 using simultaneous UARS measurements of ClO, NO2, and ClONO2 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERE; NITROGEN AB The photochemical theory of the partitioning between the chlorine species ClONO2 and ClO in the lower and mid stratosphere is tested for the first time using simultaneous measurements of ClO, NO2, and ClONO2. The theory suggests that over most of the day the production of ClONO2 through the three-body reaction of ClO and NO2 is balanced by the loss of ClONO2 through photolysis. Our analysis tests this theory by Utilizing simultaneous measurements of these species from instruments aboard the Upper Atmosphere Research Satellite (UARS), as well as calculations of the photolysis rate of ClONO2 and laboratory measurements of the rate constant for the reaction between ClO and NO2. Between 32 and 10 hPa (similar to 24 and 32 km), averaged instantaneous production and loss rates of ClONO2 agree within similar to 10%. At 46 hPa (similar to 2 1 km), the agreement between averaged instantaneous production and loss of ClONO2 is poorer than at higher altitudes, but still within uncertainties. This analysis provides no evidence for any problems in our understanding of the partitioning between the chlorine species ClONO2 and ClO over the range of pressures (46 to 10 hPa) and latitudes (60 degrees S to 60 degrees N) considered here. C1 LOCKHEED MARTIN PALO ALTO RES LAB, PALO ALTO, CA 94304 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NATL CTR ATMOSPHER RES, DIV ATMOSPHER CHEM, BOULDER, CO 80307 USA. APPL RES CORP, LANDOVER, MD 20785 USA. RP Dessler, AE (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 916, GREENBELT, MD 20771 USA. RI Douglass, Anne/D-4655-2012; Kawa, Stephan/E-9040-2012; Dessler, Andrew/G-8852-2012 OI Dessler, Andrew/0000-0003-3939-4820 NR 20 TC 19 Z9 19 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 20 PY 1996 VL 101 IS D7 BP 12515 EP 12521 DI 10.1029/96JD00695 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN558 UT WOS:A1996UN55800003 ER PT J AU Jackman, CH Considine, DB Fleming, EL AF Jackman, CH Considine, DB Fleming, EL TI Space shuttle's impact on the stratosphere: An update SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OZONE; MODEL; AEROSOLS AB To assess their impact on the stratosphere, a launch scenario of nine shuttles and three Titans per year is simulated in a two-dimensional photochemistry and transport model that includes heterogeneous reactions on a stratospheric sulfate aerosol (SSA) layer and polar stratospheric clouds (PSCs). These rocket launches are predicted to cause small constituent changes in the stratosphere. Maximum total inorganic chlorine enhancements are computed to be about 12 parts per trillion by volume (similar to 0.4% on a 3 parts per billion by volume background) in the middle to upper stratosphere at northern middle to high latitudes. Maximum ozone decreases associated with these chlorine increases are calculated to be about 0.14% in the middle to upper stratosphere at northern middle to high latitudes. Column ozone decreases are predicted to be a maximum of about 0.05% at northern polar latitudes in the early spring. Model results using (1) gas phase only reactions, (2) gas phase reactions and heterogeneous reactions on the SSA layer, and (3) gas phase reactions and heterogeneous reactions on the SSA layer and PSCs have also been compared with one another. The simulations from these three versions of our model gave annually averaged global total ozone decreases of (1) 0.0056%, (2) 0.010%, and (3) 0.014%. Stratospheric effects from heterogeneous reactions promoted by the alumina emitted from these rockets could be larger than those predicted from the chlorine emissions and need to be investigated further. C1 NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. RP Jackman, CH (reprint author), APPL RES CORP, 8201 CORP DR, LANDOVER, MD 20785 USA. RI Jackman, Charles/D-4699-2012 NR 41 TC 21 Z9 22 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 20 PY 1996 VL 101 IS D7 BP 12523 EP 12529 DI 10.1029/96JD00577 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN558 UT WOS:A1996UN55800004 ER PT J AU Muller, R Crutzen, PJ Grooss, JU Bruhl, C Russell, JM Tuck, AF AF Muller, R Crutzen, PJ Grooss, JU Bruhl, C Russell, JM Tuck, AF TI Chlorine activation and ozone depletion in the Arctic vortex: Observations by the Halogen Occultation Experiment on the Upper Atmosphere Research Satellite SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ANTARCTIC OZONE; POLAR VORTEX; AIRCRAFT MEASUREMENTS; LOWER STRATOSPHERE; WINTER; CHEMISTRY; SPECTROSCOPY; AEROSOL; TRENDS; ICE AB Chlorine-catalyzed ozone destruction is clearly observed during austral spring in the Antarctic lower stratosphere. While high concentrations of ozone-destroying ClO radicals have likewise been measured during winter in the Arctic stratosphere, the chemical ozone depletion there is more difficult to quantify. Here we present observations of the Halogen Occultation Experiment on the Upper Atmosphere Research Satellite in the vortex region of the Arctic lower stratosphere during the winter and spring months of 1991/1992, 1992/1993, 1993/1994, and 1994/1995. All February measurements indicate an almost complete conversion of the otherwise main chlorine reservoir species HCl to chemically more reactive forms. Using CH4 as a chemically conserved tracer, we show that significant chemical ozone loss occurred in the Arctic vortex region during all four winters. The deficit in column ozone was about 60 and 50 Dobson units (DU) in the winters 1991/1992 and 1993/1994, respectively. During the two winters of 1992/1993 and 1994/1995 a severe chemical loss in lower-stratospheric ozone took place, with local reductions of the mixing ratios by over 50% and a loss in the column ozone of the order of 100 DU. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. NOAA, AERON LAB, BOULDER, CO 80303 USA. MAX PLANCK INST CHEM, DEPT ATMOSPHER CHEM, D-55020 MAINZ, GERMANY. RI Tuck, Adrian/F-6024-2011; Crutzen, Paul/F-6044-2012; Muller, Rolf/A-6669-2013; GrooSS, Jens-Uwe/A-7315-2013 OI Tuck, Adrian/0000-0002-2074-0538; Muller, Rolf/0000-0002-5024-9977; GrooSS, Jens-Uwe/0000-0002-9485-866X NR 79 TC 86 Z9 87 U1 0 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 20 PY 1996 VL 101 IS D7 BP 12531 EP 12554 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN558 UT WOS:A1996UN55800005 ER PT J AU Kondo, Y Kawa, SR Lary, D Sugita, T Douglass, AR Lutman, E Koike, M Deshler, T AF Kondo, Y Kawa, SR Lary, D Sugita, T Douglass, AR Lutman, E Koike, M Deshler, T TI Interpretation of nitric oxide profile observed in January 1942 over Kiruna SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RADIATION-FIELD; ODD NITROGEN; STRATOSPHERE; MODEL; AEROSOLS; OZONE; NO; PHOTOCHEMISTRY; TROPOSPHERE; CHEMISTRY AB NO mixing ratios measured from Kiruna (68 degrees N, 20 degrees E), Sweden, on January 22, 1992, revealed values much smaller than those observed at midlatitude near equinox and had a sharper vertical gradient around 25 km. Location of the measurements was close to the terminator and near the edge of the polar vortex, which is highly distorted from concentric flow by strong planetary wave activities. These conditions necessitate accurate calculation, properly taking into account the transport and photochemical processes, in order to quantitatively explain the observed NO profile. A three-dimensional chemistry and transport model (CTM) and a trajectory model (TM) were used to interpret the profile observations within their larger spatial, temporal, and chemical context. The NO profile calculated by the CTM is in good agreement with that observed on January 31, 1992. In addition, model NOy profiles show small variabilities depending on latitudes, and they change little between January 22 and 31. The TM uses the observed NOy values. The NO values calculated by the CTM and TM agree with observations up to 27 km. Between 20 and 27 km the NO values calculated by the trajectory model including only gas phase chemistry are much larger than those including heterogeneous chemistry, indicating that NO mixing ratios were reduced significantly by heterogeneous chemistry on sulfuric acid aerosols. Very little sunlight to generate NOx from HNO3 was available, also causing the very low NO values. The good agreement between the observed and modeled NO profiles indicates that models can reproduce the photochemical and transport processes in the region where NO values have a sharp horizontal gradient. Moreover, CTM and TM model results show that even when the NOy gradients are weak, the model NO depends upon accurate calculation of the transport and insolation for several days. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UNIV WYOMING, DEPT ATMOSPHER SCI, LARAMIE, WY 82071 USA. UNIV CAMBRIDGE, DEPT CHEM, CAMBRIDGE CB2 1EW, ENGLAND. RP Kondo, Y (reprint author), NAGOYA UNIV, SOLAR TERR ENVIRONM LAB, AICHI 442, JAPAN. RI Lary, David/A-6163-2010; Koike, Makoto/F-4366-2011; Kondo, Yutaka/D-1459-2012; Douglass, Anne/D-4655-2012; Kawa, Stephan/E-9040-2012; OI Sugita, Takafumi/0000-0002-0508-7040 NR 40 TC 4 Z9 4 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 20 PY 1996 VL 101 IS D7 BP 12555 EP 12566 DI 10.1029/96JD00578 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN558 UT WOS:A1996UN55800006 ER PT J AU Rind, D Lerner, J AF Rind, D Lerner, J TI Use of on-line tracers as a diagnostic tool in general circulation model development .1. Horizontal and vertical transport in the troposphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERIC LIFETIME EXPERIMENT; SIMULATIONS; CLIMATE; RN-222; CYCLE; OZONE; CO2; HDO; AIR AB The use of passive on-line tracers in a general circulation model (GCM) developmental process is discussed. CFC-11 and Kr-85 are used to evaluate interhemispheric transport. It is shown that new boundary layer and convective parameterizations lead to reductions in the interhemispheric exchange times to values in close agreement with observations of little more than one year. Radon 222 is used to evaluate vertical mixing away from the surface. The new convection scheme produced smaller convective fluxes, which substantially reduce the high-altitude concentrations of Rn-222 equatorward of 30 degrees latitude. While this result is in better agreement with other models, scarcity of observations prevent any conclusion as to which formulation is more accurate. The effect of altered numerical schemes for solution of the momentum and energy equations in the GCM is shown to have little influence on the model's interhemispheric transport or vertical mixing. Finer vertical resolution increases convective mixing of Rn-222 somewhat and allows for larger pollution concentrations of CFC-11 in the boundary layer. Employing on-line passive tracers in the course of model development should allow for improvements in a GCM's horizontal and vertical fluxes and optimization of the model for atmospheric chemistry purposes. C1 SCI SYST & APPLICAT INC, NEW YORK, NY 10025 USA. RP Rind, D (reprint author), NASA, GODDARD SPACE FLIGHT CTR, INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. NR 49 TC 86 Z9 86 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 20 PY 1996 VL 101 IS D7 BP 12667 EP 12683 DI 10.1029/96JD00551 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN558 UT WOS:A1996UN55800015 ER PT J AU Stallcop, JR Partridge, H Levin, E AF Stallcop, JR Partridge, H Levin, E TI H-H-2 collision integrals and transport coefficients SO CHEMICAL PHYSICS LETTERS LA English DT Article ID CROSS-SECTIONS; HYDROGEN-ATOMS; DISPERSION COEFFICIENTS; ENERGY AB The transport cross sections and collision integrals for H-H-2 interactions have been calculated from the results of accurate ab initio structure calculations using sudden scattering approximations. The low-temperature diffusion and viscosity coefficients agree well with the results of a close-coupling scattering calculation. The values calculated from the potential energies deduced from scattering measurements are in agreement with the theoretical results. The viscosity coefficients for H-H and H-2-H-2 have also been calculated; the H-2-H-2 results are very close to the measured data for temperatures in the range 200-400 K. C1 NASA,AMES RES CTR,THERMOSCI INST,MOFFETT FIELD,CA 94035. RP Stallcop, JR (reprint author), NASA,AMES RES CTR,SPACE TECHNOL DIV,COMPUTAT CHEM BRANCH,MS 230-3,MOFFETT FIELD,CA 94035, USA. NR 29 TC 29 Z9 30 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD MAY 17 PY 1996 VL 254 IS 1-2 BP 25 EP 31 DI 10.1016/0009-2614(96)00285-0 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA UM799 UT WOS:A1996UM79900005 ER PT J AU Kaljevic, I Patnaik, SN Hopkins, DA AF Kaljevic, I Patnaik, SN Hopkins, DA TI Development of finite elements for two-dimensional structural analysis using the integrated force method SO COMPUTERS & STRUCTURES LA English DT Article AB The integrated force method has been developed in recent years for the analysis of structural mechanics problems. In the intgrated force method all independent forces are treated as unknown variables, which are calculated by simultaneously imposing equations of equilibrium and compatibility conditions. The development of a finite element library for the analysis of two-dimensional problems using the integrated force method is presented in this paper. Elements of triangular and quadrilateral shapes, capable of modeling arbitrary domain configurations are developed. The element equilibrium and flexibility matrices are derived by discretizing expressions for corresponding potential and complementary energies, respectively. Independent approximations of displacement and stress fields within finite elements are performed. Interpolation of the displacement field is done similarly as in the standard displacement method. The stress field is approximated using full polynomials of correct orders. A procedure for deriving the stress interpolation polynomials that utilizes the definitions of stress components in terms of Airy's stress function is developed. Such derived stress fields identically satisfy equations of equilibrium, and the resulting element matrices are insensitive to the orientation of local coordinate systems. A method to calculate the number of rigid body modes is devised, and it is shown that the present elements do not possess spurious zero energy modes. A number of example problems are solved using the present library and the results are compared with corresponding analytical solutions and those obtained from the standard displacement finite element method. A good agreement of the results, and better performance of the integrated force method, compared to the displacement method, in stress calculations, is observed. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP Kaljevic, I (reprint author), OHIO AEROSP INST,22800 CEDAR POINT RD,CLEVELAND,OH 44142, USA. NR 31 TC 16 Z9 16 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD MAY 17 PY 1996 VL 59 IS 4 BP 691 EP 706 DI 10.1016/0045-7949(95)00294-4 PG 16 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA UC192 UT WOS:A1996UC19200010 ER PT J AU Willis, SL Carroll, WF Yang, TL AF Willis, SL Carroll, WF Yang, TL TI The Space Shuttle liftoff pressure wave SO COMPUTERS & STRUCTURES LA English DT Article AB The pressure wave produced during the launch of the Space Shuttle and its dynamic effects on ground support structures are studied in this paper. The discrete form of the Fourier transform and the fast Fourier transform algorithm are employed to characterize the pressure wave and to generate design and evaluation data. Analysis is performed on pressure recordings collected from eight pressure transducers mounted on the roof and walls of a building approximately 90 m West of Launch Pad 39A at the Kennedy Space Center. A total of 23 pressure pulses were sampled every 0.25 ms for a 10 s duration from six different launches. The analysis produces a pressure-time plot and power spectrum, representing the frequency content of the pressure wave which identifies its ability to excite a structure. Also produced are response spectra for each pressure wave for various amounts of damping. These spectra may be used to predict the dynamic response of a structure located near a launch site. C1 UNIV CENT FLORIDA,COLL ENGN,ORLANDO,FL 32816. NASA,KENNEDY SPACE CTR,FL. RP Willis, SL (reprint author), HNTB CORP,FAIRFIELD,NJ, USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD MAY 17 PY 1996 VL 59 IS 4 BP 783 EP 787 DI 10.1016/0045-7949(95)00282-0 PG 5 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA UC192 UT WOS:A1996UC19200018 ER PT J AU DeMartini, EE Donaldson, TJ AF DeMartini, EE Donaldson, TJ TI Color morph-habitat relations in the arc-eye hawkfish Paracirrhites arcatus (Pisces: Cirrhitidae) SO COPEIA LA English DT Article ID CORAL REEFS; FISHES; COMPETITION; COMMUNITY; SELECTION; HAWAII AB The arc-eye hawkfish Paracirrhites arcatus, like other congeners, has multiple color morphs whose relative abundances vary greatly among geographic locations, To gain insight into the environmental factors that potentially influence the morph distributions of this species, we conducted two series of surveys at different spatial scales. One extensive, broad-scale survey of 165 central, south, and western Pacific sites was conducted over a 9-yr period (1986-1993), Another series of sites, located along an exposure gradient on the leeward coast of the Island of Hawaii, was surveyed intensively during 1990-1994. Both surveys revealed that relative abundances of the species' two most common (white-striped, WS; melanistic, MEL) color morphs were independent of microhabitat, body size, or adult sex. Morph frequencies were, however, generally related to bottom depth. Across Oceania, the WS morph was more common at depths > 10 m over a depth range of 1-27 m. At Hawaii, the WS morph increased in abundance at depths > 8 m over a range of 1-12 m and was relatively common at 1-4 m depths wherever frequently used branching corals (Pocillopora meandrina) were scarce. Patterns of color morph frequencies in P. arcatus may represent trade-offs between intraspecific communication and predation risk that exist at differing coral and fish densities. We also discuss morph distributions more generally relative to patterns observed for other, perhaps analogous polychromatisms in reef fishes. C1 KYUSHU UNIV,DEPT FISHERIES,HIGASHI KU,FUKUOKA 812,JAPAN. RP DeMartini, EE (reprint author), NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 25 TC 17 Z9 18 U1 0 U2 6 PU AMER SOC ICHTHYOLOGISTS HERPETOLOGISTS BUSINESS OFFICE PI CARBONDALE PA SOUTHERN ILLINOIS UNIV, DEPT ZOOLOGY, CARBONDALE, IL 62901-6501 SN 0045-8511 J9 COPEIA JI Copeia PD MAY 16 PY 1996 IS 2 BP 362 EP 371 DI 10.2307/1446852 PG 10 WC Zoology SC Zoology GA UM949 UT WOS:A1996UM94900011 ER PT J AU Bauschlicher, CW AF Bauschlicher, CW TI The structure of Li-7(-) and K-7(-) SO CHEMICAL PHYSICS LA English DT Article ID GAUSSIAN-BASIS SETS; CONFIGURATION-INTERACTION; MOLECULAR CALCULATIONS; ELECTRONIC-STRUCTURE; GEOMETRIC STRUCTURE; ABSORPTION-SPECTRA; CLUSTERS; ATOMS; LI AB The self-consistent-held (SCF) approach and density functional theory, using the B3LYP hybrid functional, yield three low-lying structures for Li-7(-). The relative separations differ for the SCF and B3LYP approaches, however the B3LYP results are in good agreement with the coupled cluster results. For K-7(-), only an octahedron with one face capped is found to be a minimum; this is the second most stable structure for Li-7(-). A comparison of the computed separations between the low-lying states of K-7 and the photoelectron detachment spectra does not allow an unambiguous assignment of the structure of K-7(-). RP Bauschlicher, CW (reprint author), NASA,AMES RES CTR,STC 2303,MOFFETT FIELD,CA 94035, USA. NR 27 TC 6 Z9 6 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-0104 J9 CHEM PHYS JI Chem. Phys. PD MAY 15 PY 1996 VL 206 IS 1-2 BP 35 EP 42 DI 10.1016/0301-0104(96)00019-5 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA UP170 UT WOS:A1996UP17000003 ER PT J AU Ogilvie, KW Parks, GK AF Ogilvie, KW Parks, GK TI First results from Wind spacecraft: An introduction SO GEOPHYSICAL RESEARCH LETTERS LA English DT Editorial Material C1 UNIV WASHINGTON,GEOPHYS PROGRAM,SEATTLE,WA 98195. RP Ogilvie, KW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 3 TC 17 Z9 17 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1179 EP 1181 DI 10.1029/96GL01357 PG 3 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300030 ER PT J AU Steinberg, JT Lazarus, AJ Ogilvie, KW Lepping, R Byrnes, J AF Steinberg, JT Lazarus, AJ Ogilvie, KW Lepping, R Byrnes, J TI Differential flow between solar wind protons and alpha particles: First WIND observations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CORONAL STREAMERS; HELIUM; HYDROGEN; 1-AU AB Alpha particle and proton measurements in the solar wind made using the SWE Faraday cup detectors on the WIND spacecraft are reported. Some overall trends observed confirm past observations: the ratios of alpha particle to proton density N-alpha/N-P, thermal speed W-alpha/W-P, as well as the differential velocity V-alpha-V-P (hereafter V-alpha P) are generally correlated with bulk solar wind flow speed. The detailed WIND measurements enable us to investigate instances when the alpha-proton differences deviate from these overall general trends. Occasionally, difference velocities as large as 80 km/s were seen, with the ratio of \V-alpha P\ to the Alfven speed V-A near unity, characteristics more typical of observations at solar distances less than 1 AU. An example is presented where \V-alpha\-\V-P\ reverses sign while \V-alpha P\ stays nearly constant. Comparison of the vector velocities and the magnetic field suggests that the speed reversal is associated with a localized kink in the magnetic field. Finally we show an instance where \V-alpha P\ exceeds the observed wave speed for Alfvenic fluctuations (V-wave=B-0 Delta V/Delta B) resulting in alpha particle velocity fluctuations that anti-correlate with the wave. Though this phenomenon has been previously reported in high-latitude measurements beyond 1 AU, it is shown here to also occur at 1 AU in the ecliptic. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP Steinberg, JT (reprint author), MIT,CTR SPACE RES,CAMBRIDGE,MA 02139, USA. NR 17 TC 34 Z9 34 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1183 EP 1186 DI 10.1029/96GL00628 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300031 ER PT J AU Lepping, RP Szabo, A Ogilvie, KW Fitzenreiter, RJ Lazarus, AJ Steinberg, JT AF Lepping, RP Szabo, A Ogilvie, KW Fitzenreiter, RJ Lazarus, AJ Steinberg, JT TI Magnetic cloud-bow shock interaction: WIND and IMP-8 observations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETOSPHERE; MAGNETOPAUSE AB An interplanetary magnetic cloud of typical magnetic field flux rope structure and of diameter 0.23 AU was observed in WIND magnetic field and plasma data of February 8, 1995. Starting at about 1 hour later it was also observed at IMP 8, where the bow shock reached at least 39 R(E) from Earth, on the dusk side, for brief periods within the cloud. This expanded bow shock changed from a perpendicular to pulsation type at IMP-8 as a result of the magnetic field smoothly changing direction within the passing cloud, and its surface normal was nearly, and unexpectedly, invariant during the expansion. It is inferred that, within measurement error, the bow shock's shape expanded almost 'isotropicly' and that the magnetosheath became unusually wide. C1 MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. RP Lepping, RP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 696,GREENBELT,MD 20771, USA. NR 19 TC 13 Z9 13 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1195 EP 1198 DI 10.1029/96GL01287 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300034 ER PT J AU Lepping, RP Szabo, A Peredo, M Hoeksema, JT AF Lepping, RP Szabo, A Peredo, M Hoeksema, JT TI Large-scale properties and solar connection of the heliospheric current and plasma sheets: WIND observations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PLANETARY SECTOR BOUNDARIES AB This letter presents the results of interplanetary magnetic field (IMF) analyses performed on WIND magnetometer data covering the first five months of the mission. It discusses the timing of the large scale (1-2 AU) IMF polarity changes at 1 AU and compares it to predictions that are based on a potential field solar source surface model [Hoeksema, 1989], with excellent results. General statistical properties of locally observed heliospheric current sheets, from 212 selectively chosen individual crossings, are estimated from variance analysis of their field transitions. Some of the properties discussed are: current sheet normal direction, relative B-N-component, and the rotation angle of the field in the current sheet-plane. When a related plasma sheet is present it has a complex, and difficult to characterize, magnetic field magnitude-profile. When the plasma sheet's presence is most apparent, the directional discontinuity of the field (the embedded current sheet) appears to be most abrupt, based on preliminary results from about 1/2 of the 212 cases. C1 STANFORD UNIV,STANFORD,CA 94305. HUGHES STX CORP,GREENBELT,MD. RP Lepping, RP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 17 TC 20 Z9 20 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1199 EP 1202 DI 10.1029/96GL00658 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300035 ER PT J AU Slavin, JA Szabo, A Peredo, M Lepping, RP Fitzenreiter, RJ Ogilvie, KW Owen, CJ Steinberg, JT AF Slavin, JA Szabo, A Peredo, M Lepping, RP Fitzenreiter, RJ Ogilvie, KW Owen, CJ Steinberg, JT TI Near-simultaneous bow shock crossings by WIND and IMP 8 on December 1, 1994 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETOPAUSE AB Near-simultaneous dawn-side bow shock crossings by WIND and IMP 8 on December 1, 1994 are analyzed to determine shock location and shape and to examine the changes in shock structure and the foreshock MHD wave properties with increasing downstream distance. The WIND and IMP 8 crossings took place at sun-Earth-spacecraft angles of 64.7 degrees and 115.3 degrees, respectively. The solar wind speed and interplanetary magnetic field magnitude were near their long-term average values. However, the orientation of the IMF was unusual in that it rotated from an angle of similar to 50-60 degrees to the sun-Earth line at the beginning of the interval of shock crossings to less than 20 degrees just after the final crossings. The ratio of the downstream to upstream components of the magnetic field tangential to the shock decreases from 4.1 at WIND to 3.1 at IMP 8 in general agreement with theory. In addition, the overshoot in the shock magnetic ramp observed at WIND is greatly diminished by the downstream distance of IMP 8. In the foreshock, MHD waves with periods of 10-20 s and amplitudes of 3-6 nT were observed at both spacecraft. However, at WIND they have a strong compressional component which is much weaker farther downstream at IMP 8. Unexpectedly, the radial distance of the shock at both spacecraft is only similar to 80-85% of that predicted by recent models. Motivated by this event, we have statistically analyzed a larger data set of bow shock crossings which took place under quasi-field-aligned flow conditions. On this basis it is suggested that magnetosheath thickness may decrease by similar to 10% as the IMF becomes increasingly flow aligned. C1 UNIV LONDON QUEEN MARY & WESTFIELD COLL,ASTRON UNIT,LONDON E1 4NS,ENGLAND. MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. RP Slavin, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Owen, Christopher/C-2999-2008; Slavin, James/H-3170-2012 OI Owen, Christopher/0000-0002-5982-4667; Slavin, James/0000-0002-9206-724X NR 14 TC 17 Z9 17 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1207 EP 1210 DI 10.1029/96GL01351 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300037 ER PT J AU Mazur, JE Mason, GM vonRosenvinge, TT AF Mazur, JE Mason, GM vonRosenvinge, TT TI Fe-rich solar energetic particle events during solar minimum SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ABUNDANCES; HYDROGEN AB During the first 10 months of WIND observations, we have detected several time periods with energetic particle abundances that are characteristic of impulsive flares: enrichments in the He-3 isotope, and in heavy ions compared to the corona. Using the Supra-Thermal through Energetic Particle sensor on WIND, we find that at similar to 100 keV/nucleon there events typically arrive in sequences of multiple events when the spacecraft is magnetically connected to an active region at western solar longitudes, preceding the arrival of a high speed solar wind stream. During recurrent high speed solar wind streams with their associated flux enhancements Fe-rich events are seldom seen: almost all of the events occur on days with solar wind speeds < 450 km/sec. The impulsive events we observe arrive at a rate of similar to 30 events/year at solar minimum for energies greater than or equal to 120 keV/nucleon. This rate is comparable to upper limits placed on the observed rate of higher energy He-3-rich events in the last solar minimum with measurements from ISEE-3. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Mazur, JE (reprint author), UNIV MARYLAND,DEPT PHYS,COLLEGE PK,MD 20742, USA. NR 11 TC 6 Z9 6 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1219 EP 1222 DI 10.1029/96GL00046 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300040 ER PT J AU Skoug, RM Winglee, RM McCarthy, MP Parks, GK Lin, RP Anderson, KA Carlson, C Ergun, R Larson, D McFadden, J Reme, H Bosqued, J dUston, C Sanderson, TR Wenzel, KP Lepping, RP Szabo, A AF Skoug, RM Winglee, RM McCarthy, MP Parks, GK Lin, RP Anderson, KA Carlson, C Ergun, R Larson, D McFadden, J Reme, H Bosqued, J dUston, C Sanderson, TR Wenzel, KP Lepping, RP Szabo, A TI Upstream and magnetosheath energetic ions with energies to approximate to 2 MeV SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID BOW SHOCK; MAGNETOSPHERE AB We present the first observations of approximate to 2 MeV ion bursts detected in the upstream region and file magnetosheath by the three-dimensional (3D) plasma and energetic particles instrument on the WIND spacecraft. This instrument measures the full 3D distribution of particles from a few eV to several MeV, and allows characterization of the upstream ions in both pitch angle and energy. The new feature observed is the presence of bursts of ions at energies extending up to approximate to 2 MeV, both upstream and in the magnetosheath. The observation of MeV ions has strong implications for the ion source and acceleration mechanisms. C1 UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. EUROPEAN SPACE AGCY,ESTEC,DEPT SPACE SCI,2200 AG NOORDWIJK,NETHERLANDS. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. UNIV TOULOUSE 3,CNRS,CTR ETUD SPATIALE RAYONNEMENTS,F-31062 TOULOUSE,FRANCE. UNIV TOULOUSE 3,CTR ETUD SPATIALE RAYONNEMENTS,F-31062 TOULOUSE,FRANCE. RP Skoug, RM (reprint author), UNIV WASHINGTON,GEOPHYS PROGRAM,SEATTLE,WA 98195, USA. NR 10 TC 14 Z9 14 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1223 EP 1226 DI 10.1029/96GL00301 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300041 ER PT J AU Winglee, RM Skoug, RM McCarthy, MP Parks, GK Lin, RP Anderson, KA Carlson, C Ergun, R Larson, D McFadden, J Lepping, RL Szabo, A Reme, H Bosqued, J dUston, C Sanderson, T Wenzel, KP AF Winglee, RM Skoug, RM McCarthy, MP Parks, GK Lin, RP Anderson, KA Carlson, C Ergun, R Larson, D McFadden, J Lepping, RL Szabo, A Reme, H Bosqued, J dUston, C Sanderson, T Wenzel, KP TI Modeling of upstream energetic particle events observed by WIND SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETOSPHERE AB Energetic particle events observed upstream of the bow shock can have two possible sources, shock acceleration of solar wind particles or leakage from the magnetosphere. Three-dimensioned global fluid simulations in conjunction with particle tracking in global fields are used to investigate the sources of the energetic particles. Acceleration of particles from the bow shock can account for many of the lower intensity events but the magnetosphere appears to be an important source during the more energetic particle events where 2 MeV particles are observed. C1 UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. UNIV TOULOUSE 3,CTR ETUD SPATIALE RAYONNEMENTS,F-31029 TOULOUSE,FRANCE. EUROPEAN SPACE AGCY,ESTEC,DEPT SPACE SCI,2200 AG NOORDWIJK,NETHERLANDS. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Winglee, RM (reprint author), UNIV WASHINGTON,GEOPHYS PROGRAM,BOX 351650,SEATTLE,WA 98195, USA. NR 8 TC 13 Z9 13 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1227 EP 1230 DI 10.1029/96GL00373 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300042 ER PT J AU Mason, GM Mazur, JE vonRosenvinge, TT AF Mason, GM Mazur, JE vonRosenvinge, TT TI Energetic heavy ions observed upstream of the Earth's bow shock by the STEP/EPACT instrument on WIND SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PARTICLE EVENTS; SOLAR-WIND; ABUNDANCES; ACCELERATION AB The Supra-Thermal through Energetic Particle (STEP) subsystem of the EPACT experiment on the WIND spacecraft observed numerous short duration heavy ion enhancements during the similar to 9 month period Nov. 1994-Sept. 1995. These enhancements were most frequent and intense when WIND was close to the magnetosphere, but were often observed also during the period when the spacecraft was >100 R(E) upstream. The events occur in association with high speed solar wind streams that are signatures of corotating interaction regions (CIRs). A typical event observed on January 31, 1995 when WIND was 195 R(E) upstream showed strong field aligned anisotropies and rapid time variations. Heavy ion abundances near 45 keV/nucleon (nuc) were He:C:O:Fe = 86 : 1.46 : =1 : 0.12, similar to those observed at higher energies in CIRs, and distinctly different from magnetospheric ring current abundances measured on the AMPTE spacecraft. We suggest that the CIRs provide the seed population for these heavy ion events, that are then further accelerated in association with the Earth's bow shock. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV MARYLAND,INST PHYS SCI & TECHNOL,COLLEGE PK,MD 20742. RP Mason, GM (reprint author), UNIV MARYLAND,DEPT PHYS,COLLEGE PK,MD 20742, USA. NR 21 TC 28 Z9 28 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1231 EP 1234 DI 10.1029/96GL01035 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300043 ER PT J AU Fitzenreiter, RJ Vinas, AF Klimas, AJ Lepping, RP Kaiser, ML Onsager, TG AF Fitzenreiter, RJ Vinas, AF Klimas, AJ Lepping, RP Kaiser, ML Onsager, TG TI Wind observations of the electron foreshock SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EARTHS BOW SHOCK; SOLAR-WIND; VELOCITY DISTRIBUTIONS AB Observations in the electron foreshock by the WIND/SWE investigation are presented. Between November 30 - December 28, 1994, WIND made repeated back and forth crossings of the leading edge of the electron foreshock. We present observations during one five hour interval from this period. Foreshock crossings are readily identified in the SWE data by the onset of an enhanced flux of backstreaming electrons and by a reversal of the electron heat flux. The measured velocity distribution functions indicate that both magnetic reflection from the bow shock and upstream leakage through the shock are responsible for the backstreaming electrons measured upstream. Resolved bumps are frequently observed on reduced velocity distributions and are shown to be associated with an increased electric field intensity measured by the WIND/WAVES experiment. C1 UNIV NEW HAMPSHIRE,DURHAM,NH 03284. RP Fitzenreiter, RJ (reprint author), GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 16 TC 19 Z9 19 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1235 EP 1238 DI 10.1029/96GL00826 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300044 ER PT J AU Whang, YC Zhou, J Lepping, RP Ogilvie, KW AF Whang, YC Zhou, J Lepping, RP Ogilvie, KW TI Interplanetary slow shock observed from wind SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR-WIND; MAGNETOHYDRODYNAMIC SHOCKS; MODE SHOCKS; WAVE AB Observations of interplanetary slow shocks near 1 AU are rare. From the magnetic field data obtained from MFI and the proton and electron data obtained from SWE of the WIND spacecraft, we identify the observation of a reverse slow shock on December 24, 1994. The plasma beta is small in preshock region. A new method is introduced to determine the best-fit solutions for both the normal of the shock surface and the coplanarity plane when the total deviation of the observed magnetic field and velocity vectors from the theory reaches a minimum. The flow conditions on both sides of the slow shock agree well with those predicted by MHD shock theory. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Whang, YC (reprint author), CATHOLIC UNIV AMER,DEPT MECH ENGN,WASHINGTON,DC 20064, USA. NR 25 TC 29 Z9 29 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1239 EP 1242 DI 10.1029/96GL01358 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300045 ER PT J AU Kellogg, PJ Monson, SJ Goetz, K Howard, RL Bougeret, JL Kaiser, ML AF Kellogg, PJ Monson, SJ Goetz, K Howard, RL Bougeret, JL Kaiser, ML TI Early wind observations of bow shock and foreshock waves SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PLASMA; TURBULENCE; UPSTREAM AB Some preliminary results of time-resolved waveforms of Langmuir waves in the foreshock region are presented. There is evidence for both three-wave parametric decay and modulational instability. Also strong incoherent waves in the bow shock are shown. C1 OBSERV PARIS,DESPA,F-92195 MEUDON,FRANCE. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Kellogg, PJ (reprint author), UNIV MINNESOTA,SCH PHYS & ASTRON,116 CHURCH ST SE,MINNEAPOLIS,MN 55455, USA. NR 10 TC 31 Z9 31 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1243 EP 1246 DI 10.1029/96GL01067 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300046 ER PT J AU Reiner, MJ Kaiser, ML Fainberg, J Desch, MD Stone, RG AF Reiner, MJ Kaiser, ML Fainberg, J Desch, MD Stone, RG TI 2f(p) radio emission from the vicinity of the Earth's foreshock: WIND observations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID BOW SHOCK; PLASMA FREQUENCY; SOLAR-WIND; UPSTREAM; RADIATION; WAVES; ELECTRONS; ISEE-3; NOISE AB We analyze 2f(p) radio emission observed during a perigee pass in August 1995 when the WIND spacecraft was between 47 and 72 R(E) from Earth and upstream of the electron foreshock. The WAVES experiment on WIND measures the direction of arrival and complete polarization state of the 2f(p) radiation. We found no evidence for significant linear or circular polarization. For one period when we were able to utilize the direction finding capability to determine the actual 2f(p) source location, using an interplanetary shock as a diagnostic, the radio emitting region was confirmed to lie within the electron foreshock near the contact point. We indicate how such remotely observed 2f(p) emissions can be used to monitor the response of the electron foreshock to instantaneous changes in the interplanetary magnetic field. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP Reiner, MJ (reprint author), HUGHES STX,4400 FORBES BLVD,LANHAM,MD 20706, USA. NR 21 TC 15 Z9 15 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1247 EP 1250 DI 10.1029/96GL00841 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300047 ER PT J AU Desch, MD Kaiser, ML Farrell, WM AF Desch, MD Kaiser, ML Farrell, WM TI Control of terrestrial low frequency bursts by solar wind speed SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID KILOMETRIC RADIATION; RADIO-EMISSION; COMPONENT AB Using WIND spacecraft data from the WAVES, SWE, and MFI experiments for the period from January through July, 1995, we show that the occurrence of the terrestrial low frequency (LF) radio bursts is controlled primarily by the solar wind speed. A possible secondary factor in determining the occurrence of the bursts is the direction of the IMF in the x-y plane, with the 'toward' direction (B-y< 0) favored. The correlation with bulk speed suggests, on a gross scale, a viscous-like coupling mechanism between the solar wind and the magnetosphere. In terms of the nature of the solar wind correlation, terrestrial LF bursts strongly resemble the Earth's AKR and Jovian quasi-periodic bursts. RP Desch, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 695,GREENBELT,MD 20771, USA. RI Farrell, William/I-4865-2013 NR 18 TC 6 Z9 6 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1251 EP 1254 DI 10.1029/96GL01352 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300048 ER PT J AU Ogilvie, KW Steinberg, JT Fitzenreiter, RJ Owen, CJ Lazarus, AJ Farrell, WM Torbert, RB AF Ogilvie, KW Steinberg, JT Fitzenreiter, RJ Owen, CJ Lazarus, AJ Farrell, WM Torbert, RB TI Observations of the lunar plasma wake from the WIND spacecraft on December 27, 1994 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB On December 27, 1994, the WIND spacecraft crossed the lunar wake at a distance of 6.5 lunar radii ( R(L) ) behind the moon. The observations made were the first employing modem instruments and a high data rate. The SWE plasma instrument on WIND observed new aspects of the interaction between the solar wind and unmagnetized dielectric bodies. The plasma density decreased exponentially from the periphery of the wake towards its center as predicted by simple theory. Behind the moon two distinct cold ion beams were observed refilling the lunar cavity. The ions were accelerated along the direction of the magnetic field by an electric field of the order 2x10(-4) volts/m. The region of plasma depletion was observed to extend beyond the light shadow, consistent with a rarefaction wave moving out from the wake into the undisturbed solar wind. C1 MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. UNIV NEW HAMPSHIRE,DEPT PHYS,INST EARTH OCEANS & SPACE,DURHAM,NH 03824. RP Ogilvie, KW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Owen, Christopher/C-2999-2008; Farrell, William/I-4865-2013 OI Owen, Christopher/0000-0002-5982-4667; NR 11 TC 105 Z9 105 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1255 EP 1258 DI 10.1029/96GL01069 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300049 ER PT J AU Owen, CJ Lepping, RP Ogilvie, KW Slavin, JA Farrell, WM Byrnes, JB AF Owen, CJ Lepping, RP Ogilvie, KW Slavin, JA Farrell, WM Byrnes, JB TI The lunar wake at 6.8 R(L): WIND magnetic field observations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB We report on WIND magnetic field observations at similar to 6.8 R(L) downstream of the moon on 27th December 1994. The moon was in the solar wind during the encounter. IMP-8 observations are used to determine baseline IMF conditions, and therefore determine those features in the WIND data which are related to its proximity to the moon. Previous Explorer 35 observations suggest that the lunar wake is not detectable beyond a downstream distance of similar to 4 R(L). However, despite the distance of WIND from the moon, we observe a slight decrease in field intensity just prior to the spacecraft entering the optical shadow, a slight field strength enhancement whilst in shadow, and perhaps a weak depression once the spacecraft reemerges into sunlight. These signatures closely resemble, but are weaker than, the previous observations. We conclude that a lunar wake did extend to these distances at the time of this encounter. We also note a rotation in field direction some distance outside of the wake signature which may be attributed to the crossing of the lunar mach cone boundary. We discuss the observations in terms of simple models of the solar wind interaction with an insulating body. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RI Owen, Christopher/C-2999-2008; Slavin, James/H-3170-2012; Farrell, William/I-4865-2013 OI Owen, Christopher/0000-0002-5982-4667; Slavin, James/0000-0002-9206-724X; NR 20 TC 40 Z9 40 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1263 EP 1266 DI 10.1029/96GL01354 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300051 ER PT J AU Kellogg, PJ Goetz, K Monson, SJ Bougeret, JL Manning, R Kaiser, ML AF Kellogg, PJ Goetz, K Monson, SJ Bougeret, JL Manning, R Kaiser, ML TI Observations of plasma waves during a traversal of the moon's wake SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID FREQUENCY AB The Wind satellite passed through the solar wind wake of the moon at a distance of about 8 lunar radii on 27 Dec. 1994. Several different wave modes were observed, which we describe. Some of these modes are not certainly identifiable with modes of a uniform plasma, and are probably associated with the density discontinuity, and possibly with a velocity shear, at the boundary of the wake. Modes which are identifiable, at least tentatively, include electromagnetic waves at both f(p) and 2 f(p) from outside the wake, and a mode at the local plasma frequency of the wake. C1 OBSERV PARIS,DESPA,F-92195 MEUDON,FRANCE. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Kellogg, PJ (reprint author), UNIV MINNESOTA,SCH PHYS & ASTRON,116 CHURCH ST SE,MINNEAPOLIS,MN 55455, USA. NR 8 TC 25 Z9 25 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1267 EP 1270 DI 10.1029/96GL00376 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300052 ER PT J AU Farrell, WM Fitzenreiter, RJ Owen, CJ Byrnes, JB Lepping, RP Ogilvie, KW Neubauer, F AF Farrell, WM Fitzenreiter, RJ Owen, CJ Byrnes, JB Lepping, RP Ogilvie, KW Neubauer, F TI Upstream ULF waves and energetic electrons associated with the lunar wake: Detection of precursor activity SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID FORESHOCK AB We present observations of precursor ULF wave activity and energetic electron flows detected by the WIND spacecraft just prior to entry of the lunar wake on 17 December 1994. This activity occurs upstream of the wake on field lines directly connected to the wake penumbra region. The activity ceases near the penumbra entrance. The observations of upstream ULF wave activity and solar wind counterstreaming electron flows is similar to observations made upstream of collisionless bow shocks. Analogously, the wake precursor region is characterized by thermalization and information propagation ahead of the wake structure. C1 UNIV COLOGNE,INST GEOPHYS & METEOROL,D-500 COLOGNE 41,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,GREENBELT,MD 20771. RP Farrell, WM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Owen, Christopher/C-2999-2008; Farrell, William/I-4865-2013 OI Owen, Christopher/0000-0002-5982-4667; NR 14 TC 35 Z9 35 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1271 EP 1274 DI 10.1029/96GL01355 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300053 ER PT J AU Crooker, NU Lazarus, AJ Lepping, RP Ogilvie, KW Steinberg, JT Szabo, A Onsager, TG AF Crooker, NU Lazarus, AJ Lepping, RP Ogilvie, KW Steinberg, JT Szabo, A Onsager, TG TI A two-stream, four-sector, recurrence pattern: Implications from WIND for the 22-year geomagnetic activity cycle SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CURRENT SHEET; EVOLUTION AB Continuous solar wind data from WIND reveals a new recurrence pattern which implies that speed variations contribute to the 22-year cycle of geomagnetic activity. Near December 1994 solstice, in keeping with expectation, a four-sector interplanetary magnetic field pattern was accompanied by four streams. As the season advanced toward March equinox, however, the streams in the two sectors with away polarity diminished, leaving a strikingly unusual two-stream, four-sector pattern until late April. Since the magnetic field pointed toward the sun in both streams, the polarity effect of Russell and McPherron [1973] combined with the high-speed flow resulted in a recurrent pattern of sustained geomagnetic activity during these sector passages. The solar wind pattern is consistent with Earth's excursion to southern heliographic latitudes at March equinox enabling WIND to sample high-speed flow from only the southern coronal hole. The WIND data imply that the 22-year variation in geomagnetic activity results not only from longer immersion in toward sectors in March and away sectors in September during even solar cycles, as proposed by Russell and McPherron [1973], but also from higher flow speeds in those sectors. C1 MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. NOAA,SPACE ENVIRONM CTR,BOULDER,CO 80303. RP Crooker, NU (reprint author), BOSTON UNIV,CTR SPACE PHYS,725 COMMONWEALTH AVE,BOSTON,MA 02215, USA. NR 15 TC 19 Z9 20 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1275 EP 1278 DI 10.1029/96GL00031 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300054 ER PT J AU Phan, TD Larson, DE Lin, RP McFadden, JP Anderson, KA Carlson, CW Ergun, RE Ashford, SM McCarthy, MP Parks, GK Reme, H Bosqued, JM DUston, C Wenzel, KP Sanderson, TR Szabo, A AF Phan, TD Larson, DE Lin, RP McFadden, JP Anderson, KA Carlson, CW Ergun, RE Ashford, SM McCarthy, MP Parks, GK Reme, H Bosqued, JM DUston, C Wenzel, KP Sanderson, TR Szabo, A TI The subsolar magnetosheath and magnetopause for high solar wind ram pressure: WIND observations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB On a rapid inward pass through the subsolar magnetosheath (MSH) and magnetopause (MP), the WIND spacecraft initially encountered a moderately-compressed low-magnetic shear MP (at a radial distance of 8.6 R(E)), followed by multiple crossings of a high-shear MP (at 8.2 R(E)). The large shear resulted from a southward turning of the external MSH field. Strong magnetic field pile-up, a plasma depletion layer (PDL), and plasma flow acceleration and rotation to become more perpendicular to the local magnetic field were observed in the MSH on approach to the low-shear MP. At the high-shear MP, magnetic reconnection flows were detected, and there are some indications that plasma depletion effects were weak or absent in the adjacent MSH. We attribute the changes in the MP and MSH properties to the sudden rotation of the MSH field direction. In essence, the structure of the MP regions under the unusually high solar wind ram pressure condition in this case does not seem to be qualitatively different from that observed under more typical (less compressed) conditions. Also similar to previous observations, the mirror mode is marginally unstable in the MSH proper, but is stable in the PDL. In this region, the proton temperature anisotropy is inversely correlated with beta(p parallel to). Finally, the electron distributions are observed to be anisotropic (T-e perpendicular to/T-e parallel to similar to 1.3) throughout the entire MSH. C1 CTR ETUD SPATIALE RAYONNEMENTS,F-31029 TOULOUSE,FRANCE. EUROPEAN SPACE AGCY,ESTEC,DEPT SPACE SCI,2200 AG NOORDWIJK,NETHERLANDS. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. UNIV WASHINGTON,GEOPHYS PROGRAM,SEATTLE,WA 98195. RP Phan, TD (reprint author), UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720, USA. NR 18 TC 39 Z9 39 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1279 EP 1282 DI 10.1029/96GL00845 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300055 ER PT J AU Kaiser, ML Desch, MD Farrell, WM Steinberg, JL Reiner, MJ AF Kaiser, ML Desch, MD Farrell, WM Steinberg, JL Reiner, MJ TI LF band terrestrial radio bursts observed by Wind/WAVES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID COMPONENT; EMISSION AB We report on a constituent of Earth's radio spectrum that shows remarkable similarities to Jovian ''type III'' or quasi-periodic bursts. These terrestrial bursts lie in the radio LF band, down to the in situ plasma frequency and are made of two spectral components. The lower frequency component exhibits relatively rapid negative frequency drifts, similar to type III solar bursts but on a much shorter time scale. It appears to emanate from a large source region and its characteristics are the same as those of isotropic terrestrial kilometric radiation described by other authors. The higher frequency component does not drift much in frequency, only lasts about 1 to 5 minutes and sometimes extends up to 500 kHz. It appears to emanate from a discrete source. This high frequency component was never reported before because it is often hidden by AKR events. It might be produced by a mechanism which differs from AKR. These LF bursts may belong to a more common class of radio bursts representing a previously unappreciated segment of Earth's radio spectrum. C1 OBSERV PARIS,DESPA,F-92195 MEUDON,FRANCE. HUGHES STX CORP,LANHAM,MD. RP Kaiser, ML (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 695,GREENBELT,MD 20771, USA. RI Farrell, William/I-4865-2013 NR 15 TC 16 Z9 16 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1283 EP 1286 DI 10.1029/95GL03664 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300056 ER PT J AU Kaiser, ML Desch, MD Bougeret, JL Manning, R Meetre, CA AF Kaiser, ML Desch, MD Bougeret, JL Manning, R Meetre, CA TI Wind/WAVES observations of man-made radio transmissions SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EMISSIONS; PLANETS; EARTH AB The WAVES radio and plasma wave instrument on the Wind spacecraft, launched on November 1, 1994, has detected copious shortwave radio transmissions from broadcast stations on Earth. WAVES can easily detect signals consisting of only a few kW of transmitted power, suggesting that useful ionospheric propagation research can be accomplished with very modest equipment. We also conclude that the terrestrial radio spectrum is quite ''non natural'' so that any extraterrestrial radio astronomer should easily deduce that Earth is populated with a civilization with technical capabilities. C1 OBSERV PARIS,DESPA,F-92195 MEUDON,FRANCE. HUGHES STX,LANHAM,MD. RP Kaiser, ML (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 695,GREENBELT,MD 20771, USA. NR 13 TC 16 Z9 16 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 1996 VL 23 IS 10 BP 1287 EP 1290 DI 10.1029/95GL03665 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UM113 UT WOS:A1996UM11300057 ER PT J AU Huo, WM Green, S AF Huo, WM Green, S TI Quantum calculations for rotational energy transfer in nitrogen molecule collisions SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID IOS APPROXIMATION; SCATTERING; RATES; LINEWIDTHS; ACCURACY; N-2 AB Rotational energy transfer in collisions of nitrogen molecules has been studied theoretically, using the N-2-N-2 rigid-rotor potential of van der Avoird et al. [J. Chem. Phys. 84, 1629 (1986)]. For benchmarking purposes, converged close coupling (CC) calculations have been carried out to a total energy of about 200 cm(-1). Coupled states (CS) approximation calculations have been carried out to a total energy of 680 cm(-1), and infinite order sudden (IOS) approximation calculations have also. been carried out. The CC and CS cross sections have been obtained both with and without identical molecule exchange symmetry, whereas exchange was neglected in the IOS calculations. The CS results track the CC cross sections rather well: between 113-219 cm(-1) the average deviation is 14%, with accuracy improving at higher energy. Comparison between the CS and IOS cross sections at the high energy end of the CS calculations, 500-680 cm(-1), shows that IOS is sensitive to the amount of inelasticity and the results for large Delta J transitions are subject to larger errors. State-to-state cross sections with even and odd exchange symmetry agree to better than 2% and are well represented as a sum of direct and exchange cross sections for distinguishable molecules, an indication of the applicability of a classical treatment for this system. This result, however, does not apply to partial cross sections for given total J, but arises from a near cancellation of the interference terms between even and odd exchange symmetries on summing over partial waves. In order to compare with experimental data for rotational excitation rates of N-2 in the n=1 excited vibrational level colliding with ground vibrational level (n=0) bath N-2 molecules, it is assumed that exchange scattering between molecules in different vibrational le;els is negligible and direct scattering is independent of n so that distinguishable molecule rigid rotor rates may be used. With these assumptions good agreement is obtained. Although the IOS approximation itself is found to provide only moderately accurate values for rate constants, IOS/ECS scaling methods, especially if based on fundamental rates obtained from coupled channel results, are found to provide generally good accuracy. (C) 1995 American Institute of Physics. C1 NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. RP Huo, WM (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 27 TC 24 Z9 24 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD MAY 15 PY 1996 VL 104 IS 19 BP 7572 EP 7589 DI 10.1063/1.471466 PG 18 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA UK935 UT WOS:A1996UK93500020 ER PT J AU Green, S Hue, WM AF Green, S Hue, WM TI Quantum calculations for line shapes in Raman spectra of molecular nitrogen SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID ROTATIONALLY INELASTIC RATES; ENERGY-TRANSFER RATES; Q-BRANCH COLLAPSE; THEORETICAL-ANALYSIS; HIGH-TEMPERATURES; COLLISION MODELS; N-2; SPECTROSCOPY; LINEWIDTHS; RELAXATION AB Using previously described close coupling (CC) and coupled states (CS) cross sections for N-2-N-2 collisions [J. Chem. Phys. 104, 7572 (1996)], we have calculated CARS linewidths at room temperature and below, Agreement with experimental values at room temperature is quite good but predictions become increasingly too large at lower temperatures, with errors reaching 10%-30% at 113 K. We believe these low temperature discrepancies reflect errors in the intermolecular potential used here. To obtain line widths at higher temperatures we have used the energy corrected sudden (ECS) approximation, taking the fundamental cross sections, sigma(0.0-->J(1), J(2)), from the CC-CS calculations extended to higher collision energies with additional CS and infinite order sudden (IOS) calculations: the ECS scaling distance, I-c was chosen by fitting to the 300 K CC-CS results. In general, we find rather good agreement with experimental values to 1500 K, although it appears that smaller values of I-c are more appropriate for higher temperatures and for higher rotational levels. This variability of I-c is reasonable from physical arguments but somewhat diminishes the predictive utility of this approach. Agreement of these purely ab initio predictions with experimental data is nearly as good as that obtained from the best rate law model whose parameters were fitted to these data. (C) 1996 American Institute of Physics. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP Green, S (reprint author), NASA, GODDARD SPACE FLIGHT CTR, INST SPACE STUDIES, NEW YORK, NY 10025 USA. NR 51 TC 11 Z9 11 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD MAY 15 PY 1996 VL 104 IS 19 BP 7590 EP 7598 DI 10.1063/1.471467 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA UK935 UT WOS:A1996UK93500021 ER PT J AU Wajsowicz, RC AF Wajsowicz, RC TI Flow of a western boundary current through multiple straits: An electrical circuit analogy for the Indonesian throughflow and archipelago SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID DEPTH-INTEGRATED FLOW; OCEAN; PACIFIC; CIRCULATION; EXCHANGE; ISLAND AB An analogy is drawn between the flow through multiple, frictional straits and the current through combinations of resistors acting in series and parallel in an electrical circuit. Kirchoff's laws are replaced by continuity of mass and the generalized island rule [Wajsowicz, 1993a]. Expressions are derived for the equivalent resistance of straits acting in series and in parallel. Hence the total ''current'' can be calculated for a given ''voltage'' supplied by the wind stress curl over the adjacent ocean basin. The model may be used to help understand how to parameterize the effect of the many islands within the Indonesian archipelago in a numerical general circulation model by combining islands/straits into resolvable groups with the same effective resistance. For example, from the expression for parallel straits it can be deduced that if there is at least one gap al each latitude within the archipelago, which is wide and deep enough not to block the throughflow, then the throughflow achieves its predicted wind-driven maximum. The transport is not carried by the largest gap but, instead, is carried by the westernmost gap up io a friction-determined limit, and so on eastward, until a dynamically wide gap is reached. This gap carries the remainder of the transport; gaps to the east carry no transport. Hence the model explains surprising recent observations that the throughflow is as large as the Sverdrup model prediction of O(15 Sv). It also explains observations that the narrow, shallow Lombok and Savu Straits to the west carry significant transport, even though Timer Strait to the east is much wider and deeper, and similarly for Makassar Strait versus Molucca Strait. C1 NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,GREENBELT,MD 20771. NR 18 TC 27 Z9 27 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD MAY 15 PY 1996 VL 101 IS C5 BP 12295 EP 12300 DI 10.1029/95JC02615 PG 6 WC Oceanography SC Oceanography GA UL258 UT WOS:A1996UL25800032 ER PT J AU Spinhirne, JD Hart, WD Hlavka, DL AF Spinhirne, JD Hart, WD Hlavka, DL TI Cirrus infrared parameters and shortwave reflectance relations from observations SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID OCTOBER 1986 FIRE; RADIATIVE PROPERTIES; OPTICAL-PROPERTIES; ICE CRYSTALS; HIGH CLOUDS; LIDAR; RADIOMETER; CLIMATE; SCATTERING; EVOLUTION AB A summary of experimental observations and analysis of cirrus from high-altitude aircraft remote sensing is presented. The vertical distribution of cirrus optical and infrared cross-section parameters and the relative effective emittance and visible reflectance are derived from nadir-viewing lidar and multispectral radiometer data for observations during the 1986 and 1991 FIRE cirrus experiments. Statistics on scattering and absorption cross sections in relation to altitude and temperature are given. The emittance and reflectance results are considered as a function of solar zenith angle. Comparative radiative transfer calculations based on the discrete-ordinate method were carried out for three representative cloud phase function models: a spherical water droplet, an ice column crystal cloud, and a Henyey-Greenstein function. The agreements between observations of the effective emittance and shortwave reflectance and the model calculations were a function of the solar zenith angle. At angles between 54 degrees and 60 degrees a Henyey-Greenstein (HC) function with an asymmetry factor of 0.6-0.7 produced the best comparison. At 66 degrees-72 degrees the ice column model was equally comparable to observations. Comparisons to the water cloud model were poor in all cases. The effects of ice crystal microphysical variations on the observed results were not generally apparent, but one dramatic example of difference was found. In order to explain the variations noted for solar zenith angle, an instrument-the Tilt Scan CCD Camera radiometer-was developed to directly observe the shortwave bidirectiond reflectance function for 1991 measurements. The results indicate a characteristic angular function of the visible reflectance of cirrus that is flatter than predicted by the ice column scattering model, but the overall asymmetry factor is comparable. The good agreement with values from an HG function at some angles is not generally applicable. The characteristics of the observed cirrus angular reflectance pattern correlate well with, and are explained by, the results that were found for the solar zenith angle dependence of the emittance and reflectance. C1 SCI SYST APPL INC,LANHAM,MD. RP Spinhirne, JD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 917,GREENBELT,MD 20771, USA. OI Hlavka, Dennis/0000-0002-2976-7243 NR 33 TC 47 Z9 49 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD MAY 15 PY 1996 VL 53 IS 10 BP 1438 EP 1458 DI 10.1175/1520-0469(1996)053<1438:CIPASR>2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UM251 UT WOS:A1996UM25100005 ER PT J AU Hart, DW Jani, M Barnes, NP AF Hart, DW Jani, M Barnes, NP TI Room-temperature lasing of end-pumped Ho:Lu3Al5O12 SO OPTICS LETTERS LA English DT Article AB Room-temperature lasing at 2.1-mu m has been demonstrated in Ho:Lu3Al5O12 with a slope efficiency of 82% and a threshold energy of 4.4 mJ. A maximum absorbed energy of 17 mJ yielded 10 mJ of laser output energy. To simulate diode-pumping experiments, a tunable Co:MgF2 laser operating at 1.878 mu m was used to achieve lasing on I-5(7) --> I-5(8) transitions. (C) 1996 Optical Society of America C1 SCI & TECHNOL CORP,HAMPTON,VA 23666. RP Hart, DW (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 17 TC 80 Z9 82 U1 0 U2 8 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD MAY 15 PY 1996 VL 21 IS 10 BP 728 EP 730 DI 10.1364/OL.21.000728 PG 3 WC Optics SC Optics GA UJ923 UT WOS:A1996UJ92300012 PM 19876139 ER PT J AU Tinto, M AF Tinto, M TI Spacecraft Doppler tracking as a xylophone detector of gravitational radiation SO PHYSICAL REVIEW D LA English DT Article AB We discuss spacecraft Doppler tracking for detecting gravitational waves in which Doppler data recorded on the ground are linearly combined with Doppler measurements made on board a spacecraft. By using the four-link radio system first proposed by Vessot and Levine, we derive a new method for removing from the combined data the frequency fluctuations due to the Earth troposphere, ionosphere, and mechanical vibrations of the antenna on the ground. This method also reduces the frequency fluctuations of the clock on board the spacecraft by several orders of magnitude at selected Fourier components. The nonzero gravitational wave signal remaining at these frequencies makes this Doppler tracking technique the equivalent of a xylophone detector of gravitational radiation. In the assumption of calibrating the frequency fluctuations induced by the interplanetary plasma, a strain sensitivity equal to 4.7 x 10(-18) at 10(-3) Hz is estimated. Experiments of this kind could be performed (at minimal additional cost) with future interplanetary missions by adding instrumentation to the spacecraft payload and the ground station. RP CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 23 TC 16 Z9 16 U1 0 U2 2 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2470-0010 EI 2470-0029 J9 PHYS REV D JI Phys. Rev. D PD MAY 15 PY 1996 VL 53 IS 10 BP 5354 EP 5364 DI 10.1103/PhysRevD.53.5354 PG 11 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA UM250 UT WOS:A1996UM25000004 ER PT J AU Turner, MS Wang, Y AF Turner, MS Wang, Y TI Fast and accurate algorithm for computing tensor CBR anisotropy SO PHYSICAL REVIEW D LA English DT Article ID INFLATIONARY UNIVERSE; PERTURBATIONS; SCALE; COSMOLOGY; MODELS AB Inflation gives rise to a nearly scale-invariant spectrum of tensor perturbations (gravitational waves); their contribution to the cosmic background radiation (CBR) anisotropy depends upon the present cosmological parameters as well as inflationary parameters. The analysis of a sampling-variance-limited CBR map offers the most promising means of detecting tensor perturbations, but will require evaluation of the predicted multipole spectrum for a very large number of cosmological parameter sets. We present accurate polynomial formulas for computing the predicted variance of the multipole moments in terms of the cosmological parameters Omega(Lambda), Omega(o)h(2), Omega(B)h(2), N-v, and the power-law index n(T) Which are accurate to about 1% for l less than or equal to 50 and to better than 3% for 50 0. In contrast, an axial-field component B-z, however small, destroys the conservation laws of circulation and azimuthal magnetic flux by imposing isorotation and conservation of the axial current along field lines. This radical change leads to a different stability criterion that implies structural instability, i.e., the stability properties of the flow with B-z = 0 are not recovered in the limit B-z --> 0 irrespective of the presence of rotation and/or a toroidal-field component. We discuss the relevance of our results for magnetized accretion flows and for outflows around stars and compact objects in active galactic nuclei. We also provide an application to thin accretion disks in Keplerian rotation. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Christodoulou, DM (reprint author), LOUISIANA STATE UNIV,DEPT PHYS & ASTRON,BATON ROUGE,LA 70803, USA. NR 48 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 1996 VL 462 IS 2 BP 865 EP 873 DI 10.1086/177200 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UH187 UT WOS:A1996UH18700028 ER PT J AU Leckrone, DS Johansson, S Kalus, G Wahlgren, GM Brage, T Proffitt, CR AF Leckrone, DS Johansson, S Kalus, G Wahlgren, GM Brage, T Proffitt, CR TI Abundance and isotopic anomalies of thallium in the atmosphere of the HgMn star chi Lupi SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars, abundances; stars, individual (chi Lupi); stars, peculiar ID B-STAR AB We announce the detection of two fully resolved hyperfine components of the intercombination line of Tl II (Z = 81) at 1908.6 Angstrom in the ultraviolet spectrum of the sharp-lined, nonmagnetic, chemically peculiar star chi Lupi (BB.5pHgMn + A2 Vm). The wavelengths and profiles of these absorption lines strongly suggest that they arise from the heaviest isotope, Tl-205. The echelle observations were obtained with the Hubble Space Telescope Goddard High Resolution Spectrograph (HST/GHRS). Spectrum synthesis fits to the line profiles yield a logarithmic overabundance of thallium, relative to the solar system abundance, of +3.8 dex. We believe this to be the first detection of thallium in a star other than the Sun. It is also the first time hyperfine structure has been resolved in the satellite ultraviolet spectrum of an astrophysical source. The large overabundance and the presence of only the heaviest isotope of the element continue the pattern observed previously in chi Lup for platinum (Z = 78), gold (Z = 79), and mercury (Z = 80). C1 LUND UNIV, DEPT PHYS, S-22362 LUND, SWEDEN. LUND UNIV, LUND OBSERV, S-22362 LUND, SWEDEN. NASA, GODDARD SPACE FLIGHT CTR, COMP SCI CORP, GREENBELT, MD 20771 USA. RP Leckrone, DS (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, CODE 681, GREENBELT, MD 20771 USA. NR 25 TC 22 Z9 22 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 1996 VL 462 IS 2 BP 937 EP 942 DI 10.1086/177206 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UH187 UT WOS:A1996UH18700034 ER PT J AU Johansson, S Kalus, G Brage, T Leckrone, DS Wahlgren, GM AF Johansson, S Kalus, G Brage, T Leckrone, DS Wahlgren, GM TI Hyperfine structure and isotope shift in Tl II with astrophysical applications SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic data; line, identification; stars, individual (chi Lupi); ultraviolet, stars ID OSCILLATOR-STRENGTHS AB Fourier transform (FT) spectra of Tl II with resolved hyperfine structure (hfs) have been analyzed in the region 1790-3400 Angstrom. Measured isotope shifts (IS) for two transitions, including the S-1-P-3 intercombination line to the ground state at 1908.6 Angstrom are reported. Accurate Ritz wavelengths for isotope and hyperfine components of the S-1-P-1 resonance line at 1321.6 Angstrom are given. The accuracy is better than 0.3 m Angstrom for measured wavelengths and better than 0.4 m Angstrom for the Ritz wavelengths. Theoretical multi-configuration Dirac-Fock (MCDF) calculations, including core polarization, show that the LS-allowed 1321.6 Angstrom transition is a factor of 30 stronger than the intercombination line at 1908.6 Angstrom. The application of the new Tl II data to astrophysical spectra obtained with the Hubble Space Telescope is discussed. C1 LUND UNIV,LUND OBSERV,S-22362 LUND,SWEDEN. NASA,GODDARD SPACE FLIGHT CTR,NRC,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,GREENBELT,MD 20771. RP Johansson, S (reprint author), LUND UNIV,DEPT PHYS,SOLVEGATAN 14,S-22362 LUND,SWEDEN. NR 23 TC 20 Z9 20 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 1996 VL 462 IS 2 BP 943 EP 947 DI 10.1086/177207 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UH187 UT WOS:A1996UH18700035 ER PT J AU Scully, ST Casse, M Olive, KA Schramm, DN Truran, J VangioniFlam, E AF Scully, ST Casse, M Olive, KA Schramm, DN Truran, J VangioniFlam, E TI The local abundance of He-3: A confrontation between theory and observation SO ASTROPHYSICAL JOURNAL LA English DT Article DE Galaxy, abundances; Galaxy, evolution; nuclear reactions, nucleosynthesis, abundances; Sun, abundances ID BIMODAL STAR FORMATION; INTER-STELLAR MEDIUM; CHEMICAL EVOLUTION; INTERSTELLAR-MEDIUM; GALACTIC DISK; NUCLEOSYNTHESIS; MODELS; DEUTERIUM; GALAXIES; METEORITES AB Determinations of the He-3 concentrations in Galactic matter serve to impose interesting and important constraints both on cosmological models and on models of Galactic chemical evolution. At present, observations of He-3 in the solar system and in the interstellar medium today suggest that the He-3 abundance has not increased significantly over the history of the Galaxy, while theoretical models of Galactic chemical evolution (utilizing current nucleosynthesis yields from stellar evolution and supernova models) predict a rather substantial increase in He-3. We consider the possibility that the solar( )3He abundance may have been affected by stellar processing in the solar neighborhood prior to the formation of the solar system. Such a discrepancy between solar abundances and average Galactic abundances by as much as a factor of 2 may be evidenced by several isotopic anomalies. Local destruction of He-3 by a similar amount could serve to help reconcile the expected increase in the He-3 abundance predicted by models of Galactic chemical evolution. We find, however, that the production of heavier elements, such as oxygen, places a strong constraint on the degree of He-3 destruction. We also explore the implications of both alternative models of Galactic chemical evolution and the stellar yields for He-3 in low-mass stars, which can explain the history of the He-3 concentration in the Galaxy. C1 CEA, DAPNIA, DSM, SERV ASTROPHYS, GIF SUR YVETTE, FRANCE. UNIV CHICAGO, ENRICO FERMI INST, DEPT ASTRON & ASTROPHYS, CHICAGO, IL 60637 USA. FERMILAB NATL ACCELERATOR LAB, NASA, FERMILAB ASTROPHYS CTR, BATAVIA, IL 60510 USA. INST ASTROPHYS, F-75014 PARIS, FRANCE. RP Scully, ST (reprint author), UNIV MINNESOTA, SCH PHYS & ASTRON, MINNEAPOLIS, MN 55455 USA. NR 88 TC 35 Z9 35 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 1996 VL 462 IS 2 BP 960 EP 968 DI 10.1086/177209 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UH187 UT WOS:A1996UH18700037 ER PT J AU Arnaud, K Borkowski, KJ Harrington, JP AF Arnaud, K Borkowski, KJ Harrington, JP TI X-ray emission from the wind-blown bubble in the planetary nebula BD+30 degrees 3639 SO ASTROPHYSICAL JOURNAL LA English DT Article DE planetary nebulae, individual (BD+30 degrees 3639) ID DISTANCES AB An X-ray spectrum of a wind-blown bubble in the planetary nebula ED +30 degrees 3639, acquired by the Advanced Satellite for Cosmology and Astrophysics (ASCA), shows the presence of hot (T = 3 x 10(6) K) gas dominated by the Ne K alpha line complex. There is circumstantial evidence for the enhanced abundances of other H- and He-burning products, although O is not as abundant as in the extremely C-rich stellar wind of the W-R central star. The temperature of the hot gas is several times lower than expected behind the shock from the 700 km s(-1) stellar wind. This might be caused by variations in the stellar wind speed and its chemical abundances induced by the central star evolution, and possibly aided by mixing of the stellar wind gas with the nebular material. Mixing is hinted by the discovery of small (0''.2) dusty clumps in the Hubble Space Telescope (HST) narrowband images of the nebula in [S III] lambda 9532 and [O II] lambda 3727 emission lines. These are projected against an axisymmetric, nearly square nebular shell and are most likely associated with the neutral and molecular envelope surrounding the wind-blown bubble and the wind-swept shell. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. N CAROLINA STATE UNIV,DEPT PHYS,RALEIGH,NC 27695. UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. NR 28 TC 41 Z9 41 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 1996 VL 462 IS 2 BP L75 EP & PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UH189 UT WOS:A1996UH18900007 ER PT J AU Crary, DJ Kouveliotou, C vanParadijs, J vanderHooft, F Scott, DM Paciesas, WS vanderKlis, M Finger, MH Harmon, BA Lewin, WHG AF Crary, DJ Kouveliotou, C vanParadijs, J vanderHooft, F Scott, DM Paciesas, WS vanderKlis, M Finger, MH Harmon, BA Lewin, WHG TI Correlation between BATSE hard X-ray spectral and timing properties of Cygnus X-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars, individual (Cygnus X-1); X-rays, stars ID STATE AB We have analyzed approximately 1100 days of Cygnus X-1 hard X-ray data obtained with BATSE to study its rapid variability. We find for the first time correlations between the slope of the spectrum and the hard X-ray intensity, and between the spectral slope and the amplitude of the rapid variations of the hard X-ray flux. We compare our results with expectations from current theories of accretion onto black holes. C1 UNIV SPACE RES ASSOC, HUNTSVILLE, AL 35806 USA. UNIV ALABAMA, DEPT PHYS, HUNTSVILLE, AL 35899 USA. UNIV AMSTERDAM, ASTRON INST ANTON PANNEKOEK, 1098 SJ AMSTERDAM, NETHERLANDS. NATL INST NUCL & HIGH ENERGY PHYS, CTR HIGH ENERGY ASTROPHYS, 1098 SJ AMSTERDAM, NETHERLANDS. MIT, CAMBRIDGE, MA 02139 USA. RP Crary, DJ (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, CODE ES-84, HUNTSVILLE, AL 35812 USA. NR 28 TC 27 Z9 28 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 1996 VL 462 IS 2 BP L71 EP L74 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UH189 UT WOS:A1996UH18900006 ER PT J AU Zhu, YZ Shum, CK Cheng, MK Tapley, BD Chao, BF AF Zhu, YZ Shum, CK Cheng, MK Tapley, BD Chao, BF TI Long-period variations in gravity field caused by mantle anelasticity SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID GRAVITATIONAL-FIELD; EARTH TIDES; TEMPORAL VARIATIONS; ROTATION; LAGEOS; HARMONICS AB A numerical perturbation approach is used to assess the effect of mantle anelasticity on the Earth's zonal response coefficient kappa, the zonal geopotential coefficient J(2), and the orbital node of geodetic satellites. The theoretical predictions are used to compare solutions of elastic ocean tide models and tides observed by geodetic satellites for M(f), M(m), S-sa, and S-a. The discrepancies between the satellite observed tides and the solution from Schwiderski and recent altimetric ocean tide models can be partly explained by the predicted effect of mantle anelasticity at M(f) and M(m) frequencies. Approximately 80% of the observed semiannual variation in delta J(2) by geodetic satellites can be attributed to the tidal deformation from anelasticity and from the classical equilibrium ocean. The predicted kappa for the 18.6-year tide was computed for an Earth with an anelastic mantle and a nonequilibrium ocean. The range of the lower and upper bounds of kappa for the 18.6-year tide is from 0.345 to 0.377 in amplitude, and from -6 degrees to 3 degrees in phase, with preferred amplitude of 0.365 and phase of -0 degrees 8. C1 UNIV TEXAS, CTR SPACE RES, AUSTIN, TX 78712 USA. NASA, GODDARD SPACE FLIGHT CTR R1000, GREENBELT, MD 20771 USA. RI Chao, Benjamin Fong/N-6156-2013 NR 33 TC 8 Z9 9 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD MAY 10 PY 1996 VL 101 IS B5 BP 11243 EP 11248 DI 10.1029/96JB00111 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UL090 UT WOS:A1996UL09000007 ER PT J AU Lundgren, PR Russo, RM AF Lundgren, PR Russo, RM TI Finite element modeling of crustal deformation in the North America Caribbean plate boundary zone SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID RESTRAINING-BEND; VIRGIN-ISLANDS; CAYMAN TROUGH; TECTONICS; SEISMICITY; MOTION; HISPANIOLA; EARTHQUAKE; SEA; TRANSTENSION AB We have developed two-dimensional spherical shell finite element models of elastic displacements in the North America-Caribbean (NA-Ca) plate boundary zone (PBZ) in order to quantify crust and fault motions in the PBZ. The models we derive are dependent on both the internal fault constraints and the NA-Ca Euler pole we used. Since the location and magnitude of the NA-Ca euler pole are still matters of much debate, we consider three Euler poles [DeMets et al., 1990; Calais and Mercier de Lepinay, 1993; and Deng and Sykes, 1995]. We compare the resulting finite element model displacements to recent seismicity and to geological and geophysical field observations. The model of DeMets et al. [1990], NUVEL-1, features an NA-Ca relative velocity across the PBZ which is less than the observed Cayman spreading axis rate, and thus, the finite element model based on it produces fault motions which are inconsistent with observation. The Calais and Mercier de Lepinay [1993] (C&M), and Deng and Sykes [1995] (D&S) models both yield far-field rates across the PBZ at the point of the Cayman spreading center of approximately 20 mm/yr, a value greater than the observed rate. The greatest differences in the latter two models lie in the motion calculated for the area around Puerto Rico. Both models feature a counterclockwise rotation of the PBZ around Puerto Rico with opening of the Anegada Passage and compression at the Muertos Trough south of eastern Hispaniola. The C&M-based model produces normal opening of the Anegada Passage fault system, while the D&S-based model produces left-lateral transtension across the Anegada Passage fault system, the result of continuum crustal motions which are nearly orthogonal between the two models in the area NE of Puerto Rico. We conclude that the C&M-based model better matches geological observations of PBZ fault motions and deformation primarily on the basis of the Anegada Passage results. Because of this rotation of the PBZ from Hispaniola to the Anegada Passage fault system, the Puerto Rico Trench includes highly oblique compression in its eastern portion, changing to pure left-lateral strike-slip NW of Puerto Rico. The C&M-based finite element model agrees with preliminary GPS results from Hispaniola and Puerto Rico if the central Septentrional fault is constrained to strike-slip motion. C1 CALTECH, JET PROP LAB, PASADENA, CA USA. CARNEGIE INST WASHINGTON, DEPT TERR MAGNETISM, WASHINGTON, DC 20015 USA. NR 43 TC 8 Z9 8 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD MAY 10 PY 1996 VL 101 IS B5 BP 11317 EP 11327 DI 10.1029/95JB03747 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UL090 UT WOS:A1996UL09000013 ER PT J AU Young, RE Smith, MA Sobeck, CK AF Young, RE Smith, MA Sobeck, CK TI Galileo probe: In situ observations of Jupiter's atmosphere SO SCIENCE LA English DT Article ID VOYAGER-2; WINDS; BELT AB The Galileo probe performed the first in situ measurements of the atmosphere of Jupiter on 7 December 1995, The probe returned data until it reached a depth corresponding to an atmospheric pressure of similar to 24 bars. This report presents a brief overview of the origins and purpose of the mission. Science objectives, entry parameters and mission events, and results are described. The remaining reports address in more detail the individual experiments summarized here. RP Young, RE (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 25 TC 38 Z9 38 U1 1 U2 5 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 10 PY 1996 VL 272 IS 5263 BP 837 EP 838 DI 10.1126/science.272.5263.837 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UK757 UT WOS:A1996UK75700044 PM 8629015 ER PT J AU Orton, G Ortiz, JL Baines, K Bjoraker, G Carsenty, U Colas, F Dayal, A Deming, D Drossart, P Frappa, E Friedson, J Goguen, J Golisch, W Griep, D Hernandez, C Hoffmann, W Jennings, D Kaminski, C Kuhn, J Laques, P Limaye, S Lin, H Lecacheux, J Martin, T McCabe, G Momary, T Parker, D Puetter, R Ressler, M Reyes, G Sada, P Spencer, J Spitale, J Stewart, S Varsik, J Warell, J Wild, W YanamandraFisher, P Fazio, G Hora, J Deutsch, L AF Orton, G Ortiz, JL Baines, K Bjoraker, G Carsenty, U Colas, F Dayal, A Deming, D Drossart, P Frappa, E Friedson, J Goguen, J Golisch, W Griep, D Hernandez, C Hoffmann, W Jennings, D Kaminski, C Kuhn, J Laques, P Limaye, S Lin, H Lecacheux, J Martin, T McCabe, G Momary, T Parker, D Puetter, R Ressler, M Reyes, G Sada, P Spencer, J Spitale, J Stewart, S Varsik, J Warell, J Wild, W YanamandraFisher, P Fazio, G Hora, J Deutsch, L TI Earth-based observations of the Galileo probe entry site SO SCIENCE LA English DT Article ID JUPITER; ATMOSPHERE AB Earth-based observations of Jupiter indicate that the Galileo probe probably entered Jupiter's atmosphere just inside a region that has less cloud cover and drier conditions than more than 99 percent of the rest of the planet. The visual appearance of the clouds at the site was generally dark at longer wavelengths. The tropospheric and stratospheric temperature fields have a strong longitudinal wave structure that is expected to manifest itself in the vertical temperature profile. C1 INST ASTROFIS ANDALUCIA,CSIC,E-18080 GRANADA,SPAIN. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. DLR,INST PLANETARY EXPLORAT,D-12489 BERLIN,GERMANY. BUR LONGITUDES,F-75015 PARIS,FRANCE. UNIV ARIZONA,STEWART OBSERV,TUCSON,AZ 85721. OBSERV PARIS,DESPA,F-92195 MEUDON,FRANCE. OBSERV MIDI PYRENEES,F-65200 BAGNERES BIGORRE,FRANCE. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. NATL SOLAR OBSERV,SUNSPOT,NM 88349. UNIV WISCONSIN,CTR SPACE SCI & ENGN,MADISON,WI 53706. UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90024. UNIV CALIF SAN DIEGO,CASS,LA JOLLA,CA 92093. LOWELL OBSERV,FLAGSTAFF,AZ 86001. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. UPPSALA ASTRON OBSERV,S-75120 UPPSALA,SWEDEN. UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. SMITHSONIAN ASTROPHYS OBSERV,CAMBRIDGE,MA 02138. UNIV MASSACHUSETTS,FIVE COLL RADIO ASTRON OBSERV,AMHERST,MA 01003. RP Orton, G (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Bjoraker, Gordon/D-5032-2012; OI Frappa, Eric/0000-0001-5327-7781; Hora, Joseph/0000-0002-5599-4650; Stewart, Sarah/0000-0001-9606-1593 NR 18 TC 52 Z9 53 U1 0 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 10 PY 1996 VL 272 IS 5263 BP 839 EP 840 DI 10.1126/science.272.5263.839 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UK757 UT WOS:A1996UK75700045 ER PT J AU Atkinson, DH Pollack, JB Seiff, A AF Atkinson, DH Pollack, JB Seiff, A TI Galileo Doppler measurements of the deep zonal winds at Jupiter SO SCIENCE LA English DT Article ID BALLOONS; MOTION; SATURN AB Changes in the speed of the Galileo probe caused by zonal winds created a small but measurable Doppler effect in the probe relay carrier frequency. Analysis of the probe relay link frequency allows direct measurements of the speed of Jupiter's zonal winds beneath the cloud tops, The deep winds were prograde and strong, reaching a sustained 190 to 200 meters per second at an altitude marked by a pressure of 24 bars. The depth and strength of the zonal winds severely constrain dynamic modeling of the deeper layers and begin to rule out many shallow weather theories. C1 NASA,AMES RES CTR,SAN JOSE STATE UNIV FDN,MOFFETT FIELD,CA 94035. RP Atkinson, DH (reprint author), UNIV IDAHO,MOSCOW,ID 83844, USA. NR 28 TC 52 Z9 52 U1 0 U2 0 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 10 PY 1996 VL 272 IS 5263 BP 842 EP 843 DI 10.1126/science.272.5263.842 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UK757 UT WOS:A1996UK75700047 ER PT J AU Seiff, A Kirk, DB Knight, TCD Mihalov, JD Blanchard, RC Young, RE Schubert, G vonZahn, U Lehmacher, G Milos, FS Wang, J AF Seiff, A Kirk, DB Knight, TCD Mihalov, JD Blanchard, RC Young, RE Schubert, G vonZahn, U Lehmacher, G Milos, FS Wang, J TI Structure of the atmosphere of Jupiter: Galileo probe measurements SO SCIENCE LA English DT Article AB Temperatures and pressures measured by the Galileo probe during parachute descent into Jupiter's atmosphere essentially followed the dry adiabat between 0.41 and 24 bars, consistent with the absence of a deep water cloud and with the low water content found by the mass spectrometer. From 5 to 15 bars, lapse rates were slightly stable relative to the adiabat calculated for the observed H-2/He ratio, which suggests that upward heat transport in that range is not attributable to simple radial convection, In the upper atmosphere, temperatures of >1000 kelvin at the 0.01-microbar level confirmed the hot exosphere that had been inferred from Voyager occultations. The thermal gradient increased sharply to 5 kelvin per kilometer at a reconstructed altitude of 350 kilometers, as was recently predicted, Densities at 1000 kilometers were 100 times those in the preencounter engineering model. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. UNIV CALIF LOS ANGELES,DEPT EARTH & SPACE SCI,LOS ANGELES,CA 90024. UNIV ROSTOCK,INST ATMOSPHARENPHYS,KUHLUNGSBORN,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Seiff, A (reprint author), SAN JOSE STATE UNIV,DEPT METEOROL,SAN JOSE,CA 95192, USA. RI Lehmacher, Gerald/F-2653-2013 NR 21 TC 79 Z9 79 U1 0 U2 10 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 10 PY 1996 VL 272 IS 5263 BP 844 EP 845 DI 10.1126/science.272.5263.844 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UK757 UT WOS:A1996UK75700048 ER PT J AU Niemann, HB Atreya, SK Carignan, GR Donahue, TM Haberman, JA Harpold, DN Hartle, RE Hunten, DM Kasprzak, WT Mahaffy, PR Owen, TC Spencer, NW Way, SH AF Niemann, HB Atreya, SK Carignan, GR Donahue, TM Haberman, JA Harpold, DN Hartle, RE Hunten, DM Kasprzak, WT Mahaffy, PR Owen, TC Spencer, NW Way, SH TI The Galileo probe mass spectrometer: Composition of Jupiter's atmosphere SO SCIENCE LA English DT Article ID GIANT PLANETS; ABUNDANCES; SATURN; SOLAR; RATIO AB The composition of the jovian atmosphere from 0.5 to 21 bars along the descent trajectory was determined by a quadrupole mass spectrometer on the Galileo probe. The mixing ratio of He (helium) to H-2 (hydrogen), 0.156, is close to the solar ratio. The abundances of methane, water, argon, neon, and hydrogen sulfide were measured; krypton and xenon were detected. As measured in the jovian atmosphere, the amount of carbon is 2.9 times the solar abundance relative to H-2, the amount of sulfur is greater than the solar abundance, and the amount of oxygen is much less than the solar abundance. The neon abundance compared with that of hydrogen is about an order of magnitude less than the solar abundance. Isotopic ratios of carbon and the noble gases are consistent with solar values. The measured ratio of deuterium to hydrogen (D/H) of (5 +/- 2) x 10(-5) indicates that this ratio is greater in solar-system hydrogen than in local interstellar hydrogen, and the He-3/He-4 ratio of (1.1 +/- 0.2) x 10(-4) provides a new value for protosolar (solar nebula) helium isotopes. Together, the D/H and He-3/He-4 ratios are consistent with conversion in the sun of protosolar deuterium to present-day He-3. C1 UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,ANN ARBOR,MI 48109. UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. RP Niemann, HB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Mahaffy, Paul/E-4609-2012; Harpold, Dan/I-3345-2013 NR 29 TC 178 Z9 181 U1 2 U2 18 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 10 PY 1996 VL 272 IS 5263 BP 846 EP 849 DI 10.1126/science.272.5263.846 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UK757 UT WOS:A1996UK75700049 PM 8629016 ER PT J AU Sromovsky, LA Best, FA Collard, AD Fry, PM Revercomb, HE Freedman, RS Orton, GS Hayden, JL Tomasko, MG Lemmon, MT AF Sromovsky, LA Best, FA Collard, AD Fry, PM Revercomb, HE Freedman, RS Orton, GS Hayden, JL Tomasko, MG Lemmon, MT TI Solar and thermal radiation in Jupiter's atmosphere: Initial results of the Galileo probe net flux radiometer SO SCIENCE LA English DT Article AB The Galileo probe net flux radiometer measured radiation within Jupiter's atmosphere over the 125-kilometer altitude range between pressures of 0.44 bar and 14 bars. Evidence for the expected ammonia cloud was seen in solar and thermal channels down to 0.5 to 0.6 bar. Between 0.6 and 10 bars large thermal fluxes imply very low gaseous opacities and provide no evidence for a deep water cloud. Near 8 bars the water vapor abundance appears to be about 10 percent of what would be expected for a solar abundance of oxygen. Below 8 bars, measurements suggest an increasing water abundance with depth or a deep cloud layer. Ammonia appears to follow a significantly subsaturated profile above 3 bars. Unexpectedly high absorption of sunlight was found at wavelengths greater than 600 nanometers. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. CALTECH,JET PROP LAB,PASADENA,CA 91109. LOCKHEED MARTIN ASTRONAUT,DENVER,CO 80201. UNIV ARIZONA,TUCSON,AZ 85721. RP Sromovsky, LA (reprint author), UNIV WISCONSIN,MADISON,WI 53706, USA. RI Lemmon, Mark/E-9983-2010 OI Lemmon, Mark/0000-0002-4504-5136 NR 14 TC 32 Z9 32 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 10 PY 1996 VL 272 IS 5263 BP 851 EP 854 DI 10.1126/science.272.5263.851 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UK757 UT WOS:A1996UK75700051 PM 8629018 ER PT J AU Fischer, HM Pehlke, E Wibberenz, G Lanzerotti, LJ Mihalov, JD AF Fischer, HM Pehlke, E Wibberenz, G Lanzerotti, LJ Mihalov, JD TI High-energy charged particles in the innermost jovian magnetosphere SO SCIENCE LA English DT Article AB The energetic particles investigation carried by the Galileo probe measured the energy and angular distributions of the high-energy particles from near the orbit of lo to probe entry into the jovian atmosphere. Jupiter's inner radiation region had extremely large fluxes of energetic electrons and protons; intensities peaked at similar to 2.2R(J) (where R(J) is the radius of Jupiter). Absorption of the measured particles was found near the outer edge of the bright dust ring. The instrument measured intense fluxes of high-energy helium ions (similar to 62 megaelectron volts per nucleon) that peaked at similar to 1.5R(J) inside the bright dust ring. The abundances of all particle species decreased sharply at similar to 1.35R(J); this decrease defines the innermost edge of the equatorial jovian radiation. C1 AT&T BELL LABS,LUCENT TECHNOL,MURRAY HILL,NJ 07974. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Fischer, HM (reprint author), CHRISTIAN ALBRECHTS UNIV KIEL,INST KERNPHYS,GUTENBERGSTR 76-78,D-24118 KIEL,GERMANY. NR 15 TC 23 Z9 23 U1 1 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 10 PY 1996 VL 272 IS 5263 BP 856 EP 858 DI 10.1126/science.272.5263.856 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UK757 UT WOS:A1996UK75700053 ER PT J AU Kemp, P AF Kemp, P TI Program provides ISA-bus DLL for Windows SO EDN LA English DT Article RP Kemp, P (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU CAHNERS-DENVER PUBLISHING CO PI HIGHLANDS RANCH PA 8773 S RIDGELINE BLVD, HIGHLANDS RANCH, CO 80126-2329 SN 0012-7515 J9 EDN JI EDN PD MAY 9 PY 1996 VL 41 IS 10 BP 90 EP 92 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA UK232 UT WOS:A1996UK23200021 ER PT J AU Verghese, P Stone, LS AF Verghese, P Stone, LS TI Perceived visual speed constrained by image segmentation SO NATURE LA English DT Article ID RESPONSES; VELOCITY; MOTION; AREA; DISCRIMINATION; DIRECTION; CONTRAST; CORTEX; FIELD AB LITTLE is known about how or where the visual system parses the visual scene into objects or surfaces. However, it is generally assumed that the segmentation and grouping of pieces of the image into discrete entities is due to 'later' processing stages, after the 'early' processing of the visual image by local mechanisms selective for attributes such as colour, orientation, depth, and motion(1). Speed perception is also thought to be mediated by early mechanisms tuned for speed(2-5). Here we show that manipulating the way in which an image is parsed changes the way in which local speed information is processed. Manipulations that cause multiple stimuli to appear as parts of a single patch degrade speed discrimination, whereas manipulations that perceptually divide a single large stimulus into parts improve discrimination. These results indicate that processes as early as speed perception may be constrained by the parsing of the visual image into discrete entities. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 27 TC 51 Z9 51 U1 0 U2 7 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD MAY 9 PY 1996 VL 381 IS 6578 BP 161 EP 163 DI 10.1038/381161a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UK139 UT WOS:A1996UK13900051 PM 8610014 ER PT J AU Smith, GD Yoon, DY Jaffe, RL Colby, RH Krishnamoorti, R Fetters, LJ AF Smith, GD Yoon, DY Jaffe, RL Colby, RH Krishnamoorti, R Fetters, LJ TI Conformations and structures of poly(oxyethylene) melts from molecular dynamics simulations and small-angle neutron scattering experiments SO MACROMOLECULES LA English DT Article ID ELECTRONIC-STRUCTURE CALCULATIONS; POLY(ETHYLENE OXIDE); MODEL MOLECULES; FORCE-FIELD; 1,2-DIMETHOXYETHANE; TEMPERATURE; DIMENSIONS; POLYOXYETHYLENE; POLYMETHYLENE; POLYETHYLENE AB An ensemble of H(CH2OCH2)(12)H chains has been studied by molecular dynamics simulations as both melt chains and unperturbed phantom chains as a model system to investigate condensed phase effects on chain conformations of poly(oxyethylene) (POE). In addition, conformations of high molecular weight POE chains in the melt have been determined by small-angle neutron scattering (SANS) experiments over a temperature range of 347-459 K. Our simulations show that POE chains in the melt are more extended than the phantom chains which represent the unperturbed chains in Theta solution. Moreover, the melt chains exhibit a negative temperature coefficient of chain dimensions in contrast to a positive value for the phantom chains. The difference in chain dimensions and the difference in the temperature dependence of chain dimensions between melt and phantom chains are corroborated by the results of our SANS measurements when they are compared with experimental results for POE chains in Theta solution. We attribute these significant deviations in conformational properties of POE chains in the melt from those of unperturbed ideal chains to condensed phase effects, similar to those found in 1,2-dimethoxyethane (DME), a dimer molecule of POE, from both experiments and simulations. That is, simulations show that the population of the C-C-O gt conformation is greater in melt chains than in the phantom chains, while the C-C-O g(+/-)g(-/+) populations are much smaller in the melt, the latter effect largely accounting for the more extended dimensions of the melt chains. As in DME, the conformation-dependent intermolecular polar attractions (O ... H interactions, for example) account for these condensed phase effects, which become more pronounced at lower temperatures. Such intermolecular polar attractions in POE melts also result in increased interatomic packing order, but do not appear to enhance the intermolecular orientational order when compared to simulation results for polymethylene melts. C1 IBM CORP,ALMADEN RES CTR,DIV RES,SAN JOSE,CA 95120. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. PENN STATE UNIV,DEPT MAT SCI & ENGN,UNIVERSITY PK,PA 16802. CORNELL UNIV,DEPT MAT SCI & ENGN,ITHACA,NY 14853. EXXON RES & ENGN CO,CORP RES,ANNANDALE,NJ 08801. RP Smith, GD (reprint author), UNIV MISSOURI,DEPT CHEM ENGN,COLUMBIA,MO 65211, USA. RI Krishnamoorti, Ramanan/F-7914-2011 OI Krishnamoorti, Ramanan/0000-0001-5831-502X NR 42 TC 126 Z9 126 U1 0 U2 24 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0024-9297 J9 MACROMOLECULES JI Macromolecules PD MAY 6 PY 1996 VL 29 IS 10 BP 3462 EP 3469 DI 10.1021/ma951621t PG 8 WC Polymer Science SC Polymer Science GA UK468 UT WOS:A1996UK46800021 ER PT J AU Anderson, JD Sjogren, WL Schubert, G AF Anderson, JD Sjogren, WL Schubert, G TI Galileo gravity results and the internal structure of Io SO SCIENCE LA English DT Article ID TIDAL DISSIPATION; TRACKING DATA; SATELLITES; JUPITER; MODELS; FIELD AB Doppler data generated with the Galileo spacecraft's radio carrier wave were used to measure lo's external gravitational field. The resulting triaxial field is consistent with the assumption that lo is in tidal and rotational equilibrium. The inescapable conclusion is that it has a large metallic core. If the core is a eutectic mixture of iron and iron sulfide, it comprises 20.2 +/- 7.4 percent of the satellite's total mass with a radius that is about 52 percent of lo's mean radius of 1821.3 kilometers; if the core is pure iron, it comprises 10.5 +/- 3.7 percent of the total mass with a radius of about 36 percent of the mean radius. C1 UNIV CALIF LOS ANGELES,DEPT EARTH & SPACE SCI,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90095. RP Anderson, JD (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 23 TC 99 Z9 102 U1 0 U2 5 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 3 PY 1996 VL 272 IS 5262 BP 709 EP 712 DI 10.1126/science.272.5262.709 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UJ051 UT WOS:A1996UJ05100046 ER PT J AU Roberts, DA Ogilvie, KW Goldstein, ML AF Roberts, DA Ogilvie, KW Goldstein, ML TI The nature of the solar wind SO NATURE LA English DT Letter ID TURBULENCE; EVOLUTION RP Roberts, DA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771, USA. RI Roberts, Dana/D-4625-2012; Goldstein, Melvyn/B-1724-2008 NR 5 TC 17 Z9 17 U1 1 U2 2 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD MAY 2 PY 1996 VL 381 IS 6577 BP 31 EP 32 DI 10.1038/381031a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UJ053 UT WOS:A1996UJ05300041 ER PT J AU Takahashi, TT Ross, JC AF Takahashi, TT Ross, JC TI Wake survey system SO AEROSPACE ENGINEERING LA English DT Article RP Takahashi, TT (reprint author), NASA,AMES RES CTR,NATL RES COUNCIL,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SOC AUTOMOTIVE ENG INC PI WARRENDALE PA 400 COMMONWEALTH DRIVE, WARRENDALE, PA 15096 SN 0736-2536 J9 AEROSPACE ENG JI Aerosp. Eng. PD MAY PY 1996 VL 16 IS 5 BP 31 EP 34 PG 4 WC Engineering, Aerospace SC Engineering GA UL336 UT WOS:A1996UL33600014 ER PT J AU Freund, JB Lele, SK Moini, P AF Freund, JB Lele, SK Moini, P TI Calculation of the radiated sound field using an open Kirchhoff surface SO AIAA JOURNAL LA English DT Article AB Means of improving the accuracy of Kirchhoff surface-integral evaluations for sound fields in cases where the surface may not be completely closed are investigated. Asymptotic analysis for large temporal wave number is used to analyze time-harmonic integral forms. Applicability to the moderate temporal wave numbers of real problems is discussed. Stationary-phase arguments are used to show geometrically where good results are expected from a Kirchhoff integral on an open surface. A similar asymptotic analysis is used to provide correction terms to account partially for the missing portion of the integral surface. The present study is restricted to the case where the mean how is parallel to the available portion of the surface. The analysis is extended to time-domain formulation of transient problems. Two- and three-dimensional numerical examples are given to demonstrate and evaluate the method. It is found that the derived correction terms can reduce the error in an open-surface calculation of the radiated sound field by more than an order of magnitude. C1 STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305. NASA,AMES RES CTR,DEPT ENGN MECH,MOFFETT FIELD,CA 94035. RP Freund, JB (reprint author), STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305, USA. RI Freund, Jonathan/A-6409-2014 NR 13 TC 35 Z9 36 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1996 VL 34 IS 5 BP 909 EP 916 DI 10.2514/3.13167 PG 8 WC Engineering, Aerospace SC Engineering GA UH935 UT WOS:A1996UH93500005 ER PT J AU Coirier, WJ Powell, KG AF Coirier, WJ Powell, KG TI Solution-adaptive Cartesian cell approach for viscous and inviscid flows SO AIAA JOURNAL LA English DT Article ID NAVIER-STOKES EQUATIONS; MESH REFINEMENT AB A Cartesian cell-based approach for adaptively refined solutions of the Euler and Navier-Stokes equations in two dimensions is presented. Grids about geometrically complicated bodies are generated automatically, by the recursive subdivision of a single Cartesian cell encompassing the entire flow domain. Where the resulting cells intersect bodies, polygonal cut cells are created using modified polygon-clipping algorithms. The grid is stored in a binary tree data structure that provides a natural means of obtaining cell-to-cell connectivity and of carrying out solution-adaptive mesh refinement. The Euler and Navier-Stokes equations are solved on the resulting grids using a finite volume formulation. The convective terms are upwinded: A linear reconstruction of the primitive variables is performed, providing input states to an approximate Riemann solver for computing the fluxes between neighboring cells. The results of a study comparing the accuracy and positivity of two classes of cell-centered, viscous gradient reconstruction procedures is briefly summarized. Adaptively refined solutions of the Navier-Stokes equations are shown using the more robust of these gradient reconstruction procedures, where the results computed by the Cartesian approach are compared to theory, experiment, and other accepted computational results for a series of low and moderate Reynolds number flows. C1 UNIV MICHIGAN,DEPT AEROSP ENGN,ANN ARBOR,MI 48109. RP Coirier, WJ (reprint author), NASA,LEWIS RES CTR,COMPUTAT FLUID DYNAM BRANCH,MAIL STOP 5-11,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. OI Powell, Kenneth/0000-0002-3708-8814 NR 42 TC 57 Z9 62 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1996 VL 34 IS 5 BP 938 EP 945 DI 10.2514/3.13171 PG 8 WC Engineering, Aerospace SC Engineering GA UH935 UT WOS:A1996UH93500009 ER PT J AU Knoll, DA McHugh, PR Keyes, DE AF Knoll, DA McHugh, PR Keyes, DE TI Newton-Krylov methods for low-Mach-number compressible combustion SO AIAA JOURNAL LA English DT Article ID ITERATIVE SOLUTION; LINEAR-SYSTEMS; EQUATIONS; MATRIX; FLOWS AB Fully coupled numerical techniques are used to compute steady-state solutions to a combusting, low-Mach-number compressible flow through a channel. The nonlinear governing equations are discretized on a staggered mesh via integration over discrete finite volumes. The resulting nonlinear algebraic equations are linearized with Newton's method and solved with a preconditioned Krylov algorithm. The selected Krylov solver is the generalized minimum residual algorithm. A matrix-free Newton-Krylov method and a modified Newton-Krylov method are employed as a means of reducing the required number of expensive Jacobian evaluations. The matrix-free implementation is shown to be superior to the modified Newton-Krylov method when starting from a poor initial guess. The technique of mesh sequencing is shown to provide significant CPU savings for fine grid calculations. Additionally, the domain-based multiplicative Schwarz preconditioning strategy was found to be more effective than incomplete lower-upper factorization type preconditioning at lower Mach numbers. C1 OLD DOMINION UNIV,DEPT COMP SCI,NORFOLK,VA 23529. NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681. RP Knoll, DA (reprint author), IDAHO NATL ENGN LAB,ENGN ANAL DEPT,POB 1625,IDAHO FALLS,ID 83415, USA. NR 25 TC 22 Z9 22 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1996 VL 34 IS 5 BP 961 EP 967 DI 10.2514/3.13174 PG 7 WC Engineering, Aerospace SC Engineering GA UH935 UT WOS:A1996UH93500012 ER PT J AU Cross, ER Newcomb, WW Tucker, CJ AF Cross, ER Newcomb, WW Tucker, CJ TI Use of weather data and remote sensing to predict the geographic and seasonal distribution of Phlebotomus papatasi in southwest Asia SO AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE LA English DT Article ID LEISHMANIA INFECTING MAN; CUTANEOUS LEISHMANIASIS; SAUDI-ARABIA; WILD ANIMALS; PARASITES; VECTORS AB Sandfly fever and leishmaniasis were major causes of infectious disease morbidity among military personnel deployed to the Middle East during World War II. Recently, leishmaniasis has been reported in the United Nations Multinational Forces and Observers in the Sinai. Despite these indications of endemicity, no cases of sandfly fever and only 31 cases of leishmaniasis have been identified among U.S. veterans of the Persian Gulf War. The distribution in the Persian Gulf of the vector, Phlebotomus papatasi, is thought to be highly dependent on environmental conditions, especially temperature and relative humidity. A computer model was developed using the occurrence of P. papatasi as the dependent variable and weather data as the independent variables. The results of this model indicated that the greatest sand fly activity and thus the highest risk of sandfly fever and leishmania infections occurred during the spring/summer months before U.S. troops were deployed to the Persian Gulf. Because the weather model produced probability of occurrence information for locations of the weather stations only, normalized difference vegetation index (NDVI) levels from remotely sensed Advanced Very High Resolution Radiometer satellites were determined for each weather station. From the results of the frequency of NDVI levels by probability of occurrence, the range of NDVI levels for presence of the vector was determined. The computer then identified all pixels within the NDVI range indicated and produced a computer-generated map of the probable distribution of P. papatasi. The resulting map expanded the analysis to areas where there were no weather stations and from which no information was reported in the literature, identifying these areas as having either a high or low probability of vector occurrence. C1 NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771. USN,MED RES INST,INFECT DIS THREAT ASSESSMENT,BETHESDA,MD. NR 24 TC 86 Z9 88 U1 0 U2 8 PU AMER SOC TROP MED & HYGIENE PI MCLEAN PA 8000 WESTPARK DRIVE SUITE 130, MCLEAN, VA 22101 SN 0002-9637 J9 AM J TROP MED HYG JI Am. J. Trop. Med. Hyg. PD MAY PY 1996 VL 54 IS 5 BP 530 EP 536 PG 7 WC Public, Environmental & Occupational Health; Tropical Medicine SC Public, Environmental & Occupational Health; Tropical Medicine GA UP632 UT WOS:A1996UP63200017 PM 8644911 ER PT J AU Mehta, SK Mishra, SK Pierson, DL AF Mehta, SK Mishra, SK Pierson, DL TI Evaluation of three portable samplers for monitoring airborne fungi SO APPLIED AND ENVIRONMENTAL MICROBIOLOGY LA English DT Article ID BIOLOGICAL AEROSOLS; SAMPLING METHODS AB Airborne fungi were monitored at five sample sites with the Burkard portable, the RCS Plus, and the SAS Super 90 air samplers; the Andersen 2-stage impactor was used for comparison. All samplers were calibrated before being used simultaneously to collect 100-liter samples at each site. The Andersen and Burkard samplers retrieved equivalent volumes of airborne fungi; the SAS Super 90 and RCS Plus measurements did not differ from each other hut were significantly lower than those obtained with the Andersen or Burkard samplers. Total fungal counts correlated linearly with Cladosporium and Penicillium counts. Alternaria species, although present at all sites, did not correlate with total count or with amounts of any other fungal genera. Sampler and location significantly influenced fungal counts, but no interactions between samplers and locations were found. C1 NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,KRUG LIFE SCI,HOUSTON,TX 77058. GOVT MED COLL,AMRITSAR,PUNJAB,INDIA. NR 14 TC 33 Z9 33 U1 1 U2 5 PU AMER SOC MICROBIOLOGY PI WASHINGTON PA 1325 MASSACHUSETTS AVENUE, NW, WASHINGTON, DC 20005-4171 SN 0099-2240 J9 APPL ENVIRON MICROB JI Appl. Environ. Microbiol. PD MAY PY 1996 VL 62 IS 5 BP 1835 EP 1838 PG 4 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA UJ228 UT WOS:A1996UJ22800060 PM 11536729 ER PT J AU Talamonti, JJ Kay, RB Krebs, DJ AF Talamonti, JJ Kay, RB Krebs, DJ TI Numerical model estimating the capabilities and limitations of the fast Fourier transform technique in absolute interferometry SO APPLIED OPTICS LA English DT Article DE numerical model; Fourier transform; absolute distance; interferometer ID FRINGE-PATTERN-ANALYSIS AB A numerical model was developed to emulate the capabilities of systems performing noncontact absolute distance measurements. The model incorporates known methods to minimize signal processing and digital sampling errors and evaluates the accuracy limitations imposed by spectral peak isolation by using Hanning, Blackman, and Gaussian windows in the fast Fourier transform technique. We applied this model to the specific case of measuring the relative lengths of a compound Michelson interferometer. BY processing computer-simulated data through our model, we project the ultimate precision for ideal data, and data containing AM-FM noise. The precision is shown to be limited by nonlinearities in the laser scan. (C) 1996 Optical Society of America C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Talamonti, JJ (reprint author), AMERICAN UNIV,DEPT PHYS,4400 MASSACHUSETTS AVE NW,WASHINGTON,DC 20016, USA. NR 9 TC 13 Z9 16 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAY 1 PY 1996 VL 35 IS 13 BP 2182 EP 2191 DI 10.1364/AO.35.002182 PG 10 WC Optics SC Optics GA UG861 UT WOS:A1996UG86100006 PM 21085348 ER PT J AU Perlman, ES Carilli, CL Stocke, JT Conway, J AF Perlman, ES Carilli, CL Stocke, JT Conway, J TI Multifrequency VLBI observations of PKS 1413+135: A very young radio galaxy SO ASTRONOMICAL JOURNAL LA English DT Article ID VLA OBSERVATIONS; SPECTRUM; NGC-1068; GHZ; PKS-1413+135; ABSORPTION; EMISSION; HYDROGEN; OBJECTS AB We present high-dynamic range VLBA maps of the radio galaxy/BL Lac object PKS 1413+135 at 3.6, 6, 13, and 18 cm. These observations reveal that PKS 1413+135 possesses complex, two-sided parsec-scale structure, similar to that of other compact symmetric objects (CSOs). Its morphology appears to be that of a miniature wide-angle-tail (WAT) radio source, and its total power is at the upper extreme of that seen in WATs. Comparison of these maps with previous data reveals no evidence for superluminal motion, and supports the hypothesis that the milliarcsecond-scale structure of PKS 1413+135, unlike most BL Lacs and flat radio spectrum quasars, is not a product of relativistic beaming. However, beaming is likely present within the core seen at 3.6 cm, due to its high brightness temperature. These new VLBA maps allow a more precise, but not completely unambiguous, interpretation of the various absorption data, suggesting that the A(v)>30 mag is due to a normal molecular cloud complex in the disk of the optical spiral galaxy at z=0.247, greater than or similar to few kpc away from its nucleus. The absence of scatter broadening of the core source at 1.6 and 2.3 GHz and the lack of multiple images add to the evidence against the hypothesis (originally suggested by Stocke et al.) that PKS 1413+135 is background to the spiral galaxy at z=0.247, in which the AGN appears centered. But if the AGN is within the spiral, the absence of reprocessed radiation (e.g., near-IR dust continuum and emission lines) remains difficult to understand, since the very high extinction is unlikely to cover the entire dust and line emitting regions. Whether within or background to the optical galaxy, PKS 1413+135 is similar to other CSOs in being a young radio source (of age less than or similar to 10(4) yr), with evidence for absorption along our line of sight. (C) 1996 American Astronomical Society. C1 SMITHSONIAN ASTROPHYS OBSERV, CAMBRIDGE, MA 02138 USA. UNIV COLORADO, CTR ASTROPHYS & SPACE ASTRON, BOULDER, CO 80309 USA. ONSALA SPACE OBSERV, S-43992 ONSALA, SWEDEN. RP Perlman, ES (reprint author), NASA, GODDARD SPACE FLIGHT CTR, LHEA, USRA, MAIL CODE 660 2, GREENBELT, MD 20771 USA. NR 69 TC 36 Z9 36 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 1996 VL 111 IS 5 BP 1839 EP 1851 DI 10.1086/117922 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UG899 UT WOS:A1996UG89900007 ER PT J AU Dixon, WV Davidsen, AF Dorman, B Ferguson, HC AF Dixon, WV Davidsen, AF Dorman, B Ferguson, HC TI Constraints on the horizontal-branch morphology of the globular cluster M79 (NGC 1904) from optical and far-UV observations SO ASTRONOMICAL JOURNAL LA English DT Article ID HOPKINS ULTRAVIOLET TELESCOPE; RESOLUTION CCD SPECTRA; STARS; NGC-1904; ABUNDANCES; 47-TUC; CORES; M22; M4 AB The globular cluster M79 was observed with the Hopkins Ultraviolet Telescope (HUT) during the Astro-l space shuttle mission in 1990 December. The cluster's far-UV integrated spectrum shows strong absorption in the Lyman lines of atomic hydrogen. We seek to use this spectrum, together with optical photometry, to constrain the stellar mass distribution along its zero-age horizontal branch (ZAHB). We find that a Gaussian distribution of ZAHB masses, with a mean of 0.59M(.) and standard deviation 0.05M(.), is able to reproduce the cluster's (B,V) color-magnitude diagram when subsequent stellar evolution is taken into account, but cannot reproduce the cluster's far-UV spectrum. Model stellar spectra fit directly to the HUT data indicate a surprising distribution of atmospheric parameters, with surface gravities (and thus implied masses) significantly lower than are predicted by canonical HE evolutionary models. This result is consistent with the findings of Moehler et al. [A&A, 294, 65 (1995)] for individual HB stars in M15. Further progress in understanding the mass distribution of the HE must await resolution of the inconsistencies between the derived stellar atmospheric parameters and the predictions of HE evolutionary models. Improved stellar spectral models, with higher spectral resolution and non-solar abundance ratios, may prove useful in this endeavor. (C) 1996 American Astronomical Society. C1 NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. SPACE TELESCOPE SCI INST, BALTIMORE, MD 21218 USA. RP Dixon, WV (reprint author), JOHNS HOPKINS UNIV, DEPT PHYS & ASTRON, 3400 N CHARLES ST, BALTIMORE, MD 21218 USA. NR 35 TC 19 Z9 19 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 1996 VL 111 IS 5 BP 1936 EP 1944 DI 10.1086/117931 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UG899 UT WOS:A1996UG89900016 ER PT J AU Kaspi, VM Manchester, RN Johnston, S Lyne, AG DAmico, N AF Kaspi, VM Manchester, RN Johnston, S Lyne, AG DAmico, N TI A search for radio pulsars in southern supernova remnants SO ASTRONOMICAL JOURNAL LA English DT Article ID YOUNG PULSARS; PERIOD; BEAMS; BIRTHRATE; G5.4-1.2; NEBULAE; W28 AB We have searched 40 southern Galactic supernova remnants for radio pulsars at 436, 660, and 1520 MHz, Our survey covered each target remnant in its entirety and was sensitive to pulsars with minimum luminosities in the range 5-500 mJy kpc(2), with mean similar to 100 mJy kpc(2), at 400 MHz, In addition to detecting eight known pulsars, we have discovered two new pulsars, PSR J1104-6103 and PSR J1627-4845, Both have characteristic ages of over two million years, and hence are not likely to be associated with their target remnants. However, the association of PSR J1627-4845 with its target remnant, G335.2+0.1, is plausible if the pulsar was born with a long spin period. We conclude that the main inhibiting factor against the discovery of new young pulsars is sensitivity, suggesting that deeper searches of supernova remnants are warranted. (C) 1996 American Astronomical Society. C1 CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. UNIV SYDNEY,RES CTR THEORET ASTROPHYS,SYDNEY,NSW 2006,AUSTRALIA. UNIV MANCHESTER,NUFFIELD RADIO ASTRON LABS,MACCLESFIELD SK11 9DL,CHESHIRE,ENGLAND. OSSERV ASTRON BOLOGNA,I-40126 BOLOGNA,ITALY. IST RADIOASTRON,I-40129 BOLOGNA,ITALY. RP Kaspi, VM (reprint author), CALTECH,JET PROP LAB,IPAC,4800 OAK GROVE DR,PASADENA,CA 91125, USA. RI D'Amico, Nichi/A-5715-2009 NR 49 TC 66 Z9 66 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 1996 VL 111 IS 5 BP 2028 EP 2037 DI 10.1086/117938 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UG899 UT WOS:A1996UG89900023 ER PT J AU Schlegel, EM Kirshner, RP Huchra, JP Schild, RE AF Schlegel, EM Kirshner, RP Huchra, JP Schild, RE TI The peculiar type II SN1987B in NGC 5850 SO ASTRONOMICAL JOURNAL LA English DT Article ID IB SUPERNOVAE; LIGHT CURVES; OPTICAL-SPECTRA; RADIO-EMISSION; SN-1986J; NGC-891; NGC-991; HELIUM; 1987A; STARS AB Nine photometric and five spectroscopic observations of the peculiar Type II supernova SN1987B in NGC 5850 are presented. The light curve is different from any of the typical supernova light curves. The light curve falls as slowly as a Type IIP light curve for similar to 50 days, then steepens considerably, in contrast to the spectroscopically similar object SN1988Z. Both SN1987B and SN1988Z have been considered as representative of ''Type IIn'' supernovae, those supernovae that show circumstellar signatures in their spectra. The spectra of SN1987B show weak hydrogen emission lines with a narrow core (FWZI similar to 1000 km s(-1)) and weak, low-contrast emission lines of hydrogen with a FWZI of similar to 8000 km s(-1). Both photometric and spectroscopic evidence suggests SN1987B had a low-mass envelope. (C) 1996 American Astronomical Society. C1 HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. RP Schlegel, EM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 668,GREENBELT,MD 20771, USA. NR 54 TC 10 Z9 10 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 1996 VL 111 IS 5 BP 2038 EP 2046 DI 10.1086/117939 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UG899 UT WOS:A1996UG89900024 ER PT J AU Lanz, T Artru, MC LeDourneuf, M Hubeny, I AF Lanz, T Artru, MC LeDourneuf, M Hubeny, I TI Photoionization resonances of Si II in stellar spectra SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE atomic data; lines, identification; stars, atmospheres; stars, chemically peculiar; ultraviolet, stars ID R-MATRIX; OPACITY CALCULATIONS; ATOMIC DATA; STARS; MODEL; ULTRAVIOLET; ATMOSPHERES; ABSORPTION; PROGRAM; MG AB We have studied the influence of the Si+ photoionization on stellar atmospheres. Recent calculations using the R-matrix code provide detailed cross-sections with autoionization resonances for the first 50 energy levels of Si+. These photoionization cross-sections are included in the calculation of the far ultraviolet synthetic spectrum of A and late B-type stars. The opacity from the six lowest excited states of Si+ provides observable features in the emergent spectrum of a solar-composition AO star. The photoionization from higher states of Si+ should be included when modeling hotter or silicon-rich stars. These new cross-sections increase dramatically the-opacity in the far UV spectrum of Ap Si stars and allow to reproduce the most characteristic UV features of these stars, as illustrated by a comparison with IUE data for the hot Ap Si star HD 34452. Broad features in its spectrum are definitely assigned to Si II autoionization resonances, and the flux deficiency below 130 nm is well matched with a predicted continuum edge near this wavelength. The successful stellar spectrum synthesis brings a strong support to the R-matrix photoionization calculations, which cannot otherwise be compared to laboratory data. C1 ECOLE NORMALE SUPER LYON, CTR RECH ASTRON LYON, F-69364 LYON, FRANCE. UNIV RENNES 1, LAB SIMPA, CNRS, EP99, F-35042 RENNES, FRANCE. RP Lanz, T (reprint author), NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, CODE 681, GREENBELT, MD 20771 USA. NR 34 TC 21 Z9 21 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 1996 VL 309 IS 1 BP 218 EP 226 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UK343 UT WOS:A1996UK34300031 ER PT J AU Kaufmann, DE Contopoulos, G AF Kaufmann, DE Contopoulos, G TI Self-consistent models of barred spiral galaxies SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE galaxies, kinematics and dynamics; galaxies, spiral; galaxies, structure; galaxies, NGC 3992; NGC 1073; NGC 1398 ID HIGH-RESOLUTION OBSERVATIONS; ROTATION CURVES; GALACTIC BARS; DENSITY WAVES; DYNAMICS; KINEMATICS; GAS; INSTABILITY; INDICATORS; COROTATION AB We have constructed self-consistent models of the barred spiral galaxies NGC 3992, NGC 1073, and NGC 1398 based on their rotation curves and surface photometry. The main factors that influence self-consistency are the global shape and amplitude of the bar/spiral perturbation, the bar/spiral pattern speed, the axisymmetric background disk density, and the velocity dispersion. Under the assumption of a single pattern speed for both bar and spiral, the preferred situation is for the spiral arms to emanate directly from the ends of the bar. In each model the structure of the bar and of the outermost portions of the spiral arms is dominated by regular orbits trapped around the central family. On the other hand, chaotic orbits whose Jacobi constants lie between the values at the Lagrange points L(1) and L(4) are found to play a significant role in supporting the inner portions of the spiral arms from the ends of the bar out to approximately the outer 4/1 resonance. C1 UNIV FLORIDA, DEPT ASTRON, GAINESVILLE, FL 32611 USA. UNIV ATHENS, DEPT ASTRON, GR-15783 ATHENS, GREECE. RP NASA, GODDARD SPACE FLIGHT CTR, IUE OBSERV, COMP SCI CORP, CODE 6849, GREENBELT, MD 20771 USA. NR 62 TC 69 Z9 70 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 1996 VL 309 IS 2 BP 381 EP 402 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UK956 UT WOS:A1996UK95600010 ER PT J AU Shebalin, JV Tippens, AL AF Shebalin, JV Tippens, AL TI Interplay and escape in three-body scattering SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE binaries, close; galaxy, globular clusters, general; celestial mechanics; scattering ID BINARY-SINGLE STAR AB The problem of three gravitationally interacting bodies, with total energy less than zero, is investigated numerically. After introducing the concepts of 'periastron graphs' and 'composite binaries', time-of-escape and interplay are precisely defined. These definitions are useful in characterizing the complete scattering process: escape to t = -infinity, interplay, and escape to t = +infinity. These definitions are also useful for the efficient and automatic termination of a numerical simulation of interplay. C1 NEW HORIZONS TECH CTR, GOVERNORS SCH SCI & TECHNOL, HAMPTON, VA 23666 USA. RP Shebalin, JV (reprint author), NASA, LANGLEY RES CTR, MAIL STOP 128, HAMPTON, VA 23681 USA. NR 12 TC 2 Z9 2 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 1996 VL 309 IS 2 BP 459 EP 464 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UK956 UT WOS:A1996UK95600017 ER PT J AU Justtanont, K Barlow, MJ Skinner, CJ Roche, PF Aitken, DK Smith, CH AF Justtanont, K Barlow, MJ Skinner, CJ Roche, PF Aitken, DK Smith, CH TI Mid-infrared spectroscopy of carbon-rich post-AGB objects and detection of the PAH molecule chrysene SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars, post-AGB; circumstellar matter; dust; molecular data ID PROTO-PLANETARY-NEBULAE; M STELLAR SPECTROPHOTOMETRY; EMISSION FEATURES; CIRCUMSTELLAR SHELLS; IRAS SOURCES; STARS; SPECTRA; DUST; BANDS; SUPERGIANTS AB We present 10 and 20-mu m spectroscopic observations of a sample of F- and C-type carbon-rich post-AGE objects, three of which were known to exhibit the unidentified emission feature at 21 mu m. We also find the F3I post-AGE object SAO 163075 to exhibit a (weak) 21-mu m emission feature. We additionally obtained a 10-mu m spectrum of IRAS 05341+0852, which has been reported to have a possible 21-mu m emission band in its IRAS LRS spectrum, and obtained new 10 and 20-mu m spectra of the carbon-rich bipolar post-AGE sources GL 2688 and GL 618, the extreme carbon star GL 3068, and the planetary nebulae IRAS 21282+5050 and He 2-447, in order to study the evolution of C-rich dust from the early post-AGE through to the planetary nebula (PN) phases. The 7.5-13-mu m spectra of the 21-mu m band objects exhibit broad plateau emission, shortwards of 9 mu m and from 10-13 mu m, superposed upon which, in addition to the well-known UIR-band at 11.3 mu m, are several new features, at 7.9, 8.2, 10.6, 11.5 and 12.2 mu m, differing from those observed in standard UIR-band spectra. An excellent match is found between the wavelengths of these new features and those of bands in the spectrum of chrysene (C18H12), one of the simplest PAH molecules. The absence of the new features in the spectra of earlier spectral-type post-AGE objects and PN is consistent with the expected complete dehydrogenation of any PAH molecules having less than 20-25 carbon atoms when exposed to the ultraviolet radiation fields of stars with spectral types earlier than F. Chrysene is not responsible for the 21-mu m emission bands observed in the spectra of the cool post-AGE objects. Possible identifications for the 21-mu m band in terms of highly hydrogenated 2-dimensional PAH molecules or 3-dimensional fulleranes (hydrogenated fullerenes) are discussed, The mid-infrared spectrum of GL 2688 is largely featureless, apart from two broad weak emission features between 9.5-10.5 and 10.5-12.2 mu m. The profiles of the broad 10-13-mu m absorption features in the spectra of the extreme carbon star GL 3068 and the C-rich bipolar post-AGE object GL 618 are compared. For GL 3068 the profile shape and the wavelength of peak absorption, near 11 mu m, are consistent with absorption by silicon carbide particles. However, the absorption observed towards GL 618 is considerably broader and peaks at 12 mu m. Its profile is very similar to that of the 10-13-mu m emission plateau observed in the spectra of the 21-mu m band objects, suggesting that it arises from absorption by a large column of highly-hydrogenated PAH-type species. C1 UCL, DEPT PHYS & ASTRON, LONDON WC1E 6BT, ENGLAND. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. INST ASTROPHYS PARIS, F-75014 PARIS, FRANCE. LAWRENCE LIVERMORE NATL LAB, INST GEOPHYS & PLANETARY PHYS, LIVERMORE, CA 94581 USA. UNIV OXFORD, DEPT PHYS, OXFORD OX1 3RH, ENGLAND. UNIV COLL, ADFA, DEPT PHYS, CAMPBELL, ACT 2600, AUSTRALIA. RI Barlow, Michael/A-5638-2009; OI Barlow, Michael/0000-0002-3875-1171; Roche, Patrick/0000-0002-8524-8413; /0000-0003-1689-9201 NR 67 TC 67 Z9 68 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 1996 VL 309 IS 2 BP 612 EP 628 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UK956 UT WOS:A1996UK95600031 ER PT J AU Michalowski, T AF Michalowski, T TI A new model of the asteroid 532 Herculina SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE asteroids; planets and satellites, individual, 532 Herculina ID GALILEO PHYSICAL MODEL; ATMOSPHERELESS BODIES; LIGHTCURVES; 532-HERCULINA; INVERSION AB The asteroid 532 Herculina has very unusual lightcurves. They exhibit two maxima and two minima per rotational cycle in some apparitions and only one maximum and minimum within the same period during others. It was not possible to explain such lightcurves with a triaxial ellipsoidal shape, so a new, more complex model has been proposed. It is also a triaxial ellipsoid but with rotation around an axis which does not coincide with the c-axis of ellipsoid. The parameters obtained for Herculina are as follows: the ecliptic coordinates of the north pole are (295 degrees, +36 degrees), triaxial ellipsoid shape with a/b = 1.21 and b/c = 1.20, and an angle of 7 degrees between the rotational axis and the c-axis of ellipsoid. The dihedral angle between the plane containing the a and c axes and the plane with the c-axis and the axis of rotation is 80 degrees. The synthetic and observed lightcurves show a global agreement in shapes of the lightcurves and timings of extrema during the 1954 - 1992 period. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP Michalowski, T (reprint author), ADAM MICKIEWICZ UNIV POZNAN, ASTRON OBSERV, UL SLONECZNA 36, PL-60286 POZNAN, POLAND. NR 32 TC 6 Z9 6 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 1996 VL 309 IS 3 BP 970 EP 978 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP984 UT WOS:A1996UP98400035 ER PT J AU Barbiellini, G Basini, G Bellotti, R Bocciolini, M Boezio, M Brancaccio, FM Bravar, U Cafagna, F Candusso, M Carlson, P Casolino, M Castellano, M Circella, M Codino, A DeCataldo, G DeMarzo, C DePascale, MP Finetti, N Francke, T Giglietto, N Golden, RL Grimani, C Hof, M Marangelli, B Menn, W Mitchell, JW Morselli, A Ormes, JF Papini, P Perego, A Piccardi, S Picozza, P Ricci, M Schiavon, P Simon, M Sparvoli, R Spillatini, P Spinelli, P Stephens, SA Stochaj, SJ Streitmatter, RE Suffert, M Vacchi, A Weber, N Zampa, N AF Barbiellini, G Basini, G Bellotti, R Bocciolini, M Boezio, M Brancaccio, FM Bravar, U Cafagna, F Candusso, M Carlson, P Casolino, M Castellano, M Circella, M Codino, A DeCataldo, G DeMarzo, C DePascale, MP Finetti, N Francke, T Giglietto, N Golden, RL Grimani, C Hof, M Marangelli, B Menn, W Mitchell, JW Morselli, A Ormes, JF Papini, P Perego, A Piccardi, S Picozza, P Ricci, M Schiavon, P Simon, M Sparvoli, R Spillatini, P Spinelli, P Stephens, SA Stochaj, SJ Streitmatter, RE Suffert, M Vacchi, A Weber, N Zampa, N TI The cosmic-ray positron-to-electron ratio in the energy range 0.85 to 14 GeV SO ASTRONOMY & ASTROPHYSICS LA English DT Letter DE cosmic rays, abundances; elementary particles AB We report on the positron to electron ratio in the cosmic radiation over more than one decade in energy from 0.85 to 14 GeV, using the NMSU-WiZard/CAPRICE balloon borne magnet spectrometer. The spectrometer uses a solid radiator RICH detector and a silicon-tungsten calorimeter for particle identification. The proton rejection factor of the two instruments combined is better than 2 x 10(-6) between 0.6 and 3 GV/c dropping to 6 x 10(-5) at 5 GV/c and 10(-4) at 10 GV/c. The data was collected during 23 hours at a mean residual atmosphere of 4.0 g/cm(2). From a total of 2756 well identified e(-) and 498 e(+) we are able to construct the positron fraction R = e(+) /(e(+) + e(-)) as a function of energy with small errors from 0.85 GeV to 14 GeV for the first time. We observe a decreasing ratio in this energy region. This energy dependent behaviour is consistent with the simple leaky box model. The positron fraction in the upper energy bins are in agreement with the latest high energy measurements. C1 IST NAZL FIS NUCL, SEZ TRIESTE, I-34147 TRIESTE, ITALY. CTR RECH NUCL, F-67037 STRASBOURG, FRANCE. ROYAL INST TECHNOL, S-10405 STOCKHOLM, SWEDEN. UNIV SIEGEN, D-57068 SIEGEN, GERMANY. UNIV ROME, DIPARTIMENTO FIS, I-00133 ROME, ITALY. IST NAZL FIS NUCL, SEZ ROMA, I-00133 ROME, ITALY. UNIV PERUGIA, DIPARTIMENTO FIS, I-06100 PERUGIA, ITALY. IST NAZL FIS NUCL, SEZ PERUGIA, I-06100 PERUGIA, ITALY. NEW MEXICO STATE UNIV, LAS CRUCES, NM 88003 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. IST NAZL FIS NUCL, LAB NAZL, I-00044 FRASCATI, ITALY. UNIV FLORENCE, DIPARTIMENTO FIS, I-50125 FLORENCE, ITALY. IST NAZL FIS NUCL, SEZ FIRENZE, I-50125 FLORENCE, ITALY. TATA INST FUNDAMENTAL RES, BOMBAY 400005, MAHARASHTRA, INDIA. UNIV BARI, DIPARTMENTO FIS, I-70126 BARI, ITALY. IST NAZL FIS NUCL, SEZ BARI, I-70126 BARI, ITALY. RP Barbiellini, G (reprint author), UNIV TRIESTE, DIPARTMENTO FIS, VIA A VALERIO 2, I-34147 TRIESTE, ITALY. RI Cafagna, Francesco/A-9299-2010; Morselli, Aldo/G-6769-2011; giglietto, nicola/I-8951-2012; Castellano, Marcello/J-3428-2012; Vacchi, Andrea/C-1291-2010 OI Cafagna, Francesco/0000-0002-7450-4784; Morselli, Aldo/0000-0002-7704-9553; giglietto, nicola/0000-0002-9021-2888; Castellano, Marcello/0000-0002-4211-2903; Vacchi, Andrea/0000-0003-3855-5856 NR 19 TC 33 Z9 33 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 1996 VL 309 IS 1 BP L15 EP L18 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UK343 UT WOS:A1996UK34300005 ER PT J AU Loiseau, S Shaklan, S AF Loiseau, S Shaklan, S TI Optical design, modelling and tolerancing of a Fizeau interferometer dedicated to astrometry SO ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES LA English DT Article DE instrumentation, interferometers; telescopes; astrometry AB Space-based interferometers dedicated to wide-angle astrometry would dramatically increase the accuracy of angular measurements fundamental to a wide range of astrophysical problems. The proposed Global Astrometric Interferometer for Astrophysics (GAIA), a continuously rotating instrument comprising two or three interferometers, will reach the 5 - 20 mu as level on more than 35 million objects. The necessary wide field-of-view for such a precision could be obtained with a Fizeau interferometer. We designed and modelled a 2.6 m baseline interferometer with two 40 cm apertures, and overall dimensions compatible with the size of the Ariane V payload shroud. It has a similar to 1 degree diffraction limited field-of-view. The response of the optical system to small perturbations on each optical element is given in terms of fringe visibility, which is shown to depend mainly on sub-aperture spot separation. The robustness of the design to thermal, mechanical and manufacturing errors is discussed. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Loiseau, S (reprint author), OBSERV PARIS,DESPA,F-92195 MEUDON,FRANCE. NR 17 TC 8 Z9 8 U1 0 U2 2 PU EDITIONS PHYSIQUE PI LES ULIS CEDEX PA Z I DE COURTABOEUF AVE 7 AV DU HOGGAR, BP 112, 91944 LES ULIS CEDEX, FRANCE SN 0365-0138 J9 ASTRON ASTROPHYS SUP JI Astron. Astrophys. Suppl. Ser. PD MAY PY 1996 VL 117 IS 1 BP 167 EP 178 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UL353 UT WOS:A1996UL35300014 ER PT J AU Souchay, J Feissel, M Ma, C AF Souchay, J Feissel, M Ma, C TI Precise modeling of nutation and VLBI observations SO ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES LA English DT Article DE reference systems; Earth AB Using geodetic and astrometric VLBI acquired between 1984-1994, are have determined coefficients in the nutation series with uncertainties of 10 microarcseconds. This level of accuracy is quite sufficient to differentiate between alternate theories of nutation. We show that small terms predicted using the Kinoshita & Souchay (1990) rigid Earth theory of nutation revised by Souchay & Kinoshita (1995), agree well with the VLBI results at periods where the non rigid Earth corrections are reliable. These terms are different or absent from the Kinoshita (1977) theory that is the basis for the standard IAU 1980 model. We propose a nutation series based on the Kinoshita & Souchay theory using the Wahr (1979) transformation for a non rigid Earth that can be useful where the physical interpretation of the smaller terms is important. This series, called VKSNRED5.1, includes corrections to the nine largest terms derived from VLBI observations. C1 NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771. RP Souchay, J (reprint author), OBSERV PARIS,DANOF,URA 1125 CNRS,61 AVE OBSERV,F-75014 PARIS,FRANCE. RI Ma, Chopo/D-4751-2012 NR 17 TC 2 Z9 3 U1 0 U2 0 PU EDITIONS PHYSIQUE PI LES ULIS CEDEX PA Z I DE COURTABOEUF AVE 7 AV DU HOGGAR, BP 112, 91944 LES ULIS CEDEX, FRANCE SN 0365-0138 J9 ASTRON ASTROPHYS SUP JI Astron. Astrophys. Suppl. Ser. PD MAY PY 1996 VL 116 IS 3 BP 473 EP 481 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ227 UT WOS:A1996UJ22700008 ER PT J AU Hakkila, J Meegan, CA Horack, JM Pendleton, GN Briggs, MS Mallozzi, RS Koshut, TM Preece, RD Paciesas, WS AF Hakkila, J Meegan, CA Horack, JM Pendleton, GN Briggs, MS Mallozzi, RS Koshut, TM Preece, RD Paciesas, WS TI Luminosity distributions of cosmological gamma-ray bursts SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays, bursts ID GALACTIC HALO; BATSE; STATISTICS; MODELS; DISK AB The intrinsic luminosities of gamma-ray bursts are found to be constrained by the BATSE/PVO combined intensity distribution, assuming that (1) bursts originate in Lambda = 0, Omega = 1 Friedmann cosmology with a nonevolving density distribution, (2) the nonevolving intrinsic luminosity function can be modeled as a truncated power law, and (3) burst spectra are modeled as power laws with identical spectral indices. These simplifying assumptions allow constraints to be placed on luminosity functions in cosmological gamma-ray burst scenarios and indicate that standard-candle sources are not favored. In general, either the minimum burst luminosity L(min) or the maximum burst luminosity L(max) are known, with the opposite end of the luminosity function unconstrained. Both L(max) and L(min) must be specified for luminosity power-law indices near 2. When these results are combined with other studies measuring other cosmological burst signatures, it is possible that the intrinsic luminosity function contains more low-luminosity bursts than high-luminosity ones. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. RP Hakkila, J (reprint author), MANKATO STATE UNIV,DEPT PHYS & ASTRON,MANKATO,MN 56002, USA. RI Horack, John/J-6670-2016; OI Preece, Robert/0000-0003-1626-7335 NR 59 TC 21 Z9 22 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 1996 VL 462 IS 1 BP 125 EP 130 DI 10.1086/177134 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UG298 UT WOS:A1996UG29800013 ER PT J AU Horack, JM Hakkila, J Emslie, AG Meegan, CA AF Horack, JM Hakkila, J Emslie, AG Meegan, CA TI Analytic constraints on gamma-ray burst luminosity functions SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays, bursts AB The brightness distribution of detected gamma-ray bursts enables constraints to be placed on their luminosities; specifically, analyses by previous authors have demonstrated that the range of luminosity from which approximately 90% of the observed bursts are drawn is very likely less than an order of magnitude. It has also been demonstrated that when power-law functional forms with infinite ranges of luminosity (a) from 0 to L(max) or (b) from L(min) to infinity are employed, it is necessary (but perhaps not sufficient) to restrict the power-law index beta < 1.8 and beta > 2.5, respectively, in order to obtain consistency with the observed brightness distribution. Similarly, these previous works have demonstrated that when 1.8 < beta < 2.5, the range of the burst luminosity function must be restricted and cannot be arbitrarily large. We present here analytic derivations of these results valid for any spatial density function and for both Euclidean and cosmological scenarios. This analysis shows that the limiting values of beta are simply the absolute values of the maximum and minimum logarithmic slopes of the observed brightness distribution. We demonstrate also that this result is consistent with those requiring a narrow range in luminosity for a majority of the detected bursts. C1 UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. MANKATO STATE UNIV,DEPT PHYS & ASTRON,MANKATO,MN 56002. RP Horack, JM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES-84,HUNTSVILLE,AL 35812, USA. RI Horack, John/J-6670-2016 NR 10 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 1996 VL 462 IS 1 BP 131 EP 135 DI 10.1086/177135 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UG298 UT WOS:A1996UG29800014 ER PT J AU Heiles, C Koo, BC Levenson, NA Reach, WT AF Heiles, C Koo, BC Levenson, NA Reach, WT TI Radio recombination lines from inner galaxy diffuse gas .1. High-sensitivity observations: He+/H+ and carbon SO ASTROPHYSICAL JOURNAL LA English DT Article DE H II regions; ISM, abundances; radio lines, ISM ID IONIZED INTERSTELLAR-MEDIUM; H-II REGIONS; MOLECULAR CLOUDS; STAR FORMATION; HII-REGION; HYDROGEN; EMISSION; PHOTOIONIZATION; TEMPERATURES; IONIZATION AB We have observed radio recombination lines (RRLs) at similar to 1.4 GHz toward the Galactic interior at hundreds of positions in a separately published survey. In some cases we observe not only the H alpha but also the H gamma, H delta, He alpha, and C alpha RRLs. We use previously published theory to estimate the enhancement in line intensity from non-LTE excitation, which amounts to similar to 30% for all of the alpha lines; however, the theory does not agree with our observed ratios of alpha to higher order line intensities. Intensity ratios of alpha lines of different elements should be unaffected by non-LTE excitation. The ratio (n(He+)/n(He))/(n(H+)/n(H)) less than or similar to 0.13 in the diffuse ionized medium of the Galactic interior. This is difficult to explain, because photons with energy greater than 24.6 eV must be systematically excluded from this gas. If O stars are the source of the ionizing photons, then this implies an upper mass limit on the initial mass function. However, with this upper mass limit, stars cannot produce enough ionizing photons to satisfy the total Galactic ionization requirement. One solution to this quandary is to invoke larger uncertainties in various processes than we estimate. Other solutions require an ionization source other than stars as currently understood, and we discuss two possibilities. We detect the C RRL toward several H II regions. The C RRLs are too strong to come from H ionized gas and must come instead from photodissociation regions. We compare the C RRL with the C+ 158 mu m line toward W43 and derive relatively unambiguous values for physical parameters in the associated photodissociation region. C1 SEOUL NATL UNIV, DEPT ASTRON, SEOUL 151742, SOUTH KOREA. NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, GREENBELT, MD 20771 USA. RP UNIV CALIF BERKELEY, DEPT ASTRON, 601 CAMPBELL HALL, BERKELEY, CA 94720 USA. OI Levenson, Nancy A./0000-0003-4209-639X; Reach, William/0000-0001-8362-4094 NR 62 TC 34 Z9 34 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 1996 VL 462 IS 1 BP 326 EP 338 DI 10.1086/177154 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UG298 UT WOS:A1996UG29800033 ER PT J AU Godon, P AF Godon, P TI Hot boundary layers in symbiotic binaries AX Persei and CI Cygni SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries, symbiotic; stars, individual (AX Persei, CI Cygni) ID ACCRETION AB Accretion disk boundary layer models are calculated for the symbiotic binaries AX Per and CI Cyg, using a time-dependent numerical code. Hot boundary layers are found with temperatures above 10(5) K, assuming for the accreting star a mass M* = 0.5 M. and a radius R* = 0.2 R.. However, choosing a larger stellar radius or a smaller stellar mass leads to cooler boundary layers. The numerical solutions agree fairly well with the observational estimates of the hot component temperature during quiescence but do not reproduce the apparent drop in effective temperature seen during the outburst of AX Per and CI Cyg. The maximum effective temperature obtained in the boundary layer solutions increases as the mass accretion rate increases (M = 1-10 x 10(-5) M. yr(-1)) but then stays nearly constant as the mass accretion rate approaches the Eddington limit (in the present case, M(Edd) approximate to 10(-4) M. yr(-1)). In this high accretion rate regime, the disk becomes geometrically thick (H/r approximate to 0.4), and the energy dissipated in the dynamical boundary layer is radiated outward to larger radii and advected into the star. The boundary layer luminosity is only approximate to 2/3 its expected value; the rest of the energy is advected into the star. RP Godon, P (reprint author), CALTECH,JET PROP LAB,NASA,4800 OAK GROVE DR,MS 238-332,PASADENA,CA 91109, USA. NR 23 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 1996 VL 462 IS 1 BP 456 EP 461 DI 10.1086/177164 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UG298 UT WOS:A1996UG29800043 ER PT J AU Billica, RD Simmons, SC Mathes, KL McKinley, BA Chuang, CC Wear, ML Hamm, PB AF Billica, RD Simmons, SC Mathes, KL McKinley, BA Chuang, CC Wear, ML Hamm, PB TI Perception of the medical risk of spaceflight SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID WINTER-OVER PERSONNEL; AVIATION; HEALTH; PILOTS; NAVY AB We conducted an opinion survey to improve the characterization of medical risk during spaceflight, using a questionnaire designed to elicit space medicine experts' perceptions of the probability, health effect, and mission impact of selected medical events occurring during spaceflight missions of 30-90 d. This questionnaire was directed toward those events about which little data currently exist, therefore medical events that have occurred during spaceflights with some frequency, such as space motion sickness, were excluded from the questionnaire. The questionnaire was mailed to 99 clinical and research professionals involved with NASA medical programs; 65 responses were returned, of which 60 could be analyzed. The experts rated skin disorders as the most likely to occur, but which would have little effect on mission completion or astronaut health. Circulatory diseases were rated as having the lowest probability of occurrence, but the highest effect on the mission or on a crewmember's health. The results of this survey will be combined with data from analogous populations and existing astronaut health data to establish a data set to support decisions about allocation of health care resources. C1 KRUG LIFE SCI INC,HOUSTON,TX. UNIV TEXAS,SCH MED,DEPT ANESTHESIOL,HOUSTON,TX. RP Billica, RD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,MAIL CODE SD2,201 NASA RD 1,HOUSTON,TX 77058, USA. NR 26 TC 28 Z9 28 U1 1 U2 3 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD MAY PY 1996 VL 67 IS 5 BP 467 EP 473 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA UH185 UT WOS:A1996UH18500011 PM 8725475 ER PT J AU Kaiser, MK AF Kaiser, MK TI High-power graphic computers for visual simulation: A real-time-rendering revolution SO BEHAVIOR RESEARCH METHODS INSTRUMENTS & COMPUTERS LA English DT Article; Proceedings Paper CT 25th Annual Meeting of the Society-for-Computers-in-Psychology on the Internet - How It Can be Used in Psychological Research and in Making the Teaching of Psychology More Effective and Efficient CY NOV 09, 1995 CL LOS ANGELES, CA SP Soc Comp Psychol ID MOTION AB Advances in high-end graphics computers in the past decade have made it possible to render visual scenes of incredible complexity and realism in realtime. These new capabilities make it possible to manipulate and investigate the interactions of observers with their visual world in ways once only dreamed of. This paper reviews how these developments have affected two preexisting domains of behavioral research (flight simulation and motion perception) and have created a new domain (virtual environment research) which provides tools and challenges for the perceptual psychologist. Finally, the current limitations of these technologies are considered, with an eye toward how perceptual psychologists might shape future developments. RP Kaiser, MK (reprint author), NASA,AMES RES CTR,MAIL STOP 262-2,MOFFETT FIELD,CA 94035, USA. NR 13 TC 3 Z9 3 U1 0 U2 0 PU PSYCHONOMIC SOC INC PI AUSTIN PA 1710 FORTVIEW RD, AUSTIN, TX 78704 SN 0743-3808 J9 BEHAV RES METH INSTR JI Behav. Res. Methods Instr. Comput. PD MAY PY 1996 VL 28 IS 2 BP 233 EP 238 DI 10.3758/BF03204772 PG 6 WC Psychology, Mathematical; Psychology, Experimental SC Psychology GA UN621 UT WOS:A1996UN62100022 PM 11540137 ER PT J AU Mulligan, JB AF Mulligan, JB TI When are supercomputers worth the bother? SO BEHAVIOR RESEARCH METHODS INSTRUMENTS & COMPUTERS LA English DT Article; Proceedings Paper CT 25th Annual Meeting of the Society-for-Computers-in-Psychology on the Internet - How It Can be Used in Psychological Research and in Making the Teaching of Psychology More Effective and Efficient CY NOV 09, 1995 CL LOS ANGELES, CA SP Soc Comp Psychol AB The availability of the UNIX operating system on large supercomputers has greatly simplified the importation of research software from workstations and minicomputers. Supercomputers generally offer much greater memory and storage than do smaller machines, which may make their use mandatory for some large applications. Realization of the full performance offered by vectorizing supercomputers such as the Cray C90 sometimes requires modification of existing code. The use of high-level interpreters for the development of applications is recommended, to minimize the amount of compiled code that must be optimized. RP Mulligan, JB (reprint author), NASA,AMES RES CTR,MS 262-2,MOFFETT FIELD,CA 94035, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU PSYCHONOMIC SOC INC PI AUSTIN PA 1710 FORTVIEW RD, AUSTIN, TX 78704 SN 0743-3808 J9 BEHAV RES METH INSTR JI Behav. Res. Methods Instr. Comput. PD MAY PY 1996 VL 28 IS 2 BP 239 EP 240 DI 10.3758/BF03204773 PG 2 WC Psychology, Mathematical; Psychology, Experimental SC Psychology GA UN621 UT WOS:A1996UN62100023 ER PT J AU DeMartini, EE Parrish, FA Parrish, JD AF DeMartini, EE Parrish, FA Parrish, JD TI Interdecadal change in reef fish populations at French Frigate Shoals and Midway Atoll, northwestern Hawaiian Islands: Statistical power in retrospect SO BULLETIN OF MARINE SCIENCE LA English DT Article ID SPATIAL VARIATION; RECRUITMENT; ASSEMBLAGES; ABUNDANCE; PATTERNS AB Reef fish faunas were compared between surveys conducted more than a decade apart at each of two isolated and nearly pristine oceanic atolls (French Frigate Shoals [FFS] and Midway Atoll) in the northwestern Hawaiian Islands. Species composition, assemblage structure (density rankings), and population densities were compared to test the hypothesis that reef fishes had declined during a period of lower oceanic productivity in the central North Pacific. Within each of two principal habitats (barrier and patch reefs) at each atoll, species composition and rank densities differed little between sampling periods. Densities, however, generally declined by about one-third for many numerically dominant species and for tars pooled into functional categories (trophic levels, feeding guilds). Patterns of temporal change were partly confounded by distributional shifts between barrier and patch reef habitats at FFS, perhaps reflecting indirect effects of storm disturbance on benthic algal habitat. Such effects, together with related changes in climate and oceanic productivity on an interdecadal time scale, might have been responsible for the apparent declines in reef fish densities al both atolls. Temporal patterns were clearer at Midway Atoll, where changes in benthic algae were not evident. Our observations indicate that the statistical power necessary to detect changes in the population densities of reef fish species that exhibit large temporal fluctuations in numbers, particularly on oceanic islands, is generally low. Power to detect twofold changes may be adequate, however, if taxa are pooled into functional categories. C1 UNIV HAWAII, HAWAII COOPERAT FISHERY RES UNIT, NATL BIOL SERV, HONOLULU, HI 96822 USA. RP NOAA, NATL MARINE FISHERIES SERV, SW FISHERIES SCI CTR, HONOLULU LAB, 2570 DOLE ST, HONOLULU, HI 96822 USA. NR 49 TC 17 Z9 18 U1 0 U2 5 PU ROSENSTIEL SCH MAR ATMOS SCI PI MIAMI PA 4600 RICKENBACKER CAUSEWAY, MIAMI, FL 33149 USA SN 0007-4977 EI 1553-6955 J9 B MAR SCI JI Bull. Mar. Sci. PD MAY PY 1996 VL 58 IS 3 BP 804 EP 825 PG 22 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA UP205 UT WOS:A1996UP20500015 ER PT J AU DeMartini, EE AF DeMartini, EE TI Sheltering and foraging substrate uses of the arc-eye hawkfish Paracirrhites arcatus (Pisces: Cirrhitidae) SO BULLETIN OF MARINE SCIENCE LA English DT Article ID HABITAT SELECTION; PREDATION RISK; CORAL REEFS; MINNOWS; PATTERNS; HAWAII; FISHES AB A combination of free-ranging snorkel surveys and focal-animal observations was used to evaluate substrate use by the arc-eye hawkfish Paracirrhites arcatus, a typical cirrhitid recognized for its conspicuous ''perching'' and ambushing behavior, The arc-eye hawkfish used different substrates for sheltering and for foraging. Pocillopora meandrina, the only common species of closely branched coral in the main Hawaiian Islands, was the perch most frequently encountered (>96% of all cases) on snorkel surveys at seven sites on the leeward side of the Island of Hawaii. P. arcatus refuged within Poc, meandrina whenever predators approached closely, but darted out from coral heads to feed. Foraging strikes were directed mainly at targets on benthic substrates surrounding Poc. meandrina refuges; strikes were primarily directed (81-96% of all strikes) at prey on rock/dead coral substrate that dominated cover (43-90%) at the study sites. P. arcatus also fed to a major extent within the near-bottom water column. The dichotomy between preferred foraging and sheltering substrates is discussed relative to the trade-off between foraging benefit and risk of predation hazard when the two substrates differ. RP DeMartini, EE (reprint author), NOAA, NATL MARINE FISHERIES SERV, SW FISHERIES SCI CTR, HONOLULU LAB, 2570 DOLE ST, HONOLULU, HI 96822 USA. NR 30 TC 8 Z9 9 U1 1 U2 6 PU ROSENSTIEL SCH MAR ATMOS SCI PI MIAMI PA 4600 RICKENBACKER CAUSEWAY, MIAMI, FL 33149 USA SN 0007-4977 J9 B MAR SCI JI Bull. Mar. Sci. PD MAY PY 1996 VL 58 IS 3 BP 826 EP 837 PG 12 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA UP205 UT WOS:A1996UP20500016 ER PT J AU Wielicki, BA Barkstrom, BR Harrison, EF Lee, RB Smith, GL Cooper, JE AF Wielicki, BA Barkstrom, BR Harrison, EF Lee, RB Smith, GL Cooper, JE TI Clouds and the earth's radiant energy system (CERES): An earth observing system experiment SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID RADIATION BUDGET EXPERIMENT; GENERAL-CIRCULATION MODEL; SOLAR-RADIATION; SATELLITE MEASUREMENTS; INFRARED RADIANCES; SEASONAL-VARIATION; EXPERIMENT ERBE; SURFACE; SCANNER; FIELDS AB Clouds and the Earth's Radiant Energy System (CERES) is an investigation to examine the role of cloud/radiation feedback in the Earth's climate system. The CERES broadband scanning radiometers are an improved version of the Earth Radiation Budget Experiment (ERBE) radiometers. The CERES instruments will fly on several National Aeronautics and Space Administration Earth Observing System (EOS) satellites starting in 1998 and extending over at least 15 years. The CERES science investigations will provide data to extend the ERBE climate record of top-of-atmosphere shortwave (SW) and longwave (LW) radiative fluxes. CERES will also combine simultaneous cloud property data derived using EOS narrowband imagers to provide a consistent set of cloud/radiation data, including SW and LW radiative fluxes at the surface and at several selected levels within the atmosphere. CERES data are expected to provide top-of-atmosphere radiative fluxes with a factor of 2 to 3 less error than the ERBE data. Estimates of radiative fluxes at the surface and especially within the atmosphere will be a much greater challenge but should also show significant improvements over current capabilities. RP NASA, LANGLEY RES CTR, RADIAT SCI BRANCH, DEPT ATMOSPHER SCI, MAIL STOP 420, HAMPTON, VA 23681 USA. NR 58 TC 917 Z9 924 U1 4 U2 48 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0003-0007 EI 1520-0477 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD MAY PY 1996 VL 77 IS 5 BP 853 EP 868 DI 10.1175/1520-0477(1996)077<0853:CATERE>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN464 UT WOS:A1996UN46400001 ER PT J AU Atlas, R Hoffman, RN Bloom, SC Jusem, JC Ardizzone, J AF Atlas, R Hoffman, RN Bloom, SC Jusem, JC Ardizzone, J TI A multiyear global surface wind velocity dataset using SSM/I wind observations SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID DIRECT MINIMIZATION; AMBIGUITY REMOVAL; SEASAT AB The Special Sensor Microwave Imagers (SSM/I) aboard three DMSP satellites have provided a large dataset of surface wind speeds over the global oceans from July 1987 to the present. These data are characterized by high resolution, coverage, and accuracy, but their application has been limited by the lack of directional information. In an effort to extend the applicability of these data, methodology has been developed to assign directions to the SSM/I wind speeds and to produce analyses using these data. Following extensive testing, this methodology has been used to generate a seven and one-half year dataset (from July 1987 through December 1994) of global SSM/I wind vectors. These data are currently being used in a variety of atmospheric and oceanic applications and are available to interested investigators. Recent results presented in this paper show the accuracy of the SSM/I wind velocities, the ability of these data to improve surface wind analyses, and the propagation of a synoptic-scale convergent vol tex in the Tropics that can be tracked from year to year in annual mean SSM/I wind fields. C1 ATMOSPHER & ENVIRONM RES INC,CAMBRIDGE,MA 02139. GEN SCI CORP,GODDARD SPACE FLIGHT CTR,GREENBELT,MD. RP Atlas, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,DATA ASSIMILAT OFF,CODE 9104,GREENBELT,MD 20771, USA. RI Atlas, Robert/A-5963-2011 OI Atlas, Robert/0000-0002-0706-3560 NR 23 TC 144 Z9 147 U1 3 U2 9 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD MAY PY 1996 VL 77 IS 5 BP 869 EP 882 DI 10.1175/1520-0477(1996)077<0869:AMGSWV>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN464 UT WOS:A1996UN46400002 ER PT J AU Chao, BF Han, YB Gross, RS AF Chao, BF Han, YB Gross, RS TI On seismic excitation of the polar motion SO CHINESE SCIENCE BULLETIN LA English DT Article DE earthquake; polar motion; earth rotation RP Chao, BF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Chao, Benjamin Fong/N-6156-2013 NR 7 TC 0 Z9 0 U1 0 U2 0 PU SCIENCE CHINA PRESS PI BEIJING PA 16 DONGHUANGCHENGGEN NORTH ST, BEIJING 100717, PEOPLES R CHINA SN 1001-6538 J9 CHINESE SCI BULL JI Chin. Sci. Bull. PD MAY PY 1996 VL 41 IS 10 BP 832 EP 836 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA VA153 UT WOS:A1996VA15300008 ER PT J AU Wade, CE Dubick, MA Vassar, MJ Perry, CA Holcroft, JW AF Wade, CE Dubick, MA Vassar, MJ Perry, CA Holcroft, JW TI Plasma dextran concentrations in trauma patients administered hypertonic saline-dextran-70 SO CLINICAL CHEMISTRY LA English DT Letter ID 7.5-PERCENT NACL/6-PERCENT DEXTRAN-70; SMALL-VOLUME RESUSCITATION; HYPOTENSION; INFUSION; TRIAL; NACL C1 USA,INST SURG RES,MECH TRAUMA RES BRANCH,FT SAM HOUSTON,TX 78234. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV CALIF DAVIS,DEPT SURG,DAVIS,CA 95616. NR 20 TC 5 Z9 5 U1 0 U2 2 PU AMER ASSOC CLINICAL CHEMISTRY PI WASHINGTON PA 2101 L STREET NW, SUITE 202, WASHINGTON, DC 20037-1526 SN 0009-9147 J9 CLIN CHEM JI Clin. Chem. PD MAY PY 1996 VL 42 IS 5 BP 779 EP 780 PG 2 WC Medical Laboratory Technology SC Medical Laboratory Technology GA UJ253 UT WOS:A1996UJ25300028 PM 8653912 ER PT J AU Bryson, S AF Bryson, S TI Virtual Reality in scientific visualization SO COMMUNICATIONS OF THE ACM LA English DT Article C1 MRJ INC,OAKTON,VA. RP Bryson, S (reprint author), NASA,AMES RES CTR,MS T27A-1,MOFFETT FIELD,CA 94035, USA. NR 19 TC 54 Z9 54 U1 0 U2 6 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 SN 0001-0782 J9 COMMUN ACM JI Commun. ACM PD MAY PY 1996 VL 39 IS 5 BP 62 EP 71 DI 10.1145/229459.229467 PG 10 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA UG872 UT WOS:A1996UG87200013 ER PT J AU Mathews, GJ Jacobs, BE AF Mathews, GJ Jacobs, BE TI Electronic management of the peer review process SO COMPUTER NETWORKS AND ISDN SYSTEMS LA English DT Article; Proceedings Paper CT 5th International World Wide Web Conference (WWW5) CY MAY 06-10, 1996 CL PARIS, FRANCE SP INRIA, European Commiss, ERCIM, W3C DE peer review; electronic management system; CGI; oracle; database; SQL AB This paper deals with managing the peer review process with an electronic management system (EMS). Our approach uses a WWW-based interface to an Oracle database. We describe different aspects of the EMS, namely the peer review process, report generation, and security. An experimental peer review system was developed for the Fourth International World Wide Web (WWW) Conference, which provided a model to automate the underlying processes that had been driven primarily by pen and paper. This system uses the very technology that the international WWW Conference Committee (IW3C2) promotes, so it is fitting that the conference be automated with a WWW-based system. The experimental system has evolved with the help of many suggestions to provide better support for the WWW5 conference as well. This paper discusses the first experimental system, some lessons learned, and the second more evolved system for the WWW5 conference with emphasis on the latter. RP Mathews, GJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 11 TC 4 Z9 4 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-7552 J9 COMPUT NETWORKS ISDN JI Comput. Netw. ISDN Syst. PD MAY PY 1996 VL 28 IS 7-11 BP 1523 EP 1538 PG 16 WC Computer Science, Information Systems; Engineering, Electrical & Electronic; Telecommunications SC Computer Science; Engineering; Telecommunications GA UQ960 UT WOS:A1996UQ96000058 ER PT J AU Gobbetti, E Leone, AO AF Gobbetti, E Leone, AO TI Virtual Sardinia: A large-scale hypermedia regional information system SO COMPUTER NETWORKS AND ISDN SYSTEMS LA English DT Article; Proceedings Paper CT 5th International World Wide Web Conference (WWW5) CY MAY 06-10, 1996 CL PARIS, FRANCE SP INRIA, European Commiss, ERCIM, W3C DE hypermedia; 3D visualization; VRML; WWW browser; view-and-markup tools AB The Virtual Sardinia project aims at collecting a large amount of heterogeneous data concerning the island of Sardinia and representing them in such a way that a casual user can easily navigate through them in a virtual trip. All these data are interconnected in an hypermedia way, browsable in the World-wide Web, ranging from geographic to archaeological data, from historical to touristical information, both in 2D and 3D. One of the central components of Virtual Sardinia is i3D, a high-speed 3D scene viewer for the World-wide Web. Using a Spaceball, the user can intuitively navigate with continuous viewpoint control inside three-dimensional data, while selecting 3D objects with the mouse triggers requests for access to remote media documents that can be distributed over the Internet. This allows to explore interactively a three-dimensional reconstruction of the island of Sardinia built from a digital terrain model texture-mapped with satellite images. Alternate interactive views of the model are provided in the form of movies, sequences, or clickable maps. The combination of these models becomes a natural front-end for querying all kinds of scientific, cultural, and touristic information about Sardinia. We believe that this approach opens a new way to create regional information systems easily available that could be made available to the general public. C1 UNIV MARYLAND,CSEE DEPT,BALTIMORE,MD 21201. NASA,GODDARD SPACE FLIGHT CTR,DESDIS,GREENBELT,MD 20771. CTR ADV STUDIES,CRS4,CAGLIARI,ITALY. OI Gobbetti, Enrico/0000-0003-0831-2458 NR 8 TC 1 Z9 1 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-7552 J9 COMPUT NETWORKS ISDN JI Comput. Netw. ISDN Syst. PD MAY PY 1996 VL 28 IS 7-11 BP 1539 EP 1546 PG 8 WC Computer Science, Information Systems; Engineering, Electrical & Electronic; Telecommunications SC Computer Science; Engineering; Telecommunications GA UQ960 UT WOS:A1996UQ96000059 ER PT J AU Wang, JT Raju, IS AF Wang, JT Raju, IS TI Strain energy release rate formulae for skin-stiffener debond modeled with plate elements SO ENGINEERING FRACTURE MECHANICS LA English DT Article ID PANELS AB An efficient method for predicting the strength of debonded composite skin-stiffener configurations is presented. This method, which is based on fracture mechanics, models the skin and stiffener with two-dimensional (2D) plate elements instead of three-dimensional (3D) solid elements. The skin and stiffener flange nodes are tied together by two modeling techniques. In one technique, the corresponding flange and skin nodes are required to have identical translational and rotational degrees-of-freedom. In the other technique, the corresponding flange and skin nodes are only required to have identical translational degrees-of-freedom. Strain energy release rate formulae are proposed for both modeling techniques. These formulae are used for skin-stiffener debond cases with and without cylindrical bending deformations. The cylindrical bending results are compared with plane-strain finite element results. Excellent agreement between the two sets of results is obtained when the second technique is used. Thus, from these limited studies, a preferable modeling technique for skin-stiffener debond analysis using plate elements is established. C1 ANALYT SERV & MAT INC,HAMPTON,VA 23666. RP Wang, JT (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT MECH,HAMPTON,VA 23665, USA. NR 20 TC 37 Z9 38 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0013-7944 J9 ENG FRACT MECH JI Eng. Fract. Mech. PD MAY PY 1996 VL 54 IS 2 BP 211 EP 228 DI 10.1016/0013-7944(95)00088-7 PG 18 WC Mechanics SC Mechanics GA UK426 UT WOS:A1996UK42600004 ER PT J AU Mercer, CR Rashidnia, N Creath, K AF Mercer, CR Rashidnia, N Creath, K TI High data density temperature measurement for quasi steady-state flows SO EXPERIMENTS IN FLUIDS LA English DT Article ID POINT-DIFFRACTION INTERFEROMETER AB A new optical instrument, the liquid crystal point diffraction interferometer (LCPDI), is used to measure the temperature distribution across a heated chamber filled with silicone oil. Data taken using the LCPDI are compared to equivalent measurements made with a traversing thermocouple and the two data sets show excellent agreement. This instrument maintains the compact, robust design of Linnik's point diffraction interferometer and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wavefronts with very high data density and with automated data reduction. C1 NYMA INC,NASA LERC,CLEVELAND,OH 44135. UNIV ARIZONA,CTR OPT SCI,TUCSON,AZ 85721. RP Mercer, CR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 16 TC 6 Z9 6 U1 0 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0723-4864 J9 EXP FLUIDS JI Exp. Fluids PD MAY PY 1996 VL 21 IS 1 BP 11 EP 16 PG 6 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA UP680 UT WOS:A1996UP68000002 ER PT J AU Barut, A Madenci, E Tessler, A AF Barut, A Madenci, E Tessler, A TI Nonlinear elastic deformations of moderately thick laminated shells subjected to large and rapid rigid-body motion SO FINITE ELEMENTS IN ANALYSIS AND DESIGN LA English DT Article ID LARGE DISPLACEMENT ANALYSIS; DYNAMIC ANALYSIS; ELEMENT; FORMULATION; PLATES AB This study presents a transient nonlinear finite element analysis within the realm of a multi-body dynamics formulation for determining the dynamic response of a moderately thick laminated shell undergoing a rapid and large rotational motion and nonlinear elastic deformations. Nonlinear strain measure and rotation, as well as the transverse shear deformation, are explicitly included in the formulation in order to capture the proper motion-induced stiffness of the laminate. The equations of motion are derived from the virtual work principle. The analysis utilizes shear deformable shallow shell element along with the co-rotational form of the updated Lagrangian formulation. The shallow shell element formulation is based on the Reissner-Mindlin and Marguerre theory. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP Barut, A (reprint author), UNIV ARIZONA,DEPT AEROSP & MECH ENGN,TUCSON,AZ 85721, USA. RI Tessler, Alexander/A-4729-2009 NR 15 TC 5 Z9 5 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-874X J9 FINITE ELEM ANAL DES JI Finite Elem. Anal. Des. PD MAY PY 1996 VL 22 IS 1 BP 41 EP 57 DI 10.1016/0168-874X(95)00063-Y PG 17 WC Mathematics, Applied; Mechanics SC Mathematics; Mechanics GA UN406 UT WOS:A1996UN40600005 ER PT J AU Lee, J Miller, MM Crippen, R Hacker, B Vazquez, JL AF Lee, J Miller, MM Crippen, R Hacker, B Vazquez, JL TI Middle Miocene extension in the Gulf extensional province, Baja California: Evidence from the southern Sierra Juarez SO GEOLOGICAL SOCIETY OF AMERICA BULLETIN LA English DT Article ID LATE CENOZOIC EXTENSION; PLATE MOTIONS; UNITED-STATES; NORTH-AMERICA; PACIFIC PLATE; MEXICO; EVOLUTION; BASIN; RANGE; DEFORMATION AB New geologic mapping, structural studies, and geochronology of Miocene volcanic and sedimentary rocks in the southern Sierra Juarez, Baja California, shed light on the extensional history of the Gulf Extensional Province prior to sea-floor spreading in the Gulf of California, The southern Sierra Juarez is underlain by lower-middle Miocene rocks including fluvial strata, intermediate composition volcanic deposits, basalt lava flows and cinder cones, and dacite pyroclastic deposits and lavas that non-conformably overlie the Cretaceous Peninsular Ranges batholith, The Ar-40/Ar-39 geochronology indicates that basaltic rocks are 16.90 +/- 0.05 Ma and dacite pyroclastic deposits are between 16.69 +/- 0.11 Ma and 15.98 +/- 0.13 Ma. These strata were subsequently cut by two generations of faults, First generation faults comprise a dominant set of north-south-striking, west-dipping normal faults, a secondary set of north-south-striking, east-dipping normal faults, and a lesser set of variably oriented strike-slip faults, All three fault sets are temporally and spatially related and were produced by east-west extension, The dominant west-dipping faults, which are antithetic to and oblique to the east-dipping Main Gulf Escarpment, may have been a precursor or an early phase accommodation zone along the escarpment, West-dipping normal faults are cut by a 10.96 +/- 0.05 Ma dacite hypabyssal intrusion, thus bracketing the age of east-west extension between 15.98 +/- 0.13 Ma and 10.96 +/- 0.05 Ma, Hence, this faulting event clearly indicates a period of extension that predates the onset of oceanic rifting and even predates other dated Miocene extension within Baja California. Second generation faults, which are comprised of east-west-striking strike-slip faults that cut first generation faults and associated northwest-striking, northeast-dipping normal faults, may be related to early development of the Transpeninsular Strike-slip Province. Global plate reconstructions suggest that transtensional motion between the North American and Pacific plates along the western margin of Baja California began during middle Miocene time, coeval with east-west extension in the southern Sierra Juarez. This observation supports a hypothesis that middle Miocene transtensional plate motion was partitioned into two components: a strike-slip component parallel to active faults along the western offshore margin of Baja California, and an extensional component normal to the margin, but located in what is now the Gulf Extensional Province, Hence, the onset of extension within the circum-gulf region was in response to plate boundary processes. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. STANFORD UNIV,DEPT GEOL,STANFORD,CA 93405. UNIV AUTONOMA BAJA CALIF,FAC CIENCIAS MARINAS,ENSENADA 22800,BAJA CALIFORNIA,MEXICO. RP Lee, J (reprint author), CENT WASHINGTON UNIV,DEPT GEOL,ELLENSBURG,WA 98926, USA. RI Hacker, Bradley/E-7750-2011; OI Miller, M Meghan/0000-0002-7296-0639 NR 84 TC 49 Z9 50 U1 0 U2 4 PU GEOLOGICAL SOC AMERICA PI BOULDER PA PO BOX 9140 3300 PENROSE PLACE, BOULDER, CO 80301 SN 0016-7606 J9 GEOL SOC AM BULL JI Geol. Soc. Am. Bull. PD MAY PY 1996 VL 108 IS 5 BP 505 EP 525 DI 10.1130/0016-7606(1996)108<0505:MMEITG>2.3.CO;2 PG 21 WC Geosciences, Multidisciplinary SC Geology GA UK855 UT WOS:A1996UK85500001 ER PT J AU Siebe, C Abrams, M Macias, JL Obenholzner, J AF Siebe, C Abrams, M Macias, JL Obenholzner, J TI Repeated volcanic disasters in Prehispanic time at Popocatepetl, central Mexico: Past key to the future? SO GEOLOGY LA English DT Article ID SEDIMENTATION; TEPHRA; PLUMES AB The Holocene eruptive history of Popocatepetl volcano is characterized by recurrent voluminous Plinian eruptions every 1000 to 3000 yr, the most recent of which destroyed human settlements, Major eruptions occurred between 3195 and 2830 B.C., 800 and 215 B.C., and A.D. 675 and 1095. The three eruptions followed a similar pattern and started with minor ash fall and ash flows, The eruptions reached their peak with a main Plinian pulse that produced deposition of a pumice fall, the emplacement of hot ash flows, and finally extensive mudflows, Each time the area of devastation had become repopulated, before being devastated once again, During the last eruption several settlements, including Cholula (a major urban center), were inundated by lahars, A scenario of the possible recurrence of an eruption of similar magnitude, which would have disastrous consequences for the now highly populated areas around Popocatepetl, should be considered seriously in any volcano emergency contingency plan, This is especially important because more than one million people are living within a radius of 35 km around the volcano (the outskirts of Mexico City are at a distance of 40 km), and Popocatepetl resumed emitting ash on December 21, 1994, after decades of dormancy. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. MONTAN UNIV LEOBEN,INST GEOWISSENSCHAFTEN PROSPEKT,A-8700 LEOBEN,AUSTRIA. RP Siebe, C (reprint author), UNIV NACL AUTONOMA MEXICO,INST GEOFIS,CP 04510,MEXICO CITY 04510,DF,MEXICO. RI Macias, Jose Luis/P-7679-2015; OI Macias, Jose Luis/0000-0002-2494-9849; Siebe, Claus/0000-0002-3959-9028 NR 18 TC 116 Z9 120 U1 1 U2 10 PU GEOLOGICAL SOC AMERICA PI BOULDER PA PO BOX 9140 3300 PENROSE PLACE, BOULDER, CO 80301 SN 0091-7613 J9 GEOLOGY JI Geology PD MAY PY 1996 VL 24 IS 5 BP 399 EP 402 DI 10.1130/0091-7613(1996)024<0399:RVDIPT>2.3.CO;2 PG 4 WC Geology SC Geology GA UK827 UT WOS:A1996UK82700004 ER PT J AU Hide, R Boggs, DH Dickey, JO Dong, D Gross, RS Jackson, A AF Hide, R Boggs, DH Dickey, JO Dong, D Gross, RS Jackson, A TI Topographic core-mantle coupling and polar motion on decadal time-scales SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE core-mantle boundary; dynamics; Earth's core; Earth's interior; Earth's rotation; geomagnetism; planetary oblateness; topography ID GEOMAGNETIC SECULAR VARIATION; EARTHS ROTATION; GEOSTROPHIC FLOW; FORCED NUTATIONS; OUTER-CORE; BOUNDARY; SURFACE; TORQUE; INTERFEROMETRY; FLUCTUATIONS AB Associated with non-steady magnetohydrodynamic (MHD) flow in the liquid metallic core of the Earth, with typical relative speeds of a fraction of a millimetre per second, are fluctuations in dynamic pressure of about 10(3) N m(-2). Acting on the non-spherical core-mantle boundary (CMB), these pressure fluctuations give rise to a fluctuating net topographic torque L(i)(t) (i=1, 2, 3)-where t denotes time-on the overlying solid mantle. Geophysicists now accept the proposal by one of us (RH) that L(i)(t) makes a significant and possibly dominant contribution to the total torque L(i)*(t) on the mantle produced directly or indirectly by core motions. Other contributions are the 'gravitational' torque associated with fluctuating density gradients in the core, the 'electromagnetic' torque associated with Lorentz forces in the weakly electrically conducting lower mantle, and the 'viscous' torque associated with shearing motions in the boundary layer just below the CMB. The axial component L(3)*(t) of L(i)*(t) contributes to the observed fluctuations in the length of the day [LOD, an inverse measure of the angular speed of rotation of the solid Earth (mantle, crust and cryosphere)], and the equatorial components (L(1)*(t)=L*(t)) contribute to the observed polar motion, as determined from measurements of changes in the Earth's rotation axis relative to its figure axis. In earlier phases of a continuing programme of research based on a method for determining L(i)(t) from geophysical data (proposed independently about ten years ago by Hide and Le Mouel), it was shown that longitude-dependent irregular CMB topography no higher than about 0.5 km could give rise to values of L(3)(t) sufficient to account for the observed magnitude of LOD fluctuations on decadal time-scales. Here, we report an investigation of the equatorial components (L(1)(t), L(2)(t))=L(t) of L(i)(t) taking into account just one topographic feature of the CMB-albeit possibly the most pronounced-namely the axisymmetric equatorial bulge, with an equatorial radius exceeding the polar radius by 9.5+/-0.1 km (the mean radius of the core being 3485+/-2 km, 0.547 times that of the whole Earth). A measure of the local horizontal gradient of the fluctuating pressure field near the CMB can be obtained from the local Eulerian flow velocity in the 'free stream' below the CMB by supposing that nearly everywhere in the outer reaches of the core-the 'polosphere' (Hide 1995)-geostrophic balance obtains between the pressure gradient and Coriolis forces. The polospheric velocity fields used were those determined by Jackson (1989) from geomagnetic secular variations (GSV) data on the basis of the geostrophic approximation combined with the assumption that, on the time-scales of the GSV, the core behaves like a perfect electrical conductor and the mantle as a perfect insulator. In general agreement with independent calculations by Hulot, Le Huy & Le Mouel (1996) and Greff-Lefftz & Legros (1995), we found that in magnitude L(t) for epochs from 1840 to 1990 typically exceeds \L(3)(t)\ by a factor of about 10, roughly equal to the ratio of the height of the equatorial bulge to that strongly implied for irregular topography by determinations of L(3)(t) (see Hide et al. 1993). But L(t) still apparently falls short in magnitude by a factor of up to about 5 in its ability to account for the amplitude of the observed time-series of polar motion on decadal time-scales (DPM), and it is poorly correlated with that time-series. So we conclude that unless uncertainties in the determination of the DPM time-series from observations-which we also discuss-have been seriously underestimated, the action of normal pressure forces associated with core motions on the equatorial bulge of the core-mantle boundary makes a significant but not dominant contribution to the excitation of decadal polar motion. Other geophysical processes such as the movement of groundwater and changes in sea-level must also be involved. C1 UNIV OXFORD, CLARENDON LAB, DEPT PHYS ATMOSPHER OCEAN & PLANETARY PHYS, OXFORD OX1 3PU, ENGLAND. UNIV LEEDS, SCH EARTH SCI, LEEDS LS9 NJT, W YORKSHIRE, ENGLAND. RP CALTECH, JET PROP LAB, SPACE GEODET SCI & APPLICAT GRP, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 53 TC 21 Z9 21 U1 1 U2 3 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0956-540X EI 1365-246X J9 GEOPHYS J INT JI Geophys. J. Int. PD MAY PY 1996 VL 125 IS 2 BP 599 EP 607 DI 10.1111/j.1365-246X.1996.tb00022.x PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UH536 UT WOS:A1996UH53600022 ER PT J AU Argus, DF AF Argus, DF TI Postglacial rebound from VLBI geodesy: On establishing vertical reference SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MODEL AB Difficulty in establishing a reference frame fixed to the earth's interior complicates the measurement of the vertical (radial) motions of the surface. I propose that a useful reference frame for vertical motions is that found by minimizing differences between vertical motions observed with VLBI [Ma and Ryan, 1995] and predictions from postglacial rebound predictions [Peltier, 1995]. The optimal translation of the geocenter is 1.7 mm/yr toward 36 degrees N, 111 degrees E when determined from the motions of 10 VLBI sites. This translation gives a better fit of observations to predictions than does the VLBI reference frame used by Ma and Ryan [1995], but the improvement is statistically insignificant. The root mean square of differences decreases 20% to 0.73 mm/yr and the correlation coefficient increases from 0.76 to 0.87. Postglacial rebound is evident in the uplift of points in Sweden and Ontario that were beneath the ancient ice sheets of Fennoscandia and Canada, and in the subsidence of points in the northeastern U.S., Germany, and Alaska that were around the periphery of the ancient ice sheets. RP Argus, DF (reprint author), CALTECH,JET PROP LAB,MAIL STOP 238-600,PASADENA,CA 91109, USA. RI Argus, Donald/F-7704-2011 NR 14 TC 24 Z9 24 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 1996 VL 23 IS 9 BP 973 EP 976 DI 10.1029/96GL00735 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UK814 UT WOS:A1996UK81400018 ER PT J AU Rignot, E AF Rignot, E TI Dual-frequency interferometric SAR observations of a tropical rain-forest SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Repeat-pass, interferometric, radar observations of tropical rain-forest collected by the Shuttle Imaging Radar C (SIR-C) in the state of Rondonia, Brazil, reveal signal coherence is destroyed at C-band (5.6-cm) in the forest, whereas L-band (24-cm) radar signals remain strongly coherent over the entire landscape. At L-band, the rms difference in inferred topographic height between the forest and adjacent clearings is 5 m, equivalent to the height noise. Atmospheric delays are large, however, forming kilometer-sized anomalies with a 1.2-cm rms one way. Radar interferometric studies of the humid tropics must therefore be conducted at long radar wavelengths, with kilometric baselines or with two antennas operating simultaneously. RP Rignot, E (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MS 300-243,PASADENA,CA 91109, USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 11 TC 10 Z9 11 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 1996 VL 23 IS 9 BP 993 EP 996 DI 10.1029/96GL00456 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UK814 UT WOS:A1996UK81400023 ER PT J AU Inan, US Reising, SC Fishman, GJ Horack, JM AF Inan, US Reising, SC Fishman, GJ Horack, JM TI On the association of terrestrial gamma-ray bursts with lightning and implications for sprites SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Measurements of ELF/VLF radio atmospherics (sferics) at Palmer Station, Antarctica, provide evidence of active thunderstorms near the inferred source regions of two different gamma-ray bursts of terrestrial origin [Fishman et al., 1994]. In one case, a relatively intense sferic occurring within +/-1.5 ms of the time of the gamma-ray burst provides the first indication of a direct association of this burst with a lightning discharge. This sferic and many others launched by positive cloud-to-ground (CG) discharges and observed at Palmer during the periods studied exhibit 'slow tail' waveforms, indicative of continuing currents in the causative lightning discharges. The slow tails of these sferics are similar to those of sferics originating in positive CG discharges that are associated with sprites. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP Inan, US (reprint author), STANFORD UNIV,STAR LAB,STANFORD,CA 94305, USA. RI Horack, John/J-6670-2016 NR 18 TC 113 Z9 114 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 1996 VL 23 IS 9 BP 1017 EP 1020 DI 10.1029/96GL00746 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UK814 UT WOS:A1996UK81400029 ER PT J AU Rinsland, CP Connor, BJ Jones, NB Boyd, I Matthews, WA Goldman, A Murcray, FJ Murcray, DG David, SJ Pougatchev, NS AF Rinsland, CP Connor, BJ Jones, NB Boyd, I Matthews, WA Goldman, A Murcray, FJ Murcray, DG David, SJ Pougatchev, NS TI Comparison of infrared and dobson total ozone columns measured from Lauder, New Zealand SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ABSORPTION; MODEL AB Ozone total columns have been derived from 13 spectral intervals in 5 infrared bands and compared with values deduced from correlative measurements with a Dobson spectrophotometer. The observations were recorded on 10 days in 1994 at the Network for the Detection of Stratospheric Change station in Lauder, New Zealand. The infrared total columns were derived from spectral fittings of unblended, temperature-insensitive ozone lines in high resolution solar absorption spectra. The line parameters on the 1992 HITRAN compilation were assumed with the O-3 and H2O relative volume mixing ratio and temperature profiles specified from correlative balloon ozonesonde, microwave O-3, and radiosonde measurements. The retrieved IR/Dobson total column ratios ranged from 0.96 to 1.02 with the lower wavenumber bands yielding lower ratios. The results do not support the revised O-3 intensity scale currently used to process O-3 infrared measurements from 2 instruments on the Upper Atmosphere Research Satellite. C1 NIWA CLIMATE,LAUDER,NEW ZEALAND. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. CHRISTOPHER NEWPORT UNIV,NEWPORT NEWS,VA. RP Rinsland, CP (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,MAIL STOP 401A,HAMPTON,VA 23681, USA. RI Jones, Nicholas/G-5575-2011 OI Jones, Nicholas/0000-0002-0111-2368 NR 23 TC 11 Z9 11 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 1996 VL 23 IS 9 BP 1025 EP 1028 DI 10.1029/96GL00708 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UK814 UT WOS:A1996UK81400031 ER PT J AU Sprague, AL Bjoraker, GL Hunten, DM Witteborn, FC Kozlowski, RWH Wooden, DH AF Sprague, AL Bjoraker, GL Hunten, DM Witteborn, FC Kozlowski, RWH Wooden, DH TI Water brought into Jupiter's atmosphere by fragments R and W of Comet SL-9 SO ICARUS LA English DT Article ID D/H RATIO AB Measurements of H2O in the impact plumes of the a and W fragments of Comet SL-9 were made from the Kuiper Airborne Observatory, Water emissions peaked similar to 12 min after the impacts, and indicate a temperature similar to 1000 K based upon the relative radiances of two H2O emission features at 6.62 and 6.45 mu m. Our analysis shows that the water was probably delivered by Comet SL-9 and is not of jovian origin, and that the C/O ratio in the plume was less than unity. Our calculations, which allow for entrainment of jovian air and use a Halley-like composition far the impactor, show that the R fragment contained ice equivalent to a sphere 90 m in diameter, On the further assumption that we only saw 10% of the material, the diameter of the fragment would be 250 m. (C) 1996 Academic Press, Inc. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SUSQUEHANNA UNIV,DEPT PHYS,SELINSGROVE,PA 17870. RP Sprague, AL (reprint author), UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721, USA. NR 26 TC 12 Z9 12 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 1996 VL 121 IS 1 BP 30 EP 37 DI 10.1006/icar.1996.0069 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP055 UT WOS:A1996UP05500003 ER PT J AU Ostro, SJ Jurgens, RF Rosema, KD Hudson, RS Giorgini, JD Winkler, R Yeomans, DK Choate, D Rose, R Slade, MA Howard, SD Scheeres, DJ Mitchell, DL AF Ostro, SJ Jurgens, RF Rosema, KD Hudson, RS Giorgini, JD Winkler, R Yeomans, DK Choate, D Rose, R Slade, MA Howard, SD Scheeres, DJ Mitchell, DL TI Radar observations of Asteroid 1620 Geographos SO ICARUS LA English DT Article ID RADIOMETRY AB Goldstone radar observations of Geographos from August 28 through September 2, 1994 yield over 400 delay-Doppler images whose linear spatial resolutions range from similar to 75 to similar to 151 m, and 138 pairs of dual-polarization (OC, SC) spectra with one-dimensional resolution of 103 m. Each data type provides thorough rotational coverage, The images contain an intrinsic north/south ambiguity, but the equatorial view allows accurate determination of the shape of the radar-facing part of the asteroid's pole-on silhouette at any rotation phase. Sums of co-registered images that cover nearly a full rotation have defined the extremely elongated shape of that silhouette (S. J. Ostro, K. D. Rosema, R. S. Hudson, R. F. Jurgens, J. D. Giorgini, R. Winkler, D. K. Yeomans, D. Choate, R. Rose, M. A. Slade, S. D. Howard, and D. L. Mitchell 1995, Nature 375, 474-477), Here we present individual images and co-registered sums over similar to 30 degrees of rotation phase that show the silhouette's structural characteristics in finer detail and also reveal numerous contrast features ''inside'' the silhouette. Those features include several candidate craters as well as indications of other sorts of large-scale topographic relief, including a prominent central indentation. Protuberances at the asteroid's ends may be related to the pattern of ejecta removal and deposition caused by the asteroid's gravity held. The asteroid's surface is homogeneous and displays only modest roughness at centimeter-to-meter scales. Our estimates of radar cross section and the currently available constraints on the asteroid's dimensions are consistent with a near-surface bulk density between 2 and 3 g cm(-3). The delay-Doppler trajectory of Geographos' center af mass has been determined to about 200 m on August 28 and to about 100 m on August 31, an improvement of two orders of magnitude over pre-observation ephemerides. (C) 1996 Academic Press, Inc. C1 WASHINGTON STATE UNIV,SCH ELECT ENGN & COMP SCI,PULLMAN,WA 99164. RP Ostro, SJ (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 29 TC 36 Z9 37 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 1996 VL 121 IS 1 BP 46 EP 66 DI 10.1006/icar.1996.0071 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP055 UT WOS:A1996UP05500005 ER PT J AU Scheeres, DJ Ostro, SJ Hudson, RS Werner, RA AF Scheeres, DJ Ostro, SJ Hudson, RS Werner, RA TI Orbits close to asteroid 4769 Castalia SO ICARUS LA English DT Article ID SATELLITES AB We use a radar-derived physical model of 4769 Castalia (1989 PB) to investigate close orbit dynamics around that kilometer-sized, uniformly rotating asteroid. Our methods of analysis provide a basis for systematic studies of particle dynamics close to any uniformly rotating asteroid. We establish that a Jacobi integral exists for particles orbiting this asteroid, examine the attendant zero-velocity surfaces, find families of periodic orbits, and determine their stability. All synchronous orbits and direct orbits within similar to 3 mean radii of Castalia are unstable and are subject to impact or escape from Castalia, Retrograde orbits are mostly stable and allow particles to orbit close to the asteroid surface. We derive a model which allows us to predict the escape conditions of a particle in orbit about Castalia and the (temporary) capture conditions for a hyperbolic interloper, Orbits within 1.5 km of Castalia are subject to immediate ejection from the system. Hyperbolic orbits with a V-infinity < 0.4 m/sec can potentially be captured by Castalia if their periapsis radius is within similar to 2 km. For Castalia this capture region is small, but the results also apply to larger asteroids whose capture regions would also be larger. We determine bounds on ejecta speeds which either ensure ejecta escape or re-impact as functions of location on Castalia's surface, The speeds that ensure escape range from 0.28 to 0.84 m/sec and the speeds that ensure re-impact range from 0 to 0.18 m/sec, Speeds between these two bounds lead either to escape, re-impact, or potentially finite-time stable orbits, We develop a simple criterion which can establish whether a particle could have been ejected from the asteroid in the past and if it will impact the surface in the future. (C) 1996 Academic Press, Inc. C1 WASHINGTON STATE UNIV,PULLMAN,WA 99164. UNIV TEXAS,AUSTIN,TX 78712. RP Scheeres, DJ (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91125, USA. NR 26 TC 129 Z9 134 U1 0 U2 9 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 1996 VL 121 IS 1 BP 67 EP 87 DI 10.1006/icar.1996.0072 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP055 UT WOS:A1996UP05500006 ER PT J AU Hamilton, VE Stofan, ER AF Hamilton, VE Stofan, ER TI The geomorphology and evolution of Hecate Chasma, Venus SO ICARUS LA English DT Article ID LITHOSPHERIC HEAT-TRANSPORT; WESTERN EISTLA REGIO; BETA-REGIO; SPREADING CENTERS; MANTLE DYNAMICS; CORONAE; ORIGIN; MORPHOLOGY; VOLCANISM; GEOLOGY AB Hecate Chasma is a discontinuous trough and fracture system extending from Atla Regio through Asteria Regio. A detailed examination of Hecate Chasma using Magellan image and altimetry data reveals morphologic features such as normal faults (including graben), compressional ridges, a variety of volcanic edifices, and coronae, There is no evidence for a systematic age progression among coronae in chains, thus a single, stationary thermal anomaly underlying a moving lithosphere is an unlikely origin for the chains, A comparison of the observed features with two possible models of evolution, subduction/delamination or lithospheric extension with limited rifting, shows some similarities between the predicted morphologies of each model and Hecate Chasma, The dominance of features related to upwelling and extensional tectonism strongly favor an extensional origin for this zone. The corona chain may have been formed by upwellings related to Rayleigh-Taylor instabilities, similar to those observed at terrestrial mid-ocean ridges, but in an environment of limited spreading. (C) 1996 Academic Press, Inc. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Hamilton, VE (reprint author), ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287, USA. NR 55 TC 26 Z9 27 U1 1 U2 5 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 1996 VL 121 IS 1 BP 171 EP 194 DI 10.1006/icar.1996.0077 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UP055 UT WOS:A1996UP05500011 ER PT J AU Yao, XS Lutes, G AF Yao, XS Lutes, G TI A high-speed photonic clock and carrier recovery device SO IEEE PHOTONICS TECHNOLOGY LETTERS LA English DT Article ID LASER AB We present the experimental results of a high-speed clock and carrier recovery device based on a novel oscillator called a optoelectronic oscillator (OEO), Such a device can recover a clock signal or carrier with a frequency up to 75 GHz and can be interfaced with a photonic communication system both electronically and optically. RP Yao, XS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 9 TC 40 Z9 42 U1 0 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1041-1135 J9 IEEE PHOTONIC TECH L JI IEEE Photonics Technol. Lett. PD MAY PY 1996 VL 8 IS 5 BP 688 EP 690 DI 10.1109/68.491596 PG 3 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA UG686 UT WOS:A1996UG68600035 ER PT J AU Lee, HK Divsalar, D Weber, C AF Lee, HK Divsalar, D Weber, C TI Multiple symbol trellis coding of CPFSK SO IEEE TRANSACTIONS ON COMMUNICATIONS LA English DT Article ID CONTINUOUS PHASE MODULATION; BANDWIDTH AB This paper describes a technique related to the design of a trellis encoder, combined with the full response M-ary continuous phase frequency shift keying (CPFSK) with modulation index 1/M, A new representation of CPFSK waveforms in N signaling intervals, is proposed as a function of an (N + 1)-D vector, We also decompose the generation of the proposed CPFSK waveform into two stages, an N-consecutive continuous phase encoder (NCPE) and a memoryless modulator (MM). This decomposition makes it possible to design binary convolutional encoders with various code rates, cascaded to the NCPE, Specific optimal outer convolutional encoders of two and three-consecutive full response four-ary CPFSK with modulation index 1/4 are designed following Ungerboeck's set partitioning approach, These codes achieve asymptotic coding gains up to 4.77 dB for the two-consecutive case with code rate 3/4, and asymptotic coding gains up to 5.45 dB for the three-consecutive case with code rate 5/6. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. UNIV SO CALIF, DEPT ELECT ENGN, LOS ANGELES, CA 90089 USA. RP Lee, HK (reprint author), HONGIK UNIV, DEPT RADIO COMMUN SCI & ENGN, SEOUL 121791, SOUTH KOREA. NR 13 TC 11 Z9 11 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855 USA SN 0090-6778 J9 IEEE T COMMUN JI IEEE Trans. Commun. PD MAY PY 1996 VL 44 IS 5 BP 566 EP 574 DI 10.1109/26.494300 PG 9 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA UK818 UT WOS:A1996UK81800009 ER PT J AU Morrissey, LA Durden, SL Livingston, GP Stearn, JA Guild, LS AF Morrissey, LA Durden, SL Livingston, GP Stearn, JA Guild, LS TI Differentiating methane source areas in arctic environments with multitemporal ERS-1 SAR data SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID MICROWAVE SIGNATURES; BARE SOIL; RADAR; EMISSIONS; FOREST; INVERSION; WETLANDS; WATER; MODEL AB An assessment using ERS-1 SAR data to differentiate methane source (wetland) and nonsource (nonwetland) areas was undertaken based on radar backscatter modeling and empirical observations of 24 scenes collected over Barrow, AK, in 1991 and 1992. Differences in backscatter between source and nonsource areas were dependent on surface hydrology and air temperature, Differential freezing of surface materials on daily to seasonal time scales greatly enhanced the separability of wetlands and nonwetlands with ERS-1 SAR. Radar return for nonwetlands decreased dramatically whereas backscatter from wetlands decreased little when freezing air temperatures coincided with the SAR overpass. Maximum separability between wetlands and nonwetlands, as determined from observed and modeled radar backscatter, were the result of changes in the dielectric constant of the plant and surface materials with phase change during freezing. This study has indicated the need to consider air temperature at the time of acquisition in selecting ERS-1 SAR scenes for differentiating methane source and nonsource areas. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NASA,AMES RES CTR,JOHNSON CONTROLS WORLD SERV,MOFFETT FIELD,CA 94035. RP Morrissey, LA (reprint author), UNIV VERMONT,SCH NAT RESOURCES,BURLINGTON,VT 05405, USA. NR 30 TC 20 Z9 20 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 1996 VL 34 IS 3 BP 667 EP 673 DI 10.1109/36.499746 PG 7 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA UM314 UT WOS:A1996UM31400007 ER PT J AU Jasinski, MF AF Jasinski, MF TI Estimation of subpixel vegetation density of natural regions using satellite multispectral imagery SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID RED-INFRARED SCATTERGRAMS; REFLECTANCE; CANOPY; INDEX AB A procedure is presented for estimating the subpixel fractional canopy density of natural or undisturbed semivegetated regions on a pixel-by-pixel basis using one satellite multispectral image and a physical modeling approach. The method involves applying a model of the bulk, nondimensional plant geometry combined with a simple model of canopy reflectance and transmittance to the red and near-infrared reflectance space of the atmospherically corrected satellite image. Shadow effects are parameterized assuming Poisson-distributed and geometrically similar plant canopies. The method is applied to the estimation of fractional cover and leaf area index, using Landsat thematic mapper imagery, of two physiologically different plant communities. The first is the Landes Forest, a coniferous region in south central France, during the June 1985 HAPEX-Mobilhy Experiment. The second is the semiarid Walnut Gulch basin of southeast Arizona that contains predominantly shrubs and grasses, during the June 1990 MONSOON Experiment. The procedure offers a physically based alternative to empirical vegetation indices for estimating regionally variable canopy densities of natural, homogeneous systems with little or no ground truth. RP Jasinski, MF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 31 TC 40 Z9 44 U1 1 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 1996 VL 34 IS 3 BP 804 EP 813 DI 10.1109/36.499785 PG 10 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA UM314 UT WOS:A1996UM31400020 ER PT J AU Simons, RN Dib, NI Katehi, LPB AF Simons, RN Dib, NI Katehi, LPB TI Modeling of coplanar stripline discontinuities SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID WAVE AB The paper presents a technique to obtain lumped equivalent circuit models for typical coplanar stripline (CPS) discontinuities such as an open circuit, a short circuit, and a series gap in one of the strip conductors and gives their element values as a function of the discontinuity physical dimensions for a specific substrate. The model element values are determined from the discontinuity scattering parameters which are de-embedded from the measured scattering parameters using a thru-reflect-line (TRL) algorithm. In addition, the resonant frequency of a spur-slot is presented as a function of the spur length. The experimental results are validated by data obtained using the finite-difference time-domain (FDTD) technique. C1 UNIV MICHIGAN,DEPT COMP SCI & ELECT ENGN,RADIAT LAB 3240,ANN ARBOR,MI 48109. RP Simons, RN (reprint author), NASA,LEWIS RES CTR,NYMA GRP,CLEVELAND,OH 44135, USA. RI Dib, Nihad/M-4918-2015; OI Dib, Nihad/0000-0002-2263-5512 NR 17 TC 33 Z9 33 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD MAY PY 1996 VL 44 IS 5 BP 711 EP 716 DI 10.1109/22.493924 PG 6 WC Engineering, Electrical & Electronic SC Engineering GA UL099 UT WOS:A1996UL09900009 ER PT J AU Epp, LW Smith, RP AF Epp, LW Smith, RP TI A generalized scattering matrix approach for analysis of quasi-optical grids and de-embedding of device parameters SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID OSCILLATOR; AMPLIFIER AB A generalized scattering matrix approach to analyzing quasi-optical grids used for grid amplifiers and grid oscillators is developed. The approach is verified by a novel method for de-embedding, in a waveguide simulator, the active device parameters of a differential pair high electron mobility transistor (HEMT) from the single unit cell of a grid amplifier. The method incorporates the additional ports presented to the active device into a method of moments solution of the embedding periodic array. The port(s) defined at the device or load location are within the plane of the array, and not terminated in a microstrip line with a known characteristic impedance. Therefore the generalized scattering matrix for the embedding array is normalized to the calculated input impedance(s) at these port(s). The approach described here uses a Floquet representation of the fields incident and reflected from the grid as the remaining ports in the generalized scattering matrix. The use of Floquet modes allows analysis of general geometries and nonnormal incident angles without the need for magnetic and electric wall assumptions. By developing a generalized scattering matrix for the embedding periodic array, this approach now allows conventional amplifier design techniques and analysis methods to be applied to quasi-optical grid amplifier and oscillator design. The major advantage of this unification for grid amplifier design being that the stability of the design can be predicted. RP Epp, LW (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 23 TC 6 Z9 6 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD MAY PY 1996 VL 44 IS 5 BP 760 EP 769 DI 10.1109/22.493930 PG 10 WC Engineering, Electrical & Electronic SC Engineering GA UL099 UT WOS:A1996UL09900015 ER PT J AU Parker, DE Wilson, H Jones, PD Christy, JR Folland, CK AF Parker, DE Wilson, H Jones, PD Christy, JR Folland, CK TI The impact of Mount Pinatubo on world-wide temperatures SO INTERNATIONAL JOURNAL OF CLIMATOLOGY LA English DT Article DE volcanic eruptions; temperature variations; atmospheric circulation; Mount Pinatubo ID EL-CHICHON; VOLCANIC-ERUPTIONS; WINTER; MODEL; VALIDATION; ANOMALIES; PRECISION AB We monitor and model the effects on world-wide temperatures of the June 1991 volcanic eruption of Mount Pinatubo in the Philippines. Global mean air temperatures were reduced, by up to 0.5 degrees C at the surface and 0.6 degrees C in the troposphere, for some months in mid-1992, in approximate accord with model predictions. Differences from these predictions occurred in the Northern Hemisphere winters of 1991-1992 and 1992-1993, as a result of atmospheric circulation changes that yielded continental surface warmings not fully reproduced by the model. The effects of the eruption were less evident by 1994. A superposed-epoch composite for five major tropical eruptions shows significant global post-eruption cooling at the surface when the effects of the El Nino-Southern Oscillation are removed from the data. Stratospheric warmth following Pinatubo lasted until early 1993 according to Microwave Sounding Unit data. C1 COLUMBIA UNIV,NEW YORK,NY. NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. UNIV E ANGLIA,CLIMAT RES UNIT,NORWICH NR4 7TJ,NORFOLK,ENGLAND. UNIV ALABAMA,DEPT ATMOSPHER SCI,HUNTSVILLE,AL. RP Parker, DE (reprint author), METEOROL OFF,HADLEY CTR,LONDON RD,BRACKNELL RG12 2SY,BERKS,ENGLAND. RI Jones, Philip/C-8718-2009; Folland, Chris/I-2524-2013 OI Jones, Philip/0000-0001-5032-5493; NR 49 TC 56 Z9 59 U1 3 U2 22 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0899-8418 J9 INT J CLIMATOL JI Int. J. Climatol. PD MAY PY 1996 VL 16 IS 5 BP 487 EP 497 DI 10.1002/(SICI)1097-0088(199605)16:5<487::AID-JOC39>3.0.CO;2-J PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UR647 UT WOS:A1996UR64700001 ER PT J AU Cronise, RJ Noever, DA Brittain, A AF Cronise, RJ Noever, DA Brittain, A TI Self-organized criticality in closed ecosystems: Carbon dioxide fluctuations in Biosphere 2 SO INTERNATIONAL JOURNAL OF CLIMATOLOGY LA English DT Article DE carbon dioxide fluctuations; self-organized criticality; Biosphere 2 ID SANDPILE; TURBULENCE; AVALANCHES AB A little understood question in climate and ecological modelling is when a system appropriately can be considered in statistical equilibrium or quasi-steady state. The answer bears on a host of central issues, including the ability of small perturbations to cause large catastrophes, the constant drift of unsettled systems, and the maximum amount of environmental control theoretically possible. Using Biosphere 2 records, the behaviour of carbon dioxide fluctuations was tested for correspondence with theories now known collectively as self-organized criticality. The signature of agreement with other large, composite systems, including forest fires, stock markets, and earthquakes, is a common frequency spectrum or power-law correlations. In this case, the large- and small-scale ends of the spectrum share a common driving force and consequently no single cut-off exists for excluding or ignoring small environmental changes. From the Biosphere 2 carbon dioxide data, the fluctuations in internal atmospheres vary in both small and large steps. The time fluctuations were examined as they varied over 2 years and over three orders of magnitude in fluctuation size, then binned into characteristic size classes. The statistics show a power-law scaling exponent of -1.3, compared with -1 for classical flicker noise (1/f spectrum) and -2.5 for analogous sand-pile experiments developed to test the predictions of a self-organized, critical system. For comparison with open ecosystems, the Byrd climatic record of global CO2 over the last 50 ka has a similar power-law relation but with -2.3 as the scaling exponent. For generalizing self-organized criticality, the design suggests that otherwise unrelated biological and physical models may share a common correlation between the frequency of small and large length-scales or equivalently exhibit temporal similarity laws. The results potentially have wide implications for environmental control in otherwise chaotic or difficult to predict ecological behaviour. RP Cronise, RJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,BIOPHYS BRANCH,ES76,HUNTSVILLE,AL 35812, USA. NR 20 TC 5 Z9 5 U1 3 U2 7 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0899-8418 J9 INT J CLIMATOL JI Int. J. Climatol. PD MAY PY 1996 VL 16 IS 5 BP 597 EP 602 DI 10.1002/(SICI)1097-0088(199605)16:5<597::AID-JOC28>3.0.CO;2-J PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UR647 UT WOS:A1996UR64700007 ER PT J AU Cucinotta, FA Wilson, JW Shavers, MR Katz, R AF Cucinotta, FA Wilson, JW Shavers, MR Katz, R TI Effects of track structure and cell inactivation on the calculation of heavy ion mutation rates in mammalian cells SO INTERNATIONAL JOURNAL OF RADIATION BIOLOGY LA English DT Article ID BEAMS; FIBROBLASTS; INDUCTION; ELECTRONS; MODEL AB It has long been suggested that inactivation severely effects the probability of mutation by heavy ions in mammalian cells. Heavy ions have observed cross sections of inactivation that approach and sometimes exceed the geometric size of the cell nucleus in mammalian cells. In the track structure model of Katz the inactivation cross section is found by summing an inactivation probability over all impact parameters from the ion to the sensitive sites within the cell nucleus. The inactivation probability is evaluated using the dose-response of the system to gamma-rays and the radial dose of the ions and may be equal to unity at small impact parameters for some ions. We show how the effects of inactivation may be taken into account in the evaluation of the mutation cross sections from heavy ions in the track structure model through correlation of sites for gene mutation and cell inactivation. The model is fit to available data for HPRT mutations in Chinese hamster cells and good agreement is found. The resulting calculations qualitatively show that mutation cross sections for heavy ions display minima at velocities where inactivation cross sections display maxima. Also, calculations show the high probability of mutation by relativistic heavy ions due to the radial extension of ions track from delta-rays in agreement with the microlesion concept. The effects of inactivation on mutations rates make it very unlikely that a single parameter such as LET or Z*(2)/beta(2) can be used to specify radiation quality for heavy ion bombardment. C1 JOHNS HOPKINS UNIV, SCH MED, DIV RADIAT ONCOL, BALTIMORE, MD 21205 USA. TEXAS A&M UNIV, COLLEGE STN, TX 77843 USA. UNIV NEBRASKA, LINCOLN, NE 68588 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. NR 30 TC 28 Z9 28 U1 0 U2 3 PU INFORMA HEALTHCARE PI LONDON PA TELEPHONE HOUSE, 69-77 PAUL STREET, LONDON EC2A 4LQ, ENGLAND SN 0955-3002 J9 INT J RADIAT BIOL JI Int. J. Radiat. Biol. PD MAY PY 1996 VL 69 IS 5 BP 593 EP 600 DI 10.1080/095530096145607 PG 8 WC Biology; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging GA UP361 UT WOS:A1996UP36100008 PM 8648247 ER PT J AU Jedrey, TC AF Jedrey, TC TI Advanced communications technology satellite SO INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS LA English DT Editorial Material RP Jedrey, TC (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0737-2884 J9 INT J SATELL COMMUN JI Int. J. Satell. Commun. PD MAY-JUN PY 1996 VL 14 IS 3 BP 129 EP 131 PG 3 WC Engineering, Aerospace; Telecommunications SC Engineering; Telecommunications GA VF332 UT WOS:A1996VF33200002 ER PT J AU Hoder, D Bergamo, M AF Hoder, D Bergamo, M TI Gigabit satellite network for NASA's advanced communication technology satellite (ACTS) SO INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS LA English DT Article DE earth terminals; TDMA; gigabit networks; SONET networks; wideband networks AB The advanced communication technology satellite (ACTS) gigabit satellite network provides long-haul point-to-point and point-to-multipoint full-duplex SONET services over NASA's ACTS, at rates up to 622 Mbit/s (SONET OC-12), with signal quality comparable to that obtained with terrestrial fiber networks. Data multiplexing over the satellite is accomplished using time-division multiple access' (TDMA) techniques coordinated with the switching and beam hopping facilities provided by ACTS. Transmissions through the satellite are protected with Reed-Solomon encoding, providing virtually error-free transmission under most weather conditions. Unique to the system are a TDMA frame structure and satellite synchronization mechanism that allow: (a) very efficient utilization of the satellite capacity; (b) over-the-satellite closed-loop synchronization of the network in configurations with up to 64 ground stations; and (c) ground station initial acquisition without collisions with existing signalling or data traffic. The user interfaces are compatible with SONET standards, performing the function of conventional SONET multiplexers and, as such, can be readily integrated with standard SONET fiber-based terrestrial networks. Management of the network is based upon the simple network management protocol (SNMP), and includes an over-the-satellite signalling network and backup terrestrial internet (IF-based) connectivity. A description of the ground stations is also included. RP Hoder, D (reprint author), NASA,LEWIS RES CTR,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 12 TC 3 Z9 3 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0737-2884 J9 INT J SATELL COMMUN JI Int. J. Satell. Commun. PD MAY-JUN PY 1996 VL 14 IS 3 BP 161 EP 173 DI 10.1002/(SICI)1099-1247(199605)14:3<161::AID-SAT545>3.0.CO;2-8 PG 13 WC Engineering, Aerospace; Telecommunications SC Engineering; Telecommunications GA VF332 UT WOS:A1996VF33200004 ER PT J AU Abbe, BS Agan, MJ Jedrey, TC AF Abbe, BS Agan, MJ Jedrey, TC TI Acts mobile terminals SO INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS LA English DT Article DE mobile communications; K/Ka-band communications; aeronautical communications ID SATELLITE AB The development of the advanced communications technology satellite (ACTS) mobile terminal (AMT) and its follow-on, the broadband aeronautical terminal (BAT), have provided an excellent testbed for the evaluation of K- and Ka-band mobile satellite communications systems. Such systems have proved viable for many different commercial and government applications. Combining emerging satellite communications technologies such as ACTS' highly focused spotbeams with the smaller, higher-gain K- and Ka-band antenna technology, results in system designs that can support significantly higher throughput capacity than today's current commercial systems. An overview of both of these terminals is presented in this paper. RP Abbe, BS (reprint author), CALTECH,JET PROP LAB,MAIL STOP 238-420,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 12 TC 4 Z9 4 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0737-2884 J9 INT J SATELL COMMUN JI Int. J. Satell. Commun. PD MAY-JUN PY 1996 VL 14 IS 3 BP 175 EP 189 DI 10.1002/(SICI)1099-1247(199605)14:3<175::AID-SAT550>3.0.CO;2-9 PG 15 WC Engineering, Aerospace; Telecommunications SC Engineering; Telecommunications GA VF332 UT WOS:A1996VF33200005 ER PT J AU Jedrey, TC Satorius, EH Agan, MJ AF Jedrey, TC Satorius, EH Agan, MJ TI A frequency offset estimation and compensation algorithm for K/Ka-band communications SO INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS LA English DT Article DE advanced communications technology satellite (ACTS); K/Ka band communications; ACTS mobile terminal (AMT); differential phase shift-keyed (DPSK); Doppler estimation; open loop AB This paper presents a new open-loop technique for estimating and correcting Doppler frequency shift in K/Ka-band communication systems with special reference to the advanced communications technology satellite (ACTS) mobile terminal (AMT) modem, which utilizes square-wave pulse-shaped, binary differential phase shift-keyed (DPSK) modulation. The novelty of this estimation scheme is that it exploits the Doppler-induced phase shift over a fraction of a symbol interval to provide an estimate of the Doppler offset, without requiring symbol synchronization. Furthermore, by utilizing time-differential detection (delay-and-multiply), the proposed technique can tolerate much larger frequency offsets than existing open- or closed-loop techniques. Analytical results are provided for the variance of the above estimator and the error probability performance of the AMT is evaluated in the presence of the Doppler correction. Practical design considerations are also discussed, including a method for modifying the front end, digital bandlimiting filter in such a way that Doppler bias effects in the new estimator are eliminated. Simulation results reveal that, in general, performance improves with increasing data rates, i.e., the new frequency offset estimation/compensation algorithm induces a degradation from ideal of approximately 1 dB at a 6 dB energy per data symbol (bit) and a 2.4 kbps data rate. However, there is no appreciable degradation when the data rate is increased to 9.6 or 19.2 kbps. RP Jedrey, TC (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 9 TC 1 Z9 1 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0737-2884 J9 INT J SATELL COMMUN JI Int. J. Satell. Commun. PD MAY-JUN PY 1996 VL 14 IS 3 BP 191 EP 200 PG 10 WC Engineering, Aerospace; Telecommunications SC Engineering; Telecommunications GA VF332 UT WOS:A1996VF33200006 ER PT J AU Pasqualino, CR Abbe, BS Dixon, F AF Pasqualino, CR Abbe, BS Dixon, F TI National security/emergency preparedness and disaster recovery communications via ACTS SO INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS LA English DT Article DE VSAT; satellite communications; ACTS; emergency response AB During the period from early 1993 to 1994, the U.S. National Communication System (NCS), a government agency, sponsored the development and execution of several fixed and mobile experiments using the advanced communications technology satellite (ACTS). The purpose of these experiments was to evaluate the feasibility of integrating an ACTS-like communications system into national security/emergency preparedness (NS/EP) operational scenarios. These experiments focused on clear and secure voice communications in both the fixed and mobile environment. For the mobile experiments, the focus was on the performance of both clear and secure voice in the land-mobile satellite communications channel. For the fixed experiments, the focus was on the use of a T1 terminal for restoration of communication services in the event of a disaster and for remote user communications. The results of these experiments are described in this paper. RP Pasqualino, CR (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0737-2884 J9 INT J SATELL COMMUN JI Int. J. Satell. Commun. PD MAY-JUN PY 1996 VL 14 IS 3 BP 219 EP 232 PG 14 WC Engineering, Aerospace; Telecommunications SC Engineering; Telecommunications GA VF332 UT WOS:A1996VF33200008 ER PT J AU Agan, MJ Nakamura, DI Campbell, AD Sternowski, RH Whiting, WA Shameson, L AF Agan, MJ Nakamura, DI Campbell, AD Sternowski, RH Whiting, WA Shameson, L TI ACTS aeronautical experiments SO INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS LA English DT Article DE aeronautical satellite communications; Advanced Communications Technology Satellite (ACTS); Broadband Aeronautical Terminal (BAT); high data rate aeronautical satellite communication; ACTS aeronautical experiments AB This paper discusses a series of aeronautical experiments that utilize the advanced communication technology satellite (ACTS). As part of the ongoing effort to investigate commercial applications of ACTS technologies, NASA's Jet Propulsion Laboratory and various industry/government partners have developed a series of experiments that utilize the ACTS mobile terminal (AMT)(1) and the broadband aeronautical terminal(1) to investigate aeronautical uses of the ACTS. This paper discusses these experiments including the experiment configurations, technologies, results and future implications. RP Agan, MJ (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 7 TC 3 Z9 3 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0737-2884 J9 INT J SATELL COMMUN JI Int. J. Satell. Commun. PD MAY-JUN PY 1996 VL 14 IS 3 BP 233 EP 247 DI 10.1002/(SICI)1099-1247(199605)14:3<233::AID-SAT544>3.0.CO;2-5 PG 15 WC Engineering, Aerospace; Telecommunications SC Engineering; Telecommunications GA VF332 UT WOS:A1996VF33200009 ER PT J AU Pinck, DS Tong, LH AF Pinck, DS Tong, LH TI Satellite-enhanced personal communications experiments SO INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS LA English DT Article DE personal communications; wireless networking; mobile satellite communications; wireless protocols AB Users of future generation wireless information services will have diverse needs for voice, data, and potentially even video communications in a wide variety of circumstances. For users in dense, inner-city areas, low power personal communications services (PCS) technology should be ideal. Vehicular-based users travelling at high speeds will need high-power cellular technology. For users in remote or inaccessible locations, or for applications that are broadcast over a wide geographic area, a satellite technology would be the best choice. Packet data networks provide an excellent solution for users requiring occasional small messages, whereas circuit switched networks provide more economical solutions for larger messages. To provide ubiquitous personal communications service, it is necessary to capitalize on the strength of each wireless technology and network to create one seamless internetwork including both current and future wired and wireless networks. As an initial step in exploring the opportunities afforded by the merging of satellite and terrestrial networks, Bellcore and JPL conducted several experiments. These experiments utilized Bellcore's experimental personal communications system (including several messaging applications with adaptations to wireless networks), NASA's advanced communications technology satellite (ACTS), JPL's ACTS mobile terminal, and various commercial data networks (such as the wireline Internet and the RAM wireless packet data network). Looking at loss of bits, packets and higher layer blocks (over the satellite-terrestrial internetworks with mobile and stationary users under various conditions) our initial results indicate that the communication channel can vary dramatically, even within a single network. We show that these conditions necessitate powerful and adaptive protocols if we are to achieve a seamless internetworking of satellite and terrestrial networks. RP Pinck, DS (reprint author), CALTECH,JET PROP LAB,M-S 161-241,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 9 TC 0 Z9 0 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0737-2884 J9 INT J SATELL COMMUN JI Int. J. Satell. Commun. PD MAY-JUN PY 1996 VL 14 IS 3 BP 249 EP 258 PG 10 WC Engineering, Aerospace; Telecommunications SC Engineering; Telecommunications GA VF332 UT WOS:A1996VF33200010 ER PT J AU Bergman, LA Gary, JP Edelsen, B Helm, N Cohen, J Shopbell, P Mechoso, CR ChungChun Farrara, M Spahr, J AF Bergman, LA Gary, JP Edelsen, B Helm, N Cohen, J Shopbell, P Mechoso, CR ChungChun Farrara, M Spahr, J TI High bit rate experiments over ACTS SO INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS LA English DT Article DE satellite; high data rate; remote astronomy; global climate model AB This paper describes two high data rate experiments that are being developed for the gigabit NASA Advanced Communications Technology Satellite (ACTS). The first is a telescience experiment that remotely acquires image data at the Keck telescope from the Caltech campus. The second is a distributed global climate application that is run beween two supercomputer centers interconnected by ACTS. The implementation approach for each is described along with the expected results. Also, the ACTS high data rate (HDR) ground station is also described in detail. RP Bergman, LA (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0737-2884 J9 INT J SATELL COMMUN JI Int. J. Satell. Commun. PD MAY-JUN PY 1996 VL 14 IS 3 BP 259 EP 266 PG 8 WC Engineering, Aerospace; Telecommunications SC Engineering; Telecommunications GA VF332 UT WOS:A1996VF33200011 ER PT J AU Satorius, EH Tong, LH AF Satorius, EH Tong, LH TI Analysis of a rain compensation algorithm for K/Ka-band communications SO INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS LA English DT Article DE Advanced Communications Technology Satellite (ACTS); K/Ka-band; rain fading; rain compensation algorithm; data rate control; ACTS mobile terminal (AMT); link margin AB A rain compensation algorithm (RCA) has been developed for use in the advanced communications technology satellite (ACTS) mobile terminal (AMT) system. The basic goal of the RCA is to control the transmitted data rates (9.6, 4.8 or 2.4 kbps) in the forward and return links so that a 3 dB link margin is maintained at the highest possible transmitted data rate. In this paper, analyses of both theoretical and practical issues relating to the RCA are presented. In addition, sample simulations of a one-dimensional version of the RCA at the MT are presented which illustrate typical RCA performance using both simulated and recorded pilot fade field data. It is found that with suitable post-processing, the RCA can provide reasonable (conservative) data rate estimates without making excessive data rate changes, i.e., data rate change fluctuations. It is anticipated that the results presented here will not only be useful for the eventual operation of the RCA, but more generally will be useful in the design and operation of other rain compensation techniques for K/Ka-band communication systems. RP Satorius, EH (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 15 TC 6 Z9 6 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0737-2884 J9 INT J SATELL COMMUN JI Int. J. Satell. Commun. PD MAY-JUN PY 1996 VL 14 IS 3 BP 297 EP 311 DI 10.1002/(SICI)1099-1247(199605)14:3<297::AID-SAT537>3.0.CO;2-G PG 15 WC Engineering, Aerospace; Telecommunications SC Engineering; Telecommunications GA VF332 UT WOS:A1996VF33200014 ER PT J AU Jia, TD Kelleher, SD Hultin, HO Petillo, D Maney, R Krzynowek, J AF Jia, TD Kelleher, SD Hultin, HO Petillo, D Maney, R Krzynowek, J TI Comparison of quality loss and changes in the glutathione antioxidant system in stored mackerel and bluefish muscle SO JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY LA English DT Article DE glutathione; antioxidant; mackerel; bluefish; quality loss and antioxidation ID LIPID-PEROXIDATION; FISH AB Minced mackerel muscle was less stable at -20 degrees C than minced bluefish muscle as judged by odor evaluation but not by production of TEA-reactive substances. Minced mackerel muscle lost total glutathione faster than minced bluefish muscle at both -20 and 2 degrees C. Loss of glutathione was also more rapid in mackerel fillets than in bluefish fillets, but the differences were less. Sensory scores declined in both species after about two-thirds of the glutathione was lost. Neither soluble selenium nor glutathione peroxidase, oxidized glutathione reductase, or glutathione transferase activities appeared likely to account for the differences observed in glutathione losses. In a model system of washed, minced mackerel light muscle, glutathione/glutathione peroxidase was an effective antioxidant against lipid oxidation induced by an exogenous free radical-generating system. It seems possible that glutathione protected the fish muscle against quality loss in the early stages of storage. C1 UNIV MASSACHUSETTS,MASSACHUSETTS AGR EXPT STN,DEPT FOOD SCI,MARINE FOODS LAB,MARINE STN,GLOUCESTER,MA 01930. NATL MARINE FISHERIES SERV,NORTHEAST CTR,GLOUCESTER LAB,GLOUCESTER,MA 01930. NR 23 TC 26 Z9 26 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0021-8561 J9 J AGR FOOD CHEM JI J. Agric. Food Chem. PD MAY PY 1996 VL 44 IS 5 BP 1195 EP 1201 DI 10.1021/jf950767o PG 7 WC Agriculture, Multidisciplinary; Chemistry, Applied; Food Science & Technology SC Agriculture; Chemistry; Food Science & Technology GA UL585 UT WOS:A1996UL58500005 ER PT J AU Rossow, VJ AF Rossow, VJ TI Wake-vortex separation distances when flight-path corridors are constrained SO JOURNAL OF AIRCRAFT LA English DT Article AB Improved precision of the Eight paths used by aircraft to approach and depart airports will become available when the global positioning system (GPS) Is implemented for air traffic control. It is suggested here that the improved precision be used to constrain the approach and departure corridors so that their cross-sectional sizes are small and constant in size. Such a constraint controls the Eight paths of the aircraft, and consequently where their vortex wakes are placed, so that the likelihood of a wake-vortex encounter Is reduced, if such a program is coupled with a wake-vortex advisory system, and with the operating system being planned for airports when GPS is implemented, preliminary indications are that the wake-vortex spacings currently being used for instrument flight conditions can be reduced to a uniform distance of 3 n mile, Furthermore, if the smaller GPS Eight corridors are utilized by vortex advisory or forecast systems that are currently under development, the requirements to be placed on their capabilities can be substantially reduced. RP Rossow, VJ (reprint author), NASA,AMES RES CTR,LOW SPEED AERODYNAM BRANCH,M-S N247-2,MOFFETT FIELD,CA 94035, USA. NR 24 TC 6 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAY-JUN PY 1996 VL 33 IS 3 BP 539 EP 546 DI 10.2514/3.46978 PG 8 WC Engineering, Aerospace SC Engineering GA UP198 UT WOS:A1996UP19800013 ER PT J AU Cheung, SS AF Cheung, SS TI Parallel computational fluid dynamics design on network-based computer SO JOURNAL OF AIRCRAFT LA English DT Article ID QUASI-NEWTON METHODS AB Combining multiple engineering workstations into a network-based heterogeneous parallel computer allows the application of aerodynamic optimization with advanced computational fluid dynamics codes, which can be computationally expensive on mainframe supercomputers. This article introduces a nonlinear quasi-Newton optimizer designed for this network-based heterogeneous parallel computing environment utilizing a software called Parallel Virtual Machine. This article will introduce the methodology behind coupling a parabolized Navier-Stokes flow solver to the nonlinear optimizer. This parallel optimization package is applied to reduce the wave drag of a body of revolution and a wing/body configuration with results of 5-6% drag reduction. C1 NASA AMES RES CTR,MOFFETT FIELD,CA 94035. NR 27 TC 1 Z9 1 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAY-JUN PY 1996 VL 33 IS 3 BP 561 EP 566 DI 10.2514/3.46981 PG 6 WC Engineering, Aerospace SC Engineering GA UP198 UT WOS:A1996UP19800016 ER PT J AU Guruswamy, GP Tu, EL AF Guruswamy, GP Tu, EL TI Navier-Stokes computations on flexible advanced transport wings in transonic regime SO JOURNAL OF AIRCRAFT LA English DT Article ID ALGORITHM; FLOWS AB Steady, unsteady, and aeroelastic computations are performed on an advanced transonic wing configuration, The Bow is modeled by the Navier-Stokes equations, and structures for aeroelastic computations are modeled by the modal equations. The inadequacy of Euler equations and the importance of using the Navier-Stokes equations with a turbulence model is demonstrated for supercritical Bows in the transonic regime, The effect of Mach number on steady pressure distributions is Illustrated, Steady Row computations for transonic wings are compared with wind-tunnel data and also with equivalent conventional wings. Unsteady computations are made in the context of demonstrating the use of the indicial approach for generating aerodynamic data for aeroelastic computations, By using the unsteady data generated by indicial responses, a computationally efficient approach of computing preliminary Butter boundaries is demonstrated. The effect of Mach number on the Butter boundary including the prediction of the transonic Butter speed dip is demonstrated, The Butter boundaries of transonic wings are compared with equivalent conventional wings. Characteristics of the flutter boundaries are correlated with aerodynamic Bow characteristics. RP Guruswamy, GP (reprint author), NASA,AMES RES CTR,COMPUTAT AEROSCI BRANCH,MOFFETT FIELD,CA 94035, USA. NR 17 TC 8 Z9 8 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAY-JUN PY 1996 VL 33 IS 3 BP 576 EP 581 DI 10.2514/3.46984 PG 6 WC Engineering, Aerospace SC Engineering GA UP198 UT WOS:A1996UP19800019 ER PT J AU Rouse, M Ambur, DR AF Rouse, M Ambur, DR TI Damage tolerance and failure analysis of a composite geodesically stiffened compression panel SO JOURNAL OF AIRCRAFT LA English DT Article AB A geodesically stiffened continuous-filament composite structural concept has been designed for a transport aircraft fuselage application and fabricated using an automated manufacturing process, Both large panels and element specimens derived from these panels have been experimentally and analytically investigated when subjected to axial compression to understand their buckling, postbuckling, and failure responses, The primary failure mode for this structural concept Is skin-stiffener separation in the skin postbuckling load range. The large panels are subjected to low-speed impact damage and tested to failure in axial compression to evaluate the damage tolerance of this structural concept. These results suggest that damage to the stiffener and a stiffener intersection point from the skin side do not influence the failure load or failure mode of this structural concept. Nonlinear finite element analysis using a detailed element specimen model indicates that failure of this specimen may have initiated at the skin-stiffener flange region close to the stiffener intersection, When the skin is in the postbuckling range at four times its initial buckling load, the interlaminar shear stress concentrations at a region where the stiffener makes a 20-deg turn away from the stiffener intersection seem to initiate panel failure. RP Rouse, M (reprint author), NASA,LANGLEY RES CTR,AIRCRAFT STRUCT BRANCH,STRUCT DIV,HAMPTON,VA 23681, USA. NR 9 TC 5 Z9 5 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAY-JUN PY 1996 VL 33 IS 3 BP 582 EP 588 DI 10.2514/3.46985 PG 7 WC Engineering, Aerospace SC Engineering GA UP198 UT WOS:A1996UP19800020 ER PT J AU Meyn, LA James, KD AF Meyn, LA James, KD TI Full-scale wind-tunnel studies of F/A-18 tail buffet SO JOURNAL OF AIRCRAFT LA English DT Article AB Tail buffet studies were conducted on a full scale, production F/A-18 fighter aircraft in the 80 by 120 ft Wind Tunnel at NASA Ames Research Center, The F/A-18 was tested over an angle-of-attack range of 18-50 deg, and at wind speeds of up to 168 ft/s, corresponding to a Reynolds number of 12.3 x 10(6) based on mean aerodynamic chord and a Mach number of 0.15, The port, vertical tail Bn was instrumented and the aircraft was equipped with a removable leading-edge extension (LEX) fence. Time-averaged, power-spectral analysis results are presented for the tail fin bending moment derived from the integrated pressure held, for the zero side-slip condition, both with and without the LEX fence, The LEX fence significantly reduces the magnitude of the rms pressures and bending moments, Scaling issues are addressed by comparing full-scale results for pressures at the 60%-span and 45%-chord location with small-scale, F/A-18 tail buffet data, The comparison shows that the tail buffet frequency scales very well with length and velocity, Root-mean-square pressures and power spectra do not scale as well, The LEX fence is shown to reduce tail buffet loads at all model scales. RP Meyn, LA (reprint author), NASA,AMES RES CTR,LOW SPEED AERODYNAM BRANCH,MOFFETT FIELD,CA 94035, USA. NR 14 TC 20 Z9 23 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAY-JUN PY 1996 VL 33 IS 3 BP 589 EP 595 DI 10.2514/3.46986 PG 7 WC Engineering, Aerospace SC Engineering GA UP198 UT WOS:A1996UP19800021 ER PT J AU Kremer, RG Hunt, ER Running, SW Coughlan, JC AF Kremer, RG Hunt, ER Running, SW Coughlan, JC TI Simulating vegetational and hydrologic responses to natural climatic variation and GCM-predicted climate change in a semi-arid ecosystem in Washington, USA SO JOURNAL OF ARID ENVIRONMENTS LA English DT Article DE ecosystem model; climate change; productivity; semi-arid ID NORTH-AMERICAN GRASSLANDS; WATER-USE; CARBON-DIOXIDE; REGIONAL APPLICATIONS; MODEL SIMULATIONS; CO2 CONCENTRATION; GENERAL-MODEL; LEAF-AREA; FOREST; BALANCE AB An ecosystem process model was used to assess likely ecosystem responses to natural climatic variation and GCM-predicted climatic change in the semiarid north-western U.S.A. Simulated equilibrium conditions between soil water availability and leaf area were compared to long-term natural variations for annual grass and mixed sagebrush/bunchgrass communities subjected to 2 degrees C increases in daily temperature, coupled with 10% increases and decreases in precipitation. Equilibrium simulations suggested that a less productive, invasive grass community would tolerate climate change, whereas a native sagebrush community would not survive the increased temperatures predicted by GCMs. High air temperatures, and the subsequent increases in vapor pressure deficit, caused decreased stomatal conductance, and hence decreased net photosynthesis. High air temperatures also increased maintenance respiration, leading to decreases in net primary production. As the productivity of this community declined, substantial increases in soil water storage occurred. When natural variation of annual weather is incorporated into simulations, both community types were able to survive by adjusting levels of biomass production. Soil water storage was not significantly affected when the vegetation adapted to increased or decreased precipitation through proportional adjustments to leaf area, which in nun dictates evapotranspiration and son water drawdown. (C) 1996 Academic Press Limited C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Kremer, RG (reprint author), UNIV MONTANA,SCH FORESTRY,MISSOULA,MT 59812, USA. NR 36 TC 16 Z9 20 U1 1 U2 11 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0140-1963 J9 J ARID ENVIRON JI J. Arid. Environ. PD MAY PY 1996 VL 33 IS 1 BP 23 EP 38 DI 10.1006/jare.1996.0043 PG 16 WC Ecology; Environmental Sciences SC Environmental Sciences & Ecology GA UW528 UT WOS:A1996UW52800003 ER PT J AU Kwack, EY Back, LH Ruan, XM Chaux, A AF Kwack, EY Back, LH Ruan, XM Chaux, A TI Flow measurements in an aortocoronary bypass graft casting SO JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID MAMMARY-ARTERY GRAFT; 10-YEAR SURVIVAL; STEADY FLOW AB Flow visualization and pressure measurements were carried out in a single valve saphenous vein casting which was made from a saphenous vein segment obtained from a bypass patient at Cedars Sinai Medical Center. Dye was injected to understand the flow around the valve. The dye showed very complex flow patterns around the valve and in the valve sinus, and the cavity formed by a ligated branch. For steady flow pressure drops across the valve were 0.72, 2.0 and 6.3 mmHg for the physiological flow rates of 45, 84, and 169 ml/min, respectively. Overall pressure drop across the casting (compared to Poiseuille flow for a straight tube) increased with the flow rare, being 130 to 290 percent higher over this flow rate range. In the case of pulsatile flow pressure drops across the valve were 0.95 and 3.0 mmHg for the flow rates of 47 and 87 ml/min which were 26 and 43 percent higher than those of steady flow. Overall pressure drop was 220 and 360 percent higher for those flow rates compared to Poiseuille flow. The measured spatial pressure distributions along the casting and flow visualization indicated the global nature of the flow field with the accelerated flow through the valve separating and reattaching downstream along the wall in the pressure recovery region. Atherosclerosis may be prone to occur in the lower shear region along the wall beyond the valve tip in the reattachment region, as we have observed in vivo in rabbit experiments. C1 CEDARS SINAI MED CTR, DEPT THORAC & CARDIOVASC SURG, LOS ANGELES, CA 90048 USA. RP Kwack, EY (reprint author), CALTECH, JET PROP LAB, TECH STAFF, PASADENA, CA 91109 USA. NR 15 TC 0 Z9 0 U1 0 U2 1 PU ASME PI NEW YORK PA TWO PARK AVE, NEW YORK, NY 10016-5990 USA SN 0148-0731 J9 J BIOMECH ENG-T ASME JI J. Biomech. Eng.-Trans. ASME PD MAY PY 1996 VL 118 IS 2 BP 165 EP 171 DI 10.1115/1.2795955 PG 7 WC Biophysics; Engineering, Biomedical SC Biophysics; Engineering GA UM408 UT WOS:A1996UM40800004 PM 8738780 ER PT J AU Bobele, GB Feeback, DL Leech, RW Brumback, RA AF Bobele, GB Feeback, DL Leech, RW Brumback, RA TI Hypertrophic intrafusal muscle fibers in infantile spinal muscular atrophy SO JOURNAL OF CHILD NEUROLOGY LA English DT Article ID RAT C1 NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,DIV MED SCI,HOUSTON,TX 77058. UNIV OKLAHOMA,HLTH SCI CTR,DEPT PATHOL,SECT NEUROPATHOL,OKLAHOMA CITY,OK. RP Bobele, GB (reprint author), DRISCOLL CHILDRENS HOSP,CORPUS CHRISTI,TX, USA. RI Brumback, Roger/A-2404-2008 NR 11 TC 0 Z9 0 U1 0 U2 1 PU DECKER PERIODICALS INC PI HAMILTON PA 4 HUGHSON STREET SOUTH PO BOX 620, LCD 1, HAMILTON ON L8N 3K7, CANADA SN 0883-0738 J9 J CHILD NEUROL JI J. Child Neurol. PD MAY PY 1996 VL 11 IS 3 BP 246 EP 248 PG 3 WC Clinical Neurology; Pediatrics SC Neurosciences & Neurology; Pediatrics GA UK384 UT WOS:A1996UK38400018 PM 8734032 ER PT J AU Yang, S Lau, KM SankarRao, M AF Yang, S Lau, KM SankarRao, M TI Precursory signals associated with the interannual variability of the Asian summer monsoon SO JOURNAL OF CLIMATE LA English DT Article ID SNOW COVER; TEMPERATURE; PRECIPITATION; CLIMATE; EURASIA; SCHEME; MODEL AB In this work, the interannual variability of the Asian summer monsoon is studied by analyzing outputs of the Atmospheric Model Intercomparison Project integration using the Goddard Laboratory for Atmospheres general circulation model. The main effort is devoted to exploring and understanding precursory signals associated with the interannual variability of the Asian monsoon and deciphering possible physical mechanisms responsible for the signals. It is found that strong precursory signals of highly anomalous Asian summer monsoon appear over the subtropical Asian region during the previous winter-spring seasons. Prior to a strong summer monsoon, the westerlies over subtropical Asia are weaker than normal, and vice versa. Dynamically consistent changes are found in other fields such as atmospheric temperature, geopotential height, and surface temperature. These precursory signals seem to have a barotropic structure in the troposphere. They exist over a broad region and last for two to three seasons. The robustness of the signals is important for improving seasonal prediction of the Asian summer monsoon. It is hypothesized that the above-described precursory signals of the Asian summer monsoon are linked to land-surface hydrologic processes, such as changes in snow mass and soil moisture in the Asian continent, as well as anomalous sea surface temperature forcing in the Pacific and Indian Oceans. Evidence in support of the above hypothesis can be found in the variability of a variety of parameters from both model simulation and observations. C1 NATL SCI FDN, CLIMATE DYNAM PROGRAM, ARLINGTON, VA USA. RP Yang, S (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CLIMATE & RADIAT BRANCH, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. RI Yang, Song/B-4952-2009; Lau, William /E-1510-2012 OI Lau, William /0000-0002-3587-3691 NR 26 TC 55 Z9 66 U1 1 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD MAY PY 1996 VL 9 IS 5 BP 949 EP 964 DI 10.1175/1520-0442(1996)009<0949:PSAWTI>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN856 UT WOS:A1996UN85600004 ER PT J AU Lau, KM Yang, S AF Lau, KM Yang, S TI Seasonal variation, abrupt transition, and intraseasonal variability associated with the Asian summer monsoon in the GLA GCM SO JOURNAL OF CLIMATE LA English DT Article ID ECMWF MODEL; CIRCULATION; PARAMETERIZATION; EVAPORATION; PREDICTION; RAINFALL; SCHEME; CLOUD AB In this paper, a description of the global and regional features of the Asian summer monsoon in the Goddard Laboratory Atmospheres (GLA) general circulation model (GCM) is presented based on a 10-yr (1979-1988) integration of the model under the Atmospheric Model Intercomparison Project. It is found that the earliest signal of onset of the Asian monsoon is represented by the emergence of convection over the Indo-China ''land bridge'' in early May, followed by the sudden jump of the equatorial ITCZ (intertropical convergence zone) to 10 degrees N over the South China Sea and Indian Ocean in mid-May. This sudden jump is linked to an abrupt northward shift of the ascending branch of the local Hadley circulation, possibly stemming from symmetric instability of the basic flow in May. In agreement with observations, the model shows a pronounced intraseasonal oscillation along the equator and enhanced synoptic-scale activities identified as easterly waves in the tropical and subtropical western Pacific. These intraseasonal and synoptic activities strongly regulate rainfall variability over East Asia, especially during the premonsoon period. While the model simulates a similar range of variability in the broad-scale structure and evolution of the Asian monsoon as observed, there is considerable scope for improvement in the model's ability to simulate regional features of the monsoon. Compared to observed climatology, the model produces deficient rainfall over northern India but excessive rainfall over the South China Sea and the western Pacific region due to an overactive ITCZ at 10 degrees N. The intraseasonal transition between the equatorial ITCZ and the monsoon (land) convection to the north is weaker than in nature. Moreover, the East Asian monsoon trough and Mei-yu rainband are underdeveloped in the model. These discrepancies are related to the limited northward extension of the model monsoon circulation and the confinement of the upper-level easterly flow near the equator. Overall, the GLA GCM provides a reasonably realistic description of the seasonal and subseasonal climatology of the Asian monsoon and yields important information that sheds new light on the dynamical underpinnings of the multiscale variabilities associated with the Asian summer monsoon. RP Lau, KM (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 913, GREENBELT, MD 20771 USA. RI Yang, Song/B-4952-2009; Lau, William /E-1510-2012 OI Lau, William /0000-0002-3587-3691 NR 37 TC 78 Z9 101 U1 2 U2 9 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD MAY PY 1996 VL 9 IS 5 BP 965 EP 985 DI 10.1175/1520-0442(1996)009<0965:SVATAI>2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN856 UT WOS:A1996UN85600005 ER PT J AU Lau, KM Sheu, PJ Schubert, S Ledvina, D Weng, H AF Lau, KM Sheu, PJ Schubert, S Ledvina, D Weng, H TI Evolution of large-scale circulation during TOGA COARE: Model intercomparison and basic features SO JOURNAL OF CLIMATE LA English DT Article ID WESTERN PACIFIC; COLD SURGES; HEMISPHERE; ATMOSPHERE; CLUSTERS; TROPICS; PERIOD; CLOUD; OCEAN AB An intercomparison study of the evolution of large-scale circulation features during TOGA COARE has been carried our using data from three 4D assimilation systems: the National Meteorological Center (NMC, currently known as the National Center for Environment Predication), the Navy Fleet Numerical Oceanography Center, and the NASA Goddard Space Flight Center. Results show that the preliminary assimilation products, though somewhat crude, can provide important information concerning the evolution of the large-scale atmospheric circulation over the tropical western Pacific during TOGA COARE. Large-scale features such as sea level pressure, rotational wind field, and temperature are highly consistent among models. However, the rainfall and wind divergence distributions show poor agreement among models, even though some useful information can still be derived. All three models shows a continuous background rain over the Intensive Flux Area (IFA), even during periods with suppressed convection, in contrast to the radar-estimated rainfall that is more episodic. This may reflect a generic deficiency in the oversimplified representation of large-scale rain in all three models. Based on the comparative model diagnostics, a consistent picture of large-scale evolution and multiscale interaction during TOGA COARE emerges. The propagation of the Madden and Julian Oscillation (MJO) from the equatorial Indian Ocean region into the western Pacific foreshadows the establishment or westerly wind events over the COARE region. The genesis and maintenance of the westerly wind (WW) events during TOGA COARE are related to the establishment of a large-scale east-west pressure dipole between the Maritime Continent and the equatorial central Pacific. This pressure dipole could be identified in part with the ascending (low pressure) and descending (high pressure) branches of the MJO and in part with the fluctuations of the austral summer monsoon. Accompanying the development of WW over the IFA and crucial to its maintenance is a robust meridional circulation, with strong cross-equatorial flow and rising motion near the entrance region of the WW and sinking motion in the extratropical Northern Hemisphere. The presence of a quasi-stationary equatorial heat source near the date line may have provided additional feedback mechanisms for the WWs. Surface pressure and wind surges related to cold air outbreaks off the East Asian continent play an important role in the rapid build up and/or termination of the WWs during TOGA COARE. The establishment of WWs in the near equatorial region may be linked to the modulation of North Pacific storm track activities. RP Lau, KM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,MAIL CODE 913,GREENBELT,MD 20771, USA. RI Lau, William /E-1510-2012 OI Lau, William /0000-0002-3587-3691 NR 24 TC 8 Z9 9 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD MAY PY 1996 VL 9 IS 5 BP 986 EP 1003 DI 10.1175/1520-0442(1996)009<0986:EOLSCD>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN856 UT WOS:A1996UN85600006 ER PT J AU Chen, MH Bates, JR AF Chen, MH Bates, JR TI A comparison of climate simulations from a semi-Lagrangian and an Eulerian GCM SO JOURNAL OF CLIMATE LA English DT Article ID RADIATION BUDGET EXPERIMENT; GENERAL-CIRCULATION MODELS; SHALLOW-WATER EQUATIONS; HORIZONTAL RESOLUTION; SCHEMES; INTEGRATION; SENSITIVITY AB Two parallel 5-year climate simulations have been carried out to assess the effect of changing from an Eulerian to a semi-Langrangian formulation of a general circulation model's dynamical core with the physical parameterizations unchanged. It has been found that the change in formulation leads to significant differences in the simulated climates, both for fields determined mainly by the dynamics, such as sea level pressure, and for those determined mainly by the physics, such as precipitation. The differences result both directly from the changes in the dynamics and indirectly from the interactions of the dynamics with the physics. Compared to the simulation with the Eulerian model, the principal improvement with the semi-Lagrangian model is a significant reduction in, or even elimination of, the cold bias in the polar upper troposphere and lower stratosphere in both hemispheres. This improvement is evident in both the winter and summer seasons. It results from the more efficient poleward heat transport in the semi-Lagrangian model. The effect on other simulated fields can give results either closer to or farther from the corresponding analyses and observations. The physical parameterizations used in the semi-Lagrangian model have been developed and tuned for the Eulerian model. To optimize the performance of the semi-Lagrangian model, it will be necessary to tune the physical parameterizations explicitly for this mode. C1 NASA, GODDARD SPACE FLIGHT CTR, DATA ASSIMILAT OFF, GREENBELT, MD 20771 USA. NR 47 TC 26 Z9 26 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD MAY PY 1996 VL 9 IS 5 BP 1126 EP 1149 DI 10.1175/1520-0442(1996)009<1126:ACOCSF>2.0.CO;2 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UN856 UT WOS:A1996UN85600015 ER PT J AU Green, LL Newman, PA Haigler, KJ AF Green, LL Newman, PA Haigler, KJ TI Sensitivity derivatives for advanced CFD algorithm and viscous modeling parameters via automatic differentiation SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID TURBULENCE AB The computational technique of automatic differentiation (AD) is applied to a complicated computer program to illustrate the simplicity, efficiency, and versatility of AD with complex algorithms for use within a sensitivity analysis. Many algorithmic and physics modeling coefficients appear in computer programs that are routinely set in an ad hoc manner; AD can be used to enhance computer programs with derivative information suitable for guiding formal sensitivity analyses, which allows these coefficient values to be chosen in a rigorous manner to achieve particular program properties such as an improved convergence rate or improved accuracy. In this paper, AD is applied to a three-dimensional thin-layer Navier-Stokes multigrid flow solver to assess the feasibility and computational impact of obtaining exact sensitivity derivatives with respect to algorithmic and physics modeling parameters typical of those needed for sensitivity analyses. Calculations are performed for an ONERA Ms wing in transonic flow with both the Baldwin-Lomax and Johnson-King turbulence models. The wing lift, drag, and pitching moment coefficients are differentiated with respect to two different groups of input parameters. The first group consists of the second- and fourth-order damping coefficients of the computational algorithm, whereas the second group consists of two parameters in the viscous turbulent flow physics modeling. Results obtained via AD are compared for both accuracy and computational efficiency with the results obtained with divided differences (DD). The AD results are accurate, extremely simple to obtain, and show significant computational advantage over those obtained by DD for some cases. RP Green, LL (reprint author), NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. NR 34 TC 21 Z9 22 U1 1 U2 2 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD MAY PY 1996 VL 125 IS 2 BP 313 EP 324 DI 10.1006/jcph.1996.0096 PG 12 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA UJ965 UT WOS:A1996UJ96500003 ER PT J AU Ajello, J Shemansky, D Kanik, I James, G Liu, X Ahmed, S Ciocca, M AF Ajello, J Shemansky, D Kanik, I James, G Liu, X Ahmed, S Ciocca, M TI High resolution UV spectroscopy of H-2 and N-2 applied to observations of the planets by spacecraft SO JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA LA English DT Article; Proceedings Paper CT 11th International Conference on Vacuum Ultraviolet Radiation Physics (VUV-11 Conference) CY AUG 27-SEP 01, 1995 CL RIKKYO UNIV, TOKYO, JAPAN SP Phys Soc Japan, Chem Soc Japan, Japanese Soc Appl Phys, Spectroscop Soc Japan, Biophys Soc Japan, Vacuum Soc Japan, Japan Soc Promot Sci, Federat Econ Org, Commemorat Assoc Japan World Exposit 1970, JAERI RIKEN Spring 9 Project Team, Unoue Fdn Sci, Ciba Geigy Fdn Japan Promot Sci, Murata Sci Fdn, Asahi Glass Fdn, Shimadzu Sci Fdn, Watanabe Mem Fdn Adv Technol, Nippon Sheet Glass Fdn Mat Sci & Engn, Osaka Sci & Technol Ctr HO RIKKYO UNIV ID ELECTRON-IMPACT; MOLECULAR-HYDROGEN; EMISSION; SPECTRA AB The next generation of high resolution UV imaging spacecraft are being prepared for studying the airglow and aurora of the Earth, the other terrestrial planets and the Jovian planets. To keep pace with these technological improvements we have developed a laboratory program to provide electron impact collision cross sections of the major molecular planetary gases (H-2 N-2, CO2, O-2 and CO). Spectra under optically thin conditions have been measured with a high resolution (lambda/Delta lambda = 50000) UV spectrometer in tandem with electron impact collision chamber. High resolution spectra of the Lyman and Werner band systems of H-2 have been obtained and modeled. Synthetic spectral intensities based on the J-dependent transition probabilities that include ro-vibronic perturbations ate in very good agreement with experimental intensities. The kinetic energy distribution of H(2p,3p) atoms resulting from electron impact dissociation of H-2 has been measured. The distribution is based on the first measurement of the H Lyman-alpha (H L alpha) and H Lyman-beta (H L beta) emission line Doppler profiles. Electron impact dissociation of H-2 is believed to be one of the major mechanisms leading to the observed wide profile of H L alpha from Jupiter aurora by the Hubble Space Telescope (HST). Analysis of the deconvolved line profile of H L alpha reveals the existence of a narrow line peak (40 m Angstrom FWHM) and a broad pedestal base (240 m Angstrom FWHM). The band strengths of the electron excited N-2(C-3 Pi(u)-B-3 Pi(g)) second positive system have been measured in the middle ultraviolet. We report a quantitative measurement of the predissociation fraction 0.15+/- (.01)(.045) at 300 K in the N(2)c'(1)(4) Sigma(u)(+)-X(1) Sigma(g)(+) (0,0) band, with an experimental determination of rotational line strengths to be used to understand N-2 EUV emission from Titan, Triton and the Earth. C1 UNIV SO CALIF,LOS ANGELES,CA 90089. RP Ajello, J (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 1 Z9 1 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0368-2048 J9 J ELECTRON SPECTROSC JI J. Electron Spectrosc. Relat. Phenom. PD MAY PY 1996 VL 79 BP 429 EP 432 DI 10.1016/0368-2048(96)02887-3 PG 4 WC Spectroscopy SC Spectroscopy GA UY743 UT WOS:A1996UY74300100 ER PT J AU Gary, SP Wang, J AF Gary, SP Wang, J TI Whistler instability: Electron anisotropy upper bound SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PLASMA AB If the electron distribution function is approximately bi-Maxwellian with T-perpendicular to/T-parallel to > 1, where the subscript symbols denote directions perpendicular and parallel > 1, to the background magnetic field, and if this temperature anisotropy is sufficiently large, the whistler anisotropy instability is excited. This mode is studied using two-dimensional particle-in-cell simulations in a spatially homogeneous plasma model. Theory predicts a threshold electron anisotropy for this instability which depends inversely on the electron parallel beta. The simulations show that wave-particle scattering by enhanced whistler fluctuations maintain the initially bi-Maxwellian character of the electron distribution, and that this scattering imposes an upper bound on the electron T-perpendicular to/T-parallel to commensurate with that predicted by linear theory. C1 CALTECH,JET PROP LAB,MS 301460,PASADENA,CA 91109. RP Gary, SP (reprint author), LOS ALAMOS NATL LAB,MS D438,LOS ALAMOS,NM 87545, USA. NR 21 TC 83 Z9 84 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD MAY 1 PY 1996 VL 101 IS A5 BP 10749 EP 10754 DI 10.1029/96JA00323 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ412 UT WOS:A1996UJ41200021 ER PT J AU Northrop, TG Birmingham, TJ AF Northrop, TG Birmingham, TJ TI Equilibrium electric potential of spherical, cylindrical, and planar dust grains moving through a plasma SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article AB The charge on a dust grain in a plasma depends on the plasma parameters and on the grain's velocity through the plasma. Intuition suggests that at high velocity the grain should sweep up equal numbers of both the positive and negative plasma species, and so it should come to zero potential with respect to the plasma. This is in fact not always the case. We have derived the equilibrium potential phi of a small conducting sphere moving at speed w through a plasma of temperature T composed of electrons with charge -e and ions with charge Ze and mass ratio M = m(i)/m(e) and find that for large w the potential goes to the finite value e phi/kT = -1/2[(M - 1)/(M + Z)]. For a conducting cylinder of infinite length in the same plasma, e phi/kT is slightly different owing to the different potential variation outside the grain, but for large cylinder speed the potential goes to the same nonzero limit as the sphere. The case of an infinite, conducting plane is quite different, and values depend on whether there is plasma on one side of the plane or on both. In the latter case, which is most analogous to those of the sphere and cylinder, phi does go to zero for large plane speed. We show equilibrium e\phi\/kT versus w curves for the three elementary shapes, in each instance for an O+ - e(-), H+ - e(-), and ''5m(e)''(+) - e(-) plasma, and comment on characteristics. The last example is a plasma of electrons and ions having the artificially small mass ratio M = 5, of interest because results can be compared with computer simulations of particle dynamics in the presence of a charged grain. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP Northrop, TG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 660,GREENBELT,MD 20771, USA. NR 7 TC 8 Z9 8 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD MAY 1 PY 1996 VL 101 IS A5 BP 10793 EP 10796 DI 10.1029/96JA00459 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ412 UT WOS:A1996UJ41200025 ER PT J AU Hesse, M Birn, J Kuznetsova, MM Dreher, J AF Hesse, M Birn, J Kuznetsova, MM Dreher, J TI A simple model of core field generation during plasmoid evolution SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID GEOMAGNETIC TAIL; EARTHS MAGNETOTAIL; FLUX ROPES; SUBSTORM; MAGNETOSHEATH; CDAW-8; LAYER; SHEET AB Bipolar magnetic field signatures in the far magnetotail observed by the ISEE 3 spacecraft are commonly interpreted as signatures of a passing magnetic bubble, or plasmoid. A large number of such plasmoid-type variations in the north-south component of the magnetic field are accompanied by large core magnetic fields which are directed primarily in the cross-tail direction, indicating a flux rope like structure. Similar signatures are also found in a recent examination of GEOTAIL deep tail data. The fact that more of these flux ropelike plasmoids are encountered in the far tail than closer to the Earth raises the question whether they are the result of an evolution from no or low core fields to high core fields or whether plasmoids without core fields and flux ropes are entirely different entities. We present a model which explains the evolution of a looplike plasmoid in the near tail to a thinner flux rope in the far tail. The transition is accomplished by magnetic reconnection, which progressively connects the plasmoid magnetic field lines to the colder plasma in the low-latitude boundary layer and magnetosheath. The connection leads to a draining of hot plasma from plasmoid field lines and a subsequent collapse due to the plasma pressure reduction. The collapse causes a strong enhancement of any preexisting cross-tail magnetic field component, until a quasi-force-free state is reached. We also present MHD simulations to demonstrate the process. Last, we show that this mechanism call produce core field enhancements beyond the ambient lobe field strength. C1 LOS ALAMOS NATL LAB,SPACE PHYS GRP,LOS ALAMOS,NM 87545. RUHR UNIV BOCHUM,D-4630 BOCHUM,GERMANY. RP Hesse, M (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ELECTRODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Hesse, Michael/D-2031-2012; Kuznetsova, Maria/F-6840-2012 NR 32 TC 24 Z9 24 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD MAY 1 PY 1996 VL 101 IS A5 BP 10797 EP 10804 DI 10.1029/95JA03149 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ412 UT WOS:A1996UJ41200026 ER PT J AU Hesse, M Birn, J Baker, DN Slavin, JA AF Hesse, M Birn, J Baker, DN Slavin, JA TI MHD simulations of the transition of magnetic reconnection from closed to open field lines SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID GEOMAGNETIC TAIL; PLASMOID EVOLUTION; EARTHS MAGNETOTAIL; DISTANT TAIL; RE-CONNEXION; SUBSTORM; COMPUTER; ISEE-3; SHEET; LOBES AB Two- and three-dimensional resistive MHD simulations are used to study the behavior of a dynamic magnetotail model when reconnection proceeds from closed to open field lines. For this purpose, the initial, quasi-static magnetotail configuration is set up for various lobe density values. Initiated by the increase or occurrence of anomalous resistivity, all simulations then exhibit the growth of an unstable tail mode, which leads to neutral line and plasmoid formation. The reconnection process starts in a plasma sheet region of high mass density and progresses to open field lines with much lower plasma density and much lower plasma beta. At the time of transition, drastic changes of typical dynamical parameters occur, involving strongly enhanced electric fields and reconnection rates and the generation of field-aligned currents. Further, typical substorm signatures such as the dipolarization of the magnetic field in the inner regions of the magnetotail appear on very short timescales, comparable to those found in spacecraft observations. It is argued that this behavior should indeed become important during substorm evolution, in support of substorm models based on this transition. C1 UNIV COLORADO, BOULDER, CO 80309 USA. LOS ALAMOS NATL LAB, SPACE & ATMOSPHER SCI GRP, LOS ALAMOS, NM 87545 USA. RP NASA, GODDARD SPACE FLIGHT CTR, ELECTRODYNAM BRANCH, CODE 696, GREENBELT, MD 20771 USA. RI Hesse, Michael/D-2031-2012; Slavin, James/H-3170-2012 OI Slavin, James/0000-0002-9206-724X NR 31 TC 19 Z9 19 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9380 EI 2169-9402 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD MAY 1 PY 1996 VL 101 IS A5 BP 10805 EP 10816 DI 10.1029/95JA02857 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ412 UT WOS:A1996UJ41200027 ER PT J AU Sittler, EC Hartle, RE AF Sittler, EC Hartle, RE TI Triton's ionospheric source: Electron precipitation or photoionization SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID NEPTUNE MAGNETOSPHERE; ENERGETIC PARTICLES; PLASMA OBSERVATIONS; ATMOSPHERE; VOYAGER-2; NITROGEN; VENUS; MODEL AB We have performed an evaluation to determine whether or not Neptune's magnetospheric electrons can provide the ionization of Triton's ionosphere as previously suggested or whether photoionization is the dominant ionization mechanism. Our approach has been to determine the accessibility of magnetospheric electrons to Triton's ionosphere. Using scaling relationships based on Venus and Titan observations, we have developed estimates of the centrifugal, gradient B and E x B drifts. We have computed trajectories of magnetospheric electrons and studied their accessibility to the Triton ionosphere. The following conclusions can be reached from this study: (1) Centrifugal drift delivers electrons to the ionopause. If centrifugal drift is impaired, then electron precipitation is severely limited. (2) Low-energy electrons (E < 5 keV) are lost through E x B drift around the ionopause. (3) At higher electron energy the probability of precipitation increases. If the electron gyroradius is small relative to the ionopause thickness, then at pitch angles similar to 90 degrees grad B drift dominates with trapping of electrons in the ionopause and subsequent exclusion from the ionosphere. At pitch angles 0 degrees and 180 degrees curvature drift dominates, and electrons will precipitate on entry into the ionopause. If the electron gyroradius is large compared to the ionopause thickness, then electrons will precipitate at any pitch angle. Mass loading is estimated to be unimportant at Triton, and this contributes to the importance of E x B drift and the exclusion of low-energy electrons to Triton's ionosphere. Our calculations have intentionally overestimated the effects of centrifugal drift to present the best case for electron precipitation. Although collisions are more important for low-energy electrons (E < 5 keV), we estimate that cross-field diffusion is small for ionopause heights greater than 725 km. At higher electron energies where collisions are less important, the threshold energy above which electrons become untrapped is only dependent upon the ionopause thickness and not collisions. Pressure balance arguments show that the ionopause is thick with Delta(z) > 200 km. A magnetized ionosphere would be equivalent to the high ram pressure case for the Venus interaction. A thick ionopause would contribute to prevention of precipitation of magnetospheric electrons into Triton's ionosphere when E < 50 keV. Although our calculations at the present level of development cannot rule out the importance of electron precipitation as the source of Triton's ionosphere, we suggest that photoionization be considered viable for the production of Triton's ionosphere. RP Sittler, EC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 692,GREENBELT,MD 20771, USA. NR 42 TC 4 Z9 4 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD MAY 1 PY 1996 VL 101 IS A5 BP 10863 EP 10876 DI 10.1029/96JA00398 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ412 UT WOS:A1996UJ41200034 ER PT J AU Nilsson, H Yamauchi, M Eliasson, L Norberg, O Clemmons, J AF Nilsson, H Yamauchi, M Eliasson, L Norberg, O Clemmons, J TI Ionospheric signature of the cusp as seen by incoherent scatter radar SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PARTICLE-PRECIPITATION; MAGNETOSPHERE; BOUNDARY; AURORA AB Measurements with the Sondre Stromfjord incoherent scatter radar, co-ordinated with the observations by the Freja satellite, have been performed during three campaigns, April 1993, February 1994, and May-June 1994. Radar signatures of various types of magnetosheath particle injections in the cusp-cleft region are investigated. The measurement days represent very different geomagnetic conditions, from very quiet to a Kp index of 7+. On three occasions both Freja and the radar detected the cusp. A unique cusp signature is found for a relatively stable cusp, distinguishing it from the many other soft precipitation features seen around noon. The signature includes extremely high electron temperatures in a latitudinally well-defined region with a sharp equatorward border, some F region electron density enhancement, ion outflow, and mainly poleward plasma flow. Enhanced ion temperatures are also seen in the vicinity of, but not exactly coincident with, the electron temperature enhancements. Other dayside precipitation features observed with an intense soft component are narrow arcs, which usually have an accompanying accelerated electron component of several hundred eV to some keV energy. These are typically seen in, or bordering, convection regions where the plasma flow vorticity implies upward field-aligned currents. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. MAX PLANCK INST EXTRATERR PHYS, W-8046 GARCHING, GERMANY. RP Nilsson, H (reprint author), SWEDISH INST SPACE PHYS, BOX 812, S-98128 KIRUNA, SWEDEN. NR 29 TC 32 Z9 32 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD MAY 1 PY 1996 VL 101 IS A5 BP 10947 EP 10963 DI 10.1029/95JA03341 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ412 UT WOS:A1996UJ41200041 ER PT J AU Tsurutani, BT Ho, CM Arballo, JK Smith, EJ Goldstein, BE Neugebauer, M Balogh, A Feldman, WC AF Tsurutani, BT Ho, CM Arballo, JK Smith, EJ Goldstein, BE Neugebauer, M Balogh, A Feldman, WC TI Interplanetary discontinuities and Alfven waves at high heliographic latitudes: Ulysses SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC-FIELD; SOLAR-WIND; STREAMER BELT AB This paper presents the results of the first statistical study of interplanetary directional discontinuities at both low and high heliographic latitudes measured by the Ulysses magnetometer. There is a gradual decrease in the rate of occurrence of interplanetary discontinuities (ROIDs) with increasing radial distance. From 1 to 5 AU, an e(-(r-1)/5) dependence is derived. Much of this decrease is believed to be an artifact due to the discontinuity thickening with decreasing \B\, falling outside the detection criteria. As Ulysses goes from the ecliptic plane to high (-80 degrees) heliographic latitudes, the ROID value increases dramatically. The increase is about a factor of 5 as Ulysses moves from Jupiter at 5 AU to 2.5 AU over the south pole. There is a one-to-one correspondence between high ROID values and high-speed streams. This is particularly dramatic just after the Jovian encounter when there are similar to 25.4-day period corotating streams present. Thus the increase with latitude is primarily due to Ulysses spending an increasing percentage of time within a high-speed stream emanating from the solar coronal hole. High-speed streams are characterized by the presence of nonlinear Alfven waves with peak-to-peak transverse fluctuations as large as \Delta (B) over bar\/\B\ of 1 to 2. Over the south pole, the normalized transverse wave power can be characterized by P = 2.5 x 10(-4)f(-1.6) Hz(-1) and the compressional power 1.8 x 10(-4)f(-1.2) Hz(-1) for frequencies between 10(-5) and 10(-2) Hz. The normalized wave power spectra in different regions of the polar coronal hole streams, from midlatitudes to high heliographic latitudes, appear to be quite similar. The wave power in the ecliptic plane is somewhat lower, perhaps due to contamination from low-speed streams. The Alfven waves in the high-speed stream are found to be propagating outward from the Sun, even at these large heliocentric distances (2.5-5.0 AU). The waves typically have arclike polarizations and conserve field magnitude to first order. Directional (rotational) discontinuities often form the edges of the phase-steepened Alfven waves, thus offering a natural explanation for the high ROID rates within high-speed streams. C1 UNIV LONDON IMPERIAL COLL SCI & TECHNOL,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. RP Tsurutani, BT (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MS 169-506,PASADENA,CA 91109, USA. NR 35 TC 40 Z9 41 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD MAY 1 PY 1996 VL 101 IS A5 BP 11027 EP 11038 DI 10.1029/95JA03479 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ412 UT WOS:A1996UJ41200050 ER PT J AU Seywald, H AF Seywald, H TI Variational solutions for the heat-rate-limited aeroassisted orbital transfer problem SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID MINIMUM ENERGY-LOSS; PLANE-CHANGE; GUIDANCE AB Minimum energy loss trajectories based on Pontryagin's minimum principle are generated for the atmospheric part of an aeroassisted orbital transfer problem, At the initial time all states are given. At the final time the altitude, velocity, and inclination change are prescribed. Additionally, the trajectory is subject to a heating rate limit, which, in the context of optimal control, represents a first-order state inequality constraint. Numerical difficulties implied by the singularly perturbed nature of the problem are avoided by starting the integration in the interior of the trajectory at a point where the heating rate limit is active, The state constraint becomes active always in the form of a state constrained are Nontrivial touch points have not been observed in numerical solutions. C1 NASA,LANGLEY RES CTR,GUIDANCE & CONTROLS BRANCH,HAMPTON,VA 23665. RP Seywald, H (reprint author), ANALYT MECH ASSOCIATES INC,HAMPTON,VA 23666, USA. NR 22 TC 12 Z9 14 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 1996 VL 19 IS 3 BP 686 EP 692 DI 10.2514/3.21675 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA UJ916 UT WOS:A1996UJ91600026 ER PT J AU Burkhart, PD Bishop, RH AF Burkhart, PD Bishop, RH TI Adaptive orbit determination for interplanetary spacecraft SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB The interplanetary orbit determination problem has been traditionally solved using least-squares techniques. Because of the operational limitations of this method, a Kalman filter approach has been proposed for future missions that includes all spacecraft and measurement modeling states in the filter. The goal is to increase the accuracy of the navigation process while utilizing only radiometric (Doppler and range) data. As an extension, an adaptive orbit determination approach (based on the Magill filter bank) has been developed here to process radiometric data. This adaptive approach can be used to systematically determine the operational filter parameters, which are currently selected using ad hoc methods, The Mars Pathfinder mission is utilized to demonstrate the effectiveness of the adaptive filter bank in determining variances for the process and measurement noise parameters based on the tracking data. Error budgets are presented for the range and Doppler cases, which show nongravitational accelerations and solar radiation pressure to be the main error sources. Results for the range case show that the adaptive enhanced filter bank is effective in selecting the noise variances that match those used to generate the data. Results for the Doppler case are not as conclusive, resulting primarily from linearization errors. C1 UNIV TEXAS,DEPT AEROSP ENGN & ENGN MECH,AUSTIN,TX 78712. RP Burkhart, PD (reprint author), CALTECH,JET PROP LAB,TECH STAFF,NAVIGAT & FLIGHT MECH SECT,PASADENA,CA 91109, USA. NR 22 TC 6 Z9 8 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 1996 VL 19 IS 3 BP 693 EP 701 DI 10.2514/3.21676 PG 9 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA UJ916 UT WOS:A1996UJ91600027 ER PT J AU Queen, EM Silverberg, L AF Queen, EM Silverberg, L TI Optimal control, of a rigid body with dissimilar actuators SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article C1 N CAROLINA STATE UNIV,DEPT MECH & AEROSP ENGN,RALEIGH,NC 27695. RP Queen, EM (reprint author), NASA,LANGLEY RES CTR,VEHICLE ANAL BRANCH,HAMPTON,VA 23681, USA. NR 4 TC 2 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 1996 VL 19 IS 3 BP 738 EP 740 DI 10.2514/3.21692 PG 3 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA UJ916 UT WOS:A1996UJ91600043 ER PT J AU Ahearn, DG Crow, SA Simmons, RB Price, DL Noble, JA Mishra, SK Pierson, DL AF Ahearn, DG Crow, SA Simmons, RB Price, DL Noble, JA Mishra, SK Pierson, DL TI Fungal colonization of fiberglass insulation in the air distribution system of a multi-story office building: VOC production and possible relationship to a sick building syndrome SO JOURNAL OF INDUSTRIAL MICROBIOLOGY LA English DT Article DE fungal colonization; fiberglass insulation; Penicillium spp; Cladosporium spp ID CONDITIONING SYSTEMS AB Complaints characteristic of those for sick building syndrome prompted mycological investigations of a modern multi-story office building on the Gulf coast in the Southeastern United States (Houston-Galveston area), The air handling units and fiberglass duct liner of the heating, ventilating and air conditioning system of the building, without a history of catastrophic or chronic water damage, demonstrated extensive colonization with Penicillium spp and Cladosporium herbarum, Although dense fungal growth was observed on surfaces within the heating-cooling system, most air samples yielded fewer than 200 CFU m(-3), Several volatile compounds found in the building air were released also from colonized fiberglass, Removal of colonized insulation from the floor receiving the majority of complaints of mouldy air and continuous operation of the units supplying this floor resulted in a reduction in the number of complaints. C1 INTERFACE RES CORP,KENNESAW,GA. NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,HOUSTON,TX 77058. RP Ahearn, DG (reprint author), GEORGIA STATE UNIV,DEPT BIOL,POB 4010,ATLANTA,GA 30302, USA. NR 17 TC 24 Z9 25 U1 1 U2 5 PU STOCKTON PRESS PI BASINGSTOKE PA HOUNDMILLS, BASINGSTOKE, HAMPSHIRE, ENGLAND RG21 6XS SN 0169-4146 J9 J IND MICROBIOL JI J. Indust. Microbiol. PD MAY PY 1996 VL 16 IS 5 BP 280 EP 285 DI 10.1007/BF01570035 PG 6 WC Biotechnology & Applied Microbiology SC Biotechnology & Applied Microbiology GA UX682 UT WOS:A1996UX68200004 PM 8757941 ER PT J AU Sonnenfeld, G Davis, S Taylor, GR Mandel, AD Konstantinova, IV Lesnyak, A Fuchs, BB Peres, C Tkackzuk, J Schmitt, DA AF Sonnenfeld, G Davis, S Taylor, GR Mandel, AD Konstantinova, IV Lesnyak, A Fuchs, BB Peres, C Tkackzuk, J Schmitt, DA TI Effect of space flight on cytokine production and other immunologic parameters of rhesus monkeys SO JOURNAL OF INTERFERON AND CYTOKINE RESEARCH LA English DT Article ID EXPERIMENT PROGRAM INTERFERON; SHUTTLE; CELLS; RATS AB During a recent flight of a Russian satellite (Cosmos #2229), initial experiments examining the effects of space flight on immunologic responses of rhesus monkeys were performed to gain insight into the effect of space flight on resistance to infection, Experiments were performed on tissue samples taken from the monkeys before and immediately after flight, Additional samples were obtained approximately 1 month after flight for a postflight restraint study, Two types of experiments were carried out throughout this study. The first experiment determined the ability of leukocytes to produce interleukin-l and to express interleukin-2 receptors. The second experiment examined the responsiveness of rhesus bone marrow cells to recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF), Human reagents that cross-reacted with monkey tissue were utilized for the bulk of the studies, Results from both studies indicated that there were changes in immunologic function attributable to space flight, Interleukin-l production and the expression of interleukin-2 receptors was decreased after space flight. Bone marrow cells from flight monkeys showed a significant decrease in their response to GM-CSF compared with the response of bone marrow cells from nonflight control monkeys, These results suggest that the rhesus monkey may be a useful surrogate for humans in future studies that examine the effect of space flight on immune response, particularly when conditions do not readily permit human study. C1 UNIV LOUISVILLE,SCH MED,DEPT MICROBIOL & IMMUNOL,LOUISVILLE,KY 40292. UNIV LOUISVILLE,SCH MED,DEPT BIOL & BIOPHYS SCI,LOUISVILLE,KY 40292. UNIV LOUISVILLE,SCH DENT,DEPT BIOL & BIOPHYS SCI,LOUISVILLE,KY 40292. UNIV LOUISVILLE,SCH DENT,DEPT MICROBIOL & IMMUNOL,LOUISVILLE,KY 40292. NASA,JOHNSON SPACE CTR,HOUSTON,TX 77058. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RUSSIAN ACAD SCI,INST BIOMED PROBLEMS,MOSCOW,RUSSIA. RUSSIAN ACAD MED SCI,INST HUMAN MORPHOL,MOSCOW,RUSSIA. UNIV TOULOUSE 3,CHU RANGUEIL,IMMUNOL LAB,F-31062 TOULOUSE,FRANCE. RP Sonnenfeld, G (reprint author), CAROLINAS MED CTR,DEPT GEN SURG RES,POB 32861,CHARLOTTE,NC 28232, USA. NR 26 TC 22 Z9 23 U1 0 U2 0 PU MARY ANN LIEBERT INC PUBL PI LARCHMONT PA 2 MADISON AVENUE, LARCHMONT, NY 10538 SN 1079-9907 J9 J INTERF CYTOK RES JI J. Interferon Cytokine Res. PD MAY PY 1996 VL 16 IS 5 BP 409 EP 415 DI 10.1089/jir.1996.16.409 PG 7 WC Biochemistry & Molecular Biology; Cell Biology; Immunology SC Biochemistry & Molecular Biology; Cell Biology; Immunology GA UM131 UT WOS:A1996UM13100010 PM 8727082 ER PT J AU Guelachvili, G Birk, M Borde, CJ Brault, JW Brown, LR Carli, B Cole, ARH Evenson, KM Fayt, A Hausamann, D Johns, JWC Kauppinen, J Kou, Q Maki, AG Rao, KN Toth, RA Urban, W Valentin, A Verges, J Wagner, G Wappelhorst, MH Wells, JS Winnewisse, BP Winnewisser, M AF Guelachvili, G Birk, M Borde, CJ Brault, JW Brown, LR Carli, B Cole, ARH Evenson, KM Fayt, A Hausamann, D Johns, JWC Kauppinen, J Kou, Q Maki, AG Rao, KN Toth, RA Urban, W Valentin, A Verges, J Wagner, G Wappelhorst, MH Wells, JS Winnewisse, BP Winnewisser, M TI High resolution wavenumber standards for the infrared - Technical report SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID HETERODYNE FREQUENCY MEASUREMENTS; (CO)-C-12-O-16 LASER TRANSITIONS; ACCURATE ROTATIONAL-CONSTANTS; CARBONYL SULFIDE; LINE POSITIONS; MOLECULAR-CONSTANTS; MU-M; CALIBRATION TABLES; FUNDAMENTAL-BAND; DIODE-LASER AB The calibration of high resolution infrared spectra is generally more precise than accurate. This is the case even when they are recorded with Fourier transform interferometers. The present document aims at improving the accuracy of wavenumber measurements in the infrared by recommending a selection of spectral lines as wavenumber standards for absolute calibration in the range from about 4 to about 7000 cm(-1). The uncertainties of these wavenumber standards range from 4+/-1x10(-3) to +/-1x10(-6) cm(-1). Sources of frequency standards, on which the wavenumber determinations are based, are also given. C1 DLR,INST OPTOELECTR,D-82234 WESSELING,GERMANY. UNIV PARIS 13,PHYS LASERS LAB,F-93430 VILLETANEUSE,FRANCE. CALTECH,JET PROP LAB,PASADENA,CA 91109. CNR,IST RIC ONDE ELETTROMAGNET,I-50127 FLORENCE,ITALY. UNIV WESTERN AUSTRALIA,SCH CHEM,NEDLANDS,WA 6009,AUSTRALIA. NATL INST STAND & TECHNOL,DIV TIME & FREQUENCY,BOULDER,CO 80303. UNIV CATHOLIQUE LOUVAIN,MOLEC SPECT LAB,B-1348 LOUVAIN,BELGIUM. NATL RES COUNCIL CANADA,STEACIE INST MOLEC SCI,OTTAWA,ON K1A 0R6,CANADA. UNIV TURKU,DEPT APPL PHYS,FIN-20500 TURKU,FINLAND. UNIV WASHINGTON,DEPT CHEM,SEATTLE,WA 98195. OHIO STATE UNIV,DEPT PHYS,COLUMBUS,OH 43210. UNIV BONN,INST ANGEW PHYS,D-53115 BONN,GERMANY. UNIV PARIS 06,CNRS UPR 136,PHYS MOLEC LAB,F-75252 PARIS 05,FRANCE. LAB AIMEE COTTON,F-91405 ORSAY,FRANCE. UNIV GIESSEN,INST PHYS CHEM,D-35392 GIESSEN,GERMANY. NOAA,AERON LAB REAL5,BOULDER,CO 80303. RP Guelachvili, G (reprint author), UNIV PARIS 11,MOLEC PHYS LAB,CNRS UPR 136,BATIMENT 350,F-91405 ORSAY,FRANCE. NR 96 TC 36 Z9 36 U1 1 U2 10 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD MAY PY 1996 VL 177 IS 1 BP 164 EP 179 DI 10.1006/jmsp.1996.0131 PG 16 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA UP553 UT WOS:A1996UP55300022 ER PT J AU Allen, B Norman, HA Vincent, JS Chappelle, EW AF Allen, B Norman, HA Vincent, JS Chappelle, EW TI Preparation of carotenoid enriched vesicles of monogalactosyldiacylglycerol and digalactosyldiacylglycerol for use in Raman studies to investigate leaf canopy damage SO JOURNAL OF PLANT PHYSIOLOGY LA English DT Article DE Glycine max L Merr; bilayers; carotenoids; galactolipids; model membrane systems; order/disorder; thermotropic profiles ID QUANTITATIVE-DETERMINATION; INFRARED-SPECTROSCOPY; ACID; BILAYERS; BEHAVIOR; SYSTEMS; LEAVES; CHAINS AB New methods were developed for the semi-preparative isolation of galactolipids (GL) monogalactosyldiacylglycerol (MGDG), and digalactosyldiacylglycerol (DGDG) from Glycine max L. Merr. (soybean) leaf tissue. Model membranes composed of isolated MGDG and DGDG were enriched with the natural carotenoid, lutein and subjected to vibrational spectroscopic analysis as a function of temperature. The carotenoid was introduced to provide a resonance Raman (rR) indicator that would be sensitive to the macroscopic environment of the lipid assembly. The preliminary Infra-red (IR), Raman and rR spectra in the ordered gel phase and in the relatively disordered liquid crystalline (lc) phase of the phospholipid (PL) model membrane system distearoylphosphatidylcholine (DSPC) and spectra of the GL model membrane systems, that span the temperature range of -30 degrees C to 0 degrees C, indicate that vesicles prepared by this method provide relevant model membrane systems. C1 ARS,WEED SCI LAB,USDA,BELTSVILLE,MD 20705. NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771. RP Allen, B (reprint author), UNIV MARYLAND,CATONSVILLE,MD 21228, USA. NR 21 TC 2 Z9 2 U1 0 U2 3 PU GUSTAV FISCHER VERLAG PI STUTTGART PA WOLLGRASWEG 49, D-70599 STUTTGART, GERMANY SN 0176-1617 J9 J PLANT PHYSIOL JI J. Plant Physiol. PD MAY PY 1996 VL 148 IS 3-4 BP 413 EP 417 PG 5 WC Plant Sciences SC Plant Sciences GA UT416 UT WOS:A1996UT41600024 ER PT J AU McMurtrey, JE Chappelle, EW Kim, MS Corp, LA Daughtry, CST AF McMurtrey, JE Chappelle, EW Kim, MS Corp, LA Daughtry, CST TI Blue-green fluorescence and visible-infrared reflectance of corn (Zea mays L) grain for in situ field detection of nitrogen supply SO JOURNAL OF PLANT PHYSIOLOGY LA English DT Article DE Zea mays; fluorescence; grain; reflectance; vegetation stress ID LASER-INDUCED FLUORESCENCE; EMISSION-SPECTRA; PLANT-LEAVES AB The sensing of spectral attributes of corn (Zea mays L.) grain from site specific areas of the field during the harvest process may be useful in managing agronomic inputs and production practices on those areas of the field in subsequent growing seasons. Eight levels of nitrogen (N) fertilization were applied to field grown corn at Beltsville, Maryland. These N treatments produced a range of chlorophyll levels, biomass and physiological condition in the live plant canopies. After harvest. spectra were obtained in the laboratory on whole grain samples. Fluorescence emissions were acquired from 400 to 600 nm and percent reflectance were measured in the visible (VIS) near infrared (NIR) and mid-infrared (MIR) regions from 400 nm to 2400 nm. A ultraviolet (UV) excitation band centered at 385 nm was the most effective in producing fluorescence emission differences in the blue-green region of the fluorescence spectrum with maxima centered from 430-470 nm in the blue and with an intense shoulder centered at around 530-560 nm in the green region. Reflectance showed the most spectral differences in the NIR and MIR (970-2330 nm) regions. C1 NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771. SCI SYST & APPL INC,LANHAM,MD 20706. RP McMurtrey, JE (reprint author), ARS,USDA,REMOTE SENSING RES LAB,10300 BALTIMORE AVE,BELTSVILLE,MD 20705, USA. NR 21 TC 6 Z9 6 U1 0 U2 5 PU GUSTAV FISCHER VERLAG PI STUTTGART PA WOLLGRASWEG 49, D-70599 STUTTGART, GERMANY SN 0176-1617 J9 J PLANT PHYSIOL JI J. Plant Physiol. PD MAY PY 1996 VL 148 IS 5 BP 509 EP 514 PG 6 WC Plant Sciences SC Plant Sciences GA UV718 UT WOS:A1996UV71800001 ER PT J AU Carter, GA Cibula, WG Miller, RL AF Carter, GA Cibula, WG Miller, RL TI Narrow-band reflectance imagery compared with thermal imagery for early detection of plant stress SO JOURNAL OF PLANT PHYSIOLOGY LA English DT Article DE Pinus taeda; Pinus elliottii; plant stress; diuron; bromacil; chlorosis; canopy reflectance; canopy temperature; narrow-band imagery ID FOREST-DECLINE; RED EDGE; LEAF REFLECTANCE; CHLOROPHYLL FLUORESCENCE; SPECTRAL MEASUREMENTS; SLASH PINE; BLUE-SHIFT; LEAVES; PHOTOSYNTHESIS; TREES AB A field experiment compared plant stress detection by narrow-band reflectance and ratio images with thermal infrared images. Stress was induced in a mixed stand of 5 year old loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) by a soil application of diuron (DCMU) on 22 August followed by bromacil on 19 September, 1994. Herbicide-induced stress was first indicated on 24 and 26 September by significant (p less than or equal to 0.05) decreases in photosynthesis and the ratio of variable to maximum fluorescence (F-v/F-m), respectively. Stress was first detected remotely on 5 October by 694 +/- 3 nm reflectance imagery and its ratio with reflectance at 760 +/- 5 nm (p less than or equal to 0.05). This reflectance increase was detected at least IG days prior to the first visible signs of damage, as quantified by the CIE color coordinate u', that occurred between 21 and 26 October. Reflectance images at 670 +/- 5 nm, 700 +/- 5 nm and 760 +/- 5 nm first detected stress on 21 October 12 October and 20 December, respectively. Canopy temperature as indicated by imagery in the 8 to 12 mu m band never differed significantly between herbicide-treated and control plots. This resulted from the close coupling of leaf temperatures with air temperature, and the tendency of wind and environmental moisture to equalize temperatures among treatments. The high sensitivity to stress of reflectance imagery at 694 +/- 3 nm supports similar conclusions of earlier work, and indicates that imagery in the 690 to 700 nm band is far superior to thermal imagery for the early and pre-visual detection of stress in pine. RP Carter, GA (reprint author), NASA,EARTH OBSERVAT RES OFF,BAY ST LOUIS,MS 39529, USA. NR 48 TC 71 Z9 79 U1 1 U2 16 PU GUSTAV FISCHER VERLAG PI STUTTGART PA WOLLGRASWEG 49, D-70599 STUTTGART, GERMANY SN 0176-1617 J9 J PLANT PHYSIOL JI J. Plant Physiol. PD MAY PY 1996 VL 148 IS 5 BP 515 EP 522 PG 8 WC Plant Sciences SC Plant Sciences GA UV718 UT WOS:A1996UV71800002 ER PT J AU Rodi, PE Emami, S Trexler, CA AF Rodi, PE Emami, S Trexler, CA TI Unsteady pressure behavior in a Ramjet/Scramjet inlet SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Mean and time-accurate pressures have been measured in the inlet of a dual-mode, ramjet/scramjet configuration. This configuration was designed for low hypersonic Mach number operation using a hydrocarbon based fuel. The time accurate measurements are presented for inlets operating at maximum permissible back-pressure during and after inlet unstart. C1 LOCKHEED ENGN & SCI CO,NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NASA,LANGLEY RES CTR,GAS DYNAM DIV,HAMPTON,VA 23681. RP Rodi, PE (reprint author), NATL RES COUNCIL,NASA,LANGLEY RES CTR,GAS DYNAM DIV,M-S 168,HAMPTON,VA 23681, USA. NR 16 TC 25 Z9 31 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 1996 VL 12 IS 3 BP 486 EP 493 DI 10.2514/3.24061 PG 8 WC Engineering, Aerospace SC Engineering GA UL423 UT WOS:A1996UL42300006 ER PT J AU Ahuja, JK Kumar, A Singh, DJ Tiwari, SN AF Ahuja, JK Kumar, A Singh, DJ Tiwari, SN TI Simulation of shock-induced combustion past blunt projectiles using shock-fitting technique SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Two-dimensional axisymmetric, reacting viscous how over blunt projectiles is computed to study shock-induced combustion at Mach 5.11 and 6.46 in hydrogen-air mixture. A finite difference, shock-fitting method is used to solve the complete set of Navier-Stokes and species conservation equations. In this approach, the bow shock represents a boundary of the computational domain and is treated as a discontinuity across which Rankine-Hugoniot conditions are applied. All interior details of the flow such as compression waves, reaction front, and the wall boundary layer are captured automatically in the solution. Since the shock-fitting approach reduces the amount of artificial dissipation, all intricate details of the flow are captured much more clearly than has been possible with the shock-capturing approach. This has allowed an improved understanding of the physics of shock-induced combustion over blunt projectiles and the numerical results can now be explained more readily with a one dimensional wave-interaction model. C1 NASA,LANGLEY RES CTR,GAS DYNAM DIV,HAMPTON,VA 23681. ANALYT SERV & MAT INC,ANALYT SECT,HAMPTON,VA 23666. RP Ahuja, JK (reprint author), OLD DOMINION UNIV,DEPT ENGN MECH,NORFOLK,VA 23529, USA. NR 26 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 1996 VL 12 IS 3 BP 518 EP 526 DI 10.2514/3.24065 PG 9 WC Engineering, Aerospace SC Engineering GA UL423 UT WOS:A1996UL42300010 ER PT J AU Zhao, J Isaac, KM Pellett, GL AF Zhao, J Isaac, KM Pellett, GL TI Global characteristics and structure of hydrogen-air counterflow diffusion flames SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB A model based on similarity transformation, for the nitrogen diluted, H-2-air opposed-jet laminar counterflow diffusion flame (CFDF), was developed independently of earlier models, and numerically solved to study flame location and flame structure and extinction limits. Numerical stiffness is handled by a special treatment of the species production term. Flame location with respect to the stagnation plane is identified as an important parameter that governs H-2-air diffusion flames, and physical explanations are given to show how flame location is affected by fuel dilution, strain rate, and Lewls number. Results show very good agreement with experimental extinction conditions. The effect of thermal diffusion on the flame is found to be negligible. The simpler, constant Lewis number model produced extinction at half the strain rate compared to the species dependent Lewis number model. The hydrogen-air CFDF exhibits several characteristics not observed for hydrocarbon flames. The underlying reasons are discussed in terms of the fluid dynamic and chemical kinetic aspects. C1 NASA,LANGLEY RES CTR,HYPEERSON APPLICAT PROP BRANCH,HAMPTON,VA 23681. RP Zhao, J (reprint author), UNIV MISSOURI,AEROPROP LAB,ROLLA,MO 65409, USA. NR 22 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 1996 VL 12 IS 3 BP 534 EP 542 DI 10.2514/3.24067 PG 9 WC Engineering, Aerospace SC Engineering GA UL423 UT WOS:A1996UL42300012 ER PT J AU Sambamurthi, JK AF Sambamurthi, JK TI Al2O3 collection and sizing from solid rocket motor plumes SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/ASME/SAE/ASEE 31st Joint Propulsion Conference and Exhibit CY JUL 10-12, 1995 CL SAN DIEGO, CA SP AIAA, ASME, SAE, ASEE ID ALUMINUM-OXIDE PARTICLES AB A unique dart system has been designed and built to collect aluminum oxide particles from the plumes of large-scale solid rocket motors, such as the Space Shuttle redesigned solid rocket motor (RSRM). The capability of this system to collect clean samples from both the vertically fired modified NASA (MNASA) (18.3% scaled version of the RSRM) motors and the horizontally fired RSRM motor has been demonstrated. The particle mass-averaged diameters d(43) measured from the samples for the different motors, ranged from 8 to 11 mu m and were independent of the dart collection surface and the elapsed time during motor burn. The measured d(43) results agreed well with those calculated using the industry standard Hermsen's correlation within the standard deviation of the correlation. For each of the samples analyzed from both MNASA and RSRM motors, the distribution of the cumulative mass fraction of the plume oxide particles as a function of the particle diameter was best described by a monomodal log-normal distribution with a standard deviation between 0.13-0.17. This distribution agreed well with the theoretical prediction by Salita using the one-dimensional three phase code for the RSRM motor at the nozzle exit plane; this seems to confirm that droplet collision-coalescence removes most of the smoke mass from the plume flowfield. RP Sambamurthi, JK (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,M-S ED33,HUNTSVILLE,AL 35812, USA. NR 14 TC 6 Z9 6 U1 0 U2 5 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 1996 VL 12 IS 3 BP 598 EP 604 DI 10.2514/3.24075 PG 7 WC Engineering, Aerospace SC Engineering GA UL423 UT WOS:A1996UL42300020 ER PT J AU Dorney, DJ GundyBurlet, K AF Dorney, DJ GundyBurlet, K TI Hot-streak clocking effects in a 1-1/2 stage turbine SO JOURNAL OF PROPULSION AND POWER LA English DT Article C1 NASA,AMES RES CTR,DESIGN CYCLES TECHNOL BRANCH,MOFFETT FIELD,CA 94035. RP Dorney, DJ (reprint author), WESTERN MICHIGAN UNIV,DEPT MECH & AERONAUT ENGN,KALAMAZOO,MI 49008, USA. NR 3 TC 18 Z9 19 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 1996 VL 12 IS 3 BP 619 EP 620 DI 10.2514/3.24080 PG 2 WC Engineering, Aerospace SC Engineering GA UL423 UT WOS:A1996UL42300025 ER PT J AU Mishchenko, MI Travis, LD Mackowski, DW AF Mishchenko, MI Travis, LD Mackowski, DW TI T-matrix computations of light scattering by nonspherical particles: A review SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article; Proceedings Paper CT Workshop on Light Scattering by Non-Spherical Particles CY MAY 02-03, 1995 CL FREE UNIV AMSTERDAM, AMSTERDAM, NETHERLANDS SP Het Leids Kerkhoven Bosscha fonds HO FREE UNIV AMSTERDAM ID CLASSICAL ELECTROMAGNETIC SCATTERING; AXIALLY-SYMMETRICAL PARTICLES; ELONGATED DIELECTRIC OBJECTS; BOUNDARY-CONDITION METHOD; SIZE SHAPE DISTRIBUTIONS; NULL FIELD APPROACH; POLARIZED-LIGHT; ARBITRARY CONFIGURATION; TSCHEBYSCHEFF PARTICLES; SPHEROIDAL PARTICLES AB We review the current status of Waterman's T-matrix approach which is one of the most powerful and widely used tools for accurately computing light scattering by nonspherical particles, both single and composite, based on directly solving Maxwell's equations. Specifically, we discuss the analytical method for computing orientationally-averaged light-scattering characteristics for ensembles of nonspherical particles, the methods for overcoming the numerical instability in calculating the T matrix for single nonspherical particles with large size parameters and/or extreme geometries, and the superposition approach for computing light scattering by composite/aggregated particles. Our discussion is accompanied by multiple numerical examples demonstrating the capabilities of the T-matrix approach and showing effects of nonsphericity of simple convex particles (spheroids) on light scattering. C1 AUBURN UNIV, DEPT MECH ENGN, AUBURN, AL 36849 USA. RP NASA, GODDARD INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Mackowski, Daniel/K-1917-2013; Mishchenko, Michael/D-4426-2012 NR 182 TC 541 Z9 554 U1 7 U2 61 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 EI 1879-1352 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD MAY PY 1996 VL 55 IS 5 BP 535 EP 575 DI 10.1016/0022-4073(96)00002-7 PG 41 WC Optics; Spectroscopy SC Optics; Spectroscopy GA UN386 UT WOS:A1996UN38600002 ER PT J AU Mishchenko, MI Mackowski, DW AF Mishchenko, MI Mackowski, DW TI Electromagnetic scattering by randomly oriented bispheres: Comparison of theory and experiment and benchmark calculations SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article; Proceedings Paper CT Workshop on Light Scattering by Non-Spherical Particles CY MAY 02-03, 1995 CL FREE UNIV AMSTERDAM, AMSTERDAM, NETHERLANDS SP Het Leids Kerkhoven Bosscha fonds HO FREE UNIV AMSTERDAM ID 2 DIELECTRIC SPHERES; POLARIZED-LIGHT; PARTICLES; MATRIX; ELEMENTS AB A good quantitative agreement is found between laboratory measurements of the scattering matrix for a randomly oriented latex bisphere with touching, nearly identical micron-sized components and theoretical computations using the T-matrix method. Our comparison of theory and experiment provides an additional validation of the computational method and also demonstrates that polarization measurements of light scattering can be employed as an accurate particle sizing technique. The T-matrix method is used to tabulate light scattering properties of two different kinds of randomly oriented bispheres with touching and separated components. Because of high accuracy, our computations can serve as benchmarks. C1 AUBURN UNIV, DEPT MECH ENGN, AUBURN, AL 36849 USA. RP NASA, GODDARD INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Mackowski, Daniel/K-1917-2013; Mishchenko, Michael/D-4426-2012 NR 27 TC 25 Z9 25 U1 0 U2 6 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 EI 1879-1352 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD MAY PY 1996 VL 55 IS 5 BP 683 EP 694 DI 10.1016/0022-4073(96)00011-8 PG 12 WC Optics; Spectroscopy SC Optics; Spectroscopy GA UN386 UT WOS:A1996UN38600011 ER PT J AU Wercinski, PF AF Wercinski, PF TI Mars sample return: A direct and minimum-risk design SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Current NASA strategy for Mars exploration is to seek simpler and more reliable missions with focused science objectives. This requirement has made untenable most previously proposed Mars sample return missions. The mission proposed here achieves a simplified mission profile by leveraging interplanetary trajectory design, limiting surface science operations, and using advanced propulsion and thermal protection systems. The fast mini direct Mars sample return mission presented could bring back a 0.5-kg sample from the surface of Mars with a total mission duration of less than 1.5 Earth years using a single, medium-lift launch vehicle. The mission constraints require an aggressive design that dictates the use of advanced storable liquid propulsion systems, high-performance thermal protection system materials, and limited spacecraft design mass margins. The key elements are detailed for a mission that eliminates the some of the high-risk operations that were a part of previously proposed Mars sample return missions that used propulsive insertion into orbit at Mars, complex rover operations on the surface, orbit rendezvous, and in-orbit sample transfers. RP Wercinski, PF (reprint author), NASA,AMES RES CTR,SPACE TECHNOL DIV,MOFFETT FIELD,CA 94035, USA. NR 23 TC 16 Z9 16 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1996 VL 33 IS 3 BP 381 EP 385 DI 10.2514/3.26771 PG 5 WC Engineering, Aerospace SC Engineering GA UQ303 UT WOS:A1996UQ30300011 ER PT J AU Wang, TS McConnaughey, P Chen, YS Warsi, S AF Wang, TS McConnaughey, P Chen, YS Warsi, S TI Computational pollutant environment assessment from propulsion-system testing SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID TURBULENT; COMBUSTION; FLAMES AB An asymptotic plume growth method based on a time-accurate three-dimensional computational fluid dynamics formulation has been developed to assess the exhaust-plume pollutant environment from a stimulate RD-170 engine hot-fire test on the F1 Test Stand at Marshall Space Flight Center. Researchers have long known that rocket-engine hot firing has the potential for forming thermal nitric oxides, as well as producing carbon monoxide when hydrocarbon fuels are used. Because of the complex physics involved, most attempts to predict the pollutant emissions from ground-based engine testing have used simplified methods, which may grossly underpredict and/or overpredict the pollutant formations in a test environment. The objective of this work has been to develop a computational fluid dynamics-based methodology that replicates the underlying test-stand flow physics to accurately and efficiently assesses pollutant emissions from ground-based rocket-engine testing. A nominal RD-170 engine hot-fire test was computed, and pertinent test-stand flow physics was captured. The predicted total emission rates compared reasonably well with those of the existing hydrocarbon engine hot-firing test data. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,FLUID DYNAM ANAL BRANCH,HUNTSVILLE,AL 35812. ENGN SCI INC,HUNTSVILLE,AL 35805. SVERDRUP TECHNOL INC,HUNTSVILLE,AL 35806. RP Wang, TS (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,COMPUTAT ANAL TEAM,HUNTSVILLE,AL 35812, USA. NR 34 TC 8 Z9 8 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1996 VL 33 IS 3 BP 386 EP 392 DI 10.2514/3.26772 PG 7 WC Engineering, Aerospace SC Engineering GA UQ303 UT WOS:A1996UQ30300012 ER PT J AU Wu, CC Lake, MS AF Wu, CC Lake, MS TI Multicriterion preliminary design of a tetrahedral truss platform SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB An efficient method is presented for multicriterion preliminary design and demonstrated iol a tetrahedral truss platform. The method requires minimal analysis effort and permits rapid estimation of optimized truss behavior. A 14-m-diam, three-ring truss platform represents a reflector support structure for space-based science spacecraft. Truss members are grouped by truss ring and position, Design variables are tile cross-sectional area of all members in a group, send are integer multiples of the minimum member area. Nonstructural mass represents the node and joint hardware used for assembly of the truss structure. Taguchi methods are used to identify key points in the set of Pareta-optimal designs, which are the trusses with maximum frequency, minimum mass, and maximum frequency-to-mass ratio, Low-order polynomial curve fits through tile key points are used to approximate the behavior of the full set of Pareto-optimal designs. The resulting Pareto-optimal design curve is used to predict Frequency and mass for optimized trusses. Performance improvements are plotted ill frequency-mass (criterion) space and compared with results for uniform trusses. Application of constraints to the criteria and sensitivity to constraint variation are demonstrated. RP Wu, CC (reprint author), NASA,LANGLEY RES CTR,STRUCT DIV,HAMPTON,VA 23681, USA. NR 12 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1996 VL 33 IS 3 BP 410 EP 415 PG 6 WC Engineering, Aerospace SC Engineering GA UQ303 UT WOS:A1996UQ30300015 ER PT J AU LeeGlauser, GJ Ahmadi, G Layton, JB AF LeeGlauser, GJ Ahmadi, G Layton, JB TI Satellite active and passive vibration control during liftoff SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID SYSTEMS AB The feasibility of active and passive vibration control systems for suppressing the transfer of orbiter vibration energy to its payload during liftoff is studied, A simple five-degree-of-freedom lump parameter model of a satellite is considered, and the performances of active and passive vibration control systems are evaluated and compared. Effectiveness of various vibration control systems for protection of the Space Shuttle payload during liftoff are analyzed. Peak responses of the satellite with active and passive vibration control systems are compared with those in the absence of-vibration control systems. The results show that properly designed passive and active vibration control systems are highly effective in reducing the liftoff vibration to its payload. C1 CLARKSON UNIV,DEPT MECH & AERONAUT ENGN,POTSDAM,NY 13699. RP LeeGlauser, GJ (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 15 TC 8 Z9 8 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1996 VL 33 IS 3 BP 428 EP 432 DI 10.2514/3.26778 PG 5 WC Engineering, Aerospace SC Engineering GA UQ303 UT WOS:A1996UQ30300018 ER PT J AU delaCruz, CP Hastings, DE Fergusson, D Hillard, B AF delaCruz, CP Hastings, DE Fergusson, D Hillard, B TI Data analysis and model comparison for Solar Array Module Plasma Interactions Experiment SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID ARCING RATES AB Analysis of the Salar Array Module Plasma Interactions Experiment flight data from STS-62 tvas conducted to examine the relationships between the are rate and the various solar-cell properties, environmental variables, and solar-cell parameters, The data indicate the existence of a critical ion flux, a critical neutral density, a threshold voltage for arcing ao occur, and scaling of the are rate with work function. C1 NASA, LEWIS RES CTR, SPACE ENVIRONM INTERACT BRANCH, CLEVELAND, OH 44135 USA. RP delaCruz, CP (reprint author), MIT, DEPT AERONAUT & ASTRONAUT, 77 MASSACHUSETTS AVE, CAMBRIDGE, MA 02139 USA. OI , /0000-0003-4421-5110 NR 13 TC 7 Z9 7 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1996 VL 33 IS 3 BP 438 EP 446 PG 9 WC Engineering, Aerospace SC Engineering GA UQ303 UT WOS:A1996UQ30300020 ER PT J AU Wood, WA Thompson, RA Eberhardt, S AF Wood, WA Thompson, RA Eberhardt, S TI Dual-code solution strategy for hypersonic flows SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article C1 UNIV WASHINGTON,DEPT AERONAUT & ASTRONAUT,SEATTLE,WA 98195. RP Wood, WA (reprint author), NASA,LANGLEY RES CTR,GAS DYNAM DIV,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 16 TC 1 Z9 1 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1996 VL 33 IS 3 BP 449 EP 451 DI 10.2514/3.26782 PG 3 WC Engineering, Aerospace SC Engineering GA UQ303 UT WOS:A1996UQ30300022 ER PT J AU Gupta, RN AF Gupta, RN TI Reevaluation of flight-derived surface recombination-rate expressions for oxygen and nitrogen SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article RP Gupta, RN (reprint author), NASA,LANGLEY RES CTR,GAS DYNAM DIV,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 13 TC 7 Z9 7 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1996 VL 33 IS 3 BP 451 EP 453 DI 10.2514/3.26783 PG 3 WC Engineering, Aerospace SC Engineering GA UQ303 UT WOS:A1996UQ30300023 ER PT J AU Choi, SR Salem, JA AF Choi, SR Salem, JA TI Preloading technique in dynamic fatigue testing of class and ceramics with an indentation flaw system SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID BRITTLE AB The solution of fatigue strength as a function of preloading in dynamic fatigue testing was obtained numerically for an indentation flaw system. The dynamic fatigue strength is dependent on preloading and fatigue parameter (n). The effect of preloading on dynamic fatigue strength decreases with increasing fatigue parameter: for n greater than or equal to 20 the effect is negligible up to a preloading of 90%. The solution was verified by dynamic fatigue experiments conducted with soda-lime glass and alumina specimens with as-indented flaws in room-temperature distilled water. The result indicates that one can apply a preloading corresponding up to 90% of fatigue strength for most glass and ceramic materials with no change in fatigue strength, resulting in a dramatic saving of testing time. C1 CLEVELAND STATE UNIV,CLEVELAND,OH 44115. RP Choi, SR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 15 TC 7 Z9 7 U1 0 U2 2 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD MAY PY 1996 VL 79 IS 5 BP 1228 EP 1232 DI 10.1111/j.1151-2916.1996.tb08577.x PG 5 WC Materials Science, Ceramics SC Materials Science GA UM323 UT WOS:A1996UM32300013 ER PT J AU Charron, CS Cantliffe, DJ Wheeler, RM Manukian, A Heath, RR AF Charron, CS Cantliffe, DJ Wheeler, RM Manukian, A Heath, RR TI A system and methodology for measuring volatile organic compounds produced by hydroponic lettuce in a controlled environment SO JOURNAL OF THE AMERICAN SOCIETY FOR HORTICULTURAL SCIENCE LA English DT Article DE (Z)-3-hexenal; (Z)-3-hexenol; (Z)-3-hexenyl acetate ID POSSIBLE INSECT ATTRACTANTS; EMISSION RATES; IDENTIFICATION; COMPONENTS; PLANTS AB A system and methodology were developed for the nondestructive qualitative and quantitative analysis of volatile emissions from hydroponically grown 'Waldmann's Green' leaf lettuce (Lactuca sativa L.). Photosynthetic photon flux (PPF), photoperiod, and temperature were automatically controlled and monitored in a growth chamber modified for the collection of plant volatiles. The lipoxygenase pathway products (Z)-3-hexenol, (Z)-3-hexenol, and (Z)-3-hexenyl acetate were emitted by lettuce plants after the transition from the light period to the dark period, The volatile collection system developed in this study enabled measurements of volatiles emitted by intact plants, from planting to harvest, under controlled environmental conditions. C1 NASA,KENNEDY SPACE CTR,FL 32899. USDA ARS,GAINESVILLE,FL 32604. RP Charron, CS (reprint author), UNIV FLORIDA,DEPT HORT SCI,GAINESVILLE,FL 32611, USA. RI Barickman, Thomas/I-6993-2012 NR 20 TC 8 Z9 9 U1 1 U2 6 PU AMER SOC HORTICULTURAL SCIENCE PI ALEXANDRIA PA 701 NORTH SAINT ASAPH STREET, ALEXANDRIA, VA 22314-1998 SN 0003-1062 J9 J AM SOC HORTIC SCI JI J. Am. Soc. Hortic. Sci. PD MAY PY 1996 VL 121 IS 3 BP 483 EP 487 PG 5 WC Horticulture SC Agriculture GA UG065 UT WOS:A1996UG06500025 PM 11539353 ER PT J AU Charron, CS Cantliffe, DJ Wheeler, RM Manukian, A Heath, RR AF Charron, CS Cantliffe, DJ Wheeler, RM Manukian, A Heath, RR TI Photosynthetic photon flux, photoperiod, and temperature effects on emissions of (Z)-3-hexenal, (Z)3-hexenol, and (Z)-3-hexenyl acetate from lettuce SO JOURNAL OF THE AMERICAN SOCIETY FOR HORTICULTURAL SCIENCE LA English DT Article DE controlled environments ID LEAVES; SYSTEM AB To investigate the effects of environment on plant volatile emissions, 'Waldmann's Green' leaf lettuce was cultivated under different levels of photosynthetic photon flux (PPF) photoperiod, and temperature, A modified growth chamber was used to sample plant volatile emissions nondestructively, over time, and under controlled conditions, Total volatile emission rates were significantly higher from lettuce cultivated under PPF of 360 or 200 mu mol . m(-1). s(-1) compared to 105 mu mol . m(-2). s(-1), and significantly higher under a 16-h photoperiod than an 8-h photoperiod, No differences were detected among emission rates from different temperature treatments, In controlled environments, emissions could be regulated by adjusting environmental conditions accordingly. C1 NASA, KENNEDY SPACE CTR, FL 32899 USA. USDA ARS, GAINESVILLE, FL 32604 USA. RP Charron, CS (reprint author), UNIV FLORIDA, DEPT HORT SCI, GAINESVILLE, FL 32611 USA. RI Barickman, Thomas/I-6993-2012 NR 25 TC 10 Z9 11 U1 0 U2 5 PU AMER SOC HORTICULTURAL SCIENCE PI ALEXANDRIA PA 113 S WEST ST, STE 200, ALEXANDRIA, VA 22314-2851 USA SN 0003-1062 J9 J AM SOC HORTIC SCI JI J. Am. Soc. Hortic. Sci. PD MAY PY 1996 VL 121 IS 3 BP 488 EP 494 PG 7 WC Horticulture SC Agriculture GA UG065 UT WOS:A1996UG06500026 PM 11539354 ER PT J AU Ohler, TA Mitchell, CA AF Ohler, TA Mitchell, CA TI Identifying yield-optimizing environments for two cowpea breeding lines by manipulating photoperiod and harvest scenario SO JOURNAL OF THE AMERICAN SOCIETY FOR HORTICULTURAL SCIENCE LA English DT Article DE Vigna unguiculata; edible yield rate; shoot harvest index; yield efficiency rate; controlled ecological life-support systems AB Photoperiod and harvest scenario of cowpea (Vigna unguiculata L., Walp) canopies were manipulated to optimize productivity for use in future controlled ecological life-support systems, Productivity was measured by edible yield rate (EYR : g . m(-2). day(-1)), shoot harvest index (SHI : g edible biomass .[g total shoot dry weight]), and yield-efficiency rate (YER : g edible biomass . m(-2). day(-1)per [g nonedible shoot dry weight]), Breeding lines 'IT84S-2246' (S-2246) and 'IT82D-889' (D-889) were grown in a greenhouse under 8-, 12-, or 24-h photoperiods. S-2246 was short-day and D-889 was day-neutral for flowering. Under each photoperiod, cowpeas were harvested either for leaves only, seeds only, or leaves plus seeds (mixed harvest), Photoperiod did not affect EYR of either breeding line for any harvest scenario tested, Averaged over both breeding Lines, seed harvest gave the highest EYR at 6.7 g . m(-2). day(-1). The highest SHI (65%) and YER (94 mg . m(-2). day(-1). g(-1)) were achieved for leaf-only harvest of D-889 under an 8-h photoperiod. For leaf-only harvest of S-2246, both SHI and YER increased with increasing photoperiod, but declined for seed-only and mixed harvests. However, photoperiod had no effect on SHI or YER for D-889 for any harvest scenario, A second experiment utilized the short-day cowpea breeding line 'IT89KD-288' (D-288) and the day-neutral breeding line 'IT87D-941-1' (D-941) to compare yield parameters using photoperiod extension under differing lamp types, This experiment confirmed the photoperiod responses of D-889 and S-2246 to a mixed-harvest scenario and indicated that daylength extension with higher irradiance from high pressure sodium lamps further suppressed EYR, SHI, and YER of the short-day breeding line D-288. C1 PURDUE UNIV,NASA,SPECIALIZED CTR RES & TRAINING BIOREGENERAT LIFE,DEPT HORT,W LAFAYETTE,IN 47907. NR 20 TC 3 Z9 3 U1 0 U2 0 PU AMER SOC HORTICULTURAL SCIENCE PI ALEXANDRIA PA 701 NORTH SAINT ASAPH STREET, ALEXANDRIA, VA 22314-1998 SN 0003-1062 J9 J AM SOC HORTIC SCI JI J. Am. Soc. Hortic. Sci. PD MAY PY 1996 VL 121 IS 3 BP 576 EP 581 PG 6 WC Horticulture SC Agriculture GA UG065 UT WOS:A1996UG06500040 PM 11539355 ER PT J AU Casady, JB Luckowski, ED Bozack, M Sheridan, D Johnson, RW Williams, JR AF Casady, JB Luckowski, ED Bozack, M Sheridan, D Johnson, RW Williams, JR TI Etching of 6H-SiC and 4H-SiC using NF3 in a reactive ion etching system SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID SIC THIN-FILMS; FLUORINATED GASES; MIXTURES AB The use of pure NF3 source gas in reactive ion etching of bulk and epitaxy, Si-face, 6H-SiC, and 4H-SiC is reported. The effects of RF power and chamber pressure on etch rate and surface morphology are discussed. A process developed for a smooth, residue-free etch, with a relatively high etch rate of similar to 1500 Angstrom/min is examined using scanning electron microscopy and Auger electron spectroscopy surface analysis. The process developed had a self-induced de bias ranging from 25 to 50 V, a forward RF power of 275 W (1.7 W/cm(2)), chamber pressure of 225 mT, and a NF3 now rate between 95 and 110 seem. No chemical residue or aluminum micromasking was observed on any of the samples etched with the above process. C1 AUBURN UNIV,DEPT PHYS,AUBURN,AL 36849. RP Casady, JB (reprint author), AUBURN UNIV,DEPT ELECT ENGN,NASA,CTR COMMERCIAL DEV,AUBURN,AL 36849, USA. NR 16 TC 35 Z9 36 U1 0 U2 4 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 10 SOUTH MAIN STREET, PENNINGTON, NJ 08534 SN 0013-4651 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD MAY PY 1996 VL 143 IS 5 BP 1750 EP 1753 DI 10.1149/1.1836711 PG 4 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA UK930 UT WOS:A1996UK93000053 ER PT J AU Krasich, M AF Krasich, M TI A fine year SO JOURNAL OF THE INSTITUTE OF ENVIRONMENTAL SCIENCES LA English DT Editorial Material RP Krasich, M (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,M-S 301-466,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU INST ENVIRONMENTAL SCI PI MT PROSPECT PA 940 E NORTHWEST HIGHWAY, MT PROSPECT, IL 60056 SN 1052-2883 J9 J INST ENVIRON SCI JI J. Inst. Environ. Sci. PD MAY-JUN PY 1996 VL 39 IS 3 BP 18 EP 18 PG 1 WC Engineering, Environmental; Environmental Sciences; Instruments & Instrumentation SC Engineering; Environmental Sciences & Ecology; Instruments & Instrumentation GA UU899 UT WOS:A1996UU89900002 ER PT J AU Buehler, MG Bell, LD Hecht, MH AF Buehler, MG Bell, LD Hecht, MH TI Alpha-particle gas-pressure sensor SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A LA English DT Article; Proceedings Paper CT 42nd National Symposium of the American-Vacuum-Society CY OCT 16-20, 1995 CL MINNEAPOLIS, MN SP Amer Vacuum Soc AB An approximate model was developed to establish design curves for the saturation region and a more complete model developed to characterize the current-voltage curves for an alpha-particle pressure sensor. A simple two-parameter current-voltage expression was developed to describe the dependence of the ion current on pressure. The parameters are the saturation-current pressure coefficient and mu/D, the ion mobility/diffusion coefficient. The sensor is useful in the pressure range between 0.1 and 1000 mb using a 1-mu Ci Am-241 source. Experimental results, taken between 1 and up to 200 mb, show the sensor operates with an anode voltage of 5 V and a sensitivity of 20 fA/mb in nitrogen. (C) 1996 American Vacuum Society. RP Buehler, MG (reprint author), CALTECH, JET PROP LAB, CTR SPACE MICROELECTR TECHNOL, PASADENA, CA 91109 USA. NR 13 TC 1 Z9 1 U1 0 U2 0 PU A V S AMER INST PHYSICS PI MELVILLE PA STE 1 NO 1, 2 HUNTINGTON QUADRANGLE, MELVILLE, NY 11747-4502 USA SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A PD MAY-JUN PY 1996 VL 14 IS 3 BP 1281 EP 1287 DI 10.1116/1.579942 PN 1 PG 7 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA UR134 UT WOS:A1996UR13400117 ER PT J AU Lamouri, A Wang, YX Mearini, GT Krainsky, IL Dayton, JA Mueller, W AF Lamouri, A Wang, YX Mearini, GT Krainsky, IL Dayton, JA Mueller, W TI Electron emission observations from as-grown and vacuum-coated chemical vapor deposited diamond SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article; Proceedings Paper CT 8th International Vacuum Microelectronics Conference (IVMC 95) CY JUL 31-AUG 03, 1995 CL PORTLAND, OR SP IEEE, ARPA, NRL, Japan Soc Promot Sci, AVS AB Field emission has been observed from chemical vapor deposited diamond grown on Mo and Si substrates. Emission was observed at fields as low as 20 kV/cm. The samples were tested in the as-grown form, and after coating with thin films of Au, CsI, and Ni. The emission current was typically maximum at the onset of the applied field, but was unstable, and decreased rapidly with time from the as-grown films. Thin Au layers, similar to 15 nm thick, vacuum deposited onto the diamond samples significantly improved the stability of the emission current at values approximately equal to those from uncoated samples at the onset of the applied field. Thin layers of CsI, similar to 5 nm thick, were also observed to improve the stability of the emission current but at values less than those from the uncoated samples at the onset of the applied field. While Au and CsI improved the stability of the emission, Ni was observed to have no effect. (C) 1996 American Vacuum Society. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RES 2000 INC,WESTLAKE,OH 44145. RP Lamouri, A (reprint author), GEN VACUUM INC,CLEVELAND,OH 44105, USA. NR 7 TC 15 Z9 15 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1071-1023 J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD MAY-JUN PY 1996 VL 14 IS 3 BP 2046 EP 2049 DI 10.1116/1.588983 PG 4 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA UU480 UT WOS:A1996UU48000087 ER PT J AU Miyoshi, K AF Miyoshi, K TI Friction and wear properties of as-deposited and carbon ion-implanted diamond films SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article; Proceedings Paper CT 5th International Conference on the Science of Hard Materials (ICSHM 5) CY FEB 20-24, 1995 CL MAUI, HI SP Kennametal Inc, KMS Instruments, Norton Co, Reed Tool Co, Elsevier Sci SA DE friction; diamond films; ion implantation; tribology; superhard coatings AB Recent work on the friction and wear properties of as-deposited and carbon ion-implanted diamond films was reviewed. Diamond films were produced by the microwave plasma chemical vapor deposition (CVD) technique. Diamond films with various grain sizes and surface roughnesses were implanted with carbon ions at 60 keV ion energy, resulting in a dose of 1.2 x 10(17) carbon ions per cm(2). Various analytical techniques, including Raman spectroscopy, proton recoil analysis, Rutherford backscattering, transmission and scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, were utilized to characterize the diamond films. Sliding friction experiments were conducted with a polished natural diamond pin in contact with diamond films in the three environments: humid air (40% relative humidity), dry nitrogen ([1 percent relative humidity), and ultrahigh vacuum (10(-7) Pa). The CVD diamond films indeed have friction and wear properties similar to those of natural diamond in the three environments. The as-deposited, fine-grain diamond films can be effectively used as self-lubricating, wear-resistant coatings that have low coefficients of friction (0.02 to 0.04) and low wear rates (10(-7) to 10(-8) mm(3) N-1 m(-1)) in both humid air and dry nitrogen. However, they have high coefficients of friction (1.5 to 1.7) and a high wear rate (10(-4) mm(3) N-1 m(-1)) in ultrahigh vacuum. The carbon ion implantation produced a thin surficial layer (< 0.1 mu m thick) of amorphous, nondiamond carbon on the diamond films. In humid air and dry nitrogen, the ion-implanted, fine- and coarse-grain diamond films have a low coefficient of friction (around 0.1) and a low wear rate (10(-7) mm(3) N-1 m(-1)). Even in ultrahigh vacuum, the presence of the nondiamond carbon layer reduced the coefficient of friction of fine-grain diamond films to 0.1 or lower and the wear rate to 10(-6) mm(3) N-1 m(-1). Thus, the carbon ion-implanted, fine-grain diamond films can be effectively used as wear-resistant, self-lubricating coatings not only in air and dry nitrogen, but also in ultrahigh vacuum. RP NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 26 TC 22 Z9 25 U1 1 U2 6 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0921-5093 EI 1873-4936 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD MAY PY 1996 VL 209 IS 1-2 BP 38 EP 53 DI 10.1016/0921-5093(95)10114-4 PG 16 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA UT952 UT WOS:A1996UT95200010 ER PT J AU Xue, Z Noojin, SL Vandegrift, JG Kuruvilla, AK Smith, JE AF Xue, Z Noojin, SL Vandegrift, JG Kuruvilla, AK Smith, JE TI Microgravity liquid phase sintering and pore evolution SO MATERIALS TRANSACTIONS JIM LA English DT Article; Proceedings Paper CT International Symposia on Advanced Material and Technology for the 21st-Century - JIM 95 Fall Annual Meeting CY 1995 CL HI SP Japan Inst Met DE liquid phase sintering; microgravity; Fe-Cu alloys; pore metamorphosis; critical solid volume fraction; critical coordination number; equilibrium LPS composition ID MICROSTRUCTURES AB The effect of microgravity on liquid phase sintering (LPS) in the Fe-Cu system was investigated through experiments on four sounding rockets and on three Space Shuttle missions. Three compositions, namely, Fe-33 wt.%Cu, Fe-43 wt.%Cu and Fe-53 wt.%Cu were processed for times ranging from 2.5 minutes to 66 minutes. The samples did not exhibit slumping or shape distortion during processing. However, extensive pore formation and metamorphosis was observed in all these samples, Microstructural characteristics such as densification, dihedral angle, contacts per grain, grain growth and pore metamorphosis were evaluated. The evolution of LPS microstructure in microgravity is explained using energy considerations because the liquid, solid and gaseous phases in the Fe-Cu samples seek to attain the minimum energy configuration in the absence of gravitational forces. Therefore, the volume fractions of liquid solid and gaseous phases and processing times significantly influence the LPS microstructure in microgravity. This paper documents the effect of composition and processing time on microstructural development in the Fe-Cu samples that have been liquid phase sintered under microgravity. C1 UNIV ALABAMA,DEPT CHEM & MAT ENGN,HUNTSVILLE,AL 35899. IIT,RES INST,MRF,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL. RP Xue, Z (reprint author), UNIV ALABAMA,CONSORTIUM MAT DEV SPACE,HUNTSVILLE,AL 35899, USA. NR 16 TC 13 Z9 13 U1 0 U2 0 PU JAPAN INST METALS PI SENDAI PA AOBA ARAMAKI, SENDAI 980, JAPAN SN 0916-1821 J9 MATER T JIM JI Mater. Trans. JIM PD MAY PY 1996 VL 37 IS 5 BP 1084 EP 1090 PG 7 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA UV971 UT WOS:A1996UV97100022 ER PT J AU Hanna, A Remington, R AF Hanna, A Remington, R TI The representation of color and form in long-term memory SO MEMORY & COGNITION LA English DT Article ID RECOGNITION; SURFACE; INFORMATION; INTEGRATION; PERCEPTION; RETRIEVAL; OBJECTS; SHAPES; MODEL AB Color and form are elementary stimulus encoding dimensions that have effects on the representation of visual stimuli at early processing stages. Little is known, however, about their effects on visual long-term memory. In three experiments we investigated whether color is part of the memory representation, whether color and form are bound in the memory representation, and the effect of color context on memory performance. Experimental results suggest that color is part of the memory representation and that color and form can be represented separately in memory and accessed independently. We suggest that the binding of color and form is a deliberate strategic act that requires focal attention, not a natural consequence of processing visual stimuli. We compare our results with the predictions of two computational memory models regarding feature binding. The effect of color context was not straightforward; however, results are consistent with the encoding specificity principle. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Hanna, A (reprint author), VIRGINIA COMMONWEALTH UNIV,DEPT PSYCHOL,BOX 2018,RICHMOND,VA 23284, USA. NR 34 TC 29 Z9 34 U1 0 U2 5 PU PSYCHONOMIC SOC INC PI AUSTIN PA 1710 FORTVIEW RD, AUSTIN, TX 78704 SN 0090-502X J9 MEM COGNITION JI Mem. Cogn. PD MAY PY 1996 VL 24 IS 3 BP 322 EP 330 DI 10.3758/BF03213296 PG 9 WC Psychology, Experimental SC Psychology GA UH518 UT WOS:A1996UH51800005 PM 8718766 ER PT J AU Nyquist, LE AF Nyquist, LE TI High-Ti volcanism and the lunar mantle SO METEORITICS & PLANETARY SCIENCE LA English DT Editorial Material RP Nyquist, LE (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,MAIL CODE SN4,HOUSTON,TX 77058, USA. NR 12 TC 0 Z9 0 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAY PY 1996 VL 31 IS 3 BP 319 EP 320 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UL724 UT WOS:A1996UL72400001 ER PT J AU Hiroi, T Zolensky, ME Pieters, CM Lipschutz, ME AF Hiroi, T Zolensky, ME Pieters, CM Lipschutz, ME TI Thermal metamorphism of the C, G, B, and F asteroids seen from the 0.7 mu m, 3 mu m, and UV absorption strengths in comparison with carbonaceous chondrites SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID REFLECTANCE SPECTROSCOPY; OUTER-BELT; SPECTROPHOTOMETRY; MATRIX AB Thermal metamorphism study of the C, G, B, and F asteroids has been revisited using their UV, visible, NIR, and 3 mu m reflectance spectra. High-quality reflectance spectra of seven selected C, G, B, and F asteroids have been compared with spectra for 29 carbonaceous chondrites, including thermally-metamorphosed CI/CM meteorites. There are three sets of spectral counterparts, among which 511 Davida and B-7904 are the most similar to each other in terms of both spectral shape and brightness. By comparing the 0.7 mu m and 3 mu m absorption strengths of 21 C, G, B, and F asteroids and heated Murchison samples, these asteroids have been grouped into three heating-temperature ranges. These correspond to (1) <400 degrees C: phyllosilicate-rich; (2) 400-600 degrees C: phyllosilicates transformed to anhydrous silicates; and (3) >600 degrees C: fully anhydrous. A good correlation between the UV and 3 mu m absorption strengths has been confirmed for the C, G, B, and F asteroids and the CI, CM, and CR meteorites. A plot of the UV absorption strength vs. the IRAS diameter for 142 C, G, B, and F asteroids shows that the maximum UV absorption strength decreases as the diameter increases for the asteroids >60 km, with a notable exception, Ceres. These relationships suggest that some of the larger asteroids may be the heated inner portions of once larger bodies and that common CI/CM meteorites may have come from the lost outer portions, which escaped extensive late-stage heating events. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. PURDUE UNIV,DEPT CHEM,W LAFAYETTE,IN 47907. RP Hiroi, T (reprint author), BROWN UNIV,DEPT GEOL SCI,PROVIDENCE,RI 02912, USA. NR 46 TC 105 Z9 105 U1 0 U2 4 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAY PY 1996 VL 31 IS 3 BP 321 EP 327 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UL724 UT WOS:A1996UL72400003 ER PT J AU Higgins, SJ Taylor, LA Chambers, JG Patchen, A McKay, DS AF Higgins, SJ Taylor, LA Chambers, JG Patchen, A McKay, DS TI X-ray digital-imaging petrography: Technique development for lunar mare soils SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID PETROLOGY AB Remote sensing studies are the primary means of solar system exploration. In particular, spectral reflectance measurements involve determinations of the nature and compositions of other worlds through analysis of absorption features characteristic of the surface chemistry and mineralogy. These studies are particularly applicable to ''airless'' solar system bodies (e.g., the Moon), because atmospheres, such as on Earth, tend to interfere with the reflectance spectrum. The precision of the spectral measurements is greatly increased by calibration with actual lunar soils. In the past, these calibrations were done using particle-counting data collected for the study of soil formation processes, soil classification, and provenance determination. These particle counting data, while valuable in those areas of study, neither identify the true volume percentages of soil particles, nor give the true modal values for the various phases (i.e., minerals and glasses) which make up the soil grains. These data are paramount for accurate spectral reflectance calibrations. Therefore, in this paper, a new technique is presented that involves x-ray digital-imaging of lunar soils using an energy dispersive spectrometer (EDS) on an electron microprobe. In contrast to particle counting with an optical microscope, the digital-imaging method allows precise volume percentages of soil grains to be determined, including absolute modal abundances of the various phases locked within the particles as well as their chemistry. In order to validate this method for characterization of lunar soils, the technique was applied to four Apollo 17 soils that were previously described by Heiken and McKay (1974) via particle counts with an optical microscope, and similar results were obtained. In addition to verifying the x-ray digital-imaging technique, the obtained data were applied in order to better understand the lunar-soil formational process, specifically the variation of particle types with maturity. C1 NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. RP Higgins, SJ (reprint author), UNIV TENNESSEE, DEPT GEOL SCI, PLANETARY GEOSCI INST, KNOXVILLE, TN 37996 USA. NR 24 TC 8 Z9 8 U1 0 U2 0 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAY PY 1996 VL 31 IS 3 BP 356 EP 361 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UL724 UT WOS:A1996UL72400007 ER PT J AU Meyer, C Williams, IS Compston, W AF Meyer, C Williams, IS Compston, W TI Uranium-lead ages for lunar zircons: Evidence for a prolonged period of granophyre formation from 4.32 to 3.88 Ga SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID U-TH-PB; ION-MICROPROBE; IMMISCIBLE LIQUIDS; ISOTOPIC EVIDENCE; RB-SR; ROCKS; KREEP; APOLLO-14; SAMPLE; MOON AB The ages of a number of small fragments of lunar granophyre have been determined by the in situ U-Th-Pb isotopic analysis of zircon using a sensitive high mass-resolution ion microprobe (SHRIMP I). The zircon from lunar granophyre is characterized by consistently high U and Th contents (most 200-500 ppm and 100-300 ppm, respectively) compared to zircon from mafic lunar rocks. Some fragments of lunar granophyre are found to be as old as 4.32 Ga, supporting other evidence that the original lunar magma ocean crystallized completely within similar to 200 Ma of the formation of the Moon itself. Other fragments are as young as 3.88 Ga, which is much later than the time of formation of most of the lunar crust. The older lunar granophyres have rare-earth-element (REE) patterns that are similar to lunar KREEP, whilst the younger granophyres have bow-shaped REE patterns that feature a greater relative enrichment in the heavy REE. The wide range of ages of numerous lunar zircons, lunar granophyres and other rocks indicates that zircon-forming magmatism in the lunar highlands was most active prior to 4.3 Ga but continuous until at least 3.88 Ga. The U-Pb isotopic composition of much lunar zircon is near concordant, but the effects of isotopic disturbance as late as similar to 1.0 Ga are observed in some zircon, both within granophyre fragments recrystallized by reheating and within fragments in which the original delicate silica-K-feldspar granophyric intergrowth is well preserved. It is therefore essential to make multiple analyses of individual zircon grains, and preferably analyses of suites of zircons from lunar igneous rocks if they are to be dated reliably by the U-Pb method. It is possible that some of the younger lunar granophyres are the product of large-scale silicate-liquid immiscibility within late-stage differentiates, but this remains unproven until remnants of demonstrably cogenetic, Fe-rich, immiscible liquid are positively identified. C1 AUSTRALIAN NATL UNIV, RES SCH EARTH SCI, CANBERRA, ACT 2601, AUSTRALIA. RP Meyer, C (reprint author), NASA, LYNDON B JOHNSON SPACE CTR, PLANETARY MISSIONS & MAT BRANCH SN2, HOUSTON, TX 77058 USA. RI SHRIMP, ANU/F-5312-2011; Williams, Ian/F-4302-2012 OI Williams, Ian/0000-0003-4465-6493 NR 84 TC 64 Z9 65 U1 0 U2 7 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAY PY 1996 VL 31 IS 3 BP 370 EP 387 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UL724 UT WOS:A1996UL72400010 ER PT J AU McCoy, TJ Ehlmann, AJ Benedix, GK Keil, K Wasson, JT AF McCoy, TJ Ehlmann, AJ Benedix, GK Keil, K Wasson, JT TI The Lueders, Texas, IAB iron meteorite with silicate inclusions SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID ORDINARY CHONDRITES; CLASSIFICATION; MINERALOGY; PYROXENE; IIICD AB The Lueders iron meteorite with silicate inclusions was recovered as a single specimen of similar to 35.4 kg in Shackelford County, Texas, in 1973 and recognized as a meteorite in 1993. Siderophile element concentrations indicate chemical classification as a low-Ni IAB iron meteorite closely related to Landes; like Landes, it has a Cu content similar to 4 sigma above the main IAB-IIICD trend and therefore we also designate Lueders as an anomalous member of IAB. The metallic host is composed of equigranular kamacite but with a suggestion of octahedral structure and with a bandwidth of 1.4 mm, suggesting structural classification as a coarse octahedrite (Og). The meteorite contains similar to 23 wt% of roughly millimeter to centimeter-sized angular silicate inclusions. Classification as a IAB is confirmed by O isotopic analysis of silicate inclusions. These inclusions contain an assemblage rich in silicates, troilite and graphite; lack certain minor phases (e.g., daubreelite); and have angular shapes. A variety of processes (e.g., fragmentation, partial melting, reduction) appear to have played a significant role in the formation of Lueders and all IAB iron meteorites. Petrologic and chemical differences confirm that Lueders is not paired with the widely distributed Odessa meteorite. C1 TEXAS CHRISTIAN UNIV,DEPT GEOL,FT WORTH,TX 76129. UNIV HAWAII MANOA,HAWAII INST GEOPHYS & PLANETOL,SCH OCEAN & EARTH SCI & TECHNOL,HONOLULU,HI 96822. UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024. HAWAII CTR VOLCANOL,HONOLULU,HI. UNIV CALIF LOS ANGELES,DEPT EARTH & SPACE SCI,LOS ANGELES,CA 90024. UNIV CALIF LOS ANGELES,DEPT CHEM & BIOCHEM,LOS ANGELES,CA 90024. RP McCoy, TJ (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,CODE SN4,HOUSTON,TX 77058, USA. OI Wasson, John/0000-0002-7253-2300; Benedix, Gretchen/0000-0003-0990-8878 NR 18 TC 10 Z9 10 U1 0 U2 2 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAY PY 1996 VL 31 IS 3 BP 419 EP 422 PG 4 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UL724 UT WOS:A1996UL72400016 ER PT J AU Cebula, RP Hilsenrath, E DeCamp, PW Laamann, K Janz, S McCullough, K AF Cebula, RP Hilsenrath, E DeCamp, PW Laamann, K Janz, S McCullough, K TI The SSBUV experiment wavelength scale and stability: 1988 to 1994 SO METROLOGIA LA English DT Article; Proceedings Paper CT 5th International Conference on Radiometry CY SEP 19-21, 1994 CL BERLIN, GERMANY SP Phys Tech Bundesanstalt AB A solar backscatter ultraviolet experiment flies regularly on the Space Shuttle to help validate and maintain the calibrations of several satellite-borne stratospheric ozone monitoring instruments. The Shuttle Solar Backscatter Ultraviolet (SSBUV) programme incorporates multiple radiometric standards and redundant calibration checks which have allowed the tracking of long-term changes in the calibration of the SSBUV instrument to within 1% over six flights. The reduction of uncertainties in SSBUV wavelength calibration has recently been emphasized because of an increasing need to improve precision and accuracy. Therefore, selected solar spectral features are now used to monitor intra- and inter-flight changes in that wavelength calibration. The results of applying this technique to the six SSBUV Shuttle missions are presented, together with a comparison of these results with results from two traditional approaches in which laboratory and on-board spectral line sources, respectively, are used to determine and monitor the SSBUV wavelength scale. Long-term wavelength calibration change is less than 0,02 nm, and intra-flight wavelength change is 0,05 nm or less. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. IDEA INC,BELTSVILLE,MD 20705. RP Cebula, RP (reprint author), HUGHES STX CORP,GREENBELT,MD 20770, USA. NR 11 TC 4 Z9 4 U1 0 U2 0 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD MAY PY 1996 VL 32 IS 6 BP 633 EP 636 DI 10.1088/0026-1394/32/6/47 PG 4 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA UU321 UT WOS:A1996UU32100047 ER PT J AU Janz, S Hilsenrath, E Butler, J Heath, DF Cebula, RP AF Janz, S Hilsenrath, E Butler, J Heath, DF Cebula, RP TI Uncertainties in radiance calibrations of backscatter ultraviolet (BUV) instruments SO METROLOGIA LA English DT Article; Proceedings Paper CT 5th International Conference on Radiometry CY SEP 19-21, 1994 CL BERLIN, GERMANY SP Phys Tech Bundesanstalt AB Traditional radiance calibrations of solar backscatter ultraviolet (SBUV) instruments require a measurement of the bidirectional-reflectance distribution function (BRDF) of a flat-plate diffuser. To date the BRDF of the diffusers used for calibrating the Shuttle-borne SBUV instrument (SSBUV), has relied on an initial measurement of a sample plate coated with BaSO4 made by the National Institutes of Standards and Technology (NIST). Changes in the reflectance of the calibration diffusers were tracked over time with measurements of their total hemispherical reflectance. Preliminary comparisons of direct measurements of the BRDF using a new facility at the NASA/Goddard Space Flight Center, inferred BRDF values using an integrating sphere, and the NIST-based values, show significant inconsistencies. In general, direct measurements of BRDF values compare to within 1% of those inferred from integrating sphere measurements. However, these values differ from the NIST-based values by about 6%. These differences and their uncertainties are discussed. The results imply that SSBUV-measured vertical ozone profile values have an altitude-dependent error of between 3% and -12%, but there should be little effect on the measured total ozone values. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RES & SUPPORT INSTRUMENTS,BOULDER,CO 80301. HUGHES STX CORP,GREENBELT,MD 20770. RP Janz, S (reprint author), IDEA INC,BELTSVILLE,MD 20705, USA. RI Butler, James/D-4188-2013 NR 13 TC 17 Z9 17 U1 0 U2 0 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD MAY PY 1996 VL 32 IS 6 BP 637 EP 641 DI 10.1088/0026-1394/32/6/48 PG 5 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA UU321 UT WOS:A1996UU32100048 ER PT J AU Hickey, GS Wu, TK AF Hickey, GS Wu, TK TI A four-frequency selective surface spacecraft subreflector antenna SO MICROWAVE JOURNAL LA English DT Article AB A four-frequency telecommunication subsystem has been developed for the Cassini spacecraft antenna subsystem. The frequency selective surface (FSS) subreflector design required it to be integrated into thc hi(rh gain antenna (HGA) subsystem. The FSS can multiplex S, X, Ku and Ka frequency band wavelengths. The FSS design incorporates a periodic array of conducting elements on a Kevlar(TM)/polymer composite structure, The design requires the use Of well-characterized, low dielectric composite materials that are both mechanically and electrically stable over a broad temperature range and that can survive in a deep space environment. This paper discusses the development, and mechanical and RF electrical testing of two alternate designs as flat panel prototypes. Testing was completed to verify the multifrequency design approach. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. TRW Co Inc, Redondo Beach, CA USA. RP Hickey, GS (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NR 15 TC 1 Z9 1 U1 0 U2 0 PU HORIZON HOUSE PUBLICATIONS INC PI NORWOOD PA 685 CANTON ST, NORWOOD, MA 02062 USA SN 0192-6225 J9 MICROWAVE J JI Microw. J. PD MAY PY 1996 VL 39 IS 5 BP 240 EP + PG 6 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA V2896 UT WOS:000168853500020 ER PT J AU Higgins, RW Mo, KC Schubert, SD AF Higgins, RW Mo, KC Schubert, SD TI The moisture budget of the central United States in spring as evaluated in the NCEP/NCAR and the NASA/DAO reanalyses SO MONTHLY WEATHER REVIEW LA English DT Article ID CONVECTION; SYSTEM AB The moisture budget of the central United States during May is examined using multiyear (1985-89) assimilated datasets recently produced by NASA/DAO and NCEP/NCAR. Intercomparisons and comparisons with station observations are used to evaluate the limitations of the assimilated products for studies of the atmospheric component of the U.S. hydrologic cycle. Attempts are made to reconcile differences in terms of disparities in the analysis systems. Both reanalyses overestimate daily mean precipitation rates by a factor of almost 2 over the southeastern United States. This is associated with much larger than observed afternoon convective rain and a substantial overestimate of the number of days with precipitation. Both products capture the transition to the much drier conditions over the western United States, though the NCEP/NCAR product extends moderate rain rates too far to the northwest. Over the Great Plains, the reanalyses capture observed synoptic-scale precipitation events quite well, but the variability of the daily mean precipitation is underestimated; this is particularly true for the NASA/ DAO analysis, which has difficulty capturing the extreme rain rates. The NCEP/NCAR product shows generally higher correlation's with the observed precipitation, though the fluctuations in the two assimilation products are more similar to each other than they are to the observations. The moisture transport in the reanalyses compares favorably to gridded rawinsonde data though there are some significant regional differences particularly along the Gulf Coast. Examination of the overall moisture budget for the central United States shows that the observations act as a significant local source of moisture, reflecting model bias in the first-guess fields. In both products the analysis increments act to remove water over much of the northern and western part of the country, apparently counteracting excessive evaporation in those regions, especially in the NASA/DAO. Perhaps most disturbing are the substantial differences between the two reanalyses in the moisture divergence fields since these are the most strongly constrained by the observations. Both reanalyses capture the basic temporal and structural characteristics of the Great Plains low-level jet (LLJ) documented in previous observational studies. Composites of the nocturnal fluxes of moisture during LLJ events reveal a horizontally confined region of strong southerly transport to the east of the Rocky Mountains that is sandwiched between well-defined synoptic-scale cyclonic (anticyclonic) circulations to the northwest (southeast). Low-level inflow from the Gulf of Mexico increases by more than 50% over nocturnal mean values in both reanalyses, though the excess inflow is more than 30% stronger in the NCEP/NCAR reanalysis. While both analyses underestimate the nocturnal maximum in precipitation over the Great Plains, the pattern of precipitation anomalies associated with LLJ events compares favorably to observations. C1 NASA,GODDARD LAB ATMOSPHERES,GREENBELT,MD. RP Higgins, RW (reprint author), NOAA,NWS,NCEP,CLIMATE PREDICT CTR,ANAL BRANCH,W-NP52,WORLD WEATHER BLDG,WASHINGTON,DC 20233, USA. NR 28 TC 75 Z9 78 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD MAY PY 1996 VL 124 IS 5 BP 939 EP 963 DI 10.1175/1520-0493(1996)124<0939:TMBOTC>2.0.CO;2 PG 25 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ178 UT WOS:A1996UJ17800010 ER PT J AU Cibula, WG Weber, NS AF Cibula, WG Weber, NS TI Hygrocybe andersonii a new psammophilus Hygrocybe from Horn Island, a Mississippi barrier island SO MYCOLOGIA LA English DT Article DE Walter Inglis Anderson; basidiomycete; Ceratiola ericoides; dune stabilization; Hygrophoraceae; systematics AB Hygrocybe andersonii, a new species always found in association with Ceratiola ericoides on barrier islands and mainland sand dunes, is described. This Hygrocybe is distinguished from other Hygrocybes by its densely cespitose method of growth, its occurrence in sand in the vicinity of Ceratiola ericoides, large bacilliform spores, and the presence of colorless, blue flourescing compounds on chromatograms prepared from pigment extracts. In addition, these chromatograms exhibit a complex of yellow to orange pigments of R(f) 0.14 to 0.25 that replace rhodohygrocybin as found in most other Hygrocybes. C1 UNIV MICHIGAN,HERBARIUM,ANN ARBOR,MI 48109. RP Cibula, WG (reprint author), NASA,SCI & TECHNOL LAB,JOHN C STENNIS SPACE CTR,BAY ST LOUIS,MS 39529, USA. NR 16 TC 6 Z9 6 U1 0 U2 0 PU NEW YORK BOTANICAL GARDEN PI BRONX PA PUBLICATIONS DEPT, BRONX, NY 10458 SN 0027-5514 J9 MYCOLOGIA JI Mycologia PD MAY-JUN PY 1996 VL 88 IS 3 BP 514 EP 516 DI 10.2307/3760892 PG 3 WC Mycology SC Mycology GA UT087 UT WOS:A1996UT08700019 ER PT J AU Stephens, DG Cazier, FW AF Stephens, DG Cazier, FW TI NASA noise reduction program for advanced subsonic transports SO NOISE CONTROL ENGINEERING JOURNAL LA English DT Article; Proceedings Paper CT Conference on Noise Control - Where Do We Stand Today CY JUN 01, 1995 CL WASHINGTON, DC SP Acoust Soc Amer AB The NASA Advanced Subsonics Technology (AST) program was initiated in late 1993, The program consists of 10 elements or programs, Acoustical technology is an important factor in most of these programs, The AST Noise Reduction program and the AST Short Haul-Civil Tiltrotor program are discussed in some detail. The objective of these acoustics programs is to provide innovative acoustical technology required by the industry for developing environmentally compatible and economically viable aircraft for the subsonic flight regime, These programs are exploiting advanced technologies such as computational aeroacoustics, active noise control, and advanced propagation and prediction methods. (C) 1996 Institute of Noise Control Engineering. RP Stephens, DG (reprint author), NASA,LANGLEY RES CTR,FLUID MECH & ACOUST DIV,HAMPTON,VA 23681, USA. NR 9 TC 2 Z9 2 U1 0 U2 0 PU INST NOISE CONTROL ENG PI POUGHKEEPSIE PA PO BOX 3206 ARLINGTON BRANCH, POUGHKEEPSIE, NY 12603 SN 0736-2501 J9 NOISE CONTROL ENG JI Noise Control Eng. J. PD MAY-JUN PY 1996 VL 44 IS 3 BP 135 EP 140 DI 10.3397/1.2828395 PG 6 WC Acoustics; Engineering, Multidisciplinary SC Acoustics; Engineering GA VA113 UT WOS:A1996VA11300005 ER PT J AU Grasso, D Kolb, EW AF Grasso, D Kolb, EW TI Cosmology and tau neutrino magnetic moment SO NUCLEAR PHYSICS B LA English DT Article; Proceedings Paper CT IV International Workshop on Theoretical and Phenomenological Aspects of Underground Physics (TAUP 95) CY SEP 17-21, 1995 CL TOLEDO, SPAIN SP Univ Zaragoza, Lab Nucl & High Energy Phys, Saving Bank Caja Castilla Mancha, Spanish Agcy Sci & Technol, Minist Sci, Spain ID PRIMORDIAL NUCLEOSYNTHESIS; MASS AB We investigate the possibility that stable tau neutrinos with a large diagonal magnetic moment and mass in the range 0.5 < m(nu tau) < 24 MeV could form cold dark matter. We show that Universe age limit are incompatible with this hypothesis and, more in general, with values of the magnetic moment between 10(-10) mu(B) and the present experimental upper limit in the mass range we considered. In the case the nu(tau) is unstable but tau(nu tau) > 1 s., we use primordial nucleosynthesis considerations to reduce sensibly the allowed region in the parameter space mass versus. magnetic moment. C1 UNIV STOCKHOLM,DEPT PHYS,S-11346 STOCKHOLM,SWEDEN. FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP Grasso, D (reprint author), UPPSALA UNIV,DEPT THEORET PHYS,S-75108 UPPSALA,SWEDEN. RI Grasso, Dario/I-2440-2012 OI Grasso, Dario/0000-0001-7761-7242 NR 11 TC 0 Z9 0 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0550-3213 J9 NUCL PHYS B JI Nucl. Phys. B PD MAY PY 1996 SU 48 BP 275 EP 278 DI 10.1016/0920-5632(96)00261-7 PG 4 WC Physics, Particles & Fields SC Physics GA UN019 UT WOS:A1996UN01900067 ER PT J AU Ganapol, BD Pomraning, GC AF Ganapol, BD Pomraning, GC TI The two-region Milne problem SO NUCLEAR SCIENCE AND ENGINEERING LA English DT Article AB We consider the two-region Milne problem, defined as the steady-state monoenergetic linear transport problem for two adjoining homogeneous source-free half-spaces, with a particle source coming from infinity in one of the half-spaces. We demonstrate that the asymptotic (Case discrete mode) component of the solution for the scalar flux is easily and explicitly written in terms of Chandrasekhar's H-function for each medium. This asymptotic solution is shown to exhibit a discontinuity in both the scalar flux and current at the interface between the two half-spaces. Numerical benchmark results for the linear extrapolation distance and the discontinuities are given for various combinations of the mean number of secondaries (c) characterizing the two media. Contact is also made with a variational treatment. In particular, the variational formalism is shown to predict the linear extrapolation distance and these asymptotic discontinuities correct to first order in the difference between the values of c characterizing the two half-spaces. C1 UNIV CALIF LOS ANGELES,SCH ENGN & APPL SCI,LOS ANGELES,CA 90095. UNIV ARIZONA,DEPT NUCL ENGN,TUCSON,AZ 85721. RP Ganapol, BD (reprint author), NASA,AMES RES CTR,ECOSYST SCI & TECHNOL BRANCH,MOFFETT FIELD,CA 94035, USA. NR 19 TC 2 Z9 2 U1 0 U2 2 PU AMER NUCLEAR SOCIETY PI LA GRANGE PK PA 555 N KENSINGTON AVENUE, LA GRANGE PK, IL 60525 SN 0029-5639 J9 NUCL SCI ENG JI Nucl. Sci. Eng. PD MAY PY 1996 VL 123 IS 1 BP 110 EP 120 PG 11 WC Nuclear Science & Technology SC Nuclear Science & Technology GA UJ235 UT WOS:A1996UJ23500008 ER PT J AU Park, JH Zukic, M Wilson, M Keffer, CE Torr, DG Hoover, RB AF Park, JH Zukic, M Wilson, M Keffer, CE Torr, DG Hoover, RB TI Design and fabrication of multilayer reflective filters for a Ritchey-Chretien Lyman-alpha telescope SO OPTICAL ENGINEERING LA English DT Article DE pi multilayers; self-filtering; angular sensitivity; spectrophotometers ID ULTRAVIOLET AB We report the design and fabrication of multilayer reflective filters for the self-filtering cameras of a Ritchey-Chretien Lyman-alpha (Ly-alpha) telescope that uses reflecting multilayer mirrors, polarizers, and filters. The Ly-alpha telescope is designed to measure the linear polization of hydrogen Ly-alpha line (121.6 nm) emissions from the solar corona. A key element of the filter design includes the development of pi multilayers optimized to provide maximum reflectance at 121.6 nm for the respective cameras without significant angular variation from 0 to 15-deg incident angles. We applied self-filtering concepts to design Ly-alpha telescope filters that are composed of two reflective mirrors. The calculated value of the net throughput is 28.38% with a 4-nm bandwidth at a center wavelength of 121.6 nm. The measured value is 27.35% with a less than 6-nm bandwidth at incidence angle 10 deg. (C) 1996 Society of Photo-Optical Instrumentation Engineers. C1 UNIV ALABAMA,DEPT PHYS,OPT AERONOMY LAB,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP Park, JH (reprint author), SAMSUNG ADV INST TECHNOL,CTR MAT & DEVICES,OPTODEVICE LAB,POB 111,SUWON,SOUTH KOREA. NR 7 TC 2 Z9 2 U1 0 U2 0 PU SOC PHOTO-OPT INSTRUM ENG PI BELLINGHAM PA PO BOX 10, BELLINGHAM, WA 98227-0010 SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD MAY PY 1996 VL 35 IS 5 BP 1479 EP 1482 DI 10.1117/1.600684 PG 4 WC Optics SC Optics GA UK497 UT WOS:A1996UK49700043 ER PT J AU Mishchenko, MI AF Mishchenko, MI TI Coherent backscattering by two-sphere clusters SO OPTICS LETTERS LA English DT Article ID ENHANCED BACKSCATTERING; SCATTERING; LIGHT AB Rigorous numerical solutions of Maxwell's equations are used to show, for what is believed to be the first time, that simple scattering systems composed of two interacting wavelength-sized spheres exhibit a coherent backscattering effect analogous to that observed previously for optically thick discrete random media comprising large numbers of scatterers. (C) 1996 Optical Society of America RP Mishchenko, MI (reprint author), NASA,GODDARD INST SPACE STUDIES,SCI SYST & APPLICAT INC,2880 BROADWAY,NEW YORK,NY 10025, USA. RI Mishchenko, Michael/D-4426-2012 NR 19 TC 26 Z9 26 U1 0 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD MAY 1 PY 1996 VL 21 IS 9 BP 623 EP 625 DI 10.1364/OL.21.000623 PG 3 WC Optics SC Optics GA UG322 UT WOS:A1996UG32200001 PM 19876104 ER PT J AU Downie, JD Smithey, DT AF Downie, JD Smithey, DT TI Red-shifted photochromic behavior of a bacteriorhodopsin film made from the L93T genetic variant SO OPTICS LETTERS LA English DT Article ID PROTON UPTAKE; REISOMERIZATION; PHOTOCYCLE AB We present experimental results demonstrating the red-shifted photochromic behavior of a gelatin film made from L93T, a genetic variant of bacteriorhodopsin. The red shift of the absorbance spectrum on illumination with visible light is due to a short M-state lifetime and a longer-lived O state whose absorption peaks at 610 nm. Pump-probe measurements show the O state to have a lifetime of approximately 2.2 s in the gelatin film, with a single exponential decay behavior. We also present holographic kinetic results for both red (633-nm) and blue (442-nm) readout wavelengths. (C) 1996 Optical Society of America C1 BEND RES INC,BEND,OR 97701. RP Downie, JD (reprint author), NASA,AMES RES CTR,M-S 269-3,MOFFETT FIELD,CA 94035, USA. NR 6 TC 8 Z9 8 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD MAY 1 PY 1996 VL 21 IS 9 BP 680 EP 682 DI 10.1364/OL.21.000680 PG 3 WC Optics SC Optics GA UG322 UT WOS:A1996UG32200020 PM 19876123 ER PT J AU Dominik, C Tielens, AGGM AF Dominik, C Tielens, AGGM TI Resistance to sliding on atomic scales in the adhesive contact of two elastic spheres SO PHILOSOPHICAL MAGAZINE A-PHYSICS OF CONDENSED MATTER STRUCTURE DEFECTS AND MECHANICAL PROPERTIES LA English DT Article ID SURFACE-ENERGY; SOLIDS AB The structure and stability of agglomerates of micron-sized particles is determined by the mechanical properties of the individual contacts between the constituent particles. In this paper we study the possibility of aggregate rearrangements by sliding. Since the contacts between (sub)micron particles are only a few hundred atoms in diameter, processes on atomic levels will play the dominating roll. We study a theoretical model of sliding friction for surfaces that are either flat or contain steps in their grids. The results shows that sliding over hat surfaces may produce a large range of friction coefficients, including zero if the adhesive forces are small compared to the binding forces inside a body. However, both grid alignment and steps in the surface will lead to high values for friction. These processes combined virtually eliminate the possibility of sliding in a collision of two (sub)micron-sized particles at velocities low enough for sticking to occur. On the other hand we show that in collision between aggregates sliding may be an important factor for energy dissipation and compaction. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP Dominik, C (reprint author), LEIDEN OBSERV, POB 9513, 2300 RA LEIDEN, NETHERLANDS. NR 26 TC 35 Z9 35 U1 0 U2 6 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND SN 0141-8610 J9 PHILOS MAG A JI Philos. Mag. A-Phys. Condens. Matter Struct. Defect Mech. Prop. PD MAY PY 1996 VL 73 IS 5 BP 1279 EP 1302 PG 24 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Physics, Applied; Physics, Condensed Matter SC Materials Science; Metallurgy & Metallurgical Engineering; Physics GA UN307 UT WOS:A1996UN30700003 ER PT J AU Cowan, M Rudnick, J Barmatz, M AF Cowan, M Rudnick, J Barmatz, M TI Effects of random motions on critical point measurements: Liquid-gas systems in microgravity SO PHYSICAL REVIEW E LA English DT Article ID CRITICAL-DYNAMICS; FLUID; HE-3 AB The effects of random accelerations on the measurements of quantities in the vicinity of the liquid-gas critical point are considered when the system is in a microgravity environment. These accelerations couple to the order parameter through the transverse component of the velocity field, whose dynamics are also governed by critical point properties of the liquid-gas system. The action of the accelerations is amplified by the singular static and dynamic response of the gas-liquid system. A general formulation, based on ''model H'' critical dynamics allows for the calculation of a variety of quantities. It is found that the random accelerations expected in a microgravity environment will not compromise the accuracy of any experiment that is currently envisioned. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Cowan, M (reprint author), UNIV CALIF LOS ANGELES,DEPT PHYS,405 HILGARD AVE,LOS ANGELES,CA 90024, USA. NR 22 TC 2 Z9 2 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1063-651X J9 PHYS REV E JI Phys. Rev. E PD MAY PY 1996 VL 53 IS 5 BP 4490 EP 4501 DI 10.1103/PhysRevE.53.4490 PN A PG 12 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA UM617 UT WOS:A1996UM61700037 ER PT J AU Girimaji, SS Zhou, Y AF Girimaji, SS Zhou, Y TI Analysis and modeling of subgrid scalar mixing using numerical data SO PHYSICS OF FLUIDS LA English DT Article ID RENORMALIZATION-GROUP; EDDY VISCOSITY; TURBULENCE; FLOWS AB Direct numerical simulations (DNS) of passive scalar mixing in isotropic turbulence is used to study, analyze, and, subsequently, model the role of small (subgrid) scales in the mixing process. In particular, we attempt to model the dissipation of the large-scale (supergrid) scalar fluctuations caused by the subgrid scales by decomposing it into two parts: (i) the effect due to the interaction among the subgrid scales, E(phi)(>); and, (ii) the effect due to interaction between the supergrid and the subgrid scales, E(phi)(><). Model comparison with DNS data shows good agreement. (C) 1996 American Institute of Physics. RP Girimaji, SS (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681, USA. NR 13 TC 78 Z9 78 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD MAY PY 1996 VL 8 IS 5 BP 1224 EP 1236 DI 10.1063/1.868894 PG 13 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA UH305 UT WOS:A1996UH30500010 ER PT J AU Wilson, RM AF Wilson, RM TI On the relationship between transit velocity of interplanetary shocks and solar active processes SO PLANETARY AND SPACE SCIENCE LA English DT Article ID CORONAL MASS EJECTIONS; MAGNETIC CLOUDS; GEOMAGNETIC RESPONSE; EVENTS; FLARES; GEOEFFECTIVENESS; DISTURBANCES; STORMS; EARTH AB Recently, it was reported (V.G. Eselevich, Planet. Space Sci. 42(7), 575-582, 1994) that preferential relationships exist between the transit velocity V-T of earthward-directed interplanetary shocks and solar active processes, in particular, eruptive filaments outside active regions (the size of the erupting filament L(f)) and solar flares (the value of the X-ray characteristic J). Unfortunately, statistical testing of the proposed associations was not accomplished, nor was the ''geoeffectiveness'' of the events adequately described. Reported here are the results of a re-examination of the 21 eruptive filaments (SSC-EF events) and 26 X-ray flares (SSC-F events) that have been associated with storm sudden commencements (SSCs) at Earth. Simple statistical testing refutes the claim that a preferential relationship exists between V-T and L(f), while it supports the claim that one exists between V-T and J. More importantly, the inferred relationship between V-T and J is found to be more complicated than previously thought. In particular, it now appears that SSC-F events may be separable into two groups, based on the value of J: a low-J group (J less than or equal to 56), in which V-T varies directly with J, and a high-J group (J>56), in which V-T varies inversely with J. As a whole, high-J events are associated with shocks of higher average transit velocity than those of low-J events, and SSC-F events with shocks of higher average transit velocity than those of SSC-EF events. Further, high-J events tend to be of greater X-ray class (>M3), longer duration (>80 min), and are more likely to be associated with type II/IV radio emission (9 of 12) than low-J events. They also tend to occur in magnetically complex (gamma/delta configuration) active regions (10 of 12) that are large in areal extend (area >445 millionths of a solar hemisphere) on the day of flaring (9 of 12). Of the 9 solar proton events that affected the Earth's environment that were found to be associated with SSC-F events, six were high-J events. Concerning ''geoeffectiveness'', there appears to be no preferential relationship between the value of the J-parameter and the most negative value of the Dst geomagnetic index Dst(min) following the SSC, which is found to usually occur at 6-14 h after SSC onset (18 of 26) and which ranged in value from -1 to -249 (having a median value of about -75). Of the 26 SSC-F events, only 14 can be associated with a Dst(min) less than or equal to -75, and of these only 7 were high-J events. Of the 14 storm-related events (i.e. Dst(min) less than or equal to -75), three have previously been identified as being either ''magnetic clouds'' or ''bidirectional flows'', both manifestations of earthward-directed coronal mass ejections (CMEs). Superposed epoch analysis of selected solar wind parameters and Dst during the interval of storm-related SSC-F events demonstrate that geoeffective SSC-F events tend to be associated with solar wind flows that are faster, greater in magnetic field strength, and have a rotating field which has a strong southward component shortly after SSC onset, in comparison to SSC-F events that do not have Dst(min) less than or equal to -75. Therefore, it is inferred that geoeffective SSC-F events are probably fast earthward-directed CMEs. Although no single parameter is found that can serve as a predictor of high-skill level for determining the geoeffectiveness of an SSC-F event prior to its occurrence at Earth, one finds that knowledge of the flare's hemispheric location and appearance or lack of appearance of a two-ribbon structure is sufficient to correctly postdict the geoeffectiveness of 20 out of 25 of the SSC-F events (80%). Surprisingly, the association or lack of association of metric type II/IV radio emission as a characteristic for determining the geoeffectiveness of the SSC-F events proved unfruitful, as did, to a lesser extent, the duration of the X-ray emission. Copyright (C) 1996 Published by Elsevier Science Ltd RP Wilson, RM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 51 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD MAY PY 1996 VL 44 IS 5 BP 441 EP 464 DI 10.1016/0032-0633(95)00141-7 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UQ313 UT WOS:A1996UQ31300005 ER PT J AU Irvin, DJ Cassidy, PE Meurer, DL Fitch, JW Taylor, DA StClair, A Stoakley, D AF Irvin, DJ Cassidy, PE Meurer, DL Fitch, JW Taylor, DA StClair, A Stoakley, D TI N-methylated copoly(imide amide)s containing hexafluoroisopropylidene SO POLYMER LA English DT Article DE poly(imide amide); hexafluoroisopropylidene; fluoropolymer AB A synthetic method was developed to produce N,N'-dimethylated diamines which were then used to prepare poly(imide amide)s. Thus, N,N'-dimethyl-4,4'-bis(4-aminophenoxy)biphenyl and N,N'-dimethyl-2,2-bis(4-aminophenyl)hexafluoropropane were condensed at 0 degrees C in dimethylacetamide with 2,2-bis[N-(4-chlorocarboxyphenyl)phthalimidyl]hexafluoropropane. The yields were 76-92%, viscosities 0.28-2.26 dl g(-1), water absorptions 0.16-0.37 wt% and thermal stabilities around 460 degrees C by thermogravimetric analysis. The addition of the methyl group caused lower molecular weights but superior thermal stability (isothermally) and decreased colour. Copyright (C) 1996 Elsevier Science Ltd. C1 SW TEXAS STATE UNIV,DEPT CHEM,SAN MARCOS,TX 78666. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 15 TC 7 Z9 7 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0032-3861 J9 POLYMER JI Polymer PD MAY PY 1996 VL 37 IS 11 BP 2227 EP 2232 DI 10.1016/0032-3861(96)85868-X PG 6 WC Polymer Science SC Polymer Science GA UN323 UT WOS:A1996UN32300023 ER PT J AU Barrett, P AF Barrett, P TI Distances to cataclysmic variables using linear polarimetry SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID INTERSTELLAR POLARIZATION; STARS; DUST AB A model-independent method is proposed for estimating the distances to cataclysmic variables (CVs) using linear polarimetry. A polarization versus distance relation is constructed by measuring the linear polarization of field stars along the line nf sight to the CV. The distance of the CV can be estimated by measuring its polarization and by assuming its intrinsic polarization is negligible in relation to the interstellar polarization, an assumption that appears to be true in most cases. We show that an accuracy of 6% is achievable by estimating the distance to VW Hyi to be 82+/-5 pc. Rough distance estimates of other CVs with measured polarization are also given. RP Barrett, P (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 6601,GREENBELT,MD 20771, USA. NR 30 TC 13 Z9 14 U1 0 U2 1 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD MAY PY 1996 VL 108 IS 723 BP 412 EP 418 DI 10.1086/133742 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UL015 UT WOS:A1996UL01500006 ER PT J AU Chao, BF Gross, RS Han, YB AF Chao, BF Gross, RS Han, YB TI Seismic excitation of the polar motion, 1977-1993 SO PURE AND APPLIED GEOPHYSICS LA English DT Article; Proceedings Paper CT IUTAM/IASPEI Symposium on Mechanics Problems in Geodynamics CY SEP 05-09, 1994 CL BEIJING, PEOPLES R CHINA SP IUTAM, IASPEI DE earthquake; polar motion; earth rotation ID CHANDLER-WOBBLE; EARTHQUAKES; ROTATION AB The mass redistribution in the earth as a result of an earthquake faulting changes the earth's inertia tensor, and hence its rotation. Using the complete formulae developed by CHAO and GROSS (1987) based on the normal mode theory, we calculated the earthquake-induced polar motion excitation for the largest 11,015 earthquakes that occurred during 1977.0-1993.6. The seismic excitations in this period are found to be two orders of magnitude below the detection threshold even with today's high precision earth rotation measurements. However, it was calculated that an earthquake of only one tenth the size of the great 1960 Chile event, if happened today, could be comfortably detected in polar motion observations. Furthermore, collectively these seismic excitations have a strong statistical tendency to nudge the pole towards similar to 140 degrees E, away from the actually observed polar drift direction. This non-random behavior, similarly found in other earthquake-induced changes in earth rotation and low-degree gravitational field by CHAO and GROSS (1987), manifests some geodynamic behavior yet to be explored. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CHINESE ACAD SCI,BEIJING ASTRON OBSERV,BEIJING 100080,PEOPLES R CHINA. RP Chao, BF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Chao, Benjamin Fong/N-6156-2013 NR 27 TC 22 Z9 23 U1 0 U2 3 PU BIRKHAUSER VERLAG AG PI BASEL PA PO BOX 133 KLOSTERBERG 23, CH-4010 BASEL, SWITZERLAND SN 0033-4553 J9 PURE APPL GEOPHYS JI Pure Appl. Geophys. PD MAY PY 1996 VL 146 IS 3-4 BP 407 EP 419 DI 10.1007/BF00874727 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UN775 UT WOS:A1996UN77500002 ER PT J AU Spjeldvik, WN AF Spjeldvik, WN TI Numerical modeling of stably and transiently confined energetic heavy ion radiation in the Earth's magnetosphere SO RADIATION MEASUREMENTS LA English DT Article ID IONOSPHERIC ACCELERATION MECHANISM; ELECTRIC-FIELDS; SATELLITE-OBSERVATIONS; EQUILIBRIUM STRUCTURE; GEOSYNCHRONOUS ORBIT; IONIZED HELIUM; BELT ELECTRONS; CHARGE STATES; PARTICLES; DIFFUSION AB The Earth's radiation belts contain substantial fluxes of electrons and ions of hydrogen, helium, carbon, nitrogen, oxygen, silicon, iron and other ion species. In the early space exploration era it was thought that hydrogen ions (protons) were the dominant ion species with only minor contributions of helium and heavier ions. Sophisticated instrumentation flown on modern spacecraft have shown that the heavier ion species can be very important and even be the dominant contributor to the Earth's trapped particle environment when relative comparison is viewed in terms of total ion energy rather than energy per nucleon. In such comparisons it is found that helium ions can compete favorably with hydrogen in relative abundance, and that at MeV energies oxygen and even iron ions can be very significant. In contrast, comparison of ionic composition generally tends to favor protons in the upper keV and MeV energy ranges when energy per nucleon is considered. Copyright (C) 1996 Elsevier Science Ltd. C1 NASA,WASHINGTON,DC 20546. RP Spjeldvik, WN (reprint author), WEBER STATE COLL,DEPT PHYS,OGDEN,UT 84403, USA. NR 99 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 1350-4487 J9 RADIAT MEAS JI Radiat. Meas. PD MAY PY 1996 VL 26 IS 3 BP 309 EP 320 DI 10.1016/1350-4487(96)00059-5 PG 12 WC Nuclear Science & Technology SC Nuclear Science & Technology GA VK744 UT WOS:A1996VK74400004 ER PT J AU Hoflund, GB Gardner, SD Schryer, DR Upchurch, BT Kielin, EJ AF Hoflund, GB Gardner, SD Schryer, DR Upchurch, BT Kielin, EJ TI Influence of promoters on the performance of Au/MnOx and Pt/SnOx/SiO2 low-temperature CO oxidation catalysts SO REACTION KINETICS AND CATALYSIS LETTERS LA English DT Article DE low-temperature CO oxidation; promoters; platinized tin oxide; gold on manganese oxide ID REDUCIBLE OXIDE MATERIALS; CARBON-MONOXIDE; BEHAVIOR; TIO2 AB The influence of promoters on Pt/SnOx/SiO2 and Au/MnOx low-temperature CO oxidation catalysts has been investigated under stoichiometric reaction conditions with no CO2 added to the feed gas. The performance of Pt/SnOx/SiO2 catalysts is improved significantly by the addition of 1 wt.% Fe but reduced by the addition of 5 wt.% Fe, 1 wt.% Sb, 5 wt.% Sb, 1 wt.% As, 5 wt.% As and 1.8 wt.% P. The performance of Au/MnOx is improved significantly by the addition of 1 at.% Ce but reduced by the addition of 1 at.% Co. For the catalysts and conditions examined, the Au/MnOx catalysts are superior to the Pt/SnOx/SiO2 catalysts with respect to both activity and decay characteristics. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. RP Hoflund, GB (reprint author), UNIV FLORIDA, DEPT CHEM ENGN, GAINESVILLE, FL 32611 USA. NR 23 TC 17 Z9 17 U1 0 U2 3 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0133-1736 J9 REACT KINET CATAL L JI React. Kinet. Catal. Lett. PD MAY PY 1996 VL 58 IS 1 BP 19 EP 26 DI 10.1007/BF02071100 PG 8 WC Chemistry, Physical SC Chemistry GA VH686 UT WOS:A1996VH68600004 ER PT J AU Kimes, DS Holben, BN Nickeson, JE McKee, WA AF Kimes, DS Holben, BN Nickeson, JE McKee, WA TI Extracting forest age in a Pacific Northwest Forest from thematic mapper and topographic data SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID NEURAL NETWORKS; CLASSIFICATION; MODEL AB The feasibility of extracting forest age of young stands (< 50 yr) in a Pacific Northwest Forest using Landsat Thematic Mapper (TM) spectral bands and topographic information was explored using a neural network approach. Understanding the changes of forest fragmentation through time are important for assessing alterations in ecosystem processes (forest productivity, species diversity, nutrient cycling, carbon flux, hydrology, spread of pests, etc.) and wildlife habitat and populations. The study area teas the H.J. Andrews Experimental Forest on the Blue River Ranger District of the Willamette National Forest in western Oregon. Timber harvesting has occurred in this forest over the past 45 years and has a recorded forest management history. The study area was extracted from a georeferenced TM scene acquired on 7 July 1991. A coincident digital terrain model (DTM) derived from digital topographic elevation data was also acquired. Using this DTM and an image processing software package, slope and aspect images were generated over the study area. Sites were chosen to cover the entire range of forest stand age and slope and aspect. The oldest recorded clearcut stands were logged in 1950. A number of sites were chosen as primary forest which had no recorded history of cutting. Various feed-forward neural networks trained with back propagation were tested to predict forest age from TM data and topographic data. The results demonstrated that neural networks can be used as an initial model for inferring forest age. The best network was a 6-->5-->1 structure with inputs of TM Bands 3, 4, and 5, elevation, slope and aspect. The rms values of the predicted forest age were on the order of 5 years. TM Bands 1, 2, 6, and 7 did not significantly add information to the network for learning forest age. Furthermore, the results suggest that topographic information (elevation, slope, and aspect) can be effectively utilized by a neural network approach. The results of the network approach were significantly better than corresponding linear systems. C1 HUGHES STX CORP,LANHAM,MD. OREGON STATE UNIV,DEPT FOREST SCI,CORVALLIS,OR 97331. RP Kimes, DS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,CODE 923,GREENBELT,MD 20771, USA. NR 30 TC 29 Z9 29 U1 0 U2 8 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD MAY PY 1996 VL 56 IS 2 BP 133 EP 140 DI 10.1016/0034-4257(95)00230-8 PG 8 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA UR751 UT WOS:A1996UR75100006 ER PT J AU LeClair, LR Trajmar, S Khakoo, MA Nickel, JC AF LeClair, LR Trajmar, S Khakoo, MA Nickel, JC TI Time-of-flight spectrometer for measuring inelastic to elastic differential cross-section ratios for electron-gas scattering SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID IMPACT IONIZATION; EXCITATION; HELIUM AB We describe a crossed electron beam-atomic beam apparatus which utilizes a pulsed electron gull and field free drift tube to obtain time-of-flight (TOF) spectra of electrons scattered from atoms and molecules. This apparatus was constructed for the purpose of obtaining inelastic-to-elastic differential cross-section (DCS) ratios in the energy range extending from threshold to several eV above the threshold of the inelastic channel. The TOF approach eliminates the need for complicated calibration procedures required when using conventional electrostatic electron energy-loss spectroscopy (EELS) at these low energies. The characteristics of the apparatus will be given, along with representative TOF spectra from carbon monoxide. From those spectra we obtained DCS ratios at 90 degrees scattering angle for excitation of the a(3) Pi state of CO, in the impact energy range of 6-15 eV. These ratios were measured with uncertainties as small as +/-4%, which represents a substantial improvement over previous measurements in this energy range. This demonstrates the feasibility of using the TOF technique to measure DCS ratios which in turn can serve as secondary standards to normalize other inelastic DCSs obtained from measurements with EELS. (C) 1996 American Institute of Physics. C1 CALIF STATE UNIV FULLERTON,DEPT PHYS,FULLERTON,CA 92634. UNIV CALIF RIVERSIDE,DEPT PHYS,RIVERSIDE,CA 92521. RP LeClair, LR (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 30 TC 18 Z9 18 U1 0 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD MAY PY 1996 VL 67 IS 5 BP 1753 EP 1760 DI 10.1063/1.1146970 PG 8 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA UK828 UT WOS:A1996UK82800009 ER PT J AU Biswas, A Weller, T Katehi, LPB AF Biswas, A Weller, T Katehi, LPB TI Stress determination of micromembranes using laser vibrometry SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID X-RAY MASKS; MEMBRANES; FILMS AB A laser vibrometry based dynamic technique for biaxial residual stress determination in micromembranes is reported. Layered, low pressure chemical vapor deposition grown, rectangular shaped micromembranes are ultrasonically excited. The resulting micromembrane displacement, as a function of frequency and position, is recorded to yield resonance frequencies and associated vibrational mode numbers. The stress is determined from this information. Vibrations forced from ultrasonic pressure (similar to 25 Pa) resulted in peak displacements of tens of nanometers at resonance. For the sample set studied, the (3,1) mode resonance peak displayed the least damping in atmospheric testing and was used to establish stress levels similar to 10(8) N/m(2). A trend for this stress showing an overall decrease by similar to 40% as a result of thermomechanical cycling was identified. (C) 1996 American Institute of Physics. C1 UNIV S FLORIDA,DEPT ELECT ENGN,MICROWAVE & WIRELESS RES GRP,TAMPA,FL 33620. UNIV MICHIGAN,RADIAT LAB,ANN ARBOR,MI 48109. RP Biswas, A (reprint author), CALTECH,JET PROP LAB,ADV MAT & FLUID PROC TECHNOL GRP,4800 OAK GROVE DR,MS 183-401,PASADENA,CA 91109, USA. NR 17 TC 7 Z9 7 U1 0 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD MAY PY 1996 VL 67 IS 5 BP 1965 EP 1969 DI 10.1063/1.1146952 PG 5 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA UK828 UT WOS:A1996UK82800043 ER PT J AU Smith, MF Lockwood, M AF Smith, MF Lockwood, M TI Earth's magnetospheric cusps SO REVIEWS OF GEOPHYSICS LA English DT Review ID FLUX-TRANSFER EVENTS; INTERPLANETARY MAGNETIC-FIELD; LATITUDE BOUNDARY-LAYER; ROTATIONAL MAGNETOPAUSE DISCONTINUITIES; PARTICLE-PRECIPITATION CHARACTERISTICS; LARGE CONVECTIVE VELOCITIES; IMPULSIVE PLASMA TRANSPORT; DAYSIDE AURORAL ACTIVITY; ACCELERATED FLOW EVENTS; POLAR-CAP BOUNDARY AB Earth's cusps are magnetic field features in the magnetosphere associated with regions through which plasma from the Sun can have direct access to the upper atmosphere. Recently, new ground-based observations, combined with in situ satellite measurements, have led the way in reinterpreting cusp signatures. These observations, combined with theoretical advances, have stimulated new interest in the solar wind-magnetosphere-ionosphere coupling chain. This coupling process is important because it causes both momentum and energy from the solar wind to enter into the near-Earth region. Here we describe the current ideas concerning the cusps and the supporting observational evidence which have evolved over the past 30 years. We include discussion on the plasma entry process, particle motion between the magnetopause and ionosphere, ground optical and radar measurements, and transient events. We also review the important questions that remain to be answered. C1 RUTHERFORD APPLETON LAB,DIDCOT OX11 0QX,OXON,ENGLAND. RP Smith, MF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 696,GREENBELT,MD 20771, USA. RI Lockwood, Mike/G-1030-2011 OI Lockwood, Mike/0000-0002-7397-2172 NR 217 TC 134 Z9 136 U1 2 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 8755-1209 J9 REV GEOPHYS JI Rev. Geophys. PD MAY PY 1996 VL 34 IS 2 BP 233 EP 260 DI 10.1029/96RG00893 PG 28 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UR752 UT WOS:A1996UR75200003 ER PT J AU Smith, EJ Marsden, RG AF Smith, EJ Marsden, RG TI Shooting the solar breeze SO SCIENCES-NEW YORK LA English DT Article C1 EUROPEAN SPACE TECHNOL CTR,NOORDWIJK,NETHERLANDS. RP Smith, EJ (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0036-861X J9 SCIENCES JI Sci.-New York PD MAY-JUN PY 1996 VL 36 IS 3 BP 22 EP 26 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UH317 UT WOS:A1996UH31700023 ER PT J AU Rockstad, HK Tang, TK Reynolds, JK Kenny, TW Kaiser, WJ Gabrielson, TB AF Rockstad, HK Tang, TK Reynolds, JK Kenny, TW Kaiser, WJ Gabrielson, TB TI A miniature, high-sensitivity, electron tunneling accelerometer SO SENSORS AND ACTUATORS A-PHYSICAL LA English DT Article; Proceedings Paper CT 8th International Conference on Solid-State Sensors and Actuators (Eurosensors IX) CY JUN 25-29, 1995 CL STOCKHOLM, SWEDEN DE electron tunneling; accelerometers; micromachining; hydrophones; acoustic sensors ID DETECTOR; SENSOR; TRANSDUCER; NOISE AB Prototype low-noise miniature accelerometers have been fabricated with electron-tunneling transducers. The electron-tunneling transducer permits detection of small displacements of the proof mass with high electrical response; such a transducer is essential for a high-performance miniature accelerometer. Prototype accelerometers have shown self-noise of approximately 10(-7) g (Hz)(-1/2) or less between 10 and 200 Hz, and close to 10(-8) g (Hz)(-1/2) near the resonance frequency of 100 Hz. Directivity measurements give nulls at least 50 dB below the maximum. A dual-axis prototype designed for underwater acoustic applications is packaged in an 8 cm(3) volume with a mass of 8 g. C1 STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305. UNIV CALIF LOS ANGELES,DEPT ELECT ENGN,LOS ANGELES,CA 90024. USN,AIR WARFARE CTR,DIV AIRCRAFT,WARMINSTER,PA 18974. RP Rockstad, HK (reprint author), CALTECH,CTR SPACE MICROELECTR TECHNOL,JET PROPULS LAB,PASADENA,CA 91109, USA. NR 18 TC 21 Z9 28 U1 2 U2 12 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0924-4247 J9 SENSOR ACTUAT A-PHYS JI Sens. Actuator A-Phys. PD MAY PY 1996 VL 53 IS 1-3 BP 227 EP 231 DI 10.1016/0924-4247(96)01128-4 PG 5 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA UV649 UT WOS:A1996UV64900002 ER PT J AU Abarbanel, S Gottlieb, D Carpenter, MH AF Abarbanel, S Gottlieb, D Carpenter, MH TI On the removal of boundary errors caused by Runge-Kutta integration of nonlinear partial differential equations SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE Runge-Kutta scheme; temporal accuracy; time-dependent boundary conditions ID ACCURATE AB The temporal integration of hyperbolic partial differential equations (PDEs) has been shown to lead sometimes to the deterioration of accuracy of the solution because of boundary conditions. A procedure for removal of this error in the linear case has been established previously. In this paper we consider hyperbolic PDEs (linear and nonlinear) whose boundary treatment is accomplished via the simultaneous approximation term (SAT) procedure. A methodology is presented for recovery of the full order of accuracy and has been applied to the case of a fourth-order explicit finite-difference scheme. C1 BROWN UNIV,DIV APPL MATH,PROVIDENCE,RI 02912. NASA,LANGLEY RES CTR,DIV FLUID MECH & ACOUST,AERONAUT & ACOUST METHODS BRANCH,HAMPTON,VA 23681. RP Abarbanel, S (reprint author), TEL AVIV UNIV,DEPT MATH SCI,DIV APPL MATH,IL-69978 TEL AVIV,ISRAEL. NR 4 TC 26 Z9 26 U1 0 U2 2 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER PH#382-9800, PHILADELPHIA, PA 19104-2688 SN 1064-8275 J9 SIAM J SCI COMPUT JI SIAM J. Sci. Comput. PD MAY PY 1996 VL 17 IS 3 BP 777 EP 782 DI 10.1137/S1064827595282520 PG 6 WC Mathematics, Applied SC Mathematics GA UG766 UT WOS:A1996UG76600016 ER PT J AU Healy, RW Striegl, RG Russell, TF Hutchinson, GL Livingston, GP AF Healy, RW Striegl, RG Russell, TF Hutchinson, GL Livingston, GP TI Numerical evaluation of static-chamber measurements of soil-atmosphere gas exchange: Identification of physical processes SO SOIL SCIENCE SOCIETY OF AMERICA JOURNAL LA English DT Article ID NITROUS-OXIDE; FIELD MEASUREMENT; FLUX; TRANSPORT; N2O AB The exchange of gases between soil and atmosphere is an important process that affects atmospheric chemistry and therefore climate. The static-chamber method is the most commonly used technique for estimating the rate of that exchange. We examined the method under hypothetical field conditions where diffusion was the only mechanism for gas transport and the atmosphere outside the chamber was maintained at a fixed concentration. Analytical and numerical solutions to the soil gas diffusion equation in one and three dimensions demonstrated that gas flux density to a static chamber deployed on the soil surface was less in magnitude than the ambient exchange rate in the absence of the chamber. This discrepancy, which increased with chamber deployment time and air-filled porosity of soil, is attributed to two physical factors: distortion of the soil gas concentration gradient (the magnitude was decreased in the vertical component and increased in the radial component) and the slow transport rate of diffusion relative to mixing within the chamber. Instantaneous flux density to a chamber decreased continuously with time; steepest decreases occurred so quickly following deployment and in response to such slight changes in mean chamber headspace concentration that they would likely go undetected by most field procedures. Adverse influences of these factors were reduced by mixing the chamber headspace, minimizing deployment time, maximizing the height and radius of the chamber, and pushing the rim of the chamber into the soil. Nonlinear models were superior to a linear regression model for estimating flux densities from mean headspace concentrations, suggesting that linearity of headspace concentration with time was not necessarily a good indicator of measurement accuracy. C1 UNIV COLORADO, DEPT MATH, DENVER, CO 80217 USA. USDA ARS, NPA, NAT RESOURCES RES CTR, SOIL PLANT NUTR RES UNIT, FT COLLINS, CO 80522 USA. NASA, AMES RES CTR, DIV EARTH SCI, JOHNSON CONTROLS WORLD SERV, MOFFETT FIELD, CA 94035 USA. RP Healy, RW (reprint author), US GEOL SURVEY, DENVER FED CTR, DIV WATER RESOURCES, MS 413, BOX 25046, LAKEWOOD, CO 80215 USA. NR 29 TC 166 Z9 173 U1 9 U2 66 PU SOIL SCI SOC AMER PI MADISON PA 677 SOUTH SEGOE ROAD, MADISON, WI 53711 USA SN 0361-5995 EI 1435-0661 J9 SOIL SCI SOC AM J JI Soil Sci. Soc. Am. J. PD MAY-JUN PY 1996 VL 60 IS 3 BP 740 EP 747 PG 8 WC Soil Science SC Agriculture GA UK989 UT WOS:A1996UK98900007 ER PT J AU Kariyappa, R AF Kariyappa, R TI Solar oscillations in strong and weak Fraunhofer lines over a quiet region SO SOLAR PHYSICS LA English DT Article ID CHROMOSPHERE; ATMOSPHERE; DYNAMICS AB We have analysed a 35-min-long time sequence of spectra in the Ca II H line, NaI D1 and D2 lines, and in a large number of strong and weak Fe I lines taken over a quiet region at the center of the solar disk. The time series of these spectra have been observed simultaneously in these lines under high spatial, spectral, and temporal resolution at the Vacuum Tower Telescope (VTT) of the Sacramento Peak Observatory. We have derived the line profiles and their central intensity values at the sites of the chromospheric bright points, which are visible in the H line for easy identification. We have done a power spectrum analysis for all the lines, using their central intensity values to determine the period of oscillations. It is shown that the 3 Fe I fines, present similar to 23 Angstrom away from the core of the H line representing the pure photospheric lines, Na I D1 and D2 lines, 6 Fe I lines at the wings of H line, and Ca II H line exhibit 5-min, 4.05-min, 3.96-min, and 3.2-min periodicity in their intensity oscillations, respectively. Since all these lines form at different heights in the solar atmosphere from low photosphere to middle chromosphere and show different periodicities in their intensity oscillations, these studies may give an idea about the spatial and temporal relation between the photospheric and chromospheric intensities. Therefore these studies will help to better understand the physical mechanisms of solar oscillations. It is clearly seen that the period of intensity oscillations decreases outward from the low photosphere to the middle chromosphere. Since we have studied a single feature at a time on the Sun (i.e., bright points seen in the H line) in all these spectral lines simultaneously, this may explain about the footpoints of the bright points, the origin of 3-min oscillations, and the relation to other oscillations pertaining to these locations on the Sun. We have concluded that 80% of the bright points are associated with dark elements in the true continuum, and they may seem to have a relationship with the dark intergranular lanes of the photosphere, after carefully examining the brightness (bright threads) extending from the core to the far wings of the H line at the locations of a large number of bright points, using their time sequence of spectra. RP Kariyappa, R (reprint author), CALTECH,JET PROP LAB,M-S 169-506,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 11 TC 8 Z9 8 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD MAY PY 1996 VL 165 IS 2 BP 211 EP 222 DI 10.1007/BF00149711 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UD337 UT WOS:A1996UD33700001 ER PT J AU Chang, ES Deming, D AF Chang, ES Deming, D TI Observation of infrared lines in a prominence at 1-5 microns SO SOLAR PHYSICS LA English DT Article ID QUIESCENT PROMINENCES; HYDROGEN SPECTRUM; ENERGY; MODEL AB We have observed 11 hydrogen and 3 helium lines in a quiescent prominence; none have been previously observed except for the He 10830 line. In contrast to Zirker's results based on longer-wavelength infrared lines, we find no net velocity shift, Doppler widths narrower than his by more than 30%, and a hydrogen excitation temperature 3 times higher. From the line intensity method, we find a helium temperature of 5300(+/-200) K and a hydrogen temperature of 10900(+/-1900) K, in reasonable agreement with the findings of visible line studies. We conclude that helium lines are formed in the central region while hydrogen lines are formed around the edges of the prominence. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Chang, ES (reprint author), UNIV MASSACHUSETTS,DEPT PHYS & ASTRON,AMHERST,MA 01003, USA. NR 20 TC 7 Z9 7 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD MAY PY 1996 VL 165 IS 2 BP 257 EP 274 DI 10.1007/BF00149714 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UD337 UT WOS:A1996UD33700004 ER PT J AU Gabriel, SB Feynman, J AF Gabriel, SB Feynman, J TI Power-law distribution for solar energetic proton events SO SOLAR PHYSICS LA English DT Article ID PARTICLE EVENTS; FLUENCE MODEL; ACCELERATION; PARAMETERS; FLARES; CYCLES AB Analyses of the time-integrated fluxes of solar energetic particle events during the period 1965-1990 show that the differential distribution of events with Aux F is given by a power law, with indices between 1.2 and 1.4 depending on energy. The power law represents a good fit over three to four orders of magnitude in fluence. Similar power-law distributions have been found for peak proton and electron fluxes, X-ray flares and radio and type III bursts. At fluences greater than 10(9) cm(-2), the slope of the distribution steepens and beyond 10(10) cm(-2) the power-law index is estimated to be 3.5. At energies greater than 10 MeV, the slope of the distribution was found to be essentially independent of solar cycle, when the active years of solar cycles 20, 21, and 22 were analysed. The results presented are the first for a complete period of 27 years, covering nearly 3 complete solar cycles. Other new aspects of the results include the invariance of the exponent with solar cycle and also with integral energy. C1 CALTECH, JET PROP LAB, PASADENA, CA USA. RP Gabriel, SB (reprint author), UNIV SOUTHAMPTON, DEPT AERONAUT & ASTRONAUT, SOUTHAMPTON SO9 5NH, HANTS, ENGLAND. OI Gabriel, Stephen B./0000-0002-3226-8496 NR 22 TC 31 Z9 31 U1 0 U2 1 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD MAY PY 1996 VL 165 IS 2 BP 337 EP 346 DI 10.1007/BF00149718 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UD337 UT WOS:A1996UD33700008 ER PT J AU Roth, M DeKeyser, J Kuznetsova, MM AF Roth, M DeKeyser, J Kuznetsova, MM TI Vlasov theory of the equilibrium structure of tangential discontinuities in space plasmas SO SPACE SCIENCE REVIEWS LA English DT Review ID MAGNETOPAUSE CURRENT LAYER; HYBRID-DRIFT INSTABILITY; FLUX-TRANSFER EVENTS; DAYSIDE MAGNETOPAUSE; TEARING MODES; WAVE TURBULENCE; SHEET BOUNDARY; KINETIC-THEORY; ISEE 1; STABILITY AB Extensive theoretical work has been performed on the equilibrium structure of tangential discontinuities (TDs) in collisionless plasmas. This paper reviews kinetic models based on steady-state solutions of the Vlasov equation. It is shown that most of the existing models are special cases of a generalized multi-species model. In this generalized model all particle populations - from both outer regions and from inside the layer - are described using a unique formalism for the velocity distribution functions. Because of their historical importance, the Harris and Sestero models are reviewed and deduced from the generalized model. The Lee and Kan model is also a special case of the generalized model. The generalized model, however, is also able to describe TDs with velocity shear and large angles of magnetic field rotation. Such a multi-species model with a large number of free parameters and different gradient scales illustrates many observable features of TDs, including their multiscale fine structure. Particular attention is paid to the magnetopause. Observed magnetopause crossings are simulated. The effects of the relative flow velocity and asymmetrical magnetic field profiles on the structure of the magnetopause and on its stability with respect to tearing perturbations are discussed. We also present calculations that demonstrate the potential of the generalized model in explaining the origin of discrete auroral arcs. Numerical simulations of solar wind TDs with heavy ions and a large spectrum of thicknesses are also feasible. This indicates that such a model is of fundamental importance for understanding the detailed structure of solar wind TDs, like those observed by the interplanetary spacecraft ULYSSES. The problems associated with the one-dimensional, time-independent Vlasov approach are discussed and a variational principle is suggested to reduce the arbitrariness resulting from the large number of free parameters. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. IKI,INST SPACE RES,MOSCOW,RUSSIA. RP Roth, M (reprint author), BELGIAN INST SPACE AERON,B-1180 BRUSSELS,BELGIUM. RI Kuznetsova, Maria/F-6840-2012 NR 84 TC 62 Z9 62 U1 0 U2 5 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1996 VL 76 IS 3-4 BP 251 EP 317 PG 67 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UH792 UT WOS:A1996UH79200003 ER PT J AU Sanders, JH AF Sanders, JH TI Investigation of grain boundary chemistry in Al-Li 2195 welds using Auger electron spectroscopy SO THIN SOLID FILMS LA English DT Article DE aluminium; Auger electron spectroscopy; grain boundary; metals ID ALLOY AB Al-Li alloy 2195 is a low-density material with high fracture toughness that is particularly well-suited for aerospace systems. It will replace Al-Cu alloy 2219 in the Super Light Weight Tank (SLWT), a modified version of the external tank being developed for the Space Shuttle to support Space Station deployment. Recent efforts have focused enjoining 2195 with variable polarity plasma are welding, as well as repairing 2195 welds with tungsten inert gas techniques. During this study, Auger electron spectroscopy (AES) was used to examine grain boundary chemistry in 2195 welds. Results indicated that weld integrity depends on whether (and how much) the grain boundaries are covered with thin films comprised of a mixture of discontinuous Al2O3 in Al (Al/Al2O3), which form during weld solidification. O was probably introduced as a contaminant in the shielding gases, occurring at low levels considered negligible for Al alloys that do not contain Li. However, oxidation kinetics in 2195 are increased by Li enrichment of small quantities of Al2O3, further enhancing thin film formation at the grain boundaries. Al2O3 can ultimately occupy sufficient grain boundary area to degrade the material's mechanical properties, producing negative effects that are compounded by the cumulative heat input of multi-pass repair welding. RP Sanders, JH (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,IIT,RES INST,MET RES FACIL,BLDG 4618,MARSHALL SPACE FLIGHT CTR,AL 35812, USA. NR 9 TC 8 Z9 10 U1 2 U2 6 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0040-6090 J9 THIN SOLID FILMS JI Thin Solid Films PD MAY 1 PY 1996 VL 277 IS 1-2 BP 121 EP 127 DI 10.1016/0040-6090(95)06865-1 PG 7 WC Materials Science, Multidisciplinary; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA UV528 UT WOS:A1996UV52800010 ER PT J AU Gouweleeuw, BT vandeGriend, AA Owe, M AF Gouweleeuw, BT vandeGriend, AA Owe, M TI Estimation of ''effective'' soil hydraulic properties by topsoil moisture and evaporation modeling applied to an arable site in central Spain SO WATER RESOURCES RESEARCH LA English DT Article ID SURFACE MOISTURE; AREA AB A surface moisture model for large-scale semiarid land application has been extended with a moisture flow routine for capillary flow. The model has been applied to a field-scale data set of topsoil moisture and latent heat flux of an arable site in central Spain. A comparison of the soil hydraulic properties, determined by model simulations and measurements in the field, demonstrates the capability of the model to determine these properties out of a range of soil classes as defined according to the parameterization by Clapp and Hornberger [1978]. Estimation of area average or ''effective'' soil physical parameters according to this approach requires time series of topsoil moisture and actual evapotranspiration on a patch or regional scale. Therefore this approach has potential for use with remotely sensed data. C1 NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,GREENBELT,MD 20771. RP Gouweleeuw, BT (reprint author), FREE UNIV AMSTERDAM,INST EARTH SCI,DE BOELELAAN 1085,1081 HV AMSTERDAM,NETHERLANDS. RI Gouweleeuw, Ben/A-8200-2012 NR 20 TC 4 Z9 4 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0043-1397 J9 WATER RESOUR RES JI Water Resour. Res. PD MAY PY 1996 VL 32 IS 5 BP 1387 EP 1392 DI 10.1029/96WR00197 PG 6 WC Environmental Sciences; Limnology; Water Resources SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Water Resources GA UH882 UT WOS:A1996UH88200022 ER PT J AU Kaljurand, M Valentin, JR Shao, M AF Kaljurand, M Valentin, JR Shao, M TI Feedback shift register sequences versus uniformly distributed random sequences for correlation chromatography SO ANALYTICA CHIMICA ACTA LA English DT Article DE chromatography; chemometrics; feedback shift register AB Two alternative input sequences are commonly employed in correlation chromatography (CC). They are sequences derived according to the algorithm of the feedback shift register (i.e., pseudo random binary sequences (PRBS)) and sequences derived by using the uniform random binary sequences (URBS). These two sequences are compared. By applying the ''cleaning'' data processing technique to the correlograms that result from these sequences, we show that when the PRBS is used the S/N of the correlogram is much higher than the one resulting from using URBS. RP Kaljurand, M (reprint author), NASA,AMES RES CTR,SSS 239-12,MOFFETT FIELD,CA 94035, USA. NR 9 TC 4 Z9 4 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0003-2670 J9 ANAL CHIM ACTA JI Anal. Chim. Acta PD APR 30 PY 1996 VL 324 IS 1 BP 29 EP 36 DI 10.1016/0003-2670(95)00584-6 PG 8 WC Chemistry, Analytical SC Chemistry GA UL213 UT WOS:A1996UL21300004 PM 11539201 ER PT J AU Cooper, D Pellis, N AF Cooper, D Pellis, N TI Cell-cell and cell-matrix interactions aid mitogen induced T lymphocyte activation in simulated microgravity. SO FASEB JOURNAL LA English DT Meeting Abstract C1 UNIV TEXAS,GSBS,HOUSTON,TX. UNIV SPACE RES ASSOC,HOUSTON,TX. NASA,LYNDON B JOHNSON SPACE CTR,BIOTECHNOL PROGRAM,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD APR 30 PY 1996 VL 10 IS 6 BP 2646 EP 2646 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA UK861 UT WOS:A1996UK86102875 ER PT J AU CampbellWashington, J Craig, JN Baker, T Risin, D Goodwin, TJ Pellis, NR AF CampbellWashington, J Craig, JN Baker, T Risin, D Goodwin, TJ Pellis, NR TI Differential display RT-PCR analysis and cloning of novel mRNAs expressed in HL-60 promyelocytic cells cultured in simulated microgravity conditions. SO FASEB JOURNAL LA English DT Meeting Abstract C1 KRUG LIFE SCI,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD APR 30 PY 1996 VL 10 IS 6 BP 3030 EP 3030 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA UK861 UT WOS:A1996UK86103259 ER PT J AU Woods, TN Prinz, DK Rottman, GJ London, J Crane, PC Cebula, RP Hilsenrath, E Brueckner, GE Andrews, MD White, OR VanHoosier, ME Floyd, LE Herring, LC Knapp, BG Pankratz, CK Reiser, PA AF Woods, TN Prinz, DK Rottman, GJ London, J Crane, PC Cebula, RP Hilsenrath, E Brueckner, GE Andrews, MD White, OR VanHoosier, ME Floyd, LE Herring, LC Knapp, BG Pankratz, CK Reiser, PA TI Validation of the UARS solar ultraviolet irradiances: Comparison with the ATLAS 1 and 2 measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MONITOR-SUSIM-EXPERIMENT; INSTRUMENT; ATMOSPHERE; STANDARDS; BOARD; OZONE; NM AB The measurements of the solar ultraviolet spectral irradiance made by the two Upper Atmosphere Research Satellite (UARS) solar instruments, Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) and SOLar STellar Irradiance Comparison Experiment (SOLSTICE), are compared with same-day measurements by two solar instruments on the shuttle ATmospheric Laboratory for Applications and Science (ATLAS) missions, ATLAS SUSIM and Shuttle Solar Backscatter UltraViolet (SSBUV) experiment. These measurements from the four instruments agree to within the 2 sigma uncertainty of any one instrument, which is 5 to 10% for all wavelengths above 160 nm and for strong emission features below 160 nm. Additionally, the long-term relative accuracy of the two UARS data sets is better than the original 2% goal, especially at wavelengths greater than 160 nm. This level of agreement is credited to accurate preflight calibrations coupled with comprehensive inflight calibrations to track instrument degradation. Two solar irradiance spectra, 119 to 410 nm, are presented; the first combines observations from UARS SUSIM and UARS SOLSTICE taken on March 29, 1992, during the ATLAS 1 mission, and the second combines spectra for April 15, 1993, during the ATLAS 2 mission. The ATLAS 1 mission coincided with the initial decline from the maximum of solar cycle 22 when solar activity was relatively high. The ATLAS 2 mission occurred somewhat later during the declining phase of the solar cycle 22 when solar activity was more moderate. C1 USN, RES LAB, EO HULBURT CTR SPACE RES, WASHINGTON, DC 20375 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. HUGHES STX CORP, LANHAM, MD 20706 USA. INTERFEROMETR INC, VIENNA, VA 22182 USA. UNIV COLORADO, DEPT ASTROPHYS PLANETARY & ATMOSPHER SCI, BOULDER, CO 80309 USA. RP Woods, TN (reprint author), NATL CTR ATMOSPHER RES, HIGH ALTITUDE OBSERV, POB 3000, BOULDER, CO 80307 USA. NR 52 TC 250 Z9 251 U1 0 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9541 EP 9569 DI 10.1029/96JD00225 PG 29 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400002 ER PT J AU Gille, JC Bailey, PL Massie, ST Lyjak, LV Edwards, DP Roche, AE Kumer, JB Mergenthaler, JL Gross, MR Hauchecorne, A Keckhut, P McGee, TJ McDermid, IS Miller, AJ Singh, U AF Gille, JC Bailey, PL Massie, ST Lyjak, LV Edwards, DP Roche, AE Kumer, JB Mergenthaler, JL Gross, MR Hauchecorne, A Keckhut, P McGee, TJ McDermid, IS Miller, AJ Singh, U TI Accuracy and precision of cryogenic limb array etalon spectrometer (CLAES) temperature retrievals SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RESEARCH SATELLITE UARS; ATMOSPHERIC-TEMPERATURE; LIDAR; ROCKETSONDE; INTENSITIES; SOUTH; BANDS AB The Cryogenic Limb Array Etalon Spectrometer (CLAES) measured emission from the 792 cm(-1) Q branch of CO2, from which temperature distributions in the stratosphere and low mesosphere were derived, Here we briefly review the measurement technique, concentrating on aspects that affect the temperature determination, Comparison of many pairs of retrievals at the same location (near 32 degrees N or 32 degrees S) measured on sequential orbits (time separation of 96 min) shows a precision ranging from approximately 0.8 K at 68 mbar to about 3.5 K at 0.2 mbar, which agrees with simulations incorporating random noise and short-period spacecraft motions, Comparisons of globally analyzed CLAES data with National Meteorological Center (NMC) and U.K. Meteorological Office (UKMO) analyses show general agreement, with CLAES tending to be cooler by about 2 K, except in the tropics and high-latitude winter conditions. This is supported by comparisons with individual radiosondes and several lidars that indicate that the agreement is within 2 K throughout the profile (except for a narrow layer around 3 mbar). An error analysis also indicates that systematic errors should be roughly 2 K, independent of altitude, The systematic differences at low latitudes appear to be due to tropical waves, which have vertical wavelengths too short to be seen by the TIROS Operational Vertical Sounder (TOVS) instruments. There are no correlative rocketsondes or lidars to help resolve the reasons for the high-latitude differences. Comparisons with other Upper Atmosphere Research Satellite (UARS) data should shed additional light on this question. C1 HUGHES STX CORP, LANHAM, MD 20706 USA. CNRS, SERV AERON, F-91371 VERRIERES LE BUISSON, FRANCE. NOAA, NATL WEATHER SERV, NATL METEOROL CTR, CLIMATE ANAL CTR, WASHINGTON, DC 20233 USA. LOCKHEED PALO ALTO RES LABS, PALO ALTO, CA 94304 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP Gille, JC (reprint author), NATL CTR ATMOSPHER RES, POB 3000, BOULDER, CO 80307 USA. RI Hauchecorne, Alain/A-8489-2013; McGee, Thomas/G-4951-2013 NR 32 TC 31 Z9 31 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9583 EP 9601 DI 10.1029/96JD00052 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400004 ER PT J AU Mergenthaler, JL Kumer, JB Roche, AE Nightingale, RW Potter, JF Gille, JC Massie, ST Bailey, PL Edwards, D Connell, PS Kinnison, DE Gunson, MR Abrams, MC Toon, GC Sen, B Blavier, JF Murcray, DG Murcray, FJ Goldman, A AF Mergenthaler, JL Kumer, JB Roche, AE Nightingale, RW Potter, JF Gille, JC Massie, ST Bailey, PL Edwards, D Connell, PS Kinnison, DE Gunson, MR Abrams, MC Toon, GC Sen, B Blavier, JF Murcray, DG Murcray, FJ Goldman, A TI Validation of CLAES ClONO2 measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CHLORINE NITRATE; OZONE DEPLETION; TRACE GASES; SPECTRA; STRATOSPHERE; SPECTROMETER; ANTARCTICA; HNO3; CONSTITUENTS; TEMPERATURE AB The cryogenic limb array etalon spectrometer (CLAES) aboard the Upper Atmosphere Research Satellite has made extensive measurements of thermal infrared radiation from the Earth's limb from which vertical concentration profiles of several stratospheric gases and multiwavelength aerosol absorption coefficients have been retrieved for the period from January 9, 1992, to May 5, 1993. This work examines stratospheric ClONO2 concentrations from the current calibration and retrieval software which are designated version 7 data. These data provide the first near-global view of this stratospheric species. This work evaluates data quality through (1) an analysis of estimated uncertainties and biases in the remote sensing process, (2) comparison with calculations using a two-dimensional chemical model, (3) comparison with correlative data, and (4) an examination of various known limitations. The precision of CLAES ClONO2 volume mixing ratio retrievals are within 15% in the range (10 < P < 50 mbar). The upper limit on estimated systematic error is 28% in the range (10 < P < 100 mbar) based on studies of error sources in midlatitude retrievals. The global distribution of ClONO2 computed with the Lawrence Livermore National Laboratory two-dimensional stratospheric chemistry model and the CLAES measurements agree qualitatively. However, above the profile peak the calculated concentration frequently exceeds the measurement. CLAES and ATMOS measurements show relatively good midlatitude agreement, suggesting that the major sourer of discrepancy is in the model. A possible explanation in terms of a missing reaction ClO + OH --> HCl + O-2 is suggested. Also, the ClONO2 diurnal cycle constructed from more than 30 days of CLAES data agrees well with the model. The CLAES ClONO2 data differ from correlative data acquired on flights of the shuttle-based ATMOS and balloon-borne instruments by less than 25% on the average in the 10 < P < 50 mbar range. At altitudes above 10 mbar the CLAES measurement is biased low with respect to correlative measurements. This discrepancy at high altitudes is consistent with the analysis showing a large increase of systematic errors above 10 mbar. Heavy tropical volcanic aerosol from the Mount Pinatubo eruption in June 1991 apparently interfered with ClONO2 retrievals in the period before July 1992, causing anomalous peaks in the 20 < P < 30 mbar region accompanied by very small concentrations below the peak (P > 30 mbar). A similar effect associated with thick polar stratospheric clouds is identified. Overall, this validation study indicates that the majority of these data are of good quality and should be very useful in quantitative and qualitative chemical studies of the stratosphere. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. LAWRENCE LIVERMORE NATL LAB, LIVERMORE, CA 94550 USA. UNIV DENVER, DEPT PHYS, DENVER, CO 80210 USA. RP Mergenthaler, JL (reprint author), LOCKHEED PALO ALTO RES LABS, 3251 HANOVER ST, ORG 9120, BLDG 252, PALO ALTO, CA 94304 USA. NR 47 TC 27 Z9 28 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9603 EP 9620 DI 10.1029/96JD00449 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400005 ER PT J AU Kumer, JB Mergenthaler, JL Roche, AE Nightingale, RW Ely, GA Uplinger, WG Gille, JC Massie, ST Bailey, PL Gunson, MR Abrams, MC Toon, GC Sen, B Blavier, JF Stachnik, RA Webster, CR May, RD Murcray, DG Murcray, FJ Goldman, A Traub, WA Jucks, KW Johnson, DG AF Kumer, JB Mergenthaler, JL Roche, AE Nightingale, RW Ely, GA Uplinger, WG Gille, JC Massie, ST Bailey, PL Gunson, MR Abrams, MC Toon, GC Sen, B Blavier, JF Stachnik, RA Webster, CR May, RD Murcray, DG Murcray, FJ Goldman, A Traub, WA Jucks, KW Johnson, DG TI Comparison of correlative data with HNO3 version 7 from the CLAES instrument deployed on the NASA upper atmosphere research satellite SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SIMULTANEOUS INSITU MEASUREMENTS; DIODE-LASER SPECTROMETER; LIMB INFRARED MONITOR; INTERANNUAL VARIABILITY; TRACE GASES; STRATOSPHERE; UARS; RETRIEVAL; OZONE; PERFORMANCE AB The cryogenic limb array etalon spectrometer (CLAES) aboard UARS made near-global measurements of HNO3 and 388 days from January 9, 1992, to April 25, 1993, have been processed to data version 7 (V7). Results from UARS instruments, including CLAES, the improved stratospheric and mesospheric sounder, and the microwave limb sounder, provide the first near-global documentation of the evolution of denitrification in the Antarctic 1992 winter and spring vortex. We provide a description of the CLAES HNO3 V7 quality that includes comparisons with correlative measurements to assess overall quality, accuracy, and precision. Correlative profiles of volume mixing ratio (vmr) included those obtained by the space shuttle deployed ATMOS in two missions, March-April 1992 and April 1993, data from a variety of balloon-borne instruments at midlatitude (11 profiles), and in high-latitude northern winter (six profiles), and LIMS data. In general, the CLAES V7 HNO3 maximum values of vmr were of the order of 6-15% less than correlative for CLAES values less than or equal to 8 parts per billion by volume (ppbv). However, when CLAES peak vmr values were 10 to 13 ppbv, then CLAES values exceeded correlative by 0-7%. The comparisons were within the combined instrumental error estimates, or observed measurement variability, for the large majority of comparisons. As discussed, the retrieval of future versions will utilize updated spectral parameters and will also correct for a small uncompensated drift in radiometric calibration that occurred in the latter part of the mission. This is expected to improve the comparisons in the less than or equal to 8 ppbv range, perhaps at the expense of those in the greater than or equal to 8 ppbv range. The data obtained January 9 to April 15, 1992, in comparison with data obtained January 9 to April 15, 1993, reveal strikingly evident 1-year period deseasonalized trends on a global basis. These trends agree quantitatively with available correlative data suitable fur trend analysis. These include ATMOS in the southern midlatitudes and published longterm time series of HNO3 column obtained at 45 degrees S and 20 degrees N. These trends reveal a large decrease in the southern hemisphere and small increases in the northern hemisphere, such that the global average is toward a decrease. The global average decrease we attribute to the diminishing influence of heterogeneous conversion of N2O5 to HNO3 as the Pinatubo aerosol settles out during this time period, and the HNO3 recovers toward pre-Pinatubo conditions. We establish plausibility that the small increases in the north are due to hemispherically asymmetric QBO-like effects that are strong in the northern hemisphere and weak in the southern hemisphere and are phased to produce an increase in HNO3 over the 1-year time period of just the right magnitude to more than offset decrease due to settling out of the Pinatubo aerosol. Based on this study, our range of confidence in the CLAES HNO3 V7 product is from 70 to 3 mbar, in comparison with correlative data, and the precision on this range is of the order of 0.3-1.0 ppbv. This precision was derived from data repeatability and agrees within a factor of 2 or better with estimates based on instrument characterization and with error estimates embedded within the V7 data. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. UNIV DENVER, DENVER, CO 80210 USA. SMITHSONIAN ASTROPHYS OBSERV, CAMBRIDGE, MA 02138 USA. RP Kumer, JB (reprint author), LOCKHEED PALO ALTO RES LABS, 3251 HANOVER ST, PALO ALTO, CA 94304 USA. NR 57 TC 46 Z9 46 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9621 EP 9656 DI 10.1029/95JD03759 PG 36 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400006 ER PT J AU Kumer, JB Mergenthaler, JL Roche, AE Nightingale, RW Zele, F Gille, JC Massie, ST Bailey, PL Connell, PS Gunson, MR Abrams, MC Toon, GC Sen, B Blavier, JF Smith, SE Taylor, FW AF Kumer, JB Mergenthaler, JL Roche, AE Nightingale, RW Zele, F Gille, JC Massie, ST Bailey, PL Connell, PS Gunson, MR Abrams, MC Toon, GC Sen, B Blavier, JF Smith, SE Taylor, FW TI Comparison of CLAES preliminary N2O5 data with correlative data and a model SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC N2O5; SPACELAB-3; SPECTRA; CH4 AB The cryogenic limb etalon array spectrometer (CLAES) aboard the Upper Atmosphere Research Satellite (UARS) has made near-global measurements of N2O5. Data for 388 days have been processed to version 7 (V7) for the period from January 9, 1992, to April 25, 1993. Results from UARS instruments, including CLAES and the improved stratospheric and mesospheric sounder (ISAMS) provide the first near-global N2O5 measurements. Retrieval below 3.16 mbar is adversely affected by aerosols and above 1.47 mbar by lack of signal and possible instrument effects, so data usage is recommended for just the three ''UARs: pressure surfaces'' 3.16, 2.15, and 1.47 mbar. A comparison of the diurnal data variation with the model suggests there are offsets in the data that are to first order diurnally independent. These offsets are tabulated to facilitate subtraction, which is recommended for most data applications. Candidate mechanisms for the offsets are discussed. Comparisons of CLAES data with the offsets subtracted, with profiles obtained by the shuttle-deployed Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment and concurrent ISAMS profiles, and with a profile obtained by the balloon-borne NASA Jet Propulsion Laboratory (JPL) MARK IV Instrument, show poorest agreement in equatorial regions at 3.15 mbar where CLAES values are larger by about 30 to 40%. At higher altitudes and latitudes the comparison improves and tends toward consistency with systematic error estimates that are based on instrument and retrieval process characterization and range from 14% at 3.16 mbar to 21% at 1.47 mbar. A similar estimate of random CLAES error ranges from 7% at 3.16 mbar 26% at 1.47 mbar. By comparison, the average values of the error estimates generated by the production processing algorithm at 3.16 and 1.47 mbar are 8 and 36%, respectively, and the average values derived from the observed data variability are 19 and 24%. Confidence is enhanced by the good global scale agreement and correlation of CLAES and ISAMS during an N2O5 enhancement event in early-mid-January 1992 polar winter, in which values >5.5 parts per billion at 3.16 mbar by volume are observed. A description of artifacts that may occur at 3.16 mbar and much less frequently at 2.15 mbar, during this and other enhancement conditions, and the demonstrated approach to eliminate these in future versions, is given in the text. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. LAWRENCE LIVERMORE NATL LAB, LIVERMORE, CA 94550 USA. UNIV OXFORD, DEPT PHYS, OXFORD, ENGLAND. RP Kumer, JB (reprint author), LOCKHEED MARTIN PALO ALTO RES LAB, 3251 HANOVER ST, PALO ALTO, CA 94304 USA. NR 33 TC 8 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9657 EP 9677 DI 10.1029/95JD03767 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400007 ER PT J AU Roche, AE Kumer, JB Nightingale, RW Mergenthaler, JL Ely, GA Bailey, PL Massie, ST Gille, JC Edwards, DP Gunson, MR Abrams, MC Toon, GC Webster, CR Traub, WA Jucks, KW Johnson, DG Murcray, DG Murcray, FH Goldman, A Zipf, EC AF Roche, AE Kumer, JB Nightingale, RW Mergenthaler, JL Ely, GA Bailey, PL Massie, ST Gille, JC Edwards, DP Gunson, MR Abrams, MC Toon, GC Webster, CR Traub, WA Jucks, KW Johnson, DG Murcray, DG Murcray, FH Goldman, A Zipf, EC TI Validation of CH4 and N2O measurements by the cryogenic limb array etalon spectrometer instrument on the upper atmosphere research satellite SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SIMULTANEOUS INSITU MEASUREMENTS; DIODE-LASER SPECTROMETER; MIDDLE ATMOSPHERE; NUMERICAL-MODEL; O-3; STRATOSPHERE; CONSTITUENTS; TRANSPORT; DYNAMICS; DATABASE AB CH4 and N2O are useful as dynamical tracers of stratospheric air transport because of their long photochemical lifetimes over a wide range of altitudes. The cryogenic limb array etalon spectrometer (CLAES) instrument on the NASA UARS provided simultaneous global measurements of the altitude profiles of CH4 and N2O mixing ratios in the stratosphere between October 1, 1991, and May 5, 1993. Data between January 9, 1995 and May 5, 1993 (388 days), have been processed using version 7 data processing software, and this paper is concerned with the assessment of the quality of this data set. CLAES is a limb-viewing emission instrument, and approximately 1200 profiles were obtained each 24-hour period for each constituent over a nominal altitude range of 100 to 0.1 mbar (16 to 64 km). Each latitude was sampled 30 times per day between latitudes 34 degrees S and 80 degrees N, or 34 degrees N and 80 degrees S depending on the yaw direction of the UARS, and nearly all local times were sampled in about 36 days. This data set extends the altitude, latitude, and seasonal coverage of previous experiments, particularly in relation to measurements at high winter latitudes. To arrive at estimates of experiment error, we compared CLAES profiles for both gases with a wide variety of correlative data from ground-based, rocket, aircraft, balloon, and space-borne sensors, looked at the repeatability of multiple profiles in the same location, and carried out empirical estimates of experiment error based on knowledge of instrument characteristics. These analyses indicate an average single-profile CH4 systematic error of about 15% between 46 and 0.46 mbar, with CLAES biased high. The CH4 random error over this range is 0.08 to 0.05 parts per million, which translates to about 7% in the midstratosphere. For N2O the indicated systematic error is less than 15% at all altitudes between 68 and 2 mbar, with CLAES tending to be high below 6.8 mbar and low above. The N2O random error is 20 to 5 ppb between 46 and 2 mbar, which also translates to 7% in the low to midstratosphere. Both tracers have useful profile information to as low as 68 mbar, excluding the tropics, and as high as 0.2 mbar (CH4) and 1 mbar (N2O). The global fields show generally good spatial correlation and exhibit the major morphological and seasonal features seen in previous global field data. Several morphological features are painted out for regions and conditions for which there have been essentially no previous data. These include the differential behavior of the tracer isopleths near and inside the Antarctic winter vortex, and local maxima in the tropics in 1992, probably associated with the Mount Pinatubo sulfate aerosol layer. Overall, the results of this validation exercise indicate that the version 7 CH4 and N2O data sets can be used with good confidence for quantitative and qualitative studies of stratospheric and lower-mesospheric atmospheric structure and dynamics. C1 NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. UNIV DENVER, DEPT PHYS, DENVER, CO 80208 USA. SMITHSONIAN ASTROPHYS LAB, CAMBRIDGE, MA 02138 USA. UNIV PITTSBURGH, DEPT PHYS & ASTRON, PITTSBURGH, PA 15260 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP Roche, AE (reprint author), LOCKHEED MARTIN PALO ALTO RES LAB, DEPT 91-20, BLDG 252, 3251 HANOVER ST, PALO ALTO, CA 94304 USA. NR 35 TC 72 Z9 73 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9679 EP 9710 DI 10.1029/95JD03442 PG 32 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400008 ER PT J AU Nightingale, RW Roche, AE Kumer, JB Mergenthaler, JL Gille, JC Massie, ST Bailey, PL Edwards, DP Gunson, MR Toon, GC Sen, B Blavier, JF Connell, PS AF Nightingale, RW Roche, AE Kumer, JB Mergenthaler, JL Gille, JC Massie, ST Bailey, PL Edwards, DP Gunson, MR Toon, GC Sen, B Blavier, JF Connell, PS TI Global CF2Cl2 measurements by UARS cryogenic limb array etalon spectrometer: Validation by correlative data and a model SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MIDDLE ATMOSPHERE; ANTARCTIC VORTEX; NUMERICAL-MODEL; SOURCE GASES; OZONE; STRATOSPHERE; CHLORINE; N2O; TRANSPORT; CH4 AB The cryogenic limb array etalon spectrometer (CLAES) onboard the Upper Atmosphere Research Satellite (UARS) has obtained the first global measurements of CF2Cl2 over six seasons, for which 388 days have been processed in data version 7 for the period from January 9, 1992, to May 5, 1993. The CLAES measurements provide a near-global view of this stratospheric species, greatly extending the altitude, latitude, and seasonal coverage of previous measurements. This work evaluates CLAES version 7 data set quality. To arrive at estimates of experimental error, we compared the CLAES CF2Cl2 profiles with all of the available correlative data from balloon and space-borne sensors, and we looked at the repeatability of multiple profiles in the same location. In addition, we carried out empirical estimates of experimental error based on knowledge of instrument characteristics, and we performed consistency checks using the Lawrence Livermore National Laboratory two-dimensional (LLNL-2D) model and the CLAES N2O data set. Both the range of mean differences between CLAES and the available correlative data and the empirical estimates of the instrument systematic error indicate a CF2Cl2 profile systematic error of 14% over the range of 18.7 through 32 km and 22% for 33-35 km and 16-18 km. These systematic errors are applicable in the spring through fall seasons for the midlatitude region and all seasons in the tropical region. The CF2Cl2 estimated random errors, which are close to the observed data repeatability, are 32 to 11 pptv between 17 and 32 km and translate to an average 9% in the low to midstratosphere. The altitude range of best confidence for the CF2Cl2 mixing ratio profiles is 18.7 to 32 km (similar to 68 to 10 mbar), to which we assign an accuracy (root-sum-square of systematic and random errors) of similar to 17%. In the tropics the profiles from 16 to about 26 km may sometimes be biased low by up to 14% due to a data processing algorithm constraint. The CLAES CF2Cl2 global fields show generally good spatial correlation and exhibit the major morphological and seasonal features seen in other global tracer field data. Overall, the results of this validation exercise indicate that the CLAES version 7 CF2Cl2 data set, within the limitations discussed in the paper, can be used for quantitative and qualitative studies of stratospheric structure and dynamics. C1 NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. LAWRENCE LIVERMORE NATL LAB, LIVERMORE, CA 94550 USA. RP Nightingale, RW (reprint author), LOCKHEED MARTIN RES & DEV, DEPT 91-20, BLDG 252, 3251 HANOVER ST, PALO ALTO, CA 94304 USA. NR 53 TC 23 Z9 23 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9711 EP 9736 DI 10.1029/96JD00597-A PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400009 ER PT J AU Bailey, PL Edwards, DP Gille, JC Lyjak, LV Massie, ST Roche, AE Kumer, JB Mergenthaler, JL Connor, BJ Gunson, MR Margitan, JJ McDermid, IS McGee, TJ AF Bailey, PL Edwards, DP Gille, JC Lyjak, LV Massie, ST Roche, AE Kumer, JB Mergenthaler, JL Connor, BJ Gunson, MR Margitan, JJ McDermid, IS McGee, TJ TI Comparison of cryogenic limb array etalon spectrometer (CLAES) ozone observations with correlative measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RESEARCH SATELLITE UARS; STRATOSPHERIC OZONE; ABSOLUTE ABSORPTION; ATMOSPHERE; PERFORMANCE; TEMPERATURE; VALIDATION; RETRIEVAL; AEROSOL; CH4 AB Ozone measurements made by the Cryogenic Limb array Etalon Spectrometer (CLAES) aboard the NASA Upper Atmosphere Research Satellite (UARS) are compared to nearly coincident correlative measurements taken in 1992 and 1993 and to mean ozone distributions observed by other satellite instruments during past missions. This paper describes the CLAES measurement characteristics, uncertainties, predicted, and observed precisions and compares the observations with independent measurements both qualitatively and statistically. Satellite- and ground-based remote sensing as well as balloon-borne in situ measurements are represented in the correlative data set. The CLAES data are shown to be within +/- 20% of all correlative measurements between 0.5 and 30 mbar. Differences at lower altitudes may be related to effects of the Pinatubo aerosol on certain of the correlative measurements and the CLAES retrieval. Comparisons with historical data from the LIMS, SAGE II, and SBUV instruments indicate good agreement with the spatial and seasonal ozone distributions seen by CLAES. C1 LOCKHEED PALO ALTO RES LABS, PALO ALTO, CA 94304 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP Bailey, PL (reprint author), NATL CTR ATMOSPHER RES, POB 3000, BOULDER, CO 80307 USA. RI McGee, Thomas/G-4951-2013 NR 35 TC 21 Z9 21 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9737 EP 9756 DI 10.1029/95JD03614 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400010 ER PT J AU Massie, ST Gille, JC Edwards, DP Bailey, PL Lyjak, LV Craig, CA Cavanaugh, CP Mergenthaler, JL Roche, AE Kumer, JB Lambert, A Grainger, RG Rodgers, CD Taylor, FW Russell, JM Park, JH Deshler, T Hervig, ME Fishbein, EF Waters, JW Lahoz, WA AF Massie, ST Gille, JC Edwards, DP Bailey, PL Lyjak, LV Craig, CA Cavanaugh, CP Mergenthaler, JL Roche, AE Kumer, JB Lambert, A Grainger, RG Rodgers, CD Taylor, FW Russell, JM Park, JH Deshler, T Hervig, ME Fishbein, EF Waters, JW Lahoz, WA TI Validation studies using multiwavelength cryogenic limb array etalon spectrometer (CLAES) observations of stratospheric aerosol SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID INFRARED-ABSORPTION; PINATUBO AEROSOL; SULFURIC-ACID; TEMPERATURE; ISAMS; UARS AB Validation studies of multiwavelength Cryogenic Limb Array Etalon Spectrometer (CLAES) observations of stratospheric aerosol are discussed. An error analysis of the CLAES aerosol extinction data is presented. Aerosol extinction precision values are estimated at latitudes and times at which consecutive Upper Atmosphere Research Satellite (UARS) orbits overlap. Comparisons of CLAES aerosol data with theoretical Mie calculations, based upon in situ particle size measurements at Laramie, Wyoming, are presented. CLAES aerosol data are also compared to scaled aerosol extinction measured by the Stratospheric Aerosol and Gas Experiment (SAGE II) and Atmospheric Trace Molecule Spectroscopy (ATMOS) experiments. Observed and calculated extinction spectra, from CLAES, Improved Stratospheric and Mesospheric Sounder (ISAMS), and Halogen Occultation Experiment (HALOE) data, are compared. CLAES extinction data have precisions between 10 and 25%, instrumental biases near 30%, and accuracies between 33 and 43%. C1 UNIV WYOMING, LARAMIE, WY 82071 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. UNIV OXFORD, DEPT PHYS, CLARENDON LAB, OXFORD OX1 3PU, ENGLAND. LOCKHEED PALO ALTO RES LABS, PALO ALTO, CA 94304 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23666 USA. UNIV READING, READING, BERKS, ENGLAND. RP Massie, ST (reprint author), NATL CTR ATMOSPHER RES, POB 3000, BOULDER, CO 80307 USA. RI Grainger, Roy/E-8823-2011 OI Grainger, Roy/0000-0003-0709-1315 NR 25 TC 28 Z9 29 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9757 EP 9773 DI 10.1029/95JD03225 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400011 ER PT J AU Connor, BJ Scheuer, CJ Chu, DA Remedios, JJ Grainger, RG Rodgers, CD Taylor, FW AF Connor, BJ Scheuer, CJ Chu, DA Remedios, JJ Grainger, RG Rodgers, CD Taylor, FW TI Ozone in the middle atmosphere as measured by the improved stratospheric and mesospheric sounder SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB The improved stratospheric and mesospheric sounder (ISAMS) made ozone measurements in the stratosphere and mesosphere, with dense coverage over a broad range of latitudes, on about 180 days between September 1991 and July 1992. In this paper we are concerned with version 10 of the ISAMS data, which is recommended for use in the pressure range 10-0.1 mbar at night and 10-1 mbar during daytime. We describe the measurements and the retrieval algorithm, present an error analysis, and provide comparisons of the results to both climatological and coincident data. It is demonstrated that biases with respect to other well-validated data sets are less than 10%, which is well within the internal assessment of systemetic errors. C1 UNIV OXFORD, OXFORD, ENGLAND. SCI & TECHNOL CORP, HAMPTON, VA 23665 USA. NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. GATS INC, HAMPTON, VA 23665 USA. RI Grainger, Roy/E-8823-2011 OI Grainger, Roy/0000-0003-0709-1315 NR 18 TC 5 Z9 5 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9831 EP 9841 DI 10.1029/95JD01714 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400015 ER PT J AU Remedios, JJ Ruth, SL Rodgers, CD Taylor, FW Roche, AE Gille, JC Gunson, MR Russell, JM Park, J Zipf, EC Erdman, PW AF Remedios, JJ Ruth, SL Rodgers, CD Taylor, FW Roche, AE Gille, JC Gunson, MR Russell, JM Park, J Zipf, EC Erdman, PW TI Measurements of methane and nitrous oxide distributions by the improved stratospheric and mesospheric sounder: Retrieval and validation SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TRACER DISTRIBUTIONS; NIMBUS-7; SAMS; UARS; CH4; N2O; ATMOSPHERE; DATABASE; AEROSOL; MODEL AB The improved stratospheric and mesospheric sounder (ISAMS) used the pressure modulation technique to observe infrared emissions from the atmosphere at 7.4 mu m and 7.8 mu m. The target gases, methane and nitrous oxide, both emit at these wavelengths and so their concentrations have been determined by joint retrieval from the available signals. This paper describes the measurement technique, the current retrieval scheme (version 10), and the data set produced. The version 10 data set comprises typically 2600 profiles per day on 180 days between September 26, 1991, and July 29, 1992. Retrieved profiles extend in altitude from 7 mbar to 0.08 mbar for methane and from 7 mbar to 0.8 mbar for nitrous oxide. The precision of the data is better than 20% over much of the range and estimated systematic uncertainties are less than 30%. Comparisons with coincident measurements show that the systematic uncertainties are a reasonable estimate for the methane data but reveal a much larger positive bias for the nitrous oxide data relative to other measurements. Accounting for aerosol contamination effects and a priori biases, ISAMS methane data are recommended for use in scientific studies at altitudes between 7 mbar (5 mbar in the tropics) and 0.1 mbar. ISAMS nitrous oxide data are recommended for use between 7 mbar and 1.0 mbar where relative rather than absolute values are required. C1 RUTHERFORD APPLETON LAB, CHILTON, ENGLAND. NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. CALTECH, JET PROP LAB, PASADENA, CA 91125 USA. NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. UNIV PITTSBURGH, DEPT PHYS & ASTRON, PITTSBURGH, PA 15260 USA. LOCKHEED PALO ALTO RES CTR, PALO ALTO, CA USA. RP Remedios, JJ (reprint author), UNIV OXFORD, DEPT PHYS, CLARENDON LAB, PARKS RD, OXFORD OX1 3PU, ENGLAND. NR 39 TC 17 Z9 17 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9843 EP 9871 DI 10.1029/95JD02840 PG 29 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400016 ER PT J AU Smith, SE Dudhia, A Morris, PE Remedios, JJ Rodgers, CD Taylor, FW Kerridge, BJ Chipperfield, MP Kumer, JB Roche, AE Gunson, MR AF Smith, SE Dudhia, A Morris, PE Remedios, JJ Rodgers, CD Taylor, FW Kerridge, BJ Chipperfield, MP Kumer, JB Roche, AE Gunson, MR TI Dinitrogen pentoxide measurements from the improved stratospheric and mesospheric sounder: Validation of preliminary results SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID EMISSION MEASUREMENTS; INFRARED-ABSORPTION; N2O5; RETRIEVAL; PROFILES; LATITUDE; SPECTRA; ISAMS AB The improved stratospheric and mesospheric sounder (ISAMS) on the Upper Atmosphere Research Satellite (UARS) made some of the first global measurements of dinitrogen pentoxide (N2O5) in the 1991/1992 period. N2O5 is a crucial part of the ozone photochemical cycle in the stratosphere, but measurements of its variability and distribution are difficult and hitherto have been rare, inhibiting adequate testing of dynamical-chemical models of the stratosphere. This paper describes the production and validation of the first set of ISAMS global N2O5 data to be made publically available (version 10). It is concluded that the results represent a considerable improvement over those previously available and are ready for use in certain kinds of scientific work. There still exist problems regarding the treatment of stratospheric sulfate aerosol which further processing will hopefully resolve. C1 UNIV CAMBRIDGE, CTR ATMOSPHER CHEM, DEPT CHEM, CAMBRIDGE CB2 1EW, ENGLAND. RUTHERFORD APPLETON LAB, DIDCOT OX11 0QX, OXON, ENGLAND. LOCKHEED PALO ALTO RES LABS, PALO ALTO, CA 94304 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP Smith, SE (reprint author), UNIV OXFORD, DEPT PHYS, CLARENDON LAB, PARKS RD, OXFORD OX1 3DW, ENGLAND. RI Chipperfield, Martyn/H-6359-2013 OI Chipperfield, Martyn/0000-0002-6803-4149 NR 28 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9897 EP 9906 DI 10.1029/95JD02465 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400018 ER PT J AU GossCustard, M Remedios, JJ Lambert, A Taylor, FW Rodgers, CD LopezPuertas, M Zaragoza, G Gunson, MR Suttie, MR Harries, JE Russell, JM AF GossCustard, M Remedios, JJ Lambert, A Taylor, FW Rodgers, CD LopezPuertas, M Zaragoza, G Gunson, MR Suttie, MR Harries, JE Russell, JM TI Measurements of water vapor distributions by the improved stratospheric and mesospheric sounder: Retrieval and validation SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LIMB INFRARED MONITOR; ATMOSPHERE; UARS; SPECTROSCOPY; CO AB The Improved Stratospheric and Mesospheric Sounder (ISAMS) measured emissions from the 6.3-mu m band of water vapor using the pressure modulation technique, The particular form of the technique employed by ISAMS produces two signals: a pressure-modulated signal and a wideband signal. Water vapor retrievals from the wideband signal are presented here since data from the former are still under investigation, The data are also restricted to nighttime because of the significant nonthermal emission processes which govern the daytime water vapor emissions at this wavelength, In this paper the retrieval method for the wideband water vapor retrievals is discussed in detail and an internal error budget is derived based on results for version 9 of the ISAMS data set. Comparisons are also made with available coincident measurements during the ISAMS period of observations from September 1991 to July 1992, including data from other instruments on the Upper Atmosphere Research Satellite. C1 CALTECH, JET PROP LAB, PASADENA, CA 91125 USA. UNIV EDINBURGH, EDINBURGH, MIDLOTHIAN, SCOTLAND. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED, LONDON, ENGLAND. NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. CSIC, INST ASTROFIS ANDALUCIA, GRANADA, SPAIN. RP GossCustard, M (reprint author), UNIV OXFORD, DEPT PHYS, CLARENDON LAB, PARKS RD, OXFORD OX1 3PU, ENGLAND. RI Zaragoza, Guillermo/D-8412-2011; Lopez Puertas, Manuel/M-8219-2013; OI Lopez Puertas, Manuel/0000-0003-2941-7734; Zaragoza, Guillermo/0000-0002-4452-9980 NR 45 TC 13 Z9 13 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9907 EP 9928 DI 10.1029/95JD02032 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400019 ER PT J AU Jarnot, RF Cofield, RE Waters, JW Flower, DA Peckham, GE AF Jarnot, RF Cofield, RE Waters, JW Flower, DA Peckham, GE TI Calibration of the microwave limb sounder on the Upper Atmosphere Research Satellite SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB The Microwave Limb Sounder (MLS) is a three-radiometer, passive, limb emission instrument onboard the Upper Atmosphere Research Satellite (UARS). Radiometric, spectral and field-of-view calibrations of the MLS instrument are described in this paper. In-orbit noise performance, gain stability, spectral baseline and dynamic range are described, as well as use of in-flight data for validation and refinement of prelaunch calibrations. Estimated systematic scaling uncertainties (3 sigma) on calibrated limb radiances from prelaunch calibrations are 2.6% in bands 1 through 3, 3.4% in band 4, and 6% in band 5. The observed systematic errors in band 6 are similar to 15%, consistent with prelaunch calibration uncertainties. Random uncertainties on individual limb radiance measurements are very close to the levels predicted from measured radiometer noise temperature, with negligible contribution from noise and drifts on the regular in-flight gain calibration measurements. C1 HERIOT WATT UNIV, DEPT PHYS, EDINBURGH EH14 4AS, MIDLOTHIAN, SCOTLAND. RP Jarnot, RF (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, MS 183-701, PASADENA, CA 91109 USA. NR 18 TC 20 Z9 21 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9957 EP 9982 DI 10.1029/95JD03792 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400021 ER PT J AU Fishbein, EF Cofield, RE Froidevaux, L Jarnot, RF Lungu, T Read, WG Shippony, Z Waters, JW McDermid, IS McGee, TJ Singh, U Gross, M Hauchecorne, A Keckhut, P Gelman, ME Nagatani, RM AF Fishbein, EF Cofield, RE Froidevaux, L Jarnot, RF Lungu, T Read, WG Shippony, Z Waters, JW McDermid, IS McGee, TJ Singh, U Gross, M Hauchecorne, A Keckhut, P Gelman, ME Nagatani, RM TI Validation of UARS microwave limb sounder temperature and pressure measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERIC-TEMPERATURE; MIDDLE ATMOSPHERE; LIDAR; MESOSPHERE; OXYGEN; WAVES; STRATOSPHERE; PROFILES; GRAVITY AB The accuracy and precision of the Upper Atmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS) atmospheric temperature and tangent-point pressure measurements are described, Temperatures and tangent-point pressure (atmospheric pressure at the tangent height of the held of view boresight) are retrieved from a 15-channel 63-GHz radiometer measuring O-2 microwave emissions from the stratosphere and mesosphere, The Version 3 data (first public release) contains scientifically useful temperatures from 22 to 0.46 hPa, Accuracy estimates are based on instrument performance, spectroscopic uncertainty and retrieval numerics, and range from 2.1 K at 22 hPa to 4.8 K at 0.46 hPa for temperature and from 200 m (equivalent log pressure) at 10 hPa to 300 m at 0.1 hPa. Temperature accuracy is limited mainly by uncertainty in instrument characterization, and tangent-point pressure accuracy is limited mainly by the accuracy of spectroscopic parameters. Precisions are around 1 K and 100 m, Comparisons are presented among temperatures from MLS, the National Meteorological Center (NMC) stratospheric analysis and lidar stations at Table Mountain, California, Observatory of Haute Provence (OHP), France, and Goddard Spaceflight Center, Maryland. MLS temperatures tend to be 1-2 K lower than NMC and lidar, but MLS is often 5 - 10 K lower than NMC in the winter at high latitudes, especially within the northern hemisphere vortex. Winter MLS and OHP (44 degrees N) lidar temperatures generally agree and tend to be lower than NMC. Problems with Version 3 MLS temperatures and tangent-point pressures are identified, but the high precision of MLS radiances will allow improvements with better algorithms planned for the future. C1 HUGHES STX CORP, LANHAM, MD USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. CNRS, SERV AERON, F-91371 VERRIERES LE BUISSON, FRANCE. NOAA, NATL WEATHER SERV, NATL CTR ENVIRONM PROTECT, CLIMATE PREDICT CTR, CAMP SPRINGS, MD USA. RP Fishbein, EF (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Hauchecorne, Alain/A-8489-2013; McGee, Thomas/G-4951-2013 NR 39 TC 43 Z9 43 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 9983 EP 10016 DI 10.1029/95JD03791 PG 34 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400022 ER PT J AU Froidevaux, L Read, WG Lungu, TA Cofield, RE Fishbein, EF Flower, DA Jarnot, RF Ridenoure, BP Shippony, Z Waters, JW Margitan, JJ McDermid, IS Stachnik, RA Peckham, GE Braathen, G Deshler, T Fishman, J Hofmann, DJ Oltmans, SJ AF Froidevaux, L Read, WG Lungu, TA Cofield, RE Fishbein, EF Flower, DA Jarnot, RF Ridenoure, BP Shippony, Z Waters, JW Margitan, JJ McDermid, IS Stachnik, RA Peckham, GE Braathen, G Deshler, T Fishman, J Hofmann, DJ Oltmans, SJ TI Validation of UARS microwave limb sounder ozone measurement SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC CLO; RETRIEVAL; OXYGEN; WINTER; MLS; O3 AB This paper describes the validation of ozone data from the Upper Atmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS). The MLS ozone retrievals are obtained from the calibrated microwave radiances (emission spectra) in two separate bands, at frequencies near 205 and 183 GHz. Analyses described here focus on the MLS Version 3 data (the first set of files made publicly available). We describe results of simulations performed to assess the quality of the retrieval algorithms, in terms of both mixing ratio and radiance closure. From actual MLS observations, the 205-GHz ozone retrievals give better closure (smaller radiance residuals) than that from the 183-GHz measurements and should be considered more accurate from the calibration aspects. However, the 183-GHz data are less noise limited in the mesosphere and can provide the most useful scientific results in that region. We compare the retrieved 205-GHz ozone profiles in the middle-to lower stratosphere to ozonesonde measurements at a wide range of latitudes and seasons. Ground-based lidar data from Table Mountain, California, provide a good reference for comparisons at higher altitudes. Based on these analyses, comparisons with balloon-borne measurements and others, as well as a detailed budget of estimated uncertainties, MLS results appear to be generally of high quality, with some biases worth mentioning. Results for the lowermost stratosphere (similar to 50 to 100 hPa) are still in need of improvement. A set of estimated precision and accuracy values is derived for the MLS ozone data sets. We also comment on recent updates in the retrieval algorithms and their impact on ozone values. C1 NORSK INST LUFTFORSKNINH, OSLO, NORWAY. UNIV WYOMING, DEPT ATMOSPHER SCI, LARAMIE, WY 82071 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. NOAA, CLIMATE MONITORING & DIAGNOST LAB, BOULDER, CO 80303 USA. HERIOT WATT UNIV, EDINBURGH EH14 4AS, MIDLOTHIAN, SCOTLAND. RP Froidevaux, L (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, MS 183-701, PASADENA, CA 91109 USA. NR 32 TC 106 Z9 106 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10017 EP 10060 DI 10.1029/95JD02325 PG 44 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400023 ER PT J AU Cunnold, DM Wang, H Chu, WP Froidevaux, L AF Cunnold, DM Wang, H Chu, WP Froidevaux, L TI Comparisons between stratospheric aerosol and gas experiment II and microwave limb sounder ozone measurements and aliasing of SAGE II ozone trends in the lower stratosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PINATUBO AB SAGE II ozone measurements are compared with coincident microwave limb sounder (MLS) measurements over the period September 1991 to December 1993. Between 1.5 and 10 mbar the MLS ozone values are approximately 5% larger than the Stratospheric Aerosol and Gas Experiment (SAGE) II values. These differences are remarkably systematic in space and time. At 1 mbar the mean differences are zero and the mean differences oscillate with level at lower pressures. A month of comparisons against Halogen Occultation Experiment ozone measurements suggests that the differences at pressures less than 1.5 mbar are a feature of the MLS measurements. There are also differences between SAGE II sunrise and sunset measurements at 1 mbar which may be associated with the diurnal tide. At pressures greater than 10 mbar the comparisons indicate that the SAGE II ozone retrievals are being biased by the large aerosol concentrations resulting from the Mount Pinatubo eruption. For a fixed aerosol extinction the SAGE II/MLS difference (ppm) is larger at higher altitudes. It also depends nonlinearly on the aerosol extinction at pressures greater than 20 mbar. These effects are probably caused by the interpolation of the SAGE II aerosol extinction to 0.6 mu m and by the evolution of the aerosol size distribution. For UARS layer aerosol optical depths less than 2 x 10(-3) at 1.02 mu m, the aerosol effect on the SAGE II ozone retrievals is inferred to be 3 x 10(10) cm(-3)/10(-3) aerosol layer optical depth at pressures greater than 20 mbar. This is equivalent to approximately 3% of the aerosol extinction at 0.6 mu m being interpreted as ozone. At low aerosol concentrations and between 10 and 31 mbar, MLS ozone values are found to be approximately 5% larger than SAGE II ozone values (in agreement with the higher-altitude differences). Atmospheric aerosol concentrations prior to the Mount Pinatubo eruption were large enough, particularly in the tropics after Ruiz in 1985, that long-term trends in SAGE II ozone in the lower stratosphere are inferred to be biased downward. As a result, the SAGE II column ozone trends in the tropics over the period 1984-1991 need to be increased by approximately 0.2%/yr. This effect can account for a large fraction of SAGE II total ozone mapping spectrometer (TOMS) column ozone trend differences over this period. Good agreement is found between the TOMS and the SAGE II column ozone trends if the period of comparison is restricted to times of low aerosol concentrations. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NR 17 TC 41 Z9 41 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10061 EP 10075 DI 10.1029/95JD01707 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400024 ER PT J AU Ricaud, P deLaNoe, J Connor, BJ Froidevaux, L Waters, JW Harwood, RS MacKenzie, IA Peckham, GE AF Ricaud, P deLaNoe, J Connor, BJ Froidevaux, L Waters, JW Harwood, RS MacKenzie, IA Peckham, GE TI Diurnal variability of mesospheric ozone as measured by the UARS microwave limb sounder instrument: Theoretical and ground-based validations SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERE; LATITUDE AB Diurnal variability of mesospheric ozone as measured by the 183-GHz radiometer of the UARS microwave limb sounder (MLS) instrument for the northern midlatitudes in October 1991 and 1992 is compared with theoretical calculations of diurnal amplitudes produced by two photochemical models and with ground-based microwave measurements made from Bordeaux (France, 45 degrees N) in October 1988, 1989, and 1990 and the Table Mountain Facility (California, 35 degrees N) in October 1990, Great care has been taken in comparing all the data sets within the same frame, i.e., interpolating onto the same vertical grid (pressure or altitude), using the same units (concentration or mixing ratio) and degrading the vertical resolution of some data or models (convolution of the vertical profiles with appropriate averaging kernels). MLS diurnal variability generally agrees to within 10% with ground-based and model results at 0.5, 0.2, 0.1, and 0.05 hPa (approximately 55, 60, 65, and 70 km, respectively). Although modeled diurnal changes at 55 +/- 8 km are closer to the ground-based Bordeaux measurements than to the MLS data at 45 degrees N, MLS results are closer to ground-based Table Mountain Facility data at 35 degrees N at 0.42 and 0.22 hPa (similar to 55 +/- 8 and similar to 60 +/- 8 km, respectively)than to models. At 0.1 and 0.042 hPa, MLS diurnal changes are weaker than ground-based and model variations, but daytime O-3 mixing ratios are found to be in very good agreement for all data sets. C1 NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. UNIV EDINBURGH, DEPT METEOROL, EDINBURGH EH9 3JZ, MIDLOTHIAN, SCOTLAND. HERIOT WATT UNIV, DEPT PHYS, EDINBURGH EH14 4AS, MIDLOTHIAN, SCOTLAND. RP Ricaud, P (reprint author), OBSERV BORDEAUX, CNRS, INSU, BP 89, F-33270 FLOIRAC, FRANCE. RI mackenzie, ian/E-9320-2013 NR 20 TC 41 Z9 43 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10077 EP 10089 DI 10.1029/95JD02841 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400025 ER PT J AU Waters, JW Read, WG Froidevaux, L Lungu, TA Perun, VS Stachnik, RA Jarnot, RF Cofield, RE Fishbein, EF Flower, DA Burke, JR Hardy, JC Nakamura, LL Ridenoure, BP Shippony, Z Thurstans, RP Avallone, LM Toohey, DW deZafra, RL Shindell, DT AF Waters, JW Read, WG Froidevaux, L Lungu, TA Perun, VS Stachnik, RA Jarnot, RF Cofield, RE Fishbein, EF Flower, DA Burke, JR Hardy, JC Nakamura, LL Ridenoure, BP Shippony, Z Thurstans, RP Avallone, LM Toohey, DW deZafra, RL Shindell, DT TI Validation of UARS microwave limb sounder ClO measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID IN-SITU MEASUREMENTS; ANTARCTIC SPRING STRATOSPHERE; ATMOSPHERE RESEARCH SATELLITE; CHLORINE MONOXIDE; INSITU OBSERVATIONS; HYDROGEN-PEROXIDE; REACTIVE CHLORINE; DIURNAL-VARIATION; SULFATE AEROSOLS; OZONE DEPLETION AB Validation of stratospheric ClO measurements by the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite (UARS) is described. Credibility of the measurements is established by (1) the consistency of the measured ClO spectral emission line with the retrieved ClO profiles and (2) comparisons of ClO from MLS with that from correlative measurements by balloon-based, ground-based, and aircraft-based instruments. Values of ''noise'' (random), ''scaling'' (multiplicative), and ''bias'' (additive) uncertainties are determined for the Version 3 data, the first version publicly released, and known artifacts in these data are identified. Comparisons with correlative measurements indicate agreement to within the combined uncertainties expected for MLS and the other measurements being compared. It is concluded that MLS Version 3 ClO data, with proper consideration of the uncertainties and ''quality'' parameters produced with these data, can be used for scientific analyses at retrieval surfaces between 46 and 1 hPa (approximately 20-50 km in height). Future work is planned to correct known problems in the data and improve their quality. C1 UNIV CALIF IRVINE, DEPT EARTH SYST SCI, IRVINE, CA 92717 USA. SUNY STONY BROOK, DEPT PHYS, STONY BROOK, NY 11794 USA. RP Waters, JW (reprint author), CALTECH, JET PROP LAB, MAIL STOP 183701, PASADENA, CA 91109 USA. RI Toohey, Darin/A-4267-2008; Shindell, Drew/D-4636-2012 OI Toohey, Darin/0000-0003-2853-1068; NR 97 TC 49 Z9 49 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10091 EP 10127 DI 10.1029/95JD03351 PG 37 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400026 ER PT J AU Lahoz, WA Suttie, MR Froidevaux, L Harwood, RS Lau, CL Lungu, TA Peckham, GE Pumphrey, HC Read, WG Shippony, Z Suttie, RA Waters, JW Nedoluha, GE Oltmans, SJ Russell, JM Traub, WA AF Lahoz, WA Suttie, MR Froidevaux, L Harwood, RS Lau, CL Lungu, TA Peckham, GE Pumphrey, HC Read, WG Shippony, Z Suttie, RA Waters, JW Nedoluha, GE Oltmans, SJ Russell, JM Traub, WA TI Validation of UARS microwave limb sounder 183 GHz H2O measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MESOSPHERIC WATER-VAPOR; TEMPERATURE; VARIABILITY; ATMOSPHERE; RETRIEVAL; MIDDLE AB The Upper Atmosphere Research Satellite (UARS) microwave limb sounder (MLS) makes measurements of thermal emission at 183.3 GHz which are used to infer the concentration of water vapor over a pressure range of 46 - 0.2 hPa (similar to 20 to similar to 60 km). We provide a validation of MLS H2O by analyzing the integrity of the measurements, by providing an error characterization, and by comparison with data from other instruments. It is estimated that version 3 MLS H2O retrievals are accurate to within 20-25 % in the lower stratosphere and to within 8-13 % in the upper stratosphere and lower mesosphere, The precision of a single profile is estimated to be similar to 0.15 parts per million by volume (ppmv) in the midstratosphere and 0.2 ppmv in the lower and upper stratosphere, In the lower mesosphere the estimate of a single profile precision is 0.25-0.45 ppmv. During polar winter conditions, H2O retrievals at 46 hPa can have a substantial contribution from climatology. The vertical resolution of MLS H2O retrievals is similar to 5 km. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. UNIV READING, DEPT METEOROL, CGAM, READING RG6 2AU, BERKS, ENGLAND. HERIOT WATT UNIV, DEPT PHYS, EDINBURGH EH14 4AS, MIDLOTHIAN, SCOTLAND. USN, RES LAB, WASHINGTON, DC 20375 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. NOAA, CLIMATE MONITORING & DIAGNOST LAB, BOULDER, CO 80303 USA. HARVARD SMITHSONIAN CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. RP Lahoz, WA (reprint author), UNIV EDINBURGH, DEPT METEOROL, EDINBURGH EH9 3JZ, MIDLOTHIAN, SCOTLAND. NR 28 TC 36 Z9 36 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10129 EP 10149 DI 10.1029/95JD01703 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400027 ER PT J AU Russell, JM Deaver, LE Luo, MZ Park, JH Gordley, LL Tuck, AF Toon, GC Gunson, MR Traub, WA Johnson, DG Jucks, KW Murcray, DG Zander, R Nolt, IG Webster, CR AF Russell, JM Deaver, LE Luo, MZ Park, JH Gordley, LL Tuck, AF Toon, GC Gunson, MR Traub, WA Johnson, DG Jucks, KW Murcray, DG Zander, R Nolt, IG Webster, CR TI Validation of hydrogen chloride measurements made by the halogen occultation experiment from the UARS platform SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SPECTROSCOPIC MEASUREMENTS; TRACE GASES; HCL; HF; STRATOSPHERE; OZONE; ATMOSPHERE; ANTARCTICA; PINATUBO; O3 AB The Halogen Occultation Experiment (HALOE) on UARS uses the method of solar occultation limb sounding to measure the composition and structure of the stratosphere and mesosphere. One of the HALOE channels is spectrally centered at 3.4 mu m to measure the vertical profile and global distribution of hydrogen chloride. The mean difference between HALOE and 14 balloon correlative underflight measurements ranges from 8% to 19% throughout most of the stratosphere. This difference is within the limits of error bar overlap for the two data sets. The mean differences between HALOE and HCl data from ATMOS flights on the space shuttle is of the order of 15 to 20% for the 1992 flight and 10% for the 1993 flight. Generally, HALOE results tend to be low in these comparisons. Also, comparisons with two-dimensional model calculations and HALOE data are in good qualitative agreement regarding vertical profile shapes and features in a pressure versus latitude cross section. HCl values increase from similar to 0.3 parts per billion by volume (ppbv) to 1 ppbv in the lower stratosphere to 2.6 ppbv to 3.3 ppbv just above the stratopause which is the upper limit of HALOE single-profile measurements. There is a dependence of HCl results on the angle between the orbit plane and the Earth-Sun vector with HCl varying by +/-9% in the upper stratosphere. This variation appears to be altitude dependent and it is not discernible in the data below about 10 mbar. C1 UNIV CALIF IRVINE, DEPT EARTH SYST SCI, IRVINE, CA 92717 USA. G&A TECH SOFTWARE, HAMPTON, VA USA. NOAA, AERON LAB, BOULDER, CO 80303 USA. CALTECH, JET PROP LAB, PASADENA, CA USA. HARVARD SMITHSONIAN CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. UNIV DENVER, DENVER, CO 80210 USA. UNIV LIEGE, LIEGE, BELGIUM. NASA, LANGLEY RES CTR, AEROSP ELECT SYST DIV, HAMPTON, VA 23681 USA. RP Russell, JM (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. RI Tuck, Adrian/F-6024-2011 OI Tuck, Adrian/0000-0002-2074-0538 NR 40 TC 61 Z9 61 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10151 EP 10162 DI 10.1029/95JD01696 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400028 ER PT J AU Russell, JM Deaver, LE Luo, MZ Cicerone, RJ Park, JH Gordley, LL Toon, GC Gunson, MR Traub, WA Johnson, DG Jucks, KW Zander, R Nolt, IG AF Russell, JM Deaver, LE Luo, MZ Cicerone, RJ Park, JH Gordley, LL Toon, GC Gunson, MR Traub, WA Johnson, DG Jucks, KW Zander, R Nolt, IG TI Validation of hydrogen fluoride measurements made by the halogen occultation experiment from the UARS platform SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC CONSTITUENTS; TRACE GASES; SPECTROSCOPY; HCL; HF; ANTARCTICA; CHLORIDE AB The hydrogen fluoride (HF) molecule is important as a tracer and for study of chlorine input to the stratosphere due to CFC's. This paper describes the characteristics of and data from the Halogen Occultation Experiment (HALOE) HF channel, including steps taken to validate the results. The on-orbit precision of the HF measurements is shown to be better than 0.04 parts per billion by volume (ppbv) to 0.06 ppbv throughout the stratosphere. The estimated accuracy is 14% to 27% depending on altitude, The internal consistency of the HF measurements is excellent as judged by sunrise/sunset differences and comparison with HALOE CH4 distributions. The mean difference between HALOE HF and correlative balloon underflight measurements is <7% from 5 mbar to 50 mbar. Comparisons with the shuttle ATLAS 1 Atmospheric Trace Molecules Observed by Spectroscopy (ATMOS) data are not as good and there is a systematic difference between HALOE (smaller) and ATMOS (larger) ranging from 10% to 20% at altitudes above the 10-mbar pressure level, Differences with ATMOS reach as much as 40% or more below the 10-mbar level. The larger differences in this region are believed to be due to dynamical influences on HF coupled with wide separations in space and time between HALOE and ATMOS measurements. Analysis of HALOE HF pressure versus longitude cross sections shows that obtaining close space and time coincidence can be very important in comparing tracer distributions. Typical characteristics of a pressure versus latitude cross section and polar orthographic projection are also discussed. Comparisons with latitudinal distributions of tracer measurements from previous experiments show similar features like the tropical double minimum due to the semiannual oscillation. All comparisons and analyses conducted provide good confidence in the validity of the HALOE HF results. C1 UNIV CALIF IRVINE, DEPT EARTH SYST SCI, IRVINE, CA 92717 USA. G&A TECH SOFTWARE, HAMPTON, VA 23666 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. HARVARD SMITHSONIAN CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. UNIV LIEGE, LIEGE, BELGIUM. NASA, LANGLEY RES CTR, AEROSP ELECT SYST DIV, HAMPTON, VA 23861 USA. RP Russell, JM (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23861 USA. NR 31 TC 32 Z9 32 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10163 EP 10174 DI 10.1029/95JD01705 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400029 ER PT J AU Liu, X Murcray, FJ Murcray, DG Russell, JM AF Liu, X Murcray, FJ Murcray, DG Russell, JM TI Comparison of HF and HCl vertical profiles from groundbased high-resolution infrared solar spectra with halogen occultation experiment observations SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LASER HETERODYNE SPECTROMETER; OZONE AB HCl and HF vertical mixing ratio (VMR) profiles have been retrieved from very high resolution, ground-based infrared solar absorption spectra taken from Denver, Colorado. The VMR profile retrieval is based on an iterative inversion algorithm, which incorporates a line-by-line layer-by-layer calculation for the forward model. The method has been successfully applied to both simulated and measured solar spectra. The HCl and HF profiles retrieved from the ground-based solar spectra are compared with the profiles measured by the UARS Halogen Occultation Experiment (HALOE) instrument for the same day near 40 degrees N latitude. The ground-based HF profile agrees very well with the HALOE results. The HCl profiles agree with HALOE within the combined of error limits but are higher by 5 to 20%. C1 NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23861 USA. RP Liu, X (reprint author), UNIV DENVER, DEPT PHYS, 2112 E WESLEY AVE, DENVER, CO 80208 USA. NR 15 TC 13 Z9 13 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10175 EP 10181 DI 10.1029/95JD01701 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400030 ER PT J AU Park, JH Russell, JM Gordley, LL Drayson, SR Benner, DC McInerney, JM Gunson, MR Toon, GC Sen, B Blavier, JF Webster, CR Zipf, EC Erdman, P Schmidt, U Schiller, C AF Park, JH Russell, JM Gordley, LL Drayson, SR Benner, DC McInerney, JM Gunson, MR Toon, GC Sen, B Blavier, JF Webster, CR Zipf, EC Erdman, P Schmidt, U Schiller, C TI Validation of halogen occultation experiment CH4 measurements from the UARS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NIMBUS-7 SAMS; ATMOSPHERE; AEROSOL; N2O AB Global distributions of CH4 in the mesosphere and stratosphere have been measured continuously since October 11, 1991, by the Halogen Occultation Experiment (HALOE) onboard the UARS. CH4 mixing ratio is obtained using the gas filter correlation technique operating in the 3.3-mu m region. Since measurements are made during solar occultation in the 57 degrees inclination orbit, data are collected 15 times daily for both sunrises and sunsets. This provides coverage of one hemisphere in a month period. One complete hemispheric sweep (from equator to similar to 80 degrees is made during the spring and summer seasons of two hemispheres, and a partial sweep (from equator to around 50 degrees latitude) is made during the fall and winter seasons of two hemispheres. HALOE CH4 measurements are validated using direct comparisons with correlative data and internal consistency checks using other HALOE-measured tracers, HF, and aerosols. It is estimated for the 0.3- to 50-mbar region that the total error, including systematic and random components, is less than 15% and that the precision is better than 7%. The CH4 gas filter channel does not depend significantly on the Pinatubo aerosol extinction. An experimentally accurate measurement of CH4 is very important because CH4 is a primary interfering gas in the HALOE HCl channel and, subsequently, can cause HCl measurement error. Simultaneous measurements of CH4 and other HALOE species (O-3, H2O, NO, NO2, HCl, HF, and aerosol extinction coefficients) provide important information on atmospheric dynamic and chemical processes, since CH4 can be used as a tracer and an indicator of atmospheric transport processes. Several new pieces of information on previously unreported HALOE-observed features are also presented. C1 COLL WILLIAM & MARY, DEPT PHYS, WILLIAMSBURG, VA 23185 USA. CALTECH, JET PROP LAB, PASADENA, CA 91125 USA. UNIV MICHIGAN, ANN ARBOR, MI 48109 USA. UNIV PITTSBURGH, DEPT PHYS & ASTRON, PITTSBURGH, PA 15260 USA. G&A TECH SOFTWARE, HAMPTON, VA 23666 USA. SCI APPLICAT INT CORP, HAMPTON, VA 23666 USA. INST STRATOSPHAR CHEM, JULICH, GERMANY. RP Park, JH (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, MAIL STOP 401A, HAMPTON, VA 23861 USA. RI Schiller, Cornelius/B-1004-2013 NR 22 TC 85 Z9 87 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10183 EP 10203 DI 10.1029/95JD02736 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400031 ER PT J AU Harries, JE Russell, JM Tuck, AF Gordley, LL Purcell, P Stone, K Bevilacqua, RM Gunson, M Nedoluha, G Traub, WA AF Harries, JE Russell, JM Tuck, AF Gordley, LL Purcell, P Stone, K Bevilacqua, RM Gunson, M Nedoluha, G Traub, WA TI Validation of measurements of water vapor from the halogen occultation experiment (HALOE) SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MIDDLE ATMOSPHERE; STRATOSPHERE; AEROSOL AB The Halogen Occultation Experiment (HALOE) experiment is a solar occultation limb sounder which operates between 2.45 and 10.0 mu m to measure the composition of the mesosphere, stratosphere, and upper troposphere. It flies onboard the Upper Atmosphere Research Satellite (UARS) which was launched in September 1991. Measurements are made of the transmittance of the atmosphere in a number of spectral channels as the Sun rises or sets behind the limb of the atmosphere. One of the channels, at 6.60 mu m, is a broadband filter channel tuned to detect absorption in the nu(2) band of water vapor. This paper describes efforts to validate the absolute and relative uncertainties (accuracy and precision) of the measurements from this channel. The HALOE data have been compared with independent measurements, using a variety of observational techniques, from balloons, from the ground, and from other space missions, and with the results of a two-dimensional model. The results show that HALOE is providing global measurements throughout the stratosphere and mesosphere with an accuracy within +/-10% over most of this height range, and to within +/-30% at the boundaries, and to a precision in the lower stratosphere of a few percent. The H2O data are combined with HALOE measurements of CH4 in order to test the data in terms of conservation of total hydrogen, with most encouraging results. The observed systematic behavior and internal consistency of the HALOE data, coupled with these estimates of their accuracy, indicate that the data may be used for quantitative tests of our understanding of the physical and chemical processes which control the concentration of H2O in the middle atmosphere. C1 USN, RES LAB, WASHINGTON, DC 20375 USA. G&A TECH SOFTWARE, HAMPTON, VA 23666 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23861 USA. SMITHSONIAN ASTROPHYS OBSERV, CAMBRIDGE, MA 02138 USA. NOAA, AERON LAB, BOULDER, CO 80303 USA. RP Harries, JE (reprint author), UNIV LONDON IMPERIAL COLL SCI & TECHNOL, BLACKETT LAB, PRINCE CONSORT RD, LONDON SW7 2BZ, ENGLAND. RI Tuck, Adrian/F-6024-2011 OI Tuck, Adrian/0000-0002-2074-0538 NR 24 TC 135 Z9 136 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10205 EP 10216 DI 10.1029/95JD02933 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400032 ER PT J AU Bruhl, C Drayson, SR Russell, JM Crutzen, PJ McInerney, JM Purcell, PN Claude, H Gernandt, H McGee, TJ McDermid, IS Gunson, MR AF Bruhl, C Drayson, SR Russell, JM Crutzen, PJ McInerney, JM Purcell, PN Claude, H Gernandt, H McGee, TJ McDermid, IS Gunson, MR TI Halogen occultation experiment ozone channel validation SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC OZONE; ROCOZ-A; PROFILES; AEROSOL AB The HALogen Occultation Experiment (HALOE) instrument on UARS observes vertical profiles of ozone and other gases of interest for atmospheric chemistry using the solar occultation technique. A broadband radiometer in the 9.6-mu m band is used for ozone measurements. Version 17 ozone retrieved by HALOE is intercompared successfully with about 400 profiles of other sounders, including ozonesondes, lidars, balloons, rocketsondes, and other satellites, Usually, the HALOE data are within the error range of the correlative measurements between about 100 and 0.03 mbar atmospheric pressure. Between about 30 and 1 mbar, HALOE agrees typically within 5%, with a tendency to be low. In the first year of data, larger errors sometimes occur in the lower stratosphere due to the necessary correction for Pinatubo aerosol effects, but these differences do not exceed 20%. The data show internal consistency for sunrise and sunset events at the same locations. Some examples of observed ozone distributions, including polar regions, are given. C1 METEOROL OBSERV, D-82383 HOHENPEISSENBERG, GERMANY. UNIV MICHIGAN, ANN ARBOR, MI 48109 USA. ALFRED WEGENER INST POLAR & MARINE RES, D-14473 POTSDAM, GERMANY. