FN Thomson Reuters Web of Science™ VR 1.0 PT J AU Bozzolo, G Mosca, HO Wilson, AW Noebe, RD Garces, JE AF Bozzolo, G Mosca, HO Wilson, AW Noebe, RD Garces, JE TI Atomistic modeling of quaternary alloys: Ti and Cu in NiAl SO METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE LA English DT Article ID SITE-OCCUPANCIES; GENERAL FORMULATION; ALCHEMI; METALS; IRON AB The change in site preference in NiAl(Ti,Cu) alloys with concentration is examined experimentally via ALCHEMI and theoretically using the Bozzolo-Ferrante-Smith (BFS) method for alloys. Results for the site occupancy of Ti and Cu additions as a function of concentration are determined experimentally for five alloys. These results are reproduced with large-scale BFS-based Monte Carlo atomistic simulations. The original set of five alloys is extended to 25 concentrations, which are modeled by means of the BFS method for alloys, showing in more detail the compositional range over which major changes in behavior occur. A simple but powerful approach based on the definition of atomic local environments also is introduced to describe energetically the interactions between the various elements and therefore to explain the observed behavior. C1 Ohio Aerosp Inst, Cleveland, OH 44142 USA. Comis Nacl Energia Atom, RA-1063 Buenos Aires, DF, Argentina. Boeing Co, Los Angeles, CA 90009 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Ctr Atom Bariloche, RA-8400 San Carlos De Bariloche, Rio Negro, Argentina. RP Bozzolo, G (reprint author), Ohio Aerosp Inst, Cleveland, OH 44142 USA. NR 21 TC 11 Z9 11 U1 0 U2 0 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 184 THORN HILL RD, WARRENDALE, PA 15086 USA SN 1073-5615 J9 METALL MATER TRANS B JI Metall. Mater. Trans. B-Proc. Metall. Mater. Proc. Sci. PD APR PY 2002 VL 33 IS 2 BP 265 EP 284 DI 10.1007/s11663-002-0011-8 PG 20 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA 538LG UT WOS:000174817000011 ER PT J AU Horz, F Mittlefehldt, DW See, TH Galindo, C AF Horz, F Mittlefehldt, DW See, TH Galindo, C TI Petrographic studies of the impact melts from Meteor Crater, Arizona, USA SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID SHOCK METAMORPHISM; BRECCIA; SUEVITE; ROCKS; MODEL; MARS; RIES AB We investigated the ballistically dispersed melts from Meteor Crater, Arizona, USA to determine the stratigraphic extent of its melt zone from the compositional relationship of melts and target rocks. Most melt particles are crystallized, hydrated, and oxidized; pristine glasses are rare. Hydration and oxidation occurred at ambient temperatures long after the impact. The preserved glasses are generally clear and texturally homogeneous, but unlike typical impact melts, they have unusually heterogeneous compositions, both within individual particles and from sample to sample. For example, the average SiO2 for individual particles ranges from 43 to 65%. The projectile content is unusually high and it is distributed bimodally, with specific samples containing either 5-10% or 20-30% FeO. These compositional heterogeneities most likely reflect the high carbonate content of the target rocks and the release Of Copious CO2 that dispersed the melts, thereby terminating melt flow and mixing. The high projectile content and the CO2 depleted residue of purely sedimentary rocks produced mafic melts that crystallized fine-grained olivine and pyroxene. The melts fall into three compositional groups reflecting variable proportions of the major target formations, Moenkopi, Kaibab, and Coconino. Least-square mixing calculations revealed one group to contain 55% Moenkopi, 40% quartz-rich, upper Kaibab, and 5% meteorite, suggesting a source depth of <30 in from the pre-impact surface. The other two melt groups have higher contents of meteorite (15-20%) and Kaibab (50-70%) and contain more SiO2 than average Kaibab. The additional quartz may have been derived from Coconino or the upper Kaibab, implying melt depths >90 m or <30 m, respectively. Additional studies, especially hydrocode calculations, are needed to better understand the source depth of these melts and their exceptionally high projectile content. C1 NASA, Lyndon B Johnson Space Ctr, Planetary Sci Branch, Houston, TX 77058 USA. Lockheed Martin ESC, Houston, TX 77058 USA. Hernandez Engn Inc, Houston, TX 77062 USA. RP Horz, F (reprint author), NASA, Lyndon B Johnson Space Ctr, Planetary Sci Branch, SN2, Houston, TX 77058 USA. NR 64 TC 36 Z9 36 U1 1 U2 4 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD APR PY 2002 VL 37 IS 4 BP 501 EP 531 PG 31 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 568HV UT WOS:000176537100005 ER PT J AU Gaucher, EA Das, UK Miyamoto, MM Benner, SA AF Gaucher, EA Das, UK Miyamoto, MM Benner, SA TI The crystal structure of eEF1A refines the functional predictions of an evolutionary analysis of rate changes among elongation factors SO MOLECULAR BIOLOGY AND EVOLUTION LA English DT Letter DE tertiary structures; protein function; evolutionary rates; rate changes; covarions; elongation factors ID TRANSFER-RNA; FACTOR 1-ALPHA; VARIABILITY; DIVERGENCE; RIBOSOME; COMPLEX; PROTEIN; GENE; TU C1 Univ Florida, Dept Chem, NASA Astrobiol Inst, Gainesville, FL 32611 USA. Univ Florida, Dept Zool, Gainesville, FL 32611 USA. RP Gaucher, EA (reprint author), Univ Florida, Dept Chem, NASA Astrobiol Inst, 440 Leigh Hall, Gainesville, FL 32611 USA. RI Gaucher, Eric/I-7313-2013 NR 25 TC 20 Z9 20 U1 0 U2 1 PU SOC MOLECULAR BIOLOGY EVOLUTION PI LAWRENCE PA PO BOX 1897, LAWRENCE, KS 66044-8897 USA SN 0737-4038 J9 MOL BIOL EVOL JI Mol. Biol. Evol. PD APR PY 2002 VL 19 IS 4 BP 569 EP 573 PG 5 WC Biochemistry & Molecular Biology; Evolutionary Biology; Genetics & Heredity SC Biochemistry & Molecular Biology; Evolutionary Biology; Genetics & Heredity GA 541CE UT WOS:000174967000022 PM 11919299 ER PT J AU Bauschlicher, CW So, CR AF Bauschlicher, CW So, CR TI High coverages of hydrogen on (10,0), (9,0) and (5,5) carbon nanotubes SO NANO LETTERS LA English DT Article ID GEOMETRY OPTIMIZATION; MOLECULAR MECHANICS; ADSORPTION; ENERGY AB The binding energies of H to (9,0) and (5,5) carbon nanotubes are calculated for 50 and 100% coverages using the AM1 and/or ONIOM approaches. These results are compared to our previous results for hydrogen on the outside of a (10,0) tube. The average C-H binding energies for the optimal pattern are similar for all three tubes. For the (10,0) tube, 100% hydrogen coverage, with 50% on the inside and 50% on outside of the tube, is studied. The average C-H bond energy for this configuration is significantly larger than for hydrogen only on the outside at either 50% or 100% coverage. C1 NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, Space Technol Div, Mail Stop 230-3, Moffett Field, CA 94035 USA. OI So, Christopher/0000-0001-7572-778X NR 20 TC 57 Z9 59 U1 1 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1530-6984 J9 NANO LETT JI Nano Lett. PD APR PY 2002 VL 2 IS 4 BP 337 EP 341 DI 10.1021/nl020283o PG 5 WC Chemistry, Multidisciplinary; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Chemistry; Science & Technology - Other Topics; Materials Science; Physics GA 542KF UT WOS:000175041800017 ER PT J AU Zhao, JJ Buldum, A Han, J Lu, JP AF Zhao, JJ Buldum, A Han, J Lu, JP TI Gas molecule adsorption in carbon nanotubes and nanotube bundles SO NANOTECHNOLOGY LA English DT Article ID HYDROGEN ADSORPTION; FIELD-EMISSION; ELECTRONIC-PROPERTIES; STORAGE; ENERGY; SIMULATIONS; ARRAYS AB We studied various gas molecules (NO2, O-2, NH3, N-2, CO2, CH4, H2O, H-2, Ar) on single-walled carbon nanotubes (SWNTs) and bundles using first principles methods. The equilibrium position, adsorption energy, charge transfer, and electronic band structures are obtained for different kinds of SWNTs. Most molecules adsorb weakly on SWNTs and can be either charge donors or acceptors to the nanotubes. We find that the gas adsorption on the bundle interstitial and groove sites is stronger than that on individual nanotubes. The electronic properties of SWNTs are sensitive to the adsorption of certain gases such as NO2 and O-2. Charge transfer and gas-induced charge fluctuation might significantly affect the tran,;port properties of SWNTs. Our theoretical results are consistent with recent experiments. C1 Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA. NASA, Ames Res Ctr, Eloret Corp, Santa Clara, CA 95051 USA. RP Zhao, JJ (reprint author), Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA. RI Zhao, Jijun/I-6030-2015 NR 29 TC 794 Z9 814 U1 16 U2 153 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0957-4484 J9 NANOTECHNOLOGY JI Nanotechnology PD APR PY 2002 VL 13 IS 2 BP 195 EP 200 AR PII S0957-4484(02)30254-X DI 10.1088/0957-4484/13/2/312 PG 6 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied SC Science & Technology - Other Topics; Materials Science; Physics GA 550JA UT WOS:000175498800014 ER PT J AU Kennerley, SW Diedrichsen, J Hazeltine, E Semjen, A Ivry, RB AF Kennerley, SW Diedrichsen, J Hazeltine, E Semjen, A Ivry, RB TI Callosotomy patients exhibit temporal uncoupling during continuous bimanual movements SO NATURE NEUROSCIENCE LA English DT Article ID COORDINATION; DIRECTION; DYNAMICS AB Rhythmic bimanual movements are highly constrained in the temporal domain, with the gestures of the two hands tightly synchronized. Previous studies have implicated a subcortical locus for temporal coupling based on the observation that these constraints persist in callosotomy patients. We now report that such coupling is restricted to movements entailing a discrete event (such as a movement onset). Three callosotomy patients exhibited a striking lack of temporal coupling during continuous movements, with the two hands oscillating at non-identical frequencies. We propose a subcortical locus of temporal coupling for movements involving discrete events. In contrast, synchronization between the hands during continuous movements depends on interhemispheric transmission across the corpus callosum. C1 Univ Calif Berkeley, Berkeley, CA 94720 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. CNRS, Ctr Rech Neurosci Cognit, F-13402 Marseille, France. RP Ivry, RB (reprint author), Univ Calif Berkeley, 3210 Tolman Hall 1650, Berkeley, CA 94720 USA. RI Diedrichsen, Jorn/A-7789-2010; OI Diedrichsen, Jorn/0000-0003-0264-8532; Hazeltine, Richard/0000-0002-0893-5789 FU NINDS NIH HHS [P50 NS17778, R01 NS30256] NR 32 TC 117 Z9 119 U1 1 U2 5 PU NATURE AMERICA INC PI NEW YORK PA 345 PARK AVE SOUTH, NEW YORK, NY 10010-1707 USA SN 1097-6256 J9 NAT NEUROSCI JI Nat. Neurosci. PD APR PY 2002 VL 5 IS 4 BP 376 EP 381 DI 10.1038/nn822 PG 6 WC Neurosciences SC Neurosciences & Neurology GA 534UQ UT WOS:000174606900019 PM 11914724 ER PT J AU Wertheimer, AC Thedinga, JF Heintz, RA Bradshaw, RF Celewycz, AG AF Wertheimer, AC Thedinga, JF Heintz, RA Bradshaw, RF Celewycz, AG TI Comparative effects of half-length coded wire tagging and ventral fin removal on survival and size of pink salmon fry SO NORTH AMERICAN JOURNAL OF AQUACULTURE LA English DT Article ID ALASKA AB The survival and adult size of pink salmon Oncorhynchus gorbuscha marked as recently emigrating fry with coded ire tags (CWTs) were compared with those of Sibling groups that were either unmarked or marked by removing a ventral (pelvic) fin. Prerelease mortality was significantly higher for coded-wire-tagged fish. Survival from fry release to adult return was equal to or less than that of fish with central fin clips. Pink salmon marked with CWTs were similar in size at return to pink salmon Both ventral fin clips but significantly smaller than unmarked fish. These results indicate that reduced growth after marking contributes to the loader survival reported in other Studies of pink salmon marked with CWTs or fin clips. Marking pink salmon as recently emigrating fry with CWTs provides a powerful tool for differentiating between a large number of treatment groups and categories, but doing so will affect survival and size at return and is more detrimental to survival than central tin removal. C1 Natl Marine Fisheries Serv, Auke Bay Lab, Alaska Fisheries Sci Ctr, Natl Ocean & Atmospher Adm, Juneau, AK 99801 USA. RP Wertheimer, AC (reprint author), Natl Marine Fisheries Serv, Auke Bay Lab, Alaska Fisheries Sci Ctr, Natl Ocean & Atmospher Adm, 11305 Glacier Highway, Juneau, AK 99801 USA. NR 17 TC 10 Z9 11 U1 0 U2 4 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 USA SN 1522-2055 J9 N AM J AQUACULT JI N. Am. J. Aqualcult. PD APR PY 2002 VL 64 IS 2 BP 150 EP 157 DI 10.1577/1548-8454(2002)064<0150:CEOHLC>2.0.CO;2 PG 8 WC Fisheries SC Fisheries GA 541FR UT WOS:000174975000009 ER PT J AU Tai, H Rogowski, R AF Tai, H Rogowski, R TI Optical anisotropy induced by torsion and bending in an optical fiber SO OPTICAL FIBER TECHNOLOGY LA English DT Article AB Optical anisotropy in an optical fiber under the influence of torsion and bending stress is examined. The optical proper-ties of the optical fiber in terms of indices of refraction and principal axes of the optical indicatrix are discussed. The additional bending stress broke the radial symmetry dependence of the optical principal indicatrix imposed by torsion stress alone. Published by Elsevier Science (USA). C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Tai, H (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 11 TC 25 Z9 25 U1 3 U2 6 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 1068-5200 J9 OPT FIBER TECHNOL JI Opt. Fiber Technol. PD APR PY 2002 VL 8 IS 2 BP 162 EP 169 AR PII S1068-5200(02)00006-8 DI 10.1016/S1068-5200(02)00006-8 PG 8 WC Engineering, Electrical & Electronic; Optics; Telecommunications SC Engineering; Optics; Telecommunications GA 574NL UT WOS:000176896400006 ER PT J AU Zhang, NL Chao, DF AF Zhang, NL Chao, DF TI A new laser shadowgraphy method for measurements of dynamic contact angle and simultaneous flow visualization in a sessile drop SO OPTICS AND LASER TECHNOLOGY LA English DT Article DE laser shadowgraphy; contact angle; flow visualization ID LIQUID DROPLETS AB A new laser shadowgraphy method is presented to measure the dynamic contact angle of a sessile drop on a nontransparent metal substrate and simultaneously visualize flow motions inside the drop. A collimated laser beam is refracted into the drop, then reflected on the substrate surface and finally refracted out of the drop to form a shadowgraphic image on a screen. The instant diameters of the refracted-shadowgraphic image, cooperated with the corresponding instant contact-diameters of the drop measured from the magnified top view, are used to determine the instant contact angles of the sessile drop. At the same time, flow motions, if ally, in the drop can be visualized from the refracted-shadowgraphic image, The new method is demonstrated to be a very simple, accurate, and unique optical technique for simultaneous measuring of the dynamic contact angle of a liquid drop spreading oil a nontransparent metal substrate with flow visualization in the drop. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 NASA, Micrograv Sci Div, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Zhang, NL (reprint author), NASA, Micrograv Sci Div, Glenn Res Ctr, 21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 7 TC 8 Z9 9 U1 0 U2 3 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0030-3992 J9 OPT LASER TECHNOL JI Opt. Laser Technol. PD APR PY 2002 VL 34 IS 3 BP 243 EP 248 AR PII S0030-3992(02)00002-6 PG 6 WC Optics; Physics, Applied SC Optics; Physics GA 549KD UT WOS:000175442300011 ER PT J AU Griffin, DW AF Griffin, DW TI Reply to comment on "Phase-shifting shearing interferometer" SO OPTICS LETTERS LA English DT Editorial Material C1 NASA Glenn Res Ctr, Micrograv Fluid Phys Branch, Cleveland, OH 44135 USA. RP Griffin, DW (reprint author), NASA Glenn Res Ctr, Micrograv Fluid Phys Branch, M-S 110-3 21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD APR 1 PY 2002 VL 27 IS 7 BP 511 EP 511 DI 10.1364/OL.27.000511 PG 1 WC Optics SC Optics GA 536HL UT WOS:000174694600015 PM 18007848 ER PT J AU Bandyopadhyay, S Roychowdhury, V Vatan, F AF Bandyopadhyay, S Roychowdhury, V Vatan, F TI Partial recovery of entanglement in bipartite-entanglement transformations SO PHYSICAL REVIEW A LA English DT Article ID MANIPULATION; STATES AB Any deterministic bipartite-entanglement transformation involving finite copies of pure states and carried out using local operations and classical communication (LOCC) results in a net loss of entanglement. We show that for almost all such transformations, partial recovery of lost entanglement is achievable by using 2x2 auxiliary entangled states, no matter how large the dimensions of the parent states are. For the rest of the special cases of deterministic LOCC transformations, we show that the dimension of the auxiliary entangled state depends on the presence of equalities in the majorization relations of the parent states. We show that genuine recovery is still possible using auxiliary states in dimensions less than that of the parent states for all patterns of majorization relations except only one special case. C1 Univ Calif Los Angeles, Dept Elect Engn, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bandyopadhyay, S (reprint author), Univ Calif Los Angeles, Dept Elect Engn, Los Angeles, CA 90095 USA. RI Bandyopadhyay, Somshubhro/A-1652-2015 NR 15 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 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD APR PY 2002 VL 65 IS 4 AR 040303 DI 10.1103/PhysRevB.65.040303 PN A PG 4 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 541HF UT WOS:000174978600005 ER PT J AU Bell, NF Sawyer, RF Volkas, RR Wong, YYY AF Bell, NF Sawyer, RF Volkas, RR Wong, YYY TI Generation of entangled states and error protection from adiabatic avoided level crossings SO PHYSICAL REVIEW A LA English DT Article ID NEUTRINO OSCILLATIONS; QUANTUM; MATTER; DYNAMICS; PARADOX AB We consider the environment-affected dynamics of N self-interacting particles living in one-dimensional double wells. Two topics are dealt with. First, we consider the production of entangled states of two-level systems. We show that by adiabatically varying the well biases, we may dynamically generate maximally entangled states, starting from initially unentangled product states. Entanglement degradation due to a common type of environmental influence is then computed by solving a master equation. However, we also demonstrate that entanglement production is unaffected if the system-environment coupling is of the type that induces "motional narrowing." As our second but related topic, we construct a different master equation that seamlessly merges error protection/detection dynamics for quantum information with the environmental couplings responsible for producing the errors in the first place. Adiabatic avoided crossing schemes are used in both topics. C1 Univ Melbourne, Sch Phys, High Energy Phys Res Ctr, Parkville, Vic 3010, Australia. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. RP Bell, NF (reprint author), Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, POB 500, Batavia, IL 60510 USA. EM n.bell@physics.unimelb.edu.au; sawyer@vulcan.physics.ucsb.edu; r.volkas@physics.unimelb.edu.au; y.wong@physics.unimelb.edu.au NR 25 TC 11 Z9 11 U1 0 U2 1 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD APR PY 2002 VL 65 IS 4 AR 042328 DI 10.1103/PhysRevB.65.042328 PN A PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 541HF UT WOS:000174978600054 ER PT J AU Roland, J Cerf, NJ AF Roland, J Cerf, NJ TI Quantum search by local adiabatic evolution SO PHYSICAL REVIEW A LA English DT Article ID COMPUTATION AB The adiabatic theorem has been recently used to design quantum algorithms of a new kind, where the quantum computer evolves slowly enough so that it remains near its instantaneous ground state, which tends to the solution. We apply this time-dependent Hamiltonian approach to Grover's problem, i.e., searching a marked item in an unstructured database. We find that by adjusting the evolution rate of the Hamiltonian so as to keep the evolution adiabatic on each infinitesimal time interval, the total running time is of order rootN, where N is the number of items in the database. We thus recover the advantage of Grover's standard algorithm as compared to a classical search, scaling as N. This is in contrast with the constant-rate adiabatic approach of Farhi (e-print quant-ph/0001106), where the requirement of adiabaticity is expressed only globally, resulting in a time of order N. C1 Free Univ Brussels, Ecole Polytech, B-1050 Brussels, Belgium. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Roland, J (reprint author), Free Univ Brussels, Ecole Polytech, CP 165, B-1050 Brussels, Belgium. OI Roland, Jeremie/0000-0003-0556-0376 NR 15 TC 217 Z9 218 U1 0 U2 8 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD APR PY 2002 VL 65 IS 4 AR 042308 DI 10.1103/PhysRevB.65.042308 PN A PG 6 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 541HF UT WOS:000174978600034 ER PT J AU McIntosh, SW Charbonneau, P Bogdan, TJ Liu, HL Norman, JP AF McIntosh, SW Charbonneau, P Bogdan, TJ Liu, HL Norman, JP TI Geometrical properties of avalanches in self-organized critical models of solar flares SO PHYSICAL REVIEW E LA English DT Article ID QUIET-SUN; ENERGY-DISTRIBUTION; TIME VARIABILITY; NANOFLARES; CORONA; MICROFLARES; DIAGNOSTICS; REGIONS; FIELDS; TRACE AB We investigate the geometrical properties of avalanches in self-organized critical models of solar flares. Traditionally, such models differ from the classical sandpile model in their formulation of stability criteria in terms of the curvature of the nodal field, and belong to a distinct universality class. With a view toward comparing these properties to those inferred from spatially and temporally resolved flare observations, we consider the properties of avalanche peak snapshots, time-integrated avalanches in two and three dimensions, and the two-dimensional projections of the latter. The nature of the relationship between the avalanching volume and its projected area is an issue of particular interest in the solar flare context. Using our simulation results we investigate this relationship, and demonstrate that proper accounting of the fractal nature of avalanches can bring into agreement hitherto discrepant results of observational analyses based on simple, nonfractal geometries for the flaring volume. C1 NASA, ESA, Dept Space Sci, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Natl Ctr Atmospher Res, High Altitude Observ, Boulder, CO 80307 USA. RP NASA, ESA, Dept Space Sci, Goddard Space Flight Ctr, Mailcode 682-3, Greenbelt, MD 20771 USA. EM scott@esa.nascom.nasa.gov RI Liu, Han-Li/A-9549-2008 OI Liu, Han-Li/0000-0002-6370-0704 NR 40 TC 19 Z9 19 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2470-0045 EI 2470-0053 J9 PHYS REV E JI Phys. Rev. E PD APR PY 2002 VL 65 IS 4 AR 046125 DI 10.1103/PhysRevE.65.046125 PN 2A PG 12 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA 544FA UT WOS:000175146500044 PM 12005944 ER PT J AU Mei, RW Yu, DZ Shyy, W Luo, LS AF Mei, RW Yu, DZ Shyy, W Luo, LS TI Force evaluation in the lattice Boltzmann method involving curved geometry SO PHYSICAL REVIEW E LA English DT Article ID BOUNDARY-CONDITIONS; ANALYTIC SOLUTIONS; SIMPLE FLOWS; BGK MODELS; EQUATION; SIMULATIONS; FLUID; DERIVATION; PRESSURE AB The present work investigates two approaches for force evaluation in the lattice Boltzmann equation: the momentum-exchange method and the stress-integration method on the surface of a body. The boundary condition for the particle distribution functions on curved geometries is handled with second-order accuracy based on our recent works [Mei , J. Comput. Phys. 155, 307 (1999); ibid. 161, 680 (2000)]. The stress-integration method is computationally laborious for two-dimensional flows and in general difficult to implement for three-dimensional flows, while the momentum-exchange method is reliable, accurate, and easy to implement for both two-dimensional and three-dimensional flows. Several test cases are selected to evaluate the present methods, including: (i) two-dimensional pressure-driven channel flow; (ii) two-dimensional uniform flow past a column of cylinders; (iii) two-dimensional flow past a cylinder asymmetrically placed in a channel (with vortex shedding); (iv) three-dimensional pressure-driven flow in a circular pipe; and (v) three-dimensional flow past a sphere. The drag evaluated by using the momentum-exchange method agrees well with the exact or other published results. C1 Univ Florida, Dept Aerosp Engn Mech & Engn Sci, Gainesville, FL 32611 USA. NASA, ICASE, Langley Res Ctr, Hampton, VA 23681 USA. RP Mei, RW (reprint author), Univ Florida, Dept Aerosp Engn Mech & Engn Sci, Gainesville, FL 32611 USA. EM rwm@aero.ufl.edu; ydz@aero.ufl.edu; wss@aero.ufl.edu; luo@icase.edu RI Luo, Li-Shi/A-4561-2011 OI Luo, Li-Shi/0000-0003-1215-7892 NR 40 TC 154 Z9 173 U1 2 U2 26 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1539-3755 J9 PHYS REV E JI Phys. Rev. E PD APR PY 2002 VL 65 IS 4 AR 041203 DI 10.1103/PhysRevE.65.041203 PN 1 PG 14 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA 544EZ UT WOS:000175146400020 PM 12005812 ER PT J AU Uritsky, VM Klimas, AJ Vassiliadis, D AF Uritsky, VM Klimas, AJ Vassiliadis, D TI Multiscale dynamics and robust critical scaling in a continuum current sheet model SO PHYSICAL REVIEW E LA English DT Article ID SELF-ORGANIZED CRITICALITY AB We analyze the self-organized critical behavior of a continuum running avalanche model. We demonstrate that over local interaction scales, the model behavior is affected by low-dimensional chaotic dynamics that plays the role of the primary noise source. With the help of scale-free avalanches, the uncertainty associated with chaos is distributed over a variety of intermediate scales and thus gives rise to spatiotemporal fluctuations that are characterized by power-law distribution functions. We show that globally, the continuum model displays structurally stable critical scaling that can be observed in a finite region in the control parameter space. In this region, the system exhibits a power-law critical divergence of the integrated response function over a broad range of dissipation rates. The observed behavior involves a remarkably stable spatial configuration. We explain the robust features of the model by the adjustable dynamics of its global loading-unloading cycle, which allows maintaining the long-term stationary state without affecting the intrinsic avalanche dynamics. C1 NASA, Natl Res Council, Goddard Space Flight Ctr, Greenbelt, MD 20770 USA. Univ Space Res Assoc, Seabrook, MD USA. RP St Petersburg State Univ, Inst Phys, St Petersburg 198904, Russia. EM uritsky@geo.phys.spbu.ru NR 13 TC 20 Z9 20 U1 0 U2 3 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2470-0045 EI 2470-0053 J9 PHYS REV E JI Phys. Rev. E PD APR PY 2002 VL 65 IS 4 AR 046113 DI 10.1103/PhysRevE.65.046113 PN 2A PG 5 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA 544FA UT WOS:000175146500032 PM 12005932 ER PT J AU Feynman, J AF Feynman, J TI The. good old days: John Spreiter in the 1960s SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Symposium on Intercomparative Magetosheath Studies CY SEP 04-08, 2000 CL ANTALYA, TURKEY C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Feynman, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 0 Z9 0 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD APR-MAY PY 2002 VL 50 IS 5-6 BP 417 EP 419 AR PII S0032-0633(02)00022-3 DI 10.1016/S0032-0633(02)00022-3 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 602ZP UT WOS:000178534600002 ER PT J AU Luhmann, JG Acuna, MH Purucker, M Russell, CT Lyon, JG AF Luhmann, JG Acuna, MH Purucker, M Russell, CT Lyon, JG TI The Martian magnetosheath: how Venus-like? SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Symposium on Intercomparative Magetosheath Studies CY SEP 04-08, 2000 CL ANTALYA, TURKEY ID SOLAR-WIND INTERACTION; MARS GLOBAL SURVEYOR; MAGNETIC-FIELD; BOW SHOCK; 3-DIMENSIONAL MHD; MAG/ER EXPERIMENT; IONOSPHERE; SIMULATIONS; PLANETS; MODEL AB The planets Mars and Venus, because of their weak global magnetic fields, have small-scale magnetosheaths amenable to detailed analysis and model comparisons. In this paper we examine some of the similarities and contrasts between the Venus and Mars cases based on Pioneer Venus Orbiter (PVO) magnetometer observations from the PVO prime mission, and Mars Global Surveyor magnetometer observations obtained during the MGS Science Phasing Orbits (March-September, 1998). The combination of a mass-loaded magnetohydrodynamic magnetosheath model and a data-based model of the Martian crustal fields is used to illustrate the differences produced by the presence of the Martian crustal fields. While Venus at solar maximum exhibits a nearly classical magnetosheath formed by the solar wind interaction with a practically impenetrable blunt body, Mars in late 1998 represents a complicated obstacle whose own magnetic fields compromise this simplicity within at least several hundred km of the nominal obstacle boundary inferred from the bow shock position. In particular, the results suggest the presence of a thick inner magnetosheath boundary layer when the strong southern hemisphere crustal fields are located on the sunward hemisphere. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA. Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA. RP Luhmann, JG (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. OI Russell, Christopher/0000-0003-1639-8298 NR 42 TC 5 Z9 5 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD APR-MAY PY 2002 VL 50 IS 5-6 BP 489 EP 502 AR PII S0032-0633(02)00028-4 DI 10.1016/S0032-0633(02)00028-4 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 602ZP UT WOS:000178534600008 ER PT J AU Zastenker, GN Nozdrachev, MN Nemecek, Z Safrankova, J Paularena, KI Richardson, JD Lepping, RP Mukai, T AF Zastenker, GN Nozdrachev, MN Nemecek, Z Safrankova, J Paularena, KI Richardson, JD Lepping, RP Mukai, T TI Multispacecraft measurements of plasma and magnetic field variations in the magnetosheath: Comparison with Spreiter models and motion of the structures SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Symposium on Intercomparative Magnetosheath Studies CY SEP 04-08, 2000 CL ANTALYA, TURKEY DE solar wind interaction; magnetosheath; magnetopause; bow shock ID SOLAR-WIND PLASMA; DENSITY-FLUCTUATIONS; EARTHS MAGNETOSHEATH; MAGNETOPAUSE MOTION; DYNAMIC PRESSURE; FLOW; TRANSITION; BOUNDARY; GEOTAIL; FLUX AB Large (from tens of percent up to several times) ion flux (or density) and magnetic field magnitude variations are typical magnetosheath features. Case and statistical comparisons of simultaneous solar wind observations, magnetosheath observations, and the gasdynamic model for the magnetosheath flow of Spreiter et al. (Planet. Space Sci. 14 (1966) 223) show that two types of magnetosheath plasma and magnetic field variations exist: in some cases, they are a repetition or amplification of solar wind or IMF disturbances which pass through the bow shock; but in the most cases, these variations are endogenous; i.e., they originate inside the magnetosheath. Persistence times and/or correlation lengths for the magnetosheath plasma variations were investigated via detailed comparison of simultaneous magnetosheath measurements from several spacecraft. For small separation distances (about 0.5R(E)) we used the satellite pair INTERBALL-1/MAGION-4; for larger distances (up to 10-30R(E) on the same or on the opposite flanks of the magnetosheath) we used the INTERBALL-1/GEOTAIL/IMP 8 measurements. In some cases, we observed a remarkable coincidence of the magnetosheath plasma behavior from the spacecraft separated by more than 10R(E). It seems that the compression plasma structures move tailward together with the magnetosheath plasma flow. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Russian Acad Sci, Space Res Inst, Moscow 117997, Russia. Charles Univ Prague, Fac Math & Phys, CR-18000 Prague 8, Czech Republic. MIT, Ctr Space Res, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Inst Space & Astronaut Sci, Kanagawa 229, Japan. RP Zastenker, GN (reprint author), Russian Acad Sci, Space Res Inst, Profsojuznaja St 84-32, Moscow 117997, Russia. EM gzastenk@iki.rssi.ru NR 28 TC 26 Z9 26 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD APR-MAY PY 2002 VL 50 IS 5-6 BP 601 EP 612 AR PII S0032-0633(02)00039-9 DI 10.1016/S0032-0633(02)00039-9 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 602ZP UT WOS:000178534600019 ER PT J AU Xie, SC Xu, KM Cederwall, RT Bechtold, P Del Genio, AD Klein, SA Cripe, DG Ghan, SJ Gregory, D Iacobellis, SF Krueger, SK Lohmann, U Petch, JC Randall, DA Rotstayn, LD Somerville, RCJ Sud, YC Von Salzen, K Walker, GK Wolf, A Yio, JJ Zhang, GJ Zhang, MG AF Xie, SC Xu, KM Cederwall, RT Bechtold, P Del Genio, AD Klein, SA Cripe, DG Ghan, SJ Gregory, D Iacobellis, SF Krueger, SK Lohmann, U Petch, JC Randall, DA Rotstayn, LD Somerville, RCJ Sud, YC Von Salzen, K Walker, GK Wolf, A Yio, JJ Zhang, GJ Zhang, MG TI Intercomparison and evaluation of cumulus parametrizations under summertime midlatitude continental conditions SO QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY LA English DT Article DE Continental cumulus convection; single-column models ID RELAXED ARAKAWA-SCHUBERT; LARGE-SCALE ENVIRONMENT; SINGLE-COLUMN MODELS; GENERAL-CIRCULATION MODEL; TROPICAL CLOUD CLUSTERS; FLUX CONVECTION SCHEME; TOGA-COARE; STRATIFORM CLOUDS; MOISTURE BUDGETS; SQUALL LINE AB This study reports the Single-Column Model (SCM) part of the Atmospheric Radiation Measurement (ARM)/the Global Energy and Water Cycle Experiment (GEWEX) Cloud System Study (GCSS) joint SCM and Cloud-Resolving Model (CRM) Case 3 intercomparison study, with a focus on evaluation Of Cumulus parametrizations used in SCMs. Fifteen SCMs are evaluated under summertime midlatitude continental conditions using data collected at the ARM Southern Great Plains site during the summer 1997 Intensive Observing Period. Results from ten CRMs are also used to diagnose problems in the SCMs. It is shown that most SCMs can generally capture well the convective events that were well-developed within the SCM domain, while most of them have difficulties in simulating the occurrence of those convective events that only occurred within a small part of the domain. All models significantly underestimate the surface stratiform precipitation. A third of them produce large errors in surface precipitation and thermodynamic structures. Deficiencies in convective triggering mechanisms are thought to be one of the major reasons. Using a triggering mechanism that is based on the vertical integral of parcel buoyant energy without additional appropriate constraints results in overactive convection, which in turn leads to large systematic warm/dry biases in the troposphere. It is also shown that a non-penetrative convection scheme can underestimate the depth of instability for midlatitude convection, which leads to large systematic cold/moist biases in the troposphere. SCMs agree well quantitatively with CRMs in the updraught mass fluxes, while most models significantly underestimate the downdraught mass fluxes. Neglect of mesoscale updraught and downdraught mass fluxes in the SCMs contributes considerably to the discrepancies between the SCMs and the CRMs. In addition, uncertainties in the diagnosed mass fluxes in the CRMs and deficiencies with cumulus parametrizations are not negligible. Similar results are obtained in the sensitivity tests when different forcing approaches are used. Finally. sensitivity tests from an SCM indicate that its simulations can be greatly improved when its triggering mechanism and closure assumption are improved. C1 Lawrence Livermore Natl Lab, Atmospher Sci Div L103, Livermore, CA 94551 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. Observ Midi Pyrenees, Grenoble, France. NASA, Goddard Inst Space Studies, Greenbelt, MD USA. NOAA, Geophys Fluid Dynam Lab, Silver Spring, MD USA. Colorado State Univ, Ft Collins, CO 80523 USA. Pacific NW Natl Lab, Richland, WA 99352 USA. Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA. Univ Utah, Salt Lake City, UT 84112 USA. Dalhousie Univ, Halifax, NS B3H 3J5, Canada. CSIRO, Canberra, ACT, Australia. Univ Victoria, Canadian Ctr Climate Modeling & Anal, Victoria, BC V8W 2Y2, Canada. SUNY Stony Brook, Stony Brook, NY 11794 USA. RP Xie, SC (reprint author), Lawrence Livermore Natl Lab, Atmospher Sci Div L103, POB 808, Livermore, CA 94551 USA. RI Del Genio, Anthony/D-4663-2012; Xu, Kuan-Man/B-7557-2013; Rotstayn, Leon/A-1756-2012; Xie, Shaocheng/D-2207-2013; Randall, David/E-6113-2011; Ghan, Steven/H-4301-2011; Klein, Stephen/H-4337-2016; Lohmann, Ulrike/B-6153-2009 OI Del Genio, Anthony/0000-0001-7450-1359; Xu, Kuan-Man/0000-0001-7851-2629; Rotstayn, Leon/0000-0002-2385-4223; Xie, Shaocheng/0000-0001-8931-5145; Randall, David/0000-0001-6935-4112; Ghan, Steven/0000-0001-8355-8699; Klein, Stephen/0000-0002-5476-858X; Lohmann, Ulrike/0000-0001-8885-3785 NR 65 TC 88 Z9 90 U1 0 U2 11 PU ROYAL METEOROLOGICAL SOC PI READING PA 104 OXFORD ROAD, READING RG1 7LJ, BERKS, ENGLAND SN 0035-9009 J9 Q J ROY METEOR SOC JI Q. J. R. Meteorol. Soc. PD APR PY 2002 VL 128 IS 582 BP 1095 EP 1135 DI 10.1256/003590002320373229 PN B PG 41 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 564XR UT WOS:000176339300004 ER PT J AU Mann, DH Peteet, DM Reanier, RE Kunz, ML AF Mann, DH Peteet, DM Reanier, RE Kunz, ML TI Responses of an arctic landscape to Lateglacial and early Holocene climatic changes: the importance of moisture SO QUATERNARY SCIENCE REVIEWS LA English DT Review ID BROOKS-RANGE-FOOTHILLS; LATE-QUATERNARY; NORTHWESTERN ALASKA; ENVIRONMENTAL-CHANGE; VEGETATION HISTORY; NORTHERN ALASKA; TIME RESOLUTION; MAMMOTH STEPPE; COASTAL-PLAIN; YOUNGER DRYAS AB Many of the physical and biological processes that characterize arctic ecosystems are unique to high latitudes, and their sensitivities to climate change are poorly understood. Stratigraphic records of land-surface processes and vegetation change in the Arctic Foothills of northern Alaska reveal how tundra landscapes responded to climatic changes between 13,000 and 8000 C-14 yr BP. Peat deposition began and shrub vegetation became widespread ca. 12,500 C-14 yr BP, probably in response to the advent of warmer and wetter climate. Increased slope erosion caused rapid alluviation in valleys, and Populus trees spread northward along braided floodplains before 11,000 C-14 yr BP. Lake levels fell and streams incised their floodplains during the Younger Dryas (YD) (11,000-10,000 C-14 yr BP). A hiatus in records of Populus suggest that its geographic range contracted, and pollen records of other species suggest a cooler and drier climate during this interval. Basal peats dating to the YD are rare, suggesting that rates of paludification slowed. Immediately after 10,000 C-14 yr BP, lake levels rose, streams aggraded rapidly again, intense solifluction occurred, and Populus re-invaded the area. Moist acidic tundra vegetation was widespread by 8500 C-14 yr BP along with wet, organic-rich soils. Most of these landscape-scale effects of climatic change involved changes in moisture. Although low temperature is the most conspicuous feature of arctic climate, shifts in effective moisture may be the proximate cause for many of the impacts that climate change has in arctic regions. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Univ Alaska Fairbanks, Inst Arctic Biol, Fairbanks, AK 99775 USA. Univ Alaska Fairbanks, Alaska Quaternary Ctr, Fairbanks, AK 99775 USA. NASA, Goddard Inst Space Studies, Palisades, NY 10964 USA. Lamont Doherty Earth Observ, Palisades, NY 10964 USA. Reanier & Associates, Seattle, WA 98122 USA. Bur Land Management, Fairbanks, AK 99708 USA. RP Mann, DH (reprint author), Univ Alaska Fairbanks, Inst Arctic Biol, Fairbanks, AK 99775 USA. NR 128 TC 69 Z9 70 U1 0 U2 25 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0277-3791 J9 QUATERNARY SCI REV JI Quat. Sci. Rev. PD APR PY 2002 VL 21 IS 8-9 BP 997 EP 1021 AR PII S0277-3791(01)00116-0 DI 10.1016/S0277-3791(01)00116-0 PG 25 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA 551MU UT WOS:000175566100012 ER PT J AU Nikjoo, H Khvostunov, IK Cucinotta, FA AF Nikjoo, H Khvostunov, IK Cucinotta, FA TI The response of tissue-equivalent proportional counters to heavy ions SO RADIATION RESEARCH LA English DT Article ID CHARGED-PARTICLES; ELECTRON-SPECTRA; DISTRIBUTIONS; IONIZATION AB The paper presents a theoretical model for the response of a tissue-equivalent proportional counter (TEPC) irradiated with charged particles. Heavy ions and iron ions in particular constitute a significant part of radiation in space. TEPCs are used for all space shuttle and International Space Station (ISS) missions to estimate the dose and radiation quality (in terms of lineal energy) inside spacecraft. The response of the tissue-equivalent proportional counters shows distortions at the wall/cavity interface. In this paper, we present microdosimetric investigation using Monte Carlo track structure calculations to simulate the response of a TEPC to charged particles of various LET (1 MeV protons, 2.4 MeV alpha particles, 46 MeV/nueleon (20)Ne, 55 MeV/nucleon (20)Ne, 45 MeV/nucleon (40)Ar, and 1.05 GeV/nucleon (56)Fe). Data are presented for energy lost and energy absorbed in the counter cavity and wall. The model calculations are in good agreement with the results of Rademacher et al (Radiat. Res. 149, 387-389, 1998), including the study of the interface between the wall and the sensitive region of the counter. It is shown that the anomalous response observed at large event sizes in the experiment is due to an enhanced entry of secondary electrons from the wall into the gas cavity. (C) 2002 by Radiation Research Society. C1 MRC, Radiat & Genome Stabil Unit, Didcot OX11 0RD, Oxon, England. Med Radiol Res Ctr, Obninsk 249020, Kaluga Region, Russia. NASA, Space & Life Sci Directorate, Houston, TX 77058 USA. RP Nikjoo, H (reprint author), MRC, Radiat & Genome Stabil Unit, Didcot OX11 0RD, Oxon, England. EM h.nikjoo@har.mrc.ac.uk NR 24 TC 28 Z9 28 U1 0 U2 1 PU RADIATION RESEARCH SOC PI LAWRENCE PA 810 E TENTH STREET, LAWRENCE, KS 66044 USA SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD APR PY 2002 VL 157 IS 4 BP 435 EP 445 DI 10.1667/0033-7587(2002)157[0435:TROTEP]2.0.CO;2 PG 11 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA 536VQ UT WOS:000174722900011 PM 11893246 ER PT J AU Yang, MT Gandhi, T Kasturi, R Coraor, L Camps, O McCandless, J AF Yang, MT Gandhi, T Kasturi, R Coraor, L Camps, O McCandless, J TI Real-time implementation of obstacle detection algorithms on a Datacuhe MaxPCI architecture SO REAL-TIME IMAGING LA English DT Article ID FILTER AB The high-speed civil transport (HSCT) aircraft has been designed with limited cockpit visibility. To handle this, the National Aeronautics and Space Administration (NASA) has proposed an external visibility system (XVS) to aid pilots in overcoming this lack of visibility. XVS obtains video images using high-resolution cameras mounted on and directed outside the aircraft. Images captured by the XVS enable automatic computer analysis in real-time, and thereby alert pilots about potential flight path hazards. Thus, the system is useful in helping pilots avoid air collisions. In this study, a system was configured to capture image sequences from an on-board high-resolution digital camera at a live video rate, record the images into a highspeed disk array through a fiber channel, and process the images using a Datacube MaxPCI machine with multiple pipelined processors to perform real-time obstacle detection. In this paper, we describe the design, implementation, and evaluation of this computer vision system. Using this system, real-time obstacle detection was performed and digital image data were obtained successfully in flight tests conducted at NASA Langley Research Center in January and September 1999. The system is described in detail so that other researchers can easily replicate the work. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Penn State Univ, University Pk, PA 16802 USA. NASA, Ames Res Ctr, Human Informat Proc Res Branch, Moffett Field, CA 94035 USA. NR 17 TC 2 Z9 2 U1 0 U2 1 PU ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 1077-2014 J9 REAL-TIME IMAGING JI Real-Time Imaging PD APR PY 2002 VL 8 IS 2 BP 157 EP 172 DI 10.1006/rtim.2001.0272 PG 16 WC Computer Science, Artificial Intelligence; Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA 587EN UT WOS:000177627700008 ER PT J AU Sabol, DE Gillespie, AR Adams, JB Smith, MO Tucker, CJ AF Sabol, DE Gillespie, AR Adams, JB Smith, MO Tucker, CJ TI Structural stage in Pacific Northwest forests estimated using simple mixing models of multispectral images SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID THEMATIC MAPPER; TM DATA; CANOPY; REFLECTANCE; SCATTERING; VEGETATION; VARIOGRAMS; AGE AB We identified stages of regrowth in replanted clearcuts in D ouglas-fir/western hemlock forests in the Gifford Pinchot National Forest, southern Washington, USA, using a simple four-endmember constrained linear spectral mixing model applied to a multispectral Landsat Thematic Mapper image in order to separate and quantify spectral contributions from significant scene components. Spectral unmixing produces images of the fractional amount of the spectral endmembers, which were green vegetation, nonphotosynthetic vegetation, soil and "shade," which includes topographic shading and shadows. Changes in endmember fractions correspond to changes in surface composition (as viewed from above). Unresolved shadows comprise the primary indicator of canopy structure and hence, regrowth stage. To isolate shadows, shading predicted from a digital elevation model was removed from the image before mixture analysis. As stands regrow, the surface cover shifts from initial high proportion of slash and exposed soil, and low proportions of green vegetation and shadows, to low fractions of stems and soil with high fractions of green vegetation and shadows. This shift in surface composition defines a regrowth trend in an endmember fraction data space. Projection of data onto this line allows estimation of structural stage and stand age, and provides a framework for remote mapping and monitoring of forest regrowth. Field analysis of 495 forest stands, representing stand structural stages ranging from newly replanted cuts to stands greater than 250 years in age, was used to assess the accuracy and precision of predicted structural stages and stand ages. The spectral unmixing approach can be used to evaluate and monitor forest regrowth quickly over large areas of the Pacific Northwest forests, and is extendible to mapping basic vegetation community type as well as structural stage. (C) 2002 Elsevier Science Inc. All rights reserved. C1 Univ Washington, Dept Earth & Space Sci, Seattle, WA 98195 USA. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. RP Sabol, DE (reprint author), Univ Washington, Dept Earth & Space Sci, Campus Box 251-310, Seattle, WA 98195 USA. NR 34 TC 57 Z9 60 U1 0 U2 4 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD APR PY 2002 VL 80 IS 1 BP 1 EP 16 AR PII S0034-4257(01)00245-0 DI 10.1016/S0034-4257(01)00245-0 PG 16 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 534HN UT WOS:000174579200001 ER PT J AU Hwang, PA Wright, W Krabill, WB Swift, RN AF Hwang, PA Wright, W Krabill, WB Swift, RN TI Airborne remote sensing of breaking waves SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID OCEAN SURFACE-WAVES; GREENLAND ICE-SHEET; LASER ALTIMETRY; NUMBER SPECTRA AB Airborne scanning laser ranging provides rapid measurements of the ocean wave topography. In addition to active ranging, the scanning optics can obtain passive measurements of the surface emissivity, yielding a digital image of the surface brightness. The brightness data contain information on the statistics and spatial distribution of whitecaps. Combining active measurements of the 3D surface topography and passive brightness data, the phase distribution of breaking events along a wave profile can be examined. From the phase distribution analysis, it is found that in deep water, the whitecap coverage in the windward phase is slightly higher than that in the leeward phase (51 +/- 17% vs. 49 +/- 14%), and more whitecaps are found on the crests than in the troughs (57 +/- 13% vs. 44 +/- 16%). Such quantitative information on wave breaking and whitecap coverage is important to remote sensing applications and air-sea interaction studies. (C) 2002 Elsevier Science Inc. All rights reserved. C1 USN, Res Lab, Div Oceanog, Stennis Space Ctr, MS 39529 USA. NASA, GFSC, WFF, Wallops Isl, VA USA. EG&G, Wallops Isl, VA USA. RP Hwang, PA (reprint author), USN, Res Lab, Div Oceanog, Stennis Space Ctr, MS 39529 USA. NR 10 TC 0 Z9 0 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD APR PY 2002 VL 80 IS 1 BP 65 EP 75 AR PII S0034-4257(01)00285-1 DI 10.1016/S0034-4257(01)00285-1 PG 11 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 534HN UT WOS:000174579200006 ER PT J AU Gitelson, AA Kaufman, YJ Stark, R Rundquist, D AF Gitelson, AA Kaufman, YJ Stark, R Rundquist, D TI Novel algorithms for remote estimation of vegetation fraction SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID LEAF-AREA INDEX; REFLECTANCE SPECTRA; CANOPY REFLECTANCE; GLOBAL-VEGETATION; WHEAT CANOPIES; CHLOROPHYLL-A; WATER-STRESS; EOS-MODIS; LEAVES; SOIL AB Spectral properties of a wheat canopy with vegetation fraction (AIF) from 0% to 100% in visible and near-infrared (NITR) ranges of the spectrum were studied in order to devise a technique for remote estimation of VF. When VF was <60%, from emergence till middle of the elongation stage, four distinct, and quite independent, spectral bands of reflectance existed in the visible range of the spectrum: 400 to 500 nm. 530 to 600 nm, near 670 nm, and around 700 nm. When VF was between 60% and 100%, reflectance in the NIR leveled off or even decreases with an increase of VF. The decreased reflectance in the NIR, occurring at or near the midseason, can be a limiting factor in the use of that spectral region for VF estimation. It was found that for VF>60%, the information content of reflectance spectra in visible range can be expressed by only two independent pairs of spectral bands: (1) the blue from 400 to 500 nm and the red near 670 nm; (2) the green around 550 rim and the red edge region near 700 rim. We propose using only the visible range of the spectrum to quantitatively estimate VF The green (as well as a 700-nm band) and the red (near 670 nm) reflectances were used in developing new indices, which were linearly proportional to wheat VF ranging from 0% to 100%. The Atmospherically Resistant Vegetation Index (ARVI) concept was used to correct indices for atmospheric effects. Visible Atmospherically Resistant Index in the form VARI=(R-green-R-red)/(R-green + R-red - R-blue) was found to be minimally sensitive to atmospheric effects allowing estimation of VF with an error of <10% in a wide range of atmospheric optical thickness. Validation of the newly suggested technique was carried out using wheat independent data sets and reflectance data obtained for cornfields in Nebraska. Predicted green VF was compared with retrieved from digital images. Despite the fact that the reflectance contrast among the visible channels is much smaller than between the visible and NIR, the sensitivity of suggested indices to moderate to high values of VF is much higher than for the Normalized Difference Vegetation Index (NDVI), and the error in VF prediction did not exceed 10%. Suggested indices will complement the widely used NDVI, ARVI, Soil Adjusted Vegetation Index (SAVI) and others, which are based on the red and the NIR bands in VF estimation, and also Green Atmospherically Resistant Index (GARI), which is based on the green and the NIR bands. (C) 2002 Elsevier Science Inc. All rights reserved. C1 Univ Nebraska, Sch Nat Resource Sci, Ctr Adv Land Management Informat Technol, Lincoln, NE 68588 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Ben Gurion Univ Negev, Dept Geog & Environm Sci, IL-84105 Beer Sheva, Israel. RP Gitelson, AA (reprint author), Univ Nebraska, Sch Nat Resource Sci, Ctr Adv Land Management Informat Technol, Lincoln, NE 68588 USA. RI Gitelson, Anatoly/G-3452-2012 NR 44 TC 307 Z9 421 U1 13 U2 93 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD APR PY 2002 VL 80 IS 1 BP 76 EP 87 AR PII S0034-4257(01)00289-9 DI 10.1016/S0034-4257(01)00289-9 PG 12 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 534HN UT WOS:000174579200007 ER PT J AU Qin, WH Gerstl, SAW Deering, DW Goel, NS AF Qin, WH Gerstl, SAW Deering, DW Goel, NS TI Characterizing leaf geometry for grass and crop canopies from hotspot observations: A simulation study SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID BIDIRECTIONAL REFLECTANCE; VEGETATION CANOPIES; MODEL; DISTRIBUTIONS; FOREST; SHAPE AB The potential of canopy reflectance distributions in the hotspot region for characterizing leaf geometry (leaf size and shape) of grass and crop canopies is explored with computer simulations. In this article, a computer graphics method-Lindenmayer-systems (L-systems) - is used to render a series of leaf (grass) and architecturally realistic row-planted crop (corn-like) canopies that have a variety of geometrical structures. A radiosity-graphics combined model is then employed to calculate the radiation regime in a canopy, including canopy directional reflectance. An effectiveness ratio (E ratio) is proposed, which is able to evaluate the performance of a given measure or index in estimation of the parameter of interest under the influence of a number of "noise" factors (other geometric and optical parameters of the canopy) at various noise levels. This E ratio is then applied to evaluate reflectance and normalized reflectance in the hotspot region for leaf geometry characterization. The result from simulated hotspot reflectance demonstrates that for both canopies, leaf geometry is estimable by using normalized reflectance within +/-4-8degrees (or +/-2-4degrees) around the hotspot direction in the principal cone (or principal plane). However, the center position and angular width of the optimal sampling region are affected by the number of noise factors [such as leaf area index, leaf angle distribution for leaf canopies, plus row structure for row-plant crop canopies] and their variation ranges. In most cases, normalized spectral reflectance in the near-infrared at a high solar zenith angle in the PC produces the most reliable results. The reason for better estimation of leaf geometry for grass and crop canopies than forests from hotspot observations is also discussed in this article. (C) 2002 Elsevier Science Inc. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Raytheon, ITTS, Greenbelt, MD 20771 USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Wayne State Univ, Dept Comp Sci, Detroit, MI 48202 USA. RP Qin, WH (reprint author), NASA, Goddard Space Flight Ctr, Raytheon, ITTS, Code 916, Greenbelt, MD 20771 USA. RI 黄, 建荣/B-8070-2011 NR 32 TC 9 Z9 11 U1 0 U2 3 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD APR PY 2002 VL 80 IS 1 BP 100 EP 113 AR PII S0034-4257(01)00291-7 DI 10.1016/S0034-4257(01)00291-7 PG 14 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 534HN UT WOS:000174579200009 ER PT J AU Radil, KC Dellacorte, C AF Radil, KC Dellacorte, C TI The effect of journal roughness and foil coatings on the performance of heavily loaded foil air bearings SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT 56th Annual Meeting of the Society-of-Tribologists-and-Lubrication-Engineers CY MAY 20-24, 2001 CL ORLANDO, FLORIDA SP Soc Tribologists Lubricat Engineers DE foil air bearings; solid lubrication; surface roughness; gas bearings AB Foil air bearing load capacity tests were conducted to investigate if a solid lubricant coating applied to the surface of the bearing's top foil can function as a break-in coating. Two foil coating materials, a conventional soft polymer film (polyimide) and a hard ceramic (alumina), were independently evaluated against as-ground and worn (run-in) journals coated with NASA PS304, a high-temperature solid lubricant composite coating. The foil coatings were evaluated at journal rotational speeds of 30,000 rpm and at 25degreesC. Tests were also performed on a foil bearing with a bare (uncoated) nickel-based superalloy top foil to establish a baseline for comparison. The test results indicate that the presence of a top foil solid lubricant coating is effective at increasing the load capacity performance of the foil bearing. Compared to the uncoated baseline, the addition of the soft polymer coating on the top foil increased the bearing load coefficient by 120 percent when operating against an as-ground journal surface and 85% against a run-in 0 journal surface. The alumina coating increased the load coefficient by 40 percent against the as-ground journal but did not have any effect when the bearing was operated with the run-in journal. The results suggest that the addition of solid lubricant films provide added lubrication when the air film is marginal, indicating that as the load capacity is approached foil air bearings transition from hydrodynamic to mixed and boundary lubrication. C1 NASA, Glenn Res Ctr, USA, Res Lab, Cleveland, OH 44135 USA. RP Radil, KC (reprint author), NASA, Glenn Res Ctr, USA, Res Lab, Cleveland, OH 44135 USA. NR 13 TC 22 Z9 23 U1 1 U2 10 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 1040-2004 J9 TRIBOL T JI Tribol. Trans. PD APR PY 2002 VL 45 IS 2 BP 199 EP 204 DI 10.1080/10402000208982540 PG 6 WC Engineering, Mechanical SC Engineering GA 536CC UT WOS:000174682300009 ER PT J AU von Frese, RRB Taylor, PT Chiappini, M AF von Frese, RRB Taylor, PT Chiappini, M TI Special issue - Magnetic anomalies of the Antarctic - Preface SO TECTONOPHYSICS LA English DT Editorial Material C1 Ohio State Univ, Dept Geol Sci, Columbus, OH 43210 USA. NASA, Goddard Space Flight Ctr, Geodynam Branch, Greenbelt, MD 20771 USA. Ist Nazl Geofis & Vulcanol, I-00143 Rome, Italy. RP von Frese, RRB (reprint author), Ohio State Univ, Dept Geol Sci, Columbus, OH 43210 USA. RI Taylor, Patrick/D-4707-2012 OI Taylor, Patrick/0000-0002-1212-9384 NR 6 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD MAR 29 PY 2002 VL 347 IS 1-3 BP 1 EP 2 AR PII S0040-1951(01)00233-5 DI 10.1016/S0040-1951(01)00233-5 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 560ZQ UT WOS:000176111600001 ER PT J AU Ghidella, ME Yanez, G LaBrecque, JL AF Ghidella, ME Yanez, G LaBrecque, JL TI Revised tectonic implications for the magnetic anomalies of the western Weddell Sea SO TECTONOPHYSICS LA English DT Article; Proceedings Paper CT Spring Meeting of the American-Geophysical-Union CY 1999 CL BOSTON, MASSACHUSETTS SP Amer Geophys Union DE Antarctica; Weddell Sea; magnetics; gravity; seafloor spreading; fracture zone ID MARINE GRAVITY-FIELD; ANTARCTIC PENINSULA; SOUTH-ATLANTIC; EVOLUTION; BASIN; RIDGE; CONSTRAINTS AB Ten years after the USAC (U.S.-Argentina-Chile) Project, which was the most comprehensive aeromagnetic effort in the Antarctic Peninsula and surrounding ocean basins, questions remain regarding the kinematics of the early opening history of the Weddell Sea. Key elements in this complex issue are a better resolution of the magnetic sequence in the western part of the Weddell Sea and merging the USAC data set with the other magnetic data sets in the region. For this purpose we reprocessed the USAC data set using a continuation between arbitrary surfaces and equivalent magnetic sources. The equivalent sources are located at a smooth crustal surface derived from the existing bathymetry/topography and depths estimated by magnetic inversions. The most critical area processed was the transition between the high altitude survey over the Antarctic Peninsula and the low altitude survey over the Weddell Sea that required downward continuation to equalize the distance to the magnetic source. This procedure was performed with eigenvalue analysis to stabilize the equivalent magnetic source inversion. The enhancement of the Mesozoic sequence permits refining the interpretation of the seafloor-spreading anomalies. In particular, the change in shape and wavelength of an elongated positive in the central Weddell Sea suggests that it was formed during the Cretaceous Normal Polarity Interval. The older lineations in the southwestern Weddell Sea are tentatively attributed to susceptibility contrasts modeled as fracture zones. Numerical experimentation to adjust synthetic isochrons to seafloor-spreading lineations and flow lines to fracture zones yields stage poles for the opening of the Weddell Sea since 160 Ma to anomaly 34 time. The corresponding reconstructions look reasonable within the known constraints for the motions of the Antarctic and South America plates. However, closure is not attained between 160 and 118 Ma if independent published East Antarctica-Africa-South America rotations are considered. The lack of closure may be overcome by considering relative motion between the Antarctic Peninsula and East Antarctica until 118 Ma time, an important component of convergence. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Inst Antartico Argentino, RA-1010 Buenos Aires, DF, Argentina. Geodatos SAIC, Santiago, Chile. NASA, Solid Earth & Nat Hazards Program, Off Earth Sci, Washington, DC 20546 USA. RP Ghidella, ME (reprint author), Inst Antartico Argentino, Cerrito 1248, RA-1010 Buenos Aires, DF, Argentina. NR 48 TC 45 Z9 49 U1 0 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD MAR 29 PY 2002 VL 347 IS 1-3 BP 65 EP 86 AR PII S0040-1951(01)00238-4 DI 10.1016/S0040-1951(01)00238-4 PG 22 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 560ZQ UT WOS:000176111600006 ER PT J AU Kletetschka, G Wasilewski, PJ Taylor, PT AF Kletetschka, G Wasilewski, PJ Taylor, PT TI The role of hematite-ilmenite solid solution in the production of magnetic anomalies in ground- and satellite-based data SO TECTONOPHYSICS LA English DT Article; Proceedings Paper CT Spring Meeting of the American-Geophysical-Union CY 1999 CL BOSTON, MASSACHUSETTS SP Amer Geophys Union DE magnetic petrology; hematite; ilmenite; REM; TRM; CRM; magnetic anomalies ID DEEP CRUSTAL ROCKS; REMANENT MAGNETISM; ALLARD LAKE; MINERALOGY; PROVINCE; LABRADOR; BOUNDARY; LOFOTEN; NORWAY; MOHO AB Remanent magnetization (RM) of rocks with hematite-ilmenite solid solution (HISS) minerals, at all crustal levels, may be an important contribution to magnetic anomalies measured by ground and satellite altitude surveys. The possibility that lower thermal gradient relatively deep in the crust can result in exsolution of HISS compositions with strong remanent magnetizations (RM) was studied for two bulk compositions within the HISS system. Samples from granulite-terrane around Wilson Lake, Labrador, Canada contains titanohematite with exsolved ferrian ilmenite lamellae. Other samples from the anorthosite-terrane of Allard Lake, Quebec, Canada contain ferrian ilmenite with exsolved titanohematite lamellae. In both cases, the final exsolved titanohematite has similar Ti content and carries dominant magnetic remanence with REM (=NRM/SIRM where NRM is the natural remanent magnetization and SIRM is the saturation isothermal remanent magnetization) that is comparable to the Ti-free end member. The RM was acquired prior to exsolution and the ilmeno-hematite-rich rock possesses thermal remanent magnetization (TRM), whereas rocks with hemo-ilmenite possess chemical remanent magnetization (CRM). In both cases, we found fairly large homogeneous grains with low demagnetizing energy that acquired intense RM. The magnetism of the ilmenohematite solid solution phases is not significantly perturbed by the continuous reaction: ilmeno-hematite greater than or equal totitanohematite solid solution. Hence, the occurrence of HISS in rocks that cooled slowly in a low intensity magnetic field will have an intense magnetic signature characterized by a large REM. (C) 2002 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Washington, DC 20064 USA. RP Kletetschka, G (reprint author), NASA, Goddard Space Flight Ctr, Code 691,, Greenbelt, MD 20771 USA. EM gunther.kletetschka@gsfc.nasa.gov RI Kletetschka, Gunther/C-9996-2011; Taylor, Patrick/D-4707-2012 OI Kletetschka, Gunther/0000-0002-0645-9037; Taylor, Patrick/0000-0002-1212-9384 NR 38 TC 24 Z9 24 U1 0 U2 10 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD MAR 29 PY 2002 VL 347 IS 1-3 BP 167 EP 177 AR PII S0040-1951(01)00243-8 DI 10.1016/S0040-1951(01)00243-8 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 560ZQ UT WOS:000176111600011 ER PT J AU Walch, SP Dateo, CE AF Walch, SP Dateo, CE TI Reactions of SiCl2 and SiHCl with H and Cl atoms SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID CORRELATED MOLECULAR CALCULATIONS; GAUSSIAN-BASIS SETS; WAVE-FUNCTIONS AB Calculations have been carried out for the reaction of SiCl2 and SiHCl with H and Cl atoms. In each case, the stationary point geometries and harmonic frequencies were characterized using CASSCF/derivative methods and the cc-pVDZ basis set. Accurate energetics were obtained by combining the CCSD(T) results using the aug-cc-pVTZ basis set with an extrapolation to the basis set limit using the aug-cc-pVDZ, aug-cc-pVTZ, and aug-cc-pVQZ basis sets at the MP2 level. The geometries, energetics, and harmonic frequencies were used to obtain rate constants using conventional transition state theory or a Gorin-like model. In each case, we find direct abstraction pathways compete with an addition elimination pathway. In the case of SiClH + H, the two direct pathways are H abstraction which is barrierless and Cl abstraction with a barrier of 13.5 kcal/mol, whereas the addition elimination process has a barrrier of 26.9 kcal/mol. In the case of SiCl2 + H, the direct pathway is Cl abstraction with a barrier of 16.4 kcal/mol, whereas the addition elimination pathway has a barrier of 29.6 kcal/mol. In the case of SiClH + Cl, the direct pathway is H abstraction which is barrierless and the addition elimination pathway has a barrier of 2.0 kcal/mol. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Walch, SP (reprint author), NASA, Ames Res Ctr, MS 230-3, Moffett Field, CA 94035 USA. NR 19 TC 5 Z9 5 U1 1 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5639 J9 J PHYS CHEM A JI J. Phys. Chem. A PD MAR 28 PY 2002 VL 106 IS 12 BP 2931 EP 2934 DI 10.1021/jp0126154 PG 4 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 534LU UT WOS:000174588500023 ER PT J AU Frankland, SJV Caglar, A Brenner, DW Griebel, M AF Frankland, SJV Caglar, A Brenner, DW Griebel, M TI Molecular simulation of the influence of chemical cross-links on the shear strength of carbon nanotube-polymer interfaces SO JOURNAL OF PHYSICAL CHEMISTRY B LA English DT Letter ID MECHANICAL-PROPERTIES; LOAD-TRANSFER; COMPOSITES; FUNCTIONALIZATION AB The influence of chemical cross-links between a single-walled fullerene nanotube and a polymer matrix on the matrix-nanotube shear strength has been studied using molecular dynamics simulations. A (10,10) nanotube embedded in either a crystalline or amorphous polyethylene matrix is used as a model for a nonbonded interface (in the absence of cross-Links). The simulations predict that shear strengths and critical lengths required for load transfer can be enhanced and decreased, respectively, by over an order of magnitude with the formation of cross-links involving less than 1% of the nanotube carbon atoms. At this level of chemical functionalization, calculations also predict that there is a negligible change in tensile modulus for a (10,10) nanotube. C1 Univ Bonn, Dept Appl Math, Div Sci Comp & Numer Simulat, D-5300 Bonn, Germany. N Carolina State Univ, Dept Mat Sci & Engn, Raleigh, NC 27695 USA. RP Frankland, SJV (reprint author), NASA, Langley Res Ctr, ICASE, M-S 132C, Hampton, VA 23669 USA. RI Brenner, Donald/D-1741-2009 NR 24 TC 400 Z9 407 U1 6 U2 89 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1520-6106 J9 J PHYS CHEM B JI J. Phys. Chem. B PD MAR 28 PY 2002 VL 106 IS 12 BP 3046 EP 3048 DI 10.1021/jp015591+ PG 3 WC Chemistry, Physical SC Chemistry GA 534LZ UT WOS:000174589000004 ER PT J AU Bernstein, MP Dworkin, JP Sandford, SA Cooper, GW Allamandola, LJ AF Bernstein, MP Dworkin, JP Sandford, SA Cooper, GW Allamandola, LJ TI Racemic amino acids from the ultraviolet photolysis of interstellar ice analogues SO NATURE LA English DT Article ID ALLENDE MINERALS; SOLAR-SYSTEM; DENSE CLOUDS; HYDROGEN; INVENTORY; METHANOL AB The delivery of extraterrestrial organic molecules to Earth by meteorites may have been important for the origin and early evolution of life(1). Indigenous amino acids have been found in meteorites(2)-over 70 in the Murchison meteorite alone(3). Although it has been generally accepted that the meteoritic amino acids formed in liquid water(4) on a parent body, the water in the Murchison meteorite is depleted in deuterium(5) relative to the indigenous organic acids(6,7). Moreover, the meteoritical evidence(8) for an excess of laevo-rotatory amino acids is hard to understand in the context of liquid-water reactions on meteorite parent bodies. Here we report a laboratory demonstration that glycine, alanine and serine naturally form from ultraviolet photolysis of the analogues of icy interstellar grains. Such amino acids would naturally have a deuterium excess similar to that seen in interstellar molecular clouds, and the formation process could also result in enantiomeric excesses if the incident radiation is circularly polarized. These results suggest that at least some meteoritic amino acids are the result of interstellar photochemistry, rather than formation in liquid water on an early Solar System body. C1 SETI Inst, Ctr Study Life Universe, Mountain View, CA 94043 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP SETI Inst, Ctr Study Life Universe, 2035 Landings Dr, Mountain View, CA 94043 USA. EM mbernstein@mail.arc.nasa.gov RI Dworkin, Jason/C-9417-2012 OI Dworkin, Jason/0000-0002-3961-8997 NR 30 TC 414 Z9 419 U1 8 U2 74 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 EI 1476-4687 J9 NATURE JI Nature PD MAR 28 PY 2002 VL 416 IS 6879 BP 401 EP 403 DI 10.1038/416401a PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 534UX UT WOS:000174607800038 PM 11919623 ER PT J AU Bauschlicher, CW Ricca, A Rosi, M AF Bauschlicher, CW Ricca, A Rosi, M TI Mechanisms for the growth of polycyclic aromatic hydrocarbon (PAH) cations SO CHEMICAL PHYSICS LETTERS LA English DT Article ID ACETYLENE; FLAMES AB The barriers and heats of reaction for the conversion of benzene cation to naphthalene cation by acetylene additions using the B3LYP/6-31G* approach are reported. The barrierless path we previously reported, using the B3LYP/4-31G approach. is shown to be incorrect. New paths for the ring formation are shown to have low barriers. (C) 2002 Published by Elsevier Science B.V. C1 NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. Univ Perugia, CNR, Ctr High Performance Comp Mol Sci, Dept Chem, I-06123 Perugia, Italy. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, Space Technol Div, Mail Stop 230-3, Moffett Field, CA 94035 USA. RI Rosi, Marzio/L-5748-2015 OI Rosi, Marzio/0000-0002-1264-3877 NR 13 TC 17 Z9 17 U1 1 U2 14 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 MAR 25 PY 2002 VL 355 IS 1-2 BP 159 EP 163 AR PII S0009-2614(02)00202-6 DI 10.1016/S0009-2614(02)00202-6 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 539AP UT WOS:000174847500025 ER PT J AU Carati, D Rogers, MM Wray, AA AF Carati, D Rogers, MM Wray, AA TI Statistical ensemble of large-eddy simulations SO JOURNAL OF FLUID MECHANICS LA English DT Article ID SUBGRID-SCALE MODEL; STOCHASTIC BACKSCATTER; TURBULENT FLOWS; LAYER AB A statistical ensemble of large-eddy simulations (LES) is run simultaneously for the same flow. The information provided by the different large-scale velocity fields is used in an ensemble-averaged version of the dynamic model. This produces local model parameters that only depend on the statistical properties of the flow. An important property of the ensemble-averaged dynamic procedure is that it does not require any spatial averaging and can thus be used in fully inhomogeneous flows. Also, the ensemble of LES provides statistics of the large-scale velocity that can be used for building new models for the subgrid-scale stress tensor. The ensemble-averaged dynamic procedure has been implemented with various models for three flows: decaying isotropic turbulence, forced isotropic turbulence, and the time-developing plane wake. It is found that the results are almost independent of the number of LES in the statistical ensemble provided that the ensemble contains at least 16 realizations. C1 Free Univ Brussels, Assoc Euratom Etat Belge, B-1050 Brussels, Belgium. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Carati, D (reprint author), Free Univ Brussels, Assoc Euratom Etat Belge, CP 231, B-1050 Brussels, Belgium. NR 20 TC 4 Z9 4 U1 0 U2 1 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH ST, NEW YORK, NY 10011-4221 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD MAR 25 PY 2002 VL 455 BP 195 EP 212 DI 10.1017/S0022112001007467 PG 18 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 540AA UT WOS:000174904700009 ER PT J AU Jacqmin, D AF Jacqmin, D TI Very, very fast wetting SO JOURNAL OF FLUID MECHANICS LA English DT Article ID CUSPED INTERFACES; SURFACE AB Just after formation, optical fibres are wetted stably with acrylate at capillary numbers routinely exceeding 1000. It is hypothesized that this is possible because of dissolution of air into the liquid coating. A lubrication/boundary integral analysis that includes gas diffusion and solubility is developed. It is applied using conservatively estimated solubility and diffusivity coefficients and solutions are found that are consistent with industry practice and with the hypothesis. The results also agree with the claim of Deneka, Kar & Mensah (1988) that the use of high-solubility gases to bathe a wetting line allows significantly greater wetting speeds. The solutions indicate a maximum speed of wetting which increases with gas solubility and with reduction in wetting-channel diameter. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Jacqmin, D (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 21 TC 13 Z9 13 U1 0 U2 5 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH ST, NEW YORK, NY 10011-4221 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD MAR 25 PY 2002 VL 455 BP 347 EP 358 DI 10.1017/S0022112001007492 PG 12 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 540AA UT WOS:000174904700016 ER PT J AU Andersen, DT Pollard, WH McKay, CP Heldmann, J AF Andersen, DT Pollard, WH McKay, CP Heldmann, J TI Cold springs in permafrost on Earth and Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article DE Arctic; permafrost; hydrology; springs; astrobiology; Mars ID SURFACE RUNOFF; SYSTEM; WATER AB [1] Perennial springs located on west central Axel Heiberg Island in the Canadian High Arctic occur in a region with a mean annual air temperature of -15degreesC and flow through continuous permafrost 600 m thick. The spring water is a low- temperature (up to 6 degreesC) brine that maintains constant discharge temperatures and flow rates throughout the year. Here we report on observations of temperature and discharge rate of these springs and develop a combined flow and thermal model of the subsurface flow using the measured geothermal gradient. We also consider the implications these springs have for the search for similar environments, past or present, on Mars. C1 McGill Univ, Dept Geog, Montreal, PQ H3A 2K6, Canada. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Andersen, DT (reprint author), McGill Univ, Dept Geog, 805 Sherbrooke St W, Montreal, PQ H3A 2K6, Canada. NR 19 TC 34 Z9 35 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 2002 VL 107 IS E3 AR 5015 DI 10.1029/2000JE001436 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 609LQ UT WOS:000178905400002 ER PT J AU Cerf, NJ Bourennane, M Karlsson, A Gisin, N AF Cerf, NJ Bourennane, M Karlsson, A Gisin, N TI Security of quantum key distribution using d-level systems SO PHYSICAL REVIEW LETTERS LA English DT Article ID CRYPTOGRAPHY; CLONING; INFORMATION; PROTOCOL AB We consider two quantum cryptographic schemes relying on encoding the key into qudits, i.e., quantum states in a d-dimensional Hilbert space. The first cryptosystem uses two mutually unbiased bases (thereby extending the BB84 scheme), while the second exploits all d + 1 available such bases (extending the six-state protocol for qubits). We derive the information gained by a potential eavesdropper applying a cloning-based individual attack, along with an upper bound on the error rate that ensures unconditional security against coherent attacks. C1 Free Univ Brussels, Ecole Polytech, B-1050 Brussels, Belgium. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Royal Inst Technol, Dept Microelect & Informat Technol, Electrum 229, SE-164 Kista, Sweden. Univ Geneva, GAP Opt, Geneva 4, Switzerland. RP Cerf, NJ (reprint author), Free Univ Brussels, Ecole Polytech, CP 165, B-1050 Brussels, Belgium. NR 20 TC 477 Z9 493 U1 5 U2 26 PU AMERICAN 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 MAR 25 PY 2002 VL 88 IS 12 AR 127902 DI 10.1103/PhysRevLett.88.127902 PG 4 WC Physics, Multidisciplinary SC Physics GA 533QP UT WOS:000174542000072 PM 11909502 ER PT J AU Maiti, A Svizhenko, A Anantram, MP AF Maiti, A Svizhenko, A Anantram, MP TI Electronic transport through carbon nanotubes: Effects of structural deformation and tube chirality SO PHYSICAL REVIEW LETTERS LA English DT Article ID MANIPULATION; MOLECULES AB Atomistic simulations using a combination of classical force field and density-functional theory (DFT) show that carbon atoms remain essentially sp(2) coordinated in either bent tubes or tubes pushed by an atomically sharp atomic-force microscope (AFM) tip. Subsequent Green's-function-based transport calculations reveal that for armchair tubes there is no significant drop in conductance, while for zigzag tubes the conductance can drop by several orders of magnitude in AFM-pushed tubes. The effect can be attributed to simple stretching of the tube under tip deformation, which opens up an energy gap at the Fermi surface. C1 Accelrys Inc, San Diego, CA 92121 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Maiti, A (reprint author), Accelrys Inc, 9685 Scranton Rd, San Diego, CA 92121 USA. NR 23 TC 137 Z9 140 U1 3 U2 35 PU AMERICAN 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 MAR 25 PY 2002 VL 88 IS 12 AR 126805 DI 10.1103/PhysRevLett.88.126805 PG 4 WC Physics, Multidisciplinary SC Physics GA 533QP UT WOS:000174542000062 PM 11909492 ER PT J AU Sultenfuss, MA Martinez, AA Yamauchi, K Taga, M Pellis, NR Kulkarni, AD AF Sultenfuss, MA Martinez, AA Yamauchi, K Taga, M Pellis, NR Kulkarni, AD TI Nutrition and differential cellular immune function in simulated microgravity SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ Texas, Hlth Sci Ctr, Sch Med, Houston, TX 77030 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. 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 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 22 PY 2002 VL 16 IS 5 BP A983 EP A983 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 534PC UT WOS:000174593901433 ER PT J AU Yu, DSM Dalton, BP Barrett, JE AF Yu, DSM Dalton, BP Barrett, JE TI Body composition of rats on NASA Rodent Foodbar versus Purina lab Chow SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Space Life Sci, Moffett Field, CA 94035 USA. Lockheed Martin, Space Life Sci, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 22 PY 2002 VL 16 IS 5 BP A1026 EP A1026 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 534PC UT WOS:000174593901658 ER PT J AU Bernardi, G Holbrook, SJ Schmitt, RJ Crane, NL DeMartini, E AF Bernardi, G Holbrook, SJ Schmitt, RJ Crane, NL DeMartini, E TI Species boundaries, populations and colour morphs in the coral reef three-spot damselfish (Dascyllus trimaculatus) species complex SO PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES LA English DT Article DE Dascyllus trimaculatus; mitochondrial DNA; population genetics; phylogeography; species boundaries ID SERRANID FISH HYPOPLECTRUS; GREAT-BARRIER-REEF; GENETIC-RELATIONSHIPS; HAMLETS HYPOPLECTRUS; MARINE SPECIATION; LARVAL DURATION; CICHLID FISH; EVOLUTION; POMACENTRIDAE; PATTERNS AB Coloration patterns of tropical reef fishes is commonly used for taxonomic purposes, yet few studies have focused on the relationship between species boundaries and coloration types. The three-spot damselfish (Dascyllus trimaculatus) species complex comprises four species that vary both in geographical ranges and colour patterns making them an ideal model to study these relationships. We analysed the mitochondrial control region of 122 individuals from all four species collected from 13 localities. Individuals from two species (Dascyllus albisella and D. strasburgi) grouped into monophyletic clades, while the two other species (D. trimaculatus and D. auripinnis) were found to be paraphyletic. Coloration patterns were therefore not found to be good predictors of genetic isolation. In contrast, geographical origin was always consistent with the observed genetic pattern. C1 Univ Calif Santa Cruz, Dept Ecol & Evolutionary Biol, Santa Cruz, CA 95064 USA. Univ Calif Santa Barbara, Coastal Res Ctr, Inst Marine Sci, Santa Barbara, CA 93106 USA. Univ Calif Santa Barbara, Dept Ecol Evolut & Marine Biol, Santa Barbara, CA 93106 USA. Monterey Peninsula Coll, Div Nat Sci, Monterey, CA 93940 USA. NOAA, Natl Marine Fisheries Serv, SW Fisheries Sci Ctr, Honolulu Lab, Honolulu, HI 96822 USA. RP Bernardi, G (reprint author), Univ Calif Santa Cruz, Dept Ecol & Evolutionary Biol, Santa Cruz, CA 95064 USA. EM bernardi@biology.ucsc.edu RI Bernardi, Giacomo/F-6346-2011 OI Bernardi, Giacomo/0000-0002-8249-4678 NR 51 TC 51 Z9 52 U1 0 U2 18 PU ROYAL SOC PI LONDON PA 6-9 CARLTON HOUSE TERRACE, LONDON SW1Y 5AG, ENGLAND SN 0962-8452 J9 P ROY SOC B-BIOL SCI JI Proc. R. Soc. B-Biol. Sci. PD MAR 22 PY 2002 VL 269 IS 1491 BP 599 EP 605 DI 10.1098/rspb.2001.1922 PG 7 WC Biology; Ecology; Evolutionary Biology SC Life Sciences & Biomedicine - Other Topics; Environmental Sciences & Ecology; Evolutionary Biology GA 538WC UT WOS:000174837200008 PM 11916476 ER PT J AU Ruscic, B Wagner, AF Harding, LB Asher, RL Feller, D Dixon, DA Peterson, KA Song, Y Qian, XM Ng, CY Liu, JB Chen, WW AF Ruscic, B Wagner, AF Harding, LB Asher, RL Feller, D Dixon, DA Peterson, KA Song, Y Qian, XM Ng, CY Liu, JB Chen, WW TI On the enthalpy of formation of hydroxyl radical and gas-phase bond dissociation energies of water and hydroxyl SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Review ID MOLECULAR ELECTRONIC-STRUCTURE; PHOTOELECTRON-PHOTOION COINCIDENCE; HIGHER-ORDER CORRELATION; BASIS-SET CONVERGENCE; FULL CCSDT MODEL; HIGH-RESOLUTION; SYNCHROTRON-RADIATION; DIATOMIC-MOLECULES; OD RADICALS; THRESHOLD PHOTODETACHMENT AB In a recent letter (J. Phys. Chem. A, 2001, 105, 1), we argued that, although all major thermochemical tables recommend a value of DeltaHdegrees(f0)(OH) based on a spectroscopic approach, the correct value is 0.5 kcal/mol lower as determined from an ion cycle. In this paper, we expand upon and augment both the experimental and theoretical arguments presented in the letter. In particular, three separate experiments (mass-selected photoionization measurements, pulsed-field-ionization photoelectron spectroscopy measurements, and photoelectron-photoion coincidence measurements) utilizing the positive ion cycle to derive the O-H bond energy are shown to converge to a consensus value of the appearance energy AE(0)(OH+/H2O) = 146117 +/- 24 cm(-1) (18.116(2) +/- 0.003(0) eV). With the most accurate currently available zero kinetic energy photoionization value for the ionization energy IE(OH) = 104989 +/- 2 cm(-1), corroborated by a number of photoelectron measurements, this leads to D-0(H-OH) = 41128 +/- 24 cm(-1) = 117.59 +/- 0.07 kcal/mol. This corresponds to DeltaH(f0)(OH) = 8.85 +/- 0.07 kcal/mol and implies D-0(OH) = 35593 +/- 24 cm(-1) = 101.76 +/- 0.07 kcal/mol. These results are completely supported by the most sophisticated theoretical calculations ever performed on the HxO system, CCSD(T)/aug-cc-pVnZ, n = Q, 5, 6, and 7, extrapolated to the CBS limit and including corrections for core-valence effects, scalar relativistic effects, incomplete correlation recovery, and diagonal Born-Oppenheimer corrections. These calculations have an estimated theoretical error of less than or equal to0.2 kcal/mol based on basis set convergence properties. They reproduce the experimental results for dissociation energies, atomization energies, and ionization energies for the HxO system to within 0.0-0.2 kcal/mol. In contrast, the previously accepted values of the two successive bond dissociation energies of water differ from the current values by 0.5 kcal/mol. These values were derived from the spectroscopic determinations of D-0(OH) using a very short Birge-Sponer extrapolation on OH/OD A(1)Sigma(+). However, on the basis of a calculation of the A state potential energy curve (with a multireference single and double excitation wave function and an aug-cc-pV5Z basis set) and an exhaustive reanalyzis of the original measured data on both the A and B states of OH, the Birge-Sponer extrapolation can be demonstrated to significantly underestimate the bond dissociation energy, although only the last vibrational level was not observed experimentally. The recommended values of this paper affect a large number of other thermochemical quantities which directly or indirectly rely on or refer to D-0(H-OH), D-0(OH), or DeltaHdegrees(f)(OH). This is illustrated by an analysis of several reaction enthalpies, deprotonation enthalpies, and proton affinities. C1 Argonne Natl Lab, Div Chem, Argonne, IL 60439 USA. Pacific NW Natl Lab, William R Wiley Environm Mol Sci Lab, Richland, WA 99352 USA. Washington State Univ, Richland, WA 99352 USA. US DOE, Ames Lab, Ames, IA 50011 USA. Iowa State Univ, Dept Chem, Ames, IA 50011 USA. Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Div Chem Sci, Berkeley, CA 94720 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Ruscic, B (reprint author), Argonne Natl Lab, Div Chem, 9700 S Cass Ave, Argonne, IL 60439 USA. RI Ruscic, Branko/A-8716-2008 OI Ruscic, Branko/0000-0002-4372-6990 NR 138 TC 365 Z9 366 U1 4 U2 75 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5639 J9 J PHYS CHEM A JI J. Phys. Chem. A PD MAR 21 PY 2002 VL 106 IS 11 BP 2727 EP 2747 DI 10.1021/jp013909s PG 21 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 533VP UT WOS:000174551200041 ER PT J AU Hynes, RI Haswell, CA Chaty, S Shrader, CR Cui, W AF Hynes, RI Haswell, CA Chaty, S Shrader, CR Cui, W TI The evolving accretion disc in the black hole X-ray transient XTE J1859+226 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE accretion, accretion discs; binaries : close; stars : individual : XTE J1859+226 ID ULTRAVIOLET EXTINCTION CURVES; BINARY-SYSTEMS; MULTIWAVELENGTH CAMPAIGN; 1996 OUTBURST; GRO J1655-40; IRRADIATION; CANDIDATES; EVOLUTION; SHAPES; ATLAS AB We present HST RXTE, and UKIRT observations of the broad-band spectra of the black hole X-ray transient XTE J1859+226 during the decline from its 1999-2000 outburst. Our UV spectra define the 2175-Angstrom interstellar absorption feature very well and based on its strength we estimate E(B-V) = 0.58+/-0.12. Hence we deredden our spectra and follow the evolution of the spectral energy distribution on the decline from outburst. We find that the UV and optical data, and the X-ray thermal component when detectable, can be fitted with a simple blackbody model of an accretion disc heated by internal viscosity and X-ray irradiation, and extending to close to the last stable orbit around the black hole, although the actual inner radius cannot be well constrained. During, the decline we see the disc apparently evolving from a model with the edge dominated by irradiative heating, towards one where viscous heating is dominant everywhere. The outer disc radius also appears to decrease during the decline; we interpret this as evidence of a cooling wave moving inwards and discuss its implications for the disc instability model. Based on the normalization of our spectral fits we estimate a likely distance range of 4.6-8.0 kpc, although a value outside this range cannot securely be ruled out. C1 Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. Open Univ, Dept Phys & Astron, Milton Keynes MK7 6AA, Bucks, England. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Purdue Univ, Dept Phys, W Lafayette, IN 47907 USA. RP Hynes, RI (reprint author), Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. OI Cui, Wei/0000-0002-6324-5772; Chaty, Sylvain/0000-0002-5769-8601 NR 53 TC 65 Z9 65 U1 0 U2 1 PU BLACKWELL PUBLISHING LTD PI OXFORD PA 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD MAR 21 PY 2002 VL 331 IS 1 BP 169 EP 179 DI 10.1046/j.1365-8711.2002.05175.x PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 539BZ UT WOS:000174851000019 ER PT J AU Howell, LW AF Howell, LW TI A recommended procedure for estimating the cosmic-ray spectral parameter of a simple power law SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article DE cosmic ray; power law; maximum likelihood; calorimeter AB A simple power law model with single spectral index alpha(1) is believed to be an adequate description of the galactic cosmic-ray (GCR) proton flux at energies below 10(13) eV. Two procedures for estimating alpha(1)-the method of moments and maximum likelihood (ML)-are developed and their statistical performance are compared. The NIL procedure is shown to be the superior approach and is then generalized for application to real cosmic-ray data sets. Several other important results, such as the relationship between collecting power and detector energy resolution and inclusion of a non-Gaussian detector response function, are presented. These results have many practical benefits in the design phase of a cosmic-ray detector as they permit instrument developers to make important trade studies in design parameters as a function of one of the science objectives. (C) 2002 Elsevier Science B.V. All rights reserved. C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. RP Howell, LW (reprint author), NASA, George C Marshall Space Flight Ctr, Dept Space Sci, SD50-Cosm Ray Astrophys, Huntsville, AL 35812 USA. NR 4 TC 2 Z9 2 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD MAR 21 PY 2002 VL 480 IS 2-3 BP 741 EP 753 AR PII S0168-9002(01)01235-9 DI 10.1016/S0168-9002(01)01235-9 PG 13 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 545YM UT WOS:000175245200047 ER PT J AU Frehlich, R Kavaya, MJ AF Frehlich, R Kavaya, MJ TI Comment on "Heterodyne lidar returns in the turbulent atmosphere: performance evaluation of simulated systems" SO APPLIED OPTICS LA English DT Article ID 3-DIMENSIONAL RANDOM-MEDIA; COHERENT LASER-RADAR; REFRACTIVE TURBULENCE; NUMERICAL-SIMULATION; WAVE-PROPAGATION; SCINTILLATION; EFFICIENCY; VARIANCE; SPECTRUM AB The explanation proposed by Belmonte and Rye [Appl. Opt, 39, 2401 (2000)] for the difference between simulation and the zero-order theory for heterodyne lidar returns in a turbulent atmosphere is incorrect. The theoretical expansion the authors considered is not developed under a square-law structure-function approximation (random-wedge atmosphere). Agreement between the simulations and the zero-order term of the theoretical expansion is produced for the limit of statistically independent paths (bistatic operation with large transmitter-receiver separation) when the simulations correctly include the large-scale gradients of the turbulent atmosphere. (C) 2002 Optical Society of America. C1 Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80309 USA. NASA, Langley Space Flight Ctr, Hampton, VA 23681 USA. RP Frehlich, R (reprint author), Univ Colorado, Cooperat Inst Res Environm Sci, Campus Box 216, Boulder, CO 80309 USA. EM rgf@cires.colorado.edu; m.j.kavaya@larc.nasa.gov NR 27 TC 2 Z9 2 U1 2 U2 5 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 2002 VL 41 IS 9 BP 1595 EP 1600 DI 10.1364/AO.41.001595 PG 6 WC Optics SC Optics GA 533KZ UT WOS:000174529900001 PM 11921786 ER PT J AU Gregg, WW Conkright, ME O'Reilly, JE Patt, FS Wang, MHH Yoder, JA Casey, NW AF Gregg, WW Conkright, ME O'Reilly, JE Patt, FS Wang, MHH Yoder, JA Casey, NW TI NOAA-NASA coastal zone color scanner reanalysis effort SO APPLIED OPTICS LA English DT Article ID RAYLEIGH RADIANCE CONTRIBUTIONS; SPECTRAL REFLECTANCE; MULTIPLE-SCATTERING; MERCHANT SHIPS; IN-SITU; CHLOROPHYLL; OCEAN; AEROSOL; PHYTOPLANKTON; CALIBRATION AB Satellite observations of global ocean chlorophyll span more than two decades. However, incompatibilities between processing algorithms prevent us from quantifying natural variability. We applied a comprehensive reanalysis to the Coastal Zone Color Scanner (CZCS) archive, called the National Oceanic and Atmospheric Administration and National Aeronautics and Space Administration (NOAA-NASA) CZCS reanalysis (NCR) effort. NCR consisted of (1) algorithm improvement (AI), where CZCS processing algorithms were improved with modernized atmospheric correction and bio-optical algorithms and (2) blending where in situ data were incorporated into the CZCS AI to minimize residual errors. Global spatial and seasonal patterns of NCR chlorophyll indicated remarkable correspondence with modern sensors, suggesting compatibility. The NCR permits quantitative analyses of interannual and interdecadal trends in global ocean chlorophyll. (C) 2002 Optical Society of America. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NOAA, Ocean Climate Lab, Natl Oceanog Data Ctr, Silver Spring, MD 20910 USA. NOAA, Natl Marine Fisheries Serv, Narragansett Lab, Narragansett, RI 02882 USA. Sci Applicat Int Corp, Gen Sci Corp, Beltsville, MD 20707 USA. Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Rhode Isl, Grad Sch Oceanog, Narragansett, RI 02882 USA. Sci Syst & Applicat Inc, Lanham, MD 20706 USA. RP Gregg, WW (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM gregg@cabin.gsfc.nasa.gov RI Wang, Menghua/F-5631-2010 OI Wang, Menghua/0000-0001-7019-3125 NR 30 TC 20 Z9 21 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 2002 VL 41 IS 9 BP 1615 EP 1628 DI 10.1364/AO.41.001615 PG 14 WC Optics SC Optics GA 533KZ UT WOS:000174529900004 PM 11921788 ER PT J AU Koch, GJ Petros, M Yu, JR Singh, UN AF Koch, GJ Petros, M Yu, JR Singh, UN TI Precise wavelength control of a single-frequency pulsed Ho : Tm : YLF laser SO APPLIED OPTICS LA English DT Article AB We demonstrate wavelength control of a single-frequency diode-pumped Ho:Tm:YLF laser by referencing its wavelength to an absorption line of carbon dioxide. We accomplish this wavelength control by injection seeding with a cw Ho:Tm:YLF laser that can be tuned over or stabilized to carbon dioxide or water vapor lines. We show that the pulsed laser can be scanned precisely over an absorption line of carbon dioxide by scanning the injection seed laser wavelength. We locked the pulsed laser to within 18.5 MHz of the absorption line center by stabilizing the injection seed on the line center. The single-frequency pulsed output, intended for use as a transmitter for differential absorption lidar detection of atmospheric carbon dioxide and water vapor and for coherent detection of wind, is 100 mJ per pulse at a 5-Hz repetition rate. (C) 2002 Optical Society of America. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Sci & Technol Corp, Hampton, VA 23666 USA. RP Koch, GJ (reprint author), NASA, Langley Res Ctr, Mail Stop 474, Hampton, VA 23681 USA. EM g.j.koch@larc.nasa.gov NR 7 TC 39 Z9 41 U1 4 U2 13 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 2002 VL 41 IS 9 BP 1718 EP 1721 DI 10.1364/AO.41.001718 PG 4 WC Optics SC Optics GA 533KZ UT WOS:000174529900017 PM 11921801 ER PT J AU Steck, T AF Steck, T TI Methods for determining regularization for atmospheric retrieval problems SO APPLIED OPTICS LA English DT Article ID TROPOSPHERIC OZONE; PROFILES AB The atmosphere of Earth has already been investigated by several spaceborne instruments, and several further instruments will be launched, e.g,, NASA's Earth Observing System Aura platform and the European Space Agency's Environmental Satellite. To stabilize the results in atmospheric retrievals, constraints are used in the iteration process. Therefore hard constraints (discretization of the retrieval g-rid) and soft constraints (regularization operators) are included in the retrieval. Tikhonov regularization is often used as a soft constraint. In this study, different types of Tikhonov operator were compared, and several new methods were developed to determine the optimal strength of the constraint operationally. The resulting regularization parameters were applied successfully to an ozone retrieval from simulated nadir sounding spectra like those expected to be measured by the Tropospheric Emission Spectrometer, which is part of the Aura platform. Retrievals were characterized by means of estimated error, averaging kernel, vertical resolution, and degrees of freedom. (C) 2002 Optical Society of America. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Forschungszentrum Karlsruhe, Inst Meteorol & Klimaforsch, D-76021 Karlsruhe, Germany. RP Steck, T (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr MS 183-301, Pasadena, CA 91109 USA. EM tilman.steck@imk.fzk.de NR 15 TC 87 Z9 87 U1 0 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 2002 VL 41 IS 9 BP 1788 EP 1797 DI 10.1364/AO.41.001788 PG 10 WC Optics SC Optics GA 533KZ UT WOS:000174529900027 PM 11921810 ER PT J AU Leitch, EM Pryke, C Halverson, NW Kovac, J Davidson, G Laroque, S Schartman, E Yamasaki, J Carlstrom, JE Holzapfel, WL Dragovan, M Cartwright, JK Mason, BS Padin, S Pearson, TJ Readhead, ACS Shepherd, MC AF Leitch, EM Pryke, C Halverson, NW Kovac, J Davidson, G Laroque, S Schartman, E Yamasaki, J Carlstrom, JE Holzapfel, WL Dragovan, M Cartwright, JK Mason, BS Padin, S Pearson, TJ Readhead, ACS Shepherd, MC TI Experiment design and first season observations with the Degree Angular Scale Interferometer SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations; techniques : interferometric ID MICROWAVE; FLUCTUATIONS; FOREGROUNDS; RADIATION; EMISSION AB We describe the instrumentation, experiment design, and data reduction for the first season of observations with the Degree Angular Scale Interferometer ( DASI), a compact microwave interferometer designed to measure anisotropy of the cosmic microwave background (CMB) on degree and subdegree scales (l similar or equal to100- 900). The telescope was deployed at the Amundsen-Scott South Pole Research Station during the 1999 2000 austral summer, and we conducted observations of the CMB throughout the following austral winter. In its first season of observations, DASI has mapped CMB fluctuations in 32 fields, each 3.degrees4 across, with high sensitivity. C1 Univ Chicago, Chicago, IL 60637 USA. Univ Calif Berkeley, Berkeley, CA 94720 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Pasadena, CA 91125 USA. RP Leitch, EM (reprint author), Univ Chicago, 5640 S Ellis Ave, Chicago, IL 60637 USA. RI Holzapfel, William/I-4836-2015; Pearson, Timothy/N-2376-2015 OI Pearson, Timothy/0000-0001-5213-6231 NR 25 TC 44 Z9 44 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 2002 VL 568 IS 1 BP 28 EP 37 DI 10.1086/338878 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 531VN UT WOS:000174438100004 ER PT J AU Halverson, NW Leitch, EM Pryke, C Kovac, J Carlstrom, JE Holzapfel, WL Dragovan, M Cartwright, JK Mason, BS Padin, S Pearson, TJ Readhead, ACS Shepherd, MC AF Halverson, NW Leitch, EM Pryke, C Kovac, J Carlstrom, JE Holzapfel, WL Dragovan, M Cartwright, JK Mason, BS Padin, S Pearson, TJ Readhead, ACS Shepherd, MC TI Degree Angular Scale Interferometer first results: A measurement of the cosmic microwave background angular power spectrum SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations; techniques : interferometric ID INFLATIONARY UNIVERSE SCENARIO; FLUCTUATIONS; ANISOTROPY; MAPS; PERTURBATIONS; RADIATION; FLATNESS; HORIZON AB We present measurements of anisotropy in the cosmic microwave background ( CMB) from the first season of observations with the Degree Angular Scale Interferometer (DASI). The instrument was deployed at the South Pole in the austral summer 1999 2000, and we made observations throughout the following austral winter. We present a measurement of the CMB angular power spectrum in the range 100 < l < 900 in nine bands with fractional uncertainties in the range 10%-20% and dominated by sample variance. In this paper, we review the formalism used in the analysis, in particular the use of constraint matrices to project out contaminants such as ground and point source signals and to test for correlations with diffuse foreground templates. We find no evidence of foregrounds other than point sources in the data, and we find a maximum likelihood temperature spectral index beta = -0.1 +/- 2(1 sigma), consistent with CMB. We detect a first peak in the power spectrum at l 2similar to00, in agreement with previous experiments. In addition, we detect a peak in the power spectrum at l similar to550 and power of similar magnitude at l similar to800, which are consistent with the second and third harmonic peaks predicted by adiabatic inflationary cosmological models. C1 Univ Chicago, Chicago, IL 60637 USA. Univ Calif Berkeley, Berkeley, CA 94720 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Pasadena, CA 91125 USA. RP Halverson, NW (reprint author), Univ Chicago, 5640 S Ellis Ave, Chicago, IL 60637 USA. RI Holzapfel, William/I-4836-2015; Pearson, Timothy/N-2376-2015 OI Pearson, Timothy/0000-0001-5213-6231 NR 42 TC 603 Z9 609 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 2002 VL 568 IS 1 BP 38 EP 45 DI 10.1086/338879 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 531VN UT WOS:000174438100005 ER PT J AU Pryke, C Halverson, NW Leitch, EM Kovac, J Carlstrom, JE Holzapfel, WL Dragovan, M AF Pryke, C Halverson, NW Leitch, EM Kovac, J Carlstrom, JE Holzapfel, WL Dragovan, M TI Cosmological parameter extraction from the first season of observations with the Degree Angular Scale Interferometer SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations; techniques : interferometric ID MICROWAVE BACKGROUND ANISOTROPIES; INFLATIONARY UNIVERSE; PERTURBATIONS AB The Degree Angular Scale Interferometer (DASI) has measured the power spectrum of the cosmic microwave background anisotropy over the range of spherical harmonic multipoles 100 < l < 900. We compare these data, in combination with the COBE DMR results, to a seven-dimensional grid of adiabatic cold dark matter (CDM) models. Adopting the priors h > 0.45 and 0.0 less than or equal to tauc less than or equal to 0.4, we find that the total density of the universe Omega(tot) = 1.04 +/- 0.06 and the spectral index of the initial scalar fluctuations n(s) = 1.01(-0.06)(+0.08) 0 : 06 in accordance with the predictions of inflationary theory. In addition, we find that the physical density of baryons Omega(b)h(2) = 0.022(-0.003)(+0.004), and the physical density of cold dark matter Omega(cdm) h(2) = 0.14 +/- 0.04. This value of Omega(b)h(2) is consistent with that derived from measurements of the primeval deuterium abundance combined with big bang nucleosynthesis theory. Using the result of the Hubble Space Telescope (HST) Key Project, h = 0.72 +/- 0.08, we nd that Omega(tot) = 1.00 +/- 0.04, the matter density Omega(m) = 0.40 +/- 0.15, and the vacuum energy density Omega(Lambda) = 0.60 +/- 0.15. (All 68% confidence limits. C1 Univ Chicago, Chicago, IL 60637 USA. Univ Calif Berkeley, Berkeley, CA 94720 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Univ Chicago, 5640 S Ellis Ave, Chicago, IL 60637 USA. RI Holzapfel, William/I-4836-2015 NR 30 TC 276 Z9 276 U1 0 U2 4 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 MAR 20 PY 2002 VL 568 IS 1 BP 46 EP 51 DI 10.1086/338880 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 531VN UT WOS:000174438100006 ER PT J AU Stern, D Moran, EC Coil, AL Connolly, A Davis, M Dawson, S Dey, A Eisenhardt, P Elston, R Graham, JR Harrison, F Helfand, DJ Holden, B Mao, P Rosati, P Spinrad, H Stanford, SA Tozzi, P Wu, KL AF Stern, D Moran, EC Coil, AL Connolly, A Davis, M Dawson, S Dey, A Eisenhardt, P Elston, R Graham, JR Harrison, F Helfand, DJ Holden, B Mao, P Rosati, P Spinrad, H Stanford, SA Tozzi, P Wu, KL TI Chandra detection of a type II quasar at z=3. 288 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; galaxies : active; quasars : individual (CXO J084837.9+445352); X-rays : galaxies ID REDSHIFT RADIO GALAXIES; ACTIVE GALACTIC NUCLEI; HUBBLE DEEP FIELD; LINE SEYFERT-1 GALAXIES; X-RAY; INFRARED-SPECTROSCOPY; DISTANT GALAXIES; UNIFIED SCHEMES; ALPHA EMISSION; SKY SURVEY AB We report on observations of a type II quasar at redshift z = 3.288, identified as a hard X-ray source in a 185 ks observation with the Chandra X-Ray Observatory and as a high-redshift photometric candidate from deep, multiband optical imaging. CXO J084837.9+ 445352 ( hereafter CXO 52) shows an unusually hard X-ray spectrum from which we infer an absorbing column density N-H = (4.8 +/- 2.1) x 10(23) cm(-2) (90% confidence) and an implied unabsorbed 2-10 keV rest-frame luminosity of L2-10 = 3.3 x 10(44) ergs s(-1), well within the quasar regime. Hubble Space Telescope imaging shows CXO 52 to be elongated with slight morphological differences between the WFPC2 F814W and NICMOS F160W bands. Optical and near-infrared spectroscopy of CXO 52 shows high-ionization emission lines with velocity widths similar to1000 km s(-1) and flux ratios similar to a Seyfert 2 galaxy or radio galaxy. The latter are the only class of high-redshift type II luminous active galactic nuclei that have been extensively studied to date. Unlike radio galaxies, however, CXO 52 is radio quiet, remaining undetected at radio wavelengths to fairly deep limits, f(4.8GHz) < 40 μJy. High-redshift type II quasars, expected from unification models of active galaxies and long thought necessary to explain the X-ray background, are poorly constrained observationally, with few such systems known. We discuss recent observations of similar type II quasars and detail search techniques for such systems, namely, (1) X-ray selection, (2) radio selection, (3) multicolor imaging selection, and (4) narrowband imaging selection. Such studies are likely to begin identifying luminous, high-redshift type II systems in large numbers. We discuss the prospects for these studies and their implications for our understanding of the X-ray background. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Univ Pittsburgh, Dept Phys & Astron, Pittsburgh, PA 15260 USA. Kitt Peak Natl Observ, Tucson, AZ 85719 USA. Univ Florida, Dept Astron, Gainesville, FL 32611 USA. CALTECH, Div Phys Math & Astron, Pasadena, CA 91125 USA. Columbia Univ, Dept Astron, New York, NY 10027 USA. Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94550 USA. Univ Calif Davis, Dept Phys, Davis, CA 95616 USA. European So Observ, D-85748 Garching, Germany. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Osserv Astron Trieste, I-34131 Trieste, Italy. RP Stern, D (reprint author), CALTECH, Jet Prop Lab, Mail Stop 169-327, Pasadena, CA 91109 USA. NR 100 TC 130 Z9 130 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 2002 VL 568 IS 1 BP 71 EP 81 DI 10.1086/338886 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 531VN UT WOS:000174438100008 ER PT J AU Turner, TJ Romano, P Kraemer, SB George, IM Yaqoob, T Crenshaw, DM Storm, J Alloin, D Lazzaro, D Da Silva, L Pritchard, JD Kriss, G Zheng, W Mathur, S Wang, J Dobbie, P Collins, NR AF Turner, TJ Romano, P Kraemer, SB George, IM Yaqoob, T Crenshaw, DM Storm, J Alloin, D Lazzaro, D Da Silva, L Pritchard, JD Kriss, G Zheng, W Mathur, S Wang, J Dobbie, P Collins, NR TI The spectral energy distribution of the Seyfert galaxy Ton S180 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (Ton S180); galaxies : nuclei; galaxies : Seyfert ID X-RAY-PROPERTIES; ACTIVE GALACTIC NUCLEI; ASCA OBSERVATIONS; ABSORPTION LINES; HIGH-STATE; QUASARS; EMISSION; VARIABILITY; CONTINUUM; CLOUDS AB We present spectral results from a multisatellite, broadband campaign on the narrow-line Seyfert 1 galaxy Ton S180 ( PHL 912) performed at the end of 1999. We discuss the spectral energy distribution ( SED) of the source, combining simultaneous Chandra, ASCA, and Extreme Ultraviolet Explorer data with contemporaneous Far Ultraviolet Spectroscopic Explorer ( FUSE), Hubble Space Telescope, and ground-based optical and infrared data. The resulting SED shows that most of the energy is emitted in the 10-100 eV regime, which must be dominated by the primary energy source. No spectral turnover is evident in the UV regime. This, the strong soft X-ray emission, and the overall shape of the SED indicate that emission from the accretion disk peaks between 15 and 100 eV. High-resolution FUSE spectra showing UV absorption due to O vi and the lack of detectable X-ray absorption in the Chandra spectrum demonstrate the presence of a low column density of highly ionized gas along our line of sight. The highly ionized state of the circumnuclear gas is most likely linked to the high luminosity and steep spectrum of the active nucleus. Given the strong ionizing flux in Ton S180, it is possible that the clouds within a few tens of light days of the central source are too highly ionized to produce much line emission. Thus, the narrow width of the emission lines in Ton S180 is due to the emission arising from large radii. C1 Univ Maryland Baltimore Cty, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Catholic Univ Amer, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. Johns Hopkins Univ, Dept Phys & Astron, Ctr Astrophys Sci, Baltimore, MD 21218 USA. Georgia State Univ, Dept Phys & Astron, Atlanta, GA 30303 USA. AIP, D-14482 Potsdam, Germany. European So Observ, Santiago 19, Chile. Observ nacl, Dept Astron, BR-20921400 Rio De Janeiro, Brazil. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Leicester, Astron Grp, Leicester LE1 7RH, Leics, England. Sci Syst & Applicat Inc, Lanham, MD 20706 USA. RP Turner, TJ (reprint author), Univ Maryland Baltimore Cty, Dept Phys, Joint Ctr Astrophys, 1000 Hilltop Circle, Baltimore, MD 21250 USA. RI Lazzaro, Daniela/I-3509-2012; OI Lazzaro, Daniela/0000-0002-4470-6043; Storm, Jesper/0000-0002-8627-6096; Romano, Patrizia/0000-0003-0258-7469 NR 82 TC 23 Z9 23 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 2002 VL 568 IS 1 BP 120 EP 132 DI 10.1086/338925 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 531VN UT WOS:000174438100012 ER PT J AU Giles, AB Hill, KM Strohmayer, TE Cummings, N AF Giles, AB Hill, KM Strohmayer, TE Cummings, N TI Burst oscillation periods from 4U 1636-53: A constraint on the binary Doppler modulation SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : general; stars : individual (4U 1636-53); stars : neutron; X-rays : binaries; X-rays : stars ID X-RAY BINARIES; BRIGHTNESS OSCILLATIONS; COHERENT OSCILLATIONS; EVOLUTION; PHASE AB The burst oscillations seen during type I X-ray bursts from low-mass X-ray binaries typically evolve in period toward an asymptotic limit that likely reflects the spin of the underlying neutron star. If the underlying period is stable enough, measurement of it at different orbital phases may allow a detection of the Doppler modulation caused by the motion of the neutron star with respect to the center of mass of the binary system. Testing this hypothesis requires enough X-ray bursts and an accurate optical ephemeris to determine the binary phases at which they occurred. We present here a study of the distribution of asymptotic burst oscillation periods for a sample of 26 bursts from 4U 1636-53 observed with the Rossi X-Ray Timing Explorer. The burst sample includes both archival and proprietary data and spans more than 4.5 yr. We also present new optical light curves of V801 Arae, the optical counterpart of 4U 1636-53, obtained during 1998-2001. We use these optical data to re ne the binary period measured by Augusteijn et al. to 3.7931206(152) hr. We show that a subset of similar to70% of the bursts form a tightly clustered distribution of asymptotic periods consistent with a period stability of similar to1 x 10(-4). The tightness of this distribution, made up of bursts spanning more than 4 yr in time, suggests that the underlying period is highly stable, with a time to change the period of similar to3 x 10(4) yr. This is comparable to similar numbers derived for X-ray pulsars. We investigate the period and orbital phase data for our burst sample and show that it is consistent with binary motion of the neutron star, with v(ns) sin i < 38 and 50 km s(-1) at 90% and 99% confidence, respectively. We use this limit as well as previous radial velocity data to constrain the binary geometry and component masses in 4U 1636-53. Our results suggest that unless the neutron star is significantly more massive than 1.4 M., the secondary is unlikely to have a mass as large as 0.36 M., the mass estimated assuming that it is a main-sequence star that fills its Roche lobe. We show that a factor of &SIM;3 increase in the number of bursts with asymptotic period measurements should allow a detection of the neutron star velocity. C1 Univ Tasmania, Sch Math & Phys, Hobart, Tas 7001, Australia. Spur Technol Pty Ltd, Mt Rumney, Tas 7170, Australia. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Giles, AB (reprint author), Univ Tasmania, Sch Math & Phys, GPO Box 252-21, Hobart, Tas 7001, Australia. NR 30 TC 27 Z9 27 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 2002 VL 568 IS 1 BP 279 EP 288 DI 10.1086/338890 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 531VN UT WOS:000174438100028 ER PT J AU Arzoumanian, Z Chernoff, DF Cordes, JM AF Arzoumanian, Z Chernoff, DF Cordes, JM TI The velocity distribution of isolated radio pulsars SO ASTROPHYSICAL JOURNAL LA English DT Article DE methods : statistical; pulsars : general; stars : neutron ID ISOLATED NEUTRON-STARS; GAMMA-RAY BURSTS; GALACTIC DISTRIBUTION; PERIOD PULSARS; KICK VELOCITY; BLACK-HOLE; EVOLUTION; BINARIES; SYSTEMS; SEARCH AB We infer the velocity distribution of radio pulsars based on large-scale 0.4 GHz pulsar surveys. We do so by modeling the evolution of the locations, velocities, spins, and radio luminosities of pulsars, calculating pulsed flux according to a beaming model and random orientation angles of spin and beam, applying selection effects of pulsar surveys, and comparing model distributions of measurable pulsar properties with survey data using a likelihood function. The surveys analyzed have well-defined characteristics and cover 95% of the sky. We maximize the likelihood in a six-dimensional space of observables P, (P) over dot, DM, \b\, mu, and F (period, period derivative, dispersion measure, Galactic latitude, proper motion, and flux density, respectively). The models we test are described by 12 parameters that characterize a population's birth rate, luminosity, shutoff of radio emission, birth locations, and birth velocities. We infer that the radio beam luminosity ( 1) is comparable to the energy flux of relativistic particles in models for spin-driven magnetospheres, signifying that radio emission losses reach nearly 100% for the oldest pulsars, and ( 2) scales approximately as (E) over dot(1/2), which in magnetosphere models is proportional to the voltage drop available for acceleration of particles. We find that a two-component velocity distribution with characteristic velocities of 90 and 500 km s(-1) is greatly preferred to any one-component distribution; this preference is largely immune to variations in other population parameters, such as the luminosity or distance scale or the assumed spin-down law. We explore some consequences of the preferred birth velocity distribution: (1) roughly 50% of pulsars in the solar neighborhood will escape the Galaxy, while similar to15% have velocities greater than 1000 km s(-1); (2) observational bias against high-velocity pulsars is relatively unimportant for surveys that reach high Galactic |z| distances but is severe for spatially bounded surveys; (3) an important low-velocity population exists that increases the fraction of neutron stars retained by globular clusters and is consistent with the number of old objects that accrete from the interstellar medium; (4) under standard assumptions for supernova remnant expansion and pulsar spin-down, similar to10% of pulsars younger than 20 kyr will appear to lie outside of their host remnants. Finally, we comment on the rami cations of our birth velocity distribution for binary survival and the population of inspiraling binary neutron stars relevant to some GRB models and potential sources for LIGO. