FN Thomson Reuters Web of Science™ VR 1.0 PT J AU Vennes, S Lanz, T AF Vennes, S Lanz, T TI A comparative study of the atmospheric composition of the DA white dwarfs Feige 24 and G191-B2B SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : abundances; stars : individual (Feige 24, G191-B2B); ultraviolet : stars; white dwarfs ID BLANKETED MODEL ATMOSPHERES; RADIATIVE LEVITATION; TEMPERATURE SCALE; MASS-DISTRIBUTION; BINARY FEIGE-24; HEAVY-ELEMENTS; HOT STARS; ULTRAVIOLET; ABUNDANCES; SPECTROGRAPH AB We analyze Hubble Space Telescope Imaging Spectrograph spectra of two white dwarfs, Feige 24 and G191-B2B, and we compare the measured abundance patterns. Except for carbon, which appears overabundant in G191-B2B by 0.3-0.5 dex relative to Feige 24, the average heavy-element abundance in Feige 24 is 0.17 dex larger than in the cooler, hence older, G191-B2B, indicating a slow but perceptible decline of metallicity with time. We also found that the C IV lambda 1550 doublet in G191-B2B is composed of a photospheric component and a second component, either interstellar or circumstellar, separated by only Delta upsilon = 15 km s(-1). We find a simple correspondence between the measured element abundance, its solar abundance value, and its atomic weight from which we deduce the likely presence of additional elements such as neon and magnesium in the photospheres of Feige 24 and G191-B2B. C1 Australian Natl Univ, Dept Math, Canberra, ACT 0200, Australia. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Vennes, S (reprint author), Australian Natl Univ, Dept Math, Canberra, ACT 0200, Australia. EM vennes@maths.anu.edu.au RI Vennes, Stephane/G-9903-2014 NR 29 TC 20 Z9 20 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2001 VL 553 IS 1 BP 399 EP 404 DI 10.1086/320653 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 442JA UT WOS:000169280400036 ER PT J AU Kastner, SO Bhatia, AK AF Kastner, SO Bhatia, AK TI Optically thin and thick Fe xv spectrum: Effect of self-absorption on the 284.16 angstrom resonance line SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic data; Sun : UV radiation ID EXTREME-ULTRAVIOLET-SPECTRA; ELECTRON-IMPACT EXCITATION; MG-LIKE IONS; EXTENDED ANALYSIS; SOLAR-FLARES; TRANSITIONS; IDENTIFICATIONS; INTENSITIES; SEQUENCE; COMPLEX AB Level populations and line intensity ratios are calculated in a 35 level model of Fe xv using most recently available atomic data and incorporating the effects of self-absorption through escape probability factors for slab and cylindrical sources. The computed optically thin spectrum is found to agree very well with solar active region observations, confirming the correctness of the atomic data. Under optically thick conditions, a different situation is found compared to the Fe XVII spectrum; all Fe xv subordinate lines and their intensity ratios are unaffected. At the same time the 284.16 Angstrom resonance line exhibits the counterintuitive effect of initial intensity increase with column density even more strongly than do Fe XVII resonance lines. A preliminary comparison is made with the available observations, which are found to be consistent with the present predictions. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. NR 27 TC 12 Z9 12 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 MAY 20 PY 2001 VL 553 IS 1 BP 421 EP 428 DI 10.1086/320649 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 442JA UT WOS:000169280400039 ER PT J AU Chu, YH Guerrero, MA Gruendl, RA Williams, RM Kaler, JB AF Chu, YH Guerrero, MA Gruendl, RA Williams, RM Kaler, JB TI Chandra reveals the X-ray glint in the cat's eye SO ASTROPHYSICAL JOURNAL LA English DT Article DE planetary nebulae : general; planetary nebulae : individual (NGC 6543); stars : winds, outflows; X-rays : ISM ID PLANETARY-NEBULAE; CENTRAL STARS; NGC-6543; ABUNDANCES; EMISSION; WIND; EVOLUTION; NGC-6826 AB We have obtained Chandra ACIS-S observations of NGC 6543, the Cat's Eye Nebula. The X-ray emission from NGC 6543 is clearly resolved into a point source at the central star and diffuse emission confined within the central elliptical shell and two extensions along the major axis. Spectral analysis of the diffuse component shows that the abundances of the X-ray-emitting gas are similar to those of the fast (1750 km s(-1)) stellar wind but not those of the nebula. Furthermore, the temperature of this gas is similar to1.7 x 10(6) K, which is 100 times lower than the expected postshock temperature of the fast stellar wind. The combination of low temperature and wind abundances is puzzling. The thermal pressure of this hot gas is about twice the pressure in the cool nebular shell; thus, the hot gas plays an essential role in the ongoing evolution of the nebula. C1 Univ Illinois, Dept Astron, Urbana, IL 61801 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Chu, YH (reprint author), Univ Illinois, Dept Astron, 1002 W Green St, Urbana, IL 61801 USA. OI Guerrero, Martin/0000-0002-7759-106X NR 21 TC 60 Z9 60 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 MAY 20 PY 2001 VL 553 IS 1 BP L69 EP L72 DI 10.1086/320495 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 442JB UT WOS:000169280500017 ER PT J AU Dawson, KS Holzapfel, WL Carlstrom, JE Joy, M LaRoque, SJ Reese, ED AF Dawson, KS Holzapfel, WL Carlstrom, JE Joy, M LaRoque, SJ Reese, ED TI A preliminary detection of arcminute-scale cosmic microwave background anisotropy with the BIMA array SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations ID RADIO-SOURCES; 28.5 GHZ AB We have used the Berkeley-Illinois-Maryland Association (BIMA) array outfitted with low-noise millimeterwave receivers to expand our search for arcminute-scale anisotropy of the cosmic microwave background (CMB). The interferometer was placed in a compact configuration for sensitivity on arcminute scales over its 6.'6 FWHM held of view. This experiment is most sensitive to hat band power described by an average multipole of l = 5530, corresponding to an angular scale of similar to2'. We present the analysis of 11 independent fields that were selected based on their low contrast in infrared dust emission and lack of bright radio sources. Applying a Bayesian analysis to the visibility data, we find CMB anisotropy flat band power Q(flat) = 6.1(-4.8)(+2.8), muK at 68% confidence. The measured signal exceeds that expected from instrument noise with 76% confidence, and we find an upper limit of Q(flat) < 12.4 K at 95% confidence. We have supplemented our BIMA observations with concurrent observations at 4.8 GHz with the Very Large Array to search for and remove point sources. We find that point sources make an insignificant contribution to the observed anisotropy. C1 Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Dawson, KS (reprint author), Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. RI Holzapfel, William/I-4836-2015 NR 16 TC 31 Z9 31 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 MAY 20 PY 2001 VL 553 IS 1 BP L1 EP L4 DI 10.1086/320492 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 442JB UT WOS:000169280500001 ER PT J AU Guerrero, MA Chu, YH Gruendl, RA Williams, RM Kaler, JB AF Guerrero, MA Chu, YH Gruendl, RA Williams, RM Kaler, JB TI The enigmatic X-ray point sources at the central stars of NGC 6543 and NGC 7293 SO ASTROPHYSICAL JOURNAL LA English DT Article DE planetary nebulae : general; planetary nebulae : individual (NGC 6543, NGC 7293); stars : AGB and post-AGB; X-rays : stars ID PLANETARY-NEBULAE; ROSAT OBSERVATIONS; WHITE-DWARFS; EMISSION; NGC-6543; WINDS; RADIATION; PLASMAS AB Recent Chandra ACIS-S observations have detected a point source at the central star of NGC 6543 and confirmed the point-source nature of the hard X-ray emission from NGC 7293. The X-ray spectra of both sources peak between 0.5 and 1.0 keV and show line features indicating a thin plasma at temperatures of a few times 10(6) K. Their X-ray luminosities are 10(30) and 3 x 10(29) ergs s(-1), respectively. We have considered four different mechanisms to explain the nature of these sources. The X-ray emission from the central star of NGC 6543 may originate from the coronal activity of an undetected companion star or from shocks in its fast stellar wind, while the hard X-ray emission from NGC 7293 might be ascribed to an undetected dMe companion. Follow-up observations are needed to determine the existence and natures of these stellar companions. C1 Univ Illinois, Dept Astron, Urbana, IL 61801 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Guerrero, MA (reprint author), Univ Illinois, Dept Astron, 1002 W Green St, Urbana, IL 61801 USA. OI Guerrero, Martin/0000-0002-7759-106X NR 34 TC 56 Z9 56 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 MAY 20 PY 2001 VL 553 IS 1 BP L55 EP L58 DI 10.1086/320509 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 442JB UT WOS:000169280500014 ER PT J AU Owen, T Mahaffy, PR Niemann, HB Atreya, S Wong, M AF Owen, T Mahaffy, PR Niemann, HB Atreya, S Wong, M TI Protosolar nitrogen SO ASTROPHYSICAL JOURNAL LA English DT Article DE Earth; ISM : abundances; ISM : evolution; ISM : molecules; planets and satellites : individual (Jupiter); solar system : formation ID GALILEO PROBE MEASUREMENTS; JUPITERS ATMOSPHERE; SOLAR; ABUNDANCE; FRACTIONATION; SPECTROMETER; EVOLUTION; RATIOS; ORIGIN AB We have derived a value of N-15/N-14 = (2.3 +/- 0.3) x 10(-3) in the Jovian atmosphere using data from the Galileo Probe Mass Spectrometer. Adopting this as the average value for nitrogen in the solar nebula leads to a consistent interpretation of other measurements of nitrogen isotopes in the solar system, once nuclear evolution in the Galaxy and ion-molecule reactions in the interstellar medium are taken into account. The result confirms the assumption that atmospheric nitrogen on Earth was not delivered as N-2 but that N-2 was the dominant form of nitrogen in the solar nebula. C1 Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. RP Owen, T (reprint author), Univ Hawaii, Inst Astron, 2680 Woodlawn Dr, Honolulu, HI 96822 USA. RI Mahaffy, Paul/E-4609-2012 NR 28 TC 162 Z9 162 U1 0 U2 10 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 MAY 20 PY 2001 VL 553 IS 1 BP L77 EP L79 DI 10.1086/320501 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 442JB UT WOS:000169280500019 ER PT J AU Gamba, P Houshmand, B AF Gamba, P Houshmand, B TI An efficient neural classification chain of SAR and optical urban images SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID LAND-COVER CLASSIFICATION; INPUT PATTERNS; NETWORK; RECOGNITION AB In this paper a suitable neural classification algorithm, based on the use of Adaptive Resonance Theory (ART) networks, is applied to the fusion and classification of optical and SAR urban images. ART networks provide a flexible tool for classification, but are ruled by a large number of parameters. Therefore, the simplified ART2-A algorithm is used in this paper, and the neural approach is integrated into a classification chain where fuzzy clustering for merging of classes is also considered. The interaction between the two methods leads to encouraging results in less CPU time than classification with fuzzy clustering alone or other classical approaches (ISODATA). Examples of classification are provided using C-band total power AIRSAR data and optical images of Santa Monica, Los Angeles. C1 Univ Pavia, Dept Elect, I-27100 Pavia, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gamba, P (reprint author), Univ Pavia, Dept Elect, Via Ferrata 1, I-27100 Pavia, Italy. RI Gamba, Paolo/G-1959-2010 OI Gamba, Paolo/0000-0002-9576-6337 NR 27 TC 25 Z9 25 U1 0 U2 2 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD MAY 20 PY 2001 VL 22 IS 8 BP 1535 EP 1553 DI 10.1080/01431160118746 PG 19 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 437EK UT WOS:000168977600010 ER PT J AU Weaver, HA Sekanina, Z Toth, I Delahodde, CE Hainaut, OR Lamy, PL Bauer, JM A'Hearn, MF Arpigny, C Combi, MR Davies, JK Feldman, PD Festou, MC Hook, R Jorda, L Keesey, MSW Lisse, CM Marsden, BG Meech, KJ Tozzi, GP West, R AF Weaver, HA Sekanina, Z Toth, I Delahodde, CE Hainaut, OR Lamy, PL Bauer, JM A'Hearn, MF Arpigny, C Combi, MR Davies, JK Feldman, PD Festou, MC Hook, R Jorda, L Keesey, MSW Lisse, CM Marsden, BG Meech, KJ Tozzi, GP West, R TI HST and VLT investigations of the fragments of comet C/1999 S4 (LINEAR) SO SCIENCE LA English DT Article ID NUCLEUS; BREAKUP; SPLIT; DUST AB At least 16 fragments were detected in images of comet C/1999 S4 (LINEAR) taken on 5 August 2000 with the Hubble Space Telescope (HST) and on 6 August with the Very Large Telescope (VLT). Photometric analysis of the fragments indicates that the largest ones have effective spherical diameters of about 100 meters, which implies that the total mass in the observed fragments was about 2 x 10(9) kilograms. The comet's dust tail, which was the most prominent optical feature in August, was produced during a major fragmentation event, whose activity peaked on UT 22.8 +/- 0.2 July 2000. The mass of small particles (diameters less than about 230 micrometers) in the tail was about 4 x 10(8) kilograms, which is comparable to the mass contained in a large fragment and to the total mass lost from water sublimation after 21 July 2000 (about 3 x 108 kilograms). HST spectroscopic observations during 5 and 6 July 2000 demonstrate that the nucleus contained little carbon monoxide ice (ratio of carbon monoxide to water is less than or equal to 0.4%), which suggests that this volatile species did not play a role in the fragmentation of C/1999 S4 (LINEAR). C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Konkoly Observ Budapest, H-1525 Budapest, Hungary. European So Observ, Santiago 19, Chile. CNRS, Astron Spatiale Lab, F-13376 Marseille 12, France. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Univ Liege, Inst Astrophys, B-4000 Liege, Belgium. Univ Michigan, Space Phys Res Lab, Ann Arbor, MI 48109 USA. Joint Astron Ctr, Hilo, HI 96720 USA. Observ Midi Pyrenees, F-31400 Toulouse, France. European So Observ, D-85748 Garching, Germany. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Osserv Astrofis Arcetri, I-50125 Florence, Italy. RP Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. RI Combi, Michael/J-1697-2012; Weaver, Harold/D-9188-2016; Lisse, Carey/B-7772-2016; OI Combi, Michael/0000-0002-9805-0078; Lisse, Carey/0000-0002-9548-1526; Tozzi, Gian Paolo/0000-0003-4775-5788 NR 23 TC 63 Z9 63 U1 1 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 EI 1095-9203 J9 SCIENCE JI Science PD MAY 18 PY 2001 VL 292 IS 5520 BP 1329 EP 1333 DI 10.1126/science.1058606 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 435DV UT WOS:000168862900034 PM 11359001 ER PT J AU Mumma, MJ Dello Russo, N DiSanti, MA Magee-Sauer, K Novak, RE Brittain, S Rettig, T McLean, IS Reuter, DC Xu, LH AF Mumma, MJ Dello Russo, N DiSanti, MA Magee-Sauer, K Novak, RE Brittain, S Rettig, T McLean, IS Reuter, DC Xu, LH TI Organic composition of C/1999 S4 (LINEAR): A comet formed near Jupiter? SO SCIENCE LA English DT Article ID O1 HALE-BOPP; CARBON-MONOXIDE; B2 HYAKUTAKE; SOLAR NEBULA; WATER; DEUTERIUM; EMISSION; METHANOL; P/HALLEY; ORIGIN AB In the current paradigm, Oort cloud comets formed in the giant planets' region of the solar nebula, where temperatures and other conditions varied greatly. The measured compositions of four such comets (Halley, Hyakutake, Hale-Bopp, and Lee) are consistent with formation from interstellar ices in the cold nebular region beyond Uranus. The composition of comet C/1999 S4 (LINEAR) differs greatly, which suggests that its ices condensed from processed nebular gas, probably in the Jupiter-Saturn region. Its unusual organic composition may require reevaluation of the prebiotic organic material delivered to the young Earth by comets. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. RowanUniv, Dept Chem & Phys, Glassboro, NJ 08028 USA. Iona Coll, Dept Phys, New Rochelle, NY 10801 USA. Univ Notre Dame, Dept Phys & Astron, Notre Dame, IN 46556 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. Univ New Brunswick, Dept Phys Sci, St John, NB E2L 4L5, Canada. RP Mumma, MJ (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Code 690, Greenbelt, MD 20771 USA. RI Brittain, Sean/K-9001-2012; mumma, michael/I-2764-2013; Xu, Li-Hong/J-5095-2015; Magee-Sauer, Karen/K-6061-2015; Dello Russo, Neil/G-2727-2015 OI Brittain, Sean/0000-0001-5638-1330; Magee-Sauer, Karen/0000-0002-4979-9875; Dello Russo, Neil/0000-0002-8379-7304 NR 61 TC 115 Z9 115 U1 0 U2 8 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD MAY 18 PY 2001 VL 292 IS 5520 BP 1334 EP 1339 DI 10.1126/science.1058929 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 435DV UT WOS:000168862900035 PM 11359002 ER PT J AU Lisse, CM Christian, DJ Dennerl, K Meech, KJ Petre, R Weaver, HA Wolk, SJ AF Lisse, CM Christian, DJ Dennerl, K Meech, KJ Petre, R Weaver, HA Wolk, SJ TI Charge exchange-induced X-ray emission from comet C/1999 S4 (LINEAR) SO SCIENCE LA English DT Article ID EXTREME-ULTRAVIOLET EMISSION; SOLAR-WIND; HALE-BOPP; HYAKUTAKE; IONS; SPECTRA AB Using soft x-ray observations of the bright new comet C/1999 S4 (LIN EAR) with the Chandra x-ray observatory, we have detected x-ray line emission created by charge exchange between highly ionized solar wind minor ions and neutral gases in the comet's coma. The emission morphology was symmetrically crescent shaped and extended out to 300,000 kilometers from the nucleus. The emission spectrum contains 6 lines at 320, 400, 490, 560, 600, and 670 electron volts, attributable to electron capture and radiative deexcitation by the solar wind species C+5, C+6, N+7, O+7, and O+8. A contemporaneous T-day soft x-ray Light curve obtained using the Extreme Ultraviolet Explorer demonstrates a large increase in the comet's emission coincident with a strong solar flare on 14 and 15 July 2000. C1 Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Comp Sci Corp, Sci Operat, Baltimore, MD 21218 USA. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Harvard Smithsonian Ctr Astrophys, Chandra Xray Ctr, Cambridge, MA 02138 USA. RP Lisse, CM (reprint author), Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RI Weaver, Harold/D-9188-2016; Lisse, Carey/B-7772-2016; OI Lisse, Carey/0000-0002-9548-1526; Wolk, Scott/0000-0002-0826-9261 NR 34 TC 112 Z9 113 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 MAY 18 PY 2001 VL 292 IS 5520 BP 1343 EP 1348 DI 10.1126/science.292.5520.1343 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 435DV UT WOS:000168862900037 PM 11359004 ER PT J AU Sukhatme, K Mukharsky, Y Chui, T Pearson, D AF Sukhatme, K Mukharsky, Y Chui, T Pearson, D TI Observation of the ideal Josephson effect in superfluid He-4 SO NATURE LA English DT Article ID ANALOG AB Superfluids and superconductors are the only states of condensed matter that can be described by a single wavefunction, with a coherent quantum phase Phi. The mass flow in a superfluid can be described by classical hydrodynamics for small flow velocity, but above a critical velocity, quantized vortices are created and the classical picture breaks down. This can be observed for a superfluid flowing through a microscopic aperture when the mass flow is measured as a function of the phase difference across the aperture; the curve resembles a hysteretic sawtooth where each jump corresponds to the creation of a vortex(1-3). When the aperture is made small enough, the system can enter the so-called 'ideal' Josephson regime(1,4), where the superfluid mass flow becomes a continuous function of the phase difference. This regime has been detected(1,5,6) in superfluid He-3, but was hitherto believed to be unobservable, owing to fluctuations(7), in He-4. Here we report the observation of the ideal Josephson effect in He-4. We study the flow of He-4 through an array of micro-apertures and observe a transition to the ideal Josephson regime as the temperature is increased towards the superfluid transition temperature, T-lambda. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Ctr Etud Saclay, Serv Phys Etat Condense, CEA, DRECAM, F-91191 Gif Sur Yvette, France. RP Mukharsky, Y (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Mukharsky, Yury/F-4920-2013 NR 15 TC 78 Z9 78 U1 0 U2 4 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD MAY 17 PY 2001 VL 411 IS 6835 BP 280 EP 283 DI 10.1038/35077024 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 432RT UT WOS:000168710000039 PM 11357124 ER PT J AU Rabbette, M Pilewskie, P AF Rabbette, M Pilewskie, P TI Multivariate analysis of solar spectral irradiance measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID REFLECTANCE SPECTRA; ABSORPTION; MODELS AB Principal component analysis is used to characterize approximately 7000 downwelling solar irradiance spectra retrieved at the Southern Great Plains site during an Atmospheric Radiation Measurement (ARM) shortwave intensive operating period. This analysis technique has proven to be very effective in reducing a large set of variables into a much smaller set of independent variables while retaining the information content. It is used to determine the minimum number of parameters necessary to characterize atmospheric spectral irradiance or the dimensionality of atmospheric variability. It was found that well over 99% of the spectral information was contained in the first six mutually orthogonal linear combinations of the observed variables (flux at various wavelengths). Rotation of the principal components was effective in separating various components by their independent physical influences. The majority of the variability in the downwelling solar irradiance (380-1000 nm) was explained by the following fundamental atmospheric parameters (in order of their importance): cloud scattering, water vapor absorption, molecular scattering, and ozone absorption. In contrast to what has been proposed as a resolution to a clear-sky absorption anomaly, no unexpected gaseous absorption signature was found in any of the significant components. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Bay Area Environm Res Inst, San Francisco, CA USA. RP Rabbette, M (reprint author), NASA, Ames Res Ctr, MS 245-4, Moffett Field, CA 94035 USA. NR 35 TC 10 Z9 10 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2001 VL 106 IS D9 BP 9685 EP 9696 DI 10.1029/2000JD900582 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 432ZY UT WOS:000168731900005 ER PT J AU Pfister, L Selkirk, HB Jensen, EJ Schoeberl, MR Toon, OB Browell, EV Grant, WB Gary, B Mahoney, MJ Bui, TV Hintsa, E AF Pfister, L Selkirk, HB Jensen, EJ Schoeberl, MR Toon, OB Browell, EV Grant, WB Gary, B Mahoney, MJ Bui, TV Hintsa, E TI Aircraft observations of thin cirrus clouds near the tropical tropopause SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID WATER-VAPOR; STRATOSPHERE; TROPOSPHERE; TRANSPORT; CIRCULATION; TEMPERATURE; DEHYDRATION; CONVECTION; SYSTEM; STEP AB This work describes aircraft-based lidar observations of thin cirrus clouds at the tropical tropopause in the central Pacific obtained during the Tropical Ozone Transport Experiment/Vortex Ozone Transport Experiment (TOTE/VOTE) in December 1995 and February 1996, Thin cirrus clouds were found at the tropopause on each of the four flights which penetrated within 15 degrees of the equator at 200-210 east longitude. South of 15 degreesN, thin cirrus were detected above the aircraft about 65% of the time that data were available. The altitudes of these clouds exceeded 18 km at times. The cirrus observations could be divided into two basic types: thin quasi-laminar wisps and thicker, more textured structures. On the basis of trajectory analyses and temperature histories, these two types were usually formed respectively by (1) in situ cooling on both a synoptic scale and mesoscale and (2) recent (a few days) outflow from convection. There is evidence from one case that the thicker clouds can also be formed by in situ cooling. The actual presence or absence of thin cirrus clouds was also consistent with the temperature and convective histories derived from back trajectory calculations, Notably, at any given time, only a relatively small portion (at most 25%) of the west central tropical Pacific has been influenced by convection within the previous 10 days. The structures of some of the thin cirrus clouds formed in situ strongly resembled long-wavelength (500-1000 km) gravity waves observed nearly simultaneously by the ER-2 on one of the flights. Comparison with in situ water vapor profiles made by the NASA ER-2 aircraft provide some observational support for the hypothesis that thin cirrus clouds play an important role in dehydrating tropospheric air as it enters the stratosphere. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Space Phys Res Inst, Sunnyvale, CA USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. Jet Propuls Lab, Microwave & Lidar Technol Sect, Pasadena, CA USA. Harvard Univ, Atmospher Res Project, Cambridge, MA USA. RP Pfister, L (reprint author), NASA, Ames Res Ctr, MS 245-4, Moffett Field, CA 94035 USA. RI Grant, William/B-8311-2009; Selkirk, Henry/H-2021-2012 OI Grant, William/0000-0002-1439-3285; NR 35 TC 87 Z9 86 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2001 VL 106 IS D9 BP 9765 EP 9786 DI 10.1029/2000JD900648 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 432ZY UT WOS:000168731900011 ER PT J AU O'Neill, NT Eck, TF Holben, BN Smirnov, A Dubovik, O Royer, A AF O'Neill, NT Eck, TF Holben, BN Smirnov, A Dubovik, O Royer, A TI Bimodal size distribution influences on the variation of Angstrom derivatives in spectral and optical depth space SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID AEROSOL; RETRIEVAL; THICKNESS; RADIANCE; AERONET; OCEAN AB The variation of the aerosol optical depth and its first and second spectral derivatives (a and alpha') can be largely described in terms of the spectral interaction between the individual optical components of a bimodal size distribution. Simple analytical expressions involving the separate optical components of each mode explain virtually all the features seen in spectra of the aerosol optical depth and its derivatives. Illustrations are given for a variety of measured optical depth spectra; these include comparative simulations of the diurnal behavior of alpha and alpha' spectra as well as the diurnal and general statistical behavior of alpha and alpha' as a function of optical depth (optical depth space). Each mode acts as a fixed "basis vector" from which much of the behavior in spectral and optical depth space can be generated by varying the extensive (number density dependent) contributions of fine and coarse mode optical depths. Departures from these basis vectors are caused by changes in aerosol type (average size and refractive index) and thus are associated with differing synoptical air masses, source trajectories or humidity conditions. Spectral parameters are very sensitive to interband errors in measured optical depth data. Third-order polynomial fits within the visible-NIR spectral region effectively filter such errors while representing the limit of useful extractable information. C1 Univ Sherbrooke, CARTEL, Sherbrooke, PQ J1K 2R1, Canada. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP O'Neill, NT (reprint author), Univ Sherbrooke, CARTEL, Sherbrooke, PQ J1K 2R1, Canada. RI Dubovik, Oleg/A-8235-2009; Smirnov, Alexander/C-2121-2009; ECK, THOMAS/D-7407-2012 OI Dubovik, Oleg/0000-0003-3482-6460; Smirnov, Alexander/0000-0002-8208-1304; NR 20 TC 120 Z9 125 U1 1 U2 17 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2001 VL 106 IS D9 BP 9787 EP 9806 DI 10.1029/2000JD900245 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 432ZY UT WOS:000168731900012 ER PT J AU Formenti, P Andreae, MO Andreae, TW Galani, E Vasaras, A Zerefos, C Amiridis, V Orlovsky, L Karnieli, A Wendisch, M Wex, H Holben, BN Maenhaut, W Lelieveld, J AF Formenti, P Andreae, MO Andreae, TW Galani, E Vasaras, A Zerefos, C Amiridis, V Orlovsky, L Karnieli, A Wendisch, M Wex, H Holben, BN Maenhaut, W Lelieveld, J TI Aerosol optical properties and large-scale transport of air masses: Observations at a coastal and a semiarid site in the eastern Mediterranean during summer 1998 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CHARACTERIZATION EXPERIMENT ACE-1; LIGHT-SCATTERING; TEMPORAL VARIABILITY; RADIATIVE PROPERTIES; SIZE DISTRIBUTION; BOUNDARY-LAYER; UNITED-STATES; MINERAL DUST; ISRAEL; SULFATE AB Spectral measurements of the aerosol particle scattering coefficient sigma (s) and the aerosol optical depth tau (a) were conducted at Ouranoupolis (Greece, 40 degrees 23'N, 23 degrees 57'E) and at Sde Boker (Israel, 30 degrees 51'N, 34 degrees 47'E) between June and September 1998. Measurements were related to 5-day three-dimensional back trajectories at 950, 850, and 550 hPa to assess the influence of long-range transport from particular source regions to the aerosol load at the two sites. Our measurements show that the eastern Mediterranean basin is moderately to highly polluted during summer. Daily average sigma (s) values at 550 nm were typically in the range of 30-200 Mm(-1) at both sites. The range obtained for the summer regional aerosol optical depth tau (a) was 0.03-0.52 at 500 nm. Enhanced aerosol extinction was related to transport of polluted air masses from western and eastern Europe. High-altitude transport of mineral dust from northern Africa was observed at both sites, particularly in Israel. C1 Max Planck Inst Chem, Biogeochem Dept, D-55020 Mainz, Germany. Univ Utrecht, Inst Marine & Atmospher Res, NL-2584 CC Utrecht, Netherlands. Dept Phys, Lab Atmospher Phys, Salonika 540006, Greece. Ben Gurion Univ Negev, IL-84990 Sede Boqer, Israel. Inst Tropospher Res, D-04318 Leipzig, Germany. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. State Univ Ghent, Inst Nucl Sci, B-9000 Ghent, Belgium. RP Formenti, P (reprint author), Max Planck Inst Chem, Biogeochem Dept, Postfach 3060, D-55020 Mainz, Germany. RI Amiridis, Vassilis/G-6769-2012; Maenhaut, Willy/M-3091-2013; Andreae, Meinrat/B-1068-2008; Lelieveld, Johannes/A-1986-2013; Wendisch, Manfred/E-4175-2013 OI Amiridis, Vassilis/0000-0002-1544-7812; Maenhaut, Willy/0000-0002-4715-4627; Andreae, Meinrat/0000-0003-1968-7925; Wendisch, Manfred/0000-0002-4652-5561 NR 51 TC 59 Z9 59 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2001 VL 106 IS D9 BP 9807 EP 9826 DI 10.1029/2000JD900609 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 432ZY UT WOS:000168731900013 ER PT J AU Ziemke, JR Chandra, S Bhartia, PK AF Ziemke, JR Chandra, S Bhartia, PK TI "Cloud slicing": A new technique to derive upper tropospheric ozone from satellite measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID BACKSCATTER ULTRAVIOLET MEASUREMENTS; ROTATIONAL RAMAN-SCATTERING; MODIFIED-RESIDUAL METHOD; MICROWAVE SOUNDING UNIT; MAPPING SPECTROMETER; COLUMN OZONE; TOMS AB A new technique called cloud slicing has been developed for measuring upper tropospheric O-3. Cloud slicing takes advantage of the opaque property of water vapor clouds to ultraviolet wavelength radiation. Measurements of above-cloud column O-3 from the Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) instrument are combined together with Nimbus 7 temperature-humidity and infrared radiometer (THIR) cloud-top pressure data to derive O-3 column amounts in the upper troposphere. In this study, tropical TOMS and THIR data for the period 1979-1984 are analyzed. By combining total tropospheric column ozone (referred to as TCO) measurements from the convective cloud differential (CCD) method with 100- to 400-hPa upper tropospheric column O-3 amounts from cloud slicing, it is possible to estimate 400- to 1000-hPa lower tropospheric column O-3 and evaluate its spatial and temporal variability. Results for both the upper and lower tropical troposphere show a year-round zonal wave number 1 pattern in column O-3 with the largest amounts in the Atlantic region (up to similar to 15 DU in the 100- to 400-hPa pressure band and similar to 25-30 DU in the 400- to 1000-hPa pressure band). Upper tropospheric O-3 derived from cloud slicing shows maximum column amounts in the Atlantic region in the June-August and September-November seasons which are similar to the seasonal variability of CCD-derived TCO in the region. For the lower troposphere, the largest column amounts occur in the September-November season over Brazil in South America and also southern Africa. Localized increases in the tropics in the lower tropospheric O-3 are found over the northern region of South America around August and off the west coast of equatorial Africa in the March-May season. Time series analysis for several regions in South America and Africa show an anomalous increase in O-3 in the lower troposphere around the month of March which is not observed in the upper troposphere. The eastern Pacific indicates weak seasonal variability of upper, lower, and total tropospheric O-3 compared with the western Pacific, which shows the largest TCO amounts in both hemispheres around spring months. O-3 variability in the western Pacific is expected to have greater variability caused by strong convection, pollution and biomass burning, land-sea contrast, and monsoon developments. C1 Stinger Ghaffarian Technol, Greenbelt, MD USA. NASA, Goddard Space Flight Ctr, Chem & Dynam Branch, Greenbelt, MD 20771 USA. RP Ziemke, JR (reprint author), Stinger Ghaffarian Technol, Greenbelt, MD USA. RI Bhartia, Pawan/A-4209-2016 OI Bhartia, Pawan/0000-0001-8307-9137 NR 23 TC 59 Z9 60 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2001 VL 106 IS D9 BP 9853 EP 9867 DI 10.1029/2000JD900768 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 432ZY UT WOS:000168731900016 ER PT J AU Douglass, LR Schoeberl, MR Kawa, SR Browell, EV AF Douglass, LR Schoeberl, MR Kawa, SR Browell, EV TI A composite view of ozone evolution in the 1995-1996 northern winter polar vortex developed from airborne lidar and satellite observations SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ARCTIC WINTER; 3-DIMENSIONAL SIMULATION; UARS MLS; DEPLETION; STRATOSPHERE; MODEL; AIRCRAFT; LATITUDE; CLO; PERTURBATIONS AB A three-dimensional model using winds and temperatures from the Goddard Earth Observing System Data Assimilation System is used to simulate ozone evolution in the winter high-latitude northern lower stratosphere. The simulation results are compared with ozone observations from three platforms: the differential absorption lidar (DIAL), the Microwave Limb Sounder (MLS), and the Polar Ozone and Aerosol Measurement (POAM II). Time series for the different data sets are consistent with each other, and diverge from model time series during December and January. The model ozone in December and January is much less sensitive to the model photochemistry than to the model vertical transport. Simulations with different initial conditions for ozone demonstrate sensivitity to the model ozone profile shape. The modeled ozone throughout December and January most closely resembles observed ozone when the vertical profiles between 12 and 20 km within the polar vortex closely match December DIAL observations. We make a quantitative estimate of the uncertainty in the vertical advection using diabatic trajectory calculations. The net transport uncertainty is significant and should be accounted for when comparing observations with model ozone. The observed and modeled ozone time series during December and January are not inconsistent when these transport uncertainties are taken into account. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Douglass, LR (reprint author), NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA. EM douglass@persephone.gsfc.nasa.gov; schom@zephyr.gsfc.nasa.gov; kawa@maia.gsfc.nasa.gov; e.v.browell@larc.nasa.gov RI Douglass, Anne/D-4655-2012; Kawa, Stephan/E-9040-2012 NR 51 TC 13 Z9 13 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-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2001 VL 106 IS D9 BP 9879 EP 9895 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 432ZY UT WOS:000168731900018 ER PT J AU Smith, MAH Devi, VM Benner, DC Rinsland, CP AF Smith, MAH Devi, VM Benner, DC Rinsland, CP TI Absolute intensities of O-16(3) lines in the 9-11 mu m region SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ABSORPTION CROSS-SECTIONS; OZONE UV SPECTROSCOPY; TEMPERATURE-DEPENDENCE; WAVELENGTH REGION; STRENGTHS; N2O; FREQUENCIES; DATABASE; 254-NM; 185-NM AB Absolute intensities of 376 O-16(3) lines in the 9-11 mum region have been determined from high-resolution infrared absorption spectra recorded at room temperature using a Fourier transform spectrometer. The ozone samples were contained in a glass cell having crossed IR-transmitting and UV-transmitting paths, and the UV absorption at 254 nm was used to monitor ozone concentrations in the cell. A multispectrum nonlinear least squares fitting procedure was used to determine intensities for 366 lines in the nu (3) fundamental band and 10 lines in the nu (3) band. The absolute accuracy of these intensity values ranges from 2% for the strongest, most well determined lines to 4 or 5% for the weakest lines measured. On average, our measured intensities are approximately 1% larger than the values on current spectroscopic databases. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Coll William & Mary, Dept Phys, Williamsburg, VA 23187 USA. RP Smith, MAH (reprint author), NASA, Langley Res Ctr, Mail Stop 401A, Hampton, VA 23681 USA. NR 29 TC 18 Z9 19 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2001 VL 106 IS D9 BP 9909 EP 9921 DI 10.1029/2000JD900806 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 432ZY UT WOS:000168731900020 ER PT J AU Manney, GL Michelsen, HA Bevilacqua, RM Gunson, MR Irion, FW Livesey, NJ Oberheide, J Riese, M Russell, JM Toon, GC Zawodny, JM AF Manney, GL Michelsen, HA Bevilacqua, RM Gunson, MR Irion, FW Livesey, NJ Oberheide, J Riese, M Russell, JM Toon, GC Zawodny, JM TI Comparison of satellite ozone observations in coincident air masses in early November 1994 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CRYOGENIC INFRARED SPECTROMETERS; STRATOSPHERIC POLAR VORTEX; ATMOSPHERIC SOUNDER MAS; TRACE GAS OBSERVATIONS; TRAJECTORY CALCULATIONS; WINTER STRATOSPHERE; POAM-II; VALIDATION; INSTRUMENT; RECONSTRUCTION AB Ozone observed by seven satellite instruments, the Atmospheric Trace Molecule Spectroscopy instrument (ATMOS), Stratospheric Aerosol and Gas Experiment (SAGE) II, Polar Ozone and Aerosol Measurement (POAM) II instrument, Halogen Occultation Experiment (HALOE), Microwave Limb Sounder (MLS), Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA), and Millimeter-wave Atmospheric Sounder (MAS), during early November 1994 is mapped in equivalent latitude/potential temperature (EqL/theta) space to facilitate nearly global comparisons of measurements taken in similar air masses. Ozone from all instruments usually agrees to within 0.5 ppmv (similar to5%) in the upper stratosphere and similar to0.25 ppmv in the lower stratosphere; larger differences in the midstratosphere are primarily due to sampling differences. Individual profile comparisons, selected to match meteorological conditions, show remarkably good agreement between all instruments that sample similar latitudes, although some small differences do not appear to be related to sampling differences. In the Southern Hemisphere (SH) midstratosphere, the instruments (ATMOS, SAGE II, and FOAM II) with observations confined to high latitudes measured low EqLs in air drawn up from low latitudes that had formed a "low-ozone pocket"; they measured much lower ozone at low EqL than those that sampled low latitudes. A low-ozone pocket had also formed in the Northern Hemisphere (NH) midstratosphere (a month earlier than this phenomenon has previously been reported), also resulting in differences between instruments based on their sampling patterns. FOAM If sampled only high latitudes in the NH, where extravortex sampling did not include tropical, high-ozone air, and thus measured lower ozone at a given EqL than other instruments. Ozone laminae appear in coincident profiles from multiple instruments, confirming atmospheric origins for these features and agreement in some detail between ozone observed by several instruments; reverse trajectory calculations indicate such laminae arise from filamentation in and around the polar vortices. Both EqL/theta and profile comparisons indicate overall excellent agreement in ozone observed by all seven instruments in early November 1994. When care is taken to compare similar air masses and to understand sampling effects, much useful information can be obtained from comparisons between instruments with very different observing patterns. C1 USN, Res Lab, Washington, DC 20375 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Sandia Natl Labs, Combust Res Facil, Livermore, CA 94551 USA. Berg Univ Gesamthsch Wuppertal, Dept Phys D 07 05, D-42097 Wuppertal, Germany. Hampton Univ, Ctr Atmospher Sci, Hampton, VA 23668 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Manney, GL (reprint author), New Mexico Highlands Univ, Dept Phys, Las Vegas, NM 87701 USA. RI Oberheide, Jens/C-6156-2011; Riese, Martin/A-3927-2013 OI Oberheide, Jens/0000-0001-6721-2540; Riese, Martin/0000-0001-6398-6493 NR 45 TC 28 Z9 28 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2001 VL 106 IS D9 BP 9923 EP 9943 DI 10.1029/2000JD900826 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 432ZY UT WOS:000168731900021 ER PT J AU Lefohn, AS Oltmans, SJ Dann, T Singh, HB AF Lefohn, AS Oltmans, SJ Dann, T Singh, HB TI Present-day variability of background ozone in the lower troposphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC OZONE; UNITED-STATES; SURFACE; TRANSPORT; EXCHANGE; IMPACT AB There is a substantial background of ozone (O-3) present in the lower troposphere in the Northern Hemisphere that has both a stratospheric and photochemical tropospheric origin. Levels of hourly averaged O-3 concentrations in the range 0.04-0.08 ppm are often measured as part of the "background O-3" burden. Stratospheric processes play a significant role in defining these background O-3 concentrations. In order to better understand the frequency, spatial, and temporal characteristics of this background O-3 burden, we have analyzed hourly average O-3 concentrations greater than or equal to0.05 and greater than or equal to0.06 ppm that were experienced during the photochemically quiescent months in the winter and spring at several rural sites across southern Canada, the northern United States, and northern Europe. Our results were mostly consistent and indicated that hourly average O-3 concentrations greater than or equal to0.05 and greater than or equal to0.06 ppm occur frequently during the winter and spring months. Most occurrences were during April and May but sometimes as late as June. In some, but not all, of the cases that were studied, a plausible explanation for the higher O-3 values was the presence of upper tropospheric and stratospheric air that was transported down to the surface. For purposes of making the analysis more straightforward, this study was limited to the more northerly latitudes. It might be expected that a significant contribution from natural sources is also important in producing O-3 levels in the 0.05-0.06 ppm or higher range at more southerly locations where stratospheric intrusions also have an important impact on the tropospheric O-3 distribution. C1 ASL & Associates, Helena, MT 59601 USA. Environm Technol Ctr, Anal & Air Qual Div, Ottawa, ON K1A 0H3, Canada. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80305 USA. NASA, Ames Res Ctr, Div Earth Sci MS 245 5, Moffett Field, CA 94035 USA. RP Lefohn, AS (reprint author), ASL & Associates, 111 N Last Chance Gulch,Suite 4A, Helena, MT 59601 USA. NR 32 TC 56 Z9 57 U1 0 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2001 VL 106 IS D9 BP 9945 EP 9958 DI 10.1029/2000JD900793 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 432ZY UT WOS:000168731900022 ER PT J AU Orsolini, YJ Hansen, G Manney, GL Livesey, N Hoppe, UP AF Orsolini, YJ Hansen, G Manney, GL Livesey, N Hoppe, UP TI Lagrangian reconstruction of ozone column and profile at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) throughout the winter and spring of 1997-1998 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID POLAR VORTEX; TRAJECTORY CALCULATIONS; DEPLETION; LAMINAE AB We present a Lagrangian model-based technique to reconstruct ozone profile and column in support of the interpretation of ozone lidar observations made at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR). High-resolution ozone profiles as well. as column ozone are reconstructed locally at ALOMAR, several times a day, regularly throughout the winter and spring of 1997/1998. The approach consists of calculating a large number of back trajectories to determine the origin of air parcels above ALOMAR and of using satellite observations to determine their ozone content. The blend of satellite observations with limited spatial and temporal coverage, and global gridded meteorological data is akin to a simplified form of data assimilation. The usefulness of the approach is demonstrated by a systematic comparison between reconstructed and observed ozone profiles and column and, in particular, their day-to-day variability. Abrupt changes in reconstructed and observed profile shape are caused by polar vortex displacements, deep intrusions of midlatitude air, or vortex edge filamentation. Prominent laminae are seen in the spring, as the vortex breaks down. Short-lived, large-amplitude total ozone peaks are seen in the model and observations, most prominently in February and March, when they are in excess of 100 Dobson units. They are shown to result from a combination of a lowering of isentropes in the lowermost stratosphere and of advection of ozone-rich air from the base of the polar vortex. C1 Norwegian Inst Air Res, NILU, N-2027 Kjeller, Norway. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Def Res Estab, FFI, N-2027 Kjeller, Norway. RP Orsolini, YJ (reprint author), Norwegian Inst Air Res, NILU, POB 100, N-2027 Kjeller, Norway. NR 18 TC 9 Z9 9 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2001 VL 106 IS D9 BP 10011 EP 10021 DI 10.1029/2000JD900659 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 432ZY UT WOS:000168731900026 ER PT J AU Richter, I Brinza, DE Cassel, M Glassmeier, KH Kuhnke, F Musmann, G Othmer, C Schwingenschuh, K Tsurutani, BT AF Richter, I Brinza, DE Cassel, M Glassmeier, KH Kuhnke, F Musmann, G Othmer, C Schwingenschuh, K Tsurutani, BT TI First direct magnetic field measurements of an asteroidal magnetic field: DS1 at Braille SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID GASPRA AB Deep Space 1 (DS1) is the first interplanetary spacecraft (s/c) using ion propulsion and aims at investigating the compatibility of innovative technology with scientific measurements. DS1 performed a successful flyby at the asteroid Braille on July 29th, 1999. This closest-ever encounter allowed for the first time a direct measurement of an asteroidal magnetic field. The manifold magnetic disturbances caused by the ion propulsion onboard DS1, however, required an elaborate data processing scheme in order to extract the magnetic signature of Braille. Its successful application to the magnetometer data of the asteroid flyby reveals a magnetic moment of 2.1 . 10(11) Am-2 for Braille. C1 Tech Univ Braunschweig, Inst Geophys & Meteorol, D-38106 Braunschweig, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Tech Univ Braunschweig, Inst Comp & Commun Network Engn, D-38106 Braunschweig, Germany. Graz Tech Univ, Space Res Inst, A-8042 Graz, Austria. RP Richter, I (reprint author), Tech Univ Braunschweig, Inst Geophys & Meteorol, Mendelssohnstr 3, D-38106 Braunschweig, Germany. NR 12 TC 30 Z9 31 U1 1 U2 4 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 MAY 15 PY 2001 VL 28 IS 10 BP 1913 EP 1916 DI 10.1029/2000GL012679 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 431EB UT WOS:000168617900003 ER PT J AU Moldwin, MB Collier, MR Slavin, JA Szabo, A AF Moldwin, MB Collier, MR Slavin, JA Szabo, A TI On the origin of reverse polarity TCRs SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SUDDEN IMPULSES; MAGNETIC-FIELD; SOLAR-WIND; MAGNETOTAIL; EVOLUTION AB Reverse polarity, or South-then-North (SN) bipolar, traveling compression regions (SN TCRs) are often observed in the Earth's magnetotail lobes. These events have been interpreted as either slowly earthward propagating "proto-plasmoids" during extremely quiet geomagnetic conditions, or due to pressure pulses in the solar wind or magnetosheath compressing the magnetotail. This study presents a survey of 21 IMP 8 observations of SN TCRs and the corresponding solar wind pressure conditions as measured by WIND. We found that solar wind or magnetosheath pressure pulses nicely explain most (17), though not all, of the SN TCR observations. Therefore, it appears that both explanations previously given are needed to explain SN TCRs. We also found that most of these events occurred during northward Interplanetary Magnetic Field (IMF) conditions. This suggests that the magnetotail may respond differently to solar wind dynamic pressure pulses for different orientations of the IMF. C1 Univ Calif Los Angeles, ESS, Los Angeles, CA 90095 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Moldwin, MB (reprint author), Univ Calif Los Angeles, ESS, Los Angeles, CA 90095 USA. RI Moldwin, Mark/F-8785-2011; Slavin, James/H-3170-2012; Collier, Michael/I-4864-2013 OI Moldwin, Mark/0000-0003-0954-1770; Slavin, James/0000-0002-9206-724X; Collier, Michael/0000-0001-9658-6605 NR 14 TC 6 Z9 6 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 MAY 15 PY 2001 VL 28 IS 10 BP 1925 EP 1928 DI 10.1029/2000GL012485 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 431EB UT WOS:000168617900006 ER PT J AU Katzberg, SJ Walker, RA Roles, JH Lynch, T Black, PG AF Katzberg, SJ Walker, RA Roles, JH Lynch, T Black, PG TI First GPS signals reflected from the interior of a tropical storm: Preliminary results from Hurricane Michael SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Using GPS signals reflected from the ocean surface is developing into a simple technique for measuring sea-state and inferring surface wind speeds. Theoretical models have been developed which are considered valid to approximately 24 meters per second. The GPS reflection technique has an obvious extension to extremely high sea states, cyclones and extra-tropical storms. In October of 2000 a GPS system mounted in a NOAA Hurricane Hunter research aircraft, was flown into Hurricane Michael off the South Carolina coast. The first acquisition of GPS signals reflected from the sea surface inside tropical cyclones was accomplished. This paper presents some examples of the data sets as well as early wind speed retrieval results using direct extensions of current models. Data from the GPS wind speed retrievals as well as from direct aircraft measurements are compared and discussed. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. OMAO CASC, MacDill AFB, FL 33608 USA. OAR MASC, Miami, FL 33149 USA. RP Katzberg, SJ (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 6 TC 21 Z9 22 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 2001 VL 28 IS 10 BP 1981 EP 1984 DI 10.1029/2000GL012823 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 431EB UT WOS:000168617900020 ER PT J AU de Viron, O Marcus, SL Dickey, JO AF de Viron, O Marcus, SL Dickey, JO TI Atmospheric torques during the winter of 1989: Impact of ENSO and NAO positive phases SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NORTH-ATLANTIC OSCILLATION; SEA-LEVEL PRESSURE; ANGULAR-MOMENTUM; EL-NINO; INTERANNUAL FLUCTUATIONS; SOUTHERN-OSCILLATION; EARTH ROTATION; LA-NINA; VARIABILITY; CLIMATE AB The axial component of atmospheric angular momentum (AAM) reached a decadal minimum during the winter of 1989, when the cool (La Nina) phase of the ENSO cycle and the positive phases of the North Atlantic Oscillation (NAO) and the related Arctic Oscillation (AO) were active. Here, we examine the global atmospheric dynamics associated with this event from the torque point of view. It will be shown how mountain torques on North America, South America and Europe related to these oscillations led to the AAM minimum, partly compensated by a positive ENSO-related mountain torque over Asia. The friction torque had more nearly equal positive and negative anomalies associated with ENSO and NAO forcing, respectively, and made a smaller, offsetting contribution to the global AAM anomaly during this episode. C1 Jet Prop Lab, Pasadena, CA 91108 USA. RP de Viron, O (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91108 USA. RI de Viron, Olivier/N-6647-2014; OI de Viron, Olivier/0000-0003-3112-9686; Marcus, Steven/0000-0002-5763-6961 NR 27 TC 10 Z9 10 U1 1 U2 3 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 MAY 15 PY 2001 VL 28 IS 10 BP 1985 EP 1988 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 431EB UT WOS:000168617900021 ER PT J AU Mo, KC Hakkinen, S AF Mo, KC Hakkinen, S TI Decadal variations in the tropical South Atlantic and linkages to the Pacific SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID VARIABILITY; OCEAN; TEMPERATURES; HEMISPHERE; PATTERNS; ENSO AB Linkages between the sea surface temperature anomalies (SSTAs) in the southern tropical Atlantic (STA) and in the Pacific on decadal time scales were examined. Seven to eight years before warming in the STA, an ENSO-like decadal SSTA pattern with positive anomalies in the Tropics and negative anomalies in the subtropics appears in the Pacific. In the Atlantic, negative anomalies are located in the North Atlantic, while the corresponding sea level pressure anomaly (SLPA) composite resembles a North Atlantic Oscillation (NAO) pattern. After the establishment of the NAG, a pattern with the band structure of alternating positive and negative anomalies with warming in the STA appears 6 years later in the Atlantic. In the Pacific, warm SSTAs shift from the date line to the eastern Pacific three to four years Later after the ENSO-like pattern appears. Soon after, a wave train extends from the Pacific to the tip of Argentina and negative anomalies appear in the South Atlantic. Warming starts in the STA. While SSTAs in the Pacific and the Atlantic may not vary as a single mode. two oceans interact when SSTAs in the Pacific are strong enough to generate downstream responses. These anomalies in turn contribute to the variations of SSTAs over the STA. C1 NOAA, NWS, NCEP, Climate Predict Ctr, Camp Springs, MD 20746 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Mo, KC (reprint author), NOAA, NWS, NCEP, Climate Predict Ctr, 5200 Auth Rd, Camp Springs, MD 20746 USA. RI Hakkinen, Sirpa/E-1461-2012 NR 13 TC 13 Z9 15 U1 0 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 MAY 15 PY 2001 VL 28 IS 10 BP 2065 EP 2068 DI 10.1029/2000GL012448 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 431EB UT WOS:000168617900043 ER PT J AU Wright, T Parsons, B Fielding, E AF Wright, T Parsons, B Fielding, E TI Measurement of interseismic strain accumulation across the North Anatolian Fault by satellite radar interferometry SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EARTHS SURFACE; EARTHQUAKE; MOTION; DEFORMATION; LITHOSPHERE; TOPOGRAPHY; CALIFORNIA; FIELD; ZONE AB In recent years, interseismic crustal velocities and strains have been determined for a number of tectonically active areas through repeated measurements using the Global Positioning System. The terrain in such areas is often remote and difficult. and the density of GPS measurements relatively sparse. In principle, satellite radar interferometry can be used to make millimetric-precision measurements of surface displacement over large surface areas. In practice, the small crustal deformation signal is dominated over short time intervals by errors due to atmospheric, topographic and orbital effects. Here we show that these effects can be overcome by stacking multiple interferograms, after screening for atmospheric anomalies, effectively creating a new interferogram that covers a longer time interval. In this way, we have isolated a 70 km wide region of crustal deformation across the eastern end of the North Anatolian Fault, Turkey. The distribution of deformation is consistent with slip of 17-32 mm/yr below 5-33 km on the extension of the surface fault at depth. If the GPS determined slip rate of 24 +/-1 mm/yr is accepted, the locking depth is constrained to 18 +/-6 km. C1 Univ Oxford, Dept Earth Sci, Oxford OX1 3PR, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wright, T (reprint author), Univ Oxford, Dept Earth Sci, Parks Rd, Oxford OX1 3PR, England. RI Wright, Tim/A-5892-2011; Parsons, Barry/K-4716-2012; Fielding, Eric/A-1288-2007 OI Wright, Tim/0000-0001-8338-5935; Fielding, Eric/0000-0002-6648-8067 NR 23 TC 99 Z9 101 U1 0 U2 4 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 MAY 15 PY 2001 VL 28 IS 10 BP 2117 EP 2120 DI 10.1029/2000GL012850 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 431EB UT WOS:000168617900056 ER PT J AU Qiao, D Jia, L Yu, LS Asbeck, PM Lau, SS Lim, SH Liliental-Weber, Z Haynes, TE Barner, JB AF Qiao, D Jia, L Yu, LS Asbeck, PM Lau, SS Lim, SH Liliental-Weber, Z Haynes, TE Barner, JB TI Ta-based interface ohmic contacts to AlGaN/GaN heterostructures SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID FIELD-EFFECT TRANSISTORS; N-ALGAN; GAN; POLARIZATION; CHARGE; TI/AL AB Al/Ti based metallization is commonly used for ohmic contacts to n-GaN and related compounds. We have previously reported an ohmic contact scheme specially designed for AlGaN/GaN heterostructure field-effect transistors (HFETs) [D. Qiao , Appl. Phys. Lett. 74, 2652 (1999)]. This scheme, referred to as the "advancing interface" contact, takes advantage of the interfacial reactions between the metal layers and the AlGaN barrier layer in the HFET structure. These reactions consume a portion of the barrier, thus facilitating carrier tunneling from the source/drain regions to the channel region. The advancing interface approach has led to consistently low contact resistance on Al0.25Ga0.75N/GaN HFETs. There are two drawbacks of the Al/Ti based advancing interface scheme, (i) it requires a capping layer for the ohmic formation annealing since Ti is too reactive and is easily oxidized when annealing is performed in pure N-2 or even in forming gas, and (ii) the atomic number of Al and that of Ti are too low to yield efficient backscattered electron emission for e-beam lithographic alignment purposes. In this work, we investigated a Ta based advancing interface contact scheme for the HFET structures. We found that the presence of Ta in this ohmic scheme leads to (1) a specific contact resistivity as low as 5x10(-7) Omega cm(2), (2) efficient electron emission for e-beam lithographic alignment, and (3) elimination of the capping layer for the ohmic annealing. (C) 2001 American Institute of Physics. C1 Univ Calif San Diego, La Jolla, CA 92093 USA. Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA. RP Univ Calif San Diego, La Jolla, CA 92093 USA. EM dqiao@ucsd.edu RI Liliental-Weber, Zuzanna/H-8006-2012; Haynes, Tony/P-8932-2015 OI Haynes, Tony/0000-0003-2871-4745 NR 19 TC 25 Z9 26 U1 2 U2 11 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0021-8979 EI 1089-7550 J9 J APPL PHYS JI J. Appl. Phys. PD MAY 15 PY 2001 VL 89 IS 10 BP 5543 EP 5546 DI 10.1063/1.1365431 PG 4 WC Physics, Applied SC Physics GA 428AF UT WOS:000168438400047 ER PT J AU De Boer, G Arepalli, S Holmes, W Nikolaev, P Range, C Scott, C AF De Boer, G Arepalli, S Holmes, W Nikolaev, P Range, C Scott, C TI Detection of nickel atom by laser induced fluorescence during carbon nanotube formation in a laser produced plume SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID TEMPERATURE-MEASUREMENTS; OPTICAL-EMISSION; INDUCED PLASMA; GROWTH; ABLATION; VAPORIZATION; ND1.85CE0.15CUO4; SPECTROSCOPY; DYNAMICS; C-2 AB In situ monitoring of catalyst nickel atoms by laser induced fluorescence during carbon nanotube formation in a laser-produced plume was performed at the Johnson Space Center nanotube production laboratory. The results indicate that ablation of nickel and plume dynamics are strongly related to the oven temperature. Nickel atoms have a long lifetime of several milliseconds and have an electronic temperature of at least 1500 K during carbon nanotube formation. (C) 2001 American Institute of Physics. C1 LeTourneau Univ, Dept Chem & Phys, Longview, TX 75602 USA. NASA, GB Technol, JSC, Houston, TX 77058 USA. RP De Boer, G (reprint author), LeTourneau Univ, Dept Chem & Phys, 2100 S Mobberly, Longview, TX 75602 USA. RI Arepalli, Sivaram/A-5372-2010; Nikolaev, Pavel/B-9960-2009 NR 46 TC 18 Z9 18 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD MAY 15 PY 2001 VL 89 IS 10 BP 5760 EP 5768 DI 10.1063/1.1365441 PG 9 WC Physics, Applied SC Physics GA 428AF UT WOS:000168438400087 ER PT J AU Comiso, JC Wadhams, P Pedersen, LT Gersten, RA AF Comiso, JC Wadhams, P Pedersen, LT Gersten, RA TI Seasonal and interannual variability of the Odden ice tongue and a study of environmental effects SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID NORTH-ATLANTIC OSCILLATION; SEA-ICE; GREENLAND SEA; PASSIVE MICROWAVE; SATELLITE AB The Odden ice tongue is an ice cover phenomenon in the Greenland Sea that covers all or part of the area of influence of the Jan Mayen Current and that encloses a bay of open water called Nordbukta. The yearly attributes of the spatial distribution of the Odden from 1979 through 1998 have been quantified in terms of average concentration, standard deviation of ice concentrations, persistence, maximum extent, and anomalies in extent, and the results show vastly different formation characteristics and seasonalities during different years. The monthly average extents of the Odden are shown to have a strong negative correlation with monthly surface air temperatures recorded at Jan Mayen Island and monthly temperatures retrieved from satellite infrared data, with correlation coefficients of 0.74 and 0.89, respectively. Wind effect is also shown to be an important factor at daily and shorter timescales, directly influencing size and shape and sometimes initiating the formation of Nordbukta. The Odden was most extensive in 1979, 1982, 1986 and 1997 and most persistent in 1988, 1989, and 1997 but did not appear in 1984, 1994. and 1995, suggesting decadal periodicity for the 20 year period. With the use of the 75 year temperature record at Jan Mayen Island as a proxy for Odden size, spectral analysis also shows a periodicity of 10-12 years. A correlation study of North Atlantic Oscillation (NAO) indices with extents of the Odden, as derived from satellite data, yields a correlation coefficient of 0.4, which suggests that the interannual variability of the Odden may be influenced but not controlled by NAG. Regression analysis of the Jan Mayen surface temperature record also yields a slight warming (0.06 K decade (-1)) and a decrease in Odden area (-0.14 x 10(4) km(2) decade(-1)) from 1979 to 1996, but during the past 75 years, there has actually been a slight cooling (-0.15 K decade(-1)), suggesting either that the Odden had actually been smaller in size several decades ago or that it had occurred farther north. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. Univ Cambridge, Scott Polar Res Inst, Cambridge CB2 1ER, England. Tech Univ Denmark, Inst Electromagnet, DK-2800 Lyngby, Denmark. Sci Syst & Applicat Inc, Lanham, MD 20706 USA. RP Comiso, JC (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Code 971, Greenbelt, MD 20771 USA. NR 34 TC 24 Z9 24 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-OCEANS JI J. Geophys. Res.-Oceans PD MAY 15 PY 2001 VL 106 IS C5 BP 9093 EP 9116 DI 10.1029/2000JC000204 PG 24 WC Oceanography SC Oceanography GA 431VW UT WOS:000168653300009 ER PT J AU Song, YT Haidvogel, DB Glenn, SM AF Song, YT Haidvogel, DB Glenn, SM TI Effects of topographic variability on the formation of upwelling centers off New Jersey: A theoretical model SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID COASTAL TRANSITION ZONE; CIRCULATION; DYNAMICS; BOUNDARY; SYSTEM AB A theoretical wind-driven, continuously stratified coastal ocean model with varying topography is developed to examine the formation of upwelling centers in coastal oceans, such as those observed along the New Jersey coast. In this simple model an Ekman transport layer is induced by a wind-driven shear friction profile to force the coastal ocean. An analytical perturbation solution, including a component of internal Kelvin waves, is solved for the coastal upwelling system with weak alongshore-varying topography. Under uniformly upwelling favorable winds, the model solutions show that alongshore-varying topography leads to the formation of upwelling centers along the coast by increasing upwelling on the downslope sides of topographic highs and decreasing upwelling on the upslope sides of topographic highs, similar to the observed features off the New Jersey coast during summer seasons. A conservation theorem is derived that indicates the topographic variation does not change the total amount of upwelled water but redistributes it unevenly along the coast to form enhanced upwelling centers. The theory suggests that alongshore-varying topography plays an important role in controlling the formation of upwelling centers as it enhances upwelling at some locations and induces downwelling at others. In addition, the variations of the upwelling fronts are further complicated by the topographically trapped Kelvin waves. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Rutgers State Univ, Inst Marine & Coastal Sci, New Brunswick, NJ 08901 USA. RP Song, YT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 22 TC 46 Z9 46 U1 2 U2 3 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 MAY 15 PY 2001 VL 106 IS C5 BP 9223 EP 9240 DI 10.1029/2000JC000244 PG 18 WC Oceanography SC Oceanography GA 431VW UT WOS:000168653300017 ER PT J AU Hartmann, MJ Bower, JM AF Hartmann, MJ Bower, JM TI Tactile responses in the granule cell layer of cerebellar folium Crus IIa of freely behaving rats SO JOURNAL OF NEUROSCIENCE LA English DT Article DE cerebellar granule cells; mossy fibers; somatosensory; ingestive; grooming; exploration; whiskers; vibrissae; passive touch; active touch; active sensing ID INFERIOR OLIVE; PURKINJE-CELLS; MOTOR CONTROL; SOMATOSENSORY CORTEX; DISCHARGE PATTERNS; MOSSY FIBER; PROJECTIONS; NEURONS; NUCLEUS; ORGANIZATION AB We recorded activity from the granule cell layer (GCL) of cerebellar folium Crus IIa as freely moving rats engaged in a variety of natural behaviors, including grooming, eating, and free tactile exploration. Multiunit responses in the 1000- 4500 Hz range were found to be strongly correlated with tactile stimulation of lip and whisker (perioral) regions. These responses occurred regardless of whether the stimulus was externally or self-generated and during both active and passive touch. In contrast, perioral movements that did not tactually stimulate this region of the face (e. g., chewing) produced no detectable increases in GCL activity. In addition, GCL responses were not correlated with movement extremes. When rats used their lips actively for palpation and exploration, the tactile responses in the GCL were not detectably modulated by ongoing jaw movements. However, active palpation and exploratory behaviors did result in the largest and most continuous bursts of GCL activity: responses were on average 10% larger and 50% longer during palpation and exploration than during grooming or passive stimulation. Although activity levels differed between behaviors, the position and spatial extent of the peripheral receptive field was similar over all behaviors that resulted in tactile input. Overall, our data suggest that the 1000- 4500 Hz multiunit responses in the Crus IIa GCL of awake rats are correlated with tactile input rather than with movement or any movement parameter and that these responses are likely to be of particular importance during the acquisition of sensory information by perioral structures. C1 CALTECH, Dept Biol, Pasadena, CA 91125 USA. RP Hartmann, MJ (reprint author), CALTECH, Jet Prop Lab, MC 303-300,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Hartmann, Mitra/A-8150-2008; Hartmann, Mitra/B-6766-2009; Bower, James/F-8343-2010 NR 70 TC 51 Z9 51 U1 0 U2 3 PU SOC NEUROSCIENCE PI WASHINGTON PA 11 DUPONT CIRCLE, NW, STE 500, WASHINGTON, DC 20036 USA SN 0270-6474 J9 J NEUROSCI JI J. Neurosci. PD MAY 15 PY 2001 VL 21 IS 10 BP 3549 EP 3563 PG 15 WC Neurosciences SC Neurosciences & Neurology GA 427MQ UT WOS:000168409400030 PM 11331384 ER PT J AU Klimeck, G Bowen, RC Boykin, TB AF Klimeck, G Bowen, RC Boykin, TB TI Off-zone-center or indirect band-gap-like hole transport in heterostructures SO PHYSICAL REVIEW B LA English DT Article ID RESONANT-TUNNELING-DIODE; CURRENT-VOLTAGE CALCULATIONS; TIGHT-BINDING PARAMETERS; INTERFACE ROUGHNESS; SEMICONDUCTOR STRUCTURES; APPROXIMATION; SIMULATIONS; SCATTERING; DEVICES; MODELS AB Unintuitive hole transport phenomena through heterostructures are presented. It is shown that for large bias ranges the majority of carriers travel outside the Gamma zone center (i.e., more carriers travel through the structure at an angle than straight through). Strong interaction of heavy-, light-, and split-off hole bands due to heterostructure interfaces present in devices such as resonant tunneling diodes, quantum-well photodetectors, and lasers are shown to be the cause. The result is obtained by careful numerical analysis of the hole transport as a function of the transverse momentum k in a resonant tunneling diode within the framework of a sp3s* second-nearest-neighbor tight-binding model. Three independent mechanisms that generate off-zone-center current flow are explained: (1) nonmonotonic (electronlike) hole dispersion, (2) lighter quantum well than emitter effective masses, and (3) strongly momentum-dependent quantum-well coupling strength due to state anticrossings. Finally a simulation is compared to experimental data to exemplify the importance of a full numerical transverse momentum integration versus a Tsu-Esaki approximation. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Alabama, Dept Elect & Comp Engn, Huntsville, AL 35899 USA. Univ Alabama, LICOS, Huntsville, AL 35899 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM gekco@jpl.nasa.g RI Klimeck, Gerhard/A-1414-2012 OI Klimeck, Gerhard/0000-0001-7128-773X NR 39 TC 11 Z9 11 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9950 EI 2469-9969 J9 PHYS REV B JI Phys. Rev. B PD MAY 15 PY 2001 VL 63 IS 19 AR 195310 DI 10.1103/PhysRevB.63.195310 PG 9 WC Physics, Condensed Matter SC Physics GA 434KT UT WOS:000168814200055 ER PT J AU Lee, S Jonsson, L Wilkins, JW Bryant, GW Klimeck, G AF Lee, S Jonsson, L Wilkins, JW Bryant, GW Klimeck, G TI Electron-hole correlations in semiconductor quantum dots with tight-binding wave functions SO PHYSICAL REVIEW B LA English DT Article ID POROUS SILICON; TUNNELING SPECTROSCOPY; CDSE NANOCRYSTALS; SI NANOCRYSTALS; INAS; CONFINEMENT; STATES; INP; IDENTIFICATION; LUMINESCENCE AB The electron-hole states of semiconductor quantum dots are investigated within the framework of empirical tight-binding descriptions for Si, as an example of an indirect-gap material, and InAs and CdSe as examples of typical III-V and II-VI direct-gap materials. We significantly improve the energies of the single-particle states by optimizing tight-binding parameters to give the best effective masses. As a result, the calculated excitonic gaps agree within 5% error with recent photoluminescence data for Si and CdSe but they agree less well for InAs. The electron-hole Coulomb interaction is insensitive to different ways of optimizing the tight-binding parameters. However, it is sensitive to the choice of atomic orbitals; this sensitivity decreases with increasing dot size. Quantitatively, tight-binding treatments of Coulomb interactions are reliable for dots with radii larger than 15-20 Angstrom. Further, the effective range of the electron-hole exchange interaction is investigated in detail. In quantum dots of the direct-gap materials InAs and CdSe, the exchange interaction can be long ranged, extending over the whole dot when there is no local (onsite) orthogonality between the electron and hole wave functions. By contrast, for Si quantum dots the extra phase factor due to the indirect gap effectively limits the range to about 15 Angstrom, independent of the dot size. C1 Ohio State Univ, Dept Phys, Columbus, OH 43210 USA. Natl Inst Stand & Technol, Gaithersburg, MD 20899 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ohio State Univ, Dept Phys, 174 W 18th Ave, Columbus, OH 43210 USA. RI Klimeck, Gerhard/A-1414-2012 OI Klimeck, Gerhard/0000-0001-7128-773X NR 44 TC 83 Z9 83 U1 1 U2 10 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9950 EI 2469-9969 J9 PHYS REV B JI Phys. Rev. B PD MAY 15 PY 2001 VL 63 IS 19 AR 195318 DI 10.1103/PhysRevB.63.195318 PG 13 WC Physics, Condensed Matter SC Physics GA 434KT UT WOS:000168814200063 ER PT J AU Srivastava, D Menon, M Cho, K AF Srivastava, D Menon, M Cho, K TI Anisotropic nanomechanics of boron nitride nanotubes: Nanostructured "skin" effect SO PHYSICAL REVIEW B LA English DT Article ID CARBON NANOTUBES; BN NANOTUBES; SUBSTITUTION-REACTION; MOLECULAR-DYNAMICS; TUBULES; MICROTUBULES; FILAMENTS; GROWTH; SCHEME AB The stiffness and plasticity of boron nitride nanotubes an investigated using generalized tight-binding molecular dynamics and ab initio total energy methods. Due to boron nitride (BN) bond rotation effect, compressed zigzag BN nanotubes are found to undergo anisotropic strain release followed by anisotropic plastic buckling. The strain is preferentially released toward N atoms in the rotated BN bonds. The tubes buckle anisotropically toward only one end when uniaxially compressed from both. A "skin-effect" model of smart nanocomposite materials is proposed, which localizes the structural damage toward the skin or surface side of the material. C1 NASA, Ames Res Ctr, CSC, Moffett Field, CA 94035 USA. Univ Kentucky, Dept Phys & Astron, Lexington, KY 40506 USA. Univ Kentucky, Ctr Computat Sci, Lexington, KY 40506 USA. Stanford Univ, Dept Mech Engn, Stanford, CA 94305 USA. RP Srivastava, D (reprint author), NASA, Ames Res Ctr, CSC, Mail Stop T27-A1, Moffett Field, CA 94035 USA. EM deepak@nas.nasa.gov; super250@pop.uky.edu NR 27 TC 42 Z9 44 U1 0 U2 8 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 EI 1550-235X J9 PHYS REV B JI Phys. Rev. B PD MAY 15 PY 2001 VL 63 IS 19 AR 195413 DI 10.1103/PhysRevB.63.195413 PG 5 WC Physics, Condensed Matter SC Physics GA 434KT UT WOS:000168814200083 ER PT J AU Krolak, A Tinto, M AF Krolak, A Tinto, M TI Resampled random processes in gravitational-wave data analysis SO PHYSICAL REVIEW D LA English DT Article AB The detection of continuous gravitational-wave signals requires taking into account the motion of the detector with respect to the solar system barycenter in the data analysis. In order to search efficiently for such signals by means of the fast Fourier transform the data need to be transformed from the topocentric time to the barycentric time by means of resampling. The resampled data form a nonstationary random process. In this Brief Report we prove that this nonstationary random process is mathematically well defined, and show that generalizations of the fundamental results for stationary processes, such as the Wiener-Khintchine theorem and Cramer representation, exist. C1 Polish Acad Sci, Inst Math, PL-00950 Warsaw, Poland. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Krolak, A (reprint author), Polish Acad Sci, Inst Math, Sniadeckich 8, PL-00950 Warsaw, Poland. EM krolak@impan.gov.pl; massimo.tinto@jpl.nasa.gov NR 5 TC 0 Z9 0 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1550-7998 EI 1550-2368 J9 PHYS REV D JI Phys. Rev. D PD MAY 15 PY 2001 VL 63 IS 10 AR 107101 PG 4 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 434RV UT WOS:000168830400073 ER PT J AU Phillips, NG Hu, BL AF Phillips, NG Hu, BL TI Noise kernel in stochastic gravity and stress energy bitensor of quantum fields in curved spacetimes SO PHYSICAL REVIEW D LA English DT Article ID WEAKLY INHOMOGENEOUS COSMOLOGIES; SEMICLASSICAL GRAVITY; BROWNIAN-MOTION; POINT-SEPARATION; BACK-REACTION; GRAVITATIONAL-FIELD; GENERAL ENVIRONMENT; LANGEVIN EQUATION; INTEGRAL APPROACH; FLUCTUATIONS AB The noise kernel is the vacuum expectation value of the (operator-valued) stress-energy bitensor which describes fluctuations of a quantum field in curved spacetimes. It plays the role in stochastic semiclassical gravity based on the Einstein-Langevin equation similar to the expectation value of the stress-energy tensor in semiclassical gravity based on the semiclassical Einstein equation. According to the stochastic gravity program, this two-point function (and by extension the higher-order correlations in a hierarchy) of the stress energy tensor possesses precious statistical-mechanical information of quantum fields in curved spacetime and, by the self-consistency required of Einstein's equation, provides a probe into the coherence properties of the gravity sector (as measured by the higher-order correlation functions of gravitons) and the quantum and/or extended nature of spacetime. It reflects the medium energy (referring to Planck energy as high energy) or mesoscopic behavior of any viable theory of quantum gravity, including string theory. The stress energy bitensor could be the starting point for a new quantum field theory constructed on spacetimes with extended structures. In the coincidence limit we use the method of point separation to derive a regularized noise-kernel for a scalar field in general curved spacetimes. It is useful for calculating quantum fluctuations of fields in modem theories of structure formation and for back reaction problems in the early universe and black holes. One collorary of our finding is that for a massless conformal field the trace of the noise kernel identically vanishes. We outline how the general framework and results derived here can be used for the calculation of noise kernels for specific cases of physical interest such as Robertson-Walker and Schwarzschild spacetimes. C1 NASA, Raytheon ITSS, Astron & Solar Phys Lab, GSFC, Greenbelt, MD 20771 USA. Univ Maryland, Dept Phys, College Pk, MD 20742 USA. RP Phillips, NG (reprint author), NASA, Raytheon ITSS, Astron & Solar Phys Lab, GSFC, Code 685, Greenbelt, MD 20771 USA. EM nicholas.g.phillips@gsfc.nasa.gov; hub@physics.umd.edu NR 56 TC 29 Z9 29 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 MAY 15 PY 2001 VL 63 IS 10 AR 104001 DI 10.1103/PhysRevD.63.104001 PG 16 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 434RV UT WOS:000168830400023 ER PT J AU Kanik, I Johnson, PV James, GK AF Kanik, I Johnson, PV James, GK TI Electron-impact-induced emission and excitation cross sections of xenon at low energies SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID DISTORTED-WAVE CALCULATION; ULTRAVIOLET EMISSION; EXTREME-ULTRAVIOLET; VACUUM-ULTRAVIOLET; NOBLE-GASES; XE; CALIBRATION; REGION AB Electron-impact-induced emission spectra of Xe corresponding to the resonance transitions in the FUV spectral region from 114-165 nm at 15, 20 and 30 eV impact energies are reported. Absolute emission cross sections corresponding to the Xe I spectral features at 15, 20 and 30 eV impact energies and optical excitation functions for the two most prominent transitions at 119.2 and 147.0 nm in the 0-100 eV energy range were measured. In addition, the integral cross sections for direct electron-impact excitation of the corresponding levels in Xe, obtained by integration of the differential cross section measurements of Khakoo et al (Khakoo M A et al 1996 J. Phys. B: At. Mel. Opt. Phys. 29 3455, Khakoo M A et al 1996 J. Phys. B: At. Mol. Opt. Phys. 29 3477) are compared with the present results and the theoretical calculations of Csanak (Csanak G 1996 Private communication). A comparison of the measured emission and integrated direct excitation cross sections is made leading to indirect estimation of the cascade contributions to the emission cross sections. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kanik, I (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Johnson, Paul/D-4001-2009 OI Johnson, Paul/0000-0002-0186-8456 NR 26 TC 4 Z9 4 U1 0 U2 3 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD MAY 14 PY 2001 VL 34 IS 9 BP 1685 EP 1693 DI 10.1088/0953-4075/34/9/307 PG 9 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 435VZ UT WOS:000168904000011 ER PT J AU Stolte, WC Hansen, DL Piancastelli, MN Lopez, ID Rizvi, A Hemmers, O Wang, H Schlachter, AS Lubell, MS Lindle, DW AF Stolte, WC Hansen, DL Piancastelli, MN Lopez, ID Rizvi, A Hemmers, O Wang, H Schlachter, AS Lubell, MS Lindle, DW TI Anionic photofragmentation of CO: A selective probe of core-level resonances SO PHYSICAL REVIEW LETTERS LA English DT Article ID OXYGEN K-EDGE; POST-COLLISION INTERACTION; ION-YIELD SPECTROSCOPY; SHAPE RESONANCE; POSTCOLLISION-INTERACTION; C(1S) EXCITATION; AUGER PROCESSES; MOLECULES; PHOTOIONIZATION; SHELL AB Anion-yield spectroscopy using x rays is shown to be a selective probe of molecular core-level processes, providing unique experimental verification of shape resonances. For CO, partial anion and cation yields are presented for photon energies near the C K edge. The O- yield exhibits features above threshold related only to doubly excited states, in contrast to cation yields which also exhibit pronounced structure due to the well-known sigma* shape resonance. Because the shape resonance is completely suppressed for O-, anion spectroscopy thus constitutes a highly selective probe, yielding information unobtainable with absorption or electron spectroscopy. C1 Univ Nevada, Dept Chem, Las Vegas, NV 89154 USA. Lawrence Berkeley Lab, Adv Light Source, Berkeley, CA 94720 USA. CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. Univ Roma Tor Vergata, Dept Chem Sci & Technol, I-00133 Rome, Italy. Ctr Nacl Metrol, Queretaro 76900, Mexico. Univ Lund, Max Lab, S-22100 Lund, Sweden. CUNY City Coll, Dept Phys, New York, NY 10031 USA. RP Stolte, WC (reprint author), Univ Nevada, Dept Chem, Las Vegas, NV 89154 USA. OI Dominguez-Lopez, Ivan/0000-0001-8084-8711 NR 33 TC 48 Z9 48 U1 2 U2 9 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 MAY 14 PY 2001 VL 86 IS 20 BP 4504 EP 4507 DI 10.1103/PhysRevLett.86.4504 PG 4 WC Physics, Multidisciplinary SC Physics GA 431GM UT WOS:000168623500020 PM 11384269 ER PT J AU Dolan, JF AF Dolan, JF TI Astronomy - How to find a stellar black hole SO SCIENCE LA English DT Editorial Material C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Dolan, JF (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. NR 14 TC 1 Z9 1 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD MAY 11 PY 2001 VL 292 IS 5519 BP 1079 EP 1080 DI 10.1126/science.1061665 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 431AF UT WOS:000168609200035 PM 11352057 ER PT J AU Jackson, DJ Juncosa, ML AF Jackson, DJ Juncosa, ML TI Error analysis of high data rate, optical parallel processors SO APPLIED OPTICS LA English DT Article ID SYSTEMS AB Optical parallel processors have the potential for aiding the transfer of information over networks. The systems implications for a baseline architecture employing spatial light modulators, lenses, and charge-coupled devices are examined. Specifically, because many applications have stringent requirements on errors, this study concentrates on categorizing the potential error sources-both random and systematic-and presents the results of an error analysis for a pixel-to-pixel mapping system as a notional example. (C) 2001 Optical Society of America. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RAND Corp, Santa Monica, CA 90407 USA. RP Jackson, DJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM deborah.jackson@jpl.nasa.gov NR 14 TC 2 Z9 2 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 MAY 10 PY 2001 VL 40 IS 14 BP 2253 EP 2266 DI 10.1364/AO.40.002253 PG 14 WC Optics SC Optics GA 430UW UT WOS:000168594700003 PM 18357233 ER PT J AU Stanford, SA Holden, B Rosati, P Tozzi, P Borgani, S Eisenhardt, PR Spinrad, H AF Stanford, SA Holden, B Rosati, P Tozzi, P Borgani, S Eisenhardt, PR Spinrad, H TI The intracluster medium in z > 1 galaxy clusters SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : clusters : general; X-rays : general ID X-RAY AB The Chandra X-Ray Observatory was used to obtain a 190 ks image of three high-redshift galaxy clusters in one observation. The results of our analysis of these data are reported for the two z > 1 clusters in this Lynx field, which are the most distant known X-ray luminous clusters. Spatially extended X-ray emission was detected from both these clusters, indicating the presence of hot gas in their intracluster media. A fit to the X-ray spectrum of RX J0849 + 4452 at z = 1.26 yields a temperature of kT = 5.8(-1.7)(+2.8) keV. Using this temperature and the assumption of an isothermal sphere, the total mass of RX J0849+4452 is found to be 4.01(-1.9)(+2.4) x 10(14) h(65)(-1) M. within r = 1 h(65)(-1) Mpc. The T-X for RX J0849+4452 approximately agrees with the expectation based on its L-bol = 3.3(-0.5)(+0.9) x 10(44) ergs s(-1) according to the low-redshift L-X-T-X relation. The very different distributions of X-ray-emitting gas and of the red member galaxies in the two z > 1 clusters, in contrast to the similarity of the optical/IR colors of those galaxies, suggests that the early-type galaxies mostly formed before their host clusters. C1 Univ Calif Davis, Dept Phys, Davis, CA 95616 USA. European So Observ, D-85748 Garching, Germany. Osservatorio Astron Trieste, I-34131 Trieste, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. RP Stanford, SA (reprint author), Univ Calif Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94550 USA. NR 21 TC 75 Z9 75 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 MAY 10 PY 2001 VL 552 IS 2 BP 504 EP 507 DI 10.1086/320583 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 439TM UT WOS:000169133700010 ER PT J AU Harrus, IM Slane, PO Smith, RK Hughes, JP AF Harrus, IM Slane, PO Smith, RK Hughes, JP TI A new ASCA and ROSAT study of the supernova remnant G272.2-3.2 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : individual (G272.2-3.2); shock waves; supernova remnants; X-rays : ISM ID FORMED DENSE SHELL; X-RAY-EMISSION; INTERSTELLAR-MEDIUM; THERMAL CONDUCTION; MODELING W44; HOT INTERIOR; GRADIENT; CLOUDS; PLASMA; SOLAR AB G272.2-3.2 is a supernova remnant (SNR) characterized by an apparent centrally brightened X-ray morphology and thermally dominated X-ray emission. Because of this combination of Sedov-type (thermal emission) and non-Sedov-type (non-shell-like morphology) features, the remnant is classified as a "thermal composite" SNR. This class of remnant is still poorly understood, in part because of the difficulties in modeling accurately all the physical conditions which shape the emission morphology. This paper presents a combined analysis of data from the ASCA and ROSAT satellites coupled with previous results at other wavelengths. We find that the X-ray emission from G272.2-3.2 is best described by a nonequilibrium ionization (NEI) model with a temperature around 0.70 keV, an ionization timescale of 3200 cm(-3) yr, and a relatively high column density (N-H similar to 10(22) atoms cm(-2)). We look into the possible explanations for the apparent morphology of G272.2-3.2 using several models (among which are both cloud evaporation and thermal conduction models). For each of the models considered, we examine all the implications on the evolution of G272.2-3.2. C1 NASA, Goddard Space Flight Ctr, USRA, Greenbelt, MD 20771 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Rutgers State Univ, Piscataway, NJ 08854 USA. RP Harrus, IM (reprint author), NASA, Goddard Space Flight Ctr, USRA, Bldg 2,Code 662, Greenbelt, MD 20771 USA. NR 32 TC 18 Z9 18 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 MAY 10 PY 2001 VL 552 IS 2 BP 614 EP 623 DI 10.1086/320577 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 439TM UT WOS:000169133700018 ER PT J AU Woods, PM Kouveliotou, C Gogus, E Finger, MH Swank, J Smith, DA Hurley, K Thompson, C AF Woods, PM Kouveliotou, C Gogus, E Finger, MH Swank, J Smith, DA Hurley, K Thompson, C TI Evidence for a sudden magnetic field reconfiguration in soft gamma repeater 1900+14 SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : individual (SGR 1900+14); stars : magnetic fields; X-rays : bursts ID VARIABLE SPIN-DOWN; X-RAY PULSAR; SGR 1900+14; BURST ACTIVITY; NEUTRON-STARS; SGR-1900+14; SGR1900+14; OUTBURST AB We report the detection of large flux changes in the persistent X-ray flux of soft gamma repeater (SGR) 1900+14 during its burst active episode in 1998. Most notably, we find a factor of similar to 700 increase in the nonburst X-ray flux following the August 27 flare, which decayed in time as a power law. Our measurements indicate that the pulse fraction remains constant throughout this decay. This suggests a global flux enhancement as a consequence of the August 27 flare rather than localized heating. While the persistent flux has since recovered to the preoutburst level, the pulse profile has not. The pulse shape changed to a near sinusoidal profile within the tail of the August 27 flare (in gamma -rays), and this effect has persisted for more than 1.5 years (in X-rays). The results presented here suggest that the magnetic field of the neutron star in SGR 1900+14 was significantly altered (perhaps globally) during the giant flare of August 27. C1 Univ Space Res Assoc, Columbia, MD 21044 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. MIT, Dept Phys, Cambridge, MA 02138 USA. MIT, Ctr Space Res, Cambridge, MA 02138 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Canadian Inst Theoret Phys, Toronto, ON M5S 3H8, Canada. RP Woods, PM (reprint author), Univ Space Res Assoc, Columbia, MD 21044 USA. RI Swank, Jean/F-2693-2012 NR 28 TC 101 Z9 101 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 MAY 10 PY 2001 VL 552 IS 2 BP 748 EP 755 DI 10.1086/320571 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 439TM UT WOS:000169133700031 ER PT J AU Nitta, NV Sato, J Hudson, HS AF Nitta, NV Sato, J Hudson, HS TI The physical nature of the loop-top X-ray sources in the gradual phase of solar flares SO ASTROPHYSICAL JOURNAL LA English DT Article DE plasmas; Sun : flares; Sun : X-rays, gamma rays ID A MISSION; MAGNETIC RECONNECTION; YOHKOH OBSERVATIONS; FE XXVI; TEMPERATURE; TELESCOPE; PLASMA; IMPROVEMENT; SXT AB We have analyzed Yohkoh soft and hard X-ray images of 36 flares, primarily to study the loop-top source that often prevails in these wavelengths during and following the impulsive phase. There are typically two patterns for the location of the low-energy (15-30 keV) hard X-ray (HXR) source with respect to the soft X-ray (SXR) loop. In a quarter of the flares, the HXR source lies in an extended structure separate from the brightest SXR loop. In other flares, the HXR source appears to be part of the same bipolar structure as the SXR loop, but its centroid is often displaced from the SXR loop-top source. The fact that the HXR source is not cospatial with the SXR source may reflect the presence of a distinct hotter structure. According to Yohkoh X-ray emission-line spectroscopy, the similar to 20 MK plasma accounts for only a fraction of the HXR counts. The temperature maps obtained from the SXR broadband photometry occasionally reveal high-temperature areas outside the bright loop, but they also tend to be displaced from the HXR source, indicating that they do not represent the superhot (greater than or similar to 30 MK) plasma. We discuss possible distributions of plasma of different temperatures that could be consistent with the data. C1 Lockheed Martin Solar & Astrophys Lab, Palo Alto, CA 94304 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Solar Phys Res Corp, Inst Space & Astronaut Sci, Kanagawa 229, Japan. RP Nitta, NV (reprint author), Lockheed Martin Solar & Astrophys Lab, O-L9-41,B-252,3251 Hanover St, Palo Alto, CA 94304 USA. EM nitta@lmsal.com NR 34 TC 10 Z9 10 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2001 VL 552 IS 2 BP 821 EP 832 DI 10.1086/320547 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 439TM UT WOS:000169133700037 ER PT J AU Moore, RL Sterling, AC Hudson, HS Lemen, JR AF Moore, RL Sterling, AC Hudson, HS Lemen, JR TI Onset of the magnetic explosion in solar flares and coronal mass ejections SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : coronal mass ejections (CMEs); Sun : filaments; Sun : flares; Sun : magnetic fields; Sun : X-rays, gamma rays ID X-RAY TELESCOPE; ACTIVE REGIONS; ENERGY-RELEASE; FILAMENT ERUPTIONS; YOHKOH SXT; FIELD; RECONNECTION; CONFIGURATION; PROMINENCES; EVOLUTION AB We present observations of the magnetic field configuration and its transformation in six solar eruptive events that show good agreement with the standard bipolar model for eruptive flares. The observations are X-ray images from the Yohkoh soft X-ray telescope (SXT) and magnetograms from Kitt Peak National Solar Observatory, interpreted together with the 1-8 Angstrom X-ray flux observed by GOES. The observations yield the following interpretation. (1) Each event is a magnetic explosion that occurs in an initially closed single bipole in which the core field is sheared and twisted in the shape of a sigmoid, having an oppositely curved elbow on each end. The arms of the opposite elbows are sheared past each other so that they overlap and are crossed low above the neutral line in the middle of the bipole. The elbows and arms seen in the SXT images are illuminated strands of the sigmoidal core held, which is a continuum of sheared/twisted held that fills these strands as well as the space between and around them. (2) Although four of the explosions are ejective (appearing to blow open the bipole) and two are confined (appearing to be arrested within the closed bipole), all six begin the same way. In the SXT images, the explosion begins with brightening and expansion of the two elbows together with the appearance of short bright sheared loops low over the neutral line under the crossed arms and, rising up from the crossed arms, long strands connecting the far ends of the elbows. (3) All six events are single-bipole events in that during the onset and early development of the explosion they show no evidence for reconnection between the exploding bipole and any surrounding magnetic fields. We conclude that in each of our events the magnetic explosion was unleashed by runaway tether-cutting via implosive/explosive reconnection in the middle of the sigmoid, as in the standard model. The similarity of the onsets of the two confined explosions to the onsets of the four ejective explosions and their agreement with the model indicate that runaway reconnection inside a sheared core field can begin whether or not a separate system of overlying fields, or the structure of the bipole itself, allows the explosion to be ejective. Because this internal reconnection apparently begins at the very start of the sigmoid eruption and grows in step with the explosion, we infer that this reconnection is essential for the onset and growth of the magnetic explosion in eruptive hares and coronal mass ejections. C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. Inst Space & Astronaut Sci, Yohkoh, Sagamihara, Kanagawa 229, Japan. Lockheed Martin, Solar & Astrophys Lab, Palo Alto, CA 94304 USA. RP Moore, RL (reprint author), NASA, George C Marshall Space Flight Ctr, Dept Space Sci, SD50, Huntsville, AL 35812 USA. EM ron.moore@msfc.nasa.gov; asterling@solar.stanford.edu; hhudson@solar.stanford.edu; Lemen@sag.lmsal.com NR 55 TC 380 Z9 382 U1 4 U2 15 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2001 VL 552 IS 2 BP 833 EP 848 DI 10.1086/320559 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 439TM UT WOS:000169133700038 ER PT J AU Rhodes, J Refregier, A Groth, EJ AF Rhodes, J Refregier, A Groth, EJ TI Detection of cosmic shear with the Hubble Space Telescope survey strip SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; dark matter; gravitational lensing large-scale; structure of universe ID GALAXIES; Z-SIMILAR-TO-1 AB Weak lensing by large-scale structure provides a unique method to directly measure matter fluctuations in the universe and has recently been detected from the ground. Here we report the first detection of this "cosmic shear" based on space-based images. The detection was derived from the Hubble Space Telescope (HST) Survey Strip (or "Groth Strip"), a 4' x 42' set of 28 contiguous Wide Field Planetary Camera 2 (WFPC2) pointings with I < 27. The small size of the HST point-spread function affords both a lower statistical noise and a much weaker sensitivity to systematic effects, a crucial limiting factor of cosmic shear measurements. Our method and treatment of systematic effects were discussed in an earlier paper. We measure an rms shear of 1.8% on the WFPC2 chip scale (1.'27), in agreement with the predictions of cluster-normalized cold dark matter (CDM) models. Using a maximum likelihood analysis, we show that our detection is significant at the 99.5% confidence level (CL) and measure the normalization of the matter power spectrum to be (8)Ohm (0.48)(m) = 0.51(-0.17)(+0.14), in a Lambda CDM universe. These 68% CL errors include (Gaussian) cosmic variance, systematic effects, and the uncertainty in the redshift distribution of the background galaxies. The signal comes primarily from the chip scale (1.'27) with gradually decreasing contributions up to roughly 10'. Our result is consistent with earlier lensing measurements from the ground and with the normalization derived from cluster abundance. We discuss how our measurement can be improved with the analysis of a large number of independent WFPC2 fields. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Princeton Univ, Dept Phys, Princeton, NJ 08544 USA. Univ Cambridge, Inst Astron, Cambridge CB3 OHA, England. RP Rhodes, J (reprint author), NASA, Goddard Space Flight Ctr, Code 681, Greenbelt, MD 20771 USA. NR 23 TC 52 Z9 53 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 MAY 10 PY 2001 VL 552 IS 2 BP L85 EP L88 DI 10.1086/320336 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 439TN UT WOS:000169133800001 ER PT J AU van Dokkum, PG Stanford, SA Holden, BP Eisenhardt, PR Dickinson, M Elston, R AF van Dokkum, PG Stanford, SA Holden, BP Eisenhardt, PR Dickinson, M Elston, R TI The galaxy population of cluster RX J0848+4453 at z=1.27 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : clusters : individual (RX J0848+4453); galaxies : elliptical and lenticular, cD; galaxies : evolution; galaxies : fundamental parameters; galaxies : interactions ID COLOR-MAGNITUDE RELATION; DISTANT CLUSTERS; EVOLUTION; MORPHOLOGIES; PHOTOMETRY; MS-1054-03; Z=0.83; MODEL AB We present a study of the galaxy population in the IR-selected cluster RX J0848+4453 at z = 1.27, using deep Hubble Space Telescope (HST) NICMOS H-F160W and WFPC2 I-F814W images of the cluster core. We morphologically classify all galaxies to K-s = 20.6 that are covered by the HST imaging and determine photometric redshifts using deep ground-based BRlzJK(s) photometry. Of 22 likely cluster members with morphological classifications, 11 (50%) are classified as early-type galaxies, nine (41%) as spiral galaxies, and two (9%) as "merger/peculiar." At HST resolution, the second brightest cluster galaxy is resolved into a spectacular merger between three red galaxies of similar luminosity, separated from each other by approximate to6 h(50)(-1) kpc, with an integrated magnitude K = 17.6 (similar to 3L(*) at z = 1.27). The two most luminous early-type galaxies also show evidence for recent or ongoing interactions. Mergers and interactions between galaxies are possible because RX J0848+4453 is not yet relaxed. The fraction of early-type galaxies in our sample is similar to that in clusters at 0.5 < z < 1 and consistent with a gradual decrease of the number of early-type galaxies in clusters from z = 0 to z approximate to 1.3. We find evidence that the color-magnitude relation of the early-type galaxies is less steep than in the nearby Coma Cluster. This may indicate that the brightest early-type galaxies have young stellar populations at z = 1.27 but is also consistent with predictions of single-age "monolithic" models with a galactic wind. The scatter in the color-magnitude relation is approximate to0.04 in rest-frame U-V, similar to that in clusters at 0 < z < 1. Taken together, these results show that luminous early-type galaxies exist in clusters at z approximate to 1.3 but that their number density may be smaller than in the local universe. Additional observations are needed to determine whether the brightest early-type galaxies harbor young stellar populations. C1 CALTECH, Pasadena, CA 91125 USA. Univ Calif Davis, Dept Phys, Davis, CA 95616 USA. Univ Calif Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94511 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Florida, Dept Astron, Gainesville, FL 32611 USA. RP van Dokkum, PG (reprint author), CALTECH, MS 105-24, Pasadena, CA 91125 USA. NR 33 TC 64 Z9 64 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 MAY 10 PY 2001 VL 552 IS 2 BP L101 EP L104 DI 10.1086/320335 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 439TN UT WOS:000169133800005 ER PT J AU Skarda, JRL AF Skarda, JRL TI Instability of a gravity-modulated fluid layer with surface tension variation SO JOURNAL OF FLUID MECHANICS LA English DT Article ID DIRECTIONAL SOLIDIFICATION; CONVECTION; BENARD; STABILITY; PLANE; ONSET AB Gravity modulation of an unbounded fluid layer with surface tension variations along its free surface is investigated. The stability of such systems is often characterized in terms of the wavenumber, at and the Marangoni number, Ma. In (alpha ,Ma) parameter space, modulation has a destabilizing effect on the unmodulated neutral stability curve for large Prandtl number, Pr, and small modulation frequency, Omega, while a stabilizing effect is observed for small Pr and large Omega. As Omega --> infinity co the modulated neutral stability curves approach the unmodulated neutral stability curve. At certain values of Pr and Omega, multiple minima are observed and the neutral stability curves become highly distorted. Closed regions of subharmonic instability are also observed. In (1/Omega, g(1)Rn)space, where g(1) is the relative modulation amplitude, and Ra is the Rayleigh number, alternating regions of synchronous and subharmonic instability separated by thin stable regions are observed. However, fundamental differences between the stability boundaries occur when comparing the modulated Marangoni-Benard and Rayleigh-Benard problems. Modulation amplitudes at which instability tongues occur are strongly influenced by Pr, while the fundamental instability region is weakly affected by Pr. For large modulation frequency and small amplitude, empirical relations are derived to determine modulation effects. A one-term Galerkin approximation was also used to reduce the modulated Marangoni-Benard problem to a Mathieu equation, allowing qualitative stability behaviour to be deduced from existing tables or charts, such as Strutt diagrams. In addition, this reduces the parameter dependence of the problem from seven transport parameters to three Mathieu parameters, analogous to parameter reductions of previous modulated Rayleigh-Benard studies. Simple stability criteria, valid for small parameter values (amplitude and damping coefficients), were obtained from the one-term equations using classical method of averaging results. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Skarda, JRL (reprint author), NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. NR 43 TC 14 Z9 14 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI PORT CHESTER PA 110 MIDLAND AVE, PORT CHESTER, NY 10573-9863 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD MAY 10 PY 2001 VL 434 BP 243 EP 271 PG 29 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 435VQ UT WOS:000168903200011 ER PT J AU Lowe, DAJ Parker, RL Purucker, ME Constable, CG AF Lowe, DAJ Parker, RL Purucker, ME Constable, CG TI Estimating the crustal power spectrum from vector Magsat data SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID MAGNETIC-FIELD; CURRENTS; MODEL; OCEAN AB The Earth's magnetic field can be subdivided into core and crustal components and we seek to characterize the crustal part through its spatial power spectrum, R-1. We process vector Magsat data to isolate the crustal field and then invert power spectral densities of flight-local components along-track for R-1 following O'Brien et al. [1999]. Our model, designated LPPC, is accurate up to approximately spherical harmonic degree 45 (lambda = 900 km): this is the resolution limit of our data and suggests that global crustal anomaly maps constructed from vector Magsat data should not contain features with wavelengths less than 900 km. We find continental power spectra to be greater than oceanic ones and attribute this to the relative thicknesses of continental and oceanic crust. C1 Univ Calif San Diego, Scripps Inst Oceanog, Cecil H & Ida M Green Inst Geophys & Planetary Ph, La Jolla, CA 92093 USA. NASA, Goddard Space Flight Ctr, Geodynam Branch, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. RP Lowe, DAJ (reprint author), Univ Calif San Diego, Scripps Inst Oceanog, Cecil H & Ida M Green Inst Geophys & Planetary Ph, 9500 Gilman Dr, La Jolla, CA 92093 USA. EM dlowe@mahi.ucsd.edu; rlparker@ucsd.edu; purucker@geomag.gsfc.nasa.gov; cconstable@ucsd.edu RI Constable, Catherine/F-7784-2010 OI Constable, Catherine/0000-0003-4534-4977 NR 21 TC 3 Z9 3 U1 0 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 MAY 10 PY 2001 VL 106 IS B5 BP 8589 EP 8598 DI 10.1029/2000JB900437 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 430UE UT WOS:000168593200006 ER PT J AU Sakimoto, SEH Gregg, TKP AF Sakimoto, SEH Gregg, TKP TI Channeled flow: Analytic solutions, laboratory experiments, and applications to lava flows SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID ORBITER LASER ALTIMETER; EAST PACIFIC RISE; ANALOG EXPERIMENTS; EFFUSION RATES; MAGELLAN DATA; COOLING RATE; MOUNT ETNA; MORPHOLOGY; MARS; EMPLACEMENT AB Although channeled lava flows are common in basaltic volcanism, relationships between channel morphology, eruption and emplacement parameters, and lava properties are not well understood. Several models have commonly been used to constrain these relations, but they have not been well tested on natural or simulated lava flows over a wide range of parameter space. Here, we test the accuracy and assumptions of a moderately simple analytic rectangular channel solution by comparing the behavior of well-controlled laboratory polyethylene glycol (PEG) channeled flows to the analytic solution for isothermal, steady Newtonian flow in a rectangular channel with constant dimensions. This analytic solution agrees well with laboratory measurements. Volumetric effusion rates (Q; m(3) s(-1)) calculated from the analytical model using measured PEG flows as input yield ratios of Q(calculated)/Q(pumped) of similar to0.2 to 3.6, and flow rates calculated from a best fit surface velocity profile to measured velocities give more accurate ratios of similar to0.8 to 1.2. We find a very weak dependence of solution accuracy on slope, attributable to flow front effects within the laboratory flows. We subsequently apply the solution to several subaerial and submarine terrestrial flows as well as extraterrestrial channeled flows over a wide range of flow parameters. Viscosity ranges and flow rates obtained using measured channel dimensions and assumed lava properties are plausible. Interestingly, the resulting extraterrestrial estimates of viscosities and flow rates tend to fall closer to known terrestrial measurements and estimates of channel flow than to previous planetary estimates. We therefore suggest that the analytic Newtonian rectangular channel flow model is a more appropriate physical model for many channeled terrestrial and planetary flows than the Newtonian infinite sheet flow and approximation to Bingham channel flow widely used previously. C1 SUNY Buffalo, Dept Geol Sci, Buffalo, NY 14260 USA. Univ Space Res Assoc, NASA, Goddard Space Flight Ctr, Geodynam Branch, Greenbelt, MD 20771 USA. RP Sakimoto, SEH (reprint author), Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Geodynam Branch,Goddard Earth Sci & Technol Ctr, Code 921, Greenbelt, MD 20771 USA. EM sakimoto@denali.gsfc.nasa.gov; gregg@acsu.buffalo.edu NR 55 TC 30 Z9 30 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD MAY 10 PY 2001 VL 106 IS B5 BP 8629 EP 8644 DI 10.1029/2000JB900384 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 430UE UT WOS:000168593200009 ER PT J AU de Viron, O Ponte, RM Dehant, V AF de Viron, O Ponte, RM Dehant, V TI Indirect effect of the atmosphere through the oceans on the Earth nutation using the torque approach SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID ANGULAR-MOMENTUM; BAROTROPIC MOTIONS; POLAR MOTION; PRESSURE; PRECESSION; ROTATION AB The atmosphere exerts a direct torque on the Earth, perturbing its rotation. Additionally, the atmosphere exerts pressure, gravitational, and friction forces on the ocean, which induce an indirect effect of the atmosphere on the Earth. The oceanic response consists of variable currents and mass fluxes. These effects change the oceanic torque on the Earth. As the atmosphere has a large diurnal cycle, the indirect torque also presents a large diurnal component. This indirect diurnal torque is investigated using a numerical barotropic ocean model. In particular, we show that a dynamic ocean model is essential to compute the indirect effect of the atmosphere on nutation, as the oceanic response is far from that predicted by a static model. We also point out that the response of the ocean is nevertheless highly correlated with the atmospheric signal for the diurnal timescale but with a large amplification. The amount of ocean bottom friction is found to have a substantial influence on the indirect diurnal torque acting on the Earth. The effect of this indirect torque on the Earth nutation is computed and found to be much larger than the precision of current nutation observations, but results are uncertain in light of discrepancies in the angular momentum and torque balance. C1 Atmospher & Environm Res Inc, Cambridge, MA 02139 USA. Royal Observ Belgium, B-1180 Brussels, Belgium. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP de Viron, O (reprint author), Royal Observ Belgium, Ave Circulaire 3, B-1180 Brussels, Belgium. EM o.deviron@oma.be; ponte@aer.com; v.dehant@oma.be RI de Viron, Olivier/N-6647-2014; OI de Viron, Olivier/0000-0003-3112-9686; Ponte, Rui/0000-0001-7206-6461 NR 16 TC 13 Z9 13 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD MAY 10 PY 2001 VL 106 IS B5 BP 8841 EP 8851 DI 10.1029/2000JB900387 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 430UE UT WOS:000168593200021 ER PT J AU Hazen, RM Roedder, E AF Hazen, RM Roedder, E TI Biogeology - How old are bacteria from the Permian age? SO NATURE LA English DT Article ID PALO-DURO BASIN; FLUID INCLUSIONS; SALT; TEXAS C1 Carnegie Inst Washington, Geophys Lab, Washington, DC 20015 USA. Carnegie Inst Washington, NASA, Astrobiol Inst, Washington, DC 20015 USA. RP Hazen, RM (reprint author), Carnegie Inst Washington, Geophys Lab, 5251 Broad Branch Rd NW, Washington, DC 20015 USA. NR 6 TC 30 Z9 33 U1 1 U2 8 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD MAY 10 PY 2001 VL 411 IS 6834 BP 155 EP 155 DI 10.1038/35075663 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 430FC UT WOS:000168563000037 PM 11346782 ER PT J AU Loh, CY Hultgren, LS Chang, SC AF Loh, CY Hultgren, LS Chang, SC TI Wave computation in compressible flow using space-time conservation element and solution element method SO AIAA JOURNAL LA English DT Article ID ABSORBING BOUNDARY-CONDITIONS; HYPERBOLIC SYSTEMS; EULER EQUATIONS; SCHEMES; LAYER AB The recently developed space-time conservation element solution element method has several attractive features for aeroacoustic computations. The scheme is robust, possesses almost no dispersion error, and the implementation of nonreflecting boundary conditions is simple and effective. The scheme is tested for several problems ranging from linear acoustic waves to strongly nonlinear phenomena, with special emphasis on mixing-layer instability, and good numerical results are achieved. C1 NASA, John H Glenn Res Ctr Lewis Field, Turbomachinery & Prop Syst Div, Cleveland, OH 44135 USA. NR 24 TC 32 Z9 32 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 MAY PY 2001 VL 39 IS 5 BP 794 EP 801 DI 10.2514/2.1412 PG 8 WC Engineering, Aerospace SC Engineering GA 431BK UT WOS:000168611900005 ER PT J AU Samareh, JA AF Samareh, JA TI Survey of shape parameterization techniques for high-fidelity multidisciplinary shape optimization SO AIAA JOURNAL LA English DT Article ID B-SPLINES; AUTOMATIC DIFFERENTIATION; DESIGN; GEOMETRY; DEFORMATIONS; GENERATION; ACCURACY; MESHES AB A survey is provided of shape parameterization techniques for multidisciplinary optimization, and some emerging ideas are highlighted. The survey focuses on the suitability of available techniques for multidisciplinary applications of complex configurations using high-fidelity analysis tools such as computational fluid dynamics and computational structural mechanics. The suitability criteria are based on the efficiency, effectiveness, ease of implementation, and availability of analytical sensitivities for geometry and grids. A section on sensitivity analysis, grid regeneration, and grid deformation techniques is also provided. C1 NASA, Langley Res Ctr, Multidisciplinary Optimizat Branch, Hampton, VA 23681 USA. RP Samareh, JA (reprint author), NASA, Langley Res Ctr, Multidisciplinary Optimizat Branch, Hampton, VA 23681 USA. NR 69 TC 94 Z9 103 U1 2 U2 12 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 MAY PY 2001 VL 39 IS 5 BP 877 EP 884 DI 10.2514/2.1391 PG 8 WC Engineering, Aerospace SC Engineering GA 431BK UT WOS:000168611900015 ER PT J AU Slade, KN Tinker, ML Lassiter, JO Engberg, R AF Slade, KN Tinker, ML Lassiter, JO Engberg, R TI Dynamics of an inflatable structure in vacuum and ambient conditions SO AIAA JOURNAL LA English DT Article AB In the dynamic modal testing of extremely lightweight inflatable structures, the results may vary dramatically according to the presence of either thermal vacuum or ambient atmospheric conditions. Unique aspects of modal testing techniques for an inflatable solar concentrator are identified, including the use of a noncontacting laser vibrometer measurement system. For the thermal vacuum environment, mode shapes and frequency response functions are compared for three different test article inflation pressures at room temperature. Modes that persist through all inflation pressure regimes are identified, as are modes that are unique for each pressure. In atmospheric pressure and room temperature conditions, dynamic measurements were obtained for the expected operational inflation pressure. Experimental mode shapes and frequency response functions for ambient conditions are described and compared to the results from the thermal vacuum tests. There is a surprising lack of correlation in test results between the two test conditions, which may be explained by damping and air mass considerations. Results of this investigation point out the necessity of testing inflatable space structures in vacuum conditions before they can be launched. C1 Duke Univ, Dept Mech Engn & Mat Sci, Edmund T Pratt Jr Sch Engn, Durham, NC 27708 USA. NASA, George C Marshall Space Flight Ctr, Struct Dynam & Loads Grp ED21, Struct Mech & Thermal Dept, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Struct Dynam & Testing Grp ED27, Struct Mech & Thermal Dept, Huntsville, AL 35812 USA. RP Slade, KN (reprint author), Duke Univ, Dept Mech Engn & Mat Sci, Edmund T Pratt Jr Sch Engn, Durham, NC 27708 USA. NR 28 TC 9 Z9 9 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 MAY PY 2001 VL 39 IS 5 BP 894 EP 901 PG 8 WC Engineering, Aerospace SC Engineering GA 431BK UT WOS:000168611900017 ER PT J AU Smith, RK Tremallo, RL Lofgren, GE AF Smith, RK Tremallo, RL Lofgren, GE TI Growth of megaspherulites in a rhyolitic vitrophyre SO AMERICAN MINERALOGIST LA English DT Article ID ION-MICROPROBE ANALYSES; MELT INCLUSIONS; CRYSTAL-GROWTH; NUCLEATION; TEXTURES; WATER; H2O; CRYSTALLIZATION; PLAGIOCLASE; CONSTRAINTS AB Megaspherulites occur in a rhyolitic vitrophyre, near the base of a thick rhyolitic vitrophyre that occupies a late Eocene to early Oligocene volcanic-tectonic basin near Silver Cliff, Colorado. Diameters of the megaspherulites range from 0.3 to over 3.66 m, including an alteration layer. The megaspherulites are compound spherulites. They are holocrystalline, very fine- to fine-grained, com posed of sanidine and quartz, and surrounded by a thin sanidine-quartz rind, and an alteration layer containing mordenite and 15 Angstrom montmorillonite. Megaspherulite crystallization began soon after the vitrophyre was emplaced as the result of sparse heterogeneous nucleation, under highly nonequilibrium conditions. Spherulite growth proceeded in a diffusion-controlled manner under lowered viscosity as a result of a high water content (5 to 7 wt%), which also contributed to sparse nucleation. When nucleation did occur, it was at a large DeltaT (245-350 degreesC) on near critical-sized nuclei. Once the spherulites began to grow, continued nucleation was on existing growth cones and new, independent spherulites did not form. Sanidine crystals grew with a fibrous habit, which is favored by a large DeltaT, restricting fibril lengths and diameters between 10-30 and 3-7 mum, respectively. During crystallization, these growth cones impinged upon each other, resulting in fibril cone-free areas. These cone-free (interconal) areas consist of coarser, fine-grained phases, dominated by quartz, which crystallized from the melt as it accumulated between the crystallizing sanidine fibrils of the cones. The anhydrous nature of the sanidine and quartz suggests that their crystallization concentrated a water-rich residual fluid, enriched in Ca, Mg, and Fe, and depleted in Si, K, and Na, at the megaspherulite-vitrophyre interface. This fluid phase enclosed the megaspherulites resulting in the hydrothermal alteration of the vitrophyre, forming a hydrothermal alteration layer, as indicated by the presence of the minerals mordenite and montmorillonite. C1 Univ Texas, Div Phys & Earth Sci, San Antonio, TX 78249 USA. NASA, Lyndon B Johnson Space Ctr, Planetary Sci Branch SN2, Houston, TX 77058 USA. RP Smith, RK (reprint author), Univ Texas, Div Phys & Earth Sci, San Antonio, TX 78249 USA. NR 44 TC 27 Z9 27 U1 0 U2 1 PU MINERALOGICAL SOC AMER PI WASHINGTON PA 1015 EIGHTEENTH ST, NW SUITE 601, WASHINGTON, DC 20036 USA SN 0003-004X J9 AM MINERAL JI Am. Miner. PD MAY-JUN PY 2001 VL 86 IS 5-6 BP 589 EP 600 PG 12 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA 430BZ UT WOS:000168554800001 ER PT J AU Nuth, JA AF Nuth, JA TI How were the comets made? SO AMERICAN SCIENTIST LA English DT Article ID DUST C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Astrochem Branch, Greenbelt, MD 20771 USA. RP Nuth, JA (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Astrochem Branch, Code 691, Greenbelt, MD 20771 USA. RI Nuth, Joseph/E-7085-2012 NR 11 TC 7 Z9 7 U1 1 U2 4 PU SIGMA XI-SCI RES SOC PI RES TRIANGLE PK PA PO BOX 13975, RES TRIANGLE PK, NC 27709 USA SN 0003-0996 J9 AM SCI JI Am. Scientist PD MAY-JUN PY 2001 VL 89 IS 3 BP 228 EP 235 DI 10.1511/2001.22.871 PG 8 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 422RH UT WOS:000168132700018 ER PT J AU De Chant, LJ Seidel, JA AF De Chant, LJ Seidel, JA TI Simplified turbulence modeling for forced vortical mixers using a kinematic wave analogy SO APPLIED MATHEMATICAL MODELLING LA English DT Article DE algebraic turbulence model; vortical mixer; aerodynamic mixing; ejector nozzle ID MIXING LAYERS AB In spite of the rapid advances in both scalar and parallel computational tools, the large number and breadth of variables involved in both design problems make the use of sophisticated fluid flow models impractical. With this restriction, it may be concluded that reduced or approximate models remain important. In this paper, semi-algebraic turbulence models that describe forced vortical interactions using a simple kinematic wave analogy are developed. Semi-algebraic refers to formulations based upon explicit solutions of associated model governing equations. These turbulence models have been employed in a combined analytic/numeric ejector-nozzle model. The numerical portion of the model uses a compact finite difference scheme to obtain high accuracy with three-point support, while the analytical sections have been developed to resolve singular behavior that is inherent to this flow. Solutions and comparison to aerodynamic nozzle data are presented to illustrate this methodology. (C) 2001 Elsevier Science Inc. All rights reserved. C1 Texas A&M Univ, Dept Mech Engn, College Stn, TX 77843 USA. NASA, Prop Syst Anal Off, Glenn Res Ctr, Cleveland, OH 44135 USA. RP De Chant, LJ (reprint author), Texas A&M Univ, Dept Mech Engn, College Stn, TX 77843 USA. NR 36 TC 2 Z9 2 U1 1 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0307-904X J9 APPL MATH MODEL JI Appl. Math. Model. PD MAY-JUN PY 2001 VL 25 IS 6 BP 427 EP 447 DI 10.1016/S0307-904X(00)00058-5 PG 21 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA 428VV UT WOS:000168483100001 ER PT J AU Povitsky, A AF Povitsky, A TI Wavefront cache-friendly algorithm for compact numerical schemes SO APPLIED MATHEMATICS LETTERS LA English DT Article DE cache locality; compact scheme; wavefront algorithm; banded linear systems ID FINITE-DIFFERENCE SCHEMES AB Compact numerical schemes provide high-order solution of PDEs with low dissipation and dispersion. Computer implementation of these schemes requires numerous passes of data. through cache memory that considerably reduces performance of these schemes. To reduce this difficulty, a novel algorithm is proposed here. This algorithm is based on a wavefront approach and sweeps through cache memory only twice. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. RP Povitsky, A (reprint author), NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 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 MAY PY 2001 VL 14 IS 4 BP 449 EP 454 DI 10.1016/S0893-9659(00)00176-2 PG 6 WC Mathematics, Applied SC Mathematics GA 420NQ UT WOS:000168011400010 ER PT J AU Vanek, MD Nolt, IG Tappan, ND Ade, PAR Gannaway, FC Hamilton, PA Lee, C Davis, JE Predko, S AF Vanek, MD Nolt, IG Tappan, ND Ade, PAR Gannaway, FC Hamilton, PA Lee, C Davis, JE Predko, S TI Far-infrared sensor for cirrus (FIRSC): an aircraft-based Fourier-transform spectrometer to measure cloud radiance SO APPLIED OPTICS LA English DT Article AB We describe an aircraft-based Fourier-transform spectrometer (FTS) designed to measure the Earth outgoing radiance spectrum in the far-infrared-submillimeter spectral range. The instrument features include a rapid-scan FTS to obtain high spatial resolution from a moving aircraft platform, a sensitive two-channel detector, and a CCD camera for recording the nadir cloud scene with each scan record. Such measurements demonstrate the sensitivity of Earth radiance to high clouds and provide spectral data for improving techniques for remote sensing and retrieval of atmospheric and cloud properties. (C) 2001 Optical Society of America. C1 NASA, Hampton, VA 23681 USA. Queen Mary Univ London, London E1 4NS, England. Univ Colorado, Boulder, CO 80309 USA. Cochise Instruments, Hereford, AZ 85615 USA. Univ Oregon, Eugene, OR 97403 USA. RP Vanek, MD (reprint author), NASA, Hampton, VA 23681 USA. EM m.d.vanek@larc.nasa.gov NR 10 TC 14 Z9 16 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 MAY 1 PY 2001 VL 40 IS 13 BP 2169 EP 2176 DI 10.1364/AO.40.002169 PG 8 WC Optics SC Optics GA 427HM UT WOS:000168398800015 PM 18357224 ER PT J AU Scott, CD Arepalli, S Nikolaev, P Smalley, RE AF Scott, CD Arepalli, S Nikolaev, P Smalley, RE TI Growth mechanisms for single-wall carbon nanotubes in a laser-ablation process SO APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING LA English DT Article ID VAPORIZATION; FULLERENES; TEMPERATURE; DIAMETER; DYNAMICS; C-60 AB Mechanisms proposed in the literature are compared with a current scenario for the formation of single-wall carbon nanotubes in the laser-ablation process that is based on our spectral emission and laser-induced fluorescence measurements. It is suggested that the carbon which serves as feedstock for nanotube formation not only comes from the direct ablation of the target, but also from carbon particles suspended in the reaction zone. Fullerenes formed in the reaction zone may be photo-dissociated into C? and other low molecular weight species, and also may serve as feedstock for nanotube growth. Confinement of the nanotubes in the reaction zone within the laser beam allows the nanotubes to be 'purified' and annealed during the formation process by laser heating. C1 NASA, Lyndon B Johnson Space Ctr, EM2, Houston, TX 77058 USA. GB Tech Lockheed Martin, Houston, TX 77058 USA. Rice Univ, Ctr Nanosci & Technol, Houston, TX 77005 USA. RP Scott, CD (reprint author), NASA, Lyndon B Johnson Space Ctr, EM2, Houston, TX 77058 USA. RI Arepalli, Sivaram/A-5372-2010; Nikolaev, Pavel/B-9960-2009 NR 24 TC 171 Z9 172 U1 1 U2 43 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0947-8396 J9 APPL PHYS A-MATER JI Appl. Phys. A-Mater. Sci. Process. PD MAY PY 2001 VL 72 IS 5 BP 573 EP 580 DI 10.1007/s003390100761 PG 8 WC Materials Science, Multidisciplinary; Physics, Applied SC Materials Science; Physics GA 429KE UT WOS:000168515300008 ER PT J AU Natta, A Prusti, T Neri, R Wooden, D Grinin, VP Mannings, V AF Natta, A Prusti, T Neri, R Wooden, D Grinin, VP Mannings, V TI A reconsideration of disk properties in Herbig Ae stars SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE circumstellar matter; stars : formation ID T-TAURI STARS; INTERMEDIATE-MASS STARS; SPECTRAL ENERGY-DISTRIBUTIONS; AE/BE STARS; CIRCUMSTELLAR DISKS; ACCRETION DISKS; MODEL ATMOSPHERES; HIGH-RESOLUTION; YOUNG OBJECTS; UX-ORIONIS AB This paper presents state-of-the-art spectral energy distributions (SEDs) of four Herbig Ae stars, based in part on new data in the mid and far-infrared and at millimeter wavelengths. The SEDs are discussed in the context of circumstellar disk models. We show that models of irradiated disks provide a good fit to the observations over the whole range of wavelengths. We offer a possible solution to the long-standing puzzle caused by the excess emission of Herbig Ae stars, where a large fraction of the stellar luminosity is re-radiated between similar to1.25 and 7 mum, with a peak at about 3 mum. We suggest that this general behaviour can be caused by dust evaporation in disks where the gas component is optically thin to the stellar radiation, as expected if the accretion rate is very low. The creation of a puffed-up inner wall of optically thick dust at the dust sublimation radius can account for the near-infrared characteristics of the SEDs. It can also naturally explain the H and K band interferometric observations of AB Aur (Millan-Gabet et al. 2001), which reveal a ring of emission of radius similar to0.3 AU. Finally, irradiated disk models can easily explain the observed intensity of the 10 mum silicate features and their variation from star to star. C1 Osservatorio Astrofis Arcetri, I-50125 Florence, Italy. European Space Agcy, ESTEC, Dept Space Sci, Div Astrophys, NL-2200 AG Noordwijk, Netherlands. Inst Radio Astron Millimetr, F-38406 St Martin Dheres, France. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Crimean Astrophys Observ, UA-334413 Nauchnyi, Ukraine. St Petersburg State Univ, St Petersburg 198904, Russia. CALTECH, SIRTF Sci Ctr, Pasadena, CA 91125 USA. RP Natta, A (reprint author), Osservatorio Astrofis Arcetri, Largo E Fermi 5, I-50125 Florence, Italy. EM natta@arcetri.astro.it RI Grinin, Vladimir/M-9509-2013 OI Grinin, Vladimir/0000-0001-8923-9541 NR 54 TC 237 Z9 239 U1 0 U2 3 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 2001 VL 371 IS 1 BP 186 EP 197 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 453WY UT WOS:000169942200020 ER PT J AU Guirado, JC Ros, E Jones, DL Lestrade, JF Marcaide, JM Perez-Torres, MA Preston, RA AF Guirado, JC Ros, E Jones, DL Lestrade, JF Marcaide, JM Perez-Torres, MA Preston, RA TI Space-VLBI phase-reference mapping and astrometry SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE astrometry; techniques : interferometric quasars : individual : B1342+662; quasars : individual :; B1342+663 ID BASE-LINE INTERFEROMETRY; PROPER MOTION AB We present 5 GHz space-VLBI observations of the quasar pair B1342+662/B 1342+663 that demonstrate the feasibility of phase-reference techniques using an antenna in space. The space-based data were taken by the satellite HALCA, of the space-VLBI mission VSOP. From residual (referenced) phases we derive an upper bound of 10 meters to the uncertainty of the spacecraft orbit reconstruction. An analysis of the phase-reference maps of the sources additionally suggests that the above mentioned uncertainty is likely not larger than 3 meters. With errors of this magnitude, HALCA is a useful tool for astrometric studies of close pairs of radio sources. C1 Univ Valencia, Dept Astron, E-46100 Valencia, Spain. Univ Valencia, Astron Observ, E-46100 Valencia, Spain. Max Planck Inst Radioastron, D-53121 Bonn, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Observ Paris, CNRS, F-92195 Meudon, France. CNR, Ist Radioastron, I-40129 Bologna, Italy. RP Guirado, JC (reprint author), Univ Valencia, Dept Astron, E-46100 Valencia, Spain. EM jcg@vlbi.daa.uv.es OI Ros, Eduardo/0000-0001-9503-4892 NR 11 TC 18 Z9 18 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 2001 VL 371 IS 2 BP 766 EP 770 DI 10.1051/0004-6361:20010370 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 453XJ UT WOS:000169943200036 ER PT J AU Castro-Tirado, AJ Sokolov, VV Gorosabel, J Ceron, JMC Greiner, J Wijers, RAMJ Jensen, BL Hjorth, J Toft, S Pedersen, H Palazzi, E Pian, E Masetti, N Sagar, RN Mohan, V Pandey, AK Pandey, SB Dodonov, SN Fatkhullin, TA Afanasiev, VL Komarova, VN Moiseev, AV Hudec, R Simon, V Vreeswijk, P Rol, E Klose, S Stecklum, B Zapatero-Osorio, MR Caon, N Blake, C Wall, J Heinlein, D Henden, A Benetti, S Magazzu, A Ghinassi, F Tommasi, L Bremer, M Kouveliotou, C Guziy, S Shlyapnikov, A Hopp, U Feulner, G Dreizler, S Hartmann, D Boehnhardt, H Paredes, JM Marti, J Xanthopoulos, E Kristen, HE Smoker, J Hurley, K AF Castro-Tirado, AJ Sokolov, VV Gorosabel, J Ceron, JMC Greiner, J Wijers, RAMJ Jensen, BL Hjorth, J Toft, S Pedersen, H Palazzi, E Pian, E Masetti, N Sagar, RN Mohan, V Pandey, AK Pandey, SB Dodonov, SN Fatkhullin, TA Afanasiev, VL Komarova, VN Moiseev, AV Hudec, R Simon, V Vreeswijk, P Rol, E Klose, S Stecklum, B Zapatero-Osorio, MR Caon, N Blake, C Wall, J Heinlein, D Henden, A Benetti, S Magazzu, A Ghinassi, F Tommasi, L Bremer, M Kouveliotou, C Guziy, S Shlyapnikov, A Hopp, U Feulner, G Dreizler, S Hartmann, D Boehnhardt, H Paredes, JM Marti, J Xanthopoulos, E Kristen, HE Smoker, J Hurley, K TI The extraordinarily bright optical afterglow of GRB 991208 and its host galaxy SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE gamma rays : bursts; galaxies : general; cosmology : observations ID GAMMA-RAY BURSTS; 28 FEBRUARY 1997; LIGHT CURVES; FIREBALL MODEL; ERROR BOX; PHOTOMETRY; GRB-990123; SUPERNOVA; DISCOVERY; EMISSION AB Broad-band optical observations of the extraordinarily bright optical afterglow of the intense gamma-rag burst GRB 991208 started similar to2.1 days after the event and continued until 4 Apr. 2000. The flux decay constant of the optic al afterglow in the R-band is -2.30 +/- 0.07 up to similar to5 days. which is very likely due to the jet effect. and it is followed by a much steeper decay with constant -3.2 +/- 0.2. the fastest one ever seen in a GRB optical afterglow. A negative detection in several all-sky films taken simultaneously with the er ent. that otherwise would have reached naked eye brightness, implies either a previous additional break prior to similar to2 days after the occurrence of the GRB (as expected from the jet effect) or a maximum, as observed in GRB 970508. The existence of a second break might indicate a steepening in the electron spectrum or the superposition of two events, resembling GRB 000301C. Once the afterglow emission vanished, contribution of a bright underlying supernova was found on the basis of the late-time R-band measurements. but the light curve is not sufficiently well sampled to rule out a dust echo explanation. Our redshift determination of z = 0.706 indicates that GRB 991208 is at 3.7 Gpc (for H-0 = 60 km s(-1) Mpc(-1), Omega (0) = 1 and Lambda (0) = 0), implying an isotropic energy release of 1.15 10(53) erg which may. be relaxed by beaming by a factor >10(2). Precise astrometry indicates that the GRB coincides within 0.2" with the host galaxy, thus supporting a massive star origin. The absolute magnitude of the galaxy is M-B = -18.2, well below the knee of the galaxy luminosity function and we derive a star-forming rate of (11.5 +/- 7.1) M-circle dot yr(-1), which is much larger than the present-day rate in our Galaxy. The quasi simultaneous broad-band photometric spectral energy distribution of the afterglow was determined similar to3.5 day after the burst (Dec. 12.0) implying a cooling frequency ve below the optical band, i.e. supporting a jet model with p = -2.30 as the index of the power-law electron distribution. C1 CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain. Inst Nacl Invest Agr, LAEFF, E-28080 Madrid, Spain. Russian Acad Sci, Special Astrophys Observ, Nizhnii Arkhyz 357147, Russia. Danish Space Res Inst, Copenhagen, Denmark. Real Inst, Cadiz 11110, Spain. Observ Armada, Secc Astron, Cadiz 11110, Spain. Inst Astrophys, Potsdam, Germany. SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA. Univ Copenhagen, Astron Observ, Copenhagen, Denmark. CNR, Ist Tecnol & Studio Radiaz Extraterr, I-40126 Bologna, Italy. Uttar Pradesh State Observ, Naini Tal 263129, India. Acad Sci Czech Republ, Inst Astron, CS-25165 Ondrejov, Czech Republic. Anton Pannekoehk Inst, Amsterdam, Netherlands. Thuringer Landessternwarte, D-07778 Tautenburg, Germany. Inst Astrofis Canarias, E-38200 San Cristobal la Laguna, Tenerife, Spain. Univ Oxford, Oxford AX1 4AU, England. Deutsch Zentrum Luft & Raumfahrt, D-86156 Augsburg, Germany. USN Observ, Flagstaff Stn, AZ USA. Univ Space Res Assoc, Flagstaff Stn, AZ USA. Ctr Galileo Galilei, Canary Isl, Spain. Univ Milan, Dipartimento Fis, I-20133 Milan, Italy. Inst Radio Astron Millimetr, Grenoble, France. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. Nikolaev Univ Observ, UA-327030 Nikolayev, Ukraine. Univ Sternwarte, Munich, Germany. Univ Tubingen, Tubingen, Germany. Clemson Univ, Dept Phys & Astron, Clemson, SC 29634 USA. European So Observ, Santiago 19, Chile. Univ Barcelona, Dept Astron & Meteorol, E-08028 Barcelona, Spain. Univ Jaen, Escuela Politecn Super, Dept Fis, Jaen, Spain. Univ Manchester, Jodrell Bank Observ, Macclesfield SK11 9DL, Cheshire, England. Harvard Univ, Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Queens Univ Belfast, Dept Pure & Appl Phys, Belfast BT7 1NN, Antrim, North Ireland. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RP Castro-Tirado, AJ (reprint author), CSIC, Inst Astrofis Andalucia, POB 03004, E-18080 Granada, Spain. EM ajct@laeff.esa.es RI Feulner, Georg/A-1933-2011; Moiseev, Alexey/H-9391-2013; Simon, Vojtech/G-9046-2014; Hudec, Rene/G-9018-2014; Jensen, Brian Lindgren/E-1275-2015; Palazzi, Eliana/N-4746-2015; Shlyapnikov, Aleksey/Q-1646-2016; OI Feulner, Georg/0000-0001-9215-5517; Jensen, Brian Lindgren/0000-0002-0906-9771; Shlyapnikov, Aleksey/0000-0002-2752-2429; Magazzu, Antonio/0000-0003-1259-4371; Benetti, Stefano/0000-0002-3256-0016; Wijers, Ralph/0000-0002-3101-1808; Palazzi, Eliana/0000-0002-8691-7666; Castro-Tirado, A. J./0000-0003-2999-3563; Zapatero Osorio, Maria Rosa/0000-0001-5664-2852; Masetti, Nicola/0000-0001-9487-7740; Paredes, Josep M./0000-0002-1566-9044; Pian, Elena/0000-0001-8646-4858 NR 82 TC 77 Z9 78 U1 0 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 MAY PY 2001 VL 370 IS 2 BP 398 EP 406 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 431BE UT WOS:000168611400008 ER PT J AU Jensen, BL Fynbo, JU Gorosabel, J Hjorth, J Holland, S Moller, P Thomsen, B Bjornsson, G Pedersen, H Burud, I Henden, A Tanvir, NR Davis, CJ Vreeswijk, P Rol, E Hurley, K Cline, T Trombka, J McClanahan, T Starr, R Goldsten, J Castro-Tirado, AJ Greiner, J Bailer-Jones, CAL Kummel, M Mundt, R AF Jensen, BL Fynbo, JU Gorosabel, J Hjorth, J Holland, S Moller, P Thomsen, B Bjornsson, G Pedersen, H Burud, I Henden, A Tanvir, NR Davis, CJ Vreeswijk, P Rol, E Hurley, K Cline, T Trombka, J McClanahan, T Starr, R Goldsten, J Castro-Tirado, AJ Greiner, J Bailer-Jones, CAL Kummel, M Mundt, R TI The afterglow of the short/intermediate-duration gamma-ray burst GRB 000301C: A jet at z=2.04 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE gamma rays : bursts; cosmology : observations; galaxies : distances and redshifts; ISM : dust, extinction; quasars : absorption lines ID LY-ALPHA ABSORBER; 28 FEBRUARY 1997; LIGHT CURVES; ERROR BOX; EMISSION; GALAXIES; ABSORPTION; SUPERNOVA; REDSHIFT; CONSTRAINTS AB We present Ulysses and NEAR data from the detection of the short or intermediate duration (2 s) gamma-ray burst GRB 000301C (2000 March 1.41 UT). The gamma-ray burst (GRB) was localised by the Inter Planetary Network (IPN) and RXTE to an area of similar to 50 arcmin(2). A fading optical counterpart was subsequently discovered with the Nordic Optical Telescope (NOT) about 42 h after the burst. The GRB lies at the border between the long-soft and the short-hard classes of GRBs. If GRB 000301C belongs to the latter class, this would be the first detection of an afterglow to a short-hard burst. We present UBRI photometry from the time of the discovery until 11 days after the burst. We also present JHK photometry obtained with UKIRT on 2000 March 4.5 UT (3.1 days after the burst). Finally, we present spectroscopic observations of the optical afterglow obtained with the ESO VLT Antu telescope 4 and 5 days after the burst. The optical light curve is consistent with bring achromatic from 2 to 11 days after the burst and exhibits a break. A broken power-law fit yields a shallow pre-break decay power-law slope of alpha (1) = -0.72 +/- 0.06, a break time of t(break) = 4.39 +/- 0.26 days after the burst, and a post-break slope of alpha (2) = -2.29 +/- 0.17. These properties of the light curve are best explained by a sideways expanding jet in an ambient medium of constant mean density. In the optical spectrum we find absorption features that are consistent with Fe II, C IV, C II, Si II and Ly alpha at a redshift of 2.0404 +/- 0.0008. We find evidence for a curved shape of the spectral energy distribution of the observed afterglow. It is best fitted with a power-law spectral distribution with index beta similar to -0.7 reddened by an SMC-like extinction law with A(v) similar to 0.1 mag. Based on the Ly alpha absorption line we estimate the H I column density to be log(N(HI)) = 21.2 +/- 0.5. This is the first direct indication of a connection between GRB host galaxies and Damped Ly alpha Absorbers. C1 Univ Copenhagen, Astron Observ, DK-2100 Copenhagen O, Denmark. Aarhus Univ, Inst Phys & Astron, DK-8000 Aarhus C, Denmark. European So Observ, D-85748 Garching, Germany. Danish Space Res Inst, DK-2100 Copenhagen O, Denmark. Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 USA. Univ Iceland, Inst Sci, IS-107 Reykjavik, Iceland. Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium. USN Observ, Flagstaff Stn, Flagstaff, AZ 86002 USA. Univ Hertfordshire, Dept Phys Sci, Hatfield AL10 9AB, Herts, England. Joint Astron Ctr, Hilo, HI 96720 USA. Univ Amsterdam, NL-1098 SJ Amsterdam, Netherlands. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. INTA, LAEFF, Madrid 28040, Spain. CSIC, IAA, E-18080 Granada, Spain. Inst Astrophys, Potsdam, Germany. Max Planck Inst Astron, D-69117 Heidelberg, Germany. RP Jensen, BL (reprint author), Univ Copenhagen, Astron Observ, Juliane Maries Vej 30, DK-2100 Copenhagen O, Denmark. EM brian_j@astro.ku.dk RI McClanahan, Timothy/C-8164-2012; Jensen, Brian Lindgren/E-1275-2015; OI Jensen, Brian Lindgren/0000-0002-0906-9771; Castro-Tirado, A. J./0000-0003-2999-3563 NR 79 TC 103 Z9 103 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 2001 VL 370 IS 3 BP 909 EP 922 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 453WX UT WOS:000169942100013 ER PT J AU Hony, S Van Kerckhoven, C Peeters, E Tielens, AGGM Hudgins, DM Allamandola, LJ AF Hony, S Van Kerckhoven, C Peeters, E Tielens, AGGM Hudgins, DM Allamandola, LJ TI The CH out-of-plane bending modes of PAH molecules in astrophysical environments SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE circumstellar matter; stars : pre-main sequence; HII regions; ISM : molecules; planetary nebulae : general infrared : ISM : lines and bands ID POLYCYCLIC AROMATIC-HYDROCARBONS; INFRARED-EMISSION SPECTRA; IR EMISSION; MU-M; SPECTROSCOPY; CATIONS; BANDS; FEATURES; MICRON; REGION AB We present 10-15 mum spectra of a sample of H II regions. YSOs and evolved stars that show strong unidentified infrared emission features, obtained with the ISO/SWS spectrograph on-board ISO. These spectra reveal a plethora of emission features with bands at 11.0, 11.2, 12.0, 12.7, 13.5 and 14.2 mum. These features are observed to vary considerably in relative strength to each-other from source to source. In particular, the 10-15 mum spectra of the evolved stars are dominated by lthe 11.2 mum band while for H II regions the 12.7 is typically as strong as the 11.2 mum band. Analysing the ISO data we find a good correlation between the 11.2 mum band and the 3.3. mum band, and between the 12.7 mum and the 6.2 mum band. There is also a correlation between the ratio of the UIR bands to the total dust emission and the 12.7 over 11.2 mum ratio. Bands in the 10-15 mum spectral region are due to CH out-of-plane (OOP) bending modes of polycyclic aromatic hydrocarbons (PAHs). We summarise existing laboratory data and theoretical quantum chemical calculations of these modes for neutral and cationic PAHs. Due to mode coupling, the exact peak position of the these bands depends on the number of adjacent CH groups and hence the observed interstellar 10-15 mum spectra can be used to determine the molecular structure of the interstellar PAHs emitting in the different regions. We conclude that evolved stars predominantly inject compact 100-200 C-atom PAHs into the ISM where they are subsequently processed, resulting in more open and uneven PAH structures. C1 Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Katholieke Univ Leuven, Inst Sterrenkunde, B-3001 Heverlee, Belgium. SRON, Lab Space Res Groningen, NL-9700 AV Groningen, Netherlands. Univ Groningen, Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Astron Inst Anton Pannekoek, Kruislaan 403, NL-1098 SJ Amsterdam, Netherlands. EM hony@astro.uva.nl NR 46 TC 226 Z9 227 U1 1 U2 9 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 2001 VL 370 IS 3 BP 1030 EP 1043 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 453WX UT WOS:000169942100027 ER PT J AU Kocharov, L Torsti, J St Cyr, OC Huhtanen, T AF Kocharov, L Torsti, J St Cyr, OC Huhtanen, T TI A relation between dynamics of coronal mass ejections and production of solar energetic particles SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE acceleration of particles; Sun : flares; Sun : corona; Sun : particle emission ID MAGNETIC CLOUD; JANUARY 6-11; EVENT; CME; ACCELERATION; TRACKING; ORIGIN; LASCO; ERNE; SUN AB During January 1997-June 1998, the Large Angle Spectroscopic Coronagraph (LASCO) aboard the Solar and Heliospheric Observatory spacecraft (SOHO) registered 670 coronal mass ejections (CMEs). We compare two groups of the 300-800 km s(-1) CMEs: (i) (very) gradually accelerating CMEs with acceleration below 10 m s(-2) and (ii) impulsively accelerating CMEs with acceleration a > 20 m s(-2) near the Sun, continuing then with the constant speed across the LASCO field of view. An association of those CMEs with solar energetic particle (SEP) events is studied using the data of the energetic particle experiment ERNE also aboard SOHO. There were no SEP events registered in association with the first group CMEs, whereas about 8% of the second group CMEs produced an enhancement in the similar to 10 MeV proton flux at SOHO. This result along with a number of additional tests supports an idea that production of SEPs by the moderate speed CMEs depends not only on the final speed hut also on the magnitude of acceleration that CME experiences during its liftoff. The SEP-producing CMEs are typified by impulsively accelerating CMEs accompanied by soft X-ray flares and coronal shocks. C1 Univ Turku, Dept Phys, Space Res Lab, Turku 20014, Finland. NASA, Goddard Space Flight Ctr, Computat Phys Inc, Greenbelt, MD 20771 USA. RP Kocharov, L (reprint author), Univ Turku, Dept Phys, Space Res Lab, Turku 20014, Finland. EM leon.kocharov@rsl.utu.fi NR 23 TC 13 Z9 13 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 2001 VL 370 IS 3 BP 1064 EP 1070 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 453WX UT WOS:000169942100030 ER PT J AU Binello, AM Landi, E Mason, HE Storey, PJ Brosius, JW AF Binello, AM Landi, E Mason, HE Storey, PJ Brosius, JW TI A comparison between theoretical and solar Fe XII UV line intensity ratios SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE Sun : general; atomic data; UV Sun : radiations; plasmas ID ELECTRON-IMPACT EXCITATION; EXTREME-ULTRAVIOLET SPECTRUM; HIGH-RESOLUTION OBSERVATIONS; FINE-STRUCTURE TRANSITIONS; ACTIVE-REGION; ATOMIC DATA; EMISSION-LINES; IRON PROJECT; DENSITY DIAGNOSTICS; SPECTROSCOPIC DIAGNOSTICS AB A new set of radiative and electron collisional data for Fe XII was presented in two earlier papers. In the present work, rye derive level populations and theoretical line intensities for a range of plasma densities and temperatures. Observations of Fe XII lines obtained with the Solar EUV Rocket Telescope and Spectrograph are analysed both as a check the quality of the new atomic data and to determine the electron density in active regions and the quiet Sun. The discrepancy between the electron density values determined from Fe XII line intensity ratios and those obtained from other ions is investigated. C1 USN, Res Lab, Washington, DC 20375 USA. Univ Cambridge, Dept Appl Math & Theoret Phys, Cambridge CB2 1TN, England. UCL, Dept Phys & Astron, London WC1E 6BT, England. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Raytheon ITSS, Greenbelt, MD 20771 USA. RP USN, Res Lab, Washington, DC 20375 USA. EM landi@poppeo.nrl.navy.mil RI Landi, Enrico/H-4493-2011 NR 53 TC 22 Z9 22 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 2001 VL 370 IS 3 BP 1071 EP 1087 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 453WX UT WOS:000169942100031 ER PT J AU Patzold, M Wennmacher, A Hausler, B Eidel, W Morley, T Thomas, N Anderson, JD AF Patzold, M Wennmacher, A Hausler, B Eidel, W Morley, T Thomas, N Anderson, JD TI Mass and density determinations of 140 Siwa and 4979 Otawara as expected from the Rosetta flybys SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE asteroids : mass; asteroids : individual : Siwa, Otawara ID INNER DUST COMA; GIOTTO SPACECRAFT; DYNAMICS; EROS AB During its interplanetary cruise to comet P/Wirtanen, the Rosetta spacecraft will encounter the asteroids 4979 Otawara and 140 Siwa on 11 July 2006 and 24 July 2008, respectively. The objective of the Rosetta Radio Science investigations (RSI) experiment at these flybys is a determination of the asteroid's mass and bulk density by analyzing the radio tracking data (Doppler and range) received from Rosetta before, during and after closet approach. The spacecraft's flyby trajectory will be gravitationally deflected by an amount proportional to the mass of the asteroid for a given flyby distance and velocity. An analysis of the Doppler noise sources indicates that the mass can be determined to an accuracy of 1% for 140 Siwa. The corresponding bulk density show be accurate to 20%. Unfortunately, a detectable trajectory perturbation seems to be hopeless for Otawara because of its small size and the large nominal flyby distance. C1 Univ Cologne, Inst Geophys & Meteorol, D-50923 Cologne, Germany. Univ Bundeswehr Munchen, Inst Raumfahrttech, D-85557 Neubiberg, Germany. ESA, ESOC, D-64293 Darmstadt, Germany. Max Planck Inst Aeron, D-37189 Katlenburg Lindau, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91107 USA. RP Patzold, M (reprint author), Univ Cologne, Inst Geophys & Meteorol, Albertus Magnus Pl, D-50923 Cologne, Germany. EM paetzold@geo.Uni-Koeln.DE; wennmach@geo.Uni-Koeln.DE; Bernd.Haeusler@UniBW-Muenchen.DE; werner.eidel@UniBW-Muenchen.DE; tmorley@esoc.esa.de; thomas@linmpi.mpg.de; John.D.Anderson@jpl.nasa.gov NR 15 TC 7 Z9 7 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 2001 VL 370 IS 3 BP 1122 EP 1127 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 453WX UT WOS:000169942100035 ER PT J AU Grego, L Carlstrom, JE Reese, ED Holder, GP Holzapfel, WL Joy, MK Mohr, JJ Patel, S AF Grego, L Carlstrom, JE Reese, ED Holder, GP Holzapfel, WL Joy, MK Mohr, JJ Patel, S TI Galaxy cluster gas mass fractions from Sunyaev-Zeldovich effect measurements: Constraints on Omega(M) SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations; galaxies : clusters : general; techniques : interferometric ID MEDIUM-SENSITIVITY SURVEY; X-RAY-CLUSTERS; INTRACLUSTER GAS; COOLING FLOWS; MILLIMETER ARRAY; DISTANT CLUSTER; OPTICAL IDENTIFICATIONS; TEMPERATURE PROFILES; BRIGHTEST CLUSTERS; LUMINOUS CLUSTERS AB Using sensitive centimeter-wave receivers mounted on the Owens Valley Radio Observatory and Berkeley-Illinois-Maryland-Association millimeter arrays, we have obtained interferometric measurements of the Sunyaev-Zeldovich (SZ) effect toward massive galaxy clusters. We use the SZ data to determine the pressure distribution of the cluster gas and, in combination with published X-ray temperatures, to infer the gas mass and total gravitational mass of 18 clusters. The gas mass fraction, f(g), is calculated for each cluster and is extrapolated to the fiducial radius r(500) using the results of numerical simulations. The mean f(g) within r(500) is 0.081(-0.011)(+0.009) h(100) (-1)(statistical uncertainty at 68% confidence level, assuming Omega (M), = 0.3, Omega (Lambda) (g)= 0.7). We discuss possible sources of systematic errors in the mean f(g) measurement. We derive an upper limit for Omega (M) from this sample under the assumption that the mass composition of clusters within r(500) reflects the universal mass composition: Omega (M) h less than or equal to Omega (B)/f(g). The gas mass fractions depend on cosmology through the angular diameter distance and the r(500) correction factors. For a flat universe (Omega (Lambda) equivalent to 1 - Omega (M)) and h = 0.7, we find the measured gas mass fractions are consistent with Omega (M) < 0.40, at 68% confidence. Including estimates of the baryons contained in galaxies and the baryons which failed to become bound during the cluster formation process, we find (M) similar to 0.25. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. RP Grego, L (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Holzapfel, William/I-4836-2015 NR 79 TC 128 Z9 129 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 MAY PY 2001 VL 552 IS 1 BP 2 EP 14 DI 10.1086/320443 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 434EX UT WOS:000168803100002 ER PT J AU Hui, L Burles, S Seljak, U Rutledge, RE Magnier, E Tytler, D AF Hui, L Burles, S Seljak, U Rutledge, RE Magnier, E Tytler, D TI On estimating the QSO transmission power spectrum SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; intergalactic medium; large-scale structure of universe; methods : data analysis; quasars : absorption lines ID LY-ALPHA FOREST; PHOTOIONIZED INTERGALACTIC MEDIUM; MASS FLUCTUATIONS; REDSHIFT SURVEYS; GRAVITATIONAL COLLAPSE; VARIANCE; CLOUDS; MODEL; SPECTROSCOPY; ABSORPTION AB The Ly alpha forest has become an important tool for measuring the mass power spectrum at high redshifts (z = 2-4). A crucial intermediate step is the measurement of the transmission power spectrum. We present new methods to minimize the systematic and random errors for such a measurement and discuss their implications for observing strategies. Sources of systematic errors explored include metal line contamination and continuum fitting. We advocate the technique of trend removal in place of traditional continuum fitting: here a spectrum is normalized by its (smoothly varying) mean rather than its continuum; this method is easily automated and removes biases introduced by continuum fitting. Moreover, trend removal can be easily applied to spectra where continuum fitting is difficult, such as when the resolution or signal-to-noise ratio (S/N) is low, or for spectra at high redshifts. We further show that a measurement of the continuum power spectrum (plus a related quantity) using trend removal, from either low-redshift quasar spectra or the red side of Ly alpha, can be used to constrain the amount of spurious large-scale power introduced by the uncertain continuum and in principle allows the removal of such contamination and thereby expanding scales probed to larger ones. We also derive expressions for the shot noise bias and variance of the power spectrum estimate, taking into account the non-Poissonian nature of the shot noise and the non-Gaussianity of the cosmic fluctuations. An appropriate minimum variance weighting of the data is given. Finally, we give practical suggestions on observing strategy: the desired resolution and S/N for different purposes and instruments, as well as how to distribute one's finite observing time among quasar targets. Also discussed is the quasar spectroscopic study of the Sloan Digital Sky Survey (SDSS), which has the potential to measure the power spectrum accurate to better than 1% per mode (Deltak similar to 10(-4) s km(-1)). The techniques presented here will be useful for tackling the anticipated issues of shot noise and continuum contamination. C1 Fermi Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Inst Adv Study, Princeton, NJ 08540 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Princeton Univ, Dept Phys, Princeton, NJ 08544 USA. CALTECH, Dept Astron, Pasadena, CA 91125 USA. Canada France Hawaii Telescope Corp, Kamuela, HI 96743 USA. Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. RP Hui, L (reprint author), Inst Adv Study, Olden Lane, Princeton, NJ 08540 USA. NR 63 TC 41 Z9 41 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 MAY PY 2001 VL 552 IS 1 BP 15 EP 35 DI 10.1086/320436 PN 1 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 434EX UT WOS:000168803100003 ER PT J AU Reichart, DE Lamb, DQ Fenimore, EE Ramirez-Ruiz, E Cline, TL Hurley, K AF Reichart, DE Lamb, DQ Fenimore, EE Ramirez-Ruiz, E Cline, TL Hurley, K TI A possible Cepheid-like luminosity estimator for the long gamma-ray bursts SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts ID 28 FEBRUARY 1997; 25 APRIL 1998; UNUSUAL SUPERNOVA; ERROR BOX; AFTERGLOW; CONNECTION; ENERGY; DISCOVERY; TRANSIENT; REDSHIFT AB We present a possible Cepheid-like luminosity estimator for the long gamma-ray bursts based on the variability of their light curves. To construct the luminosity estimator, we use CGRO/BATSE data for 13 bursts, Wind/Konus data for fie bursts, Ulysses/GRB data for one burst, and NEAR/XGRS data for one burst. Spectroscopic redshifts, peak fluxes, and high-resolution light curves are available for 11 of these bursts; partial information is available for the remaining nine bursts. We find that the isotropic equivalent peak luminosities L of these bursts positively correlate with a rigorously constructed measure V of the variability of their light curves. We fit to these data a model that accommodates both intrinsic scatter (statistical variance) and extrinsic scatter (sample variance). We find that L similar to V--0.9(3.3 +/-)+1.1. If one excludes GRB 980425 from the fit, on the grounds that its association with SN 1998bw at a redshift of z = 0.0085 is not secure, the luminosity estimator spans approximate to2.5 orders of magnitude in L, and the slope of the correlation between L and V is positive with a probability of 1 - (1.4 x 10(-4)) (3.8 sigma). Although GRB 980425 is excluded from this fit, its L and V values are consistent with the fitted model, which suggests that GRB 980425 may well be associated with SN 1998bw and that GRB 980425 and the cosmological bursts may share a common physical origin. If one includes GRB 980425 in the fit, the luminosity estimator spans approximate to6.3 orders of magnitude in L, and the slope of the correlation is positive with a probability of 1--(9.3 x 10(-7)) (4.9 sigma). In either case, the luminosity estimator yields best-estimate luminosities that are accurate to a factor of approximate to4, or best-estimate luminosity distances that are accurate to a factor of approximate to2. Regardless of whether GRB 980425 should be included in the fit, its light curve is unique in that it is much less variable than the other approximate to 17 light curves of bursts in our sample for which the signal-to-noise ratio is reasonably good. C1 Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. CALTECH, Dept Astron, Pasadena, CA 91125 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RP Reichart, DE (reprint author), Univ Chicago, Dept Astron & Astrophys, 5640 S Ellis Ave, Chicago, IL 60637 USA. NR 43 TC 228 Z9 233 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 MAY PY 2001 VL 552 IS 1 BP 57 EP 71 DI 10.1086/320434 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 434EX UT WOS:000168803100007 ER PT J AU Becker, PA Subramanian, P Kazanas, D AF Becker, PA Subramanian, P Kazanas, D TI Relativistic outflows from advection-dominated accretion disks around black holes SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; black hole physics; galaxies : jets; galaxies : nuclei; Galaxy : center ID QUASI-SPHERICAL ACCRETION; MARGINALLY STABLE ORBIT; SGR A-ASTERISK; COMPACT SOURCES; FLOWS; MODEL; VARIABILITY; EFFICIENCY; QUIESCENCE; TURBULENCE AB Advection-dominated accretion flows (ADAFs) have a positive Bernoulli parameter and are therefore gravitationally unbound. The Newtonian ADAF model has been generalized recently to obtain the ADIOS model that includes outflows of energy and angular momentum, thereby allowing accretion to proceed self-consistently. However, the utilization of a Newtonian gravitational potential limits the ability of this model to describe the inner region of the disk, where any relativistic outflows are likely to originate. In this paper we modify the ADIOS scenario to incorporate a pseudo-Newtonian potential, which approximates the effects of general relativity. The analysis yields a unique, self-similar solution for the structure of the coupled disk/wind system. Interesting features of the new solution include the relativistic character of the outflow in the vicinity of the radius of marginal stability, which represents the inner edge of the quasi-Keplerian disk in our model. Hence, our self-similar solution may help to explain the origin of relativistic jets in active galaxies. At large distances the radial dependence of the accretion rate approaches the unique form (M) over dot proportional to r(1/2), with an associated density variation given by rho proportional to r(-1). This density variation agrees with that implied by the dependence of the hard X-ray time lags on the Fourier frequency for a number of accreting galactic black hole candidates. While intriguing, the predictions made using our self-similar solution need to be confirmed in the future using a detailed model that includes a physical description of the energization mechanism that drives the outflow, which is likely to be powered by the shear of the underlying accretion disk. C1 George Mason Univ, Ctr Earth Observing & Space Res, Fairfax, VA 22030 USA. Tata Inst Fundamental Res, Natl Ctr Radio Astrophys, Pune 411007, Maharashtra, India. NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Greenbelt, MD 20771 USA. George Mason Univ, Dept Phys & Astron, Fairfax, VA 22030 USA. RP Becker, PA (reprint author), George Mason Univ, Ctr Earth Observing & Space Res, Fairfax, VA 22030 USA. NR 45 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 MAY PY 2001 VL 552 IS 1 BP 209 EP 220 DI 10.1086/320433 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 434EX UT WOS:000168803100021 ER PT J AU Burles, S Nollett, KM Turner, MS AF Burles, S Nollett, KM Turner, MS TI Big bang nucleosynthesis predictions for precision cosmology SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : theory; nuclear reactions, nucleosynthesis, abundances ID PRIMORDIAL HELIUM ABUNDANCE; DEUTERIUM ABUNDANCE; SPATIAL VARIATIONS; LITHIUM ABUNDANCE; REACTION-RATES; LOCAL ISM; STARS; RATIO; HE-4; UNCERTAINTIES AB The determination of the primeval deuterium abundance has opened a precision era in big bang nucleosynthesis, making accurate predictions more important than ever before. We present in analytic form new, more precise predictions for the light-element abundances and their error matrix. Using our predictions and the primeval deuterium abundance, we infer a baryon density of (3)Omega (beta)h(2) = 0.020 +/- 0.002 (95% confidence level) and find no evidence for stellar production (or destruction) of He-3 beyond burning D into He-3. Conclusions about He-4 and Li-7 currently hinge on possible systematic errors in their measurements. C1 Fermi Natl Accelerator Lab, Expt Astrophys Dept, Batavia, IL 60510 USA. Univ Chicago, Enrico Fermi Inst, Dept Astron & Astrophys, Chicago, IL 60637 USA. Univ Chicago, Dept Phys, Chicago, IL 60637 USA. CALTECH, Dept Phys, Pasadena, CA 91125 USA. Fermi Natl Accelerator Lab, Fermilab Astrophys Ctr, NASA, Batavia, IL 60510 USA. RP Burles, S (reprint author), Fermi Natl Accelerator Lab, Expt Astrophys Dept, MS 127,POB 500,500 Wilson Rd, Batavia, IL 60510 USA. OI Nollett, Kenneth/0000-0002-0671-320X NR 49 TC 335 Z9 335 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 MAY 1 PY 2001 VL 552 IS 1 BP L1 EP L5 DI 10.1086/320251 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 434EY UT WOS:000168803200001 ER PT J AU Gotthelf, EV Koralesky, B Rudnick, L Jones, TW Hwang, U Petre, R AF Gotthelf, EV Koralesky, B Rudnick, L Jones, TW Hwang, U Petre, R TI Chandra detection of the forward and reverse shocks in Cassiopeia A SO ASTROPHYSICAL JOURNAL LA English DT Article DE supernova remnants; supernovae : individual (Cassiopeia A); X-rays : general ID YOUNG SUPERNOVA-REMNANTS; SYNCHROTRON EMISSION; EJECTA; ACCELERATION; ELECTRONS; SHELL AB We report the localization of the forward and reverse shock fronts in the young supernova remnant Cassiopeia A using X-ray data obtained with the Chandra X-Ray Observatory. High-resolution X-ray maps resolve a previously unseen X-ray feature encompassing the extremity of the remnant. This feature consists of thin, tangential wisps of emission bordering the outer edge of the thermal X-ray and radio remnant, forming a circular rim, similar to2.'7 in radius. Radio images show a sharp rise in brightness at this X-ray rim along with a large jump in the synchrotron polarization angle. These characteristics suggest that these wisps are the previously unresolved signature of the forward, or outer, shock. Similarly, we identify the sharp rise in emissivity of the bright shell for both the radio and X-ray line emission associated with the reverse shock. The derived ratio of the averaged forward and reverse shock radii of similar to3 : 2 constrains the remnant to have swept up roughly the same amount of mass as was ejected; this suggests that Cas A is just entering the Sedov phase. Comparison of the X-ray spectra from the two shock regions shows that the equivalent widths of prominent emission lines are significantly lower exterior to the bright shell, as expected if they are respectively identified with the shocked circumstellar material and shocked ejecta. Furthermore, the spectrum of the outer rim itself is dominated by power-law emission, likely the counterpart of the nonthermal component previously seen at energies above similar to 10 keV. C1 Columbia Univ, Columbia Astrophys Lab, New York, NY 10027 USA. Univ Minnesota, Dept Astron, Minneapolis, MN 55455 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Gotthelf, EV (reprint author), Columbia Univ, Columbia Astrophys Lab, 538 W 120th St, New York, NY 10027 USA. NR 25 TC 129 Z9 129 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 MAY 1 PY 2001 VL 552 IS 1 BP L39 EP L43 DI 10.1086/320250 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 434EY UT WOS:000168803200009 ER PT J AU Strohmayer, TE AF Strohmayer, TE TI Discovery of a 450 Hz quasi-periodic oscillation from the microquasar GRO J1655-40 with the Rossi X-Ray Timing Explorer SO ASTROPHYSICAL JOURNAL LA English DT Article DE black hole physics; stars : individual (GRO J1655-40); stars : oscillations; X-rays : stars ID BLACK-HOLE; SUPERLUMINAL SOURCE; RXTE OBSERVATIONS; NEUTRON-STAR; MASS; BINARIES; MODEL; FREQUENCIES; PRECESSION; OUTBURST AB We report the discovery with the Proportional Counter Array on board the Rossi X-Ray Timing Explorer of a 450 Hz quasi-periodic oscillation (QPO) in the hard X-ray flux from the Galactic microquasar GRO J1655-40. This is the highest frequency QPO modulation seen to date from a black hole. The QPO is detected only in the hard X-ray band above similar to 13 keV. It is both strong and narrow, with a typical rms amplitude of 4.5% in the 13-27 keV range and a width of similar to 40 Hz (FWHM). For two observations in which we detect the 450 Hz QPO, a previously known similar to 300 Hz QPO is also observed in the 2-13 keV band. We show that these two QPOs sometimes appear simultaneously, thus demonstrating the first detection of a pair of high-frequency QPOs in a black hole system. Prior to this, pairs of high-frequency QPOs have been detected only in neutron star systems. GRO J1655-40 is one of only a handful of black hole systems with a good dynamical mass constraint. For a nonrotating black hole with mass between 5.5 and 7.9 M., the innermost stable circular orbit (ISCO) ranges from 45 to 70 km. For any mass in this range the radius at which the orbital frequency reaches 450 Hz is less than the ISCO radius, indicating that, if the modulation is caused by Kepler motion, the black hole must have appreciable spin. If the QPO frequency is set by the orbital frequency of matter at the ISCO, then for this mass range the dimensionless angular momentum lies in the range 0.15 < j < 0.5. Moreover, if the modulation is caused by oscillation modes in the disk or Lense-Thirring precession, then this would also require a rapidly rotating hole. We briefly discuss the implications of our findings for models of X-ray variability in black holes and neutron stars. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Strohmayer, TE (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NR 33 TC 203 Z9 204 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 MAY 1 PY 2001 VL 552 IS 1 BP L49 EP L53 DI 10.1086/320258 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 434EY UT WOS:000168803200011 ER PT J AU Sandell, G Weintraub, DA AF Sandell, G Weintraub, DA TI On the similarity of FU Orionis stars to class I protostars: evidence from the submillimeter SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Review DE circumstellar matter; ISM : clouds; stars : formation; stars : pre-main-sequence; submillimeter ID YOUNG STELLAR OBJECTS; HERBIG-HARO OBJECTS; Z-CANIS-MAJORIS; T-TAURI STARS; INTERMEDIATE-MASS STARS; MAIN-SEQUENCE OBJECTS; MU-M SURVEY; MOLECULAR OUTFLOWS; CIRCUMSTELLAR DISKS; HL TAURI AB On the basis of analysis of new submillimeter maps of a sample of most known FU Orionis stars, we confirm that these stars are extremely young, more similar to Class I protostars than to Class II T Tauri stars. The submillimeter maps reveal that FU Orionis stars have accretion disks that are larger and contain an order of magnitude more mass than those of T Tauri stars but are comparable in mass to those seen around Class I sources. The disks around the FU Orionis stars are sufficiently massive to act as reservoirs of material for replenishing the mass of the disks after eruptions, in which large amounts of material are believed to fall onto the underlying stars. We have identified a number of FU Orionis stars that are surrounded by extended cloud emission, and in several cases we find nearby submillimeter sources that have no optical or near-infrared counterparts. These sources most likely are young protostellar Class I or Class 0 sources. In at least in one case, V1735 Cyg, the dominant submillimeter source is the protostar, not the optically visible FU Orionis star. C1 Natl Radio Astron Observ, Green Bank, WV 24944 USA. Vanderbilt Univ, Dept Phys & Astron, Nashville, TN 37235 USA. RP Sandell, G (reprint author), NASA, USRA, Ames Res Ctr, MS 144-2, Moffett Field, CA 94035 USA. NR 135 TC 78 Z9 79 U1 0 U2 1 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 MAY PY 2001 VL 134 IS 1 BP 115 EP 132 DI 10.1086/320360 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 432TG UT WOS:000168711300006 ER PT J AU Bautista, MA Kallman, TR AF Bautista, MA Kallman, TR TI The XSTAR atomic database SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Review DE astronomical data bases : miscellaneous; atomic data; atomic processes; line : formation; ultraviolet : general; X-rays : general ID ELECTRON-IMPACT-EXCITATION; EFFECTIVE COLLISION STRENGTHS; PHOTOIONIZATION CROSS-SECTIONS; SPECTRAL-LINE INTENSITIES; FINE-STRUCTURE LEVELS; HELIUM-LIKE IONS; BE-LIKE IONS; HE-LIKE IONS; ASTROPHYSICALLY ABUNDANT ELEMENTS; RECOMBINATION RATE COEFFICIENTS AB We report on the XSTAR atomic database that contains a large quantity of atomic rates for use in spectral modeling of astrophysical plasmas. The database includes atomic energy levels, line wavelengths, radiative transition probabilities, electron impact excitation rates, photoionization cross section, recombination rate coefficients, electron impact ionization rates, and fluorescence and Auger yields. The species considered are all the ions of H, He, C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, and Ni. The database collects recent data from many sources including CHIANTI, TOPbase, ADAS, NIST, and the IRON Project. Two particular features of the database are the incorporation of photoionization cross sections from the Opacity Project for all levels of every ion, and state-specific recombination rates. State-specific collisional ionization and three-body recombination are also included. The collection of data is used to build excitation-ionization models of each ion for calculation of their spectra for electron densities of up to 10(18) cm(-3) and temperatures between 100 and 10(9) K. In addition, every ion model is designed to converge to LTE under appropriate conditions. These models and data are implemented in the photoionization modeling code XSTAR v.2. C1 NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Bautista, MA (reprint author), NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 202 TC 111 Z9 112 U1 2 U2 8 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 MAY PY 2001 VL 134 IS 1 BP 139 EP 149 DI 10.1086/320363 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 432TG UT WOS:000168711300008 ER PT J AU Lee, SMC Bishop, PA Schneider, SM Clapp, LL Williams, WJ Conza, N Greenisen, MC AF Lee, SMC Bishop, PA Schneider, SM Clapp, LL Williams, WJ Conza, N Greenisen, MC TI Simulated shuttle egress: Role of helmet visor position during approach and landing SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE Launch and Entry Suit; carbon dioxide; spaceflight; human performance; protective clothing; anti-gravity suits; G-suits AB Background: We previously reported that carbon dioxide (CO,) rapidly accumulates in the helmet of the NASA launch and Entry Suit (LES) during a simulated egress from the Space Shuttle Following 6 min of visor-closed seated rest to simulate approach and landing. The purpose of this study was to determine if CO2 accumulation and walking time in the LES would be improved by helmet visor-open rather than visor-closed seated rest prior to the performance of the simulated egress. Methods: Wearing the LES, 12 male subjects performed 4 laboratory egress simulation; consisting of 6-min seated rest, 2-min stand, and 5-min walk at 1.56 m s(-1) (3.5 mph). During seated rest, subjects sat either with the Visor open, breathing room air until the visor was closed on standing, or with the visor closed for the duration of the simulation. For all visor-closed operations 100% O-2 was supplied. The G-suit was either deflated (0.0 psi) or inflated to 1.5 psi. Inspired CO2 and walking time were measured. Data were analyzed at the end of seated rest, standing, and after 5 min of walking at 0.0 psi or after 2 min of walking at 1.5 psi (>90% of data available). Results: Walk time was not different following visor-open (0.0 psi: 5.0 +/- 0.0; 1.5 psi: 3.4 +/- 0.3 min) or visor-closed (0.0 psi: 4.8 +/- 0.2, 1.5 psi: 3.5 +/- 0.4 mini seated rest at either G-suit pressure. Inspired CO2 levels were not different between the two conditions during walking at 5 min at 0.0 psi (p = 0.50; Open: 4.39 +/- 0.14. Closed: 4.48 +/- 0.18%) or at 2 min at 1.5 psi (p = 0.53; Open: 3.59 +/- 0.12; Closed: 3.65 +/- 0.21%). Conclusions Visor position during seated rest immediately preceding the egress walk had no effect on inspired CO2 or walking time. C1 Univ Alabama, Human Performance Lab, Tuscaloosa, AL USA. Wyle Labs, Life Sci Syst & Serv Div, Houston, TX USA. Swiss Fed Inst Technol, Zurich, Switzerland. NASA, Lyndon B Johnson Space Ctr, Exercise Physiol Lab, Houston, TX 77058 USA. RP Greenisen, MC (reprint author), NASA, Lyndon B Johnson Space Ctr, Exercise Physiol Lab, Mail Code SD3, Houston, TX 77058 USA. NR 13 TC 2 Z9 2 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 MAY PY 2001 VL 72 IS 5 BP 484 EP 489 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 427CX UT WOS:000168388200012 PM 11346016 ER PT J AU Vazquez-Cuervo, J Sumagaysay, R AF Vazquez-Cuervo, J Sumagaysay, R TI A comparison between sea surface temperatures as derived from the European remote sensing along-track scanning radiometer and the NOAA/NASA AVHRR oceans pathfinder dataset SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID SATELLITE RETRIEVALS; CLOUD CONTAMINATION; ATSR; ELIMINATION; BIAS AB The paper focuses on the comparison between the National Oceanic and Atmospheric Administration/National Aeronautics and Space Administration Advanced Very High Resolution Radiometer Oceans Pathfinder sea surface temperature (SST) dataset and SST as derived from the Along-Track Scanning Radiometer (ATSR) onboard the European Remote Sensing Satellite (ERS-1) (ASST). These two datasets provide a unique opportunity for comparing, on global scales, two independent satellite-derived SST retrievals. The comparison was done for data between 1992 and June of 1996. In a preliminary step, mean values and standard deviations of the residuals as defined by the differences between the Modified Pathfinder SST (MPFSST) algorithm and the collocated in situ Pathfinder matchup database were calculated. Globally, as defined by the mean difference, the MPFSST was colder than the in situ data by -0.01 degreesC with a standard deviation of 0.54 degreesC. However, these results were found to vary between ocean basins. The Caribbean showed the largest difference, with a warm mean difference of 0.24 degreesC and a standard deviation of 0.56 degreesC. Mean differences and standard deviations of the residuals as defined by MPFSST - ASST were calculated. The loss of the 3.7-mum channel onboard the ATSR-1 instrument had a larger effect on the nighttime differences and, thus, application of the model to remove residual cloud cover only had a significant impact on the nighttime statistics. A mean difference of 1.40 degreesC, with MPFSST warmer than ASST, and a standard deviation of 0.57 were calculated after the application of the cloud removal model to the ASST. To confirm that part of the differences between the MPFSST and the ASST was due to residual cloud cover, a set of empirical orthogonal functions (EOFs) was extracted from the MPFSST - ASST difference maps, before and after applying the cloud removal model to the ASST. A significant drop from 36% to 14% in the percent variance explained by the first mode indicates that applying the cloud removal algorithm has removed a significant signal from the difference maps. The mean bias for the summation of the first two EOFs is reduced from 0.59 degrees to 0.34 degreesC and the standard deviation from 0.19 degrees to 0.16 degreesC. Thus, a minimum 0.25 degreesC of the signal in the difference maps is due to residual cloud cover in the ASST data. It is concluded that, with improved cloud detection and atmospheric corrections being applied to the ASST, along with improvements to the MPFSST, achieving a 0 degreesC mean difference and a standard deviation of < 0.3 degreesC for global climate studies is possible. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Vazquez-Cuervo, J (reprint author), CALTECH, Jet Prop Lab, M-S 300-323,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 20 TC 7 Z9 7 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD MAY PY 2001 VL 82 IS 5 BP 925 EP 944 DI 10.1175/1520-0477(2001)082<0925:ACBSST>2.3.CO;2 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 428WY UT WOS:000168485700005 ER PT J AU Nelson, ML Maly, K AF Nelson, ML Maly, K TI Buckets: Smart objects for digital libraries SO COMMUNICATIONS OF THE ACM LA English DT Article C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. Old Dominion Univ, Dept Comp Sci, Norfolk, VA 23529 USA. RP NASA, Langley Res Ctr, Hampton, VA 23665 USA. EM m.l.nelson@larc.nasa.gov; maly@cs.odu.edu OI Nelson, Michael/0000-0003-3749-8116 NR 5 TC 6 Z9 6 U1 0 U2 9 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 2 PENN PLAZA, STE 701, NEW YORK, NY 10121-0701 USA SN 0001-0782 EI 1557-7317 J9 COMMUN ACM JI Commun. ACM PD MAY PY 2001 VL 44 IS 5 BP 60 EP 62 DI 10.1145/374308.374342 PG 3 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA 428PH UT WOS:000168469700019 ER PT J AU Ambur, DR Jaunky, N AF Ambur, DR Jaunky, N TI Optimal design of grid-stiffened panels and shells with variable curvature SO COMPOSITE STRUCTURES LA English DT Article DE grid-stiffened panels and shells; curvature; discrete optimizer ID ANISOTROPIC PLATES; BUCKLING ANALYSIS; COMPOSITE PANELS AB A design strategy for optimal design of composite grid-stiffened structures with variable curvature subjected to global and local buckling constraints is developed using a discrete optimizer. An improved smeared stiffener theory is used for the global buckling analysis. Local buckling of skin segments is assessed using a Rayleigh-Ritz method that accounts for material anisotropy and transverse shear flexibility. The local buckling of stiffener segments is also assessed. Design variables are the axial and transverse stiffener spacing, stiffener height and thickness, skin laminate, and stiffening configuration. Stiffening configuration is herein defined as a design variable that indicates the combination of axial, transverse and diagonal stiffeners in the stiffened panel. The design optimization process is adapted to identify the lightest-weight stiffening configuration and stiffener spacing for grid-stiffened composite panels given the overall panel dimensions, in-plane design loads, material properties, and boundary conditions of the grid-stiffened panel or shell. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Mech & Durabil Branch, Hampton, VA 23681 USA. Eagle Aeronaut Inc, Newport News, VA 23606 USA. RP Ambur, DR (reprint author), NASA, Langley Res Ctr, Mech & Durabil Branch, Hampton, VA 23681 USA. NR 13 TC 7 Z9 11 U1 0 U2 6 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 MAY PY 2001 VL 52 IS 2 BP 173 EP 180 DI 10.1016/S0263-8223(00)00165-3 PG 8 WC Materials Science, Composites SC Materials Science GA 426RG UT WOS:000168361700005 ER PT J AU Kamiya, K Warner, BA DiPirro, MJ AF Kamiya, K Warner, BA DiPirro, MJ TI Magnetic shielding for sensitive detectors SO CRYOGENICS LA English DT Article; Proceedings Paper CT US-Japan Joint Seminar on Innovative Measurement Techniques in Cryogenics CY DEC 03-06, 2000 CL TALLAHASSEE, FLORIDA DE ADR; SAFIRE; SOFIA; passive shielding AB This paper describes the design and test of shielding for a superconducting magnet, The magnet is part of an Adiabatic Demagnetization Refrigerator (ADR) for the Submillimeter and Far Infrared Experiment (SAFIRE), a payload on the Stratospheric Observatory for Infrared Astronomy (SOFIA). SAFIRE will use superconducting detectors which must be shielded from the magnet cooling system. Because the detectors use Superconducting Quantum Interference Devices (SQUIDs), the field at the detector package must remain at or below the 10(-7) T level while the detectors are operating. We discuss laboratory tests of the passive shielding and simulations using Poisson group programs. (C) 2001 Published by Elsevier Science Ltd. C1 NASA, Goddard Space Flight Ctr, Cryogen Technol Sect, Greenbelt, MD 20771 USA. RP Kamiya, K (reprint author), NASA, Goddard Space Flight Ctr, Cryogen Technol Sect, Code 552, Greenbelt, MD 20771 USA. NR 6 TC 21 Z9 21 U1 1 U2 4 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0011-2275 J9 CRYOGENICS JI Cryogenics PD MAY-JUN PY 2001 VL 41 IS 5-6 BP 401 EP 405 DI 10.1016/S0011-2275(01)00107-2 PG 5 WC Thermodynamics; Physics, Applied SC Thermodynamics; Physics GA 474GW UT WOS:000171098800018 ER PT J AU Chui, TCP AF Chui, TCP TI SQUID-based high-resolution thermometer SO CRYOGENICS LA English DT Article; Proceedings Paper CT US-Japan Joint Seminar on Innovative Measurement Techniques in Cryogenics CY DEC 03-06, 2000 CL TALLAHASSEE, FLORIDA DE SQUID; high-resolution thermometer; fluctuations ID TEMPERATURE-MEASUREMENT; SUPERFLUID TRANSITION; HEAT-CAPACITY; LAMBDA-POINT; HE-4; HELIUM AB High-resolution thermometers (HRTs) based on the detection of magnetization changes of a magnetic material using very sensitive superconducting quantum interference device (SQUID) have routinely achieved temperature resolution of 0.1 nK/root Hz at temperatures below 4 K in several laboratories. The resolution of these thermometers has reached the fundamental limit imposed by thermodynamic fluctuations. The principle of operation as well as the theory of the noise are presented. Some recent discoveries using HRT are discussed. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chui, TCP (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 79-24, Pasadena, CA 91109 USA. NR 21 TC 2 Z9 2 U1 0 U2 2 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0011-2275 J9 CRYOGENICS JI Cryogenics PD MAY-JUN PY 2001 VL 41 IS 5-6 BP 407 EP 414 DI 10.1016/S0011-2275(01)00111-4 PG 8 WC Thermodynamics; Physics, Applied SC Thermodynamics; Physics GA 474GW UT WOS:000171098800019 ER PT J AU Gabriel, AK Goldstein, RM Blom, RG AF Gabriel, AK Goldstein, RM Blom, RG TI ERS radar interferometry: Absence of recent surface deformation near the Aswan Dam SO ENVIRONMENTAL & ENGINEERING GEOSCIENCE LA English DT Article DE Aswan Dam; structure; interferometry; deformation; synthetic aperture radar; subsidence; Lake Nasser; water height; water loading ID SAR INTERFEROMETRY; LANDERS EARTHQUAKE; VOLCANO; EGYPT C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gabriel, AK (reprint author), CALTECH, Jet Prop Lab, Mail Stop 300-233,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 23 TC 0 Z9 0 U1 0 U2 3 PU ASSOC ENGINEERING GEOLOGISTS GEOLOGICAL SOCIETY AMER PI COLLEGE STN PA TEXAS A & M UNIV, DEPT GEOLOGY & GEOPHYSICS, COLLEGE STN, TX 77843-3115 USA SN 1078-7275 J9 ENVIRON ENG GEOSCI JI Environ. Eng. Geosci. PD MAY PY 2001 VL 7 IS 2 BP 205 EP 210 PG 6 WC Engineering, Environmental; Engineering, Geological; Geosciences, Multidisciplinary SC Engineering; Geology GA 477RG UT WOS:000171297600004 ER PT J AU Leslie, FW Ramachandran, N AF Leslie, FW Ramachandran, N TI A technique for rapidly deploying a concentration gradient with applications to microgravity SO EXPERIMENTS IN FLUIDS LA English DT Article ID MAGNETIC FLUIDS; HEAT-TRANSFER; CONVECTION; INSTABILITY; FIELD AB The latter half of the last century has seen rapid advancements in semiconductor crystal growth powered by the demand for high performance electronics in myriad applications. The reduced gravity environment of space has also been used for crystal growth tests, especially in instances where terrestrial growth has largely been unsuccessful. While reduced gravity crystal growth affords some control of the gravity parameter, many crystals grown in space, to date, have structural flaws believed to result from convective motions during the growth phase. The character of these instabilities is not well understood but is associated with thermal and solutal density variations near the solidification interface in the presence of residual gravity and g-jitter. In order to study these instabilities in a separate, controlled space experiment, a concentration gradient would first have to be artificially established in a timely manner as an initial condition. This is generally difficult to accomplish in a microgravity environment because the momentum of the fluid injected into a test cell tends to swirl around and mix in the absence of a restoring force. The use of magnetic fields to control the motion and position of liquids has received growing interest in recent times. The possibility of using the force exerted by a non-uniform magnetic field on a ferrofluid to not only achieve fluid manipulation but also to actively control fluid motion makes it an attractive candidate for space applications. This paper describes a technique for quickly establishing a linear or exponential fluid concentration gradient using a magnetic field in place of gravity to stabilize the deployment. Also discussed is a photometric technique for measuring the concentration profile using light attenuation. Results of the ground-based experiments indicate that the concentration distribution is within 3% of the predicted value. Although any range of concentations can be realized, photometric constraints are discussed which impose some limitations on measurements. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. RP Leslie, FW (reprint author), NASA, George C Marshall Space Flight Ctr, Mail Code SD47, Huntsville, AL 35812 USA. NR 22 TC 1 Z9 1 U1 0 U2 2 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0723-4864 J9 EXP FLUIDS JI Exp. Fluids PD MAY PY 2001 VL 30 IS 5 BP 568 EP 577 DI 10.1007/s003480000237 PG 10 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 434CY UT WOS:000168798600011 ER PT J AU Tanaka, KL Banerdt, WB Kargel, JS Hoffman, N AF Tanaka, KL Banerdt, WB Kargel, JS Hoffman, N TI Huge, CO(2)-charged debris-flow deposit and tectonic sagging in the northern plains of Mars SO GEOLOGY LA English DT Article DE Mars; debris flows; sedimentation rates; erosion rates; CO(2) ID TOPOGRAPHY; METEORITE; ALH84001; HISTORY; OCEANS; MODEL; CO2 AB The northern plains of R lars contain a vast deposit, covering one-sixth of the planet, that apparently resulted in extensive lithospheric deformation. The center of the deposit may be as much as 2-3 km thick. The deposit has lobate margins consistent with the how of fluidized debris for hundreds to thousands of kilometers derived from highland and high-plains sources. The deposit surface lowers inward by similar to 900 m in places and is locally bordered by a bulge similar to 300 m high. Similar deformation accompanied development of Pleistocene ire sheets on Earth. The lack of burial of a large inlier of older terrain and the response time of the mantle to the loading require that the deposit was emplaced in < 1000 yr, assuming that the deposit was originally flat. We account for what may have been the largest catastrophic erosional and/or depositional event in solar system history by invoking pore-filling subsurface CO(2) as an active agent in the processes of source-rock collapse and debris flow. C1 US Geol Survey, Flagstaff, AZ 86001 USA. Jet Prop Lab, Pasadena, CA 91109 USA. La Trobe Univ, Bundoora, Vic 3083, Australia. RP Tanaka, KL (reprint author), US Geol Survey, Flagstaff, AZ 86001 USA. NR 28 TC 39 Z9 39 U1 0 U2 2 PU GEOLOGICAL SOC AMER, INC PI BOULDER PA PO BOX 9140, BOULDER, CO 80301-9140 USA SN 0016-8505 J9 GEOLOGY JI Geology PD MAY PY 2001 VL 29 IS 5 BP 427 EP 430 DI 10.1130/0091-7613(2001)029<0427:HCCDFD>2.0.CO;2 PG 4 WC Geology SC Geology GA 428DJ UT WOS:000168445700013 ER PT J AU Kuang, WJ Chao, BF AF Kuang, WJ Chao, BF TI Topographic Core-Mantle coupling in Geodynamo modeling SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID BOUNDARY TOPOGRAPHY; ANGULAR-MOMENTUM; FLOW; DYNAMICS; SURFACE AB A 8-dimensional, fully nonlinear numerical geo-dynamo model is used to study the core-mantle coupling arising from a non-hydrostatic pressure field acting on an aspherical core-mantle boundary (CMB) based on a seismological model. The simulation results demonstrate that the topographic coupling torque is close to being proportional to the square of the amplitude of the CMB topography. We conclude that the contribution of the topographic coupling to the total torque that is responsible for the axial angular momentum transfer on decadal timescales (for the decadal length-of-day variation) is significant only if the amplitude of the CMB topography is considerably larger than 3km inferred from seismological evidence. C1 Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21250 USA. NASA, Goddard Space Flight Ctr, Space Geodesy Branch, Greenbelt, MD 20771 USA. RP Kuang, WJ (reprint author), Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21250 USA. RI Kuang, Weijia/K-5141-2012; Chao, Benjamin Fong/N-6156-2013 OI Kuang, Weijia/0000-0001-7786-6425; NR 15 TC 18 Z9 22 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 MAY 1 PY 2001 VL 28 IS 9 BP 1871 EP 1874 DI 10.1029/2000GL012237 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 424QN UT WOS:000168243100051 ER PT J AU Moore, JM Asphaug, E Belton, MJS Bierhaus, B Breneman, HH Brooks, SM Chapman, CR Chuang, FC Collins, GC Giese, B Greeley, R Head, JW Kadel, S Klaasen, KP Klemaszewski, JE Magee, KP Moreau, J Morrison, D Neukum, G Pappalardo, RT Phillips, CB Schenk, PM Senske, DA Sullivan, RJ Turtle, EP Williams, KK AF Moore, JM Asphaug, E Belton, MJS Bierhaus, B Breneman, HH Brooks, SM Chapman, CR Chuang, FC Collins, GC Giese, B Greeley, R Head, JW Kadel, S Klaasen, KP Klemaszewski, JE Magee, KP Moreau, J Morrison, D Neukum, G Pappalardo, RT Phillips, CB Schenk, PM Senske, DA Sullivan, RJ Turtle, EP Williams, KK TI Impact features on Europa: Results of the Galileo Europa Mission (GEM) SO ICARUS LA English DT Article DE Europa; cratering; satellites of Jupiter ID CRATER FORMATION; SATELLITES; CALLISTO; GANYMEDE; VELOCITY; JUPITER; CHAOS; SIZE AB During the Galileo Europa Mission (GEM), impact features on Europa were observed with improved resolution and coverage was compared with Voyager or the Galileo nominal mission. We surveyed all primary impact features >4 km in diameter seen on Europa (through orbit E19). The transition from simple to complex crater morphology occurs at a diameter of about 5 km. We calculated the transient crater dimensions and excavation depths of all craters surveyed. The largest impact feature (Tyre) probably had a transient crater depth between 5 and 10 km and transported material to the surface from a depth of not greater than similar to4 km. Craters < 30 km in diameter, such as Manannan and Pwyll, formed within targets whose immediate subcrater materials exhibited nonfluid behavior on time scales of the impact event, and that are capable, especially in the case of Pwyll, of supporting significant local topographic loads such as a central peak. These craters are nevertheless quite shallow, with very subdued floors, and we suspect that Manannan and Pwyll's small depth-to-diameter ratios are due to the isostatic adjustment of large-scale topography, facilitated by warm, plastically deformable ice at depth. Morphological similarities between Callanish and Tyre strongly imply that conclusions reached regarding Callanish in J. Moore et al. (1998, Icarus 135, 127-145) also apply to Tyre, which was that Callanish is the consequence of impact into target materials that are mechanically very weak at depth. New evidence that Callanish's circumferential rings formed before the proximal ejecta became immobile implies a low-viscosity substrate at the time of impact. We also report additional evidence that a component of the proximal ejecta of Callanish was emplaced as a fluid. Our observations of Pwyll secondaries support the conclusions stated in Alpert and Melosh (1999) that impacts on icy bodies eject smaller fragments and that fragment size decreases more gradually as velocity increases than observed for impacts on silicate bodies at equivalent ejection velocities. Examination of Pwyll's secondary craters reveals azimuthal variations, with ejecta fragment sizes being larger near the center of a ray than off the ray. Our initial analysis of the characteristic size distribution of Pwyll's secondary craters shows that they form a differential slope slightly shallower than -4, Similar steep slopes for small craters on Ganymede imply that small craters there are mostly formed by secondary impact, and the jovian system may thus be deficient in small impacts relative to the environment of the terrestrial planets. (C) 2001 Academic Press. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Santa Cruz, Dept Earth Sci, Santa Cruz, CA 95064 USA. Kitt Peak Natl Observ, Tucson, AZ 85726 USA. SW Res Inst, Boulder, CO 80302 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Arizona State Univ, Dept Geol Sci, Tempe, AZ 85287 USA. Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. DLR, Inst Planetary Explorat, D-12489 Berlin, Germany. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Lunar & Planetary Inst, Houston, TX 77058 USA. Cornell Univ, Ithaca, NY 14853 USA. RP Moore, JM (reprint author), NASA, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. RI Turtle, Elizabeth/K-8673-2012; OI Turtle, Elizabeth/0000-0003-1423-5751; Moreau, John W/0000-0002-5997-522X NR 30 TC 49 Z9 49 U1 1 U2 8 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 2001 VL 151 IS 1 BP 93 EP 111 DI 10.1006/icar.2000.6558 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 428BZ UT WOS:000168442400008 ER PT J AU Larsen, WE Cooksy, KD Zuk, J AF Larsen, WE Cooksy, KD Zuk, J TI Managing aviation safety through inspection and information technology SO IEEE INDUSTRY APPLICATIONS MAGAZINE LA English DT Article C1 Fed Aviat Adm, Washington, DC USA. Amer Technol Initiat, Menlo Park, CA USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Larsen, WE (reprint author), Fed Aviat Adm, Washington, DC USA. NR 18 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1077-2618 J9 IEEE IND APPL MAG JI IEEE Ind. Appl. Mag. PD MAY-JUN PY 2001 VL 7 IS 3 BP 40 EP 45 DI 10.1109/2943.922449 PG 6 WC Engineering, Industrial; Engineering, Electrical & Electronic SC Engineering GA 425MK UT WOS:000168294400009 ER PT J AU Filman, RE AF Filman, RE TI Medicine on the Net - From isolation to universal Connectivity SO IEEE INTERNET COMPUTING LA English DT Editorial Material C1 NASA, Ames Res Ctr, Adv Comp Sci Res Inst, Ames, IA USA. RP Filman, RE (reprint author), NASA, Ames Res Ctr, Adv Comp Sci Res Inst, Ames, IA USA. NR 0 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 90720-1314 USA SN 1089-7801 J9 IEEE INTERNET COMPUT JI IEEE Internet Comput. PD MAY-JUN PY 2001 VL 5 IS 3 BP 40 EP 41 DI 10.1109/MIC.2001.935175 PG 2 WC Computer Science, Software Engineering SC Computer Science GA 436BH UT WOS:000168916300006 ER PT J AU Siegel, PH Divsalar, D Eleftheriou, E Hagenauer, J Rowitch, D Tranter, WH AF Siegel, PH Divsalar, D Eleftheriou, E Hagenauer, J Rowitch, D Tranter, WH TI The turbo principle: From theory to practice SO IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS LA English DT Editorial Material C1 Univ Calif San Diego, La Jolla, CA 92093 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. IBM Res, CH-8803 Ruschlikon, Switzerland. Tech Univ Munich, D-80290 Munich, Germany. Qualcomm Inc, San Diego, CA 92121 USA. RP Siegel, PH (reprint author), Univ Calif San Diego, La Jolla, CA 92093 USA. NR 0 TC 20 Z9 21 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0733-8716 J9 IEEE J SEL AREA COMM JI IEEE J. Sel. Areas Commun. PD MAY PY 2001 VL 19 IS 5 BP 793 EP 799 DI 10.1109/JSAC.2001.924863 PG 7 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 436GH UT WOS:000168927800001 ER PT J AU Divsalar, D Dolinar, S Pollara, F AF Divsalar, D Dolinar, S Pollara, F TI Iterative turbo decoder analysis based on density evolution SO IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS LA English DT Article DE concatenated mixture codes; density evolution; iterative decoding analysis; noise figure; serially concatenated codes; turbo codes ID CODES; DESIGN AB We track the density of extrinsic information in iterative turbo decoders by actual density evolution, and also approximate it by symmetric Gaussian density functions, The approximate model is verified by experimental measurements. We view the evolution of these density functions through an iterative decoder as a nonlinear dynamical system with feedback, Iterative decoding of turbo codes and of serially concatenated codes is analyzed by examing whether a sign-to-noise ratio (SNR) for the extrinsic information keeps growing with iterations, We define a "noise figure" for the iterative decoder, such that the turbo decoder will converge to the correct codeword if the noise figure is bounded by a number below zero dB, By decomposing the code's noise figure into individual curves of output SNR versus input SNR corresponding to the individual constituent codes, we gain many new insights into the performance of the iterative decoder for different constituents. Many mysteries of turbo codes tire explained based on this analysis, For example, we show why certain codes converge better with iterative decoding than more powerful codes which are only suitable for maximum likelihood decoding, The roles of systematic bits and of recursive convolutional codes as constituents of turbo codes are crystallized. The analysis is generalized to serial concatenations of mixtures of complementary outer and inner constituent codes. Design examples are given to optimize mixture codes to achieve low iterative decoding thresholds on the signal-to-noise ratio of the channel. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Divsalar, D (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 28 TC 179 Z9 184 U1 1 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0733-8716 J9 IEEE J SEL AREA COMM JI IEEE J. Sel. Areas Commun. PD MAY PY 2001 VL 19 IS 5 BP 891 EP 907 DI 10.1109/49.924873 PG 17 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 436GH UT WOS:000168927800011 ER PT J AU Berenji, HR Saraf, S Chang, PW Swanson, SR AF Berenji, HR Saraf, S Chang, PW Swanson, SR TI Pitch control of the space shuttle training aircraft SO IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY LA English DT Article DE attitude control; fuzzy control; nonminimum phase systems; orbiter simulation; pitch control AB A set of shuttle training aircrafts (STAs) are used by NASA to train astronaut pilots to land the space shuttle after returning from orbit. The STA simulates the dynamics of the much larger and heavier space shuttle with the help of some hardware and software modifications. In this paper, we present a new STA controller that tracks the shuttle pitch trajectory. Our control system includes a feedforward controller based on zero phase error tracking control and a fuzzy proportional derivative (PD) feedback controller. Test results on a ground hardware simulator used at the Ellington field of NASA Johnson Space Center show that the new controller significantly reduces pitch following errors between the shuttle and the STA, when compared to the existing controller. C1 NASA, Ames Res Ctr, Intelligent Inference Syst Corp, Moffett Field, CA 94035 USA. NASA, Lyndon B Johnson Space Ctr, Shuttle Training Branch, Ellington Field, TX USA. RP Berenji, HR (reprint author), NASA, Ames Res Ctr, Intelligent Inference Syst Corp, Moffett Field, CA 94035 USA. NR 4 TC 5 Z9 6 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1063-6536 J9 IEEE T CONTR SYST T JI IEEE Trans. Control Syst. Technol. PD MAY PY 2001 VL 9 IS 3 BP 542 EP 551 DI 10.1109/87.918906 PG 10 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA 427JR UT WOS:000168401500011 ER PT J AU Anderson, BJ Zanetti, LJ Lohr, DH Hayes, JR Acuna, MH Russell, CT Mulligan, T AF Anderson, BJ Zanetti, LJ Lohr, DH Hayes, JR Acuna, MH Russell, CT Mulligan, T TI In-flight calibration of the NEAR magnetometer SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE calibration; extraterrestrial measurements; magnetometers ID SOLAR-WIND INTERACTION; SMALL BODIES; GASPRA; SYSTEM; IDA AB The science objectives for the Near Earth Asteroid Rendezvous (NEAR) Magnetometer Experiment (MAG) are to measure a possible magnetic field of 433 Eros to 5 nT accuracy and secondarily to detect asteroid-solar wind interaction signatures. Because the MAG sensor is body mounted, achieving this accuracy required detailed analysis of spacecraft magnetic fields during cruise. Sources of magnetic contamination identified prior to launch and during cruise are: propulsion latch valves, fixed 190 nT residual field, solar arrays and power harness, variable 15 to 60 nT held, power distribution terminal board, similar to 30 nT field with 5 nT variations, power shunting circuitry, 1-5 nT variations, the MAG sensor survival heater 6 nT steps and attitude control momentum wheels, and 1 nT amplitude at 0.5 to 10 Hz from each of four wheels. Analysis of cruise data was used to create accurate +/-1 nT models for the tired and variable fields with signals below 0.5 Hz to provide correction of the raw data. The spacecraft field corrections and MAG calibration were validated with data from the Earth swing-by of January 1997. Comparison of solar wind magnetic field measurements from the WIND spacecraft and NEAR from January 22-24, 1997, before and after the Earth swing-by maneuver, confirm that the resulting NEAR magnetic field measurements are accurate to 1-2 nT. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA. RP Anderson, BJ (reprint author), Johns Hopkins Univ, Appl Phys Lab, Johns Hopkins Rd, Laurel, MD 20723 USA. RI Anderson, Brian/I-8615-2012; OI Russell, Christopher/0000-0003-1639-8298 NR 13 TC 13 Z9 14 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 2001 VL 39 IS 5 BP 907 EP 917 DI 10.1109/36.921408 PG 11 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 431GJ UT WOS:000168623200001 ER PT J AU Fung, AK Zuffada, C Hsieh, CY AF Fung, AK Zuffada, C Hsieh, CY TI Incoherent bistatic scattering from the sea surface at L-band SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID OCEAN; MODEL AB A bistatic electromagnetic wave scattering model for the sea surface is developed to examine its wind dependence property over a wide range of incident angles along the specular direction. This is done by combining an existing scattering model with a sea spectrum recently reported in the literature. In general, electromagnetic wave scattering from a rough surface is dependent on the Fourier transform of the nth power of its height correlation function which can be computed numerically from the surface spectrum. This transform relation indicates that scattering is sensitive not only to the surface spectrum but also to its convoluted properties. Generally, surface scattering is sensitive only to a portion of the surface correlation measured from the origin. The size of this portion is a function of three variables (the incident angle, the surface height standard deviation, and the exploring wavelength) and the rate of decay of the correlation function. The decay rate near the origin of the sea surface correlation is very small, so much so that at L-band this portion is too wide for a two-term approximation of the correlation function,This is true in spite of the fact that the sea surface has a very large rms height. Thus, a scattering model based on geometric optics is generally not applicable at L-band especially at large angles of incidence. An additional finding is that in specular scattering wind dependence is stronger at larger angles of incidence for incident angles between 0 and 70 degrees over the wind speed range of 4 m/s-20 m/s. C1 Univ Texas, Wave Scattering Res Ctr, Arlington, TX 76019 USA. Jet Prop Lab, Pasadena, CA 91109 USA. Natl Kaohsiung Inst Marine Technol, Dept Elect & Comp Engn, Kaohsiung, Taiwan. RP Fung, AK (reprint author), Univ Texas, Wave Scattering Res Ctr, Arlington, TX 76019 USA. NR 12 TC 24 Z9 26 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 2001 VL 39 IS 5 BP 1006 EP 1012 DI 10.1109/36.921418 PG 7 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 431GJ UT WOS:000168623200011 ER PT J AU Wilson, WJ Yueh, SH Dinardo, SJ Chazanoff, SL Kitiyakara, A Li, FK Rahmat-Samii, Y AF Wilson, WJ Yueh, SH Dinardo, SJ Chazanoff, SL Kitiyakara, A Li, FK Rahmat-Samii, Y TI Passive active L- and S-band (PALS) microwave sensor for ocean salinity and soil moisture measurements SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE radiometers; salinity; scatterometers; soil moisture AB A passive/active L/S-band (PALS) microwave aircraft instrument to measure ocean salinity and soil moisture has been built and tested. Because the L-band brightness temperatures associated with salinity changes are expected to be small, it was necessary to build a very sensitive and stable system. This new instrument has dual-frequency, dual polarization radiometer and radar sensors. The antenna is a high beam efficiency conical horn. The PALS instrument was installed on the NCAR C-130 aircraft and soil moisture measurements were made in support of the Southern Great Plains 1999 experiment in Oklahoma from July 8-14, 1999, Data taken before and after a rainstorm showed significant changes in the brightness temperatures, polarization ratios and radar backscatter, as a function of soil moisture. Salinity measurement missions were flown on July 17-19, 1999, southeast of Norfolk, VA, over the Gulf Stream. The measurements indicated a clear and repeatable salinity signal during these three days, which was in good agreement with the Cape Hatteras ship salinity data. Data was also taken in the open ocean and a small decrease of 0.2 K was measured in the brightness temperature, which corresponded to the salinity increase of 0.4 psu measured by the MN Oleander vessel. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Dept Elect Engn, Los Angeles, CA 90024 USA. RP Wilson, WJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 69 Z9 76 U1 1 U2 10 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 MAY PY 2001 VL 39 IS 5 BP 1039 EP 1048 DI 10.1109/36.921422 PG 10 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 431GJ UT WOS:000168623200015 ER PT J AU Yueh, SH West, R Wilson, WJ Li, FK Njoku, EG Rahmat-Samii, Y AF Yueh, SH West, R Wilson, WJ Li, FK Njoku, EG Rahmat-Samii, Y TI Error sources and feasibility for microwave remote sensing of ocean surface salinity SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE microwave radiometry; remote sensing; scatterometry; sea salinity ID PERMITTIVITY MEASUREMENTS; SEA; DEPENDENCE; EMISSION; MODEL AB A set of geophysical error sources for the microwave remote sensing of ocean surface salinity have been examined. The error sources include the sea surface temperature, sea surface roughness, atmospheric gases, ionospheric Faraday rotation, and solar and galactic emission sources. It is shown that the brightness temperature effects of a few kelvin can be expected for most of these error sources. The hey correction requirements for accurate salinity measurements are the knowledge accuracy of 0.5 degreesC for the sea surface temperature (SST), 10 mbar for the surface air pressure, 2 degreesC for the surface air temperature, 0.2 degrees accuracy for the Faraday rotation, and Surface roughness equivalent to 0.3 m . s(-1) for the surface wind speed. We suggest the use of several data products for corrections, including the AMSR-type instruments for SST and liquid cloud water, the AMSU-type product for air temperature, the scatterometer products or numerical weather analysis for the air pressure, coincidental radar observations with 0.2 dB precision for surface roughness, and on-board polarimetric radiometer channel for Faraday rotation. The most significant sky radiation is from the sun. A careful design of the antenna is necessary to minimize the leakage of solar radiation or reflection into the antenna sidelobes. The narrow-band radiation from galactic hydrogen clouds with a bandwidth of less than 1 MHz is also significant, but can be corrected with a radio sky survey or minimized with a notched (band-rejection) filter centered at 1.421 GHz. The other planetary and galactic radio sources can also be flagged with a small data loss. We have performed a sampling analysis for a polar-orbiting satellite with 900 km swath width to determine the number of satellite observations over a given surface grid cell during an extended period. Under the assumption that the observations from different satellite passes are independent, it is suggested that an accuracy of 0.1 psu (practical salinity unit) is achievable for global monthly 1 degrees latitude by 1 degrees longitude gridded products. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Los Angeles, CA 90024 USA. RP Yueh, SH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 25 TC 106 Z9 120 U1 0 U2 11 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 MAY PY 2001 VL 39 IS 5 BP 1049 EP 1060 DI 10.1109/36.921423 PG 12 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 431GJ UT WOS:000168623200016 ER PT J AU Liu, JM Maluf, DA Desmarais, MC AF Liu, JM Maluf, DA Desmarais, MC TI A new uncertainty measure for belief networks with applications to optimal evidential inferencing SO IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING LA English DT Article DE belief networks; uncertainty modeling and management; discrete event dynamical systems; optimal evidential inferencing; controller; observer; entropy; user profile assessment AB This paper is concerned with the problem of measuring the uncertainty in a broad class of belief networks, as encountered in evidential reasoning applications. In our discussion, we give an explicit account of the networks concerned, and coin them the Dempster-Shafer (D-S) belief networks. We examine the essence and the requirement of such an uncertainty measure based on well-defined discrete event dynamical systems concepts. Furthermore, we extend the notion of entropy for the D-S belief networks in order to obtain an improved optimal dynamical observer. The significance and generality of the proposed dynamical observer of measuring uncertainty for the D-S belief networks lie in that it can serve as a performance estimator as well as a feedback for improving both the efficiency and the quality of the D-S belief network-based evidential inferencing. We demonstrate, with Monte Carte simulation, the implementation and the effectiveness of the proposed dynamical observer in solving the problem of evidential inferencing with optimal evidence node selection. C1 Hong Kong Baptist Univ, Dept Comp Sci, Kowloon, Hong Kong, Peoples R China. NASA, Ames Res Ctr, RIACS, Moffett Field, CA 94035 USA. Publ Technol Multimedia, Montreal, PQ H2L 1L3, Canada. RP Liu, JM (reprint author), Hong Kong Baptist Univ, Dept Comp Sci, Kowloon, Hong Kong, Peoples R China. NR 19 TC 3 Z9 3 U1 0 U2 3 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1041-4347 J9 IEEE T KNOWL DATA EN JI IEEE Trans. Knowl. Data Eng. PD MAY-JUN PY 2001 VL 13 IS 3 BP 416 EP 425 DI 10.1109/69.929899 PG 10 WC Computer Science, Artificial Intelligence; Computer Science, Information Systems; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 440DT UT WOS:000169161200007 ER PT J AU Ponchak, GE Margomenos, A Katehi, LPB AF Ponchak, GE Margomenos, A Katehi, LPB TI Low-loss CPW on low-resistivity Si substrates with a micromachined polyimide interface layer for RFIC interconnects SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article DE attenuation; coplanar waveguide; interconnects ID COPLANAR WAVE-GUIDES; X-BAND; ATTENUATION; COMPONENTS AB The measured and calculated propagation constant of coplanar waveguide (CPW) on low-resistivity silicon (1 Omega . cm) with a micromachined polyimide interface layer is presented in this paper, With this new structure, the attenuation (decibels per centimeter) of narrow CPW lines on low-resistivity silicon is comparable to the attenuation of narrow CPW lines on high-resistivity silicon, To achieve these results, a 20-mum-thick polyimide interface layer is used between the CPW and the Si substrate with the polyimide etched from the CPW slots. only a single thin-film metal layer is used in this paper, but the technology supports multiple thick metal layers that will further lower the attenuation. These new micromachined CPW lines have a measured effective permittivity of 1.3. Design rules are presented from measured characteristics and finite-element method analysis to estimate the required polyimide thickness for a given CPW geometry. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Univ Michigan, Dept Elect Engn & Comp Sci, Ann Arbor, MI 48109 USA. RP Ponchak, GE (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 16 TC 69 Z9 71 U1 0 U2 4 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 MAY PY 2001 VL 49 IS 5 BP 866 EP 870 DI 10.1109/22.920142 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA 429KK UT WOS:000168515800003 ER PT J AU Wier, LT Ayers, GW Jackson, AS Rossum, AC Poston, WSC Foreyt, JP AF Wier, LT Ayers, GW Jackson, AS Rossum, AC Poston, WSC Foreyt, JP TI Determining the amount of physical activity needed for long-term weight control SO INTERNATIONAL JOURNAL OF OBESITY LA English DT Article DE weight control; body weight; physical activity; aging; gender ID ALL-CAUSE MORTALITY; PREDICTING BODY DENSITY; AEROBIC POWER; GENERALIZED EQUATIONS; MEN; ADULTS; WOMEN; MAINTENANCE; EXERCISE; HEALTHY AB OBJECTIVE: To evaluate prospectively the influence of habitual physical activity on body weight of men and women and to develop a model that defines the role of physical activity on longitudinal weight change. DESIGN AND SETTING: Occupational cohort study conducted for a mean of 5.5y. SUBJECTS: A total of 496 (341 male and 155 female) NASA/Johnson Space Center employees who completed the 3 month education component of the employee health-related fitness program and remained involved for a minimum of 2y. MEASUREMENTS: Body weights were measured at baseline (T1) and follow-up (T2), and habitual physical activity was obtained from the mean of multiple ratings of the 11-point (0-10) NASA Activity Scale (NAS) recorded quarterly between T1 and T2. Other measures included age, gender, VO2 max obtained from maximal treadmill testing, body mass index (BMI), and body fat percentage. RESULTS: Multiple regression demonstrated that mean NAS, T1 weight, aging and gender all influence long-term T2 weight. T1 age was significant for the men only. independently, each increase in mean NAS significantly (P < 0.01) reduced T2 weight in men (b= - 0.91 kg; 95% CI: - 1.4 to - 0.42 kg) and women (b = - 2.14 kg; 95% CI: - 2.93 to - 1.35 kg). Mean NAS had a greater effect on T2 weight as T1 weight increased, and the relationship was dose-dependent. CONCLUSIONS: Habitual physical activity is a significant source of long-term weight change. The use of self-reported activity level is helpful in predicting long-term weight changes and may be used by health care professionals when counseling patients about the value of physical activity for weight control. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Houston, Dept Hlth & Human Performance, Houston, TX USA. NASA, Johnson Space Ctr, Kelsey Seybold Clin, Houston, TX USA. Univ Missouri, Kansas City, MO 64110 USA. Baylor Coll Med, Behav Med Res Ctr, Houston, TX 77030 USA. RP Wier, LT (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code AW-9, Houston, TX 77058 USA. NR 43 TC 34 Z9 34 U1 3 U2 7 PU NATURE PUBLISHING GROUP PI BASINGSTOKE PA HOUNDMILLS, BASINGSTOKE RG21 6XS, HAMPSHIRE, ENGLAND SN 0307-0565 J9 INT J OBESITY JI Int. J. Obes. PD MAY PY 2001 VL 25 IS 5 BP 613 EP 621 DI 10.1038/sj.ijo.0801586 PG 9 WC Endocrinology & Metabolism; Nutrition & Dietetics SC Endocrinology & Metabolism; Nutrition & Dietetics GA 425MQ UT WOS:000168294900004 PM 11360142 ER PT J AU Noor, A Birman, V AF Noor, A Birman, V TI Honoring the 70th birthday of Prof. Jack Vinson and Prof. Charles Bert SO INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES LA English DT Editorial Material C1 Univ Virginia, Ctr Adv Computat Technol, NASA, Langley Res Ctr, Hampton, VA 23681 USA. Univ Missouri, Engn Educ Ctr, St Louis, MO 63121 USA. RP Noor, A (reprint author), Univ Virginia, Ctr Adv Computat Technol, NASA, Langley Res Ctr, Mail Stop 201, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 2 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0020-7683 J9 INT J SOLIDS STRUCT JI Int. J. Solids Struct. PD MAY PY 2001 VL 38 IS 19 BP 3305 EP 3307 DI 10.1016/S0020-7683(00)00258-4 PG 3 WC Mechanics SC Mechanics GA 419QX UT WOS:000167961100001 ER PT J AU Ryzhii, V Khmyrova, I Ishibashi, T Bandara, SV Gunapala, SD AF Ryzhii, V Khmyrova, I Ishibashi, T Bandara, SV Gunapala, SD TI High-frequency characteristics of quantum well infrared photodetectors with blocking barrier SO JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS LA English DT Article DE quantum well infrared photodetector; superlattice; blocking barrier; responsivity; high-frequency ID TRAVELING-CARRIER PHOTODIODES; ELECTRON-TRANSPORT; TRANSIT-TIME; CAPTURE; SUPERLATTICE; DETECTORS AB We have developed an analytical model for quantum well infrared photodetectors (QWIPs) with a superlattice serving as the absorption region and a blocking barrier. The explicit analytical expression for the frequency-dependent responsivity is derived as a function of the QWIP structural parameters. Using this expression we calculate the 3 dB cut-off frequency and bandwidth-response efficiency. The bandwidth of QWIPs with a moderate number of QWs can exceed 100 GHz exhibiting fairly large responsivity. We show that a fast tunneling filling of the absorption region by the electrons injected from the emitter contact results in a significant modification of the high-frequency properties of the QWIP under consideration compared to the standard QWIPs, in particular, in the elimination of the low-frequency peak of the responsivity. C1 Univ Aizu, Comp Solid State Phys Lab, Aizu Wakamatsu, Wakamatsu 9658580, Japan. Nippon Telegraph & Tel Corp, Photon Lab, Atsugi, Kanagawa 2430198, Japan. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Univ Aizu, Comp Solid State Phys Lab, Aizu Wakamatsu, Wakamatsu 9658580, Japan. NR 33 TC 1 Z9 1 U1 0 U2 2 PU JAPAN SOC APPLIED PHYSICS PI TOKYO PA KUDAN-KITA BUILDING 5TH FLOOR, 1-12-3 KUDAN-KITA, CHIYODA-KU, TOKYO, 102-0073, JAPAN SN 0021-4922 J9 JPN J APPL PHYS 1 JI Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Brief Commun. Rev. Pap. PD MAY PY 2001 VL 40 IS 5A BP 3137 EP 3142 DI 10.1143/JJAP.40.3137 PG 6 WC Physics, Applied SC Physics GA 468RM UT WOS:000170772000017 ER PT J AU Chandrasekhara, MS Wilder, MC Carr, LW AF Chandrasekhara, MS Wilder, MC Carr, LW TI Compressible dynamic stall control: Comparison of two approaches SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA 17th Applied Aerodynamics Conference CY JUN 28-JUL 01, 1999 CL NORFOLK, VIRGINIA SP Amer Inst Aeronaut & Astronaut AB The approaches of compressible dynamic stall control using real-time airfoil adaptation and slatted airfoils are compared, Each method attempts to solve the unsteady flow separation and the underlying causes differently. The approaches lead to unexpected results: For the slatted airfoil, dynamic stall alleviation on the main airfoil with a fully stalled slat occurred, and for the shape adapting airfoil, leading-edge attached how with trailing-edge separation was obtained. In both cases, no dynamic stall vortex was present. As can he expected, the control effectiveness of each method varies over the full cycle and depends on the Mach number due to the new factors introduced by the use of the methods, These issues are addressed. C1 USN, Postgrad Sch, NASA,Dept Aeronaut & Astronauts, Joint Inst Aeronaut, Monterey, CA 93943 USA. ELORET, Sunnyvale, CA 94087 USA. NASA, Ames Res Ctr, Aeroflightdynam Directorate, Moffett Field, CA 94035 USA. RP Chandrasekhara, MS (reprint author), NASA, Ames Res Ctr, MS 260-1, Moffett Field, CA 94035 USA. NR 15 TC 2 Z9 2 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAY-JUN PY 2001 VL 38 IS 3 BP 448 EP 453 DI 10.2514/2.2812 PG 6 WC Engineering, Aerospace SC Engineering GA 441LV UT WOS:000169232600006 ER PT J AU Seifert, A Pack, LG AF Seifert, A Pack, LG TI Oscillatory control of shock-induced separation SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA 37th Aerospace Sciences Meeting and Exhibit CY JAN 11-14, 1999 CL RENO, NEVADA SP Amer Inst Aeronaut & Astronaut ID AIRFOIL; DELAY; STALL AB An experimental investigation, aimed at delaying Bow separation as a result of the occurrence of a shock-wave/boundary-lager interaction, is reported. The experiment was performed using a NACA 0015 airfoil at high-Reynolds-number incompressible and compressible flow conditions. The effects of Mach and Reynolds numbers were identified, using the capabilities of the cryogenic-pressurized facility to maintain one parameter fixed and change the other. The main objectives of the experiment were to study the effects of periodic excitation on airfoil drag divergence and to alleviate the severe unsteadiness associated with shock-induced separation (known as buffeting), Zero-mass-flux oscillatory blowing was introduced through a downstream directed slot located at 10% chord on the upper surface of the NACA 0015 airfoil. The effective frequencies generated 2-4 vortices over the separated region, regardless of the Mach number. Even though the excitation was introduced upstream of the shock wave, it had pronounced effects downstream of it. Wake deficit (associated with drag) and unsteadiness (associated with buffeting) were reduced. The spectral content of the wake pressure fluctuations indicates steadier how throughout the frequency range when excitation is applied. This is especially evident at low frequencies which are more likely to interact with the airframe. C1 NASA, Langley Res Ctr, Flow Phys & Control Branch, Hampton, VA 23681 USA. RP Seifert, A (reprint author), Tel Aviv Univ, Fac Engn, Dept Fluid Mech & Heat Transfer, IL-69978 Ramat Aviv, Israel. NR 23 TC 9 Z9 9 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAY-JUN PY 2001 VL 38 IS 3 BP 464 EP 472 DI 10.2514/2.2815 PG 9 WC Engineering, Aerospace SC Engineering GA 441LV UT WOS:000169232600009 ER PT J AU Pack, LG Seifert, A AF Pack, LG Seifert, A TI Periodic excitation for jet vectoring and enhanced spreading SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA 37th Aerospace Sciences Meeting and Exhibit CY JAN 11-14, 1999 CL RENO, NEVADA SP Amer Inst Aeronaut & Astronaut ID SUPERSONIC JETS; COUNTERFLOW; LAYER; DELAY AB The effects of periodic excitation on the evolution of a turbulent jet were studied experimentally. A short, wide-angle diffuser was attached to the jet exit, and excitation was introduced at the junction between the jet exit and the diffuser inlet. The introduction of high-amplitude periodic excitation at the jet exit enhances the mixing and promotes attachment of the jet shear layer to the diffuser wall, Vectoring is achieved by applying the excitation over a fraction of the circumference of the circular jet, enhancing its spreading rate on the excited side and its tendency to reattach to that side. Static-deflection studies demonstrate that the presence of the wide-angle diffuser increases the effectiveness of the added periodic momentum caused by a favorable interaction between the excitation, the jet shear layer, and the diffuser wall. This point was further demonstrated by the evolution of a wave packet that was excited in the jet shear layer. Strong amplification of the wave packet was measured with a diffuser attached to the jet exit. The turbulent jet responds quickly (10-20 ms) to step changes in the level of the excitation input. The response scales with the jet-exit velocity and is independent of the Reynolds number. Jet deflection angles were found to be highly sensitive to the relative direction between the excitation and the jet how and less sensitive to the excitation frequency. Significant jet deflection angles were obtained for a diffuser length of one-half to two diameters and for diffusers with half-angles greater than 15 deg. C1 NASA, Langley Res Ctr, Phys & Control Branch, Hampton, VA 23681 USA. RP Pack, LG (reprint author), NASA, Langley Res Ctr, Phys & Control Branch, Hampton, VA 23681 USA. NR 25 TC 31 Z9 32 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAY-JUN PY 2001 VL 38 IS 3 BP 486 EP 495 DI 10.2514/2.2788 PG 10 WC Engineering, Aerospace SC Engineering GA 441LV UT WOS:000169232600012 ER PT J AU Lachowicz, JT Yao, CS Joslin, RD AF Lachowicz, JT Yao, CS Joslin, RD TI Physical analysis and scaling of a jet and vortex actuator SO JOURNAL OF AIRCRAFT LA English DT Article ID STREAMWISE C1 NASA, Natl Res Council, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Div Fluid Mech, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Div Acoust, Hampton, VA 23681 USA. RP Lachowicz, JT (reprint author), NASA, Natl Res Council, Hampton, VA 23681 USA. NR 7 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAY-JUN PY 2001 VL 38 IS 3 BP 573 EP 575 DI 10.2514/2.2800 PG 3 WC Engineering, Aerospace SC Engineering GA 441LV UT WOS:000169232600023 ER PT J AU Rabkin, BA Szivek, JA Schonfeld, JE Halloran, BP AF Rabkin, BA Szivek, JA Schonfeld, JE Halloran, BP TI Long-term measurement of bone strain in vivo: The rat tibia SO JOURNAL OF BIOMEDICAL MATERIALS RESEARCH LA English DT Article DE bone; mechanical strain; in vivo ID GAUGES; EXERCISE; RADIUS; ULNA AB Despite the importance of strain in regulating bone metabolism, knowledge of strains induced in bone in vivo during normal activities is limited to short-term studies, Biodegeneration of the bond between gauge and bone is the principle cause of this limitation. To overcome the problem of bond degeneration, a unique calcium phosphate ceramic (CPC) coating has been developed that permits long-term attachment of microminiature strain gauges to hone. Using this technique, we report the first long-term measurements of bone strain in the rat tibia. Gauges, mounted on the tibia, achieved peak or near peak bonding at 7 weeks. Measurements were made between 7-10 weeks. Using ambulation on a treadmill, the pattern and magnitude of strain measured in the tibia remained relatively constant between 7-10 weeks post implantation. That strain levels were similar at 7 and 10 weeks suggests that gauge bonding is stable. These data demonstrate that CPC-coated strain gauges can be used to accurately measure bone strain for extended periods, and provide an in vivo assessment of tibial strain levels during normal ambulation in the rat. (C) 2001 John Wiley & Sons, Inc. C1 Vet Affairs Med Ctr, San Francisco, CA 94121 USA. Univ Calif San Francisco, Dept Med, San Francisco, CA USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Arizona, Dept Surg, Tucson, AZ USA. RP Halloran, BP (reprint author), Vet Affairs Med Ctr, 111N,4150 Clement St, San Francisco, CA 94121 USA. NR 27 TC 29 Z9 29 U1 0 U2 3 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 USA SN 0021-9304 J9 J BIOMED MATER RES JI J. Biomed. Mater. Res. PD MAY 1 PY 2001 VL 58 IS 3 BP 277 EP 281 DI 10.1002/1097-4636(2001)58:3<277::AID-JBM1017>3.0.CO;2-T PG 5 WC Engineering, Biomedical; Materials Science, Biomaterials SC Engineering; Materials Science GA 432HX UT WOS:000168687100008 PM 11319741 ER PT J AU Zhu, S Su, CH Lehoczky, SL Harris, MT Callahan, MJ McCarty, P George, MA AF Zhu, S Su, CH Lehoczky, SL Harris, MT Callahan, MJ McCarty, P George, MA TI Substrate preparations in epitaxial ZnO film growth SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 12th American Conference on Crystal Growth and Epitaxy CY AUG 13-18, 2000 CL VAIL, COLORADO SP NASA Micrograv Res Div, Natl Renewable Energy Lab, Adv Ceram Corp, Bicron, Crystal Assoc Inc, Crystal Syst Inc, Delron Crystal Ind Inc, Engelhard CLAL LP, Engis Corp, Sawyer Res Prod, Sensors Unltd Inc, S Bay Technol, ThermCraft, II VI Inc, Tyco Electr DE surface structure; vapor phase epitaxy; oxides; semiconducting II-VI materials ID ZINC-OXIDE FILMS; SURFACES; SAPPHIRE AB Epitaxial ZnO films were grown on two polar surfaces (O-surface and Zn-surface) of (0 0 0 1) ZnO single crystal substrates using off-axis magnetron sputtering deposition. As a comparison, films were also deposited on (0 0 0 1) Al2O3 substrates. It was found that the two polar ZnO surfaces have different photoluminescence (PL) spectrum, surface structure and morphology, which strongly influence the epitaxial film growth. The morphology and structure of homoepitaxial films grown on the ZnO substrates were different from heteroepitaxial films grown on the Al2O3 An interesting result shows that high temperature annealing of ZnO single crystals will improve the surface structure on the O-surface rather than the Zn-surface. The measurements of PL, low-angle incident X-ray diffraction, and atomic force microscopy of ZnO films indicate that the O-terminated surface is better for ZnO epitaxial film growth. (C) 2001 Published by Elsevier Science B.V. C1 NASA, George C Marshall Space Flight Ctr, USRA, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Sci Directorate, Huntsville, AL 35812 USA. AFRL SNHX, Sensors Directorate, Hanscom AFB, MA 01731 USA. Solid State Sci Corp, Hanscom AFB, MA 01731 USA. Univ Alabama, Dept Chem, Huntsville, AL 35899 USA. RP Zhu, S (reprint author), NASA, George C Marshall Space Flight Ctr, USRA, Huntsville, AL 35812 USA. NR 16 TC 5 Z9 5 U1 1 U2 3 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 MAY PY 2001 VL 225 IS 2-4 BP 190 EP 196 DI 10.1016/S0022-0248(01)00873-9 PG 7 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 444HP UT WOS:000169394300018 ER PT J AU Burger, A Chattopadhyay, K Ndap, JO Ma, X Morgan, SH Rablau, CI Su, CH Feth, S Page, RH Schaffers, KI Payne, SA AF Burger, A Chattopadhyay, K Ndap, JO Ma, X Morgan, SH Rablau, CI Su, CH Feth, S Page, RH Schaffers, KI Payne, SA TI Preparation conditions of chromium doped ZnSe and their infrared luminescence properties SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 12th American Conference on Crystal Growth and Epitaxy CY AUG 13-18, 2000 CL VAIL, COLORADO SP NASA Micrograv Res Div, Natl Renewable Energy Lab, Adv Ceram Corp, Bicron, Crystal Assoc Inc, Crystal Syst Inc, Delron Crystal Ind Inc, Engelhard CLAL LP, Engis Corp, Sawyer Res Prod, Sensors Unltd Inc, S Bay Technol, ThermCraft, II VI Inc, Tyco Electr DE diffusion; doping; growth from vapor; zinc compounds; semiconducting II-VI materials; solid state lasers ID TRACE GAS-DETECTION; ZINC CHALCOGENIDES; SPECTROSCOPY; LASER; CRYSTALS AB We report the investigation by photoluminescence lifetime measurements of the near-IR emissions from a series of chromium-doped ZnSe samples, correlated to their preparation conditions. The samples were polycrystalline or single crystals prepared by post growth diffusion doping or single crystals doped during growth by the physical vapor transport method. Room temperature lifetime values between 6 and 8 mus were measured for samples with Cr2+ concentrations from low 10(17) to high 10(18)cm(-3) range. Lifetime data taken down to 78 K was found to be rather temperature independent, reconfirming previous reports indicating a quantum yield of the corresponding emission of close to 100% at room temperature. A strong decrease in the room temperature lifetime was found for chromium concentrations higher than 10(19) cm(-3). (C) 2001 Elsevier Science B.V. Ah rights reserved. C1 Fisk Univ, Ctr Photon Mat & Devices, Dept Phys, Nashville, TN 37208 USA. W Virginia Univ, Dept Phys, Morgantown, WV 26506 USA. NASA, George C Marshall Space Flight Ctr, Micrograv Sci & Applicat Dept, Sci Directorate SD 47, Huntsville, AL 35812 USA. Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. RP Burger, A (reprint author), Fisk Univ, Ctr Photon Mat & Devices, Dept Phys, Nashville, TN 37208 USA. RI Feth, Shari/F-6302-2013 OI Feth, Shari/0000-0003-3545-5649 NR 18 TC 37 Z9 41 U1 1 U2 5 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 MAY PY 2001 VL 225 IS 2-4 BP 249 EP 256 DI 10.1016/S0022-0248(01)00845-4 PG 8 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 444HP UT WOS:000169394300028 ER PT J AU Owens, C Bhat, K Wang, WS Tan, A Aggarwal, MD Penn, BG Frazier, DO AF Owens, C Bhat, K Wang, WS Tan, A Aggarwal, MD Penn, BG Frazier, DO TI Bulk growth of high quality nonlinear optical crystals of L-arginine tetrafluoroborate (L-AFB) SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 12th American Conference on Crystal Growth and Epitaxy CY AUG 13-18, 2000 CL VAIL, COLORADO SP NASA Micrograv Res Div, Natl Renewable Energy Lab, Adv Ceram Corp, Bicron, Crystal Assoc Inc, Crystal Syst Inc, Delron Crystal Ind Inc, Engelhard CLAL LP, Engis Corp, Sawyer Res Prod, Sensors Unltd Inc, S Bay Technol, ThermCraft, II VI Inc, Tyco Electr DE solubility; growth from solutions; single crystal growth; inorganic compounds; organic compounds; non-linear optical devices AB Bulk single crystals of L-arginine tetrafluoroborate (L-AFB) a new semiorganic nonlinear optical material has been successfully grown from solution by the temperature lowering method. Solubility of L-AFB was measured in various solvents such as ethanol, methanol, acetone and water. L-AFB was found to have extremely low solubility in acetone, ethanol and methanol. Therefore, it was not feasible to grow L-AFB single crystals using these solvents. However, high quality crystals of L-AFB were successfully grown from aqueous solution by the temperature lowering method, even though the mother liqueur became viscous. Large single crystals of L-AFB were grown with dimensions 78 x 50 x 35 mm(3) in eight weeks. Growth rate and effects of seed orientation on morphologies of L-AFB crystals were studied. L-AFB crystals belong to a class of organic-inorganic complexes in which the high optical nonlinearity of a pure organic compound is combined with the favorable mechanical and thermally stable properties of an inorganic compound. Bulk single crystals of L-AFB are potential materials for applications in blue-green wavelength region. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Alabama A&M Univ, Dept Phys, Normal, AL 35762 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Aggarwal, MD (reprint author), Alabama A&M Univ, Dept Phys, Normal, AL 35762 USA. NR 7 TC 24 Z9 24 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 MAY PY 2001 VL 225 IS 2-4 BP 465 EP 469 DI 10.1016/S0022-0248(01)00917-4 PG 5 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 444HP UT WOS:000169394300065 ER PT J AU Singh, NB Coriell, SR Duval, WMB Mani, SS Green, K Glicksman, ME AF Singh, NB Coriell, SR Duval, WMB Mani, SS Green, K Glicksman, ME TI Thermal conductivity measurement in lead bromide SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 12th American Conference on Crystal Growth and Epitaxy CY AUG 13-18, 2000 CL VAIL, COLORADO SP NASA Micrograv Res Div, Natl Renewable Energy Lab, Adv Ceram Corp, Bicron, Crystal Assoc Inc, Crystal Syst Inc, Delron Crystal Ind Inc, Engelhard CLAL LP, Engis Corp, Sawyer Res Prod, Sensors Unltd Inc, S Bay Technol, ThermCraft, II VI Inc, Tyco Electr DE heat transfer; solidification; halides; acousto-optic materials ID INSTABILITIES AB The ratio of liquid and solid thermal conductivities was determined for lead bromide by measuring the temperature of solid and liquid under the steady-state conditions. The liquid thermal conductivity was determined to be 10.5 x 10(-4)Cal/K s cm, a value 1.65 times higher than that reported for the solid. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Northrop Grumman Corp, Ctr Sci & Technol, ESSS, Linthicum, MD 21090 USA. NIST, Gaithersburg, MD 20889 USA. NASA, John Glenn Res Ctr, Cleveland, OH 44135 USA. Rensselaer Polytech Inst, Dept Mat Sci & Engn, Troy, NY 12180 USA. RP Singh, NB (reprint author), Northrop Grumman Corp, Ctr Sci & Technol, ESSS, ATL-3D14,1212 Winterson Rd, Linthicum, MD 21090 USA. OI Glicksman, Martin/0000-0002-2675-2759 NR 4 TC 4 Z9 4 U1 0 U2 2 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 MAY PY 2001 VL 225 IS 2-4 BP 512 EP 515 DI 10.1016/S0022-0248(01)00958-7 PG 4 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 444HP UT WOS:000169394300074 ER PT J AU Kassemi, M Barsi, S Kaforey, M Matthiesen, D AF Kassemi, M Barsi, S Kaforey, M Matthiesen, D TI Effect of void location on segregation patterns in microgravity solidification SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 12th American Conference on Crystal Growth and Epitaxy CY AUG 13-18, 2000 CL VAIL, COLORADO SP NASA Micrograv Res Div, Natl Renewable Energy Lab, Adv Ceram Corp, Bicron, Crystal Assoc Inc, Crystal Syst Inc, Delron Crystal Ind Inc, Engelhard CLAL LP, Engis Corp, Sawyer Res Prod, Sensors Unltd Inc, S Bay Technol, ThermCraft, II VI Inc, Tyco Electr DE computer simulations; convection; directional solidification; fluid flows; segregation; growth from melt; microgravity conditions AB Three recent microgravity experiments have been hampered by convection caused by unwanted voids and/or bubbles in the melt. In this work, we present a numerical study to describe how thermocapillary convection generated by a void or bubble can affect a typical microgravity solidification process. A detailed numerical model for the Bridgman solidification of a doped single crystal from its dilute binary melt is developed which solves the. quasi-steady Navier Stokes equations together with the conservation equations for transport of energy and species. The complicating effects of thermocapillary convection generated by the void and solutal rejection at the melt-solid interface are included, Numerical simulations indicate that void-generated thermocapillary convection can affect segregation patterns drastically, especially, if the thermocapillary vortex penetrates the solutal boundary layer at the growth interface. Two lateral void positions are considered with the void placed either in the center of the ampoule or on the side wall. From a transport point of view, three different segregation regimes are identified for each lateral void location based on the distance between the void and the growth interface. These range from a diffusion-controlled regime where most of the radial nonuniformity in the interfacial composition is due to the interface curvature with minimal convective effects to a fully mixed regime where the penetration of the solutal boundary layer by the thermocapillary vortex tends to homogenize the interfacial compositions drastically. Naturally, the extent of each of three regions will not only depend on the size and lateral position of the void but also on the material and growth properties of the system under consideration. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Glenn Res Ctr, NCMR, Cleveland, OH 44135 USA. Case Western Reserve Univ, Cleveland, OH 44106 USA. RP Kassemi, M (reprint author), NASA, Glenn Res Ctr, NCMR, 21000 Brook Pk Rd,MS 110-1, Cleveland, OH 44135 USA. NR 9 TC 8 Z9 8 U1 0 U2 4 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 MAY PY 2001 VL 225 IS 2-4 BP 516 EP 521 DI 10.1016/S0022-0248(01)00945-9 PG 6 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 444HP UT WOS:000169394300075 ER PT J AU Zhu, S Su, CH Carpenter, P Lehoczky, S AF Zhu, S Su, CH Carpenter, P Lehoczky, S TI Gravity-related transport process in off-axis sputtering deposition SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 12th American Conference on Crystal Growth and Epitaxy CY AUG 13-18, 2000 CL VAIL, COLORADO SP NASA Micrograv Res Div, Natl Renewable Energy Lab, Adv Ceram Corp, Bicron, Crystal Assoc Inc, Crystal Syst Inc, Delron Crystal Ind Inc, Engelhard CLAL LP, Engis Corp, Sawyer Res Prod, Sensors Unltd Inc, S Bay Technol, ThermCraft, II VI Inc, Tyco Electr DE mass transfer; physical vapor deposition processes; oxides; semiconducting II-VI materials ID THIN-FILMS; GROWTH AB In the reactive off-axis sputtering deposition of ZnO films, three transport regimes from a ballistic motion to a diffusive drift of the ejected species were observed when the growth pressures were varied from 5 to 150 mTorr, The distribution of the film thickness at different substrate locations was measured, When the substrate surface was parallel to the gravity vector, a film thickness variation along the direction of gravity was detected in the region of diffusive transport deposition. This phenomenon depends strongly on the growth pressures while only slightly on the growth temperatures. Based on experimental results, a gravity-related motion of the sputtered species is proposed in film growth under relative low growth pressures. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, George C Marshall Space Flight Ctr, USRA, SD47, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Micrograv Sci & Applicat Dept, Huntsville, AL 35812 USA. RP Zhu, S (reprint author), NASA, George C Marshall Space Flight Ctr, USRA, SD47, Huntsville, AL 35812 USA. NR 13 TC 2 Z9 2 U1 0 U2 0 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 MAY PY 2001 VL 225 IS 2-4 BP 522 EP 527 DI 10.1016/S0022-0248(01)00946-0 PG 6 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 444HP UT WOS:000169394300076 ER PT J AU Lisano, ME Schutz, BE AF Lisano, ME Schutz, BE TI Arcsecond-level pointing calibration for ICESat laser altimetry of ice sheets SO JOURNAL OF GEODESY LA English DT Article DE ICESat; GLAS; calibration; pointing determination; ice-sheet altimetry AB Arcsecond-level accuracy of NASA's ICESat (Ice, Cloud, and land Elevation Satellite) satellite laser altimeter beam pointing angle is required to satisfy the scientific goal of detecting centimeter-level elevation changes, over time, in the Greenland and Antarctic ice sheets. Two different approaches, termed "topographic inferred" and "direct detection", were examined for calibrating the laser pointing angle (that is, detecting and removing pointing determination bias) at the 1.5-arcsec level, using information independent of the onboard pointing instrumentation. Both approaches entail estimating the beam pointing by differencing the three-dimensional position of the altimeter instrument and the laser-beam spot (or "footprint") location on the ground. Analytical assessments of the two approaches are discussed. along with recommendations for the ICESat pointing determination calibration strategy. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Texas, Ctr Space Res, Austin, TX 78712 USA. RP Lisano, ME (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 10 TC 5 Z9 6 U1 3 U2 6 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0949-7714 J9 J GEODESY JI J. Geodesy PD MAY PY 2001 VL 75 IS 2-3 BP 99 EP 108 DI 10.1007/s001900000156 PG 10 WC Geochemistry & Geophysics; Remote Sensing SC Geochemistry & Geophysics; Remote Sensing GA 438FD UT WOS:000169042200004 ER PT J AU Ruzmaikin, A Feynman, J Neugebauer, M Smith, EJ AF Ruzmaikin, A Feynman, J Neugebauer, M Smith, EJ TI Preferred solar longitudes with signatures in the solar wind SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC-FIELD; ROTATION; DYNAMO; MODEL; SUN AB Using spacecraft data collected over three solar cycles, Neugebauer et al. [2000] found a persistent dependence of the solar wind speed and the radial component of the interplanetary magnetic field on solar longitude, defined in a coordinate system with a rotation period of 27.03 days. Here we investigate the solar source of this period using observations of the photospheric magnetic field. We study the lowest-order nonaxisymmetric modes of the solar field extracted from synoptic charts of the Wilcox Solar Observatory. We find there is a robust magnetic structure on the Sun, which rotates with the period found by Neugebauer et al. [2000] in the solar wind. This rotation is more rapid than the solar equatorial and core rotations. We discuss the association of this nonaxisymmetric mode with the magnetic field generated by the solar mean field dynamo. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ruzmaikin, A (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 25 TC 22 Z9 22 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD MAY 1 PY 2001 VL 106 IS A5 BP 8363 EP 8370 DI 10.1029/2000JA000392 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 428VL UT WOS:000168482300024 ER PT J AU Fok, MC Wolf, RA Spiro, RW Moore, TE AF Fok, MC Wolf, RA Spiro, RW Moore, TE TI Comprehensive computational model of Earth's ring current SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETOSPHERIC ELECTRIC-FIELDS; PLASMA SHEET; CURRENT IONS; LARGE-SCALE; CONVECTION; STORM; REPRESENTATIONS; CONFIGURATION; CONDUCTIVITY; IONOSPHERE AB A comprehensive ring current model (CRCM) has been developed that couples the Rice Convection Model (RCM) and the kinetic model of Fok and coworkers. The coupled model is able to simulate, for the first time using a self-consistently calculated electric field, the evolution of an inner magnetosphere plasma distribution that conserves the first two adiabatic invariants. The traditional RCM calculates the ionospheric electric fields and currents consistent with a magnetospheric ion distribution that is assumed to be isotropic in pitch angle. The Fok model calculates the plasma distribution by solving the Boltzmann equation with specified electric and magnetic fields. To combine the RCM and the Fok model, the RCM. Birkeland current algorithm has been generalized to arbitrary pitch angle distributions. Given a specification of height-integrated ionospheric conductance, the RCM component of the CRCM computes the ionospheric electric field and currents. The Fok model then advances the ring current plasma distribution using the electric field computed by the RCM and at the same time calculates losses along particle drift paths. We present the logic of CRCM and the first validation results following the Hf distribution during the previously studied magnetic storm of May 2, 1986. The H+ fluxes calculated by the coupled model agree very well with observations by AMPTE/CCE. In particular, the coupled model is able to reproduce the high Hf flux seen on the dayside at L similar to 2.3 that the previous simulation, which employed a Stern-Volland convection model with shielding factor 2, failed to produce. Though the Stern-Volland and CRCM electric fields differ in several respects, the most notable difference is that the CRCM predicts strong electric fields near Earth in the storm main phase, particularly in the dusk-midnight quadrant. Thus the CRCM injects particles more deeply and more quickly. C1 NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. Rice Univ, Dept Phys & Astron, Houston, TX 77005 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Fok, MC (reprint author), NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Code 692, Greenbelt, MD 20771 USA. RI Moore, Thomas/D-4675-2012; Fok, Mei-Ching/D-1626-2012 OI Moore, Thomas/0000-0002-3150-1137; NR 38 TC 158 Z9 158 U1 2 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD MAY 1 PY 2001 VL 106 IS A5 BP 8417 EP 8424 DI 10.1029/2000JA000235 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 428VL UT WOS:000168482300029 ER PT J AU Keller, KA Lysak, RL AF Keller, KA Lysak, RL TI MHD simulation of magnetospheric waveguide modes SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID KELVIN-HELMHOLTZ INSTABILITY; FIELD LINE RESONANCES; NUMERICAL MAGNETOHYDRODYNAMICS; WAVE-GUIDES; MICROPULSATIONS; ASTROPHYSICS; PULSATIONS; EXCITATION; ALGORITHM; TESTS AB Ultralow frequency waves with frequencies of 1.3, 1.9, 2.6, and 3.4 mHz are often observed and associated with field line resonances (FLRs) in the inner magnetosphere of the Earth. Waveguide modes have been proposed as a mechanism for generating FLRs. Using a compressible two-dimensional MHD simulation, we will exp lore the nonlinear effects on the excitation of waveguide modes and the frequencies of the modes. We will discuss bow changes in key parameters affect waveguide modes. C1 Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA. RP Keller, KA (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Code 696, Greenbelt, MD 20771 USA. 