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. JET PROP LAB, TABLE MT FACIL, WRIGHTWOOD, CA 92397 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. RP Bruhl, C (reprint author), MAX PLANCK INST CHEM, AIRCHEM DEPT, POB 3060, D-55020 MAINZ, GERMANY. RI Crutzen, Paul/F-6044-2012; McGee, Thomas/G-4951-2013 NR 32 TC 137 Z9 139 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10217 EP 10240 DI 10.1029/95JD02031 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400033 ER PT J AU Gordley, LL Russell, JM Mickley, LJ Frederick, JE Park, JH Stone, KA Beaver, GM McInerney, JM Deaver, LE Toon, GC Murcray, FJ Blatherwick, RD Gunson, MR Abbatt, JPD Mauldin, RL Mount, GH Sen, B Blavier, JF AF Gordley, LL Russell, JM Mickley, LJ Frederick, JE Park, JH Stone, KA Beaver, GM McInerney, JM Deaver, LE Toon, GC Murcray, FJ Blatherwick, RD Gunson, MR Abbatt, JPD Mauldin, RL Mount, GH Sen, B Blavier, JF TI Validation of nitric oxide and nitrogen dioxide measurements made by the halogen occultation experiment for UARS platform SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LOWER THERMOSPHERE; STRATOSPHERIC NO2; O-3; CHEMISTRY; CLO AB The Halogen Occultation Experiment (HALOE) experiment on Upper Atmosphere Research Satellite (UARS) performs solar occultation (sunrise and sunset) measurements to infer the composition and structure of the stratosphere and mesosphere. Two of the HALOE channels, centered at 5.26 mu m and 6.25 mu m, are designed to infer concentrations of nitric oxide and nitrogen dioxide respectively. The NO measurements extend from the lower stratosphere up to 130 km, while the NO2 results typically range from the lower stratosphere to 50 km and higher near the winter terminator. Comparison with results from various instruments are presented, including satellite-, balloon-, and ground-based measurements. Both NO and NO2 can show large percentage errors in the presence of heavy aerosol concentrations, confined to below 25 km and before 1993. The NO2 measurements show mean differences with correlative measurements of about 10 to 15% over the middle stratosphere. The NO2 precision is about 7.5x10(-13) atm, degrading to 2x10(-12) atm in the lower stratosphere. The NO differences are similar in the middle stratosphere but sometimes show a low bias (as much as 35%) between 30 and 60 km with some correlative measurements. NO precision when expressed in units of density is nearly constant at 1x10(-12) atmospheres, or approximately 0.1 ppbv at 10.0 mb or, 1.0 ppbv at 1.0 mb, and so forth when expressed in mixing ratio. Above 65 km, agreement in the mean with Atmospheric Trace Molecule Spectroscopy (ATMOS) NO results is very good, typically +/- 15%. Model comparisons are also presented, showing good agreement with both expected morphology and diurnal behavior for both NO2 and NO. C1 UNIV CHICAGO, DEPT GEOPHYS SCI, CHICAGO, IL 60637 USA. UNIV DENVER, DENVER, CO 80208 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. NOAA, AERON LAB, BOULDER, CO 80303 USA. SCI APPLICAT INT CORP, HAMPTON, VA 23666 USA. RP Gordley, LL (reprint author), GATS INC, 28 RES DR, HAMPTON, VA 23666 USA. RI Mickley, Loretta/D-2021-2012 OI Mickley, Loretta/0000-0002-7859-3470 NR 38 TC 87 Z9 87 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10241 EP 10266 DI 10.1029/95JD02143 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400034 ER PT J AU Hervig, ME Russell, JM Gordley, LL Park, JH Drayson, SR Deshler, T AF Hervig, ME Russell, JM Gordley, LL Park, JH Drayson, SR Deshler, T TI Validation of aerosol measurements from the Halogen Occultation Experiment SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SIZE DISTRIBUTION; PINATUBO AEROSOL; SULFURIC-ACID; VOLATILITY AB Measurements from the Halogen Occultation Experiment (HALOE) are used to infer profiles of aerosol extinction at five infrared wavelengths. This paper provides a validation of the aerosol measurements based on uncertainty analysis, internal validations, comparisons with theory, and comparisons with independent measurements. Monte Carlo calculations using accepted values of random and systematic errors determine typical measurement uncertainties of less than 15% for pressures from 100 to 10 mbar. Comparisons of coincident HALOE sunrise and sunset observations indicate systematic differences (sunrise > sunset) for pressures less than 10 mbar. Random sunrise-sunset differences, taken as an upper limit of the measurement precision, are generally from 10 to similar to 30% for pressures from 100 to 10 mbar. Measured extinction ratios are compared with ratios determined from theory. These comparisons show that the measurements are consistent with theory at pressures from 100 to 10 mbar, depending on channels, latitude, and season. HALOE extinctions are compared with extinctions calculated from balloon-borne particle counter measurements. The results show random differences from 30 to 50% for pressures from 100 to 10 mbar and systematic differences (HALOE > particle counters) for pressures less than 40 mbar. The results indicate that the HALOE 2.80 mu m aerosol measurements are much less reliable than the other four measurements. C1 UNIV MICHIGAN, DEPT SPACE PHYS, ANN ARBOR, MI 48105 USA. GATS INC, HAMPTON, VA 23666 USA. NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. RP Hervig, ME (reprint author), UNIV WYOMING, DEPT ATMOSPHER SCI, LARAMIE, WY 82071 USA. NR 12 TC 35 Z9 37 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10267 EP 10275 DI 10.1029/95JD02464 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400035 ER PT J AU Hervig, ME Russell, JM Gordley, LL Drayson, SR Stone, K Thompson, RE Gelman, ME McDermid, IS Hauchecorne, A Keckhut, P McGee, TJ Singh, UN Gross, MR AF Hervig, ME Russell, JM Gordley, LL Drayson, SR Stone, K Thompson, RE Gelman, ME McDermid, IS Hauchecorne, A Keckhut, P McGee, TJ Singh, UN Gross, MR TI Validation of temperature measurements from the Halogen Occultation Experiment SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LIDAR AB The Halogen Occultation Experiment (HALOE) onboard UARS measures profiles of limb path solar attenuation in eight infrared bands. These measurements are used to infer profiles of temperature, gas mixing ratios of seven species, and aerosol extinction at five wavelengths. The objective of this paper is to validate profiles of temperature retrieved from atmospheric transmission measurements in the 2.80-mu m CO2 band. Temperatures are retrieved fur levels above where aerosol affects the signals (35 km) to altitudes where the signal-to-noise decreases to unity (similar to 85 km). At altitudes from 45 to 35 km the profile undergoes a gradual transition from retrieved to National Meteorological Center (NMC) temperatures and below 35 km the profile is strictly from the NMC. This validation covers the uncertainty analysis, internal validations, and comparisons with independent measurements. Monte Carlo calculations using all known random and systematic errors determine typical measurement uncertainties of 5 K for altitudes below 80 km. Comparisons of coincident HALOE sunrise and sunset measurements are an indicator of the upper limit of measurement uncertainty. The sunrise-sunset comparisons have random and systematic differences which are less than 10 K for altitudes below 80 km. Comparisons of HALOE to lidar and rocket measurements typically have random differences of similar to 5 K for altitudes below 65 km. The mean differences for the correlative comparisons indicate that HALOE temperatures have a cold bias (2 to 5 K) in the upper stratosphere and stratopause. C1 UNIV MICHIGAN, DEPT SPACE PHYS, ANN ARBOR, MI 48109 USA. NOAA, NATL WEATHER SERV, WASHINGTON, DC 20233 USA. GATS INC, HAMPTON, VA 23666 USA. HUGHES STX, LANHAM, MD 20706 USA. CNRS, SERV AERON, F-91371 VERRIERES LE BUISSON, FRANCE. CALTECH, JET PROPULS LAB, TABLE MT FAC, PASADENA, CA 92397 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. RP Hervig, ME (reprint author), UNIV WYOMING, DEPT ATMOSPHER SCI, POB 3038, LARAMIE, WY 82071 USA. RI Hauchecorne, Alain/A-8489-2013; McGee, Thomas/G-4951-2013 NR 13 TC 60 Z9 62 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10277 EP 10285 DI 10.1029/95JD01713 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400036 ER PT J AU Singh, UN Keckhut, P McGee, TJ Gross, MR Hauchecorne, A Fishbein, EF Waters, JW Gille, JC Roche, AE Russell, JM AF Singh, UN Keckhut, P McGee, TJ Gross, MR Hauchecorne, A Fishbein, EF Waters, JW Gille, JC Roche, AE Russell, JM TI Stratospheric temperature measurements by two collocated NDSC lidars during UARS validation campaign SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MIDDLE ATMOSPHERE; MESOSPHERE; ROCKETSONDE; OZONE AB The NASA Goddard Space Flight Center (GSFC) mobile lidar system was deployed at the Observatoire de Haute Provence (OHP), during an Upper Atmosphere Research Satellite (UARS)/Network for Detection of Stratospheric Change (NDSC) correlative measurement campaign (July-August 1992). The objective of this campaign was twofold: to intercompare two independent lidars and to provide ground-based UARS correlative ozone and temperature validation measurements. This paper, for the first time, presents a coincident temperature intercomparison between two independently operating temperature lidar systems of similar capabilities. Systems and retrieval algorithms have been described and discussed in terms of error sources. The comparison of the two analysis have shown very similar results up to the upper mesosphere. The statistical mean differences of 0.5 K in the stratosphere and about 2 K in the mesosphere suggests insignificant bias throughout except below 35 km, where one of the data sets is contaminated by the volcanic aerosols from the eruption of Mount Pinatubo. Profiles of the root-mean-square (RMS) of the differences are in good agreement with random error estimates, except around 35-40 km where RMS is larger. These measurements can be used as the ground reference for UARS temperature validation. However, the spatial-temporal coincidence between satellite and lidar needs to be carefully considered for meaningful validation. C1 CNRS, SERV AERON, BP3, F-91371 VERRIERES LE BUISSON, FRANCE. NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, CODE 916, GREENBELT, MD 20771 USA. CALTECH, JET PROP LAB, MS 183-701, PASADENA, CA 91109 USA. NATL CTR ATMOSPHER RES, POB 3000, BOULDER, CO 80307 USA. LOCKHEED PALO ALTO RES LABS, DEPT 91-20, PALO ALTO, CA 94304 USA. NASA, LANGLEY RES CTR, MS 401B, HAMPTON, VA 23681 USA. RP Singh, UN (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HUGHES STX CORP, CODE 916, GREENBELT, MD 20771 USA. RI Hauchecorne, Alain/A-8489-2013; McGee, Thomas/G-4951-2013 NR 40 TC 32 Z9 35 U1 2 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10287 EP 10297 DI 10.1029/96JD00516 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400037 ER PT J AU Keckhut, P Gelman, ME Wild, JD Tissot, F Miller, AJ Hauchecorne, A Chanin, ML Fishbein, EF Gille, J Russell, JM Taylor, FW AF Keckhut, P Gelman, ME Wild, JD Tissot, F Miller, AJ Hauchecorne, A Chanin, ML Fishbein, EF Gille, J Russell, JM Taylor, FW TI Semidiurnal and diurnal temperature tides (30-55 km): Climatology and effect on UARS-LIDAR data comparisons SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID EQUATORIAL MIDDLE ATMOSPHERE; RAYLEIGH LIDAR; SOLAR; VARIABILITY; ROCKETSONDE; MODEL; WAVES AB Very good agreement is shown for diurnal and semidiurnal temperature variations calculated from lidar measurements in southern France and from data of the microwave limb sounder of the Upper Atmosphere Research Satellite (UARS). Tides induce temperature deviations observed in southern France to be as large as +/-3 K, with a maximum at the stratopause. The amplitudes and phases of the semidiurnal variation change significantly with season and location. Seasonal changes up to 2 K have been clearly identified for the diurnal component. An analytic model of the diurnal component, based on sinusoidal functions, fits the data well, but is less successful for the semidiurnal component. Substantial agreement is also reported for the diurnal component between the results of our analytical model and the published results of a two-dimensional global-scale wave model. In contrast, the semidiurnal component is in total disagreement with numerical simulations that report very small amplitudes, as compared with the observations reported here. The confidence in detecting bias in data comparisons is improved if data used are limited to periods from April to September and if time-of-day adjustments are applied. Comparison between lidar and nearly coincident UARS temperature measurements have revealed, systematically, for the 4 experiments aboard UARS, a significant residual mean difference of up to 3 K around 35-43 km. A comparison using simultaneous measurements suggests that the bias is associated with the variability of migrating tides and/or the presence of nonmigrating tides rather than instrumental characteristics. C1 CALTECH, JET PROP LAB, MS 183 701, PASADENA, CA 91109 USA. NOAA, NATL WEATHER SERV, NATL METEOROL CTR, CLIMATE ANAL CTR, WASHINGTON, DC 20233 USA. NATL CTR ATMOSPHER RES, POB 3000, BOULDER, CO 80307 USA. NASA, LANGLEY RES CTR, MS 401B, HAMPTON, VA 23681 USA. UNIV OXFORD, OXFORD OX1 3PU, ENGLAND. RP Keckhut, P (reprint author), CNRS, SERV AERON, BP 3, F-91371 VERRIERES LE BUISSON, FRANCE. RI Hauchecorne, Alain/A-8489-2013 NR 33 TC 45 Z9 45 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10299 EP 10310 DI 10.1029/96JD00344 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400038 ER PT J AU Manney, GL Swinbank, R Massie, ST Gelman, ME Miller, AJ Nagatani, R ONeill, A Zurek, RW AF Manney, GL Swinbank, R Massie, ST Gelman, ME Miller, AJ Nagatani, R ONeill, A Zurek, RW TI Comparison of UK Meteorological Office and US National Meteorological Center stratospheric analyses during northern and southern winter SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID POLAR VORTEX; TEMPERATURE; MLS AB Meteorological data from the United Kingdom Meteorological Office (UKMO), produced using a data assimilation system, and the U.S, National Meteorological Center (NMC), produced using an objective analysis procedure, are compared for dynamically active periods during the Arctic and Antarctic winters of 1992. The differences seen during these periods are generally similar to those seen during other winter periods. Both UKMO and NMC analyses capture the large-scale evolution of the stratospheric circulation during northern hemisphere (NH) and southern hemisphere (SH) winters, Stronger vertical and horizontal temperature gradients develop in the UKMO than in the NMC data during stratospheric warmings; comparison with satellite measurements with better vertical resolution suggests that the stronger vertical temperature gradients are more realistic. The NH polar vortex is slightly stronger in the UKMO analyses than in the NMC in the middle and upper stratosphere, and midstratospheric temperatures are slightly lower. The SH polar vortex as represented in the UKMO analyses is stronger and colder in the midstratosphere than its representation in the NMC analyses. The UKMO analyses on occasion exhibit some difficulties in representing cross-polar flow or changes in curvature of the wind field at very high latitudes. In addition to the above study of two wintertime periods, a more detailed comparison of lower-stratospheric temperatures is done for all Arctic and Antarctic winter periods since the launch of the Upper Atmosphere Research Satellite. In the NH lower stratosphere during winter, NMC temperatures are consistently lower than UKMO temperatures and closer to radiosonde temperatures than are UKMO temperatures. Conversely, in the SH lower stratosphere during winter, UKMO temperatures are typically lower than NMC and are closer to radiosonde temperature observations. C1 NOAA, NATL WEATHER SERV, NATL METEOROL CTR, WASHINGTON, DC 20233 USA. RP Manney, GL (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, MAIL STOP 183-701, PASADENA, CA 91109 USA. NR 25 TC 72 Z9 72 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10311 EP 10334 DI 10.1029/95JD03350 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400039 ER PT J AU Cunnold, DM Froidevaux, L Russell, JM Connor, B Roche, A AF Cunnold, DM Froidevaux, L Russell, JM Connor, B Roche, A TI Overview of UARS ozone validation based primarily on intercomparisons among UARS and stratospheric aerosol and gas experiment II measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB Comparisons among Stratospheric Aerosol and Gas Experiment (SAGE) II, microwave limb sounder (MLS) (version 3), cryogenic limb array etalon spectrometer (CLAES) (version 7), improved stratospheric and mesospheric sounder (ISAMS) (version 10), and Halogen Occultation Experiment (HALOE) (version 17) ozone profiles are reported with the emphasis being on the periods of January 9-11, April 15-20, and August 25-30, 1992, which were selected for analysis at four UARS validation workshops. The differences with respect to SAGE II are consistent with the conclusions of those workshops, MLS values are found to be systematically approximately 5% larger than SAGE II values except at 1 mbar (where they are approximately 5% smaller) and at 46 mbar in the tropics where they are approximately 20% too small (perhaps with some time dependence to this difference). HALOE values are systematically approximately 5% lower than SAGE II values, with a tendency for this difference to increase slightly in the upper part of the altitude range. CLAES values are approximately 15% high near 4.6 mbar and at 46 mbar in the tropics and are approximately 20% low near 0.32 mbar but show small differences near 1 and 10 mbar. ISAMS produced considerably more variable differences with respect to the other sensors both in space and in time. There remains clear evidence of Pinatubo aerosol contamination of ISAMS values at 10 mbar (the lowest level of the v10 retrievals) in January. The standard deviations of the differences between the coincidentally measured ozone profiles are generally consistent with the prescribed profile error bars of better than 5% from approximately 46 to 0.46 mbar for HALOE and from 1.5 to 15 mbar for MLS (and to approximately 0.46 mbar fur the 183-GHz measurements). For ISAMS also, the error bars of 10-15% are consistent with the standard deviations of the differences, but for CLAES, the precision seems to be approximately 10% and would be approximately 20% if the relatively systematic, vertical structure differences were to be included in the error bars. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. LOCKHEED CLAES, PALO ALTO, CA 94106 USA. RP Cunnold, DM (reprint author), GEORGIA INST TECHNOL, SCH EARTH & ATMOSPHER SCI, ATLANTA, GA 30332 USA. NR 10 TC 31 Z9 31 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10335 EP 10350 DI 10.1029/95JD01697 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400040 ER PT J AU Burrage, MD Skinner, WR Gell, DA Hays, PB Marshall, AR Ortland, DA Manson, AH Franke, SJ Fritts, DC Hoffman, P McLandress, C Niciejewski, R Schmidlin, FJ Shepherd, GG Singer, W Tsuda, T Vincent, RA AF Burrage, MD Skinner, WR Gell, DA Hays, PB Marshall, AR Ortland, DA Manson, AH Franke, SJ Fritts, DC Hoffman, P McLandress, C Niciejewski, R Schmidlin, FJ Shepherd, GG Singer, W Tsuda, T Vincent, RA TI Validation of mesosphere and lower thermosphere winds from the high resolution Doppler imager on UARS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERE RESEARCH SATELLITE; PARTIAL REFLECTION RADAR; SASKATOON 52-DEGREES-N; MIDDLE ATMOSPHERE; MESOPAUSE REGION; METEOR RADAR; TIDAL WINDS; POKER-FLAT; MEAN WINDS; TIDES AB Horizontal wind fields in the mesosphere and lower thermosphere are obtained with the high resolution Doppler imager (HRDI) on the Upper Atmosphere]Research Satellite (UARS) by observing the Doppler shifts of emission lines in the O-2 atmospheric band, The validity of the derived winds depends on an accurate knowledge of the positions on the detector of the observed lines in the absence of a wind-induced Doppler shift, Relative changes in these positions are readily identified in the routine measurements of onboard calibration lines. The determination of the absolute values relies on the comparison of HRDI observations with those obtained by MF radars and rockets. In addition, the degrees of horizontal and vertical smoothing of the recovered wind profiles have been optimized by examining the effects of these parameters both on the amplitude of the HRDI-derived diurnal tidal amplitude and on the variance of the wind differences with correlative measurements. This paper describes these validation procedures and presents comparisons with correlative data. The main discrepancy appears to be in the relative magnitudes measured by HRDI and by the MF radar technique. Specifically, HRDI generally observes larger winds than the MF radars, but the size of the discrepancy varies significantly between different stations, HRDI wind magnitudes are found to be somewhat more consistent with measurements obtained by the rocket launched falling sphere technique and are in very good agreement with the wind imaging interferometer (WINDII), also flown on UARS. C1 UNIV SASKATCHEWAN, INST SPACE & ATMOSPHER STUDIES, SASKATOON, SK S7N 0W0, CANADA. UNIV ILLINOIS, WAVE PROPAGAT LAB, URBANA, IL 61801 USA. UNIV COLORADO, ATMOSPHER & SPACE PHYS LAB, BOULDER, CO 80309 USA. INST ATMOSPHER PHYS, KUHLUNGSBORN, GERMANY. YORK UNIV, INST SPACE & TERR SCI, TORONTO, ON M3J 2R7, CANADA. NASA, GODDARD SPACE FLIGHT CTR, WALLOPS FLIGHT FAC, WALLOPS ISL, VA 23337 USA. KYOTO UNIV, CTR RADIO ATMOSPHER SCI, KYOTO, JAPAN. UNIV ADELAIDE, DEPT PHYS & MATH PHYS, ADELAIDE, SA 5001, AUSTRALIA. RP UNIV MICHIGAN, SPACE PHYS RES LAB, 2455 HAYWARD ST, ANN ARBOR, MI 48109 USA. RI tsuda, toshitaka/A-3035-2015 NR 54 TC 98 Z9 99 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10365 EP 10392 DI 10.1029/95JD01700 PG 28 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400042 ER PT J AU Fleming, EL Chandra, S Burrage, MD Skinner, WR Hays, PB Solheim, BH Shepherd, GG AF Fleming, EL Chandra, S Burrage, MD Skinner, WR Hays, PB Solheim, BH Shepherd, GG TI Climatological mean wind observations from the UARS high-resolution Doppler imager and wind imaging interferometer: Comparison with current reference models SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERE RESEARCH SATELLITE; EQUATORIAL MIDDLE ATMOSPHERE; SEMIANNUAL OSCILLATION; LOWER THERMOSPHERE; ZONAL WIND; GEOPOTENTIAL HEIGHT; SEASONAL-VARIATION; UPPER MESOSPHERE; NUMERICAL-MODEL; GRAVITY-WAVE AB Direct wind measurements from the high-resolution Doppler imager (HRDI) and wind imaging interferometer (WINDII) instruments onboard the Upper Atmosphere Research Satellite (UARS) represent a substantial increase in the number of available wind observations in the mesosphere-to lower-thermosphere region. These unique data sets provide an opportunity to evaluate current climatological reference models in the 80-to 120-km region which are based on limited empirical data coverage available during the pre-UARS time period. Below 80 km the general climatological features have been fairly well established by previous observational databases. The reference models therefore provide a means for validating the climatological mean UARS observations in the lowe-mesosphere, especially at midlatitudes. We have used 2-3 years of UARS HRDI and WINDII observations to construct a monthly and diurnal mean zonally averaged climatology of zonal and meridional wind for the 50-to 120-km region. We use this to compare with the current CIRA-86 and HWM-93 reference models. Comparisons are limited to regions where the tidal oscillations can be adequately removed from the UARS observations using simple binning and averaging methods. At 50-80 km the reference models, which are based on gradient winds derived from temperatures, compare well with the HRDI data in reproducing the overall seasonal variations, including the magnitudes and positions of the winter westerly and summer easterly jets at midlatitudes. At 95 km, HRDI and WINDII show year-round easterlies at low latitudes and indicate a strong westerly jet during summer and weaker, more variable flow during winter at midlatitudes. The CIRA-86 gradient winds at 95 km show some qualitative agreement with the UARS data at midlatitudes, especially in simulating the summertime jet, However, the comparison is poor at low latitudes. We attribute this to the lack of available temperature measurements in this region from which the gradient winds are derived, The HWM-93 model, which is based mainly on medium frequency and meteor radar winds at 95 km, shows qualitatively similar seasonal variations in both zonal and meridional wind compared with the UARS data in this region. However, the HWM model is consistently smaller by a factor of 2-3 in wind magnitude relative to the UARS measurements at 95 km. C1 UNIV MICHIGAN, DEPT ATMOSPHER OCEAN & SPACE SCI, SPACE PHYS RES LAB, ANN ARBOR, MI 48109 USA. YORK UNIV, INST SPACE & TERR SCI, N YORK, ON M3J 1P3, CANADA. RP Fleming, EL (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 916, GREENBELT, MD 20771 USA. NR 55 TC 39 Z9 43 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1996 VL 101 IS D6 BP 10455 EP 10473 DI 10.1029/95JD01043 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ404 UT WOS:A1996UJ40400047 ER PT J AU Cartwright, DC Trajmar, S AF Cartwright, DC Trajmar, S TI Resonant electron-impact excitation of vibrational modes in polyatomic molecules SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID CROSS-SECTIONS; TRIATOMIC-MOLECULES; BOOMERANG MODEL; STATES; CO2; SPECTROSCOPY; SCATTERING; SPECTRA AB Measured differential cross sections (DCSs) for electron-impact excitation of bending vibrational modes involving an odd number of vibrational quanta in CO2 by 4 eV incident energy electrons display a strong trend to zero for forward and backward scattering which is characteristic of 'symmetry-forbidden' transitions. This DCS behaviour is postulated here to be produced by a Feshbach resonant mechanism involving a low-lying bent excited state of CO2. The model described here identifies three additional low-lying bent excited states of CO2 which could also be parent states for core-excited Feshbach resonances, one of which may play a role in dissociative attachment in this 3.5-5.0 eV energy region. The resonant vibrational excitation mechanism proposed here is also believed to be operative in other polyatomic molecules and could be investigated by performing selected electron energy-loss measurements within the lowest energy resonance regions of the molecules CO2, N2O, OCS, CS2 and SO2. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Cartwright, DC (reprint author), LOS ALAMOS NATL LAB,POB 1663,LOS ALAMOS,NM 87545, USA. NR 46 TC 10 Z9 10 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD APR 28 PY 1996 VL 29 IS 8 BP 1549 EP 1562 DI 10.1088/0953-4075/29/8/018 PG 14 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA UJ320 UT WOS:A1996UJ32000018 ER PT J AU Cutten, DR Pueschel, RF Bowdle, DA Srivastava, V Clarke, AD Rothermel, J Spinhirne, JD Menzies, RT AF Cutten, DR Pueschel, RF Bowdle, DA Srivastava, V Clarke, AD Rothermel, J Spinhirne, JD Menzies, RT TI Multiwavelength comparison of modeled and measured remote tropospheric aerosol backscatter over Pacific Ocean SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SCATTERING SPECTROMETER PROBE; FSSP-300 AB Aerosol concentrations and size distributions in the middle and upper troposphere over the remote Pacific Ocean were measured with a forward scattering spectrometer probe (FSSP) nn thp NASA DC-8 aircraft during NASA's Global Backscatter Experiment (GLOBE) in May-June 1990, The FSSP size channels were recalibrated based on refractive index estimates from flight-level aerosol volatility measurements with a collocated laser optical particle counter (LOPC). The recalibrated FSSP size distributions were averaged over 100-s intervals, fitted with lognormal distributions and used to calculate aerosol backscatter coefficients at selected wavelengths, The FSSP-derived backscatter estimates were averaged over 300-s intervals to reduce large random fluctuations. The smoothed FSSP aerosol backscatter coefficients were then compared with LOPC-derived backscatter values and with backscatter measured at or near flight level from four lidar systems operating at 0.53, 1.06, 9.11, 9.25, and 10.59 mu m. Agreement between FSSP-derived and lidar-measured backscatter was generally best at flight level in homogeneous aerosol fields and at high backscatter values. FSSP data often underestimated low backscatter values especially at the longer wavelengths due to poor counting statistics for larger particles (> 0.8 mu m diameter) that usually dominate aerosol backscatter at these wavelengths. FSSP data also underestimated backscatter at shorter wavelengths when particles smaller than the FSSP lower cutoff diameter (0.35 mu m) made significant contributions to the total backscatter. C1 UNIV ALABAMA, EARTH SYST SCI LAB, HUNTSVILLE, AL 35899 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV SPACE RES ASSOC, HUNTSVILLE, AL 35806 USA. UNIV HAWAII MANOA, SCH OCEANOG, HONOLULU, HI 96822 USA. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP Cutten, DR (reprint author), UNIV ALABAMA, INST GLOBAL CHANGE RES & EDUC, HUNTSVILLE, AL 35899 USA. NR 24 TC 14 Z9 14 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 1996 VL 101 IS D5 BP 9375 EP 9389 DI 10.1029/95JD03423 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ130 UT WOS:A1996UJ13000006 ER PT J AU Minschwaner, K Dessler, AE Elkins, JW Volk, CM Fahey, DW Loewenstein, M Podolske, JR Roche, AE Chan, KR AF Minschwaner, K Dessler, AE Elkins, JW Volk, CM Fahey, DW Loewenstein, M Podolske, JR Roche, AE Chan, KR TI Bulk properties of isentropic mixing into the tropics in the lower stratosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SOLAR-RADIATION; N2O; SPECTROMETER; LATITUDES; CLIMATE; CF2CL2; MODEL; CFCL3 AB Timescales for mixing of midlatitude air into the tropical lower stratosphere are deduced from observations of long-lived tracers N2O and CCl3F, Bulk mixing between tropical and midlatitude regions is assumed to be isentropic and relatively slow compared with local mixing within each region. The mean value of the mixing timescale ranges from 12 to 18 months near 20 km, There is a tendency for shorter mixing times at higher and lower altitudes, although vertical profiles of mixing cannot be definitively established by the data, A more robust quantity is given by the fraction of midlatitude air entrained into the tropical upwelling region, Implied mixing fractions exceed 50% above 22 km. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NOAA, CLIMATE MONITORING & DIAGNOST LAB, BOULDER, CO 80303 USA. NOAA, AERON LAB, BOULDER, CO 80303 USA. LOCKHEED PALO ALTO RES LABS, PALO ALTO, CA 94303 USA. RP Minschwaner, K (reprint author), NEW MEXICO INST MIN & TECHNOL, DEPT PHYS, SOCORRO, NM 87801 USA. RI Fahey, David/G-4499-2013; Dessler, Andrew/G-8852-2012 OI Fahey, David/0000-0003-1720-0634; Dessler, Andrew/0000-0003-3939-4820 NR 36 TC 68 Z9 67 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 1996 VL 101 IS D5 BP 9433 EP 9439 DI 10.1029/96JD00335 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ130 UT WOS:A1996UJ13000010 ER PT J AU Bacmeister, JT Eckermann, SD Newman, PA Lait, L Chan, KR Loewenstein, M Proffitt, MH Gary, BL AF Bacmeister, JT Eckermann, SD Newman, PA Lait, L Chan, KR Loewenstein, M Proffitt, MH Gary, BL TI Stratospheric horizontal wavenumber spectra of winds, potential temperature, and atmospheric tracers observed by high-altitude aircraft SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ANTARCTIC OZONE EXPERIMENT; WAVE NUMBER SPECTRA; GRAVITY-WAVES; PERTURBATION SPECTRA; BALLOON OBSERVATIONS; ENERGY-DISSIPATION; LIDAR OBSERVATIONS; MESOSCALE MOTIONS; FREQUENCY-SPECTRA; MIDDLE ATMOSPHERE AB Horizontal wavenumber power spectra of vertical and horizontal wind velocities, potential temperatures, and ozone and N2O mixing ratios, as measured in the mid-stratosphere during 73 ER-2 flights (altitude approximate to 20 km) are presented. The velocity and potential temperature spectra in the 100 to 1-km wavelength range deviate significantly from the uniform -5/3 power law expected for the inverse energy-cascade regime of two-dimensional turbulence and also for inertial-range, three-dimensional turbulence. Instead, steeper spectra approximately consistent with a -3 power law are observed at horizontal scales smaller than 3 km for all velocity components as well as potential temperature. Shallower spectra are observed at scales longer than 6 km. For horizontal velocity and potential temperature the spectral indices at longer scales are between -1.5 and -2.0. For vertical velocity the spectrum at longer scales becomes flat. It is argued that the observed velocity and potential temperature spectra are consistent with gravity waves. At smaller scales, the shapes are also superficially consistent with a Lumley-Shur-Weinstock buoyant subrange of turbulence and/or nonlinear gravity waves. Contemporaneous spectra of ozone and N2O mixing ratio in the 100 to 1-km wavelength range do conform to an approximately uniform -5/3 power law. It is argued that this may reflect interactions between gravity wave air-parcel displacements and laminar or filamentary structures in the trace gas mixing ratio field produced by enstrophy-cascading two-dimensional turbulence. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. COMPUTAT PHYS INC, FAIRFAX, VA 22031 USA. NASA, JET PROP LAB, PASADENA, CA 91109 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NOAA, AERON LAB, BOULDER, CO 80303 USA. RP Bacmeister, JT (reprint author), USN, RES LAB, WASHINGTON, DC 20375 USA. RI Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 99 TC 103 Z9 104 U1 2 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 1996 VL 101 IS D5 BP 9441 EP 9470 DI 10.1029/95JD03835 PG 30 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ130 UT WOS:A1996UJ13000011 ER PT J AU Nash, ER Newman, PA Rosenfield, JE Schoeberl, MR AF Nash, ER Newman, PA Rosenfield, JE Schoeberl, MR TI An objective determination of the polar vortex using Ertel's potential vorticity SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID BREAKING PLANETARY-WAVES; STRATOSPHERE; OZONE; DYNAMICS; TRANSPORT; TRACER; RESOLUTION; EVOLUTION; RADIATION; MODEL AB We have developed objective criteria for choosing the location of the northern hemisphere polar vortex boundary region and the onset and breakup dates of the vortex. By determining the distribution of Ertel's potential vorticity (Epv) on equivalent latitudes, we define the vortex edge as the location of maximum gradient of Epv constrained by the location of the maximum wind jet calculated along Epv isolines. We define the vortex boundary region to be at the local maximum convex and concave curvature in the Epv distribution surrounding the edge. We have determined that the onset and breakup dates of the vortex on the 450 K isentropic surface occur when the maximum wind speed calculated along Epv isolines rises above and falls below approximately 15.2 m s(-1). We use 1992-1993 as a test case to study the onset and breakup periods, and we find that the increase of polar vortex Epv values is associated with the dominance of the term in the potential vorticity equation involving the movement of air through the surface due to the diabatic circulation, We also find that the decrease is associated with the dominance of the term involving radiatively induced changes in the stability of the atmosphere. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RI Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 43 TC 346 Z9 356 U1 4 U2 18 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 1996 VL 101 IS D5 BP 9471 EP 9478 DI 10.1029/96JD00066 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UJ130 UT WOS:A1996UJ13000012 ER PT J AU Bell, JF Calvin, WM OckertBell, ME Crisp, D Pollack, JB Spencer, J AF Bell, JF Calvin, WM OckertBell, ME Crisp, D Pollack, JB Spencer, J TI Detection and monitoring of H2O and CO2 ice clouds on Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID INFRARED SPECTROSCOPY; REFLECTANCE SPECTRA; GENERAL-CIRCULATION; MARTIAN ATMOSPHERE; CARBONATES; MARINER-9; CLIMATE; REGIONS AB We have developed an observational scheme for the detection and discrimination of Mars atmospheric H-2 and CO2 clouds using ground-based instruments in the near infrared. We report the results of our cloud detection and characterization study using Mars near IR images obtained during the 1990 and 1993 oppositions, We focused on specific wavelengths that have the potential, based on previous laboratory studies of H2O and CO2 ices, of yielding the greatest degree of cloud detectability and compositional discriminability. We have detected and mapped absorption features at some of these wavelengths in both the northern and southern polar regions of Mars, Compositional information on the nature of these absorption features was derived from comparisons with laboratory ice spectra and with a simplified radiative transfer model of a CO2 ice cloud overlying a bright surface. Our results indicate that both H2O and CO2 ices can be detected and distinguished in the polar hood clouds. The region near 3.00 mu m is mast useful for the detection of water ice clouds because there is a strong H2O ice absorption at this wavelength but only a weak CO2 ice band, The region near 3.33 mu m is most useful for the detection of CO2 ice clouds because there is a strong, relatively narrow CO2 ice band at this wavelength but only broad ''continuum'' H2O ice absorption. Weaker features near 2.30 mu m could arise from CO2 ice at coarse grain sizes, or surface/dust minerals. Narrow features near 2.00 mu m, which could potentially be very diagnostic of CO2 ice clouds, suffer from contamination by Mars atmospheric CO2 absorptions and are difficult to interpret because of the rather poor knowledge of surface elevation at high latitudes. These results indicate that future ground-based, Earth-orbital, and spacecraft studies over a more extended span of the seasonal cycle should yield substantial information on the style and timing of volatile transport on Mars, as well as a more detailed understanding of the role of CO2 condensation in the polar heat budget. C1 US GEOL SURVEY,BRANCH ASTROGEOL,FLAGSTAFF,AZ 86001. CALTECH,JET PROP LAB,PASADENA,CA 91109. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. LOWELL OBSERV,FLAGSTAFF,AZ 86001. RP Bell, JF (reprint author), CORNELL UNIV,DEPT ASTRON,CTR RADIOPHYS & SPACE RES,ITHACA,NY 14853, USA. NR 60 TC 28 Z9 28 U1 0 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD APR 25 PY 1996 VL 101 IS E4 BP 9227 EP 9237 DI 10.1029/96JE00689 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UG926 UT WOS:A1996UG92600002 ER PT J AU Kiefer, WS Bills, BG Nerem, RS AF Kiefer, WS Bills, BG Nerem, RS TI An inversion of gravity and topography for mantle and crustal structure on Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID THARSIS REGION; LITHOSPHERIC STRESS; GEOID ANOMALIES; VENUS GRAVITY; MODEL; EVOLUTION; EARTH; THICKNESS; PROVINCE; PLANETS AB Analysis of the gravity and topography of Mars presently provides our primary quantitative constraints on the internal structure of Mars. We present an inversion of the long-wavelength (harmonic degree less than or equal to 10) gravity and topography of Mars for lateral variations of mantle temperature and crustal thickness. Our formulation incorporates both viscous mantle how (which most prior studies have neglected) and isostatically compensated density anomalies in the crust and lithosphere. Our nominal model has a 150-km-thick high-viscosity surface layer over an isoviscous mantle, with a core radius of 1840 km. It predicts lateral temperature variations of up to a few hundred degrees Kelvin relative to the mean mantle temperature, with high temperature under Tharsis and to a lesser extent under Elysium and cool temperatures elsewhere. Surprisingly, the model predicts crustal thinning beneath Tharsis. If correct, this implies that thinning of the crust by mantle shear stresses dominates over thickening of the crust by volcanism. The major impact basins (Hellas, Argyre, Isidis, Chryse, and Utopia) are regions of crustal thinning, as expected. Utopia is also predicted to be a region of hot mantle, which is hard to reconcile with the surface geology. An alternative model for Utopia treats it as a mascon basin. The Utopia gravity anomaly is consistent with the presence of a 1.2 to 1.6 km thick layer of uncompensated basalt, in good agreement with geologic amount of volcanic fill in this area. The mantle thermal structure is the dominant contributor to the observed geoid in our inversion. The mantle also dominates the topography at the longest wavelengths, but shorter wavelengths (harmonic degrees greater than or equal to 4) are dominated by the crustal structure. Because of the uncertainty about the appropriate numerical values for some of the model's input parameters, we have examined the sensitivity of the model results to the planetary structural model (core radius and core and mantle densities), the mantle's viscosity stratification, and the mean crustal thickness. The model results are insensitive to the specific thickness or viscosity contrast of the high-viscosity surface layer and to the mean crustal thickness in the range 25 to 100 km. Models with a large core radius or with an upper mantle low-viscosity zone require implausibly large lateral variations in mantle temperature. C1 NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,SPACE GEODESY BRANCH,GREENBELT,MD 20771. RP Kiefer, WS (reprint author), LUNAR & PLANETARY INST,3600 BAY AREA BLVD,HOUSTON,TX 77058, USA. RI Bills, Bruce/C-1156-2008; OI Kiefer, Walter/0000-0001-6741-5460 NR 61 TC 27 Z9 27 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD APR 25 PY 1996 VL 101 IS E4 BP 9239 EP 9252 DI 10.1029/95JE03699 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UG926 UT WOS:A1996UG92600003 ER PT J AU Iga, I Rao, MVVS Srivastava, SK AF Iga, I Rao, MVVS Srivastava, SK TI Absolute electron impact ionization cross sections for N2O and NO from threshold up to 1000 eV SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID DISSOCIATIVE ELECTROIONIZATION; NITROUS-OXIDE; PHOTOIONIZATION; CHANNELS; N+; O+ AB Cross sections for the production of singly charged ions by electron impacton N2O and NO have been obtained by utilizing the relative flow technique in which the accurately known values of cross sections for the production of singly charged ions of rare gases have been used for normalization. By summing the cross sections for direct ionization and dissociative ionization, the total ionization cross sections have been obtained and compared with the previously available data. Energies for the appearance of various ions have also been measured and compared with previous determinations from photoelectron spectroscopy. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RI Iga, Ione/C-1273-2015 NR 24 TC 32 Z9 32 U1 2 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD APR 25 PY 1996 VL 101 IS E4 BP 9261 EP 9266 DI 10.1029/96JE00467 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UG926 UT WOS:A1996UG92600005 ER PT J AU Rettig, TW Mumma, MJ Sobczak, GJ Hahn, JM DiSanti, M AF Rettig, TW Mumma, MJ Sobczak, GJ Hahn, JM DiSanti, M TI The nature of comet Shoemaker-Levy 9 subnuclei from analysis of preimpact Hubble Space Telescope images SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID NUCLEI; MODEL AB We obtained Hubble Space Telescope (HST) Wide Field Planetary Camera images of comet Shoemaker-Levy 9 (S-L 9) prior to impact with Jupiter in 1994 to observe the effects of the Jovian gravitational field on the approaching fragments. The HST images were used to monitor the absolute brightness in the central regions of the comae, changes in the surface brightness profiles, and general morphological changes in the fragments as they approached final impact with Jupiter. S-L 9 most likely came apart under the influence of the Jovian tidal force near perijove in 1992 [Scotti and Melosh, 1993; Asphaug and Bent, 1994a; Solem, 1994; Sekanina et al., 1994] into approximately 20 fragments [Scotti, 1993; Luu and Jewitt, 1993; Weaver et al., 1994]. In contrast to condensed or solid fragments, we suggested that after perijove, the breakup debris condensed initially as swarms of particles [Rettig et al., 1994a; Olson and Mumma, 1994] and if interparticle collisions were infrequent, some of these swarm-like subnuclei might have remained extended throughout the 2-year orbit. In this paper we discuss a simple analytical model to demonstrate how after the original nucleus came apart, the debris cloud formed 14-20 fragments. We also present temporal magnitudes of all fragments obtained from the HST images from January through July 1994 and an analysis of the preimpact images for four S-L 9 condensations T(4), Q2(7b), P1(8a), and K(12) which suggests that not all of the central subnuclei were consistent with solid objects. The temporal magnitudes and surface brightness profiles of several S-L 9 fragments are consistent with tidal dispersal at distances much greater than the classical similar to 2R(J) Roche limit. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP Rettig, TW (reprint author), UNIV NOTRE DAME,DEPT PHYS,NOTRE DAME,IN 46556, USA. RI mumma, michael/I-2764-2013 NR 37 TC 6 Z9 6 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD APR 25 PY 1996 VL 101 IS E4 BP 9271 EP 9281 DI 10.1029/96JE00520 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UG926 UT WOS:A1996UG92600007 ER PT J AU Koch, D Borucki, W Cullers, K Dunham, E Webster, L Miers, T Reitsema, H AF Koch, D Borucki, W Cullers, K Dunham, E Webster, L Miers, T Reitsema, H TI System design of a mission to detect Earth-sized planets in the inner orbits of solar-like stars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID VARIABILITY; EVOLUTION AB A point design for a mission to detect Earth-sized planets in the inner orbits of solar-like stars is described. The observing technique is based upon continuously and simultaneously monitoring 5000 solar-like stars for brightness changes that would be caused by planets transiting their star. Detection of periodic transits of the same amplitude and duration provides for a robust method of discovery. The instrument would consist of a 1-m Schmidt telescope with an array of charge-coupled devices (CCDs) filling the 12 degrees field of view. The instrument would be placed in a halo orbit about the L2 Lagrange point, where its viewing would not be obscured at any time by the Sun, Earth, or Moon. C1 BALL AEROSP SYST GRP,BOULDER,CO 80306. RP Koch, D (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 14 TC 10 Z9 10 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD APR 25 PY 1996 VL 101 IS E4 BP 9297 EP 9302 DI 10.1029/96JE00468 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UG926 UT WOS:A1996UG92600011 ER PT J AU Ohashi, T Ebisawa, K Fukazawa, Y Hiyoshi, K Horii, M Ikebe, Y Ikeda, H Inoue, H Ishida, M Ishisaki, Y Ishizuka, T Kamijo, S Kaneda, H Kohmura, Y Makishima, K Mihara, T Tashiro, M Murakami, T Shoumura, R Tanaka, Y Ueda, Y Taguchi, K Tsuru, T Takeshima, T AF Ohashi, T Ebisawa, K Fukazawa, Y Hiyoshi, K Horii, M Ikebe, Y Ikeda, H Inoue, H Ishida, M Ishisaki, Y Ishizuka, T Kamijo, S Kaneda, H Kohmura, Y Makishima, K Mihara, T Tashiro, M Murakami, T Shoumura, R Tanaka, Y Ueda, Y Taguchi, K Tsuru, T Takeshima, T TI The gas imaging spectrometer on board ASCA SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Article DE instruments; spacecraft; spectroscopy; X-rays, general; X-rays, spectra ID SCINTILLATION PROPORTIONAL-COUNTERS; SATELLITE; GINGA; TENMA AB The Gas Imaging Spectrometer (GIS) system on board ASCA is described. The experiment consists of 2 units of imaging gas scintillation proportional counters with a sealed-off gas cell equipped with an imaging phototube. The performance is characterized by the high X-ray sensitivity (from 0.7 keV to over 10 keV), good energy resolution (7.8% FWHM at 6 keV following E(-0.5) as a function of X-ray energy E), moderate position resolution (0.5 mm FWHM at 6 keV with E(-0.5) dependence), fast time resolution down to 61 mu s, and an effective area of 50 mm diameter. The on-board signal processing system and the data transmitted to the ground are also described. The background rejection efficiency of the GIS is reaching the level achieved by the non-imaging multi-cell proportional counters. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UNIV TOKYO, DEPT PHYS, BUNKYO KU, TOKYO 113, JAPAN. MEISEI ELECT CO, IBARAKI, OSAKA 30101, JAPAN. INST PHYS & CHEM RES, WAKO, SAITAMA 351, JAPAN. JAPAN RADIO CO, KAMIFUKUOKA, SAITAMA 356, JAPAN. INST SPACE & ASTRONAUT SCI, SAGAMIHARA, KANAGAWA 229, JAPAN. FUJITSU LTD, NAKAHARA KU, KAWASAKI, KANAGAWA 221, JAPAN. MAX PLANCK INST EXTRATERR PHYS, W-8046 GARCHING, GERMANY. KYOTO UNIV, DEPT PHYS, SAKYO KU, KYOTO 60601, JAPAN. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP TOKYO METROPOLITAN UNIV, DEPT PHYS, 1-1 MINAMI OHSAWA, HACHIOJI, TOKYO 19203, JAPAN. RI Kohmura, Yoshiki/A-9967-2016; Mihara, Tatehiro/C-5536-2017 OI Kohmura, Yoshiki/0000-0001-5182-063X; Mihara, Tatehiro/0000-0002-6337-7943 NR 15 TC 286 Z9 286 U1 0 U2 3 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0004-6264 EI 2053-051X J9 PUBL ASTRON SOC JPN JI Publ. Astron. Soc. Jpn. PD APR 25 PY 1996 VL 48 IS 2 BP 157 EP + DI 10.1093/pasj/48.2.157 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ292 UT WOS:A1996UJ29200003 ER PT J AU Makishima, K Tashiro, M Ebisawa, K Ezawa, H Fukazawa, Y Gunji, S Hirayama, M Idesawa, E Ikebe, Y Ishida, M Ishisaki, Y Iyomoto, N Kamae, T Kaneda, H Kikuchi, K Kohmura, Y Kubo, H Matsushita, K Matsuzaki, K Mihara, T Nakagawa, K Ohashi, T Saito, Y Sekimoto, Y Takahashi, T Tamura, T Tsuru, T Ueda, Y Yamasaki, NY AF Makishima, K Tashiro, M Ebisawa, K Ezawa, H Fukazawa, Y Gunji, S Hirayama, M Idesawa, E Ikebe, Y Ishida, M Ishisaki, Y Iyomoto, N Kamae, T Kaneda, H Kikuchi, K Kohmura, Y Kubo, H Matsushita, K Matsuzaki, K Mihara, T Nakagawa, K Ohashi, T Saito, Y Sekimoto, Y Takahashi, T Tamura, T Tsuru, T Ueda, Y Yamasaki, NY TI In-orbit performance of the gas imaging spectrometer onboard ASCA SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Article DE instruments, detectors; ISM, individual objects (Crab Nebula); X-rays, background; X-rays, general ID GINGA AB The in-orbit performance and calibration of the Gas Imaging Spectrometer (GIS), located on the focal plane of the X-ray astronomy satellite ASCA, are described. An extensive in-orbit calibration has confirmed its basic performance, including a position resolution of 0.6 mm (FWHM) and an energy resolution of 7.8% (FWHM), both at 6 keV. When combined with the X-ray telescope, the GIS sensitivity range becomes 0.7-10 keV. The in-orbit non X-ray background of the GIS has been confirmed to be as low as (5-9) x 10(-4) cs(-1) cm(-2) keV(-1) over the 1-10 keV range. The long-term detector gain has been stable within a few ro for nearly 3 years. Extensive observations of the Crab Nebula and other sources have provided accurate calibrations of the position response, photometric capability, dead time, and timing accuracy of the GIS. Furthermore, the overall energy response, including the temporal and positional gain variations and the absolute gain scale, has been calibrated to similar to 1%. Thus, the GIS is working as an all-round cosmic X-ray detector, capable of X-ray imagery, fine X-ray spectroscopy, X-ray photometry With a flux dynamic range covering more than 5 orders of magnitude, and fast X-ray photometry with a time resolution up to 60 mu s. C1 NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. YAMAGATA UNIV, FAC SCI, YAMAGATA 990, JAPAN. INST SPACE & ASTRONAUT SCI, SAGAMIHARA, KANAGAWA 229, JAPAN. INST PHYS & CHEM RES, WAKO, SAITAMA 35101, JAPAN. TOKYO METROPOLITAN UNIV, DEPT PHYS, HACHIOJI, TOKYO 19203, JAPAN. KYOTO UNIV, DEPT PHYS, SAKYO KU, KYOTO 60601, JAPAN. RP UNIV TOKYO, DEPT PHYS, BUNKYO KU, TOKYO 113, JAPAN. RI Yamasaki, Noriko/C-2252-2008; Kikuchi, Kenichi/H-3382-2011; Tashiro, Makoto/J-4562-2012; Kohmura, Yoshiki/A-9967-2016; Mihara, Tatehiro/C-5536-2017 OI Kikuchi, Kenichi/0000-0002-2088-0717; Kohmura, Yoshiki/0000-0001-5182-063X; Mihara, Tatehiro/0000-0002-6337-7943 NR 18 TC 227 Z9 227 U1 0 U2 2 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0004-6264 EI 2053-051X J9 PUBL ASTRON SOC JPN JI Publ. Astron. Soc. Jpn. PD APR 25 PY 1996 VL 48 IS 2 BP 171 EP 189 DI 10.1093/pasj/48.2.171 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ292 UT WOS:A1996UJ29200004 ER PT J AU Matsumoto, H Koyama, K Awaki, H Tomida, H Tsuru, T Mushotzky, R Hatsukade, I AF Matsumoto, H Koyama, K Awaki, H Tomida, H Tsuru, T Mushotzky, R Hatsukade, I TI Discovery of an abundance gradient in the central region of the Virgo cluster SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Article DE clusters of galaxies, individual (Virgo); clusters of galaxies, intracluster medium; clusters of galaxies, X-rays; galaxies, individual (M87); galaxies, intergalactic medium; galaxies, structure; X-rays, spectra ID X-RAY OBSERVATIONS; HOT PLASMA; M87; HALO; MASS; GAS AB We present the ASCA results of spatially resolved X-ray spectra in the central regions of the Virgo cluster, near to the central elliptical galaxy M87 and 40' northwest of M87 (M87 NW). Since the spectra of the M87 region is complex, an adequate fit requires at least two thin thermal-plasma components. The temperatures of the hot and cool components are approximately 3.0 and 1.3 keV, respectively, and the temperature of these components are both nearly constant over the central 10' radius from the center of M87. The spectrum of M87 NW, on the other hand, can be well fitted by a single thin thermal-plasma model of similar to 2.7 keV temperature. The abundances of Fe, Si, and S rise towards the center of M87, though the ratios of Si/Fe and S/Si remain constant. We also found, contrary to the Einstein Observatory's results, that the abundance ratio of oxygen to iron (O/Fe) is smaller than the solar value. C1 NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. MIYAZAKI UNIV, FAC ENGN, MIYAZAKI 88921, JAPAN. RP KYOTO UNIV, FAC SCI, DEPT PHYS, SAKYO KU, KYOTO 60601, JAPAN. NR 34 TC 66 Z9 66 U1 0 U2 0 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0004-6264 EI 2053-051X J9 PUBL ASTRON SOC JPN JI Publ. Astron. Soc. Jpn. PD APR 25 PY 1996 VL 48 IS 2 BP 201 EP 210 DI 10.1093/pasj/48.2.201 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ292 UT WOS:A1996UJ29200006 ER PT J AU Ishisaki, Y Makishima, K Iyomoto, N Hayashida, K Inoue, H Mitsuda, K Tanaka, Y Uno, S Kohmura, Y Mushotzky, RF Petre, R Serlemitsos, PJ Terashima, Y AF Ishisaki, Y Makishima, K Iyomoto, N Hayashida, K Inoue, H Mitsuda, K Tanaka, Y Uno, S Kohmura, Y Mushotzky, RF Petre, R Serlemitsos, PJ Terashima, Y TI X-ray properties of the nucleus of M81 SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Article DE galaxies, active; galaxies, individual (M81); galaxies, X-rays ID ACTIVE GALACTIC NUCLEI; SEYFERT-GALAXIES; EMISSION-LINES; VARIABILITY; SPECTRUM AB Due to the appearance of SN 1993J, the region of M81 (NGC 3031) was observed with ASCA ten times between 1993 April and 1995 April. Data from eight of these observations have been used to study the 0.5-10 keV spectral and temporal properties of the source designated X-5, coincident with the M81 nucleus. The 2-10 keV luminosity of X-5 varied by a factor of 1.7 over a period of two years, around a mean of similar to 2 x 10(40) erg s(-1). Variations by similar to 20% on a time scale of one day Mere also detected. The average spectrum of X-5 can be represented in the 2-10 keV range by a power-law continuum of the photon index, Gamma = 1.85 +/- 0.04, and a relatively low intrinsic absorption column of N-H similar to 1 x 10(21) cm(-2). In the soft (< 2 keV) energy range, an additional thermal component with a temperature of 0.6-0.8 keV has been detected. An apparently broad or complex Fe-K emission line centered at 6.6-6.7 keV was also detected at an equivalent width of 170 +/- 60 eV. These results indicate that the M81 nucleus is a low-luminosity active galactic nucleus, and suggest that similar objects are relatively numerous. A comparison is made between the nucleus of M81 and those of Seyfert galaxies. C1 OSAKA UNIV, DEPT EARTH & SPACE SCI, TOYONAKA, OSAKA 560, JAPAN. INST SPACE & ASTRONAUT SCI, SAGAMIHARA, KANAGAWA 229, JAPAN. INST PHYS & CHEM RES, WAKO, SAITAMA 35101, JAPAN. NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY PHYS LAB, GREENBELT, MD 20771 USA. NAGOYA UNIV, DEPT ASTROPHYS, CHIKUSA KU, NAGOYA, AICHI 46401, JAPAN. RP UNIV TOKYO, SCH SCI, DEPT PHYS, BUNKYO KU, TOKYO 113, JAPAN. RI Mitsuda, Kazuhisa/C-2649-2008; Kohmura, Yoshiki/A-9967-2016 OI Kohmura, Yoshiki/0000-0001-5182-063X NR 66 TC 93 Z9 94 U1 0 U2 0 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0004-6264 EI 2053-051X J9 PUBL ASTRON SOC JPN JI Publ. Astron. Soc. Jpn. PD APR 25 PY 1996 VL 48 IS 2 BP 237 EP 248 DI 10.1093/pasj/48.2.237 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ292 UT WOS:A1996UJ29200010 ER PT J AU Koyama, K Maeda, Y Sonobe, T Takeshima, T Tanaka, Y Yamauchi, S AF Koyama, K Maeda, Y Sonobe, T Takeshima, T Tanaka, Y Yamauchi, S TI ASCA view of our galactic center: Remains of past activities in X-rays? SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Article DE galaxies, Milky Way; interstellar, clouds; X-rays, sources; X-rays, spectra ID IRON LINE; EMISSION AB Detailed X-ray images and spectra of the galactic-center region up to 10 keV were obtained with ASCA. Diffuse thermal-emission with distinct K alpha lines from highly ionized ions of various elements has confirmed the presence of an extended high-temperature plasma. The fluorescent X-ray emission from cold iron atoms in molecular clouds was also found, possibly due to irradiation by X-rays from the center, which was bright in the past, but is presently dim. The results suggest that the galactic center exhibited intermittent activities with a time-averaged energy generation rate comparable to Seyfert nuclei, a class of active galactic nuclei. C1 INST SPACE & ASTRONAUT SCI, SAGAMIHARA, KANAGAWA 229, JAPAN. NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. MAX PLANCK INST EXTRATERR PHYS, D-85748 GARCHING, GERMANY. IWATE UNIV, COLL HUMANITIES & SOCIAL SCI, MORIOKA, IWATE 020, JAPAN. RP KYOTO UNIV, DEPT PHYS, SAKYO KU, KYOTO 60601, JAPAN. NR 25 TC 320 Z9 321 U1 0 U2 1 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0004-6264 EI 2053-051X J9 PUBL ASTRON SOC JPN JI Publ. Astron. Soc. Jpn. PD APR 25 PY 1996 VL 48 IS 2 BP 249 EP + DI 10.1093/pasj/48.2.249 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ292 UT WOS:A1996UJ29200011 ER PT J AU Murakami, T Shibata, R Ogasaka, Y Yoshida, A Hurley, K Li, P Kouveliotou, C Fishman, GJ AF Murakami, T Shibata, R Ogasaka, Y Yoshida, A Hurley, K Li, P Kouveliotou, C Fishman, GJ TI ASCA observation of a possible X-ray counterpart of the 1992 May 1 gamma-ray burst SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Letter DE galaxies, X-rays; Gamma rays; stars, individual (GRB 920501); X-rays, spectra AB A probable X-ray counterpart of the 1992 May 1 gamma-ray burst was observed with ASCA. This burst was first observed with the 3rd interplanetary network, which consisted of BATSE, Ulysses, and PVO, and was localized to a small error box. Then, 18 days after the burst, ROSAT discovered a weak X-ray source in the error box, and later ROSAT HRT. and PSPC observations determined the spectrum and refined the position. ASCA observed this source on 1995 April 10. Its 0.5-10.0 keV spectrum appears to be hard, and is heavily absorbed at low energies. The amount of absorption is consistent with the galactic hydrogen column density in this direction. This suggests that the X-ray source is quite distant, and might not be a field star or a supernova remnant in the galactic disk. Recently, IR observations at KECK found a galaxy in the error box, which seems to be consistent with the ASCA results. C1 INST PHYS & CHEM RES, WAKO, SAITAMA 35101, JAPAN. UNIV CALIF BERKELEY, SPACE SCI LAB, BERKELEY, CA 94720 USA. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. RP INST SPACE & ASTRONAUT SCI, 3-1-1 YOSHINODAI, SAGAMIHARA, KANAGAWA 229, JAPAN. NR 26 TC 4 Z9 4 U1 0 U2 0 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0004-6264 EI 2053-051X J9 PUBL ASTRON SOC JPN JI Publ. Astron. Soc. Jpn. PD APR 25 PY 1996 VL 48 IS 2 BP L9 EP L14 DI 10.1093/pasj/48.2.L9 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UJ292 UT WOS:A1996UJ29200001 ER PT J AU Mitchell, JW Barbier, LM Christian, ER Krizmanic, JF Krombel, K Ormes, JF Streitmatter, RE Labrador, AW Davis, AJ Mewaldt, RA Schindler, SM Golden, RL Stochaj, SJ Webber, WR Menn, W Hof, M Reimer, O Simon, M Rasmussen, IL AF Mitchell, JW Barbier, LM Christian, ER Krizmanic, JF Krombel, K Ormes, JF Streitmatter, RE Labrador, AW Davis, AJ Mewaldt, RA Schindler, SM Golden, RL Stochaj, SJ Webber, WR Menn, W Hof, M Reimer, O Simon, M Rasmussen, IL TI Measurement of 0.25-3.2 GeV antiprotons in the cosmic radiation SO PHYSICAL REVIEW LETTERS LA English DT Article ID PROTON RATIO; RAY; SPECTROMETER; MODULATION AB The balloon-borne Isotope Matter-Antimatter Experiment (IMAX) was flown from Lynn Lake, Manitoba, Canada on 16-17 July 1992. Using velocity and magnetic rigidity to determine mass, we have directly measured the abundances of cosmic ray antiprotons and protons in the energy range from 0.25 to 3.2 GeV. Both the absolute flux of antiprotons and the antiproton/proton ratio are consistent with recent theoretical work in which antiprotons are produced as secondary products of cosmic ray interactions with the interstellar medium. This consistency implies a lower limit to the antiproton lifetime of similar to 10(7) yr. C1 CALTECH, PASADENA, CA 91125 USA. NEW MEXICO STATE UNIV, LAS CRUCES, NM 88003 USA. UNIV SIEGEN, D-57068 SIEGEN, GERMANY. DANISH SPACE RES INST, DK-2800 LYNGBY, DENMARK. RP Mitchell, JW (reprint author), NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RI Christian, Eric/D-4974-2012; Reimer, Olaf/A-3117-2013 OI Christian, Eric/0000-0003-2134-3937; Reimer, Olaf/0000-0001-6953-1385 NR 34 TC 113 Z9 113 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD APR 22 PY 1996 VL 76 IS 17 BP 3057 EP 3060 DI 10.1103/PhysRevLett.76.3057 PG 4 WC Physics, Multidisciplinary SC Physics GA UF744 UT WOS:A1996UF74400004 ER PT J AU Rothermel, J Chambers, DM Jarzembski, MA Srivastava, V Bowdle, DA Jones, WD AF Rothermel, J Chambers, DM Jarzembski, MA Srivastava, V Bowdle, DA Jones, WD TI Signal processing and calibration of continuous-wave focused CO2 Doppler lidars for atmospheric backscatter measurement SO APPLIED OPTICS LA English DT Article ID AEROSOL BACKSCATTER; AIRBORNE; SYSTEMS AB Two continuous-wave (CW) focused CO2 Doppler lidars (9.1 and 10.6 mu m) were developed for airborne in situ aerosol backscatter measurements. The complex path of reliably calibrating these systems, with different signal processors, for accurate derivation of atmospheric backscatter coefficients is documented. Lidar calibration for absolute backscatter measurement for both lidars is based on range response over the lidar sample volume, not solely at focus. Both lidars were calibrated with a new technique using well-characterized aerosols as radiometric standard targets and related to conventional hard-target calibration. A digital signal processor (DSP), a surface acoustic wave spectrum analyzer, and manually tuned spectrum analyzer signal analyzers were used. The DSP signals were analyzed with an innovative method or correcting for systematic noise fluctuation; the noise statistics exhibit the chi-square distribution predicted by theory. System parametric studies and detailed calibration improved the accuracy of conversion from the measured signal-to-noise ratio to absolute backscatter. The minimum backscatter sensitivity is similar to 3 x 10(-12) m(-1) sr(-1) at 9.1 mu m and similar to 9 x 10(-12) m(-1) sr(-1) at 10.6 mu m. Sample measurements are shown for a flight over the remote Pacific Ocean in 1990 as part of the NASA Global Backscatter Experiment (GLOBE) survey missions, the first time to our knowledge that 9.1-10.6-mu m lidar intercomparisons were made. Measurements at 9.1 mu m, a potential wavelength for space-based lidar remote-sensing applications, are to our knowledge the first based on the rare isotope C-12 O-18(2) gas. (C) 1996 Optical Society of America C1 MICROCRAFT INC,HUNTSVILLE,AL 35806. UNIV SPACE RES ASSOC,GLOBAL HYDROL & CLIMATE CTR,INST GLOBAL CHANGE RES & EDUC,HUNTSVILLE,AL 35895. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,OPT & RADIO FREQUENCY DIV,HUNTSVILLE,AL 35812. RP Rothermel, J (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,GLOBAL HYDROL & CLIMATE CTR,EARTH SYST SCI DIV,HUNTSVILLE,AL 35806, USA. NR 24 TC 14 Z9 14 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD APR 20 PY 1996 VL 35 IS 12 BP 2083 EP 2095 DI 10.1364/AO.35.002083 PG 13 WC Optics SC Optics GA UF393 UT WOS:A1996UF39300021 PM 21085337 ER PT J AU Jarzembski, MA Srivastava, V Chambers, DM AF Jarzembski, MA Srivastava, V Chambers, DM TI Lidar calibration technique using laboratory-generated aerosols SO APPLIED OPTICS LA English DT Article DE lidar; coherent detection; backscatter ID COHERENT LASER-RADAR; COLORADO HIGH-PLAINS; CO2 DOPPLER LIDARS; BACKSCATTER MEASUREMENTS; 10.6 MICROMETERS; AIRBORNE; PERFORMANCE AB A new calibration technique for continuous-wave Doppler lidars that uses an aerosol scattering target has been developed. Calibrations with both single- and many-particle scattering were performed at the same lidar operating conditions as in atmospheric measurements. The calibrating targets, simulating atmospheric aerosols, were laboratory-generated spherical silicone oil droplets with known complex refractive indices and sizes, hence with known single-particle backscatter cross sections as obtained from Mie theory. Measurements of lidar efficiency with the conventional hard target calibration method were consistently higher by a factor of similar to 2 than measurements with the aerosol calibration technique. This result may have important implications for lidar backscatter estimates both for aerosol modeling efforts and for optimal design of future lidar systems. The aerosol calibration method provides a validation of basic lidar theory for particle scattering for coherent detection. (C) 1996 Optical Society of America C1 UNIV SPACE RES ASSOC,GLOBAL HYDROL & CLIMATE CTR,INST GLOBAL CHANGE RES & EDUC,HUNTSVILLE,AL 35806. MICROCRAFT INC,HUNTSVILLE,AL 35806. RP Jarzembski, MA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,GLOBAL HYDROL & CLIMATE CTR,922 EXPLORER BLVD,HUNTSVILLE,AL 35806, USA. NR 30 TC 17 Z9 17 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD APR 20 PY 1996 VL 35 IS 12 BP 2096 EP 2108 DI 10.1364/AO.35.002096 PG 13 WC Optics SC Optics GA UF393 UT WOS:A1996UF39300022 PM 21085338 ER PT J AU Michalitsianos, AG Oliversen, RJ Nichols, J AF Michalitsianos, AG Oliversen, RJ Nichols, J TI Detection of O VI lambda 1033 emission and far-ultraviolet spectral variability in the gravitational lens PG 1115+080 SO ASTROPHYSICAL JOURNAL LA English DT Article DE gravitational lensing; quasars, emission lines; quasars, individual (PG 1115+080); ultraviolet, galaxies ID QSO PG1115+08; ABSORPTION; EVOLUTION; QUASARS AB Far-UV spectra acquired with the International Ultraviolet Explorer (IUE) of the gravitational lens PG 1115+080 and processed with the NEWSIPS software show the presence of prominent O VI lambda 1033 resonance line emission that is superimposed on strong far-UV continuum between 900 and 1100 Angstrom (in the z(QSO) = 1.722 rest frame). A comparison of these spectra with an IUE Archive spectrum of PG 1115+080 indicates that O VI emission was not present in 1978, when the only other spectrum covering this wavelength range was obtained, which showed only far-UV continuum. The detection of O VI lambda 1033 resonance line emission in the brightest component, PG 1115+080A, suggests a high state of ionization in the broad emission line region (BELR). O VI emission is accompanied by absorption in the line core and complex absorption features that truncate the blue wing of the emission profile. The O VI absorption trough suggests outflow that is characteristic of high-ionization resonance lines in broad absorption line (BAL) quasars. Both the O VI emission and BAL absorption decreased significantly in strength relative to the continuum over a timescale of similar to 100 days. The equivalent widths of absorption features within the O VI BAL trough also changed on timescales of roughly weeks down to similar to 1 day. Rapid variations associated with absorption features may reflect ionization changes that cause column densities in the BAL outflow to fluctuate. These results emphasize the importance of monitoring emission lines of very high ionization (> 100 eV) because the timescale over which O VI changes occur is comparable to the gravitational delay time of similar to 2-3 months estimated for images in PG 1115+080. C1 NASA,GODDARD SPACE FLIGHT CTR,IUE OBSERV,COMP SCI CORP,GREENBELT,MD 20771. RP Michalitsianos, AG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 26 TC 17 Z9 17 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1996 VL 461 IS 2 BP 593 EP & DI 10.1086/177087 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UE570 UT WOS:A1996UE57000011 ER EF