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Ithaca, NY 14853 USA. RP Arzoumanian, Z (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 682, Greenbelt, MD 20771 USA. NR 74 TC 324 Z9 332 U1 1 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 2002 VL 568 IS 1 BP 289 EP 301 DI 10.1086/338805 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 531VN UT WOS:000174438100029 ER PT J AU Stothers, RB AF Stothers, RB TI Outflow-induced dynamical and radiative instability in stellar envelopes with an application to luminous blue variables and Wolf-Rayet stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : evolution; stars : mass loss; stars : oscillations; stars : variables : other; stars : Wolf-Rayet ID MASS-LOSS RATES; OPTICALLY THICK WINDS; DRIVEN WINDS; P-CYGNI; ANGULAR-MOMENTUM; AG-CARINAE; O-STARS; EVOLUTION; MODELS; SUPERGIANTS AB Theoretical models of the remnants of massive stars in a very hot, post-red-supergiant phase display no obvious instability if standard assumptions are made. However, the brightest observed classical luminous blue variables (LBVs) may well belong to such a phase. A simple time-dependent theory of moving stellar envelopes is developed in order to treat deep hydrodynamical disturbances caused by surface mass loss and to test the moving envelopes for dynamical instability. In the case of steady state outflow, the theory reduces to the equivalent of the Castor, Abbott, & Klein formulation for optically thick winds at distances well above the sonic point. The time-dependent version indicates that the brightest and hottest LBVs are both dynamically and radiatively unstable, as a result of the substantial lowering of the generalized Eddington luminosity limit by the mass-loss acceleration. It is suggested that dynamical instability, by triggering secular cycles of mass loss, is primarily what differentiates LBVs from the purely radiatively unstable Wolf-Rayet stars. Furthermore, when accurate main-sequence mass-loss rates are used to calculate the evolutionary tracks, the predicted surface hydrogen and nitrogen abundances of the blue remnants agree much better with observations of the brightest LBVs than before. C1 NASA, Inst Space Studies, Goddard Space Flight Ctr, New York, NY 10025 USA. RP Stothers, RB (reprint author), NASA, Inst Space Studies, Goddard Space Flight Ctr, 2880 Broadway, New York, NY 10025 USA. NR 85 TC 9 Z9 9 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 2002 VL 568 IS 1 BP 312 EP 323 DI 10.1086/338806 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 531VN UT WOS:000174438100031 ER PT J AU Marley, MS Seager, S Saumon, D Lodders, K Ackerman, AS Freedman, RS Fan, XH AF Marley, MS Seager, S Saumon, D Lodders, K Ackerman, AS Freedman, RS Fan, XH TI Clouds and chemistry: Ultracool dwarf atmospheric properties from optical and infrared colors SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : atmospheres; stars : low-mass, brown dwarfs ID ALL-SKY SURVEY; BROWN DWARFS; GLIESE 229B; DISCOVERY; MODELS; EVOLUTIONARY; JUPITER; 2MASS AB The optical and infrared colors of L and T dwarfs are sensitive to cloud sedimentation and chemical equilibrium processes in their atmospheres. The i'-z' versus J-K color-color diagram provides a window into diverse atmospheric processes mainly because different chemical processes govern each color, and cloud opacity largely affects J-K but not i'-z'. Using theoretical atmosphere models that include for the first time a self-consistent treatment of cloud formation, we present an interpretation of the i'-z' versus J-K color trends of known L and T dwarfs. We find that the i'-z' color is extremely sensitive to chemical equilibrium assumptions; chemical equilibrium models accounting for cloud sedimentation predict redder i'-z' colors by up to 2 mag-than models that neglect sedimentation. We explore the previously known J-K color trends in which objects first become redder, then bluer with decreasing effective temperature. Only models that include sedimentation of condensates are able to reproduce these trends. We find that the exact track of a cooling brown dwarf in J-K (and i'-z') is very sensitive to the details of clouds, in particular to the efficiency of sedimentation of condensates in its atmosphere. We also find that clouds still affect the strength of the J-, H-, and K-band fluxes of even the coolest T dwarfs. In addition, we predict the locus in the i'-z' versus J-K color-color diagram of brown dwarfs cooler than yet discovered. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Inst Adv Study, Princeton, NJ 08540 USA. Vanderbilt Univ, Dept Phys & Astron, Nashville, TN 37235 USA. Washington Univ, Dept Earth & Planetary Sci, Planetary Chem Lab, St Louis, MO 63130 USA. RP Marley, MS (reprint author), NASA, Ames Res Ctr, MS 245-5, Moffett Field, CA 94035 USA. RI Ackerman, Andrew/D-4433-2012; Marley, Mark/I-4704-2013 OI Ackerman, Andrew/0000-0003-0254-6253; NR 39 TC 211 Z9 211 U1 1 U2 5 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 2002 VL 568 IS 1 BP 335 EP 342 DI 10.1086/338800 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 531VN UT WOS:000174438100033 ER PT J AU Turmon, M Pap, JM Mukhtar, S AF Turmon, M Pap, JM Mukhtar, S TI Statistical pattern recognition for labeling solar active regions: application to SOHO/MDI imagery SO ASTROPHYSICAL JOURNAL LA English DT Article DE methods : analytical; methods : statistical; Sun : activity; Sun : faculae, plages; sunspots ID II K SPECTROHELIOGRAMS; MODEL; VARIABILITY; LIKELIHOOD; FIELD AB This paper presents a new application of statistical methods for identifying the various surface structures on the Sun that may contribute to observed changes in total and spectral solar irradiance. These structures are divided for our purposes into three types: quiet Sun, faculae, and sunspots (umbra and penumbra). Each region type is characterized by the observed data present at pixels of that type. Statistical models characterizing these observables are found from expert identification of a sample set of regions or unsupervised clustering. Information about the spatial continuity of regions is incorporated into the model via a prior distribution on the label image; the contribution of the prior can be interpreted as a regularizing term. Once the parameters de ning the models are fixed, the inference procedure becomes to maximize the probability of an image labeling given the observed data. This allows objective and automated classification of a large set of images. We describe the application of these procedures to computing labelings from synchronized full-disk high-resolution magnetic-field and light-intensity maps from the Michelson Doppler Imager experiment on the Solar and Heliospheric Observatory. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. CALTECH, Computat & Neurosci Program, Pasadena, CA 91125 USA. NASA, Goddard Earth Sci & Technol Ctr, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Turmon, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 34 TC 55 Z9 55 U1 0 U2 2 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 MAR 20 PY 2002 VL 568 IS 1 BP 396 EP 407 DI 10.1086/338681 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 531VN UT WOS:000174438100040 ER PT J AU Ramsey, BD Alexander, CD Apple, JA Benson, CM Dietz, KL Elsner, RF Engelhaupt, DE Ghosh, KK Kolodziejczak, JJ O'Dell, SL Speegle, CO Swartz, DA Weisskopf, MC AF Ramsey, BD Alexander, CD Apple, JA Benson, CM Dietz, KL Elsner, RF Engelhaupt, DE Ghosh, KK Kolodziejczak, JJ O'Dell, SL Speegle, CO Swartz, DA Weisskopf, MC TI First images from HERO, a hard X-ray focusing telescope SO ASTROPHYSICAL JOURNAL LA English DT Article DE balloons; instrumentation : detectors; stars : imaging telescopes; X-rays : general ID ENERGY AB We are developing a balloon-borne hard X-ray telescope that utilizes grazing-incidence optics. Termed HERO, for High-Energy Replicated Optics, the instrument will provide unprecedented sensitivity in the hard X-ray region and will achieve millicrab-level sensitivity in a typical 3 hr balloon-flight observation and 50 mucrab sensitivity on ultralong-duration flights. A recent proof-of-concept flight, featuring a small number of mirror shells, captured the first focused hard X-ray images of galactic X-ray sources. Full details of the pay-load, its expected future performance, and its recent measurements are provided. C1 NASA, Sci Directorate, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Alabama, Ctr Appl Opt, Huntsville, AL 35899 USA. Raytheon ITSS, Lanham, MD 20706 USA. NASA, Univ Space Res Assoc, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Ramsey, BD (reprint author), NASA, Sci Directorate, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. OI O'Dell, Stephen/0000-0002-1868-8056 NR 7 TC 48 Z9 48 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 2002 VL 568 IS 1 BP 432 EP 435 DI 10.1086/338801 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 531VN UT WOS:000174438100044 ER PT J AU Brown, TM Ferguson, HC O'Connell, RW Ohl, RG AF Brown, TM Ferguson, HC O'Connell, RW Ohl, RG TI Photospheric abundances of the hot stars in NGC 1399 and limits on the Fornax Cluster cooling flow SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : abundances; galaxies : elliptical and lenticular, cD galaxies : stellar content; ultraviolet : galaxies ID HORIZONTAL-BRANCH STARS; ULTRAVIOLET-UPTURN PHENOMENON; EVOLVED STELLAR POPULATIONS; EARLY-TYPE GALAXIES; SUBDWARF B-STAR; ELLIPTIC GALAXIES; SDB STARS; RADIATION; ATMOSPHERES; EVOLUTION AB We present far-UV spectroscopy of the giant elliptical galaxy NGC 1399, obtained with the Far Ultraviolet Spectroscopic Explorer. Of all quiescent ellipticals, NGC 1399 has the strongest known "UV upturn"- a sharp spectral rise shortward of 2500 Angstrom. It is now well established that this emission comes from hot horizontal branch stars and their progeny; however, the chemical composition of these stars has been the subject of a longstanding debate. For the first time in observations of any elliptical galaxy, our spectra clearly show photospheric metallic absorption lines within the UV upturn. The abundance of N is at 45% solar, Si is at 13% solar, and C is at 2% solar. Such abundance anomalies are a natural consequence of gravitational diffusion. These photospheric abundances fall in the range observed for subdwarf B stars of the Galactic field. Although NGC 1399 is at the center of the Fornax Cluster, we find no evidence for O vi cooling flow emission. The upper limit to lambdalambda1032, 1038 emission is 3.9 x 10(-15) ergs s(-1) cm(-2), equivalent to 0.14 M-. yr(-1) and less than the value predicted by simple cooling flow models of the NGC 1399 X-ray luminosity. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Brown, TM (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. OI Brown, Thomas/0000-0002-1793-9968 NR 33 TC 7 Z9 7 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 2002 VL 568 IS 1 BP L19 EP L22 DI 10.1086/340142 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 531VQ UT WOS:000174438300005 ER PT J AU Baer, LA Wade, CE Ronca, AE AF Baer, LA Wade, CE Ronca, AE TI Correlative analysis of behavioral and physiological concomitants of labor in pregnant rats. SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. 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 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 20 PY 2002 VL 16 IS 4 BP A393 EP A393 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 533MG UT WOS:000174533602179 ER PT J AU Gurun, G Fung, C Baer, L Wade, W Tou, J Martinez, D Grindeland, R AF Gurun, G Fung, C Baer, L Wade, W Tou, J Martinez, D Grindeland, R TI Effects of unweighting and rhGrowth hormone on rat growth hormone and IGF-1 SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Houston, Houston, TX 77004 USA. 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 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 20 PY 2002 VL 16 IS 4 BP A49 EP A50 PN 1 PG 2 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 533MG UT WOS:000174533600277 ER PT J AU Hilder, T Han, J Pope, M Borchers, C Dial, M Grindeland, R Graves, L AF Hilder, T Han, J Pope, M Borchers, C Dial, M Grindeland, R Graves, L TI The application of proteomics to study skeletal muscle atrophy following exposure to microgravity SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ N Carolina, Chapel Hill, NC 27599 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 2 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 20 PY 2002 VL 16 IS 4 BP A15 EP A15 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 533MG UT WOS:000174533600082 ER PT J AU Ortiz, RM Wade, CE Talamantes, F Ortiz, CL AF Ortiz, RM Wade, CE Talamantes, F Ortiz, CL TI Effects of vasopressin in fasting elephant seal pups SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ Calif Santa Cruz, Santa Cruz, CA 95064 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. 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 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 20 PY 2002 VL 16 IS 4 BP A46 EP A46 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 533MG UT WOS:000174533600258 ER PT J AU Shi, SJ Garcia, KM Meck, JV AF Shi, SJ Garcia, KM Meck, JV TI Effects of Temazepam (Restoril) on blood pressure and heart rate in astronauts on landing day. SO FASEB JOURNAL LA English DT Meeting Abstract C1 Wyle Labs, Cardiovasc Lab, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Cardiovasc Lab, Houston, TX 77058 USA. 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 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 20 PY 2002 VL 16 IS 4 BP A49 EP A49 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 533MG UT WOS:000174533600276 ER PT J AU Smith, SM O'Brien, KO Wastney, ME Abrams, S Davis-Street, JE Morukov, BV Larina, IM Lane, HW Shackelford, LC AF Smith, SM O'Brien, KO Wastney, ME Abrams, S Davis-Street, JE Morukov, BV Larina, IM Lane, HW Shackelford, LC TI Calcium kinetics during extended Spaceflight SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Johns Hopkins Univ, Bloomberg Sch Publ Hlth, Baltimore, MD USA. Metab Modeling Serv Ltd, Hamilton, New Zealand. Baylor Coll Med, Houston, TX 77030 USA. Enterprise Advisory Serv Inc, Houston, TX USA. IBMP, Moscow, Russia. 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 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 20 PY 2002 VL 16 IS 4 BP A224 EP A224 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 533MG UT WOS:000174533601243 ER PT J AU Stenger, M Evans, J Knapp, C Eddie, K McIntosh, C Simonson, S Stocks, J Moore, F Ziegler, M Patwardhan, A Brown, D Evetts, S Pemberton, K Vener, J Greenleaf, J AF Stenger, M Evans, J Knapp, C Eddie, K McIntosh, C Simonson, S Stocks, J Moore, F Ziegler, M Patwardhan, A Brown, D Evetts, S Pemberton, K Vener, J Greenleaf, J TI Differences between exercise training and passive acceleration training on cardiovascular responses to head-up tilt. SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ Kentucky, Lexington, KY 40506 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif San Diego, San Diego, CA 92103 USA. NR 0 TC 2 Z9 2 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 20 PY 2002 VL 16 IS 4 BP A47 EP A48 PN 1 PG 2 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 533MG UT WOS:000174533600266 ER PT J AU Sundaresan, A Yamauchi, K Pellis, NR Kulkarni, AD AF Sundaresan, A Yamauchi, K Pellis, NR Kulkarni, AD TI Lymphocyte functions and second messenger trans-membrane signalling is affected in mouse and human microgravity model systems. SO FASEB JOURNAL LA English DT Meeting Abstract C1 Wyle Labs, Biotechnol Program, Houston, TX 77058 USA. Univ Texas, Hlth Sci Ctr, Houston, TX USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. 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 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 20 PY 2002 VL 16 IS 4 BP A701 EP A701 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 533MG UT WOS:000174533603890 ER PT J AU Tou, J Grindeland, R Baer, L Gurun, G Fong, C Wade, C AF Tou, J Grindeland, R Baer, L Gurun, G Fong, C Wade, C TI The effect of hindlimb suspension on the reproductive system of young male rats SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. 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 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 20 PY 2002 VL 16 IS 4 BP A395 EP A395 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 533MG UT WOS:000174533602188 ER PT J AU Boykin, PO Mor, T Roychowdhury, V Vatan, F Vrijen, R AF Boykin, PO Mor, T Roychowdhury, V Vatan, F Vrijen, R TI Algorithmic cooling and scalable NMR quantum computers SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article AB We present here algorithmic cooling (via polarization heat bath)-a powerful method for obtaining a large number of highly polarized spins in liquid nuclear-spin systems at finite temperature. Given that spin-half states represent (quantum) bits, algorithmic cooling cleans dirty bits beyond the Shannon's bound on data compression, by using a set of rapidly thermal-relaxing bits. Such auxiliary bits could be implemented by using spins that rapidly get into thermal equilibrium with the environment, e.g., electron spins. Interestingly, the interaction with the environment, usually a most undesired interaction, is used here to our benefit, allowing a cooling mechanism. Cooling spins to a very low temperature without cooling the environment could lead to a breakthrough in NMR experiments, and our "spin-refrigerating" method suggests that this is possible. The scaling of NMR ensemble computers is currently one of the main obstacles to building larger-scale quantum computing devices, and our spin-refrigerating method suggests that this problem can be resolved. C1 Coll Judea & Samaria, Dept Elect Engn, IL-44837 Ariel, Israel. Univ Calif Los Angeles, Dept Elect Engn, Los Angeles, CA 90095 USA. Technion Israel Inst Technol, Dept Comp Sci, IL-32000 Haifa, Israel. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Sun Microsyst Inc, RAS Comp Anal Lab, Menlo Pk, CA 94025 USA. RP Mor, T (reprint author), Coll Judea & Samaria, Dept Elect Engn, IL-44837 Ariel, Israel. EM talmo@cs.technion.ac.il NR 15 TC 78 Z9 78 U1 0 U2 8 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA SN 0027-8424 J9 P NATL ACAD SCI USA JI Proc. Natl. Acad. Sci. U. S. A. PD MAR 19 PY 2002 VL 99 IS 6 BP 3388 EP 3393 DI 10.1073/pnas.241641898 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 533CC UT WOS:000174511000009 PM 11904402 ER PT J AU Ho, CH Chou, MD Sui, CH AF Ho, CH Chou, MD Sui, CH TI Comparison of different earth radiation budget experiment data sets over tropical oceans SO INTERNATIONAL JOURNAL OF CLIMATOLOGY LA English DT Article DE tropical oceans; Earth Radiation Budget Experiment; longwave radiation; shortwave radiation; sea surface temperature; water vapour greenhouse effect; cloud radiative forcing ID EL-NINO; PACIFIC; MODEL AB We compare radiation budgets derived from different Earth Radiation Budget Experiment (ERBE) archives over the tropical oceans (30S and 30N) from 1985 to 1989. Two ERBE data sets are used. One is taken from the Earth Radiation Budget Satellite (ERBS), and the other from the combined ERBS, National Oceanic and Atmospheric Administration (NOAA) 9, and NOAA 10 satellites. The domain-mean all-sky outgoing longwave radiation (OLR) derived from the combined data set shows a notable change in early 1987 when NOAA 10 replaced NOAA 9. This change is also found in longwave (LNV) cloud radiative forcing (CRF), all-sky shortwave (SW) radiation, and SWCRF. The ERBS, however, does not show such changes. We also examine the sensitivity of cloud-radiation interaction to the sea surface temperature (SST) of the tropical oceans. In general, each component of radiative feedbacks derived from the two ERBE data have the same sign, although they show a certain degree of discrepancy in the magnitude. The discrepancy is more notable for averaged quantities over the entire tropical oceans, particularly over the subtropics where convective activities are relatively weak, The combined data show a larger sensitivity of LWCRF and SWCRF to SST than those of the ERBS, consistent with the above results. The response of clouds to an increase in SST has a net cooling effect when using the combined data but has a net heating effect when using the ERBS data (-0.80 W m(-2) K-1 versus 0.48 W m(-2) K-1). Most of the discrepancies of the net CRF between the two ERBE data sets can be accounted for by the difference in the sensitivity of all-sky OLR (4.52 W m(-2) K-1 versus 1.73 W m(-2) K-1). Copyright (C) 2002 Royal Meteorological Society. C1 Seoul Natl Univ, Sch Earth & Environm Sci, Kwanak Ku, Seoul 151742, South Korea. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Ho, CH (reprint author), Seoul Natl Univ, Sch Earth & Environm Sci, Kwanak Ku, San 56-1 Shinlim Dong, Seoul 151742, South Korea. RI Ho, Chang-Hoi/H-8354-2015; OI SUI, CHUNG-HSIUNG/0000-0003-2842-5660 NR 13 TC 3 Z9 3 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0899-8418 J9 INT J CLIMATOL JI Int. J. Climatol. PD MAR 15 PY 2002 VL 22 IS 3 BP 263 EP 270 DI 10.1002/joc.734 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 535MY UT WOS:000174649300001 ER PT J AU Blanco, JL Carr, ME Thomas, AC Strub, PT AF Blanco, JL Carr, ME Thomas, AC Strub, PT TI Hydrographic conditions off northern Chile during the 1996-1998 La Nina and El Nino events SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article DE El Nino; Humboldt current; hydrography; northern Chile ID COASTAL CURRENTS; VARIABILITY; DYNAMICS; PERU AB The evolution of oceanographic conditions in the upwelling region off northern Chile (18degrees-24degreesS) between 1996 and 1998 (including the 1997-1998 El Nino) is presented using hydrographic measurements acquired on quarterly cruises of the Chilean Fisheries Institute, with sea surface temperature (SST), sea level, and wind speeds from Arica (18.5degreesS), Iquique (20.5degreesS), and Antofagasta (23.5degreesS) and a time series of vertical temperature profiles off Iquique. Spatial patterns of sea surface temperature and salinity from May 1996 to March 1997 followed a normal seasonal progression, though conditions were anomalously cool and fresh. Starting in March 1997, positive anomalies in sea level and sea surface temperature propagated along the South American coast to 37degreesS. Maximum sea level anomalies occurred in two peaks in May-July 1997 and October 1997 to February 1998, separated by a relaxation period. Maximum anomalies (2degreesC and 0.1 practical salinity units (psu)) extended to 400 m in December 1997 within 50 km of the coast. March 1998 presented the largest surface anomalies (> 4degreesC and 0.6 psu). Strong poleward flow (20-35 cm s(-1) ) occurred to 400 m or deeper during both sea level maxima and weaker (10 cm s(-1) ) equatorward flow followed each peak. By May 1998, SST had returned to the climatological mean, and flow was equatorward next to the coast. However, offshore salinity remained anomalously high owing to a tongue of subtropical water extending southeast along the Peruvian coast. Conditions off northern Chile returned to normal between August and December 1998. The timing of the anomalies suggests a connection to equatorial waves. The progression of the 1997-1998 El Nino was very similar to that of 1982-1983, though with different timing with respect to seasons. C1 Inst Vomento Pesquero, Valparaiso, Chile. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Maine, Sch Marine Sci, Orono, ME 04473 USA. Oregon State Univ, Coll Ocean & & Atmospher Sci, Corvallis, OR 97331 USA. RP Blanco, JL (reprint author), Old Dominion Univ, Ctr Coastal Phys Oceanog, Norfolk, VA 23508 USA. NR 26 TC 17 Z9 17 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD MAR 15 PY 2002 VL 107 IS C3 AR 3017 DI 10.1029/2001JC001002 PG 20 WC Oceanography SC Oceanography GA 609UH UT WOS:000178922600009 ER PT J AU Steyert, DW Wang, WF Sirota, JM Donahue, NM Reuter, DC AF Steyert, DW Wang, WF Sirota, JM Donahue, NM Reuter, DC TI Pressure broadening coefficients for rotational transitions of water in the 380-600 cm(-1) range SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article DE water vapor; infrared; line widths; rotational transitions ID VAPOR LINES; H2O; AIR AB We present results of recent experiments on the pressure broadening of pure rotational transitions of (H2O)-O-16 water in the 400-600 cm(-1) range by nitrogen and oxygen. The average broadening coefficient is about 0.056 cm(-1)/atm for N-2 and about 0.029 cm(-1)/atm for O-2, however, as expected, the broadening coefficient varies as a strong function of transition. In general, the broadening decreases with increasing J and K-a, with a stronger dependence on K-a than on J. On average, air broadening coefficients obtained from the coefficients presented here are about 10% lower than those found in HITRAN '96, although, as detailed below, the differences are a function of quantum number. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21250 USA. Harvard Univ, Dept Chem & Biochem, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RI Donahue, Neil/A-2329-2008 OI Donahue, Neil/0000-0003-3054-2364 NR 19 TC 12 Z9 12 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD MAR 15 PY 2002 VL 72 IS 6 BP 775 EP 782 DI 10.1016/S0022-4073(01)00156-X PG 8 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 517WD UT WOS:000173632700004 ER PT J AU Boccippio, DJ AF Boccippio, DJ TI Lightning scaling relations revisited SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID VERTICAL VELOCITY EVENTS; GLOBAL DISTRIBUTION; THUNDERSTORMS; ELECTRIFICATION; CONVECTION; PARAMETERIZATION; THUNDERCLOUDS; INTENSITY; TROPICS; MODEL AB Scaling relations connecting storm electrical generator power (and hence lightning flash rate) to charge transport velocity and storm geometry were originally posed by Vonnegut in the 1960s. These were later simplified to yield simple parameterizations for lightning based upon cloud-top height, with separate parameterizations derived over land and ocean. It is demonstrated that the most recent ocean parameterization 1) yields predictions of storm updraft velocity, which appear inconsistent with observation, and 2) is formally inconsistent with Vonnegut's original theory. Revised formulations consistent with Vonnegut's original framework are presented. These demonstrate that Vonnegut's theory is, to first order, consistent with recent satellite observations. The implications of assuming that flash rate is set by the electrical generator power, rather than the electrical generator current, are examined. The two approaches yield significantly different predictions about the dependence of charge transfer per flash on storm dimensions, which should be empirically and numerically testable. The two approaches also differ significantly in their physical explanations of regional variability in lightning observations. C1 NASA, George C Marshall Space Flight Ctr, Natl Space Sci & Technol Ctr, Huntsville, AL 35812 USA. RP Boccippio, DJ (reprint author), NASA, George C Marshall Space Flight Ctr, Natl Space Sci & Technol Ctr, SD-60, Huntsville, AL 35812 USA. NR 40 TC 39 Z9 40 U1 1 U2 6 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD MAR 15 PY 2002 VL 59 IS 6 BP 1086 EP 1104 DI 10.1175/1520-0469(2002)059<1086:LSRR>2.0.CO;2 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 524NN UT WOS:000174019900005 ER PT J AU Capra, L Macias, JL Scott, KM Abrams, M Garduno-Monroy, VH AF Capra, L Macias, JL Scott, KM Abrams, M Garduno-Monroy, VH TI Debris avalanches and debris flows transformed from collapses in the Trans-Mexican Volcanic Belt, Mexico - behavior, and implications for hazard assessment SO JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH LA English DT Article DE Trans-Mexican Volcanic Belt; debris avalanche; cohesive debris flow; hazard assessment ID PICO-DE-ORIZABA; TOLUCA VOLCANO; LATE PLEISTOCENE; MOUNT-RAINIER; DEPOSITS; NEVADO; COLIMA; POPOCATEPETL; EARTHQUAKES; EVOLUTION AB Volcanoes of the Trans-Mexican Volcanic Belt (TMVB) have yielded numerous sector and flank collapses during Pleistocene and Holocene times. Sector collapses associated with magmatic activity have yielded debris avalanches with generally limited runout extent (e.g. Popocatepetl, Jocotitlan, and Colima volcanoes). In contrast, flank collapses (smaller failures not involving the volcano summit), both associated and unassociated with magmatic activity and correlating with intense hydrothermal alteration in ice-capped volcanoes, commonly have yielded highly mobile cohesive debris flows (e.g. Pico de Orizaba and Nevado de Toluca volcanoes). Collapse orientation in the TMVB is preferentially to the south and northeast, probably reflecting the tectonic regime of active E-W and NNW faults, The differing mobilities of the flows transformed from collapses have important implications for hazard assessment. Both sector and flank collapse can yield highly mobile debris flows, but this transformation is more common in the cases of the smaller failures. High mobility is related to factors such as water content and clay content of the failed material, the paleotopography, and the extent of entrainment of sediment during flow (bulking). The ratio of fall height to runout distance commonly used for hazard zonation of debris avalanches is not valid for debris flows, which are more effectively modeled with the relation inundated area to failure or flow volume coupled with the topography of the inundated area. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Univ Nacl Autonoma Mexico, Inst Geografia, Mexico City 04510, DF, Mexico. Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City, DF, Mexico. Cascades Volcano Observ, Vancouver, WA USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. Univ Michoacana, Morelia, Mexico. RP Capra, L (reprint author), Univ Nacl Autonoma Mexico, Inst Geografia, Mexico City 04510, DF, Mexico. EM solari@servidor.unam.mx RI Capra, Lucia/C-2371-2011; Namikawa, Laercio/C-5559-2013; Macias, Jose Luis/P-7679-2015 OI Namikawa, Laercio/0000-0001-7847-1804; Macias, Jose Luis/0000-0002-2494-9849 NR 88 TC 73 Z9 74 U1 3 U2 9 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0377-0273 J9 J VOLCANOL GEOTH RES JI J. Volcanol. Geotherm. Res. PD MAR 15 PY 2002 VL 113 IS 1-2 BP 81 EP 110 AR PII S0377-0273(01)00252-9 DI 10.1016/S0377-0273(01)00252-9 PG 30 WC Geosciences, Multidisciplinary SC Geology GA 561LX UT WOS:000176143100006 ER PT J AU Rodriguez, SR Siebe, C Komorowski, JC Abrams, M AF Rodriguez, SR Siebe, C Komorowski, JC Abrams, M TI The Quetzalapa Pumice: a voluminous late Pleistocene rhyolite deposit in the eastern Trans-Mexican Volcanic Belt SO JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH LA English DT Article DE rhyolitic pumice; Trans-Mexican Volcanic Belt; plinian deposits; pumice fall deposits ID PICO-DE-ORIZABA; TEPHRA FALL DEPOSITS; PLINIAN ERUPTIONS; CITLALTEPETL VOLCANO; EXPLOSION; PUEBLA; VOLUME AB The study area is located in the cast part of the Trans-Mexican Volcanic Belt, in the Las Cumbres Volcanic Complex (LCVC) which lies between two large stratovolcanoes: Pico de Orizaba (5700 m a.s.l.) to the south, and Cofre de Perote (4200 m a.s.l.) to the NNE. The most conspicuous structure of the LCVC is a 4-km-diameter circular crater with a dacitic dome in the center, which constitutes the remains of a destroyed stratovolcano. The Quetzalapa Pumice (QP) was produced by a plinian eruption that was dated by the C-14 method at 20000 yr. BP. The eruptive sequence consists predominantly of pumice fall deposits and scarce intra-plinian pyroclastic flow deposits, which crop out on the west flank of the LCVC. The absence of post-plinian ignimbrite deposits is striking. The deposits are well sorted, clast-supported with reverse grading at the base, with a medium to high accessory lithics content. The maximum average thickness of the deposit in the proximal areas is about 15 m and has been divided into three members: the Basal Member (BM), 2 m thick with four submembers (BMf(1), BMf(2). BMf(3), and BMafl), the Intermediate Member (IM), 10 m thick with two submembers (IMpf and IMaf). and the Upper Member (UM), 3 m thick with four submembers (UMpl, UMsdf, UMwaf, and UMpls). The predominant component of the fall deposits is a white, highly vesiculated pumice with 71% SiO2 content. Plagioclase is the most abundant mineral followed by 1-3-mm-long biotite phenocrysts. The accessory lithics are lavas mostly of andesitic composition. Their abundance increases toward the uppermost levels of the sequence. We calculate a minimum volume of 8.4 km(3) (2.22 km(3) dense rock equivalent), for the entire QP deposit. Isopach and isopleth maps show that the IM deposit has an elongated distribution with a NNE-SSW direction, whereas the UM deposit has a circular distribution. We estimate a maximum eruptive column height for the IM of 20 km. Field studies and isopach and isopleth maps indicate that the eruptive column was affected by a strong wind. Previous studies located the QP source in the Las Cumbres crater. However. based on the isopach and isopleth distribution, and the lack of pumice fall deposits inside the Las Cumbres crater, we consider that the QP emission center is located on the west flank of the LCVC, and was buried by its own pumice fall deposits. It coincides with an explosion crater called La Capilla formed during the closing phase of the QP eruption. A 'pumice fountain' model is proposed to explain the observed sequence of deposits. According to this model, the material was emitted through a 'hose-type' conduit during a monogenetic eruption of rhyolitic composition. This kind of volcanic activity is not extensively reported in the literature. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Natl Autonomous Univ Mexico, Inst Geol, Mexico City 04510, DF, Mexico. Natl Autonomous Univ Mexico, Inst Geofis, Mexico City 04510, DF, Mexico. OVSG, Inst Phys Globe Paris, Gourbeyre 97113, Guadeloupe. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Rodriguez, SR (reprint author), Natl Autonomous Univ Mexico, Inst Geol, Mexico City 04510, DF, Mexico. OI Siebe, Claus/0000-0002-3959-9028 NR 54 TC 18 Z9 18 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0377-0273 J9 J VOLCANOL GEOTH RES JI J. Volcanol. Geotherm. Res. PD MAR 15 PY 2002 VL 113 IS 1-2 BP 177 EP 212 AR PII S0377-0273(01)00258-X DI 10.1016/S0377-0273(01)00258-X PG 36 WC Geosciences, Multidisciplinary SC Geology GA 561LX UT WOS:000176143100011 ER PT J AU d'Humieres, D Ginzburg, I Krafczyk, M Lallemand, P Luo, LS AF d'Humieres, D Ginzburg, I Krafczyk, M Lallemand, P Luo, LS TI Multiple-relaxation-time lattice Boltzmann models in three dimensions SO PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Article DE multiple-relaxation-time LBE in three dimensions; D3Q15 and D3Q19 models; three-dimensional diagonal lid-driven cavity flow ID NAVIER-STOKES EQUATION; NONIDEAL GASES; SIMULATIONS; BOUNDARY AB This article provides a concise exposition of the multiple-relaxation-time lattice Boltzmann equation, with examples of 15-velocity and 19-velocity models in three dimensions. Simulation of a diagonally lid-driven cavity flow in three dimensions at Re = 500 and 2000 is performed. The results clearly demonstrate the superior numerical stability of the multiple-relaxation-time lattice Boltzmann equation over the popular lattice Bhatnagar-Gross-Krook equation. C1 Ecole Normale Super, Lab Phys Stat, F-75231 Paris 05, France. Fraunhofer Inst Technol & Wirtschaftsmath, D-67663 Kaiserslautern, Germany. Tech Univ Munich, Fak Bauingenieur & Vermessungswesen, Lehrstuhl Bauinformat, D-80290 Munich, Germany. Univ Paris 11, Lab Applicat Sci Calcul Intens, ASCI, F-91405 Orsay, France. NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. RP d'Humieres, D (reprint author), Ecole Normale Super, Lab Phys Stat, 24 Rue Lhomond, F-75231 Paris 05, France. RI Luo, Li-Shi/A-4561-2011; Ginzburg, Irina/J-5669-2013 OI Luo, Li-Shi/0000-0003-1215-7892; NR 30 TC 644 Z9 647 U1 12 U2 99 PU ROYAL SOC LONDON PI LONDON PA 6 CARLTON HOUSE TERRACE, LONDON SW1Y 5AG, ENGLAND SN 1364-503X J9 PHILOS T ROY SOC A JI Philos. Trans. R. Soc. Lond. Ser. A-Math. Phys. Eng. Sci. PD MAR 15 PY 2002 VL 360 IS 1792 BP 437 EP 451 DI 10.1098/rsta.2001.0955 PG 15 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 535NB UT WOS:000174649600015 PM 16214687 ER PT J AU Moore, TA Hellings, RW AF Moore, TA Hellings, RW TI Angular resolution of space-based gravitational wave detectors SO PHYSICAL REVIEW D LA English DT Article ID BINARIES; LISA AB Proposed space-based gravitational wave antennas involve satellites arrayed either in an equilateral triangle around the Earth in the ecliptic plane (the ecliptic-plane option) or in an equilateral triangle orbiting the Sun in such a way that the plane of the triangle is tilted at 60degrees relative to the ecliptic (the precessing-plane option). In this paper, we explore the angular resolution of these two classes of detectors for two kinds of sources (essentially monochromatic compact binaries and coalescing massive-black-hole binaries) using time-domain expressions for the gravitational waveform that are accurate to 4/2 PN order. Our results display an interesting effect not previously reported in the literature, and particularly underline the importance of including the higher-order PN terms in the waveform when predicting the angular resolution of ecliptic-plane detector arrays. C1 Pomona Coll, Dept Phys & Astron, Claremont, CA 91711 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Moore, TA (reprint author), Pomona Coll, Dept Phys & Astron, Claremont, CA 91711 USA. NR 8 TC 47 Z9 47 U1 0 U2 2 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 MAR 15 PY 2002 VL 65 IS 6 AR 062001 DI 10.1103/PhysRevD.65.062001 PG 13 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 533UE UT WOS:000174548100004 ER PT J AU Wichoski, UF MacGibbon, JH Brandenberger, RH AF Wichoski, UF MacGibbon, JH Brandenberger, RH TI High energy neutrino, photon, and cosmic ray fluxes from VHS cosmic strings SO PHYSICAL REVIEW D LA English DT Article ID MONTE-CARLO SIMULATION; PRIMORDIAL BLACK-HOLES; GRAND UNIFIED THEORIES; TOPOLOGICAL DEFECTS; GAMMA-RAY; DARK-MATTER; LIMITS; EVOLUTION; NETWORKS; EMISSION AB Decaying topological defects, in particular cosmic strings, can produce a significant flux of high energy neutrinos, photons and cosmic rays. According to the prevailing understanding of cosmic string dynamics in an expanding Universe, the network of long strings loses its energy first into string loops, which in turn give off most of their energy as gravitational radiation. However, it has been suggested by Vincent, Hindmarsh, and Sakellariadou (VHS) that particle emission may be the dominant energy loss channel for the long string network. In this case, the predicted flux of high energy particles would be much larger. Here we calculate the predicted flux of high energy gamma rays, neutrinos and cosmic ray antiprotons and protons as a function of the scale of symmetry breaking hat which the strings are produced and as a function of the initial energy m(J) of the particle jets which result from the string decay. Assuming the validity of the VHS scenario, we find that due to the interactions with the cosmic radiation backgrounds all fluxes but the neutrino flux are suppressed at the highest energies. This indicates that the observed events above the GZK cutoff can only be accounted for in this scenario if the primary particle is a neutrino and eta is somewhat less than the GUT scale, i. e. eta less than or similar to 10(23) 23 eV. The domain of parameter space corresponding to GUT-scale symmetry breaking is excluded also by the current observations below the GZK cutoff. A new aspect of this work is the calculation of the spectrum of the tau neutrinos directly produced in the decay of the X particles. This significantly increases the tau neutrino signal at high energies in all cosmic string scenarios. C1 Brown Univ, Dept Phys, Providence, RI 02912 USA. IST, CENTRA, Dept Fis, P-1049001 Lisbon, Portugal. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Brown Univ, Dept Phys, Providence, RI 02912 USA. RP Wichoski, UF (reprint author), Brown Univ, Dept Phys, Providence, RI 02912 USA. NR 85 TC 21 Z9 21 U1 0 U2 0 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 MAR 15 PY 2002 VL 65 IS 6 AR 063005 DI 10.1103/PhysRevD.65.063005 PG 18 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 533UE UT WOS:000174548100011 ER PT J AU Niimura, M Cadez, I Smith, SJ Chutjian, A AF Niimura, M Cadez, I Smith, SJ Chutjian, A TI Measurement of absolute cross sections for excitation of the 3s(2)3p(5) P-2(3/2)o-3s(2)3p(5) P-2(1/2)o fine-structure transition in Fe9+ SO PHYSICAL REVIEW LETTERS LA English DT Article ID ELECTRON-EXCITATION AB Experimental cross sections are reported for the 3s(2)3p(5) P-2(3/2)0-3s(2)3p(5) P-2(1/2)0 transition in Fe9+ heated at 1.945 eV. The center-of-mass interaction energies are in the range of 1.72 eV (below threshold) through threshold, to 5.6 eV (2.9xthreshold). Data are compared with results of a 49-state Breit-Pauli R-matrix theory. The experiment detects structures at 3.5 and 4.6 eV corresponding to enhancement of the direct excitation via many narrow, closely spaced resonances about these energies calculated by the theory. Iron is present in practically every astrophysical object, as well as being an impurity in fusion plasmas. Present data are the first electron-energy-loss measurements on a highly charged iron ion. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Jozef Stefan Inst, Ljubljana, Slovenia. RP Niimura, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 10 TC 8 Z9 8 U1 0 U2 0 PU AMERICAN 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 MAR 11 PY 2002 VL 88 IS 10 AR 103201 DI 10.1103/PhysRevLett.88.103201 PG 3 WC Physics, Multidisciplinary SC Physics GA 530EE UT WOS:000174342000023 PM 11909352 ER PT J AU Connaughton, V AF Connaughton, V TI BATSE observations of gamma-ray burst tails SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts ID 28 FEBRUARY 1997; HIGH-ENERGY; SPECTRAL EVOLUTION; AFTERGLOW; CAMERAS AB With the discovery of low-energy radiation appearing to come from the site of gamma-ray bursts in the hours to weeks after the initial burst of gamma rays, it would appear that astronomers have seen a cosmological imprint made by the burster on its surroundings. I discuss in this paper the phenomenon of postburst emission in BATSE gamma-ray bursts at energies traditionally associated with prompt emission. By summing the background-subtracted signals from hundreds of bursts, I find that tails out to hundreds of seconds after the trigger may be a common feature of long events (duration greater than 2 s) and perhaps of the shorter bursts, at a lower and shorter-lived level. The tail component appears independent of both the duration (within the long-GRB sample) and brightness of the prompt burst emission and may be softer. Some individual bursts have visible tails at gamma-ray energies, and the spectrum in at least a few cases is different from that of the prompt emission. Afterglow at lower energies was detected for one of these bursts, GRB 991216, raising the possibility of afterglow observations over large energy ranges using the next generation of GRB detectors in conjunction with sensitive space or ground-based telescopes. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Connaughton, V (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 32 TC 78 Z9 81 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 10 PY 2002 VL 567 IS 2 BP 1028 EP 1036 DI 10.1086/338695 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527WF UT WOS:000174210400030 ER PT J AU Titarchuk, L Shrader, CR AF Titarchuk, L Shrader, CR TI Observational signatures of black holes: Spectral and temporal features of XTE J1550-564 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : close; black hole physics; radiation mechanisms : nonthermal; relativity; star, individual (XTE J1550-564, XTE J1118+480) ID QUASI-PERIODIC OSCILLATIONS; HIGH-ENERGY SPECTRA; X-RAY-EMISSION; COMPTONIZATION MODELS; RXTE OBSERVATIONS; ACCRETION DISKS; NEUTRON-STAR; MONTE-CARLO; CYGNUS X-1; PHASE-LAG AB The theoretical predictions of the converging inflow, or bulk motion Comptonization (BMC) model are discussed and some predictions are compared to X-ray and gamma-ray observations of the high/soft state of Galactic black hole candidate XTE J1550-564. The similar to10(2) Hz quasi-periodic oscillation phenomenon tends to be detected in the high state at times when the bolometric luminosity surges and the hard power-law spectral component is dominant. Furthermore, the power in these features increases with energy. We offer interpretation of this phenomenon as oscillations of the innermost part of the accretion disk, which in turn supplies the seed photons for the converging inflow where the hard power law is formed through BMC. We further argue that the noted lack of coherence between intensity variations of the high/soft state low- and high-energy bands is a natural consequence of our model and that a natural explanation for the observed hard and soft lag phenomenon is offered. In addition, we address some criticisms of the BMC model supporting our claims with observational results. For XTE J1550-564, assuming the source is 5 kpc distant, we derive a black hole mass estimate of 12-15 M-circle dot through application of the BMC model. C1 George Mason Univ, CEOSR, Fairfax, VA 22030 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Lanham, MD USA. RP Titarchuk, L (reprint author), George Mason Univ, CEOSR, Fairfax, VA 22030 USA. NR 69 TC 23 Z9 23 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 10 PY 2002 VL 567 IS 2 BP 1057 EP 1066 DI 10.1086/338661 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527WF UT WOS:000174210400033 ER PT J AU Shaposhnikov, N Titarchuk, L AF Shaposhnikov, N Titarchuk, L TI Spectra of the expansion stage of X-ray bursts SO ASTROPHYSICAL JOURNAL LA English DT Article DE radiation mechanisms : nonthermal; stars : neutron; X-rays : binaries; X-rays : bursts ID NEUTRON-STARS; BLACK-HOLES; STATIONARY AB We present an analytical theory of thermonuclear X-ray burst atmosphere structure. Newtonian gravity and diffusion approximation are assumed. Hydrodynamic and thermodynamic profiles are obtained as a numerical solution of the Cauchy problem for the first-order ordinary differential equation. We further elaborate a combined approach to the radiative transfer problem that yields the spectrum of the expansion stage of X-ray bursts in an analytical form in which Comptonization and free-free absorption-emission processes are accounted for and tausimilar tor(-2) opacity dependence is assumed. A relaxation method on an energy opacity grid is used to simulate a radiative diffusion process in order to match the analytical form of the spectrum, which contains the free parameter, to the energy axis. Numerical and analytical results show high similarity. All spectra consist of a power-law soft component and a diluted blackbody hard tail. We derive simple approximation formulae usable for mass-radius determination by observational spectra fitting. C1 George Mason Univ, Sch Computat Sci, Fairfax, VA 22030 USA. George Mason Univ, Ctr Earth Observing & Space Res, Fairfax, VA 22030 USA. USN, Res Lab, Washington, DC 20375 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Shaposhnikov, N (reprint author), George Mason Univ, Sch Computat Sci, Fairfax, VA 22030 USA. NR 20 TC 9 Z9 9 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 10 PY 2002 VL 567 IS 2 BP 1077 EP 1090 DI 10.1086/338590 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527WF UT WOS:000174210400035 ER PT J AU Chen, H Beiersdorfer, P Scofield, JH Gendreau, KC Boyce, KR Brown, GV Kelley, RL Porter, FS Stahle, CK Szymkowiak, AE Kahn, SM AF Chen, H Beiersdorfer, P Scofield, JH Gendreau, KC Boyce, KR Brown, GV Kelley, RL Porter, FS Stahle, CK Szymkowiak, AE Kahn, SM TI Measurement of emission cross sections for n=3 -> 2 lines in Li-like Fe23+ SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic data; atomic processes; methods : laboratory; X-rays : general ID X-RAY SPECTROMETER; BEAM ION-TRAP; ELECTRON-BEAM; HELIUM-LIKE; FE-XXV; EXCITATION; POLARIZATION; CALIBRATION AB We report measurements of emission cross sections for iron L-shell 3-->2 lines in Fe23+ performed on the electron beam ion trap EBIT-II using a combination of a crystal spectrometer and the spare 6x6 element X-Ray Spectrometer microcalorimeter from the Astro-E X-ray satellite mission. Use of the microcalorimeter enables for first time the normalization of line emission cross sections, i.e., effective electron impact excitation cross sections that include radiative cascades, to the well-established cross section of radiative electron capture, thus allowing the normalization of relative line intensity measurements using crystal spectrometers. C1 Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Columbia Univ, Columbia Astrophys Lab, New York, NY 10027 USA. RP Chen, H (reprint author), Lawrence Livermore Natl Lab, 7000 E Ave, Livermore, CA 94550 USA. RI Porter, Frederick/D-3501-2012; Kelley, Richard/K-4474-2012 OI Porter, Frederick/0000-0002-6374-1119; NR 27 TC 24 Z9 25 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 10 PY 2002 VL 567 IS 2 BP L169 EP L172 DI 10.1086/340007 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527WG UT WOS:000174210500016 ER PT J AU Lamb, RC Macomb, DJ Prince, TA Majid, WA AF Lamb, RC Macomb, DJ Prince, TA Majid, WA TI Discovery of 16.6 and 25.5 second pulsations from the Small Magellanic Cloud SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : general; pulsars : general; X-rays : general ID X-RAY SOURCES AB We report the serendipitous detection of two previously unreported pulsars from the direction of the Small Magellanic Cloud, with periods of 16.6 and 25.5 s. The detections are based on archival Proportional Counter Array data from the Rossi X-Ray Timing Explorer. The observation leading to these detections occurred in 2000 September, extending over 2.1 days with an exposure of 121 ks. A possible identification of the 16.6 s pulsar with an X-ray source (RX J0051.8-7310) seen by both the ROSAT and ASCA imaging X-ray satellites is presented. C1 CALTECH, Space Radiat Lab, Pasadena, CA 91125 USA. Boise State Univ, Dept Phys, Boise, ID 83725 USA. CALTECH, Jet Prop Lab, NASA, Pasadena, CA 91109 USA. RP Lamb, RC (reprint author), CALTECH, Space Radiat Lab, MS 220-47, Pasadena, CA 91125 USA. NR 13 TC 14 Z9 14 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 10 PY 2002 VL 567 IS 2 BP L129 EP L132 DI 10.1086/340001 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527WG UT WOS:000174210500007 ER PT J AU McAteer, RTJ Gallagher, PT Williams, DR Mathioudakis, M Phillips, KJH Keenan, FP AF McAteer, RTJ Gallagher, PT Williams, DR Mathioudakis, M Phillips, KJH Keenan, FP TI Long-period chromospheric oscillations in network bright points SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : chromosphere; Sun : magnetic fields; Sun : oscillations; Sun : photosphere ID SOLAR CHROMOSPHERE; SUNS CHROMOSPHERE; FLUX TUBES; WAVES; DYNAMICS; INTERNETWORK; ATMOSPHERE; GRAINS; LINE AB The spatial variation of chromospheric oscillations in network bright points (NBPs) is studied using high-resolution observations in Ca II K3. Light curves and hence power spectra were created by isolating distinct regions of the NBP via a simple intensity thresholding technique. Using this technique, it was possible to identify peaks in the power spectra with particular spatial positions within the NBPs. In particular, long-period waves with periods of 4-15 minutes (1-4 mHz) were found in the central portions of each NBP, indicating that these waves are certainly not acoustic but possibly due to magnetoacoustic or magnetogravity wave modes. We also show that spatially averaged or low spatial resolution power spectra can lead to an inability to detect such long-period waves. C1 Queens Univ Belfast, Dept Pure & Appl Phys, Belfast BT7 1NN, Antrim, North Ireland. NASA, Goddard Space Flight Ctr, Emergent Technol Serv Inc, Greenbelt, MD 20771 USA. Rutherford Appleton Lab, Dept Space Sci, Didcot OX11 0QX, Oxon, England. RP McAteer, RTJ (reprint author), Queens Univ Belfast, Dept Pure & Appl Phys, Belfast BT7 1NN, Antrim, North Ireland. RI McAteer, R. T. James/D-3736-2011; Gallagher, Peter/C-7717-2011 OI Gallagher, Peter/0000-0001-9745-0400 NR 23 TC 29 Z9 30 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 10 PY 2002 VL 567 IS 2 BP L165 EP L168 DI 10.1086/340110 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527WG UT WOS:000174210500015 ER PT J AU Monnier, JD Tuthill, PG Danchi, WC AF Monnier, JD Tuthill, PG Danchi, WC TI Proper motions of new dust in the colliding wind binary WR 140 SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : close; circumstellar matter; stars : individual (WR 98a, WR 104, WR 137, WR 140); stars : winds, outflows; stars : Wolf-Rayet ID MULTIFREQUENCY VARIATIONS; PINWHEEL NEBULA; RADIO-EMISSION; HD-193793; TELESCOPE; ASTRONOMY; SHELL; STARS; PHASE AB The eccentric W-R + O binary system WR 140 produces dust for a few months at intervals of 7.94 yr coincident with periastron passage. We present the first resolved images of this dust shell, at binary phases phi similar to 0.039 and similar to 0.055, using aperture masking techniques on the Keck I telescope to achieve diffraction-limited resolution. Proper motions of approximately 1.1 mas per day were detected, implying a distance less than or similar to1.5 kpc from the known wind speed. The dust plume observed is not as simple as the "pinwheel" nebulae seen around other W-R colliding wind binaries, indicating the orbital plane is highly inclined to our line of sight and/or the dust formation is very clumpy. Follow-up imaging in the mid-infrared and with adaptive optics is urgently required to track the dust motion further, necessary for unambiguously determining the orbital geometry, which we only partially constrain here. With full knowledge of the orbital elements, these infrared images can be used to reconstruct the dust distribution along the colliding wind interface, providing a unique tool for probing the postshock physical conditions of violent astrophysical flows. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Sydney, Sch Phys, Sydney, NSW 2006, Australia. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Monnier, JD (reprint author), Harvard Smithsonian Ctr Astrophys, MS 42,60 Garden St, Cambridge, MA 02138 USA. EM jmonnier@cfa.harvard.edu; gekko@physics.usyd.edu.au; wcd@iri1.gsfc.nasa.gov OI Monnier, John D/0000-0002-3380-3307 NR 25 TC 42 Z9 42 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 MAR 10 PY 2002 VL 567 IS 2 BP L137 EP L140 DI 10.1086/340005 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527WG UT WOS:000174210500009 ER PT J AU Montesi, LGJ Zuber, MT AF Montesi, LGJ Zuber, MT TI A unified description of localization for application to large-scale tectonics SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Review DE localization; shear zones; rheology; earthquake; dynamics ID HIGH-TEMPERATURE CREEP; GRAIN-SIZE REDUCTION; ANGLE NORMAL FAULTS; SAN-ANDREAS FAULT; SHEAR ZONES; PLATE-TECTONICS; FLUID PRESSURE; MANTLE FLOW; POROUS ROCK; CONTINENTAL LITHOSPHERE AB [1] Localized regions of deformation such as faults and shear zones are ubiquitous in the Earth's lithosphere. However, we lack a simple unified framework of localization that is independent of the mechanism or scale of localization. We address this issue by introducing the effective stress exponent, ne, a parameter that describes how a material responds to a local perturbation of an internal variable being tested for localization. The value of ne is based on micromechanics. A localizing regime has a negative n(e), indicating a weakening behavior, and localization is stronger for more negative 1/n(e). We present expressions for the effective stress exponent associated with several mechanisms that trigger localization at large scale: brittle failure with loss of cohesion, elastoplasticity, rate- and state-dependent friction, shear heating, and grain-size feedback in ductile rocks. In most cases, localization does not arise solely from the relation between stress and deformation but instead requires a positive feedback between the rheology and internal variables. Brittle mechanisms (failure and friction) are generally described by ne of the order of -100. Shear heating requires an already localized forcing, which could be provided by a brittle fault at shallower levels of the lithosphere. Grain size reduction, combined with a transition from dislocation to diffusion creep, leads to localization only if the grain size departs significantly from its equilibrium value, because either large-scale flow moves rocks through different thermodynamic environments or new grains are nucleated. When shear heating or grain-size feedback produce localization, 1/n(e) can be extremely negative and can control lithospheric-scale localization. C1 MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. RP Montesi, LGJ (reprint author), MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. EM montesi@mit.edu; zuber@mit.edu RI Montesi, Laurent/C-5216-2009 OI Montesi, Laurent/0000-0002-3519-1412 NR 127 TC 53 Z9 53 U1 0 U2 11 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 MAR 10 PY 2002 VL 107 IS B3 AR 2045 DI 10.1029/2001JB000465 PG 21 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 609MQ UT WOS:000178909900013 ER PT J AU Strekalov, DV Dowling, JP AF Strekalov, DV Dowling, JP TI Two-photon interferometry for high-resolution imaging SO JOURNAL OF MODERN OPTICS LA English DT Article; Proceedings Paper CT Conference on the Physics of Quantum Electronics CY JAN 08-11, 2001 CL SNOWBIRD, UTAH ID POLYMERIZATION; FILAMENTATION; ENTANGLEMENT; INTERFERENCE; LITHOGRAPHY; CONVERSION; VACUUM; LIMIT; LIGHT AB This paper discusses the advantages of using non-classical states of light for two aspects of optical imaging: the creation of microscopic images on photosensitive substrates, which constitutes the foundation for optical lithography, and the imaging of microscopic objects. In both cases, the classical resolution limit given by the Rayleigh criterion is approximately half of the optical wavelength. It has been shown, however, that by using multi-photon quantum states of the light field, and a multi-photon sensitive material or detector, this limit can be surpassed. A rigorous quantum mechanical treatment of this problem is given, some particularly widespread misconceptions are addressed, and turning quantum imaging into a practical technology is discussed. C1 CALTECH, Jet Prop Lab, Quantum Comp Technol Grp, Pasadena, CA 91109 USA. RP Strekalov, DV (reprint author), CALTECH, Jet Prop Lab, Quantum Comp Technol Grp, MS 300-123,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI DOWLING, JONATHAN/L-2749-2013 NR 17 TC 22 Z9 22 U1 1 U2 2 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 0950-0340 J9 J MOD OPTIC JI J. Mod. Opt. PD MAR 10 PY 2002 VL 49 IS 3-4 BP 519 EP 527 DI 10.1080/09500340110090846 PG 9 WC Optics SC Optics GA 524KQ UT WOS:000174012700019 ER PT J AU Ma, Q Tipping, RH AF Ma, Q Tipping, RH TI The frequency detuning correction and the asymmetry of line shapes: The far wings of H2O-H2O SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID MOLECULAR COMPLEXES; COORDINATE REPRESENTATION; DETAILED BALANCE; WATER-MOLECULES; DENSITY-MATRIX; CO2; TEMPERATURE; ABSORPTION; TENSOR; DIMER AB A far-wing line shape theory that satisfies the detailed balance principle is applied to the H2O-H2O system. Within this formalism, two line shapes are introduced, corresponding to band averages over the positive and negative resonance lines, respectively. Using the coordinate representation, the two line shapes can be obtained by evaluating 11-dimensional integrations whose integrands are a product of two factors. One depends on the interaction between the two molecules and is easy to evaluate. The other contains the density matrix of the system and is expressed as a product of two three-dimensional distributions associated with the density matrices of the absorber and the perturber molecule, respectively. If most of the populated states are included in the averaging process, to obtain these distributions requires extensive computer CPU time, but only have to be computed once for a given temperature. The 11-dimensional integrations are evaluated using the Monte Carlo method, and in order to reduce the variance, the integration variables are chosen such that the sensitivity of the integrands on them is clearly distinguished. Numerical tests show that by taking into account about 10(7) random selections, one is able to obtained converged results. We find that it is necessary to consider frequency detuning, because this makes significant and opposite contributions in the two band-averaging processes and causes the lines to be asymmetric. Otherwise, the two line shapes become symmetric, are the same, and equal to the mean of the two shapes obtained including the frequency detuning effects. For the pure rotational band, we find that the magnitude of the line shape obtained from the positive line average is larger than that obtained from the negative line average for omega>0 and vice versa for omega<0, and their relative gap increases as the frequency displacement from the line center increases. By adopting a realistic potential model and optimizing its parameters, one is able to obtain these two line shapes and calculate the corresponding absorption coefficients that are in good agreement with laboratory data. Also, this same potential yields good theoretical values for other physical properties of the dilute H2O gas. (C) 2002 American Institute of Physics. C1 Columbia Univ, Dept Appl Phys, New York, NY 10025 USA. NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. RP Ma, Q (reprint author), Columbia Univ, Dept Appl Phys, New York, NY 10025 USA. NR 26 TC 35 Z9 37 U1 0 U2 2 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 MAR 8 PY 2002 VL 116 IS 10 BP 4102 EP 4115 DI 10.1063/1.1436115 PG 14 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 525TL UT WOS:000174087000016 ER PT J AU Cruden, BA Gleason, KK Sawin, HH AF Cruden, BA Gleason, KK Sawin, HH TI Ultraviolet absorption measurements of CF2 in the parallel plate pyrolytic chemical vapour deposition process SO JOURNAL OF PHYSICS D-APPLIED PHYSICS LA English DT Article ID FLUOROCARBON FILMS; ETCHING PLASMAS; THIN-FILMS; SPECTROSCOPY; CONSTANT AB Polytetrafluoroethylene films have been deposited for use as low dielectric constant materials. Deposition is performed through pyrolysis of hexafluoropropylene oxide (HFPO) to produce CF2, which can then polymerize and deposit as a thin film. The variation of CF2 concentration as a function of reactor conditions has been characterized by ultraviolet absorption spectroscopy. CF2 concentration is observed to go through a maximum with respect to both pressure and pyrolysis temperature when it is present in large amounts (similar to10(14) cm(-3)). A one-dimensional model including known kinetic reactions for HFPO decomposition and CF2 recombination and multi-component diffusive transport has been applied to the parallel plate system. The result is seen to overestimate the measured concentration and does not capture the maxima observed versus pressure and temperature. An additional mechanism of particle formation, by CF2 insertion into (CF2)(n) oligomers, has been introduced to produce a kinetic model that explains the CF2 concentration measurements. C1 MIT, Dept Chem Engn, Cambridge, MA 02139 USA. RP Cruden, BA (reprint author), Eloret Corp, NASA, Ames Res Ctr, Sunnyvale, CA 94087 USA. RI Gleason, Karen/G-1471-2013 OI Gleason, Karen/0000-0001-6127-1056 NR 26 TC 8 Z9 9 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0022-3727 J9 J PHYS D APPL PHYS JI J. Phys. D-Appl. Phys. PD MAR 7 PY 2002 VL 35 IS 5 BP 480 EP 486 AR PII S0022-3727(02)31312-3 DI 10.1088/0022-3727/35/5/311 PG 7 WC Physics, Applied SC Physics GA 536EM UT WOS:000174687800013 ER PT J AU Tabazadeh, A Drdla, K Schoeberl, MR Hamill, P Toon, OB AF Tabazadeh, A Drdla, K Schoeberl, MR Hamill, P Toon, OB TI Arctic "ozone hole" in a cold volcanic stratosphere SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID ANTARCTIC OZONE; MOUNT-PINATUBO; POLAR VORTEX; AEROSOL; CLOUDS; RECOVERY; ERUPTION; DENITRIFICATION; CHARACTER; DEPLETION AB Optical depth records indicate that volcanic aerosols from major eruptions often produce clouds that have greater surface area than typical Arctic polar stratospheric clouds (PSCs). A trajectory cloud-chemistry model is used to study how volcanic aerosols could affect springtime Arctic ozone loss processes, such as chlorine activation and denitrification, in a cold winter within the current range of natural variability. Several studies indicate that severe denitrification can increase Arctic ozone loss by up to 30%. We show large PSC particles that cause denitrification in a nonvolcanic stratosphere cannot efficiently form in a volcanic environment. However, volcanic aerosols, when present at low altitudes, where Arctic PSCs cannot form, can extend the vertical range of chemical ozone loss in the lower stratosphere. Chemical processing on volcanic aerosols over a 10-km altitude range could increase the current levels of springtime column ozone loss by up to 70% independent of denitrification. Climate models predict that the lower stratosphere is cooling as a result of greenhouse gas built-up in the troposphere. The magnitude of column ozone loss calculated here for the 1999-2000 Arctic winter, in an assumed volcanic state, is similar to that projected for a colder future nonvolcanic stratosphere in the 2010 decade. C1 NASA, Ames Res Ctr, Div Earth Sci, Moffett Field, CA 94035 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. San Jose State Univ, Dept Phys, San Jose, CA 95192 USA. Univ Colorado, Atmospher & Space Phys Lab, Program Atmospher & Ocean Sci, Boulder, CO 80309 USA. RP Tabazadeh, A (reprint author), NASA, Ames Res Ctr, Div Earth Sci, MS-245-4, Moffett Field, CA 94035 USA. NR 29 TC 22 Z9 22 U1 0 U2 5 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA SN 0027-8424 J9 P NATL ACAD SCI USA JI Proc. Natl. Acad. Sci. U. S. A. PD MAR 5 PY 2002 VL 99 IS 5 BP 2609 EP 2612 DI 10.1073/pnas.052518199 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 529DK UT WOS:000174284600007 PM 11854461 ER PT J AU Kuehn, K Mehta, S Fu, HY Genio, E Murphy, D Liu, FC Liu, YM Ahlers, G AF Kuehn, K Mehta, S Fu, HY Genio, E Murphy, D Liu, FC Liu, YM Ahlers, G TI Singularity in the thermal boundary resistance between superfluid He-4 and a solid surface SO PHYSICAL REVIEW LETTERS LA English DT Article ID T-LAMBDA; KAPITZA RESISTANCE; TRANSITION; GOLD AB We report new measurements in four cells of the thermal boundary resistance R between copper and He-4 below but near the superfluid-transition temperature T-lambda. For 10(-7) less than or equal to t = 1 - T/T-lambda less than or equal to 10(-4) fits of R = R(0)t(-xb) + R-B to the data yielded x(b) similar or equal to 0.18, whereas a fit to theoretical values based on the renormalization-group theory yielded x(b) = 0.23. Alternatively, a good fit of the theory to the data could be obtained if the amplitude of the prediction was reduced by a factor close to 2. The results raise the question whether the boundary conditions used in the theory should be modified. C1 Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. Univ Calif Santa Barbara, iQUEST, Santa Barbara, CA 93106 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kuehn, K (reprint author), Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. NR 24 TC 9 Z9 9 U1 0 U2 1 PU AMERICAN 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 MAR 4 PY 2002 VL 88 IS 9 AR 095702 DI 10.1103/PhysRevLett.88.095702 PG 4 WC Physics, Multidisciplinary SC Physics GA 527WZ UT WOS:000174212100044 PM 11864027 ER PT J AU Mankins, JC AF Mankins, JC TI A technical overview of the "SunTower" solar power satellite concept SO ACTA ASTRONAUTICA LA English DT Article AB During 1995-1996, the National Aeronautics and Space Administration (NASA) conducted a far-reaching reexamination of the technologies, systems concepts and terrestrial markets that might be involved in future space solar power (SSP) systems. The principal objective of this "fresh look" study was to determine whether a solar power satellite (SPS) and associated systems could be defined that could deliver energy into terrestrial electrical power grids at prices equal to or below ground alternatives in a variety of markets, do so without major environmental drawbacks, and which could be developed at a fraction of the initial investment projected for the SPS Reference System of the late 1970s. One of the key concepts emerging from the "fresh look" SSP study is the "SunTower" SPS system. This concept exploits a variety of innovative technologies and design approaches to achieve a potential breakthrough in establishing the technical and programmatic feasibility on initial commercial SSP operations. Capable of being deployed to either low Earth orbit or middle Earth orbit altitudes and various inclinations, the SunTower concept involves essentially no in-space infrastructure and requires no unique heavy lift launch vehicle. The concept, which can provide power to global market places appears to allow up to a factor of 30:1 reduction in initial investment requirements, compared to the 1979 SPS Reference Concept. This paper presents a technical overview of the SunTower SPS concept, including key technologies, sensitivity trades, operational scenarios. Potential non-SPS space program uses of the SunTower concept and related technologies are identified, including human exploration, space science and commercial space applications, Published by Elsevier Science Ltd. C1 NASA, Headquarters Off, Adv Projects Off, Off Space Flight, Washington, DC 20546 USA. RP Mankins, JC (reprint author), NASA, Headquarters Off, Adv Projects Off, Off Space Flight, 300 E St SW, Washington, DC 20546 USA. NR 9 TC 3 Z9 5 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAR PY 2002 VL 50 IS 6 BP 369 EP 377 AR PII S0094-5765(01)00167-9 DI 10.1016/S0094-5765(01)00167-9 PG 9 WC Engineering, Aerospace SC Engineering GA 543NQ UT WOS:000175108400005 ER PT J AU Singh, M AF Singh, M TI Ecoceramics: Ceramics from wood SO ADVANCED MATERIALS & PROCESSES LA English DT Article AB Silicon carbide-based ecoceramics have been fabricated by reactive infiltration of carbonaceous preforms by molten silicon or silicon-refractory metal alloys. C1 QSS Grp Inc, NASA, Glenn Res Ctr, Cleveland, OH 44136 USA. RP Singh, M (reprint author), QSS Grp Inc, NASA, Glenn Res Ctr, MS 106-5, Cleveland, OH 44136 USA. NR 0 TC 9 Z9 9 U1 0 U2 1 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 USA SN 0882-7958 J9 ADV MATER PROCESS JI Adv. Mater. Process. PD MAR PY 2002 VL 160 IS 3 BP 39 EP 41 PG 3 WC Materials Science, Multidisciplinary SC Materials Science GA 529NK UT WOS:000174305400006 ER PT J AU Wasfy, TM Noor, AK AF Wasfy, TM Noor, AK TI Rule-based natural-language interface for virtual environments SO ADVANCES IN ENGINEERING SOFTWARE LA English DT Article DE natural language recognition; expert systems; artificial intelligence; voice recognition; virtual environments; virtual reality; object-oriented software; visual simulation ID VISUALIZATION; ROBOT AB A hierarchical rule-based natural-language interface (NLI) for object-oriented virtual environment (VE) toolkits is described. The NLI allows modifying the properties of existing objects, as well as creating new objects in the VE using near-natural language speech. The rules are organized in a tree hierarchy with each rule branching to a 'group of rules'. Each tree-branch forms a possible user's command. Each rule generates global variables, which can be accessed by rules down the branch in order to formulate an appropriate action for the command. The action consists of a set of script commands that are sent to the VE. Also., the NLI maintains a state that allows it to respond to a command in the context of the previous command that the user issued. The hierarchical NLI exploits the object-oriented data structure of the VE toolkit by using three main levels of rules, namely, object, property, and action rules. The NLI can run on a remote computer and is linked to the computer running the VE via a network socket connection. The application of the NLI to the visualization of computational fluid dynamics results in a virtual wind tunnel is presented. Published by Elsevier Science Ltd. C1 Old Dominion Univ, Ctr Adv Engn Environm, NASA, Langley Res Ctr, Hampton, VA 23681 USA. Adv Sci & Automat Corp, Hampton, VA USA. RP Noor, AK (reprint author), Old Dominion Univ, Ctr Adv Engn Environm, NASA, Langley Res Ctr, Mail Stop 201, Hampton, VA 23681 USA. EM a.k.noor@larc.nasa.gov NR 13 TC 10 Z9 10 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0965-9978 J9 ADV ENG SOFTW JI Adv. Eng. Softw. PD MAR PY 2002 VL 33 IS 3 BP 155 EP 168 AR PII S0965-9978(02)00004-2 DI 10.1016/S0965-9978(02)00004-2 PG 14 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Engineering, Multidisciplinary SC Computer Science; Engineering GA 536JA UT WOS:000174695900004 ER PT J AU Jorgensen, C Wheeler, K AF Jorgensen, C Wheeler, K TI Letting thoughts take wing SO AEROSPACE AMERICA LA English DT Article C1 NASA, Ames Res Ctr, Computat Sci Div, Moffett Field, CA 94035 USA. RP Jorgensen, C (reprint author), NASA, Ames Res Ctr, Computat Sci Div, Moffett Field, CA 94035 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 USA SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD MAR PY 2002 VL 40 IS 3 BP 33 EP 37 PG 5 WC Engineering, Aerospace SC Engineering GA 530CZ UT WOS:000174339200011 PM 11898824 ER PT J AU Wang, FY Zaman, KBMQ AF Wang, FY Zaman, KBMQ TI Aerodynamics of a jet in the vortex wake of a wing SO AIAA JOURNAL LA English DT Article AB Results of a low-speed experimental investigation of jet behavior in the trailing vortex wake of a wing are presented. The effects of varying jet-to-freestream velocity ratio and vortex-wake strength on the downstream evolution of the flowfield are quantified via three-dimensional hot-wire anemometry surveys. Under conditions encountered in powered flight, especially flow states characteristics of takeoff, landing, and maneuvering of a vehicle, the jet is found to undergo severe distortion within a very short distance from the nozzle exit. The interaction of the jet and the wing vortices generates additional vortical structures. Spreading and decay of the jet are shown to be governed predominantly by the interaction of the vortices. C1 NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. John A Volpe Natl Transportat Syst Ctr, Cambridge, MA 02142 USA. RP Wang, FY (reprint author), NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. NR 15 TC 12 Z9 12 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD MAR PY 2002 VL 40 IS 3 BP 401 EP 407 DI 10.2514/2.1669 PG 7 WC Engineering, Aerospace SC Engineering GA 528VG UT WOS:000174264500001 ER PT J AU Mercer, CR Raman, G AF Mercer, CR Raman, G TI Quantitative interferometry in the severe acoustic environment of resonant supersonic jets SO AIAA JOURNAL LA English DT Article ID POINT-DIFFRACTION INTERFEROMETER; SCREECH AB Understanding fundamental fluidic dynamic and acoustic processes in high-speed jets requires quantitative velocity, density, and temperature measurements. We demonstrate a new, robust liquid crystal point diffraction interferometer (LCPDI) that includes phase stepping and can provide accurate data even in the presence of intense acoustic fields. This novel common path interferometer was developed to overcome difficulties with the Mach-Zehnder interferometer in vibratory environments and is applied here to the case of a supersonic shock-containing jet. The environmentally insensitive LCPDI, which is easy to align and capable of measuring optical wavefronts with high accuracy, is briefly described, and then integrated line of sight density data from the LCPDI for two underexpanded jets are presented. C1 NASA, John H Glenn Res Ctr, Opt Instrumentat Technol Branch, Cleveland, OH 44135 USA. IIT, Mech Mat & Aerosp Engn Dept, Chicago, IL 60616 USA. RP Mercer, CR (reprint author), NASA, John H Glenn Res Ctr, Opt Instrumentat Technol Branch, Cleveland, OH 44135 USA. NR 16 TC 0 Z9 0 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD MAR PY 2002 VL 40 IS 3 BP 438 EP 442 DI 10.2514/2.1693 PG 5 WC Engineering, Aerospace SC Engineering GA 528VG UT WOS:000174264500005 ER PT J AU Takaki, R Liou, MS AF Takaki, R Liou, MS TI Parametric study of heat release preceding a blunt body in hypersonic flow SO AIAA JOURNAL LA English DT Article AB A computational parametric study is presented illustrating the effects of upstream heat release on drag and heating rate in hypersonic flow over an axisymmetric blunt body. A chemical nonequilibrium viscous flow is considered with seven species; Park's two-temperature model is also used to take account of thermally nonequilibrium phenomena. Three parameters that control the heat release are introduced, and their effects on the flow structure, specifically with respect to drag and heating rate, are quantified. Results show that heat release upstream of the body can reduce not only the aerodynamic drag but also the aerodynamic heating rate at the body surface. Computed results achieved a reduction of 23% in drag and 74% in heating rate, relative to baseline values in the absence of heat release. The reduction mechanism is discussed, and dynamic pressure is shown to play an important role in the drag reduction mechanism. C1 NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. RP Takaki, R (reprint author), NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. NR 17 TC 8 Z9 9 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD MAR PY 2002 VL 40 IS 3 BP 501 EP 509 DI 10.2514/2.1674 PG 9 WC Engineering, Aerospace SC Engineering GA 528VG UT WOS:000174264500014 ER PT J AU Subramanian, CS Amer, TR Oglesby, DM Burkett, CG AF Subramanian, CS Amer, TR Oglesby, DM Burkett, CG TI New self-referencing pressure-sensitive-paint measurement SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT 21st Aerodynamic Measurement Technology and Ground Testing Conference CY JUN 19-22, 2000 CL DENVER, COLORADO C1 Florida Inst Technol, Melbourne, FL 32901 USA. NASA, Langley Res Ctr, Instrument Status Data Block, Hampton, VA 23681 USA. RP Subramanian, CS (reprint author), Florida Inst Technol, 150 W Univ Blvd, Melbourne, FL 32901 USA. OI Subramanian, Chelakara S./0000-0003-4149-2972 NR 9 TC 3 Z9 3 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD MAR PY 2002 VL 40 IS 3 BP 582 EP 584 PG 3 WC Engineering, Aerospace SC Engineering GA 528VG UT WOS:000174264500026 ER PT J AU Arnaud, SB Navidi, M Deftos, L Thierry-Palmer, M Dotsenko, R Bigbee, A Grindeland, RE AF Arnaud, SB Navidi, M Deftos, L Thierry-Palmer, M Dotsenko, R Bigbee, A Grindeland, RE TI The calcium endocrine system of adolescent rhesus monkeys and controls before and after spaceflight SO AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM LA English DT Article DE rhesus monkey; 1,25-dihydroxyvitamin D ID PARATHYROID-HORMONE; BED REST; CALCITONIN; 1,25-DIHYDROXYVITAMIN-D; ABSORPTION; RESTRAINT; PRIMATE; PLASMA; INVIVO; GENE AB The calcium endocrine system of nonhuman primates can be influenced by chairing for safety and the weightless environment of space-flight. The serum of two rhesus monkeys flown on the Bion 11 mission was assayed pre- and postflight for vitamin D metabolites, parathyroid hormone, calcitonin, parameters of calcium homeostasis, cortisol, and indexes of renal function. Results were compared with the same measures from five monkeys before and after chairing for a flight simulation study. Concentrations of 1,25-dihydroxyvitamin D were 72% lower after the flight than before, and more than after chairing on the ground (57%, P<0.05). Decreases in parathyroid hormone did not reach significance. Calcitonin showed modest decreases postflight (P<0.02). Overall, effects of space-flight on the calcium endocrine system were similar to the effects of chairing on the ground, but were more pronounced. Reduced intestinal calcium absorption, losses in body weight, increases in cortisol, and higher postflight blood urea nitrogen were the changes in flight monkeys that distinguished them from the flight simulation study animals. C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. Vet Affairs Med Ctr, San Diego, CA 92161 USA. Univ Calif San Diego, San Diego, CA 92161 USA. Morehouse Sch Med, Atlanta, GA 30310 USA. Inst Biomed Problems, Moscow 123007, Russia. RP Arnaud, SB (reprint author), NASA, Ames Res Ctr, Div Life Sci, SLR 239-11, Moffett Field, CA 94035 USA. NR 40 TC 3 Z9 3 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 0193-1849 J9 AM J PHYSIOL-ENDOC M JI Am. J. Physiol.-Endocrinol. Metab. PD MAR PY 2002 VL 282 IS 3 BP E514 EP E521 PG 8 WC Endocrinology & Metabolism; Physiology SC Endocrinology & Metabolism; Physiology GA 521HB UT WOS:000173832200003 PM 11832352 ER PT J AU Ortiz, RM Wade, CE Costa, DP Ortiz, CL AF Ortiz, RM Wade, CE Costa, DP Ortiz, CL TI Renal responses to plasma volume expansion and hyperosmolality in fasting seal pups SO AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY LA English DT Article DE aldosterone; cortisol; glomerular filtration rate; kidney; osmoregulation; vasopressin ID ATRIAL-NATRIURETIC-PEPTIDE; GLOMERULAR-FILTRATION RATE; CONSCIOUS DOGS; SALINE INFUSION; ANGIOTENSIN-II; VASOPRESSIN RELEASE; OSMOTIC CONTROL; EXCRETION; SODIUM; WATER AB Renal responses were quantified in northern elephant seal (Mirounga angustirostris) pups during their postweaning fast to examine their excretory capabilities. Pups were infused with either isotonic (0.9%; n = 8; Iso) or hypertonic (16.7%; n = 7; Hyper) saline via an indwelling catheter such that each pup received 3 mmol NaCl/kg. Diuresis after the infusions was similar in magnitude between the two treatments. Osmotic clearance increased by 37% in Iso and 252% in Hyper. Free water clearance was reduced 3.4-fold in Hyper but was not significantly altered in Iso. Glomerular filtration rate increased 71% in the 24-h period after Hyper, but no net change occurred during the same time after Iso. Natriuresis increased 3.6-fold in Iso and 5.3-fold in Hyper. Iso decreased plasma arginine vasopressin (AVP) and cortisol acutely, whereas Hyper increased plasma and excreted AVP and cortisol. Iso was accompanied by the retention of water and electrolytes, whereas the Hyper load was excreted within 24 h. Natriuresis is attributed to increased filtration and is independent of an increase in atrial natriuretic peptide and decreases in ANG II and aldosterone. Fasting pups appear to have well-developed kidneys capable of both extreme conservation and excretion of Na+. C1 Univ Calif Santa Cruz, Dept Biol, Santa Cruz, CA 95064 USA. NASA, Ames Res Ctr, Neuroendocrinol Lab, Div Life Sci, Moffett Field, CA 94035 USA. RP Ortiz, RM (reprint author), Univ Calif Santa Cruz, Dept Biol, Santa Cruz, CA 95064 USA. FU NIGMS NIH HHS [GM-58903-01] NR 50 TC 16 Z9 16 U1 0 U2 2 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 0363-6119 J9 AM J PHYSIOL-REG I JI Am. J. Physiol.-Regul. Integr. Comp. Physiol. PD MAR PY 2002 VL 282 IS 3 BP R805 EP R817 PG 13 WC Physiology SC Physiology GA 520JR UT WOS:000173779200023 PM 11832402 ER PT J AU Rashidnia, N Balasubramaniam, R AF Rashidnia, N Balasubramaniam, R TI Development of an interferometer for measurement of the diffusion coefficient of miscible liquids SO APPLIED OPTICS LA English DT Article AB A common-path interferometer (CPI) system was developed to measure the diffusivity of transparent liquid pairs by real-time visualization of the concentration gradient profile. The CPI is an optical technique that can be used to measure changes in the gradient of the refractive index of transparent materials. The CPI is a shearing interferometer that shares the same optical path from a laser light source to the final imaging plane. Molecular diffusivity of liquids can be determined by use of physical relations between changes in the optical path length and the liquid phase properties. The data obtained by this interferometer are compared with similar results from other techniques. This demonstrates that the instrument is reliable for measurement of the diffusivity of miscible liquids and allows the system to be compact and robust. It can also be useful for studies in interface dynamics as well as other applications in a low-gravity environment. (C) 2002 Optical Society of America. C1 NASA, Natl Ctr Micrograv Res Fluids & Combust, Cleveland, OH 44135 USA. RP NASA, Natl Ctr Micrograv Res Fluids & Combust, Mail Stop 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. EM nasser.rashidnia@grc.nasa.gov NR 12 TC 21 Z9 21 U1 0 U2 4 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAR 1 PY 2002 VL 41 IS 7 BP 1337 EP 1342 DI 10.1364/AO.41.001337 PG 6 WC Optics SC Optics GA 525VW UT WOS:000174095600018 PM 11900012 ER PT J AU Pauluhn, A Ruedi, I Solanki, SK Schuhle, U Wilhelm, K Lang, J Thompson, WT Hollandt, J Huber, MCE AF Pauluhn, A Ruedi, I Solanki, SK Schuhle, U Wilhelm, K Lang, J Thompson, WT Hollandt, J Huber, MCE TI Intercalibration of SUMER and CDS on SOHO. II. SUMER detectors a and B and CDS NIS (vol 40, pg 6292, 2001) SO APPLIED OPTICS LA English DT Correction C1 Hsch Tech & Architekture, Inst Technol Transfer, CH-3000 Bern, Switzerland. ETH Zentrum, Inst Astron, CH-8092 Zurich, Switzerland. Phys Meteorol Observ, World Radiat Ctr, CH-7260 Davos, Switzerland. Max Planck Inst Aeron, D-37191 Katlenburg Lindau, Germany. Rutherford Appleton Lab, Didcot OX11 0QX, Oxon, England. NASA, Goddard Space Flight Ctr, Emergent Informat Technol Inc, Greenbelt, MD 20771 USA. Phys Tech Bundesanstalt, D-10587 Berlin, Germany. European Space Agcy, European Space Res & Technol Ctr, NL-2200 AG Noordwijk, Netherlands. RP Int Space Sci Inst, CH-3012 Bern, Switzerland. EM pauluhn@issi.unibe.ch RI Thompson, William/D-7376-2012; Hollandt, Jorg/A-2124-2014 NR 1 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAR 1 PY 2002 VL 41 IS 7 BP 1433 EP 1433 DI 10.1364/AO.41.001433 PG 1 WC Optics SC Optics GA 525VW UT WOS:000174095600031 ER PT J AU Toporski, JKW Steele, A Westall, F Thomas-Keprta, KL McKay, DS AF Toporski, JKW Steele, A Westall, F Thomas-Keprta, KL McKay, DS TI Winner of the 2001 Gerald A. Soffen Memorial Award - The simulated silicification of bacteria - New clues to the modes and timing of bacterial preservation and implications for the search for extraterrestrial microfossils SO ASTROBIOLOGY LA English DT Review DE bacteria; biofilms; silica; silicification; bacterial fossils; fossilization; experimental; transmission electron microscopy ID BARBERTON GREENSTONE-BELT; IN-SITU SILICIFICATION; SOUTH-AFRICA; BACILLUS-SUBTILIS; SULFATE REDUCTION; MARTIAN METEORITE; SEDIMENTARY-ROCKS; ESCHERICHIA-COLI; ONVERWACHT GROUP; FOSSIL BACTERIA AB Evidence of microbial, life on Earth has been found in siliceous rock formations throughout the geological and fossil record. To understand the mechanisms of silicification and thus improve our search patterns for evidence of fossil microbial life in rocks, a series of controlled laboratory experiments were designed to simulate the silicification of microorganisms. The bacterial strains Pseudomonas fluorescens and Desulphovibrio indonensis were exposed to silicifying media. The experiments were designed to determine how exposure time to silicifying solutions and to silicifying solutions of different Si concentration affect the fossilization of microbial biofilms. The silicified biofilms were analyzed using transmission electron microscopy (TEM) in combination with energy-dispersive spectroscopy. Both bacterial species showed evidence of silicification after 24 h in 1,000 ppm silica solution, although D. indonensis was less prone to silicification. The degree of silicification of individual cells of the same sample varied, though such variations decreased with increasing exposure time. High Si concentration resulted in better preservation of cellular detail; the Si concentration was more important than the duration in Si solution. Even though no evidence of amorphous silica precipitation was observed, bacterial cells became permineralized. High-resolution TEM analysis revealed nanometer-sized crystallites characterized by lattice fringe-spacings that match the {10-11} d-spacing of quartz formed within bacterial cell walls after 1 week in 5,000 ppm silica solution. The mechanisms of silicification under controlled laboratory conditions and the implication for silicification in ' natural e environments are discussed, along with the relevance of our findings in the search for early life on Earth and extraterrestrial life. C1 Carnegie Inst Washington, Geophys Lab, Washington, DC 20015 USA. Univ Portsmouth, Sch Earth Environm & Phys Sci, Portsmouth, Hants, England. CNRS, Ctr Biophys Mol, Orleans, France. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Toporski, JKW (reprint author), Carnegie Inst Washington, Geophys Lab, 5251 Broad Branch Rd NW, Washington, DC 20015 USA. NR 116 TC 79 Z9 84 U1 1 U2 16 PU MARY ANN LIEBERT INC PUBL PI LARCHMONT PA 2 MADISON AVENUE, LARCHMONT, NY 10538 USA SN 1531-1074 J9 ASTROBIOLOGY JI Astrobiology PD SPR PY 2002 VL 2 IS 1 BP 1 EP 26 DI 10.1089/153110702753621312 PG 26 WC Astronomy & Astrophysics; Biology; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Life Sciences & Biomedicine - Other Topics; Geology GA 671KF UT WOS:000182463400001 PM 12449852 ER PT J AU Brinton, KLF Tsapin, AI Gilichinsky, D McDonald, GD AF Brinton, KLF Tsapin, AI Gilichinsky, D McDonald, GD TI Aspartic acid racemization and age-depth relationships for organic carbon in Siberian permafrost SO ASTROBIOLOGY LA English DT Article DE racemization; permafrost; long-term survival; cold environments ID BACTERIA; MARS; MICROBES; BODIES; EARTH AB We have analyzed the degree of racemization of aspartic acid in permafrost samples from Northern Siberia, an area from which microorganisms of apparent ages up to a few million years have previously been isolated and cultured. We find that the extent of aspartic acid racemization in permafrost cores increases very slowly up to an age of similar to25,000 years (around 5 m in depth). The apparent temperature of racernization over the age range of 0-25,000 years, determined using measured aspartic acid racernization rate constants, is -19degreesC. This apparent racernization temperature, is significantly lower than the measured environmental temperature (-11 to -13degreesC) and suggests active recycling Of D-aspartic acid in Siberian permafrost up to, an age of around 25,000 years. This indicates that permafrost organisms are capable of repairing some molecular damage incurred while in a "dormant" state over geologic time. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Russian Acad Sci, Inst Physicochem & Biol Problems Soil Sci, Biol Res Ctr, Pushchino, Moscow Region, Russia. RP McDonald, GD (reprint author), CALTECH, Jet Prop Lab, MS 183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 20 Z9 21 U1 0 U2 6 PU MARY ANN LIEBERT INC PUBL PI LARCHMONT PA 2 MADISON AVENUE, LARCHMONT, NY 10538 USA SN 1531-1074 J9 ASTROBIOLOGY JI Astrobiology PD SPR PY 2002 VL 2 IS 1 BP 77 EP 82 DI 10.1089/153110702753621358 PG 6 WC Astronomy & Astrophysics; Biology; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Life Sciences & Biomedicine - Other Topics; Geology GA 671KF UT WOS:000182463400005 PM 12449856 ER PT J AU Freund, F Dickinson, JT Cash, M AF Freund, F Dickinson, JT Cash, M TI Hydrogen in rocks: An energy source for deep microbial communities SO ASTROBIOLOGY LA English DT Article DE hydrogen in rocks; deep microbial communities; solute water in minerals; redox conversion of hydroxyl pairs; peroxy in minerals ID MAGNESIUM-OXIDE; CHARGE-DISTRIBUTION; ANHYDROUS MINERALS; BASALT AQUIFERS; WATER; GENERATION; MANTLE; ECOSYSTEMS; OLIVINE; TRACES AB To survive in deep subsurface environments, lithotrophic microbial communities require a sustainable energy source such as hydrogen. Though H-2 can be produced when water reacts with fresh mineral surfaces and. oxidizes ferrous iron, this reaction is unreliable since it depends upon the exposure of fresh rock surfaces via the episodic opening of cracks and fissures. A more reliable and potentially more voluminous H-2 source exists in nominally anhydrous minerals of igneous and metamorphic rocks. Our experimental results indicate that H-2 molecules can be derived from small amounts of H2O dissolved in minerals in the form of hydroxyl, OH- or O3Si-OH, whenever such minerals crystallized in an H2O-laden environment. Two types of experiments were conducted. Single crystal fracture experiments indicated that hydroxyl pairs undergo an in situ redox conversion to H-2 molecules plus peroxy links, O3Si/(OO)\SiO3. While the peroxy links become part of the mineral structure, the H-2 molecules diffused out of the freshly fractured mineral surfaces. If such a mechanism occurred in natural settings, the entire rock column would become a volume source of H-2. Crushing experiments to facilitate the outdiffusion of H-2 were conducted with common crustal igneous rocks such as granite, andesite, and labradorite. At least 70 nmol of H-2/g diffused out of coarsely crushed andesite, equivalent at standard pressure and temperature to 5,000 cm(3) of H-2/m(3) of rock. In the water-saturated, biologically relevant upper portion of the rock column the diffusion of H-2 out of the minerals will be buffered by H-2 saturation of the intergranular water film. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. San Jose State Univ, SETI Inst, San Jose, CA 95192 USA. San Jose State Univ, Dept Phys, San Jose, CA 95192 USA. Washington State Univ, Dept Phys, Pullman, WA 99164 USA. RP Freund, F (reprint author), NASA, Ames Res Ctr, MS 239-20, Moffett Field, CA 94035 USA. NR 36 TC 21 Z9 21 U1 2 U2 17 PU MARY ANN LIEBERT INC PUBL PI LARCHMONT PA 2 MADISON AVENUE, LARCHMONT, NY 10538 USA SN 1531-1074 J9 ASTROBIOLOGY JI Astrobiology PD SPR PY 2002 VL 2 IS 1 BP 83 EP 92 DI 10.1089/153110702753621367 PG 10 WC Astronomy & Astrophysics; Biology; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Life Sciences & Biomedicine - Other Topics; Geology GA 671KF UT WOS:000182463400006 PM 12449857 ER PT J AU Hough, DH Vermeulen, RC Readhead, ACS Cross, LL Barth, EL Yu, LH Beyer, PJ Phifer, EM AF Hough, DH Vermeulen, RC Readhead, ACS Cross, LL Barth, EL Yu, LH Beyer, PJ Phifer, EM TI Parsec-scale radio structure and broad optical emission lines in a complete sample of 3CR lobe-dominated quasars SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : jets; galaxies : nuclei; quasars : emission lines; radio continuum ID ACTIVE GALACTIC NUCLEI; BANK VLBI SURVEY; SUPERLUMINAL MOTION; JETS; STATISTICS; MODELS; 3C-245; INTERFEROMETRY; SPECTRA; IMAGES AB We present results from VLBI observations of 24 of the 25 lobe-dominated quasars ( LDQs) in the 3CR complete sample and from optical spectrophotometry of 14 of these objects. The VLBI observations were made with a variety of arrays-most recently the Very Long Baseline Array at frequencies ranging from 5 to 22 GHz during the period 1981-1997. The optical spectra were obtained with the Hale 200 inch ( 5 m) telescope at Palomar Observatory, using the blue and red CCDs of the Double Spectrograph, between 1984 and 1992. The radio nuclei range in strength over nearly 3 orders of magnitude, from similar to0.9 Jy down to similar to3 mJy, and were imaged at typical resolutions of similar to0.5-1.0 mas and sensitivities of similar to0.1-0.2 mJy beam(-1). All 24 LDQs show detectable radio structure in their nuclei. All 19 objects for which VLBI images could be made show one-sided nuclear jets, often several milliarcseconds in length and significantly curved, on the same side of the compact core as the one-sided large-scale jets seen on Very Large Array images. No counterjets were observed; jet-to-counterjet ratios that virtually all exceed similar to10 suggest that these objects are all oriented within similar to70degrees to the line of sight. For the 10 sources in which parsec-scale jet speeds could be estimated, the well-defined motions range from. less than or similar toh(-1)c to similar to4h(-1) c; some ambiguous cases might allow for motions as fast as similar to8h(-1) c, even then they are not indicative of bulk Lorentz factors, gamma, in excess of similar to10h(-1) (H-0 = 100h km s(-1) Mpc(-1), q(0) = 0.5). While the present distribution of jet speeds is consistent with random orientations, it is more easily accomodated by a restricted range of orientations. Evidence for slower jet speeds and larger apparent bends close to the core support the concept of a transition zone in the inner few parsecs of these jets. There are significant correlations among the prominences of the cores and jets, relative jet length, maximum jet deflection angles, and variability amplitude, as well as possible trends involving jet speed and strength of compact jet knots; furthermore, these objects tend to exhibit flat-spectrum cores and steep-spectrum jets. These results are all consistent with orientation-dependent relativistic beaming effects and unification of core- and lobe-dominated quasars. We have also defined a new postulated measure of orientation, based on both prominence of the radio nucleus and projected linear size, that correlates very well with properties predicted to have strong orientation dependence on beaming models. Finally, we confirm earlier studies demonstrating an anticorrelation between the prominence of the radio nucleus and the width of broad Mg II lambda2798 optical emission lines; we also extend this result to C III] lambda1909 and, more generally, to all broad lines by simple scaling and normalization methods. This relationship suggests a restricted range of orientations for LDQs, and that the broad-line clouds may have a flattened distribution associated with the accretion zone surrounding a central supermassive black hole. C1 Netherlands Fdn Res Astron, NL-7990 AA Dwingeloo, Netherlands. CALTECH, Pasadena, CA 91125 USA. Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA. Rice Univ, Dept Space Phys & Astron, Houston, TX 77005 USA. Univ Delaware, Dept Math Sci, Newark, DE 19716 USA. Trinity Univ, Dept Phys & Astron, San Antonio, TX 78212 USA. RP Hough, DH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Yu, Lam/F-9025-2012 NR 96 TC 27 Z9 27 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAR PY 2002 VL 123 IS 3 BP 1258 EP 1287 DI 10.1086/338847 PG 30 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 534KN UT WOS:000174585700009 ER PT J AU Rebull, LM Makidon, RB Strom, SE Hillenbrand, LA Birmingham, A Patten, BM Jones, BF Yagi, H Adams, MT AF Rebull, LM Makidon, RB Strom, SE Hillenbrand, LA Birmingham, A Patten, BM Jones, BF Yagi, H Adams, MT TI Circumstellar disk candidates identified in NGC 2264 SO ASTRONOMICAL JOURNAL LA English DT Article DE open clusters and associations : individual (NGC 2264); stars : pre-main-sequence ID ORION-NEBULA-CLUSTER; INITIAL MASS FUNCTION; STAR-FORMING HISTORY; MAIN-SEQUENCE TRACKS; STELLAR POPULATION; MONOCEROS OB1; DARK CLOUD; NGC-2264; PHOTOMETRY; ULTRAVIOLET AB We present an optical and near-infrared study of a 45' x 45' field in NGC 2264, which includes both S Mon and the Cone Nebula. We report photometry at optical (UBVRCIC) and near-infrared (JHK) wavelengths for similar to5600 stars and spectroscopic classifications for similar to400 of these stars. We identify circumstellar disk candidates using three techniques: excess ultraviolet ( U V) emission, excess near-IR (I-K and H-K) emission, and Halpha emission-line equivalent widths for those stars with spectra. We find generally good correlation between disk indicators thought to originate from different physical processes. We find little if any evolution of disk fraction with stellar age or mass. However, when we derive mass accretion rates ((M)over dot) from the excess emission at U, we find that (M)over dot decreases with age over the age range spanned by our data, similar to0.1-5 Myr, and increases with mass over the range similar to0.25-1 M-circle dot. These findings are comparable to results found previously by us in the Orion Nebula cluster flanking fields. C1 CALTECH, Jet Prop Lab, NASA, Pasadena, CA 91109 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Natl Opt Astron Observ, Tucson, AZ USA. CALTECH, Dept Astron, Pasadena, CA 91125 USA. Amherst Coll, Five Coll Astron Dept, Amherst, MA 01002 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Calif Santa Cruz, Univ Calif Observ, Lick Observ, Santa Cruz, CA 95064 USA. Univ Massachusetts, Five Coll Dept Astron, Amherst, MA 01003 USA. Univ Texas, McDonald Observ, Ft Davis, TX 79734 USA. RP Rebull, LM (reprint author), CALTECH, Jet Prop Lab, NASA, 4800 Oak Grove Dr,Mail Stop 169-506, Pasadena, CA 91109 USA. OI Rebull, Luisa/0000-0001-6381-515X NR 40 TC 87 Z9 87 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAR PY 2002 VL 123 IS 3 BP 1528 EP 1547 DI 10.1086/338904 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 534KN UT WOS:000174585700028 ER PT J AU Dumas, C Terrile, RJ Smith, BA Schneider, G AF Dumas, C Terrile, RJ Smith, BA Schneider, G TI Astrometry and near-infrared photometry of Neptune's inner satellites and ring arcs SO ASTRONOMICAL JOURNAL LA English DT Article DE astrometry; planets and satellites : individual (Neptune); techniques : photometric ID URANUS; TELESCOPE; VOYAGER-2; PROTEUS; DARK AB We report 1.87 mum photometry and astrometry of the inner satellites ( Proteus, Larissa, Galatea, and Despina) and ring arcs of Neptune, obtained with the Hubble Space Telescope and its near-infrared camera NICMOS. From comparison with the Voyager data obtained at visible wavelengths, the small bodies orbiting within the ring region of Neptune have a near-infrared albedo consistently low, but higher than at visible wavelengths for most of the satellites, ranging from p(1.87) (mum) = 0.058 (Despina) to p(1.87) (mum) = 0.094 (Proteus). The ring arcs display a reddish spectral response similar to the satellites in the 0.5-1.9 mum wavelength range. If we consider an earlier photometric measurement of Proteus obtained at K band, the satellite's albedo shows a depression at 2.2 mum that could be the first spectral evidence for the presence of C-H or C=N bearing material on its surface. Although astrometry of the inner moons of Neptune yields positions consistent with the predictions derived from Voyager images, the long time base between the Voyager and NICMOS observations allows us to re ne our knowledge of their mean motions and semimajor axes, and to decrease the errors associated with these measurements. In addition, we confirm a mismatch between the mean semimajor axis of the ring arcs and the location of the 42:43 corotation inclined resonance due to Galatea. This result calls into question the ability of this resonance to con ne the arcs azimuthally. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. RP Dumas, C (reprint author), CALTECH, Jet Prop Lab, Mail Stop 183-501,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 31 TC 12 Z9 12 U1 0 U2 1 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 MAR PY 2002 VL 123 IS 3 BP 1776 EP 1783 DI 10.1086/339022 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 534KN UT WOS:000174585700042 ER PT J AU Gorosabel, J Fynbo, JU Hjorth, J Wolf, C Andersen, MI Pedersen, H Christensen, L Jensen, BL Moller, P Afonso, J Treyer, MA Mallen-Ornelas, G Castro-Tirado, AJ Fruchter, A Greiner, J Pian, E Vreeswijk, PM Frontera, F Kaper, L Klose, S Kouveliotou, C Masetti, N Palazzi, E Rol, E Salamanca, I Tanvir, N Wijers, RAMJ van den Heuvel, E AF Gorosabel, J Fynbo, JU Hjorth, J Wolf, C Andersen, MI Pedersen, H Christensen, L Jensen, BL Moller, P Afonso, J Treyer, MA Mallen-Ornelas, G Castro-Tirado, AJ Fruchter, A Greiner, J Pian, E Vreeswijk, PM Frontera, F Kaper, L Klose, S Kouveliotou, C Masetti, N Palazzi, E Rol, E Salamanca, I Tanvir, N Wijers, RAMJ van den Heuvel, E TI Strategies for prompt searches for GRB afterglows: The discovery of the GRB 001011 optical/near-infrared counterpart using colour-colour selection SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE galaxies : fundamental parameters galaxies : statistics; gamma rays : bursts; techniques : photometric; quasars : general ID GAMMA-RAY BURST; HIGH-REDSHIFT GALAXIES; 28 FEBRUARY 1997; ERROR BOX; STANDARD STARS; X-RAY; EMISSION; FIELD; QUASARS; LOCALIZATIONS AB We report the discovery of the optical and near-infrared counterparts to GRB 001011. The GRB 001011 error box determined by Beppo-SAX was simultaneously imaged in the near-infrared by the 3.58-m New Technology Telescope and in the optical by the 1.54-m Danish Telescope similar to8 hr after the gamma-ray event. Here we implement the colour-colour discrimination technique proposed by Rhoads (2001) and extend it using near-IR data as well. We present the results provided by an automatic colour-colour discrimination pipe-line developed to discern the different populations of objects present in the GRB 001011 error box. Our software revealed three candidates based on single-epoch images. Second-epoch observations carried out similar to3.2 days after the burst revealed that the most likely candidate had faded, thus identifying it with the counterpart to the GRB. In deep R-band images obtained 7 months after the burst a faint (R = 25.38+/-0.25) elongated object, presumably the host galaxy of GRB 001011, was detected at the position of the afterglow. The GRB 001011 afterglow is the first discovered with the assistance of colour-colour diagram techniques. We discuss the advantages of using this method and its application to error boxes determined by future missions. C1 Danish Space Res Inst, DK-2100 Copenhagen O, Denmark. European So Observ, D-85748 Garching, Germany. Univ Copenhagen, Astron Observ, DK-2100 Copenhagen O, Denmark. Observ Midi Pyrenees, LAS, F-31400 Toulouse, France. Max Planck Inst Astron, D-69117 Heidelberg, Germany. Univ Oulu, Div Astron, Oulu 90014, Finland. Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2BW, England. Astron Spatiale Lab, F-13376 Marseille, France. Univ Toronto, Dept Astron, Toronto, ON M5S 3H8, Canada. LAEFF, INTA, Madrid 28080, Spain. Inst Astrofis Andalucia, CSIC, E-18080 Granada, Spain. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Inst Astrophys, Potsdam, Germany. Osserv Astron Trieste, I-34131 Trieste, Italy. Univ Amsterdam, NL-1098 SJ Amsterdam, Netherlands. CNR, Ist Tecnol & Studio Radiaz Extraterr, I-40129 Bologna, Italy. Thuringer Landessternwarte Tautenburg, D-07778 Tautenburg, Germany. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Hertfordshire, Dept Phys Sci, Hatfield AL10 9AB, Herts, England. SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA. RP Gorosabel, J (reprint author), Danish Space Res Inst, Juliane Maries Vej 30, DK-2100 Copenhagen O, Denmark. RI Christensen, Lise/M-5301-2014; Hjorth, Jens/M-5787-2014; Jensen, Brian Lindgren/E-1275-2015; Afonso, Jose/B-5185-2013; Palazzi, Eliana/N-4746-2015; OI Christensen, Lise/0000-0001-8415-7547; Hjorth, Jens/0000-0002-4571-2306; Jensen, Brian Lindgren/0000-0002-0906-9771; Castro-Tirado, A. J./0000-0003-2999-3563; Pian, Elena/0000-0001-8646-4858; Afonso, Jose/0000-0002-9149-2973; Palazzi, Eliana/0000-0002-8691-7666 NR 75 TC 19 Z9 19 U1 0 U2 1 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAR PY 2002 VL 384 IS 1 BP 11 EP 23 DI 10.1051/0004-6361:20011598 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527KP UT WOS:000174185500004 ER PT J AU Norton, AJ Quaintrell, H Katajainen, S Lehto, HJ Mukai, K Negueruela, I AF Norton, AJ Quaintrell, H Katajainen, S Lehto, HJ Mukai, K Negueruela, I TI Pulsations and orbital modulation of the intermediate polar 1WGA J1958.2+3232 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE novae, cataclysmic variables; stars : magnetic fields; stars : individual; 1WGA J1958.2+3232 ID PERIOD AB We present optical photometry, spectroscopy and photopolarimetry, as well as ASCA X-ray observations, of the recently discovered intermediate polar 1WGA J1958.2+3232. Through the first detection of an optical beat frequency, we confirm the previously tentative suggestion that the spin period of the white dwarf is twice the X-ray and optical pulsation period, which we also confirm in each case. We detect an orbital modulation in each of the U, B, V, R and I bands for the first time, and suggest that the true orbital period is the -1d alias of that previously suggested. We also confirm the presence of circular polarization in this system, detecting a variable polarization which has opposite signs in each of the B and R bands. The double peaked pulse profile and oppositely signed polarization pulses suggest that 1WGA J1958.2+3232 accretes onto both magnetic poles via a disc which is truncated relatively close to the white dwarf. C1 Open Univ, Dept Phys & Astron, Milton Keynes MK7 6AA, Bucks, England. Turku Univ, Tuorla Observ, Piikkio 21500, Finland. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Observ Astron, F-67000 Strasbourg, France. RP Norton, AJ (reprint author), Open Univ, Dept Phys & Astron, Walton Hall, Milton Keynes MK7 6AA, Bucks, England. EM A.J.Norton@open.ac.uk; H.Quaintrell@open.ac.uk; sekataja@astro.utu.fi; hlehto@astro.utu.fi; mukai@milkyway.gsfc.nasa.gov; ignacio@isaac.u-strasbg.fr RI Negueruela, Ignacio/L-5483-2014; OI Negueruela, Ignacio/0000-0003-1952-3680; Norton, Andrew/0000-0001-7619-8269 NR 16 TC 20 Z9 20 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 MAR PY 2002 VL 384 IS 1 BP 195 EP 205 DI 10.1051/0004-6361:20011820 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527KP UT WOS:000174185500020 ER PT J AU Lanzafame, AC Brooks, DH Lang, J Summers, HP Thomas, RJ Thompson, AM AF Lanzafame, AC Brooks, DH Lang, J Summers, HP Thomas, RJ Thompson, AM TI ADAS analysis of the differential emission measure structure of the inner solar corona - Application of the data adaptive smoothing approach to the SERTS-89 active region spectrum SO ASTRONOMY & ASTROPHYSICS LA English DT Review DE Sun : atmosphere; Sun : corona; Sun : UV radiation; atomic data; methods : data analysis; techniques : spectroscopic ID EUV-ROCKET-TELESCOPE; ELECTRON-IMPACT-EXCITATION; EXPERIMENTAL LEVEL VALUES; BE-LIKE IONS; BERYLLIUM ISOELECTRONIC SEQUENCE; EFFECTIVE COLLISION STRENGTHS; FINE-STRUCTURE TRANSITIONS; C-LIKE NE; LINE-INTENSITIES; ATOMIC DATA AB The differential emission measure (DEM) of a solar active region is derived from SERTS-89 rocket data between 170 and 450 Angstrom (Thomas & Neupert 1994). The integral inversion to infer the DEM distribution from spectral line intensities is performed by the data adaptive smoothing approach (Thompson 1990, 1991). Our analysis takes into account the density dependence of both ionisation fractions and excitation coefficients according to the collisional-radiative theory as implemented in ADAS, the Atomic Data and Analysis Structure (McWhirter Summers 1984; Summers 1994; Summers 2001). Our strategy aims at checking, using observational data, the validity and limitations of the DEM method used for analysing solar EUV spectra. We investigate what information it is possible to extract, within defined limitations, and how the method can assist in a number of cases, e.g. abundance determination, spectral line identification, intensity predictions, and validation of atomic cross-sections. Using the above data and theory, it is shown that a spurious multiple peak in the DEM distribution between log(T-e) = 6.1 and 6.7, where T-e is the electron temperature, may derive from an inaccurate treatment of the population densities of the excited levels and ionisation fractions or from using an integral inversion technique with arbitrary smoothing. Therefore, complex DEM structures, like those proposed for solar and stellar coronae by several authors, must be considered with caution. We address also the issue of systematic differences between iso-electronic sequences and show that these cannot be unambiguously detected in the coronal lines observed by SERTS. Our results indicate that a substantial improvement is required in the atomic modelling of the complex element Fe. The elemental abundance ratio Si/Ne is found to be close to its photospheric value. The same result may be true for the Fe/Ne abundance, but this latter result is uncertain because of the problems found with Fe. C1 Catania Univ, Dipartimento Fis & Astron, I-95123 Catania, Italy. Univ Strathclyde, Dept Phys & Appl Phys, Glasgow G4 0NG, Lanark, Scotland. Rutherford Appleton Lab, Didcot OX11 0QX, Oxon, England. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Schlumberger GeoQuest Simulat Sofware Dev, Abingdon OX14 1DZ, Oxon, England. RP Lanzafame, AC (reprint author), Catania Univ, Dipartimento Fis & Astron, Via S Sofia 78, I-95123 Catania, Italy. RI Lanzafame, Alessandro/A-1129-2012 OI Lanzafame, Alessandro/0000-0002-2697-3607 NR 110 TC 26 Z9 26 U1 0 U2 3 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAR PY 2002 VL 384 IS 1 BP 242 EP 272 DI 10.1051/0004-6361:20011662 PG 31 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527KP UT WOS:000174185500025 ER PT J AU Standish, EM Fienga, A AF Standish, EM Fienga, A TI Accuracy limit of modern ephemerides imposed by the uncertainties in asteroid masses SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE astrometry; celestial mechanics; ephemerides; solar system : minor planets; planets and satelites : general AB Accuracy limits in the ephemerides of the four inner planets, imposed by uncertainties in the masses of the asteroids, are investigated and illustrated. We consider present-day knowledge of the asteroid masses (determined by the IRAS survey, direct dynamical determinations, ground-based photometry, occultations, etc.), and we model the distribution of those masses. This distribution is then used in a Monte Carlo study, repeatedly adjusting the ephemerides to fit the observational data, each time using a different, but equally-likely, set of asteroid masses. The differences in the resulting ephemerides are shown. If the full inherent weighting of the highly accurate ranging data is used, stretching over more than two decades, the orbits become distorted in right ascension and declination-as much as 5 kilometers or more. If the ranging is de-weighted to a level equivalent to the other two coordinates (1-2 mas, determined by VLBI), then a reasonable ephemeris results, showing uncertainties of 2-3 kilometers. It is also possible to produce an ephemeris which will extrapolate a year or so into the future at the sub-kilometer level (as is often required for spacecraft navigation). This can be done by fully-weighting only the recent observational data. However, the ephemeris farther from the fitting interval is seen to deteriorate rapidly. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Inst Mecan Celeste & Calculs Ephemerides, F-75014 Paris, France. RP Fienga, A (reprint author), CALTECH, Jet Prop Lab, JPL 301-150, Pasadena, CA 91109 USA. NR 14 TC 30 Z9 33 U1 0 U2 2 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAR PY 2002 VL 384 IS 1 BP 322 EP 328 DI 10.1051/0004-6361:20011821 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527KP UT WOS:000174185500031 ER PT J AU Mennella, A Bersanelli, M Burigana, C Maino, D Mandolesi, N Morgante, G Stanghellini, G AF Mennella, A Bersanelli, M Burigana, C Maino, D Mandolesi, N Morgante, G Stanghellini, G TI PLANCK: Systematic effects induced by periodic fluctuations of arbitrary shape SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE cosmology : cosmic microwave background, observations; instrumentation : detectors, miscellaneous methods : analytical ID LFI INSTRUMENT; DESIGN AB A fundamental requirement in the new generation of high resolution Cosmic Microwave Background imaging experiments is a strict control of systematic errors that must be kept at muK level in the final maps. Some of these errors are of celestial origin, while others will be generated by periodic fluctuations of the satellite environment. These environment instabilities will cause fluctuations in the measured signal output thus generating correlated effects in the reconstructed maps. In this paper we present an analytical study of the impact of periodic signal fluctuations on the measured sky maps produced by the Planck survey. In particular we show how it is possible to estimate analytically the damping factor of the peak-to-peak amplitude of the fluctuation at the instrument output after the projection in the final maps. C1 CNR, IFC, I-20133 Milan, Italy. Univ Milan, I-20133 Milan, Italy. CNR, TESRE, I-40126 Bologna, Italy. Osserv Astron Trieste, I-34131 Trieste, Italy. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Mennella, A (reprint author), CNR, IFC, Via Bassini 15, I-20133 Milan, Italy. OI Morgante, Gianluca/0000-0001-9234-7412; Burigana, Carlo/0000-0002-3005-5796 NR 24 TC 23 Z9 23 U1 0 U2 0 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAR PY 2002 VL 384 IS 2 BP 736 EP 742 DI 10.1051/0004-6361:20020024 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 528PW UT WOS:000174253000037 ER PT J AU Eiroa, C Oudmaijer, RD Davies, JK de Winter, D Garzon, F Palacios, J Alberdi, A Ferlet, R Grady, CA Cameron, A Deeg, HJ Harris, AW Horne, K Merin, B Miranda, LF Montesinos, B Mora, A Penny, A Quirrenbach, A Rauer, H Schneider, J Solano, E Tsapras, Y Wesselius, PR AF Eiroa, C Oudmaijer, RD Davies, JK de Winter, D Garzon, F Palacios, J Alberdi, A Ferlet, R Grady, CA Cameron, A Deeg, HJ Harris, AW Horne, K Merin, B Miranda, LF Montesinos, B Mora, A Penny, A Quirrenbach, A Rauer, H Schneider, J Solano, E Tsapras, Y Wesselius, PR TI On the simultaneous optical and near-infrared variability of pre-main sequence stars SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : formation; stars : pre-main-sequence; stars : variables : general; stars : circumstellar matter; accretion, accretion disks ID T-TAURI STAR; HERBIG AE/BE STARS; YOUNG STELLAR OBJECTS; UX ORIONIS; ACCRETION; RY; POLARIZATION; POLARIMETRY; EXTINCTION; PHOTOMETRY AB For a complete understanding of the physical processes causing the photometric variability of pre-main sequence systems, simultaneous optical and near-IR observations are required to disentangle the emission from the stars and that from their associated circumstellar disks. Data of this sort are extremely rare and little systematic work has been reported to date. The work presented in this paper is a systematic attempt in this direction. It presents an analysis of the simultaneous optical and near-IR photometric variability of 18 Herbig Ae/Be and T Tauri stars which were observed in October 98 by the EXPORT collaboration. The time difference between the UBVRI and JHK measurements is less than 1 hour in approximate to 50% of the data and the largest difference is around 2 hours in only approximate to 10% of the data. Twelve stars appear to show a correlation between the optical and near-IR variability trends, which suggests a common physical origin such as spots and/or variable extinction. The optical and near-IR variability is uncorrelated in the rest of the objects, which suggests it originates in distinctly different regions. In general, the optical variability qualitatively follows the predictions of starspots or variable extinction. As far as the near-IR is concerned, the simultaneity of the observations demonstrates that for most objects the flux is largely produced by their circumstellar disks and, consequently, in many cases the near-IR fluctuations must be attributed to structural variations of such disks producing variations of their thermal emission and/or scattered light. The observed near-IR changes of up to around 1 mag on timescales of 1-2 days provide interesting challenges for understanding the mechanisms generating such remarkable variabilities, an issue insufficiently investigated until now but one which deserves further theoretical and modeling efforts. C1 Univ Autonoma Madrid, Fac Ciencias, Dept Fis Teor, E-28049 Madrid, Spain. Univ Leeds, Dept Phys & Astron, Leeds LS2 9JT, W Yorkshire, England. Royal Observ, Astron Technol Ctr, Edinburgh, Midlothian, Scotland. TNO, TPD Space Instrumentat, NL-2600 AD Delft, Netherlands. Inst Astrofis Canarias, Tenerife 38200, Spain. Inst Astrofis Andalucia, E-18080 Granada, Spain. CNRS, Inst Astrophys Paris, F-75014 Paris, France. NASA, Goddard Space Flight Ctr, NOAO, STIS, Greenbelt, MD 20771 USA. Univ St Andrews, St Andrews KY16 9SS, Fife, Scotland. DLR, Dept Planetary Explorat, D-12489 Berlin, Germany. VILSPA, LAEFF, Madrid 28080, Spain. Rutherford Appleton Lab, Didcot OX11 0QX, Oxon, England. Univ Calif San Diego, Ctr Astrophys & Space Sci, Dept Phys, La Jolla, CA 92093 USA. Observ Paris, F-92195 Meudon, France. SRON, NL-9700 AV Groningen, Netherlands. RP Eiroa, C (reprint author), Univ Autonoma Madrid, Fac Ciencias, Dept Fis Teor, C-XI, E-28049 Madrid, Spain. RI Solano, Enrique/C-2895-2017; Montesinos, Benjamin/C-3493-2017; OI Montesinos, Benjamin/0000-0002-7982-2095; Cameron, Andrew/0000-0002-8863-7828; Deeg, Hans-Jorg/0000-0003-0047-4241; Merin, Bruno/0000-0002-8555-3012 NR 44 TC 80 Z9 80 U1 1 U2 6 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAR PY 2002 VL 384 IS 3 BP 1038 EP 1049 DI 10.1051/0004-6361:20020096 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 532AC UT WOS:000174448600032 ER PT J AU Canuto, VM AF Canuto, VM TI Critical Richardson numbers and gravity waves SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE Sun : general; Sun : interior; convection; turbulence ID LARGE-EDDY SIMULATION; SHEAR INSTABILITIES; BOUNDARY-LAYER; ROTATING STARS; MAIN-SEQUENCE; TURBULENCE; CRITERION; DIFFUSION; MODELS; FLOWS AB In this paper we present two new results. The first concerns the proper identification of the critical Richardson number Ri(cr) above which there is no longer turbulent mixing. Thus far, all studies have assumed that: Ri(cr) = Ri(l) (cr) = 1/4. (1) However, since Ri(l) (cr) determines the upper limit of a laminar regime (superscript l), it has little relevance to stars where the problem is not to determine the end point of a laminar regime but the endpoint of turbulence. We show that the latter is characterized by Ri(t) (cr), where t stands for turbulence, and has a value four times larger than (1): Ri(cr) = Ri(t) (cr) approximate to 4Ri(l) (cr) approximate to 1. (2) We also show that use of (2) instead of (1) changes the conclusions of recent studies. Inclusion of radiative losses (characterized by the Peclet number Pe) which weaken stable stratification and help turbulence, further changes (2) to (r stands for radiative): Ri(cr) = Ri(r) (cr) similar to (1 + Pe)Pe(-1) Ri(t) (cr) (3) which, for Pe<1, allows turbulence to survive far longer than (2). Finally, turbulent convection generates gravity waves that propagate into the radiative region and act as an additional source of energy. This further changes Eq. (3) to (gw stands for gravity waves): Ri(cr) = Ri(gw) (cr) = Ri(r) (1 + η(gw)) (4) where η(gw) > 1. In conclusion, the successive inclusion of relevant physical processes leads to a chain of increasing values of Ri(cr): Ri(cr) = Ri(l) (cr) --> Ri(t) (cr) --> Ri(r) (cr) --> Ri(gw) (cr): (5) The second result concerns the dependence of the diffusivity D on Omega. We show that the commonly used expression Dchi-1 similar to (Omega/N)(2) (6) is not correct for the regime Pe<1 that characterizes a stably stratified regime. The proper &UOmega;-dependence is: Dχ-1 &SIM; (&UOmega;/N)(4) (7). C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Dept Appl Phys & Math, New York, NY 10027 USA. RP Canuto, VM (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 28 TC 21 Z9 22 U1 0 U2 3 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAR PY 2002 VL 384 IS 3 BP 1119 EP 1123 DI 10.1051/0004-6361:20011773 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 532AC UT WOS:000174448600039 ER PT J AU Popov, MV Bartel, N Cannon, WH Novikov, AY Kondratiev, VI Altunin, VI AF Popov, MV Bartel, N Cannon, WH Novikov, AY Kondratiev, VI Altunin, VI TI Microstructure of pulsar radio pulses measured with a time resolution of 62.5 ns at 1650 MHz SO ASTRONOMY REPORTS LA English DT Article ID EMISSION MECHANISM; SCINTILLATIONS; PSR-1133+16; FREQUENCIES; TURBULENCE; PLASMA AB We present an analysis of pulsar observations carried out on two frequency channels at 1634 MHz and 1650 MHz with a time resolution of 62.5 ns on the 70-m radio telescope of the NASA Deep Space Network in Tidbinbilla. The data were recorded using the S2 system, intended primarily for VLBI observations. Microstructure with characteristic timescales of 270, 80, and 150 mus was detected in pulsars B0833 - 45, B1749 - 28, and B1933 + 16, respectively. The distribution of microstructure timescales for the Vela pulsar (130833 - 45) is characterized by a gradual growth with decreasing timescale to 200 mus; the distribution has a maximum at 20-200 mus and falls off sharply for timescales below 20 mus. The statistical relation between the microstructure modulation index in and the corresponding timescale tau(mu) can be approximated by the power law dependance mproportional totau(mu)(0.5); i.e., the intensity is higher for inicropulses with longer durations. This contradicts the predictions of nonlinear models for the formation of micropulses by supercompact soliton wave packets. In all the pulsars studied, the time delays of the micropulses between the two frequency channels deviate from the expected dispersion laws for the interstellar plasma. In particular, the micropulses in the low-frequency channel arrive earlier than predicted by the dispersion measures derived previously from the mean pulse profiles. The deviation from the dispersion delay is determined most accurately for B0833 - 45, and is 4.9 +/- 0.2 mus. Such anomalous delays are probably associated with the effects of propagation of the radio emission within the pulsar magnetosphere. (C) 2002 MAIK "Nauka/Interperiodica". C1 Astro Space Ctr, Lebedev Phys Inst, Moscow 119991, Russia. York Univ, Dept Phys & Astron, Toronto, ON M2J 1P3, Canada. CRESTech, Space Geodynam Lab, Toronto, ON M2J 2K1, Canada. Jet Propuls Lab, Pasadena, CA 91109 USA. RP Popov, MV (reprint author), Astro Space Ctr, Lebedev Phys Inst, Profsoyuznaya 84-32, Moscow 119991, Russia. RI Popov, Mikhail/M-6118-2015; Kondratiev, Vladislav/N-1105-2015 OI Kondratiev, Vladislav/0000-0001-8864-7471 NR 41 TC 3 Z9 3 U1 0 U2 1 PU MAIK NAUKA/INTERPERIODICA PUBL PI MELVILLE PA C/O AMERICAN INST PHYSICS, 2 HUNTINGTON QUANDRANGLE, STE 1NO1, MELVILLE, NY 11747-4502 USA SN 1063-7729 J9 ASTRON REP+ JI Astron. Rep. PD MAR PY 2002 VL 46 IS 3 BP 206 EP 215 DI 10.1134/1.1463098 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 552XA UT WOS:000175644300004 ER PT J AU Nayakshin, S Kazanas, D AF Nayakshin, S Kazanas, D TI On time-dependent X-ray reflection by photoionized accretion disks: Implications for FeK alpha line reverberation studies of active galactic nuclei SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; galaxies : active; line : formation; radiative transfer; X-rays : general ID BLACK-HOLE MASS; COMPTON REFLECTION; EMISSION-LINE; COLD MATTER; NGC 3516; GAMMA-RAYS; VARIABILITY; MCG-6-30-15; SPECTRA; ULTRAVIOLET AB We perform the first study of time-dependent X-ray reflection in photoionized accretion disks. We assume a step-functional change in the X-ray flux and use a simplified prescription to describe the time evolution of the illuminated gas density profile in response to changes in the flux. We find that the dynamical time for readjustment of the hydrostatic balance is an important relaxation timescale of the problem since it affects the evolution of the ionization state of the reflector. If the variations of the X-ray flux occur on timescales shorter than this time, then the Fe Kalpha line emissivity is not a function of the instantaneous illuminating spectrum since it depends on the shape and intensity of the illuminating flux in prior times. Moreover, during the transition, a prominent Helium-like component of the Fe Kalpha line may appear. As a result, the Fe Kalpha line flux may appear to be completely uncorrelated with X-ray continuum flux on timescales shorter than the dynamical time. In addition, the time dependence of the illuminating flux may leave imprints even on the time-averaged Fe Kalpha line spectra, which may be used as an additional test of accretion disk geometry. Our findings appear to be important for the proposed Fe Kalpha line reverberation studies in lamppost-like geometries for accretion rates exceeding about similar to1% of the Eddington value. However, most active galactic nuclei do not show Helium-like lines that are prominent in such models, probably indicating that these models are not applicable to real sources. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. RP NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. NR 45 TC 31 Z9 31 U1 0 U2 1 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 MAR 1 PY 2002 VL 567 IS 1 BP 85 EP 96 DI 10.1086/338333 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 525BQ UT WOS:000174047700011 ER PT J AU Popescu, CC Tuffs, RJ Volk, HJ Pierini, D Madore, BF AF Popescu, CC Tuffs, RJ Volk, HJ Pierini, D Madore, BF TI Cold dust in late-type Virgo cluster galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : clusters : individual (Virgo); galaxies : dwarf; galaxies : ISM; galaxies : spiral; galaxies : statistics; infrared : galaxies ID FAR-INFRARED EMISSION; MOLECULAR LINE EMISSION; COMPACT DWARF GALAXIES; SPIRAL GALAXIES; EXTENDED DISTRIBUTION; SPECTRAL OBSERVATIONS; OPTICAL-PROPERTIES; RADIO CORRELATION; SILICATE GRAINS; NGC-891 AB We have statistically analyzed the spatially integrated far-infrared (FIR) emissions of the complete volume- and luminosity-limited sample of late-type (later than S0) Virgo Cluster galaxies measured using the Infrared Space Observatory by Tuffs and coworkers in bands centered on 60, 100, and 170 mum. Thirty of 38 galaxies detected at all three wavelengths contain a cold dust emission component, present within all morphological types of late-type systems ranging from early giant spiral galaxies to blue compact dwarfs (BCDs) and which could not have been recognized by IRAS. We fitted the data with a super-position of two modified blackbody functions, physically identified with a localized warm dust emission component associated with H II regions (whose temperature was constrained to be 47 K), and a diffuse emission component of cold dust. The cold dust temperatures were found to be broadly distributed, with a median of 18 K, some 8-10 K lower than would have been predicted from IRAS. The derived total dust mass is correspondingly increased by factors of typically 6-13. A good linear correlation is found between the "warm FIR" luminosities and the Halpha equivalent widths (EWs), supporting the assumptions of our constrained spectral energy distribution fit procedure. We also found a good nonlinear correlation between the "cold FIR" luminosities and the Halpha EWs, consistent with the prediction of Popescu and coworkers that the FIR-submillimeter emission should mainly be due to diffuse nonionizing UV photons. Both the "warm" and the "cold" FIR luminosity components are nonlinearly correlated with the (predominantly nonthermal) radio luminosities. There is a tendency for the temperatures of the cold dust component to become colder and for the cold dust surface densities (normalized to optical area) to increase for later morphological types. A particularly significant result concerns the low dust temperatures (ranging down to less than 10 K) and large dust masses associated with the Im and BCD galaxies in our sample. We propose two scenarios to account for the FIR characteristics of these systems. C1 Observ Carnegie Inst Washington, Pasadena, CA 91101 USA. Max Planck Inst Kernphys, D-69117 Heidelberg, Germany. Univ Toledo, Toledo, OH 43606 USA. NASA IPAC Extragalact Database, Pasadena, CA 91125 USA. RP Popescu, CC (reprint author), Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany. NR 72 TC 116 Z9 116 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 1 PY 2002 VL 567 IS 1 BP 221 EP 236 DI 10.1086/338383 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 525BQ UT WOS:000174047700021 ER PT J AU Hurley, K Berger, E Castro-Tirado, A Ceron, JMC Cline, T Feroci, M Frail, DA Frontera, F Masetti, N Guidorzi, C Montanari, E Hartmann, DH Henden, A Levine, SE Mazets, E Golenetskii, S Frederiks, D Morrison, G Oksanen, A Moilanen, M Park, HS Price, PA Prochaska, J Trombka, J Williams, G AF Hurley, K Berger, E Castro-Tirado, A Ceron, JMC Cline, T Feroci, M Frail, DA Frontera, F Masetti, N Guidorzi, C Montanari, E Hartmann, DH Henden, A Levine, SE Mazets, E Golenetskii, S Frederiks, D Morrison, G Oksanen, A Moilanen, M Park, HS Price, PA Prochaska, J Trombka, J Williams, G TI Afterglow upper limits for four short-duration, hard spectrum gamma-ray bursts SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts ID X-RAY; BEPPOSAX; SPECTROMETER; EMISSION AB We present interplanetary network localization, spectral, and time history information for four short-duration, hard spectrum gamma-ray bursts, GRB 000607, GRB 001025B, GRB 001204, and GRB 010119. All of these events were followed up with sensitive radio and optical observations (the first and only such bursts to be followed up in the radio to date), but no detections were made, demonstrating that the short bursts do not have anomalously intense afterglows. We discuss the upper limits and show that the lack of observable counterparts is consistent with both the hypothesis that the afterglow behavior of the short bursts is like that of the long-duration bursts, many of which similarly have no detectable afterglows, as well as the hypothesis that the short bursts have no detectable afterglows at all. Small number statistics do not allow a clear choice between these alternatives, but given the present detection rates of various missions, we show that progress can be expected in the near future. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. CALTECH, Pasadena, CA 91125 USA. CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain. Real Inst, Cadiz 11110, Spain. Observ Armada, Secc Astron, Cadiz 11110, Spain. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. CNR, Ist Astrofis Spaziale, I-00133 Rome, Italy. Natl Radio Astron Observ, Socorro, NM 87801 USA. CNR, Ist Tecnol & Studio Radiaz Extraterr, I-40129 Bologna, Italy. Univ Ferrara, Dipartmento Fis, I-44100 Ferrara, Italy. Clemson Univ, Dept Phys & Astron, Kinard Lab 118, Clemson, SC 29634 USA. USN Observ, Univ Space Res Assoc, Flagstaff, AZ 86002 USA. USN Observ, Flagstaff Stn, Flagstaff, AZ 86002 USA. AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia. CALTECH, IPAC, Pasadena, CA 91125 USA. Jyvaskylan Sirius Ry, Nyrola Observ, FIN-40100 Jyvaskyla, Finland. Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. CALTECH, Palomar Observ, Pasadena, CA 91125 USA. Carnegie Observ, Pasadena, CA 91101 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. RP Hurley, K (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RI Frederiks, Dmitry/C-7612-2014; Golenetskii, Sergey/B-3818-2015; OI Feroci, Marco/0000-0002-7617-3421; Castro-Tirado, A. J./0000-0003-2999-3563; Masetti, Nicola/0000-0001-9487-7740; Frederiks, Dmitry/0000-0002-1153-6340 NR 48 TC 51 Z9 52 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 1 PY 2002 VL 567 IS 1 BP 447 EP 453 DI 10.1086/338420 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 525BQ UT WOS:000174047700042 ER PT J AU Aurass, H Shibasaki, K Reiner, M Karlicky, M AF Aurass, H Shibasaki, K Reiner, M Karlicky, M TI Microwave detection of shock and associated electron beam formation SO ASTROPHYSICAL JOURNAL LA English DT Article DE shock waves; Sun : flares; Sun : radio radiation ID RADIO EVIDENCE; SOLAR CORONA; X-RAY; WAVES; ACCELERATION; ORIGIN; BURSTS; PROPAGATION; MECHANISM; FLARE AB We use complementary European and Japanese solar radio ground-based observations, together with Yohkoh soft X-ray and SOHO extreme-UV images, to search for the signature of flare-related waves at different heights above the Sun. The key data set for event selection is 40-800 MHz dynamic radio spectra from the Potsdam Astrophysical Institute, whose radio spectral polarimeter is sensitive to the coronal shock waves due to the associated type II radio bursts in the range between 0.2 and 1 R-circle dot. Nobeyama Radio Heliograph images at 17 GHz show the chromosphere and the transition region to the corona with unprecedented sensitivity and time resolution (1 s image cadence). Here we focused on 17 GHz images in the time interval between flare onset and the start of the metric type II burst. The decametric-hectometric (Dm-Hm; 1-14 MHz) radio experiment on board Wind completes the radio spectral coverage. The spectra are used to check if the coronal shock wave is also continuously visible in the range 3-8 R-circle dot and if the corona is open or closed for electron beams exciting hectometric type III bursts. We selected two flare events that show metric type II bursts, but with different associated 17 GHz features. For both events we find flare disturbances in 17 GHz images that propagate earlier than the type II bursts : a hot, dense blob (event 1; 1997 April 2) or a cold, absorbing cloud (event 2; 1998 July 31). In event 1, the hot and dense blob preceded the formation of a wave front segment that appeared in SOHO/EIT images. In event 2, we observed the impact of the 17 GHz absorbing cloud on a preexisting quiescent prominence far out of the flaring active region after several minutes of propagation without being disturbed. We demonstrate that the spectral pattern, as well as the drift rate, of the given type II burst drastically changes shortly before the cloud's impact. The Dm-Hm spectra in event 2 reveal a typical shock-associated (SA) event in the outer corona during the interaction between the absorbing cloud and the prominence. Finally, we stress that there may be a common driver for the metric type II bursts and simultaneous decimeter reverse-drift bursts between 1 and 2 GHz recorded on the radio spectrograph of Astronomical Observatory Ondrejov. C1 Astrophys Inst Potsdam, D-14482 Potsdam, Germany. Natl Astron Observ, Nobeyama Radio Observ, Minamisa Ku, Nagano 3841305, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Raytheon STX, Lanham, MD 20706 USA. Astron Observ Ondrejov, Ondrejov, Czech Republic. RP Aurass, H (reprint author), Astrophys Inst Potsdam, Sternwarte 16, D-14482 Potsdam, Germany. RI Karlicky, Marian/G-9023-2014 NR 34 TC 10 Z9 10 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 1 PY 2002 VL 567 IS 1 BP 610 EP 621 DI 10.1086/338417 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 525BQ UT WOS:000174047700056 ER PT J AU Menon, S Saxena, VK Durkee, P Wenny, BN Nielsen, K AF Menon, S Saxena, VK Durkee, P Wenny, BN Nielsen, K TI Role of sulfate aerosols in modifying the cloud albedo: a closure experiment SO ATMOSPHERIC RESEARCH LA English DT Article DE sulfate aerosols; cloud microphysics; cloud reflectivity; satellite retrievals; closure experiment ID CONDENSATION-NUCLEI; EFFECTIVE-RADIUS; SOLAR-RADIATION; SOUTHEASTERN US; NORTH-ATLANTIC; OPTICAL DEPTH; UNITED-STATES; CLIMATE MODEL; DROPLET; SENSITIVITY AB At a remote mountain-top location in the southeastern US, measurements were made to estimate the contribution of anthropogenic aerosols to the cloud albedo. The influence of the long-range transport of anthropogenic emissions on cloud microphysical and optical properties at the mountain top site was investigated. The sources of the cloud forming air masses were determined from back-trajectory analysis. Cloud water sulfate content was used as a surrogate for anthropogenic pollution. The effects of particulate sulfate on cloud condensation nuclei (CCN) concentration, cloud droplet number concentration (N), cloud droplet effective radii (R-eff) and cloud albedo were analyzed. A non-linear relationship between CCN and sulfate mass was obtained with a lowered sensitivity of CCN at high values of sulfate. Differences in N and sulfate from polluted to less polluted type air masses were much larger than that in R-eff. This could be due to the variability in cloud liquid water content (LWC) as R-eff is more related to LWC and cloud thickness than is N. The variability in cloud liquid water path (LWP) results in the optical depth being more sensitive to changes in R-eff than to N for differences in cloud pollutant content. As part of a "closure experiment", the cloud albedo calculated from in situ measurements for a 3-year period (1993-1995) compared well with that inferred from the Advanced Very High Resolution Radiometer (AVHRR) data. This accomplishes the objective of our closure experiment and proves that albedo of non-precipitating, thin, isolated clouds can be resolved against the dark forested background by AVHRR. The cloud reflectivity inferred from satellite measurements and that calculated from in situ observations were found to vary with the cloud water sulfate and N. Non-linear increases in satellite inferred cloud albedo with LWP suggest the importance of determining the contribution of cloud dynamic feedbacks on the indirect effect. (C) 2002 Elsevier Science B.V. All rights reserved. C1 N Carolina State Univ, Dept Marine Earth & Atmospher Sci, Raleigh, NC 27695 USA. Columbia Univ, NASA, GISS, New York, NY USA. USN, Postgrad Sch, Dept Meteorol, Monterey, CA 93943 USA. RP Saxena, VK (reprint author), N Carolina State Univ, Dept Marine Earth & Atmospher Sci, Box 8208, Raleigh, NC 27695 USA. EM saxena@eos.ncsu.edu NR 59 TC 13 Z9 14 U1 0 U2 3 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0169-8095 EI 1873-2895 J9 ATMOS RES JI Atmos. Res. PD MAR PY 2002 VL 61 IS 3 BP 169 EP 187 AR PII S0169-8095(01)00140-5 DI 10.1016/S0169-8095(01)00140-5 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 533JH UT WOS:000174525800001 ER PT J AU Rawat, N Connor, CW Jones, JA Kozlovskaya, IB Sullivan, P AF Rawat, N Connor, CW Jones, JA Kozlovskaya, IB Sullivan, P TI The correlation between aerobic fitness and motion sickness susceptibility SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE motion sickness; oxygen consumption; physical fitness AB Susceptibility to motion sickness has been linked to aerobic fitness in several studies, however, these studies have not elucidated the underlying physiological mechanism by which increased aerobic fitness is related to a decreased ability to tolerate motion sickness stimuli. This pilot study provides further evidence of a relationship between aerobic fitness and motion sickness susceptibility. It also suggests that aerobic capacity is more specifically linked to signs and symptoms of vasomotor origin including stomach discomfort, nausea and/or vomiting, headache, and diaphoresis. By independently correlating vasomotor susceptibility and neurogenic susceptibility to maximum oxygen uptake, we find that vasomotor symptoms in particular are significantly increased in aerobically fit individuals. Larger studies should be conducted to confirm this relationship. C1 Queens Univ, Queens Sch Med, Kingston, ON, Canada. MIT, Boston, MA USA. Johnson Space Ctr, Natl Aeronaut & Space Adm, Houston, TX USA. Inst Biomed Problems, Moscow, Russia. Canadian Space Agcy, St Hubert, PQ, Canada. RP Connor, CW (reprint author), Brigham & Womens Hosp, Longwood Med Res Ctr, Dept Radiol, 221 Longwood Ave, Boston, MA 02115 USA. RI Kozlovskaya, Inesa/R-9729-2016 NR 10 TC 4 Z9 5 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD MAR PY 2002 VL 73 IS 3 BP 216 EP 218 PG 3 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 527LD UT WOS:000174186800010 PM 11908888 ER PT J AU Roy, NK Courtenay, S Maxwell, G Yuan, ZP Chambers, RC Wirgin, I AF Roy, NK Courtenay, S Maxwell, G Yuan, ZP Chambers, RC Wirgin, I TI Cytochrome P4501A1 is induced by PCB 77 and benzo[a] pyrene treatment but not by exposure to the Hudson River environment in Atlantic tomcod (Microgadus tomcod) post-yolk sac larvae SO BIOMARKERS LA English DT Article DE competitive RT-PCR; cytochrome P4501A1; PCBs; PAHs; postlarvae; biomarkers ID LIFE-STAGE DEVELOPMENT; TROUT SALVELINUS-NAMAYCUSH; MESSENGER-RNA EXPRESSION; JUVENILE CHINOOK SALMON; FUNDULUS-HETEROCLITUS; 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN; CYP1A1; QUANTITATION; POPULATIONS; INDUCTION AB In fish, the embryos and larvae are the life-stages most sensitive to damage from environmentally borne dioxin-like compounds and polycyclic aromatic hydrocarbons (PAHs). Methods are not routinely available to measure the body burdens of contaminants in embryos and larvae, thus precluding the investigation of links between exposure and biological effects. Quantification of expression of cytochrome P4501A1 (CYP1A1) provides an index of relative exposure of natural populations to bioavailable aromatic hydrocarbons (AH) and an initial evaluation of their biological effects. We developed a quantitative approach to standardize total RNA loading and then used competitive reverse transcriptase-polymerase chain reaction (RT-PCR) to quantify the CYP1A1 mRNA expression in environmentally exposed Atlantic tomcod (Microgadus tomcod) post yolk-sac larvae (postlarvae) from the Hudson River, New York, and in chemically treated postlarval offspring of controlled laboratory crosses of Hudson River parents. Significant induction of CYP1A1 expression was observed in tomcod postlarvae exposed to waterborne 3, 3',4, 4'-tetrachlorobiphenyl (PCB 77) (four-fold) and benzo[ a] pyrene (eight-fold) compared with vehicle-exposed controls. In contrast, CYP1A1 was not induced in Hudson River-exposed postlarvae compared with vehicle-exposed controls. This study demonstrates the feasibility of using competitive RT-PCR for the measurement of gene expression in environmentally exposed larvae of sentinel species, and is consistent with the hypothesis that postlarvae exposed to the Hudson River environment have not bioaccumulated sufficient levels of AHs to induce CYP1A1 expression. The high levels of hepatic CYP1A1 mRNA expression previously reported in 5-8 month old juvenile tomcod from the Hudson River coincides with their descent to the benthic habitat and the onset of independent feeding on AH-contaminated benthic prey. C1 NYU, Sch Med, Inst Environm Med, Tuxedo Pk, NY 10987 USA. Fisheries & Oceans Canada, Gulf Fisheries Ctr, Moncton, NB E1C 9B6, Canada. Natl Marine Fisheries Serv, Howard Marine Sci Lab, Highlands, NJ 07732 USA. RP Wirgin, I (reprint author), NYU, Sch Med, Inst Environm Med, 57 Old Forge Rd, Tuxedo Pk, NY 10987 USA. FU NIEHS NIH HHS [ES10344, ES00260] NR 38 TC 10 Z9 10 U1 1 U2 4 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 1354-750X J9 BIOMARKERS JI Biomarkers PD MAR-APR PY 2002 VL 7 IS 2 BP 162 EP 173 DI 10.1080/13547500110113981 PG 12 WC Biotechnology & Applied Microbiology; Toxicology SC Biotechnology & Applied Microbiology; Toxicology GA 538RA UT WOS:000174827800006 PM 12101635 ER PT J AU Dickinson, RE Zebiak, SE Anderson, JL Blackmon, ML De Luca, C Hogan, TF Iredell, M Ji, M Rood, RB Suarez, MJ Taylor, KE AF Dickinson, RE Zebiak, SE Anderson, JL Blackmon, ML De Luca, C Hogan, TF Iredell, M Ji, M Rood, RB Suarez, MJ Taylor, KE TI How can we advance our weather and climate models as a community? SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article AB An argument is made for greater emphasis on shared infrastructure and commonality in codes and data. C1 Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. NOAA, Geophys Fluid Dynam Lab, Princeton, NJ USA. Lamont Doherty Earth Observ, Int Res Inst Climate Predict, Palisades, NY USA. USN, Res Lab, Marine Meteorol Div, Monterey, CA USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. NOAA, Natl Ctr Environm Predict, Boulder, CO USA. NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. Lawrence Livermore Natl Lab, Program Climate Model Diag & Intercomparison, Livermore, CA USA. RP Georgia Inst Technol, Sch Earth & Atmospher Sci, 221 Bobby Dodd Way, Atlanta, GA 30332 USA. EM robted@eas.gatech.edu RI Rood, Richard/C-5611-2008; Taylor, Karl/F-7290-2011 OI Rood, Richard/0000-0002-2310-4262; Taylor, Karl/0000-0002-6491-2135 NR 8 TC 13 Z9 13 U1 0 U2 0 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 MAR PY 2002 VL 83 IS 3 BP 431 EP 434 DI 10.1175/1520-0477(2002)083<0431:HCWAOW>2.3.CO;2 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 537HC UT WOS:000174752000022 ER PT J AU Hansen, JE AF Hansen, JE TI A brighter future SO CLIMATIC CHANGE LA English DT Editorial Material ID AIR-POLLUTION; CLIMATE C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Hansen, JE (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 8 TC 13 Z9 13 U1 0 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0165-0009 J9 CLIMATIC CHANGE JI Clim. Change PD MAR PY 2002 VL 52 IS 4 BP 435 EP 440 DI 10.1023/A:1014226429221 PG 6 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA 523YR UT WOS:000173985600007 ER PT J AU Hochedez, JF Alvarez, J Auret, FD Bergonzo, P Castex, MC Deneuville, A Defise, JM Fleck, B Gibart, P Goodman, SA Hainaut, O Kleider, JP Lemaire, P Manca, J Monroy, E Munoz, E Muret, P Nesladek, M Omnes, F Pace, E Pau, JL Ralchenko, V Roggen, J Schuhle, U Van Hoof, C AF Hochedez, JF Alvarez, J Auret, FD Bergonzo, P Castex, MC Deneuville, A Defise, JM Fleck, B Gibart, P Goodman, SA Hainaut, O Kleider, JP Lemaire, P Manca, J Monroy, E Munoz, E Muret, P Nesladek, M Omnes, F Pace, E Pau, JL Ralchenko, V Roggen, J Schuhle, U Van Hoof, C TI Recent progresses of the BOLD investigation towards UV detectors for the ESA Solar Orbiter SO DIAMOND AND RELATED MATERIALS LA English DT Article; Proceedings Paper CT 12th European Conference on Diamond Diamond-Like Materials Carbon Nanotubes Nitrides and Silicon Carbide (Diamond 2001) CY SEP 02-07, 2001 CL BUDAPEST, HUNGARY DE detectors; UV range; diamond; nitrides ID QUIET SUN; PHOTODETECTORS; SOHO; EIT AB BOLD (Blind to the Optical Light Detectors) is an international initiative dedicated to the development of novel imaging detectors for UV solar observations. It relies on the diamond and nitride materials that have lately undergone key advances. The investigation is proposed in view of Solar Orbiter UV instruments, for which the expected properties of the new sensors-visible blindness and radiation hardness-will be highly beneficial. Solar Orbiter is a selected Flexi mission of the European Space Agency (ESA). Despite various improvements over the last few decades, the present UV detectors exhibit limitations inherent to their actual technology. Yet the utmost spatial resolution, temporal cadence, sensitivity, and photometric accuracy will be decisive for the forthcoming space solar missions. The advent of imagers made of a large bandgap semiconductor would surmount many weaknesses, thus opening up new prospects and making the instruments cheaper. As for the ESA Solar Orbiter, the aspiration for wide bandgap semi conductor-based UV detectors is still more sensible, for the spacecraft will approach the Sun where the heat and the radiation fluxes are high. We depict motivations and present activities and programme to achieve revolutionary flight cameras within the Solar Orbiter schedule. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Observ Royal Belgique, Solar Phys Dept, B-1180 Brussels, Belgium. Max Planck Inst Aeron, Katlenburg Lindau, Germany. IMEC, Louvain, Belgium. Russian Acad Sci, Inst Gen Phys, Moscow 117942, Russia. Univ Florence, Dept Astron & Space Sci, XUV Lab, I-50125 Florence, Italy. ETSI Telecommun, UPM, Dept Ingn Elect, Madrid 28040, Spain. Inst Mat Res, Diepenbeek, Belgium. Univ Paris 11, Inst Astrophys Spatiale, F-91405 Orsay, France. Ctr Rech Hetero Epitaxie & Applicat, F-06560 Valbonne, France. NASA, Goddard Space Flight Ctr, ESA Space Sci Dept, Greenbelt, MD 20771 USA. Univ Liege, Ctr Spatial Liege, Angleur, Belgium. Etud Proprietes Elect Solides Lab, F-38042 Grenoble 9, France. Univ Paris 13, Phys Lasers Lab, F-93430 Villetaneuse, France. CEA, LETI, DEIN, SPE, F-91191 Gif Sur Yvette, France. Univ Pretoria, Dept Phys, Pretoria, South Africa. Ecole Super Elect, Lab Genie Elect Paris, F-91192 Gif Sur Yvette, France. RP Hochedez, JF (reprint author), Observ Royal Belgique, Solar Phys Dept, Circular Av 3, B-1180 Brussels, Belgium. RI Auret, Francois Danie/H-3512-2011; Fleck, Bernhard/C-9520-2012; Monroy, Eva/D-9593-2011; Pau, Jose Luis/L-1193-2014; Bergonzo, Philippe/A-6567-2015; OI Monroy, Eva/0000-0001-5481-3267; Bergonzo, Philippe/0000-0002-0647-9134; Muret, Pierre/0000-0003-1459-472X; Alvarez, Jose/0000-0003-3558-8302 NR 12 TC 17 Z9 18 U1 0 U2 0 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0925-9635 J9 DIAM RELAT MATER JI Diam. Relat. Mat. PD MAR-JUN PY 2002 VL 11 IS 3-6 SI SI BP 427 EP 432 AR PII S0925-9635(02)00034-1 DI 10.1016/S0925-9635(02)00034-1 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA 559VL UT WOS:000176046300030 ER PT J AU Harris, WM Morgenthaler, JP Scherb, F Anderson, C Oliversen, RJ AF Harris, WM Morgenthaler, JP Scherb, F Anderson, C Oliversen, RJ TI Wide field imaging and the velocity structure in the coma of Hale-Bopp SO EARTH MOON AND PLANETS LA English DT Article; Proceedings Paper CT IAU Colloquium No 186 on Cometary Science after Hale-Bopp CY JAN 21-25, 2002 CL CANARY ISL, SPAIN SP Int Astronom Union ID COMETARY ATMOSPHERES; CARBON PRODUCTION; IUE OBSERVATIONS; OH; P/HALLEY; EXPANSION; EVOLUTION; MODEL; H2O; O1 AB The comae of very active comets have a substantially more complex coma than their weaker cousins. The primary cause of this is photolytic heating and collisions that occur over an ever-larger volume of the coma as Q(H2O) increases. Collisions with the photochemical daughters of water in this region modify the radial distributions and outflow velocity of each species, excite and quench metastable emissions, and introduce velocity gradients from photolytic heating. Comet Hale-Bopp was the first comet for which the collisional coma was both spatially resolvable and comparable in extent to the scale lengths of major coma species. In the case of this object, the classical assumptions that make it possible to invert radial emission line profiles, brightnesses, and lineshapes to production rate and velocity either do not hold or require adjustment to work. Here we describe how a large collision zone modifies the coma, how it affects the classical methods for obtaining production rate and velocity, and discuss how wide field imaging may be combined with modified versions of simple models to address the complications and extract some structural information. C1 Univ Wisconsin, Madison, WI 53706 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Harris, WM (reprint author), Univ Wisconsin, 1150 Univ Ave, Madison, WI 53706 USA. NR 32 TC 1 Z9 1 U1 0 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0167-9295 J9 EARTH MOON PLANETS JI Earth Moon Planets PD MAR-JUN PY 2002 VL 90 IS 1-4 BP 45 EP 56 DI 10.1023/A:1021556132765 PG 12 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Geology GA 622RM UT WOS:000179660800006 ER PT J AU Morgenthaler, JP Harris, WM Roesler, FL Scherb, F Anderson, CM Doane, NE Oliversen, RJ AF Morgenthaler, JP Harris, WM Roesler, FL Scherb, F Anderson, CM Doane, NE Oliversen, RJ TI The gas production rate and coma structure of comet C/1995 O1 (Hale-Bopp) SO EARTH MOON AND PLANETS LA English DT Article; Proceedings Paper CT IAU Colloquium No 186 on Cometary Science after Hale-Bopp CY JAN 21-25, 2002 CL CANARY ISL, SPAIN SP Int Astronom Union DE carbon monoxide; C/1995 O1 (Hale-Bopp); comets; dissociative recombination; electron collisional excitation; hydrogen Balmer-alpha coma; hydroxyl radical photodissociation; metastable oxygen coma; water photochemistry; water production rate ID OH; SPECTROSCOPY; ATMOSPHERES; EQUATIONS; MODELS; HALLEY; H2O; O1 AB The University of Wisconsin-Madison and NASA-Goddard conducted a comprehensive multi-wavelength observing campaign of coma emissions from comet Hale-Bopp, including OH 3080 Angstrom, [O I] 6300 Angstrom, H(2)O(+) 6158 Angstrom, H Balmer-alpha 6563 Angstrom, NH(2) 6330 Angstrom, [ C I] 9850 Angstrom CN 3879 Angstrom, C(2) 5141 Angstrom, C(3) 4062 Angstrom, C I 1657 Angstrom, and the UV and optical continua. In this work, we concentrate on the results of the H(2)O daughter studies. Our wide-field OH 3080 Angstrom measured flux agrees with other, similar observations and the expected value calculated from published water production rates using standard H(2)O and OH photochemistry. However, the total [O I] 6300 Angstrom flux determined spectroscopically over a similar field-of-view was a factor of 3-4 higher than expected. Narrow-band [O I] images show this excess came from beyond the H(2)O scale length, suggesting either a previously unknown source of [O I] or an error in the standard OH + nu --> O((1)D) + H branching ratio. The Hale-Bopp OH and [O I] distributions, both of which were imaged to cometocentric distances > 1 x 10(6) km, were more spatially extended than those of comet Halley (after correcting for brightness differences), suggesting a higher bulk outflow velocity. Evidence of the driving mechanism for this outflow is found in the Ha line profile, which was narrower than in comet Halley (though likely because of opacity effects, not as narrow as predicted by Monte-Carlo models). This is consistent with greater collisional coupling between the suprathermal H photodissociation products and Hale-Bopp's dense coma. Presumably because of mass loading of the solar wind by ions and ions by the neutrals, the measured acceleration of H(2)O(+) down the ion tail was much smaller than in comet Halley. Tailward extensions in the azimuthal distributions of OH 3080 Angstrom, [O I], and [C I], as well as a Doppler asymmetry in the [O I] line profile, suggest ion-neutral coupling. While the tailward extension in the OH can be explained by increased neutral acceleration, the [O I] 6300 Angstrom and [C I] 9850 Angstrom emissions show 13% and > 200% excesses in this direction (respectively), suggesting a non-negligible contribution from dissociative recombination of CO(+) and/or electron collisional excitation. Thus, models including the effects of photo- and collisional chemistry are necessary for the full interpretation of these data. C1 Univ Wisconsin, Space Astron Lab, Madison, WI 53706 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Wisconsin, Dept Phys, Madison, WI 53706 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. RP Morgenthaler, JP (reprint author), Univ Wisconsin, Space Astron Lab, 1150 Univ Ave, Madison, WI 53706 USA. EM jpmorgen@alum.mit.edu NR 28 TC 3 Z9 3 U1 0 U2 1 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0167-9295 J9 EARTH MOON PLANETS JI Earth Moon Planets PD MAR-JUN PY 2002 VL 90 IS 1-4 BP 77 EP 87 DI 10.1023/A:1021564301815 PG 11 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Geology GA 622RM UT WOS:000179660800010 ER PT J AU Morgenthaler, JP Harris, WM Scherb, F Doane, NE Oliversen, RJ AF Morgenthaler, JP Harris, WM Scherb, F Doane, NE Oliversen, RJ TI Velocity-resolved observations of H alpha emission from comet C/1995 O1 (Hale-Bopp) SO EARTH MOON AND PLANETS LA English DT Article; Proceedings Paper CT IAU Colloquium No 186 on Cometary Science after Hale-Bopp CY JAN 21-25, 2002 CL CANARY ISL, SPAIN SP Int Astronom Union DE C/1995 O1 (Hale-Bopp); comets; Fabry-Perot spectrometers; hydrogen Balmer-alpha coma; line widths; photolytic heating ID LINE; SPECTROSCOPY; P/HALLEY AB We present hydrogen Balmer-alpha spectra of comet C/1995 O1 (Hale-Bopp) recorded on 5 nights from 1997 February 1 to April 19 by a high-resolution (Deltav = 5 km s(-1)) Fabry-Perot spectrometer for a 4'.1 (similar to2.7 x 10(5) km) FOV centered 5' sunward of the nucleus. The Ha line profile is an important diagnostic of photolytic heating in cometary atmospheres. Extraction of the spectra from the Fabry-Perot ring images was complicated by obscuration of the telescope FOV due to Hale-Bopp's low elevation, but the measured H-alpha line widths of 11-13 km s(-1) (FWHM) are insensitive to the spectral extraction technique. The line widths are consistent with estimates derived from a successful model of Hale-Bopp's hydrogen Lyman-alpha coma assuming the inner coma is opaque to Halpha. We discuss methods for improving the spectral extraction technique and deriving a precise instrument profile which will allow the detailed shape of the line profile to constrain coma models. C1 Univ Wisconsin, Space Astron Lab, Madison, WI 53706 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Wisconsin, Dept Phys, Madison, WI 53706 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Morgenthaler, JP (reprint author), Univ Wisconsin, Space Astron Lab, 1150 Univ Ave, Madison, WI 53706 USA. NR 19 TC 1 Z9 1 U1 0 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0167-9295 J9 EARTH MOON PLANETS JI Earth Moon Planets PD MAR-JUN PY 2002 VL 90 IS 1-4 BP 89 EP 97 DI 10.1023/A:1021516418653 PG 9 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Geology GA 622RM UT WOS:000179660800011 ER PT J AU Jehin, E Boehnhardt, H Sekanina, Z Bonfils, X Schutz, O Beuzit, JL Billeres, M Garradd, GJ Leisy, P Marchis, F Mas, A Origlia, L Scarpa, D Thomas, D Tozzi, GP AF Jehin, E Boehnhardt, H Sekanina, Z Bonfils, X Schutz, O Beuzit, JL Billeres, M Garradd, GJ Leisy, P Marchis, F Mas, A Origlia, L Scarpa, D Thomas, D Tozzi, GP TI Split Comet C/2001 A2 (LINEAR) SO EARTH MOON AND PLANETS LA English DT Article; Proceedings Paper CT IAU Colloquium No 186 on Cometary Science after Hale-Bopp CY JAN 21-25, 2002 CL CANARY ISL, SPAIN SP Int Astronom Union DE C/2001 A2 (LINEAR); comets; fragmentation ID PHOTOMETRY AB Comet C/2001 A2 experienced several splitting events during its 2001 perihelion passage. The first break-up event was observed in March 2001 (IAUC 7616). In this paper we report the first results of our extensive imaging and spectroscopic monitoring campaign with ESO telescopes over several weeks before and after the perihelion passage on May 25 2001. C1 European So Observ, Santiago 19, Chile. CALTECH, Jet Prop Lab, Pasadena, CA USA. Univ Grenoble 1, Observ Grenoble, Astrophys Lab, F-38041 Grenoble, France. Univ Calif Berkeley, Ctr Adapt Opt, Berkeley, CA 94720 USA. Observ Kappa Crucis, Montevideo, Uruguay. Osservatorio Astron Bologna, I-40127 Bologna, Italy. Univ Sternwarte Munchen, D-41679 Munich, Germany. Osserv Astrofis Arcetri, I-50125 Florence, Italy. RP Jehin, E (reprint author), European So Observ, Casilla 19001,Alonso de Cordova 3107, Santiago 19, Chile. RI Marchis, Franck/H-3971-2012; ORIGLIA, LIVIA/O-9883-2015; OI ORIGLIA, LIVIA/0000-0002-6040-5849; Tozzi, Gian Paolo/0000-0003-4775-5788 NR 9 TC 9 Z9 9 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0167-9295 J9 EARTH MOON PLANETS JI Earth Moon Planets PD MAR-JUN PY 2002 VL 90 IS 1-4 BP 147 EP 151 DI 10.1023/A:1021528821379 PG 5 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Geology GA 622RM UT WOS:000179660800017 ER PT J AU Charnley, SB Rodgers, SD Butner, HM Ehrenfreund, P AF Charnley, SB Rodgers, SD Butner, HM Ehrenfreund, P TI Chemical processes in cometary comae SO EARTH MOON AND PLANETS LA English DT Article; Proceedings Paper CT IAU Colloquium No 186 on Cometary Science after Hale-Bopp CY JAN 21-25, 2002 CL CANARY ISL, SPAIN SP Int Astronom Union DE comets; general-comets; individual; (Hale-Bopp) ID O1 HALE-BOPP; C/1995 O1; INTERSTELLAR CLOUDS; MOLECULES; CHEMISTRY; FRACTIONATION; ORIGIN; MODEL; RATIO; HNC AB Recent developments in the chemical modelling of cometary comae are described. We discuss the cyanide chemistry and present new HCN observations of the recent comet C/2002 C1 (Ikeya-Zhang). The connection between interstellar and cometary organic molecules is discussed from the perspective of recent theories of interstellar gas-grain chemistry. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Univ Arizona, Steward Observ, SMTO, Tucson, AZ 85721 USA. Leiden Observ, NL-2300 RA Leiden, Netherlands. RP Charnley, SB (reprint author), NASA, Ames Res Ctr, Div Space Sci, MS 245-3, Moffett Field, CA 94035 USA. RI Charnley, Steven/C-9538-2012; OI Butner, Harold/0000-0003-4899-2064 NR 48 TC 3 Z9 3 U1 0 U2 3 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0167-9295 J9 EARTH MOON PLANETS JI Earth Moon Planets PD MAR-JUN PY 2002 VL 90 IS 1-4 BP 349 EP 360 DI 10.1023/A:1021534417261 PG 12 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Geology GA 622RM UT WOS:000179660800036 ER PT J AU Lederer, SM Campins, H AF Lederer, SM Campins, H TI Evidence for chemical heterogeneity in the nucleus of C/1995 O1 (Hale-Bopp) SO EARTH MOON AND PLANETS LA English DT Article; Proceedings Paper CT IAU Colloquium No 186 on Cometary Science after Hale-Bopp CY JAN 21-25, 2002 CL CANARY ISL, SPAIN SP Int Astronom Union DE C/1995 O1 (Hale-Bopp); comets; gas jets ID COMET; JETS AB We present an analysis of OH, CN, and C-2 jets observed in the coma of Comet Hale-Bopp on UT April 22, 23, and 25, 1997. Monte Carlo models designed to simulate the gas jets were employed to analyze the nuclear active areas responsible for the observed coma gas jets. Our results indicate that four active areas are necessary to reproduce the CN and C-2 jets while five active areas are required to simulate the OH jets. The additional OH active area must produce significant levels of OH, but cannot emit measurable quantities of either carbon radical. This difference suggests that the nucleus of Comet Hale-Bopp is chemically heterogeneous. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. RP Lederer, SM (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code SR, Houston, TX 77058 USA. NR 10 TC 12 Z9 12 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0167-9295 J9 EARTH MOON PLANETS JI Earth Moon Planets PD MAR-JUN PY 2002 VL 90 IS 1-4 BP 381 EP 389 DI 10.1023/A:1021542619078 PG 9 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Geology GA 622RM UT WOS:000179660800040 ER PT J AU Kitchell, JF Essington, TE Boggs, CH Schindler, DE Walters, CJ AF Kitchell, JF Essington, TE Boggs, CH Schindler, DE Walters, CJ TI The role of sharks and longline fisheries in a pelagic ecosystem of the Central Pacific SO ECOSYSTEMS LA English DT Article DE sharks; blue shark; food web; models; ecosystem; pelagic ecosystem; fisheries; predation; predator-prey interactions; conservation; Pacific Ocean ID MARINE ECOSYSTEMS; MANAGEMENT; PREDATION; EMPHASIS; OCEAN; DIET; SEA AB The increased exploitation of pelagic sharks by longline fisheries raised questions about changes in the food webs that include sharks as apex predators. We used a version of Ecopath/Ecosim models to evaluate changes in trophic interactions due to shark exploitation in the Central North Pacific. Fisheries targeted on blue sharks tend to produce compensatory responses that favor other shark species and billfishes, but they have only modest effects on the majority of food web components. Modest levels of intraguild predation (adult sharks that eat juvenile sharks) produce strong, nonlinear responses in shark populations. in general, analysis of the Central North Pacific model reveals that sharks are not keystone predators, but that increases in longline fisheries can have profound effects on the food webs that support sharks. C1 Univ Wisconsin, Ctr Limnol, Madison, WI 53706 USA. Natl Marine Fisheries Serv, SW Fishery Ctr, Honolulu Lab, Honolulu, HI 96822 USA. Univ Washington, Dept Zool, Seattle, WA 98195 USA. Univ British Columbia, Fisheries Ctr, Vancouver, BC V6T 124, Canada. RP Kitchell, JF (reprint author), Univ Wisconsin, Ctr Limnol, 680 N Pk St, Madison, WI 53706 USA. RI Walters, Carl/D-5714-2012 NR 47 TC 89 Z9 93 U1 6 U2 44 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 1432-9840 J9 ECOSYSTEMS JI Ecosystems PD MAR PY 2002 VL 5 IS 2 BP 202 EP 216 DI 10.1007/s10021-001-0065-5 PG 15 WC Ecology SC Environmental Sciences & Ecology GA 549DN UT WOS:000175429400007 ER PT J AU Guerra, M Walker, E Jones, C Paskewitz, S Cortinas, MR Stancil, A Beck, L Bobo, M Kitron, U AF Guerra, M Walker, E Jones, C Paskewitz, S Cortinas, MR Stancil, A Beck, L Bobo, M Kitron, U TI Predicting the risk of Lyme disease: Habitat suitability for Ixodes scapularis in the north central United States SO EMERGING INFECTIOUS DISEASES LA English DT Article ID WHITE-TAILED DEER; GEOGRAPHIC INFORMATION-SYSTEMS; DAMMINI ACARI; NORTHWESTERN ILLINOIS; PEROMYSCUS-LEUCOPUS; BORRELIA-BURGDORFERI; SPATIAL-ANALYSIS; RICINUS ACARI; SMALL MAMMALS; NEW-YORK AB The distribution and abundance of Ixodes scapularis were studied in Wisconsin, northern Illinois, and portions of the Upper Peninsula of Michigan by inspecting small mammals for ticks and by collecting questing ticks in state parks and natural areas. Environmental data were gathered at a local level (i.e., micro and meso levels), and a geographic information system (GIS) was used with several digitized coverages of environmental data to create a habitat profile for each site and a grid map for Wisconsin and Illinois. Results showed that the presence and abundance of I. scapularis varied, even when the host population was adequate. Tick presence was positively associated with deciduous, dry to mesic forests and alfisol-type soils of sandy or loam-sand textures overlying sedimentary rock. Tick absence was associated with grasslands, conifer forests, wet to wet/mesic forests, acidic soils of low fertility and a clay soil texture, and Precambrian bedrock. We performed a discriminant analysis to determine environmental differences between positive and negative tick sites and derived a regression equation to examine the probability of 1, scapularis presence per grid. Both analyses indicated that soil order and land cover were the dominant contributors to tick presence. We then constructed a risk map indicating suitable habitats within areas where I. scapularis is already established. The risk map also shows areas of high probability the tick will become established if introduced. Thus, this risk analysis has both explanatory power and predictive capability. C1 Univ Illinois, Coll Vet Med, Urbana, IL 61801 USA. Michigan State Univ, E Lansing, MI USA. Univ Wisconsin, Madison, WI USA. NASA Ames Res Ctr, Moffett Field, CA USA. RP Kitron, U (reprint author), Univ Illinois, Coll Vet Med, Urbana, IL 61801 USA. FU NIAID NIH HHS [AI-36917] NR 52 TC 140 Z9 144 U1 7 U2 70 PU CENTER DISEASE CONTROL PI ATLANTA PA ATLANTA, GA 30333 USA SN 1080-6040 J9 EMERG INFECT DIS JI Emerg. Infect. Dis PD MAR PY 2002 VL 8 IS 3 BP 289 EP 297 PG 9 WC Immunology; Infectious Diseases SC Immunology; Infectious Diseases GA 531UC UT WOS:000174434800010 PM 11927027 ER PT J AU Xu, GW Ikegami, M Honma, S Ikeda, K Nagaishi, H Dietrich, DL Takeshita, Y AF Xu, GW Ikegami, M Honma, S Ikeda, K Nagaishi, H Dietrich, DL Takeshita, Y TI Burning droplets composed of light cycle oil and diesel light oil SO ENERGY & FUELS LA English DT Article ID FUEL DROPLET; COMBUSTION; IGNITION AB Burning of single droplets composed of a light cycle oil (LCO) and a diesel light oil (LO) was investigated in normal and micro gravity conditions, with the intention of developing technologies burning these oils in gas turbines. While the normal gravity test used a hot-air chamber to simulate the burning condition that occurs in actual burners, the microgravity test employed an igniter, set beneath the droplet, to make the burning free of extra radiation. The result showed that the burning of the LCO droplet had higher soot yield, while that of the LO droplet was more disruptive. In the conditions tested, coke formation was negligible for both the oils. The LCO droplets exhibited lower ignition delay times, but the burning times between ignition and extinction of equi-sized droplets were slightly larger for LO. A burning rate constant, which was an explicit value when microexplosions were present, could be defined according to the d(2)-law. The constant, however, was closely related to the initial droplet diameter (d(0)), causing the relative size d/d(0) to be unified (normalized) into a single curve by a relative burning time t/d(0)(n) (1.0 < n < 2.0). The droplet temperature histories in microgravity demonstrated that the burning of the LCO and LO droplets proceeded by vaporizing fuel constituents according to their volatility, suggesting a distillation-like mechanism dominating the burning. The test in gravity showed also that the soot particles from the LCO droplets were easier to glow (fire) after flame extinction, while the droplets required as well longer times to burn up the soot particles. C1 AIST, Natl Inst Adv Ind Sci & Technol, Toyohira Ku, Sapporo, Hokkaido 0628517, Japan. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Japan Space Utilizat Promot Ctr, Shinjuku Ku, Tokyo 1698624, Japan. RP Xu, GW (reprint author), AIST, Natl Inst Adv Ind Sci & Technol, Toyohira Ku, 2-17 Tsukisamu Higashi, Sapporo, Hokkaido 0628517, Japan. NR 33 TC 6 Z9 6 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0887-0624 J9 ENERG FUEL JI Energy Fuels PD MAR-APR PY 2002 VL 16 IS 2 BP 366 EP 378 DI 10.1021/ef010112r PG 13 WC Energy & Fuels; Engineering, Chemical SC Energy & Fuels; Engineering GA 533GW UT WOS:000174522000014 ER PT J AU Hobbs, A Williamson, A AF Hobbs, A Williamson, A TI Skills, rules and knowledge in aircraft maintenance: errors in context SO ERGONOMICS LA English DT Article DE task analysis; skill-based performance; maintenance errors; safety ID TASK-ANALYSIS; ACCIDENTS; ATTENTION AB Automatic or skill-based behaviour is generally considered to be less prone to error than behaviour directed by conscious control. However, researchers who have applied Rasmussen's skill-rule-knowledge human error framework to accidents and incidents have sometimes found that skill-based errors appear in significant numbers. It is proposed that this is largely a reflection of the opportunities for error which workplaces present and does not indicate that skill-based behaviour is intrinsically unreliable. In the current study, 99 errors reported by 72 aircraft mechanics were examined in the light of a task analysis based on observations of the work of 25 aircraft mechanics. The task analysis identified the opportunities for error presented at various stages of maintenance work packages and by the job as a whole. Once the frequency of each error type was normalized in terms of the opportunities for error, it became apparent that skill-based performance is more reliable than rule-based performance, which is in turn more reliable than knowledge-based performance. The results reinforce the belief that industrial safety interventions designed to reduce errors would best be directed at those aspects of jobs that involve rule- and knowledge-based performance. C1 New S Wales Injury Risk Management Res Ctr, Sydney, NSW, Australia. Bur Air Safety Invest, Canberra, ACT 2608, Australia. RP Hobbs, A (reprint author), San Jose State Univ, NASA, Ames Res Ctr, MS262-4, Moffett Field, CA 94035 USA. NR 42 TC 24 Z9 24 U1 3 U2 10 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 0014-0139 J9 ERGONOMICS JI Ergonomics PD MAR PY 2002 VL 45 IS 4 BP 290 EP 308 DI 10.1080/00140130110116100 PG 19 WC Engineering, Industrial; Ergonomics; Psychology, Applied; Psychology SC Engineering; Psychology GA 545DL UT WOS:000175200900004 PM 12028726 ER PT J AU Al-Theneyan, A Jakatdar, A Mehrotra, P Zubair, M AF Al-Theneyan, A Jakatdar, A Mehrotra, P Zubair, M TI XML-based visual specification of multidisciplinary applications SO FUTURE GENERATION COMPUTER SYSTEMS LA English DT Article; Proceedings Paper CT 1st IEEE/AMC International Symposium on Cluster Computing and the Grid CY MAY 15-18, 2001 CL BRISBANE, AUSTRALIA SP IEEE, Comp Soc, IEEE Comp Soc, Task Force Cluster Computing, Assoc Comp Mach, SIGARCH, IEEE Comp Soc, Tech Comm Parallel Processing, Queensland Univ Technol DE XML-based visual specification; Arcade; Internet ID INFRASTRUCTURE AB Advancements in the Internet and Web technologies have fueled a growing interest in developing a web-based distributed computing environment. We have designed and developed Arcade, a web-based environment for designing, executing, monitoring, and controlling distributed heterogeneous applications, which is easy to use and access, portable, and provides support through all phases of the application development and execution. A major focus of the environment is the specification of heterogeneous, multidisciplinary applications. In this paper we focus on the visual- and script-based specification interface of Arcade. The web/browser-based visual interface is designed to be intuitive and can also be used for visual monitoring during execution. The script specification is based on XML to (a) make it portable across different frameworks, and (b) make the development of our tools easier by using the existing freely available XML parsers and editors. There is a one-to-one correspondence between the visual- and script-based interfaces allowing users to go back and forth between the two. To support this we have developed translators that transform a script-based specification to a visual-based specification, and vice versa. These translators are integrated with our tools and are transparent to users. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Old Dominion Univ, Dept Comp Sci, Norfolk, VA 23529 USA. NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. NASA, Ames Res Ctr, NAS Div, Moffett Field, CA 94035 USA. RP Al-Theneyan, A (reprint author), Old Dominion Univ, Dept Comp Sci, Norfolk, VA 23529 USA. NR 15 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-739X J9 FUTURE GENER COMP SY JI Futur. Gener. Comp. Syst. PD MAR PY 2002 VL 18 IS 4 BP 539 EP 548 AR PII S0167-739X(01)00069-3 DI 10.1016/S0167-739X(01)00069-3 PG 10 WC Computer Science, Theory & Methods SC Computer Science GA 536GD UT WOS:000174691600009 ER PT J AU Das, SK Harvey, DJ Biswas, R AF Das, SK Harvey, DJ Biswas, R TI MinEX: a latency-tolerant dynamic partitioner for grid computing applications SO FUTURE GENERATION COMPUTER SYSTEMS-THE INTERNATIONAL JOURNAL OF ESCIENCE LA English DT Article; Proceedings Paper CT 1st IEEE/AMC International Symposium on Cluster Computing and the Grid CY MAY 15-18, 2001 CL BRISBANE, AUSTRALIA SP IEEE, Comp Soc, IEEE Comp Soc, Task Force Cluster Comp, Assoc Comp Mach, SIGARCH, IEEE Comp Soc, Tech Comm Parallel Proc, Queensland Univ Technol DE information power grid; adaptive computations; partitioning; dynamic load balancing; latency tolerance ID ADAPTIVE UNSTRUCTURED MESHES AB The Information Power Grid (IPG) being developed by NASA is designed to harness the power of geographically distributed computers, databases, and human expertise, in order to solve large-scale realistic computational problems. This type of a metacomputing infrastructure is necessary to present a unified virtual machine to application developers that hides the intricacies of a highly heterogeneous environment and yet maintains adequate security. In this paper, we present a novel latency-tolerant partitioning scheme, called MinEX, that dynamically balances processor workloads while minimizing data movement and runtime communication, for applications that are executed in a parallel distributed fashion on the IPG. The number of IPG nodes, the number of processors per node, and the interconnect speeds are parameterized in a simulation experiment to derive conditions under which the IPG would be suitable for solving such applications. Experimental results demonstrate that MinEX is an effective load balancer for the IPG when the nodes are connected by a high-speed asynchronous interconnection network. (C) 2002 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, NASA Adv Supercomp Div, Moffett Field, CA 94035 USA. Univ Texas, Dept Comp Sci & Engn, Arlington, TX 76019 USA. So Oregon Univ, Dept Comp Sci, Ashland, OR 97520 USA. RP NASA, Ames Res Ctr, NASA Adv Supercomp Div, Mail Stop T27A-1, Moffett Field, CA 94035 USA. EM das@cse.uta.edu; harveyd@sou.edu; rbiswas@nas.nasa.gov NR 27 TC 10 Z9 10 U1 0 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-739X EI 1872-7115 J9 FUTURE GENER COMP SY JI Futur. Gener. Comp. Syst. PD MAR PY 2002 VL 18 IS 4 BP 477 EP 489 AR PII S0167-739X(01)00073-5 DI 10.1016/S0167-739X(01)00073-5 PG 13 WC Computer Science, Theory & Methods SC Computer Science GA 536GD UT WOS:000174691600005 ER PT J AU Halpern, D AF Halpern, D TI Offshore Ekman transport and Ekman pumping off Peru during the 1997-1998 El Nino SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID WIND STRESS; VARIABILITY AB [1] Satellite ocean vector wind measurements are used to describe onshore-offshore Ekman transport and Ekman pumping/ suction (i.e., downward/upward velocity) in the coastal ocean at 15degreesS off Peru, where upwelling is the dominant physical process. Normal and El Nino conditions are defined for May 1992 - April 1997 and May 1997 - May 1998, respectively. During normal conditions, both Ekman suction and offshore Ekman transport produced upwelling. During the El Nino, the May-August speed of Ekman pumping (-9 x 10(-6) m s(-1)) was nearly 4 times larger than the normal speed of Ekman suction and offshore Ekman transport nearly doubled. The strong Ekman pumping may be the source for the deepened coastal thermocline during El Nino, although the evidence is not conclusive because of the absence of in situ observations. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Halpern, D (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 21 Z9 22 U1 1 U2 2 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 MAR 1 PY 2002 VL 29 IS 5 AR 1075 DI 10.1029/2001GL014097 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DC UT WOS:000178886500002 ER PT J AU Joshi, M Young, R AF Joshi, M Young, R TI Is the mean Venusian tropospheric circulation unsteady? SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ATMOSPHERE; EQUATOR; MODEL AB [1] The troposphere of Venus, or that region between the surface and the sulphuric acid cloud layer, is characterised by very low horizontal temperature contrasts of less than 10 K. Such low thermal gradients will have a large impact on the tropospheric mean circulation. Using a simplified atmospheric model, we show that the mean circulation might change in strength, and possibly even reverse in direction, on timescales of decades to centuries. The phenomenon is associated with the high surface pressure, and hence long thermal relaxation time scale of the lower atmosphere. Inertial oscillations appear to play a role in any circulation reversals that occur. We note that wind streak data are consistent with a variable Hadley circulation. Our results imply that the Venusian cloud layer could also exhibit significant variability on the same very long timescales, consistent with some observations. C1 Univ Reading, Dept Meteorol, Reading RG6 6BB, Berks, England. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Joshi, M (reprint author), Univ Reading, Dept Meteorol, Earley Gate,POB 243, Reading RG6 6BB, Berks, England. RI Joshi, Manoj/C-1795-2008 OI Joshi, Manoj/0000-0002-2948-2811 NR 19 TC 4 Z9 4 U1 0 U2 0 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 MAR 1 PY 2002 VL 29 IS 5 AR 1062 DI 10.1029/2001GL013979 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DC UT WOS:000178886500015 ER PT J AU Paranicas, C Mauk, BH Ratliff, JM Cohen, C Johnson, RE AF Paranicas, C Mauk, BH Ratliff, JM Cohen, C Johnson, RE TI The ion environment near Europa and its role in surface energetics SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID BOMBARDMENT; MAGNETOSPHERE; SATELLITES; GANYMEDE AB [1] This paper gives the composition, energy spectra, and time variability of energetic ions measured just upstream of Europa. From 100 keV to 100 MeV, ion intensities vary by less than a factor of similar to5 among Europa passes considered between 1997 and 2000. We use the data to estimate the radiation dose rate into Europa's surface for depths 0.01 mm - 1 m. We find that in a critical fraction of the upper layer on Europa's trailing hemisphere, energetic electrons are the principal agent for radiolysis, and their bremsstrahlung photon products, not included in previous studies, dominate the dose below about 1 m. Because ion bombardment is more uniform across Europa's surface, the radiation dose on the leading hemisphere is dominated by the proton flux. Differences exist between this calculation and published doses based on the E4 wake pass. For instance, proton doses presented here are much greater below 1 mm. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Pasadena, CA 91125 USA. Univ Virginia, Charlottesville, VA 22903 USA. RP Paranicas, C (reprint author), Johns Hopkins Univ, Appl Phys Lab, 11100 Johns Hopkins Rd, Laurel, MD 20723 USA. RI Paranicas, Christopher/B-1470-2016; Mauk, Barry/E-8420-2017 OI Paranicas, Christopher/0000-0002-4391-8255; Mauk, Barry/0000-0001-9789-3797 NR 15 TC 27 Z9 27 U1 0 U2 1 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 MAR 1 PY 2002 VL 29 IS 5 AR 1074 DI 10.1029/2001GL014127 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DC UT WOS:000178886500003 ER PT J AU Ravat, D Whaler, KA Pilkington, M Sabaka, T Purucker, M AF Ravat, D Whaler, KA Pilkington, M Sabaka, T Purucker, M TI Compatibility of high-altitude aeromagnetic and satellite-altitude magnetic anomalies over Canada SO GEOPHYSICS LA English DT Article ID UNITED-STATES; HARMONIC SPLINES; EARTHS SURFACE; MAGSAT; FIELD; MAPS; INVERSION; LIMITATIONS; COMPONENTS AB Results from equivalent-source distributions derived jointly from high-altitude (average 4 km) aeromagnetic and Magsat-derived (average 400 km) magnetic anomalies over Canada indicate that long-wavelength components (500-2500 km) in these fields are extremely compatible with one another (with a correlation coefficient of 0.95). The jointly estimated anomaly field at the earth's surface can be used as a long-wavelength adjustment surface for regional near-surface magnetic anomaly compilations and in assessing the performance of other downward-continuation techniques. Because near-surface anomalies are not available over all regions of the world, we compare the jointly estimated anomaly field to the results of two different downward-continuation techniques: the evaluation of anomalies at the earth's surface from spherical harmonic coefficients derived from satellite-altitude data and the use of downward-continuation methods based on harmonic splines. Numerical and visual comparisons of these downward-continued fields with the jointly estimated anomaly field from the equivalent-source method indicate they are well correlated and could provide a useful method of deriving long-wavelength leveling surfaces for regional and worldwide magnetic anomaly maps. C1 So Illinois Univ, Dept Geol, Carbondale, IL 62901 USA. Univ Edinburgh, Grant Inst Geol, Dept Geol & Geophys, Edinburgh EH9 3JW, Midlothian, Scotland. Geol Survey Canada, Ottawa, ON K1A 0E9, Canada. NASA, Goddard Space Flight Ctr, Raytheon STX Geodynam Branch, Greenbelt, MD 20771 USA. RP Ravat, D (reprint author), So Illinois Univ, Dept Geol, MS 4324, Carbondale, IL 62901 USA. RI Sabaka, Terence/D-5618-2012; OI Ravat, Dhananjay/0000-0003-1962-4422 NR 42 TC 24 Z9 24 U1 0 U2 1 PU SOC EXPLORATION GEOPHYSICISTS PI TULSA PA 8801 S YALE ST, TULSA, OK 74137 USA SN 0016-8033 J9 GEOPHYSICS JI Geophysics PD MAR-APR PY 2002 VL 67 IS 2 BP 546 EP 554 DI 10.1190/1.1468615 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 540GC UT WOS:000174920300021 ER PT J AU Campbell, S Scheiman, D AF Campbell, S Scheiman, D TI Orientation of aromatic ion exchange diamines and the effect on melt viscosity and thermal stability of PMR-15/silicate nanocomposites SO HIGH PERFORMANCE POLYMERS LA English DT Article ID POLYIMIDE CLAY HYBRID; SILICATE NANOCOMPOSITES; POLYMER; ORGANOCLAY AB Nanocomposites of PMR-15 polyimide and a diamine modified silicate were prepared by the addition of the silicate to PMR-15 resin. The orientation of the ion exchange diamine within the silicate gallery was evaluated by x-ray diffraction and found to depend on the clay cation exchange capacity. The melt viscosity of the oligomer and the uncured nanocomposite was measured. The melt viscosity exhibited a dependence on the orientation of the diamine in the silicate interlayer and, in some cases, on the chain length of the diamine. A correlation was observed between the oligomer melt viscosity and the crosslinking enthalpy, where nanocomposites with an increased melt viscosity exhibited a decrease in enthalpy on crosslinking. After crosslinking, a poorer nanocomposite thermal oxidative stability was also observed, compared to the less viscous systems. The melt viscosity was tailored by co-exchange of an aromatic diamine and an aliphatic amine, increasing the thermal oxidative stability of the nanocomposite. PMR-15/silicate nanocomposites were investigated as a matrix for carbon fabric reinforced composites. Dispersion of an organically modified silicate into the PMR-15 matrix greatly enhanced the thermal oxidative stability of the polymer matrix composite. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Campbell, S (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 28 TC 15 Z9 15 U1 0 U2 3 PU SAGE PUBLICATIONS LTD PI LONDON PA 6 BONHILL STREET, LONDON EC2A 4PU, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD MAR PY 2002 VL 14 IS 1 BP 17 EP 30 DI 10.1177/0954008302014001089 PG 14 WC Polymer Science SC Polymer Science GA 593BR UT WOS:000177971800002 ER PT J AU Degani, A Heymann, M AF Degani, A Heymann, M TI Formal verification of human-automation interaction SO HUMAN FACTORS LA English DT Article AB This paper discusses a formal and rigorous approach to the analysis of operator interaction with machines. It addresses the acute problem of detecting design errors in human-machine interaction and focuses on verifying the correctness of the interaction in complex and automated control systems. The paper describes a systematic methodology for evaluating whether the interface provides the necessary information about the machine to enable the operator to perform a specified task successfully and unambiguously. It also addresses the adequacy of information provided to the user via training material (e.g., user manual) about the machine's behavior. The essentials of the methodology, which can be automated and applied to the verification of large systems, are illustrated by several examples and through a case study of pilot interaction with an autopilot aboard a modern commercial aircraft. The expected application of this methodology is an augmentation and enhancement, by formal verification, of human-automation interfaces. C1 NASA, Ames Res Ctr, Mt View, CA USA. Technion Israel Inst Technol, Haifa, Israel. RP Degani, A (reprint author), NASA, Ames Res Ctr, MS 269-4, Moffett Field, CA 94035 USA. NR 19 TC 57 Z9 57 U1 2 U2 5 PU HUMAN FACTORS SOC PI SANTA MONICA PA BOX 1369, SANTA MONICA, CA 90406 USA SN 0018-7208 J9 HUM FACTORS JI Hum. Factors PD SPR PY 2002 VL 44 IS 1 BP 28 EP 43 DI 10.1518/0018720024494838 PG 16 WC Behavioral Sciences; Engineering, Industrial; Ergonomics; Psychology, Applied; Psychology SC Behavioral Sciences; Engineering; Psychology GA 569UE UT WOS:000176620000003 PM 12118871 ER PT J AU Heifetz, J AF Heifetz, J TI Coral in Alaska: distribution, abundance, and species associations SO HYDROBIOLOGIA LA English DT Article; Proceedings Paper CT 1st International Deep-Sea Coral Symposium CY JUL 31-AUG 03, 2000 CL HALIFAX, CANADA DE coral; Alaska; distribution and abundance; fish habitat AB To help identify fishery management actions that minimize the adverse impacts of fishing activities on corals in Alaska, the distribution and abundance of corals were analyzed based on trawl survey data collected during 1975-1998. We also examined the species of commercially managed fish that are associated with coral. Soft corals, primarily Gersemia sp. (=Eunephthya sp.), were the most frequently encountered corals in the Bering Sea. In the Aleutian Islands gorgonian corals, primarily in the genera Callogorgia, Primnoa, Paragorgia, Thouarella, and Arthrogorgia were the most common corals. In the Gulf of Alaska, gorgonian corals, primarily in the genera Callogorgia and Primnoa, and cup corals, primarily 'Scleractinia unidentified', occurred most frequently. The Aleutian Islands area appears to have the highest abundance and diversity of corals. Some fish groups are associated with particular types of coral. Rockfish (Sebastes spp. and Sebastolobus alascanus) and Atka mackerel (Pleurogrammus monopterygius) were the most common fish captured with gorgonian, cup, and hydrocorals, whereas flatfish and gadids were the most common fish captured with soft corals. C1 Natl Marine Fisheries Serv, Auke Bay Lab, Alaska Fisheries Sci Ctr, NOAA, Juneau, AK 99801 USA. RP Heifetz, J (reprint author), Natl Marine Fisheries Serv, Auke Bay Lab, Alaska Fisheries Sci Ctr, NOAA, 11305 Glacier Highway, Juneau, AK 99801 USA. EM jon.heifetz@noaa.gov NR 11 TC 57 Z9 60 U1 2 U2 14 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0018-8158 EI 1573-5117 J9 HYDROBIOLOGIA JI Hydrobiologia PD MAR 1 PY 2002 VL 471 SI SI BP 19 EP 28 DI 10.1023/A:1016528631593 PG 10 WC Marine & Freshwater Biology SC Marine & Freshwater Biology GA 575VT UT WOS:000176969700004 ER PT J AU Krieger, KJ Wing, BL AF Krieger, KJ Wing, BL TI Megafauna associations with deepwater corals (Primnoa spp.) in the Gulf of Alaska SO HYDROBIOLOGIA LA English DT Article; Proceedings Paper CT 1st International Deep-Sea Coral Symposium CY JUL 31-AUG 03, 2000 CL HALIFAX, CANADA DE corals; Alaska; submarine ID ABUNDANCE; ROCKFISH; SHELF AB Few in situ observations have been made of deepwater corals and, therefore, little is known about their biology or ecological significance. Deepwater corals (Primnoa spp.) were observed from a manned submersible at 11 sites in the Gulf of Alaska from 1989 to 1997 at depths of 161-365 m. We identified 10 megafaunal groups that associate with Primnoa to feed on the coral, use the coral branches for suspension feeding, or for protection. Predators on Primnoa polyps included sea stars, nudibranchs, and snails. Sea stars were the main predators, consuming 45% and 34% of the polyps at two sites. Suspension-feeders included crinoids, basket stars, anemones, and sponges. Most suspension-feeders observed at depths >300 m were associated with Primnoa. Protection seekers included rockfish, crab, and shrimp. Six rockfish species were either beneath, among, or above Primnoa. Shrimp were among the polyps, and a pair of mating king crabs were beneath Primnoa. These observations indicate Primnoa are important components of the deepwater ecosystem and removal of these slow-growing corals could cause long-term changes in associated megafauna. C1 Natl Marine Fisheries Serv, Auke Bay Lab, Alaska Fisheries Sci Ctr, NOAA, Juneau, AK 99801 USA. RP Krieger, KJ (reprint author), Natl Marine Fisheries Serv, Auke Bay Lab, Alaska Fisheries Sci Ctr, NOAA, 11305 Glacier Highway, Juneau, AK 99801 USA. NR 20 TC 94 Z9 100 U1 4 U2 14 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0018-8158 J9 HYDROBIOLOGIA JI Hydrobiologia PD MAR 1 PY 2002 VL 471 SI SI BP 83 EP 90 DI 10.1023/A:1016597119297 PG 8 WC Marine & Freshwater Biology SC Marine & Freshwater Biology GA 575VT UT WOS:000176969700010 ER PT J AU Gibbard, SG Roe, H de Pater, I Macintosh, B Gavel, D Max, CE Baines, KH Ghez, A AF Gibbard, SG Roe, H de Pater, I Macintosh, B Gavel, D Max, CE Baines, KH Ghez, A TI High-resolution infrared imaging of Neptune from the Keck Telescope SO ICARUS LA English DT Article DE Neptune; atmosphere; infrared observations ID COORDINATED 1996 HST; CLOUD STRUCTURE; ABSORPTION SPECTRA; ADAPTIVE OPTICS; VOYAGER IMAGES; H-2-HE PAIRS; METHANE; BAND; TEMPERATURES; PHOTOCHEMISTRY AB We present results of infrared observations of Neptune from the 10-m W M. Keck I Telescope, using both high-resolution (0.04 arc-second) broadband speckle imaging and conventional imaging with narrowband filters (0.6 arcsec resolution). The speckle data enable us to track the size and shape of infrared-bright features ("storms") as they move across the disk and to determine rotation periods for latitudes -30 and -45degrees. The narrowband data are input to a model that allows Lis to make estimates of Neptune's stratospheric haze abundance and the size of storm features. We find a haze column density of similar to10(6) cm(-2) for a haze layer located in the stratosphere, and a lower limit of 10(7) cm(-2) and an upper limit of 10(9) cm(-2) for a layer of 0.2 mum particles in the troposphere. We also calculate a lower limit of 7 x 10(6) km(2) for the size of a "storm" feature observed on 13 October 1997. (C) 2002 Elsevier Science (USA). C1 Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. Univ Calif Berkeley, Astron Dept, Berkeley, CA 94720 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Los Angeles, CA 90095 USA. RP Gibbard, SG (reprint author), Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. EM sgibbard@igpp.ucllnl.org OI Max, Claire/0000-0003-0682-5436 NR 47 TC 9 Z9 9 U1 0 U2 2 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 MAR PY 2002 VL 156 IS 1 BP 1 EP 15 DI 10.1006/icar.2001.6766 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 548DX UT WOS:000175374300001 ER PT J AU Sromovsky, LA Fry, PM Baines, KH AF Sromovsky, LA Fry, PM Baines, KH TI The unusual dynamics of northern Dark Spots on Neptune SO ICARUS LA English DT Article DE Neptune; Neptune, dynamics; Neptune, atmosphere ID COORDINATED 1996 HST; CLOUD STRUCTURE; ATMOSPHERIC CIRCULATION; EPIC SIMULATIONS; NAVIGATION; FEATURES AB Hubble Space Telescope (HST) and ground-based observations of Neptune from 1991 to 2000 show that Neptune's northern Great Dark Spots (NGDS) remained remarkably stable in latitude and longitudinal drift rate, in marked contrast to the 1989 southern Great Dark Spot (GDS), which moved continuously equatorward during 1989 and dissipated unseen during 1990. NGDS-32, discovered in October 1994 HST images, (H. B. Hammel et al., 1995, Science 268, 1740-1742), stayed at similar to32degreesN from 1994 through at least 1996, and possibly through 2000. The second northern GDS (NGDS-15), discovered in August 1996 HST images, (L. A. Sromovsky et al. 2001, Icarus 146, 459-488), appears to have existed as early as 8 March 1996 and remained near 15degreesN for the 16 months over which it was observed. NGDS-32 had a very uniform longitudinal drift rate averaging -36.28+/-0.04degrees/day from 10 October 1994 to 2 November 1995, and -35.84+/-0.02degrees/day from I September 1995 through 24 November 1995. A single circulation feature certainly exists during each of the first two periods, though it is not certain that it is the same feature. It is probable, but less certain, that only a single circulation feature was tracked during the 1996-1998 period, during which positions are consistent with a modulated drift rate averaging -35.401+/-0.001degrees/day, but with a peak-to-peak modulation of 1.5degrees/day with an similar to760-day period. If NDS-32 varied its drift rate in accord with the local latitudinal shear in the zonal wind, then all its drift-rate changes might be due to only similar to0.4degrees of latitudinal motion. The movement of NGDS-15 is also not consistent with a uniform longitudinal drift rate, but the nature of its variation cannot be estimated from the limited set of observations. The relatively stable latitudinal positions of both northern dark spots are not consistent with current numerical model calculations treating them as anticyclonic vortices in a region of uniform potential vorticity gradient (R. P. Lebeau and T. E. Dowling 1998, Icarus 132, 239-265). Possible explanations include unresolved latitudinal structure in the zonal wind background or unaccounted-for variations in vertical stability structure. (C) 2002 Elsevier Science (USA). C1 Univ Wisconsin, Space Sci & Engn Ctr, Madison, WI 53706 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sromovsky, LA (reprint author), Univ Wisconsin, Space Sci & Engn Ctr, Madison, WI 53706 USA. EM larry.sromovsky@ssec.wisc.edu NR 23 TC 11 Z9 11 U1 0 U2 4 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 MAR PY 2002 VL 156 IS 1 BP 16 EP 36 DI 10.1006/icar.2001.6761 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 548DX UT WOS:000175374300002 ER PT J AU Harris, AW AF Harris, AW TI On the slow rotation of asteroids SO ICARUS LA English DT Article ID SPIN AB Asteroids with very slow rotation rates, up to 100 times slower than the mean for ordinary asteroids, are clearly a statistically distinct population from the rest. The cause of such slow rotation has remained a mystery since the discovery of the population about 20 years ago. The expected distribution of slow rotations for three-dimensional rotation vectors f if uniform near the origin (e.g., a three-dimensional Maxwellian distribution) would be N (< f) proportional to f(3), where f is the rotation frequency (inverse period of rotation) and N (2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 527WR UT WOS:000174211400001 ER PT J AU Bourras, D Eymard, L Liu, WT Dupuis, H AF Bourras, D Eymard, L Liu, WT Dupuis, H TI An integrated approach to estimate instantaneous near-surface air temperature and sensible heat flux fields during the SEMAPHORE experiment SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID ATMOSPHERIC BOUNDARY-LAYER; SATELLITE DATA; OCEAN; SIMULATION; MESOSCALE; HUMIDITY AB A new technique was developed to retrieve near-surface instantaneous air temperatures and turbulent sensible heat fluxes using satellite data during the Structure des Echanges Mer-Atmosphere, Proprietes des Heterogeneites Oceaniques: Recherche Experimentale (SEMAPHORE) experiment, which was conducted in 1993 under mainly anticyclonic conditions. The method is based on a regional, horizontal atmospheric temperature advection model whose inputs are wind vectors, sea surface temperature fields, air temperatures around the region under study, and several constants derived from in situ measurements. The intrinsic rms error of the method is 0.7degreesC in terms of air temperature and 9 W m(-2) for the fluxes, both at 0.16degrees x 0.16degrees and 1.125degrees x 1.125degrees resolution. The retrieved air temperature and flux horizontal structures are in good agreement with fields from two operational general circulation models. The application to SEMAPHORE data involves the First European Remote Sensing Satellite (ERS-1) wind fields, Advanced Very High Resolution Radiometer (AVHRR) SST fields, and European Centre for Medium-Range Weather Forecasts (ECMWF) air temperature boundary conditions. The rms errors obtained by comparing the estimations with research vessel measurements are 0.3degreesC and 5 W m(-2). C1 CALTECH, Jet Prop Lab, NASA, Pasadena, CA 91109 USA. Ctr Etud Environm Terrestre & Planetaires, Velizy Villacoublay, France. Univ Bordeaux 1, F-33405 Talence, France. RP Bourras, D (reprint author), CALTECH, Jet Prop Lab, NASA, MS300-323,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 16 TC 7 Z9 8 U1 1 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD MAR PY 2002 VL 41 IS 3 BP 241 EP 252 DI 10.1175/1520-0450(2002)041<0241:AIATEI>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 527WR UT WOS:000174211400004 ER PT J AU Rao, PA Velden, CS Braun, SA AF Rao, PA Velden, CS Braun, SA TI The vertical error characteristics of GOES-derived winds: Description and experiments with numerical weather prediction SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID 4-DIMENSIONAL DATA ASSIMILATION; BOUNDARY-LAYER; MESOSCALE MODEL; MOTION WINDS; CLOUD; FORECASTS; CYCLONE; IMPACT; SENSITIVITY; SIMULATIONS AB Errors in the height assignment of some satellite-derived winds exist because the satellites sense radiation emitted from a finite layer of the atmosphere rather than a specific level. Problems in data assimilation may arise because the motion of a measured layer is often represented by a single-level value. In this research, Geostationary Operational Environmental Satellite (GOES)-derived cloud and water-vapor motion winds are compared with collocated rawinsonde observations (raobs). The satellite winds are compared with the entire profile of the collocated raob data to determine the vertical error characteristics of the satellite winds. These results are then tested in numerical weather prediction. Comparisons with the entire profile of the collocated raobs indicate that clear-air water-vapor winds represent deeper layers than do either infrared or water-vapor cloud-tracked winds. In addition, it is found that if the vertical gradient of moisture is smooth and uniform from near the height assignment upward, the clear-air water-vapor wind tends to represent a deeper layer than if the moisture gradient contains a sharp peak. The information from the comparisons is then used in numerical model simulations of two separate events to test the results. In the first case, the use of the satellite data results in improved storm tracks during the initial similar to24-h forecast period. Mean statistics indicate that the use of satellite winds generally improves the simulation with time. The simulation results suggest that it is beneficial to spread the satellite wind information over multiple levels, particularly when the moisture profile is used to define the vertical influence. C1 Univ Wisconsin, Cooperat Inst Meteorol Satellite Studies, Madison, WI USA. NASA, Goddard Space Flight Ctr, Mesoscale Atmospher Proc Branch, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Mesoscale Atmospher Proc Branch, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Greenbelt, MD USA. RP USAF, HQ AFTAC TMAR, 1030 S Highway A1A, Patrick AFB, FL 32925 USA. EM raoanil@hotmail.com NR 33 TC 17 Z9 17 U1 1 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD MAR PY 2002 VL 41 IS 3 BP 253 EP 271 DI 10.1175/1520-0450(2002)041<0253:TVECOG>2.0.CO;2 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 527WR UT WOS:000174211400005 ER PT J AU Chiacchio, M Francis, J Stackhouse, P AF Chiacchio, M Francis, J Stackhouse, P TI Evaluation of methods to estimate the surface downwelling longwave flux during arctic winter SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID RADIATION BUDGET; SATELLITE DATA; SEA-ICE; CLOUD; IMPROVEMENTS; CLIMATOLOGY; RETRIEVALS; MODELS AB Surface longwave radiation fluxes dominate the energy budget of nighttime polar regions, yet little is known about the relative accuracy of existing satellite-based techniques to estimate this parameter. We compare eight methods to estimate the downwelling longwave radiation flux and to validate their performance with measurements from two field programs in the Arctic: the Coordinated Eastern Arctic Experiment (CEAREX) conducted in the Barents Sea during the autumn and winter of 1988, and the Lead Experiment performed in the Beaufort Sea in the spring of 1992. Five of the eight methods were developed for satellite-derived quantities, and three are simple parameterizations based on surface observations. All of the algorithms require information about cloud fraction, which is provided from the NASA-NOAA Television and Infrared Observation Satellite (TIROS) Operational Vertical Sounder (TOVS) polar pathfinder dataset (Path-P); some techniques ingest temperature and moisture profiles (also from Path-P); one-half of the methods assume that clouds are opaque and have a constant geometric thickness of 50 hPa, and three include no thickness information whatsoever. With a somewhat limited validation dataset, the following primary conclusions result: 1) all methods exhibit approximately the same correlations with measurements and rms differences, but the biases range from -34 W m(-2) (16% of the mean) to nearly 0; 2) the error analysis described here indicates that the assumption of a 50-hPa cloud thickness is too thin by a factor of 2 on average in polar nighttime conditions; 3) cloud-overlap techniques, which effectively increase mean cloud thickness, significantly improve the results; 4) simple Arctic-specific parameterizations performed poorly, probably because they were developed with surface-observed cloud fractions whereas the tests discussed here used satellite-derived effective cloud fractions; and 5) the single algorithm that includes an estimate of cloud thickness exhibits the smallest differences from observations. C1 Rutgers State Univ, Inst Marine & Coastal Sci, New Brunswick, NJ 08901 USA. Analyt Serv & Mat Inc, Hampton, VA 23666 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Francis, J (reprint author), Rutgers State Univ, Inst Marine & Coastal Sci, 71 Dudley Rd, New Brunswick, NJ 08901 USA. NR 33 TC 6 Z9 6 U1 1 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD MAR PY 2002 VL 41 IS 3 BP 306 EP 318 DI 10.1175/1520-0450(2002)041<0306:EOMTET>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 527WR UT WOS:000174211400009 ER PT J AU Pandey, JC Singh, KP Sagar, R Drake, SA AF Pandey, JC Singh, KP Sagar, R Drake, SA TI Photometric variability of four coronally active stars SO JOURNAL OF ASTROPHYSICS AND ASTRONOMY LA English DT Article; Proceedings Paper CT International Conference on Multi-Colour Universe CY SEP 11-14, 2001 CL TATA INST FUNDAMENTAL RES, MUMBAI, INDIA HO TATA INST FUNDAMENTAL RES DE stars; variable, optical photometry, X-rays; source AB We present photometric observations of four stars that are optical counterparts of soft X-ray/EUV sources, namely IES 0829+15.9, 1ES0920-13.6, 2RE J110159+223509 and 1ES 1737+61.2. We have discovered periodic variability in two of the stars, viz., MCC 527 (1ES 0829+15.9; Period 0(d) .828 +/- 0.0047) and HD 81032 (1ES 0920-13.6; Period = similar to 57.02 +/- 0.560 days). HD 95559 (2RE J110159+223509) is found to show a period of 3(d). HD 160934 (1ES1737+61.2) also shows photometric variability but needs to be monitored further for finding its period. These stars most likely belong to the class of chromospherically active stars. C1 State Observ, Naini Tal 263129, India. Tata Inst Fundamental Res, Mumbai, India. Indian Inst Astrophys, Bangalore 560034, Karnataka, India. NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. RP Pandey, JC (reprint author), State Observ, Naini Tal 263129, India. NR 10 TC 6 Z9 6 U1 0 U2 0 PU INDIAN ACADEMY SCIENCES PI BANGALORE PA P B 8005 C V RAMAN AVENUE, BANGALORE 560 080, INDIA SN 0250-6335 J9 J ASTROPHYS ASTRON JI J. Astrophys. Astron. PD MAR-JUN PY 2002 VL 23 IS 1-2 BP 9 EP 14 DI 10.1007/BF02702457 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 603JC UT WOS:000178555000003 ER PT J AU Hwang, U Petre, R Szymkowiak, AE Holt, SS AF Hwang, U Petre, R Szymkowiak, AE Holt, SS TI Chandra observations of Tycho's supernova remnant SO JOURNAL OF ASTROPHYSICS AND ASTRONOMY LA English DT Article; Proceedings Paper CT International Conference on Multi-Colour Universe CY SEP 11-14, 2001 CL TATA INST FUNDAMENTAL RES, MUMBAI, INDIA HO TATA INST FUNDAMENTAL RES DE X-rays; supernova remnants; interstellar medium; shocks; Tycho's SNR; SN 1572 AB We present a new Chandra observation of Tycho's supernova remnant with the Advanced CCD Imaging Spectrometer. Multicolor Xray imaging reveals new details of the outer shock and ejecta. At energies between 4 and 6 keV, the outline of the outer shock is clearly revealed in X-rays for the first time. The distribution of the emission from lines of Si and Fe are confirmed to have a different morphology from each other, and the Si ejecta are shown to extend to the blast shock at several locations. Characteristic spectra of the outer shock and ejecta are also presented. C1 Univ Maryland, NASA GSFC, College Pk, MD 20742 USA. Yale Univ, New Haven, CT 06520 USA. RP Hwang, U (reprint author), Univ Maryland, NASA GSFC, College Pk, MD 20742 USA. NR 8 TC 8 Z9 8 U1 0 U2 0 PU INDIAN ACADEMY SCIENCES PI BANGALORE PA P B 8005 C V RAMAN AVENUE, BANGALORE 560 080, INDIA SN 0250-6335 J9 J ASTROPHYS ASTRON JI J. Astrophys. Astron. PD MAR-JUN PY 2002 VL 23 IS 1-2 BP 81 EP 87 DI 10.1007/BF02702469 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 603JC UT WOS:000178555000015 ER PT J AU Hajj, GA Kursinski, ER Romans, LJ Bertiger, WI Leroy, SS AF Hajj, GA Kursinski, ER Romans, LJ Bertiger, WI Leroy, SS TI A technical description of atmospheric sounding by GPS occultation SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article DE GPS radio occultation; remote sensing; refractivity temperature; water vapor; pressure; electron density ID GLOBAL-POSITIONING-SYSTEM; GPS/MET RADIO OCCULTATION; LOW-EARTH-ORBIT; WATER-VAPOR; ABELIAN INVERSION; SURFACE PRESSURE; PROFILES; SIMULATION; SIGNALS; TEMPERATURE AB In recent years, the global positioning system (GPS) has been exploited via radio occultation techniques to obtain profiles of refractivity, temperature, pressure and water vapor in the neutral atmosphere and electron density in the ionosphere. The GPS MET experiment, which placed a GPS receiver in a low-Earth orbit, provided a wealth of data which was used to test this concept and the accuracy of the retrievals. Several investigations have already demonstrated that the retrieval accuracies obtained with GPS MET is already comparable, if not better. than the more traditional atmospheric sensing techniques (e.g.. radiosondes). Even though the concept of atmospheric profiling via radio occultation is quite a simple one. care Must be taken to separate the numerous factors that can affect the occulted signal. These include the motion of the satellites, clock drifts. relativistic effects, the separation of the ionosphere and the neutral atmosphere, and the contribution of the tipper atmosphere where sensitivity of the GPS signal is weak. In addition, care must be taken to use proper boundary conditions. use proper smoothing intervals and interpolation schemes to avoid retrieving artificial atmospheric structures, and most importantly detect and correct phase measurement errors introduced by sharp refractivity gradients in the atmosphere. This work describes in some detail the several steps involved in processing Such data. In particular. it describes a system that was developed at the Jet Propulsion Laboratory and used to process the GPS MET data. Several examples of retrieved refractivity, temperature and water vapor profiles are shown and compared to analyses from the European Center for Medium-range Weather Forecast (ECMWF). Statistical comparisons of GPS MET and ECMWF temperatures for data collected during June 21-July 4. 1995. indicate that differences are of order 1-2 K at northern latitudes where the ECMWF analyses are most accurate. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hajj, GA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 238-600, Pasadena, CA 91109 USA. NR 79 TC 214 Z9 235 U1 3 U2 12 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD MAR PY 2002 VL 64 IS 4 BP 451 EP 469 AR PII S1364-6826(01)00114-6 DI 10.1016/S1364-6826(01)00114-6 PG 19 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 548XE UT WOS:000175414500007 ER PT J AU Bauschlicher, CW Gutsev, GL AF Bauschlicher, CW Gutsev, GL TI A new interpretation of the CrO- photoelectron detachment spectra SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID BASIS-SETS; ATOMS; SPECTROSCOPY AB Complete active space self-consistent field/multireference configuration interaction calculations are performed on CrO- and CrO. The ground state of CrO- is identified as (4)Pi, not (6)Sigma(+), as recently suggested. We assign the experimental detachment features to the seven one-electron processes arising from the two ion states. (C) 2002 American Institute of Physics. C1 NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. Univ Virginia, Dept Chem, Charlottesville, VA 22901 USA. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, Space Technol Div, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 9 TC 10 Z9 10 U1 1 U2 5 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 MAR 1 PY 2002 VL 116 IS 9 BP 3659 EP 3661 DI 10.1063/1.1448829 PG 3 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 522GT UT WOS:000173888400015 ER PT J AU Mukhopadhyay, I Perry, DS Duan, YB Pearson, JC Albert, S Butler, RAH Herbst, E DeLucia, FC AF Mukhopadhyay, I Perry, DS Duan, YB Pearson, JC Albert, S Butler, RAH Herbst, E DeLucia, FC TI Observation and analysis of high-J o(1)-e(1) inter-state transitions in CH2DOH SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID EXCITED TORSIONAL STATES; ASYMMETRIC ASYMMETRIC MOLECULES; INFRARED LASER LINES; ROTATIONAL SPECTRA; AXIS APPROACH; CHD2OH; IDENTIFICATION AB We report the observation and assignments of several series of transitions in CH2DOH, including a new and intense series of Q-branch c-type transitions between the e(1) and o(1) torsional substates through high values of the rotational quantum number J. Other transitions assigned are c-type R-branch and P-branch transitions between these two substates and a-type lines within the e(1) and o(1) substates. The assignments were facilitated by initial analysis of the strong Q-branch series, as recorded by the fast scan submillimeter spectroscopy technique (FASSST). The assigned lines of CH2DOH include the first inter-state transitions in the sub-millimeter-wave region and the first to possess high J-values. The completeness of the data generated by FASSST and the success of a simple power series analysis suggest that many parts of the spectrum of CH2DOH may be far more tractable than previously believed. The data should be useful in the development of a full Hamiltonian and in the assignment of astronomical emission features. (C) 2002 American Institute of Physics. C1 Univ Akron, Dept Chem, Ctr Laser Spect, Akron, OH 44325 USA. Ocean Univ Qingdao, Inst Computat Sci & Engn, Qingdao 266003, Peoples R China. Univ British Columbia, Dept Phys & Astron, Vancouver, BC V6T 1Z1, Canada. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Ohio State Univ, Dept Phys, Columbus, OH 43210 USA. RP Mukhopadhyay, I (reprint author), Univ Akron, Dept Chem, Ctr Laser Spect, Akron, OH 44325 USA. NR 25 TC 10 Z9 10 U1 1 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 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD MAR 1 PY 2002 VL 116 IS 9 BP 3710 EP 3717 DI 10.1063/1.1447218 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 522GT UT WOS:000173888400022 ER PT J AU Braverman, A AF Braverman, A TI Compressing massive geophysical datasets using vector quantization SO JOURNAL OF COMPUTATIONAL AND GRAPHICAL STATISTICS LA English DT Article DE clustering; ECVQ algorithm; K-means algorithm; Monte Carlo methods; self-consistency AB This article presents a procedure for compressing massive geophysical datasets. A dataset is stratified geographically, and a penalized clustering algorithm applied to each stratum independently. The algorithm, called Monte Carlo extended ECVQ, is based on the entropy-constrained vector quantizer algorithm (ECVQ). ECVQ trades off error induced by compression against data reduction to produce a set of representative points, each of which stands for some number of input observations. Since the data are massive, a preliminary set of representatives is determined from a stratum sample, then the full stratum is clustered by assigning each observation to the nearest representative. After replacing the initial representatives by means of these clusters, the new representatives and their associated counts are a compressed version, or summary, of the original stratum data. With the initial set of representatives determined from a sample, the final summary is subject to sampling variation. A statistical model for the relationship between compressed and uncompressed data provides a framework for assessing this variability. Test data from the International Satellite Cloud Climatology Project are used to demonstrate the procedure. C1 CALTECH, Jet Prop Lab, Multi Angle Imaging SpectroRadiometer Instrument, Pasadena, CA 91109 USA. RP Braverman, A (reprint author), CALTECH, Jet Prop Lab, Multi Angle Imaging SpectroRadiometer Instrument, Mail Stop 169-237,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 11 Z9 11 U1 0 U2 0 PU AMER STATISTICAL ASSOC PI ALEXANDRIA PA 1429 DUKE ST, ALEXANDRIA, VA 22314 USA SN 1061-8600 J9 J COMPUT GRAPH STAT JI J. Comput. Graph. Stat. PD MAR PY 2002 VL 11 IS 1 BP 44 EP 62 DI 10.1198/106186002317375613 PG 19 WC Statistics & Probability SC Mathematics GA 530YK UT WOS:000174386900003 ER PT J AU Okong'o, N Bellan, J AF Okong'o, N Bellan, J TI Consistent boundary conditions for multicomponent real gas mixtures based on characteristic waves SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE partial differential equations; fluid mechanics; classical thermodynamics; heat transfer ID HYPERBOLIC SYSTEMS; SIMULATIONS; FLOW AB Previously developed characteristic-wave-based boundary conditions for multi-component perfect gas mixtures are here extended to real gas mixtures. The characteristic boundary conditions are derived from the one-dimensional wave decomposition of the Euler equations. and the Wave amplitude variations are determined from the prescribed boundary conditions oil the flow variables. The viscous conditions are applied separately. For multidimensional simulations. the boundary conditions for each coordinate direction are applied additively. These boundary conditions are tested oil a representative two-dimensional problem-the propagation of an incompressible vortex vortex by a supersonic flow with outflow conditions specified as nonreflecting-solved using a high-order finite-difference scheme. Simulations conducted for a heptane-nitrogen mixture flow with strong real gas effects display excellent, nonreflective wave behavior as the vortex leaves the computational domain, verifying the suitability of this method for the multidimensional multicomponent real gas HOWL, computed. (C) 2002 Elsevier Science (USA). C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Okong'o, N (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS125-109, Pasadena, CA 91109 USA. NR 17 TC 53 Z9 54 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 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD MAR 1 PY 2002 VL 176 IS 2 BP 330 EP 344 DI 10.1006/jcph.2002.6990 PG 15 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 529NA UT WOS:000174304500004 ER PT J AU Lee, AY AF Lee, AY TI Coordinated control of steering and anti-roll bars to alter vehicle rollover tendencies SO JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME LA English DT Article AB A Variable Dynamic Testbed Vehicle is presently being built for the National Highway Traffic Safety Administration. It will have four-wheel steering, front and rear active antiroll bar systems, four adjustable dampers, and other active controls. Using these active devices, we can alter the vehicle's understeer coefficient, front/rear load transfer distribution in high-g lateral maneuvers, and roll mode frequency and damping. This study investigates how, these active systems could be controlled to alter the vehicle rollover tendencies. In particular, we study how an increased front antiroll bar stiffness, in conjunction with an increased front damper rate and out-of-phase rear steering could improve vehicle rollover resistance and enhance vehicle safety. Similar but "reverse" algorithms could be used to artificially degrade the rollover resistance of a vehicle. Rollover-related accidents could then be studied using such a vehicle. Results obtained could also provide guidelines for the safe operation of the variable dynamic vehicle in limit lateral maneuvers. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lee, AY (reprint author), CALTECH, Jet Prop Lab, MS 230-104,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 9 TC 19 Z9 22 U1 0 U2 13 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0022-0434 J9 J DYN SYST-T ASME JI J. Dyn. Syst. Meas. Control-Trans. ASME PD MAR PY 2002 VL 124 IS 1 BP 127 EP 132 DI 10.1115/1.1434982 PG 6 WC Automation & Control Systems; Instruments & Instrumentation SC Automation & Control Systems; Instruments & Instrumentation GA 547MH UT WOS:000175335800016 ER PT J AU Bell, AM AF Bell, AM TI Locally interdependent preferences in a general equilibrium environment SO JOURNAL OF ECONOMIC BEHAVIOR & ORGANIZATION LA English DT Article DE interdependent preferences; bandwagon effect; herding; network externalities ID LEGAL CULTURE; BANKRUPTCY AB This paper explores the consequences of interdependent preferences for consumer goods, that is, preferences that evolve in response to the consumption decisions of neighboring agents. The key feature is that the interdependence of preferences coexists and interacts with the price mechanism in a general equilibrium environment. The interaction between the negative feedback operating through the price system and the positive feedback expressed in the bandwagon effect creates distinct geographic patterns of consumption on the micro-level and a characteristic evolution of average preferences and production on the macro-level. In equilibrium, agents' preferences and consumption are completely polarized into stable regions in which every agent consumes the same good exclusively. (C) 2002 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94305 USA. RP Bell, AM (reprint author), NASA, Ames Res Ctr, Mail Stop 239-8, Moffett Field, CA 94305 USA. NR 30 TC 8 Z9 11 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-2681 J9 J ECON BEHAV ORGAN JI J. Econ. Behav. Organ. PD MAR PY 2002 VL 47 IS 3 BP 309 EP 333 AR PII S0167-2681(01)00177-9 DI 10.1016/S0167-2681(01)00177-9 PG 25 WC Economics SC Business & Economics GA 531AZ UT WOS:000174393700005 ER PT J AU Putko, MM Taylor, AC Newman, PA Green, LL AF Putko, MM Taylor, AC Newman, PA Green, LL TI Approach for input uncertainty propagation and robust design in CFD using sensitivity derivatives SO JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID AUTOMATIC DIFFERENTIATION; OPTIMIZATION AB An implementation of the approximate statistical moment method for uncertainty propagation and robust optimization for quasi 1-D Eider CFD code is presented. Given uncertainties in statistically independent, random, normally distributed input variables, first- and second-order statistical Moment procedures are performed to approximate the uncertainty in the CFD output. Efficient calculation of both first- and second-order sensitivity derivatives is required. In order to assess the validity of the approximations, these moments are compared with statistical moments generated through Monte Carlo simulations. The uncertainties in the CFD input variables are also incorporated into a robust optimization procedure. For this optimization, statistical moments involving first-order sensitivity derivatives appear in the objective function and system constraints. Second-order sensitivity derivatives are used in a gradient-based search to successfully execute a robust optimization. The approximate methods used throughout the analyses are found to be valid when considering robustness about input parameter mean values. C1 Old Dominion Univ, Dept Engn Mech, Norfolk, VA 23529 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Putko, MM (reprint author), Old Dominion Univ, Dept Engn Mech, Norfolk, VA 23529 USA. NR 30 TC 35 Z9 36 U1 0 U2 6 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0098-2202 J9 J FLUID ENG-T ASME JI J. Fluids Eng.-Trans. ASME PD MAR PY 2002 VL 124 IS 1 BP 60 EP 69 DI 10.1115/1.1446068 PG 10 WC Engineering, Mechanical SC Engineering GA 547KJ UT WOS:000175331300009 ER PT J AU Rosenfield, JE Douglass, AR Considine, DB AF Rosenfield, JE Douglass, AR Considine, DB TI The impact of increasing carbon dioxide on ozone recovery SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article DE stratospheric ozone; greenhouse gases; carbon dioxide cooling; ozone depletion ID DOUBLED CO2 CLIMATE; MIDDLE ATMOSPHERE; POLAR VORTEX; MODEL; WINTER; DENITRIFICATION; PERTURBATIONS; TEMPERATURE; LAYER; GASES AB [1] We have used the Goddard Space Flight Center coupled two-dimensional model to study the impact of increasing carbon dioxide from 1980 to 2050 on the recovery of ozone to its pre-1980 amounts. We find that the changes in temperature and circulation arising from increasing CO2 affect ozone recovery in a manner which varies greatly with latitude, altitude, and time of year. Middle and upper stratospheric ozone recovers faster at all latitudes due to a slowing of the ozone catalytic loss cycles. In the lower stratosphere the recovery of tropical ozone is delayed due to a decrease in production and a speedup in the overturning circulation. The recovery of high northern latitude lower stratospheric ozone is delayed in spring and summer due to an increase in springtime heterogeneous chemical loss, and is speeded up in fall and winter due to increased downwelling. The net effect on the higher northern latitude column ozone is to slow down the recovery from late March to late July, while making it faster at other times. In the high southern latitudes the impact of CO2 cooling is negligible. Annual mean column ozone is predicted to recover faster at all latitudes, and globally averaged ozone is predicted to recover approximately 10 years faster as a result of increasing CO2. C1 Univ Maryland Baltimore Cty, Baltimore, MD 21228 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. RP Rosenfield, JE (reprint author), NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA. EM rose@euterpe.gsfc.nasa.gov RI Douglass, Anne/D-4655-2012 NR 25 TC 42 Z9 42 U1 3 U2 8 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 MAR PY 2002 VL 107 IS D5-6 AR 4049 DI 10.1029/2001JD000824 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 609FJ UT WOS:000178892700002 ER PT J AU Lurie, BJ Ghavimi, A Hadaegh, FY Mettler, E AF Lurie, BJ Ghavimi, A Hadaegh, FY Mettler, E TI System architecture trades using bode-step control design SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB The initial stage of a complex system design involves understanding and evaluation of various plant architecture. The conventional approach is to select the configuration of choice via an exhaustive performance evaluation process. The procedure involves designing primitive control laws for each configuration option until the best choice is achieved. This approach is quite time consuming and does not necessarily lead to an optimal choice. An alternative approach is to consider the asymptotic Bode-step technique to arrive at a desired configuration choice. The method is simple and provides a powerful tool in performing system tradeoffs. The method relies on little information regarding plant parameters and does not require any detailed controller design for each system configuration option. The method can easily lend itself to an optimized control strategy that is applicable during both the initial and the final stages of a concept design. The procedure is demonstrated by applying the proposed method to the motion control design of the retroreflector carriage of a spacecraft instrument. C1 CALTECH, Jet Prop Lab, Guidance & Control Anal Grp, Pasadena, CA 91109 USA. RP Lurie, BJ (reprint author), CALTECH, Jet Prop Lab, Guidance & Control Anal Grp, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 4 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 2002 VL 25 IS 2 BP 309 EP 315 DI 10.2514/2.4883 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 530ZB UT WOS:000174388700015 ER PT J AU Johnson, JD Lu, J Dhawan, AP Lin, R AF Johnson, JD Lu, J Dhawan, AP Lin, R TI Real-time identification of flutter boundaries using the discrete wavelet transform SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID DECOMPOSITION AB Real-time analysis of an airframe's flutter boundaries during flight testing can help ensure safety and reduce costs. One method of identification is to perform correlation filtering using a set of singlet functions. The method is able to identify accurately the frequency and damping coefficient of the system to excitation, but the computational time required can be too significant to implement in real-time. An alternative method is presented for correlation filtering that employs a multiple-level discrete wavelet transform. The wavelet transform decomposes the response signal into a set of subsignals that correspond to different frequency bands. The same operation is applied to each entry in a dictionary of singlet functions. The transform results in a considerable reduction in the data and, thus, to a reduction in the computational time needed to calculate the correlation. We demonstrate that our approach is able to identify accurately frequency and damping characteristics of the impulse response of both a synthetically generated test signal and actual flight-test data. As a result, real-time identification of flutter boundaries during flight testing may be possible with relatively low-cost computational resources. C1 Univ Toledo, Toledo, OH 43606 USA. NASA, Dryden Flight Res Ctr, Edwards AFB, CA 92523 USA. RP Johnson, JD (reprint author), Univ Toledo, Mail Code 303,2801 W Bancroft St, Toledo, OH 43606 USA. NR 20 TC 9 Z9 11 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 2002 VL 25 IS 2 BP 334 EP 339 DI 10.2514/2.4886 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 530ZB UT WOS:000174388700018 ER PT J AU Ely, TA AF Ely, TA TI Eccentricity impact on east-west stationkeeping for global positioning system class orbits SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID ARTIFICIAL-SATELLITE ORBITS; RESONANT TESSERAL HARMONICS AB A strong relationship exists between eccentricity and the potential for an orbit that has a mean motion commensurate with the Earth's rotation rate to be chaotic. These complex motions can significantly impact the east-west stationkeeping (SK) process for maintaining the repeat groundtrack property of a commensurate orbit. Orbits with characteristics that are similar to the global positioning system (GPS) except that their eccentricities are modestly larger are investigated. It will be shown that at eccentricities greater than similar to0.01 the chaotic regions become significant, and the need arises for a robust stable SK approach. Furthermore, an analytical model for eccentricity is developed, and the factors that contribute to its growth, thus increasing the probability of encountering chaotic motion during a typical satellite lifetime, are shown. These results are applied to selected GPS orbits. It is determined that, if the initial eccentricity is sufficiently large, then the traditional SK methods can destabilize and a more robust technique is required. C1 CALTECH, Jet Prop Lab, Mars Network Project, Pasadena, CA 91109 USA. RP Ely, TA (reprint author), CALTECH, Jet Prop Lab, Mars Network Project, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 8 TC 11 Z9 11 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 2002 VL 25 IS 2 BP 352 EP 357 DI 10.2514/2.4889 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 530ZB UT WOS:000174388700020 ER PT J AU Crain, TP Bishop, RH Ely, TA AF Crain, TP Bishop, RH Ely, TA TI Event detection and characterization during autonomous interplanetary navigation SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article; Proceedings Paper CT AIAA/AAS Astrodynamics Specialist Conference CY AUG 14-17, 2000 CL DENVER, COLORADO SP Amer Inst Aeronaut & Astronaut, AAS AB A prototype autonomous/adaptive interplanetary navigation system employing neural networks and genetic algorithms is introduced. This system consists of a near real-time autonomous monitoring component and an offline adaptive modeling component. Unexpected dynamic or measurement events trigger 1) alerts to navigators and 2) recommendations for modifying the appropriate model parameters to improve filtering. The autonomous component analyzes tracking measurement residuals to first detect and then characterize the unexpected event. Once an environment change has been detected and characterized, the adaptive modeling component then modifies the necessary model parameters to bring the tracking filter back into optimal operation. The autonomous monitor employs a hierarchical mixture-of-experts model where the experts are extended Kalman filters organized into banks regulated by two levels of single-layer neural networks. The autonomous monitor is the focus of this presentation and demonstrates the ability to detect successfully. the occurrence and to differentiate between the characteristics of unexpected discrete velocity changes and continuous dynamic changes. These environment changes are represented by an unmodeled impulsive maneuver and by solar radiation pressure surface mismodeling, respectively, The robust decision-making capability of this approach is further demonstrated by successfully characterizing three successive environment changes. All experiments were performed on recorded Mars Pathfinder two-way Doppler data from the period of 4 February 1997 to 17 April 1997. C1 NASA, Lyndon B Johnson Space Ctr, Aerosci & Flight Mech Div, Houston, TX 77058 USA. Univ Texas, Ctr Space Res, Austin, TX 78759 USA. CALTECH, Jet Prop Lab, Navigat & Mission Design Sect, Pasadena, CA 91109 USA. RP Crain, TP (reprint author), NASA, Lyndon B Johnson Space Ctr, Aerosci & Flight Mech Div, Houston, TX 77058 USA. NR 14 TC 0 Z9 0 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 2002 VL 25 IS 2 BP 394 EP 403 DI 10.2514/2.4894 PG 10 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 530ZB UT WOS:000174388700025 ER PT J AU Markley, FL AF Markley, FL TI Fast quaternion attitude estimation from two vector measurements SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID ALGORITHM C1 NASA, Goddard Space Flight Ctr, Guidance Navigat & Control Syst Engn Branch, Greenbelt, MD 20771 USA. RP Markley, FL (reprint author), NASA, Goddard Space Flight Ctr, Guidance Navigat & Control Syst Engn Branch, Code 571, Greenbelt, MD 20771 USA. NR 16 TC 38 Z9 40 U1 4 U2 7 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 2002 VL 25 IS 2 BP 411 EP 414 DI 10.2514/2.4897 PG 4 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 530ZB UT WOS:000174388700028 ER PT J AU Rosipal, R Trejo, LJ AF Rosipal, R Trejo, LJ TI Kernel partial least squares regression in Reproducing Kernel Hilbert Space SO JOURNAL OF MACHINE LEARNING RESEARCH LA English DT Article; Proceedings Paper CT Workshop on Kernel Methods CY DEC 01, 2000 CL BRECKENRIDGE, CO ID EVENT-RELATED POTENTIALS; FEATURE-EXTRACTION; PCA ALGORITHMS; WIDE DATA; PERFORMANCE; CONNECTION; COMPONENTS; VIEW AB A family of regularized least squares regression models in a Reproducing Kernel Hilbert Space is extended by the kernel partial least squares (PLS) regression model. Similar to principal components regression (PCR), PLS is a method based on the projection of input (explanatory) variables to the latent variables (components). However, in contrast to PCR, PLS creates the components by modeling the relationship between input and output variables while maintaining most of the information in the input variables. PLS is useful in situations where the number of explanatory variables exceeds the number of observations and/or a high level of multicollinearity among those variables is assumed. Motivated by this fact we will provide a kernel PLS algorithm for construction of nonlinear regression models in possibly high-dimensional feature spaces. We give the theoretical description of the kernel PLS algorithm and we experimentally compare the algorithm with the existing kernel PCR and kernel ridge regression techniques. We will demonstrate that on the data sets employed kernel PLS achieves the same results as kernel PCR but uses significantly fewer, qualitatively different components. C1 Univ Paisley, Appl Computat Intelligence Res Unit, Paisley PA1 2BE, Renfrew, Scotland. SAS, Inst Measurement Sci, Lab Neural Networks, Bratislava 84219, Slovakia. RP Rosipal, R (reprint author), NASA, Ames Res Ctr, Computat Sci Div, Mail Stop 269-3, Moffett Field, CA 94035 USA. EM RROSIPAL@MAIL.ARC.NASA.GOV; LTREJO@MAIL.ARC.NASA.GOV RI Rosipal, Roman/B-8060-2008 NR 49 TC 107 Z9 117 U1 3 U2 40 PU MICROTOME PUBL PI BROOKLINE PA 31 GIBBS ST, BROOKLINE, MA 02446 USA SN 1532-4435 J9 J MACH LEARN RES JI J. Mach. Learn. Res. PD SPR PY 2002 VL 2 IS 2 BP 97 EP 123 DI 10.1162/15324430260185556 PG 27 WC Automation & Control Systems; Computer Science, Artificial Intelligence SC Automation & Control Systems; Computer Science GA 559YZ UT WOS:000176055300002 ER PT J AU Brown, LR Toth, RA Dulick, M AF Brown, LR Toth, RA Dulick, M TI Empirical line parameters of (H2O)-O-16 near 0.94 mu m: Positions, intensities and air-broadening coefficients SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID WATER-VAPOR LINES; 720-NM WAVELENGTH REGION; POTENTIAL-ENERGY SURFACE; N-2-BROADENED HALFWIDTHS; TEMPERATURE-DEPENDENCE; SPECTRAL REGION; CM(-1); CM-1; ABSORPTION; DATABASE AB To support the interpretation of remote sensing instruments that use water features near 0.94 mum, the water vapor line parameters have been measured using 16 laboratory spectra of pure water and 9 spectra of water + air mixtures recorded at resolution 0.012 and 0.02 cm(-1) with the McMath Fourier transform spectrometer at the National Solar Observatory located at Kitt Peak. Over 3300 line positions and intensities between 9650 and 11400 cm(-1) and 507 air-broadened widths and 462 pressure-induced shifts in positions between 10 150 and 11 190 cm(-1) have been obtained at room temperature for the main isotopomer, (H2O)-O-16. The numbers of width measurements involving the parallel bands are 108 for (121), 192 for (201), and 86 for the (003) upper states for the perpendicular bands, the numbers of widths are 4 for (022), 78 for (300), and 38 for the (102) upper states. These empirical values have been combined with calculated positions and intensities of (H2O)-O-18 and (H2O)-O-17 and with available broadening coefficients from other spectral regions to form a new composite database. The sum of 5002 transition intensities for the region is 0.6417 cm(-2).atm(-1) (2.588 x 10(-20) cm(-1)/(molecule.cm(-2))) at 296 K. This new compilation appears in the 2000 edition of HITRAN. (C) 2002 Elsevier Science (USA). C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Solar Observ, Tucson, AZ 85726 USA. RP Brown, LR (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 37 TC 44 Z9 47 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD MAR PY 2002 VL 212 IS 1 BP 57 EP 82 DI 10.1006/jmsp.2002.8515 PG 26 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 555BF UT WOS:000175772400008 ER PT J AU Mulenburg, GM AF Mulenburg, GM TI Virtual manufacturing SO JOURNAL OF PRODUCT INNOVATION MANAGEMENT LA English DT Book Review C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Mulenburg, GM (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 1 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0737-6782 J9 J PROD INNOVAT MANAG JI J. Prod. Innov. Manage. PD MAR PY 2002 VL 19 IS 2 BP 180 EP 181 PG 2 WC Business; Engineering, Industrial; Management SC Business & Economics; Engineering GA 542AP UT WOS:000175021300009 ER PT J AU Brown, AM AF Brown, AM TI Temperature-dependent modal test/analysis correlation of X-34 FASTRAC composite rocket nozzle SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/ASME/ASCE/AHS/ASC 41st Structures, Structural Dynamics, and Materials Conference CY APR 03-06, 2000 CL ATLANTA, GEORGIA SP Amer Inst Aeronaut & Astronaut, ASME, ASCE, AHS, ASC AB A unique high-temperature modal test and model correlation/update program has been performed on the composite nozzle of the FASTRAC engine for the NASA X34 reusable launch vehicle. The program was required to provide an accurate high-temperature model of the nozzle for incorporation into the engine system structural dynamics model for loads calculation; this model is significantly different from the ambient case due to the large decrease in composite stiffness properties due to heating. The high-temperature modal test was performed during a hot-fire test of the nozzle. Previously, a series of high-fidelity modal tests and finite element model correlation of the nozzle in a free-free configuration had been performed. This model was then attached to a modal-test verified model of the engine hot-fire test stand, and the ambient system mode shapes were identified. A reduced set of accelerometers was then attached to the nozzle, the engine fired full duration, and the frequency peaks corresponding to the ambient nozzle modes individually isolated and tracked as they decreased during the test. To update the finite element model of the nozzle to these frequency curves, the percentage differences of the anisotropic composite moduli due to temperature variation from ambient, which had been used in the initial modeling and which were obtained by small sample coupon testing, were multiplied by an iteratively determined constant factor. These new properties were used to create high-temperature nozzle models corresponding to 10-s engine operation increments and tied into the engine system model for loads determination. RP Brown, AM (reprint author), NASA, George C Marshall Space Flight Ctr, Struct Dynam & Loads Grp, Huntsville, AL 35812 USA. NR 5 TC 10 Z9 13 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 2002 VL 18 IS 2 BP 284 EP 288 DI 10.2514/2.5968 PG 5 WC Engineering, Aerospace SC Engineering GA 532QV UT WOS:000174487300009 ER PT J AU Kankam, MD Lyons, VJ Hoberecht, MA Tacina, RR Hepp, AF AF Kankam, MD Lyons, VJ Hoberecht, MA Tacina, RR Hepp, AF TI Recent GRC aerospace technologies applicable to terrestrial energy systems SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB An overview of a wide range of recent aerospace technologies under development at the NASA John H. Glenn Research Center at Lewis Field, in collaboration with other NASA centers, government agencies, industry, and academia is provided. The focused areas are space solar power, advanced power management and distribution systems, Stirling cycle conversion systems, fuel cells, advanced thin-film photovoltaics and batteries, and combustion technologies. The aerospace-related objectives of the technologies are generation of space power; development of cost-effective and reliable, high-performance power systems; cryogenic applications; energy storage; and reduction in gas-turbine emissions, with attendant clean jet engines. The terrestrial energy applications of the technologies include augmentation of bulk power in ground power distribution systems and generation of residential, commercial, and remote power, as well as promotion of pollution-free environment via reduction in combustion emissions. C1 NASA, John H Glenn Res Ctr, POBPD, Cleveland, OH 44135 USA. NASA, John H Glenn Res Ctr, Turbomachinery & Prop Syst Div, Cleveland, OH 44135 USA. RP Kankam, MD (reprint author), NASA, John H Glenn Res Ctr, POBPD, Cleveland, OH 44135 USA. NR 21 TC 1 Z9 1 U1 3 U2 7 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 2002 VL 18 IS 2 BP 481 EP 488 DI 10.2514/2.5959 PG 8 WC Engineering, Aerospace SC Engineering GA 532QV UT WOS:000174487300034 ER PT J AU Liu, T Torgerson, S Sullivan, J Johnston, R Fleeter, S AF Liu, T Torgerson, S Sullivan, J Johnston, R Fleeter, S TI Transonic rotor blade pressure measurement using fluorescent paints SO JOURNAL OF PROPULSION AND POWER LA English DT Article C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. LM Aero, Palmdale, CA 93550 USA. Purdue Univ, Sch Aeronaut & Astronaut, W Lafayette, IN 47907 USA. Pratt & Whitney, Middletown, CT 06457 USA. Purdue Univ, Sch Mech Engn, W Lafayette, IN 47907 USA. RP Liu, T (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 5 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 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 2002 VL 18 IS 2 BP 491 EP 493 DI 10.2514/2.5961 PG 3 WC Engineering, Aerospace SC Engineering GA 532QV UT WOS:000174487300036 ER PT J AU Dorney, DJ Griffin, LW Huber, F Sondak, DL AF Dorney, DJ Griffin, LW Huber, F Sondak, DL TI Unsteady flow in a supersonic turbine with variable specific heats SO JOURNAL OF PROPULSION AND POWER LA English DT Article C1 NASA, George C Marshall Space Flight Ctr, Appl Fluids Dynam Anal Branch, Huntsville, AL 35812 USA. Riverbend Design Serv, Palm Beach Gardens, FL 33418 USA. Boston Univ, Off Informat Technol, Boston, MA 02215 USA. RP Dorney, DJ (reprint author), NASA, George C Marshall Space Flight Ctr, Appl Fluids Dynam Anal Branch, Huntsville, AL 35812 USA. NR 5 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 2002 VL 18 IS 2 BP 493 EP 496 DI 10.2514/2.5962 PG 4 WC Engineering, Aerospace SC Engineering GA 532QV UT WOS:000174487300037 ER PT J AU Reda, DC AF Reda, DC TI Review and synthesis of roughness-dominated transition correlations for reentry applications SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID BOUNDARY-LAYER-TRANSITION; SPEEDS C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Reda, DC (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 47 TC 47 Z9 48 U1 1 U2 6 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 2002 VL 39 IS 2 BP 161 EP 167 DI 10.2514/2.3803 PG 7 WC Engineering, Aerospace SC Engineering GA 541BV UT WOS:000174966100001 ER PT J AU Visentine, J Kinard, W Brinker, D Banks, B Albyn, K AF Visentine, J Kinard, W Brinker, D Banks, B Albyn, K TI Mir solar-array return experiment: Power performance measurements and molecular contamination analysis results SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT AIAA 39th Aerospace Sciences Meeting CY JAN 08-11, 2001 CL RENO, NEVADA SP Amer Inst Aeronaut & Astronaut AB In 1997 a solar-array segment was removed from the Space Station Mir core module and returned for ground-based analysis. The segment, which is similar to the ones the Russians have provided for the Functional Cargo Block and Service Module, was microscopically examined and disassembled by U.S. and Russian science teams. Laboratory analyses by the International Space Station program have shown the segment to be heavily contaminated by an organic silicone coating, which was converted to an organic silicate film by reactions with atomic oxygen within the orbital flight environment. The source of the contaminant was a silicone polymer used by the Russians as an adhesive and bonding agent during segment construction. During its life cycle, the array experienced a reduction in power performance from similar to12%, when it was new and first deployed, to similar to5%, when it was taken out of service. However, current-voltage measurements of three contaminated cells and three pristine Russian standard cells have shown that very little degradation in solar-array performance was caused by the silicate contaminants on the solar-cell surfaces. The primary sources of performance degradation is attributed to "thermal hot-spotting" or electrical arcing, orbital debris and micrometeoroid impacts, and possibly to the degradation of the solar cells and interconnects caused by radiation damage from high-energy protons and electrons. C1 Boeing Space Stn Program Off, Houston, TX 77058 USA. NASA Langley Res Ctr, Hampton, VA USA. NASA John H Glenn Res Ctr, Cleveland, OH 44135 USA. NASA Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Visentine, J (reprint author), Boeing Space Stn Program Off, Houston, TX 77058 USA. NR 5 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 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 2002 VL 39 IS 2 BP 187 EP 193 DI 10.2514/2.3818 PG 7 WC Engineering, Aerospace SC Engineering GA 541BV UT WOS:000174966100004 ER PT J AU Hunter, SL Dischinger, C Estes, S AF Hunter, SL Dischinger, C Estes, S TI Three-dimensional simulation: Microgravity environments and applications SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Most, if not all, three-dimensional and virtual reality (VR) software programs are designed for one-g gravity applications. For space environment simulations, where gravity is of the order of 10(-6) g or for all practical purposes nonexistent, one must be able to generate simulations that replicate microgravity effects upon simulated astronauts. Unfortunately, the software programs utilized by NASA do not have the ability to readily neutralize the 1-g gravity effect. This preprogrammed situation causes the engineer or analysis difficulty during microgravity, simulations. Therefore, microgravity simulations require special techniques or additional code in order to apply the power of three-dimensional graphic simulations to space-related applications. This paper discusses the problem and possible solutions to allow microgravity three-dimensional/VR simulations to be completed successfully without program code modifications. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Hunter, SL (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RI Hunter, Stanley/D-2942-2012 NR 6 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 2002 VL 39 IS 2 BP 194 EP 197 DI 10.2514/2.3819 PG 4 WC Engineering, Aerospace SC Engineering GA 541BV UT WOS:000174966100005 ER PT J AU Fasanella, EL Jones, Y Knight, NF Kellas, S AF Fasanella, EL Jones, Y Knight, NF Kellas, S TI Earth impact studies for Mars sample return SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Dynamic finite element modeling of a series of penetrometer drop tests into soft clay that were conducted as part of the Mars sample return advanced technology program is discussed. Structural impacts into soil continue to challenge analysts to develop accurate soil material models for finite element simulations to predict the observed deceleration pulse and impact crater. Parametric studies are presented for penetrometers of varying diameter, mass, and impact velocity to a maximum of 45 m/s, which is the expected terminal velocity of a sample return capsule. Parameters influencing the simulation such as the contact penalty factor and the material model representing the soil are discussed. An empirical relationship between peak deceleration and key parameters is developed and is shown to correlate experimental and analytical results. The results provide preliminary design guidelines for Earth impact that may be useful for future space exploration sample return missions. C1 NASA Langley Res Ctr, Hampton, VA 23681 USA. Veridian Syst, Fairfax, VA 22030 USA. RP Fasanella, EL (reprint author), NASA Langley Res Ctr, Hampton, VA 23681 USA. NR 12 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 2002 VL 39 IS 2 BP 237 EP 243 DI 10.2514/2.3805 PG 7 WC Engineering, Aerospace SC Engineering GA 541BV UT WOS:000174966100011 ER PT J AU Meyer, TR Pryor, WR McKay, CP McKenna, PM AF Meyer, TR Pryor, WR McKay, CP McKenna, PM TI Laser elevator: Momentum transfer using an optical resonator SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB In principle, spacecraft that do not carry their own propellant but are propelled by the transfer of momentum of photons can be accelerated to very high velocity. The subject of this research is a laser propulsion system utilizing the momentum of photons recirculating in an optical cavity that consists of a mirror on the spacecraft and a mirror fixed at the laser source. This configuration allows the photons in the beam to be recycled, thus multiplying the effective power of the laser. The gain of this system over a conventional lightsail depends on the number of times the photons can be recycled. We analyze the physics of this propulsion method, compare it with rockets, and examine its use for several cases of interest. We find that improvements in thrust on the order of 1000 over conventional lightsails may be feasible using mirrors whose reflectivity is 0.9995, but that diffraction sets the limit on system performance as the cavity expands. However, a system not too far from the current state of the art could reach Pluto in about 6.5 years. Other potential applications include rapid interplanetary delivery, reconnaissance of a new comet, and probes beyond the solar system. C1 Boulder Ctr Sci & Policy, Boulder, CO 80306 USA. Univ Colorado, Boulder, CO 80309 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Natl Telecommun & Informat Adm, Boulder, CO 80305 USA. RP Meyer, TR (reprint author), Boulder Ctr Sci & Policy, Boulder, CO 80306 USA. RI Chang, Yanwei/D-8117-2013 NR 21 TC 5 Z9 5 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 2002 VL 39 IS 2 BP 258 EP 266 DI 10.2514/2.3807 PG 9 WC Engineering, Aerospace SC Engineering GA 541BV UT WOS:000174966100013 ER PT J AU Parmenter, KE Shuman, K Milstein, F Szalai, CE Tran, HK Rasky, DJ AF Parmenter, KE Shuman, K Milstein, F Szalai, CE Tran, HK Rasky, DJ TI Compressive response of lightweight ceramic ablators: Silicone impregnated reusable ceramic ablator SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID GAS-PERMEABILITY AB Silicone impregnated reusable ceramic ablators are highly porous fibrous ceramic substrates that are partially impregnated with silicone. The ablators are used as heat shields for planetary entry. The compressive responses of virgin and charred ablators, and their corresponding fibrous substrates, are reported, The fibers in the materials tend to be randomly and uniformly aligned parallel to a preferred plane, resulting in anisotropic mechanical properties. Compressive loads, applied either parallel or normal to the preferred fiber-alignment plane, yielded initial stress-strain responses that were fairly linear, to strains of about 1 or 2%. For virgin ablators loaded normal to the fiber-alignment plane, the initial linear response was followed by a rapid decrease in the slope of the stress-strain curve, after which the stress increased asymptotically with strain, to strains over 80%, and stresses approaching 10 MPa, without macroscopic failure. In all other cases, after the initial linear response, the stress varied in an erratic, roughly horizontal, manner, without exceeding about 3 MPa. This erratic stress path indicates discontinuous breaking of the bonds between the fibers and/or buckling of the fibers. Good correlation between compressive strength and hardness was found among materials with this latter response. Comparisons are made with the behavior of phenolic impregnated carbon ablator. C1 Univ Calif Santa Barbara, Santa Barbara, CA 93106 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Parmenter, KE (reprint author), Univ Calif Santa Barbara, Santa Barbara, CA 93106 USA. NR 11 TC 3 Z9 4 U1 3 U2 11 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 2002 VL 39 IS 2 BP 290 EP 298 DI 10.2514/2.3811 PG 9 WC Engineering, Aerospace SC Engineering GA 541BV UT WOS:000174966100017 ER PT J AU Hirsch, DB Beeson, HD AF Hirsch, DB Beeson, HD TI Test method to determine flammability of aerospace materials SO JOURNAL OF TESTING AND EVALUATION LA English DT Article DE test methods; flammability; aerospace materials; combustion; microgravity AB Qualitative correlations between ground upward flammability tests and flammability testing in microaravity indicate that the NASA STD 6001 Test 1 provides conservative results by sustaining flaming combustion in less severe environments than those in which extinguishment occurs in quiescent microaravity environments. The upward flammability test is conducted in the most severe flaming combustion environment expected in the spacecraft. Its pass/fail test logic does not allow a precise quantitative comparison with other ground or microaravity materials flammability test results. Thus, although reasonable from a flammability safety point of view, the test is likely to eliminate materials that may be safe for use on spacecraft. A different test logic that will determine materials self-extinguishment limits is suggested to address these impediments. Data to support this approach are presented, including self-extinguishment limits in concurrent and countercurrent flows and under quiescent conditions. The proposed method will allow continued use of existing NASA flammability data and make possible quantitative correlations between ground testing and microgravity test results. Quantitative correlations between ground test results and microgravity combustion data will improve the aerospace materials selection process and allow realistic estimates of spacecraft fire extinguishment requirements. Theoretical analyses of flaming combustion will be possible, leading to a better understanding of materials combustion. This will benefit not only the aerospace community, but also the combustion community at large. C1 Honeywell Technol Solut Inc, NASA Labs Off, NASA, Lyndon B Johnson Space Ctr,White Sands Test Facil, Las Cruces, NM 88004 USA. RP Hirsch, DB (reprint author), Honeywell Technol Solut Inc, NASA Labs Off, NASA, Lyndon B Johnson Space Ctr,White Sands Test Facil, POB 20, Las Cruces, NM 88004 USA. NR 13 TC 5 Z9 6 U1 0 U2 0 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 USA SN 0090-3973 J9 J TEST EVAL JI J. Test. Eval. PD MAR PY 2002 VL 30 IS 2 BP 156 EP 159 PG 4 WC Materials Science, Characterization & Testing SC Materials Science GA 536RX UT WOS:000174716600008 ER PT J AU Salem, JA Jenkins, MG AF Salem, JA Jenkins, MG TI Estimating bounds on fracture stresses determined from mirror size measurements SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article AB Statistical techniques are used to derive closed-form. approximate solutions for estimating a standard deviation on the fracture stress determined from mirror size measurements. The estimated coefficient of variation of fracture stress is noted to be twice as sensitive to the variation of the mirror constant, A(j), as to the variation in the measured boundary radius. r(j). This allows the hackle radius to be reasonably estimated and bounded from the mirror and branch radii when it cannot be clearly delineated. C1 NASA, Gleen Res Ctr, Life Predict Branch, Cleveland, OH 44135 USA. Univ Washington, Dept Mech Engn, Seattle, WA 98195 USA. RP Salem, JA (reprint author), NASA, Gleen Res Ctr, Life Predict Branch, Cleveland, OH 44135 USA. NR 9 TC 2 Z9 2 U1 0 U2 0 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43086-6136 USA SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD MAR PY 2002 VL 85 IS 3 BP 706 EP 708 PG 3 WC Materials Science, Ceramics SC Materials Science GA 531HK UT WOS:000174409800031 ER PT J AU Tumakha, S Brillson, LJ Jessen, GH Okojie, RS Lukco, D Zhang, M Pirouz, P AF Tumakha, S Brillson, LJ Jessen, GH Okojie, RS Lukco, D Zhang, M Pirouz, P TI Chemically dependent traps and polytypes at Pt/Ti contacts to 4H and 6H-SiC SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article ID INTERFACE; TRANSFORMATION; SPECTROSCOPY; TEMPERATURE; VANADIUM; EMISSION; SILICON AB We have used low energy etectron-excited nanoluminescence (LEEN) spectroscopy and x-ray photoemission spectroscopy (XPS) to probe deep level defect states Lit interfaces of 4H and 6H-Sic with Ti/Pt metallization. These studies aim to identify process conditions under which thermally stable ohmic and Schottky contacts can be obtained on SiC while minimizing the formation of deep level electrorde states. Depth-dependent LEEN measurements establish the presence of localized states and their spatial distribution on a nanometer scale. Spectra from the near interface region of 6H-SiC indicate the existence of a SiC polytype with a higher build gap of similar to3.4 eV. Excitation of the intimate metal-SiC interface reveals a process-dependent discrete state deep within the SiC band gap. XPS measurements reveal consistent differences in the C Is chemical bonding changes with specific process steps. Analogous chemical treatments of 4H-SiC also produce a lower band gap SiC polytype with similar to2.5 eV energy extending tens of nanometers beyond the interface-confirmed by transmission electron microscopy. This work is the first to show the effect of metal-semiconductor interactions not only on localized states but also on the lattice,structure of the semiconductor near the interface. (C) 2002 American Vacuum Society. C1 Ohio State Univ, Dept Phys, Columbus, OH 43210 USA. Ohio State Univ, Dept Elect Engn, Columbus, OH 43210 USA. Ohio State Univ, Ctr Mat Res, Columbus, OH 43210 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. AYT 20001 Aerosp Pk, Brookpark, OH 44142 USA. Case Western Reserve Univ, Cleveland, OH 44106 USA. RP Tumakha, S (reprint author), Ohio State Univ, Dept Phys, 174 W 19th Ave, Columbus, OH 43210 USA. NR 23 TC 10 Z9 10 U1 0 U2 6 PU A V S AMER INST PHYSICS PI MELVILLE PA STE 1 NO 1, 2 HUNTINGTON QUADRANGLE,, MELVILLE, NY 11747-4502 USA SN 1071-1023 J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD MAR-APR PY 2002 VL 20 IS 2 BP 554 EP 560 DI 10.1116/1.1451303 PG 7 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA 544PH UT WOS:000175168800009 ER PT J AU Cruden, BA Gleason, KK Sawin, HH AF Cruden, BA Gleason, KK Sawin, HH TI Relationship of CF2 concentration to deposition rates in the pyrolytic chemical vapor deposition process SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article ID ULTRAVIOLET-ABSORPTION SPECTROSCOPY; PTFE THIN-FILMS; FLUOROCARBON FILMS; ETCHING PLASMAS; CONSTANT; MORPHOLOGY; BAND AB Polytetrafluoroethylene films have been deposited for use as low dielectric constant materials, in microelectronic chips. Deposition is performed through pyrolysis of hexalluoropropylene oxide on a heated filament array to produce CF2, which can then polymerize and deposit as a thin film. The variation of CF2 concentration as a function of the pressure and filament temperature has been characterized by ultraviolet absorption spectroscopy. The CF, concentration is seen to approach a constant as filament temperature approaches 400degreesC, and an activation energy of 11.9 kcal/mol is measured at lower temperatures. Attempting to develop a specific relationship between the CF, concentration and deposition rate yields a sticking coefficient of similar to4 X 10(-5). which is consistent with what has been measured in a CF2 beam experiment. However, this result is not sufficient to explain deposition properties observed in other related work. This implies that it is possible for of the. properties of the deposition process to affect the sticking coefficient. A consistent alternative Picture is also developed in which gas phase polymerization can produce (CF,), species that are responsible for depostion. (C) 2002 American Vacuum Society. C1 MIT, Dept Chem Engn, Cambridge, MA 02139 USA. RP Cruden, BA (reprint author), NASA, Ames Res Ctr, Eloret Corp, MS 223-3, Moffett Field, CA 94035 USA. RI Gleason, Karen/G-1471-2013 OI Gleason, Karen/0000-0001-6127-1056 NR 25 TC 7 Z9 7 U1 0 U2 5 PU A V S AMER INST PHYSICS PI MELVILLE PA STE 1 NO 1, 2 HUNTINGTON QUADRANGLE,, MELVILLE, NY 11747-4502 USA SN 1071-1023 J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD MAR-APR PY 2002 VL 20 IS 2 BP 690 EP 695 DI 10.1116/1.1459726 PG 6 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA 544PH UT WOS:000175168800032 ER PT J AU Bailin, SC Truszkowski, W AF Bailin, SC Truszkowski, W TI Ontology negotiation between intelligent information agents SO KNOWLEDGE ENGINEERING REVIEW LA English DT Article; Proceedings Paper CT 13th International Conference on Knowledge Engineering and Knowledge Management (EKAW 2002) CY OCT 01-04, 2002 CL SIGUENZA, SPAIN SP Univ Politecn Madrid, UPM, Fac Informat, iSOCO, Minist Ciencia & Technol, OntoWeb, Amer Assoc Artificial Intelligence, IBROW ID CONTEXT INTERCHANGE; SEMANTIC WEB; SYSTEM AB This paper describes an approach to ontology negotiation between agents supporting intelligent information management. Ontologies are declarative (data-driven) expressions of an agent's "world": the objects, operations, facts and rules that constitute the logical space within which an agent performs. Ontology negotiation enables agents to cooperate in performing a task, even if they are based on different ontologies. Our objective is to increase the opportunities for "strange agents" - that is, agents not necessarily developed within the same framework or with the same contextual operating assumptions - to communicate in solving tasks when they encounter each other on the web. In particular, we have focused on information search tasks. We have developed a protocol that allows agents to discover ontology conflicts and then, through incremental interpretation, clarification and explanation, establish a common basis for communicating with each other. We have implemented this protocol in a set of Java classes that can be added to a variety of agents, irrespective of their underlying ontological assumptions. We have demonstrated the use of the protocol, through this implementation, in a test-bed that includes two large scientific archives: NASA's Global Change Master Directory and NOAN's Wind and Sea Index. This paper presents an overview of different methods for resolving ontology mismatches and motivates the Ontology Negotiation Protocol (ONP) as a method that addresses some problems with other approaches. Much remains to be done. The protocol must be tested in larger and less familiar contexts (for example, numerous archives that have not been preselected) and it must be extended to accommodate additional forms of clarification and ontology evolution. C1 Knowledge Evolut Inc, Washington, DC 20036 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Knowledge Evolut Inc, 1215 17th St NW,Suite 101, Washington, DC 20036 USA. EM sbailin@kevol.com; Walt.Truszkowski@gsfc.nasa.gov NR 35 TC 27 Z9 29 U1 1 U2 5 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0269-8889 EI 1469-8005 J9 KNOWL ENG REV JI Knowl. Eng. Rev. PD MAR PY 2002 VL 17 IS 1 BP 7 EP 19 DI 10.1017/S0269888902000292 PG 13 WC Computer Science, Artificial Intelligence SC Computer Science GA 595LB UT WOS:000178109700002 ER PT J AU Zalameda, JN AF Zalameda, JN TI Heat source finite pulse time effects in thermal nondestructive testing SO MATERIALS EVALUATION LA English DT Article DE thermal diffusivity; thermal nondestructive testing; impulse heating; pulse heating ID DIFFUSIVITY AB An important material property for quantitative thermal nondestructive testing (NDT) is the measurement of thermal diffusivity. Any change in this material property can potentially be attributed to a discontinuity. One area causing a potential error in the measurement of thermal diffusivity is the finite pulse time of the input heat source. Newer infrared camera technologies have allowed for the capture of very fast transient temperature events. These events can be affected by the finite pulse time of the input heat source. In this work, two types of commonly used heat sources are investigated: flash and quartz heat lamps. Measurement errors of thermal diffusivity are demonstrated for aluminum and stainless steel samples of varying thickness where the finite pulse time of the input heat flux is not taken into account. An analysis is presented to estimate these measurement errors. This is necessary to calculate when the finite pulse time of the input heat flux must be taken into account. By improving the measurement accuracy, thermal NDT can be snore readily accepted as a quantitative testing technique and potentially open new areas of application. C1 USA, Res Lab, Vehicle Technol Directorate MS 231, NASA,Langley Res Ctr, Hampton, VA 23681 USA. RP Zalameda, JN (reprint author), USA, Res Lab, Vehicle Technol Directorate MS 231, NASA,Langley Res Ctr, Hampton, VA 23681 USA. NR 16 TC 4 Z9 4 U1 0 U2 2 PU AMER SOC NON-DESTRUCTIVE TEST PI COLUMBUS PA 1711 ARLINGATE LANE PO BOX 28518, COLUMBUS, OH 43228-0518 USA SN 0025-5327 J9 MATER EVAL JI Mater. Eval. PD MAR PY 2002 VL 60 IS 3 BP 425 EP 429 PG 5 WC Materials Science, Characterization & Testing SC Materials Science GA 529RE UT WOS:000174311700008 ER PT J AU Gyekenyesi, AL AF Gyekenyesi, AL TI Testing static and dynamic stresses in metallic alloys using thermoelastic stress analysis SO MATERIALS EVALUATION LA English DT Article DE thermoelastic stress analysis; thermoelastic constant; residual stress; mean stress; stress pattern analysis by thermal emission AB This study focuses oil the application of the thermoelastic stress analysis technique as a tool for assessing the residual stress state of structures. Thermoelastic stress analysis is based oil the fact that materials experience small temperature changes when compressed or expanded. Men a structure is cyclically loaded, a surface temperature profile results, which correlates to the surface stresses. The cyclic surface temperature is measured with an infrared camera. Traditionally, the amplitude of a thermoelastic stress analysis signal was theoretically defined to be linearly dependent oil the cyclic stress amplitude. Recent studies have established that the temperature response is also dependent on the cyclic wean stress (for example, the static stress state of the structure). In a previous study by Gyekenyesi and Baaklini (1999), it was shown that mean stresses significantly influenced the results for titanium and nickel based alloys. This study continues the effort of accurate direct measurements of the mean stress effect by implementing various experimental modifications. In addition, a more in depth analysis was conducted which involved analyzing the second harmonic of the temperature response. By obtaining the amplitudes of the first and second harmonics, the stress amplitude and the mean stress at a given point oil a structure, subjected to a cyclic load, can be simultaneously obtained. The experimental results showed good agreement with the theoretical predictions for both the first and second harmonics of the temperature response. As a result, confidence was achieved concerning the ability to simultaneously obtain values for the static stress state as well as the cyclic stress amplitude of structures subjected to cyclic loads using the thermoelastic stress analysis technique. With continued research, it is now feasible to establish a protocol that would enable the monitoring of residual stresses in structures utilizing the technique. C1 OAI, NASA, Glenn Res Ctr, Cleveland, OH 44115 USA. RP Gyekenyesi, AL (reprint author), OAI, NASA, Glenn Res Ctr, 2100 Brookpk Rd,MS 6-1, Cleveland, OH 44115 USA. NR 11 TC 1 Z9 1 U1 0 U2 0 PU AMER SOC NON-DESTRUCTIVE TEST PI COLUMBUS PA 1711 ARLINGATE LANE PO BOX 28518, COLUMBUS, OH 43228-0518 USA SN 0025-5327 J9 MATER EVAL JI Mater. Eval. PD MAR PY 2002 VL 60 IS 3 BP 445 EP 451 PG 7 WC Materials Science, Characterization & Testing SC Materials Science GA 529RE UT WOS:000174311700011 ER PT J AU McKenna, VT Rubal, MP Steif, PS Pereira, JM Gray, GT AF McKenna, VT Rubal, MP Steif, PS Pereira, JM Gray, GT TI Cracking in gamma-TiAl due to high speed particle impact SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID BEHAVIOR AB Cracking due to small particle impacts on prospective gamma-TiAl blades in jet turbine engines has been studied experimentally and theoretically. Flat rectangular specimens of two gamma-TiAl alloys, with edges chamfered to resemble the taper of blades, were subjected to small particle impacts. The forms of damage observed resembled those revealed by earlier studies using specimens that were cast closely to the shape of blade leading edges. Numerical simulations of the impact events were carried out using finite element analysis, using uniaxial stress-strain behavior that was obtained in compression at high strain rates. A criterion for cracking is proposed that requires critical levels of plastic strain and tensile stress. Predictions of crack extent that were based on such a combined criterion were found to be in the range of observations. The predictive methodology, together with information on the fatigue strength of various damage states, potentially offers designers the opportunity to examine the risk associated with small particle damage on contemplated blades. C1 Hall Ind, Pittsburgh, PA 15219 USA. Battelle Mem Inst, Columbus, OH 43201 USA. Carnegie Mellon Univ, Dept Engn Mech, Pittsburgh, PA 15213 USA. NASA, Glenn Res Ctr, Struct & Acoust Div, Cleveland, OH USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. RP McKenna, VT (reprint author), Hall Ind, Pittsburgh, PA 15219 USA. RI Steif, Paul/D-2459-2013 NR 17 TC 6 Z9 6 U1 0 U2 4 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 184 THORN HILL RD, WARRENDALE, PA 15086 USA SN 1073-5623 J9 METALL MATER TRANS A JI Metall. Mater. Trans. A-Phys. Metall. Mater. Sci. PD MAR PY 2002 VL 33 IS 3 BP 581 EP 589 DI 10.1007/s11661-002-0120-7 PG 9 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA 564TA UT WOS:000176328600013 ER PT J AU Raj, SV Locci, IE Salem, JA Pawlik, RJ AF Raj, SV Locci, IE Salem, JA Pawlik, RJ TI Effect of directionally solidified microstructures on the room-temperature fracture-toughness properties of Ni-33(at. pct)Al-33Cr-1 Mo and Ni-33(at. pct)Al-31 Cr-3Mo eutectic alloys grown at different solidification rates SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID ROD-PLATE TRANSITION; NIAL-CR; CREEP-BEHAVIOR; COMPOSITES; LAMELLAR AB Directionally solidified (DS) Ni-33(at. pct)Al-33Cr-1Mo and Ni-33(at. pct)Al-3iCr-3Mo eutectic alloys were grown at different rates varying from 7.6 to 508 mm h(-1). The microstructures consisted of eutectic colonies with parallel lamellar NiAl/(CrMo) plates for solidification rates at and below 12.7 mm h(-1). Cellular eutectic microstructures were observed at higher solidification rates, where the plates exhibited a radial pattern. Room-temperature fracture-toughness tests were conducted using a modified ASTM E-399 technique. The average fracture-toughness values for specimens with planar eutectic and cellular microstructures were about 12 to 15 and 17 MParootm, respectively, for both alloys. However, the Ni-33(at. pct)Al-33Cr-1Mo specimens grown at and above 254 mm h(-1) exhibited fracture toughness values of about 8 MPa, m due to the presence of short (CrMo) plates. The fracture toughness values for the Ni-33(at. pct)Al-31Cr-3Mo alloy were also correlated with quantitative microstructural data in an attempt to identify the relevant elements of the microstructure determining resistance to fracture. A phenomenological fracture model is presented in an attempt to rationalize the present observations. C1 Case Western Reserve Univ, NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Cleveland, OH 44135 USA. RP Raj, SV (reprint author), Case Western Reserve Univ, NASA, Glenn Res Ctr, Lewis Field, Cleveland, OH 44135 USA. NR 32 TC 22 Z9 22 U1 2 U2 3 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 1073-5623 EI 1543-1940 J9 METALL MATER TRANS A JI Metall. Mater. Trans. A-Phys. Metall. Mater. Sci. PD MAR PY 2002 VL 33 IS 3 BP 597 EP 612 DI 10.1007/s11661-002-0122-5 PG 16 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA 564TA UT WOS:000176328600015 ER PT J AU Norman, MD Mittlefehldt, DW AF Norman, MD Mittlefehldt, DW TI Impact processing of chondritic planetesimals: Siderophile and volatile element fractionation in the Chico L chondrite SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID TRACE-ELEMENTS; PARENT BODY; PRIMITIVE METEORITES; CORE FORMATION; CONSTRAINTS; ORIGIN; METAMORPHISM; ABUNDANCES; PETROLOGY; ASTEROIDS AB A large impact event 500 Ma ago shocked and melted portions of the L-chondrite parent body. Chico is an impact melt breccia produced by this event. Sawn surfaces of this 105 kg meteorite reveal a dike of fine-grained, clast-poor impact melt cutting shocked host chondrite. Coarse (1-2 cm diameter) globules of FeNi metal + sulfide are concentrated along the axis of the dike from metal-poor regions toward the margins. Refractory lithophile element abundance patterns in the melt rock are parallel to average L chondrites, demonstrating near-total fusion of the L-chondrite target by the impact and negligible crystal-liquid fractionation during emplacement and cooling of the dike. Significant geochemical effects of the impact melting event include fractionation of siderophile and chalcophile elements with increasing metal-silicate heterogeneity, and mobilization of moderately to highly volatile elements. Siderophile and chalcophile elements ratios such as Ni/Co, Cu/Ga, and Ir/Au vary systematically with decreasing metal content of the melt. Surprisingly small (similar to10(2)) effective metal/silicate-melt distribution coefficients for highly sideropbile elements probably reflect inefficient segregation of metal despite the large degrees of melting. Moderately volatile lithophile elements such K and Rb were mobilized and heterogeneously distributed in the L-chondrite impact breccias whereas highly volatile elements such as Cs and Pb were profoundly depleted in the region of the parent body sampled by Chico. Volatile element variations in Chico and other L chondrites are more consistent with a mechanism related to impact heating rather than condensation from a solar nebula. Impact processing can significantly alter the primary distributions of siderophile and volatile elements in chondritic planetesimals. C1 Lunar & Planetary Inst, Houston, TX 77058 USA. NASA, Johnson Space Ctr, Houston, TX 77058 USA. Australian Natl Univ, Res Sch Earth Sci, Canberra, ACT 0200, Australia. RP Norman, MD (reprint author), Lunar & Planetary Inst, 3600 Bay Area Blvd, Houston, TX 77058 USA. NR 54 TC 13 Z9 14 U1 1 U2 2 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAR PY 2002 VL 37 IS 3 BP 329 EP 344 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 538BW UT WOS:000174795000002 ER PT J AU Mittlefehldt, DW Killgore, M Lee, MT AF Mittlefehldt, DW Killgore, M Lee, MT TI Petrology and geochemistry of D'Orbigny, geochemistry of Sahara 99555, and the origin of angrites SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID ANGRA-DOS-REIS; RARE-EARTH ELEMENTS; PARENT BODY; METEORITES; ACHONDRITES; AGES; MELT; PETROGENESIS; ASUKA-881371; METAMORPHISM AB We have done a detailed petrologic study of the angrite, D'Orbigny, and geochemical study of it and Sahara 99555. D'Orbigny is an igneous-textured rock composed of Ca-rich olivine, Al-Ti-diopside-hedenbergite, subcalcic kirschsteinite, two generations of hercynitic spinel and anorthite, with the mesostasis phases ulvospinel, Ca-phosphate, a silico-phosphate phase and Fe-sulfide. We report an unknown Fe-Ca-Al-Ti-silicate phase in the mesostasis not previously found in angrites. One hercynitic spinel is a large, rounded homogeneous grain of a different composition than the euhedral and zoned grains. We believe the former is a xenocryst, the first such described from angrites. The mafic phases are highly zoned; mg# of cores for olivine are similar to64, and for clinopyroxene similar to58, and both are zoned to Mg-free rims. The Ca content of olivine increases with decreasing mg#, until olivine with similar to20 mol% Ca is overgrown by subcalcic kirschsteinite with about 30-35 mol% Ca. Detailed zoning sequences in olivine-subcalcie kirschsteinite and clinopyroxene show slight compositional reversals. There is no mineralogic control that can explain these reversals, and we believe they were likely caused by local additions of more primitive melt during crystallization of D'Orbigny. D'Orbigny is the most ferroan angrite with a bulk rock mg# of 32. Compositionally, it is virtually identical to Sahara 99555; they are the first set of compositionally identical angrites. Comparison with the other angrites shows that there is no simple petrogenetic sequence, partial melting with or without fractional crystallization, that can explain the angrite suite. Angra dos Reis remains an anomalous angrite. Angrites show no evidence for the brecciation, shock, impact metamorphism, or thermal metamorphism that affected the howardite, eucrite, diogenite (HED) suite and ordinary chondrites. This suggests that the angrite parent body may have followed a fundamentally different evolutionary path than did these other parent bodies. C1 NASA, Johnson Space Ctr, Houston, TX 77058 USA. SW Meteorite Lab, Payson, AZ 85541 USA. Hernandez Engn Inc, Houston, TX 77058 USA. RP Mittlefehldt, DW (reprint author), NASA, Johnson Space Ctr, Mail Code SR, Houston, TX 77058 USA. NR 51 TC 81 Z9 81 U1 1 U2 18 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAR PY 2002 VL 37 IS 3 BP 345 EP 369 PG 25 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 538BW UT WOS:000174795000003 ER PT J AU Fagan, TJ Taylor, GJ Keil, K Bunch, TE Wittke, JH Korotev, RL Jolliff, BL Gillis, JJ Haskin, LA Jarosewich, E Clayton, RN Mayeda, TK Fernandes, VA Burgess, R Turner, G Eugster, O Lorenzetti, S AF Fagan, TJ Taylor, GJ Keil, K Bunch, TE Wittke, JH Korotev, RL Jolliff, BL Gillis, JJ Haskin, LA Jarosewich, E Clayton, RN Mayeda, TK Fernandes, VA Burgess, R Turner, G Eugster, O Lorenzetti, S TI Northwest Africa 032: product of lunar volcanism SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID LASER ARGON-40-ARGON-39 AGE; APOLLO 12 SITE; MARE BASALTS; CENTRAL HIGHLANDS; CRYSTAL-GROWTH; NOBLE-GASES; METEORITE; CRYSTALLIZATION; OLIVINE; HISTORY AB Mineralogy, major element compositions of minerals, and elemental and oxygen isotopic compositions of the whole rock attest to a lunar origin of the meteorite Northwest Africa (NWA) 032, an unbrecciated basalt found in October 1999. The rock consists predominantly of olivine, pyroxene and chromite phenocrysts, set in a crystalline groundmass of feldspar, pyroxene, ilmenite, troilite and trace metal. Whole-rock shock veins comprise a minor, but ubiquitous portion of the rock. Undulatory to mosaic extinction in olivine and pyroxene phenocrysts and micro-faults in groundmass and phenocrysts also are attributed to shock. Several geochemical signatures taken together indicate unambiguously that NWA 032 originated from the Moon. The most diagnostic criteria include whole-rock oxygen isotopic composition and ratios of Fe/Mn in the whole rock, olivine, and pyroxene. A lunar origin is documented further by the presence of Fe-metal, troilite, and ilmenite; zoning to extremely Fe-rich compositions in pyroxene; the ferrous oxidation state of all Fe in pyroxene; and the rare earth element (REE) pattern with a well-defined negative europium anomaly. This rock is similar in major element chemistry to basalts from Apollo 12 and 15, but is enriched in light REE and has an unusually high Th/Sm ratio. Some Apollo 14 basalts yield a closer match to NWA 032 in REE patterns, but have higher concentrations of Al(2)O(3). Ar-Ar step release results are complex, but yield a whole-rock age of similar to2.8 Ga, suggesting that NWA 032 was extruded at 2.8 Ga or earlier. This rock may be the youngest sample of mare basalt collected to date. Noble gas concentrations combined with previously collected radionuclide data indicate that the meteorite exposure history is distinct from currently recognized lunar meteorites. In short, the geochemical and petrographic features of NWA 032 are not matched by Apollo or Luna samples, nor by previously identified lunar meteorites, indicating that it originates from a previously unsampled mare deposit. Detailed assessment of petrographic features, olivine zoning, and thermodynamic modelling indicate a relatively simple cooling and crystallization history for NWA 032. Chromite-spinel, olivine, and pyroxene crystallized as phenocrysts while the magma cooled no faster than 2 degreesC/h based on the polyhedral morphology of olivine. Comparison of olivine size with crystal growth rates and preserved Fe-Mg diffusion profiles in olivine phenocrysts suggest that olivine was immersed in the melt for no more than 40 days. Plumose textures in groundmass pyroxene, feldspar, and ilmenite, and Fe-rich rims on the phenocrysts formed during rapid crystallization (cooling rates similar to20 to 60 degreesC/h) after eruption. C1 Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. No Arizona Univ, Dept Geol, Flagstaff, AZ USA. Washington Univ, Dept Earth & Planetary Sci, St Louis, MO 63130 USA. Smithsonian Inst, Dept Mineral Sci, Washington, DC 20560 USA. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Manchester, Dept Earth Sci, Manchester M13 9PL, Lancs, England. Univ Bern, Inst Phys, CH-3012 Bern, Switzerland. RP Fagan, TJ (reprint author), Tokyo Inst Technol, Meguro Ku, 2-12-1 Ookayama, Tokyo 1528551, Japan. EM fagan@geo.titech.ac.jp RI Burgess, Ray/A-5767-2009; Fernandes, Vera/B-4653-2013; Lorenzetti, Silvio/B-1188-2009 OI Burgess, Ray/0000-0001-7674-8718; Fernandes, Vera/0000-0003-0848-9229; Lorenzetti, Silvio/0000-0002-8339-8960 NR 78 TC 55 Z9 59 U1 2 U2 6 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 MAR PY 2002 VL 37 IS 3 BP 371 EP 394 PG 24 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 538BW UT WOS:000174795000004 ER PT J AU Rodgers, SD Charnley, SB AF Rodgers, SD Charnley, SB TI A model of the chemistry in cometary comae: deuterated molecules SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Review DE astrochemistry; comets : general; comets : individual : Hale-Bopp; comets : individual : Hyakutake ID O1 HALE-BOPP; INTER-STELLAR MOLECULES; STATE DYNAMICAL PICTURE; C/1996 B2 HYAKUTAKE; OUTER SOLAR NEBULA; 121.6 NM; PHOTODISSOCIATION DYNAMICS; DEUTERIUM FRACTIONATION; HOT CORES; DISSOCIATIVE RECOMBINATION AB We have developed a combined chemical and hydrodynamical model of cometary comae. The model is described and used to follow the deuterium chemistry occurring in the coma after the sublimation of D-rich nuclear ices. It is shown that the molecular D/H ratios in parent species remain unchanged in the coma gas, confirming that observations of such molecules can be used to infer the D/H ratio in the nuclear ices. The D/H ratios in daughter molecules reflect that of their parents. and so can potentially be used to elucidate the formation mechanisms of these species. In particular, observations of DNC may be able to resolve the uncertainty surrounding the origin of HNC in cometary comae. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Rodgers, SD (reprint author), NASA, Ames Res Ctr, Div Space Sci, MS 245-3, Moffett Field, CA 94035 USA. EM rodgers@dusty.arc.nasa.gov RI Charnley, Steven/C-9538-2012 NR 136 TC 28 Z9 28 U1 0 U2 4 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD MAR 1 PY 2002 VL 330 IS 3 BP 660 EP 674 DI 10.1046/j.1365-8711.2002.05165.x PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 530NQ UT WOS:000174365200020 ER PT J AU Yeh, HC Chen, GTJ Liu, WT AF Yeh, HC Chen, GTJ Liu, WT TI Kinematic characteristics of a mei-yu front detected by the QuikSCAT oceanic winds SO MONTHLY WEATHER REVIEW LA English DT Article ID AREA MESOSCALE EXPERIMENT; EXPERIMENT TAMEX; TAIWAN; FEATURES; SEASON AB Based on conventional surface observations and NASA Quick Scatterometer (QuikSCAT) data, a heavy rainfall event that occurred in the Taiwan mei-yu season was chosen to further study the kinematic characteristics of the accompanying surface front. With the help of the QuikSCAT oceanic surface winds, it was found that the location and propagation of a mei-yu front over the ocean to the east of Taiwan during 10-12 June 2000 are better represented by the frontal wind shift line, which was located approximately on the leading edge of the baroclinic zone. The mesoscale system with cyclonic circulation embedded within the frontal zone was clearly shown in the wind field and kinematic parameters (horizontal divergence and vorticity) as well as satellite clouds and rainfall estimations. The conditional instability of the second kind (CISK) process was suggested to be responsible for the intensification of the mei-yu front and the frontal disturbance over the ocean. Under the influence of island topography over Taiwan and the mountains over southern China, the frontal wind shift line distorted and receded within the Taiwan Strait after the mei-yu front reached northern Taiwan. In the later period, the front moved southward faster to the area immediately east of Taiwan as compared to that over southwestern Taiwan and the Taiwan Strait due to earlier arrival of strong postfrontal northerly winds. The localized southwesterly jetlike feature was observed to the southeast of Taiwan and persisted until the arrival of the strong northerly winds. These localized phenomena were detected by the QuikSCAT oceanic winds. C1 Natl Taiwan Univ, Dept Atmospher Sci, Taipei 10772, Taiwan. Aletheia Univ, Dept Comp & Informat Sci, Taipei, Taiwan. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Chen, GTJ (reprint author), Natl Taiwan Univ, Dept Atmospher Sci, 61,Ln 144,Sec 4,Keelung Rd, Taipei 10772, Taiwan. NR 23 TC 10 Z9 10 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD MAR PY 2002 VL 130 IS 3 BP 700 EP 711 DI 10.1175/1520-0493(2002)130<0700:KCOAMY>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 523VA UT WOS:000173976900014 ER PT J AU Spicer, D Bingham, R Huba, J Shapiro, VD AF Spicer, D Bingham, R Huba, J Shapiro, VD TI Particle acceleration in tangential discontinuities by lower hybrid waves SO NONLINEAR PROCESSES IN GEOPHYSICS LA English DT Article ID INSTABILITY AB We consider the role that the lower-hybrid wave turbulence plays in providing the necessary resistivity at collisionless reconnection sights. The mechanism for generating the waves is considered to be the lower-hybrid drift instability. We find that the level of the wave amplitude is sufficient enough to heat and accelerate both electrons and ions. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Rutherford Appleton Lab, Chilton OX11 0QX, Oxon, England. Univ Strathclyde, Dept Phys & Appl Phys, Glasgow G4 0NG, Lanark, Scotland. USN, Res Lab, Beam Phys Branch, Washington, DC USA. Univ Calif San Diego, Dept Elect & Comp Engn, La Jolla, CA 92091 USA. RP Bingham, R (reprint author), NASA, Goddard Space Flight Ctr, Code 930, Greenbelt, MD 20771 USA. NR 9 TC 2 Z9 2 U1 0 U2 0 PU EUROPEAN GEOPHYSICAL SOC PI KATLENBURG-LINDAU PA MAX-PLANCK-STR 13, 37191 KATLENBURG-LINDAU, GERMANY SN 1023-5809 J9 NONLINEAR PROC GEOPH JI Nonlinear Process Geophys. PD MAR PY 2002 VL 9 IS 2 SI SI BP 121 EP 124 PG 4 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 540PG UT WOS:000174936900007 ER PT J AU Perreault, JA Bifano, TG Levine, BM Horenstein, MN AF Perreault, JA Bifano, TG Levine, BM Horenstein, MN TI Adaptive optic correction using microelectromechanical deformable mirrors SO OPTICAL ENGINEERING LA English DT Article DE adaptive optics; actuators; aberrations; micromachined; mirrors; optical phase correction; wavefront reconstruction ID SILICON AB A micromachined deformable mirror (mu-DM) for optical wave-front correction is described. Design and manufacturing approaches for mu-DMs are detailed. The mu-DM employs a flexible silicon membrane supported by mechanical attachments to an array of electrostatic parallel plate actuators. Devices are fabricated through surface micromachining using polycrystalline silicon thin films. mu-DM membranes measuring 2 mm x 2 mm X 2 mum, supported by 100 actuators are described. Figures of merit include stroke of 2 mum, resolution of 10 nm, and frequency bandwidth dc to 7 kHz in air. The devices are compact, inexpensive to fabricate, exhibit no hysteresis, and use only a small fraction of the power required for conventional DMs. Performance of an adaptive optics system using a mu-DM is characterized in a closed-loop control experiment. Significant reduction in quasistatic wavefront phase error is achieved. Advantages and limitations of mu-DMs are described in relation to conventional adaptive optics systems and to emerging applications of adaptive optics such as high-resolution correction, small-aperture systems, and optical communication. (C) 2002 Society of Photo-Optical Instrumentation Engineers. C1 Boston Univ, Boston, MA 02215 USA. Jet Prop Lab, Pasadena, CA 91109 USA. RP Perreault, JA (reprint author), Boston Univ, Boston, MA 02215 USA. RI Bifano, Thomas/E-6412-2013 OI Bifano, Thomas/0000-0003-4952-2515 NR 9 TC 63 Z9 65 U1 1 U2 11 PU SPIE-INT SOCIETY OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98225 USA SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD MAR PY 2002 VL 41 IS 3 BP 561 EP 566 DI 10.1117/1.1447230 PG 6 WC Optics SC Optics GA 533AY UT WOS:000174508300005 ER PT J AU Marcinkevicius, S Leon, R Cechavicius, B Siegert, J Lobo, C Magness, B Taylor, W AF Marcinkevicius, S Leon, R Cechavicius, B Siegert, J Lobo, C Magness, B Taylor, W TI Changes in carrier dynamics induced by proton irradiation in quantum dots SO PHYSICA B-CONDENSED MATTER LA English DT Article; Proceedings Paper CT 12th International Conference on Nonequilibrium Carrier Dynamics in Semiconductors (HCIS-12) CY AUG, 2001 CL SANTA FE, NEW MEXICO DE quantum dots; proton irradiation; time-resolved photoluminescence ID ENHANCED RADIATION HARDNESS; LASERS; DAMAGE AB The effects of proton irradiation on carrier dynamics were investigated by time-resolved photoluminescence on different InGaAs/GaAs quantum-dot (QD) structures varying in QD surface density and substrate orientation, as well as thin InGaAs quantum wells. The carrier lifetimes in the dots are much less affected by proton irradiation than in the wells. Decrease in lifetimes of only 40 percent at the highest proton dose are observed in some of the QDs, whereas an similar to20 to similar to40-fold decrease is observed in the wells. Similar trends were observed for all quantum dot samples. (C) 2002 Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Royal Inst Technol, Dept Microelect & Informat Technol, S-16440 Kista, Sweden. Lithuania Acad Sci, Inst Semicond Phys, LT-2600 Vilnius, Lithuania. Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England. Calif State Univ Los Angeles, Dept Phys & Astron, Los Angeles, CA 90032 USA. RP Leon, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Schaff, William/B-5839-2009; Lobo, Charlene/B-3977-2013; Lobo, Charlene/G-5003-2011 OI Lobo, Charlene/0000-0002-2746-1363; Lobo, Charlene/0000-0002-2746-1363 NR 10 TC 11 Z9 11 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4526 J9 PHYSICA B JI Physica B PD MAR PY 2002 VL 314 IS 1-4 BP 203 EP 206 AR PII S0921-4526(01)01361-8 DI 10.1016/S0921-4526(01)01361-8 PG 4 WC Physics, Condensed Matter SC Physics GA 558ZD UT WOS:000175997500046 ER PT J AU McCammon, D Galeazzi, M Liu, D Sanders, WT Smith, B Tan, P Boyce, KR Brekosky, R Gygax, JD Kelley, R Mott, DB Porter, FS Stahle, CK Stahle, CM Szymkowiak, AE AF McCammon, D Galeazzi, M Liu, D Sanders, WT Smith, B Tan, P Boyce, KR Brekosky, R Gygax, JD Kelley, R Mott, DB Porter, FS Stahle, CK Stahle, CM Szymkowiak, AE TI 1/f noise and hot electron effects in variable range hopping conduction SO PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS LA English DT Article; Proceedings Paper CT 9th International Conference on Hopping and Related Phenomena CY SEP 03-06, 2001 CL SHEFAYIM, ISRAEL ID X-RAY SPECTROSCOPY; DOPED SILICON; CALORIMETERS AB In the course of developing microcalorimeters as detectors for astronomical X-ray spectroscopy, we have undertaken an empirical characterization of "non-ideal" effects in the doped semiconductor thermometers used with these detectors, which operate at temperatures near 50 mK. We have found three apparently independent categories of such behavior that are apparently intrinsic properties of the variable-range hopping conduction mechanism in these devices: 1/f fluctuations in the resistance, which seems to be a 2D effect; a departure from the ideal coulomb-gap temperature dependence of the resistance at temperatures below T(0)/24; and an electrical nonlinearity that has the time dependence and extra noise that are quantitatively predicted by a simple hot electron model. This work has been done largely with ion-implanted Si:P:B, but similar behaviors have been observed in transmutation doped germanium. C1 Univ Wisconsin, Dept Phys, Madison, WI 53706 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP McCammon, D (reprint author), Univ Wisconsin, Dept Phys, 1150 Univ Ave, Madison, WI 53706 USA. EM mccammon@wisp.physics.wisc.edu RI Porter, Frederick/D-3501-2012; Kelley, Richard/K-4474-2012 OI Porter, Frederick/0000-0002-6374-1119; NR 8 TC 29 Z9 29 U1 0 U2 3 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0370-1972 J9 PHYS STATUS SOLIDI B JI Phys. Status Solidi B-Basic Solid State Phys. PD MAR PY 2002 VL 230 IS 1 BP 197 EP 204 DI 10.1002/1521-3951(200203)230:1<197::AID-PSSB197>3.0.CO;2-8 PG 8 WC Physics, Condensed Matter SC Physics GA 533TK UT WOS:000174546200032 ER PT J AU Di Rienzi, J Drachman, RJ AF Di Rienzi, J Drachman, RJ TI Resonances in positronium hydride SO PHYSICAL REVIEW A LA English DT Article ID STATES; SCATTERING; HYDROGEN AB We reexamine the problem of calculating the positions and widths of the lowest-lying resonances in the Ps+H scattering system that consists of two electrons, one positron and one proton. The first of these resonances, for L=0, was found by the methods of complex rotation and stabilization, and later described as a Feshbach resonance lying close to a bound state in the closed-channel e(+)+H- system. Recently, results for the L=1 and 2 scattering states were published, and it was found, surprisingly, that there is a large shift in the positions of these resonances. In this paper we repeat the analysis for L=1 and find an unexpected explanation for the shift. C1 Coll Notre Dame Maryland, Baltimore, MD 21210 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Di Rienzi, J (reprint author), Coll Notre Dame Maryland, Baltimore, MD 21210 USA. NR 15 TC 14 Z9 14 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD MAR PY 2002 VL 65 IS 3 AR 032721 DI 10.1103/PhysRevA.65.032721 PN A PG 7 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 533UJ UT WOS:000174548500111 ER PT J AU Fursa, DV Bray, I Csanak, G Clark, REH Abdallah, J Kanik, I Trajmar, S AF Fursa, DV Bray, I Csanak, G Clark, REH Abdallah, J Kanik, I Trajmar, S TI Electron-impact excitation of excited atomic barium SO PHYSICAL REVIEW A LA English DT Article ID CROSS-SECTIONS; GROUND-STATE; VAPOR LASERS; COUPLED-CHANNELS; PLASMA CLOUDS; SCATTERING; IONIZATION; BA-138(; TRANSITION; MOMENTUM AB We present results of integral-excitation and total-ionization cross section calculations from the 6s6p P-1(1), 6s5d D-1(2), 6s6p P-3(0,1,2), and 6s5d D-3(1,2,3) states of Ba. The unitarized first-order many-body theory and the close-coupling method were used to obtain the integrated cross sections, while the Born approximation was used to estimate the ionization cross sections. A comparison is given with the semiempirical estimates of excitation cross sections obtained from small-angle differential cross-section measurements. C1 Flinders Univ S Australia, Elect Struct Mat Ctr, Adelaide, SA 5001, Australia. Murdoch Univ, Sch Math & Phys Sci, Ctr Atom Mol & Surface Phys, Perth, WA 6150, Australia. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Fursa, DV (reprint author), Flinders Univ S Australia, Elect Struct Mat Ctr, GPO Box 2100, Adelaide, SA 5001, Australia. RI Fursa, Dmitry/C-2301-2009; Bray, Igor/B-8586-2009 OI Fursa, Dmitry/0000-0002-3951-9016; Bray, Igor/0000-0001-7554-8044 NR 31 TC 1 Z9 1 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD MAR PY 2002 VL 65 IS 3 AR 032723 DI 10.1103/PhysRevA.65.032723 PN A PG 7 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 533UJ UT WOS:000174548500113 ER PT J AU Lee, H Kok, P Cerf, NJ Dowling, JP AF Lee, H Kok, P Cerf, NJ Dowling, JP TI Linear optics and projective measurements alone suffice to create large-photon-number path entanglement SO PHYSICAL REVIEW A LA English DT Article ID QUANTUM AB We propose a method for preparing maximal path entanglement with a definite photon-number N, larger than two, using projective measurements. In contrast with the previously known schemes, our method uses only linear optics. Specifically, we exhibit a way of generating four-photon, path-entangled states of the form \4,0] + \0,4], using only four beam splitters and two detectors. These states are of major interest as a resource for quantum interferometric sensors as well as for optical quantum lithography and quantum holography. C1 CALTECH, Jet Prop Lab, Explorat Syst Auton, Quantum Comp Technol Grp,Sect 367, Pasadena, CA 91109 USA. Free Univ Brussels, Ecole Polytech, B-1050 Brussels, Belgium. RP CALTECH, Jet Prop Lab, Explorat Syst Auton, Quantum Comp Technol Grp,Sect 367, MS 126-347,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Kok, Pieter/B-1658-2010; DOWLING, JONATHAN/L-2749-2013 NR 22 TC 100 Z9 99 U1 0 U2 6 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9926 EI 2469-9934 J9 PHYS REV A JI Phys. Rev. A PD MAR PY 2002 VL 65 IS 3 AR 030101 DI 10.1103/PhysRevA.65.030101 PN A PG 4 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 533UJ UT WOS:000174548500001 ER PT J AU Somoza, A Petkov, MP Lynn, KG Dupasquier, A AF Somoza, A Petkov, MP Lynn, KG Dupasquier, A TI Stability of vacancies during solute clustering in Al-Cu-based alloys SO PHYSICAL REVIEW B LA English DT Article ID POSITRON-ANNIHILATION; AGING KINETICS; MG ALLOY; METALS; ZONES; PHASE AB A direct comparison between Al-Cu and Al-Cu-Mg alloys shows that the mechanism, by which Mg affects the microstructure and the aging kinetics of the alloys, is related to the formation of vacancy-Cu-Mg complexes that act as embryos for the nucleation of coherent solute clusters. The presence of Mg stabilizes the vacancies in the Guinier-Preston (GP) zones. Experimental evidence of the association of the vacancies with the solute atoms was obtained by Doppler-broadening spectroscopy of the positron annihilation radiation using two Ge detectors in coincidence. The evolution of the average content of Cu in the proximity of the vacancies was monitored at different stages of aging at temperatures below the solvus of GP zones, after the solution heat treatment of the alloy. C1 Politecn Milan, Ist Nazl Fis Mat, I-20133 Milan, Italy. Politecn Milan, Dipartimento Fis, I-20133 Milan, Italy. Washington State Univ, Dept Phys, Pullman, WA 99164 USA. Univ Nacl Ctr Prov Buenos Aires, IFIMAT, Tandil, Argentina. Comis Invest Cient Prov Buenos Aires, Tandil, Argentina. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Dupasquier, A (reprint author), Politecn Milan, Ist Nazl Fis Mat, Piazza L da Vinci 32, I-20133 Milan, Italy. NR 27 TC 63 Z9 63 U1 0 U2 13 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 J9 PHYS REV B JI Phys. Rev. B PD MAR 1 PY 2002 VL 65 IS 9 AR 094107 DI 10.1103/PhysRevB.65.094107 PG 6 WC Physics, Condensed Matter SC Physics GA 533UC UT WOS:000174547900044 ER PT J AU Albergo, S Bellwied, R Bennett, M Bonner, B Caines, H Christie, W Costa, S Crawford, HJ Cronqvist, M Debbe, R Engelage, J Greiner, L Hallman, T Hijazi, G Hoffmann, G Huang, HZ Humanic, TJ Insolia, A Jensen, P Judd, EG Kainz, K Kaplan, M Kelly, S Kotov, I Kunde, G Lindstrom, PJ Llope, W LoCurto, G Longacre, R Lynn, D Mahzeh, N Milosevich, Z Mitchell, JT Mitchell, JW Nehmeh, S Paganis, S Pandey, SU Potenza, R Russ, DE Saulys, A Schambach, J Sheen, J Sugarbaker, E Takahashi, J Tang, J Trattner, AL Trentalange, S Tricomi, A Tuve, C Whitfield, JP Wilson, K AF Albergo, S Bellwied, R Bennett, M Bonner, B Caines, H Christie, W Costa, S Crawford, HJ Cronqvist, M Debbe, R Engelage, J Greiner, L Hallman, T Hijazi, G Hoffmann, G Huang, HZ Humanic, TJ Insolia, A Jensen, P Judd, EG Kainz, K Kaplan, M Kelly, S Kotov, I Kunde, G Lindstrom, PJ Llope, W LoCurto, G Longacre, R Lynn, D Mahzeh, N Milosevich, Z Mitchell, JT Mitchell, JW Nehmeh, S Paganis, S Pandey, SU Potenza, R Russ, DE Saulys, A Schambach, J Sheen, J Sugarbaker, E Takahashi, J Tang, J Trattner, AL Trentalange, S Tricomi, A Tuve, C Whitfield, JP Wilson, K TI Light nuclei production in heavy-ion collisions at relativistic energies SO PHYSICAL REVIEW C LA English DT Article ID PLUS AU REACTIONS; TRANSVERSE-MOMENTUM; PARTICLE-PRODUCTION; AU+AU COLLISIONS; FLOW; GEV/C; COALESCENCE; EXPANSION; SPECTRA; PROTON AB We have measured the production of light nuclei (A less than or equal to 3) in 11.6 GeV/c Au-Au collisions at the Brookhaven Alternating Gradient Synchrotron (AGS). The transverse mass spectra are analyzed using a thermal fireball model, and the yields for different particle species are discussed assuming coalescence and fragmentation as possible production mechanisms. The wide acceptance range of the He-3 measurements permits a broad study of the coalescence parameter B-3 as functions of transverse momentum and rapidity. Comparisons with data obtained previously at AGS energies suggest that the simple models are insufficient to describe fully the production mechanisms of light nuclei. C1 Univ Catania, Catania, Italy. Brookhaven Natl Lab, Upton, NY 11973 USA. Univ Calif Los Angeles, Los Angeles, CA USA. Carnegie Mellon Univ, Pittsburgh, PA 15213 USA. Ist Nazl Fis Nucl, Sez Catania, I-95129 Catania, Italy. Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Ohio State Univ, Columbus, OH 43210 USA. Rice Univ, Houston, TX 77251 USA. Univ Calif Berkeley, Space Sci Labs, Berkeley, CA 94720 USA. Univ Texas, Austin, TX 78712 USA. Wayne State Univ, Detroit, MI USA. Yale Univ, New Haven, CT USA. RP Univ Catania, Catania, Italy. RI Takahashi, Jun/B-2946-2012; Insolia, Antonio/M-3447-2015; TUVE', Cristina/P-3933-2015 OI Takahashi, Jun/0000-0002-4091-1779; Insolia, Antonio/0000-0002-9040-1566; TUVE', Cristina/0000-0003-0739-3153 NR 38 TC 9 Z9 9 U1 0 U2 4 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9985 EI 2469-9993 J9 PHYS REV C JI Phys. Rev. C PD MAR PY 2002 VL 65 IS 3 AR 034907 DI 10.1103/PhysRevC.65.034907 PG 7 WC Physics, Nuclear SC Physics GA 533UF UT WOS:000174548200077 ER PT J AU Geso, M Azizi, A Amos, K Deb, PK Igo, G Jones, K Mclelland, JB Westen, G Whitney, R Whitten, C AF Geso, M Azizi, A Amos, K Deb, PK Igo, G Jones, K Mclelland, JB Westen, G Whitney, R Whitten, C TI Elastic scattering of polarized protons from He-3 at 800 MeV SO PHYSICAL REVIEW C LA English DT Article ID NUCLEON-NUCLEUS SCATTERING; MICROSCOPIC MODEL ANALYSES; BASIS SHELL-MODEL; DIVERSE MASS; NN; TARGETS AB Cross section, analyzing power, and spin transfer observables for p-He-3 elastic scattering have been obtained using an 800-MeV polarized proton beam at the Los Alamos Meson Physics Facility (LAMPF). The results are compared with theoretical predictions for these observables using nonlocal optical potentials defined by full folding a complex nucleon-nucleon (NN) effective interaction with a ground state He-3 wave function given by a large space, shell model nuclear structure calculation. The effective NN interaction has been derived from complex NN potentials that fit the (complex) NN scattering phase shifts at 800 MeV. C1 RMIT Univ, Dept Med Radiat Sci, Bundoora, Vic 3083, Australia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Melbourne, Sch Phys, Parkville, Vic 3010, Australia. Univ Calif Los Angeles, Dept Phys, Los Angeles, CA 90095 USA. Los Alamos Natl Lab, LANSCE 6, Los Alamos, NM 87545 USA. Los Alamos Natl Lab, PDO, Los Alamos, NM 87545 USA. Calif State Univ Hayward, Dept Phys, Hayward, CA 94542 USA. Thomas Jefferson Natl Accelarator Facil, Newport News, VA 23606 USA. RP RMIT Univ, Dept Med Radiat Sci, Bundoora, Vic 3083, Australia. NR 36 TC 2 Z9 2 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9985 EI 2469-9993 J9 PHYS REV C JI Phys. Rev. C PD MAR PY 2002 VL 65 IS 3 AR 034005 DI 10.1103/PhysRevC.65.034005 PG 6 WC Physics, Nuclear SC Physics GA 533UF UT WOS:000174548200016 ER PT J AU Qu, D Rame, E Garoff, S AF Qu, D Rame, E Garoff, S TI Dip-coated films of volatile liquids SO PHYSICS OF FLUIDS LA English DT Article ID CONTACT LINES; MAXIMUM SPEED; SURFACES; DYNAMICS; MENISCUS AB We examine experimentally the hydrodynamics of dip-coated, finite-length films of evaporative fluids, from the film tip through the film body all the way to the connection with the main meniscus. The characteristic film thickness has a power-law dependence on the withdrawing speed similar to that for the thickness of "infinite" films formed by nonvolatile liquids. The film length and cross-sectional area have power-law dependence on the withdrawing speed as well, but the prefactors of the power laws are controlled by the evaporation rate of the fluid. These power laws are consistent with the global mass balance over the film between mass lost by evaporation and mass input by the solid motion. We have also found that the apparent contact angle and the curvature at the film tip both have power-law dependencies on the withdrawing speed that are consistent with those found for the length and the film thickness. Film shape measurements near the film tip reach thicknesses similar to100 Angstrom from the solid; but we did not detect any influence of the inner scale hydrodynamics and van der Waals forces on this shape. We have developed a systematic method for measuring the contributions of gravity, capillary force, viscous force, and vapor recoil on the pressure and flow fields in the film. This exercise reveals detailed information about the flow in evaporative films. The combined effects of evaporation and Marangoni flow on the hydrodynamics are deduced from experimental data, independent of evaporation models. (C) 2002 American Institute of Physics. C1 Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. Carnegie Mellon Univ, Ctr Complex Fluids Engn, Pittsburgh, PA 15213 USA. NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, Cleveland, OH 44135 USA. RP Qu, D (reprint author), Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. RI Garoff, Stephen/P-7629-2014 OI Garoff, Stephen/0000-0001-8148-8535 NR 28 TC 32 Z9 32 U1 1 U2 20 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD MAR PY 2002 VL 14 IS 3 BP 1154 EP 1165 DI 10.1063/1.1449467 PG 12 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 521XM UT WOS:000173866700025 ER PT J AU Mahapatra, PR Benner, LAM Ostro, SJ Jurgens, RF Giorgini, JD Yeomans, DK Chandler, JF Shapiro, II AF Mahapatra, PR Benner, LAM Ostro, SJ Jurgens, RF Giorgini, JD Yeomans, DK Chandler, JF Shapiro, II TI Radar observations of asteroid 7335 (1989 JA) SO PLANETARY AND SPACE SCIENCE LA English DT Article DE asteroids; radar AB Radar observations of 1989 JA during its discovery apparition yielded dual-polarization echo spectra on two dates at Arecibo and three dates at Goldstone. The echoes indicate that this object has an effective diameter within a factor of two of 1 km, a rotation period less than half a day, and a surface that is fairly smooth at centimeter-to-meter scales. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Indian Inst Sci, Bangalore 560012, Karnataka, India. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Ostro, SJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD MAR PY 2002 VL 50 IS 3 BP 257 EP 260 AR PII S0032-0633(02)00002-8 DI 10.1016/S0032-0633(02)00002-8 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 547UD UT WOS:000175349800002 ER PT J AU Wang, K Bolton, SJ Gulkis, SM Levin, SM AF Wang, K Bolton, SJ Gulkis, SM Levin, SM TI Atmospheric loss of energetic electrons in the Jovian synchrotron zone SO PLANETARY AND SPACE SCIENCE LA English DT Article DE Jovian synchrotron radiation; drift shells; drift loss cones ID RADIAL DIFFUSION-MODELS; COMET SHOEMAKER-LEVY-9; MAGNETIC-FIELD; JUPITER; VARIABILITY AB For decades, ground-based radio observations of Jovian synchrotron radiation have shown emission originating predominantly from the equatorial region and from high-latitude regions (lobes) near L similar to 2.5. The observations show a longitudinally asymmetric gap between the emission peaks of the lobes and the atmosphere of Jupiter. One possible explanation for these gaps is the loss of electrons through collisions with atmospheric neutrals as the electrons bounce along magnetic field lines and drift longitudinally in the presence of asymmetric magnetic fields. To assess this hypothesis, we applied the recently developed O6 and VIP4 magnetic field models to calculate the trajectories of electrons as they drift longitudinally in Jupiter's magnetic field, and derive the sizes of their equatorial drift loss cones. We then identified the shells on which electrons would be lost due to collisions with the atmosphere. The calculated drift loss cone sizes could be applied in future to the modeling of electron distribution functions in this region and could also be applied to the study of Jovian auroral zone. This method also allowed us to compute the shell-splitting effects for these drifting electrons and we find the shell-splitting to be small (less than or equal to0.05R(J)). This justifies a recent modeling assumption that particles drift on the same shells in a three-dimensional distribution model of electrons. We also compared the computed gaps with the observed gaps, and found that the atmospheric loss mechanism alone is not able to sufficiently explain the observed gap asymmetry. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Natl Taiwan Univ, Dept Phys, Taipei, Taiwan. Natl Cheng Kung Univ, Dept Phys, Tainan 70101, Taiwan. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Wang, K (reprint author), Natl Taiwan Univ, Dept Phys, Taipei, Taiwan. OI Wang, Kaiti/0000-0003-2165-5922 NR 24 TC 18 Z9 18 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD MAR PY 2002 VL 50 IS 3 BP 277 EP 285 AR PII S0032-0633(01)00129-5 DI 10.1016/S0032-0633(01)00129-5 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 547UD UT WOS:000175349800005 ER PT J AU Clarke, AH AF Clarke, AH TI Understanding sustainable development in the context of other emergent environmental perspectives SO POLICY SCIENCES LA English DT Article AB Concepts of preservation, conservation, and development shaped in large part the debate about U.S. environmental policy at the end of the 19th century. Forest use was often the focal point of controversy. Throughout the 20th century, Americans continued debating forest use, but by the late 20th century, the assumption that 19th century beliefs prevailed had begun to create a barrier to understanding changing perspectives. This paper begins by discussing one of these new perspectives, sustainable development, which has gained international prominence since the 1992 United Nations Conference on Environment and Development after being mentioned in the 1986 World Commission on Environment and Development's Our Common Future. Following the introduction to sustainable development, this paper briefly presents the results of a 1989 study using Q methodology, which identified the emergence of sustainable development as one of several beliefs in a more complex framework of perspectives on forest use than had been assumed. In addition to sustainable development, this new framework included beliefs in nature as a community to be respected, a place for personal growth, a means for demonstrating self-reliance, and a rallying point for grassroots activism. This paper examines sustainable development in the context of these other belief types and concludes by cautioning policymakers to consider these additional policy arguments and define the policy agenda more fully. C1 NASA, Washington, DC 20546 USA. RP Clarke, AH (reprint author), NASA, 300 E St SW, Washington, DC 20546 USA. NR 56 TC 23 Z9 23 U1 1 U2 5 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0032-2687 J9 POLICY SCI JI Policy Sci. PD MAR PY 2002 VL 35 IS 1 BP 69 EP 90 DI 10.1023/A:1016067819764 PG 22 WC Planning & Development; Public Administration; Social Sciences, Interdisciplinary SC Public Administration; Social Sciences - Other Topics GA 567BP UT WOS:000176463000004 ER PT J AU Anderson, MS Pike, WT AF Anderson, MS Pike, WT TI A Raman-atomic force microscope for apertureless-near-field spectroscopy and optical trapping SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID SINGLE MOLECULES; SURFACE; MANIPULATION; SCATTERING; TIPS; SENSITIVITY; RESOLUTION; NEARFIELD; PROBES; LIMIT AB An instrument that combines the analytical power of Raman spectroscopy with the spatial resolution of the Atomic Force Microscope (AFM) is presented. This instrument is capable of resolving 50 nm scale spectral features or better by using surface enhanced Raman scattering at the AFM tip. The localized spectrochemical information allows the interpretation of the concurrently acquired friction or phase contrast AFM images. This instrument has a unique combination of features including side illumination of the tip-sample interface that permits opaque samples. As a result of precise focusing of a laser at the AFM tip-sample interface this instrument is also capable of laser beam profiling and studying optical trapping at the probe tip. Applications of this versatile instrument include chemical analysis of nanometer scale phenomena, chemical separation, and the potential for targeted single molecule spectroscopy. (C) 2002 American Institute of Physics. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Anderson, MS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 125-109, Pasadena, CA 91109 USA. NR 38 TC 60 Z9 61 U1 3 U2 18 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD MAR PY 2002 VL 73 IS 3 BP 1198 EP 1203 DI 10.1063/1.1445864 PN 1 PG 6 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 527JJ UT WOS:000174182700019 ER PT J AU Burns, JA Squyres, SW A'Hearn, M Barker, E Belton, M Binzel, R Chapman, C Cuzzi, J Drake, M Esposito, L Feldman, P Greeley, R Hartmann, W Head, J Huntress, W Ingersoll, A Johnson, T Lunine, J McKinnon, W Millis, R Nelson, R Owen, T Pieters, C Stern, SA Wood, J AF Burns, JA Squyres, SW A'Hearn, M Barker, E Belton, M Binzel, R Chapman, C Cuzzi, J Drake, M Esposito, L Feldman, P Greeley, R Hartmann, W Head, J Huntress, W Ingersoll, A Johnson, T Lunine, J McKinnon, W Millis, R Nelson, R Owen, T Pieters, C Stern, SA Wood, J TI Healthy discussion of planetary science goals SO SCIENCE LA English DT Letter C1 Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. Univ Maryland, College Pk, MD 20742 USA. MIT, Cambridge, MA 02139 USA. SW Res Inst, San Antonio, TX USA. NASA Ames, Moffett Field, CA USA. Univ Arizona, Tucson, AZ 85721 USA. Univ Colorado, Boulder, CO 80309 USA. Johns Hopkins Univ, Baltimore, MD 21218 USA. Arizona State Univ, Tempe, AZ 85287 USA. Brown Univ, Providence, RI 02912 USA. Carnegie Inst, Washington, DC USA. CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. Washington Univ, St Louis, MO 63130 USA. Lowell Observ, Flagstaff, AZ 86001 USA. Univ Hawaii, Honolulu, HI 96822 USA. Harvard Univ, Cambridge, MA 02138 USA. Amer Astron Soc, Div Planetary Sci, Washington, DC USA. NRC Comm Planetary & Lunar Explorat, Rockville, MD USA. Amer Geophys Union, Planetary Sci Sect, Washington, DC USA. RP Burns, JA (reprint author), Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. NR 0 TC 0 Z9 0 U1 0 U2 19 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 MAR 1 PY 2002 VL 295 IS 5560 BP 1644 EP 1644 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 527XH UT WOS:000174212900021 PM 11881633 ER PT J AU Koide, S Shibata, K Kudoh, T Meier, DL AF Koide, S Shibata, K Kudoh, T Meier, DL TI Extraction of black hole rotational energy by a magnetic field and the formation of relativistic jets SO SCIENCE LA English DT Article ID ANGULAR-MOMENTUM TRANSPORT; ACCRETION DISKS; RADIO JETS; SIMULATIONS; DRIVEN; FLOWS; MAGNETOSPHERE; MODEL AB Using numerical simulations, we modeled the general relativistic magnetohydrodynamic behavior of a plasma flowing into a rapidly rotating black hole in a large-scale magnetic field. The results show that a torsional Atfven wave is generated by the rotational dragging of space near the black hole. The wave transports energy along the magnetic field tines outward, causing the total energy of the plasma near the hole to decrease to negative values. When this negative energy plasma enters the horizon, the rotational energy of the black hole decreases. Through this process, the energy of the spinning black hole is extracted magnetically. C1 Toyama Univ, Fac Engn, Toyama 9308555, Japan. Kyoto Univ, Kwasan & Hida Observ, Kyoto 6078471, Japan. Natl Astron Observ, Tokyo 1818588, Japan. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Koide, S (reprint author), Toyama Univ, Fac Engn, Toyama 9308555, Japan. NR 26 TC 136 Z9 137 U1 2 U2 6 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 MAR 1 PY 2002 VL 295 IS 5560 BP 1688 EP 1691 DI 10.1126/science.1068240 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 527XH UT WOS:000174212900039 PM 11809939 ER PT J AU Sutter, B Taylor, RE Hossner, LR Ming, DW AF Sutter, B Taylor, RE Hossner, LR Ming, DW TI Solid state "phosphorus nuclear magnetic resonance of iron-, manganese-, and copper-containing synthetic hydroxyapatites SO SOIL SCIENCE SOCIETY OF AMERICA JOURNAL LA English DT Article ID SPIN-LATTICE RELAXATION; MAS NMR; PHOSPHATE; AL-27; KAOLINITE; SI-29; SPECTROSCOPY; GROWTH; PHASES; WHEAT AB The incorporation of mironutrients into synthetic hydroxyapatite (SHA) is proposed for slow release of these nutrients to crops in the National Aeronautics and Space Administration's (NASA's) Advanced Life Support (ALS) program for Lunar or Martian outposts. Solid state P-31 nuclear magnetic resonance (NMR) was utilized to examine the paramagnetic effects of Fe3+, Mn2+, and Cu2+ to determine if they were incorporated into the SHA structure. Separate Fe3+, Mn2+, and Cu2+ containing SHA materials along with a transition metal free SHA (pure-SHA) were synthesized using a precipitation method. The proximity (<1 nm) of the transition metals to the P-31 nuclei of SHA were apparent when comparing the integrated P-31 signal intensities of the pure-SHA (87 arbitrary units g(-1)) with the Fe-, Mn-, and Cu-SHA materials (37-71 arbitrary units g(-1)). The lower integrated P-31 signal intensities of the Fe-, Mn-, and Cu-SHA materials relative to the pure-SHA suggested that Fe3+, Mn2+, and Cu2+ were incorporated in the SHA structure. Further support for Fe3+, Mn2+, and Cu2+ incorporation was demonstrated by the reduced spin-lattice relaxation constants of the Fe-, Mn-, and Cu-SHA materials (T' 0.075-0.434 s) relative to pure-SHA (T-1 = 58.4 s). Inversion recovery spectra indicated that Fe3+, Mn2+, and Cu2+ were not homogeneously distributed about the P-31 nuclei in the SHA structure. Extraction with diethylenetriamine-penta-acetic acid (DTPA) suggested that between 50 and 80% of the total starting metal concentrations were incorporated in the SHA structure. Iron-, Mn-, and Cu-containing SHA are potential slow release sources of Fe, Mn, and Cu in the ALS cropping system. C1 NASA, Ames Res Ctr, Natl Res Council, Moffett Field, CA 94035 USA. Texas A&M Univ, Dept Chem, College Stn, TX 77843 USA. Texas A&M Univ, Dept Soil & Crop Sci, College Stn, TX 77843 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Sutter, B (reprint author), NASA, Ames Res Ctr, Natl Res Council, Moffett Field, CA 94035 USA. NR 28 TC 22 Z9 22 U1 1 U2 11 PU SOIL SCI SOC AMER PI MADISON PA 677 SOUTH SEGOE ROAD, MADISON, WI 53711 USA SN 0361-5995 J9 SOIL SCI SOC AM J JI Soil Sci. Soc. Am. J. PD MAR-APR PY 2002 VL 66 IS 2 BP 455 EP 463 PG 9 WC Soil Science SC Agriculture GA 528ZF UT WOS:000174275000016 PM 12088032 ER PT J AU Swap, RJ Annegarn, HJ Suttles, JT Haywood, J Helmlinger, MC Hely, C Hobbs, PV Holben, BN Ji, J King, MD Landmann, T Maenhaut, W Otter, L Pak, B Piketh, SJ Platnick, S Privette, J Roy, D Thompson, AM Ward, D Yokelson, R AF Swap, RJ Annegarn, HJ Suttles, JT Haywood, J Helmlinger, MC Hely, C Hobbs, PV Holben, BN Ji, J King, MD Landmann, T Maenhaut, W Otter, L Pak, B Piketh, SJ Platnick, S Privette, J Roy, D Thompson, AM Ward, D Yokelson, R TI The Southern African Regional Science Initiative (SAFARI 2000): overview of the dry season field campaign SO SOUTH AFRICAN JOURNAL OF SCIENCE LA English DT Article ID TROPICAL TROPOSPHERIC OZONE; MODIS AB The Southern African Regional Science Initiative (SAFARI 2000) is an international science project investigating the earth-atmosphere-human system in southern Africa. The programme was conducted over a two-year period from March 1999 to March 2001. The dry season field campaign (August-September 2000) was the most intensive activity and involved over 200 scientists from eighteen countries. The main objectives were to characterize and quantify biogenic, pyrogenic and anthropogenic aerosol and trace gas emissions and their transport and transformations in the atmosphere, and to validate NASA's Earth Observing System's satellite Terra within a scientific context. Five aircraft - two South African Weather Service Aerocommanders, the University of Washington's CV-580, the U.K. Meteorological Office's C-130, and NASA's ER-2-with different altitude capabilities, participated in the campaign. Additional airborne sampling of southern African air masses, that had moved downwind of the subcontinent, was conducted by the CSIRO over Australia. Multiple observations were made in various geographical sectors under different synoptic conditions. Airborne missions were designed to optimize the value of synchronous over-flights of the Terra satellite platform, above regional ground validation and science targets. Numerous smaller-scale ground validation activities took place throughout the subcontinent during the campaign period. C1 Univ Virginia, Dept Environm Sci, Charlottesville, VA 22903 USA. Univ Witwatersrand, Atmosphere & Energy Res Grp, Johannesburg, South Africa. Raytheon Co, Lexington, MA 02041 USA. United Kingdom Meteorol Off, Bracknell, Berks, England. NASA, Jet Prop Lab, Pasadena, CA USA. Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Gottingen, Dept Landscape Ecol, Inst Geog, D-3400 Gottingen, Germany. State Univ Ghent, B-9000 Ghent, Belgium. Univ Witwatersrand, Climatol Res Grp, Johannesburg, South Africa. Univ Calif Irvine, Irvine, CA USA. Univ Montana, Missoula, MT 59812 USA. RP Annegarn, HJ (reprint author), Univ Witwatersrand, Atmosphere & Energy Res Grp, Private Bag 3, ZA-2050 Wits, South Africa. RI Annegarn, Harold/A-9127-2008; King, Michael/C-7153-2011; Privette, Jeffrey/G-7807-2011; Yokelson, Robert/C-9971-2011; Maenhaut, Willy/M-3091-2013; Platnick, Steven/J-9982-2014; Pak, Bernard/F-4326-2015; Thompson, Anne /C-3649-2014 OI Annegarn, Harold/0000-0001-6653-4679; King, Michael/0000-0003-2645-7298; Privette, Jeffrey/0000-0001-8267-9894; Yokelson, Robert/0000-0002-8415-6808; Maenhaut, Willy/0000-0002-4715-4627; Platnick, Steven/0000-0003-3964-3567; Pak, Bernard/0000-0002-2137-8171; Thompson, Anne /0000-0002-7829-0920 NR 16 TC 72 Z9 72 U1 0 U2 3 PU ACAD SCIENCE SOUTH AFRICA A S S AF PI LYNWOOD RIDGE PA PO BOX 72135, LYNWOOD RIDGE 0040, SOUTH AFRICA SN 0038-2353 J9 S AFR J SCI JI S. Afr. J. Sci. PD MAR-APR PY 2002 VL 98 IS 3-4 BP 125 EP 130 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 566NW UT WOS:000176435700007 ER PT J AU Otter, LB Scholes, RJ Dowty, P Privette, J Caylor, K Ringrose, S Mukelabai, M Frost, P Hanan, N Totolo, O Veenendaal, EM AF Otter, LB Scholes, RJ Dowty, P Privette, J Caylor, K Ringrose, S Mukelabai, M Frost, P Hanan, N Totolo, O Veenendaal, EM TI The Southern African Regional Science Initiative (SAFARI 2000): wet season campaigns SO SOUTH AFRICAN JOURNAL OF SCIENCE LA English DT Article ID EMISSIONS AB The Southern African Regional Science Initiative (SAFARI 2000) involved two wet season and one dry season field campaigns. This paper reports on the wet season campaigns. The first was conducted at five sites along the Kalahari Transect in Zambia (Kataba Forest) and Botswana (Pandamatenga, Maun, Okwa River Crossing, Tshane) during February 2000 and concentrated primarily on characterizing the land surface with respect to exchanges of matter and energy with the atmosphere. The second, conducted in February 2001, focused on fluxes of water, gases and energy between the canopy and the atmosphere at Maun, Botswana, and at Skukuza in the Kruger National Park, South Africa. Eddy covariance measurements at Skukuza and Maun were designed to collect a near-continuous record of the seasonality and inter-annual variability in savanna carbon, water and energy exchanges in representative savanna ecosystems. This paper gives brief descriptions of the sites, the measurements made, and the methods used. It highlights some preliminary results, particularly from the first campaign, and outlines the next stages of the SAFARI 2000 project. C1 Univ Witwatersrand, Climatol Res Grp, ZA-2050 Wits, South Africa. CSIR, Div Water Environm & Forestry Technol, ZA-0001 Pretoria, South Africa. Univ Virginia, Global Environm Change Program, Charlottesville, VA USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Botswana, Harry Oppenheimer Okavango Res Ctr, Maun, Botswana. Zambian Meteorol Dept, Mongu, Zambia. Univ Zimbabwe, Inst Environm Studies, Harare, Zimbabwe. Colorado State Univ, Nat Resource Ecol Lab, Ft Collins, CO 80523 USA. Univ Botswana, Dept Environm Sci, Gaborone, Botswana. RP Otter, LB (reprint author), Univ Witwatersrand, Climatol Res Grp, Private Bag 3, ZA-2050 Wits, South Africa. RI Caylor, Kelly/B-7734-2008; Privette, Jeffrey/G-7807-2011; Veenendaal, Elmar/B-4628-2009; OI Caylor, Kelly/0000-0002-6466-6448; Privette, Jeffrey/0000-0001-8267-9894; Scholes, Robert/0000-0001-5537-6935; Hanan, Niall/0000-0002-9130-5306 NR 24 TC 30 Z9 30 U1 0 U2 0 PU ACAD SCIENCE SOUTH AFRICA A S S AF PI LYNWOOD RIDGE PA PO BOX 72135, LYNWOOD RIDGE 0040, SOUTH AFRICA SN 0038-2353 J9 S AFR J SCI JI S. Afr. J. Sci. PD MAR-APR PY 2002 VL 98 IS 3-4 BP 131 EP 137 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 566NW UT WOS:000176435700008 ER PT J AU Schwenke, DW AF Schwenke, DW TI Towards accurate ab initio predictions of the vibrational spectrum of methane SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article DE methane; vibrational spectrum; Born-Oppenheimer approximation ID BORN-OPPENHEIMER APPROXIMATION; BASIS-SET CONVERGENCE; TRIATOMIC-MOLECULES; ENERGY-LEVELS; H2O AB We have carried out extensive ab initio calculations of the electronic structure of methane, and these results are used to compute vibrational energy levels. We include basis set extrapolations, core-valence correlation, relativistic effects, and Born-Oppenheimer breakdown terms in our calculations. Our ab initio predictions of the lowest lying levels are superb. (C) 2002 Published by Elsevier Science B.V. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Schwenke, DW (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. EM schwenke@pegasus.arc.nasa.gov RI schwenke, david/I-3564-2013 NR 27 TC 90 Z9 93 U1 2 U2 9 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1386-1425 J9 SPECTROCHIM ACTA A JI Spectroc. Acta Pt. A-Molec. Biomolec. Spectr. PD MAR 1 PY 2002 VL 58 IS 4 SI SI BP 849 EP 861 AR PII S1386-1425(01)00673-4 DI 10.1016/S1386-1425(01)00673-4 PG 13 WC Spectroscopy SC Spectroscopy GA 529NJ UT WOS:000174305300015 PM 11991499 ER PT J AU Chaban, GM Gerber, RB AF Chaban, GM Gerber, RB TI Ab initio calculations of anharmonic vibrational spectroscopy for hydrogen fluoride (HF)(n) (n=3, 4) and mixed hydrogen fluoride/water (HF)(n)(H(2)O)(n) (n=1, 2, 4) clusters SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article DE hydrogen fluoride; anharmonic vibrational spectroscopy; potential energy surface ID DENSITY-FUNCTIONAL THEORY; MOLLER-PLESSET; WAVE-FUNCTIONS; BASIS-SETS; STATES; HF; COMBINATION; COMPLEXES; SYSTEMS; BPTI AB Anharmonic vibrational frequencies and intensities are computed for hydrogen fluoride clusters (HF)(n) with n = 3, 4 and mixed clusters of hydrogen fluoride with water (HF)(n)(H(2)O)(n) where n = 1, 2. For the (HF)(4)(H(2)O)(4) complex, the vibrational spectra are calculated at the harmonic level, and anharmonic effects are estimated. Potential energy surfaces for these systems are obtained at the MP2/TZP level of electronic structure theory. Vibrational states are calculated from the potential surface points using the correlation-corrected vibrational self-consistent field method. The method accounts for the anharmonicities and couplings between all vibrational modes and provides fairly accurate anharmonic vibrational spectra that can be directly compared with experimental results without a need for empirical scaling. For (HF)(n), good agreement is found with experimental data. This agreement shows that the Moller-Plesset (MP2) potential surfaces for these systems are reasonably reliable. The accuracy is best for the stiff intramolecular modes, which indicates the validity of MP2 in describing coupling between intramolecular and intermolecular degrees of freedom. For (HF)(n)(H(2)O)(n) experimental results are unavailable. The computed intramolecular frequencies show a strong dependence on cluster size. Intensity features are predicted for future experiments. Published by Elsevier Science B.V. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA. Hebrew Univ Jerusalem, Dept Phys Chem, IL-91904 Jerusalem, Israel. Hebrew Univ Jerusalem, Fritz Haber Res Ctr, IL-91904 Jerusalem, Israel. RP Chaban, GM (reprint author), NASA, Ames Res Ctr, Mail Stop T27B-1, Moffett Field, CA 94035 USA. EM chaban@pegasus.arc.nasa.gov NR 32 TC 42 Z9 42 U1 0 U2 7 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1386-1425 J9 SPECTROCHIM ACTA A JI Spectroc. Acta Pt. A-Molec. Biomolec. Spectr. PD MAR 1 PY 2002 VL 58 IS 4 SI SI BP 887 EP 898 AR PII S1386-1425(01)00676-X DI 10.1016/S1386-1425(01)00676-X PG 12 WC Spectroscopy SC Spectroscopy GA 529NJ UT WOS:000174305300018 PM 11991501 ER PT J AU Giauque, PH Cherry, HB Nicolet, MA Bernard, C Pisch, A AF Giauque, PH Cherry, HB Nicolet, MA Bernard, C Pisch, A TI Annealing of amorphous Ir18Si15O67 films in dry oxygen SO THIN SOLID FILMS LA English DT Article DE amorphous materials; oxidation; oxides; sputtering ID SEMICONDUCTOR AB X-ray-amorphous films 210 nm thick of Ir18Si15O67 were deposited by reactive sputtering of a target of iridium and silicon on substrates of oxidized silicon wafers, and subsequently annealed for I h at 700 degreesC in dry oxygen at pressures of 0.2, 8.0 or 760 torr. Regardless of oxygen pressure the films' composition is preserved, their microstructure changes little, and their resistivity drops only slightly from similar to1.9 to similar to1.7 mOmegacm. These films resemble those of Ru20Si14O65 and of TM-Si-N (TM=early transition metal) in the thermal stability of their amorphous structure, but Ir18Si15O67 films differ sharply from all others by their high chemical inertness against dry oxygen. (C) 2002 Elsevier Science B.V. All rights reserved. C1 CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. ENSEEG, INPG, LTPCM, F-38402 St Martin Dheres, France. RP Nicolet, MA (reprint author), CALTECH, Pasadena, CA 91125 USA. NR 5 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0040-6090 J9 THIN SOLID FILMS JI Thin Solid Films PD MAR 1 PY 2002 VL 406 IS 1-2 BP 299 EP 301 AR PII S0040-6090(01)01789-8 DI 10.1016/S0040-6090(01)01789-8 PG 3 WC Materials Science, Multidisciplinary; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA 552GG UT WOS:000175610800045 ER PT J AU Pohorille, A Deamer, D AF Pohorille, A Deamer, D TI Artificial cells: prospects for biotechnology SO TRENDS IN BIOTECHNOLOGY LA English DT Review ID INFLUENZA-A VIRUS; ION SELECTIVITY; LIPOSOMES; MEMBRANE; VESICLES; CHANNEL; PEPTIDES; SYNTHASE; VOLUME; DESIGN AB A variety of techniques can now be used to alter the genome of a cell. Although these techniques are very powerful, they have limitations related to cost and efficiency of scale. Artificial cells designed for specific applications combine properties of biological systems such as nanoscale efficiency, self-organization and adaptability at relatively low cost. Individual components needed for such structures have already been developed, and now the main challenge is to integrate them in functional microscopic compartments. It will then become possible to design and construct communities of artificial cells that can perform different tasks related to therapeutic and diagnostic applications. C1 NASA, Ames Res Ctr, Exobiol Branch, Moffett Field, CA 94035 USA. Univ Calif Santa Cruz, Dept Chem, Santa Cruz, CA 95064 USA. RP Pohorille, A (reprint author), NASA, Ames Res Ctr, Exobiol Branch, MS 239-4, Moffett Field, CA 94035 USA. NR 39 TC 146 Z9 151 U1 9 U2 41 PU ELSEVIER SCIENCE LONDON PI LONDON PA 84 THEOBALDS RD, LONDON WC1X 8RR, ENGLAND SN 0167-7799 J9 TRENDS BIOTECHNOL JI Trends Biotechnol. PD MAR PY 2002 VL 20 IS 3 BP 123 EP 128 DI 10.1016/S0167-7799(02)01909-1 PG 6 WC Biotechnology & Applied Microbiology SC Biotechnology & Applied Microbiology GA 522TV UT WOS:000173913800010 PM 11841864 ER PT J AU Geiger, CL Ruiz, NE Clausen, CA Reinhart, DR Quinn, JW AF Geiger, CL Ruiz, NE Clausen, CA Reinhart, DR Quinn, JW TI Ultrasound pretreatment of elemental iron: kinetic studies of dehalogenation reaction enhancement and surface effects SO WATER RESEARCH LA English DT Article DE trichloroethylene; iron; ultrasound; groundwater remediation ID ZERO-VALENT IRON; AQUEOUS-SOLUTION; TRICHLOROETHYLENE; DEGRADATION; METALS AB This work presents data showing the kinetic improvement afforded by ultrasound pretreatment and illustrates the physical and chemical changes that take place at the iron surface. First-order rate constants improved as much as 78% with 2h of ultrasound pretreatment. Scanning electron microscopy (SEM) and surface area analysis were used for confirmation of the physical changes that take place after ultrasound was used on iron surfaces exposed to a variety of conditions. X-ray photoelectron spectroscopy was used to determine chemical surface characteristics before and after ultrasound use. SEM and surface area analysis showed that ultrasound use clears the iron surface of debris increasing the surface area up to 169%. In addition, exposure to ultrasound alters ratios of surface species, such as adventitious carbon to carbonyl carbon and iron to oxygen, and removed hydroxides thus making the iron more reactive to reductive dehalogenation. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Univ Cent Florida, Dept Chem, Orlando, FL 32816 USA. Univ Cent Florida, Dept Civil & Environm Engn, Orlando, FL 32816 USA. NASA, Kennedy Space Ctr, FL 32800 USA. RP Geiger, CL (reprint author), Univ Cent Florida, Dept Chem, Orlando, FL 32816 USA. NR 28 TC 19 Z9 22 U1 1 U2 12 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0043-1354 J9 WATER RES JI Water Res. PD MAR PY 2002 VL 36 IS 5 BP 1342 EP 1350 AR PII S0043-1354(01)00319-0 DI 10.1016/S0043-1354(01)00319-0 PG 9 WC Engineering, Environmental; Environmental Sciences; Water Resources SC Engineering; Environmental Sciences & Ecology; Water Resources GA 525JZ UT WOS:000174067800024 PM 11902789 ER PT J AU Gurnett, DA Kurth, WS Hospodarsky, GB Persoon, AM Zarka, P Lecacheux, A Bolton, SJ Desch, MD Farrell, WM Kaiser, ML Ladreiter, HP Rucker, HO Galopeau, P Louarn, P Young, DT Pryor, WR Dougherty, MK AF Gurnett, DA Kurth, WS Hospodarsky, GB Persoon, AM Zarka, P Lecacheux, A Bolton, SJ Desch, MD Farrell, WM Kaiser, ML Ladreiter, HP Rucker, HO Galopeau, P Louarn, P Young, DT Pryor, WR Dougherty, MK TI Control of Jupiter's radio emission and aurorae by the solar wind SO NATURE LA English DT Article ID KILOMETRIC RADIATION AB Radio emissions from Jupiter provided the first evidence that this giant planet has a strong magnetic field(1,2) and a large magnetosphere(3). Jupiter also has polar aurorae(4), which are similar in many respects to Earth's aurorae(5). The radio emissions are believed to be generated along the high-latitude magnetic field lines by the same electrons that produce the aurorae, and both the radio emission in the hectometric frequency range and the aurorae vary considerably(6,7). The origin of the variability, however, has been poorly understood. Here we report simultaneous observations using the Cassini and Galileo spacecraft of hectometric radio emissions and extreme ultraviolet auroral emissions from Jupiter. Our results show that both of these emissions are triggered by interplanetary shocks propagating outward from the Sun. When such a shock arrives at Jupiter, it seems to cause a major compression and reconfiguration of the magnetosphere, which produces strong electric fields and therefore electron acceleration along the auroral field lines, similar to the processes that occur during geomagnetic storms at the Earth. C1 Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. Observ Paris, Space Res Dept, F-92195 Meudon, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria. Univ Versailles, CETP, F-78140 Velizy Villacoublay, France. CNRS, Ctr Etud Spatiale Rayonnements, F-31028 Toulouse, France. Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80303 USA. Univ London Imperial Coll Sci & Technol, Blackett Lab, London SW7 2BZ, England. RP Gurnett, DA (reprint author), Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. RI Farrell, William/I-4865-2013; OI Hospodarsky, George/0000-0001-9200-9878; Kurth, William/0000-0002-5471-6202 NR 29 TC 89 Z9 90 U1 0 U2 4 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 28 PY 2002 VL 415 IS 6875 BP 985 EP 987 DI 10.1038/415985a PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 525MF UT WOS:000174075000032 PM 11875556 ER PT J AU Bolton, SJ Janssen, M Thorne, R Levin, S Klein, M Gulkis, S Bastian, T Sault, R Elachi, C Hofstadter, M Bunker, A Dulk, G Gudim, E Hamilton, G Johnson, WTK Leblanc, Y Liepack, O McLeod, R Roller, J Roth, L West, R AF Bolton, SJ Janssen, M Thorne, R Levin, S Klein, M Gulkis, S Bastian, T Sault, R Elachi, C Hofstadter, M Bunker, A Dulk, G Gudim, E Hamilton, G Johnson, WTK Leblanc, Y Liepack, O McLeod, R Roller, J Roth, L West, R TI Ultra-relativistic electrons in Jupiter's radiation belts SO NATURE LA English DT Article ID SYNCHROTRON-RADIATION; CHARGED-PARTICLES; MAGNETOSPHERE; ENERGIZATION; DIFFUSION; SIMULATION AB Ground-based observations have shown that Jupiter is a two-component source of microwave radio emission(1): thermal atmospheric emission and synchrotron emission(2) from energetic electrons spiralling in Jupiter's magnetic field. Later in situ measurements(3,4) confirmed the existence of Jupiter's high-energy electron-radiation belts, with evidence for electrons at energies up to 20 MeV. Although most radiation belt models predict electrons at higher energies(5,6), adiabatic diffusion theory can account only for energies up to around 20 MeV. Unambiguous evidence for more energetic electrons is lacking. Here we report observations of 13.8 GHz synchrotron emission that confirm the presence of electrons with energies up to 50 MeV; the data were collected during the Cassini fly-by of Jupiter. These energetic electrons may be repeatedly accelerated through an interaction with plasma waves, which can transfer energy into the electrons. Preliminary comparison of our data with model results suggests that electrons with energies of less than 20 MeV are more numerous than previously believed. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90024 USA. Natl Radio Astron Observ, Charlottesville, VA 24944 USA. Australia Telescope Natl Facil, Epping, NSW 1710, Australia. Observ Paris, Dept Space Res, F-92195 Meudon, France. Lewis Ctr Educ Res, Apple Valley, CA 92307 USA. RP Bolton, SJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 25 TC 65 Z9 66 U1 3 U2 16 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 28 PY 2002 VL 415 IS 6875 BP 987 EP 991 DI 10.1038/415987a PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 525MF UT WOS:000174075000033 PM 11875557 ER PT J AU Kurth, WS Gurnett, DA Hospodarsky, GB Farrell, WM Roux, A Dougherty, MK Joy, SP Kivelson, MG Walker, RJ Crary, FJ Alexander, CJ AF Kurth, WS Gurnett, DA Hospodarsky, GB Farrell, WM Roux, A Dougherty, MK Joy, SP Kivelson, MG Walker, RJ Crary, FJ Alexander, CJ TI The dusk flank of Jupiter's magnetosphere SO NATURE LA English DT Article ID PLASMA-WAVE OBSERVATIONS; SOLAR-WIND; MAGNETOPAUSE; MAGNETOTAIL; VOYAGER-1 AB Limited single-spacecraft observations of Jupiter's magnetopause have been used to infer that the boundary moves inward or outward in response to variations in the dynamic pressure of the solar wind(1-8). At Earth, multiple-spacecraft observations have been implemented to understand the physics of how this motion occurs, because they can provide a snapshot of a transient event in progress. Here we present a set of nearly simultaneous two-point measurements of the jovian magnetopause at a time when the jovian magnetopause was in a state of transition from a relatively larger to a relatively smaller size in response to an increase in solar-wind pressure. The response of Jupiter's magnetopause is very similar to that of the Earth, confirming that the understanding built on studies of the Earth's magnetosphere is valid. The data also reveal evidence for a well-developed boundary layer just inside the magnetopause. C1 Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Versailles, CETP, F-78140 Velizy Villacoublay, France. Univ London Imperial Coll Sci & Technol, Blackett Lab, London SW7 2BZ, England. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA. Univ Michigan, Space Phys Res Lab, Ann Arbor, MI 48109 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kurth, WS (reprint author), Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. RI Kivelson, Margaret/I-9019-2012; Farrell, William/I-4865-2013; OI Kivelson, Margaret/0000-0003-3859-8581; Hospodarsky, George/0000-0001-9200-9878; Kurth, William/0000-0002-5471-6202 NR 26 TC 27 Z9 27 U1 0 U2 3 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 28 PY 2002 VL 415 IS 6875 BP 991 EP 994 DI 10.1038/415991a PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 525MF UT WOS:000174075000034 PM 11875558 ER PT J AU Krimigis, SM Mitchell, DG Hamilton, DC Dandouras, J Armstrong, TP Bolton, SJ Cheng, AF Gloeckler, G Hsieh, KC Keath, EP Krupp, N Lagg, A Lanzerotti, LJ Livi, S Mauk, BH McEntire, RW Roelof, EC Wilken, B Williams, DJ AF Krimigis, SM Mitchell, DG Hamilton, DC Dandouras, J Armstrong, TP Bolton, SJ Cheng, AF Gloeckler, G Hsieh, KC Keath, EP Krupp, N Lagg, A Lanzerotti, LJ Livi, S Mauk, BH McEntire, RW Roelof, EC Wilken, B Williams, DJ TI A nebula of gases from Io surrounding Jupiter SO NATURE LA English DT Article ID MAGNETOSPHERE; UPSTREAM; ULYSSES AB Several planetary missions have reported(1-4) the presence of substantial numbers of energetic ions and electrons surrounding Jupiter; relativistic electrons are observable up to several astronomical units (AU) from the planet. A population of energetic (>30 keV) neutral particles also has been reported(5), but the instrumentation was not able to determine the mass or charge state of the particles, which were subsequently labelled(6) energetic neutral atoms. Although images showing the presence of the trace element sodium were obtained(7), the source and identity of the neutral atoms-and their overall significance relative to the loss of charged particles from Jupiter's magnetosphere-were unknown. Here we report the discovery by the Cassini spacecraft of a fast (>10(3) km s(-1)) and hot magnetospheric neutral wind extending more than 0.5 AU from Jupiter, and the presence of energetic neutral atoms (both hot and cold) that have been accelerated by the electric field in the solar wind. We suggest that these atoms originate in volcanic gases from Io, undergo significant evolution through various electromagnetic interactions, escape Jupiter's magnetosphere and then populate the environment around the planet. Thus a 'nebula' is created that extends outwards over hundreds of jovian radii. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Univ Maryland, Dept Phys, College Pk, MD 20742 USA. CNES, F-31028 Toulouse, France. Fundamental Technol, Lawrence, KS 66046 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Arizona, Dept Phys, Tucson, AZ 85721 USA. Max Planck Inst Aeron, D-37191 Katlenburg Lindau, Germany. Bell Labs, Murray Hill, NJ 07974 USA. RP Krimigis, SM (reprint author), Johns Hopkins Univ, Appl Phys Lab, 11100 Johns Hopkins Rd, Laurel, MD 20723 USA. RI Mauk, Barry/E-8420-2017; OI Mauk, Barry/0000-0001-9789-3797; Dandouras, Iannis/0000-0002-7121-1118; Hamilton, Douglas/0000-0001-6103-8019 NR 14 TC 20 Z9 20 U1 0 U2 4 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 28 PY 2002 VL 415 IS 6875 BP 994 EP 996 DI 10.1038/415994a PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 525MF UT WOS:000174075000035 PM 11875559 ER PT J AU Clarke, JT Ajello, J Ballester, G Ben Jaffel, L Connerney, J Gerard, JC Gladstone, GR Grodent, D Pryor, W Trauger, J Waite, JH AF Clarke, JT Ajello, J Ballester, G Ben Jaffel, L Connerney, J Gerard, JC Gladstone, GR Grodent, D Pryor, W Trauger, J Waite, JH TI Ultraviolet emissions from the magnetic footprints of Io, Ganymede and Europa on Jupiter SO NATURE LA English DT Article ID GALILEO SPACECRAFT; FLUX TUBE; AURORA; SYSTEM; FIELD AB Io leaves a magnetic footprint on Jupiter's upper atmosphere that appears as a spot of ultraviolet emission that remains fixed underneath Io as Jupiter rotates(1-3). The specific physical mechanisms responsible for generating those emissions are not well understood, but in general the spot seems to arise because of an electromagnetic interaction between Jupiter's magnetic field and the plasma surrounding Io, driving currents of around 1 million amperes down through Jupiter's ionosphere(4-6). The other galilean satellites may also leave footprints, and the presence or absence of such footprints should illuminate the underlying physical mechanism by revealing the strengths of the currents linking the satellites to Jupiter. Here we report persistent, faint, far-ultraviolet emission from the jovian footprints of Ganymede and Europa. We also show that Io's magnetic footprint extends well beyond the immediate vicinity of Io's flux-tube interaction with Jupiter, and much farther than predicted theoretically(4-6); the emission persists for several hours downstream. We infer from these data that Ganymede and Europa have persistent interactions with Jupiter's magnetic field despite their thin atmospheres. C1 Boston Univ, Boston, MA 02215 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Michigan, Ann Arbor, MI 48109 USA. CNRS, Inst Astrophys Paris, F-75014 Paris, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Liege, B-4000 Liege, Belgium. SW Res Inst, San Antonio, TX 78228 USA. Univ Colorado, Boulder, CO 80303 USA. RP Clarke, JT (reprint author), Boston Univ, 725 Commonwealth Ave, Boston, MA 02215 USA. RI Clarke, John/C-8644-2013; connerney, john/I-5127-2013; OI GERARD, Jean-Claude/0000-0002-8565-8746 NR 25 TC 113 Z9 114 U1 0 U2 8 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 28 PY 2002 VL 415 IS 6875 BP 997 EP 1000 DI 10.1038/415997a PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 525MF UT WOS:000174075000036 PM 11875560 ER PT J AU Gladstone, GR Waite, JH Grodent, D Lewis, WS Crary, FJ Elsner, RF Weisskopf, MC Majeed, T Jahn, JM Bhardwaj, A Clarke, JT Young, DT Dougherty, MK Espinosa, SA Cravens, TE AF Gladstone, GR Waite, JH Grodent, D Lewis, WS Crary, FJ Elsner, RF Weisskopf, MC Majeed, T Jahn, JM Bhardwaj, A Clarke, JT Young, DT Dougherty, MK Espinosa, SA Cravens, TE TI A pulsating auroral X-ray hot spot on Jupiter SO NATURE LA English DT Article ID IO FLUX TUBE; MIDDLE MAGNETOSPHERE; ENERGETIC OXYGEN; UV AURORA; EMISSION; STRATOSPHERE; TEMPERATURE; ABUNDANCES; FEATURES; GALILEO AB Jupiter's X-ray aurora has been thought to be excited by energetic sulphur and oxygen ions precipitating from the inner magnetosphere into the planet's polar regions(1-3). Here we report high-spatial-resolution observations that demonstrate that most of Jupiter's northern auroral X-rays come from a 'hot spot' located significantly poleward of the latitudes connected to the inner magnetosphere. The hot spot seems to be fixed in magnetic latitude and longitude and occurs in a region where anomalous infrared(4-7) and ultraviolet(8) emissions have also been observed. We infer from the data that the particles that excite the aurora originate in the outer magnetosphere. The hot spot X-rays pulsate with an approximately 45-min period, a period similar to that reported for high-latitude radio and energetic electron bursts observed by near-Jupiter spacecraft(9,10). These results invalidate the idea that jovian auroral X-ray emissions are mainly excited by steady precipitation of energetic heavy ions from the inner magnetosphere. Instead, the X-rays seem to result from currently unexplained processes in the outer magnetosphere that produce highly localized and highly variable emissions over an extremely wide range of wavelengths. C1 SW Res Inst, San Antonio, TX 78228 USA. Univ Michigan, Ann Arbor, MI 48109 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Vikram Sarabhai Space Ctr, Trivandrum 695022, Kerala, India. Boston Univ, Boston, MA 02215 USA. Univ London Imperial Coll Sci & Technol, Blackett Lab, London SW7 2BZ, England. Max Planck Inst Aeron, D-37191 Katlenburg Lindau, Germany. Univ Kansas, Lawrence, KS 66045 USA. RP Gladstone, GR (reprint author), SW Res Inst, 6220 Culebra Rd, San Antonio, TX 78228 USA. RI Clarke, John/C-8644-2013; OI Bhardwaj, Anil/0000-0003-1693-453X NR 26 TC 105 Z9 105 U1 0 U2 8 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 28 PY 2002 VL 415 IS 6875 BP 1000 EP 1003 DI 10.1038/4151000a PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 525MF UT WOS:000174075000037 PM 11875561 ER PT J AU Shenoy, DK Thomsen, DL Srinivasan, A Keller, P Ratna, BR AF Shenoy, DK Thomsen, DL Srinivasan, A Keller, P Ratna, BR TI Carbon coated liquid crystal elastomer film for artificial muscle applications SO SENSORS AND ACTUATORS A-PHYSICAL LA English DT Article DE liquid crystal elastomers; carbon coating; contraction/extension times; mechanical properties; actuators AB New liquid crystal elastomer materials with properties that mimic the action of a muscle have been developed recently. Uniaxial contraction of a free standing film of the material can be achieved by heating the film through the nematic to isotropic phase transition. In this paper, carbon coating of such a material is shown to be an effective approach for enhancing the response of a free standing elastomer film to an external stimulus. The heat is generated in the carbon coating by absorption of infrared laser radiation and then conducted through the bulk. It is shown that this leads to a significant reduction in the actuation response time without substantially affecting mechanical properties. This demonstration opens up new opportunities for application of liquid crystal elastomers as actuators. (C) 2002 Elsevier Science B.V All rights reserved. C1 NASA, Langley Res Ctr, Adv Mat & Proc Branch, Hampton, VA 23681 USA. Geocenters Inc, USN, Res Lab, Newton Ctr, MA 02159 USA. RP Shenoy, DK (reprint author), NASA, Langley Res Ctr, Adv Mat & Proc Branch, 6A W Taylor St,MS 226, Hampton, VA 23681 USA. NR 11 TC 77 Z9 80 U1 2 U2 23 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0924-4247 J9 SENSOR ACTUAT A-PHYS JI Sens. Actuator A-Phys. PD FEB 28 PY 2002 VL 96 IS 2-3 BP 184 EP 188 AR PII S0924-4247(01)00793-2 DI 10.1016/S0924-4247(01)00793-2 PG 5 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 532WH UT WOS:000174497700013 ER PT J AU Brasunas, JC Lakew, B Fettig, R AF Brasunas, JC Lakew, B Fettig, R TI A comment on the reported detectivity of a new uncooled thermal infrared detector SO SENSORS AND ACTUATORS A-PHYSICAL LA English DT Editorial Material DE uncooled; infrared detector; silicon diode AB A recently published paper describes a newly developed, uncooled thermal infrared detector using a silicon diode. The authors state the detector demonstrates a detectivity D* of 1.2 x 10(10) cm rootHz/W at room temperature in air ambient. We believe that in fact this level of D* has not been demonstrated. Using information given in the paper we show such a D* to be inconsistent with the apparent time constant of this device. (C) 2002 Published by Elsevier Science B.V. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Raytheon Co, Lanham, MD 20706 USA. RP Brasunas, JC (reprint author), NASA, Goddard Space Flight Ctr, Code 693, Greenbelt, MD 20771 USA. RI brasunas, john/I-2798-2013 NR 4 TC 3 Z9 4 U1 0 U2 2 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0924-4247 J9 SENSOR ACTUAT A-PHYS JI Sens. Actuator A-Phys. PD FEB 28 PY 2002 VL 96 IS 2-3 BP 211 EP 213 AR PII S0924-4247(01)00771-3 DI 10.1016/S0924-4247(01)00771-3 PG 3 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 532WH UT WOS:000174497700016 ER PT J AU Salby, M Sassi, F Callaghan, P Wu, D Keckhut, P Hauchecorne, A AF Salby, M Sassi, F Callaghan, P Wu, D Keckhut, P Hauchecorne, A TI Mesospheric inversions and their relationship to planetary wave structure SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article DE inversion; mesosphere; planetary waves ID TEMPERATURE INVERSIONS; BREAKING AB [1] Mesospheric inversions are studied in vertical soundings from the French lidar at Observatoire de Haute-Provence and in synoptic global structure that was observed simultaneously by the UARS satellite. The latter provides the instantaneous three-dimensional (3-D) structure of the circulation that accompanies mesospheric inversions. A numerical simulation with a 3-D primitive equation model is then shown to reproduce major features of the observed behavior. Both reveal an extensive pattern of inverted thermal structure. The behavior is closely related to planetary waves, which, in the model, experience strong absorption in the upper mesosphere and lower thermosphere. Inverted thermal structure mirrors the synoptic pattern of potential vorticity, which marks the polar night vortex. Both are strongly distorted during stratospheric warmings, when inverted thermal structure at midlatitudes is favored. The region of negative lapse rate coincides with those altitudes where planetary wave temperature undergoes an abrupt phase shift. Wave temperature is then driven out of phase with wave geopotential. This alters the vertical structure of planetary waves, from westward tilt and upward amplification below the inversion to nearly barotropic structure and upward decay above the inversion. Accompanying the upward decay of planetary waves above the inversion is a decay of flow distortion, as the disturbed vortex is gradually restored toward polar symmetry. C1 Univ Colorado, Program Atmospher & Ocean Sci, Boulder, CO 80309 USA. Atmospher Syst & Anal, Westminster, CO 80234 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CNRS, Serv Aeron, F-91371 Verrieres Le Buisson, France. RP Salby, M (reprint author), Univ Colorado, Program Atmospher & Ocean Sci, 311 UCB, Boulder, CO 80309 USA. EM sassi@thunder.asac.org; paddy@asac.org; dwu@mls.jpl.nasa.gov; philippe.keckhut@aerov.jussieu.fr; hauchecorne@aerov.jussieu.fr RI Hauchecorne, Alain/A-8489-2013; Wu, Dong/D-5375-2012 NR 15 TC 20 Z9 20 U1 1 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 FEB 27 PY 2002 VL 107 IS D4 AR 4041 DI 10.1029/2001JD000756 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 609ET UT WOS:000178891200001 ER PT J AU King, RA Breuer, KS AF King, RA Breuer, KS TI Oblique transition in a laminar Blasius boundary layer SO JOURNAL OF FLUID MECHANICS LA English DT Article ID PLANE POISEUILLE FLOW; WAVE PACKET; DISTURBANCES; INSTABILITY; EVOLUTION; MECHANISM AB Oblique transition was experimentally investigated in a Blasius boundary layer formed on a flat plate. This transition mechanism was provoked by exciting a pair of oppositely oriented oblique Orr-Sommerfeld (O-S) modes given by (omega/omega(ts) +/-beta/beta(ts)) = (1, +/-1) in the frequency-wavenumber (spanwise) space. Surface waviness with height Deltah and a well-defined wavenumber spectrum that is synchronized with the neutral O-S wavenumber at Branch I, (alpha(w) +/-beta(w)) = (alpha(ts,I) +/-beta(ts,I)), was used to provide a steady velocity perturbation in the near-wall region. A planar downstream-travelling acoustic wave of amplitude e was created to temporally excite the flow near the resonance frequency, omega(ts)(= 2pif(o)), of an unstable eigenmode corresponding to k(ts) = k(w) (where k = +/-[alpha(2) + beta(2)](1/2)). Possible mechanisms leading to laminar-to-turbulent breakdown were examined for various forcing combinations, epsilonDeltah. For small values of epsilonDeltah, a peak-valley structure corresponding to a spanwise wavenumber of 2beta(w) was observed. As expected, the maximum r.m.s. narrow-band streamwise velocity fluctuations, u(t)(f(o)), occur at peak locations, which correspond to regions with mean streamwise velocity, U, deficits. For the largest value of epsilonDeltah, significant mean-flow distortion was observed in the spanwise profiles of U. Large spanwise velocity gradients, \dU/dxi\, exist between peaks and valleys and appear to generate an explosive growth in the velocity fluctuations. The maximum values of it, no longer occur at peak locations of the stationary structure but at locations of spanwise inflection points. The magnitude of u(t) scales with \dU/dxi\. A nonlinear interaction of two non-stationary modes was conjectured as a possible mechanism for the enhancement of the streak amplification rate. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Brown Univ, Div Engn, Providence, RI 02912 USA. RP King, RA (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. OI Breuer, Kenneth/0000-0002-5122-2231 NR 31 TC 0 Z9 0 U1 0 U2 5 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH ST, NEW YORK, NY 10011-4221 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD FEB 25 PY 2002 VL 453 BP 177 EP 200 DI 10.1017/S0022112001006826 PG 24 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 532BY UT WOS:000174452800008 ER PT J AU Weichman, PB Glazman, RE AF Weichman, PB Glazman, RE TI Spatial variations of a passive tracer in a random wave field SO JOURNAL OF FLUID MECHANICS LA English DT Article ID TURBULENCE; FLUCTUATION; TRANSPORT; SPECTRUM AB The effect of random wave fields on passive tracer spatial variations is studied. We derive a closed-form expression for the spatial autocorrelation function (or power spectrum) of the tracer fluctuations that is quantitatively accurate so long as wave field nonlinearities are small. The theory is illustrated for the case of long internal gravity waves in the ocean. We find that even if the (rear face of the) spectrum of the advecting velocity field is a pure power law, the tracer spectrum has two separate power law subranges. Most important to oceanographic applications, in the larger scale subrange, the effective horizontal compressibility of the wave velocity field becomes a dominant factor of the tracer variations. In such cases, the concentration spectrum becomes approximately proportional to the spectrum of the wave potential energy. The latter, which decays with increasing wavenumber much more rapidly than that known for two-dimensional eddy turbulence, is confirmed by satellite observations in wave-dominated ocean regions. As an additional confirmation of the theory, we demonstrate the occurrence of spectral peaks at wavenumbers corresponding to the semi-diurnal tide frequency. C1 Blackhawk Geometr, Golden, CO 80401 USA. CALTECH, Jet Prop Lab 300 323, Pasadena, CA 91109 USA. RP Weichman, PB (reprint author), Blackhawk Geometr, 301 Commercial Rd,Suite B, Golden, CO 80401 USA. NR 31 TC 6 Z9 7 U1 0 U2 6 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH ST, NEW YORK, NY 10011-4221 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD FEB 25 PY 2002 VL 453 BP 263 EP 287 DI 10.1017/S0022112001006942 PG 25 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 532BY UT WOS:000174452800011 ER PT J AU Catling, D Zahnle, K McKay, C AF Catling, D Zahnle, K McKay, C TI The problematic rise of Archean oxygen - Response SO SCIENCE LA English DT Editorial Material C1 Univ Washington, Dept Atmospher Sci, Astrobiol Program, Seattle, WA 98195 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Catling, D (reprint author), Univ Washington, Dept Atmospher Sci, Astrobiol Program, Box 351640, Seattle, WA 98195 USA. RI Catling, David/D-2082-2009 NR 5 TC 0 Z9 0 U1 0 U2 0 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 FEB 22 PY 2002 VL 295 IS 5559 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 523WV UT WOS:000173981300002 ER PT J AU Barstow, MA Good, SA Holberg, JB Burleigh, MR Bannister, NP Hubeny, I Napiwotzki, R AF Barstow, MA Good, SA Holberg, JB Burleigh, MR Bannister, NP Hubeny, I Napiwotzki, R TI FUSE observations of PG1342+444: new insights into the nature of the hottest DA white dwarfs SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE methods : data analysis; stars : abundances; stars : atmospheres; stars : individual : PG1342+444; white dwarfs; ultraviolet : stars ID LUMINOSITY FUNCTION; MODEL ATMOSPHERES; MASS-DISTRIBUTION; HYDROGEN-RICH; HOT; ULTRAVIOLET; G191-B2B; HELIUM; STARS; TEMPERATURES AB We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the very hot (T(eff) approximate to 60 000 K) DA white dwarf PG 1342+444, describing our data reduction and analysis techniques. The spectrum reveals a number of photospheric absorption lines from high ionization species along with numerous interstellar features. The photospheric detections include the 1031.9- and 1037.0-Angstrom Ovi lines which are seen for the first time in a hot DA atmosphere and are usually associated with the much hotter PG 1159 stars and so-called Ovi central stars of planetary nebulae. Estimates of the stellar effective temperature made independently using both the Balmer and Lyman series lines are in disagreement (T(eff) approximate to 67 000 and approximate to 54 000 K respectively), when taking into account just the statistical uncertainties in the analyses. However, the presence of weak absorption from the CIII multiplet near 1176 Angstrom, which is predicted to be much stronger if the star were as cool as the Lyman measurement suggests, leads us to favour the higher temperature. PG1342+444 appears to have enhanced C, Fe and Ni abundances in its atmosphere compared with all the other G191-B2B-like DA white dwarfs, which might affect the temperature structure of the atmosphere if not homogeneously distributed, as assumed in this study. C1 Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Dr Remeis Sternwarte, D-96049 Bamberg, Germany. RP Barstow, MA (reprint author), Univ Leicester, Dept Phys & Astron, Univ Rd, Leicester LE1 7RH, Leics, England. EM mab@star.le.ac.uk NR 39 TC 7 Z9 7 U1 0 U2 0 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD FEB 21 PY 2002 VL 330 IS 2 BP 425 EP 434 DI 10.1046/j.1365-8711.2002.05082.x PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 526XL UT WOS:000174155100021 ER PT J AU Wang, MH Isaacman, A Franz, BA McClain, CR AF Wang, MH Isaacman, A Franz, BA McClain, CR TI Ocean-color optical property data derived from the Japanese ocean color and temperature scanner and the French polarization and directionality of the earth's reflectances: a comparison study SO APPLIED OPTICS LA English DT Article ID WATER-LEAVING RADIANCE; ATMOSPHERIC DIFFUSE TRANSMITTANCE; A-BAND ABSORPTION; SPECTRAL REFLECTANCE; SURVEY SENSORS; SEAWIFS; ALGORITHM; IMAGERY; CALIBRATION; WHITECAPS AB We describe our efforts to study and compare the ocean-color data derived from the Japanese Ocean Color and Temperature Scanner (OCTS) and the French Polarization and Directionality of the Earth's Reflectances (POLDER). OCTS and POLDER were both on board Japan's Sun-synchronous Advanced Earth Observing Satellite from August 1996 to June 1997, collecting approximately 10 months of global ocean-color data. This operation provided a unique opportunity for the development of methods and strategies for the merging of ocean-color data from multiple ocean-color sensors. We describe our approach to the development of consistent data-processing algorithms for both OCTS and POLDER and the use of a common in situ data set to calibrate vicariously the two sensors. Therefore the OCTS- and POLDER-measured radiances are bridged effectively through common in situ measurements. With this approach to the processing of data from two different sensors, the only differences in the derived products from OCTS and POLDER are the differences that are inherited from the instrument characteristics. Results show that there are no obvious bias differences between the OCTS- and POLDER-derived ocean-color products, whereas the differences due to noise, which stem from variations in sensor characteristics, are difficult to correct at the pixel level. The ocean-color data from OCTS and POLDER therefore can be compared and merged in the sense that there is no significant bias between two. (C) 2002 Optical Society of America. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Baltimore, MD 21210 USA. Sci Applicat Int Corp, Gen Sci Corp, Beltsville, MD 20705 USA. RP Wang, MH (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM wang@simbios.gsfc.nasa.gov RI Wang, Menghua/F-5631-2010; Franz, Bryan/D-6284-2012 OI Wang, Menghua/0000-0001-7019-3125; Franz, Bryan/0000-0003-0293-2082 NR 41 TC 28 Z9 30 U1 1 U2 4 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD FEB 20 PY 2002 VL 41 IS 6 BP 974 EP 990 DI 10.1364/AO.41.000974 PG 17 WC Optics SC Optics GA 523CN UT WOS:000173934400004 PM 11900148 ER PT J AU de Jager, OC Stecker, FW AF de Jager, OC Stecker, FW TI Extragalactic gamma-ray absorption and the intrinsic spectrum of Markarian 501 during the 1997 flare SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL Lacertae objects : individual (Markarian 501); diffuse radiation; gamma rays : theory; intergalactic medium ID BACKGROUND EXPERIMENT SEARCH; INFRARED GALAXY COUNTS; TEV ENERGY-SPECTRUM; MULTIWAVELENGTH OBSERVATIONS; COBE FIRAS; MKN 501; MU-M; CONSTRAINTS; EMISSION; MICRONS AB Using the recent models of Malkan & Stecker for the infrared background radiation and extrapolating them into the optical and UV range using recent galaxy count data, we rederive the optical depth of the universe to high-energy gamma-rays as a function of energy and redshift for energies between 50 GeV and 100 TeV and redshifts between 0.03 and 0.3. We then use these results to derive the intrinsic gamma-ray spectrum of Mrk 501 during its 1997 high state. We find that the time-averaged spectral energy distribution of Mrk 501 while flaring had a broad, flat peak in the similar to5-10 TeV range that corresponds to the broad, flat, time-averaged X-ray peak in the similar to50-100 keV range observed during the flare. The spectral index of our derived intrinsic differential photon spectrum for Mrk 501 at energies below similar to2 TeV was found to be similar to1.6-1.7. This corresponds to a time-averaged spectral index of 1.76 found in soft X-rays at energies below the X-ray (synchrotron) peak. These results apparently favor a synchrotron self-Compton (SSC) origin for the TeV emission, together with jet parameters that are consistent with time variability constraints within the context of a simple SSC model. C1 Potchefstroom Univ Christian Higher Educ, Unit Space Phys, ZA-2520 Potchefstroom, South Africa. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP de Jager, OC (reprint author), Potchefstroom Univ Christian Higher Educ, Unit Space Phys, ZA-2520 Potchefstroom, South Africa. RI Stecker, Floyd/D-3169-2012 NR 45 TC 86 Z9 86 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 FEB 20 PY 2002 VL 566 IS 2 BP 738 EP 743 DI 10.1086/338275 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520WE UT WOS:000173804900013 ER PT J AU Tumlinson, J Shull, JM Rachford, BL Browning, MK Snow, TP Fullerton, AW Jenkins, EB Savage, BD Crowther, PA Moos, HW Sembach, KR Sonneborn, G York, DG AF Tumlinson, J Shull, JM Rachford, BL Browning, MK Snow, TP Fullerton, AW Jenkins, EB Savage, BD Crowther, PA Moos, HW Sembach, KR Sonneborn, G York, DG TI A Far Ultraviolet Spectroscopic Explorer survey of interstellar molecular hydrogen in the Small and Large Magellanic Clouds SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : clouds; ISM : molecules; Magellanic Clouds; ultraviolet : ISM ID WOLF-RAYET STARS; SEST KEY PROGRAM; LINE-OF-SIGHT; SPECTRAL CLASSIFICATION; OB STARS; IRREGULAR GALAXIES; INFRARED-EMISSION; INTRINSIC COLORS; MASSIVE STARS; BAND SYSTEM AB We describe a moderate-resolution Far Ultraviolet Spectroscopic Explorer (FUSE) survey of H(2) along 70 sight lines to the Small and Large Magellanic Clouds, using hot stars as background sources. FUSE spectra of 67% of observed Magellanic Cloud sources (52% of LMC and 92% of SMC) exhibit absorption lines from the H(2) Lyman and Werner bands between 912 and 1120 Angstrom. Our survey is sensitive to N(H(2)) greater than or equal to 10(14) cm(-2); the highest column densities are log N(H(2)) = 19.9 in the LMC and 20.6 in the SMC. We find reduced H(2) abundances in the Magellanic Clouds relative to the Milky Way, with average molecular fractions [f(H2)] = 0.010(-0.002)(+0.005) for the SMC and [f(H2)] = 0.012(-0.003)(+0.006) for the LMC, compared with [f(H2)] = 0.095 for the Galactic disk over a similar range of reddening. The dominant uncertainty in this measurement results from the systematic di+erences between 21 cm radio emission and Lyalpha in pencil beam sight lines as measures of N(H I). These results imply that the diffuse H(2) masses of the LMC and SMC are 8 x 10(6) and 2 x 10(6) M., respectively, 2% and 0.5% of the H I masses derived from 21 cm emission measurements. The LMC and SMC abundance patterns can be reproduced in ensembles of model clouds with a reduced H(2) formation rate coefficient, Rsimilar to3 x 10(-18) cm(3) s(-1), and incident radiation fields ranging from 10-100 times the Galactic mean value. We find that these high-radiation, low formation rate models can also explain the enhanced N(4)/N(2) and N(5)/N(3) rotational excitation ratios in the Clouds. We use H(2) column densities in low rotational states (J = 0 and 1) to derive kinetic and/or rotational temperatures of diffuse interstellar gas, and we find that the distribution of rotational temperatures is similar to Galactic gas, with [T(01)] = 82 +/- 21 K for clouds with N(H(2)) greater than or equal to 10(16.5) cm(-2). There is only a weak correlation between detected H(2) and far-infrared fluxes as determined by IRAS, perhaps as a result of differences in the survey techniques. We find that the surface density of H(2) probed by our pencil beam sight lines is far lower than that predicted from the surface brightness of dust in IRAS maps. We discuss the implications of this work for theories of star formation in low-metallicity environments. C1 Univ Colorado, Dept Astrophys & Planetary Sci, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Boulder, CO 80309 USA. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Princeton Univ, Dept Astrophys Sci, Princeton, NJ 08544 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. UCL, Dept Phys & Astron, London WC1E 6BT, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Tumlinson, J (reprint author), Univ Colorado, Dept Astrophys & Planetary Sci, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. RI Jenkins, Edward/P-5684-2014; OI Jenkins, Edward/0000-0003-1892-4423; Browning, Matthew/0000-0002-8634-1003; Crowther, Paul/0000-0001-6000-6920 NR 72 TC 153 Z9 153 U1 0 U2 2 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 FEB 20 PY 2002 VL 566 IS 2 BP 857 EP 879 DI 10.1086/338112 PN 1 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520WE UT WOS:000173804900024 ER PT J AU Lai, SP Crutcher, RM Girart, JM Rao, R AF Lai, SP Crutcher, RM Girart, JM Rao, R TI Interferometric mapping of magnetic fields in star-forming regions. II. NGC 2024 FIR 5 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (NGC 2024); ISM : magnetic fields; polarization; stars : formation; techniques : interferometric ID NGC 2024; PROTOSTELLAR CONDENSATIONS; MOLECULAR CLOUD; HIGH-RESOLUTION; DUST EMISSION; CORES; ORION; CONTRACTION; POLARIMETRY; CONTINUUM AB We present the first interferometric polarization maps of the NGC 2024 FIR 5 molecular core, obtained with the BIMA array at approximately 2" resolution. We measure an average position angle of -60degrees +/- 6degrees in the main core of FIR 5 and 54degrees +/- 9degrees in the eastern wing of FIR 5. The morphology of the polarization angles in the main core of FIR 5 suggests that the field lines are parabolic, with a symmetry axis approximately parallel to the major axis of the putative disk in FIR 5, which is consistent with the theoretical scenario that the gravitational collapse pulled the field lines into an hourglass shape. The polarization percentage decreases toward regions with high intensity and close to the center of the core, suggesting that the dust alignment efficiency may decrease at high density. The plane-of-sky field strength can be estimated with the modified Chandrasekhar-Fermi formula, and the small dispersion of the polarization angles in FIR 5 suggests that the magnetic field is strong (greater than or similar to2 mG) and perhaps dominates the turbulent motions in the core. C1 Univ Illinois, Dept Astron, Urbana, IL 61801 USA. RP Lai, SP (reprint author), CALTECH, Jet Prop Lab, MS 169-506, Pasadena, CA 91109 USA. EM slai@thisvi.jpl.nasa.gov; crutcher@astro.uiuc.edu; jgirart@am.ub.es; ramp@oddjob.uchicago.edu RI Girart, Josep/O-1638-2014 OI Girart, Josep/0000-0002-3829-5591 NR 34 TC 61 Z9 61 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 FEB 20 PY 2002 VL 566 IS 2 BP 925 EP 930 DI 10.1086/338336 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520WE UT WOS:000173804900029 ER PT J AU Murray, SS Ransom, SM Juda, M Hwang, U Holt, SS AF Murray, SS Ransom, SM Juda, M Hwang, U Holt, SS TI Is the compact source at the center of Cassiopeia A pulsed? SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (Cassiopeia A); pulsars : general; stars : neutron; supernova remnants; X-rays : stars ID RESOLUTION CAMERA HRC; RAY; STARS; MASS; AXAF AB A 50 ks observation of the supernova remnant Cas A was taken, using the Chandra X-Ray Observatory High-Resolution Camera (HRC) to search for periodic signals from the compact source located near the center. Using the HRC-S in imaging mode, problems with correctly assigning times to events were overcome, allowing the period search to be extended to higher frequencies than possible with previous observations. In an extensive analysis of the HRC data, several possible candidate signals are found using various algorithms, including advanced techniques recently developed by Ransom to search for low-significance periodic signals. Of these possible periods, none is at a high enough confidence level to be particularly favored over the rest. When combined with other information, however (e.g., spectra, total energetics, and the historical age of the remnant), a 12 ms period seems to be more physically plausible than the others, and we use it for illustrative purposes in discussing the possible properties of a putative neutron star in the remnant. We emphasize that this is not necessarily the true period, and that a follow-up observation, scheduled for the fall of 2001, is required. A 50 ks Advanced CCD Imaging Spectrometer (ACIS) observation was taken, and analysis of these data for the central object shows that the spectrum is consistent with several forms and that the emitted X-ray luminosity in the 0.1-10 keV band is 10(33)-10(35) ergs cm(-2) s(-1), depending on the spectral model and the interstellar absorption along the line of sight to the source. The spectral results are consistent with those of Pavlov et al. and Chakrabarty et al. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Olin Coll Engn, Needham, MA 02492 USA. RP Murray, SS (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. OI Juda, Michael/0000-0002-4375-9688; Ransom, Scott/0000-0001-5799-9714 NR 25 TC 27 Z9 27 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 2002 VL 566 IS 2 BP 1039 EP 1044 DI 10.1086/338224 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520WE UT WOS:000173804900038 ER PT J AU Strohmayer, TE Brown, EF AF Strohmayer, TE Brown, EF TI A remarkable 3 hour thermonuclear burst from 4U 1820-30 SO ASTROPHYSICAL JOURNAL LA English DT Article DE nuclear reactions, nucleosynthesis, abundances; stars : individual (4U 1820-30); stars : neutron; X-rays : binaries; X-rays : bursts ID X-RAY-BURSTS; ACCRETING NEUTRON-STAR; QUASI-PERIODIC OSCILLATIONS; COMPTON-SCATTERING; MODEL ATMOSPHERES; RADIUS EXPANSION; ABSORPTION-LINES; REACTION-RATES; SPECTRA; DISCOVERY AB We present a detailed observational and theoretical study of a similar to3 hr long X-ray burst (the "superburst") observed by the Rossi X-Ray Timing Explorer (RXTE) from the low-mass X-ray binary 4U 1820-30. This is the longest X-ray burst ever observed from this source and perhaps one of the longest ever observed in great detail from any source. We show that the superburst is thermonuclear in origin. Its peak luminosity of similar to3.4 x 10(38) ergs s(-1) is consistent with the helium Eddington limit for a neutron star at similar to7 kpc as well as the peak luminosity of other, shorter, thermonuclear bursts from the same source. The superburst begins in the decaying tail of a more typical (approximate to20 s duration) thermonuclear burst. These shorter, more frequent bursts are well-known helium flashes from this source. The level of the accretion-driven flux as well as the observed energy release of upward of 1.5 x 10(42) ergs indicate that helium could not be the energy source for the superburst. We outline the physics relevant to carbon production and burning on helium-accreting neutron stars and present calculations of the thermal evolution and stability of a carbon layer and show that this process is the most likely explanation for the superburst. Ignition at the temperatures in the deep carbon "ocean" requires more than 30 times the mass of carbon inferred from the observed burst energetics unless the He flash is able to trigger a deflagration from a much smaller mass of carbon. We show, however, that for large columns of accreted carbon fuel, a substantial fraction of the energy released in the carbon-burning layer is radiated away as neutrinos, and the heat that is conducted from the burning layer in large part flows inward, only to be released on timescales longer than the observed burst. Thus, the energy released during the event possibly exceeds that observed in X-rays by more than a factor of 10, making the scenario of burning a large mass of carbon at great depths consistent with the observed fluence without invoking any additional trigger. A strong constraint on this scenario is the recurrence time: to accrete an ignition column of 10(13) g cm(-2) takes similar to13/((M) over dot/3 x 10(17) g s(-1)) yr. Spectral analysis during the superburst reveals the presence of a broad emission line between 5.8 and 6.4 keV and an edge at 8-9 keV, likely due to reflection of the burst flux from the inner accretion disk in 4U 1820-30. We believe that this is the first time such a signature has been unambiguously detected in the spectrum of an X-ray burst. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. RP Strohmayer, TE (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 680, Greenbelt, MD 20771 USA. RI Brown, Edward/F-1721-2011; OI Brown, Edward/0000-0003-3806-5339 NR 79 TC 147 Z9 147 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 2002 VL 566 IS 2 BP 1045 EP 1059 DI 10.1086/338337 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520WE UT WOS:000173804900039 ER PT J AU Wijnands, R Muno, MP Miller, JM Franco, LM Strohmayer, T Galloway, D Chakrabarty, D AF Wijnands, R Muno, MP Miller, JM Franco, LM Strohmayer, T Galloway, D Chakrabarty, D TI The burst behavior of the eclipsing low-mass X-ray binary MXB 1659-298 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; stars : individual (MXB 1659-298); stars : neutron; stars : rotation; X-rays : bursts; X-rays : stars ID COHERENT OSCILLATIONS; NEUTRON STARS; EVOLUTION; SYSTEM AB We present a detailed study of the correlations between the burst properties and the inferred mass accretion rate for the X-ray transient MXB 1659-298. The bursts that exhibited oscillations were observed when the source was at a relatively high mass accretion rate, similar to what has been seen for other sources. However, owing to the limited number of observations at lower mass accretion rates, no bursts were observed at such accretion rates, and it is still possible that when MXB 1659-298 accretes at such low-mass accretion rates, bursts can occur that might still exhibit burst oscillations. No clear correlations were found between the different burst properties and the accretion rate, in contrast to what has been found for KS 1731-260 and 4U 1728-34, but similar to what has been reported for Aq1 X-1. However, this lack of correlation for MXB 1659-298 and Aq1 X-1 might be due to the limited range of the mass accretion rate observed for those sources compared to KS 1731-260 and 4U 1728-34. C1 MIT, Ctr Space Res, Cambridge, MA 02139 USA. Univ Chicago, Chicago, IL 60637 USA. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Wijnands, R (reprint author), MIT, Ctr Space Res, 77 Massachusetts Ave, Cambridge, MA 02139 USA. OI Galloway, Duncan/0000-0002-6558-5121 NR 36 TC 16 Z9 16 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 2002 VL 566 IS 2 BP 1060 EP 1068 DI 10.1086/338140 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520WE UT WOS:000173804900040 ER PT J AU Akeson, RL Ciardi, DR van Belle, GT Creech-Eakman, MJ AF Akeson, RL Ciardi, DR van Belle, GT Creech-Eakman, MJ TI Constraints on circumstellar disk parameters from multiwavelength observations: T Tauri and SU Aurigae SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; stars : individual (T Tauri, SU Aurigae); stars : pre-main-sequence ID YOUNG STELLAR OBJECTS; PALOMAR TESTBED INTERFEROMETER; SPECTRAL ENERGY-DISTRIBUTIONS; MILLIMETER-WAVE; STARS AB We present circumstellar disk models for two pre-main-sequence objects, T Tau and SU Aur. The models are based on interferometric data from infrared and millimeter wavelengths and infrared photometry from the literature. The physical properties of the disk are examined by calculating parameter probabilities based on a passive, flat-disk model. The model adequately fits the data for SU Aur but not for T Tau. We find that there are significant differences in the physical parameters suggested by the individual data sets. The size of the inner disk radius as implied by the infrared interferometry data (similar totenths of AU) is larger than expected for a flat-disk model. This discrepancy is discussed in consideration of more complex disk models that include the presence of a hot, inner region or wall in the disk. C1 CALTECH, Interferometry Sci Ctr, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Florida, Gainesville, FL 32611 USA. RP Akeson, RL (reprint author), CALTECH, Interferometry Sci Ctr, MS 100-22, Pasadena, CA 91125 USA. OI Ciardi, David/0000-0002-5741-3047 NR 27 TC 63 Z9 64 U1 1 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 2002 VL 566 IS 2 BP 1124 EP 1131 DI 10.1086/338229 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520WE UT WOS:000173804900046 ER PT J AU Gibb, EL Whittet, DCB AF Gibb, EL Whittet, DCB TI The 6 micron feature in protostars: Evidence for organic refractory material SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : ISM; ISM : abundances; ISM : molecules; line : profiles ID INFRARED-SPECTROSCOPY; INTERSTELLAR-MEDIUM; ION IRRADIATION; DUST; GRAINS; CONSTRAINTS; COMPONENT; BAND; ICES; CO AB Data from the Infrared Space Observatory Short Wavelength Spectrometer have allowed abundances of many species present in interstellar ices to be determined. However, that of H2O, the commonest of all ices, has proved controversial because of inconsistencies between results from different vibrational modes: the 6.0 mum bending mode predicts column densities systematically higher than the stretching, combination, and libration modes in several lines of sight. We show that this discrepancy can be explained by excess absorption arising in a previously unrecognized blended feature, which we attribute to organic refractory matter (ORM). The strength of the excess absorption at 6.0 mum is correlated with that of the 4.62 mum "XCN" feature, the carrier of which is thought to form when interstellar ices undergo UV photolysis or ion bombardment. Our results are thus consistent with an origin for the ORM by energetic processing of simple ices. C1 Rensselaer Polytech Inst, Dept Phys Appl Phys & Astron, Troy, NY 12180 USA. RP Gibb, EL (reprint author), NASA, Extraterr Phys Lab, Goddard Space Flight Ctr, Code 690-2, Greenbelt, MD 20771 USA. OI Whittet, Douglas/0000-0001-8539-3891 NR 29 TC 29 Z9 29 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 2002 VL 566 IS 2 BP L113 EP L116 DI 10.1086/339633 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520WF UT WOS:000173805100013 ER PT J AU Rundle, JB Tiampo, KF Klein, W Martins, JSS AF Rundle, JB Tiampo, KF Klein, W Martins, JSS TI Self-organization in leaky threshold systems: The influence of near-mean field dynamics and its implications for earthquakes, neurobiology, and forecasting SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article; Proceedings Paper CT Colloquium of the National-Academy-of-Science on Self-Organized Complexity in the Physical, Biological, and Social Sciences CY MAR 23-24, 2001 CL NAS BECKMAN CTR, IRVINE, CALIFORNIA SP Natl Acad Sci HO NAS BECKMAN CTR ID ROCK FRICTION; STATISTICAL-MECHANICS; MODELS; CRITICALITY; DEPENDENCE; BEHAVIOR; GRANITE; PHYSICS; FAULTS; SLIP AB Threshold systems are known to be some of the most important nonlinear self-organizing systems in nature, including networks of earthquake faults, neural networks, superconductors and semiconductors, and the World Wide Web, as well as political, social, and ecological systems. All of these systems have dynamics that are strongly correlated in space and time, and all typically display a multiplicity of spatial and temporal scales. Here we discuss the physics of self-organization in earthquake threshold systems at two distinct scales: (i) The "microscopic" laboratory scale, in which consideration of results from simulations leads to dynamical equations that can be used to derive the results obtained from sliding friction experiments, and (ii) the "macroscopic" earthquake fault-system scale, in which the physics of strongly correlated earthquake fault systems can be understood by using time-dependent state vectors defined in a Hilbert space of eigenstates, similar in many respects to the mathematics of quantum mechanics. In all of these systems, long-range interactions induce the existence of locally ergodic dynamics. The existence of dissipative effects leads to the appearance of a "leaky threshold" dynamics, equivalent to a new scaling field that controls the size of nucleation events relative to the size of background fluctuations. At the macroscopic earthquake fault-system scale, these ideas show considerable promise as a means of forecasting future earthquake activity. C1 Univ Colorado, Colorado Ctr Chaos & Complex, Boulder, CO 80309 USA. Univ Colorado, CIRES, Boulder, CO 80309 USA. Univ Colorado, Dept Phys, Boulder, CO 80309 USA. CALTECH, Jet Prop Lab, Explorat Syst Auton Div, Pasadena, CA 91109 USA. Boston Univ, Dept Phys, Boston, MA 02215 USA. Los Alamos Natl Lab, Ctr Nonlinear Studies, Los Alamos, NM 87545 USA. RP Rundle, JB (reprint author), Univ Colorado, Colorado Ctr Chaos & Complex, 216 UCB, Boulder, CO 80309 USA. RI Martins, Jorge/F-7780-2012; Tiampo, Kristy/I-1355-2015 OI Tiampo, Kristy/0000-0002-5500-7600 NR 44 TC 93 Z9 102 U1 0 U2 9 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA SN 0027-8424 J9 P NATL ACAD SCI USA JI Proc. Natl. Acad. Sci. U. S. A. PD FEB 19 PY 2002 VL 99 SU 1 BP 2514 EP 2521 DI 10.1073/pnas.012581899 PG 8 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 525RZ UT WOS:000174085900010 PM 11875204 ER PT J AU Suehle, JS Vogel, EM Roitman, P Conley, JF Johnston, AH Wang, B Bernstein, JB Weintraub, CE AF Suehle, JS Vogel, EM Roitman, P Conley, JF Johnston, AH Wang, B Bernstein, JB Weintraub, CE TI Observation of latent reliability degradation in ultrathin oxides after heavy-ion irradiation SO APPLIED PHYSICS LETTERS LA English DT Article ID THIN GATE OXIDES; INDUCED LEAKAGE CURRENT; BREAKDOWN; RUPTURE AB Constant voltage time-dependent-dielectric-breakdown distributions were obtained for both unirradiated and irradiated 3.0 and 3.2 nm thick SiO2 films subjected to Co-60 gamma irradiation and heavy ions of 823 MeV Xe-129 (linear energy transfer=59 MeV-cm(2)/mg). The gamma irradiation had no effect on oxide lifetime. The heavy ion irradiation substantially reduced oxide life even though the devices were biased at 0.0 V during irradiation. The reduction of oxide lifetime under constant-voltage stress conditions was a strong function of the heavy ion fluence. (C) 2002 American Institute of Physics. C1 Natl Inst Stand & Technol, Div Semicond Elect, Gaithersburg, MD 20899 USA. CALTECH, Jet Prop Lab, NASA, Pasadena, CA 91109 USA. Univ Maryland, Ctr Rehabil Engn, College Pk, MD 20742 USA. N Carolina State Univ, Dept Elect Engn, Raleigh, NC 27695 USA. RP Suehle, JS (reprint author), Natl Inst Stand & Technol, Div Semicond Elect, Gaithersburg, MD 20899 USA. RI Vogel, Eric/A-7731-2008 OI Vogel, Eric/0000-0002-6110-1361 NR 14 TC 32 Z9 32 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD FEB 18 PY 2002 VL 80 IS 7 BP 1282 EP 1284 DI 10.1063/1.1448859 PG 3 WC Physics, Applied SC Physics GA 522LA UT WOS:000173896400058 ER PT J AU Bregman, B Wang, PH Lelieveld, J AF Bregman, B Wang, PH Lelieveld, J TI Chemical ozone loss in the tropopause region on subvisible ice clouds, calculated with a chemistry-transport model SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article DE atmospheric chemistry; ozone depletion; heterogeneous chemistry; tropopause region; subvisible clouds ID REAL-TIME KINETICS; LOWER STRATOSPHERE; HETEROGENEOUS CHEMISTRY; CIRRUS CLOUDS; CHLORINE ACTIVATION; SULFATE AEROSOLS; MIDLATITUDE TROPOPAUSE; NORTHERN MIDLATITUDES; UPPER TROPOSPHERE; TRACE GAS AB [1] A global chemistry-transport model has been used to investigate the role of subvisible ice clouds in chemical ozone loss in the tropopause region. The three-dimensional subvisible cloud representation is based on 6-hourly European Centre for Medium-Range Weather Forecasts high cloud fields, assuming observed cloud particle radii and densities. The resulting seasonal average subvisible cloud occurrence agrees well with that observed by the Stratospheric Aerosol and Gas Experiment (SAGE) II instrument. The clouds are located along cold and warm fronts, associated with cyclonic activity. On the ice clouds, heterogeneous reactions occur similarly as on polar stratospheric clouds. The calculated chemical perturbations show high spatial variability, owing to the relatively detailed cloud representation. Halogen activation occurs only when the clouds are located at or above potential vorticity levels of 2-3 PVU. The cloud-induced chlorine activation is stronger in June than in December with maximum ClO levels close to 100 pptv. Consequently, the calculated chemical ozone loss is stronger in June than in December with local maxima of similar to4%. The calculated chlorine activation is significantly lower compared to previous model results and shows an opposite seasonal behavior. Changing the cloud composition to a mix of liquid and ice reduces the chlorine activation even further. This illustrates the strong sensitivity to cloud properties. In addition, the reactive gas uptake on the ice cloud surfaces is poorly described for midlatitude tropopause conditions. Although these uncertainties prevent an accurate calculation of chemical ozone loss, it seems unlikely that heterogeneous chemistry on subvisible clouds can explain the observed negative ozone trends in the midlatitude lowermost stratosphere. Nevertheless, the ozone loss cannot be neglected, being of comparable magnitude as ozone formation by NOx from commercial air traffic. C1 Univ Utrecht, Inst Marine & Atmospher Res, Utrecht, Netherlands. NASA, Langley Res Ctr, Sci & Technol Corp, Hampton, VA 23681 USA. Max Planck Inst Chem, Air Chem Dept, D-55020 Mainz, Germany. RP Bregman, B (reprint author), Royal Netherlands Meteorol Inst, POB 201, NL-3730 AE De Bilt, Netherlands. EM bregman@knmi.nl RI Lelieveld, Johannes/A-1986-2013 NR 63 TC 14 Z9 15 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 FEB 16 PY 2002 VL 107 IS D3 AR 4032 DI 10.1029/2001JD000761 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 609EF UT WOS:000178890100003 ER PT J AU Gillett, NP Allen, MR McDonald, RE Senior, CA Shindell, DT Schmidt, GA AF Gillett, NP Allen, MR McDonald, RE Senior, CA Shindell, DT Schmidt, GA TI How linear is the Arctic Oscillation response to greenhouse gases? SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article DE Arctic Oscillation; greenhouse gas; AO; GCM; CO2 ID 20TH-CENTURY TEMPERATURE-CHANGE; NORTH-ATLANTIC OSCILLATION; GENERAL-CIRCULATION MODEL; CLIMATE-CHANGE; MIDDLE ATMOSPHERE; OZONE; ATTRIBUTION; SIMULATION; SIGNATURE; TRENDS AB [1] We examine the sensitivity of the Arctic Oscillation (AO) index to increases in greenhouse gas concentrations in integrations of five climate models (the Hadley Centre coupled models (HadCM2 and HadCM3), the European Centre/Hamburg models (ECHAM3 and ECHAM4), and the Goddard Institute for Space Studies stratosphere- resolving (GISS-S) model) and in the National Centers for Environmental Prediction reanalysis. With the exception of HadCM2 all the models show a significant positive AO response to greenhouse gas forcing, but in the models lacking a well-resolved stratosphere that response is smaller than observed. In these models the AO index is linearly dependent on the radiative forcing, even up to similar to 20 times current CO2 levels. By contrast, the GISS-S stratosphere- resolving model shows an AO response comparable to that observed, but the sensitivity of the model to further increases in forcing is reduced when CO2 levels exceed similar to 1.5 times preindustrial values. It has been suggested that greenhouse gas forcing results in the equatorward deflection of planetary waves, which leads to a cooling and strengthening of the polar vortex and hence an increase in the surface Arctic Oscillation. In the observations the number of sudden warmings has reduced dramatically, consistent with this planetary wave effect, leading to a large mean cooling of the vortex. However, neither the GISS-S nor the HadCM3 models are able to reproduce the observed temperature changes, suggesting that this explanation for the impact of the inclusion of a stratosphere in the model may be incomplete. C1 Univ Oxford, Dept Phys, Clarendon Lab, Oxford OX1 3PU, England. Hadley Ctr Climate Predict & Res, Met Off, Bracknell RG12 2SY, Berks, England. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Gillett, NP (reprint author), Univ Oxford, Dept Phys, Clarendon Lab, Pks Rd, Oxford OX1 3PU, England. EM gillett@atm.ox.ac.uk; atmmra@atm.ox.ac.uk; remcdonald@meto.gov.uk; casenior@meto.gov.uk; dshindell@giss.nasa.gov; gschmidt@giss.nasa.gov RI Allen, Myles/A-5172-2012; Shindell, Drew/D-4636-2012; Schmidt, Gavin/D-4427-2012 OI Schmidt, Gavin/0000-0002-2258-0486 NR 32 TC 48 Z9 48 U1 1 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 FEB 16 PY 2002 VL 107 IS D3 AR 4022 DI 10.1029/2001JD000589 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 609EF UT WOS:000178890100013 ER PT J AU Michelsen, HA Manney, GL Irion, FW Toon, GC Gunson, MR Rinsland, CP Zander, R Mahieu, E Newchurch, MJ Purcell, PN Remsberg, EE Russell, JM Pumphrey, HC Waters, JW Bevilacqua, RM Kelly, KK Hintsa, EJ Weinstock, EM Chiou, EW Chu, WP McCormick, MP Webster, CR AF Michelsen, HA Manney, GL Irion, FW Toon, GC Gunson, MR Rinsland, CP Zander, R Mahieu, E Newchurch, MJ Purcell, PN Remsberg, EE Russell, JM Pumphrey, HC Waters, JW Bevilacqua, RM Kelly, KK Hintsa, EJ Weinstock, EM Chiou, EW Chu, WP McCormick, MP Webster, CR TI ATMOS version 3 water vapor measurements: Comparisons with observations from two ER-2 Lyman-alpha hygrometers, MkIV, HALOE, SAGE II, MAS, and MLS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article DE water vapor; comparison; validation; ATMOS; stratosphere ID TRACE MOLECULE SPECTROSCOPY; GAS EXPERIMENT-II; MICROWAVE LIMB SOUNDER; MILLIMETER-WAVE SPECTROMETER; TOTAL HYDROGEN BUDGET; LOWER STRATOSPHERE; POLAR VORTEX; OCCULTATION EXPERIMENT; SEASONAL-VARIATIONS; NOVEMBER 1994 AB [1] We have compared a new version of Atmospheric Trace Molecule Spectroscopy Experiment (ATMOS) retrievals (version 3) of stratospheric and mesospheric water vapor with observations from shuttleborne, satelliteborne, balloonborne, and aircraftborne instruments. These retrievals show agreement to within 5% with the MkIV observations in the middle and lower stratosphere. ATMOS agrees with the National Oceanic and Atmospheric Administration (NOAA) Lyman-alpha hygrometer to within 5% except for features with spatial scales less than the vertical resolution of ATMOS (such as the lower stratospheric seasonal cycle). ATMOS observations are 10-16% lower than measurements from the Harvard Lyman-alpha hygrometer in the lower stratosphere and are 7-14% higher than those from the Microwave Limb Sounder (MLS; prototype version 0104) throughout most of the stratosphere. Agreement is within 7% with the Millimeter-Wave Atmospheric Sounder (MAS; version 20) in the middle and upper stratosphere, but differences are closer to 13% in the lower stratosphere. Throughout the stratosphere, agreement is within 8% with the Halogen Occultation Experiment (HALOE; version 19). ATMOS data from 1994 show agreement with the Stratospheric Aerosol and Gas Experiment II (SAGE II; version 6) values to within 8% in the middle stratosphere, but ATMOS observations are systematically higher than those from SAGE II by as much as 41% in the lower stratosphere. In contrast, ATMOS 1985 values are systematically similar to50% lower than SAGE II values from sunset occultations in the lower stratosphere near 70 hPa but appear to be in better agreement with sunrise occultations. Version 3 retrievals in the upper stratosphere and lower mesosphere are typically 5-10% lower than version 2 values between 1 and 0.05 hPa. This reduction improves agreement with HALOE, MAS, and MLS upper atmospheric observations, but ATMOS values still tend to be higher than values from these instruments in the middle mesosphere. Agreement among the instruments compared here (except for SAGE II) is generally within 15% in the middle to lower stratosphere and mesosphere and within 10% in the middle to upper stratosphere. At altitudes near 30 km, all instruments (including SAGE II) agree to within 10%. C1 Sandia Natl Labs, Combust Res Facil, Livermore, CA 94551 USA. USN, Res Lab, Washington, DC 20375 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Woods Hole Oceanog Inst, Dept Marine Chem & Geochem, Woods Hole, MA 02543 USA. NOAA, Aeron Lab, Boulder, CO 80303 USA. Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium. New Mexico Highlands Univ, Dept Nat Resources Management, Las Vegas, NM 87701 USA. Hampton Univ, Ctr Atmospher Sci, Hampton, VA 23668 USA. Univ Alabama, Dept Atmospher Sci, Huntsville, AL 35899 USA. Univ Edinburgh, Dept Meteorol, Edinburgh EH9 3JZ, Midlothian, Scotland. Harvard Univ, Dept Chem & Biol Chem, Cambridge, MA 02138 USA. Tribal DDB, New York, NY USA. RP Michelsen, HA (reprint author), Sandia Natl Labs, Combust Res Facil, MS 9055,POB 969, Livermore, CA 94551 USA. EM hamiche@ca.sandia.gov; manney@mls.jpl.nasa.gov; fwi@caesar.jpl.nasa.gov; toon@mark4sun.jpl.nasa.gov; mrg@derecho.jpl.nasa.gov; c.p.rinsland@larc.nasa.gov; zander@astro.ulg.ac.be; mahieu@astro.ulg.ac.be; mike@atmos.uah.edu; ppurcell@tribalddb.com; e.e.remsberg@larc.nasa.gov; james.russell@hamptonu.edu; hcp@met.ed.ac.uk; joe@mls.jpl.nasa.gov; bevilacq@poamb.nrl.navy.mil; kellyk@al.noaa.gov; ehintsa@whoi.edu; elliot@huarp.harvard.edu; e.chiou@larc.nasa.gov; w.p.chu@larc.nasa.gov; pat.mccormick@hamptonu.edu; chris.r.webster@jpl.nasa.gov NR 84 TC 11 Z9 11 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 FEB 16 PY 2002 VL 107 IS D3 AR 4027 DI 10.1029/2001JD000587 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 609EF UT WOS:000178890100008 ER PT J AU Lang, QY Cheng, IF Wai, CM Paszczynski, A Crawford, RL Barnes, B Anderson, TJ Wells, R Corti, G Allenbach, L Erwin, DP Assefi, T Mojarradi, M AF Lang, QY Cheng, IF Wai, CM Paszczynski, A Crawford, RL Barnes, B Anderson, TJ Wells, R Corti, G Allenbach, L Erwin, DP Assefi, T Mojarradi, M TI Supercritical fluid extraction and high-performance liquid chromatography-diode array-electrochemical detection of signature redox compounds from sand and soil samples SO ANALYTICAL BIOCHEMISTRY LA English DT Article DE SFE; DAD; ECD; HPLC; redox; riboflavin; coenzyme Q; FMN; FAD; hemin ID POLYCYCLIC AROMATIC-HYDROCARBONS; EXPERIMENTAL-DESIGN APPROACH; COENZYME-Q; CAPILLARY ELECTROPHORESIS; POLYCHLORINATED-BIPHENYLS; PLANETARY SCIENCE; MARS; LIFE; LIPIDS; HPLC AB A supercritical fluid extraction procedure and a chromatographic separation/detection method were developed for the detection of Earth-based microorganisms. After microbes in a sand or a soil sample were hydrolyzed in a diluted NH4OH/acetone solution, several redox compounds from bacteria could be effectively extracted with trimethylamine-modified supercritical CO2 at 35degreesC and 300 atm. These signature redox-active compounds were separated by a reversed-phase HPLC column in an ion-pair mode and then monitored with a diode array detector and an electrochemical detector. The analytical results demonstrated the feasibility of using the reported techniques to detect the chemical signature of life in barren desert sand Samples. (C) 2002 Elsevier Science (USA). C1 Univ Idaho, Dept Chem, Moscow, ID 83844 USA. Univ Idaho, Environm Biotechnol Inst, Moscow, ID 83844 USA. Univ Idaho, Dept Elect Engn, Moscow, ID 83844 USA. Univ Idaho, Dept Mech Engn, Moscow, ID 83844 USA. Univ Idaho, Microelect Res & Commun Inst, Moscow, ID 83844 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wai, CM (reprint author), Univ Idaho, Dept Chem, Moscow, ID 83844 USA. NR 68 TC 7 Z9 7 U1 0 U2 10 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0003-2697 J9 ANAL BIOCHEM JI Anal. Biochem. PD FEB 15 PY 2002 VL 301 IS 2 BP 225 EP 234 DI 10.1006/abio.2001.5502 PG 10 WC Biochemical Research Methods; Biochemistry & Molecular Biology; Chemistry, Analytical SC Biochemistry & Molecular Biology; Chemistry GA 524JB UT WOS:000174008600008 PM 11814293 ER PT J AU Svizhenko, A Anantram, MP Govindan, TR Biegel, B Venugopal, R AF Svizhenko, A Anantram, MP Govindan, TR Biegel, B Venugopal, R TI Two-dimensional quantum mechanical modeling of nanotransistors SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID FIELD-EFFECT TRANSISTORS; SCATTERING-THEORY; SILICON MOSFETS; MONTE-CARLO; ELECTRON-TRANSPORT; INVERSION LAYER; MOS-TRANSISTORS; SIMULATION; DEVICES; MOBILITY AB Quantization in the inversion layer and phase coherent transport are anticipated to have significant impact on device performance in "ballistic" nanoscale transistors. While the role of some quantum effects have been analyzed qualitatively using simple one-dimensional ballistic models, two-dimensional (2D) quantum mechanical simulation is important for quantitative results. In this paper, we present a framework for 2D quantum mechanical simulation of a nanotransistor/metal oxide field effect transistor. This framework consists of the nonequilibrium Green's function equations solved self-consistently with Poisson's equation. Solution of this set of equations is computationally intensive. An efficient algorithm to calculate the quantum mechanical 2D electron density has been developed. The method presented is comprehensive in that treatment includes the three open boundary conditions, where the narrow channel region opens into physically broad source, drain and gate regions. Results are presented for (i) drain current vs drain and gate voltages, (ii) comparison to results from Medici, and (iii) gate tunneling current, using 2D potential profiles. Methods to reduce the gate leakage current are also discussed based on simulation results. (C) 2002 American Institute of Physics. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Purdue Univ, Sch Elect & Comp Engn, W Lafayette, IN 47907 USA. RP Svizhenko, A (reprint author), NASA, Ames Res Ctr, Mail Stop T27A-1, Moffett Field, CA 94035 USA. NR 46 TC 310 Z9 314 U1 10 U2 35 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 FEB 15 PY 2002 VL 91 IS 4 BP 2343 EP 2354 DI 10.1063/1.1432117 PG 12 WC Physics, Applied SC Physics GA 516LB UT WOS:000173553800094 ER PT J AU Yuan, DL AF Yuan, DL TI A numerical study of barotropicly forced intrusion in DeSoto Canyon SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article DE DeSoto Canyon; Loop Current; Ekman; intursion ID GULF-OF-MEXICO; WEST FLORIDA SHELF; WARM-CORE RINGS; LOOP CURRENT; SUBMARINE CANYONS; VARIABILITY; EDDY; WAVE; CIRCULATION; DYNAMICS AB [1] The intrusion of open ocean water across the head of DeSoto Canyon offshore of Pensacola, Florida, is investigated using a version of the Bryan-Cox model of the entire Gulf of Mexico. The Loop Current-forced model circulation in DeSoto Canyon features an eastward, nearly along-isobath, current with a weak cross-isobath velocity component. In contrast, the southward wind-driven currents over the west Florida shelf in response to northerly winds induce strong cross-isobath flow at the head of DeSoto Canyon. The flow is diagnosed to be the bottom Ekman flow associated with the strong along-isobath currents. In addition, transient responses of sea levels to the northerly wind bursts give rise to pressure gradient-forced currents up the canyon during the collapse phase of the winds. A case study in November 1997 is conducted, and the above arguments are substantiated with the simulated and the observed currents. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Goddard Earth Sci & Technol Ctr, Baltimore, MD 21228 USA. RP NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Code 971, Greenbelt, MD 20771 USA. EM dyuan@janus.gsfc.nasa.gov NR 51 TC 7 Z9 7 U1 2 U2 5 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 FEB 15 PY 2002 VL 107 IS C2 AR 3010 DI 10.1029/2001JC000793 PG 16 WC Oceanography SC Oceanography GA 609TL UT WOS:000178920600005 ER PT J AU Rathz, TJ Robinson, MB Hyers, RW Rogers, JR Li, D AF Rathz, TJ Robinson, MB Hyers, RW Rogers, JR Li, D TI Triggered nucleation in Ni60Nb40 using an electrostatic levitator SO JOURNAL OF MATERIALS SCIENCE LETTERS LA English DT Article ID SOLIDIFICATION; FACILITY; MELTS C1 Univ Alabama, Huntsville, AL 35899 USA. NASA, Sci Directorate 47, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Wescast Ind Inc, Stratford, ON N4Z 1H3, Canada. RP Rathz, TJ (reprint author), Univ Alabama, Huntsville, AL 35899 USA. RI Hyers, Robert/G-3755-2010 NR 16 TC 6 Z9 6 U1 0 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0261-8028 J9 J MATER SCI LETT JI J. Mater. Sci. Lett. PD FEB 15 PY 2002 VL 21 IS 4 BP 301 EP 303 DI 10.1023/A:1017928022508 PG 3 WC Materials Science, Multidisciplinary SC Materials Science GA 532TQ UT WOS:000174491500009 ER PT J AU Campos, PRA Adami, C Wilke, CO AF Campos, PRA Adami, C Wilke, CO TI Optimal adaptive performance and delocalization in NK fitness landscapes SO PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS LA English DT Article DE NK landscapes; error threshold; quasispecies; delocalization transition ID ERROR THRESHOLD; EVOLUTION; POPULATIONS; MODEL; MUTATION; TRANSITIONS; DYNAMICS; WALKS AB We investigate the evolutionary dynamics of a finite population of sequences adapting to NK fitness landscapes. We find that. unlike in the case of an infinite population, the average fitness in a finite population is maximized at a small but finite, rather than vanishing, mutation rate. The highest local maxima in the landscape are visited for even larger mutation rates. close to a transition point at which the population delocalizes (i.e.. leaves the fitness peak at which it was localized) and starts traversing the sequence space. If the mutation rate is increased even further, the population undergoes a second transition and loses all sensitivity to fitness peaks. This second transition corresponds to the standard error threshold transition first described by Eigen. We discuss the implications of our results for biological evolution and for evolutionary optimization techniques. (C) 2002 Elsevier Science B.V. All rights reserved. C1 CALTECH, Digital Life Lab, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP, Brazil. RP Wilke, CO (reprint author), CALTECH, Digital Life Lab, Mail Code 136-93, Pasadena, CA 91125 USA. EM wilke@caltech.edu RI Adami, Christoph/A-5181-2009; Adami, Christoph/A-9675-2011; Campos, Paulo/G-2459-2012; Wilke, Claus/B-4643-2008; Sao Carlos Institute of Physics, IFSC/USP/M-2664-2016 OI Adami, Christoph/0000-0002-2915-9504; Campos, Paulo/0000-0002-7823-1998; Wilke, Claus/0000-0002-7470-9261; NR 38 TC 21 Z9 21 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0378-4371 EI 1873-2119 J9 PHYSICA A JI Physica A PD FEB 15 PY 2002 VL 304 IS 3-4 BP 495 EP 506 AR PII S0378-4371(01)00572-6 DI 10.1016/S0378-4371(01)00572-6 PG 12 WC Physics, Multidisciplinary SC Physics GA 533DM UT WOS:000174514200013 ER PT J AU Adessi, C Devel, M AF Adessi, C Devel, M TI Field-enhancement properties of nanotubes in a field emission setup SO PHYSICAL REVIEW B LA English DT Article ID WALL CARBON NANOTUBES; ELECTRON-EMISSION; MATERIALS SCIENCE; COLD CATHODES; DIAMOND; MECHANISM; ARRAYS; FILMS; COMPUTATION; EMITTERS AB The polarization phenomenon. involved in the mechanisms of emission from carbon nanotubes, is investigated by means of a self-consistent resolution of Poisson's equation. We show that the field enhancement. responsible for the emission, varies in a logarithmic way with the nanotube length. This leads. for most of the nanotubes investigated, to a rapid saturation of the amplification of the field which does not allow for the recovery of experimental values for microscopic lengths. However., this saturation is less important with (n,0) nanotubes and values of the amplification factor around 2000 can be obtained with small diameter nanotubes of this kind. The case of nanotube films is also investigated, and the dependence of the amplification factor with the nanotube density is pointed out. Finally, the screening effect of the outer shells on the inner ones is investigated in the case of multiwall nanotubes. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Mol Phys Lab, CNRS, UMR 6624, F-25030 Besancon, France. RP Adessi, C (reprint author), NASA, Ames Res Ctr, Mail Stop T27A-1, Moffett Field, CA 94035 USA. RI DEVEL, Michel/A-5677-2009 OI DEVEL, Michel/0000-0001-8785-6896 NR 34 TC 26 Z9 28 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 J9 PHYS REV B JI Phys. Rev. B PD FEB 15 PY 2002 VL 65 IS 7 AR 075418 DI 10.1103/PhysRevB.65.075418 PG 7 WC Physics, Condensed Matter SC Physics GA 524UH UT WOS:000174030900092 ER PT J AU Baker, J Campanelli, M Lousto, CO AF Baker, J Campanelli, M Lousto, CO TI The Lazarus project: A pragmatic approach to binary black hole evolutions SO PHYSICAL REVIEW D LA English DT Article ID QUASI-CIRCULAR ORBITS; NUMERICAL RELATIVITY; PERTURBATION-THEORY; TEUKOLSKY EQUATION; INITIAL DATA; CAUCHY DATA; CONSTRUCTION; COLLISIONS; SPACETIMES; IMPOSITION AB We present a detailed description of techniques developed to combine 3D numerical Simulations and, subsequently, a single black hole close-limit approximation. This method has made it possible to compute the first complete waveforms covering the post-orbital dynamics of a binary-black-hole system with the numerical simulation covering the essential nonlinear interaction before the close limit becomes applicable for the late time dynamics. In order to couple full numerical and perturbative methods we must address several questions. To determine when close-limit perturbation theory is applicable we apply a combination of invariant a priori estimates and a posteriori consistency checks of the robustness of our results against exchange of linear and nonlinear treatments near the interface. Our method begins with a specialized application of standard numerical techniques adapted to the presently realistic goal of brief, but accurate simulations. Once the numerically modeled binary system reaches a regime that can be treated as perturbations of the Kerr spacetime, we must approximately relate the numerical coordinates to the perturbative background coordinates. We also perform a rotation of a numerically defined tetrad to asymptotically reproduce the tetrad required in the perturbative treatment. We can then produce numerical Cauchy data for the close-limit evolution in the form of the Weyl scalar psi(4) and its time derivative partial derivative(t)psi(4) with both objects being first order coordinate and tetrad invariant. The Teukolsky equation in Boyer-Lindquist coordinates is adopted to further continue the evolution, To illustrate the application of these techniques we evolve a single Kerr hole and compute the spurious radiation as a measure of the error of the whole procedure. We also briefly discuss the extension of the project to make use of improved full numerical evolutions and outline the approach to a full understanding of astrophysical black-hole-binary systems which we can now pursue. C1 Max Planck Inst Gravitat Phys, Albert Einstein Inst, D-14476 Golm, Germany. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Texas, Dept Phys & Astron, Brownsville, TX 78520 USA. Consejo Nacl Invest Cient & Tecn, Inst Astron & Fis Espacio, RA-1033 Buenos Aires, DF, Argentina. RP Baker, J (reprint author), Max Planck Inst Gravitat Phys, Albert Einstein Inst, Muhlenberg 1, D-14476 Golm, Germany. OI Lousto, Carlos/0000-0002-6400-9640 NR 33 TC 91 Z9 91 U1 0 U2 0 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 FEB 15 PY 2002 VL 65 IS 4 AR 044001 DI 10.1103/PhysRevD.65.044001 PG 16 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 524ZY UT WOS:000174043800031 ER PT J AU O'Donnell, F AF O'Donnell, F TI Getting space camera back on track soon SO NATURE LA English DT Letter C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP O'Donnell, F (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 NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 14 PY 2002 VL 415 IS 6873 BP 732 EP 732 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 521HE UT WOS:000173833900019 PM 11845179 ER PT J AU Mecerreyes, D Stevens, R Nguyen, C Pomposo, JA Bengoetxea, M Grande, H AF Mecerreyes, D Stevens, R Nguyen, C Pomposo, JA Bengoetxea, M Grande, H TI Synthesis and characterization of polypyrrole-graft-poly(epsilon-caprolactone) copolymers: new electrically conductive nanocomposites SO SYNTHETIC METALS LA English DT Article DE polypyrrole; graft copolymers; nanocomposite ID BLOCK-COPOLYMER; POLY(METHYL METHACRYLATE); PYRROLE; POLYPYRROLE AB A series of polypyrrole-graft-poly(epsilon-caprolactone) (PPy-g-PCL) copolymers have been synthesized via oxidative copolymerization of pyrrole and pyrrole-end functional macromonomers. Copolymerizations were carried out in tetrahydrofuran at 0 degreesC using FeCl3 as the oxidizing and doping agent. Poly(E-caprolactone) rich copolymers (>85 wt.%) were partly soluble in common organic solvents, whereas polypyrrole-rich copolymers were completely insoluble. The composition of the PPy-g-PCL copolymers was determined by Fourier transform infra-red (FTIR) spectroscopy and thermal gravimetrical analysis (TGA). By controlling the monomer feed and molecular weight of the macromonomer, graft copolymers across a broad composition range were obtained. Both differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) show that the PPy-g-PCL copolymers phase separate into PPy and PCL rich domains. The electrical conductivity of the nanocomposites increases with the amount of polypyrrole in the copolymer between the value of pure PCL (10(-12) S/cm) and that of polypyrrole (10 S/cm). Atomic force microscopy (AFM) confirmed the presence of nanophases (15-40 nm) and hence, the preparation of new nanomaterials. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Ctr Electrochem Res & Dev, Cidetec, Parque Tecnol Miramon, Donostia San Sebastian 20009, Spain. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. IBM Corp, Almaden Res Ctr, San Jose, CA USA. RP Mecerreyes, D (reprint author), Ctr Electrochem Res & Dev, Cidetec, Parque Tecnol Miramon, Parque Tecnol Miramon,Paseo Mikeletegi 61-1, Donostia San Sebastian 20009, Spain. RI Mecerreyes, David/K-7541-2014; OI Mecerreyes, David/0000-0002-0788-7156; Pomposo, Jose A./0000-0001-9458-4200 NR 16 TC 52 Z9 53 U1 5 U2 15 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0379-6779 J9 SYNTHETIC MET JI Synth. Met. PD FEB 14 PY 2002 VL 126 IS 2-3 BP 173 EP 178 AR PII S0379-6779(01)00503-3 DI 10.1016/S0379-6779(01)00503-3 PG 6 WC Materials Science, Multidisciplinary; Physics, Condensed Matter; Polymer Science SC Materials Science; Physics; Polymer Science GA 528JL UT WOS:000174240600007 ER PT J AU Albergo, S Bellwied, R Bennett, M Boemi, D Bonner, B Caines, H Christie, W Costa, S Crawford, HJ Cronqvist, M Debbe, R Engelage, J Flores, I Greiner, L Hallman, T Hijazi, G Hoffmann, G Huang, HZ Humanic, TJ Insolia, A Jensen, P Judd, EG Kainz, K Kaplan, M Kelly, S Kotov, I Kunde, G Lindstrom, PJ Ljubicic, T Llope, W LoCurto, G Longacre, R Lynn, D Madansky, L Mahzeh, N Milosevich, Z Mitchell, JM Mitchell, JW Nehmeh, S Nociforo, C Paganis, S Pandey, SU Potenza, R Russ, DE Saulys, A Schambach, J Sheen, J Sugarbaker, E Takahashi, J Tang, J Trattner, AL Trentalange, S Tricomi, A Tuve, E Whitfield, JP Wilson, K AF Albergo, S Bellwied, R Bennett, M Boemi, D Bonner, B Caines, H Christie, W Costa, S Crawford, HJ Cronqvist, M Debbe, R Engelage, J Flores, I Greiner, L Hallman, T Hijazi, G Hoffmann, G Huang, HZ Humanic, TJ Insolia, A Jensen, P Judd, EG Kainz, K Kaplan, M Kelly, S Kotov, I Kunde, G Lindstrom, PJ Ljubicic, T Llope, W LoCurto, G Longacre, R Lynn, D Madansky, L Mahzeh, N Milosevich, Z Mitchell, JM Mitchell, JW Nehmeh, S Nociforo, C Paganis, S Pandey, SU Potenza, R Russ, DE Saulys, A Schambach, J Sheen, J Sugarbaker, E Takahashi, J Tang, J Trattner, AL Trentalange, S Tricomi, A Tuve, E Whitfield, JP Wilson, K TI Lambda spectra in 11.6A GeV/c Au-Au collisions SO PHYSICAL REVIEW LETTERS LA English DT Article ID SILICON DRIFT DETECTORS; HEAVY-ION COLLISIONS AB E896 has measured Lambda production in 11.6A GeV/c Au-Au collisions over virtually the whole rapidity phase space. The midrapidity p(t) distributions have been measured for the first time at this energy and appear to indicate that the Lambda hyperons have different freeze-out conditions than protons. A comparison with the relativistic quantum molecular dynamics model shows that while there is good shape agreement at high rapidity the model predicts significantly different slopes of the m(t) spectra at midrapidity. The data, where overlap occurs, are consistent with previously reported measurements. C1 Univ Catania, Catania, Italy. Brookhaven Natl Lab, Upton, NY 11973 USA. Univ Calif Los Angeles, Los Angeles, CA USA. Carnegie Mellon Univ, Pittsburgh, PA 15213 USA. Ist Nazl Fis Nucl, Sez Catania, I-95129 Catania, Italy. Johns Hopkins Univ, Baltimore, MD USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Ohio State Univ, Columbus, OH 43210 USA. Rice Univ, Houston, TX 77251 USA. Univ Calif Berkeley, Space Sci Labs, Berkeley, CA 94720 USA. Univ Texas, Austin, TX 78712 USA. Wayne State Univ, Detroit, MI USA. Yale Univ, New Haven, CT USA. RP Albergo, S (reprint author), Univ Catania, Catania, Italy. RI Takahashi, Jun/B-2946-2012; Insolia, Antonio/M-3447-2015 OI Takahashi, Jun/0000-0002-4091-1779; Insolia, Antonio/0000-0002-9040-1566 NR 20 TC 47 Z9 47 U1 0 U2 4 PU AMERICAN 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 FEB 11 PY 2002 VL 88 IS 6 AR 062301 DI 10.1103/PhysRevLett.88.062301 PG 4 WC Physics, Multidisciplinary SC Physics GA 521PJ UT WOS:000173849300007 PM 11863798 ER PT J AU Crenshaw, DM Kraemer, SB Turner, TJ Collier, S Peterson, BM Brandt, WN Clavel, J George, IM Horne, K Kriss, GA Mathur, S Netzer, H Pogge, RW Pounds, KA Romano, P Shemmer, O Wamsteker, W AF Crenshaw, DM Kraemer, SB Turner, TJ Collier, S Peterson, BM Brandt, WN Clavel, J George, IM Horne, K Kriss, GA Mathur, S Netzer, H Pogge, RW Pounds, KA Romano, P Shemmer, O Wamsteker, W TI Reddening, emission-line, and intrinsic absorption properties in the narrow-line Seyfert 1 galaxy Arakelian 564 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (Arakelian 564); galaxies : Seyfert; ultraviolet : galaxies ID ACTIVE GALACTIC NUCLEI; INTERNATIONAL-ULTRAVIOLET-EXPLORER; SPECTRA; REGION; EXTINCTION; NGC-4151; SPECTROSCOPY; DUST; IUE AB We use Hubble Space Telescope UV and optical spectra of the narrow-line Seyfert 1 (NLS1) galaxy Ark 564 to investigate its internal reddening and properties of its emission-line and intrinsic UV absorption gas. We find that the extinction curve of Ark 564, derived from a comparison of its UV/optical continuum to that of an unreddened NLS1, lacks a 2200 Angstrom bump and turns up toward the UV at a longer wavelength (4000 Angstrom) than the standard Galactic, LMC, and SMC curves. However, it does not show the extremely steep rise to 1200 Angstrom that characterizes the extinction curve of the Seyfert 1 galaxy NGC 3227. The emission lines and continuum experience the same amount of reddening, indicating the presence of a dust screen that is external to the narrow-line region. Echelle spectra from the Space Telescope Imaging Spectrograph show intrinsic UV absorption lines due to Lyalpha, N V, C IV, Si IV, and Si III, centered at a radial velocity of -190 km s(-1) (relative to the host galaxy). Photoionization models of the UV absorber indicate that it has a sufficient column (N-H = 1.6 x 10(21) cm(-2)) and is at a sufficient distance from the nucleus (D > 95 pc) to be the source of the dust screen. Thus, Ark 564 contains a dusty "lukewarm absorber" similar to that seen in NGC 3227. C1 Georgia State Univ, Dept Phys & Astron, Astron Off, Atlanta, GA 30303 USA. Catholic Univ Amer, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA. Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA. ESA, Madrid 28080, Spain. Univ St Andrews, Sch Phys & Astron, St Andrews KY16 9SS, Fife, Scotland. Univ Texas, Dept Astron, Austin, TX 78704 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Wise Observ, IL-69978 Tel Aviv, Israel. Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England. RP Crenshaw, DM (reprint author), Georgia State Univ, Dept Phys & Astron, Astron Off, 1 Pk Pl S SE,Suite 700, Atlanta, GA 30303 USA. RI Brandt, William/N-2844-2015; OI Brandt, William/0000-0002-0167-2453; Romano, Patrizia/0000-0003-0258-7469; Shemmer, Ohad/0000-0003-4327-1460 NR 49 TC 49 Z9 51 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2002 VL 566 IS 1 BP 187 EP 194 DI 10.1086/338058 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520EB UT WOS:000173766700015 ER PT J AU Contopoulos, I Kazanas, D AF Contopoulos, I Kazanas, D TI Toward resolving the Crab sigma-problem: A linear accelerator? SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; magnetic fields; MHD; pulsars : general ID AXISYMMETRICAL PULSAR MAGNETOSPHERE; DRIVEN RELATIVISTIC JETS; HIGH-ENERGY; GAMMA-RAY; WINDS; COLLIMATION; NEBULA; CONFINEMENT; OUTFLOWS AB Using the exact solution of the axisymmetric pulsar magnetosphere derived in a previous publication and the conservation laws of the associated MHD flow, we show that the Lorentz factor of the outflowing plasma increases linearly with distance from the light cylinder. Therefore, the ratio of the Poynting to particle energy flux, generically referred to as sigma, decreases inversely proportional to distance from a large value (typically greater than or similar to 10(4)) near the light cylinder to sigma similar or equal to 1 at a transition distance R-trans. Beyond this distance, the inertial ejects of the outnowing plasma become important, and the magnetic Deld geometry must deviate from the almost monopolar form it attains between and R-1c and R-trans. We anticipate that this is achieved by collimation of the poloidal field lines toward the rotation axis, ensuring that the magnetic field pressure in the equatorial region will fall off faster than 1/R-2 (R being the cylindrical radius). This leads both to a value sigma = sigma(s) << 1 at the nebular reverse shock at distance R-s (R-s >> R-trans) and to a component of the flow perpendicular to the equatorial component, as required by observation. The presence of the strong shock at R = R-s allows for the efficient conversion of kinetic energy into radiation. We speculate that the Crab pulsar is unique in requiring sigma(s) similar or equal to 3 x 10(-3) because of its small translational velocity, which allows for the shock distance R-s to grow to values >> R-trans. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Contopoulos, I (reprint author), 200 Akti Themistokleous St, Piraeus 18539, Greece. NR 35 TC 40 Z9 40 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2002 VL 566 IS 1 BP 336 EP 342 DI 10.1086/324778 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520EB UT WOS:000173766700030 ER PT J AU Monnier, JD Greenhill, LJ Tuthill, PG Danchi, WC AF Monnier, JD Greenhill, LJ Tuthill, PG Danchi, WC TI Radio properties of pinwheel nebulae SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : close; circumstellar matter; radio continuum : stars; stars : winds, outflows; stars : Wolf-Rayet ID WOLF-RAYET STARS; MASS-LOSS; X-RAY; MULTIFREQUENCY VARIATIONS; PARTICLE-ACCELERATION; SYSTEM HD-193793; EMISSION; WINDS; OBJECTS; WR-147 AB A small number of dusty Wolf-Rayet stars have been resolved into pinwheel nebulae, defined by their "rotating" spiral dust shells observed in the infrared. This morphology is naturally explained by dust formation associated with colliding winds in a binary system. In order to confirm and further explore this hypothesis, we have observed the known pinwheel nebulae (WR 104 and WR 98a) as well as the suspected binary WR 112 at multiple radio wavelengths with the Very Large Array to search for nonthermal radio emission from colliding winds. The spectrum of each target is nearly flat between 5 and 22 GHz, consistent with the presence of nonthermal emission that is reduced at low frequencies by free-free absorption. This emission must lie outside the radio "photosphere," leading us to estimate a lower limit to the physical size of the nonthermal emitting region that is larger than expected from current theory. Based on a radio and infrared comparison to WR 104 and WR 98a, we conclude that WR 112 is a likely candidate pinwheel nebula, but its temporal variability indicates an eccentric binary orbit or a pinwheel viewed nearly edge-on. A sensitive radio survey of IR-bright WRs would stringently test the hypothesis that colliding winds lie at the heart of all dusty WR systems. We also discuss the effects of dust obscuration in the ultraviolet and how radio-determined mass-loss rates of pinwheel nebulae (and dusty WR stars in general) may be underestimated due to shadowing effects. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Sydney, Sch Phys, Sydney, NSW 2006, Australia. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Monnier, JD (reprint author), Harvard Smithsonian Ctr Astrophys, MS 42,60 Garden St, Cambridge, MA 02138 USA. OI Monnier, John D/0000-0002-3380-3307 NR 43 TC 22 Z9 23 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2002 VL 566 IS 1 BP 399 EP 408 DI 10.1086/337961 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520EB UT WOS:000173766700038 ER PT J AU Sekanina, Z AF Sekanina, Z TI Statistical investigation and modeling of sungrazing comets discovered with the Solar and Heliospheric Observatory SO ASTROPHYSICAL JOURNAL LA English DT Article DE comets : general; methods : data analysis ID SECONDARY FRAGMENTATION; MAXIMUM MISSION; HALE-BOPP; CORONAGRAPH; SHOEMAKER-LEVY-9 AB More than 300 sungrazing comets, most of them discovered with the Solar and Heliospheric Observatory (SOHO) coronagraphs since the beginning of 1996, are known to belong to the Kreutz group or system. Moving about the Sun in similar orbits, they are of indisputably common parentage and represent by far the most extensive data set in the history of investigations of cometary splitting. This study compares the SOHO sungrazers, which always disappear during their approach to the Sun, with the sungrazers detected earlier with the other space-borne coronagraphs (Solwind and Solar Maximum Mission [SMM]) as well as with the bright members of the Kreutz system, discovered from the ground between 1843 and 1970. Collected, summarized, and reviewed information on the sungrazers' light curves indicates that there is a difference of 20 mag (a factor of 10(8) in brightness) between the brightest sungrazer, C/1882 R1, and the faintest objects detectable with the SOHO instruments. The headless comet C/1887 B1 is suggested to be a transition object between the bright sungrazers and the coronagraphically discovered ones: its physical behavior was similar to that of the latter comets, but it survived the perihelion passage. This study also (1) examines temporal and spatial distributions of the SOHO sungrazers; (2) depicts correlations among their orbital elements; (3) distinguishes among tidally triggered, post-tidal, and terminal fragmentation; (4) reiterates the conclusion made in an earlier paper that post-tidal, secondary fragmentation events are occurring throughout the orbit, including the region of aphelion; (5) determines the relationship between a breakup's location in the orbit and the perturbations of the orbital elements of a fragment caused by the momentum it acquires during the separation from the parent; (6) shows that collisions of the Kreutz system comets with the Sun are clearly possible; (7) finds that minor fragments acquire enough extra momentum during each of the breakup episodes that their motions carry no "memory" of these events other than the most recent one; (8) offers a law for simulating the temporal distribution of these events; and (9) proposes a conceptual model scenario for the formation and evolution of the Kreutz system, including the process of progressive fragmentation. It appears that most of the mass is still locked in the major fragments (particularly C/1882 R1) and that therefore this comet system is relatively young. This paper is a first step in a massive investigation of the Kreutz system, which will combine deterministic and Monte Carlo techniques to verify the paradigms of the proposed conceptual model and eventually will develop a specific evolutionary scenario. This approach will account fully for effects of the planetary perturbations, where appropriate, and from time to time the results will be updated as the statistical sample of the SOHO sungrazers continues to grow. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sekanina, Z (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 83 TC 33 Z9 33 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2002 VL 566 IS 1 BP 577 EP 598 DI 10.1086/324335 PN 1 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520EB UT WOS:000173766700053 ER PT J AU Harrington, J Deming, D AF Harrington, J Deming, D TI Models of the Shoemaker-Levy 9 impacts. I. Ballistic Monte Carlo plume (vol 561, pg 455, 2001) SO ASTROPHYSICAL JOURNAL LA English DT Correction C1 Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Greenbelt, MD 20771 USA. RP Harrington, J (reprint author), Cornell Univ, Dept Astron, 326 Space Sci Bldg, Ithaca, NY 14853 USA. RI Harrington, Joseph/E-6250-2011 NR 1 TC 0 Z9 0 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2002 VL 566 IS 1 BP 617 EP 617 DI 10.1086/338577 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520EB UT WOS:000173766700056 ER PT J AU Deming, D Harrington, J AF Deming, D Harrington, J TI Models of the Shoemaker-Levy 9 impacts. II. Radiative-hydrodynamic modeling of the plume splashback (vol 561, pg 468, 2001) SO ASTROPHYSICAL JOURNAL LA English DT Correction C1 NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Greenbelt, MD 20771 USA. Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. RP Deming, D (reprint author), NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Code 693, Greenbelt, MD 20771 USA. RI Harrington, Joseph/E-6250-2011 NR 1 TC 0 Z9 0 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2002 VL 566 IS 1 BP 618 EP 618 DI 10.1086/338578 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520EB UT WOS:000173766700057 ER PT J AU Mauche, CW Mukai, K AF Mauche, CW Mukai, K TI The X-ray spectra of VY Sculptoris stars are not blackbodies SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; novae, cataclysmic variables; stars : individual (KR Aurigae, TT Arietis); X-rays : stars ID CATACLYSMIC VARIABLE-STARS; SS CYGNI; DWARF NOVAE; ROSAT; EMISSION; OUTBURST; SAMPLE; SKY AB Using ASCA data, we find, contrary to other researchers using ROSAT data, that the X-ray spectra of the VY Sculptoris stars TT Arietis and KR Aurigae are poorly fitted by an absorbed blackbody model but are well fitted by an absorbed thermal plasma model. The different conclusions about the nature of the X-ray spectrum of KR Aur may be due to differences in the accretion rate since this star was in a high optical state during the ROSAT observation but in an intermediate optical state during the ASCA observation. TT Ari, on the other hand, was in a high optical state during both observations and so directly contradicts the hypothesis that the X-ray spectra of VY Scl stars in their high optical states are blackbodies. Instead, based on theoretical expectations and the ASCA, Chandra, and XMM spectra of other nonmagnetic cataclysmic variables, we believe that the X-ray spectra of VY Scl stars in their low and high optical states are due to hot thermal plasma in the boundary layer between the accretion disk and the surface of the white dwarf, and we appeal to the acquisition of Chandra and XMM grating spectra to test this prediction. C1 Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. RP Mauche, CW (reprint author), Lawrence Livermore Natl Lab, L-43,7000 East Ave, Livermore, CA 94550 USA. NR 22 TC 6 Z9 6 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2002 VL 566 IS 1 BP L33 EP L36 DI 10.1086/339454 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520EG UT WOS:000173767200009 ER PT J AU Yseboodt, M de Viron, O Chin, TM Dehant, V AF Yseboodt, M de Viron, O Chin, TM Dehant, V TI Atmospheric excitation of the Earth's nutation: Comparison of different atmospheric models SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article DE Earth rotation; nutation; atmospheric angular momentum; singular spectral analysis ID FREE CORE NUTATION; OF-DAY CHANGES; PRESSURE; VARIABILITY; PRECESSION AB [1] Using the angular momentum approach, the effect of the atmosphere on the Earth's nutation is evaluated from five atmospheric circulation models. Five nutation frequencies are considered: the annual and semiannual prograde and retrograde and the terannual prograde. The atmospheric effect on the 18.6-year nutation is also evaluated from the only model that gives a long enough homogeneous series. The results obtained from the different models and a noninverted barometer ocean model are intercompared and compared with the residuals between the observed and computed nutations. The evaluation of the atmospheric effect on the Earth's nutation is shown to be above the observation precision, particularly at the annual frequency (prograde and retrograde) and the semiannual prograde frequency but is highly dependent on the model used, strengthening the importance of having a correct estimation for the atmospheric effects on nutation. The time evolution of the atmospheric excitation of the nutation is also studied, using a wavelet analysis and a sliding-window least squares method. We show that the fluctuations of the excited amplitude are above the level of precision of the observation. C1 Observ Royal Belgique, B-1180 Brussels, Belgium. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Yseboodt, M (reprint author), Observ Royal Belgique, Ave Circulaire 3, B-1180 Brussels, Belgium. EM marie.yseboodt@oma.be RI de Viron, Olivier/N-6647-2014 OI de Viron, Olivier/0000-0003-3112-9686 NR 21 TC 22 Z9 22 U1 1 U2 2 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 FEB 10 PY 2002 VL 107 IS B2 AR 2036 DI 10.1029/2000JB000042 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 609MP UT WOS:000178909800008 ER PT J AU Muller, HSP Cohen, EA AF Muller, HSP Cohen, EA TI The molecular properties of chlorosyl fluoride, FClO, as determined from the ground-state rotational spectrum SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID HARMONIC FORCE-FIELD; DIPOLE-MOMENT; HYPERFINE CONSTANTS; MICROWAVE-SPECTRUM; CHLORIDE FLUORIDE; SHIELDING TENSOR; SPIN-ROTATION; SPECTROSCOPY; DIOXIDE; QUADRUPOLE AB The pure rotational spectrum of chlorosyl fluoride was studied by microwave Fourier transform spectroscopy and conventional millimeter and submillimeter absorption spectroscopy. More than 100 rotational transitions for each isotopomer were observed involving Jless than or equal to73, 61 and K(a)less than or equal to19, 16 for (FClO)-Cl-35 and (FClO)-Cl-37, respectively. The analysis yielded precise rotational, centrifugal distortion, Cl-35,Cl-37 nuclear quadrupole, and F-19 and Cl-35,Cl-37 nuclear spin-rotation coupling constants. The spin-rotation constants were used to derive nuclear magnetic shielding values. All nonzero elements of the Cl quadrupole tensor were obtained, permitting its diagonalization. The dipole moment was determined by Stark measurements in the millimeter region. The ground-state average structure r(z) and an estimate of the equilibrium structure r(e) were calculated. The properties derived for FClO were compared with those of ClF3 and other related molecules. Structural parameters, harmonic force constants, the dipole moment, and the nuclear quadrupole coupling constants were also evaluated by means of quantum-chemical calculations. The results are in good agreement with experiment. (C) 2002 American Institute of Physics. C1 Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Muller, HSP (reprint author), Univ Cologne, Inst Phys 1, Zulpicher Str 77, D-50937 Cologne, Germany. NR 54 TC 7 Z9 7 U1 0 U2 2 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 FEB 8 PY 2002 VL 116 IS 6 BP 2407 EP 2416 PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 517PD UT WOS:000173618400012 ER PT J AU Yamaleev, NK AF Yamaleev, NK TI Optimal two-dimensional finite difference grids providing superconvergence SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE truncation error; optimal grid; finite difference approximation ID FLUID-DYNAMICS; 2 DIMENSIONS; FLOW AB A novel multidimensional grid adaptation method based on minimization of the leading truncation error term of arbitrary second- and higher-order finite difference approximations is proposed. The method does not explicitly require the truncation error estimate, but increases the design order of approximation globally by one, so that the same finite difference operator is superconvergent on the optimal grid. If the differential operator and the metric coefficients are evaluated identically by some hybrid approximation, the single optimal grid generator can be used in the entire computational domain and does not depend on points where the hybrid discretization switches from one approximation to another. If one family of the coordinate lines is given a priori, then the analytical optimal mapping is constructed for any consistent second-order finite difference approximation of delf in two dimensions. The present approach can be extended directly to nonlinear partial differential equations and three dimensions. Numerical calculations show that the truncation error obtained on the two-dimensional optimal grid is both superconvergent and reduced by several orders of magnitude in comparison with the uniform grid results for all the test examples considered. C1 NASA, Natl Res Council, Langley Res Ctr, Hampton, VA 23681 USA. RP Yamaleev, NK (reprint author), NASA, Natl Res Council, Langley Res Ctr, Mail Stop 128, Hampton, VA 23681 USA. NR 16 TC 0 Z9 0 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 1064-8275 J9 SIAM J SCI COMPUT JI SIAM J. Sci. Comput. PD FEB 6 PY 2002 VL 23 IS 5 BP 1707 EP 1730 AR PII S1064827500378994 DI 10.1137/S1064827500378994 PG 24 WC Mathematics, Applied SC Mathematics GA 525TE UT WOS:000174086400013 ER PT J AU Vodovotz, Y Vittadini, E Sachleben, JR AF Vodovotz, Y Vittadini, E Sachleben, JR TI Use of H-1 cross-relaxation nuclear magnetic resonance spectroscopy to probe the changes in bread and its components during aging SO CARBOHYDRATE RESEARCH LA English DT Article DE proton cross-relaxation NMR-1; bread staling; molecular mobility; starch retrogradation ID PROTON RELAXATION; STARCH; TRANSITION; AMYLOPECTIN; MOBILITY; H-1-NMR; AMYLOSE AB H-1 nuclear magnetic cross-relaxation spectroscopy was used to probe the molecular mobility/rigidity in bread and its components during storage. The Z-spectra lineshapes, attributed to the solid-like polymer fractions of the samples, differed for the bread, gelatinized waxy starch (GX), gelatinized wheat starch (GW), heated flour (HF), and heated gluten (HG). Upon storage, no change was observed in the Z-spectrum of the bread sample, while the Z-spectra for GX, GW, and HG increased in the width at half height of the decomposed broad component (increased rigidity). These trends in the Z-spectra detected by NMR were contradictory to the DSC results that showed an increase in amylopectin retrogradation enthalpy for all samples containing starch, including bread, These trends in the Z-spectra detected by NMR were not reflected by the DSC results that showed an increase in amylopectin retrogradation enthalpy for all samples, including bread. The differences in molecular mobility could not be therefore, due to recrystallized amylopectin and may be attributed to the role of gluten and/or redistribution of water in the amorphous regions of the samples, (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Ohio State Univ, Dept Food Sci & Technol, Columbus, OH 43210 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Ohio State Univ, Campus Chem Instrumentat Ctr, Columbus, OH 43210 USA. RP Vodovotz, Y (reprint author), Ohio State Univ, Dept Food Sci & Technol, 2015 Fyffe Court, Columbus, OH 43210 USA. EM vodovotz.1@osu.edu NR 21 TC 18 Z9 20 U1 1 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0008-6215 J9 CARBOHYD RES JI Carbohydr. Res. PD FEB 5 PY 2002 VL 337 IS 2 BP 147 EP 153 AR PII S0008-6215(01)00293-2 DI 10.1016/S0008-6215(01)00293-2 PG 7 WC Biochemistry & Molecular Biology; Chemistry, Applied; Chemistry, Organic SC Biochemistry & Molecular Biology; Chemistry GA 522VW UT WOS:000173918500009 PM 11814446 ER PT J AU Sergeev, AV Mitin, VV Karasik, BS AF Sergeev, AV Mitin, VV Karasik, BS TI Ultrasensitive hot-electron kinetic-inductance detectors operating well below the superconducting transition SO APPLIED PHYSICS LETTERS LA English DT Article ID TEMPORAL RELAXATION; QUANTUM DETECTORS; FILMS; NONEQUILIBRIUM; PHOTORESPONSE; BOLOMETER AB While most experimental studies of kinetic-inductance sensors have been limited so far by the temperature range near the superconducting transition, kinetic-inductance detectors can be very sensitive at temperatures well below the transition, where the number of equilibrium quasiparticles is exponentially small. In this regime, a shift of the quasiparticle chemical potential under radiation results in the change of the kinetic inductance. We modeled the noise characteristics of the kinetic-inductance detectors made from disordered superconducting Nb, NbC, and MoRe films. Low-phonon transparency of the interface between the superconductor and the substrate causes substantial retrapping of phonons providing high quantum efficiency and the operating time of similar to1 ms at approximate to1 K. Due to the small number of quasiparticles, the noise equivalent power of the detector determined by the quasiparticle generation-recombination noise can be as small as similar to10(-19) W/rootHz at He-4 temperatures. (C) 2002 American Institute of Physics. C1 Wayne State Univ, Dept Elect & Comp Engn, Detroit, MI 48202 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sergeev, AV (reprint author), Wayne State Univ, Dept Elect & Comp Engn, Detroit, MI 48202 USA. RI Karasik, Boris/C-5918-2011 NR 24 TC 43 Z9 43 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 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD FEB 4 PY 2002 VL 80 IS 5 BP 817 EP 819 DI 10.1063/1.1445462 PG 3 WC Physics, Applied SC Physics GA 517NW UT WOS:000173617700038 ER PT J AU Asaoka, Y Shikaze, Y Abe, K Anraku, K Fujikawa, M Fuke, H Haino, S Imori, M Izumi, K Maeno, T Makida, Y Matsuda, S Matsui, N Matsukawa, T Matsumoto, H Matsunaga, H Mitchell, J Mitsui, T Moiseev, A Motoki, M Nishimura, J Nozaki, M Orito, S Ormes, JF Saeki, T Sanuki, T Sasaki, M Seo, ES Sonoda, T Streitmatter, R Suzuki, J Tanaka, K Tanizaki, K Ueda, I Wang, JZ Yajima, Y Yamagami, Y Yamamoto, A Yamamoto, Y Yamato, K Yoshida, T Yoshimura, K AF Asaoka, Y Shikaze, Y Abe, K Anraku, K Fujikawa, M Fuke, H Haino, S Imori, M Izumi, K Maeno, T Makida, Y Matsuda, S Matsui, N Matsukawa, T Matsumoto, H Matsunaga, H Mitchell, J Mitsui, T Moiseev, A Motoki, M Nishimura, J Nozaki, M Orito, S Ormes, JF Saeki, T Sanuki, T Sasaki, M Seo, ES Sonoda, T Streitmatter, R Suzuki, J Tanaka, K Tanizaki, K Ueda, I Wang, JZ Yajima, Y Yamagami, Y Yamamoto, A Yamamoto, Y Yamato, K Yoshida, T Yoshimura, K TI Measurements of cosmic-ray low-energy antiproton and proton spectra in a transient period of solar field reversal SO PHYSICAL REVIEW LETTERS LA English DT Article ID MODULATION; ATMOSPHERE; MINIMUM; DRIFT AB The energy spectra of cosmic-ray low-energy antiprotons ((p) over bar 's) and protons (p's) have been measured by BESS in 1999 and 2000, during a period covering reversal at the solar magnetic field. Based an these measurements, a sudden increase of the (p) over bar /p flux ratio following the solar magnetic field reversal was observed, and it generally agrees with a drift model of the solar modulation. C1 Univ Tokyo, Tokyo 1130033, Japan. Kobe Univ, Kobe, Hyogo 6578501, Japan. High Energy Accelerator Res Org, Tsukuba, Ibaraki 3050801, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, College Pk, MD 20742 USA. Inst Space & Astronaut Sci, Kanagawa 2298510, Japan. RP Asaoka, Y (reprint author), Univ Tokyo, Tokyo 1130033, Japan. RI MOTOKI, Masakazu/B-4212-2009; OI Seo, Eun-Suk/0000-0001-8682-805X NR 33 TC 129 Z9 130 U1 0 U2 3 PU AMERICAN 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 FEB 4 PY 2002 VL 88 IS 5 AR 051101 DI 10.1103/PhysRevLett.88.051101 PG 4 WC Physics, Multidisciplinary SC Physics GA 518VA UT WOS:000173687500007 PM 11863712 ER PT J AU Chandrasekhar, P Zay, BJ Birur, GC Rawal, S Pierson, EA Kauder, L Swanson, T AF Chandrasekhar, P Zay, BJ Birur, GC Rawal, S Pierson, EA Kauder, L Swanson, T TI Large, switchable electrochromism in the visible through far-infrared in conducting polymer devices SO ADVANCED FUNCTIONAL MATERIALS LA English DT Article ID SIGNATURE CONTROL; SYSTEMS AB Advanced materials with large and dynamic variation in thermal properties, sought,for urgent defense and space applications, have heretofore been elusive. Conducting polymers (CPs) have shown some intrinsic variation of mid- to far-infrared (IR) signature in this respect, but the practical utilization of this has remained elusive. We report herein the first significant IR electrochromism in any material, to our knowledge, in the 0.4 through 45 mum region. This is seen in practical CP devices in the form of thin (<0.5 mm), flexible, entirely solid-state, variable area (1 cm(2) to 1 m(2)) flat panels. Typical properties include: very high reflectance variation; switching times <2 s; clyclabilities of 10(5) cycles; emittance variation from 0.32 to 0.79; solar absorptance variation from 0.39 to 0.79; operating temperatures of -35 to +85degreesC; durability against gamma-radiation to 7.6 Mrad, vacumn to 10(6) torr, and simulated solar wind (e.g., 6.5 x 10(16) e/cm(2) @ 10 keV). C1 Ashwin Ushas Corp Inc, Lakewood, NJ 08701 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Lockheed Martin Astronaut, Denver, CO 80201 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Chandrasekhar, P (reprint author), Ashwin Ushas Corp Inc, 500 James St,Unit 7, Lakewood, NJ 08701 USA. NR 37 TC 108 Z9 121 U1 1 U2 38 PU WILEY-V C H VERLAG GMBH PI WEINHEIM PA PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY SN 1616-301X J9 ADV FUNCT MATER JI Adv. Funct. Mater. PD FEB PY 2002 VL 12 IS 2 BP 95 EP 103 DI 10.1002/1616-3028(20020201)12:2<95::AID-ADFM95>3.0.CO;2-N PG 9 WC Chemistry, Multidisciplinary; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Chemistry; Science & Technology - Other Topics; Materials Science; Physics GA 526JB UT WOS:000174125900002 ER PT J AU Lazos, BS AF Lazos, BS TI Mean flow features around the inline wheels of four-wheel landing gear SO AIAA JOURNAL LA English DT Article AB Landing gear are noted to be a significant, sometimes dominant, airframe noise source for commercial aircraft. Aerodynamic noise is a direct result of the fluctuating flow and its interaction with surface components. Knowledge of the mean flow, however, can be used to aid in the determination of noise sources. The complex geometry of multiple-wheel-set landing gear has thus far precluded even this basic information. In this study the mean flow-field is determined in a streamwise plane surrounding the inline wheels of a generic four-wheel landing-gear configuration using digital particle image velocimetry. The velocity and vorticity fields highlight a vortex that persists between the wheels on the ground side of the axle midplane. The formation of this vortex is believed to result from the geometric asymmetry caused by the presence of the center support strut. Evidence is also presented that shows the vortex does not remain stationary, but oscillates between the fore and aft wheels. Its position is hypothesized to depend on the state of an unstable vorticity layer that develops on the ground side of the fore wheel. C1 NASA Langley Res Ctr, Hampton, VA 23681 USA. RP Lazos, BS (reprint author), NASA Langley Res Ctr, Hampton, VA 23681 USA. NR 10 TC 17 Z9 19 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD FEB PY 2002 VL 40 IS 2 BP 193 EP 198 DI 10.2514/2.1642 PG 6 WC Engineering, Aerospace SC Engineering GA 521RB UT WOS:000173854400001 ER PT J AU Watson, WR AF Watson, WR TI Three-dimensional rectangular duct code with application to impedance eduction SO AIAA JOURNAL LA English DT Article AB A zero flow, fully three-dimensional, variable impedance, rectangular duct aeroacoustics code that spans the frequency spectrum of interest in duct liner research is developed. The governing equations and boundary conditions in the duct are solved numerically using the finite element methodology. The methodology makes use of a state-of-the-art, sparse equation solver to obtain the capability to study high-frequency sound waves that may require millions of grid points for resolution. Noise suppression levels predicted from the code are in excellent agreement with those obtained from mode theory. Tile single-processor performance of the solver, relative to that of the more commonly used band solver, increases with frequency. At a frequency of 17 kHz, the band solver is 4.25 times slower and consumes 2.5 times more memory than the fully sparse equation solver. The duct aeroacoustics code is combined with an optimization algorithm and used successfully to educe the impedance spectrum of a ceramic liner. The primary problem with using the methodology to perform optimization studies at frequencies above 14 kHz is excessive central processor unit time. The results support the recommendation that research be directed toward exploitation of the multiprocessor capability of the solver to further reduce central processor unit time. C1 NASA Langley Res Ctr, Hampton, VA 23681 USA. RP Watson, WR (reprint author), NASA Langley Res Ctr, Hampton, VA 23681 USA. NR 10 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 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD FEB PY 2002 VL 40 IS 2 BP 217 EP 226 DI 10.2514/2.1663 PG 10 WC Engineering, Aerospace SC Engineering GA 521RB UT WOS:000173854400004 ER PT J AU DeBonis, JR Scott, JN AF DeBonis, JR Scott, JN TI Study of the error and efficiency of numerical schemes for computational aeroacoustics SO AIAA JOURNAL LA English DT Article ID FINITE-DIFFERENCE SCHEMES; RUNGE-KUTTA SCHEMES; LOW-DISSIPATION; ACOUSTICS AB Two types of high-order numerical schemes suitable for computational aeroacoustics are examined. Truncation error, efficiency, and the consequence of disparate temporal and spatial accuracy are discussed. The Gottlieb-Turkel 2-4 predictor-corrector scheme and two Runge-Kutta schemes (4-4 and 4-6) are used to solve the one-dimensional inviscid convection of a Gaussian pulse. For schemes with lower-order time stepping, the truncation error caused by the time stepping dominates the solution for optimum time steps. Reducing the time step can effectively increase the order of accuracy to that of the spatial discretization. However, this increased accuracy is balanced by an increase in the computational cost. The uniformly fourth-order-accurate Runge-Kutta scheme proves to be superior to the second-order temporal and fourth-order spatial accurate Gottlieb-Turkel scheme in terms of truncation error and computational efficiency. Increasing the spatial accuracy of the Runge-Kutta scheme to sixth order does not improve the efficiency of the scheme. To illustrate the relevance to a representative multidimensional problem, the Gottlieb-Turkel 2-4 and Runge-Kutta 4-4 schemes are then used to solve the unsteady axisymmetric Navier-Stokes equations for a supersonic jet. For this case the Runge-Kutta scheme provides better resolution of large-scale structures and requires less computational time. C1 NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. Ohio State Univ, Columbus, OH 43210 USA. RP DeBonis, JR (reprint author), NASA, John H Glenn Res Ctr, Lewis Field, Cleveland, OH 44135 USA. NR 22 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 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD FEB PY 2002 VL 40 IS 2 BP 227 EP 234 DI 10.2514/2.1664 PG 8 WC Engineering, Aerospace SC Engineering GA 521RB UT WOS:000173854400005 ER PT J AU Alexandrov, NM Lewis, RM AF Alexandrov, NM Lewis, RM TI Analytical and computational aspects of collaborative optimization for multidisciplinary design SO AIAA JOURNAL LA English DT Article ID MULTILEVEL OPTIMIZATION; OPTIMUM DESIGN AB Analytical features of multidisciplinary optimization (MDO) problem formulations have significant practical consequences for the ability of nonlinear programming algorithms to solve the resulting computational optimization problems reliably and efficiently. We explore this important but frequently overlooked fact using the notion of disciplinary autonomy. Disciplinary autonomy is a desirable goal in formulating and solving MDO problems; however, the resulting system optimization problems are frequently difficult to solve. We illustrate the implications of MDO problem formulation for the tractability of the resulting design optimization problem by examining a representative class of MDO problem formulations known as collaborative optimization, We also discuss an alternative problem formulation, distributed analysis optimization, that yields a more tractable computational optimization problem. C1 NASA Langley Res Ctr, Multidisciplinary Optimizat Branch, Hampton, VA 23681 USA. Coll William & Mary, Dept Math, Williamsburg, VA 23187 USA. RP Alexandrov, NM (reprint author), NASA Langley Res Ctr, Multidisciplinary Optimizat Branch, Mail Stop 159, Hampton, VA 23681 USA. EM n.alexandrov@larc.nasa.gov; buckaroo@math.wm.edu NR 35 TC 96 Z9 127 U1 1 U2 18 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD FEB PY 2002 VL 40 IS 2 BP 301 EP 309 DI 10.2514/2.1646 PG 9 WC Engineering, Aerospace SC Engineering GA 521RB UT WOS:000173854400013 ER PT J AU Andersson, L Wahlund, JE Clemmons, J Gustavsson, B Eliasson, L AF Andersson, L Wahlund, JE Clemmons, J Gustavsson, B Eliasson, L TI Electromagnetic waves and bursty electron acceleration: implications from Freja SO ANNALES GEOPHYSICAE LA English DT Article DE ionosphere; particle acceleraton; wave-particle interactions; magnetospheric physics; auroral phenomena ID KINETIC ALFVEN WAVES; PLASMA-WAVES; SATELLITE-OBSERVATIONS; AURORAL ARC; IONOSPHERE; ENERGIZATION; EMISSION AB Dispersive Alfven wave activity is identified in four dayside auroral oval events measured by the Freja satellite. The events are characterized by ion injection, bursty electron precipitation below about 1 keV, transverse ion heating and broadband extremely low frequency (ELF) emissions below the lower hybrid cutoff frequency (a few kHz). Large-scale density depletions/cavities, as determined by the Langmuir probe measurements, and strong electrostatic emissions are often observed simultaneously. A correlation study has been carried out between the E and B field fluctuations below 64Hz and 10Hz, respectively, (the DC instruments upper threshold) and the characteristics of the precipitating electrons. This study revealed that the energisation of electrons is indeed related to the broadband ELF emissions and that the electrostatic component plays a predominant role during very active magnetospheric conditions. Furthermore, the effect of the ELF electromagnetic emissions on the larger scale field-aligned current systems has been investigated, and it is found that such an effect cannot be detected. Instead, the Alfvenic activity creates a local region of field-aligned currents. It is suggested that dispersive Alfven waves set up these local field-aligned current regions and, in turn, trigger more electrostatic emissions during certain conditions. In these regions, ions are transversely heated, and large-scale density depletions/cavities may be created during especially active periods. C1 Swedish Inst Space Phys, Uppsala, Sweden. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Swedish Inst Space Phys, S-98128 Kiruna, Sweden. RP Andersson, L (reprint author), Univ Colorado, Atmospher & Space Phys Lab, Campus Box 392, Boulder, CO 80309 USA. OI Clemmons, James/0000-0002-5298-5222 NR 29 TC 14 Z9 14 U1 0 U2 1 PU EUROPEAN GEOPHYSICAL SOC PI KATLENBURG-LINDAU PA MAX-PLANCK-STR 13, 37191 KATLENBURG-LINDAU, GERMANY SN 0992-7689 J9 ANN GEOPHYS-GERMANY JI Ann. Geophys. PD FEB PY 2002 VL 20 IS 2 BP 139 EP 150 PG 12 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA 526XB UT WOS:000174154200001 ER PT J AU Srinivasan, RS Gerth, WA Powell, MR AF Srinivasan, RS Gerth, WA Powell, MR TI Mathematical model of diffusion-limited gas bubble dynamics in unstirred tissue with finite volume SO ANNALS OF BIOMEDICAL ENGINEERING LA English DT Article DE mathematical models; gas diffusion in tissue; decompression; sickness AB Models of gas bubble dynamics for studying decompression sickness have been developed by considering the bubble to be immersed in an extravascular tissue with diffusion-limited gas exchange between the bubble and the surrounding unstirred tissue. In previous versions of this two-region model, the tissue volume must be theoretically infinite, which renders the model inapplicable to analysis of bubble growth in a finite-sized tissue. We herein present a new two-region model that is applicable to problems involving finite tissue volumes. By introducing radial deviations to gas tension in the diffusion region surrounding the bubble, the concentration gradient can be zero at a finite distance from the bubble, thus limiting the tissue volume that participates in bubble-tissue gas exchange. It is shown that these deviations account for the effects of heterogeneous perfusion on gas bubble dynamics, and are required for the tissue volume to be finite. The bubble growth results from a difference between the bubble gas pressure and an average gas tension in the surrounding diffusion region that explicitly depends on gas uptake and release by the bubble. For any given decompression, the diffusion region volume must stay above a certain minimum in order to sustain bubble growth. (C) 2002 Biomedical Engineering Society. C1 Wyle Labs, Life Sci Syst & Serv, Houston, TX 77058 USA. USN, Expt Diving Unit, Panama City, FL USA. NASA, Environm Physiol Lab, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Srinivasan, RS (reprint author), Wyle Labs, Life Sci Syst & Serv, 1290 Hercules Dr,Suite 120, Houston, TX 77058 USA. NR 15 TC 8 Z9 8 U1 1 U2 3 PU BIOMEDICAL ENGINEERING SOC AMER INST PHYSICS PI MELVILLE PA STE 1 NO 1, 2 HUNTINGTON QUADRANGLE, MELVILLE, NY 11747-4502 USA SN 0090-6964 J9 ANN BIOMED ENG JI Ann. Biomed. Eng. PD FEB PY 2002 VL 30 IS 2 BP 232 EP 246 DI 10.1114/1.1451076 PG 15 WC Engineering, Biomedical SC Engineering GA 536ZY UT WOS:000174732800008 PM 11962775 ER PT J AU Huang, XQ Reinisch, BW Bilitza, D Benson, RF AF Huang, XQ Reinisch, BW Bilitza, D Benson, RF TI Electron density profiles of the topside ionosphere SO ANNALS OF GEOPHYSICS LA English DT Article; Proceedings Paper CT EGC 26th General Meeting CY MAR, 2001 CL NICE, FRANCE SP EGC DE electron density profile; topside ionosphere; ionogram processing ID IONOGRAMS AB The existing uncertainties about the electron density profiles in the topside ionosphere, i.e., in the height region from h(m)F(2) to similar to2000 km, require the search for new data sources. The ISIS and Alouette topside sounder satellites from the sixties to the eighties recorded millions of ionograms but most were not analyzed in terms of electron density profiles. In recent years an effort started to digitize the analog recordings to prepare the ionograms for computerized analysis. As of November 2001 about 350000 ionograms have been digitized from the original 7-track analog tapes. These data are available in binary and CDF format from the anonymous ftp site of the National Space Science Data Center. A search site and browse capabilities on CDAWeb assist the scientific usage of these data. All information and access links can be found at http://nssdc.gsfc.nasa.gov/space/isis/isisstatus.html. This paper describes the ISIS data restoration effort and shows how the digital ionograins are automatically processed into electron density profiles from satellite orbit altitude (1400 km for ISIS-2) down to the F peak. Because of the large volume of data an automated processing algorithm is imperative. The TOPside Ionogram Scaler with True height algorithm TOPIST software developed for this task is successfully scaling similar to70% of the ionograms. An much less thanediting processmuch greater than is available to manually scale the more difficult ionograms. The automated processing of the digitized ISIS ionograms is now underway, producing a much-needed database of topside electron density profiles for ionospheric modeling covering more than one solar cycle. C1 Univ Lowell, Ctr Atmospher Res, Lowell, MA 01854 USA. Raytheon ITSS, GSFC, Greenbelt, MD USA. RP Reinisch, BW (reprint author), Univ Lowell, Ctr Atmospher Res, 600 Suffolk St, Lowell, MA 01854 USA. NR 7 TC 27 Z9 28 U1 0 U2 2 PU EDITRICE COMPOSITORI BOLOGNA PI SIENA PA VIA SAN QUIRICO 13/2, I-53100 SIENA, ITALY SN 1593-5213 J9 ANN GEOPHYS-ITALY JI Ann. Geophys. PD FEB PY 2002 VL 45 IS 1 BP 125 EP 130 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 587ZU UT WOS:000177675600013 ER PT J AU Thompson, DK Beliaev, AS Giometti, CS Tollaksen, SL Khare, T Lies, DP Nealson, KH Lim, H Yates, J Brandt, CC Tiedje, JM Zhou, JZ AF Thompson, DK Beliaev, AS Giometti, CS Tollaksen, SL Khare, T Lies, DP Nealson, KH Lim, H Yates, J Brandt, CC Tiedje, JM Zhou, JZ TI Transcriptional and proteomic analysis of a ferric uptake regulator (fur) mutant of Shewanella oneidensis: Possible involvement of fur in energy metabolism, transcriptional regulation, and oxidative stress SO APPLIED AND ENVIRONMENTAL MICROBIOLOGY LA English DT Article ID UPTAKE REGULATION PROTEIN; 6FE-6S PRISMANE-CLUSTER; OUTER-MEMBRANE PROTEIN; EXOTOXIN-A PRODUCTION; INFLUENZAE TYPE-B; ESCHERICHIA-COLI; PSEUDOMONAS-AERUGINOSA; VIBRIO-CHOLERAE; SUPEROXIDE-DISMUTASE; SIDEROPHORE BIOSYNTHESIS AB The iron-directed, coordinate regulation of genes depends on the fur (ferric uptake regulator) gene product, which acts as an iron-responsive, transcriptional repressor protein. To investigate the biological function of a fur homolog in the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1, a fur knockout strain (FUR1) was generated by suicide plasmid integration into this gene and characterized using phenotype assays, DNA microarrays containing 691 arrayed genes, and two-dimensional polyacrylamide gel electrophoresis. Physiological studies indicated that FUR1 was similar to the wild-type strain when they were compared for anaerobic growth and reduction of various electron acceptors. Transcription profiling, however, revealed that genes with predicted functions in electron transport, energy metabolism, transcriptional regulation, and oxidative stress protection were either repressed (ccoNQ, etrA, cytochrome b and c maturation-encoding genes, qor, yiaY, sodB, rpoH, phoB, and chvI) or induced (yggW, pdhC, prpC, aceE, fdhD, and ppc) in the fur mutant. Disruption of fur also resulted in derepression of genes (hxuC, alcC,fhuA, hemR, irgA, and ompW) putatively involved in iron uptake. This agreed with the finding that the fur mutant produced threefold-higher levels of siderophore than the wild-type strain under conditions of sufficient iron. Analysis of a subset of the FUR1 proteome (i.e., primarily soluble cytoplasmic and periplasmic proteins) indicated that 11 major protein species reproducibly showed significant (P < 0.05) differences in abundance relative to the wild type. Protein identification using mass spectrometry indicated that the expression of two of these proteins (SodB and AlcC) correlated with the microarray data. These results suggest a possible regulatory role of S. oneidensis MR-1 Fur in energy metabolism that extends the traditional model of Fur as a negative regulator of iron acquisition systems. C1 Oak Ridge Natl Lab, Div Environm Sci, Oak Ridge, TN 37831 USA. Argonne Natl Lab, Biosci Div, Argonne, IL 60439 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Scripps Res Inst, Dept Cell Biol, La Jolla, CA 92037 USA. Michigan State Univ, Ctr Microbial Ecol, E Lansing, MI 48824 USA. RP Zhou, JZ (reprint author), Oak Ridge Natl Lab, Div Environm Sci, POB 2008, Oak Ridge, TN 37831 USA. EM zhouj@ornl.gov RI Beliaev, Alexander/E-8798-2016 OI Beliaev, Alexander/0000-0002-6766-4632 NR 73 TC 120 Z9 126 U1 3 U2 30 PU AMER SOC MICROBIOLOGY PI WASHINGTON PA 1752 N ST NW, WASHINGTON, DC 20036-2904 USA SN 0099-2240 EI 1098-5336 J9 APPL ENVIRON MICROB JI Appl. Environ. Microbiol. PD FEB PY 2002 VL 68 IS 2 BP 881 EP 892 DI 10.1128/AEM.68.2.881-892.2002 PG 12 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA 517AH UT WOS:000173588600056 PM 11823232 ER PT J AU Jordan, PM Puri, A AF Jordan, PM Puri, A TI Qualitative results for solutions of the steady Fisher-KPP equation SO APPLIED MATHEMATICS LETTERS LA English DT Article DE genetics; nonlinear analysis; nonlinear elliptic boundary value problems; population dynamics ID NON-LINEAR DIFFUSION; POPULATION-GENETICS AB In this letter, the homogeneous Dirichlet problem involving the N-dimensional Fisher-KPP equation, a reaction-diffusion model which arises in study of population genetics, is investigated for a class of nonlinear polynomial growth laws. Existence and uniqueness conditions for positive (i.e., physically realistic), steady-state solutions on finite domains, or habitats, are noted and stability questions are addressed. Of particular interest are habitats that can be modeled as open balls. For these cases, two relatively recent and powerful theorems from nonlinear analysis are employed to ascertain important qualitative information. Specifically, these solutions are shown to be strictly decreasing and radially symmetric, as well as achieving a stationary maximum at the habitat's center. In addition, the function spaces containing these solutions are determined. Last, the effects of the solution parameters are investigated numerically for the physically relevant cases of N = 2 and 3, the temporal evolution of a particular solution is illustrated, and connections to nuclear reactor science, as well as other fields, are noted. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Univ New Orleans, Dept Phys, New Orleans, LA 70148 USA. RP Jordan, PM (reprint author), USN, Res Lab, Stennis Space Ctr, Code 7181, Stennis Space Ctr, MS 39529 USA. NR 15 TC 10 Z9 11 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0893-9659 J9 APPL MATH LETT JI Appl. Math. Lett. PD FEB PY 2002 VL 15 IS 2 BP 239 EP 250 DI 10.1016/S0893-9659(01)00124-0 PG 12 WC Mathematics, Applied SC Mathematics GA 520MM UT WOS:000173785700019 ER PT J AU Stanford, SA Holden, B Rosati, P Eisenhardt, PR Stern, D Squires, G Spinrad, H AF Stanford, SA Holden, B Rosati, P Eisenhardt, PR Stern, D Squires, G Spinrad, H TI An X-ray selected galaxy cluster at z=1.11 in the ROSAT Deep Cluster Survey SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : clusters : general; galaxies : evolution; galaxies : formation; X-rays ID BAND LUMINOSITY FUNCTION; COLOR-MAGNITUDE RELATION; SPECTROPHOTOMETRIC STANDARDS; DISTANT CLUSTERS; EVOLUTION; MS-1054-03; Z=0.83 AB We report the discovery of an X-ray luminous galaxy cluster at z=1.11. RDCS J0910+5422 was selected as an X-ray cluster candidate in the ROSAT Deep Cluster Survey on the basis of its spatial extent in a ROSAT Position Sensitive Proportional Counter image. Deep optical and near-IR imaging reveal a red galaxy overdensity around the peak of the X-ray emission, with a significant excess of objects with J-K and I-K colors typical of elliptical galaxies at z similar to 1. Spectroscopic observations at the Keck II telescope secured nine galaxy redshifts in the range 1.095 < z < 1.120, yielding a mean cluster redshift of = 1.106. Eight of these galaxies lie within a 30" radius around the peak X-ray emission. A deep Chandra ACIS exposure on this field shows extended X-ray morphology and allows the X-ray spectrum of the intracluster medium to be measured. The cluster has bolometric luminosity Lx = 2.48(-0.26)(+0.33) x 10(44) ergs s(-1), temperature kT = 7.2(-1.4)(+2.2) keV, and mass within r = 1 Mpc of 7.0x10(14) M-circle dot (H-0 = 65 km s(-1) Mpc(-1), Omega(m) = 0.3, and Omega(Lambda)= 0.7). The spatial distribution of the cluster members is elongated, which is not due to an observational selection effect, and followed by the X-ray morphology. The X-ray surface brightness pro le and the spectrophotometric properties of the cluster members suggest that this is an example of a massive cluster in an advanced stage of formation with a hot intracluster medium and an old galaxy population already in place at z > 1. C1 Univ Calif Davis, Dept Phys, Davis, CA 95616 USA. European So Observ, D-85748 Munich, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. RP Stanford, SA (reprint author), Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94550 USA. NR 48 TC 63 Z9 63 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD FEB PY 2002 VL 123 IS 2 BP 619 EP 626 DI 10.1086/338442 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527WK UT WOS:000174210800004 ER PT J AU Smith, BJ Leisawitz, D Castelaz, MW Luttermoser, D AF Smith, BJ Leisawitz, D Castelaz, MW Luttermoser, D TI Infrared light curves of Mira variable stars from COBE DIRBE data SO ASTRONOMICAL JOURNAL LA English DT Article DE stars : AGB and post-AGB; Miras ID LONG-PERIOD VARIABLES; CIRCUMSTELLAR DUST SHELLS; IRAS LRS OBSERVATIONS; MASS-LOSS RATES; MU-M RANGE; SPECTRAL CLASSIFICATION; CARBON STARS; C-STARS; LIGHTCURVES; PHOTOMETRY AB We have used the COBE DIRBE database to derive near- and mid-infrared light curves for a well-defined sample of 38 infrared-bright Mira variable stars and compared with optical data from the AAVSO. In general the 3.5 and 4.9 mum DIRBE bandpasses provide the light curves with the best signal-to-noise ratio (S/N), with S/N decreasing with wavelength at longer wavelengths. At 25 mum good light curves are only available for similar to10% of our stars, and at wavelengths greater than or equal to60 mum extracting high quality light curves is not possible. The amplitude of variability is typically less in the near- infrared than in the optical and less in the mid-infrared than in the near- infrared, with decreasing amplitude with increasing wavelength. On average there are 0.20 +/- 0.01 mag variation at 1.25 mum and 0.14 +/- 0.01 mag variation at 4.9 mum for each magnitude variation in V. The observed amplitudes are consistent with results of recent theoretical models of circumstellar dust shells around Mira variables. For a few stars in our sample we find clear evidence of time lags between the optical and near- infrared maxima of phase similar to0.05 +/- 0.13, with no lags in the minima. For three stars mid-infrared maximum appears to occur slightly before that in the near- infrared, but after optical maximum. We find three examples of secondary maxima in the rising portions of the DIRBE light curves, all of which have optical counterparts in the AAVSO data, supporting the hypothesis that they are due to shocks rather than newly formed dust layers. We find no conclusive evidence for rapid (hours to days) variations in the infrared brightnesses of these stars. C1 E Tennessee State Univ, Dept Phys & Astron, Johnson City, TN 37614 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Pisgah Astron Res Inst, Rosman, NC USA. E Tennessee State Univ, Dept Phys & Astron, Johnson City, TN 37614 USA. RP Smith, BJ (reprint author), E Tennessee State Univ, Dept Phys & Astron, Box 70652, Johnson City, TN 37614 USA. EM smithbj@etsu.edu; leisawitz@stars.gsfc.nasa.gov; mcastelaz@pari.edu; lutter@etsu.edu NR 56 TC 35 Z9 35 U1 0 U2 1 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 FEB PY 2002 VL 123 IS 2 BP 948 EP 964 DI 10.1086/338647 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527WK UT WOS:000174210800027 ER PT J AU Pittard, JM Corcoran, MF AF Pittard, JM Corcoran, MF TI In hot pursuit of the hidden companion of eta Carinae: An X-ray determination of the wind parameters SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : binaries : general; stars : early-type; stars : individual : eta Carinae; stars : Wolf-Rayet; X-rays : stars ID STELLAR WIND; ASCA OBSERVATIONS; GAMMA(2) VELORUM; COLLIDING WINDS; O-STARS; EMISSION; BINARY; SIMULATIONS; OUTBURST; SPECTRUM AB We present X-ray spectral fits to a recently obtained Chandra grating spectrum of eta Carinae, one of the most massive and powerful stars in the Galaxy and which is strongly suspected to be a colliding wind binary system. Hydrodynamic models of colliding winds are used to generate synthetic X-ray spectra for a range of mass-loss rates and wind velocities. They are then fitted against newly acquired Chandra grating data. We find that due to the low velocity of the primary wind (approximate to500 km s(-1)), most of the observed X-ray emission appears to arise from the shocked wind of the companion star. We use the duration of the lightcurve minimum to fix the wind momentum ratio at eta=0.2. We are then able to obtain a good fit to the data by varying the mass-loss rate of the companion and the terminal velocity of its wind. We find that (M)over dot(2) approximate to 10(-5) M-circle dot yr(-1) and v(infinity2) approximate to 3000 km s(-1). With observationally determined values of approximate to500-700 km s(-1) for the velocity of the primary wind, our fit implies a primary mass-loss rate of (M)over dot(1) approximate to 2.5x10(-4) M-circle dot yr(-1). This value is smaller than commonly inferred, although we note that a lower mass-loss rate can reduce some of the problems noted by Hillier et al. (2001) when a value as high as 10(-3) M-circle dot yr(-1) is used. The wind parameters of the companion are indicative of a massive star which may or may not be evolved. The line strengths appear to show slightly sub-solar abundances, although this needs further confirmation. Based on the over-estimation of the X-ray line strengths in our model, and re-interpretation of the HST/FOS results, it appears that the Homunculus nebula was produced by the primary star. C1 Univ Leeds, Dept Phys & Astron, Leeds LS2 9JT, W Yorkshire, England. Univ Space Res Assoc, Lanham, MD 20706 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Pittard, JM (reprint author), Univ Leeds, Dept Phys & Astron, Woodhouse Lane, Leeds LS2 9JT, W Yorkshire, England. NR 54 TC 150 Z9 150 U1 0 U2 0 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD FEB PY 2002 VL 383 IS 2 BP 636 EP 647 DI 10.1051/0004-6361:20020025 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 527KC UT WOS:000174184400026 ER PT J AU Demoulin, P Mandrini, CH van Driel-Gesztelyi, L Thompson, BJ Plunkett, S Kovari, Z Aulanier, G Young, A AF Demoulin, P Mandrini, CH van Driel-Gesztelyi, L Thompson, BJ Plunkett, S Kovari, Z Aulanier, G Young, A TI What is the source of the magnetic helicity shed by CMEs? The long-term helicity budget of AR 7978 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE Sun : corona; Sun : coronal mass ejections (CMEs); Sun : magnetic fields; solar-terrestrial relations ID CORONAL MASS EJECTIONS; FORCE-FREE FIELDS; CONSTANT-ALPHA; ACTIVE-REGION; CLOUDS; MODEL; EVOLUTION; ROTATION; MISSION; PROPAGATION AB An isolated active region (AR) was observed on the Sun during seven rotations, starting from its birth in July 1996 to its full dispersion in December 1996. We analyse the long-term budget of the AR relative magnetic helicity. Firstly, we calculate the helicity injected by differential rotation at the photospheric level using MDI/SoHO magnetograms. Secondly, we compute the coronal magnetic field and its helicity selecting the model which best fits the soft X-ray loops observed with SXT/Yohkoh. Finally, we identify all the coronal mass ejections (CMEs) that originated from the AR during its lifetime using LASCO and EIT/SoHO. Assuming a one to one correspondence between CMEs and magnetic clouds, we estimate the magnetic helicity which could be shed via CMEs. We find that differential rotation can neither provide the required magnetic helicity to the coronal field (at least a factor 2.5 to 4 larger), nor to the field ejected to the interplanetary space (a factor 4 to 20 larger), even in the case of this AR for which the total helicity injected by differential rotation is close to the maximum possible value. However, the total helicity ejected is equivalent to that of a twisted flux tube having the same magnetic flux as the studied AR and a number of turns in the interval [0.5, 2.0]. We suggest that the main source of helicity is the inherent twist of the magnetic flux tube forming the active region. This magnetic helicity is transferred to the corona either by the continuous emergence of the flux tube for several solar rotations (i.e. on a time scale much longer than the classical emergence phase), or by torsional Alfven waves. C1 Observ Paris, DASOP, Meudon Sect, CNRS,URA 2080, F-92195 Meudon, France. Inst Astron & Fis Espacio, RA-1428 Buenos Aires, DF, Argentina. UCL, Mullard Space Sci Lab, London, England. Konkoly Observ Budapest, Budapest, Hungary. Katholieke Univ Leuven, Ctr Plasma Astrophys, B-3001 Heverlee, Belgium. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USN, Res Lab, USRA, Washington, DC 20375 USA. RP Demoulin, P (reprint author), Observ Paris, DASOP, Meudon Sect, CNRS,URA 2080, F-92195 Meudon, France. EM pascal.demoulin@obspm.fr; mandrini@iafe.uba.ar RI Thompson, Barbara/C-9429-2012; OI Kovari, Zsolt/0000-0001-5160-307X; Demoulin, Pascal/0000-0001-8215-6532 NR 65 TC 156 Z9 161 U1 1 U2 2 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 FEB PY 2002 VL 382 IS 2 BP 650 EP 665 DI 10.1051/0004-6361:20011634 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 516PG UT WOS:000173561700022 ER PT J AU Blasi, P AF Blasi, P TI A semi-analytical approach to non-linear shock acceleration SO ASTROPARTICLE PHYSICS LA English DT Article DE cosmic rays; high energy; origin; acceleration ID COSMIC-RAYS; PARTICLE-ACCELERATION; OBLIQUE SHOCKS; ORIGIN; INJECTION; SN-1006 AB Shocks in astrophysical fluids can generate suprathermal particles by first order (or diffusive) Fermi acceleration. In the test particle regime there is a simple relation between the spectrum of the accelerated particles and the jump conditions at the shock. This simple picture becomes complicated when the pressure of the accelerated particles becomes comparable with the pressure of the shocked fluid, so that the non-linear backreaction of the particles becomes non-negligible and the spectrum is affected in a substantial way. Though only numerical simulations can provide a fully self-consistent approach, a more direct and easily applicable method would be very useful, and would allow to take into account the non-linear effects in particle acceleration in those cases in which they are important and still neglected. We present here a simple semi-analytical model that deals with these non-linear effects in a quantitative way. This new method, while compatible with the previous simplified results, also provides a satisfactory description of the results of numerical simulations of shock acceleration. (C) 2002 Elsevier Science B.V. All rights reserved. C1 NASA, Fermilab Theoret Astrophys Grp, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. RP Blasi, P (reprint author), NASA, Fermilab Theoret Astrophys Grp, Fermi Natl Accelerator Lab, POB 500, Batavia, IL 60510 USA. EM blasi@fnal.gov RI Blasi, Pasquale/O-9345-2015 OI Blasi, Pasquale/0000-0003-2480-599X NR 29 TC 94 Z9 94 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-6505 EI 1873-2852 J9 ASTROPART PHYS JI Astropart Phys. PD FEB PY 2002 VL 16 IS 4 BP 429 EP 439 DI 10.1016/S0927-6505(01)00127-X PG 11 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 509JF UT WOS:000173144100008 ER PT J AU Brotherton, MS Green, RF Kriss, GA Oegerle, W Kaiser, ME Zheng, W Hutchings, JB AF Brotherton, MS Green, RF Kriss, GA Oegerle, W Kaiser, ME Zheng, W Hutchings, JB TI Far Ultraviolet Spectroscopic Explorer observations of the Seyfert 1.5 galaxy NGC 5548 in a low state SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (NGC 5548); galaxies : nuclei; galaxies : Seyfert; quasars : absorption lines; ultraviolet : galaxies; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; NARROW-LINE REGION; INTRINSIC ABSORPTION; NGC-5548; EMISSION; SPECTRA; SPECTROGRAPH; COMPONENTS; IONIZATION; MODELS AB We present far-ultraviolet spectra of the Seyfert 1.5 galaxy NGC 5548 obtained in 2000 June with the Far Ultraviolet Spectroscopic Explorer (FUSE). Our data span the observed wavelength range 915-1185 Angstrom at a resolution of similar to20 km s(-1). The spectrum shows a weak continuum and emission from O VI lambdalambda1032, 1038, C III lambda977, and He II lambda1085. The FUSE data were obtained when the active galactic nucleus was in a low state, which has revealed strong, narrow O VI emission lines. We also resolve intrinsic, associated absorption lines of O VI and the Lyman series. Several distinct kinematic components are present, spanning a velocity range of similar to0 to -1300 km s-1 relative to the systemic velocity, with kinematic structure similar to that seen in previous observations of longer wavelength ultraviolet (UV) lines. We explore the relationships between the far-UV absorbers and those seen previously in the UV and X-rays. We find that the high-velocity UV absorption component is consistent with being low ionization, contrary to some previous claims, and is consistent with its nondetection in high-resolution X-ray spectra. The intermediate-velocity absorbers, at -300 to -400 km s(-1), show H I and O VI column densities consistent with having contributions from both a high-ionization X-ray absorber and a low-ionization UV absorber. No single far-UV-absorbing component can be solely identified with the X-ray absorber. C1 Kitt Peak Natl Observ, Natl Opt Astron Observ, Tucson, AZ 85726 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Johns Hopkins Univ, Ctr Astrophys Sci, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V9E 2E7, Canada. RP Brotherton, MS (reprint author), Kitt Peak Natl Observ, Natl Opt Astron Observ, POB 26732,950 M Cherry Ave, Tucson, AZ 85726 USA. RI Oegerle, William/C-9070-2012 NR 35 TC 26 Z9 26 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2002 VL 565 IS 2 BP 800 EP 807 DI 10.1086/324694 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520DP UT WOS:000173765600012 ER PT J AU Wilson, CA Finger, MH Gogus, E Woods, PM Kouveliotou, C AF Wilson, CA Finger, MH Gogus, E Woods, PM Kouveliotou, C TI Serendipitous detections of XTE J1906+09 with the Rossi X-Ray Timing Explorer SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; pulsars : individual (XTE J1906+09); X-rays : binaries ID INTERSTELLAR-MEDIUM; GRO J2058+42; PULSAR; RXTE; OUTBURSTS; DISCOVERY; EMISSION; ORBIT; PERFORMANCE; PERIODS AB In 1996 during Rossi X-Ray Timing Explorer (RXTE) observations of SGR 1900+14, the 89 s X-ray pulsar XTE J1906+09 was discovered. As a result of monitoring campaigns of SGR 1900+14, XTE J1906+09 was also monitored regularly in 1996 September, 1998 May-June, 1998 August-1999 July, and 2000 March-2001 January. A search for pulsations in these observations resulted in detections of only the two previously reported outbursts in 1996 September and 1998 August-September. Pulsed flux upper limits for the remaining observations indicate that XTE J1906+09 is a transient X-ray pulsar and therefore likely has a Be star companion. XTE J1906+09 was not detected with the RXTE all-sky monitor. Pulse-timing analysis of the second outburst revealed a sinusoidal signature in the pulse frequencies that is likely produced by periastron passage in an orbit. Fits to pulse phases using an orbital model and quadratic phase model have chi(2) minima at orbital periods of 26-30 days for fixed mass functions of 5, 10, 15, and 20 M.. The pulse shape showed intensity- and energy-dependent variations. Pulse-phase spectroscopy was used to quantify the energy-dependent variations. The phase-averaged spectrum, using the pulse minimum spectrum as the background spectrum to eliminate effects from SGR 1900+14 and the Galactic ridge, was well fitted by an absorbed power law with a high-energy cutoff with column density N-H = (6 +/- 1) x 10(22) cm(-2), a photon index of 1.01 +/- 0.08, cutoff energy E-cut = 11 +/- 1 keV, and e-folding energy E-fold = 19 +/- 4 keV. Estimated 2-10 keV peak fluxes, corrected for contributions from the Galactic ridge and SGR 1900+14, are 6 x 10(-12) and 1.1 x 10(-10) ergs cm(-2) s(-1) for the 1996 and 1998 outbursts, respectively. XTE J1906+09 may be a member of an unusual class of Be/X-ray binaries that do not lie on the general spin period versus orbital period correlation with the majority of Be/X-ray binaries. C1 Natl Space Sci & Technol Ctr, Space Sci Res Ctr, SD 50, Huntsville, AL 35805 USA. RP NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. EM colleen.wilson-hodge@msfc.nasa.gov NR 37 TC 4 Z9 4 U1 0 U2 1 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 FEB 1 PY 2002 VL 565 IS 2 BP 1150 EP 1160 DI 10.1086/324707 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520DP UT WOS:000173765600043 ER PT J AU Wu, K Soria, R Campbell-Wilson, D Hannikainen, D Harmon, BA Hunstead, R Johnston, H McCollough, M McIntyre, V AF Wu, K Soria, R Campbell-Wilson, D Hannikainen, D Harmon, BA Hunstead, R Johnston, H McCollough, M McIntyre, V TI The 1998 outburst of XTE J1550-564: A model based on multiwavelength observations SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : close; black hole physics; stars : individual (XTE J1550-564); stars : magnetic fields; X-rays : stars ID ADVECTION-DOMINATED ACCRETION; BLACK-HOLE CANDIDATE; X-RAY; OPTICAL OBSERVATIONS; BINARIES; MATTER; DISKS AB The 1998 September outburst of the black hole X-ray binary XTE J1550-564 was monitored at X-ray, optical, and radio wavelengths. We divide the outburst sequence into five phases and discuss their multiwavelength properties. The outburst starts with a hard X-ray spike, while the soft X-ray flux rises with a longer timescale. We suggest that the onset of the outburst is determined by an increased mass transfer rate from the companion star, but the outburst morphology is determined by the distribution of specific angular momentum in the accreting matter. The companion in XTE J1550-564 is likely to be an active magnetic star, with a surface field strong enough to influence the dynamics of mass transfer. We suggest that its magnetic field can create a magnetic bag capable of confining gas inside the Roche lobe of the primary. The impulsive rise in the hard X-rays is explained by the inflow of material with low angular momentum onto the black hole, on a free-fall timescale, when the magnetic confinement breaks down. At the same time, high angular momentum matter, transferred via ordinary Roche lobe overflow, is responsible for the formation of a disk. C1 UCL, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England. Univ Sydney, Sch Phys, Sydney, NSW 2006, Australia. Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. CSIRO, Australia Telescope Natl Facil, Epping, NSW 1710, Australia. RP UCL, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England. EM kw@mssl.ucl.ac.uk; rs1@mssl.ucl.ac.uk NR 37 TC 43 Z9 43 U1 0 U2 1 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 FEB 1 PY 2002 VL 565 IS 2 BP 1161 EP 1168 DI 10.1086/324328 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520DP UT WOS:000173765600044 ER PT J AU Harvin, JA Gies, DR Bagnuolo, WG Penny, LR Thaller, ML AF Harvin, JA Gies, DR Bagnuolo, WG Penny, LR Thaller, ML TI Tomographic separation of composite spectra. VIII. The physical properties of the massive compact binary in the triple star system HD 36486 (delta orionis A) SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : eclipsing; binaries : spectroscopic; stars : early-type; stars : fundamental parameters; stars : individual (delta Orionis, HD 36486); ultraviolet : stars ID ICCD SPECKLE OBSERVATIONS; PEAK 4-M TELESCOPE; O-STARS; INTERFEROMETRIC MEASUREMENTS; STELLAR WINDS; ULTRAVIOLET; VELOCITIES; EMISSION; MAJORIS; MODELS AB We present the first double-lined spectroscopic orbital elements for the central binary in the massive triple delta Orionis A. The solutions are based on fits of cross-correlation functions of IUE high-dispersion UV spectra and He I lambda6678 profiles. The orbital elements for the primary agree well with previous results, and in particular, we confirm the apsidal advance with a period of 224.5 +/- 4.5 yr. We also present tomographic reconstructions of the primary and secondary stars' spectra that confirm the O9.5 II classification of the primary and indicate a B0.5 III type for the secondary. The relative line strengths between the reconstructed spectra suggest magnitude differences of Deltam = -2.5 log (F-s/F-p) = 2.6 +/- 0.2 in the UV and Deltam = 2.5 +/- 0.3 at 6678 Angstrom. The widths of the UV cross-correlation functions are used to estimate the projected rotational velocities, V sin i = 157 +/- 6 and 138 +/- 16 km s(-1) for the primary and secondary, respectively (which implies that both the primary and the secondary rotate faster than the orbital motion). We used the spectroscopic results to make a constrained fit of the Hipparcos light curve of this eclipsing binary, and the model fits limit the inclination to the range i = 67degrees-77degrees. The lower limit corresponds to a near Roche-filling configuration that has an absolute magnitude that is consistent with the photometrically determined distance to Ori OB1b, the Orion Belt cluster in which delta Ori resides. The i = 67degrees solution results in masses of and both of which are substantially below M-p = 11.2 M-s = 5.6 M., the expected masses for stars of their luminosity. The binary may have experienced a mass ratio reversal caused by case A Roche lobe overflow or the system may have suffered extensive mass loss through a binary interaction (perhaps during a common envelope phase) in which most of the primary's mass was lost from the system rather than transferred to the secondary. We also made three-component reconstructions to search for the presumed stationary spectrum of the close visual companion delta Ori Ab (Hei 42 Ab). There is no indication of the spectral lines of this tertiary in the UV spectrum, but a broad and shallow feature is apparent in the reconstruction of He I lambda6678 indicative of an early B-type star. The tertiary may be a rapid rotator (V sin i approximate to 300 km s(-1)) or a spectroscopic binary. C1 Georgia State Univ, Dept Phys & Astron, Ctr High Angular Resolut Astron, Atlanta, GA 30303 USA. Coll Charleston, Dept Phys & Astron, Charleston, SC 29424 USA. CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Harvin, JA (reprint author), Georgia State Univ, Dept Phys & Astron, Ctr High Angular Resolut Astron, Atlanta, GA 30303 USA. NR 67 TC 35 Z9 36 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2002 VL 565 IS 2 BP 1216 EP 1230 DI 10.1086/324705 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520DP UT WOS:000173765600049 ER PT J AU Suess, ST Nerney, SF AF Suess, ST Nerney, SF TI Stagnation flow in streamer boundaries SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; Sun : corona; Sun : magnetic fields ID SOLAR-WIND; CORONAL STREAMER; MODEL AB Flow tubes adjacent to closed magnetic field lines on the boundaries of streamers can have spreading factors that change rapidly with height. Numerical models in this thin layer are subject to uncertainties. Here we use an analytic model of magnetically closed and adjacent open regions to compute the spreading factor close to the closed field lines and the flow on the open field lines. We are able to recover the shape of the closed field region, or helmet, and show the evolution of the helmet under slowly increasing temperature. We also show why and when stagnation flow can occur in the vicinity of the cusp at the top of the helmet. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Ohio Univ, Dept Phys, Lancaster, OH 43130 USA. RP Suess, ST (reprint author), NASA, George C Marshall Space Flight Ctr, SD50, Huntsville, AL 35812 USA. NR 19 TC 20 Z9 20 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2002 VL 565 IS 2 BP 1275 EP 1288 DI 10.1086/324697 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520DP UT WOS:000173765600054 ER PT J AU Harker, DE Desch, SJ AF Harker, DE Desch, SJ TI Annealing of silicate dust by nebular shocks at 10 AU SO ASTROPHYSICAL JOURNAL LA English DT Article DE comets : general; dust, extinction; shock waves; solar system : formation ID HALE-BOPP; OPTICAL-PROPERTIES; SOLAR NEBULA; COMETS; GRAINS; DISKS; STARS; COMA; PREPERIHELION; MINERALOGY AB Silicate dust grains in the interstellar medium are known to be mostly amorphous, yet crystalline silicate grains have been observed in many long-period comets and in protoplanetary disks. Annealing of amorphous silicate grains into crystalline grains requires temperatures of greater than or similar to1000 K, but exposure of dust grains in comets to such high temperatures is incompatible with the generally low temperatures experienced by comets. This has led to the proposal of models in which dust grains were thermally processed near the proto-Sun, then underwent considerable radial transport until they reached the gas giant planet region where the long-period comets originated. We hypothesize instead that silicate dust grains were annealed in situ by shock waves triggered by gravitational instabilities. We assume a shock speed of 5 km s(-1), a plausible value for shocks driven by gravitational instabilities. We calculate the peak temperatures of micron and submicron amorphous pyroxene grains of chondritic composition under conditions typical in protoplanetary disks at 5-10 AU. Our results also apply to chondritic amorphous olivine grains. We show that in situ thermal annealing of submicron- and micron-sized silicate dust grains can occur, obviating the need for large-scale radial transport. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. RP Harker, DE (reprint author), NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. OI Harker, David/0000-0001-6397-9082 NR 41 TC 102 Z9 102 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2002 VL 565 IS 2 BP L109 EP L112 DI 10.1086/339363 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520EA UT WOS:000173766600011 ER PT J AU Piacentini, F Ade, PAR Bhatia, RS Bock, JJ Boscaleri, A Cardoni, P Crill, BP de Bernardis, P Del Castillo, H De Troia, G Farese, P Giacometti, M Hivon, EF Hristov, VV Iacoangeli, A Lange, AE Masi, S Mauskopf, PD Miglio, L Netterfield, CB Palangio, P Pascale, E Raccanelli, A Rao, S Romeo, G Ruhl, J Scaramuzzi, F AF Piacentini, F Ade, PAR Bhatia, RS Bock, JJ Boscaleri, A Cardoni, P Crill, BP de Bernardis, P Del Castillo, H De Troia, G Farese, P Giacometti, M Hivon, EF Hristov, VV Iacoangeli, A Lange, AE Masi, S Mauskopf, PD Miglio, L Netterfield, CB Palangio, P Pascale, E Raccanelli, A Rao, S Romeo, G Ruhl, J Scaramuzzi, F TI The BOOMERANG North America instrument: A balloon-borne bolometric radiometer optimized for measurements of cosmic background radiation anisotropies from 0.degrees 3 to 4 degrees SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE balloons; cosmic microwave background; cosmology : observations; instrumentation : photometers ID DIFFERENTIAL MICROWAVE RADIOMETERS; INFRARED BOLOMETERS; TEST FLIGHT; MILLIMETER; SPECTRUM; MAPS AB We describe the BOOMERANG North America instrument, a balloon-borne bolometric radiometer designed to map the cosmic microwave background (CMB) radiation with 0.degrees3 resolution over a significant portion of the sky. This receiver employs new technologies in bolometers, readout electronics, millimeter-wave optics and filters, cryogenics, scan, and attitude reconstruction. All these subsystems are described in detail in this paper. The system has been fully calibrated in flight using a variety of techniques, which are described and compared. Using this system, we have obtained a measurement of the first peak in the CMB angular power spectrum in a single, few hour long balloon flight. The instrument described here was a prototype of the BOOMERANG Long Duration Balloon experiment. C1 Univ Roma La Sapienza, Dipartimento Fis, I-00185 Rome, Italy. Univ London Queen Mary & Westfield Coll, Dept Phys, London E1 4NS, England. CALTECH, Dept Phys Math & Astron, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CNR, IROE, I-50127 Florence, Italy. Ente Nazl Energie Alternat, I-00044 Frascati, Italy. Univ Wales Coll Cardiff, Dept Phys & Astron, Cardiff CF34 3YB, S Glam, Wales. Univ Toronto, Dept Astron, Toronto, ON M5S 3H8, Canada. Ist Nazl Geofis, I-00143 Rome, Italy. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. RP Piacentini, F (reprint author), Univ Roma La Sapienza, Dipartimento Fis, Piazzale Aldo Moro 2, I-00185 Rome, Italy. OI Masi, Silvia/0000-0001-5105-1439; de Bernardis, Paolo/0000-0001-6547-6446; ROMEO, Giovanni/0000-0002-5535-7803; Piacentini, Francesco/0000-0002-5444-9327 NR 32 TC 36 Z9 36 U1 0 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD FEB PY 2002 VL 138 IS 2 BP 315 EP 336 DI 10.1086/324265 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 523NC UT WOS:000173959700007 ER PT J AU Morgun, VV Voronin, LI Kaspranskiy, RR Pool, SL Barratt, MR Navinkov, AL AF Morgun, VV Voronin, LI Kaspranskiy, RR Pool, SL Barratt, MR Navinkov, AL TI Development of US-Russian medical support procedures for long-duration spaceflight: The NASA-Mir experience SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE space medicine; spaceflight; medical certification; International Space Station AB As the Russian Space Agency and the U.S. National Aeronautics and Space Administration began in the mid-1990s to plan a preliminary cooperative flight program in anticipation of the International Space Station, programmatic and philosophical differences became apparent in the technical and medical approaches of the two agencies. This paper briefly describes some of these differences and the process by which the two sides resolved differences in their approaches to the medical selection and certification of NASA-Mir crewmembers. These negotiations formed the basis for developing policies on other aspects of the medical support function for international missions, including crew training, preflight and postflight data collection, and rehabilitation protocols. The experience gained through this cooperative effort has been invaluable for developing medical care capabilities for the International Space Station. C1 NASA, Lyndon B Johnson Space Ctr, Space & Life Sci Directorate, Houston, TX 77058 USA. Yu A Gagarin Cosmonaut Training Ctr, Star City 141160, Russia. NASA, Lyndon B Johnson Space Ctr, Astronaut Off, Houston, TX 77058 USA. Wyle Labs, Houston, TX USA. RP Morgun, VV (reprint author), NASA, Lyndon B Johnson Space Ctr, Space & Life Sci Directorate, Mail Code SA, Houston, TX 77058 USA. NR 5 TC 5 Z9 5 U1 2 U2 4 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD FEB PY 2002 VL 73 IS 2 BP 147 EP 155 PG 9 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 517KZ UT WOS:000173610900011 PM 11846184 ER PT J AU Burgmann, R Ayhan, ME Fielding, EJ Wright, TJ McClusky, S Aktug, B Demir, C Lenk, O Turkezer, A AF Burgmann, R Ayhan, ME Fielding, EJ Wright, TJ McClusky, S Aktug, B Demir, C Lenk, O Turkezer, A TI Deformation during the 12 November 1999 Duzce, Turkey, earthquake, from GPS and InSAR data SO BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA LA English DT Article ID NORTH-ANATOLIAN FAULT; MARMARA SEA REGION; 17 AUGUST 1999; RADAR INTERFEROMETRY; SOUTHERN-CALIFORNIA; EARTHS SURFACE; SEISMIC HAZARD; HALF-SPACE; SLIP; DISPLACEMENT AB Only 87 days after the M-w 7.5, 17 August 1999 Izmit earthquake, the Duzce earthquake ruptured a ca. 40-km-long adjoining strand of the North Anatolian fault (NAF) system to the east. We used displacements of 50 Global Positioning System (IGPS) sites together with interferometric synthetic aperture radar (InSAR) range-change data spanning the event to estimate the geometry and slip distribution of the coseismic rupture. Postseismic deformation transients from the Duzce earthquake and the preceding Izmit event that are included in some of the measurements are corrected for using dislocation models fit to GPS data spanning the various time periods. Nonlinear inversions for fault geometry indicate that the rupture occurred on a ca. 54degrees north-dipping oblique normal, right-lateral fault. Distributed-slip inversions indicate maximum strike slip near the center of the Duzce fault close to the earthquake hypocenter. Slip magnitude and depth of faulting decrease to the west and east of the hypocenter. Both GPS and InSAR data suggest that normal slip is restricted to the shallow portion of the rupture. The Duzce earthquake had the highest slip-to-rupture-length ratio of any historic earthquake along the NAF. C1 Univ Calif Berkeley, Dept Earth & Planetary Sci & Berkeley, Seismol Lab, Berkeley, CA 94720 USA. Gen Command Mapping, Dept Geodesy, Ankara, Turkey. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. MIT, Dept Earth Atmospher & Planetary Sci, Earth Resource Lab, Cambridge, MA 02139 USA. Univ Oxford, Dept Earth Sci, Oxford, England. RP Burgmann, R (reprint author), Univ Calif Berkeley, Dept Earth & Planetary Sci & Berkeley, Seismol Lab, 301 McCone Hall, Berkeley, CA 94720 USA. RI Wright, Tim/A-5892-2011; Fielding, Eric/A-1288-2007; OI Wright, Tim/0000-0001-8338-5935; Fielding, Eric/0000-0002-6648-8067; McClusky, Simon/0000-0003-4040-925X NR 32 TC 76 Z9 79 U1 0 U2 9 PU SEISMOLOGICAL SOC AMER PI EL CERRITO PA PLAZA PROFESSIONAL BLDG, SUITE 201, EL CERRITO, CA 94530 USA SN 0037-1106 J9 B SEISMOL SOC AM JI Bull. Seismol. Soc. Amer. PD FEB PY 2002 VL 92 IS 1 BP 161 EP 171 DI 10.1785/0120000834 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 540LG UT WOS:000174930000012 ER PT J AU Delouis, B Giardini, D Lundgren, P Salichon, J AF Delouis, B Giardini, D Lundgren, P Salichon, J TI Joint inversion of InSAR, GPS, teleseismic, and strong-motion data for the spatial and temporal distribution of earthquake slip: Application to the 1999 Izmit mainshock SO BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA LA English DT Article ID NORTH ANATOLIAN FAULT; 17 AUGUST 1999; LANDERS EARTHQUAKE; TURKEY EARTHQUAKE; RADAR INTERFEROMETRY; FIELD; KOCAELI AB The space-time distribution of slip of the 17 August 1999 Izmit earthquake is investigated by inverting synthetic aperture radar (SAR) interferometry and Global Positioning System (GPS) data, together with teleseismic broadband and near-field strong-motion records. Surface offsets are used as an added constraint. Special emphasis is given to analysis of the resolution of the different data sets. We use a four-segment finite fault model and a nonlinear inversion scheme, allowing slip to vary in amplitude, direction, and duration, as well as variable rupture velocity. From the inversion of synthetic data, we find that the best spatial resolution can be expected in the upper half of the fault model (above 12 km), where coverage of the interferometric SAR data is good (western half of the rupture), and near the GPS and strong-motion stations. Teleseismic data are found to have a lower resolution that is more evenly distributed over the fault model. The joint inversion of all the data sets has an increased resolving power compared with the separate inversions and gives a more robust description of the space and time distribution of slip. Our study shows the importance of resolution tests in evaluating the reliability of earthquake kinematic models, and it confirms that an excellent fit of a single kind of data does not necessarily imply a good retrieval of the kinematic properties of an earthquake. The Izmit rupture, which is almost pure right-lateral strike-slip faulting, is dominated by the bilateral breaking of a central asperity located between 29.7degrees E (about 10 km west of the city of Golcuk) and 30.4degrees E (eastern margin of Sapanka Lake), with slip reaching 6-8 m in the depth range 6-12 km. The western termination of the rupture is found near the city of Yalova, but large slip ends around 29.7degrees E (about 10 km east of Hersek Delta). A second area of large slip is required by all the data sets further east toward the city of Duzce, between 30.7degrees E and 31.1degrees E (Karadere and Duzce faults). This eastern slip zone, which is separated from the main central asperity by an area of greatly reduced slip, is less well constrained by the data. However, a strong-motion station near the city of Duzce helps to locate a high-slip patch near 31.1degrees E in the depth range 6-12 kin. The total seismic moment resulting from the joint inversion is 2.4 X 10(27) dyne cm. Most of the energy release occurred in a short time, less than 15 sec, corresponding to the bilateral breaking of the central asperity. Rupture propagation is relatively uniform and fast toward the west, with a rupture velocity close to 3.5 km/sec. Propagation of large slip toward the east is initially slower, but it accelerates during a short time interval about 10 sec after rupture nucleation. Eastward progression then slows down to less than 2 km/sec after 15 sec, and rupture almost vanishes in amplitude ca. 20 sec after initiation. Rupture propagation then proceeds on the easternmost Karadere and Duzce fault segments, east of 30.7degrees E, from 22 to ca. 50 sec. Supershear rupture propagation is not required for modeling the waveforms considered in this study. The hypocenter of the Duzce earthquake. which occurred 3 months later (12 November 1999, M-w 7.2), is located in the immediate vicinity of the easternmost slip patch of the Izmit earthquake. C1 ETH Hoenggerberg, Inst Geophys, Zurich, Switzerland. CALTECH, Jet Propuls Lab, Pasadena, CA USA. RP Delouis, B (reprint author), ETH Hoenggerberg, Inst Geophys, Zurich, Switzerland. RI Giardini, Domenico/F-5406-2011 NR 42 TC 168 Z9 173 U1 1 U2 17 PU SEISMOLOGICAL SOC AMER PI EL CERRITO PA PLAZA PROFESSIONAL BLDG, SUITE 201, EL CERRITO, CA 94530 USA SN 0037-1106 J9 B SEISMOL SOC AM JI Bull. Seismol. Soc. Amer. PD FEB PY 2002 VL 92 IS 1 BP 278 EP 299 DI 10.1785/0120000806 PG 22 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 540LG UT WOS:000174930000021 ER PT J AU Wehrmeyer, JA Cheng, ZX Mosbacher, DM Pitz, RW Osborne, R AF Wehrmeyer, JA Cheng, ZX Mosbacher, DM Pitz, RW Osborne, R TI Opposed jet flames of lean or rich premixed propane-air reactants versus hot products SO COMBUSTION AND FLAME LA English DT Article ID DIFFUSION FLAMES AB Several opposed jet flames, produced by a lean H-2-air jet opposing a rich or lean C3H8-air jet, are investigated. Spontaneous Raman spectroscopy is used for major species concentration and temperature measurements along the opposed jet centerline. The hot products of the H.-air flame simulate the burnt gases of I impinge upon a weak-burning lean or rich hydrocarbon-strong-burning near-stoichiometric reactants as they fueled reactant mix, a situation encountered in stratified charge operation of direct injection spark ignition engines. In addition the H-2-air name hot products facilitate experimental data interpretation through the absence of carbon-bearing species. Good agreement between numerical and experimental data are obtained for a rich (equivalence ratio, (phi = 1.25) C3H8-air jet versus a lean (phi = 0.4) H-2-air jet. Two lean C3H8-air jets (0 = 0.64 or 0.60), versus the phi= 0.4 H-2-air jet, are also investigated. For both of those flames, the amount of Co-2 production strongly depends upon phi), with the 6 0.64 flame having a peak CO2 mole fraction an order of magnitude higher than for the (h = 0.60 flame, and the C3H8 flames burning either as a normal flame (high Co-2) or as a "negative flame speed" flame producing little CO2 and then only through diffusion of C3H8 into the hot products jet. The numerically predicted and experimental CO2 profiles agree well for the positive flame speed flame, but the large discrepancy between predicted and measured peak CO2 in the negative flame speed flame suggests modeling improvements Lire needed for this type of flame. (C) 2002 by The Combustion Institute. C1 Vanderbilt Univ, Dept Mech Engn, Nashville, TN 37235 USA. NASA, George C Marshall Space Flight Ctr, ERC Inc, Huntsville, AL 35812 USA. RP Wehrmeyer, JA (reprint author), Vanderbilt Univ, Dept Mech Engn, Box 1592 Stn B, Nashville, TN 37235 USA. RI Pitz, Robert/H-7868-2016 OI Pitz, Robert/0000-0001-6435-5618 NR 17 TC 19 Z9 19 U1 0 U2 8 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0010-2180 J9 COMBUST FLAME JI Combust. Flame PD FEB PY 2002 VL 128 IS 3 BP 232 EP 241 AR PII 0010-2180(01)00348-0 DI 10.1016/S0010-2180(01)00348-0 PG 10 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA 525DK UT WOS:000174053300004 ER PT J AU Barut, A Hanauska, J Madenci, E Ambur, DR AF Barut, A Hanauska, J Madenci, E Ambur, DR TI Analysis method for bonded patch repair of a skin with a cutout SO COMPOSITE STRUCTURES LA English DT Article DE adhesive; patch; repair; cutout; composite ID JOINT AB This study presents an analysis method for determining the transverse shear and normal stresses in the adhesive and in-plane stresses in the repair patch and in the repaired skin. The damage to the skin is represented in the form of a cutout. The circular or elliptical cutout can be located arbitrarily under the patch. The patch is free of external tractions while the skin is subjected to general loading along its external edge. The method utilizes the principle of minimum potential energy in conjunction with complex potential functions to analyze a patch-repaired damage configuration. The present results have been validated against experimental measurements and three-dimensional finite element (FE) predictions concerning the patch repair of a circular cutout in a skin under uniform loading. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Univ Arizona, Dept Aerosp & Mech Engn, Tucson, AZ 85721 USA. NASA, Langley Res Ctr, Mech & Durabil Branch, Hampton, VA 23665 USA. RP Madenci, E (reprint author), Univ Arizona, Dept Aerosp & Mech Engn, POB 210119, Tucson, AZ 85721 USA. NR 16 TC 14 Z9 18 U1 2 U2 3 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0263-8223 J9 COMPOS STRUCT JI Compos. Struct. PD FEB-MAR PY 2002 VL 55 IS 3 BP 277 EP 294 AR PII S0263-8223(01)00158-1 DI 10.1016/S0263-8223(01)00158-1 PG 18 WC Materials Science, Composites SC Materials Science GA 522XG UT WOS:000173921800003 ER PT J AU Ibrahim, AH Hou, GJW Tiwari, SN Smith, RE AF Ibrahim, AH Hou, GJW Tiwari, SN Smith, RE TI Aerodynamic design optimization using Euler equations and variational methods SO COMPUTERS & FLUIDS LA English DT Article DE aerodynamics; design optimization; variational methods ID SENSITIVITY ANALYSIS; FLOW AB An optimization methodology which uses the conservative field variables, is developed to solve a design optimization problem in fluid dynamical distributed parameter systems. This approach which is completely based on the variational method, is employed to derive the costate partial differential equations (pdes) and their transversality (boundary) conditions from the continuous pdes of the fluid flow. The costate equations coupled with the flow field equations are solved iteratively to get the functional derivative coefficients. Then, these derivative coefficients combined with the flow field variables are used to find the boundary shape which extremizes the performance index (functional). To demonstrate the method through examples, the shape of the nozzle is optimized for the maximum thrust. For this maximization problem, inlet and outlet flow conditions that depend on the upstream and downstream Mach numbers respectively are considered. In order to build confidence in the optimization procedure, high convergences of the state and costate equations were sought and the numerical and analytical solutions (in the form of pressure distributions) of the state equations are compared. In the purely supersonic flow case, the gain in thrust is remarkably high. Even in the supersonic-inlet-subsonic-outlet and the purely subsonic cases, the improvement of the thrust is found to be substantial. As demonstrated through the cases investigated, a new achievement is that the present variational shape optimization approach is capable of resolving flows with shocks. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Old Dominion Univ, Dept Mech Engn, Norfolk, VA 23529 USA. Norfolk State Univ, Dept Phys & Elect Engn, Norfolk, VA USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Tiwari, SN (reprint author), Old Dominion Univ, Dept Mech Engn, Norfolk, VA 23529 USA. NR 24 TC 2 Z9 2 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD FEB PY 2002 VL 31 IS 2 BP 227 EP 243 DI 10.1016/S0045-7930(01)00012-3 PG 17 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA 480VE UT WOS:000171482800005 ER PT J AU Spirkovska, L Lodha, SK AF Spirkovska, L Lodha, SK TI AWE: aviation weather data visualization environment SO COMPUTERS & GRAPHICS-UK LA English DT Article DE weather visualization; general aviation; route selection; user evaluation ID COMPUTER-GRAPHICS; UNCERTAINTY VISUALIZATION AB Weather is one of the major causes of aviation accidents. General aviation (GA) flights account for 92% of all the aviation accidents. Researchers are addressing this problem from various perspectives including improving meteorological forecasting techniques, collecting additional weather data automatically via on-board sensors and "flight" modems, and improving weather data dissemination (often available only in the textual format) and visualization techniques. We approach the problem from the improved dissemination perspective and propose weather visualization methods tailored for general aviation pilots. Although some aviation weather data, such as possible icing (Airman's Meteorological Information (AIRMETs)) or turbulence conditions (Significant Meteorological Conditions (SIGMETs)), or information about precipitation intensity and movement, has already been presented well by existing systems, there is still an urgent need for visualizing several critical weather elements neglected so far. Our system, Aviation Weather Data Visualization Environment (AWE), focuses on graphical displays of these weather elements, namely, meteorological observations, terminal area forecasts, and winds aloft forecasts and maps them onto a cartographic grid specific to the pilot's area of interest. Additional weather graphics such as icing (AIRMETs) or turbulence conditions (SIGMETs) can easily be added to our system to provide a pilot with a more complete visual weather briefing. Decisions regarding the graphical display and design are made based on careful consideration of user needs. Integral visual display of these elements of weather reports is designed for the use of GA pilots as a weather briefing and route selection tool, AWE provides linking of the weather information to the flight's path and schedule. The pilot can interact with the system to obtain aviation-specific weather for the entire area or for his specific route to explore what-if scenarios including the selection of alternates, and make "go/no-go" decisions. AWE, as evaluated by some pilots at National Aeronautics and Space Administration Ames Research Center, was found to be useful. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Santa Cruz, Santa Cruz, CA 95064 USA. RP Spirkovska, L (reprint author), NASA, Ames Res Ctr, MS 269-3, Moffett Field, CA 94035 USA. EM spirkov@mail.arc.nasa.gov; lodha@cse.ucsc.edu NR 39 TC 5 Z9 5 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0097-8493 EI 1873-7684 J9 COMPUT GRAPH-UK JI Comput. Graph.-UK PD FEB PY 2002 VL 26 IS 1 BP 169 EP 191 DI 10.1016/S0097-8493(01)00187-X PG 23 WC Computer Science, Software Engineering SC Computer Science GA 525HB UT WOS:000174061900017 ER PT J AU Stunz, GW Minello, TJ Levin, PS AF Stunz, GW Minello, TJ Levin, PS TI A comparison of early juvenile red drum densities among various habitat types in Galveston Bay, Texas SO ESTUARIES LA English DT Article ID QUANTITATIVELY SAMPLING NEKTON; MARSH-EDGE FISHES; SALT-MARSH; SCIAENOPS-OCELLATUS; DECAPOD CRUSTACEANS; ESTUARINE HABITATS; LOUISIANA ESTUARY; SEAGRASS MEADOWS; NORTH-CAROLINA; GROWTH AB Seagrass meadows are often cited as important nursery areas for newly settled red drum even though many estuaries, such as Galveston Bay, Texas, support large numbers of red drum and have limited seagrass cover, suggesting the use of alternate nursery areas. We examined patterns of habitat use for newly settled red drum at six sampling areas in Galveston Bay, two areas had seagrass beds and four areas had no seagrass. We measured densities in different habitat types using epibenthic sleds and enclosure samplers. Peal, recruitment of young red drum to the estuary occurred during September through December. Highest densities of new settlers were found in seagrass meadows (primarily Halodule wrightii), but when seagrass was absent, the highest densities of red drum occurred along the Spartina alterniflora marsh edge interface. Densities were relatively low on nonvegetated bottom away from die marsh edge. We also examined density patterns in other habitat types at selected sampling areas and found no red drum within marsh vegetation away from the marsh edge interface (5 and 10 m into the marsh interior). Oyster reef Crassostrea virginica was sampled using lift nets, and we found no red drum using this habitat, although adjacent seagrass and marsh interface habitats were used. Even though red drum densities in marsh edge were low relative to seagrass, the large areal extent of marshes in the bay complex probably makes marsh edge the most important nursery habitat for red drum in Galveston Bay. C1 SE Fisheries Sci Ctr, Natl Marine Fisheries Serv, Fishery Ecol Branch, Galveston Lab, Galveston, TX 77551 USA. NW Fisheries Sci Ctr, Seattle, WA 98112 USA. RP Stunz, GW (reprint author), SE Fisheries Sci Ctr, Natl Marine Fisheries Serv, Fishery Ecol Branch, Galveston Lab, 4700 Ave U, Galveston, TX 77551 USA. NR 60 TC 50 Z9 52 U1 1 U2 21 PU ESTUARINE RES FEDERATION PI LAWRENCE PA PO BOX 368, LAWRENCE, KS 66044 USA SN 0160-8347 J9 ESTUARIES JI Estuaries PD FEB PY 2002 VL 25 IS 1 BP 76 EP 85 DI 10.1007/BF02696051 PG 10 WC Environmental Sciences; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 544FM UT WOS:000175147600008 ER PT J AU Cerf, NJ Iblisdir, S Van Assche, G AF Cerf, NJ Iblisdir, S Van Assche, G TI Cloning and cryptography with quantum continuous variables SO EUROPEAN PHYSICAL JOURNAL D LA English DT Article; Proceedings Paper CT Conference on Quantum Interference and Cryptographic Keys - Novel Physics and Advancing Technologies (QUICK) CY APR 07-13, 2001 CL INST ETUDES SCI, CARGESE, FRANCE HO INST ETUDES SCI ID PRIVACY AMPLIFICATION; TELEPORTATION; INFORMATION; STATES; KEY AB The cloning of quantum variables with continuous spectra is investigated. We define a Gaussian 1-to-2 cloning machine that copies equally well two conjugate variables such as position and momentum or the two quadrature components of a light mode. The resulting cloning fidelity for coherent states, namely F = 2/3, is shown to be optimal. An asymmetric version of this Gaussian cloner is then used to assess the security of a continuous-variable quantum key distribution scheme that allows two remote parties to share a Gaussian key. The information versus disturbance tradeoff underlying this continuous quantum cryptographic scheme is then analyzed for the optimal individual attack. Methods to convert the resulting Gaussian keys into secret key bits are also studied. Finally, the extension of the Gaussian cloner to optimal N-to-M continuous cloners is discussed, and it is shown how to implement these cloners for light modes using a phase-insensitive optical amplifier and beam splitters. In addition, a phase-conjugate input cloner is defined, yielding M clones and M' anticlones from N replicas of a coherent state and N' replicas of its phase-conjugate (with M'-M = N'-N). This novel kind of cloners is shown to outperform the standard N-to-M cloners in some cases. C1 Free Univ Brussels, Ecole Polytech, B-1050 Brussels, Belgium. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Cerf, NJ (reprint author), Free Univ Brussels, Ecole Polytech, CP 165, B-1050 Brussels, Belgium. NR 30 TC 20 Z9 20 U1 0 U2 2 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 1434-6060 J9 EUR PHYS J D JI Eur. Phys. J. D PD FEB PY 2002 VL 18 IS 2 BP 211 EP 218 DI 10.1140/epjd/e20020025 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 527HK UT WOS:000174180500010 ER PT J AU Arkoosh, MR Collier, TK AF Arkoosh, MR Collier, TK TI Ecological risk assessment paradigm for salmon: Analyzing immune function to evaluate risk SO HUMAN AND ECOLOGICAL RISK ASSESSMENT LA English DT Article DE salmon; contaminants; estuary; PCBs; PAHs; ecology ID JUVENILE CHINOOK SALMON; POLYCHLORINATED-BIPHENYLS; ONCORHYNCHUS-TSHAWYTSCHA; WASHINGTON; EXPOSURE; RECOVERY; ESTUARY; URBAN AB Wild Pacific salmon populations are in serious decline, and as a result, a number of salmon stocks are listed as threatened or endangered under the Endangered Species Act. Our research identifies and supports the possibility that certain environmental contaminants can alter salmon survival, and as a result may contribute to these species being at risk. We have shown that juvenile chinook salmon (Oncorhynchus tshawytscha) are exposed to polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) as they migrate through a contaminated urban estuary in Puget Sound WA (the Duwamish Waterway estuary). Immune function was analyzed in these fish by examining the ability of their anterior kidney and splenic leukocytes to produce a primary and secondary in vitro plaque-forming cell (PFC) response to the hapten, trinitrophenyl (TNP), and by determining their susceptibility to a marine pathogen, Vibrio anguillarum. We found that fish outmigrating from the urban estuary produced a significantly lower PFC response to TNP and were more susceptible to the pathogen, compared to juvenile salmon collected from a rural estuary during their outmigration. In the laboratory, we exposed juvenile chinook salmon collected from a hatchery to either a PCB technical mixture or a PAH compound to determine if these contaminants have the potential to alter immune function in salmon. Indeed, we found that salmon exposed in the laboratory to either die PCB mixture or the PAH also produced lower PFC responses and were more susceptible to disease compared to animals treated with the solvent vehicle. In summary, contaminants such as PAHs and PCBs are demonstrated to influence salmon health, and thus have the potential to adversely impact salmon populations. C1 Oregon State Univ, Hatfield Marine Sci Ctr, Natl Marine Fisheries Serv, NOAA,NW Fisheries Sci Ctr,Environm Conservat Div, Newport, OR 97365 USA. RP Arkoosh, MR (reprint author), Oregon State Univ, Hatfield Marine Sci Ctr, Natl Marine Fisheries Serv, NOAA,NW Fisheries Sci Ctr,Environm Conservat Div, 2030 S Marine Sci Dr, Newport, OR 97365 USA. NR 30 TC 20 Z9 23 U1 3 U2 10 PU CRC PRESS LLC PI BOCA RATON PA 2000 CORPORATE BLVD NW, JOURNALS CUSTOMER SERVICE, BOCA RATON, FL 33431 USA SN 1080-7039 J9 HUM ECOL RISK ASSESS JI Hum. Ecol. Risk Assess. PD FEB PY 2002 VL 8 IS 2 BP 265 EP 276 DI 10.1080/20028091056908 PG 12 WC Biodiversity Conservation; Environmental Sciences SC Biodiversity & Conservation; Environmental Sciences & Ecology GA 527ZQ UT WOS:000174218600006 ER PT J AU Cockell, CS Barlow, NG AF Cockell, CS Barlow, NG TI Impact excavation and the search for subsurface life on Mars SO ICARUS LA English DT Article DE impacts; Mars; life; excavation; critical depth; drilling; paleolacustrine ID ORBITER-LASER-ALTIMETER; EJECTA MORPHOLOGIES; DEEP SUBSURFACE; MICROBIAL LIFE; CRATER LAKES; EARLY EARTH; PERMAFROST; MICROORGANISMS; SEDIMENTS; ORIGIN AB Because of the ubiquity of subsurface microbial life on Earth, examination of the subsurface of Mars could provide an answer to the question of whether microorganisms exist or ever existed on that planet. Impact craters provide a natural mechanism for accessing the deep substrate of Mars and exploring its exobiological potential. Based on equations that relate impact crater diameters to excavation depth we estimate the observed crater diameters that are required to prospect to given depths in the martian subsurface and we relate these depths to observed microbiological phenomena in the terrestrial subsurface. Simple craters can be used to examine material to a depth of similar to270 m. Complex craters can be used to reach greater depths, with craters of diameters greater than or equal to 300 km required to reach depths of 6 km or greater, which represent the limit of the terrestrial deep subsurface biosphere. Examination of the ejecta blankets of craters between 17.5 and 260 km in diameter would provide insights into whether there is an extant, or whether there is evidence of an extinct, deep subsurface microbiota between 500 and 5000 m prior to committing to large-scale drilling efforts. At depths < 500 m some crater excavations are likely to be more important than others from an excibiological point of view. We discuss examples of impacts into putative intracrater paleolacustrine sediments and regions associated with hydrothermal activity. We compare these depths to the characteristics of subsurface life on Earth and the fossil microbiological record in terrestrial impact craters. (C) 2002 Elsevier Science (USA). C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. British Antarctic Survey, Cambridge CB3 0ET, England. Univ Cent Florida, Dept Phys, Orlando, FL 32816 USA. RP Cockell, CS (reprint author), NASA, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. NR 79 TC 14 Z9 15 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 FEB PY 2002 VL 155 IS 2 BP 340 EP 349 DI 10.1006/icar.2001.6725 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 548GN UT WOS:000175380400006 ER PT J AU Buratti, BJ Hicks, MD Tryka, KA Sittig, MS Newburn, RL AF Buratti, BJ Hicks, MD Tryka, KA Sittig, MS Newburn, RL TI High-resolution 0.33-0.92 mu m spectra of Iapetus, Hyperion, Phoebe, Rhea, Dione, and D-type asteroids: How are they related? SO ICARUS LA English DT Article ID DARK SIDE; PHOTOMETRIC PROPERTIES; SATURNIAN SATELLITES; REFLECTANCE SPECTRA; COLOR MAPS; LAPETUS; SPECTROPHOTOMETRY; ALBEDO; SYSTEM; ORIGIN AB New high-resolution spectra in the 0.33 to 0.92 mum range of Iapetus, Hyperion, Phoebe, Dione, Rhea, and three D-type asteroids were obtained on the Palomar 200-inch telescope and the double spectrograph. The spectra of Hyperion and the low-albedo hemisphere of Iapetus can both be closely matched by a simple model that is the linear admixture of the spectrum of a medium-sized, high-albedo icy Saturnian satellite and D-type material. Our results support an exogenous origin to the dark material on Iapetus; furthermore, this material may share a common origin and a similar means of transport with material on the surface of Hyperion. The recently discovered retrograde satellites of Saturn (Gladman et al., Nature 412, 163-166) may be the source of this material. The leading sides of Callisto and the Uranian satellites may be subjected to a similar alteration mechanism as that of Iapetus: accretion of low-albedo dust originating from outer retrograde satellites. Phoebe does not appear to be related to either Iapetus or Hyperion. Separate spectra of the two hemispheres of Phoebe show no identifiable global compositional differences. (C) 2002 Elsevier Science (USA). C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Buratti, BJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mailstop 183-501, Pasadena, CA 91109 USA. OI Tryka, Kimberly/0000-0002-5399-4235 NR 52 TC 45 Z9 45 U1 0 U2 3 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 FEB PY 2002 VL 155 IS 2 BP 375 EP 381 DI 10.1006/icar.2001.6730 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 548GN UT WOS:000175380400009 ER PT J AU Simon, MK AF Simon, MK TI A simpler form of the Craig representation for the two-dimensional joint Gaussian Q-function SO IEEE COMMUNICATIONS LETTERS LA English DT Article DE digital communication; fading channels; Gaussian distributions AB We derive a simpler form for the Craig representation of the two-dimensional joint Gaussian Q-function which dispenses with the trigonometric factor that precedes the exponentials in the integrands and furthermore results in an exponential argument that is precisely in the same simple form as that in the Craig representation of the one-dimensional Gaussian Q-function. As such, the entire dependence on the correlation parameter now appears only in the limits of integration. The resulting single integral form is particularly useful in evaluating the outage probability for dual diversity selection combining over correlated identically and nonidentically distributed log normal channels. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Simon, MK (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 4 TC 46 Z9 46 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1089-7798 J9 IEEE COMMUN LETT JI IEEE Commun. Lett. PD FEB PY 2002 VL 6 IS 2 BP 49 EP 51 AR PII S1089-7798(02)01918-X DI 10.1109/4234.984687 PG 3 WC Telecommunications SC Telecommunications GA 523BJ UT WOS:000173931200001 ER PT J AU Heymann, M Lin, F Meyer, G AF Heymann, M Lin, F Meyer, G TI Multiuser discrete-event control with active events SO IEEE TRANSACTIONS ON AUTOMATIC CONTROL LA English DT Article DE discrete-event systems; manufacturing systems; multiagent; safety and liveness; supervisory control ID SUPERVISORY CONTROL; SYSTEMS AB The traditional framework for discrete-event control is extended to include the case of control with active events, in which both the user and the environment have events that they can trigger. A variety of liveness and safety specifications can be considered within this extended framework. A synthesis algorithm of minimally restrictive controllers is outlined. Multiuser systems are also discussed. C1 Technion Israel Inst Technol, Dept Comp Sci, IL-32000 Haifa, Israel. Wayne State Univ, Dept Elect & Comp Engn, Detroit, MI 48202 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Heymann, M (reprint author), Technion Israel Inst Technol, Dept Comp Sci, IL-32000 Haifa, Israel. NR 14 TC 2 Z9 2 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9286 J9 IEEE T AUTOMAT CONTR JI IEEE Trans. Autom. Control PD FEB PY 2002 VL 47 IS 2 BP 314 EP 318 AR PII S0018-9286(02)02072-X DI 10.1109/9.983368 PG 5 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA 521VT UT WOS:000173862600012 ER PT J AU Tai, AT Tso, KS Alkalai, L Chau, SN Sanders, WH AF Tai, AT Tso, KS Alkalai, L Chau, SN Sanders, WH TI Low-cost error containment and recovery for onboard guarded software upgrading and beyond SO IEEE TRANSACTIONS ON COMPUTERS LA English DT Article DE guarded software upgrading; message-driven confidence-driven; global state consistency and recoverability; performance overhead; software fault tolerance; distributed embedded systems ID FAULT-TOLERANT; SYSTEMS; DESIGN; ARCHITECTURE; RELIABILITY AB Message-driven confidence-driven (MDCD) error containment and recovery, a low-cost approach to mitigating the effect of software design faults in distributed embedded systems, is developed for onboard guarded software upgrading for deep-space missions. In this paper, we first describe and verify the MDCD algorithms in which we introduce the notion of "confidence-driven" to complement the "communication-induced" approach employed by a number of existing checkpointing protocols to achieve error containment and recovery efficiency. We then conduct a model-based analysis to show that the algorithms ensure low performance overhead. Finally, we discuss the advantages of the MDCD approach and its potential utility as a general-purpose, low-cost software fault tolerance technique for distributed embedded computing. C1 IA Tech Inc, Los Angeles, CA 90024 USA. Jet Propuls Lab, Pasadena, CA 91109 USA. Univ Illinois, Urbana, IL 61801 USA. RP IA Tech Inc, Los Angeles, CA 90024 USA. EM a.t.tai@ieee.org; k.tso@ieee.org; lalkalai@jpl.nasa.gov; schau@jpl.nasa.gov; whs@crhc.uiuc.edu NR 26 TC 6 Z9 6 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 0018-9340 EI 1557-9956 J9 IEEE T COMPUT JI IEEE Trans. Comput. PD FEB PY 2002 VL 51 IS 2 BP 121 EP 137 DI 10.1109/12.980004 PG 17 WC Computer Science, Hardware & Architecture; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 518PM UT WOS:000173677100004 ER PT J AU Markus, T Dokken, ST AF Markus, T Dokken, ST TI Evaluation of late summer passive microwave Arctic sea ice retrievals SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE Arctic; passive microwave remote sensing; sea ice ID MELT; SIGNATURES; REDUCTION; SURFACE; SSM/I; COVER AB The melt period of the Arctic sea ice cover is of particular interest in studies of climate change due to the albedo feedback mechanisms associated with meltponds and openings in the ice pack. The traditionally used satellite passive microwave sea ice concentration algorithms have deficiencies during the summer months due to the period's highly variable surface properties. A newly developed ice concentration algorithm overcomes some of these deficiencies. It corrects for low ice concentration biases caused by surface effects through the use of 85 GHz data in addition to the commonly used 19 and 37 GHz data and, thus, the definition of an additional ice type representing layering and inhomogeneities in the snow layer. This new algorithm will be the standard algorithm for Arctic sea ice concentration retrievals with the EOS Aqua advanced microwave scanning radiometer (AMSR-E) instrument. In this paper, we evaluate the performance of this algorithm for the summer period of 1996 using data from the special sensor microwave imager (SSM/I) which has frequencies similar to the AMSR instrument. The temporal evolution of summertime passive microwave sea ice signatures are investigated and sea ice concentration retrievals from the standard NASA team and the new algorithm are compared. The results show that the introduction of the additional sea ice type in the new algorithm leads to improved summertime sea ice concentrations. The SSM/I sea ice retrievals are validated using SAR-derived ice concentrations that have been convolved with the SSM/I antenna pattern to ensure an appropriate comparison. For the marginal ice zone, with ice concentrations ranging from 40% to 100%, the correlation coefficient of SAR and SSM/I retrievals is 0.66 with a bias of 5% toward higher SAR ice concentrations. For the central Arctic, where ice concentrations varied between 60% and 100%, the correlation coefficient is 0.87 with a negligible bias. C1 NASA, Goddard Space Flight Ctr, UMBC, Joint Ctr Earth Syst Technol, Greenbelt, MD 20771 USA. Chalmers Univ Technol, Dept Radio & Space Sci, S-41296 Gothenburg, Sweden. RP Markus, T (reprint author), NASA, Goddard Space Flight Ctr, UMBC, Joint Ctr Earth Syst Technol, Code 971, Greenbelt, MD 20771 USA. RI Markus, Thorsten/D-5365-2012 NR 23 TC 31 Z9 31 U1 1 U2 9 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD FEB PY 2002 VL 40 IS 2 BP 348 EP 356 AR PII S0196-2892(02)01881-8 DI 10.1109/36.992795 PG 9 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 534XM UT WOS:000174615100012 ER PT J AU Chang, CI Chiang, SS Smith, JA Ginsberg, IW AF Chang, CI Chiang, SS Smith, JA Ginsberg, IW TI Linear spectral random mixture analysis for hyperspectral imagery SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE hyperspectral image classification; independent component analysis (ICA); linear spectral mixture analysis (LSMA); linear spectral random mixture analysis (LSRMA) ID INDEPENDENT COMPONENT ANALYSIS; SUBSPACE PROJECTION APPROACH; REMOTELY-SENSED IMAGERY; TARGET DETECTION; CLASSIFICATION; SEPARATION; PURSUIT AB Independent component analysis (ICA) has shown success in blind source separation and channel equalization. Its applications to remotely sensed images have been investigated in recent years. Linear spectral mixture analysis (LSMA) has been widely used for subpixel detection and mixed pixel classification. It models an image pixel as a linear mixture of materials present in an image where the material abundance fractions are assumed to be unknown and nonrandom parameters. This paper considers an application of ICA to the LSMA, referred to as ICA-based linear spectral random mixture analysis (LSRMA), which describes an image pixel as a random source resulting from a random composition of multiple spectral signatures of distinct materials in the image. It differs from the LSMA in that the abundance fractions of the material spectral signatures in the LSRMA are now considered to be unknown but random independent signal sources. Two major advantages result from the LSRMA. First, it does not require prior knowledge of the materials to be used in the linear mixture model, as required for the LSMA. Second, and most importantly, the LSRMA models the abundance fraction of each material spectral signature as an independent random signal source so that the spectral variability of materials can be described by their corresponding abundance fractions and captured more effectively in a stochastic manner. The experimental results demonstrate that the proposed LSRMA provides an effective unsupervised technique for target detection and image classification in hyperspectral imagery. C1 Univ Maryland Baltimore Cty, Dept Comp Sci & Elect Engn, Remote Sensing Signal & Image Proc Lab, Baltimore, MD 21250 USA. Lunghua Univ Sci & Technol, Dept Elect Engn, Tao Yuan, Taiwan. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. Remote Sensing Lab, Dept Energy, Las Vegas, NV USA. RP Chang, CI (reprint author), Univ Maryland Baltimore Cty, Dept Comp Sci & Elect Engn, Remote Sensing Signal & Image Proc Lab, Baltimore, MD 21250 USA. EM equinoxsr@aol.com NR 34 TC 72 Z9 79 U1 0 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD FEB PY 2002 VL 40 IS 2 BP 375 EP 392 AR PII S0196-2892(02)02126-5 DI 10.1109/36.992799 PG 18 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 534XM UT WOS:000174615100015 ER PT J AU Tran, N Vandemark, D Ruf, CS Chapron, B AF Tran, N Vandemark, D Ruf, CS Chapron, B TI The dependence of Nadir ocean surface emissivity on wind vector as measured with microwave radiometer SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE Nadir ocean surface emissivity; SeaWinds wind vector; TOPEX/Poseidon microwave radiometer (TMR) ID SEA-SURFACE; BRIGHTNESS TEMPERATURES; ALGORITHM; TMR; CALIBRATION; SATELLITE; RETRIEVAL; WATER; SPEED; MODEL AB Global brightness temperature observations of TOPEX/Poseidon microwave radiometer (TMR) at 18, 21, and 37 GHz have been collocated with near-simultaneous SeaWinds wind vector data as well as with monthly sea surface temperature and salinity products. The combined data allow us to study the dependence of zenith-directed ocean surface emissivity, at each frequency, upon both wind speed and direction. Results show a clear two-branch wind speed dependence; weak and linear below 7 m . s(-1) with an increase in sensitivity above that point. The observed emissivity also depends on the angle between the wind direction and TMR's antenna polarization orientation, providing satellite confirmation of aircraft-derived results. There is little change in these wind vector dependencies with frequency. C1 NASA, Goddard Space Flight Ctr, Wallops Flight Facil, Wallops Isl, VA 23337 USA. Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. IFREMER, Ctr Brest, Dept Oceanog Spatiale, F-29280 Plouzane, France. RP Tran, N (reprint author), NASA, Goddard Space Flight Ctr, Wallops Flight Facil, Wallops Isl, VA 23337 USA. RI Ruf, Christopher/I-9463-2012; Chapron, Bertrand/O-6527-2015 NR 35 TC 6 Z9 8 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD FEB PY 2002 VL 40 IS 2 BP 515 EP 523 AR PII S0196-2892(02)03264-3 DI 10.1109/36.992827 PG 9 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 534XM UT WOS:000174615100031 ER PT J AU Ortiz, SC Hubert, J Mirth, L Schlecht, E Mortazawi, A AF Ortiz, SC Hubert, J Mirth, L Schlecht, E Mortazawi, A TI A high-power Ka-band quasi-optical amplifier array SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article DE amplifiers; power combiners; quasi-optical; spatial AB Results for a high-power Ka-band quasi-optical amplifier array are presented in this paper. The amplifier consists of a 45-element double-sided active array with a hard-horn feed. Excess heat is removed via a metal carrier integrated into the array with liquid cooling at the periphery. Each unit cell of the array consists of transmitting and receiving patch antennas, driver and power amplifier monolithic microwave integrated circuits on input and output layers, and a through-plate coaxial transition, which connects the input and output layers. An estimated,25 W is radiated when the amplifier is used as an antenna feed, otherwise 13 W is collected into waveguide. Experimental results and construction details are discussed. C1 Harris Corp, Govt Commun Syst Div, Melbourne, FL 32902 USA. Xytrans Inc, Orlando, FL 32819 USA. Lockhead Martin Corp, Orlando, FL 32819 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Univ Michigan, Dept Elect & Comp Engn, Ann Arbor, MI 48109 USA. RP Ortiz, SC (reprint author), Harris Corp, Govt Commun Syst Div, Melbourne, FL 32902 USA. NR 14 TC 35 Z9 37 U1 5 U2 8 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD FEB PY 2002 VL 50 IS 2 BP 487 EP 494 DI 10.1109/22.982228 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA 519AR UT WOS:000173701700012 ER PT J AU Kory, CL Andro, M AF Kory, CL Andro, M TI Intersymbol interference investigations using a 3-D time-dependent traveling wave tube model SO IEEE TRANSACTIONS ON PLASMA SCIENCE LA English DT Article; Proceedings Paper CT Annual Meeting of the International Conference on Plasma Science/Pulsed Power Conference (PPPS 2001) CY 2001 CL LAS VEGAS, NEVADA DE helix; high-power amplifier; intersymbol interference; MAFIA; nonlinear model; PIC code; SPW; traveling wave tube amplifier AB For the first time, a physics based computational model has been used to provide a direct description of the effects of the traveling wave tube (TWT) on modulated digital signals. The TWT model comprehensively takes into account the effects of frequency dependent AM/AM and AM/PM conversion, gain and phase ripple, drive-induced oscillations, harmonic generation, intermodulation products, and backward waves. Thus, signal integrity can be investigated in the presence of these sources of potential distortion as a function of the physical geometry of the high-power amplifier and the operational digital signal. This method promises superior predictive fidelity compared to methods using TWT models based on swept-amplitude and/or swept-frequency data. The fully three-dimensional (3-D) time-dependent, TWT interaction model using the electromagnetic code MAFIA is presented. This model is used to investigate assumptions made in conventional TWT black-box models used in communication system level simulations. To quantitatively demonstrate the effects these approximations have on digital signal performance predictions, including intersymbol interference, direct digital data input into the MAFIA model is compared to the system level analysis tool, SPW, which incorporates these approximations. C1 NASA, Glenn Res Ctr, Analex Corp, Cleveland, OH 44135 USA. RP Kory, CL (reprint author), NASA, Glenn Res Ctr, Analex Corp, Cleveland, OH 44135 USA. NR 11 TC 4 Z9 4 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0093-3813 J9 IEEE T PLASMA SCI JI IEEE Trans. Plasma Sci. PD FEB PY 2002 VL 30 IS 1 BP 267 EP 273 AR PII S0093-3813(02)01604-1 DI 10.1109/TPS.2002.1003870 PN 2 PG 7 WC Physics, Fluids & Plasmas SC Physics GA 556JQ UT WOS:000175846000009 ER PT J AU Young, RB Bridge, KY Wuethrich, AJ Hancock, DL AF Young, RB Bridge, KY Wuethrich, AJ Hancock, DL TI Effect of serum from chickens treated with clenbuterol on myosin accumulation, beta-adrenergic receptor population, and cyclic amp synthesis in embryonic chicken skeletal muscle cell cultures SO IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY-ANIMAL LA English DT Article DE muscle; myofibrillar proteins; beta-adrenergic receptor agonists; phenethanolamines ID BROILER-CHICKENS; CARCASS COMPOSITION; PERFORMANCE; CIMATEROL; PROTEIN; GROWTH; STIMULATION; DENSITY AB Broiler chicken, at 35 d of age were fed 1 ppm clenbuterol for 14 d. This level of dietary clenbuterol led to 5-7% increases in the weights of leg and breast muscle tissue. At the end of the 14-d period, serum was prepared from both control and clenbuterol-treated chickens, and was then employed as a component of cell culture media at a final concentration of 20%, (v/v). Muscle cell cultures were prepared from both the leg and the breast muscle groups of 12-d chick embryos. Treatment groups included control chicken serum to which 10 nM, 50 nM, and 1 muM clenbuterol had been added. as well as cells grown in media containing 10% horse serum. Cultures were subjected to each treatment for 3 d, beginning on the seventh d in culture. Neither the percent fusion nor the number of nuclei in myotubes was significantly affected by any of the treatments. The quantity of myosin heavy chains (MHCs) was not increased by serum from clenbuterol-treated chickens in either breast or leg muscle cultures: however, the MHC quantity was 50-150% higher in cultures grown in control chicken serum to which 10 and 50 nM clenbuterol had also been added. The beta-adrenergic receptor (betaAR) population was 4400-7000 betaARs per cell in cultures grown in chicken serum, with log muscle cultures having approximately 25-30% more receptors than breast muscle cultures. Receptor population was not significantly affected by the presence of clenbuterol or by the presence of serum from clenbuterol-treated chickens. In contrast, the betaAR population in leg and breast muscle cultures grown in the presence of 10% horse serum was 16,000-18,000 betaARs per cell. Basal concentration of cyclic adenosine 3':5'monophosphate (cAMP) was not significantly affected by the treatments. When cultures grown in chicken serum were stimulated for 10 min with 1 muM isoproterenol, limited increases of 12-20% in cAMP concentration above the basal levels were observed. However, when cultures grown in the presence of horse serum were stimulated with 1 muM isoproterenol, cAMP concentration was stimulated 5- to 9-fold above the basal levels. Thus not only did cells grown in horse serum have a higher betaAR population, but also each receptor had a higher capacity for cAMP synthesis following isoproterenol stimulation. Finally, the hypothesis that clenbuterol exert, its action on muscle protein content by changes in cAMP concentration was tested. No correlation was apparent between basal cAMP concentration and MHC content. C1 NASA, George C Marshall Space Flight Ctr, Biotechnol Sci Grp, Huntsville, AL 35812 USA. Elanco Anim Hlth, Anim Sci Discovery & Dev Res, Greenfield, IN USA. RP Young, RB (reprint author), NASA, George C Marshall Space Flight Ctr, Biotechnol Sci Grp, SD48,Bldg 4481, Huntsville, AL 35812 USA. NR 20 TC 0 Z9 0 U1 0 U2 0 PU SOC IN VITRO BIOLOGY PI LARGO PA 9315 LARGO DR WEST, STE 25, LARGO, MD 20774 USA SN 1071-2690 J9 IN VITRO CELL DEV-AN JI In Vitro Cell. Dev. Biol.-Anim. PD FEB PY 2002 VL 38 IS 2 BP 102 EP 110 PG 9 WC Cell Biology; Developmental Biology SC Cell Biology; Developmental Biology GA 556YN UT WOS:000175877400009 ER PT J AU Sundaresan, M Risin, D Pellis, NR AF Sundaresan, M Risin, D Pellis, NR TI Loss of signal transduction and inhibition of lymphocyte locomotion in a ground-based model of microgravity SO IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY-ANIMAL LA English DT Article DE migration; receptor; PKC; PMA; modeled-microgravity; cell signaling; restoration ID PROTEIN-KINASE-C; COLLAGEN AB Inflammatory adherence to, and locomotion through the interstitium is all important component of the immune response. Conditions such as microgravity and modeled microgravity (MMG) severely inhibit lymphocyte locomotion in vitro through gelled type I collagen. We used the NASA rotating wall vessel bioreactor or slow-turning lateral vessel as a prototype for MMG in ground-based experiments. Previous experiments from our laboratory revealed that when lymphocytes (human peripheral blood mononuclear cells [PBMCs]) were first activated with phytohemaglutinin followed by exposure to MMG, locomotory capacity was not affected. In the present study MMG inhibits lymphocyte locomotion in a manner similar to that observed in microgravity. Phorbol myristate acetate (PMA) treatment of PBMCs restored lost locomotory capacity by a maximum of 87%. Augmentation of cellular calcium flux with ionomycin had no restorative effect. Treatment of lymphocytes with mitomycin C prior to exposure to MMC. followed by PMA, restored locomotion to the same extent as when nonmitomycin C-treated lymphocytes were exposed to MMG (80-87%), suggesting that deoxyribonucleic acid replication is not essential for the restoration of locomotion. Thus, direct activation of protein kinase C (PKC) with PMA was effective in restoring locomotion in MMG comparable to the normal levels seen in Ig cultures. Therefore, in MMG, lymphocyte calcium signaling pathways were functional, with defects occurring at either the level of PKC or upstream of PKC. C1 Wyle Labs, Life Sci Syst & Serv, Cellular Biotechnol Program, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Cellular Biotechnol Program, Houston, TX 77058 USA. RP Sundaresan, M (reprint author), Wyle Labs, Life Sci Syst & Serv, Cellular Biotechnol Program, BT-37,Suite 120,1290 Hercules Dr, Houston, TX 77058 USA. NR 7 TC 3 Z9 3 U1 0 U2 0 PU SOC IN VITRO BIOLOGY PI LARGO PA 9315 LARGO DR WEST, STE 25, LARGO, MD 20774 USA SN 1071-2690 J9 IN VITRO CELL DEV-AN JI In Vitro Cell. Dev. Biol.-Anim. PD FEB PY 2002 VL 38 IS 2 BP 118 EP 122 PG 5 WC Cell Biology; Developmental Biology SC Cell Biology; Developmental Biology GA 556YN UT WOS:000175877400011 ER PT J AU Bozzolo, GH Noebe, RD Amador, C AF Bozzolo, GH Noebe, RD Amador, C TI Site occupancy of ternary additions to B2 alloys SO INTERMETALLICS LA English DT Article DE nickel aluminides, based on NiAl; iron aluminides, based on FeAL; site occupancy ID INTERMETALLIC COMPOUNDS; FE; DISTRIBUTIONS; ALUMINIDES; OCCUPATION; PREFERENCE; SYSTEMS; METALS; IRON; TI AB In this broad-based survey study, the substitutional site preference of ternary alloying additions to B2 compounds (stable at room temperature and 50/50 composition) is determined using the Bozzolo-Ferrante-Smith (BFS) method for alloys. The method is applied to Ni, Al, Ti, Cr, Cu, Co, Fe, Ta, Hf, Mo, Nb, W, V and Ru additions to NiAl, FeAl, CoAl, CoFe, CoHf, CoTi, FeTi, RuAl, RuSi, RuHf, RuTi, and RuZr. The results arc compared, when available, to experimental data and other theoretical results. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Ohio Aerosp Inst, Cleveland, OH 44142 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Univ Nacl Autonoma Mexico, Dept Fis & Quim Teor, Fac Quim, Mexico City 04510, DF, Mexico. RP Bozzolo, GH (reprint author), Ohio Aerosp Inst, 22800 Cedar Point Rd, Cleveland, OH 44142 USA. RI Amador-Bedolla, Carlos/E-7448-2010 OI Amador-Bedolla, Carlos/0000-0001-9590-2645 NR 27 TC 50 Z9 55 U1 2 U2 14 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0966-9795 J9 INTERMETALLICS JI Intermetallics PD FEB PY 2002 VL 10 IS 2 BP 149 EP 159 DI 10.1016/S0966-9795(01)00124-8 PG 11 WC Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Chemistry; Materials Science; Metallurgy & Metallurgical Engineering GA 511VJ UT WOS:000173286000004 ER PT J AU O'Brien, TK Chawan, AD Krueger, R Paris, IL AF O'Brien, TK Chawan, AD Krueger, R Paris, IL TI Transverse tension fatigue life characterization through flexure testing of composite materials SO INTERNATIONAL JOURNAL OF FATIGUE LA English DT Article; Proceedings Paper CT 2nd International Conference on Fatigue of Composites CY JUN 04-07, 2001 CL WILLIAMSBURG, VIRGINIA DE composite materials; carbon-epoxy; glass-epoxy; transverse tension strength; fatigue life; Weibull scaling law ID STRENGTH AB The transverse tension fatigue life of S2/8552 glass-epoxy and IM7/8552 carbon-epoxy was characterized using flexure tests of 90-degree laminates loaded in 3-point and 4-point bending. The influence of specimen polishing and specimen configuration on transverse tension fatigue life was examined using the glass-epoxy laminates. Results showed that 90-degree flexure specimens with polished machined edges and polished tension-side surfaces had lower fatigue lives than unpolished specimens when cyclically loaded at equal stress levels. The influence of specimen thickness and the utility of a Weibull scaling law were examined using the carbon-epoxy laminates. The influence of test frequency on fatigue results was also documented for the 4-point bending configuration. A Weibull scaling law was used to predict the 4-point bending fatigue lives from the 3-point bending curve fit and vice versa. Scaling was performed based on maximum cyclic stress level as well as fatigue life. The scaling laws based on stress level shifted the curve fit S-N characterizations in the desired direction, however, the magnitude of the shift was not adequate to accurately predict the fatigue lives. Furthermore, the scaling law based on fatigue life shifted the curve fit S-N characterizations in the opposite direction from measured values. Therefore, these scaling laws were not adequate for obtaining accurate predictions of the transverse tension fatigue lives of heterogeneous, fiber reinforced, polymer matrix composites. Published by Elsevier Science Ltd. C1 NASA, Langley Res Ctr, USA, Res Lab,Vehicle Technol Directorate, Hampton, VA 23665 USA. NASA, Langley Res Ctr, Natl Res Council, Hampton, VA 23665 USA. RP O'Brien, TK (reprint author), NASA, Langley Res Ctr, USA, Res Lab,Vehicle Technol Directorate, Hampton, VA 23665 USA. RI Krueger, Ronald/G-5356-2015 NR 8 TC 14 Z9 14 U1 0 U2 12 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0142-1123 J9 INT J FATIGUE JI Int. J. Fatigue PD FEB-APR PY 2002 VL 24 IS 2-4 BP 127 EP 145 AR PII S0142-1123(01)00104-9 DI 10.1016/S0142-1123(01)00104-9 PG 19 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 523MK UT WOS:000173957700007 ER PT J AU Nicholson, LM Whitley, KS Gates, TS AF Nicholson, LM Whitley, KS Gates, TS TI The role of molecular weight and temperature on the elastic and viscoelastic properties of a glassy thermoplastic polyimide SO INTERNATIONAL JOURNAL OF FATIGUE LA English DT Article; Proceedings Paper CT 2nd International Conference on Fatigue of Composites CY JUN 04-07, 2001 CL WILLIAMSBURG, VIRGINIA DE molecular weight; modulus; strength; creep-compliance; physical ageing; polyimides ID AMORPHOUS POLYMERS; FREE-VOLUME; COMPOSITES; DEPENDENCE; FRACTURE; CREEP AB Mechanical testing of the elastic and viscoelastic response of an advanced thermoplastic polyimide (LaRC(TM)-SI) with known variations in molecular weight was performed over a range of temperatures below the glass transition temperature. The notched tensile strength was shown to be a strong function of both molecular weight and temperature, whereas stiffness was only a strong function of temperature. A critical molecular weight was observed at a weight-average molecular weight of (M) over bar (w)similar to22 000 g/mol below which the notched tensile strength decreases rapidly. This critical molecular weight transition is temperature-independent. Low molecular weight materials tended to fail in a brittle manner, whereas high molecular weight materials exhibited ductile failure. Furthermore, low molecular weight materials have increased creep compliance and creep compliance rate and are more sensitive to temperature than the high molecular weight materials. At long timescales (>1100 h) physical ageing serves to significantly decrease the creep compliance and creep rate of all the materials tested. Low molecular weight materials are less influenced by the effects of physical ageing. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Mech & Durabil Branch, Hampton, VA 23681 USA. RP Gates, TS (reprint author), NASA, Langley Res Ctr, Mech & Durabil Branch, Struct & Mat Competency MS 188E,2 W Reid St, Hampton, VA 23681 USA. NR 25 TC 13 Z9 13 U1 0 U2 7 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0142-1123 J9 INT J FATIGUE JI Int. J. Fatigue PD FEB-APR PY 2002 VL 24 IS 2-4 BP 185 EP 195 AR PII S0142-1123(01)00072-X DI 10.1016/S0142-1123(01)00072-X PG 11 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 523MK UT WOS:000173957700013 ER PT J AU Harik, VM Klinger, JR Bogetti, TA AF Harik, VM Klinger, JR Bogetti, TA TI Low-cycle fatigue of unidirectional composites: Bi-linear S-N curves SO INTERNATIONAL JOURNAL OF FATIGUE LA English DT Article; Proceedings Paper CT 2nd International Conference on Fatigue of Composites CY JUN 04-07, 2001 CL WILLIAMSBURG, VIRGINIA DE low-cycle fatigue; polymer matrix composites; S-N curves; fatigue limits; damage AB Low-cycle fatigue (LCF) behavior of polymer matrix composites (PMCs) is investigated in an experimental study of unidirectional glass/epoxy composites subjected to axial tensile loading along longitudinal 0degrees orientation of fibers. Under high LCF loads, fatigue life of PMCs is found to be less than 10(4) loading cycles due to the high property degradation rates that are noticeably higher than those seen during high-cycle fatigue (HCF). In PMC response, unique LCF features have been identified and linked with damage accumulation patterns in unidirectional composites. At high loads near the ultimate strength of specimens, large strains and finite strain rates are found to be significant under semi-rectangular loading so the LCF behavior is affected. Lower and upper limits for the LCF life impose some restrictions on the S-N curves that are obtained for the LCF life assessment. A bi-linear S-N curve is used to approximate the data in the LCF and HCF regions. The bi-linear S-N relationship and the associated fatigue model are described by a proposed analytical formula. The concept of pre-LCF damage state is introduced. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 USA, Res Lab, AMSRL WM MB, Aberdeen Proving Ground, MD 21005 USA. Univ Delaware, ARL Grp, Ctr Composite Mat, Newark, DE 19716 USA. Natl Nonwoven Inc, E Hampton, MA 01027 USA. RP Harik, VM (reprint author), NASA, ICASE, Langley Res Ctr, MS 132C, Hampton, VA 23681 USA. NR 17 TC 26 Z9 26 U1 4 U2 10 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0142-1123 J9 INT J FATIGUE JI Int. J. Fatigue PD FEB-APR PY 2002 VL 24 IS 2-4 BP 455 EP 462 AR PII S0142-1123(01)00101-3 DI 10.1016/S0142-1123(01)00101-3 PG 8 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 523MK UT WOS:000173957700042 ER PT J AU Hlavka, CA Dungan, JL AF Hlavka, CA Dungan, JL TI Areal estimates of fragmented land cover: effects of pixel size and model-based corrections SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID COARSE SPATIAL-RESOLUTION; AVHRR DATA; EMISSIONS; WETLANDS; IMAGERY; ERRORS; AFRICA; SCALE AB The effects of coarse spatial resolution on the apparent extent of fragmented cover types on digital maps were assessed and a model-based method for correcting for underestimation due to omission of small fragments was tested. Burn scar maps based on Landsat Multispectral Scanner (MSS) imagery and a map of ponds in Arctic tundra based on ERS-1 synthetic aperture radar (SAR) imagery were spatially degraded to simulate EOS Moderate-Resolution Imaging Spectroradiometer (MODIS) and 100m SAR maps. Omission of small fragments on the degraded imagery decreased the apparent extent by as much as 50%. The apparent extent on degraded maps, where various degrees of systematic tendency towards commission were simulated by identification of pixels with less than 50% burn scar or open water, was either close to that measured on the original map (for small classification bias) or overestimated (large classification bias). An area correction procedure based on fitting sizes to a lognormal distribution with censored data was tested. The area correction compensated for 25 to 70% of the underestimation relative to the original maps. Area correction led to inflated areal estimates with biased maps or with a Pareto rather than the lognormal distribution model, indicating that the areal correction procedure must be used judiciously if improved estimates are to be expected. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Calif State Univ, Monterey Bay Ames Res Ctr, Moffett Field, CA 94035 USA. RP Hlavka, CA (reprint author), NASA, Ames Res Ctr, 242-4, Moffett Field, CA 94035 USA. RI Dungan, Jennifer/G-9921-2016 OI Dungan, Jennifer/0000-0002-4863-1616 NR 35 TC 12 Z9 12 U1 0 U2 7 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD FEB PY 2002 VL 23 IS 4 BP 711 EP 724 DI 10.1080/01431160010020092 PG 14 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 508UW UT WOS:000173109000008 ER PT J AU Carpenter, JR AF Carpenter, JR TI Decentralized control of satellite formations SO INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL LA English DT Article ID QUADRATIC-GAUSSIAN CONTROL; TRANSMISSION REQUIREMENTS; COMPUTATION AB A decentralized architecture is proposed for autonomous establishment and maintenance of satellite formations, Such an architecture does not require a central supervisor. as the spacecraft can cooperatively track planned maneuvers and trajectories in the face of disturbances and uncertainties, while processing only local measurement information. If the planned maneuvers and trajectories are themselves optimal, the decentralized framework generates a neighbouring optimal control. Use of such a controller simplifies and improves the robustness of formation operations. since it distributes an autonomous capability for orbit determination and relative navigation. formation maintenance. and maneuver trim among all of the spacecraft. In an example formation flying scenario, the decentralized approach successfully maintains the formation in the face of uncertainties and nonlinear perturbations, and produces identical results to those of a corresponding centralized controller. Published in 2002 by John Wiley Sons, Ltd. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Carpenter, JR (reprint author), NASA, Goddard Space Flight Ctr, Code 572, Greenbelt, MD 20771 USA. EM russell.carpenter@gsfc.nasa.gov NR 21 TC 56 Z9 59 U1 0 U2 13 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 1049-8923 J9 INT J ROBUST NONLIN JI Int. J. Robust Nonlinear Control PD FEB-MAR PY 2002 VL 12 IS 2-3 BP 141 EP 161 DI 10.1002/rnc.680 PG 21 WC Automation & Control Systems; Engineering, Electrical & Electronic; Mathematics, Applied SC Automation & Control Systems; Engineering; Mathematics GA 528LJ UT WOS:000174245000004 ER PT J AU Wright, DL Yu, SC Kasibhatla, PS McGraw, R Schwartz, SE Saxena, VK Yue, GK AF Wright, DL Yu, SC Kasibhatla, PS McGraw, R Schwartz, SE Saxena, VK Yue, GK TI Retrieval of aerosol properties from moments of the particle size distribution for kernels involving the step function: cloud droplet activation SO JOURNAL OF AEROSOL SCIENCE LA English DT Article DE moments; modeling; cloud activation ID OPTICAL-PROPERTIES; ATMOSPHERIC AEROSOLS; RADIATIVE PROPERTIES; II SATELLITE AB Aerosol properties such as the number of particles that activate to form cloud drops and the mass contained within specified size ranges (as in the PM 2.5 and PM 10 regulatory standards) require integration over only part of the full size range of the particle distribution function (PDF) and may be formally expressed as integrals over kernels involving the Heaviside step function. Determination of these properties requires essentially that the size spectrum be partitioned into two (or more) portions, and poses a special challenge for aerosol modeling with the method or moments. To assess the ability of moment-based methods to treat kernels involving step functions, several algorithms for the estimation of aerosol properties associated with cloud activation have been evaluated. For 240 measured continental distributions employed here as test cases, the full size spectrum of the PDF was partitioned into three distinct portions based upon characteristic critical radii for activation in cumulus and stratiform clouds, and mass- and number-concentration metrics were evaluated for each portion. The first six radial moments yielded results accurate to within about 10% or better, on average, and the numbers of particles activated as cloud drops and the aerosol mass taken into cloud water were estimated to an accuracy of 5% or better. Of the moment-based approaches evaluated, the multiple isomomental distribution aerosol surrogate (MIDAS) (Wright, J. Aerosol Sci. 31 (2000) 1) technique performed best. Accurate results were also obtained with the randomized minimization search technique (RMST) (Yue et al., Geophys. Res. Lett. 24 (1997) 651; Heintzenberg et al., Appl. Opt. 20 (1981) 1308). Published by Elsevier Science Ltd. C1 Duke Univ, Nicholas Sch Environm, Durham, NC 27708 USA. Brookhaven Natl Lab, Div Atmospher Sci, Dept Environm Sci, Upton, NY 11973 USA. N Carolina State Univ, Dept Marine Earth & Atmospher Sci, Raleigh, NC 27695 USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Wright, DL (reprint author), Duke Univ, Nicholas Sch Environm, Durham, NC 27708 USA. RI Kasibhatla, Prasad/A-2574-2010; yu, shaocai/G-7806-2011; Schwartz, Stephen/C-2729-2008; yu, shaocai/F-1394-2014; OI Schwartz, Stephen/0000-0001-6288-310X; Kasibhatla, Prasad/0000-0003-3562-3737 NR 14 TC 26 Z9 26 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0021-8502 J9 J AEROSOL SCI JI J. Aerosol. Sci. PD FEB PY 2002 VL 33 IS 2 BP 319 EP 337 DI 10.1016/S0021-8502(01)00172-0 PG 19 WC Engineering, Chemical; Engineering, Mechanical; Environmental Sciences; Meteorology & Atmospheric Sciences SC Engineering; Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA 512HK UT WOS:000173318800008 ER PT J AU Satyanadh, G Joshi, RP Abedin, N Singh, U AF Satyanadh, G Joshi, RP Abedin, N Singh, U TI Monte Carlo calculation of electron drift characteristics and avalanche noise in bulk InAs SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID LIGHT-EMITTING-DIODES; IMPACT-IONIZATION; TRANSPORT-PROPERTIES; ROOM-TEMPERATURE; BAND-STRUCTURE; DEPENDENT TRANSPORT; SEPARATE ABSORPTION; METHANE GAS; DEAD SPACE; III-V AB Field dependent drift velocity results are presented for electron transport in bulk indium arsenide (InAs) material based on a Monte Carlo model, which includes an analytical treatment of band-to-band impact ionization. Avalanche multiplication and related excess noise factor (F) are computed as a function of device length and applied voltage. A decrease in F with increases in device length is obtained. The results suggest an inherent utility for InAs-based single-photon avalanche detectors, particularly around the 2 mum region of interest for atmospheric remote sensing applications. (C) 2002 American Institute of Physics. C1 Old Dominion Univ, Dept Elect & Comp Engn, Norfolk, VA 23529 USA. NASA, Langley Res Ctr, Aerosp Elect Syst Div, Electroopt Branch, Hampton, VA 23681 USA. RP Satyanadh, G (reprint author), Old Dominion Univ, Dept Elect & Comp Engn, Norfolk, VA 23529 USA. NR 72 TC 17 Z9 17 U1 0 U2 5 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 FEB 1 PY 2002 VL 91 IS 3 BP 1331 EP 1338 DI 10.1063/1.1429771 PG 8 WC Physics, Applied SC Physics GA 514CF UT WOS:000173418500066 ER PT J AU Watcharapasorn, A Feigelson, RS Caillat, T Borshchevsky, A Snyder, GJ Fleurial, JP AF Watcharapasorn, A Feigelson, RS Caillat, T Borshchevsky, A Snyder, GJ Fleurial, JP TI Preparation and thermoelectric properties of CeFe4As12 SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID ELECTRONIC-STRUCTURE; REFLECTION SPECTRA; LAFE4P12; COAS3; COSB3; SKUTTERUDITES; COP3 AB The thermoelectric properties of CeFe4As12 have been measured. The compound was synthesized by reacting a powder mixture of CeAs2 and FeAs2 with As metal. The sample was characterized by both x-ray diffractometry and electron microprobe analysis. The Seebeck coefficient, electrical resistivity, Hall effect, and the thermal conductivity were measured between room temperature and about 900 K. The results indicate that CeFe4As12 possesses semimetallic behavior similar to that of CeFe4Sb12 with a room temperature electrical resistivity of 0.49 mOmega cm and a Seebeck coefficient of about 40 muV/K. The thermal conductivity of CeFe4As12 lies between that of CeFe4P12 and CeFe4Sb12 as may be expected from considerations of anionic mass and rattling effect of Ce atoms inside the skutterudite unit cell. A maximum thermoelectric figure of merit value of about 0.4 was obtained at 850 K for this compound. (C) 2002 American Institute of Physics. C1 Stanford Univ, Geballe Lab Adv Mat, Stanford, CA 94305 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Watcharapasorn, A (reprint author), Stanford Univ, Geballe Lab Adv Mat, McCullough Bldg Room 237, Stanford, CA 94305 USA. RI Snyder, G. Jeffrey/E-4453-2011; Snyder, G/I-2263-2015 OI Snyder, G. Jeffrey/0000-0003-1414-8682; NR 24 TC 13 Z9 13 U1 1 U2 9 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 FEB 1 PY 2002 VL 91 IS 3 BP 1344 EP 1348 DI 10.1063/1.1427141 PG 5 WC Physics, Applied SC Physics GA 514CF UT WOS:000173418500068 ER PT J AU Waters, WW Ziegler, MG Meck, JV AF Waters, WW Ziegler, MG Meck, JV TI Postspaceflight orthostatic hypotension occurs mostly in women and is predicted by low vascular resistance SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE microgravity; gender; sympathetic; plasma volume; vascular resistance ID BODY NEGATIVE-PRESSURE; GENDER-RELATED DIFFERENCES; POSTMENOPAUSAL WOMEN; CARDIOVASCULAR-RESPONSES; SIMULATED MICROGRAVITY; NITRIC-OXIDE; SPACEFLIGHT; TOLERANCE; ESTROGEN; HUMANS AB About 20% of astronauts suffer postspaceflight presyncope. We studied pre- to postflight (5- to 16-day missions) cardiovascular responses to standing in 35 astronauts to determine differences between 1) men and women and 2) presyncopal and nonpresyncopal groups. The groups were presyncopal women, presyncopal men, and nonpresyncopal men based on their ability to stand for 10 min postflight. Preflight, women and presyncopal men had low vascular resistance, with the women having the lowest. Postflight, women experienced higher rates of presyncope (100 vs. 20%; P = 0.001) and greater losses of plasma volume (20 vs. 7%; P < 0.05) than men. Also, presyncopal subjects had lower standing mean arterial pressure (P &LE; 0.001) and vascular resistance (P < 0.05), smaller increases in norepinephrine (P less than or equal to 0.058) and greater increases in epinephrine (P less than or equal to 0.058) than nonpresyncopal subjects. Presyncopal subjects had a strong dependence on plasma volume to maintain standing stroke volume. These findings suggest that postflight presyncope is greatest in women, and this can be ascribed to a combination of inherently low-resistance responses, a strong dependence on volume status, and relative hypoadrenergic responses. Conversely, high vascular resistance and postflight hyperadrenergic responses prevent presyncope. C1 NASA, Lyndon B Johnson Space Ctr, Space Life Sci Res Lab, SD3, Houston, TX 77058 USA. Baylor Coll Med, Natl Space Biomed Res Inst, Houston, TX 77030 USA. Univ Calif San Diego, Dept Med, San Diego, CA 92103 USA. RP Meck, JV (reprint author), NASA, Lyndon B Johnson Space Ctr, Space Life Sci Res Lab, SD3, Houston, TX 77058 USA. FU NCRR NIH HHS [M01 RR-08827] NR 38 TC 136 Z9 140 U1 2 U2 11 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD FEB PY 2002 VL 92 IS 2 BP 586 EP 594 PG 9 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 511YB UT WOS:000173293400022 PM 11796668 ER PT J AU Bauer, M Del Genio, AD Lanzante, JR AF Bauer, M Del Genio, AD Lanzante, JR TI Observed and simulated temperature-humidity relationships: Sensitivity to sampling and analysis SO JOURNAL OF CLIMATE LA English DT Article ID SEA-SURFACE TEMPERATURE; GENERAL-CIRCULATION MODELS; TROPOSPHERE WATER-VAPOR; CLIMATE MODELS; SATELLITE; FEEDBACK; PARAMETERIZATION; REANALYSIS; CONVECTION; RADIATION AB Recent studies have demonstrated that the correlation between interannual variations of large-scale average temperature and water vapor is stronger and less height dependent in one GCM than in an objective analysis of radiosonde observations. To address this discrepancy, a GCM with a different approach to cumulus parameterization is used to explore the model dependence of this result, the effect of sampling biases, and the analysis scheme applied to the data. It is found that the globally complete data from the two GCMs produce similar patterns of correlation despite their fundamentally different moist convection schemes. While this result concurs with earlier studies, it is also shown that this apparent model-observation discrepancy is significantly reduced (although not eliminated) by sampling the GCM in a manner more consistent with the observations, and especially if the objective analysis is not then applied to the sampled data. Furthermore, it is found that spatial averages of the local temperature-humidity correlations are much weaker, and show more height dependence, than correlations of the spatially averaged quantities for both model and observed data. The results of the previous studies are thus inconclusive and cannot therefore be interpreted to mean that GCMs greatly overestimate the water vapor feedback. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, New York, NY USA. NOAA, Geophys Fluid Dynam Lab, Princeton, NJ USA. RP Bauer, M (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. RI Del Genio, Anthony/D-4663-2012 OI Del Genio, Anthony/0000-0001-7450-1359 NR 51 TC 21 Z9 21 U1 0 U2 3 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 FEB PY 2002 VL 15 IS 2 BP 203 EP 215 DI 10.1175/1520-0442(2002)015<0203:OASTHR>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 507UE UT WOS:000173049000005 ER PT J AU Su, CH Palosz, W Zhu, S Lehoczky, SL Grzegory, I Perlin, P Suski, T AF Su, CH Palosz, W Zhu, S Lehoczky, SL Grzegory, I Perlin, P Suski, T TI Energy gap in GaN bulk single crystal between 293 and 1237 K SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE nitrides; semiconducting gallium compounds ID LUMINESCENCE; ABSORPTION AB Optical transmission measurements were performed on GaN bulk single-crystal platelet at temperatures between 293 and 1237 K. The energy bandgaps were determined from the corresponding optical absorption spectra. The bandgaps can be fit well as a function of temperature using the Varshni expression as Eg(eV) = 3.556 - 9.9 x 10(-4) T-2 /(T + 600). The shapes of the measured absorption edges were found to be dependent on the thermal treatments of the sample. (C) 2002 Published by Elsevier Science B.V. C1 NASA, George C Marshall Space Flight Ctr, Micrograv Sci & Applicat Dept, Sci Directorate, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. Polish Acad Sci, High Pressure Ctr, UNIPRESS, PL-01142 Warsaw, Poland. RP Su, CH (reprint author), NASA, George C Marshall Space Flight Ctr, Micrograv Sci & Applicat Dept, Sci Directorate, SD46, Huntsville, AL 35812 USA. NR 17 TC 6 Z9 7 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD FEB PY 2002 VL 235 IS 1-4 BP 111 EP 114 DI 10.1016/S0022-0248(01)01834-6 PG 4 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 519TY UT WOS:000173742600017 ER PT J AU Schweizer, M Cobb, SD Volz, MP Szoke, J Szofran, FR AF Schweizer, M Cobb, SD Volz, MP Szoke, J Szofran, FR TI Defect density characterization of detached-grown germanium crystals SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE defects; Bridgman technique; detached Bridgman technique; single crystal growth; semiconducting germanium ID BRIDGMAN GROWTH; GALLIUM; ANGLE; MELT AB Several (1 1 1)-oriented, Ga-doped germanium crystals were grown in pyrolytic boron nitride (pBN) containers by the Bridgman and the detached Bridgman growth techniques. Growth experiments in closed-bottom pBN containers resulted in nearly completely detached-grown crystals, because the gas pressure below the melt can build up to a higher pressure than above the melt. With open-bottom tubes the gas pressure above and below the melt is balanced during the experiment, and thus no additional force supports the detachment. In this case the crystals grew attached to the wall. Etch pit density (EPD) measurements along the axial growth direction indicated a strong improvement of the crystal quality of the detached-grown samples compared to the attached samples. Starting in the seed with an EPD of 6-8 x 10(3) cm(-2) it decreased in the detached-grown crystals continuously to about 200-500 cm(-2). No significant radial difference between the EPD on the edge and the middle of these crystals exists. In the attached grown samples the EPD increases up to a value of about 2-4 x 10(4) cm(-2) (near the edge) and up to 1 x 10(4) cm(-2) in the middle of the sample. Thus the difference between the detached- and the attached-grown crystals with respect to the EPD is approximately two orders of magnitude. (C) 2002 Published by Elsevier Science B.V. C1 NASA, MSFC, USRA, SD47, Huntsville, AL 35812 USA. Univ Miskolc, H-3515 Miskolc, Hungary. RP Schweizer, M (reprint author), NASA, MSFC, USRA, SD47, Huntsville, AL 35812 USA. EM markus.schweizer@msfc.nasa.gov NR 17 TC 19 Z9 19 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD FEB PY 2002 VL 235 IS 1-4 BP 161 EP 166 DI 10.1016/S0022-0248(01)01908-X PG 6 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 519TY UT WOS:000173742600025 ER PT J AU Su, CH Zhu, S Ramachandran, N Burger, A AF Su, CH Zhu, S Ramachandran, N Burger, A TI Beer law constants and vapor pressures of HgI2 over HgI2(s,l) SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE phase equilibria; semiconducting mercury compounds ID MERCURIC IODIDE; STOICHIOMETRY; EVAPORATION AB Optical absorption spectra of the vapor phase over HgI2(s,1) were measured for wavelengths between 200 and 600 nm at sample temperatures between 349 and 610 K. The spectra show that the samples sublimed congruently into HgI2 with no Hg or I-2 absorption spectrum observed. The Beer's Law constants for 15 wavelengths between 200 and 440 nm were determined. From these constants the vapor pressure of HgI2, P, was established as a function of temperature for the liquid and the solid beta-phases: In P(atm) = -7,700/T (K) + 12.462 (liquid phase), In P(atm) = - 10,150/ T (K) + 17.026 (beta-phase). The expressions correspond to the enthalpies of vaporization and sublimation of 15.30 and 20.17 kcal/mole, respectively, for the liquid and the beta-phase HgI2. The difference in the enthalpies gives an enthalpy of fusion of 4.87 kcal/mole, and the intersection of the two expressions gives a melting point of 537 K. Published by Elsevier Science B.V. C1 NASA, George C Marshall Space Flight Ctr, Micrograv Sci & Applicat Dept, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, USRA, Huntsville, AL 35812 USA. Fisk Univ, Ctr Photon Mat & Devices, Dept Phys, Nashville, TN 37208 USA. RP Su, CH (reprint author), NASA, George C Marshall Space Flight Ctr, Micrograv Sci & Applicat Dept, SD46, Huntsville, AL 35812 USA. NR 14 TC 3 Z9 3 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD FEB PY 2002 VL 235 IS 1-4 BP 313 EP 319 DI 10.1016/S0022-0248(01)01806-1 PG 7 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 519TY UT WOS:000173742600050 ER PT J AU Hawkins, SL Varnavskaya, NV Matzak, EA Efremov, VV Guthrie, CM Wilmot, RL Mayama, H Yamazaki, F Gharrett, AJ AF Hawkins, SL Varnavskaya, NV Matzak, EA Efremov, VV Guthrie, CM Wilmot, RL Mayama, H Yamazaki, F Gharrett, AJ TI Population structure of odd-broodline Asian pink salmon and its contrast to the even-broodline structure SO JOURNAL OF FISH BIOLOGY LA English DT Article DE Oncorhynchus gorbuscha; pink salmon; population structure; allozyme; isolation by distance ID NORTH-AMERICAN POPULATIONS; STARCH-GEL ELECTROPHORESIS; ONCORHYNCHUS-GORBUSCHA; GENETIC-VARIATION; GREAT-LAKES AB Most of the variation (99%) of Asian odd-broodline pink salmon Oncorhynchus gorbuscha, based on data at 32 variable (46 total) allozyme loci from 35 populations, occurred within populations, The remaining interpopulation variation was attributable to: (1) differences between northern (the northern Sea of Okhotsk, eastern Kamchatka Peninsula and western Kamchatka Peninsula) and southern (Hokkaido Island. Kuril Islands and Sakhalin Island) populations; (2) differences between the southern areas; (3) low variation among populations within some areas. The pattern contrasted strongly with that observed for Asian even-broodline populations, which had a strong structure, possibly related to geographic and oceanographic influences. Isolation-by-distance analyses of each of the two broodlines showed a stronger relationship (x 4.8) among even- than odd-broodline populations. Allele frequency differences between even- and odd-broodlines reflected the reproductive isolation of the broodlines. However. there were no fixed frequency differences which. considered with the differing population structures, suggests that migration-drift equilibrium has not yet obtained in one or both broodlines. The structural differences also suggest it is likely that the even- and odd-broodlines are of different ages and that one is derived from the other. Allozyme data do not provide a genealogical basis for identifying the ancestral lineage. C1 Univ Alaska Fairbanks, Div Fisheries, Juneau, AK 99801 USA. Auke Bay Lab, Natl Marine Fisheries Serv, Juneau, AK 99801 USA. KamchatNIRO, Kamchatka Sci Res Inst Fisheries & Oceanog, Petropavlovsk Kamchatski 683602, Russia. CENTRE, TINRO, Pacific Res Fisheries Ctr, Vladivostok 690600, Russia. Russian Acad Sci, Far East Branch, Inst Marine Biol, Vladivostok 690041, Russia. Natl Salmon Resources Ctr, Sapporo, Hokkaido 0620922, Japan. Hokkaido Univ, Lab Genet & Embryol, Fac Fisheries, Hakodate, Hokkaido 041, Japan. RP Gharrett, AJ (reprint author), Univ Alaska Fairbanks, Div Fisheries, 1120 Glacier Hwy, Juneau, AK 99801 USA. EM ffajg@uaf.edu NR 49 TC 16 Z9 21 U1 0 U2 2 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 0022-1112 J9 J FISH BIOL JI J. Fish Biol. PD FEB PY 2002 VL 60 IS 2 BP 370 EP 388 DI 10.1006/jfbi.2001.1850 PG 19 WC Fisheries; Marine & Freshwater Biology SC Fisheries; Marine & Freshwater Biology GA 532ZN UT WOS:000174505100009 ER PT J AU Takahashi, K Denton, RE Gallagher, D AF Takahashi, K Denton, RE Gallagher, D TI Toroidal wave frequency at L=6-10: Active Magnetospheric Particle Tracer Explorers/CCE observations and comparison with theoretical model SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article DE ULF waves; AMPTE/CCE; ion flux oscillation; Pc5 waves; mass density; realistic magnetic field ID FIELD LINE RESONANCES; PC 3-4 PULSATIONS; ULF WAVES; GEOMAGNETIC-PULSATIONS; HYDROMAGNETIC-WAVES; MAGNETIC PULSATIONS; ALFVEN WAVES; PLASMA; MULTISATELLITE; SATELLITE AB [1] Magnetospheric standing Alfven waves are guided along the ambient magnetic field, and their frequency depends on the mass density of the plasma distributed along the field lines. These properties allow us to use Alfven waves to map time-dependent phenomena between space and ground and to estimate the mass density. In this paper we present a statistical study of the spatial variation of the fundamental frequency f(T1) of toroidal-mode standing Alfven waves in the L range from 6 to 10, where L indicates the maximum geocentric distance on the field line. The data used for this analysis are energetic particle flux anisotropy (proxy of transverse electric field) and magnetic field measurements from the Active Magnetospheric Particle Tracer Explorers /Charge Composition Explorer (CCE) spacecraft. Using CCE data covering 4 years, we obtained similar to5000 20-min intervals containing a clear signature of toroidal waves. The median f(T1) is 6-10 mHz at L =7 and decreases to 4-8 mHz at L = 9. The frequency tends to be lower at noon than at midnight. The observed frequencies are compared with numerically derived frequencies using an empirical mass density model [Gallagher et al., 2000] and a magnetic field model [Tsyganenko, 1989]. We found a good agreement for 1200-2400 magnetic local time (MLT) but a large discrepancy near 0300 MLT. This may indicate that the flux tubes at this local time are more heavily loaded than specified in Gallagher et al. 's [2000] model. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA. NASA, Dept Space Sci, Marshall Space Flight Ctr, Huntsville, AL 35803 USA. RP Takahashi, K (reprint author), Johns Hopkins Univ, Appl Phys Lab, 11100 Johns Hopkins Rd, Laurel, MD 20723 USA. NR 60 TC 25 Z9 25 U1 0 U2 2 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 FEB PY 2002 VL 107 IS A2 AR 1020 DI 10.1029/2001JA000197 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 609MF UT WOS:000178907600013 ER PT J AU Gill, JJ Ho, K Carman, GP AF Gill, JJ Ho, K Carman, GP TI Three-dimensional thin-film shape memory alloy microactuator with two-way effect SO JOURNAL OF MICROELECTROMECHANICAL SYSTEMS LA English DT Article DE nickel titanium (NiTi); shape memory alloy; thin film; three-dimensional (3-D) transformation; two-way effect ID TINI AB A novel thin film (micrometer thickness) shape memory alloy (SMA) micro actuator is presented in this paper. The thin film SMA with composition of approximately 50:50 nickel titanium (NiTi) is sputter-deposited onto a silicon wafer in an ultra high vacuum system. Transformation temperatures of the NiTi film are determined by measuring the residual stress as a function of temperature. The transformation temperature is independent of the presence of Chromium (Cr) used as an adhesion layer, or being exposed to air before annealing. A mixture of hydrofluoric acid (HF), nitric acid (HNO(3)) and deionized (DI) water is used to etch the film. Different etch masks are evaluated to protect the NiTi film during the etching. Among the masks tested, a thick photoresist (AZ-4620) produces the best result. The NiTi membrane is hot-shaped into a three-dimensional (3-D) dome shape using a stainless-steel jig. Results indicate the membrane exhibits two-way effect. The performance of the SMA micro actuator is characterized with a laser measurement system for deflection versus input power and frequency response. C1 Univ Calif Los Angeles, Mech Aerosp Engn Dept, Los Angeles, CA 90095 USA. RP Gill, JJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM jgill@merlin.jpl.nasa.gov; carman@seas.ucla.edu NR 31 TC 46 Z9 49 U1 2 U2 21 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1057-7157 J9 J MICROELECTROMECH S JI J. Microelectromech. Syst. PD FEB PY 2002 VL 11 IS 1 BP 68 EP 77 DI 10.1109/84.982865 PG 10 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Instruments & Instrumentation; Physics, Applied SC Engineering; Science & Technology - Other Topics; Instruments & Instrumentation; Physics GA 519XP UT WOS:000173751000009 ER PT J AU Liu, WT AF Liu, WT TI Progress in scatterometer application SO JOURNAL OF OCEANOGRAPHY LA English DT Review DE remote-sensing; air-sea interaction; weather wind ID GENERAL-CIRCULATION MODEL; SEA-SURFACE TEMPERATURE; NUMERICAL WEATHER PREDICTION; TROPICAL INSTABILITY WAVES; A SATELLITE SCATTEROMETER; SENSOR MICROWAVE IMAGER; NSCAT WINDS; ERS-SCATTEROMETER; KU-BAND; AMBIGUITY REMOVAL AB Progress in the scientific application of space-based scatterometer data over the past two decades is reviewed. There has been continuous improvement in coverage, resolution, and accuracy. Besides the traditional applications in weather and ocean-atmosphere interaction, which are based on ocean surface wind vectors, emerging applications over land and ice are also described. Future missions and new technology are introduced. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 300-323, Pasadena, CA 91109 USA. EM liu@pacific.jpl.nasa.gov NR 144 TC 153 Z9 169 U1 4 U2 19 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0916-8370 EI 1573-868X J9 J OCEANOGR JI J. Oceanogr. PD FEB PY 2002 VL 58 IS 1 BP 121 EP 136 DI 10.1023/A:1015832919110 PG 16 WC Oceanography SC Oceanography GA 553LF UT WOS:000175676100010 ER PT J AU Katsaros, KB Vachon, PW Liu, WT Black, PG AF Katsaros, KB Vachon, PW Liu, WT Black, PG TI Microwave remote sensing of tropical cyclones from space SO JOURNAL OF OCEANOGRAPHY LA English DT Review DE microwave remote sensing; tropical cyclones; scatterometer; SAR, synthetic-aperture-radar; rain radar ID SYNTHETIC-APERTURE RADAR; NEURAL-NETWORK APPROACH; MEASURING MISSION TRMM; SURFACE WIND FIELDS; ERS-1 SATELLITE; BOUNDARY-LAYER; SCATTEROMETER; IMAGERY; STRESS; MODEL AB This article reviews several microwave instruments employed in research and analysis of tropical cyclones (TCs), typhoons, and hurricanes. The instruments discussed include scatterometers, microwave radiometers, synthetic aperture radars (SARs), and rain radar from space. Examples of the particular contribution by one or more of these instruments in analysis of several storms illustrate the comprehensive new views provided by the SeaWinds scatterometers, the detailed high-resolution wind field provided by RADARSAT-1 SAR, particularly inside and in the vicinity of hurricane "eyes," and the presence of secondary flows in the region between rainbands in TCs. The high spatial resolution of precipitation data from the Tropical Rainfall Measuring Mission's rain radar, combined with scatterometer or SAR data, give a significant improvement in the details that can be seen from space, at the surface, and in the precipitating areas of TCs. The microwave instruments provide a penetrating view below the upper level cirrus clouds. C1 NOAA, Atlantic Oceanog & Meteorol Lab, Miami, FL 33149 USA. Canada Ctr Remote Sensing, Ottawa, ON K1A 0Y7, Canada. Jet Prop Lab, Pasadena, CA 91109 USA. RP Katsaros, KB (reprint author), NOAA, Atlantic Oceanog & Meteorol Lab, 4301 Rickenbacker Causeway, Miami, FL 33149 USA. NR 66 TC 50 Z9 53 U1 4 U2 17 PU TERRA SCIENTIFIC PUBL CO PI TOKYO PA 2003 SANSEI JIYUGAOKA HAIMU, 5-27-19 OKUSAWA, SETAGAYA-KU, TOKYO, 158, JAPAN SN 0916-8370 J9 J OCEANOGR JI J. Oceanogr. PD FEB PY 2002 VL 58 IS 1 BP 137 EP 151 DI 10.1023/A:1015884903180 PG 15 WC Oceanography SC Oceanography GA 553LF UT WOS:000175676100011 ER PT J AU Shan, HZ Singh, JP Oliker, L Biswas, R AF Shan, HZ Singh, JP Oliker, L Biswas, R TI A comparison of three programming models for adaptive applications on the Origin2000 SO JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING LA English DT Article; Proceedings Paper CT Supercomputing Conference 2000 (SC2000) CY NOV 04-10, 2000 CL DALLAS, TX DE parallel programming; shared address space; message passing; dynamic mesh adaptation; N-body problem ID N-BODY METHODS; ALGORITHM AB Adaptive applications have computational workloads and communication patterns that change unpredictably at runtime, requiring dynamic load balancing to achieve scalable performance on parallel machines. Efficient parallel implementations of such adaptive applications is therefore a challenging task. In this paper, we compare the performance of and the programming effort required for two major classes of adaptive applications under three leading parallel programming models on an SGI Origin2000 system, a machine that supports all three models efficiently. Results indicate that the three models deliver comparable performance; however, the implementations differ significantly beyond merely using explicit messages versus implicit loads/stores even though the basic parallel algorithms are similar. Compared with the message-passing (using MPI) and SHMEM programming models, the cache-coherent shared address space (CC-SAS) model provides substantial ease of programming at both the conceptual and program orchestration levels, often accompanied by performance gains. However, CC-SAS currently has portability limitations and may suffer from poor spatial locality of physically distributed shared data on large numbers of processors. (C) 2002 Elsevier Science (USA). C1 Princeton Univ, Dept Comp Sci, Princeton, NJ 08544 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Natl Energy Res Sci Comp Ctr, Berkeley, CA 94720 USA. NASA, Adv Supercomp Div, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Princeton Univ, Dept Comp Sci, 35 Olden St, Princeton, NJ 08544 USA. EM shz@cs.princeton.edu; jps@cs.princeton.edu; loliker@lbl.gov; rbiswas@nas.nasa.gov NR 24 TC 13 Z9 13 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0743-7315 EI 1096-0848 J9 J PARALLEL DISTR COM JI J. Parallel Distrib. Comput. PD FEB PY 2002 VL 62 IS 2 BP 241 EP 266 DI 10.1006/jpdc.2001.1777 PG 26 WC Computer Science, Theory & Methods SC Computer Science GA 525ZB UT WOS:000174103000005 ER PT J AU Venkateswaran, S Rai, MM Govindan, TR Meyyappan, M AF Venkateswaran, S Rai, MM Govindan, TR Meyyappan, M TI Neural network modeling of growth processes SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article AB Process control based on physics-based modeling requires detailed real-time reactor simulations, which are currently not realistic. For such process control models to be feasible, information from reactor simulations must therefore be represented in a compact model. In this paper, we have developed a neural network based model for chemical vapor deposition. Detailed reactor simulations are used to train the neural network and the network predictions are then validated by additional simulations. We show that the current model is capable of accurately representing the process parameter space, thereby enabling use of the trained network for process control and design. (C) 2002 The Electrochemical Society. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Venkateswaran, S (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 11 TC 5 Z9 5 U1 0 U2 0 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 65 SOUTH MAIN STREET, PENNINGTON, NJ 08534 USA SN 0013-4651 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD FEB PY 2002 VL 149 IS 2 BP G137 EP G142 DI 10.1149/1.1430721 PG 6 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA 521QX UT WOS:000173853800049 ER PT J AU Kimiaghalam, B Homaifar, A Bikdash, M Hunt, BR AF Kimiaghalam, B Homaifar, A Bikdash, M Hunt, BR TI Feedforward control law for a shipboard crane with Maryland Rigging system SO JOURNAL OF VIBRATION AND CONTROL LA English DT Article DE crane control; feedforward control; nonlinear control; swinging suppression AB A state-space model of the Maryland Rigging shipboard crane is derived from Newton's law under the assumptions of boom stiffness, fully controllable boom motion, no cable elasticity, no damping, and full control authority for changing the length of the rope. A chaotic rolling moment, with a dominant frequency of the same order as the resonance frequency of the shipboard crane, is applied to the ship as an external disturbance. The effect of this disturbance is studied. Since designing a controller by means of analytical methods for this system is too complex, we use a novel approach to this problem that focuses on the equilibrium point. By deriving the equations for calculating the position of the equilibrium point of the load in space, we change the problem to minimizing the change in the position of this point. A feedforward type controller is then designed as to keep the load closest to the "equilibrium point" for the actual roll angle. The controller seeks to suppress the load sway caused by the ship's rolling motion by changing the luffing angle while the friction in the pulley is assumed to be negligible. Changing the luffing angle seems to be the most effective control action in shipboard cranes. The feedforward gain is then optimized by numerical methods. The simulation results for this controller show a huge decrease in the sway magnitude as compared to the cases with no control. The roll angle, luffing angle of the boom, and the length of the rope are changed individually and then the related optimum feedforward gains are numerically obtained. Using these data, the mapping of the optimum gain based on these variables is derived. Scheduling the gain based on this mapping greatly improves the performance of the feedforward controller. This procedure can be repeated for similar applications. C1 N Carolina Agr & Tech State Univ, Dept Elect Engn, NASA, Autonomous Control Engn Ctr,Dept Elect Engn, Greensboro, NC 27411 USA. Univ Maryland, Dept Math, College Pk, MD 20742 USA. RP Kimiaghalam, B (reprint author), N Carolina Agr & Tech State Univ, Dept Elect Engn, NASA, Autonomous Control Engn Ctr,Dept Elect Engn, Greensboro, NC 27411 USA. RI Hunt, Brian/J-6895-2012 NR 10 TC 3 Z9 4 U1 2 U2 3 PU SAGE PUBLICATIONS LTD PI LONDON PA 6 BONHILL STREET, LONDON EC2A 4PU, ENGLAND SN 1077-5463 J9 J VIB CONTROL JI J. Vib. Control PD FEB PY 2002 VL 8 IS 2 BP 159 EP 188 PG 30 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 553AF UT WOS:000175652600004 ER PT J AU Bruyns, CD Senger, S Menon, A Montgomery, K Wildermuth, S Boyle, R AF Bruyns, CD Senger, S Menon, A Montgomery, K Wildermuth, S Boyle, R TI A survey of interactive mesh-cutting techniques and a new method for implementing generalized interactive mesh cutting using virtual tools SO JOURNAL OF VISUALIZATION AND COMPUTER ANIMATION LA English DT Article DE modeling; simulation; procedural simulation and training; haptic interfaces AB In our experience, mesh-cutting methods can be distinguished by how their solutions address the following major issues: definition of the cut path, primitive removal and re-meshing, number of new primitives created, when re-meshing is performed, and representation of the cutting tool, Many researches have developed schemes for interactive mesh cutting with the goals of reducing the number of new primitives created, creating new primitives with good aspect ratios, avoiding a disconnected mesh structure between primitives in the cut path, and representing the path traversed by the tool as accurately as possible. The goal of this paper is to explain how, by using a very simple framework, one can build a generalized cutting scheme. This method allows for any arbitrary cut to be made within a virtual object, and can simulate cutting surface, layered surface or tetrahedral objects using a virtual scalpel, scissors, or loop cautery tool. This method has been implemented in a real-time, haptic-rate surgical simulation system allowing arbitrary cuts to be made on high-resolution patient-specific models. Published in 2002 by John Wiley Sons, Ltd. C1 NASA, Ames Res Ctr, BioVis Lab, Moffett Field, CA 94035 USA. Univ Wisconsin, La Crosse, WI 54601 USA. Univ Zurich Hosp, Inst Diagnost Radiol, CH-8091 Zurich, Switzerland. RP Stanford Univ, Natl Biocomp Ctr, 701A Welch Rd,Suite 1128, Stanford, CA 94305 USA. EM bruyns@biocomp.stanford.edu NR 30 TC 33 Z9 38 U1 0 U2 2 PU JOHN WILEY & SONS LTD PI CHICHESTER PA THE ATRIUM, SOUTHERN GATE, CHICHESTER PO19 8SQ, W SUSSEX, ENGLAND SN 1049-8907 J9 J VISUAL COMP ANIMAT JI J. Vis. Comput. Animat. PD FEB PY 2002 VL 13 IS 1 BP 21 EP 42 DI 10.1002/vis.275 PG 22 WC Computer Science, Software Engineering SC Computer Science GA 583KV UT WOS:000177407800003 ER PT J AU DellaCorte, C AF DellaCorte, C TI Diminished harvest - Who will help me plant the corn? SO LUBRICATION ENGINEERING LA English DT Editorial Material C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP DellaCorte, C (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD FEB PY 2002 VL 58 IS 2 BP 3 EP + PG 2 WC Engineering, Mechanical SC Engineering GA 513HZ UT WOS:000173373600001 ER PT J AU Deshpande, AD Draxler, AFJ Zdanowicz, VS Schrock, ME Paulson, AJ AF Deshpande, AD Draxler, AFJ Zdanowicz, VS Schrock, ME Paulson, AJ TI Contaminant levels in the muscle of four species of fish important to the recreational fishery of the New York Bight Apex SO MARINE POLLUTION BULLETIN LA English DT Article C1 Natl Marine Fisheries Serv, Highlands, NJ 07732 USA. Battelle Mem Inst, Columbus, OH 43201 USA. RP Natl Marine Fisheries Serv, 74 Magruder Rd, Highlands, NJ 07732 USA. EM ashok.deshpande@noaa.gov NR 18 TC 13 Z9 13 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0025-326X EI 1879-3363 J9 MAR POLLUT BULL JI Mar. Pollut. Bull. PD FEB PY 2002 VL 44 IS 2 BP 164 EP 171 AR PII S0025-326X(01)00223-5 DI 10.1016/S0025-326X(01)00223-5 PG 8 WC Environmental Sciences; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 532JN UT WOS:000174471300020 PM 11981981 ER PT J AU Mackey, JR Salari, E Tin, P AF Mackey, JR Salari, E Tin, P TI Optical material stress measurement using two orthogonally polarized sinusoidally intensity-modulated semiconductor lasers SO MEASUREMENT SCIENCE AND TECHNOLOGY LA English DT Article DE stress; retardance; birefringence; polarization; laser; optoelectronic ID MUELLER MATRIX; LIGHT; BIREFRINGENCE AB A novel, compact, robust and highly versatile polarization-modulated electro-optical instrument for measuring material properties, fluid flow parameters, stress, strain and molecular structure of optically anisotropic materials has been developed in this paper. The new instrumentation uses two polarized laser beams. Each beam is linearly polarized with the two polarization states orthogonal to each other. The laser beams are sinusoidally intensity modulated with 180degrees phase difference by two laser drivers and a signal inverter connected to the output of one of the laser driver circuits. The anti-phase intensity modulation of each orthogonal polarization increases the instrument's sensitivity through the use of heterodyning signal analysis techniques with a single lock-in amplifier (LIA). When the two semiconductor laser beams are optically combined, the result produces a laser beam with a constant optical power level comprised of time-varying power levels in each orthogonal polarization state. The polarization state of the laser light is modulated without the use of a traditional modulator. The instrument photodetector produces a direct-current signal along with a periodic signal at the modulation frequency that is recovered by a LIA tuned to the modulation frequency. By combining these signals in the appropriate relationship, a material's phase retardance or average molecular orientation angle may be measured. The main advantages of this technique over existing methods are lower cost due to the lack of an optical modulator, small size when compared to a photoelastically modulated system and improved sensitivity over continuous-wave laser crossed-polarizer instruments. C1 Univ Toledo, Dept Elect Engn & Comp Sci, Toledo, OH 43606 USA. NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. RP Univ Toledo, Dept Elect Engn & Comp Sci, 2801 W Bancroft St, Toledo, OH 43606 USA. EM jrmackey@en.com; esalari@uoft02.utoledo.edu; padetha.tin@grc.nasa.gov NR 25 TC 10 Z9 10 U1 0 U2 3 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0957-0233 EI 1361-6501 J9 MEAS SCI TECHNOL JI Meas. Sci. Technol. PD FEB PY 2002 VL 13 IS 2 BP 179 EP 185 DI 10.1088/0957-0233/13/2/307 PG 7 WC Engineering, Multidisciplinary; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 532TP UT WOS:000174491400007 ER PT J AU Greshake, A Krot, AN Meibom, A Weisberg, MK Zolensky, ME Keil, K AF Greshake, A Krot, AN Meibom, A Weisberg, MK Zolensky, ME Keil, K TI Heavily-hydrated lithic clasts in CH chondrites and the related, metal-rich chondrites Queen Alexandra Range 94411 and Hammadah al Hamra 237 SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID CARBONACEOUS CHONDRITE; AQUEOUS ALTERATION; NITROGEN ISOTOPE; ALH85085; ORIGIN; GRAINS; METEORITES; BENCUBBIN AB Fine-grained, heavily-hydrated lithic clasts in the metal-rich (CB) chondrites Queen Alexandra Range (QUE) 94411 and Hammadah al Hamra 237 and CH chondrites, such as Patuxent Range (PAT) 91546 and Allan Hills (ALH) 85085, are mineralogically similar suggesting genetic relationship between these meteorites. These clasts contain no anhydrous silicates and consist of framboidal and platelet magnetite, prismatic sulfides (pentlandite and pyrrhotite), and Fe-Mn-Mg-bearing Ca-carbonates set in a phyllosilicate-rich matrix. Two types of phyllosilicates were identified: serpentine, with basal spacing of similar to0.73 nm, and saponite, with basal spacings of about 1.1-1.2 nm. Chondrules and FeNi-metal grains in CB and CH chondrites are believed to have formed at high temperature (>1300 K) by condensation in a solar nebula region that experienced complete vaporization. The absence of aqueous alteration of chondrules and metal grains in CB and CH chondrites indicates that the clasts experienced hydration in an asteroidal setting prior to incorporation into the CH and CB parent bodies. The hydrated clasts were either incorporated during regolith gardening or accreted together with chondrules and FeNi-metal gains after these high-temperature components had been transported from their hot formation region to a much colder region of the solar nebula. C1 Humboldt Univ, Inst Mineral, Museum Nat Kunde, D-10115 Berlin, Germany. Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Stanford Univ, Palo Alto, CA 94305 USA. Kingsborough Coll, Brooklyn, NY 11235 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Greshake, A (reprint author), Humboldt Univ, Inst Mineral, Museum Nat Kunde, Invalidenstr 43, D-10115 Berlin, Germany. NR 40 TC 38 Z9 38 U1 0 U2 2 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD FEB PY 2002 VL 37 IS 2 BP 281 EP 293 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 545XK UT WOS:000175242700011 ER PT J AU Duda, DP Minnis, P AF Duda, DP Minnis, P TI Observations of aircraft dissipation trails from GOES SO MONTHLY WEATHER REVIEW LA English DT Article ID HIGHLY SUPERCOOLED ALTOCUMULUS; RADIATIVE PROPERTIES; CLOUD PROPERTIES; ICE PARTICLES; CIRRUS AB Two cases of aircraft dissipation trails (distrails) with associated fall streak clouds were analyzed with multispectral geostationary satellite data. One dissipation trail was observed in a single cloud layer on 23 July 2000 over southeastern Virginia and the Chesapeake Bay. Another set of trails developed at the top of multilayer cloudiness off the coasts of Georgia and South Carolina on 6 January 2000. The distrails on both days formed in optically thin, midlevel stratified clouds with cloud-top heights between 7.6 and 9.1 km. The distrail features remained intact and easily visible from satellite images over a period of 1-2 h despite winds near 50 kt at cloud level. The width of the distrails became as large as 20 km within a period of 90 min or less. Differences between the optical properties of the fall streak particles inside the distrails and those of the clouds surrounding the trails allowed for the easy identification of the fall streak clouds in either the 3.9-mum brightness temperature imagery, or the 10.7-mum minus 12.0-mum brightness temperature difference imagery. Two independent remote sensing retrievals of both distrail cases showed that the fall streaks had larger particle sizes than the clouds outside of the trails, although the three-channel infrared retrieval was better at retrieving cloud properties in the multilayer cloud case. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Hampton Univ, Ctr Atmospher Sci, Hampton, VA 23668 USA. RP Duda, DP (reprint author), NASA, Langley Res Ctr, Mail Stop 420,21 Langley Blvd, Hampton, VA 23681 USA. RI Minnis, Patrick/G-1902-2010 OI Minnis, Patrick/0000-0002-4733-6148 NR 19 TC 2 Z9 2 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD FEB PY 2002 VL 130 IS 2 BP 398 EP 406 DI 10.1175/1520-0493(2002)130<0398:OOADTF>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 509YL UT WOS:000173177800012 ER PT J AU McCaul, EW Buechler, DE Hodanish, S Goodman, SJ AF McCaul, EW Buechler, DE Hodanish, S Goodman, SJ TI The Almena, Kansas, tornadic storm of 3 June 1999: A long-lived supercell with very little cloud-to-ground lightning SO MONTHLY WEATHER REVIEW LA English DT Article ID THUNDERSTORM AB The visual, radar, and lightning characteristics of a severe thunderstorm that spawned a large F3 tornado near Almena, Kansas, on 3 June 1999 are documented. The storm is interesting in that it made a transition from a low-precipitation to classic supercell then back to low-precipitation supercell again prior to dissipation after sunset. The storm remarkably produced only 17 cloud-to-ground lightning flashes during its 4.5-h lifetime, despite vertically integrated liquid (VIL) values reaching 95 kg m(-2), reflectivities of 50 dBZ or greater at altitudes of 14 km, and baseball-size hail at the surface. In contrast, total lightning rates inferred from a portable lightning detector during the large tornado were very high, approximately 100 per minute, as expected for a storm of this size and intensity. C1 NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. Univ Alabama, Huntsville, AL 35899 USA. Natl Weather Serv, NOAA, Pueblo, CO USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP McCaul, EW (reprint author), Inst Global Change Res & Educ, 4950 Corp Dr,Suite 200, Huntsville, AL 35806 USA. NR 20 TC 15 Z9 16 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD FEB PY 2002 VL 130 IS 2 BP 407 EP 415 DI 10.1175/1520-0493(2002)130<0407:TAKTSO>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 509YL UT WOS:000173177800013 ER PT J AU Adriani, O Ambriola, M Barbarino, G Barbier, LM Bartalucci, S Bazilevskaja, G Bellotti, R Bertazzoni, S Bidoli, V Boezio, M Bogomolov, E Bonechi, L Bonvicini, V Boscherini, M Bravar, U Cafagna, F Campana, D Carlson, P Casolino, M Castellano, M Castellini, G Christian, ER Ciacio, F Circella, M D'Alessandro, R De Marzo, CN De Pascale, MP Finetti, N Furano, G Gabbanini, A Galper, AM Giglietto, N Grandi, M Grigorjeva, A Guarino, F Hof, M Koldashov, SV Korotkov, MG Krizmanic, JF Krutkov, S Lund, J Marangelli, B Marino, L Menn, W Mikhailov, VV Mirizzi, N Mitchell, JW Mocchiutti, E Moiseev, AA Morselli, A Mukhametshin, R Ormes, JF Osteria, G Ozerov, JV Papini, P Pearce, M Perego, A Piccardi, S Picozza, P Ricci, M Salsano, A Schiavon, P Scian, G Simon, M Sparvoli, R Spataro, B Spillantini, P Spinelli, P Stephens, SA Stochaj, SJ Stozhkov, Y Straulino, S Streitmatter, RE Taccetti, F Tesi, M Vacchi, A Vannuccini, E Vasiljev, G Vignoli, V Voronov, SA Yurkin, Y Zampa, G Zampa, N AF Adriani, O Ambriola, M Barbarino, G Barbier, LM Bartalucci, S Bazilevskaja, G Bellotti, R Bertazzoni, S Bidoli, V Boezio, M Bogomolov, E Bonechi, L Bonvicini, V Boscherini, M Bravar, U Cafagna, F Campana, D Carlson, P Casolino, M Castellano, M Castellini, G Christian, ER Ciacio, F Circella, M D'Alessandro, R De Marzo, CN De Pascale, MP Finetti, N Furano, G Gabbanini, A Galper, AM Giglietto, N Grandi, M Grigorjeva, A Guarino, F Hof, M Koldashov, SV Korotkov, MG Krizmanic, JF Krutkov, S Lund, J Marangelli, B Marino, L Menn, W Mikhailov, VV Mirizzi, N Mitchell, JW Mocchiutti, E Moiseev, AA Morselli, A Mukhametshin, R Ormes, JF Osteria, G Ozerov, JV Papini, P Pearce, M Perego, A Piccardi, S Picozza, P Ricci, M Salsano, A Schiavon, P Scian, G Simon, M Sparvoli, R Spataro, B Spillantini, P Spinelli, P Stephens, SA Stochaj, SJ Stozhkov, Y Straulino, S Streitmatter, RE Taccetti, F Tesi, M Vacchi, A Vannuccini, E Vasiljev, G Vignoli, V Voronov, SA Yurkin, Y Zampa, G Zampa, N TI The PAMELA experiment on satellite and its capability in cosmic rays measurements SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 9th International Vienna Conference on Instrumentation CY FEB 19-23, 2001 CL VIENNA, AUSTRIA SP Austrian Fed Minist Educ Sci & Culture, Vienna Convent Bur, Univ Technol, Austrian Airlines, Bank Austria AG, Cambridge Univ Press DE satellite experiment; cosmic rays; antimatter AB The PAMELA equipment will be assembled in 2001 and installed on board the Russian satellite Resurs. PAMELA is conceived mainly to study the antiproton and positron fluxes in cosmic rays up to high energy (190 GeV for (p) over bar and 270 GeV for e(+)) and to search antinuclei, up to 30 GeV/n, with a sensitivity of 10(-7) in the He/He ratio. The PAMELA telescope consists of. a magnetic spectrometer made up of a permanent magnet system equipped with double sided microstrip silicon detectors a transition radiation detector made up of active layers of proportional straw tubes interleaved with carbon fibre radiators; and a silicon-tungsten imaging calorimeter made up of layers of tungsten absorbers and silicon detector planes. A time-of-flight system and anti-coincidence counters complete the PAMELA equipment. In the past years, tests have been done on each subdetector of PAMELA; the main results are presented and their implications on the anti-particles identification capability in cosmic rays are discussed here. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Univ Florence, I-50125 Florence, Italy. Ist Nazl Fis Nucl, Sez Firenze, I-50125 Florence, Italy. Univ Bari, Bari, Italy. Ist Nazl Fis Nucl, I-70126 Bari, Italy. Univ Naples, Naples, Italy. Ist Nazl Fis Nucl, I-80125 Naples, Italy. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Ist Nazl Fis Nucl, Lab Nazl Frascati, I-00044 Frascati, Italy. PN Lebedev Phys Inst, Moscow 117924, Russia. Univ Roma Tor Vergata, Dept Elect Engn, I-00173 Rome, Italy. Ist Nazl Fis Nucl, Rome, Italy. Univ Trieste, Trieste, Italy. Ist Nazl Fis Nucl, Trieste, Italy. AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia. Univ Siegen, Dept Phys, D-5900 Siegen, Germany. NMSU, Particle Astrophys Lab, Las Cruces, NM USA. Royal Inst Technol, Stockholm, Sweden. CNR, Ist Ric Onde Elettromagnet, I-50127 Florence, Italy. Moscow Engn & Phys Inst, Moscow, Russia. Tata Inst Fundamental Res, Bombay 400005, Maharashtra, India. RP Straulino, S (reprint author), Univ Florence, Largo Enrico Fermi 2, I-50125 Florence, Italy. RI Christian, Eric/D-4974-2012; D'Alessandro, Raffaello/F-5897-2015; Barbarino, Giancarlo/L-2559-2015; Galper, Arkady/M-9610-2015; Morselli, Aldo/G-6769-2011; giglietto, nicola/I-8951-2012; Castellano, Marcello/J-3428-2012; Cafagna, Francesco/A-9299-2010; Mocchiutti, Emiliano/I-8049-2013; Mikhailov, Vladimir/B-5368-2014; Vasilyev, Gennady/E-4843-2014; Krutkov, Sergey/E-7561-2014; Vacchi, Andrea/C-1291-2010; Voronov, Sergey/P-9654-2016; Guarino, Fausto/I-3166-2012; OI Vignoli, Valerio/0000-0003-2509-6566; Papini, Paolo/0000-0003-4718-2895; Boezio, Mirko/0000-0002-8015-2981; Christian, Eric/0000-0003-2134-3937; D'Alessandro, Raffaello/0000-0001-7997-0306; Barbarino, Giancarlo/0000-0001-9253-3397; Morselli, Aldo/0000-0002-7704-9553; giglietto, nicola/0000-0002-9021-2888; Castellano, Marcello/0000-0002-4211-2903; Cafagna, Francesco/0000-0002-7450-4784; Mocchiutti, Emiliano/0000-0001-7856-551X; Mikhailov, Vladimir/0000-0003-3851-2901; Vacchi, Andrea/0000-0003-3855-5856; Voronov, Sergey/0000-0002-9209-0618; Guarino, Fausto/0000-0003-1427-9885; Taccetti, Francesco/0000-0003-2657-2990; Bellotti, Roberto/0000-0003-3198-2708; casolino, marco/0000-0001-6067-5104; Castellini, Guido/0000-0002-0177-0643; SPATARO, BRUNO/0000-0002-3036-2657; Sparvoli, Roberta/0000-0002-6314-6117; Picozza, Piergiorgio/0000-0002-7986-3321 NR 2 TC 22 Z9 24 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD FEB 1 PY 2002 VL 478 IS 1-2 BP 114 EP 118 AR PII S0168-9002(01)01726-0 DI 10.1016/S0168-9002(01)01726-0 PG 5 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 527UB UT WOS:000174205100015 ER PT J AU Deines-Jones, P Black, JK Hunter, SD Jahoda, K Owens, SM AF Deines-Jones, P Black, JK Hunter, SD Jahoda, K Owens, SM TI Large-area imaging micro-well detectors for high-energy astrophysics SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 9th International Vienna Conference on Instrumentation CY FEB 19-23, 2001 CL VIENNA, AUSTRIA SP Austrian Fed Minist Educ Sci & Culture, Vienna Convent Bur, Univ Technol, Austrian Airlines, Bank Austria AG, Cambridge Univ Press DE x-ray imager; electron track imager; micro-pattern detector; micro-well; large area imager; lobster ID GAS DETECTORS AB Micro-well detectors are pixelized imaging sensors that can be inexpensively fabricated in very large arrays. Owing to their intrinsic gain and operation at room temperature, they can be instrumented at very low power, per unit area, making them valuable for a variety of space-flight applications where wide-angle X-ray imaging or large-area particle tracking is required. For example, micro-well detectors have been chosen as the focal plane imager for Lobster-ISS, a proposed soft X-ray all-sky monitor. We have fabricated detectors which image X-rays with 200 mum FWHM resolution at 3 keV. In agreement with other groups using similar geometries, we find nominal proportional counter energy resolution (20% at 6 keV in P-10), and stable operation at gas gains up to 30,000. (C) 2002 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Greenbelt, MD 20771 USA. RP Deines-Jones, P (reprint author), NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Code 661, Greenbelt, MD 20771 USA. RI Hunter, Stanley/D-2942-2012; Jahoda, Keith/D-5616-2012 NR 9 TC 15 Z9 15 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD FEB 1 PY 2002 VL 478 IS 1-2 BP 130 EP 134 AR PII S0168-9002(01)01732-6 DI 10.1016/S0168-9002(01)01732-6 PG 5 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 527UB UT WOS:000174205100019 ER PT J AU Pan, XG Barker, PF Meschanov, A Grinstead, JH Shneider, MN Miles, RB AF Pan, XG Barker, PF Meschanov, A Grinstead, JH Shneider, MN Miles, RB TI Temperature measurements by coherent Rayleigh scattering SO OPTICS LETTERS LA English DT Article ID LASER; GRATINGS; FLOW AB We demonstrate, for the first time to our knowledge, the utility of coherent Rayleigh scattering (CRS) for temperature measurements in low-density gases and weakly ionized plasmas by measuring the translational temperature of neutral argon in a glow discharge. By analysis of the near-Gaussian spectral profile of the CRS signal, we determine temperatures with an uncertainty of less than or equal to3%. We also investigate the intensity range over which this simple Gaussian analysis can be used for temperature measurements and discuss its potential for gas diagnostics. (C) 2002 Optical Society of America. C1 Princeton Univ, Dept Mech & Aerosp Engn, Princeton, NJ 08544 USA. Heriot Watt Univ, Dept Phys, Edinburgh EH14 4AS, Midlothian, Scotland. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Pan, XG (reprint author), Princeton Univ, Dept Mech & Aerosp Engn, Princeton, NJ 08544 USA. RI Barker, Peter/A-4581-2011; OI Barker, Peter/0000-0001-9669-9853 NR 12 TC 29 Z9 29 U1 1 U2 7 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD FEB 1 PY 2002 VL 27 IS 3 BP 161 EP 163 DI 10.1364/OL.27.000161 PG 3 WC Optics SC Optics GA 514PA UT WOS:000173449200005 PM 18007742 ER PT J AU Hay, SI Myers, MF Maynard, N Rogers, DJ AF Hay, SI Myers, MF Maynard, N Rogers, DJ TI From remote sensing to relevant sensing in human health - Introduction SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Editorial Material C1 Univ Oxford, Dept Zool, Trypanosomiasis & Land Use Africa Res Grp, Oxford OX1 3PS, England. Kenya Govt Med Res Ctr, Wellcome Trust Collaborat Programme, Nairobi, Kenya. Decis Syst Technol Inc, Rockville, MD 20850 USA. NASA, Goddard Space Flight Ctr, Environm Hlth Program, Greenbelt, MD 20771 USA. RP Hay, SI (reprint author), Univ Oxford, Dept Zool, Trypanosomiasis & Land Use Africa Res Grp, S Parks Rd, Oxford OX1 3PS, England. RI Hay, Simon/F-8967-2015 OI Hay, Simon/0000-0002-0611-7272 NR 10 TC 4 Z9 4 U1 0 U2 1 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 USA SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD FEB PY 2002 VL 68 IS 2 BP 109 EP 111 PG 3 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA 518DB UT WOS:000173650400001 ER PT J AU Rogers, DJ Myers, MF Tucker, CJ Smith, PF White, DJ AF Rogers, DJ Myers, MF Tucker, CJ Smith, PF White, DJ TI Predicting the distribution of West Nile Fever SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article C1 Univ Oxford, Dept Zool, Trypanosomiasis & Land Use Africa Res Grp, Oxford OX1 3PS, England. Decis Syst Technol Inc, Rockville, MD 20850 USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Terr Phys Lab, Greenbelt, MD 20771 USA. New York State Dept Hlth, Albany, NY 12237 USA. RP Rogers, DJ (reprint author), Univ Oxford, Dept Zool, Trypanosomiasis & Land Use Africa Res Grp, S Parks Rd, Oxford OX1 3PS, England. RI Hay, Simon/F-8967-2015 OI Hay, Simon/0000-0002-0611-7272 NR 7 TC 18 Z9 18 U1 0 U2 1 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 USA SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD FEB PY 2002 VL 68 IS 2 BP 112 EP 114 PG 3 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA 518DB UT WOS:000173650400002 ER PT J AU Anyamba, A Linthicum, KJ Mahoney, R Tucker, CJ Kelley, PW AF Anyamba, A Linthicum, KJ Mahoney, R Tucker, CJ Kelley, PW TI Mapping potential risk of Rift Valley fever outbreaks in African savannas using vegetation index time series data SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article ID NINO SOUTHERN OSCILLATION; EL-NINO; EAST-AFRICA; RAINFALL FLUCTUATIONS; DOMESTIC-ANIMALS; SATELLITE DATA; WEST-AFRICA; NOAA AVHRR; KENYA; VIRUS AB Rift Valley fever (RVF) outbreaks in East Africa are closely coupled with above normal rainfall that is associated with the occurrence of the warm phase of the El Nino/Southern Oscillation (ENSO) phenomenon. Outbreaks elsewhere in central and southern Africa are also linked to elevated rainfall patterns. Major RVF activity has been reported to occur throughout much of sub-Saharan Africa, except in areas with extensive tropical forest, In this study we used normalized difference vegetation index (NDVI) time-series data derived from the Advanced Very High Resolution Radiometer (AVHRR) instrument on polar orbiting National Oceanographic and Atmospheric Administration (NOAA) satellites to map areas with a potential for an RVF outbreak. A 19-year NDVI climatology was created and used to discriminate between areas with tropical forest, savanna, and desert. Because most RVF outbreaks have occurred in regions dominated by savanna vegetation, we created a mask to identify those areas where RVF would likely occur within the savanna ecosystems. NDVI anomalies were then calculated for the entire time Series from July 1981 to the July 2000. Subsequently, we developed a methodology that detects areas with persistent positive NDVI anomalies (greater than + 0.1 NDVI units) using a three-month moving window to flag regions at greatest risk. Algorithms were designed to account for periods of extended above normal NDVI (by inference rainfall) and to consider the complex life cycle of mosquitoes that maintain and transmit RVF virus to domestic animals and people. We present results for different ENSO warm- and cold-event periods. The results indicate that regions of potential outbreaks have occurred predominantly during warm ENSO events in East Africa and during cold ENSO events in southern Africa. Results provide a likely historical reconstruction of areas where RVF may have occurred during the last 19 years. There is a close agreement between confirmed outbreaks between 1981 and 2000, particularly in East Africa, and the risk maps produced in this study. This technique is adaptable to near real-time monitoring on a monthly basis and may be a useful tool in RVF disease surveillance. C1 NASA, Goddard Space Flight Ctr, Goddard Earth Sci Technol Ctr, UMBC, Greenbelt, MD 20771 USA. Walter Reed Army Inst Res, Dept Def Global Engn Infect Syst, Silver Spring, MD 20910 USA. Calif Dept Hlth Sci, Vector Borne Dis Sect, Ontario, CA 91764 USA. Global Sci & Technol, Greenbelt, MD 20770 USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. RP Anyamba, A (reprint author), NASA, Goddard Space Flight Ctr, Goddard Earth Sci Technol Ctr, UMBC, Code 923-0, Greenbelt, MD 20771 USA. NR 58 TC 47 Z9 49 U1 0 U2 16 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 USA SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD FEB PY 2002 VL 68 IS 2 BP 137 EP 145 PG 9 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA 518DB UT WOS:000173650400006 ER PT J AU Tucker, CJ Wilson, JM Mahoney, R Anyamba, A Linthicum, K Myers, MF AF Tucker, CJ Wilson, JM Mahoney, R Anyamba, A Linthicum, K Myers, MF TI Climatic and ecological context of the 1994-1996 Ebola outbreaks SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article ID HEMORRHAGIC-FEVER; SPECTRAL REFLECTANCE; COTE-DIVOIRE; VIRUS; CONGO; RADIATION; INFECTION; DISEASE; KIKWIT; SEARCH AB Ebola hemorrhagic fever outbreaks occurred in 1975-1979 and 1994-1996 within tropical Africa, It was determined from Landsat satellite data that all outbreaks occurred in tropical forest with a range of human intrusions. Meteorological satellite data, spanning the 1981 to 2000 time period, showed that marked and sudden climate changes from drier to wetter conditions were associated with the Ebola outbreaks in the 1990s. The extent of the marked climate changes suggest that Ebola outbreaks are possible over large areas of equitorial Africa, Our analysis is limited by only having one Ebola hemorrhagic fever outbreak during our period of study. C1 NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Terr Phys Lab, Greenbelt, MD 20771 USA. WHO, Ebola Tai Forest Project, Abidjan, Cote Ivoire. US Dept Def, Global Emerging Infect Syst, Walter Reed Army Inst Res, Washington, DC 20307 USA. NASA, Goddard Space Flight Ctr, Res Data Syst Corp, Greenbelt, MD 20771 USA. RP Tucker, CJ (reprint author), NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Terr Phys Lab, Code 923, Greenbelt, MD 20771 USA. EM compton@ltpmail.gsfc.nasa.gov NR 34 TC 11 Z9 12 U1 0 U2 19 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 USA SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD FEB PY 2002 VL 68 IS 2 BP 147 EP 152 PG 6 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA 518DB UT WOS:000173650400007 ER PT J AU Adrian, ML AF Adrian, ML TI The density-potential (N-e-V-S/C) relation in the high-latitude prenoon ionosphere SO PHYSICS OF PLASMAS LA English DT Article ID PLASMA; MAGNETOSPHERE; PROBE; WIND AB Sounding of the Cleft Ion Fountain Energization Region (SCIFER) Thermal Electron Capped Hemisphere Spectrometer (TECHS) data are used to study the plasma density, spacecraft potential relation (N-e-V-S/C) in the prenoon topside auroral and cleft ionosphere during a period of low solar activity. The SCIFER TECHS data show a power-law electron temperature dependence on ambient density across the transition from positive to negative spacecraft potential values in the high-latitude ionosphere. The illuminated ionospheric N-e-V-S/C relation is numerically modeled by imposing equilibrium of current flowing to/from the conductive surfaces of the payload. This modeling demonstrates a strong dependence of spacecraft potential on electron temperature across a wide range of densities. This electron temperature dependence is especially significant in the negative spacecraft potential regime. SCIFER TECHS observations of the N-e-V-S/C relation are used to extend the previous magnetospheric observation-model results to the higher density ionospheric regime. (C) 2002 American Institute of Physics. C1 NASA, George C Marshall Space Flight Ctr, Space Plasma Phys Grp SD50, Dept Space Sci, Huntsville, AL 35812 USA. RP Adrian, ML (reprint author), NASA, George C Marshall Space Flight Ctr, Space Plasma Phys Grp SD50, Dept Space Sci, Huntsville, AL 35812 USA. NR 26 TC 4 Z9 4 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 1070-664X J9 PHYS PLASMAS JI Phys. Plasmas PD FEB PY 2002 VL 9 IS 2 BP 602 EP 618 DI 10.1063/1.1415423 PG 17 WC Physics, Fluids & Plasmas SC Physics GA 514CH UT WOS:000173418700028 ER PT J AU Rao, MVVS Sharma, SP Cruden, BA Meyyappan, M AF Rao, MVVS Sharma, SP Cruden, BA Meyyappan, M TI Langmuir probe and mass spectrometric measurements in inductively coupled CF4 plasmas SO PLASMA SOURCES SCIENCE & TECHNOLOGY LA English DT Article ID LASER-INDUCED FLUORESCENCE; ENERGY DISTRIBUTION FUNCTION; HIGH-DENSITY PLASMAS; ION ENERGY; ETCHING PLASMA; ABSORPTION-SPECTROSCOPY; FLUOROCARBON PLASMAS; MOLECULAR GASES; POSITIVE-IONS; DISCHARGES AB Electron and ion energy distribution functions and other plasma parameters such as plasma potential (V-p), electron temperature (T-e) and electron and ion number densities (n(e) and n(i)) in low-pressure CF4 plasmas have been measured. The experiments were conducted in a GEC cell using an inductively coupled plasma device powered by a 13.56 MHz radiofrequency (rf) power source. The measurements were made at 300 W of input rf power at 10, 30 and 50 mTorr gas pressures. Langmuir probe measurements suggest that n(e), n(i) and V-p remain constant over 60% of the central electrode area, beyond which they decrease. Within the limits of experimental error (+/-0.25 eV), T-e remains nearly constant over the electrode area and peaks towards the electrode edge before falling rapidly. T-e and V-p increase with a decrease in pressure. n(e) and n(i) are not affected as significantly as T-e or V-p by variation in the gas pressure. The electron energy distribution function measurements indicate a highly non-Maxwellian plasma. CF3+ is the most dominant ion product of the plasma, followed by CF2+ and CF+. Significant amounts of etch products, SiFx/COFx (x=0-3), of the quartz window were also detected. The concentrations of CF2+ and CF+ are much larger than that is possible from direct electron impact ionization of the parent gas. The cross-section data suggest that the direct electron impact ionization of fragment neutrals and negative ion production by electron attachment may be responsible for increase of the minor ions. C1 NASA, Ames Res Ctr, Plasma Res Lab, ELORET Corp, Moffett Field, CA 94035 USA. RP Sharma, SP (reprint author), NASA, Ames Res Ctr, Plasma Res Lab, ELORET Corp, MS 223-3, Moffett Field, CA 94035 USA. NR 56 TC 26 Z9 26 U1 1 U2 7 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0963-0252 J9 PLASMA SOURCES SCI T JI Plasma Sources Sci. Technol. PD FEB PY 2002 VL 11 IS 1 BP 69 EP 76 AR PII S0963-0252(02)32000-0 DI 10.1088/0963-0252/11/1/309 PG 8 WC Physics, Fluids & Plasmas SC Physics GA 530BT UT WOS:000174336300009 ER PT J AU Cruden, BA Rao, MVVS Sharma, SP Meyyappan, M AF Cruden, BA Rao, MVVS Sharma, SP Meyyappan, M TI Fourier transform infrared spectroscopy of CF4 plasmas in the GEC reference cell SO PLASMA SOURCES SCIENCE & TECHNOLOGY LA English DT Article ID DIODE-LASER ABSORPTION; RF REFERENCE CELL; FLUOROCARBON PLASMAS; INDUCED FLUORESCENCE; DISCHARGES; DIAGNOSTICS; RESOLUTION; PRODUCTS; DENSITY; SPECTROMETRY AB Fourier transform infrared spectroscopy (FTIR) has been used to characterize inductively coupled CF4 plasmas in a GEC reference cell in situ. In examining these FTIR spectra., several assumptions and approximations of FTIR analysis are addressed. This includes the density dependence of cross-sections, non-linear effects in the addition of overlapping bands and the effect of spatial variations in density and temperature. This analysis demonstrates that temperatures extracted from FTIR spectra may provide a poor estimate of the true neutral plasma temperature. The FTIR spectra are dominated by unreacted CF4. accounting for 40-60% of the gas products. The amount of CF4 consumption is found to have a marked dependence on power. and is nearly independent of pressure in the range of 10-50 mTorr. Small amounts of C2F6 are observed at low power. Also observed are etching products from the quartz window-SiF4, COF2 and CO-which occur in approximately equal ratios and together account for 17-19% of the cas at 300 W and 6-9% of the gas at 100 W. The concentrations of these species are nearly independent of pressure. CFx radicals are below the detection limit of this apparatus (similar to10(13) cm(-3)). C1 NASA, Ames Res Ctr, Plasma Res Lab, ELORET Corp, Moffett Field, CA 94035 USA. RP Cruden, BA (reprint author), NASA, Ames Res Ctr, Plasma Res Lab, ELORET Corp, MS 223-3, Moffett Field, CA 94035 USA. NR 58 TC 13 Z9 13 U1 0 U2 3 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0963-0252 J9 PLASMA SOURCES SCI T JI Plasma Sources Sci. Technol. PD FEB PY 2002 VL 11 IS 1 BP 77 EP 90 AR PII S0963-0252(02)22229-X DI 10.1088/0963-0252/11/1/310 PG 14 WC Physics, Fluids & Plasmas SC Physics GA 530BT UT WOS:000174336300010 ER PT J AU Delozier, DM Orwoll, RA Cahoon, JF Johnston, NJ Smith, JG Connell, JW AF Delozier, DM Orwoll, RA Cahoon, JF Johnston, NJ Smith, JG Connell, JW TI Preparation and characterization of polyimide/organoclay nanocomposites SO POLYMER LA English DT Article DE nanocomposites; polyimide; organoclay ID POLYIMIDE-CLAY HYBRID; NYLON 6-CLAY HYBRID; SWELLING BEHAVIOR; MONTMORILLONITE; FILMS AB Organically modified montmorrillonite clay, containing a long chain aliphatic quarternary ammonium cation, was used to prepare polyimide/organoclay hybrids. Several approaches were examined in an attempt to achieve fully exfoliated nanocomposites. These included simple mixing of the clay in a pre-made high molecular weight poly(amide acid) solution; simple mixing followed by sonication of the organoclay/poly(amide acid) solutions; and the preparation of high molecular weight poly(amide acid)s in the presence of the organoclay dispersed in N-methyl-2-pyrrolidinone (NMP). The best results were obtained using the in-situ polymerization approach. The resulting nanocomposite films (both amide acid and imide), containing 3-8% by weight of organoclay, were characterized by differential scanning calorimetry (DSC), dynamic thormogravimetric analysis (TGA), transmission electron microscopy (TEM), X-ray diffraction (XRD) and thin film tensile properties. A significant degree of dispersion was observed in the nanocomposite films of the amide acid and the imide. After thermal treatment of amide acid films to effect imidization, in both air and nitrogen, the films were visually darker than control films without clay and the level of clay dispersion appeared to have decreased. In the latter case, the separation between the layers of the clay decreased to a spacing less than that present in the original organoclay. These observations suggest that thermal degradation of the aliphatic quarternary ammonium cation occurred likely during thermal treatment to effect imidization and solvent removal. These thermal degradation effects were less pronounced when thermal treatment was performed under nitrogen. The polyimide/organoclay hybrid films exhibited higher room temperature tensile moduli and lower strength and elongation to break than the control films. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Adv Mat & Proc Branch, Hampton, VA 23681 USA. Coll William & Mary, Dept Appl Sci, Williamsburg, VA 23187 USA. RP Connell, JW (reprint author), NASA, Langley Res Ctr, Adv Mat & Proc Branch, Mail Stop 226, Hampton, VA 23681 USA. NR 38 TC 144 Z9 147 U1 4 U2 29 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0032-3861 J9 POLYMER JI Polymer PD FEB PY 2002 VL 43 IS 3 BP 813 EP 822 DI 10.1016/S0032-3861(01)00640-1 PG 10 WC Polymer Science SC Polymer Science GA 500CC UT WOS:000172607500019 ER PT J AU Lathrop, WB Kaiser, MK AF Lathrop, WB Kaiser, MK TI Perceived orientation in physical and virtual environments: Changes in perceived orientation as a function of idiothetic information available SO PRESENCE-TELEOPERATORS AND VIRTUAL ENVIRONMENTS LA English DT Article ID SPATIAL KNOWLEDGE; DESK-TOP; NAVIGATION; LOCOMOTION AB Two experiments examined perceived spatial orientation in a small environment as a function of experiencing that environment under three conditions: real-world, desk-top-display (DD), and head-mounted display (HMD). Across the three conditions, participants acquired two targets located on a perimeter surrounding them, and attempted to remember the relative locations of the targets, Subsequently, participants were tested on how accurately and consistently they could point in the remembered direction of a previously seen target. Results showed that participants were significantly more consistent in the real-world and HMD conditions than in the DD condition. Further, it is shown that the advantages observed in the HMD and real-world conditions were not simply due to nonspatial response strategies. These results suggest that the additional idiothetic information afforded in the real-world and HMD conditions is useful for orientation purposes in our presented task domain. Our results are relevant to interface design issues concerning tasks that require spatial search, navigation, and visualization. C1 Univ Calif Santa Cruz, Dept Psychol, Santa Cruz, CA 95064 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Lathrop, WB (reprint author), Univ Calif Santa Cruz, Dept Psychol, 1156 High St, Santa Cruz, CA 95064 USA. NR 21 TC 21 Z9 21 U1 0 U2 0 PU M I T PRESS PI CAMBRIDGE PA FIVE CAMBRIDGE CENTER, CAMBRIDGE, MA 02142 USA SN 1054-7460 J9 PRESENCE-TELEOP VIRT JI Presence-Teleoper. Virtual Env. PD FEB PY 2002 VL 11 IS 1 BP 19 EP 32 DI 10.1162/105474602317343631 PG 14 WC Computer Science, Cybernetics; Computer Science, Software Engineering SC Computer Science GA 534BR UT WOS:000174565200002 PM 12096756 ER PT J AU Rumsey, CL Ying, SX AF Rumsey, CL Ying, SX TI Prediction of high lift: review of present CFD capability SO PROGRESS IN AEROSPACE SCIENCES LA English DT Review ID 2-EQUATION TURBULENCE MODELS; NAVIER-STOKES COMPUTATIONS; MULTIELEMENT AIRFOIL; AERODYNAMIC COMPUTATIONS; TRANSPORT AIRCRAFT; FLOWS; FLOWFIELD; EQUATIONS; CONFIGURATIONS; DESIGN AB A survey is conducted of CFD methods applied to the computation of high-lift multi-element configurations over the last 10-15 years. Both 2-D and 3-D configurations are covered. The review is organized by configuration, in an effort to glean useful insights with respect to particular successes or failings of CFD methods as a whole. In general, for both 2-D and 3-D flows, if certain guidelines regarding grid, transition, and turbulence model are followed, then surface pressures, skin friction, lift, and drag can be predicted with reasonably good accuracy at angles of attack below stall. Velocity profiles can generally be predicted in 2-D flow fields, with the exception of the slat wake, which tends to be predicted too deep by most CFD codes for a range of different configurations. CFD codes can usually predict trends due to Reynolds number in 2-D, but they are inconsistent in the prediction of trends due to configuration changes. On the whole, 2-D CFD is unreliable for predicting stall (maximum lift and the angle of attack at which it occurs); in most cases, maximum lift is overpredicted, but for some configurations the opposite occurs. However, there is some evidence that stall misprediction of nominally 2-D experiments may be caused by 3-D effects, which are obviously not modeled by 2-D CFD. In general, 3-D computations are also inconsistent with respect to computing stall, but there have been fewer of these applications to date. The paper concludes with a list of challenges that confront CFD at the start of the next decade, which should witness a dramatic increase in the number of CFD applications for 3-D high-lift configurations. Published by Elsevier Science Ltd. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Boeing Co, Long Beach, CA USA. RP Rumsey, CL (reprint author), NASA, Langley Res Ctr, Mail Stop 128, Hampton, VA 23681 USA. NR 210 TC 59 Z9 77 U1 2 U2 26 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0376-0421 J9 PROG AEROSP SCI JI Prog. Aeosp. Sci. PD FEB PY 2002 VL 38 IS 2 BP 145 EP 180 AR PII S0376-0421(02)00003-9 DI 10.1016/S0376-0421(02)00003-9 PG 36 WC Engineering, Aerospace SC Engineering GA 562VU UT WOS:000176220300002 ER PT J AU Moran, MS Hymer, DC Qi, JG Kerr, Y AF Moran, MS Hymer, DC Qi, JG Kerr, Y TI Comparison of ERS-2 SAR and Landsat TM imagery for monitoring agricultural crop and soil conditions SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID APERTURE RADAR DATA; LEAF-AREA INDEX; BARE SOIL; SCATTERING MODEL; KU-BAND; X-BANDS; C-BAND; SURFACE; CANOPY; BACKSCATTERING AB Studies over the past 25 years have shown that measurements of surface reflectance and temperature (termed optical remote sensing) are useful for monitoring crop and soil conditions. Far less attention has been given to the use of radar imagery, even though synthetic aperture radar (SAR) systems have the advantages of cloud penetration, all-weather coverage, high spatial resolution, day/night acquisitions, and signal independence of the solar illumination angle. In this study, we obtained coincident optical and SAR images of an agricultural area to investigate the use of SAR imagery for farm management. The optical and SAR data were normalized to indices ranging from 0 to 1 based on the meteorological conditions and sun/sensor geometry for each date to allow temporal analysis. Using optical images to interpret the response of SAR backscatter (sigmadegrees) to soil and plant conditions, we found that SAR sigmadegrees was sensitive to variations in field tillage, surface soil moisture, vegetation density, and plant litter. In an investigation of the relation between SAR sigmadegrees and soil surface roughness, the optical data were used for two purposes: (1) to filter the SAR images to eliminate fields with substantial vegetation cover and/or high surface soil moisture conditions, and (2) to evaluate the results of the investigation. For dry, bare soil fields, there was a significant correlation (r(2) = .67) between normalized SAR sigmadegrees and near-infrared (NIR) reflectance, due to the sensitivity of both measurements to surface roughness. Recognizing the limitations of optical remote sensing data due to cloud interference and atmospheric attenuation, the findings of this study encourage further studies of SAR imagery for crop and soil assessment. (C) 2002 Elsevier Science Inc. All rights reserved. C1 USDA ARS, SW Watershed Res Ctr, Tucson, AZ 85719 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Michigan State Univ, E Lansing, MI 48824 USA. Ctr Etud Spatiale Biosphere, CESBIO, Toulouse, France. RP Moran, MS (reprint author), USDA ARS, SW Watershed Res Ctr, 2000 E Allen Rd, Tucson, AZ 85719 USA. NR 30 TC 43 Z9 47 U1 1 U2 16 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD FEB PY 2002 VL 79 IS 2-3 BP 243 EP 252 DI 10.1016/S0034-4257(01)00276-0 PG 10 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 510WN UT WOS:000173230400009 ER PT J AU Sun, G Ranson, KJ Kharuk, VI AF Sun, G Ranson, KJ Kharuk, VI TI Radiometric slope correction for forest biomass estimation from SAR data in the Western Sayani Mountains, Siberia SO REMOTE SENSING OF ENVIRONMENT LA English DT Article DE forest biomass; terrain effect; SAR; backscatter model ID SIR-C/X-SAR; SYNTHETIC-APERTURE RADAR; CONIFEROUS FOREST; NORTHERN FOREST; BOREAL FORESTS; WATER-CONTENT; BACKSCATTER; IMAGERY; AREAS; DEPENDENCE AB We investigated the possibility of using multiple polarization (SIR-C) L-band data to map forest biomass in a mountainous area in Siberia. The use of a digital elevation model (DEM) and a model-based method for reducing terrain effects was evaluated. We found that the available DEM data were not suitable to correct the topographic effects on the SIR-C radar images. A model-based slope correction was applied to an L-band cross-polarized (hv) backscattering image and found to reduce the topographic effect. A map of aboveground biomass was produced from the corrected image. The results indicated that multipolarization L-band synthetic aperture radar (SAR) data can be useful for estimation of total aboveground biomass of forest stands in mountainous areas. (C) 2002 Elsevier Science Inc. All rights reserved. C1 Univ Maryland, Dept Geog, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sukachev Inst Forest, Krasnoyarsk, Russia. RP Sun, G (reprint author), Univ Maryland, Dept Geog, College Pk, MD 20742 USA. RI Ranson, Kenneth/G-2446-2012 OI Ranson, Kenneth/0000-0003-3806-7270 NR 28 TC 54 Z9 56 U1 0 U2 4 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD FEB PY 2002 VL 79 IS 2-3 BP 279 EP 287 DI 10.1016/S0034-4257(01)00279-6 PG 9 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 510WN UT WOS:000173230400012 ER PT J AU Drake, JB Dubayah, RO Clark, DB Knox, RG Blair, JB Hofton, MA Chazdon, RL Weishampel, JF Prince, SD AF Drake, JB Dubayah, RO Clark, DB Knox, RG Blair, JB Hofton, MA Chazdon, RL Weishampel, JF Prince, SD TI Estimation of tropical forest structural characteristics using large-footprint lidar SO REMOTE SENSING OF ENVIRONMENT LA English DT Article DE aboveground biomasss; carbon; forest structure; tropical forests; lidar remote sensing; laser altimeter; Costa Rica ID LASER SCANNER DATA; LANDSAT TM DATA; RADAR BACKSCATTER; RAIN-FOREST; LANDSCAPE-SCALE; SPATIAL HETEROGENEITY; STAND CHARACTERISTICS; CANOPY STRUCTURE; AIRBORNE LIDAR; COSTA-RICA AB Quantification of forest structure is important for developing a better understanding of how forest ecosystems function. Additionally, estimation of forest structural attributes, such as aboveground biomass (AGBM), is an important step in identifying the amount of carbon in terrestrial vegetation pools and is central to global carbon cycle studies. Although current remote sensing techniques recover such tropical forest structure poorly, new large-footprint lidar instruments show great promise. As part of a prelaunch validation plan for the Vegetation Canopy Lidar (VCL) mission, the Laser Vegetation Imaging Sensor (LVIS), a large-footprint airborne scanning lidar, was flown over the La Selva Biological Station, a tropical wet forest site in Costa Rica. The primary objective of this study was to test the ability of large-footprint lidar instruments to recover forest structural characteristics across a spectrum of land cover types from pasture to secondary and primary tropical forests. LVIS metrics were able to predict field-derived quadratic mean stem diameter (QMSD), basal area, and AGBM with R 2 values of up to .93,.72, and .93, respectively. These relationships were significant and nonasymptotic through the entire range of conditions sampled at the La Selva. Our results confirm the ability of large-footprint lidar instruments. to estimate. important structural attributes, including biomass in dense tropical forests, and when taken along with similar results from studies in temperate forests, strongly validate the VCL mission framework. (C) 2002 Elsevier Science Inc. All rights reserved. C1 Univ Maryland, Dept Geog, College Pk, MD 20742 USA. Univ Missouri, Dept Biol, St Louis, MO 63121 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Connecticut, Dept Ecol & Evolutionary Biol, Storrs, CT 06269 USA. Univ Cent Florida, Dept Biol, Orlando, FL 32816 USA. RP Drake, JB (reprint author), Univ Maryland, Dept Geog, College Pk, MD 20742 USA. EM jasdrak@geog.umd.edu RI Mitchard, Edward/C-6346-2009; Knox, Robert/E-9657-2011; Blair, James/D-3881-2013; Beckley, Matthew/D-4547-2013 NR 67 TC 298 Z9 316 U1 14 U2 110 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD FEB PY 2002 VL 79 IS 2-3 BP 305 EP 319 DI 10.1016/S0034-4257(01)00281-4 PG 15 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 510WN UT WOS:000173230400014 ER PT J AU Kimes, D Gastellu-Etchegorry, J Esteve, P AF Kimes, D Gastellu-Etchegorry, J Esteve, P TI Recovery of forest canopy characteristics through inversion of a complex 3D model SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID REFLECTANCE MODEL; NETWORKS AB Radiative transfer models for vegetation serve as a basis for extracting vegetation variables using directional/spectral data from modern-borne sensors (e.g., MODIS. MISR, POLDER, SeaWiFS). Only recently have significant efforts been made to provide operational algorithms to invert these models. These efforts have exposed a need to significantly improve the efficiency and accuracy of traditional methods for inverting these physically based models. In an effort to overcome the limitations of traditional inversion methods. a neural network method was designed and tested. In this study, a complex 3D model (Discrete Anisotropic Radiative Transfer, DART) was inverted for a wide range of simulated forest canopies using POLDER-like data. The model was inverted to recover three forest canopy variables: forest cover, leaf area index, and a soil reflectance parameter. The ranges of these variables were 0.4-1.0, 0.8-9.3, and 0.0-1.0, respectively. Two inversion methods were used - a traditional inversion technique using a modified simplex method, and a neural network method in combination with an exhaustive variable selection technique. A comparison of the methods' efficiency, accuracy, and stability was made. The neural network method gave relatively accurate solutions to the inversion problem given a small subset of directional/spectral data using only one to five view angles. Using only nadir data, the root mean squared error (RMSE) for the forest cover, leaf area index. and the soil reflectance parameter were 0.025, 0.23, and 0.15, respectively, and using the "best" view directions (2-5) were 0.021, 0.21, and 0.11, respectively. In general, the neural network method was more accurate than the simplex method. The results from both methods showed that the addition of directional view angles, as opposed to only a nadir view, can significantly improve the accuracy of recovering forest canopy characteristics. The traditional simplex method is computationally intensive and may not be appropriate for many operational applications on a per-pixel basis for regional and global data. The neural network method was computationally efficient and can be applied on a per-pixel basis. In general, the neural network technique had significantly lower RMSE values at the low noise levels. However. at moderate noise levels. the simplex method was equal to the neural network method in RMSE values. At high noise levels. the simplex method had significantly lower RMSE values than the neural network method. The neural network approach can provide an accurate, efficient, and stable inversion method for radiative transfer models using directional/spectral data from modern-borne sensors. (C) 2002 Elsevier Science Inc. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. Ctr Etudes Spatiales BIOspere, CESBIO, Toulouse, France. RP Kimes, D (reprint author), NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Code 923, Greenbelt, MD 20771 USA. NR 22 TC 34 Z9 36 U1 4 U2 15 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD FEB PY 2002 VL 79 IS 2-3 BP 320 EP 328 DI 10.1016/S0034-4257(01)00282-6 PG 9 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 510WN UT WOS:000173230400015 ER PT J AU Schein, J Qi, N Binder, R Krishnan, M Ziemer, JK Polk, JE Anders, A AF Schein, J Qi, N Binder, R Krishnan, M Ziemer, JK Polk, JE Anders, A TI Inductive energy storage driven vacuum arc thruster SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article; Proceedings Paper CT 9th International Conference on Ion Sources (ICIS) CY SEP 03-07, 2001 CL OAKLAND, CALIFORNIA SP Lawrence Berkeley Natl Lab, Axcells Technologies Inc, AccSys Technol Inc, Bergoz Instrumentat, Chabot Space & Sci Ctr, Dehnel Consulting Ltd, GMW Associates, INTMAG EGUN IGUN AB A new type of vacuum arc thruster in combination with an innovative power processing unit (PPU) has been developed that promises to be a high efficiency (similar to15%), low mass (similar to100 g) propulsion system for micro- and nanosatellites. This thruster accelerates a plasma that consists almost exclusively of ions of the cathode material and has been operated with a wide variety of cathodes. The streaming velocity of the plasma exhaust varies with cathode material, from a low of 11 km/s for Ti up to 30 km/s for Al, with a corresponding range of specific impulse from 1100 s for Ta to 3000 s for Al. Initiation of the arc requires only a few hundred volts due to an innovative "triggerless" approach in which a conductive layer between the cathode and the anode produces the initial charge carriers needed for plasma production. The initial starting voltage spike as well as the energy to operate the vacuum arc are generated by a low mass (<300 g) inductive energy storage PPU which is controlled using +5 V level signals. The thrust-to-power ratio has been estimated to reach up to &AP;20,μN/W. The vacuum arc thruster was tested at the Jet Propulsion Laboratory using W as cathode material. Experimental results are within 65% of the estimated values. (C) 2002 American Institute of Physics. C1 Alameda Appl Sci Corp, San Leandro, CA 94577 USA. NASA, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA. RP Schein, J (reprint author), Alameda Appl Sci Corp, 2235 Polvorosa Ave, San Leandro, CA 94577 USA. RI Anders, Andre/B-8580-2009 OI Anders, Andre/0000-0002-5313-6505 NR 15 TC 22 Z9 22 U1 1 U2 2 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD FEB PY 2002 VL 73 IS 2 BP 925 EP 927 DI 10.1063/1.14287884 PN 2 PG 3 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 522WY UT WOS:000173921000131 ER PT J AU Brophy, JR AF Brophy, JR TI NASA's Deep Space 1 ion engine (plenary) SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article; Proceedings Paper CT 9th International Conference on Ion Sources (ICIS) CY SEP 03-07, 2001 CL OAKLAND, CALIFORNIA SP Lawrence Berkeley Natl Lab, Axcells Technologies Inc, AccSys Technol Inc, Bergoz Instrumentat, Chabot Space & Sci Ctr, Dehnel Consulting Ltd, GMW Associates, INTMAG EGUN IGUN AB Ion propulsion is now a legitimate propulsion option for future deep space missions. The long journey required to get from the first laboratory test of an ion engine in 1960 to the first successful flight of an ion propulsion system on NASA's Deep Space 1 mission in 1998 is briefly summarized herein. An overview of the operation of the Deep Space 1 ion engine is provided along with a description of the complete ion propulsion system on the spacecraft. Engine performance measured in space compares well with that based on ground test data. Future deep space missions desire improved engine performance in the form of longer engine life (greater total impulse) and greater specific impulse. Derivatives of the NSTAR ion engine are being evaluated to assess their capability to meet these future needs. (C) 2002 American Institute of Physics. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Brophy, JR (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 44 TC 21 Z9 21 U1 2 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 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD FEB PY 2002 VL 73 IS 2 BP 1071 EP 1078 DI 10.1063/1.1432470 PN 2 PG 8 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 522WY UT WOS:000173921000176 ER PT J AU Johnson, L AF Johnson, L TI Propulsion technologies for exploration of the solar system and beyond (plenary) SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article; Proceedings Paper CT 9th International Conference on Ion Sources (ICIS) CY SEP 03-07, 2001 CL OAKLAND, CALIFORNIA SP Lawrence Berkeley Natl Lab, Axcells Technologies Inc, AccSys Technol Inc, Bergoz Instrumentat, Chabot Space & Sci Ctr, Dehnel Consulting Ltd, GMW Associates, INTMAG EGUN IGUN AB NASA's Advanced Space Transportation Program (ASTP) is investing in technologies to achieve a factor of 10 reduction in the cost of Earth orbital transportation and a factor of 2 reduction in propulsion system mass and travel time for planetary missions within the next 15 years. Since more than 70% of projected launches over the next 10 years will require propulsion systems capable of attaining destinations beyond low-Earth orbit, investment in in-space technologies will benefit a large percentage of future missions. The ASTP technology portfolio includes many advanced propulsion systems. From the next-generation ion propulsion system operating in the 5-10 kW range to fission-powered multikilowatt systems, substantial advances in spacecraft propulsion performance are anticipated. Some of the most promising technologies for achieving these goals use the environment of space itself for energy and propulsion and are generically called "propellantless," because they do not require onboard fuel to achieve thrust. An overview of state-of-the-art space propulsion technologies, such as solar and plasma sails, electrodynamic and momentum transfer tethers, and aeroassist and aerocapture, are described. Results of recent Earth-based technology demonstrations and space tests for many of these new propulsion technologies are discussed. C1 NASA, George C Marshall Space Flight Ctr, Adv Space Transportat Program TD 15, Huntsville, AL 35812 USA. RP Johnson, L (reprint author), NASA, George C Marshall Space Flight Ctr, Adv Space Transportat Program TD 15, Huntsville, AL 35812 USA. NR 9 TC 3 Z9 3 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 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD FEB PY 2002 VL 73 IS 2 BP 1079 EP 1082 DI 10.1063/1.1431426 PN 2 PG 4 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 522WY UT WOS:000173921000177 ER PT J AU Chen, JY Carlson, BE Del Genio, AD AF Chen, JY Carlson, BE Del Genio, AD TI Evidence for strengthening of the tropical general circulation in the 1990s SO SCIENCE LA English DT Article ID CLOUDS AB Satellite observations suggest that the thermal radiation emitted by Earth to space increased by more than 5 watts per square meter, while reflected sunlight decreased by less than 2 watts per square meter, in the tropics over the period 1985-2000, with most of the increase occurring after 1990. By analyzing temporal changes in the frequency of occurrence of emitted thermal and reflected solar fluxes, the effects of El Nino-Southern Oscillation are minimized, and an independent longer-time-scale variation of the radiation budget is identified. Similar analyses of upper tropospheric humidity, cloud amount, surface air temperature, and vertical velocity confirm that these flux changes are associated with a decadal-time-scale strengthening of the tropical Hadley and Walker circulations. Equatorial convective regions have intensified in upward motion and moistened, while both the equatorial and subtropical subsidence regions have become drier and less cloudy. C1 Columbia Univ, Dept Earth & Environm Sci, Palisades, NY 10964 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Chen, JY (reprint author), Columbia Univ, Dept Earth & Environm Sci, Palisades, NY 10964 USA. RI Chen, Junye/G-4301-2011; Del Genio, Anthony/D-4663-2012; Carlson, Barbara/D-8319-2012 OI Del Genio, Anthony/0000-0001-7450-1359; NR 15 TC 176 Z9 185 U1 0 U2 16 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 FEB 1 PY 2002 VL 295 IS 5556 BP 838 EP 841 DI 10.1126/science.1065835 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 519NU UT WOS:000173733000040 PM 11823637 ER PT J AU Wielicki, BA Wong, TM Allan, RP Slingo, A Kiehl, JT Soden, BJ Gordon, CT Miller, AJ Yang, SK Randall, DA Robertson, F Susskind, J Jacobowitz, H AF Wielicki, BA Wong, TM Allan, RP Slingo, A Kiehl, JT Soden, BJ Gordon, CT Miller, AJ Yang, SK Randall, DA Robertson, F Susskind, J Jacobowitz, H TI Evidence for large decadal variability in the tropical mean radiative energy budget SO SCIENCE LA English DT Article ID CLIMATE-MODEL; SYSTEM CERES; CLOUDS; EARTH AB It is widely assumed that variations in Earth's radiative energy budget at large time and space scales are small. We present new evidence from a compilation of over two decades of accurate satellite data that the top-of-atmosphere (TOA) tropical radiative energy budget is much more dynamic and variable than previously thought. Results indicate that the radiation budget changes are caused by changes in tropical mean cloudiness. The results of several current climate model simulations fail to predict this large observed variation in tropical energy budget. The missing variability in the models highlights the critical need to improve cloud modeling in the tropics so that prediction of tropical climate on interannual and decadal time scales can be improved. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Hadley Ctr, Met Off, Bracknell RG12 2SY, Berks, England. Natl Ctr Atmospher Res, Boulder, CO 80303 USA. Princeton Univ, NOAA, GFDL, Princeton, NJ 08542 USA. NCEP, NOAA, Climate Predict Ctr, Camp Springs, MD 20746 USA. Colorado State Univ, Ft Collins, CO 80523 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NOAA, NESDIS, Camp Springs, MD 20746 USA. RP Wielicki, BA (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. RI Allan, Richard/B-5782-2008; Randall, David/E-6113-2011 OI Allan, Richard/0000-0003-0264-9447; Randall, David/0000-0001-6935-4112 NR 17 TC 253 Z9 264 U1 1 U2 22 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 FEB 1 PY 2002 VL 295 IS 5556 BP 841 EP 844 DI 10.1126/science.1065837 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 519NU UT WOS:000173733000041 PM 11823638 ER PT J AU Harris, H Benford, G AF Harris, H Benford, G TI Life in galactic suburbia SO SCIENTIFIC AMERICAN LA English DT Letter C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Univ Calif Irvine, Dept Phys & Astron, Irvine, CA USA. RP Harris, H (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SCI AMERICAN INC PI NEW YORK PA 415 MADISON AVE, NEW YORK, NY 10017 USA SN 0036-8733 J9 SCI AM JI Sci.Am. PD FEB PY 2002 VL 286 IS 2 BP 12 EP 12 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 513BH UT WOS:000173357700002 ER PT J AU Fouke, BW Zerkle, AL Alvarez, W Pope, KO Ocampo, AC Wachtman, RJ Nishimura, JMG Claeys, P Fischer, AG AF Fouke, BW Zerkle, AL Alvarez, W Pope, KO Ocampo, AC Wachtman, RJ Nishimura, JMG Claeys, P Fischer, AG TI Cathodoluminescence petrography and isotope geochemistry of KT impact ejecta deposited 360 km from the Chicxulub crater, at Albion Island, Belize SO SEDIMENTOLOGY LA English DT Article DE carbonates; cathodoluminescence; Chicxulub; Cretaceous-Tertiary (KT) boundary event; ejecta; isotopes ID CRETACEOUS-TERTIARY BOUNDARY; ACCRETIONARY LAPILLI; YUCATAN PENINSULA; ASTEROID IMPACT; MELT ROCK; MEXICO; STRATIGRAPHY; CONSTRAINTS; SR-87/SR-86; GLASS AB The depositional and diagenetic history of Cretaceous-Tertiary (KT) impact ejecta deposited 360 km from the Chicxulub crater, at Albion Island, Belize, has been investigated using integrated cathodoluminescence and isotopic analyses. A quarry exposes 26 m of Upper Cretaceous Barton Greek Formation dolomitized marine limestone overlain by 16 m of dolomitized Albion Formation impact ejecta. The Albion Formation consists of a lower fine-grained approximate to1-m-thick spheroid bed and an upper 15-m-thick coarse conglomeratic diamictite bed. A 14-event paragenetic sequence has been documented and used as a temporal framework to interpret chemostratigraphic trends in bulk rock delta(18)O, delta(13)C and Sr-87/Sr-86. The uppermost surface of the Barton Creek Formation was subaerially exposed before the KT impact, as indicated by a brecciated palaeosol that caps upsection decreases in delta(13)C and delta(18)O. Small 1-cm-diameter spheroids in the spheroid bed exhibit vermicular crystalline textures but lack the concentric zonations common to accretionary lapilli. These spheroids are hypothesized originally to have been impact glass or reactive Ca and Mg oxide dusts that adhered to water vapour particles condensing from the cooling impact vapour cloud. The spheroids were dolomitized soon after deposition. The earliest dolomitization in the matrix sediments of the Albion Formation was also post-depositional, replacing clays formed by devitrification of impact glass. Dolomite and clay Sr-87/Sr-86 exhibit a distinct symmetrical distribution in the spheroid bed ranging from 0.707745 to 0.707872. Although unproven, this may represent primary changes in the chemical composition of the impact glass. The limestone clasts in the diamictite bed were dolomitized before the KT impact and exhibit upsection decreases in bulk rock Sr-87/Sr-86. This suggests that the clasts were excavated from strata equivalent in age or older than the Barton Creek Formation at locations closer to, or in, the Chicxulub crater. C1 Univ Illinois, Dept Geol, Urbana, IL 61801 USA. Univ Calif Berkeley, Dept Geol & Geophys, Berkeley, CA 94720 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA Headquarters, Washington, DC 20546 USA. Inst Mexicano Petr, Mexico City 07730, DF, Mexico. Free Univ Brussels, Dept Geol, B-1050 Brussels, Belgium. Univ So Calif, Dept Earth Sci, Los Angeles, CA 90089 USA. RP Fouke, BW (reprint author), Univ Illinois, Dept Geol, 245 Nat Hist Bldg,1301 W Green St, Urbana, IL 61801 USA. RI Claeys, Philippe/B-4895-2008; OI Claeys, Philippe/0000-0002-4585-7687; Zerkle, Aubrey/0000-0003-2324-1619 NR 65 TC 24 Z9 24 U1 0 U2 6 PU BLACKWELL PUBLISHING LTD PI OXFORD PA 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND SN 0037-0746 J9 SEDIMENTOLOGY JI Sedimentology PD FEB PY 2002 VL 49 IS 1 BP 117 EP 138 DI 10.1046/j.1365-3091.2002.00435.x PG 22 WC Geology SC Geology GA 532GA UT WOS:000174464900008 ER PT J AU Keenan, FP Mathioudakis, M Katsiyannis, AC Ramsbottom, CA Bell, KL Thomas, RJ Brosius, JW AF Keenan, FP Mathioudakis, M Katsiyannis, AC Ramsbottom, CA Bell, KL Thomas, RJ Brosius, JW TI A comparison of theoretical MgVI emission line strengths with active-region observations from serts SO SOLAR PHYSICS LA English DT Article ID EUV-ROCKET-TELESCOPE; SPECTROGRAPH SERTS; ATOMIC DATABASE; SPECTRA; DIAGNOSTICS; CHIANTI; SUN; XII; VI; NI AB R-matrix calculations of electron impact excitation rates in N-like Mg vi are used to derive theoretical electron-density-sensitive emission line ratios involving 2s(2)2p(3)-2s2p(4) transitions in the 269-403 Angstrom wavelength range. A comparison of these with observations of a solar active region, obtained during the 1989 flight of the Solar EUV Rocket Telescope and Spectrograph (SERTS), reveals good agreement between theory and observation for the 2s(2)2p(3) S-4-2s2p(4) P-4 transitions at 399.28, 400.67, and 403.30 Angstrom, and the 2s(2)2p(3) P-2-2s2p(4) D-2 lines at 387.77 and 387.97 Angstrom. However, intensities for the other lines attributed to Mg vi in this spectrum by various authors do not match the present theoretical predictions. We argue that these discrepancies are not due to errors in the adopted atomic data, as previously suggested, but rather to observational uncertainties or mis-identifications. Some of the features previously identified as Mg vi lines in the SERTS spectrum, such as 291.36 and 293.15 Angstrom, are judged to be noise, while others (including 349.16 Angstrom) appear to be blended. C1 Queens Univ Belfast, Dept Pure & Appl Phys, Belfast BT7 1NN, Antrim, North Ireland. Queens Univ Belfast, Dept Appl Math & Theoret Phys, Belfast BT7 1NN, Antrim, North Ireland. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Raytheon ITSS, Lanham, MD 20706 USA. RP Keenan, FP (reprint author), Queens Univ Belfast, Dept Pure & Appl Phys, Belfast BT7 1NN, Antrim, North Ireland. RI Katsiyannis, Thanassis/L-8496-2013 NR 29 TC 4 Z9 4 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD FEB PY 2002 VL 205 IS 2 BP 265 EP 277 DI 10.1023/A:1014282830043 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 524BZ UT WOS:000173993200004 ER PT J AU Klimeck, G Oyafuso, F Bowen, RC Boykin, TB Cwik, TA Huang, E Vinyard, ES AF Klimeck, G Oyafuso, F Bowen, RC Boykin, TB Cwik, TA Huang, E Vinyard, ES TI 3-D atomistic nanoelectronic modeling on high performance clusters: multimillion atom simulations SO SUPERLATTICES AND MICROSTRUCTURES LA English DT Article DE quantum dot; nanoelectronics; sparse matrix-vector multiplication ID DOT INFRARED PHOTODETECTORS; SEMICONDUCTOR QUANTUM DOTS; TIGHT-BINDING PARAMETERS; ELECTRONIC-STRUCTURE AB Electronic device scaling is ultimately limited by atomic dimensions. The simulation of electronic structure and electron transport on these length scales must be fundamentally quantum mechanical. This leads to computational models that account for fundamental physical interactions using an atomistic basis and tax even the largest available supercomputer when simulating measurable devices. The prototype development of a software tool that enables this class of simulation is presented. Realistically sized structures contain one million to tens of millions of atoms that need to be represented with an appropriate basis. The resulting sparse complex Hamiltonian matrix is of the order to tens of millions. A custom matrix-vector multiplication algorithm that is coupled to a Lanczos and/or Rayleigh-Ritz eigenvalue solver has been developed and ported to a Beowulf cluster as well as an Origin 2000. First benchmarking results of these algorithms as well as the first results of quantum dot simulations are reported. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Alabama, Huntsville, AL 35899 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 169-315, Pasadena, CA 91109 USA. EM gekco@ieee.org RI Klimeck, Gerhard/A-1414-2012 OI Klimeck, Gerhard/0000-0001-7128-773X NR 21 TC 6 Z9 6 U1 0 U2 1 PU ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0749-6036 J9 SUPERLATTICE MICROST JI Superlattices Microstruct. PD FEB-APR PY 2002 VL 31 IS 2-4 BP 171 EP 179 DI 10.1006/spmi.2002.1038 PG 9 WC Physics, Condensed Matter SC Physics GA 593QD UT WOS:000178002900011 ER PT J AU Gautsch, S Akiyama, T Imer, R de Rooij, NF Staufer, U Niedermann, P Howald, L Brandlin, D Tonin, A Hidber, HR Pike, WT AF Gautsch, S Akiyama, T Imer, R de Rooij, NF Staufer, U Niedermann, P Howald, L Brandlin, D Tonin, A Hidber, HR Pike, WT TI Measurement of quartz particles by means of an atomic force microscope for planetary exploration SO SURFACE AND INTERFACE ANALYSIS LA English DT Article; Proceedings Paper CT SXM 4 Conference CY 2000 CL MUNSTER, GERMANY DE AFM; Mars; particles; quartz AB Within the last 2 years our consortium has developed, built and tested an atomic force microscope for planetary science applications, in particular for the study of Martian dust and soil. An array of eight cantilevers and tips provides redundancy in case of tip or cantilever failure. Images can be recorded in both static and dynamic operation modes. As we plan to investigate Martian dust, our interest focuses on the behaviour of the instrument when measuring loose particles in the above-mentioned modes. During scanning, tip contamination with a particle occurs quite frequently, altering the quality of the images. Before changing the cantilever, reverse-imaging the contaminated tip on a tip calibration sample will be performed in order to increase the scientific throughput. We present the results of our test measurements on respirable alpha-quartz. Copyright (C) 2002 John Wiley Sons, Ltd. C1 Univ Neuchatel, Inst Microtechnol, CH-2007 Neuchatel, Switzerland. CSEM, CH-2007 Neuchatel, Switzerland. Nanosurf AG, CH-4410 Liestal, Switzerland. Univ Basel, Inst Phys, CH-4056 Basel, Switzerland. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gautsch, S (reprint author), Univ Neuchatel, Inst Microtechnol, Jaquet Droz 1, CH-2007 Neuchatel, Switzerland. RI Gautsch, Sebastian/G-2561-2015; Staufer, Urs/J-6866-2016 OI Staufer, Urs/0000-0002-3519-6467 NR 3 TC 6 Z9 6 U1 0 U2 2 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0142-2421 J9 SURF INTERFACE ANAL JI Surf. Interface Anal. PD FEB PY 2002 VL 33 IS 2 BP 163 EP 167 DI 10.1002/sia.1182 PG 5 WC Chemistry, Physical SC Chemistry GA 523UK UT WOS:000173974600024 ER PT J AU Banger, KK Harris, JD Cowen, JE Hepp, AF AF Banger, KK Harris, JD Cowen, JE Hepp, AF TI Facile modulation of single source precursors: the synthesis and characterization of single source precursors for deposition of ternary chalcopyrite materials SO THIN SOLID FILMS LA English DT Article; Proceedings Paper CT E-MRS 2001 Spring Meeting CY JUN 05-08, 2001 CL STRASBOURG, FRANCE DE chemical vapor deposition; chalcopyrite; thin film technology; solar cells ID FILMS; CVD; SE AB In this paper, the syntheses and thermal modulation of ternary single source precursors, based on the [{ER3}(2)Cu(YR')(2)In(YR')(2)] architecture in good yields are described (E=P. As, Sb: Y=S, Se, and R=alkyl, aryl). Most importantly. we have successfully prepared the first liquid CuInS2 (CIS) single source precursors, (when R = B u, Y = S, and R'= Et, or Pr). These new compounds were utilized for spray chemical vapor deposition (CVD) of copper indium disulfide, an absorber layer for the fabrication of thin-film solar cells. Thermogravimetric analyses (TGA) and Differential Scanning Calorionnetry (DSC) demonstrate that controlled manipulation of the steric and electronic properties of either the group five donor and/or chalcogenide moiety permits directed adjustment of the thermal stability and physical properties of the precursor. Preliminary studies show that these derivatives produce CuInS2 thin-films at low temperature. X-Ray diffraction studies, EDS and SEM confirmed the formation of the single-phase CuInS2 thin-films. (C) 2002 Elsevier Science B.V. All rights reserved. C1 NASA, Glenn Res Ctr, Thin Film Technol Grp, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Cleveland, OH 44142 USA. Cleveland State Univ, Dept Chem, Cleveland, OH 44135 USA. RP Hepp, AF (reprint author), NASA, Glenn Res Ctr, Thin Film Technol Grp, 21000 Brookpk Rd,Mail Stop 302-1, Cleveland, OH 44135 USA. NR 12 TC 23 Z9 23 U1 0 U2 6 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0040-6090 J9 THIN SOLID FILMS JI Thin Solid Films PD FEB 1 PY 2002 VL 403 BP 390 EP 395 AR PII S0040-6090(01)01517-6 DI 10.1016/S0040-6090(01)01517-6 PG 6 WC Materials Science, Multidisciplinary; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA 525DQ UT WOS:000174053800076 ER PT J AU Imam, MA Chu, HP Rath, BB AF Imam, MA Chu, HP Rath, BB TI Fatigue properties of titanium alloy Ti-6Al-2Cb-1Ta-0.8Mo SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article DE titanium alloys; cycle; fatigue properties AB The low cycle fatigue properties of a Ti-6Al-2Cb-1Ta:-0.8Mo (Ti-6211) alloy have been studied by testing hourglass specimens, based on ASTM specification 606-92, under cyclic stresses in strain-controlled conditions. Results indicate that strain softening occurs under cyclic loading and that fatigue life can be related to either strain range or stress range. Both low cycle and high cycle fatigue data on Ti-6211 have been reviewed. A complete fatigue curve has been established which predicts fatigue life of the alloy for R = - 1 from 100 to 100 million cycles. Published by Elsevier Science B.V. C1 USN, Res Lab, Mat Sci & Component Technol Directorate, Dept Navy, Washington, DC 20375 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Imam, MA (reprint author), USN, Res Lab, Mat Sci & Component Technol Directorate, Dept Navy, Code 6320,4555 Overlook Ave SW, Washington, DC 20375 USA. NR 21 TC 5 Z9 9 U1 0 U2 3 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD JAN 31 PY 2002 VL 323 IS 1-2 BP 457 EP 461 DI 10.1016/S0921-5093(01)01473-3 PG 5 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 516WM UT WOS:000173579800058 ER PT J AU Doran, PT Priscu, JC Lyons, WB Walsh, JE Fountain, AG McKnight, DM Moorhead, DL Virginia, RA Wall, DH Clow, GD Fritsen, CH McKay, CP Parsons, AN AF Doran, PT Priscu, JC Lyons, WB Walsh, JE Fountain, AG McKnight, DM Moorhead, DL Virginia, RA Wall, DH Clow, GD Fritsen, CH McKay, CP Parsons, AN TI Antarctic climate cooling and terrestrial ecosystem response SO NATURE LA English DT Article ID TAYLOR-VALLEY; DRY VALLEYS; COMMUNITIES; TEMPERATURE AB The average air temperature at the Earth's surface has increased by 0.06degreesC per decade during the 20th century(1), and by 0.19degreesC per decade from 1979 to 1998(2). Climate models generally predict amplified warming in polar regions(3,4), as observed in Antarctica's peninsula region over the second half of the 20th century(5-9). Although previous reports suggest slight recent continental warming(9,10), our spatial analysis of Antarctic meteorological data demonstrates a net cooling on the Antarctic continent between 1966 and 2000, particularly during summer and autumn. The McMurdo Dry Valleys have cooled by 0.7degreesC per decade between 1986 and 2000, with similar pronounced seasonal trends. Summer cooling is particularly important to Antarctic terrestrial ecosystems that are poised at the interface of ice and water. Here we present data from the dry valleys representing evidence of rapid terrestrial ecosystem response to climate cooling in Antarctica, including decreased primary productivity of lakes (6-9% per year) and declining numbers of soil invertebrates (more than 10% per year). Continental Antarctic cooling, especially the seasonality of cooling, poses challenges to models of climate and ecosystem change. C1 Univ Illinois, Dept Earth & Environm Sci, Chicago, IL 60607 USA. Montana State Univ, Bozeman, MT 59717 USA. Ohio State Univ, Byrd Polar Res Ctr, Columbus, OH 43210 USA. Univ Illinois, Dept Atmospher Sci, Urbana, IL 61801 USA. Univ Colorado, Inst Arctic & Alpine Res, Boulder, CO 80309 USA. Portland State Univ, Dept Geol, Portland, OR 97207 USA. Univ Toledo, Dept Earth Ecol & Environm Sci, Toledo, OH 43606 USA. Dartmouth Coll, Environm Studies Program, Hanover, NH 03755 USA. Colorado State Univ, Nat Resource Ecol Lab, Ft Collins, CO 80523 USA. US Geol Survey, Climate Program, Denver, CO 80225 USA. Desert Res Inst, Div Earth & Ecosyst Sci, Reno, NV 89512 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Doran, PT (reprint author), Univ Illinois, Dept Earth & Environm Sci, 845 W Taylor St, Chicago, IL 60607 USA. RI Wall, Diana/F-5491-2011; OI MCKNIGHT, DIANE/0000-0002-4171-1533 NR 29 TC 278 Z9 286 U1 7 U2 76 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JAN 31 PY 2002 VL 415 IS 6871 BP 517 EP 520 DI 10.1038/nature710 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 516PQ UT WOS:000173564300044 PM 11793010 ER PT J AU de Oliveira, HP AF de Oliveira, HP TI Density perturbations in warm inflation and COBE normalization SO PHYSICS LETTERS B LA English DT Article ID COSMOLOGICAL PERTURBATIONS; MODELS; STAGE; WAVES AB Starting from a gauge invariant treatment of perturbations an analytical expression for the spectrum of long wavelength density perturbations in warm inflation is derived. The adiabatic and entropy modes are exhibited explicitly. As an application of the analytical results, we determined the observational constraint for the dissipation term compatible with COBE observation of the cosmic microwave radiation anisotropy for some specific models. In view of the results the feasibility of warm inflation is discussed. (C) 2002 Published by Elsevier Science B.V. C1 NASA, Fermi Natl Accelerator Lab, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Estado Rio de Janeiro, Inst Fis, Dept Fis Teor, BR-20550013 Rio De Janeiro, RJ, Brazil. RP de Oliveira, HP (reprint author), NASA, Fermi Natl Accelerator Lab, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. NR 25 TC 23 Z9 23 U1 0 U2 3 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 JAN 31 PY 2002 VL 526 IS 1-2 BP 1 EP 8 DI 10.1016/S0370-2693(01)01496-4 PG 8 WC Astronomy & Astrophysics; Physics, Nuclear; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 518CP UT WOS:000173649300001 ER PT J AU McKenzie, D Barnett, DN Yuan, DN AF McKenzie, D Barnett, DN Yuan, DN TI The relationship between Martian gravity and topography SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Article DE Mars; elastic properties; convection; lithosphere; melts ID CONTINENTAL LITHOSPHERE; ELASTIC THICKNESS; THERMAL EVOLUTION; MARS; VENUS; TECTONICS; VOLCANISM; ANOMALIES; SUPPORT AB The relationship between gravity and topography of various regions of Mars is used to estimate their effective elastic thicknesses T-e using direct measurements of line of sight velocity, rather than spherical harmonic coefficients. Estimates of T-e vary from 70 km for Tharsis, 29 km for Elysium, to 14.5 km for the southern hemisphere, and show that the thickness of the Martian lithosphere increases with age as the radioactive isotopes of K, Th, and U decay. A simple parameterised model of the convective thermal history is used to estimate the temperature structure of the lithosphere, and shows that the base of the elastic layer has a temperature of 300 +/- 50degreesC, or similar to the value for terrestrial continents. In both cases the rheology is probably affected by the presence of water. The short wavelength behaviour of the gravity field allows the density of the rocks that form the topography to be estimated, and gives values of about 3.0 Mg/m(3) for Tharsis and Elysium. This value is substantially greater than that of 2.7 Mg/m(3) obtained for Earth, and is in agreement with estimates from SNC (Shergottites-Nahklites-Chassigny) meteorites of 3.3 Mg/m(3). The density of the topography of Valles Marineris is only 2.35 Mg/m(3), and suggests that ice may be present below the surface. In the heavily bombarded southern hemisphere, isostatic compensation occurs at wavelengths as short as 700 kin, which requires the effective compensation depth to be no more than 10 km. The gravity field with wavelengths greater than 1500 km may be supported dynamically, by a plume rising beneath the Tharsis region. The difference in temperature between the solidus and the present areotherm is less than 250degreesC, so melt generation can occur in rising plumes. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Univ Cambridge, Dept Earth Sci, Bullard Labs, Inst Theoret Geophys, Cambridge CB3 0EZ, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Univ Cambridge, Dept Earth Sci, Bullard Labs, Inst Theoret Geophys, Madingley Rd, Cambridge CB3 0EZ, England. EM mckenzie@esc.cam.ac.uk NR 30 TC 66 Z9 72 U1 0 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-821X EI 1385-013X J9 EARTH PLANET SC LETT JI Earth Planet. Sci. Lett. PD JAN 30 PY 2002 VL 195 IS 1-2 BP 1 EP 16 AR PII S0012-821X(01)00555-6 DI 10.1016/S0012-821X(01)00555-6 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 522MA UT WOS:000173900100001 ER PT J AU Johnson, CM Skulan, JL Beard, BL Sun, H Nealson, KH Braterman, PS AF Johnson, CM Skulan, JL Beard, BL Sun, H Nealson, KH Braterman, PS TI Isotopic fractionation between Fe(III) and Fe(II) in aqueous solutions SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Article DE ferric iron; ferrous iron; stable isotopes; oxidation; reduction; fractionation ID RAY-ABSORPTION-SPECTROSCOPY; FERRIC-CHLORIDE; IRON ISOTOPES; COMPLEXES; SOLUBILITY; 200-DEGREES-C; PRECIPITATION; EQUILIBRIUM; MAGNETITE; REDUCTION AB Large equilibrium isotope fractionation occurs between Fe(III) and Fe(II) in very dilute (less than or equal to 22 mM Cl-) aqueous solutions, reflecting significant differences in bonding environments. Separation of Fe(III) and Fe(II) is attained by rapid and complete precipitation of Fe(III) through carbonate addition, followed by separation of supernatant and ferric precipitate: experiments reported here produce an equilibrium Delta(Fe(III)-Fe(II)) = 2.75 +/- 0.15% for Fe-56/Fe-54 at room temperature (22 +/- 2degreesC). The timescales required for attainment of isotopic equilibrium have been determined by parallel isotope tracer experiments using Fe-57-enriched iron, which are best fitted by a second-order rate law, with K = 0. 18 +/- 0.03 s(-1). Based on this rate constant, similar to 15-20% isotopic exchange is estimated to have occurred during Fe(III)-Fe(II) separation, which contributes <0.10%v uncertainty to the equilibrium Delta(Fe(III)-Fe(II)). Under the experimental conditions used in this study, >97% Fe(II) exists as [Fe-II(H2O)(6)](2+), and >82% Fe(III) exists as [Fe-III(H2O)(6)](3+) and [Fe-III(H2O)(6-n)(OH)(n)](3-n); assuming these are the dominant species, the measured Fe isotope fractionation is approximately half that predicted by Schauble et al. [Geochim. Cosmochim. Acta 65 (2001) 2487-2497] at 20-25degreesC. Although this discrepancy may be due in part to the experimentally unknown isotopic effects of chloride interacting with Fe-hexaquo or Fe-hydroxide complexes, or directly bonded to Fe, there still appears to be at this stage a > 1% difference between prediction and experiment. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Univ Wisconsin, Dept Geol & Geophys, Madison, WI 53706 USA. Jet Prop Lab, Pasadena, CA 91109 USA. Univ N Texas, Dept Chem, Denton, TX 76203 USA. RP Johnson, CM (reprint author), Univ Wisconsin, Dept Geol & Geophys, 1215 W Dayton St, Madison, WI 53706 USA. NR 48 TC 175 Z9 193 U1 3 U2 61 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-821X J9 EARTH PLANET SC LETT JI Earth Planet. Sci. Lett. PD JAN 30 PY 2002 VL 195 IS 1-2 BP 141 EP 153 AR PII S0012-821X(01)00581-7 DI 10.1016/S0012-821X(01)00581-7 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 522MA UT WOS:000173900100011 ER PT J AU O'Keeffe, J Wei, CY Cho, KJ AF O'Keeffe, J Wei, CY Cho, KJ TI Bandstructure modulation for carbon nanotubes in a uniform electric field SO APPLIED PHYSICS LETTERS LA English DT Article ID SINGLE-WALL; GAP AB A method to electronically modulate the energy gap and bandstructure of semiconducting carbon nanotubes is proposed. We investigate this bandstructure modulation mechanism using tight-binding and density functional theory (DFT). Results show that the energy gap of a semiconducting nanotube can be narrowed, when the tube is placed in an electric field perpendicular to the tube axis. In contrast, Metallic tubes were found to exhibit a screening behavior, whereby free charge redistributes about the tube circumference as a result of the external field. In this case, the bandstructure shows little perturbation in response to an applied electric field. (C) 2002 American Institute of Physics. C1 NASA, Ames Res Ctr, Moffett Field, CA 94305 USA. Stanford Univ, Dept Mech Engn, Stanford, CA 94305 USA. RP O'Keeffe, J (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94305 USA. NR 12 TC 96 Z9 96 U1 2 U2 16 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JAN 28 PY 2002 VL 80 IS 4 BP 676 EP 678 DI 10.1063/1.1432441 PG 3 WC Physics, Applied SC Physics GA 515RE UT WOS:000173508900048 ER PT J AU Bisset, DK Hunt, JCR Rogers, MM AF Bisset, DK Hunt, JCR Rogers, MM TI The turbulent/non-turbulent interface bounding a far wake SO JOURNAL OF FLUID MECHANICS LA English DT Article ID LARGE-SCALE MOTION; BOUNDARY-LAYER; FLOW-VISUALIZATION; ORGANIZED MOTION; REGION; FLUCTUATIONS; CYLINDER AB The velocity fields of a turbulent wake behind a flat plate obtained from the direct numerical simulations of Moser et al. (1998) are used to study the structure of the flow in the intermittent zone where there are, alternately, regions of fully turbulent flow and non-turbulent velocity fluctuations on either side of a thin randomly moving interface. Comparisons are made with a wake that is 'forced' by amplifying initial velocity fluctuations. A temperature field T, with constant values of 1.0 and 0 above and below the wake, is transported across the wake as a passive scalar. The value of the Reynolds number based on the centreplane mean velocity defect and half-width b of the wake is Re approximate to 2000. The thickness of the continuous interface is about 0.07b, whereas the amplitude of fluctuations of the instantaneous interface displacement y(I)(t) is an order of magnitude larger, being about 0.5b. This explains why the mean statistics of vorticity in the intermittent zone can be calculated in terms of the probability distribution of y(I) and the instantaneous discontinuity in vorticity across the interface. When plotted as functions of y - y(I), the conditional mean velocity U) and temperature T profiles show sharp jumps at the interface adjacent to a thick zone where (U and T vary much more slowly. Statistics for the conditional vorticity and velocity variances, available in such detail only from DNS data, show how streamwise and spanwise components of vorticity are generated by vortex stretching in the bulges of the interface. While mean Reynolds stresses (in the fixed reference frame) decrease gradually in the intermittent zone, conditional stresses are roughly constant and then decrease sharply towards zero at the interface. Flow fields around the interface, analysed in terms of the local streamline pattern, confirm and explain previous results that the advancement of the vortical interface into the irrotational flow is driven by large-scale eddy motion. Terms used in one-point turbulence models are evaluated both conventionally and conditionally in the interface region, and the current practice in statistical models of approximating entrainment by a diffusion process is assessed. C1 Stanford Univ, Ctr Turbulence Res, Stanford, CA 94305 USA. UCL, Dept Space & Climate Phys, London WC1E 6BT, England. UCL, Dept Geol Sci, London WC1E 6BT, England. Tech Univ Delft, JM Burgers Ctr, Delft, Netherlands. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Bisset, DK (reprint author), Univ Surrey, SMME, Guildford GU2 7XH, Surrey, England. NR 35 TC 110 Z9 110 U1 0 U2 7 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JAN 25 PY 2002 VL 451 BP 383 EP 410 DI 10.1017/10.1017/S0022112001006759 PG 28 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 522HW UT WOS:000173891300016 ER PT J AU Greeley, R Bridges, NT Kuzmin, RO Laity, JE AF Greeley, R Bridges, NT Kuzmin, RO Laity, JE TI Terrestrial analogs to wind-related features at the Viking and Pathfinder landing sites on Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article DE Mars; aeolian/eolian; ventifacts; Pathfinder; Viking landers; dunes ID KELSO DUNES; ROCKS; TRANSPORT; SURFACE; GEOLOGY; SAND; CALIFORNIA; THRESHOLD; LANDERS; DESERT AB [1] Features in the Mojave Desert and Iceland provide insight into the characteristics and origin of Martian wind-related landforms seen by the Viking and Pathfinder landers. The terrestrial sites were chosen because they exhibit diverse wind features that are generally well understood. These features have morphologies comparable to those on Mars and include origins by deposition and erosion, with erosional processes modifying both soils and rocks. Duneforms and drifts are the most common depositional features seen at the Martian landing sites and indicate supplies of sand-sized particles blown by generally unidirectional winds. Erosional features include la deposits, moat-like depressions around some rocks, and exhumed soil horizons. They indicate that wind can deflate at least some sediments and that this process is particularly effective where the wind interacts with rocks. The formation of ripples and wind tails involves a combination of depositional and erosional processes. Rock erosional features, or ventifacts, are recognized by their overall shapes, erosional flutes, and characteristic surface textures resulting from abrasion by windblown particles. The physics of saltation requires that particles in ripples and duneforms are predominantly sand-sized (60-2000 mum). The orientations of duneforms. wind tails, moats, and ventifacts are correlated with surface winds above particle threshold. Such winds are influenced by local topography and are correlated with winds at higher altitudes predicted by atmospheric models. C1 Arizona State Univ, Dept Geol Sci, Tempe, AZ 85287 USA. Jet Prop Lab, Pasadena, CA 91109 USA. Russian Acad Sci, Vernadsky Inst, Moscow 117975, Russia. Calif State Univ Northridge, Dept Geog, Northridge, CA 91330 USA. RP Greeley, R (reprint author), Arizona State Univ, Dept Geol Sci, Box 871404, Tempe, AZ 85287 USA. EM greeley@asu.edu RI Bridges, Nathan/D-6341-2016 NR 69 TC 32 Z9 32 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JAN 25 PY 2002 VL 107 IS E1 AR 5005 DI 10.1029/2000JE001481 PG 23 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 554FZ UT WOS:000175725800005 ER PT J AU Head, JW Wilson, L Weitz, CM AF Head, JW Wilson, L Weitz, CM TI Dark ring in southwestern Orientale Basin: Origin as a single pyroclastic eruption SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article DE Orientale Basin; Moon; pyroclastics; dark mantle; Io; dike ID BASALTIC MAGMA; MOON; VOLCANISM; GALILEO; DEPOSITS; PRESSURE; IO; STRATIGRAPHY; CHAMBER; HISTORY AB [1] A large, 154 km diameter dark annular ring, located in the southwestern part of the Orientale Basin along the Montes Rook ring, was first discovered and documented in Soviet Zond 8 images. Clementine LW-visible multispectral data indicate that the dark ring consists of material similar to the pyroclastic glasses collected by the Apollo astronauts, with the glasses being more closely related to the orange glass beads that comprise the Aristarchus Plateau than to the crystallized black beads typical of Taurus-Littrow. This implies relatively rapid cooling times for the eruption products. We propose that the dark ring is the manifestation of a pyroclastic eruption originating at a fissure vent, an elongate 7.5 km by 16 km depression, located near the center of the ring. The event producing the eruption began with a dike rapidly emplaced from subcrustal depths to within similar to3-4 km of the surface. The dike stabilized and degassed over similar to1.7 years to form an upper foam layer which then penetrated to the surface to cause an eruption, lasting similar to1-2 weeks. The eruption produced a similar to38 km high symmetrical spray of pyroclasts into the lunar vacuum at velocities of similar to350 to similar to420 m/s, and the pyroclastic material accumulated in a symmetrical ring around the vent. The geometry of eruption caused the deposits to accumulate preferentially in a ring representing the material ejected at 45degrees. The paucity of pyroclastic rings of this type on the Moon can be attributed to the low probability of a dike stalling at just the right depth (similar to3-4 km) to create these eruption conditions. The detailed characteristics of this ring provide important new insight into the emplacement of pyroclastics in the more regionally continuous lunar dark mantle deposits, suggesting that their sources are dominated by effusive and Hawaiian-style eruptions. The Orientale dark ring deposit has similarities to the pyroclastic rings on the Galilean satellite Io. Both the Orientale dark ring and Ionian eruptions involve acceleration of small particles to a high velocity in an expanding gas stream, silicate pyroclasts derived from the disrupted foam layer in the lunar case, and a mixture of silicate pyroclasts and "snowflakes" of condensing SO(2) solids on Io. In both cases the silicate pyroclasts ejected from the vent are accelerated by the gas until they become decoupled and continue on ballistic trajectories controlled only by gravity. Differences in mass flux and cloud opacity between the Moon and Io are the direct result of the origin and mass fraction of the volatile phase: the accumulation of a magmatic foam layer on top of a silicate intrusion in the lunar case and the intimate mixing on Io of a steadily erupting magma and liquid SO(2). The interpretation of the Orientale dark mantle ring as a pyroclastic eruption provides an alternative to the hypothesis that the dark ring represents the presence of an ancient pre-Orientale impact structure and that the Orientale Basin cavity of excavation must therefore lie within the Outer Rook Mountain ring. C1 Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. Univ Lancaster, Inst Environm & Biol Sci, Dept Environm Sci, Lancaster LA1 4YQ, England. NASA Headquarters, Washington, DC 20546 USA. RP Head, JW (reprint author), Brown Univ, Dept Geol Sci, Box 1846, Providence, RI 02912 USA. EM james_head_III@brown.edu NR 71 TC 21 Z9 21 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JAN 25 PY 2002 VL 107 IS E1 AR 5001 DI 10.1029/2000JE001438 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 554FZ UT WOS:000175725800001 ER PT J AU Borbulevych, OY Clark, RD Romero, A Tan, L Antipin, MY Nesterov, VN Cardelino, BH Moore, CE Sanghadasa, M Timofeeva, TV AF Borbulevych, OY Clark, RD Romero, A Tan, L Antipin, MY Nesterov, VN Cardelino, BH Moore, CE Sanghadasa, M Timofeeva, TV TI Experimental and theoretical study of the structure of N,N-dimethyl-4-nitroaniline derivatives as model compounds for non-linear optical organic materials SO JOURNAL OF MOLECULAR STRUCTURE LA English DT Article DE N,N-dimethyl-4-nitroaniline; hyperpolarisability; Bader's topological theory ID ELECTRON-DENSITY DISTRIBUTION; 2ND-ORDER HYPERPOLARIZABILITY; MOLECULAR-STRUCTURE; CRYSTAL-STRUCTURES; DICYANOVINYLBENZENE; POLARIZABILITIES; APPROXIMATION; SYSTEMS AB Molecular and crystal structure of a series of derivatives of NN-dimethyl-4-nitroaniline has been studied by both X-ray diffraction method and high-level ab initio calculations. According to these data, the dimethylamino groups were found to have a trigonal-pyramidal configuration and are considerably turned with respect to the ring plane in all molecules having a substituent in the ortho-position; on the contrary, this group is planar in the meta-substituted molecules. Topological analysis of the electron density function for all molecules studied within the framework of Bader's 'atoms in molecules' (AIM) theory revealed that introduction of a substituent into the ortho- or meta-position of the ring results in increasing of the contribution of the resonance forms different from the quinoid one. Contribution of the latter form is predominant for the structure of N,N-dimethyl-4-nitroaniline (1). Topological analysis of the electron density distribution was used to explain a decreasing of the molecular hyperpolarisabilites of the ortho- and meta-substituted compounds as compared with those for 1. (C) 2002 Elsevier Science B.V. All rights reserved. C1 New Mexico Highlands Univ, Dept Chem, Las Vegas, NV USA. Inst Organoelement Cpds, Moscow, Russia. Spelman Coll, Dept Chem, Atlanta, GA 30314 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. RP Borbulevych, OY (reprint author), New Mexico Highlands Univ, Dept Chem, Las Vegas, NV USA. EM oleg@kremlin.nmhu.edu NR 39 TC 29 Z9 29 U1 0 U2 8 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-2860 EI 1872-8014 J9 J MOL STRUCT JI J. Mol. Struct. PD JAN 23 PY 2002 VL 604 IS 1 BP 73 EP 86 DI 10.1016/S0022-2860(01)00642-1 PG 14 WC Chemistry, Physical SC Chemistry GA 518PQ UT WOS:000173677400008 ER PT J AU Morales-Rueda, L Still, MD Roche, P Wood, JH Lockley, JJ AF Morales-Rueda, L Still, MD Roche, P Wood, JH Lockley, JJ TI The stellar mass ratio of GK persei SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE binaries : close; stars : fundamental parameters; stars : individual : GK Per; novae, cataclysmic variables ID X-RAY BINARIES; INTERMEDIATE POLAR; CATACLYSMIC VARIABLES; STANDARD STARS; HERCULIS; SPECTROSCOPY; OSCILLATIONS; EMISSION AB We study the absorption lines present in the spectra of the long-period cataclysmic variable GK Per during its quiescent state, which are associated with the secondary star. By comparing quiescent data with outburst spectra we infer that the donor star appears identical during the two states and the inner face of the secondary star is not noticeably irradiated by flux from the accreting regions. We obtain new values for the radial velocity semi-amplitude of the secondary star, K-K = 120.5+/-0.7 km s(-1), a projected rotational velocity, V-K sin i = 61.5+/-11.8 km s(-1), and consequently a measurement of the stellar mass ratio of GK Per, q = M-K/M-WD = 0.55+/-0.21. The inferred white dwarf radial velocities are greater than those measured traditionally using the wings of Doppler-broadened emission lines suspected to originate in an accretion disc, highlighting the unsuitability of emission lines for mass determinations in cataclysmic variables. We determine mass limits for both components in the binary, M-K greater than or equal to 0.48+/-0.32 M-circle dot and M-WD greater than or equal to 0.87+/-0.24 M-circle dot. C1 Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Seabrook, MD 20706 USA. Univ St Andrews, St Andrews KY16 9SS, Fife, Scotland. Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England. Univ Keele, Sch Chem & Phys, Keele ST5 5BG, Staffs, England. San Diego State Univ, Dept Astron, San Diego, CA 92182 USA. RP Morales-Rueda, L (reprint author), Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. NR 40 TC 22 Z9 22 U1 0 U2 0 PU BLACKWELL PUBLISHING LTD PI OXFORD PA 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JAN 21 PY 2002 VL 329 IS 3 BP 597 EP 604 DI 10.1046/j.1365-8711.2002.05013.x PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 518DV UT WOS:000173652100012 ER PT J AU Scoccimarro, R Sheth, RK AF Scoccimarro, R Sheth, RK TI PTHALOS: a fast method for generating mock galaxy distributions SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE methods : numerical; large-scale structure of Universe ID DARK-MATTER HALOES; LARGE-SCALE BIAS; GRAVITATIONAL-INSTABILITY; POWER SPECTRUM; REDSHIFT-SPACE; DENSITY PROFILE; ANALYTIC MODEL; CONDENSATION; SIMULATIONS; STATISTICS AB Current models of galaxy formation applied to understanding the large-scale structure of the Universe have two parts. The first is an accurate solution of the equations of motion for the dark matter caused by gravitational clustering. The second consists of making physically reasonable approximations to the behaviour of baryons inside dark matter haloes. The first uses large, computationally intensive, N-body simulations. We argue that because the second step is, at least at present, uncertain, it is possible to obtain similar galaxy distributions without solving the first step exactly. We describe an algorithm that is several orders of magnitude faster than N-body simulations, but that is, nevertheless, rather accurate. The algorithm combines perturbation theory with virialized halo models of the non-linear density and velocity fields. For two- and three-point statistics the resulting fields are exact on large scales, and rather accurate well into the non-linear regime, particularly for two-point statistics in real and redshift space. We then show how one can use this algorithm to generate mock galaxy distributions from halo occupation numbers. As a first application, we show that it provides a good description of the clustering of galaxies in the PSCz survey. We also discuss applications to the estimation of non-Gaussian contributions to the error bars and the covariance matrix of the power spectrum, in real and redshift space, for galaxies and dark matter. The results for the latter show good agreement with simulations, supporting the use of our method for constraining cosmological parameters from forthcoming galaxy surveys. C1 NYU, Dept Phys, New York, NY 10003 USA. NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. RP Scoccimarro, R (reprint author), NYU, Dept Phys, 4 Washington Pl, New York, NY 10003 USA. NR 81 TC 104 Z9 104 U1 0 U2 1 PU BLACKWELL PUBLISHING LTD PI OXFORD PA 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JAN 21 PY 2002 VL 329 IS 3 BP 629 EP 640 DI 10.1046/j.1365-8711.2002.04999.x PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 518DV UT WOS:000173652100015 ER PT J AU Deines-Jones, P Black, JK Crawford, H Hunter, SD AF Deines-Jones, P Black, JK Crawford, H Hunter, SD TI Imaging micro-well proportional counters fabricated with masked UV laser ablation SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 5th International Conference on Position-Sensitive Detectors CY SEP 13-17, 1999 CL UNIV COLL LONDON, LONDON, ENGLAND HO UNIV COLL LONDON DE astrophysical detectors; micro-pattern detectors; micro-well detectors; pixelized proportional counters ID DETECTOR AB The micro-well detector is a gas-proportional counter similar to the CAT (Bartol et al., J. Phys. 1116 (1996) 337) and WELL detectors (Bellazzini et al., Nucl. Instr. and Meth. A 423 (1999) 125). The micro-well is a cylindrical hole formed in the polymer substrate of commercially fabricated copper-clad flexible printed circuit board by UV laser ablation. The micro-wells are drilled at GSFC's UV laser-ablation facility. The cathode is a metal annulus that surrounds the opening of the well. The anode is a metal pad that fills the bottom of the well. Advantages of this topology include intrinsic two-dimensional sensing, thick robust electrodes, and large localized image charge on the cathodes. We have fabricated 5 cm x 5 cm micro-well detectors with segmented anodes (1-d) and with both anodes and cathodes segmented (2-d), and have demonstrated: stable, proportional operation at gas gains in excess of 30,000 in Ar- and Xe-based gases; FWHM energy resolution of 20% at 6keV in P-10; preliminary 1-d spatial resolution of less than or equal to 150 mum (rms) in P-10; and the capability of MWDs to produce 2-dimensional images. We report on the design, fabrication, and testing of 1-d, 2-d, and pixelized micro-well detectors. (C) 2002 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Berkeley, CA 94720 USA. RP Deines-Jones, P (reprint author), NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. RI Hunter, Stanley/D-2942-2012 NR 2 TC 12 Z9 12 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD JAN 21 PY 2002 VL 477 IS 1-3 BP 55 EP 58 AR PII S0168-9002(01)01908-8 DI 10.1016/S0168-9002(01)01908-8 PG 4 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 522FV UT WOS:000173886100011 ER PT J AU Farah, AM Venable, DD Thorpe, AN Marsh, F Heaps, WS AF Farah, AM Venable, DD Thorpe, AN Marsh, F Heaps, WS TI Validation of a novel ultraviolet lidar system with relative Raman-scattering cross sections determined from atmospheric measurements SO APPLIED OPTICS LA English DT Article ID WATER-VAPOR; OZONE; NITROGEN; REGION; LASER; NM AB We have developed an ultraviolet lidar system in which the upwelled laser beam and the telescope field of view can be made to overlap at any specified location in space. We refer to this system as the Selected Overlap Lidar Experiment. We discuss validation of our system by calculating relative Raman-scattering cross sections (with respect to the nitrogen scattering cross section) for oxygen and water vapor using data collected during field operations of our lidar. Our relative cross sections are consistent with those obtained by other researchers making similar measurements in laboratory environments. (C) 2002 Optical Society of America. C1 Howard Univ, Dept Phys & Astron, Washington, DC 20059 USA. NASA, Goddard Space Flight Ctr, Laser & Electroopt Branch, Greenbelt, MD 20771 USA. RP Farah, AM (reprint author), Howard Univ, Dept Phys & Astron, Washington, DC 20059 USA. EM dvenable@howard.edu NR 16 TC 0 Z9 0 U1 1 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD JAN 20 PY 2002 VL 41 IS 3 BP 407 EP 411 DI 10.1364/AO.41.000407 PG 5 WC Optics SC Optics GA 514RW UT WOS:000173455700002 PM 11905564 ER PT J AU Yan, BH Stamnes, K Li, W Chen, BQ Stamnes, JJ Tsay, SC AF Yan, BH Stamnes, K Li, W Chen, BQ Stamnes, JJ Tsay, SC TI Pitfalls in atmospheric correction of ocean color imagery: how should aerosol optical properties be computed? SO APPLIED OPTICS LA English DT Article ID MARINE BOUNDARY-LAYER; SIZE DISTRIBUTIONS; MULTIPLE-SCATTERING; ALGORITHM; ABSORPTION; TRANSPORT; ATLANTIC; LIDAR AB Current methods for the atmospheric correction of ocean-color imagery rely on the computation of optical properties of a mixture of chemically different aerosol particles through combination of the mixture with it into an effective, single-particle component that has an average refractive index, However, a multicomponent approach in which each particle type independently grows and changes its refractive index with increasing humidity is more realistic. Computations based on Mie theory and radiative transfer are used to show that the two approaches result in top-of-the-atmosphere radiances that differ more than the water-leaving radiance. Thus, proper atmospheric correction requires a multicomponent approach for the computation of realistic aerosol optical properties. (C) 2002 Optical Society of America. C1 Univ Alaska, Inst Geophys, Fairbanks, AK 99775 USA. Stevens Inst Technol, Dept Phys & Engn Phys, Hoboken, NJ 07030 USA. Univ Bergen, Dept Phys, N-5007 Bergen, Norway. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Yan, BH (reprint author), Univ Alaska, Inst Geophys, Fairbanks, AK 99775 USA. EM kstamnes@stevens-tech.edu RI Tsay, Si-Chee/J-1147-2014 NR 42 TC 26 Z9 27 U1 0 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD JAN 20 PY 2002 VL 41 IS 3 BP 412 EP 423 DI 10.1364/AO.41.000412 PG 12 WC Optics SC Optics GA 514RW UT WOS:000173455700003 PM 11905565 ER PT J AU Smith, DA Wilson, AS Arnaud, KA Terashima, Y Young, AJ AF Smith, DA Wilson, AS Arnaud, KA Terashima, Y Young, AJ TI A Chandra X-ray study of Cygnus A. III. The cluster of galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : abundances; galaxies : clusters : individual (Cygnus A); galaxies : individual (Cygnus A); intergalactic medium; X-rays : galaxies : clusters; X-rays : individual (Cygnus A) ID DARK-MATTER HALOS; ASCA; GAS; ABUNDANCES; PROFILES; TEMPERATURE; DENSITY; MODELS AB We present an analysis of the Chandra Advanced CCD Imaging Spectrometer (ACIS) observation of the intracluster gas associated with the cluster of galaxies surrounding Cygnus A. The dominant gaseous structure is a roughly elliptical (presumably prolate spheroidal in three dimensions) feature with semi-major axis similar or equal to 1'.1 (similar or equal to100 kpc). This structure apparently represents intracluster gas that has been swept up and compressed by a cavity innated in this gas by relativistic material that has passed through the ends of the radio jets. The X-ray-emitting gas shows this prolate spheroidal morphology to similar or equal to1'.2 (110 kpc) from the radio galaxy but is spherical on larger scales. The X-ray emission from the intracluster gas extends to at least 8' (similar or equal to720 kpc) from the radio galaxy, and a second, extended source of X-ray emission (probably associated with a second cluster of galaxies) is seen some 12' (similar or equal to1 Mpc) to the northwest of Cygnus A. The X-ray spectrum of the integrated intracluster gas imaged on the S3 chip (dimensions 8' x 8' = 720 x 720 kpc), excluding the contribution from the radio galaxy and other compact sources of X-ray emission, has a gas temperature, metallicity, and unabsorbed 2-10 keV rest-frame luminosity of 7.7 keV, 0.34 times solar, and 3.5 x 10(44) ergs s(-1), respectively. We have deprojected the X-ray spectra taken from 12 elliptical and circular annuli in order to derive a run of temperature, metallicity, density, and pressure as a function of radius. The temperature of the X-ray-emitting gas drops from similar or equal to8 keV more than 100 kpc from the center to similar or equal to5 keV some 80 kpc from the center, with the coolest gas immediately adjacent to the radio galaxy. "Belts" of slightly cooler (similar or equal to4 keV) X-ray-emitting gas run around the minor dimension of the cavity created by the radio source, while the limb-brightened edges of the cavity are slightly hotter (similar or equal to6 keV), perhaps as a result of heating by a bow shock driven by the probably expanding cavity into the intracluster gas. There is a metallicity gradient in the X-ray-emitting gas, with the highest metallicities (similar tosolar) found close to the center, decreasing to similar to0.3 times solar in the outer parts. We have used the assumption of hydrostatic equilibrium to derive a total cluster mass within 500 kpc of 2.0 x 10(14) M-circle dot and 2.8 x 10(14) M-circle dot for constant and centrally decreasing temperature profiles, respectively. The total mass of X-ray-emitting gas within the same radius is 1.1 x 10(13) M-circle dot. Thus, the gas fraction of the cluster within 500 kpc is 0.055 and 0.039 for the constant and centrally decreasing temperature profiles, respectively. C1 Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Smith, DA (reprint author), Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NR 38 TC 84 Z9 84 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2002 VL 565 IS 1 BP 195 EP 207 DI 10.1086/324539 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 515QP UT WOS:000173507200018 ER PT J AU Moskalenko, IV Strong, AW Ormes, JF Potgieter, MS AF Moskalenko, IV Strong, AW Ormes, JF Potgieter, MS TI Secondary antiprotons and propagation of cosmic rays in the galaxy and heliosphere SO ASTROPHYSICAL JOURNAL LA English DT Review DE cosmic rays; elementary particles; Galaxy : general; ISM : general; nuclear reactions, nucleosynthesis, abundances ID SUPERSYMMETRIC DARK-MATTER; PARTIAL CROSS-SECTIONS; GALACTIC GAMMA-RAYS; HELIUM SPECTRA; SOLAR MODULATION; MAGNETIC-FIELD; HIGH-ENERGY; ASTROPHYSICAL IMPLICATIONS; NEUTRALINO ANNIHILATION; RADIAL-DISTRIBUTION AB High-energy collisions of cosmic-ray nuclei with interstellar gas are believed to be the mechanism producing the majority of cosmic-ray antiprotons. Because of the kinematics of the process, they are created with a nonzero momentum; the characteristic spectral shape with a maximum at similar to2 GeV and a sharp decrease toward lower energies makes antiprotons a unique probe of models for particle propagation in the Galaxy and modulation in the heliosphere. On the other hand, accurate calculation of the secondary antiproton flux provides a "background" for searches for exotic signals from the annihilation of supersymmetric particles and primordial black hole evaporation. Recently, new data with large statistics on both low-and high-energy antiproton fluxes have become available which allow such tests to be performed. We use our propagation code GALPROP to calculate interstellar cosmic-ray propagation for a variety of models. We show that there is no simple model capable of accurately describing the whole variety of data: boron/carbon and sub-iron/iron ratios, spectra of protons, helium, antiprotons, positrons, electrons, and diffuse gamma-rays. We find that only a model with a break in the diffusion coefficient plus convection can reproduce measurements of cosmic-ray species, and the reproduction of primaries (p, He) can be further improved by introducing a break in the primary injection spectra. For our best-fit model we make predictions of proton and antiproton fluxes near the Earth for different modulation levels and magnetic polarity using a steady state drift model of propagation in the heliosphere. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. Potchefstroom Univ Christian Higher Educ, Unit Space Phys, ZA-2520 Potchefstroom, South Africa. Moscow MV Lomonosov State Univ, Inst Nucl Phys, Moscow 119899, Russia. RP NASA, Goddard Space Flight Ctr, Code 660, Greenbelt, MD 20771 USA. EM imos@milkyway.gsfc.nasa.gov; aws@mpe.mpg.de; jfo@lheapop.gsfc.nasa.gov; fskmsp@puknet.puk.ac.za RI Moskalenko, Igor/A-1301-2007 OI Moskalenko, Igor/0000-0001-6141-458X NR 114 TC 258 Z9 259 U1 0 U2 1 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 JAN 20 PY 2002 VL 565 IS 1 BP 280 EP 296 DI 10.1086/324402 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 515QP UT WOS:000173507200025 ER PT J AU Proga, D Kallman, TR AF Proga, D Kallman, TR TI On the role of the ultraviolet and X-ray radiation in driving a disk wind in X-ray binaries SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : close; galaxies : active; hydrodynamics; methods : numerical; X-rays : binaries ID ILLUMINATED STELLAR WINDS; ACTIVE GALACTIC NUCLEI; COMPTON HEATED WINDS; ACCRETION DISKS; DRIVEN WINDS; MULTIWAVELENGTH CAMPAIGN; EXPLORER OBSERVATIONS; CORONAE; SYSTEMS; MODELS AB X-ray heating of the photosphere of an accretion disk is a possible mechanism to produce strong, broad UV emission lines in low-mass X-ray binaries (LMXBs). However, detailed photoionization calculations show that this mechanism fails to produce sufficient emission measure at suitable ionization and optical depth. We present the results of hydrodynamical calculations of the disk photosphere irradiated by strong X-rays. We attempt to determine whether LMXBs can harbor significant UV-driven disk winds despite the effects of X-ray ionization. Such winds would be a likely candidate for the site of emission of UV lines and may better explain the observations than the X-ray-heated disk photosphere. We find that the local disk radiation cannot launch a wind from the disk because of strong ionizing radiation from the central object. Unphysically high X-ray opacities would be required to shield the UV-emitting disk and allow the line force to drive a disk wind. However, the same X-ray radiation that inhibits line driving heats the disk and can produce a hot bipolar wind or corona above the disk. Our calculations are generally consistent with past work on the dynamics of coronae and winds from accretion disks in LMXBs. Additionally, our results are consistent with the UV observations of LMXB that show no obvious spectral features associated with strong and fast disk winds. To assess the impact of X-ray heating on driving of a disk wind by the line force in any system with an accretion disk, we derive analytic formulae. In particular, we compare results of line-driven disk wind models for accretion disks in LMXBs and active galactic nuclei. The latter show spectral features associated with a strong and fast disk wind, the wind that has been successfully modeled by Proga, Stone, & Kallman. The key parameter determining the role of the line force is not merely the presence of the luminous UV zone in the disk and the presence of the X-rays but also the distance of this UV zone from the center. The closer the UV zone to the center, the stronger the line force and subsequently the denser the disk wind launched by the line force. The density of the disk wind critically determines whether the wind will stay in a lower ionization state in the presence of the X-ray radiation and be further accelerated by the line force to supersonic velocities. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Proga, D (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 53 TC 60 Z9 60 U1 1 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2002 VL 565 IS 1 BP 455 EP 470 DI 10.1086/324534 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 515QP UT WOS:000173507200040 ER PT J AU Gonthier, PL Ouellette, MS Berrier, J O'brien, S Harding, AK AF Gonthier, PL Ouellette, MS Berrier, J O'brien, S Harding, AK TI Galactic populations of radio and gamma-ray pulsars in the polar cap model SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : theory; magnetic fields; pulsars : general; radiation mechanisms : nonthermal; stars neutron ID HIGH-FREQUENCY SURVEY; NEUTRON-STARS; OUTER MAGNETOSPHERE; MAGNETIC-FIELDS; POWERED PULSARS; YOUNG PULSARS; EMISSION; VELOCITIES; STATISTICS; EVOLUTION AB We simulate the characteristics of the Galactic population of radio and gamma-ray pulsars using Monte Carlo techniques. At birth, neutron stars are spatially distributed in the Galactic disk, with supernova-kick velocities, and randomly dispersed in age back to 10(9) yr. They are evolved in the Galactic gravitational potential to the present time. From a radio luminosity model, the radio flux is filtered through a selected set of radio-survey parameters. gamma-ray luminosities are assigned using the features of recent polar cap acceleration models invoking space-charge-limited flow, and a pulsar death valley further attenuates the population of radio-loud pulsars. Assuming a simple emission geometry with aligned radio and gamma-ray beams of 1 sr solid angle, our model predicts that EGRET should have seen seven radio-loud and one radio-quiet gamma-ray pulsars. With much improved sensitivity, GLAST, on the other hand, is expected to observe 76 radio-loud and 74 radio-quiet gamma-ray pulsars, of which seven would be identified as pulsed sources. We also explore the effect of magnetic field decay on the characteristics of the radio and gamma-ray pulsar populations. Including magnetic field decay on a timescale of 5 Myr improves agreement with the radio pulsar population and increases the predicted number of GLAST-detected pulsars to 90 radio-loud and 101 radio-quiet (nine pulsed) gamma-ray pulsars. The lower flux threshold allows GLAST to detect gamma-ray pulsars at larger distances than those observed by the radio surveys used in this study. C1 Hope Coll, Dept Phys, Holland, MI 49422 USA. Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Gonthier, PL (reprint author), Hope Coll, Dept Phys, 27 Graves Pl, Holland, MI 49422 USA. RI Harding, Alice/D-3160-2012 NR 71 TC 65 Z9 66 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2002 VL 565 IS 1 BP 482 EP 499 DI 10.1086/324535 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 515QP UT WOS:000173507200042 ER PT J AU Dobrzycka, D Cranmer, SR Raymond, JC Biesecker, DA Gurman, JB AF Dobrzycka, D Cranmer, SR Raymond, JC Biesecker, DA Gurman, JB TI Polar coronal jets at solar minimum SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : activity; Sun : corona; Sun : UV radiation ID ANGLE SPECTROMETRIC CORONAGRAPH; DENSITY STRUCTURE; SOHO MISSION; WHITE-LIGHT; HOLES; PLUMES; TELESCOPE; UVCS/SOHO; MODEL; EIT AB We present an analysis of six polar coronal jets observed by the Ultraviolet Coronagraph Spectrometer (UVCS) at solar minimum (1996). Four of the events were also recorded by the Extreme-Ultraviolet Imaging Telescope (EIT) and/or the Large Angle Spectrometric Coronagraph (LASCO) C2 coronagraph. We compared the jets with others recorded in 1997. We modeled the observable properties of the jet from 1996 June 11, detected at 1.5 R-circle dot. It represents a type of polar jet in which H I Lyalpha and O VI get brighter at the same time. The model reproduced the line properties with an electron density enhancement of a factor of 2 (with a resulting density of 4.8 x 10(6) cm(-3)), an outflow velocity enhancement of a factor of 3 (yielding a velocity of 200 km s(-1)), and an electron temperature decrease of a factor of 0.36 (with a resulting temperature of 5.3 x 10(5) K). We derived the jet's electron densities from the LASCO C2 white-light observations. They are a factor of 1.5 higher than in the interplume corona and comparable to those in plume regions within the C2 field of view. We developed a model for the origin of polar jets based on Wang's model for plumes. We envisioned that jets may be the result of short-lived bursts of base heating, while plumes may be the result of base-heating events that last longer than several hours. Models with the base heat flux near 3 x 10(5) ergs cm(-2) s(-1) come closest to matching the observations, though they are not entirely consistent. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Emergent Informat Technol Inc, Vienna, VA 22180 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Dobrzycka, D (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. NR 33 TC 17 Z9 17 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2002 VL 565 IS 1 BP 621 EP 629 DI 10.1086/324431 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 515QP UT WOS:000173507200052 ER PT J AU Niimura, M Smith, SJ Chutjian, A AF Niimura, M Smith, SJ Chutjian, A TI Electron excitation cross sections for the 2s(2)2p(2) P-3 -> 2s(2)2p(2) D-1 transition in O2+ SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic data; atomic processes ID IO PLASMA TORUS; PLANETARY-NEBULAE; LINE-INTENSITIES; O-III; STRENGTHS AB Absolute experimental excitation cross sections are reported for the combined 2s(2)2p(2) P-3 (0,1,2) --> 2s(2)2p(2) D-1(2) spin- and symmetry-forbidden transitions in O2+. These excitations correspond to the optical emission wavelengths lambda5009.0 (J = 2 --> 2) and lambda4960.9 (J = 2 --> 1). Use is made in the measurements of the electron energy-loss method with merged electron and ion beams. Data are reported for the center-of-mass collision energy range of 2.48 eV (threshold) to 5.35 eV (or 2.2x threshold). One finds agreement between experiment and some of the predictions of resonances in a recent 26 state R-matrix calculation. In particular, experiment confirms the presence of strong, narrow resonances near 2.7 and 4.2 eV, detectable with an experimental electron-beam energy spread of only 0.10 eV (FWHM). Resonance enhancement predicted at 3.1 eV is absent in the experiment. C1 CALTECH, Jet Prop Lab, Atom & Mol Collis Team, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, Atom & Mol Collis Team, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 5 Z9 5 U1 0 U2 1 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 JAN 20 PY 2002 VL 565 IS 1 BP 645 EP 647 DI 10.1086/324432 PN 1 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 515QP UT WOS:000173507200056 ER PT J AU Velusamy, T Langer, WD Goldsmith, PF AF Velusamy, T Langer, WD Goldsmith, PF TI Tracing the infall and the accretion shock in the protostellar disk: L1157 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; ISM : individual (L1157); ISM : molecules; stars : formation; stars : pre-main-sequence ID EVOLUTION; METHANOL AB We present the first observational evidence supporting the presence of an accretion shock in a protostellar disk. This result was obtained from the spatially resolved methanol emission in the 5(0)-4(0) (A) transition at 1 mm in the Class 0 protostellar object L1157. The high spatial resolution (with a beam of similar to1".1 x 1".1) maps of methanol and continuum dust emission were observed with the Owens Valley Radio Observatory Millimeter Array. The structure and kinematics of the methanol emission indicate that the gas is tracing a warm layer in the infall-disk interface, consistent with an accretion shock. This result confirms an important prediction of theoretical models of infalling material feeding the growth of protostellar disks. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Cornell Univ, Dept Astron, Natl Astron & Ionosphere Ctr, Ithaca, NY 14853 USA. RP Velusamy, T (reprint author), CALTECH, Jet Prop Lab, MS 169-506,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Goldsmith, Paul/H-3159-2016 NR 12 TC 17 Z9 17 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2002 VL 565 IS 1 BP L43 EP L46 DI 10.1086/339246 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 515QR UT WOS:000173507400011 ER PT J AU Joughin, I Tulaczyk, S AF Joughin, I Tulaczyk, S TI Positive mass balance of the Ross Ice Streams, West Antarctica SO SCIENCE LA English DT Article ID SHEET; FLOW AB We have used ice-flow velocity measurements from synthetic aperture radar to reassess the mass balance of the Ross Ice Streams, West Antarctica. We find strong evidence for ice-sheet growth (+ 26.8 gigatons per year), in contrast to earlier estimates indicating a mass deficit (-20.9 gigatons per year), Average thickening is equal to similar to25% of the accumulation rate, with most of this growth occurring on Ice Stream C. Whillans Ice Stream, which was thought to have a significantly negative mass balance, is close to balance, reflecting its continuing slowdown. The overall positive mass balance may signal an end to the Holocene retreat of these ice streams. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Santa Cruz, Dept Earth Sci, Santa Cruz, CA 95064 USA. RP Joughin, I (reprint author), CALTECH, Jet Prop Lab, Mailstop 300-235,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Joughin, Ian/A-2998-2008 OI Joughin, Ian/0000-0001-6229-679X NR 32 TC 134 Z9 136 U1 0 U2 9 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 JAN 18 PY 2002 VL 295 IS 5554 BP 476 EP 480 DI 10.1126/science.1066875 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 512YG UT WOS:000173350700043 PM 11799237 ER PT J AU Kodibagkar, V Herberg, JL Bowman, RC Conradi, MS AF Kodibagkar, V Herberg, JL Bowman, RC Conradi, MS TI NMR study of a temperature-induced structural transition in ZrBe2Dx SO JOURNAL OF ALLOYS AND COMPOUNDS LA English DT Article; Proceedings Paper CT International Symposium on Metal-Hydrogen Systems, Fundamentals and Applications (MH2000) CY OCT 01-06, 2000 CL NOOSA HEADS, AUSTRALIA DE intermetallic compound; deuterium; diffusion; two-dimensional diffusion; structural transition; isotope effect; NMR ID NUCLEAR-MAGNETIC-RESONANCE; HYDROGEN DIFFUSION; ZRBE2H1.4 AB We have studied the motion of D atoms in ZrBe2D1.56 and ZrBe2D1.4 using deuterium NMR and observed a temperature-induced structural transition near 240 K. By comparing the behavior of hydride and deuteride samples with the same concentration (x=1.4), the absence of a transition in the hydride is shown to be an isotope effect. Above 240 K, the deuterium relaxation times T, and T, behave as expected from proton data in ZrBe2H1.4. However, on decreasing the temperature below 240 K, T-2 decreases rapidly and T-1 increases rapidly, indicating that the D atom mobility is dramatically reduced. Above the transition temperature, the spectrum shows a quadrupolar doublet splitting of order 1 kHz, reflecting a small motionally averaged electric field-gradient (EFG) at the D atoms. Upon cooling below 240 K the line broadens rapidly, revealing a large distribution of quadrupolar splittings and EFGs at the individual sites. Thus substantial variations exist between the D-atom sites, despite their nominal equivalence in the neutron diffraction-determined structure. We suggest that the strong Be-H (Be-D) repulsion generates substantial Be displacements near vacant D-atom sites. The probable nature of the transition is discussed from the point of view of ordering of D-atom vacancies. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Washington Univ, Dept Phys, St Louis, MO 63130 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kodibagkar, V (reprint author), Washington Univ, Dept Phys, CB 1105, St Louis, MO 63130 USA. NR 15 TC 5 Z9 5 U1 0 U2 4 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0925-8388 J9 J ALLOY COMPD JI J. Alloy. Compd. PD JAN 17 PY 2002 VL 330 BP 179 EP 182 DI 10.1016/S0925-8388(01)01525-0 PG 4 WC Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Chemistry; Materials Science; Metallurgy & Metallurgical Engineering GA 508KT UT WOS:000173087800036 ER PT J AU Cantrell, JS Bowman, RC Maeland, AJ AF Cantrell, JS Bowman, RC Maeland, AJ TI X-ray diffraction, neutron scattering and NMR studies of hydrides formed by Ti4Pd2O and Zr4Pd2O SO JOURNAL OF ALLOYS AND COMPOUNDS LA English DT Article; Proceedings Paper CT International Symposium on Metal-Hydrogen Systems, Fundamentals and Applications (MH2000) CY OCT 01-06, 2000 CL NOOSA HEADS, AUSTRALIA DE metal hydrides; crystal structure; hydrogen diffusion; X-ray powder diffraction; neutron powder diffraction; nuclear magnetic resonance ID DEUTERIUM SITE OCCUPATION; ETA-CARBIDES ZR3V3ODX; HYDROGEN DIFFUSION; CRYSTAL-STRUCTURE; LOCAL-STRUCTURE; PHASE; BETA-TI1-YVYHX; BEHAVIOR; SYSTEMS; ZRTI2HX AB The oxygen-stabilized Ti4Pd2O and Zr4Pd2O alloys with the cubic E9(3)-Ti2Ni type structure have been reacted with hydrogen gas. Powder X-ray diffraction (XRD) has shown that the hydride phase retains a face-centered-cubic unit cell with an expansion of lattice parameter that is dependent on hydrogen content. The crystal structure has been solved for Zr4Pd2OD3.5 by neutron diffraction. NMR measurements of proton relaxation times were made on Ti4Pd2OH5.0 to assess diffusion behavior. Although the activation energy of 0.39 eV derived for Ti4Pd2OH5.0 was nearly identical to the value found for hydrogen diffusion in oxygen-free Ti2PdH1.47, the spin-lattice (T-1d) and rotating-frame (T-1l,) relaxation times minima were at much lower temperatures for Ti4Pd2OH5.0, which implies more rapid hydrogen diffusion rates in the oxygen-stabilized phase. The nearest neighbor coordination sites that are involved in proposed hydrogen diffusion path ways are discussed and compared to the deuterium sites of Zr4Pd2OD3.5. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Miami Univ, Dept Chem & Biochem, Oxford, OH 45056 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Inst Energy Technol, Dept Phys, N-2007 Kjeller, Norway. RP Cantrell, JS (reprint author), Miami Univ, Dept Chem & Biochem, Oxford, OH 45056 USA. OI Bowman, Robert/0000-0002-2114-1713 NR 28 TC 9 Z9 10 U1 0 U2 2 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0925-8388 J9 J ALLOY COMPD JI J. Alloy. Compd. PD JAN 17 PY 2002 VL 330 BP 191 EP 196 DI 10.1016/S0925-8388(01)01454-2 PG 6 WC Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Chemistry; Materials Science; Metallurgy & Metallurgical Engineering GA 508KT UT WOS:000173087800039 ER PT J AU Bowman, RC Lindensmith, CA Luo, S Flanagan, TB Vogt, T AF Bowman, RC Lindensmith, CA Luo, S Flanagan, TB Vogt, T TI Degradation behavior of LaNi5-xSnxHz (x=0.20-0.25) at elevated temperatures SO JOURNAL OF ALLOYS AND COMPOUNDS LA English DT Article; Proceedings Paper CT International Symposium on Metal-Hydrogen Systems, Fundamentals and Applications (MH2000) CY OCT 01-06, 2000 CL NOOSA HEADS, AUSTRALIA DE La-Ni-Sn alloys; CaCu5 phases; P-C isotherms; non-stoichiometric alloys; hydride degradation behavior; X-ray diffraction ID SYSTEM; ISOTHERMS; HYDRIDES; ALLOYS AB Systematic studies of the hydriding behavior of LaNi5-xSnx alloys with tin contents in the range 0.20 1000 h) at elevated temperatures and hydrogen pressure to produce further degradation in the P-C-T isotherms. The impact of alloy composition on the isotherms has been determined. The crystal lattice properties of the alloys before and after hydrogen reactions have been studied using high-resolution X-ray powder diffraction with synchrotron radiation. Changes in these X-ray diffraction patterns are correlated to various structural modifications resulting from hydride formation and degradation. (C) 2002 Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Vermont, Dept Chem, Burlington, VT 05405 USA. Brookhaven Natl Lab, Dept Phys, Upton, NY 11973 USA. RP Bowman, RC (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Vogt, Thomas /A-1562-2011; OI Vogt, Thomas /0000-0002-4731-2787; Bowman, Robert/0000-0002-2114-1713 NR 19 TC 32 Z9 32 U1 0 U2 4 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0925-8388 J9 J ALLOY COMPD JI J. Alloy. Compd. PD JAN 17 PY 2002 VL 330 BP 271 EP 275 DI 10.1016/S0925-8388(01)01521-3 PG 5 WC Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Chemistry; Materials Science; Metallurgy & Metallurgical Engineering GA 508KT UT WOS:000173087800054 ER PT J AU Luo, S Flanagan, TB Bowman, RC AF Luo, S Flanagan, TB Bowman, RC TI Hydrogen isotherms for LaNi4.6M0.4 alloys where M-group 4A elements SO JOURNAL OF ALLOYS AND COMPOUNDS LA English DT Article; Proceedings Paper CT International Symposium on Metal-Hydrogen Systems, Fundamentals and Applications (MH2000) CY OCT 01-06, 2000 CL NOOSA HEADS, AUSTRALIA DE hydrogen isotherms; LaNi5; alloys ID LANI5-XSNX-H; DEGRADATION; SYSTEM AB Hydrogen isotherms have been measured for activated LaNi4.6M0.4 alloys from 300 to 473 or 493 K where M=Si, Ge, Sn. Thermodynamic parameters have been obtained from the isotherms using van't Hoff plots for hydride formation and decomposition. The DeltaH(plat) values are more exothermic than for the parent compound, LaNi5, but the DeltaS(plat) values are similar. As for the LaNi5-xSnx alloys, LaNi4.6Ge0.4 and LaNi4.6Si0.4 have a greater resistance towards degradation than the parent compound. (C) 2002 Published by Elsevier Science B.V. C1 Univ Vermont, Mat Sci Program, Burlington, VT 05405 USA. Univ Vermont, Dept Chem, Burlington, VT 05405 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Luo, S (reprint author), Univ Vermont, Mat Sci Program, Burlington, VT 05405 USA. NR 14 TC 14 Z9 14 U1 0 U2 2 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0925-8388 J9 J ALLOY COMPD JI J. Alloy. Compd. PD JAN 17 PY 2002 VL 330 BP 531 EP 535 DI 10.1016/S0925-8388(01)01623-1 PG 5 WC Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Chemistry; Materials Science; Metallurgy & Metallurgical Engineering GA 508KT UT WOS:000173087800109 ER PT J AU Prina, M Kulleck, JG Bowman, RC AF Prina, M Kulleck, JG Bowman, RC TI Assessment of Zr-V-Fe getter alloy for gas-gap heat switches SO JOURNAL OF ALLOYS AND COMPOUNDS LA English DT Article; Proceedings Paper CT International Symposium on Metal-Hydrogen Systems, Fundamentals and Applications (MH2000) CY OCT 01-06, 2000 CL NOOSA HEADS, AUSTRALIA DE hydrogen storage; Zr-V-Fe hydrides; reversible thermal switch; X-ray diffraction; P-C-T isotherms; hydrogen getters ID PURIFICATION; DIFFRACTION; SORPTION; SYSTEM AB A commercial Zr-V-Fe alloy (i.e. SAES Getters trade name alloy St-172) has been assessed as reversible hydrogen storage material for use in actuators of gas-gap heat switches. For applications involving hydride compressors in closed-cycle Joule-Thomson sorption cryocoolers, the actuator need to produce a conducting (i.e. ON) state pressure above 670 Pa and an insulating (i.e. OFF) state pressure below 0.13 Pa in the gas-gap switch with switching times similar to200 s between the two states. Pressure-composition-temperature isotherms have been measured for the SAES St-172 material to define power efficient baseline performance at appropriate hydrogen concentration for these heat switch actuators. Two prototype actuators containing the SAES St-172 material were built and operated for several thousand cycles to evaluate performance of the metal hydride system under conditions simulating heat switch operation. (C) 2002 Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bowman, RC (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. OI Bowman, Robert/0000-0002-2114-1713 NR 20 TC 21 Z9 22 U1 0 U2 3 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0925-8388 J9 J ALLOY COMPD JI J. Alloy. Compd. PD JAN 17 PY 2002 VL 330 BP 886 EP 891 DI 10.1016/S0925-8388(01)01522-5 PG 6 WC Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Chemistry; Materials Science; Metallurgy & Metallurgical Engineering GA 508KT UT WOS:000173087800177 ER PT J AU Masterson, RA Miller, DW Grogan, RL AF Masterson, RA Miller, DW Grogan, RL TI Development and validation of reaction wheel disturbance models: Empirical model SO JOURNAL OF SOUND AND VIBRATION LA English DT Article ID PERFORMANCE AB Accurate disturbance models are necessary to predict the effects of vibrations on the performance of precision space-based telescopes, such as the Space Interferometry Mission (SIM). There are many possible disturbance sources on such spacecraft, but mechanical jitter from the reaction wheel assembly (RWA) is anticipated to be the largest. A method has been developed and implemented in the form of a MATLAB toolbox to extract parameters for an empirical disturbance model from RWA micro-vibration data. The disturbance model is based on one that was used to predict the vibration behaviour of the Hubble Space Telescope (HST) wheels and assumes that RWA disturbances consist of discrete harmonics of the wheel speed with amplitudes proportional to the wheel speed squared. The MATLAB toolbox allows the extension of this empirical disturbance model for application to any reaction wheel given steady state vibration data. The toolbox functions are useful for analyzing RWA vibration data, and the model provides a good estimate of the disturbances over most wheel speeds. However, it is shown that the disturbances are under-predicted by a model of this form over some wheel speed ranges. The poor correlation is due to the fact that the empirical model does not account for disturbance amplifications caused by interactions between the harmonics and the structural modes of the wheel. Experimental data from an ITHACO Space Systems E-type reaction wheel are used to illustrate the model development and validation process. (C) 2002 Academic Press. C1 MIT, Dept Aeronaut & Astronaut, Space Syst Lab, Cambridge, MA 02139 USA. MIT, Dept Aeronaut & Astronaut, Space Syst Lab, Cambridge, MA 02139 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Masterson, RA (reprint author), MIT, Dept Aeronaut & Astronaut, Space Syst Lab, 77 Massachusetts Ave, Cambridge, MA 02139 USA. NR 20 TC 53 Z9 63 U1 0 U2 10 PU ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD JAN 17 PY 2002 VL 249 IS 3 BP 575 EP 598 DI 10.1006/jsvi.2001.3868 PG 24 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 514YZ UT WOS:000173469800010 ER PT J AU Callis, LB Natarajan, M Lambeth, JD AF Callis, LB Natarajan, M Lambeth, JD TI Observed and calculated mesospheric NO, 1992-1997 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HALOGEN OCCULTATION EXPERIMENT; MIDDLE ATMOSPHERE; NITRIC-OXIDE; ELECTRONS; TRANSPORT AB [1] Mesospheric nitric oxide as observed by the Halogen Occultation Experiment (HALOE) and calculated by the Langley Research Center two-dimensional chemical transport model are compared on a daily and collocated basis for the period 920101 through 971231. Results show excellent agreement when energetic electron precipitation (EEP) from the outer trapping region of the magnetosphere is included. A simulation using only an upper boundary condition derived from the HALOE, but not explicitly including EEP, is deficient in NO at altitudes above 60 km. The contribution to the stratosphere of odd nitrogen formed by EEP in the mesosphere is significant and is approximately three times the contribution due to the HALOE upper boundary condition (HUBC) which approximates auroral electron precipitation, and solar EUV and solar X-ray effects on NO formation. C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. Sci Applicat Int Corp, Hampton, VA 23666 USA. RP Callis, LB (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, Mail Stop 401B, Hampton, VA 23681 USA. EM lbc@jaguar.larc.nasa.gov NR 11 TC 10 Z9 10 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JAN 15 PY 2002 VL 29 IS 2 AR 1030 DI 10.1029/2000GL013995 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609CR UT WOS:000178885500001 ER PT J AU Choi, KK Bandara, SV Gunapala, SD Liu, WK Fastenau, JM AF Choi, KK Bandara, SV Gunapala, SD Liu, WK Fastenau, JM TI Detection wavelength of InGaAs/AlGaAs quantum wells and superlattices SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID INFRARED PHOTODETECTORS; MU-M; INTERSUBBAND TRANSITIONS; CUTOFF WAVELENGTH; ABSORPTION; GAAS; GAAS/ALGAAS; BAND AB InGaAs/AlGaAs quantum well structures have been shown to be versatile for infrared detection. By changing the material composition, one can tune the detection wavelength from 2 to 35 mum and beyond. However, there have been few systematic calculations on the absorption wavelength of these structures with respect to their structural parameters. In this work we have adopted the transfer-matrix method to calculate both their energy levels and the wave functions. From this calculation, the absorption and the responsivity spectra of the structures can be predicted. The theory agrees with the experimental result of the test structures. Supported by the experimental evidence, we applied the calculation to a general class of midwavelength detectors and thus established a useful guideline for the detector design in this wavelength range. (C) 2002 American Institute of Physics. C1 USA, Res Lab, Adelphi, MD 20783 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. IQE Inc, Bethlehem, PA 18015 USA. RP Choi, KK (reprint author), USA, Res Lab, 2800 Powder Mill Rd, Adelphi, MD 20783 USA. RI Liu, Wing/B-7599-2009; Choi, Kwong-Kit/K-9205-2013 NR 22 TC 34 Z9 39 U1 1 U2 8 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 JAN 15 PY 2002 VL 91 IS 2 BP 551 EP 564 DI 10.1063/1.1421216 PG 14 WC Physics, Applied SC Physics GA 506NG UT WOS:000172978200001 ER PT J AU Florenchie, P Perigaud, C AF Florenchie, P Perigaud, C TI Role of the western Pacific Ocean boundary conditions during 1980-1998 in the El Nino-Southern Oscillation events simulated by a coupled ocean-atmosphere model SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article DE ENSO; Indonesian throughflow; forecast; coupled model; western boundary ID 1993-1998 TOPEX/POSEIDON PERIOD; INDONESIAN THROUGHFLOW; EQUATORIAL OCEAN; INDIAN OCEANS; INTERANNUAL VARIATIONS; SEASONAL-VARIATIONS; CIRCULATION MODEL; TROPICAL PACIFIC; WIND STRESS; SEA-LEVEL AB [1] In situ and satellite sea level data sets over 1980 - 1998 are used to estimate interannual variations of the geostrophic zonal transport from the western Pacific Ocean into the Celebes Sea. Then the transport component due to the Pacific wind-driven and fully reflected equatorial waves is removed. Finally, the residual variations, named Indonesian throughflow correction (ITFC), are used to correct for the model closed western boundary. ITFC inflows/outflows are leading the warm/cold events by a few months. They are then prescribed at the model western boundary over 1980-1998 to compare with closed boundary simulations. An ITFC inflow anomaly makes the eastern Pacific slightly warmer and trade winds in the central Pacific slightly weaker. Indeed, these quantities are simulated by both experiments in very good agreement with observations. More importantly, prescribing the ITFC greatly improves two characteristics of the model that play a key role in the coupled simulations. The first is the RMS variability of sea level versus longitude; the ITFC shifts to the west the position of the minimum. The second is the basin average sea level; the ITFC largely amplifies its fluctuations, stimulating the charge and discharge of the system. Consequently, the ITFC can have a very large impact on El Nino-Southern Oscillation forecasts. For example, the 1982/1983 and 1997/1998 1-year lead forecasts which fail to predict the warm events with closed boundaries are successful with the ITFC. The impact of the ITFC on coupled simulations is not linearly dependent on the ITFC value itself: In addition to the fluctuating conditions at the western boundary, results depend on how close to instability the system is at each time step. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Florenchie, P (reprint author), Univ Cape Town, Dept Oceanog, ZA-7700 Rondebosch, South Africa. NR 40 TC 1 Z9 1 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-OCEANS JI J. Geophys. Res.-Oceans PD JAN 15 PY 2002 VL 107 IS C1 AR 3002 DI 10.1029/2000JC000615 PG 19 WC Oceanography SC Oceanography GA 609RJ UT WOS:000178918100007 ER PT J AU Morozhenko, V Kostiuk, T Buhl, D Hewagama, T Livengood, TA Kollyukh, A Blass, WE AF Morozhenko, V Kostiuk, T Buhl, D Hewagama, T Livengood, TA Kollyukh, A Blass, WE TI Infrared heterodyne spectroscopic measurements of transition frequencies and intensities of ethylene and isotopic ethylene ((C12CH4)-C-13) between 840 and 980 cm(-1) SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article DE ethylene; C2H4; line intensities; line frequencies; infrared heterodyne spectroscopy; spectra; isotope; isotopic C2H4 ID TITANS ATMOSPHERE; SATURNIAN SYSTEM; LASER; C2H4; CO2; BAND AB Infrared heterodyne spectroscopy (lambda/Delta lambda greater than or equal to 10(6)) enabled the precision measurement of lineshapes of 168 ethylene absorption transitions for (C2H4)-C-12 and 88 absorption transitions for C-13 (CH4)-C-12. Of the 168 (C2H4)-C-12 transitions, 96 are assigned to nu (7), 17 to nu (10), 10 to nu (4), and 45 to hotband transitions. The 88 C-13 (CH4)-C-12 transitions have not been assigned. Measurements were made at gas temperatures in the range of 293-297 K and at pressures in the range of 0.05-0.5 Torr. Absolute line frequencies and line intensities were retrieved for each of the transitions. Frequencies and absolute intensities of unblended strong lines were determined to better than 5 x 10(-5) cm(-1) and 10%, respectively. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Greenbelt, MD 20771 USA. Inst Semicond Phys, UA-252065 Kiev 28, Ukraine. Univ Tennessee, Dept Phys & Astron, Complex Syst Lab, Knoxville, TN 37996 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Kostiuk, T (reprint author), NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Code 693, Greenbelt, MD 20771 USA. RI Blass, William/A-2792-2008; Hewagama, T/C-8488-2012; Livengood, Timothy/C-8512-2012; Kostiuk, Theodor/A-3077-2014 NR 24 TC 10 Z9 10 U1 1 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD JAN 15 PY 2002 VL 72 IS 2 BP 101 EP 115 DI 10.1016/S0022-4073(01)00049-8 PG 15 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 481GC UT WOS:000171510700001 ER PT J AU Devi, VM Benner, DC Brown, LR Smith, MAH Rinsland, CP Sams, RL Sharpe, SW AF Devi, VM Benner, DC Brown, LR Smith, MAH Rinsland, CP Sams, RL Sharpe, SW TI Multispectrum analysis of self- and N-2-broadening, shifting and line mixing coefficients in the nu(6) band of (CH3D)-C-12 SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article DE methane; monodeuterated methane; infrared spectra; Fourier transform infrared (FTIR) spectroscopy; spectral lineshape ID DIODE-LASER MEASUREMENTS; AIR-BROADENED WIDTH; 6-10 MU-M; TEMPERATURES RELEVANT; INFRARED-SPECTRUM; FITTING TECHNIQUE; CM(-1); INTENSITIES; (H2O)-O-16; ABSORPTION AB A multispectrum nonlinear least-squares fitting technique has been applied to determine accurate zero-pressure line center positions, Lorentz self- and N-2-broadening coefficients and self- and N-2-induced pressure shift coefficients of transitions in the nu (6) (E) perpendicular band of (CH3D)-C-12 between 1035 and 1270 cm(-1). Seventeen high-resolution (0.002-0.006 cm(-1)) room temperature absorption spectra recorded with two Fourier transform spectrometers (FTS) were analyzed together. Self-broadening coefficients for over 700 transitions and self-shift coefficients for more than 600 transitions were determined. Measurements of nitrogen-broadening coefficients for more than 480 transitions and nitrogen pressure induced shift coefficients for nearly 430 transitions were also made. The measurements include transitions with rotational quantum numbers as high as J " = 18 and K " = 15 and several forbidden transitions. The measurements were made in all six sub-bands (P-P, (P)Q, R-P, P-R, (R)Q and R-R). The measured self-broadening coefficients vary from 0.025-0.096 cm(-1) atm(-1) at 296 K and the N2-broadening coefficients from 0.02 to 0.08 cm(-1) atm(-1) at 296 K. Self-induced-shift coefficients range from -0.014 to +0.004 cm(-1) atm(-1) while the nitrogen-induced-shift coefficients vary from -0.013 to +0.008 cm(-1) atm(-1). Very few of the measured pressure-shift coefficients were positive, and the positive shift coefficients were mostly associated with the J " = K " transitions in the (P)Q sub-bands. The off-diagonal relaxation matrix element coefficients of a number of transitions with K " = 3 doublets for both self- and N-2-broadening were also obtained. The results obtained with the two different broadening gases are compared and discussed. Comparisons with previous values from the literature are also made. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Coll William & Mary, Dept Phys, Williamsburg, VA 23187 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Langley Res Ctr, Hampton, VA 23691 USA. Pacific NW Natl Lab, Richland, WA 99352 USA. RP Benner, DC (reprint author), Coll William & Mary, Dept Phys, Box 8795, Williamsburg, VA 23187 USA. NR 25 TC 20 Z9 20 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD JAN 15 PY 2002 VL 72 IS 2 BP 139 EP 191 PG 53 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 481GC UT WOS:000171510700004 ER PT J AU Morozhenko, V Kostiuk, T Blass, WE Hewagama, T Livengood, TA AF Morozhenko, V Kostiuk, T Blass, WE Hewagama, T Livengood, TA TI Self- and nitrogen broadening of the nu(10)20(11,10) <- 19(10,9) ethylene transition at 927.01879 cm(-1) SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article DE ethylene; C2H4; line broadening; infrared heterodyne spectra; spectroscopy; self-broadening; nitrogen-broadening ID INFRARED OBSERVATIONS; TITANS ATMOSPHERE; SATURNIAN SYSTEM; ETHANE; LINES; BAND AB Self- and nitrogen (N-2) broadening of ethylene (C2H4) have been measured for the nu (10) 20(11,10) <-- 19(10,9) ethylene transition at 927.01879 cm(-1). The measurements were made using infrared heterodyne spectroscopy with a spectral resolution of similar to1.7 x 10(-4) cm(-1). At 296 K, the retrieved self-broadening coefficient for the observed transition is 0.1244(92)cm(-1)/atm; the nitrogen-broadening coefficient is 0.0757(99) cm(-1)/atm. These results represent the most conservative treatment of experimental and statistical errors. A different purely statistical approach provides consistent values with uncertainties of only a few percent. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Greenbelt, MD 20771 USA. Univ Tennessee, Dept Phys & Astron, Complex Syst Lab, Knoxville, TN 37996 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Kostiuk, T (reprint author), NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Code 693, Greenbelt, MD 20771 USA. RI Blass, William/A-2792-2008; Hewagama, T/C-8488-2012; Livengood, Timothy/C-8512-2012; Kostiuk, Theodor/A-3077-2014 NR 20 TC 7 Z9 7 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD JAN 15 PY 2002 VL 72 IS 2 BP 193 EP 198 DI 10.1016/S0022-4073(01)00050-4 PG 6 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 481GC UT WOS:000171510700005 ER PT J AU Keller, P Thomsen, DL Li, MH AF Keller, P Thomsen, DL Li, MH TI Facile and inexpensive synthesis of alpha,beta,beta '-deuterated liquid crystalline and classical acrylate monomers SO MACROMOLECULES LA English DT Article ID CHAIN CONFORMATION; POLYMERS; ACID C1 Inst Curie, Sect Rech, CNRS, UMR 168,Lab Physicochim Curie, F-75231 Paris 05, France. Univ Colorado, Dept Chem & Biochem, Ferroelect Liquid Crystals Mat Res Ctr, Boulder, CO 80309 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Keller, P (reprint author), Inst Curie, Sect Rech, CNRS, UMR 168,Lab Physicochim Curie, 11 Rue P & M Curie, F-75231 Paris 05, France. NR 14 TC 12 Z9 12 U1 1 U2 12 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0024-9297 J9 MACROMOLECULES JI Macromolecules PD JAN 15 PY 2002 VL 35 IS 2 BP 581 EP 584 DI 10.1021/ma010838m PG 4 WC Polymer Science SC Polymer Science GA 510WE UT WOS:000173229600037 ER PT J AU Raj, SV Bieler, TR Mohamed, FA Kad, BK AF Raj, SV Bieler, TR Mohamed, FA Kad, BK TI Rate processes in plastic deformation II: Towards a unified constitutive theory of deformation - Preface SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Editorial Material C1 NASA, Glenn Res Ctr, Div Mat, Cleveland, OH 44135 USA. Michigan State Univ, E Lansing, MI 48824 USA. Univ Calif Irvine, Irvine, CA 92717 USA. Univ Calif San Diego, La Jolla, CA 92093 USA. RP Raj, SV (reprint author), NASA, Glenn Res Ctr, Div Mat, 21000 Brookpk Rd,MS 24-1, Cleveland, OH 44135 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD JAN 15 PY 2002 VL 322 IS 1-2 SI SI BP IX EP X DI 10.1016/S0921-5093(01)01114-5 PG 2 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 516KK UT WOS:000173552300001 ER PT J AU Raj, SV AF Raj, SV TI Power-law and exponential creep in class M materials: discrepancies in experimental observations and implications for creep modeling SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article; Proceedings Paper CT 2nd International Symposium on Rate Processes in Plastic Deformation held at the TMS Fall Meeting CY OCT 09-10, 2000 CL ST LOUIS, MO SP ASM Int, AIME, Mat Soc, Glenn Res Ctr, NASA DE power-law and exponential creep; creep microstructure; creep modeling; activation energy; viscoplastic models; dislocation patterning; nonlinear dislocation dynamics ID HIGH-TEMPERATURE CREEP; COPPER SINGLE CRYSTALS; STEADY-STATE CREEP; STACKING-FAULT ENERGY; 316 STAINLESS-STEEL; INTERMEDIATE TEMPERATURES; DISLOCATION-STRUCTURES; CROSS-SLIP; POLYCRYSTALLINE ALUMINUM; ELEVATED-TEMPERATURE AB This paper discusses our current understanding of the processes thought to be dominant in the exponential creep regime as well as the implications for creep modeling relating to both power-law and exponential creep regions. The significance and implications of creep controlled by vacancy diffusion along dislocation cores are discussed. It is pointed out that creep substructures, other than subgrains. have been reported in the literature, and a bifurcation diagram is presented to demonstrate how this evolution can occur from an initially homogeneous dislocation substructure. The use of nonlinear dislocation dynamics in creep modeling is advocated to rationalize the observed diversity in the creep substructures. It is demonstrated that the dislocation substructure evolution models can be coupled with a viscoplastic model through the volume fractions of the 'hard' and 'soft' phases. This coupling is shown to lead to the stress-subgrain size relationship in a simple and a natural way. Published by Elsevier Science B.V. C1 NASA, Glenn Res Ctr, Div Mat, Cleveland, OH 44135 USA. RP Raj, SV (reprint author), NASA, Glenn Res Ctr, Div Mat, MS 24-1, Cleveland, OH 44135 USA. EM sai.v.raj@grc.nasa.gov NR 86 TC 25 Z9 26 U1 1 U2 4 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD JAN 15 PY 2002 VL 322 IS 1-2 SI SI BP 132 EP 147 DI 10.1016/S0921-5093(01)01126-1 PG 16 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 516KK UT WOS:000173552300013 ER PT J AU Hansen, J Ruedy, R Sato, M Lo, K AF Hansen, J Ruedy, R Sato, M Lo, K TI Global warming continues SO SCIENCE LA English DT Letter C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Hansen, J (reprint author), NASA, Goddard Inst Space Studies, New York, NY 10025 USA. NR 5 TC 32 Z9 34 U1 0 U2 4 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 JAN 11 PY 2002 VL 295 IS 5553 BP 275 EP 275 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 511RD UT WOS:000173278600022 PM 11789536 ER PT J AU Smette, A Heap, SR Williger, GM Tripp, TM Jenkins, EB Songaila, A AF Smette, A Heap, SR Williger, GM Tripp, TM Jenkins, EB Songaila, A TI Hubble Space Telescope Space Telescope Imaging System observations of the HeII Gunn-Peterson effect toward HE 2347-4342 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; intergalactic medium; quasars : absorption lines; quasars : individual (HE 2347-4342) ID LY-ALPHA FOREST; QUASI-STELLAR OBJECTS; METAL-LINE RATIOS; INTERGALACTIC MEDIUM; HIGH-REDSHIFT; ABSORPTION SYSTEMS; RADIATIVE-TRANSFER; HELIUM ABSORPTION; CLUMPY UNIVERSE; IONIZED HELIUM AB We present an HST Space Telescope Imaging System (STIS) spectrum of the He II Gunn-Peterson effect toward HE 2347-4342. Compared to the previous HST Goddard High Resolution Spectrograph data obtained by Reimers et al. the STIS spectrum has a much improved resolution. The two-dimensional detector also allows us to better characterize the sky and dark background. We confirm the presence of two spectral ranges of much reduced opacity, the opacity gaps, and provide improved lower limits on the He II Gunn-Peterson opacity tau(He II) in the high-opacity regions. We use the STIS spectrum together with a Keck-HIRES spectrum covering the corresponding H I Lyalpha forest to calculate a onedimensional map of the softness S of the ionization radiation along the line of sight toward HE 2347-4342, where S is the ratio of the H I to He II photoionization rates. We find that S is generally large but presents important variations, from similar to30 in the opacity gaps to a 1 sigma lower limit of 2300 at z similar or equal to 2.86, in a region that shows an extremely low H I opacity over a 6.5 Angstrom spectral range. We note that a large softness parameter naturally accounts for most of the large Si IV/C IV ratios seen in other quasar absorption line spectra. We present a simple model that reproduces the shape of the opacity gaps in absence of large individual absorption lines. We extend the model described in Heap et al. to account for the presence of sources close to the line of sight of the background quasar. As an alternative to the delayed reionization model suggested by Reimers et al., we propose that the large softness observed at z similar or equal to 2.86 is due to the presence of bright soft sources close to the line of sight, i.e., for which the ratio between the number of H I to He II ionizing photons reaching the intergalactic medium is large. We discuss these two models and suggest ways to discriminate between them. C1 NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Natl Opt Astron Observ, Tucson, AZ 85716 USA. Princeton Univ Observ, Princeton, NJ 08544 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. RP Smette, A (reprint author), Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium. RI Jenkins, Edward/P-5684-2014 OI Jenkins, Edward/0000-0003-1892-4423 NR 56 TC 68 Z9 68 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2002 VL 564 IS 2 BP 542 EP 558 DI 10.1086/324397 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 509TZ UT WOS:000173166900003 ER PT J AU de Bernardis, P Ade, PAR Bock, JJ Bond, JR Borrill, J Boscaleri, A Coble, K Contaldi, CR Crill, BP de Troia, G Farese, P Ganga, K Giacometti, M Hivon, E Hristov, VV Iacoangeli, A Jaffe, AH Jones, WC Lange, AE Martinis, L Masi, S Mason, P Mauskopf, PD Melchiorri, A Montroy, T Netterfield, CB Pascale, E Piacentini, F Pogosyan, D Polenta, G Pongetti, F Prunet, S Romeo, G Ruhl, JE Scaramuzzi, F AF de Bernardis, P Ade, PAR Bock, JJ Bond, JR Borrill, J Boscaleri, A Coble, K Contaldi, CR Crill, BP de Troia, G Farese, P Ganga, K Giacometti, M Hivon, E Hristov, VV Iacoangeli, A Jaffe, AH Jones, WC Lange, AE Martinis, L Masi, S Mason, P Mauskopf, PD Melchiorri, A Montroy, T Netterfield, CB Pascale, E Piacentini, F Pogosyan, D Polenta, G Pongetti, F Prunet, S Romeo, G Ruhl, JE Scaramuzzi, F TI Multiple peaks in the angular power spectrum of the cosmic microwave background: Significance and consequences for cosmology SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmological parameters; cosmology : observations ID AMERICAN TEST FLIGHT; RADIATION; UNIVERSE; FLUCTUATIONS; ANISOTROPIES; SUPERNOVAE; BOOMERANG; CLUSTERS; OMEGA AB Three peaks and two dips have been detected in the power spectrum of the cosmic microwave background by the BOOMERANG experiment, at and l = (213(-13)(+10)), (541(-32)(+20)), (845(-25)(+12)) and l = (416(-12)(+22)), (750(-750)(+20)), respectively. Using model-independent analyses, we find that all five features are statistically significant, and we measure their location and amplitude. These are consistent with the adiabatic inflationary model. We also calculate the mean and variance of the peak and dip locations and amplitudes in a large seven-dimensional parameter space of such models, which gives good agreement with the model-independent estimates. We forecast where the next few peaks and dips should be found if the basic paradigm is correct. We test the robustness of our results by comparing Bayesian marginalization techniques on this space with likelihood maximization techniques applied to a second seven-dimensional cosmological parameter space, using an independent computational pipeline, and find excellent agreement: Omega02/tot / (+0.05)(-0.06) versus 1.04 +/- 0.05, Omega(b) h(2) =0.022(-0.003)(+0.004) versus 0.019(-0.004)(+0.005), and n(s) = 0.96(-0.08)(+0.09) versus 0.90 +/- 0.08. The determination of the best fit by the maximization procedure effectively ignores nonzero optical depth of reionization tau(C) > 0, and the difference in primordial spectral index between the two methods is thus a consequence of the strong correlation of n(s) with the tau(C). C1 Univ Roma La Sapienza, Dipartimento Fis, I-00185 Rome, Italy. Univ London Queen Mary & Westfield Coll, London E1 4NS, England. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Univ Toronto, Canadian Inst Theoret Astrophys, Toronto, ON, Canada. LBNL, Natl Energy Res Sci Comp Ctr, Berkeley, CA 94720 USA. CNR, IROE, I-50127 Florence, Italy. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. CALTECH, IPAC, Pasadena, CA 91125 USA. Univ Calif Berkeley, Dept Astron, Space Sci Lab, Berkeley, CA 94720 USA. Univ Calif Berkeley, Ctr Particle Astrophys, Berkeley, CA 94720 USA. ENEA, Frascati, Italy. Cardiff Univ, Dept Phys & Astron, Cardiff CF24 3YB, S Glam, Wales. Univ Oxford, Nucl & Astrophys Lab, Oxford OX 3RH, England. Univ Toronto, Dept Phys, Toronto, ON, Canada. Univ Toronto, Dept Astron, Toronto, ON, Canada. Ist Nazl Geofis, I-00161 Rome, Italy. RP de Bernardis, P (reprint author), Univ Roma La Sapienza, Dipartimento Fis, Piazzale Aldo Moro 2, I-00185 Rome, Italy. RI Jaffe, Andrew/D-3526-2009; OI ROMEO, Giovanni/0000-0002-5535-7803; de Bernardis, Paolo/0000-0001-6547-6446; Masi, Silvia/0000-0001-5105-1439; Polenta, Gianluca/0000-0003-4067-9196; Melchiorri, Alessandro/0000-0001-5326-6003; Piacentini, Francesco/0000-0002-5444-9327; Hivon, Eric/0000-0003-1880-2733 NR 44 TC 248 Z9 250 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2002 VL 564 IS 2 BP 559 EP 566 DI 10.1086/324298 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 509TZ UT WOS:000173166900004 ER PT J AU Bauschlicher, CW AF Bauschlicher, CW TI The infrared spectra of C96H24, C-96H24(+), and C-96H25+ SO ASTROPHYSICAL JOURNAL LA English DT Article DE astrochemistry; ISM : molecules; molecular data ID POLYCYCLIC AROMATIC-HYDROCARBONS; INTERSTELLAR-MEDIUM; MOLECULES; PHOTODESTRUCTION; IONIZATION; EXCHANGE; CATIONS; MODEL; PAHS AB The infrared spectra of C96H24, C96H24+, and C96H25+ have been computed using the B3LYP/4-31G approach. The computed spectra show that the 3.3 mum band is sizable for the cations, being about half that of the neutral. Thus, the observation of a 3.3 mum band does not guarantee the presence of neutral polycyclic aromatic hydrocarbons. These calculations give some insight into the interstellar 6.2 mum band. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 24 TC 49 Z9 49 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2002 VL 564 IS 2 BP 782 EP 786 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 509TZ UT WOS:000173166900022 ER PT J AU Kaplan, DL Fox, DW Kulkarni, SR Gotthelf, EV Vasisht, G Frail, DA AF Kaplan, DL Fox, DW Kulkarni, SR Gotthelf, EV Vasisht, G Frail, DA TI Precise Chandra localization of the soft gamma-ray repeater SGR 1806-20 SO ASTROPHYSICAL JOURNAL LA English DT Article DE astrometry; pulsars : individual (SGR 1806-20); stars : neutron; X-rays : stars ID MAGNETIZED NEUTRON-STARS; INTERSTELLAR DUST; RADIO NEBULA; LIGHT-CURVE; SGR-1806-20; SCATTERING; SGR-1900+14; DISTANCE; SGR1806-20; DISCOVERY AB We present observations of the soft gamma-ray repeater SGR 1806-20 taken with the Chandra X-Ray Observatory. We identify the X-ray counterpart of SGR 1806[20 based on detection of 7.5 s pulsations. Using three unrelated X-ray sources (and USNO stars) as position references, we are able to determine that the SGR is at alpha(2000) = 18(h)08(m)39(8).32 and delta(2000) = -20degrees24'39."5 with rms uncertainty of 0."3 in each coordinate. We find that SGR 1806-20 is located within the 1 sigma error region determined by Interplanetary Network data and is 14" +/- 0."5 distant from the nonthermal core of SNR G10.0-0.3, excluding SGR 1806-20 as the origin of the core. We see evidence of a significant deviation of the spin-down of SGR 1806-20 from its long-term trend, demonstrating erratic spin-down behavior in this source similar to that seen in other SGRs. Finally, we show that there is a broad X-ray halo surrounding SGR 1806-20 out to radii similar to1' due to scattering in the interstellar medium. C1 CALTECH, Dept Astron, Pasadena, CA 91125 USA. Columbia Univ, Columbia Astrophys Lab, New York, NY 10027 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Radio Astron Observ, Socorro, NM 87801 USA. RP Kaplan, DL (reprint author), CALTECH, Dept Astron, 105-24, Pasadena, CA 91125 USA. NR 43 TC 30 Z9 30 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2002 VL 564 IS 2 BP 935 EP 940 DI 10.1086/324339 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 509TZ UT WOS:000173166900037 ER PT J AU Fischer, DA Marcy, GW Butler, RP Laughlin, G Vogt, SS AF Fischer, DA Marcy, GW Butler, RP Laughlin, G Vogt, SS TI A second planet orbiting 47 Ursae Majoris SO ASTROPHYSICAL JOURNAL LA English DT Article DE planetary systems; stars : individual (47 Ursae Majoris) ID MAIN-SEQUENCE STARS; UPSILON-ANDROMEDAE; SYSTEMS; HIPPARCOS; CANDIDATES; STABILITY; DIVERSITY; 51-PEGASI; DISTANCES AB Precise Doppler velocity measurements during 13 yr at Lick Observatory reveal the presence of two planets orbiting the star 47 UMa. The previously detected inner planet is confirmed by the newer velocities that yield a revised orbital period P-b = 1089.0 +/- 2.9 days, M sin i = 2.54 M-J, and eccentricity e(b) = 0.061 +/- 0.014. The residuals to that single-Keplerian fit exhibit a periodicity that is consistent with an additional planetary companion. A simultaneous fit for both planets implies that the outer planet has P-c = 2594 +/- 90 days, a = 3.73 AU, 0 < e(c) < 0.2, and M sin i = 0.76 M-J. Its semimajor axis is the largest yet found for an extrasolar planet, and its angular separation from the host star of 0."26 makes it a good target for direct detection and astrometry. Hipparcos astrometry places limits on the masses of these planets at less than similar to10 MJ, and dynamical modeling places limits on both e(c) and the orbital inclinations. The outer planet induces a velocity semiamplitude of K = 11.1 m s(-1) in the star during its 7 yr orbit, similar to the signal induced on the sun by Jupiter. C1 Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Santa Cruz, Univ Calif Observ, Lick Observ, Santa Cruz, CA 95064 USA. RP Fischer, DA (reprint author), Univ Calif Berkeley, Dept Astron, 601 Campbell Hall, Berkeley, CA 94720 USA. RI Butler, Robert/B-1125-2009; OI Fischer, Debra/0000-0003-2221-0861 NR 43 TC 102 Z9 103 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2002 VL 564 IS 2 BP 1028 EP 1034 DI 10.1086/324336 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 509TZ UT WOS:000173166900047 ER PT J AU Sittler, EC Guhathakurta, M AF Sittler, EC Guhathakurta, M TI Semiempirical two-dimensional magnetohydrodynamic model of the solar corona and interplanetary medium (vol 523, pg 812, 1999) SO ASTROPHYSICAL JOURNAL LA English DT Correction C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. RP Sittler, EC (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 1 TC 8 Z9 8 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2002 VL 564 IS 2 BP 1062 EP 1065 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 509TZ UT WOS:000173166900053 ER PT J AU Schiermeier, JE Kansakar, R Mong, D Ransom, JB Aminpour, MA Stroud, WJ AF Schiermeier, JE Kansakar, R Mong, D Ransom, JB Aminpour, MA Stroud, WJ TI p-Version interface elements in global/local analysis SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article; Proceedings Paper CT 1st International Conference on p and hp Finite Element Methods: Mathematics and Engineering Practice (p-FEM2000) CY MAY 31-JUN 02, 2000 CL WASHINGTON UNIV, ST LOUIS, MISSOURI HO WASHINGTON UNIV DE p-elements; interface elements; non-conforming meshes; global/local analysis AB When performing global/local analysis, the issue of connecting dissimilar meshes often arises, especially when refinement is performed. One method of connecting these dissimilar meshes is to use interface elements. Curve interface elements, to connect dissimilar p-element edges along a curve; surface interface elements, to connect dissimilar p-element faces over a surface; and shell-to-solid transition interface elements, to connect dissimilar p-element edges with p-element faces, have been implemented in MSC.Nastran. The background, theory, and implementation are being presented herein, along with examples. These three interface elements comprise a complete set of interface tools for global/local analysis. Copyright (C) 2001 John Wiley & Sons, Ltd. C1 MSC Software Corp, Los Angeles, CA 90041 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Appl Res Associates Inc, Raleigh, NC 27609 USA. RP Schiermeier, JE (reprint author), MSC Software Corp, 815 Colorado Blvd, Los Angeles, CA 90041 USA. NR 12 TC 5 Z9 5 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0029-5981 J9 INT J NUMER METH ENG JI Int. J. Numer. Methods Eng. PD JAN 10 PY 2002 VL 53 IS 1 BP 181 EP 206 DI 10.1002/nme.398 PG 26 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA 504KV UT WOS:000172856600010 ER PT J AU Panda, J Seasholtz, RG AF Panda, J Seasholtz, RG TI Experimental investigation of density fluctuations in high-speed jets and correlation with generated noise SO JOURNAL OF FLUID MECHANICS LA English DT Article ID RAYLEIGH-SCATTERING; INSTABILITY WAVES; TEMPERATURE; TURBULENCE; LAYER; FIELD; FLOW AB The air density fluctuations in the plumes of fully expanded, unheated free jets were investigated experimentally using a Rayleigh-scattering-based technique. The point measuring technique used a continuous-wave laser, fibre-optic transmission and photon counting electronics. The radial and centreline profiles of time-averaged density and root-mean-square density fluctuation provided a comparative description of jet growth. To measure density fluctuation spectra a two-photomultiplier-tube (PMT) technique was used. Cross-correlation between the two PMT signals significantly reduced the electronic shot noise contribution. The density fluctuation spectra were found to be remarkably similar for all Mach number jets. A detailed survey in fully expanded Mach 0.95, 1.4 and 1.8 jets further confirmed that the distribution of various Strouhal frequency fluctuations remained similar, except for a spatial stretching with increased Mach number. In spite of this similarity in flow fluctuations the noise sources in these three jets were found to be significantly different. Spark schlieren photographs and near-field microphone measurements confirmed that Mach wave radiation was present in the Mach 1.8 jet, and was absent in the Mach 0.95 jet. Direct correlation measurement between the flow density fluctuation (cause) and far-field sound pressure fluctuation (effect) shed further light on the sound generation process. For this purpose a microphone was kept fixed at a far-field point, mostly at a distance of 50 diameters and 30degrees to the flow direction, and the laser probe volume was moved from point to point in the flow. In the Mach 1.8 jet, where the convective velocity of Kelvin-Helmholtz instability waves exceeded the ambient sound speed, significant correlation was measured from the peripheral shear layer, while in the Mach 0.95 jet, where the instability waves had subsonic convective speed, no correlation could be measured. Although the same instability waves were present in both Mach 1.8 and 0.95 jets, the peripheral shear layer of the former was found to be an obvious noise source, while that of the latter was not. Further correlation studies along the jet centreline showed that behaviour in the region downstream of the potential core was similar in all Mach number jets tested, 0.6 less than or equal to M less than or equal to 1.8. Good correlation at low Strouhal frequencies was measured from this region, which started from downstream of the potential core and extended many diameters from there. C1 Ohio Aerosp Inst, Cleveland, OH 44142 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Panda, J (reprint author), Ohio Aerosp Inst, Cleveland, OH 44142 USA. NR 44 TC 60 Z9 60 U1 0 U2 7 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH ST, NEW YORK, NY 10011-4221 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JAN 10 PY 2002 VL 450 BP 97 EP 130 PG 34 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 518LC UT WOS:000173669000004 ER PT J AU Chambers, JE AF Chambers, JE TI Solar system evolution: A new perspective. 2nd edition SO NATURE LA English DT Book Review C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Chambers, JE (reprint author), NASA, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. NR 1 TC 0 Z9 0 U1 0 U2 1 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JAN 10 PY 2002 VL 415 IS 6868 BP 119 EP 119 DI 10.1038/415119a PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 509PR UT WOS:000173159300019 ER PT J AU Chambers, JE AF Chambers, JE TI Higher than Everest: An adventurer's guide to the Solar System SO NATURE LA English DT Book Review C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Chambers, JE (reprint author), NASA, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. NR 1 TC 0 Z9 0 U1 0 U2 1 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JAN 10 PY 2002 VL 415 IS 6868 BP 119 EP 119 DI 10.1038/415119a PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 509PR UT WOS:000173159300018 ER PT J AU Walch, SP AF Walch, SP TI Computed energetics for etching of the Si(100) surface by F and Cl atoms SO SURFACE SCIENCE LA English DT Article DE density functional calculations; models of surface chemical reactions; etching; silicon; halogens; chlorine; single crystal surfaces; solid-gas interfaces ID MOLECULAR-DYNAMICS; FIRST-PRINCIPLES; FLUORINE-ATOMS; STEP EDGES; BASIS-SETS; SILICON; ADSORPTION; CHLORINE; DENSITY; STATES AB Energetics and limited reaction pathways have been computed using density functional theory with the B3LYP functional for the reaction of F and Cl atoms with the Si(100) surface. The energetics are in good agreement with the earlier ab initio calculations of Wu and Carter for the bonding of 1-3 F atoms to a surface dimer. The present energetics are also in good agreement with the results of Srivastava et al. using the Stillinger-Weber potential. We find no barrier for adding a third F atom to a monofluorinated dimer. A significant new result is a low energy pathway to SiF4, which has not been previously characterized. We find that Cl differs from F in having smaller binding energies and much larger non-bonded repulsions. Adding a third Cl to a monochlorinated dimer leads to a barrier of about 0.6 eV (for a symmetry constrained search) and step edge sites are strongly favored in the Cl case, but not in the F case. The energetics obtained for Cl on Si(100) are in good agreement with results obtained by Halicioglu and coworkers using the Feil potential. (C) 2001 Published by Elsevier Science B.V. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Walch, SP (reprint author), NASA, Ames Res Ctr, MS 230-3, Moffett Field, CA 94035 USA. NR 34 TC 13 Z9 13 U1 0 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0039-6028 J9 SURF SCI JI Surf. Sci. PD JAN 10 PY 2002 VL 496 IS 3 BP 271 EP 286 DI 10.1016/S0039-6028(01)01381-4 PG 16 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA 511VK UT WOS:000173286100013 ER PT J AU Ng, HT Foo, ML Fang, AP Li, J Xu, GQ Jaenicke, S Chan, L Li, SFY AF Ng, HT Foo, ML Fang, AP Li, J Xu, GQ Jaenicke, S Chan, L Li, SFY TI Soft-lithography-mediated chemical vapor deposition of architectured carbon nanotube networks on elastomeric polymer SO LANGMUIR LA English DT Letter ID ORDERED STRUCTURES; GROWTH; ARRAYS; MEMBRANES AB The ability to develop highly site-selective and in situ orientation-controlled growth of carbon nanotubes on novel substrates such as elastomeric polymers may provide new opportunities in both fundamental research and practical applications. A soft-lithography-mediated approach has been used in combination with the surface wetting manipulation to selectively immobilize solution-based catalyst precursors for growing highly regular microarrays of multiwalled carbon nanotubes with controlled morphologies on elastomeric poly(dimethylsiloxane) substrates. The thermal shrinking property of poly(dimethylsiloxane) at elevated temperatures allows the possibility of fabricating three-dimensionally complex intertwined networks of carbon nanotubes, which may be utilized as a basic matrix for integration with flexible polymeric frameworks to fabricate flexible nanodevices, such as highly sensitive electrochemical and chemical gas sensors. C1 Inst Mat Res & Engn, Singapore 117602, Singapore. Natl Univ Singapore, Dept Chem, Singapore 117543, Singapore. Chartered Semicond Mfg, Res & Dev, Singapore 738406, Singapore. RP Li, J (reprint author), NASA, Ames Res Ctr, ELORET Corp, Moffett Field, CA 94035 USA. RI Foo, Maw Lin/H-9273-2012; Fang, Aiping/D-1229-2010; Xu, Guo Qin/C-2077-2013; Li, Sam/J-3113-2013; Li, Jun/H-7771-2013 OI Li, Sam/0000-0002-2092-9226; Li, Jun/0000-0002-3689-8946 NR 21 TC 20 Z9 21 U1 0 U2 19 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0743-7463 J9 LANGMUIR JI Langmuir PD JAN 8 PY 2002 VL 18 IS 1 BP 1 EP 5 DI 10.1021/la0108095 PG 5 WC Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 512UD UT WOS:000173341200001 ER PT J AU Cheng, ZD Chaikin, PM Zhu, JX Russel, WB Meyer, WV AF Cheng, ZD Chaikin, PM Zhu, JX Russel, WB Meyer, WV TI Crystallization kinetics of hard spheres in microgravity in the coexistence regime: Interactions between growing crystallites SO PHYSICAL REVIEW LETTERS LA English DT Article ID DYNAMIC LIGHT-SCATTERING; COLLOIDAL SPHERES; DENSITY-FLUCTUATIONS; GLASS-TRANSITION; GROWTH; NUCLEATION; ENTROPY; STATE AB The hard sphere disorder-order transition serves as the paradigm for crystallization. However, measurements of the crystallization kinetics for colloidal hard spheres in the coexistence regime are incomplete for early times and are affected by sedimentation. We use time resolved Bragg light scattering to characterize crystal nucleation and growth in a microgravity environment on the space shuttle. In contrast to the classical picture of the nucleation and growth of isolated crystallites, we find substantial coarsening of growing crystallites. We also observe dendritic growth and face-centered cubic as the stable structure. C1 Princeton Univ, Dept Phys, Princeton, NJ 08540 USA. Princeton Univ, Dept Chem Engn, Princeton, NJ 08540 USA. NASA, Glenn Res Ctr, NCMR, Cleveland, OH 44135 USA. RP Cheng, ZD (reprint author), DiCon Fiberopt Inc, 1689 Regatta Blvd, Richmond, CA 94804 USA. NR 33 TC 49 Z9 50 U1 3 U2 19 PU AMERICAN 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 JAN 7 PY 2002 VL 88 IS 1 AR 015501 DI 10.1103/PhysRevLett.88.015501 PG 4 WC Physics, Multidisciplinary SC Physics GA 509BQ UT WOS:000173124800037 PM 11800960 ER PT B AU Minnis, P Nguyen, L Duda, DP Palikonda, R AF Minnis, P Nguyen, L Duda, DP Palikonda, R GP AMS AMS TI Spreading of isolated contrails during the 2001 air traffic shutdown SO 10TH CONFERENCE ON AVIATION, RANGE, AND AEROSPACE METEOROLOGY LA English DT Proceedings Paper CT 10th Conference on Aviation, Range, and Aerospace Meteorology/13th Conference on Applied Climatology CY MAY 13-16, 2002 CL PORTLAND, OR SP Amer Meteorol Soc, Amer Inst Aeronaut & Astronaut, Atmospher Environm Tech ID CIRRUS C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Minnis, P (reprint author), NASA, Langley Res Ctr, MS 420, Hampton, VA 23681 USA. NR 8 TC 4 Z9 4 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 33 EP 36 PG 4 WC Meteorology & Atmospheric Sciences; Transportation Science & Technology SC Meteorology & Atmospheric Sciences; Transportation GA BX41B UT WOS:000185178800010 ER PT B AU Proctor, FH Hamilton, DW Bowles, RL AF Proctor, FH Hamilton, DW Bowles, RL GP AMS AMS TI Numerical simulation of a convective turbulence encounter SO 10TH CONFERENCE ON AVIATION, RANGE, AND AEROSPACE METEOROLOGY LA English DT Proceedings Paper CT 10th Conference on Aviation, Range, and Aerospace Meteorology/13th Conference on Applied Climatology CY MAY 13-16, 2002 CL PORTLAND, OR SP Amer Meteorol Soc, Amer Inst Aeronaut & Astronaut, Atmospher Environm Tech C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Proctor, FH (reprint author), NASA, Langley Res Ctr, MS 156A, Hampton, VA 23681 USA. NR 13 TC 1 Z9 1 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 41 EP 44 PG 4 WC Meteorology & Atmospheric Sciences; Transportation Science & Technology SC Meteorology & Atmospheric Sciences; Transportation GA BX41B UT WOS:000185178800012 ER PT B AU Smith, WL Minnis, P Bernstein, BC Rapp, AD Heck, PW AF Smith, WL Minnis, P Bernstein, BC Rapp, AD Heck, PW GP AMS AMS TI Supercooled liquid water cloud properties derived from goes: Comparisons with in-situ aircraft measurements SO 10TH CONFERENCE ON AVIATION, RANGE, AND AEROSPACE METEOROLOGY LA English DT Proceedings Paper CT 10th Conference on Aviation, Range, and Aerospace Meteorology/13th Conference on Applied Climatology CY MAY 13-16, 2002 CL PORTLAND, OR SP Amer Meteorol Soc, Amer Inst Aeronaut & Astronaut, Atmospher Environm Tech ID FLIGHT ICING ALGORITHMS C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Smith, WL (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. RI Rapp, Anita/G-8845-2012 NR 17 TC 3 Z9 3 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 89 EP 92 PG 4 WC Meteorology & Atmospheric Sciences; Transportation Science & Technology SC Meteorology & Atmospheric Sciences; Transportation GA BX41B UT WOS:000185178800024 ER PT B AU Roberts, BC Overbey, G Leahy, F Batts, GW AF Roberts, BC Overbey, G Leahy, F Batts, GW GP AMS AMS TI Natural atmospheric environment model developmen for the National Aeronautics and Space Adminstration Second Generation Reusable Launch Vehicle SO 10TH CONFERENCE ON AVIATION, RANGE, AND AEROSPACE METEOROLOGY LA English DT Proceedings Paper CT 10th Conference on Aviation, Range, and Aerospace Meteorology/13th Conference on Applied Climatology CY MAY 13-16, 2002 CL PORTLAND, OR SP Amer Meteorol Soc, Amer Inst Aeronaut & Astronaut, Atmospher Environm Tech C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Roberts, BC (reprint author), NASA, George C Marshall Space Flight Ctr, Mail Code ED44, Huntsville, AL 35812 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 189 EP 190 PG 2 WC Meteorology & Atmospheric Sciences; Transportation Science & Technology SC Meteorology & Atmospheric Sciences; Transportation GA BX41B UT WOS:000185178800051 ER PT B AU Johnson, DL Roberts, BC Vaughan, WW AF Johnson, DL Roberts, BC Vaughan, WW GP AMS AMS TI Reference and standard atmosphere models SO 10TH CONFERENCE ON AVIATION, RANGE, AND AEROSPACE METEOROLOGY LA English DT Proceedings Paper CT 10th Conference on Aviation, Range, and Aerospace Meteorology/13th Conference on Applied Climatology CY MAY 13-16, 2002 CL PORTLAND, OR SP Amer Meteorol Soc, Amer Inst Aeronaut & Astronaut, Atmospher Environm Tech C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Johnson, DL (reprint author), NASA, George C Marshall Space Flight Ctr, Mail Code ED44, Huntsville, AL 35812 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 191 EP 194 PG 4 WC Meteorology & Atmospheric Sciences; Transportation Science & Technology SC Meteorology & Atmospheric Sciences; Transportation GA BX41B UT WOS:000185178800052 ER PT B AU Teets, EH Carter, EJ AF Teets, EH Carter, EJ GP AMS AMS TI Atmospheric conditions of stratospheric mountain waves: Soaring the Perlan aircraft to 30 km SO 10TH CONFERENCE ON AVIATION, RANGE, AND AEROSPACE METEOROLOGY LA English DT Proceedings Paper CT 10th Conference on Aviation, Range, and Aerospace Meteorology/13th Conference on Applied Climatology CY MAY 13-16, 2002 CL PORTLAND, OR SP Amer Meteorol Soc, Amer Inst Aeronaut & Astronaut, Atmospher Environm Tech AB Mountain waves in the troposphere can and do become stratospheric mountain waves under certain meteorological conditions in locations around the world. Analysis shows that these waves will produce vertical wind speeds that will lift a specially designed sailplane potentially to an altitude of 30 km. The meteorological data analysis indicates that the best stratospheric mountain wave conditions required to get to an altitude of either 19 or 30 km in New Zealand are: strong low-level winds in a stable atmosphere (required for initial perturbation by mountains). a gradual wind increase with altitude to supply energy for wave amplification. a weak tropopause that allows for waves to traverse into the stratosphere. high-altitude winds (the polar vortex) in the stratosphere increasing velocity with altitude. The atmospheric conditions and their favored locations and seasons are discussed in this report. C1 NASA, Dryden Flight Res Ctr, Edwards AFB, CA 92523 USA. RP Teets, EH (reprint author), NASA, Dryden Flight Res Ctr, POB 273, Edwards AFB, CA 92523 USA. NR 5 TC 0 Z9 0 U1 0 U2 2 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 195 EP 198 PG 4 WC Meteorology & Atmospheric Sciences; Transportation Science & Technology SC Meteorology & Atmospheric Sciences; Transportation GA BX41B UT WOS:000185178800053 ER PT B AU Hamilton, DW Proctor, FH AF Hamilton, DW Proctor, FH GP AMS AMS TI Convectively induced turbulence encountered during NASNS fall-2000 flight experiments SO 10TH CONFERENCE ON AVIATION, RANGE, AND AEROSPACE METEOROLOGY LA English DT Proceedings Paper CT 10th Conference on Aviation, Range, and Aerospace Meteorology/13th Conference on Applied Climatology CY MAY 13-16, 2002 CL PORTLAND, OR SP Amer Meteorol Soc, Amer Inst Aeronaut & Astronaut, Atmospher Environm Tech C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Hamilton, DW (reprint author), NASA, Langley Res Ctr, MS 156A, Hampton, VA 23681 USA. NR 14 TC 1 Z9 1 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 371 EP 374 PG 4 WC Meteorology & Atmospheric Sciences; Transportation Science & Technology SC Meteorology & Atmospheric Sciences; Transportation GA BX41B UT WOS:000185178800098 ER PT B AU Basdogan, C Lum, M Salcedo, J Chow, E Kupiec, SA Kostrewski, A AF Basdogan, C Lum, M Salcedo, J Chow, E Kupiec, SA Kostrewski, A GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI Autostereoscopic and haptic visualization for space exploration and mission design SO 10TH SYMPOSIUM ON HAPTIC INTERFACES FOR VIRTUAL ENVIRONMENT AND TELEOPERATOR SYSTEMS, PROCEEDINGS LA English DT Proceedings Paper CT 10th Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems (HAPTICS 2002) CY MAR 24-25, 2002 CL ORLANDO, FL SP IEEE Comp Soc AB We have developed a multi-modal virtual environment set-up by fusing visual and haptic images through the use of a new autostereoscopic display and a force-feedback haptic device. Most of the earlier visualization systems that integrate stereo displays and haptic devices have utilized polarized or shutter glasses for stereo vision (see, for example, Veldkamp et al., 1998, Chen et al., 1998, and Brederson et al., 2000). In this paper, we discuss the development stages and components of our set-tip that allows a user to touch, feel, and manipulate virtual objects through a haptic device while seeing them in stereo without using any special eyewear. We also discuss the transformations involved in mapping the absolute coordinates of virtual objects into visual and haptic workspaces and the synchronization of cursor movements in these workspaces. Future applications of this work will include a) multi-modal visualization of planetary data and b) planning of space mission operations in virtual environments. C1 CALTECH, Jet Prop Lab, Virtual Environms Lab, Pasadena, CA 91109 USA. RP Basdogan, C (reprint author), CALTECH, Jet Prop Lab, Virtual Environms Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Basdogan, Cagatay /H-5192-2011 OI Basdogan, Cagatay /0000-0002-6382-7334 NR 10 TC 1 Z9 1 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA BN 0-7695-1489-8 PY 2002 BP 271 EP 276 DI 10.1109/HAPTIC.2002.998968 PG 6 WC Automation & Control Systems; Computer Science, Cybernetics; Computer Science, Interdisciplinary Applications; Instruments & Instrumentation SC Automation & Control Systems; Computer Science; Instruments & Instrumentation GA BU24P UT WOS:000175458900035 ER PT B AU Russell, PB Flatau, PJ Valero, FPJ Nakajima, T Holben, B Pilewskie, P Bergin, M Schmid, B Bergstrom, RW Vogelmann, A Bush, B Redemann, J Pope, S Livingston, J Leitner, S Hsu, NC Wang, J Seinfeld, J Hegg, D Quinn, P Covert, D AF Russell, PB Flatau, PJ Valero, FPJ Nakajima, T Holben, B Pilewskie, P Bergin, M Schmid, B Bergstrom, RW Vogelmann, A Bush, B Redemann, J Pope, S Livingston, J Leitner, S Hsu, NC Wang, J Seinfeld, J Hegg, D Quinn, P Covert, D GP AMS AMS TI Overview of ACE-Asia spring 2001 investigations on aerosol-radiation interactions SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Russell, PB (reprint author), NASA, Ames Res Ctr, MS 245-5, Moffett Field, CA 94035 USA. RI Hsu, N. Christina/H-3420-2013; Flatau, Piotr/E-2219-2011; Quinn, Patricia/R-1493-2016 OI Quinn, Patricia/0000-0003-0337-4895 NR 11 TC 1 Z9 1 U1 0 U2 3 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 1 EP 4 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900001 ER PT B AU Loeb, NG Manalo-Smith, N Loukachine, K Kato, S Wielicki, BA AF Loeb, NG Manalo-Smith, N Loukachine, K Kato, S Wielicki, BA GP AMS AMS TI A new generation of angular distribution models for top-of-atmosphere radiative flux estimation from the clouds and the Earth's Radiant Energy System (CERES) satellite instrument SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc ID MISSION; ERBE; BUDGET C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Loeb, NG (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 9 EP 12 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900003 ER PT B AU Kato, S Loeb, NG AF Kato, S Loeb, NG GP AMS AMS TI Effect of a spherical atmosphere in the irradiance estimate from radiances measured by satellite-based instruments SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Kato, S (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 17 EP 19 PG 3 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900005 ER PT B AU Minnis, P Young, DF Wielicki, BA Kratz, DP Heck, PW Sun-Mack, S Trepte, CZ Chen, Y Gibson, SL Brown, RR AF Minnis, P Young, DF Wielicki, BA Kratz, DP Heck, PW Sun-Mack, S Trepte, CZ Chen, Y Gibson, SL Brown, RR GP AMS AMS TI Seasonal and diurnal variations of cloud properties derived for CERES from VIRS and MODIS data SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc ID REFLECTANCE C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Minnis, P (reprint author), NASA, Langley Res Ctr, MS 420, Hampton, VA 23681 USA. NR 13 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 20 EP 23 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900006 ER PT B AU Young, DF Wielicki, BA Wong, TM Haeffelin, MA Doelling, DR Boghosian, JS AF Young, DF Wielicki, BA Wong, TM Haeffelin, MA Doelling, DR Boghosian, JS GP AMS AMS TI New geostationary-enhanced CERES monthly mean radiative fluxes and cloud properties SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc ID ENERGY SYSTEM CERES C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Young, DF (reprint author), NASA, Langley Res Ctr, MS 420, Hampton, VA 23681 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 24 EP 27 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900007 ER PT B AU Charlock, TP Rose, FG Rutan, D Kratz, DP Jin, ZH Coleman, LH Fu, Q AF Charlock, TP Rose, FG Rutan, D Kratz, DP Jin, ZH Coleman, LH Fu, Q GP AMS AMS TI Relationship of tropical circulation and energetics using retrieved surface and atmospheric radiation budget (SARB) for January-August 1998 SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc ID SATELLITE; CLOUDS; ASSIMILATION; AEROSOLS; SYSTEM C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Charlock, TP (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 28 EP 31 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900008 ER PT B AU Chambers, LH Lin, B Young, DF AF Chambers, LH Lin, B Young, DF GP AMS AMS TI New CERES data examined for evidence of tropical iris feedback SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc ID ENERGY SYSTEM CERES; INFRARED IRIS; EARTH; CLOUDS C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Chambers, LH (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. NR 11 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 32 EP 35 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900009 ER PT B AU Liu, L Mishchenko, MI Menon, S Macke, A Lacis, AA AF Liu, L Mishchenko, MI Menon, S Macke, A Lacis, AA GP AMS AMS TI Estimation of black carbon effect on light scattering and absorption by cloud water droplets SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc ID ALBEDO C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Liu, L (reprint author), NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RI Mishchenko, Michael/D-4426-2012 NR 10 TC 1 Z9 1 U1 0 U2 1 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 36 EP 38 PG 3 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900010 ER PT B AU Varnai, T Marshak, A AF Varnai, T Marshak, A GP AMS AMS TI MODIS observations on the occurrence of 3D radiative effects in clouds SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc ID OPTICAL-THICKNESS C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Varnai, T (reprint author), NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 68 EP 71 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900019 ER PT B AU Mlynczak, M Johnson, D Kratz, D Mertens, C Collins, W Applin, J AF Mlynczak, M Johnson, D Kratz, D Mertens, C Collins, W Applin, J GP AMS AMS TI The far-infrared spectroscopy of the troposphere (FIRST) project SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc ID RADIATIVE PROPERTIES; CIRRUS CLOUDS AB The radiative balance of the Earth is influenced strongly by radiative cooling associated with emission of radiation by water vapor at far-infrared (far-IR) wavelengths greater than 15 mum and extending out beyond 60 mum. The distribution of water vapor and associated far-IR radiative forcings and feedbacks are well-recognized as major uncertainties in understanding and predicting future climate. Up to half of the outgoing longwave radiation (OLR) from the Earth occurs beyond 15.4 mum. Cirrus clouds also modulate the outgoing longwave radiation in the far-IR. Despite this fundamental importance, far-IR emission (spectra or band-integrated) has rarely been directly measured from space, airborne, or ground-based platforms. Current and planned operational and research satellites typically observe the mid-infrared only to about 15.4 mum. The Far-Infrared Spectroscopy of the Troposphere (FIRST) project is an investment by NASA through the Instrument Incubator Program (IIP) to develop a space-based capability to measure the spectrally resolved infrared spectrum to 100 mum. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Mlynczak, M (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. NR 13 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 90 EP 93 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900025 ER PT B AU Loeb, NG Kato, S AF Loeb, NG Kato, S GP AMS AMS TI Top-of-atmosphere direct radiative effect of aerosols from the clouds and the earth's radiant energy system (CERES) satellite instrument over the tropical oceans SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Loeb, NG (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 103 EP 104 PG 2 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900029 ER PT B AU Ferrare, R Brasseur, L Clayton, M Turner, D Remer, L Gao, BC AF Ferrare, R Brasseur, L Clayton, M Turner, D Remer, L Gao, BC GP AMS AMS TI Evaluation of terra aerosol and water vapor measurements using ARM SGP data SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc ID OPTICAL DEPTH C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Ferrare, R (reprint author), NASA, Langley Res Ctr, Mail Stop 401A, Hampton, VA 23681 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 130 EP 133 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900037 ER PT B AU Hunt, LA Seals, RK Ritchey, NA AF Hunt, LA Seals, RK Ritchey, NA GP AMS AMS TI Radiation, cloud and aerosol data from the multi-angle imaging spectroradiometer (MISR) instrument SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc C1 NASA, Langley Res Ctr, Atmospher Sci Data Ctr, Sci User & Data Serv, Hampton, VA 23681 USA. RP Hunt, LA (reprint author), NASA, Langley Res Ctr, Atmospher Sci Data Ctr, Sci User & Data Serv, MS 157D,2 S Wright St, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 134 EP 135 PG 2 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900038 ER PT B AU Wen, GY Cahalan, RF Holben, BN AF Wen, GY Cahalan, RF Holben, BN GP AMS AMS TI Solstice observed and Cimel estimated exo-atmospheric atmospheric solar irradiance SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc ID COMPARISON EXPERIMENT-1; OPTICAL-DEPTH; CONSTANT; AERONET; MISSION C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Wen, GY (reprint author), NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. RI Cahalan, Robert/E-3462-2012 OI Cahalan, Robert/0000-0001-9724-1270 NR 18 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 136 EP 139 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900039 ER PT B AU Chen, Y Sun-Mack, S Trepte, QZ Minnis, P Young, DF AF Chen, Y Sun-Mack, S Trepte, QZ Minnis, P Young, DF GP AMS AMS TI Solar zenith angle variation of clear-sky narrowband albedos derived from VIRS and MODIS SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Minnis, P (reprint author), NASA, Langley Res Ctr, MS 420, Hampton, VA 23681 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 152 EP 155 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900043 ER PT B AU Lin, B Rose, F Wielicki, B AF Lin, B Rose, F Wielicki, B GP AMS AMS TI Estimation of longwave radiation at sea surface using combined VIRS and TMI retrieved cloud properties SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc ID VISIBLE MEASUREMENTS; SATELLITE MICROWAVE; FLUXES C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Lin, B (reprint author), NASA, Langley Res Ctr, MS 420, Hampton, VA 23681 USA. EM b.lin@larc.nasa.gov NR 10 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 168 EP 170 PG 3 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900047 ER PT B AU Wong, TM Young, DF Wielicki, BA AF Wong, TM Young, DF Wielicki, BA GP AMS AMS TI First year of CERES/Terra ERBE-like global radiation budget observations SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Wong, TM (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 171 EP 174 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900048 ER PT B AU Bush, KA Smith, GL Lee, RB Wong, TM Young, DF AF Bush, KA Smith, GL Lee, RB Wong, TM Young, DF GP AMS AMS TI The earth radiation budget 15-year data set SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc C1 Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Smith, GL (reprint author), Langley Res Ctr, Div Atmospher Sci, Mail Stop 420, Hampton, VA 23681 USA. NR 18 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 175 EP 178 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900049 ER PT B AU Hunt, LA Seals, RK Sorlie, SE AF Hunt, LA Seals, RK Sorlie, SE GP AMS AMS TI Clouds and the Earth's Radiant Energy System (CERES) data sets and tools SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc C1 NASA, Langley Res Ctr,Sci Applicat Int Corp, Atmospher Sci Data Ctr, Sci User Serv, Hampton, VA 23681 USA. RP Hunt, LA (reprint author), NASA, Langley Res Ctr,Sci Applicat Int Corp, Atmospher Sci Data Ctr, Sci User Serv, MS 157D,2 S Wright St, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 179 EP 180 PG 2 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900050 ER PT B AU Stackhouse, PW Gupta, SK Cox, SJ Mikovitz, JC Chiacchio, M AF Stackhouse, PW Gupta, SK Cox, SJ Mikovitz, JC Chiacchio, M GP AMS AMS TI New results from the NASA/GEWEX surface radiation budget project: Evaluating El Nino effects at different scales SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Stackhouse, PW (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, MS 420, Hampton, VA 23681 USA. NR 5 TC 1 Z9 1 U1 1 U2 1 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 199 EP 202 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900056 ER PT B AU Rose, FG Charlock, TP AF Rose, FG Charlock, TP GP AMS AMS TI New Fu-Liou code tested with ARM Raman lidar aerosols and CERES in pre-CALIPSO sensitivity study SO 11TH CONFERENCE ON ATMOSPHERIC RADIATION LA English DT Proceedings Paper CT 11th Conference on Atmospheric Radiation CY JUN 03-07, 2002 CL OGDEN, UT SP Amer Meteorol Soc ID RADIATIVE PROPERTIES; CLOUDS C1 Analyt Serv & Mat Inc, Hampton, VA 23666 USA. NASA, Langley Res Ctr, Atmospher Sci Competency, Hampton, VA 23665 USA. RP Rose, FG (reprint author), Analyt Serv & Mat Inc, 1 Enterprise Pkwy,Suite 300, Hampton, VA 23666 USA. NR 12 TC 0 Z9 0 U1 0 U2 1 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 215 EP 218 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing GA BX57X UT WOS:000185754900061 ER PT B AU Matthews, G Hood, R Johnson, S Leggett, P AF Matthews, G Hood, R Johnson, S Leggett, P GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI Backtracking and re-execution in the automatic debugging of parallelized programs SO 11TH IEEE INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE DISTRIBUTED COMPUTING, PROCEEDINGS LA English DT Proceedings Paper CT 11th IEEE International Symposium on High Performance Distributed Computing (HPDC-11) CY JUL 24-26, 2002 CL EDINBURGH, SCOTLAND SP IEEE Tech Comm Distributed Processing AB In this work we describe a new approach using relative debugging to find differences in computation between a serial program and a parallel version of that program. We use a combination of re-execution and backtracking in order to find the first difference in computation that may ultimately lead to an incorrect value that the user has indicated In our prototype implementation we use static analysis information from a parallelization tool in order to perform the backtracking as well as the mapping required between serial and parallel computations. C1 NASA, Ames Res Ctr, Comp Sci Corp, Adv Supercomp Div, Moffett Field, CA 94035 USA. RP Matthews, G (reprint author), NASA, Ames Res Ctr, Comp Sci Corp, Adv Supercomp Div, Moffett Field, CA 94035 USA. NR 12 TC 0 Z9 0 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA BN 0-7695-1686-6 PY 2002 BP 150 EP 160 DI 10.1109/HPDC.2002.1029913 PG 11 WC Computer Science, Theory & Methods SC Computer Science GA BU96F UT WOS:000177508900016 ER PT B AU Bettencourt, MT AF Bettencourt, MT GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI Distributed model coupling framework SO 11TH IEEE INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE DISTRIBUTED COMPUTING, PROCEEDINGS LA English DT Proceedings Paper CT 11th IEEE International Symposium on High Performance Distributed Computing (HPDC-11) CY JUL 24-26, 2002 CL EDINBURGH, SCOTLAND SP IEEE Tech Comm Distributed Processing ID EQUATIONS AB An implementation of a distributed model coupling framework is documented. This framework provides the infrastructure for a data-flow approach for solving the problem of distributed numerical models sharing coupling information. There exists a centralized server which stores coupling information such as surface fluxes. This information is then passed to client applications (numerical models) through a series of filters. These filters are used to transform the information into a ready-to-use form by the model and are specific to the coupling process being performed. CORBA is used for all the communication between processes. Results are given for two test cases, a strong tropical event and a rip current calculation over a barred beach. Results for the rip current example are compared to the traditional approach of file based coupling approach showing a 50% decrease in execution time with equivalent results. C1 Ctr Higher Learning, Stennis Space Ctr, Stennis Space Ctr, MS 39529 USA. RP Bettencourt, MT (reprint author), Ctr Higher Learning, Stennis Space Ctr, Bldg 1103,Rm 103, Stennis Space Ctr, MS 39529 USA. RI bettencourt, matthew/I-5924-2014 NR 16 TC 6 Z9 6 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA BN 0-7695-1686-6 PY 2002 BP 284 EP 290 DI 10.1109/HPDC.2002.1029928 PG 7 WC Computer Science, Theory & Methods SC Computer Science GA BU96F UT WOS:000177508900030 ER PT B AU Chen, BD Chao, WC Liu, XD AF Chen, BD Chao, WC Liu, XD GP AMS AMS TI Enhanced climatic warming over the Tibetan Plateau due to doubling CO2: A model study SO 13TH SYMPOSIUM ON GLOBAL CHANGE AND CLIMATE VARIATIONS LA English DT Proceedings Paper CT 13th Symposium on Global Change and Climate Variations CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, GEST Ctr, Greenbelt, MD 20771 USA. RP Chen, BD (reprint author), NASA, Goddard Space Flight Ctr, GEST Ctr, Code 913, Greenbelt, MD 20771 USA. NR 4 TC 0 Z9 0 U1 0 U2 1 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 48 EP 49 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV58M UT WOS:000179447900018 ER PT B AU Serafino, GN Ahmad, SP AF Serafino, GN Ahmad, SP GP AMS AMS TI Climate data at NASA Goddard Earth Sciences DAAC SO 13TH SYMPOSIUM ON GLOBAL CHANGE AND CLIMATE VARIATIONS LA English DT Proceedings Paper CT 13th Symposium on Global Change and Climate Variations CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Serafino, GN (reprint author), NASA, Goddard Space Flight Ctr, Code 902, Greenbelt, MD 20771 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 123 EP 126 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV58M UT WOS:000179447900046 ER PT B AU Haberer, S Ritchey, N Morris, KL AF Haberer, S Ritchey, N Morris, KL GP AMS AMS TI ISCCP data available for climate variability research SO 13TH SYMPOSIUM ON GLOBAL CHANGE AND CLIMATE VARIATIONS LA English DT Proceedings Paper CT 13th Symposium on Global Change and Climate Variations CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 NASA, Langley Res Ctr, Atmospher Sci Data Ctr, Hampton, VA 23681 USA. RP Haberer, S (reprint author), NASA, Langley Res Ctr, Atmospher Sci Data Ctr, MS 157D, Hampton, VA 23681 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 133 EP 134 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV58M UT WOS:000179447900049 ER PT B AU Ahmad, SP King, MD Koziana, JV Leptoukh, GG Serafino, GN Sharma, AK AF Ahmad, SP King, MD Koziana, JV Leptoukh, GG Serafino, GN Sharma, AK GP AMS AMS TI Modis cloud, aerosol, and water vapor products for climate and global change studies SO 13TH SYMPOSIUM ON GLOBAL CHANGE AND CLIMATE VARIATIONS LA English DT Proceedings Paper CT 13th Symposium on Global Change and Climate Variations CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc ID RESOLUTION IMAGING SPECTRORADIOMETER C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ahmad, SP (reprint author), NASA, Goddard Space Flight Ctr, Code 902, Greenbelt, MD 20771 USA. NR 11 TC 0 Z9 0 U1 0 U2 2 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 135 EP 139 PG 5 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV58M UT WOS:000179447900050 ER PT B AU Xu, KM Wong, T Parker, L Wielicki, BA Randall, DA Branson, M Wang, DH Barkstrom, B AF Xu, KM Wong, T Parker, L Wielicki, BA Randall, DA Branson, M Wang, DH Barkstrom, B GP AMS AMS TI Study of large ensemble of cloud systems from EOS satellite observations for cloud model evaluation SO 13TH SYMPOSIUM ON GLOBAL CHANGE AND CLIMATE VARIATIONS LA English DT Proceedings Paper CT 13th Symposium on Global Change and Climate Variations CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Wong, T (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. RI Xu, Kuan-Man/B-7557-2013 OI Xu, Kuan-Man/0000-0001-7851-2629 NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 162 EP 164 PG 3 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV58M UT WOS:000179447900059 ER PT B AU Lin, B Wielicki, BA Chambers, LH Hu, YX Xu, KM AF Lin, B Wielicki, BA Chambers, LH Hu, YX Xu, KM GP AMS AMS TI Radiative forcing of the tropical anvil clouds SO 13TH SYMPOSIUM ON GLOBAL CHANGE AND CLIMATE VARIATIONS LA English DT Proceedings Paper CT 13th Symposium on Global Change and Climate Variations CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc ID EARTH C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Lin, B (reprint author), NASA, Langley Res Ctr, MS 420, Hampton, VA 23681 USA. EM b.lin@larc.nasa.gov RI Hu, Yongxiang/K-4426-2012; Xu, Kuan-Man/B-7557-2013 OI Xu, Kuan-Man/0000-0001-7851-2629 NR 5 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 168 EP 169 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV58M UT WOS:000179447900061 ER PT B AU Chao, WC Chen, BD AF Chao, WC Chen, BD GP AMS AMS TI The origin of monsoons SO 13TH SYMPOSIUM ON GLOBAL CHANGE AND CLIMATE VARIATIONS LA English DT Proceedings Paper CT 13th Symposium on Global Change and Climate Variations CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Chao, WC (reprint author), NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. NR 2 TC 0 Z9 0 U1 6 U2 7 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 175 EP 175 PG 1 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV58M UT WOS:000179447900064 ER PT B AU Schlosser, CA Kirtman, BP AF Schlosser, CA Kirtman, BP GP AMS AMS TI Predictable skill and its associated sea-surface temperature variability in an ensemble climate simulation SO 13TH SYMPOSIUM ON GLOBAL CHANGE AND CLIMATE VARIATIONS LA English DT Proceedings Paper CT 13th Symposium on Global Change and Climate Variations CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, UMBC, GEST, Greenbelt, MD 20771 USA. RP Schlosser, CA (reprint author), NASA, Goddard Space Flight Ctr, UMBC, GEST, Code 974, Greenbelt, MD 20771 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 223 EP 224 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV58M UT WOS:000179447900085 ER PT B AU Liu, Z Chiu, L Teng, W Rui, H Serafino, G AF Liu, Z Chiu, L Teng, W Rui, H Serafino, G GP AMS TI TRMM rainfall products and tools for tropical infectious disease studies SO 15TH CONFERENCE ON BIOMETEOROLOGY AND AEROBIOLOGY JOINT WITH THE 16TH INTERNATIONAL CONGRESS ON BIOMETEOROLOGY LA English DT Proceedings Paper CT 15th Conference on Biometeorology and Aerobiology/16th International Congress on Biometeorology CY OCT 28-NOV 01, 2002 CL KANSAS CITY, MO SP Int Soc Biometeorol, Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, GMU, DAAC,Earth Sci Data & Informat Serv Ctr, Greenbelt, MD 20771 USA. RP Liu, Z (reprint author), NASA, Goddard Space Flight Ctr, GMU, DAAC,Earth Sci Data & Informat Serv Ctr, Code 902, Greenbelt, MD 20771 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 19 EP 23 PG 5 WC Biophysics; Ecology; Meteorology & Atmospheric Sciences SC Biophysics; Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA BY35Z UT WOS:000189043800006 ER PT B AU Cheng, AN Xu, KM AF Cheng, AN Xu, KM GP AMS AMS TI Turbulence closure and cloud dynamics in cloud-resolving simulations of boundary-layer cloud regimes SO 15TH SYMPOSIUM ON BOUNDARY LAYERS AND TURBULENCE LA English DT Proceedings Paper CT 15th Symposium on Boundary Layers and Turbulence CY JUL 15-19, 2002 CL WAGENINGEN, NETHERLANDS SP Amer Meteorol Soc, Wageningen Univ, Dept Meteorol & Air Qual ID PARAMETERIZATION; MODEL C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Cheng, AN (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. RI Xu, Kuan-Man/B-7557-2013 OI Xu, Kuan-Man/0000-0001-7851-2629 NR 11 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 92 EP 95 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BX63B UT WOS:000185937700026 ER PT B AU Tang, WQ Liu, WT AF Tang, WQ Liu, WT GP AMS AMS TI Moisture advection and fresh water flux over oceans SO 16TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 16th Conference on Hydrology CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Tang, WQ (reprint author), CALTECH, Jet Prop Lab, MS 300-323, Pasadena, CA 91109 USA. NR 7 TC 1 Z9 1 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 24 EP 28 PG 5 WC Meteorology & Atmospheric Sciences; Remote Sensing; Water Resources SC Meteorology & Atmospheric Sciences; Remote Sensing; Water Resources GA BV55F UT WOS:000179336300008 ER PT B AU Jedlovec, GJ Meyer, PJ Guillory, AR Stellman, K Limaye, A AF Jedlovec, GJ Meyer, PJ Guillory, AR Stellman, K Limaye, A GP AMS AMS TI Intercomparison of CHARM data and WSR-88D storm integrated rainfall SO 16TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 16th Conference on Hydrology CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 NASA, Global Hydrol & Climate Ctr, MSFC, Huntsville, AL 35805 USA. RP Jedlovec, GJ (reprint author), NASA, Global Hydrol & Climate Ctr, MSFC, 320 Sparkman Dr, Huntsville, AL 35805 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 109 EP 112 PG 4 WC Meteorology & Atmospheric Sciences; Remote Sensing; Water Resources SC Meteorology & Atmospheric Sciences; Remote Sensing; Water Resources GA BV55F UT WOS:000179336300029 ER PT B AU Smith, GL AF Smith, GL GP AMS AMS TI Randomness of radiances from broken cloud fields SO 16TH CONFERENCE ON PROBABILITY AND STATISTICS IN THE ATMOSPHERIC SCIENCES LA English DT Proceedings Paper CT 16th Conference on Probability and Statistics in the Atmospheric Sciences CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 Virginia Polytech Inst & State Univ, NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Smith, GL (reprint author), Virginia Polytech Inst & State Univ, NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 61 EP 64 PG 4 WC Meteorology & Atmospheric Sciences; Statistics & Probability SC Meteorology & Atmospheric Sciences; Mathematics GA BV55E UT WOS:000179335800011 ER PT B AU Wong, T Smith, GL AF Wong, T Smith, GL GP AMS AMS TI Temporal spectra of Earth radiation budget components SO 16TH CONFERENCE ON PROBABILITY AND STATISTICS IN THE ATMOSPHERIC SCIENCES LA English DT Proceedings Paper CT 16th Conference on Probability and Statistics in the Atmospheric Sciences CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Wong, T (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, Mail Stop 420, Hampton, VA 23681 USA. NR 3 TC 1 Z9 1 U1 0 U2 2 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 66 EP 69 PG 4 WC Meteorology & Atmospheric Sciences; Statistics & Probability SC Meteorology & Atmospheric Sciences; Mathematics GA BV55E UT WOS:000179335800013 ER PT B AU Olson, J Rowe, K Wang, F AF Olson, J Rowe, K Wang, F GP AMS AMS TI Extracting the maximum from geographic metadata at the NASA Langley ASDC SO 18TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY, AND HYDROLOGY LA English DT Proceedings Paper CT 18th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography and Hydrology CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 NASA, Langley Res Ctr, Atmospher Sci Data Ctr, Hampton, VA 23665 USA. RP Olson, J (reprint author), NASA, Langley Res Ctr, Atmospher Sci Data Ctr, Hampton, VA 23665 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 27 EP 27 PG 1 WC Computer Science, Information Systems; Computer Science, Software Engineering; Meteorology & Atmospheric Sciences SC Computer Science; Meteorology & Atmospheric Sciences GA BV55B UT WOS:000179335200010 ER PT B AU Ouzounov, D Ahmad, S Eaton, P Koziana, J Leptoukh, G Savtchenko, A Serafino, G Sharma, AK Skider, M Qu, J Zhou, B AF Ouzounov, D Ahmad, S Eaton, P Koziana, J Leptoukh, G Savtchenko, A Serafino, G Sharma, AK Skider, M Qu, J Zhou, B GP AMS AMS TI GES DAAC improved methods and tools for accessing MODIS data SO 18TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY, AND HYDROLOGY LA English DT Proceedings Paper CT 18th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography and Hydrology CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, SSAI, Greenbelt, MD 20771 USA. RP Ouzounov, D (reprint author), NASA, Goddard Space Flight Ctr, SSAI, Mailstop 902, Greenbelt, MD 20771 USA. RI Ouzounov, Dimitar/A-5929-2012 NR 3 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 28 EP 29 PG 2 WC Computer Science, Information Systems; Computer Science, Software Engineering; Meteorology & Atmospheric Sciences SC Computer Science; Meteorology & Atmospheric Sciences GA BV55B UT WOS:000179335200011 ER PT B AU Liu, Z Chiu, L Rui, H Teng, W Serafino, G AF Liu, Z Chiu, L Rui, H Teng, W Serafino, G GP AMS AMS TI Online analysis and visualization of TRMM and other precipitation data sets SO 18TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY, AND HYDROLOGY LA English DT Proceedings Paper CT 18th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography and Hydrology CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc ID AIR-TEMPERATURE; SPATIAL VARIABILITY; INTERPOLATION C1 NASA, Goddard Space Flight Ctr, GMU, DAAC, Greenbelt, MD 20771 USA. RP Liu, Z (reprint author), NASA, Goddard Space Flight Ctr, GMU, DAAC, Code 902, Greenbelt, MD 20771 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 75 EP 77 PG 3 WC Computer Science, Information Systems; Computer Science, Software Engineering; Meteorology & Atmospheric Sciences SC Computer Science; Meteorology & Atmospheric Sciences GA BV55B UT WOS:000179335200032 ER PT B AU Ahmad, SP Salomonson, VV Barnes, WL Xiong, X Leptoukh, GG Serafino, GN AF Ahmad, SP Salomonson, VV Barnes, WL Xiong, X Leptoukh, GG Serafino, GN GP AMS AMS TI MODIS radiances and reflectances for earth system science studies and environmental applications SO 18TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY, AND HYDROLOGY LA English DT Proceedings Paper CT 18th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography and Hydrology CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc ID IMAGING SPECTRORADIOMETER MODIS; EOS-AM1 C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ahmad, SP (reprint author), NASA, Goddard Space Flight Ctr, Code 902, Greenbelt, MD 20771 USA. RI Xiong, Xiaoxiong (Jack)/J-9869-2012 NR 8 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 188 EP 192 PG 5 WC Computer Science, Information Systems; Computer Science, Software Engineering; Meteorology & Atmospheric Sciences SC Computer Science; Meteorology & Atmospheric Sciences GA BV55B UT WOS:000179335200072 ER PT B AU Bess, TD Wong, T AF Bess, TD Wong, T GP AMS AMS TI One year of daily averaged longwave radiation measurements for environmental and climate change studies SO 18TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY, AND HYDROLOGY LA English DT Proceedings Paper CT 18th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography and Hydrology CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc ID BUDGET EXPERIMENT AB One year of daily averaged scanner outgoing longwave radiation (OLR) 2.5 degree region measurements from the Clouds and the Earth's Radiant Energy System (CERES) instrument is made available on the Internet/Web for use by the scientific and educational community. This year. of daily averaged data is from scanner measurements taken by the CERES instrument on the Terra satellite which is in a sun-synchronous orbit with an equator crossing time of about 10:40 AM. The data set spans the period from March 2000 through February 2001 and can be viewed and accessed using a web browser located on a server at NASA, Langley Research Center. The browser uses a live access server (LAS) developed by the Thermal Modeling and Analysis Prtoject at NOAA's Pacific Marine Environmental Laboratory. LAS allows researchers to interact directly with the data to view, select, and subset the data in terms of month, year, latitude, and longitude. In addition to daily OLR measurements, monthly, average and variation over the month will be included on LAS. C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Bess, TD (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, MS-420, Hampton, VA 23681 USA. NR 6 TC 0 Z9 0 U1 0 U2 1 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 193 EP 195 PG 3 WC Computer Science, Information Systems; Computer Science, Software Engineering; Meteorology & Atmospheric Sciences SC Computer Science; Meteorology & Atmospheric Sciences GA BV55B UT WOS:000179335200073 ER PT B AU Kavaya, MJ Emmitt, GD AF Kavaya, MJ Emmitt, GD GP AMS AMS TI Characteristics and trade-offs of Doppler Lidar global wind profiling SO 18TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY, AND HYDROLOGY LA English DT Proceedings Paper CT 18th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography and Hydrology CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Kavaya, MJ (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 215 EP 217 PG 3 WC Computer Science, Information Systems; Computer Science, Software Engineering; Meteorology & Atmospheric Sciences SC Computer Science; Meteorology & Atmospheric Sciences GA BV55B UT WOS:000179335200082 ER PT B AU Liu, Z Chiu, L Teng, W Serafino, G Yang, R AF Liu, Z Chiu, L Teng, W Serafino, G Yang, R GP AMS AMS TI Examples of climate applications of TRMM data SO 18TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY, AND HYDROLOGY LA English DT Proceedings Paper CT 18th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography and Hydrology CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, DAAC, GMU,Earth Sci Data & Informat Sci Ctr, Greenbelt, MD 20771 USA. RP Liu, Z (reprint author), NASA, Goddard Space Flight Ctr, DAAC, GMU,Earth Sci Data & Informat Sci Ctr, Greenbelt, MD 20771 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 222 EP 224 PG 3 WC Computer Science, Information Systems; Computer Science, Software Engineering; Meteorology & Atmospheric Sciences SC Computer Science; Meteorology & Atmospheric Sciences GA BV55B UT WOS:000179335200085 ER PT B AU Rui, HL Teng, B Chiu, L Serafino, G Hrubiak, P Bonk, J AF Rui, HL Teng, B Chiu, L Serafino, G Hrubiak, P Bonk, J GP AMS AMS TI Statistics of TRMM data archive and distribution at the GES DAAC SO 18TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY, AND HYDROLOGY LA English DT Proceedings Paper CT 18th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography and Hydrology CY JAN 13-17, 2002 CL ORLANDO, FL SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, DAAC, DISC,GSFC Earth Sci,GES, Greenbelt, MD 20771 USA. RP Rui, HL (reprint author), NASA, Goddard Space Flight Ctr, DAAC, DISC,GSFC Earth Sci,GES, Greenbelt, MD 20771 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2002 BP 225 EP 227 PG 3 WC Computer Science, Information Systems; Computer Science, Software Engineering; Meteorology & Atmospheric Sciences SC Computer Science; Meteorology & Atmospheric Sciences GA BV55B UT WOS:000179335200086 ER EF