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 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD MAY 1 PY 2001 VL 106 IS A5 BP 8447 EP 8454 DI 10.1029/2000JA000139 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 428VL UT WOS:000168482300032 ER PT J AU Azor, R Bar-Itzhack, IY Deutschmann, JK Harman, RR AF Azor, R Bar-Itzhack, IY Deutschmann, JK Harman, RR TI Angular-rate estimation using delayed quaternion measurements SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Algorithms are presented for estimating the angular-rate vector of satellites using quaternion measurements, Two approaches are compared, one that uses differentiated quaternion measurements to yield coarse rate measurements, which are then fed into two different estimators. In the other approach, the ram quaternion measurements themselves are fed directly into the two estimators. The two estimators rely on the ability to decompose the nonlinear, part of the rotational dynamics equation of a body into a product of an angular-rate dependent matrix and the angular-rate vector itself. This nonunique decomposition enables the treatment of the nonlinear spacecraft dynamics model as a linear one and, thus, the application of a pseudolinear Kalman filter. II also enables the application of a special Kalman filter, which is based on the use of the solution of the state-dependent algebraic Riccati equation to compute the gain matrix and, thus, eliminates the need to compute recursively the filter. covariance matrix, The replacement of the rotational dynamics by a simple Markov model is also examined. Special consideration is given to the problem of delayed quaternion measurements. Two solutions to this problem are suggested and tested, Real Rossi X-Ray. Timing Explorer data are used to test these algorithms, and results ale presented. C1 Israel Aircraft Ind Inc, Syst & Space Technol Elect Div, Dept Syst Engn, MBT, IL-56000 Yehud, Israel. NASA, Goddard Space Flight Ctr, Flight Dynam Anal Branch, Greenbelt, MD 20771 USA. Technion Israel Inst Technol, Fac Aerosp Engn, IL-32000 Haifa, Israel. RP Azor, R (reprint author), Israel Aircraft Ind Inc, Syst & Space Technol Elect Div, Dept Syst Engn, MBT, IL-56000 Yehud, Israel. NR 14 TC 16 Z9 20 U1 1 U2 3 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 MAY-JUN PY 2001 VL 24 IS 3 BP 436 EP 443 DI 10.2514/2.4759 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 430VC UT WOS:000168595300003 ER PT J AU Bilimoria, KD AF Bilimoria, KD TI Methodology for the performance evaluation of a conflict probe SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article; Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 10-12, 1998 CL BOSTON, MASSACHUSETTS SP Amer Inst Aeronaut & Astronaut AB A conflict probe is an air traffic controller decision support tool that can predict conflicts well in advance by the use of information on aircraft position, speed, and Eight plans? along with forecasts of wind and temperature profiles. A comprehensive methodology is presented to evaluate quantitatively; the performance of a conflict probe by the use of real traffic data and expanded separation criteria. The methodology is universal in nature and can be applied to any conflict probe, Several metrics of conflict probe performance have been developed and evaluated, The missed alert rate and false alert rate are primary metrics that quantify the reliability of a conflict probe; these metrics are partitioned by quality of Eight intent information. The mean conflict warning time and errors in key conflict prediction parameters, for example, conflict start time, minimum horizontal and vertical separations, are important secondary metrics that quantify the accuracy of a conflict probe, The evaluation methodology: developed was exercised by applying it to the Center-TRACON Automation System's Conflict Probe Tool, using real traffic data from the Denver Air Route Traffic Control Center: some preliminary results are presented as an example. C1 NASA, Ames Res Ctr, Automat Concepts Res Branch, Moffett Field, CA 94035 USA. RP Bilimoria, KD (reprint author), NASA, Ames Res Ctr, Automat Concepts Res Branch, Mail Stop 210-10, Moffett Field, CA 94035 USA. NR 11 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 2001 VL 24 IS 3 BP 444 EP 451 DI 10.2514/2.4764 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 430VC UT WOS:000168595300004 ER PT J AU Burken, JJ Lu, P Wu, ZL Bahm, C AF Burken, JJ Lu, P Wu, ZL Bahm, C TI Two reconfigurable flight-control design methods: Robust servomechanism and control allocation SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID SYSTEMS AB Two methods are discussed for design of reconfigurable night-control systems when one or more control surfaces are jammed. The first is a robust servomechanism control approach, which is a generalization of the classical proportional-plus-integral control to multi-input/multi-output systems. The second proposed method is a control-allocation approach based on a quadratic programming formulation. The formulation is formally analyzed, and a globally convergent fixed-point iteration algorithm is used to make onboard implementation of this method feasible. The two methods are applied to reconfigurable entry night control design for the X-33 vehicle, Nonlinear sis-degree-of-freedom simulations demonstrate simultaneous tracking of angle-of-attack and roll-angle commands during control surface failures. The control-allocation method appears to offer more uniform and good performance at the expense of modestly higher computation requirement. C1 NASA, Dryden Flight Res Ctr, Edwards, CA 93523 USA. Iowa State Univ Sci & Technol, Dept Aerosp Engn & Engn Mech, Ames, IA 50011 USA. RP Burken, JJ (reprint author), NASA, Dryden Flight Res Ctr, Edwards, CA 93523 USA. NR 9 TC 61 Z9 75 U1 0 U2 6 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 MAY-JUN PY 2001 VL 24 IS 3 BP 482 EP 493 DI 10.2514/2.4769 PG 12 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 430VC UT WOS:000168595300009 ER PT J AU Schmidt, DK Raney, DL AF Schmidt, DK Raney, DL TI Modeling and simulation of flexible flight vehicles SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article; Proceedings Paper CT AIAA Modeling and Simulation Technologies Conference CY AUG 10-12, 1998 CL BOSTON, MASSACHUSETTS SP Amer Inst Aeronaut & Astronaut AB The effects of flexibility on the flight dynamics of large aircraft have been shown to be quite significant, especial ly as the frequencies of the elastic modes become lower and approach those of the rigid-body modes. The handling characteristics of such vehicles are altered significantly from those of a rigid vehicle, and the design of the flight-control system may become drastically more complex. Consequently the need to model accurately the dynamics of such vehicles, and to develop valid simulations, is becoming particularly acute, The theoretical development of a generic flexible-aircraft model is reviewed. This modeling technique allows far the flexible degrees of freedom to be added to an existing simulation model of the vehicle's rigid-body dynamics. The data necessary for modeling a specific vehicle include aerodynamic stability derivatives, aerodynamic influence coefficients, elastic mode shapes, modal frequencies and damping, and generalized masses, Two case studies are presented, both involving the development of motion-based simulations in NASA Langley Research Center's simulation facility, The first example investigates an aircraft similar in geometry to the B-1, whereas the second investigates a large highspeed commercial transport, The dynamic responses (time and frequency domain) for these vehicles are presented, along with the evaluations of the effects of dynamic aeroelasticity on their handling characteristics. The vehicle responses are critical to evaluating hardware and software requirements for simulation fidelity, far example, visual and motion cues. Finally. a brief assessment of the effects of limitations of the simulation facility is presented, Limitations considered include digital time delay, motion hardware bandwidth, and motion washout logic. C1 Univ Colorado, Flight Dynam & Control Lab, Colorado Springs, CO 80918 USA. NASA, Langley Res Ctr, Dynam & Control Branch, Hampton, VA 23681 USA. RP Schmidt, DK (reprint author), Univ Colorado, Flight Dynam & Control Lab, Colorado Springs, CO 80918 USA. NR 9 TC 14 Z9 19 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 MAY-JUN PY 2001 VL 24 IS 3 BP 539 EP 546 DI 10.2514/2.4744 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 430VC UT WOS:000168595300016 ER PT J AU Scheeres, DJ Han, D Hou, Y AF Scheeres, DJ Han, D Hou, Y TI Influence of unstable manifolds on orbit uncertainty SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article; Proceedings Paper CT AIAA/AAS Astrodynamics Specialists Conference CY AUG 10-12, 1998 CL BOSTON, MASSACHUSETTS SP Amer Inst Aeronaut & Astronaut, AAS ID MECHANICS AB The dynamics of orbit uncertainty in an unstable orbital environ ment are discussed with specific application to the orbit determination of a halo orbit about an Earth-sun libration point. The goal of the paper is to investigate orbit determination and orbit uncertainty dynamics in this environment and to present basic results. The dynamics model is based on the Hill equations of motion, and the orbit determination measurement model is based on the classical Hamilton-Melbourne analysis for the information content of a Doppler pass of data. The effect of correlated stochastic accelerations on the orbit uncertainty distributions is also included in the model. Results are presented, and the major departures from the classic two-body orbital environment are highlighted, We show that the unstable manifolds of the halo orbit control the long-term evolution of the uncertainty, During active periods of tracking, however, this relationship can be reversed, and the largest direction of uncertainty will not, in general,lie along the local unstable manifold of the orbit, The influence of the unstable manifold on the direction of maximum orbit uncertainty is seen to vary with the orbit geometry, level of stochastic accelerations, and tracking frequency. C1 Univ Michigan, Dept Aerosp Engn, Ann Arbor, MI 48109 USA. CALTECH, Jet Prop Lab, Navigat & Flight Mech Sect, Pasadena, CA 91109 USA. Iowa State Univ, Dept Aerosp Engn & Engn Mech, Ames, IA 50011 USA. RP Scheeres, DJ (reprint author), Univ Michigan, Dept Aerosp Engn, Ann Arbor, MI 48109 USA. NR 19 TC 25 Z9 25 U1 0 U2 2 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 MAY-JUN PY 2001 VL 24 IS 3 BP 573 EP 585 DI 10.2514/2.4749 PG 13 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 430VC UT WOS:000168595300020 ER PT J AU Deutschmann, JK Bar-Itzhack, IY AF Deutschmann, JK Bar-Itzhack, IY TI Evaluation of attitude and orbit estimation using actual earth magnetic field data SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID MAGNETOMETER AB A single, augmented extended Kalman filter (EKF), which simultaneously and autonomously estimates spacecraft attitude and orbit, has been developed and successfully tested with real magnetometer and gyro data only. Because the Earth magnetic field is a function of time and position, and because time is known quite precisely, the differences between the computed and measured magnetic field components, as measured by the magnetometers throughout the entire spacecraft orbit, are a function of both orbit and attitude errors. Thus, conceivably these differences could be used to estimate both orbit and attitude: an observability study validated this assumption. The results of testing the EKF with actual magnetometer and gyro data, from four satellites supported by the NASA Goddard Space Flight Center Guidance, Navigation, and Control Center, are presented and evaluated. They confirm the assumption that a single EKF can estimate both attitude and orbit when using gyros and magnetometers only. C1 NASA, Goddard Space Flight Ctr, Guidance Navigat & Control Ctr, Greenbelt, MD 20771 USA. Technion Israel Inst Technol, Fac Aerosp Engn, IL-32000 Haifa, Israel. RP Deutschmann, JK (reprint author), NASA, Goddard Space Flight Ctr, Guidance Navigat & Control Ctr, Code 572, Greenbelt, MD 20771 USA. NR 19 TC 24 Z9 47 U1 1 U2 3 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 MAY-JUN PY 2001 VL 24 IS 3 BP 616 EP 623 DI 10.2514/2.4753 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 430VC UT WOS:000168595300024 ER PT J AU Whittenberger, JD Aikin, B Salem, J AF Whittenberger, JD Aikin, B Salem, J TI Creep and toughness of cryomilled NiAl containing Cr SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID HIGH-TEMPERATURE CREEP; DYNAMIC YOUNGS MODULUS; MECHANICAL-PROPERTIES; SINGLE-CRYSTALS; COMPOSITES; INTERMETALLICS; DEPENDENCE; STRENGTH; BEHAVIOR; SIZE AB NiAl-AlN + Cr composites were produced by blending cryomilled NiAl powder with approximately 10 vol% Cr flakes. In comparison to the as-consolidated matrices, hot isostatically pressed Cr-modified materials did not demonstrate any significant improvement in toughness. Hot extruded NiAl-AlN + 10.5Cr, however, possessed a toughness twice that determined for the base NiAl-AlN alloy. Measurement of the 1200 to 1400 K plastic flow properties revealed that the strength of the composites was completely controlled by the properties of the NiAl-AlN matrices. This behavior could be successfully modeled by the Rule-of-Mixtures, where load is shed from the weak Cr to the strong matrix. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Case Western Reserve Univ, Cleveland, OH 44135 USA. RP Whittenberger, JD (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 30 TC 2 Z9 2 U1 0 U2 0 PU MATERIALS RESEARCH SOCIETY PI WARRENDALE PA 506 KEYSTONE DR, WARRENDALE, PA 15086 USA SN 0884-2914 J9 J MATER RES JI J. Mater. Res. PD MAY PY 2001 VL 16 IS 5 BP 1333 EP 1344 DI 10.1557/JMR.2001.0186 PG 12 WC Materials Science, Multidisciplinary SC Materials Science GA 429AW UT WOS:000168494700019 ER PT J AU Drouin, BJ Miller, CE Cohen, EA Wagner, G Birk, M AF Drouin, BJ Miller, CE Cohen, EA Wagner, G Birk, M TI Further investigations of the ClO rotational spectrum SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID PHOTODISSOCIATION DYNAMICS; DIATOMIC-MOLECULES; OCLO; CL+O-3->CLO+O-2; SUBMILLIMETER; RADICALS; STATES; CIO; GHZ AB Pure rotational transitions of the chlorine monoxide radical have been observed up to v = 2 in the X-1 (2)Pi (3/2) and X(2)(2)Pi (1/2) states and transitions of the (ClO)-Cl-35-O-18 isotopomer have been observed in natural abundance. Additionally, rotational transitions for levels up to J' = 115/2 have been measured in the far infrared. These data have been merged with the existing microwave, submillimeter, and high-resolution infrared transition frequencies and fit simultaneously with a set of isotopically independent parameters. Isotopic substitution of both the Cl and O atoms has enabled the first determination of the electron spin-rotation constant gamma = -296.0(43) MHz as well as the Born-Oppenheimer corrections to the rotational constants. (C) 2001 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Haverford Coll, Dept Chem, Haverford, PA 19041 USA. Fernerkundung Deutsch Zentrum Luft & Raumfahrt eV, Inst Method, D-82234 Wessling, Germany. RP Drouin, BJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 36 TC 27 Z9 27 U1 0 U2 3 PU ACADEMIC PRESS INC 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 MAY PY 2001 VL 207 IS 1 BP 4 EP 9 DI 10.1006/jmsp.2001.8332 PG 6 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 435ZY UT WOS:000168913100002 ER PT J AU Perrin, A Flaud, JM Keller, F Smith, MAH Rinsland, CP Devi, VM Benner, DC Stephen, TM Goldman, A AF Perrin, A Flaud, JM Keller, F Smith, MAH Rinsland, CP Devi, VM Benner, DC Stephen, TM Goldman, A TI The nu(1)+nu(3) bands of the (OOO)-O-16-O-17-O-16 and (OOO)-O-16-O-16-O-17 Isotopomers of ozone SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article DE IR spectroscopy; O-3; ozone; isotopes; (OOO)-O-16-O-16-O-17; (OOO)-O-16-O-17-O-16 ID LINE POSITIONS; 5-MU-M REGION; NU(3) BANDS; NU-3 BANDS; INTENSITIES; SPECTRA; PARAMETERS; (OOO)-O-18-O-16-O-18; IDENTIFICATION; ISOTOPES AB Using 0.002 cm(-1) resolution Fourier transform absorption spectra of an O-17 enriched ozone sample, an extensive analysis of the v(1) + v(3) bands of the (OOO)-O-16-O-17-O-16 and (OOO)-O-16-O-16-O-17 isotopomers of ozone has been performed for the first time. The experimental rotational levels of the (101) vibrational states were satisfactorily reproduced using a Hamiltonian matrix that rakes into account the observed rovibrational resonances. More precisely, for (OOO)-O-16-O-17-O-16, as for the other C-2v-type ozone isotopomers, it was necessary to account for the Coriolis type resonances linking the (101) rotational levels with the levels of the (200) and (002) vibrational states and the Darling-Dennison interaction coupling the levels of (200) with those of (002). For the C-s-type isotopomer, namely (OOO)-O-16-O-16-O-17, as for (OOO)-O-16-O-16-O-18 and (OOO)-O-16-O-18-O-18, it proved necessary to also account for an additional DeltaK(a) = +/-2 resonance involving the rotational levels from (101) and (002) (J.-M. Flaud and R. Bacis, Spectrochimica Acta Part A 54, 3-16 (1998)). Using a Hamiltonian matrix which takes these resonances explicitly into account, precise vibrational energies and rotational and coupling constants were deduced, leading to the following band centers: v(0)(v(1) + v(3)) = 2078.3496 cm(-1) for (OOO)-O-16-O-17-O-16 and v(0)(v(1) + v(3)) = 2098.8631 cm(-1) for (OOO)-O-16-O-16-O-17. (C) 2001 Academic Press. C1 Univ Paris 11, CNRS, Photophys Mol Lab, F-91405 Orsay, France. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Coll William & Mary, Dept Phys, Williamsburg, VA 23187 USA. Univ Denver, Dept Phys & Astron, Denver, CO 80208 USA. RP Perrin, A (reprint author), Univ Paris 11, CNRS, Photophys Mol Lab, Bat 350,Campus Orsay, F-91405 Orsay, France. NR 32 TC 7 Z9 9 U1 0 U2 1 PU ACADEMIC PRESS INC 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 MAY PY 2001 VL 207 IS 1 BP 54 EP 59 DI 10.1006/jmsp.2001.8320 PG 6 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 435ZY UT WOS:000168913100008 ER PT J AU Appelbaum, J Steiner, A Landis, GA Baraona, CR Segalov, T AF Appelbaum, J Steiner, A Landis, GA Baraona, CR Segalov, T TI Spectral content of solar radiation on Martian surface based on Mars pathfinder SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID IMAGER; SKY AB Photovoltaic arrays were used successfully to power the various instruments for the Mars Pathfinder, To identify the type of the solar cell most suitable for Mars surface missions in the future, the spectral content of Mars's solar radiation must first be determined, The response of photovoltaic cells depends on the solar cell type and the wavelengths of the incident light. The suspended dust particles of Mars's atmosphere affect the intensity and spectral content of the solar radiation reaching the planet's surface. The Pathfinder employed four bandpass filters for measuring the atmospheric optical depth during the course of the mission that lasted for about 80 sols (Martian days). The central wavelengths of these filters were 450, 670, 883, and 989 nm, This paper deals with the analysis of the optical depth of the Martian atmosphere based on the Mars Pathfinder measurements and includes 1) variation of the monochromatic optical depth with the time of the day, 2) variation of the monochromatic optical depth with sol for the duration of the mission, 3) variation of the optical depth with wavelength, 4) transmittance of the direct beam with wavelength, and 5) solar cell response on the Martian surface of the direct beam irradiance. C1 Tel Aviv Univ, Fac Engn, IL-69978 Tel Aviv, Israel. NASA, Glenn Res Ctr, Power Technol Div, Cleveland, OH 44135 USA. Tel Aviv Univ, Power Technol Div, IL-69978 Tel Aviv, Israel. RP Appelbaum, J (reprint author), Tel Aviv Univ, Fac Engn, IL-69978 Tel Aviv, Israel. NR 8 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 2001 VL 17 IS 3 BP 508 EP 516 DI 10.2514/2.5805 PG 9 WC Engineering, Aerospace SC Engineering GA 434FN UT WOS:000168804600004 ER PT J AU Sovey, JS Rawlin, VK Patterson, MJ AF Sovey, JS Rawlin, VK Patterson, MJ TI Ion propulsion development projects in US: Space electric rocket test I to deep space 1 SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID CUSP AB The historical background and characteristics of the experimental Rights of ion propulsion systems and the major ground-based technology demonstrations are reviewed, The results of the first successful ion engine Right in 1964, Space Electric Rocket Test (SERT) I, which demonstrated ion beam neutralization, are discussed along with the extended operation of SERT II starting in 1970, These results together with the technologies employed on the early cesium engine Rights, the applications technology satellite series, and the ground-test demonstrations, have provided the evolutionary path for the development of xenon ion thruster component technologies, control systems, and power circuit implementations. In the 1997-1999 period, the communication satellite Rights using ion engine systems and the Deep Space 1 flight confirmed that these auxiliary and primary propulsion systems have advanced to a high level of Right readiness. C1 NASA, John H Glenn Res Ctr Lewis Field, Power & OnBoard Propuls Technol Div, Cleveland, OH 44135 USA. RP Sovey, JS (reprint author), NASA, John H Glenn Res Ctr Lewis Field, Power & OnBoard Propuls Technol Div, 21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 71 TC 24 Z9 24 U1 4 U2 10 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 MAY-JUN PY 2001 VL 17 IS 3 BP 517 EP 526 DI 10.2514/2.5806 PG 10 WC Engineering, Aerospace SC Engineering GA 434FN UT WOS:000168804600005 ER PT J AU Park, C Bogdanoff, D Mehta, UB AF Park, C Bogdanoff, D Mehta, UB TI Theoretical performance of frictionless magnetohydrodynamic-bypass scramjets SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Theoretical performance calculation is made of a scramjet propulsion system incorporating a magnetohydrodynamic (MHD)-energy-bypass scheme. The MHD generator upstream of the combustion chamber slows down the Row so that the Mach number at the entrance of the combustion chamber is kept below a specified value, The MHD accelerator downstream of the combustion chamber accelerates the Row, expending the electrical power produced by the generator. The Row is seeded with potassium or cesium, and the MHD devices operate as Faraday machines, Friction is neglected, and chemical equilibrium is assumed everywhere except in the nozzle downstream of the freezing point, The calculation shows that the MHD-bypass scheme can improve specific impulse over that of a conventional scramjet at Eight speeds over 3.5 km/s, At speeds below about 6 km/s, the calculated specific impulse fan be higher than that of a typical rocket engine, Consequently, the MHD-bypass scheme can extend the operational range or improve the performance of a conventional scramjet engine. C1 Eloret Corp, Sunnyvale, CA 94087 USA. NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. RP Park, C (reprint author), Eloret Corp, Sunnyvale, CA 94087 USA. NR 7 TC 8 Z9 14 U1 0 U2 1 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 MAY-JUN PY 2001 VL 17 IS 3 BP 591 EP 598 DI 10.2514/2.5782 PG 8 WC Engineering, Aerospace SC Engineering GA 434FN UT WOS:000168804600015 ER PT J AU Madavan, NK Rai, MM Huber, FW AF Madavan, NK Rai, MM Huber, FW TI Redesigning gas-generator turbines for improved unsteady aerodynamic performance using neural networks SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID HEAT-TRANSFER MEASUREMENTS; TRANSONIC TURBINE; DESIGN AB A recently developed neural network-based aerodynamic design procedure is used in the redesign of a gas-generator turbine stage to improve its unsteady aerodynamic performance. The redesign procedure used incorporates the advantages of both traditional response-surface methodology and neural networks by employing a strategy called parameter-based partitioning of the design space. Starting from the reference design, a sequence of response surfaces based on both neural networks and polynomial fits is constructed to traverse the design space in search of an optimal solution that exhibits improved unsteady performance. The procedure combines the power of neural networks and the economy of low-order polynomials tin terms of number of simulations required and network training requirements). A time-accurate, two-dimensional, Navier-Stokes solver is used to evaluate the various intermediate designs and provide inputs to the optimization procedure. The procedure yields a modified design that improves the aerodynamic performance through small changes to the reference design geometry, These results demonstrate the capabilities of the neural network-based design procedure and also show the advantages of including high-fidelity unsteady simulations that capture the relevant Row physics in the design optimization process. C1 NASA, Ames Res Ctr, Numer Aerosp Simulat Syst Div, Moffett Field, CA 94035 USA. Riverbend Design Serv, Palm Beach Gardens, FL 33418 USA. NASA, Ames Res Ctr, Informat Sci & Technol Directorate, Moffett Field, CA 94035 USA. RP Madavan, NK (reprint author), NASA, Ames Res Ctr, Numer Aerosp Simulat Syst Div, M-S T27A-I, Moffett Field, CA 94035 USA. NR 21 TC 2 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 2001 VL 17 IS 3 BP 669 EP 677 DI 10.2514/2.5794 PG 9 WC Engineering, Aerospace SC Engineering GA 434FN UT WOS:000168804600026 ER PT J AU Im, KS Kim, H Lai, MC Tacina, R AF Im, KS Kim, H Lai, MC Tacina, R TI Parametric study of the swirler/venturi spray injectors SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID COMBUSTORS; PRESSURE AB An experimental parametric study is carried out to characterize the spray From swirler/venturi injectors (SVIs) inside a steady-how pressure chamber. In this study, venturi tubes with diffuser angles of 20, 40, 60, and 80 deg and different throat lengths are combined with different swirlers with vane angles of 30, 45, and 60 deg to investigate their combined effect on spray structure. The ambient pressure conditions inside the chamber were varied from 0.1 to 0.4 MPa to simulate the relevant gas turbine density and momentum condition. For simplicity; water is used to present liquid fuel. Focusing on the spray atomization and dispersion aspects, laser diagnostic techniques are used to characterize the isothermal spray structure, including phase Doppler particle analyzer and copper-vapor laser-sheet visualization. Pressure drop across the SVI is also measured, It was found that the pressure drop and droplet size are dominated by the throat velocity, but are modified significantly by the divergent angle, throat length, and swirler. It is also shown that matching the correct swirler with the venturi geometry is important to obtain optimal liquid atomization and droplet distribution. C1 Wayne State Univ, Dept Mech Engn, Detroit, MI 48202 USA. NASA, John H Glenn Res Ctr, Combust Branch, Turbomachinery & Propuls Syst Div, Cleveland, OH 44135 USA. RP Im, KS (reprint author), Wayne State Univ, Dept Mech Engn, Detroit, MI 48202 USA. NR 30 TC 1 Z9 4 U1 1 U2 2 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 MAY-JUN PY 2001 VL 17 IS 3 BP 717 EP 727 DI 10.2514/2.5801 PG 11 WC Engineering, Aerospace SC Engineering GA 434FN UT WOS:000168804600032 ER PT J AU Pamadi, BN Brauckmann, GJ Ruth, MJ Fuhrmann, HD AF Pamadi, BN Brauckmann, GJ Ruth, MJ Fuhrmann, HD TI Aerodynamic characteristics, database development, and flight simulation of the X-34 vehicle SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT AIAA 38th Aerospace Sciences Meeting and Exhibit CY JAN 10-15, 2000 CL RENO, NEVADA SP Amer Inst Aeronatu & Astronaut AB An overview of the aerodynamic characteristics, development of the preflight aerodynamic database, and flight simulation of the NASA/Orbital X-34 vehicle is presented, To develop the aerodynamic database, wind tunnel tests from subsonic to hypersonic Mach numbers, including ground-effect tests at low subsonic speeds, were conducted in various facilities at the NASA Langley Research Center. Where wind-tunnel test data were not available, engineering level analysis was used to fill the gaps in the database. Using these aerodynamic data, simulations have been performed for typical design reference missions of the X-34 vehicle. C1 NASA, Langley Res Ctr, Vehicle Anal Branch, Aerosp Syst Concepts & Anal Competency, Hampton, VA 23681 USA. Orbital, Navigat & Control, Dulles, VA 20166 USA. NASA, Langley Res Ctr, Aerothermodynam Branch, Aerodynam & Aerothermodynam Competancy, Hampton, VA 23681 USA. RP Pamadi, BN (reprint author), NASA, Langley Res Ctr, Vehicle Anal Branch, Aerosp Syst Concepts & Anal Competency, Hampton, VA 23681 USA. NR 15 TC 3 Z9 3 U1 1 U2 4 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 MAY-JUN PY 2001 VL 38 IS 3 BP 334 EP 344 DI 10.2514/2.3706 PG 11 WC Engineering, Aerospace SC Engineering GA 442XF UT WOS:000169309700003 ER PT J AU Desai, PN Cheatwood, FM AF Desai, PN Cheatwood, FM TI Entry dispersion analysis for the genesis sample return capsule SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT AAS/AIAA Astrodynamics Conference CY AUG 16-19, 1999 CL GIRDWOOD, ALASKA SP Amer Astronaut Soc, Amer Inst Aeronaut & Astronaut ID STARDUST AB Genesis will be the first mission to return samples from beyond the Earth-moon system. The spacecraft will be inserted into a halo orbit about the sun-Earth collinear libration point L-1 located between the sun and Earth, where it will remain for 2 gears collecting solar wind particles. Upon Earth return, the sample return capsule, which is passively controlled, will descend under parachute to Utah. Analysis of the entry, descent, and landing scenario of the returning sample capsule is described. In particular, the use of gyroscopic stiffness to suppress aerodynamic instabilities is presented. The robustness of the overall entry sequence is assessed through a Monte Carlo dispersion analysis, where the impact of off-nominal conditions is ascertained. The dispersion results indicate that the capsule attitude excursions near peak heating and drogue chute deployment are within Genesis mission limits. Additionally, the size of the resulting 3-sigma landing ellipse is 47.8 km in downrange by 15.2 km in cross-range, which is within the Utah Test and Training Range boundaries. C1 NASA, Langley Res Ctr, Aerosp Syst Concepts & Anal Competency, Hampton, VA 23681 USA. RP Desai, PN (reprint author), NASA, Langley Res Ctr, Aerosp Syst Concepts & Anal Competency, Hampton, VA 23681 USA. NR 14 TC 8 Z9 9 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 MAY-JUN PY 2001 VL 38 IS 3 BP 345 EP 350 DI 10.2514/2.3707 PG 6 WC Engineering, Aerospace SC Engineering GA 442XF UT WOS:000169309700004 ER PT J AU Chen, PT Thomson, S Woronowicz, MS AF Chen, PT Thomson, S Woronowicz, MS TI Applying contamination modeling to spacecraft conventional propulsion system designs and operations SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Molecular and particulate contaminants generated from the operations of a propulsion system can impinge on spacecraft critical surfaces. Plume depositions or clouds can hinder the spacecraft and instruments from performing normal operations. The interconnection between the functions of spacecraft contamination modeling and propulsion system implementation is presented. An innovative contamination engineering approach is addressed during a spacecraft mission, which includes concept design, manufacturing, integration and test, launch, and on-orbit operations. A summary of the implementation on several successful missions is also presented. C1 NASA, Goddard Space Flight Ctr, Tech Contaminat Staff, Thermal Engn Branch, Greenbelt, MD 20771 USA. Swales Aerosp, Beltsville, MD 20705 USA. RP Chen, PT (reprint author), NASA, Goddard Space Flight Ctr, Tech Contaminat Staff, Thermal Engn Branch, Greenbelt, MD 20771 USA. NR 19 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 MAY-JUN PY 2001 VL 38 IS 3 BP 388 EP 392 DI 10.2514/2.3696 PG 5 WC Engineering, Aerospace SC Engineering GA 442XF UT WOS:000169309700011 ER PT J AU Brinza, D Wang, J Polk, J Henry, M AF Brinza, D Wang, J Polk, J Henry, M TI Deep Space 1 measurements of ion propulsion contamination SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The first in situ measurements are reported of ion propulsion-induced contamination from an interplanetary spacecraft, NASA's New Millennium Deep Space 1. Deep Space 1 carries two quartz crystal microbalance and calorimeter pairs to characterize contaminant deposition due to ion thruster operation. One pair of sensors has a direct line-of-sight view of the ion engine whereas the other pair is shadowed from direct view of the engine. After about 2750 h of ion thruster operation in the first year of the mission, the line-of-sight sensor has collected about 250 Angstrom of molybdenum, and the non-line of-sight sensor has only collected the equivalent mass of a 25-Angstrom -thick deposit of molybdenum. The line-of-sight deposition rate appears proportional to the thrust level, whereas the non-line-of-sight deposition rate increases much more rapidly with the thrust level. Measurement results suggest that significant backflow of ionized molybdenum particles would occur primarily at high thrusting levels when both the molybdenum ionization rate and the plume potential relative to the spacecraft are higher than that at lower thrusting levels. C1 CALTECH, Jet Prop Lab, Adv Propp Technol Grp, Pasadena, CA 91109 USA. RP Brinza, D (reprint author), CALTECH, Jet Prop Lab, Adv Propp Technol Grp, MS 125-177, Pasadena, CA 91109 USA. NR 12 TC 4 Z9 6 U1 1 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 MAY-JUN PY 2001 VL 38 IS 3 BP 426 EP 432 DI 10.2514/2.3701 PG 7 WC Engineering, Aerospace SC Engineering GA 442XF UT WOS:000169309700016 ER PT J AU Wang, J Brinza, D Young, M AF Wang, J Brinza, D Young, M TI Three-dimensional particle simulations of ton propulsion plasma environment for Deep Space 1 SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID ION-THRUSTER PLUME; IN-CELL; PLATFORMS; FLOW AB A fully three-dimensional particle-in-cell simulation model was developed to compute the ion propulsion induced plasma environment for the Deep Space 1 (DS1) spacecraft. Simulations are compared with in-flight measurements of charge-exchange plasma from the ion propulsion diagnostics subsystem on DSI, and the results show good agreement. It is found that the plasma environment of DS1 is dominated by the charge-exchange plasma from the plume. For a typical ion thruster operating condition, the charge exchange plasma near the spacecraft surface has a density ranging from 10(6) cm(-3) near the thruster to 10(4) cm-3 at the opposite end of the spacecraft and a current density ranging from 10(-7) A/cm(2) to 10(-9) A/cm(2). It is shown that, for an interplanetary spacecraft with a moderate charging potential, charge-exchange ion backflow is through an expansion process similar to that of the expansion of a mesothermal plasma into a vacuum. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ So Calif, Dept Aerosp & Mech Engn, Los Angeles, CA 90089 USA. RP Wang, J (reprint author), CALTECH, Jet Prop Lab, MS 127-177, Pasadena, CA 91109 USA. NR 21 TC 24 Z9 29 U1 1 U2 5 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 MAY-JUN PY 2001 VL 38 IS 3 BP 433 EP 440 DI 10.2514/2.3702 PG 8 WC Engineering, Aerospace SC Engineering GA 442XF UT WOS:000169309700017 ER PT J AU Gatsonis, NA Eckman, R Yin, XM Pencil, EJ Myers, RM AF Gatsonis, NA Eckman, R Yin, XM Pencil, EJ Myers, RM TI Experimental investigations and numerical modeling of pulsed plasma thruster plumes SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Integration of pulsed plasma thruster (PPT) onboard spacecraft requires the evaluation of potential plume/spacecraft interactions. Important findings are summarized of our experimental and modeling plume investigations of rectangular-geometry Teflon((R)) PPTs. Initial studies of the Lincoln Experimental Satellite 8/9 PPT plume used time-of-flight analysis of single langmuir probe data and found two ion populations with approximately 30 and 60 km/s, respectively. A residual gas analyzer identified C, F, C,Fy, and various thruster materials. Fast ionization gauges detected the presence of slow neutral particles up to 1 ms after the end of the discharge. Subsequent studies used triple langmuir probes and obtained electron temperature and density in the plume of a laboratory PPT operating at 5, 20, and 40 J. Plume properties showed large angular density variation on the perpendicular to the electrodes plane but small variation on the parallel plane. Electron density and temperature were found to decrease with increasing radial distance from the Teflon surface. Time-average temperatures were between 1 and 3 eV. Time-average electron density increased with increasing discharge energy and are in the range between 10(19) and 2 x 10(20) m(-3) for 5 J, 6 x 10(20) to 10(21 m-3) for 20 J, and 2 x 10(20) to 1.4 x 10(21) m(-3) for 40 J. The PPT plume model is based on a hybrid (particle-fluid) methodology. Neutrals and ions were modeled with a combination of the direct simulation Monte Carlo and a hybrid-particle-in-cell method. Electrons were modeled as a massless fluid with a momentum equation that includes collisional contributions from ions and neutrals and an energy equation. Simulations of the laboratory PPT operating at discharge energies of 5, 20, and 40 J showed the expansion of the neutral and ion components of the plume during a pulse, the generation of low energy ions and high-energy neutrals due to charge exchange reactions, and the generation of backflow. Numerical predictions showed good quantitative agreements with data. C1 Worcester Polytech Inst, Dept Engn Mech, Worcester, MA 01609 USA. NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. RP Gatsonis, NA (reprint author), Worcester Polytech Inst, Dept Engn Mech, 100 Inst Rd, Worcester, MA 01609 USA. NR 41 TC 8 Z9 9 U1 0 U2 7 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 MAY-JUN PY 2001 VL 38 IS 3 BP 454 EP 464 DI 10.2514/2.3704 PG 11 WC Engineering, Aerospace SC Engineering GA 442XF UT WOS:000169309700019 ER PT J AU Gouadec, G Colomban, P Bansal, NP AF Gouadec, G Colomban, P Bansal, NP TI Raman study of Hi-Nicalon-fiber-reinforced celsian composites: I, distribution and nanostructure of different phases SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID CERAMIC-MATRIX COMPOSITES; CUBIC BORON-NITRIDE; SIC POLYTYPES; MECHANICAL-BEHAVIOR; DIAMOND FILMS; SPECTROSCOPY; GRAPHITE; SPECTRA; CARBIDE; SCATTERING AB Hi-Nicalon-fiber-reinforced celsian-matrix composites were characterized by Raman spectroscopy and imaging, using several laser wavelengths. Composite 1 was reinforced by as-received fibers while coatings of p-BN and SiC protected the fibers in composite 2. The matrix contained traces of the hexagonal phase of celsian, which was concentrated in the neighborhood of fibers in composite 1. Some free silicon was evident in the coating of composite 2 which might have involved a IBN C SiC --> BNC + Si) "reaction" at the p-BN/SiC interface. Careful analysis of C-C peaks revealed no abnormal degradation of the fiber core in the composites. C1 CNRS, UMR7075, Lab Dynam Interact Reactivite, F-94320 Thiais, France. Univ Paris 06, F-94320 Thiais, France. Off Natl Etud & Rech Aerosp, Dept Mat & Syst Composites, F-92322 Chatillon, France. NASA, John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. RP Gouadec, G (reprint author), CNRS, UMR7075, Lab Dynam Interact Reactivite, F-94320 Thiais, France. RI Gouadec, Gwenael/P-6526-2016 OI Gouadec, Gwenael/0000-0002-1476-2765 NR 47 TC 17 Z9 17 U1 0 U2 4 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 USA SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD MAY PY 2001 VL 84 IS 5 BP 1129 EP 1135 PG 7 WC Materials Science, Ceramics SC Materials Science GA 431XM UT WOS:000168657100034 ER PT J AU Gouadec, G Colomban, P Bansal, NP AF Gouadec, G Colomban, P Bansal, NP TI Raman study of Hi-Nicalon-fiber-reinforced celsian composites: II, residual stress in fibers SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID CERAMIC-MATRIX COMPOSITES; COMPRESSIONAL BEHAVIOR; CARBON-FIBERS; SPECTROSCOPY; FRAGMENTATION; SILICON; STRAIN; MODEL AB Band shifts in Raman spectra were used to assess, on a microscopic scale, the residual strain existing in Hi-Nicalon silicon carbide fibers reinforcing celsian-matrix composites, Uncoated as well as p-BN/SiC-coated and p-B(Si)N/SiC-coated Hi-Nicalon fibers were used as the reinforcements. We unambiguously conclude that the fibers were in a state of compressive residual stress. Quantitative determination of the residual stress was made possible by taking into account the heating induced by laser probing and by using a reference line, of fixed wavenumber, We found fiber compressive residual stress values between 110 and 960 MPa, depending on the fiber/ matrix coating in the composite, A stress relaxation-like phenomenon was observed at the surface of p-BN/SiC-coated Hi-Nicalon fibers whereas the uncoated or p-B(Si)N/SiC-coated Hi-Nicalon fibers did not show any stress relaxation in the celsian-matrix composites. C1 CNRS, UMR7075, Lab Dynam Interact Reactivite, F-94320 Thiais, France. Univ Paris 06, F-94320 Thiais, France. Off Natl Etud & Rech Aerosp, Dept Mat & Syst Composites, F-92322 Chatillon, France. NASA, John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. RP Gouadec, G (reprint author), CNRS, UMR7075, Lab Dynam Interact Reactivite, F-94320 Thiais, France. RI Gouadec, Gwenael/P-6526-2016 OI Gouadec, Gwenael/0000-0002-1476-2765 NR 37 TC 23 Z9 23 U1 2 U2 5 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 USA SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD MAY PY 2001 VL 84 IS 5 BP 1136 EP 1142 PG 7 WC Materials Science, Ceramics SC Materials Science GA 431XM UT WOS:000168657100035 ER PT J AU Milligan, DB Freeman, CG Maclagan, RGAR McEwan, MJ Wilson, PF Anicich, VG AF Milligan, DB Freeman, CG Maclagan, RGAR McEwan, MJ Wilson, PF Anicich, VG TI Termolecular ion-molecule reactions in Titan's atmosphere. II: The structure of the association adducts of HCNH+ with C2H2 and C2H4 SO JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY LA English DT Article ID IONOSPHERE; CHEMISTRY; H3O+ AB The ion-molecule reactivity of the products formed in the association reactions of HCNH+ with C2H2 (C3H4N+) and C2H4 (C3H6N+) has been investigated to provide information on the structures of the adducts thus formed. The C3H4N+ and C3H6N+ adducts were formed in the reaction flow tube of a flowing afterglow sourced-selected ion flow tube (FA-SIFT) and their reactivity with a neutral molecular "probe" examined. The reactivity of possible known structural isomers for the C3H4N+ and C3H6N+ ions was investigated in both the FA-SIFT and an ion cyclotron resonance spectrometer (ICR). Ab initio investigations of the potential energy surfaces for both structures at the G2(MP2) level have also been performed and structures corresponding to local minima on both surfaces have been identified and evaluated. The results of these experimental and theoretical studies show that at room temperature, the C3H4N+ adduct ion contains two isomers; a less reactive one that is likely to be a four-membered cyclic covalent isomer (similar to 70%) and a faster reacting component that is probably an electrostatic complex (similar to 30%). The C3H6N+ adduct ion formed from HCNH+ + C2H4 at room temperature is a single isomer that is likely to be the four-membered covalently bound cyclic CH2CH2CHNH+ species. (J Am Soc Mass Spectrom 2001, 12, 557-564) (C) 2001 American Society for Mass Spectrometry. C1 Univ Canterbury, Dept Chem, Christchurch, New Zealand. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP McEwan, MJ (reprint author), Univ Canterbury, Dept Chem, Christchurch, New Zealand. NR 24 TC 9 Z9 9 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 1044-0305 J9 J AM SOC MASS SPECTR JI J. Am. Soc. Mass Spectrom. PD MAY PY 2001 VL 12 IS 5 BP 557 EP 564 DI 10.1016/S1044-0305(01)00215-X PG 8 WC Chemistry, Analytical; Chemistry, Physical; Spectroscopy SC Chemistry; Spectroscopy GA 428WA UT WOS:000168483600010 PM 11349953 ER PT J AU Beyerle, G Gross, MR Haner, DA Kjome, NT McDermid, IS McGee, TJ Rosen, JM Schafer, HJ Schrems, O AF Beyerle, G Gross, MR Haner, DA Kjome, NT McDermid, IS McGee, TJ Rosen, JM Schafer, HJ Schrems, O TI A lidar and backscatter sonde measurement campaign at Table Mountain during February-March 1997: Observations of cirrus clouds SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID MICROPHYSICAL PROPERTIES; OPTICAL-PROPERTIES; ICE CLOUDS; DEPOLARIZATION; EXTINCTION; MIDLATITUDE; SCATTERING; CLIMATE AB Results from a measurement campaign performed at Table Mountain Facility/Jet Propulsion Laboratory/California Institute of Technology (34.38 degreesN, 117.68 degreesW, 2280 m ASL) are presented. Between 19 February and 18 March 1997 more than 400 h worth of lidar data were acquired and four backscatter sondes were launched. About 50% of the observations show the presence of cirrus clouds at altitudes close to and below the tropopause. Of these clouds 80% are characterized as subvisual with optical depths below 0.03 at a wavelength of 532 nm. Simple geometrical considerations lead to cloud spatial scales of 0.31 km vertically and 7.5 km horizontally, respectively. Deviations from color ratio values derived on the basis of geometrical optics are interpreted as small particle signatures. Comparing backscatter ratio profiles observed concurrently by three aerosol lidars, mean deviations of about 10% are found. C1 CALTECH, Jet Prop Lab, Wrightwood, CA USA. Univ Maryland, Joint Ctr Earth Syst Technol, Baltimore, MD 21201 USA. Calif State Polytech Univ Pomona, Dept Chem, Pomona, CA USA. Univ Wyoming, Dept Phys & Astron, Laramie, WY 82071 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Alfred Wegener Inst Polar & Marine Res, D-2850 Bremerhaven, Germany. Alfred Wegener Inst Polar & Marine Res, Potsdam, Germany. RP Beyerle, G (reprint author), Geoforschungszentrum Potsdam, Div Kinemat Dynam Earth, Telegrafenberg A17-PB1 1, D-14473 Potsdam, Germany. RI McGee, Thomas/G-4951-2013; OI Beyerle, Georg/0000-0003-1215-2418 NR 27 TC 19 Z9 20 U1 2 U2 5 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 MAY PY 2001 VL 58 IS 10 BP 1275 EP 1287 DI 10.1175/1520-0469(2001)058<1275:ALABSM>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 430EZ UT WOS:000168562700005 ER PT J AU Tao, WK Shie, CL Simpson, J AF Tao, WK Shie, CL Simpson, J TI Comments on "A sensitivity study of radiative-convective equilibrium in the tropics with a convection-resolving model'' SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID LARGE-SCALE PROCESSES; LONG-TERM BEHAVIOR; CLOUD SYSTEMS; MESOSCALE PROCESSES; CUMULUS CLOUDS; DEEP; SIMULATION C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Mesoscale Atmospher Proc Branch, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. RP Tao, WK (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Mesoscale Atmospher Proc Branch, Code 912, Greenbelt, MD 20771 USA. NR 18 TC 4 Z9 5 U1 0 U2 0 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 MAY PY 2001 VL 58 IS 10 BP 1328 EP 1333 DI 10.1175/1520-0469(2001)058<1328:COASSO>2.0.CO;2 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 430EZ UT WOS:000168562700009 ER PT J AU Xu, KM Randall, DA AF Xu, KM Randall, DA TI Comments on "A sensitivity study of radiative-convective equilibrium in the tropics with a convection-resolving model" - Reply SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Editorial Material ID CLOUD SYSTEMS; MESOSCALE PROCESSES; CUMULUS ENSEMBLES; PHASE-III; DEEP; SIMULATION; BEHAVIOR; MOISTURE; BUDGETS; STATES C1 Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. RP Xu, KM (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. RI Xu, Kuan-Man/B-7557-2013; Randall, David/E-6113-2011 OI Xu, Kuan-Man/0000-0001-7851-2629; Randall, David/0000-0001-6935-4112 NR 19 TC 0 Z9 0 U1 0 U2 0 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 MAY PY 2001 VL 58 IS 10 BP 1334 EP 1338 DI 10.1175/1520-0469(2001)058<1334:R>2.0.CO;2 PG 5 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 430EZ UT WOS:000168562700010 ER PT J AU Ostraat, ML De Blauwe, JW Green, ML Bell, LD Atwater, HA Flagan, RC AF Ostraat, ML De Blauwe, JW Green, ML Bell, LD Atwater, HA Flagan, RC TI Ultraclean two-stage aerosol reactor for production of oxide-passivated silicon nanoparticles for novel memory devices SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID DIFFERENTIAL MOBILITY ANALYZER; PARTICLES AB Silicon nanoparticle-based floating gate metal oxide semiconductor field effect devices are attractive candidates for terabit cm(-2) density nonvolatile memory applications. We have designed an ultraclean two-stage aerosol process reactor and 200 mm wafer deposition chamber in order to integrate Si/SiO2 nanoparticles into memory devices. In the first stage, silicon nanoparticles are synthesized by thermal decomposition of silane gas in a reactor that has been optimized to produce nonagglomerated nanoparticles at rates sufficient for layer deposition. In the second stage, the silicon particles are passivated with thermal oxide that partly consumes the particle. This two-stage aerosol reactor has been integrated to a 200 mm silicon wafer deposition chamber that is contained within a class 100 cleanroom environment. This entire reactor system conforms to rigorous cleanliness specifications such that we can control transition metal contamination to as good as 10(10) atoms cm(-2). The deposition chamber has been designed to produce a controllable particle density profile along a 200 mm wafer where particles are thermophoretically deposited uniformly over three-quarters of the wafer. Thus, we now have the capability to deposit controlled densities of oxide-passivated silicon nanoparticles onto 200 mm silicon wafers for production of silicon nanoparticle memory devices. (C) 2001 The Electrochemical Society. C1 CALTECH, Pasadena, CA 91125 USA. Agere Syst, Murray Hill, NJ 07974 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ostraat, ML (reprint author), CALTECH, Pasadena, CA 91125 USA. NR 8 TC 50 Z9 50 U1 0 U2 16 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 MAY PY 2001 VL 148 IS 5 BP G265 EP G270 DI 10.1149/1.1360210 PG 6 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA 427TH UT WOS:000168421200059 ER PT J AU Chen, PC Romeo, RC AF Chen, PC Romeo, RC TI Graphite fiber strengthens lightweight mirrors SO LASER FOCUS WORLD LA English DT Article AB Composites based on graphite fibers allow large-aperture mirrors to be made extremely lightweight, while maintaining rigidity and strength. Applications include large telescopes. C1 Composite Mirror Applicat Inc, Tucson, AZ USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Chen, PC (reprint author), Composite Mirror Applicat Inc, Tucson, AZ USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU PENNWELL PUBL CO PI NASHUA PA 98 SPIT BROOK RD, NASHUA, NH 03062-2801 USA SN 0740-2511 J9 LASER FOCUS WORLD JI Laser Focus World PD MAY PY 2001 VL 37 IS 5 BP 193 EP + PG 4 WC Optics SC Optics GA 432RM UT WOS:000168709500044 ER PT J AU DellaCorte, C AF DellaCorte, C TI Asleep at the wheel? SO LUBRICATION ENGINEERING LA English DT Editorial Material C1 NASA, Glenn Res Ctr, Washington, DC 20546 USA. RP DellaCorte, C (reprint author), NASA, Glenn Res Ctr, Washington, DC 20546 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 MAY PY 2001 VL 57 IS 5 BP 3 EP 3 PG 1 WC Engineering, Mechanical SC Engineering GA 432RP UT WOS:000168709700001 ER PT J AU Brill, R Swimmer, Y Taxboel, C Cousins, K Lowe, T AF Brill, R Swimmer, Y Taxboel, C Cousins, K Lowe, T TI Gill and intestinal Na+-K+ ATPase activity, and estimated maximal osmoregulatory costs, in three high energy-demand teleosts: yellowfin tuna (Thunnus albacares), skipjack tuna (Katsuwonus pelamis), and dolphin fish (Coryphaena hippurus) SO MARINE BIOLOGY LA English DT Article ID TILAPIA OREOCHROMIS-MOSSAMBICUS; STANDARD METABOLIC-RATE; TROUT SALMO-GAIRDNERI; FRESH-WATER; SEAWATER ACCLIMATION; OXYGEN-CONSUMPTION; RAINBOW-TROUT; CARBONIC-ANHYDRASE; EURYHALINE TELEOST; ENZYME-ACTIVITIES AB We hypothesize that the morpho-physiological adaptations that permit tunas to achieve maximum metabolic rates (MMR) that are more than double those of other active fishes should result in high water and ion flux rates across the gills and concomitant high osmoregulatory costs. The high standard metabolic rates (SMR) of tunas and dolphin fish may, therefore, be due to the elevated rates of energy expenditure for osmoregulation (i.e. teleosts capable of achieving exceptionally high MMR necessarily have SMR). Previous investigators have suggested a link between activity patterns and osmoregulatory costs based on Na+-K+ ATPase activity in the gills of active epipelagic and sluggish deepsea fishes. Based on these observations, we conclude that high-energy-demand fishes (i.e, tunas and dolphin fish) should have exceptionally elevated gill and intestinal Na+-K+ ATPase activity reflecting their elevated rates of salt and water transfer. To test this idea and estimate osmoregulatory costs, we measured Naf-Kf ATPase activity (V,,,) in homogenates of frozen samples taken from the gills and intestines of skipjack and yellowfin tunas, and the gills of dolphin fish. As a check of our procedures, we made similar measurements using tissues from hybrid red tilapia (Oreochromis mossambicus x O. niloticus). Contrary to our supposition, we found no difference in Na+-K+ ATPase activity per unit mass of gill or intestine in these four species. We estimate the cost of osmoregulation to be at most 9% and 13% of the SMR in skipjack tuna and yellowfin tuna, respectively. Our results, therefore, do not support either of our original suppositions, and the cause(s) underlying the high SMR of tunas and dolphin fish remain unexplained. C1 Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Joint Inst Marine & Atmospher Res, Pelag Fisheries Res Program, Honolulu, HI 96822 USA. RP Brill, R (reprint author), NOAA, Natl Marine Fisheries Serv, 2570 Dole St, Honolulu, HI 96822 USA. NR 90 TC 18 Z9 18 U1 2 U2 18 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0025-3162 J9 MAR BIOL JI Mar. Biol. PD MAY PY 2001 VL 138 IS 5 BP 935 EP 944 DI 10.1007/s002270000514 PG 10 WC Marine & Freshwater Biology SC Marine & Freshwater Biology GA 439HD UT WOS:000169104300005 ER PT J AU Yeo, HS Chopra, I AF Yeo, HS Chopra, I TI Coupled rotor/fuselage vibration analysis using detailed 3-D airframe models SO MATHEMATICAL AND COMPUTER MODELLING LA English DT Article DE helicopter vibration; rotor/fuselage coupling; AH-1G helicopter; NASTRAN airframe AB A comprehensive vibration analysis of a coupled rotor/fuselage system is carried out using detailed 3-D finite element models of the AH-1G airframe from the DAMVIBS program. Predicted vibration results are compared with operational load survey flight test data of the AH-1G helicopter, Modeling of difficult components (secondary structures, doors/panels, etc.) is essential in predicting airframe natural frequencies. Calculated 2/rev vertical vibration levels at the pilot seat show good correlation with the flight test data both in magnitude and phase, but 4/rev vibration levels show fair correlation only in magnitude. Lateral vibration results show more disagreement than vertical vibration results. Refined aerodynamics such as fi ee wake and unsteady aerodynamics have an important role in the prediction of vibration. Main rotor pylon roll mode has a significant contribution (about 26%) on the 2/rev vibration. Accurate prediction of airframe natural frequencies up to about 40 Hz appears essential to predict vibration in airframe. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, Raytheon ITSS, Stanford, CA 94305 USA. Univ Maryland, Dept Aerosp Engn, Alfred Gessow Rotorcraft Ctr, College Pk, MD 20742 USA. RP Yeo, HS (reprint author), NASA, Ames Res Ctr, Raytheon ITSS, Mail Stop 215-1, Stanford, CA 94305 USA. NR 18 TC 4 Z9 4 U1 1 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0895-7177 J9 MATH COMPUT MODEL JI Math. Comput. Model. PD MAY-JUN PY 2001 VL 33 IS 10-11 BP 1035 EP 1054 DI 10.1016/S0895-7177(00)00299-5 PG 20 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Mathematics, Applied SC Computer Science; Mathematics GA 422XA UT WOS:000168143500002 ER PT J AU Ruzicka, GC Hodges, DH AF Ruzicka, GC Hodges, DH TI Application of the mixed finite-element method to rotor blade modal reduction SO MATHEMATICAL AND COMPUTER MODELLING LA English DT Article DE mixed finite elements; beam theory; rotor blades; modal reduction AB A mixed finite element is investigated as a means for achieving accurate modal reduction of rotor blades in finite-element software. A rationale for mixed finite elements is developed by investigating the modal reduction accuracy of a series of blade analysis methods that introduces, in a step-by-step fashion, the key features of the mixed element. During this investigation, the shortcomings of classical, displacement-based finite elements are examined qualitatively and through calculations of articulated blade response. The formal derivation of the mixed element starting from a mixed variational principle is then summarized, and finally, numerical examples are presented to demonstrate the element's modal reduction accuracy. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 USA, Army NASA Rotorcraft Div, Aeroflightdynam Directorate, AMRDEC,Aviat & Missile Command,Ames Res Ctr, Moffett Field, CA 94035 USA. Georgia Inst Technol, Sch Aerosp Engn, Atlanta, GA 30332 USA. RP Ruzicka, GC (reprint author), USA, Army NASA Rotorcraft Div, Aeroflightdynam Directorate, AMRDEC,Aviat & Missile Command,Ames Res Ctr, Moffett Field, CA 94035 USA. NR 18 TC 4 Z9 4 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0895-7177 J9 MATH COMPUT MODEL JI Math. Comput. Model. PD MAY-JUN PY 2001 VL 33 IS 10-11 BP 1177 EP 1202 DI 10.1016/S0895-7177(00)00306-X PG 26 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Mathematics, Applied SC Computer Science; Mathematics GA 422XA UT WOS:000168143500009 ER PT J AU Stone, M Dismukes, K Remington, R AF Stone, M Dismukes, K Remington, R TI Prospective memory in dynamic environments: Effects of load, delay, and phonological rehearsal SO MEMORY LA English DT Article ID WORKING-MEMORY; TIME; AGE; INTENTIONS AB A new paradigm was developed to examine prospective memory performance in a visual-spatial task that resembles some aspects of the work of air traffic controllers. Two experiments examined the role of workload (number of aeroplanes that participants directed), delay (between receipt of prospective instructions and execution), and phonological rehearsal. High workload increased prospective memory errors but increasing delay from 1-3 or 5 minutes had no effect. Shadowing aurally presented text reduced prospective memory performance, presumably because it prevented verbal rehearsal of the prospective instructions. However, performance on the foreground task of directing aeroplanes to routine destinations was affected only by workload and not by opportunity for rehearsal. Our results suggest that ability to maintain performance on a routine foreground task while performing a secondary task-perhaps analogous to conversation-does not predict ability to retrieve a prospective intention to deviate from the routine. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Dismukes, K (reprint author), NASA, Ames Res Ctr, Mail Stop 262-4, Moffett Field, CA 94035 USA. NR 37 TC 27 Z9 27 U1 1 U2 5 PU PSYCHOLOGY PRESS PI HOVE PA 27 CHURCH RD, HOVE BN3 2FA, EAST SUSSEX, ENGLAND SN 0965-8211 J9 MEMORY JI Memory PD MAY PY 2001 VL 9 IS 3 BP 165 EP 176 PG 12 WC Psychology, Experimental SC Psychology GA 438TM UT WOS:000169070400002 PM 11469311 ER PT J AU Cassen, P AF Cassen, P TI Nebular thermal evolution and the properties of primitive planetary materials SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID PROTOPLANETARY ACCRETION DISKS; OXYGEN-ISOTOPIC COMPOSITION; SOLAR NEBULA; CHEMICAL-REACTIONS; CARBONACEOUS CHONDRITES; GLOBAL EVOLUTION; SOLID MATTER; DUST; CONSTRAINTS; METEORITES AB Models of the solar nebula are constructed to investigate the hypothesis that surviving planetary objects began to form as the nebula cooled from an early, hot epoch. The imprint of such an epoch might be retained in the spatial distribution of planetary material, the systematic deviations of its elemental composition from that of the Sun, chemical indicators of primordial oxidation state, and variations in oxygen and other isotopic compositions. Our method of investigation is to calculate the time-dependent, two-dimensional temperature distributions within model nebulas of prescribed dynamical evolution, and to deduce the consequences of the calculated thermal histories for coagulated solid material. The models are defined by parameters which characterize nebular initial states (mass and angular momentum), mass accretion histories, and coagulation rates and efficiencies. It is demonstrated that coagulation during the cooling of the nebula from a hot state is expected to produce systematic heterogeneities which affect the chemical and isotopic compositions of planetary material. The radial thermal gradient at the midplane results in delayed coagulation of the more volatile elements. Vertical thermal gradients isolate the most refractory material and concentrate evaporated heavy elements in the gas phase. It is concluded that these effects could be responsible for the distribution of terrestrial planetary masses, the systematic depletion patterns of the moderately volatile elements in chondritic meteorites and the Earth, the range of oxygen isotopic compositions exhibited by calcium-aluminum-rich inclusions (CAIs) and other refractory inclusions, and some geochemical evidence for a moderately enhanced oxidation state. However, nebular fractionations on a global scale are unlikely to account for the more oxidizing conditions inferred for some CAIs and chondritic silicates, which require dust enhancements greater than a few hundred. This conclusion, along with the well-established evidence from studies of chondrules and CAIs for thermal excursions of short duration, make it likely that local environments, unrelated to nebular thermal evolution, were also important. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Cassen, P (reprint author), NASA, Ames Res Ctr, Mail Stop 245-3, Moffett Field, CA 94035 USA. NR 81 TC 74 Z9 74 U1 2 U2 7 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAY PY 2001 VL 36 IS 5 BP 671 EP 700 PG 30 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 438YF UT WOS:000169081300009 ER PT J AU Osinski, GR Spray, JG Lee, P AF Osinski, GR Spray, JG Lee, P TI Impact-induced hydrothermal activity within the Haughton impact structure, arctic Canada: Generation of a transient, warm, wet oasis SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID LEAD-ZINC DEPOSITS; REACTIONS FORMING PYRITE; DEVON-ISLAND; MARCASITE; CRATER; MARS; 100-DEGREES-C; EQUILIBRIA; GENESIS; SOIL AB Field studies and analytical scanning electron microscopy indicate that a hydrothermal system was created by the interaction of water with hot, impact-generated rocks following formation of the 24 km diameter, 23 Ma Haughton impact structure. Hydrothermal alteration is recognized in two settings: within polymict impact breccias overlying the central portion of the structure, and within localized pipes in impact-generated concentric fault systems. The intra-breccia alteration comprises three varieties of cavity and fracture filling: (a) sulfide with carbonate, (b) sulfate, and (c) carbonate. These are accompanied by subordinate celestite, barite, fluorite, quartz and marcasite. Selenite is also developed, particularly in the lower levels of the impact breccia sheet. The fault-related hydrothermal alteration occurs in 1-7 m diameter subvertical pipes that are exposed for lengths of up 20 m. The pipes are defined by a monomict quartz-carbonate breccia showing pronounced Fe-hydroxide alteration. Associated sulfides include marcasite, pyrite and chalcopyrite. We propose three distinct stages in the evolution of the hydrothermal system: (1) Early Stage (> 200 degreesC), with the precipitation of quartz (vapor phase dominated); (2) Main Stage (200-100 degreesC), with the development of a two-phase (vapor plus liquid) zone, leading to calcite, celestite, barite, marcasite and fluorite precipitation; and (3) Late Stage (< 100 degreesC), with selenite and fibroferrite development through liquid phase-dominated precipitation. We estimate that it took several tens of thousands of years to cool below 50 degreesC following impact. During this time, Haughton supported a 14 km diameter crater lake and subsurface water system, providing a warmer, wetter niche relative to the surrounding terrain. The results reveal how understanding the internal structure of impact craters is necessary in order to determine their plumbing and cooling systems. C1 Univ New Brunswick, Dept Geol, Planetary & Space Sci Ctr, Fredericton, NB E3B 5A3, Canada. NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. RP Osinski, GR (reprint author), Univ New Brunswick, Dept Geol, Planetary & Space Sci Ctr, 2 Bailey Dr, Fredericton, NB E3B 5A3, Canada. RI Spray, John/J-7504-2013 NR 55 TC 96 Z9 97 U1 0 U2 14 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAY PY 2001 VL 36 IS 5 BP 731 EP 745 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 438YF UT WOS:000169081300011 ER PT J AU Rodgers, SD Charnley, SB AF Rodgers, SD Charnley, SB TI On the origin of HNC in Comet Lee SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE comets : general; comets : individual : Lee ID BOPP C/1995 O1; HALLEY DUST PARTICLES; HALE-BOPP; SPECTROSCOPIC OBSERVATIONS; INFRARED-SPECTROSCOPY; DENSITY DISTRIBUTION; RADIO TELESCOPES; B2 HYAKUTAKE; P-HALLEY; H1 LEE AB We have modelled the chemistry occurring in the coma of Comet Lee and have critically evaluated the possible routes leading to HNC. We show that the observed levels of HNC cannot be produced by ion-molecule chemistry, or by reactions of energetic H atoms with HCN. Rather, it appears that HNC is injected into the coma following the photodestruction of an unknown precursor. We discuss the possible nature of the parent of HNC and conclude that photofragmentation of large HCN polymers, such as polyaminocyanomethylene (PACM), is responsible. The degradation of hydrogen cyanide polymers may constitute a common source of HNC in comets, accounting for HNC/HCN ratios in the range measured in Lee and Hyakutake (approximate to0.06-0.12). The high HNC/HCN ratio measured in Hale-Bopp (approximate to0.2) and its heliocentric variation may, however, require an additional source. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP 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 69 TC 39 Z9 39 U1 1 U2 1 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0035-8711 EI 1365-2966 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD MAY 1 PY 2001 VL 323 IS 1 BP 84 EP 92 DI 10.1046/j.1365-8711.2001.04099.x PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 434JE UT WOS:000168810700011 ER PT J AU Bauschlicher, CW AF Bauschlicher, CW TI High coverages of hydrogen on a (10,0) carbon nanotube SO NANO LETTERS LA English DT Article ID GEOMETRY OPTIMIZATION; MOLECULAR MECHANICS; ADSORPTION; ENERGY AB The binding energy of H to a (10,0) carbon nanotube is calculated at 24, 50, and 100% coverage using the AM1 and ONIOM approaches. Several different bonding configurations are considered for the 50% coverage case. Using the ONIOM approach, the average C-H bond energy for the most stable 50% coverage and for the 100% coverage are 57.3 and 38.6 kcal/mol, respectively. Considering the size of the bond energy of H-2, these values suggest that it will be difficult to achieve 100% atomic H coverage on a (10,0) nanotube. The 50% coverage, which appears favorable, corresponds to about 4% by weight storage of H. 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 20 TC 101 Z9 102 U1 0 U2 3 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 MAY PY 2001 VL 1 IS 5 BP 223 EP 226 DI 10.1021/nl010018n PG 4 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 519JA UT WOS:000173721000001 ER PT J AU Powell, CA Sullivan, BM AF Powell, CA Sullivan, BM TI Subjective response to propeller airplane interior sounds modified by hypothetical active noise control systems SO NOISE CONTROL ENGINEERING JOURNAL LA English DT Article AB Active noise control technology offers the potential for weight-efficient aircraft interior noise reduction, particularly for propeller aircraft. However, there is little information on how passengers respond to interior sounds resulting from this type of noise control. This paper presents results of two experiments that use sound quality engineering practices to determine the subjective effectiveness of hypothetical active noise control (ANC) systems in a range of propeller aircraft. The two experiments differed in the type of judgments made by the subjects: pair comparisons based on preference in the first and numerical category scaling of noisiness in the second. Although the results of the two experiments were in general agreement that the hypothetical active control measures improved the interior noise environments, the pair comparison method appears to be more sensitive to subtle changes in the characteristics of the sounds which are related to passenger preference. The reductions in subjective response due to the ANC conditions were predicted with reasonable accuracy by reductions in measured loudness level. Inclusion of corrections for the sound quality characteristics of tonality and fluctuation strength in multiple regression models slightly improved the prediction of the ANC effects. (C) 2001 Institute of Noise Control Engineering. C1 NASA, Langley Res Ctr, Aerodynam Aerothermodynam & Acoust Competency, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Struct Acoust Branch, Hampton, VA 23681 USA. RP Powell, CA (reprint author), NASA, Langley Res Ctr, Aerodynam Aerothermodynam & Acoust Competency, Mail Stop 285, Hampton, VA 23681 USA. NR 14 TC 6 Z9 6 U1 0 U2 4 PU INST NOISE CONTROL ENGINEERING PI AMES PA IOWA STATE UNIV, COLLEGE ENGINEERING, 212 MARSTON HALL, AMES, IA 50011-2152 USA SN 0736-2501 J9 NOISE CONTROL ENG J JI Noise Control Eng. J. PD MAY-JUN PY 2001 VL 49 IS 3 BP 125 EP 136 DI 10.3397/1.2839648 PG 12 WC Acoustics; Engineering, Multidisciplinary SC Acoustics; Engineering GA 510VJ UT WOS:000173227700003 ER PT J AU Rielage, K Arisaka, K Atac, M Binns, WR Christl, MJ Dowkontt, P Epstein, JW Hink, PL Israel, MH Leopold, D Pendleton, GN Wallace, DB AF Rielage, K Arisaka, K Atac, M Binns, WR Christl, MJ Dowkontt, P Epstein, JW Hink, PL Israel, MH Leopold, D Pendleton, GN Wallace, DB TI Characterization of a multianode photomultiplier tube for use with scintillating fibers SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article DE multianode photomultiplier; scintillating fiber ID READOUT; TRACKER; PERFORMANCE; DETECTOR; ARRAY; PMT AB The characteristics of a multianode photomultiplier tube (MAPMT; Hamamatsu R5900-00-M64) with 64 anodes have been studied. We report measurements that include single photoelectron sensitivity, electrical and optical crosstalk, dark count, and gain variation. Environmental test results relevant to use of these devices in space are also presented. The characteristics of the MAPMT make it well suited for detection of light from scintillating fibers as well as other applications. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Washington Univ, Dept Phys, St Louis, MO 63130 USA. Washington Univ, McDonnell Ctr Space Sci, St Louis, MO 63130 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. RP Rielage, K (reprint author), Washington Univ, Dept Phys, 1 Brookings Dr, St Louis, MO 63130 USA. NR 17 TC 11 Z9 12 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 MAY 1 PY 2001 VL 463 IS 1-2 BP 149 EP 160 DI 10.1016/S0168-9002(01)00448-X PG 12 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 435HK UT WOS:000168871200014 ER PT J AU Bergstrom, D Boezio, M Carlson, P Francke, T Grinstein, S Weber, N Suffert, M Hof, M Kremer, J Menn, W Simon, M Stephens, SA Ambriola, M Bellotti, R Cafagna, F Castellano, M Ciacio, F Circella, M De Marzo, C Finetti, N Papini, P Piccardi, S Spillantini, P Bartalucci, S Ricci, M Bidoli, V Casolino, M De Pascale, MP Morselli, A Picozza, P Sparvoli, R Barbiellini, G Schiavon, P Vacchi, A Zampa, N Mitchell, JW Ormes, JF Streitmatter, RE Bravar, U Stochaj, SJ AF Bergstrom, D Boezio, M Carlson, P Francke, T Grinstein, S Weber, N Suffert, M Hof, M Kremer, J Menn, W Simon, M Stephens, SA Ambriola, M Bellotti, R Cafagna, F Castellano, M Ciacio, F Circella, M De Marzo, C Finetti, N Papini, P Piccardi, S Spillantini, P Bartalucci, S Ricci, M Bidoli, V Casolino, M De Pascale, MP Morselli, A Picozza, P Sparvoli, R Barbiellini, G Schiavon, P Vacchi, A Zampa, N Mitchell, JW Ormes, JF Streitmatter, RE Bravar, U Stochaj, SJ TI Performance of the CAPRICE98 balloon-borne gas-RICH detector SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article DE Cherenkov detector; balloon instrumentation; cosmic rays ID COSMIC-RAY; MAGNETIC SPECTROMETER AB A RICK counter using a gas radiator of C4F10 and a photosensitive MWPC with pad readout has been developed, tested in particle beam at CERN and used in the CAPRICE98 balloon-borne experiment. The MWPC was operated with a TMAE and ethane mixture at atmospheric pressure and used a cathode pad plane to give an unambiguous image of the Cherenkov light. The induced signals in the pad plane were read out using the AMPLEX chip and CRAMS. The good efficiency of the Cherenkov light collection, the efficient detection of the weak signal from single UV photons together with a low noise level in the electronics of the RICH detector, resulted in a large number of detected photoelectrons per event. For beta similar or equal to 1 charge one particles, an average of 12 photoelectrons per event were detected. The reconstructed Cherenkov angle of 50 mrad for a beta similar or equal to 1 particle had a resolution of 1.2 mrad (rms). The RICH was flown with the CAPRICE98 magnetic spectrometer and was the first RICH counter ever used in a balloon-borne experiment capable of identifying charge one particles at energies above 5 GeV. The RICH provided an identification of cosmic ray antiprotons up to the highest energies ever studied (about 50 GeV of total energy). The spectrometer was flown on 28-29 May 1998 from Fort Summer, New Mexico, USA. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Royal Inst Technol, Stockholm, Sweden. Ctr Rech Nucl, Strasbourg, France. Univ Siegen, D-5900 Siegen, Germany. Tata Inst Fundamental Res, Bombay 400005, Maharashtra, India. Univ Bari, INFN Sect, Bari, Italy. Univ Bari, Dept Phys, Bari, Italy. Univ Florence, INFN Sect, Florence, Italy. Univ Florence, Dept Phys, Florence, Italy. INFN Frascati, Nazl Frascati Lab, Frascati, Italy. Univ Roma Tor Vergata, INFN Sect, Rome, Italy. Univ Roma Tor Vergata, Dept Phys, Rome, Italy. Univ Trieste, INFN Sect, Trieste, Italy. Univ Trieste, Dept Phys, Trieste, Italy. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. New Mexico State Univ, Las Cruces, NM USA. RP Bergstrom, D (reprint author), Royal Inst Technol, Stockholm, Sweden. RI Morselli, Aldo/G-6769-2011; Castellano, Marcello/J-3428-2012; Cafagna, Francesco/A-9299-2010; Vacchi, Andrea/C-1291-2010; OI Morselli, Aldo/0000-0002-7704-9553; Castellano, Marcello/0000-0002-4211-2903; Cafagna, Francesco/0000-0002-7450-4784; Vacchi, Andrea/0000-0003-3855-5856; Bellotti, Roberto/0000-0003-3198-2708; casolino, marco/0000-0001-6067-5104; Sparvoli, Roberta/0000-0002-6314-6117; Picozza, Piergiorgio/0000-0002-7986-3321; Papini, Paolo/0000-0003-4718-2895; Boezio, Mirko/0000-0002-8015-2981 NR 20 TC 8 Z9 8 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 MAY 1 PY 2001 VL 463 IS 1-2 BP 161 EP 174 DI 10.1016/S0168-9002(01)00202-9 PG 14 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 435HK UT WOS:000168871200015 ER PT J AU Cullings, KW Vogler, DR Parker, VT Makhija, S AF Cullings, KW Vogler, DR Parker, VT Makhija, S TI Defoliation effects on the ectomycorrhizal community of a mixed Pinus contorta/Picea engelmannii stand in Yellowstone Park SO OECOLOGIA LA English DT Article DE community ecology; Ectomycorrhizae; ITS-RFLP; PCR; Yellowstone ID ELEVATED ATMOSPHERIC CO2; MYCORRHIZAL COLONIZATION; PINYON PINES; ENVIRONMENTAL-STRESS; SEQUENCE DATABASE; NITROGEN; FOREST; FUNGAL; IDENTIFICATION; ACQUISITION AB Molecular genetic methods were used to determine whether artificial defoliation affects ectomycorrhizal (EM) colonization, EM fungal species richness, and species composition in a mixed Pinus contorta (lodgepole pine)/Picea engelmannii (Engelmann spruce) forest in Yellowstone National Park, Wyoming. All lodgepole pines in three replicate plots were defoliated 50%, while Engelmann spruce were left untreated. This was done to determine how defoliation of one conifer species would affect EM mutualisms of both treated and neighboring, untreated conifers. The results indicated no significant effect on either EM colonization (142.0 EM tips/core in control plots and 142.4 in treatment plots) or species richness (5.0 species/core in controls and 4.5 in treatments). However, the relative abundance of EM of the two tree species shifted from a ratio of approximately 6:1 without treatment (lodgepole EM:spruce EM), to a near 1:1 ratio post-treatment. This shift may be responsible for maintaining total EM colonization and species richness following defoliation. In addition, EM species composition changed significantly post-defoliation; the system dominant, an Inocybe species, was rare in defoliation plots, while Agaricoid and Suilloid species that were rare in controls were dominant in treatments. Furthermore, species of EM fungi associating with both lodgepole pine and Engelmann spruce were affected, which indicates that changing the photosynthetic capacity of one species can affect mycorrhizal associations of neighboring non-defoliated trees. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. USDA, Forest Serv, Inst Forest Genet, Davis, CA 95616 USA. San Francisco State Univ, Dept Biol, San Francisco, CA 94132 USA. RP Cullings, KW (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 35 TC 31 Z9 32 U1 2 U2 18 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0029-8549 J9 OECOLOGIA JI Oecologia PD MAY PY 2001 VL 127 IS 4 BP 533 EP 539 DI 10.1007/s004420000610 PG 7 WC Ecology SC Environmental Sciences & Ecology GA 440YK UT WOS:000169204100010 ER PT J AU Milstein, A Monroe, SE Juday, RD AF Milstein, A Monroe, SE Juday, RD TI Optimal region of support for arbitrary filter spatial light modulators SO OPTICAL ENGINEERING LA English DT Article DE spatial light modulators; optimal filters; optical correlation; pattern recognition ID SIGNAL; NOISE AB When only certain filter pixels in a spatial light modulator (SLM) are allowed to transmit light, those "on" pixels constitute the region of support (ROS) for the filter. At the frequencies where noise power overwhelms signal power, or where the available values of the filter are not well aligned with the ideal spectral filter, the filter can actually work against the intent of the metric, and zero transmittance is preferable to what the SLM can do. In contrast to prior theories, which applied to only unit-magnitude filters, we present algorithms for optimizing and studying ROS for an arbitrary SLM. We also present laboratory demonstrations of improvement in signal-to-noise ratio when a blocking mask is inserted into an optical correlator. A mask has detailed functional dependence on the signal, the noise power spectral density, the selected metric, and the realizable filter values. Broadly useful rules are given for designing a mask. Conjecture is offered that it could be beneficial to build a permanent ROS into SLMs. (C) 2001 Society of Photo-Optical Instrumentation Engineers. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin Space Mission Syst & Serv, Houston, TX 77058 USA. RP NASA, Lyndon B Johnson Space Ctr, Mail Code ER5, Houston, TX 77058 USA. EM juday@jsc.nasa.gov NR 8 TC 1 Z9 1 U1 0 U2 0 PU SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98225 USA SN 0091-3286 EI 1560-2303 J9 OPT ENG JI Opt. Eng. PD MAY PY 2001 VL 40 IS 5 BP 841 EP 850 DI 10.1117/1.1356707 PG 10 WC Optics SC Optics GA 436QF UT WOS:000168946000030 ER PT J AU Cerf, NJ Levy, M Van Assche, G AF Cerf, NJ Levy, M Van Assche, G TI Quantum distribution of Gaussian keys using squeezed states SO PHYSICAL REVIEW A LA English DT Article ID ENTANGLED PHOTONS; BELL THEOREM; CRYPTOGRAPHY; INFORMATION; VARIABLES; PROTOCOL; CLONING AB A continuous key-distribution scheme is proposed that relies on a pair of conjugate quautum variables. It allows two remote Parties to share a secret Gaussian key try encoding it into one of the two quadrature components of a single-mode electromagnetic field. The resulting quantum cryptographic information versus disturbance trade-off is investigated for an individual attack based on the optimal continuous cloning machine. It is shown that the information gained by the eavesdropper then simply equals the information lost by the receiver. C1 Free Univ Brussels, Ecole Polytech, CP 165, 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 24 TC 141 Z9 143 U1 1 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 MAY PY 2001 VL 63 IS 5 AR 052311 DI 10.1103/PhysRevA.63.052311 PG 5 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 430RJ UT WOS:000168589100039 ER PT J AU Massar, S Bacon, D Cerf, NJ Cleve, R AF Massar, S Bacon, D Cerf, NJ Cleve, R TI Classical simulation of quantum entanglement without local hidden variables SO PHYSICAL REVIEW A LA English DT Article ID COMMUNICATION; BIT AB Recent work has extended Bell's theorem by quantifying the amount of communication required to simulate entangled quantum systems with classical information. The general scenario is that a bipartite measurement is given from a set of possibilities and the goal is to find a classical scheme that reproduces exactly the conclusions that arise when an actual quantum system is measured. Previous results have shown that. using local hidden variables, a finite amount of communication suffices to simulate the correlations for a Bell state. We extend this in a number of ways. First, we show that, when the communication is merely required to be finite on average, Bell states can be simulated without any local hidden variables. More generally, we show that arbitrary positive operator valued measurements on systems of n Bell states call be simulated with O(n2") bits of communication on average (again, without local hidden variables). On the other hand, when the communication is required to be absolutely bounded, we show that a finite number of bits of local hidden variables is insufficient to simulate a Bell state. This latter result is based on an analysis of the nondeterministic communication complexity of the NOT-EQUAL function, which is constant in the quantum model and logarithmic in the classical model. C1 Free Univ Brussels, Serv Phys Theor, CP 225, B-1050 Brussels, Belgium. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94704 USA. Univ Calif Berkeley, Dept Chem, Berkeley, CA 94704 USA. Free Univ Brussels, Ecole Polytech, CP 165, B-1050 Brussels, Belgium. CALTECH, Jet Prop Lab, Informat & Comp Technol Res Sect, Pasadena, CA 91109 USA. Univ Calgary, Dept Comp Sci, Calgary, AB T2N 1N4, Canada. RP Free Univ Brussels, Serv Phys Theor, CP 225, B-1050 Brussels, Belgium. RI Bacon, Dave/A-3112-2008 NR 9 TC 45 Z9 45 U1 0 U2 1 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 MAY PY 2001 VL 63 IS 5 AR 052305 DI 10.1103/PhysRevA.63.052305 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 430RJ UT WOS:000168589100033 ER PT J AU Hahn, I Zhong, F Barmatz, M Haussmann, R Rudnick, J AF Hahn, I Zhong, F Barmatz, M Haussmann, R Rudnick, J TI Crossover behavior in the isothermal susceptibility near the He-3 critical point SO PHYSICAL REVIEW E LA English DT Article ID VAPOR CRITICAL-POINT; GAS CRITICAL-POINT; MINIMAL RENORMALIZATION; CRITICAL EXPONENTS; EPSILON-EXPANSION; 3 DIMENSIONS; ISING-LIKE; FLUIDS AB We present high-resolution measurements of the isothermal susceptibility of pure He-3 near the liquid-gas critical point. PVT measurements were performed in the single-phase region over the reduced temperature range 3 x 10(-5) < T/T-c - 1 < 1.5 X 10(-1). The crossover behavior of the susceptibility along the critical isochore was analyzed using a field-theoretical renormalization-group calculation based on the phi (4) model. A similar crossover analysis was performed on previously obtained Xe susceptibility measurements. A comparison of the rescaled susceptibility for He-3 and Xe shows theoretically predicted universal crossover behavior. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Gottingen, Inst Theoret Phys, D-37073 Gottingen, Germany. Univ Calif Los Angeles, Dept Phys, Los Angeles, CA 90095 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 21 TC 13 Z9 13 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 MAY PY 2001 VL 63 IS 5 AR 055104 DI 10.1103/PhysRevE.63.055104 PN 2 PG 4 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA 432ZL UT WOS:000168730800004 PM 11414949 ER PT J AU Winckelmans, GS Wray, AA Vasilyev, OV Jeanmart, H AF Winckelmans, GS Wray, AA Vasilyev, OV Jeanmart, H TI Explicit-filtering large-eddy simulation using the tensor-diffusivity model supplemented by a dynamic Smagorinsky term SO PHYSICS OF FLUIDS LA English DT Article ID FINITE-DIFFERENCE SCHEMES; TURBULENT FLOWS; SCALE MODELS; MIXING LAYER; REPRESENTATION AB Large-eddy simulation (LES) with regular explicit filtering is investigated. The filtered-scale stress due to the explicit filtering is here partially reconstructed using the tensor-diffusivity model: It provides for backscatter along the stretching direction(s), and for global dissipation, both also attributes of the exact filtered-scale stress. The necessary LES truncations (grid and numerical method) are responsible for an additional subgrid-scale stress. A natural mixed model is then the tensor-diffusivity model supplemented by a dynamic Smagorinsky term. This model is reviewed, together with useful connections to other models, and is tested against direct numerical simulation (DNS) of turbulent isotropic decay starting with Re-lambda=90 (thus moderate Reynolds number): LES started from a 256(3) DNS truncated to 64(3) and Gaussian filtered. The tensor-diffusivity part is first tested alone; the mixed model is tested next. Diagnostics include energy decay, enstrophy decay, and energy spectra. After an initial transient of the dynamic procedure (observed with all models), the mixed model is found to produce good results. However, despite expectations based on favorable a priori tests, the results are similar to those obtained when using the dynamic Smagorinsky model alone in LES without explicit filtering. Nevertheless, the dynamic mixed model appears as a good compromise between partial reconstruction of the filtered-scale stress and modeling of the truncations effects (incomplete reconstruction and subgrid-scale effects). More challenging 48(3) LES are also done: Again, the results of both approaches are found to be similar. The dynamic mixed model is also tested on the turbulent channel flow at Re-tau=395. The tensor-diffusivity part must be damped close to the wall in order to avoid instabilities. Diagnostics are mean profiles of velocity, stress, dissipation, and reconstructed Reynolds stresses. The velocity profile obtained using the damped dynamic mixed model is slightly better than that obtained using the dynamic Smagorinsky model without explicit filtering. The damping used so far is however crude, and this calls for further work. (C) 2001 American Institute of Physics. C1 Univ Catholique Louvain, Dept Mech Engn, CESAME, B-1348 Louvain, Belgium. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Missouri, Columbia, MO 65211 USA. RP Winckelmans, GS (reprint author), Univ Catholique Louvain, Dept Mech Engn, CESAME, B-1348 Louvain, Belgium. RI Vasilyev, Oleg/H-5597-2016 OI Vasilyev, Oleg/0000-0003-0294-6097 NR 44 TC 99 Z9 99 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD MAY PY 2001 VL 13 IS 5 BP 1385 EP 1403 DI 10.1063/1.1360192 PG 19 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 420ZU UT WOS:000168037200026 ER PT J AU Holbrook, NM Ahrens, ET Burns, MJ Zwieniecki, MA AF Holbrook, NM Ahrens, ET Burns, MJ Zwieniecki, MA TI In vivo observation of cavitation and embolism repair using magnetic resonance imaging SO PLANT PHYSIOLOGY LA English DT Article ID XYLEM VESSELS; WATER-FLOW; PLANTS; VULNERABILITY; STEMS; MAIZE; NEED AB Magnetic resonance imaging (MRI) was used to noninvasively monitor the status of individual xylem vessels in the stem of an intact, transpiring grape (Vitis vinifera) plant over a period of approximately 40 h. Proton density-weighted MRI was used to visualize the distribution of mobile water in the stem and individual xylem vessels were scored as either water or gas filled (i.e. embolized). The number of water-filled vessels decreased during the first 24 h of the experiment, indicating that approximately 10 vessels had cavitated during this time. Leaf water potentials decreased from -1.25 to -2.1 MPa during the same period. Watering increased leaf water potentials to -0.25 MPa and prevented any further cavitation. Refilling of xylem vessels occurred as soon as the lights were switched off, with the majority of vessels becoming refilled with water during the first 2 to 3 h in darkness. These measurements demonstrate that MRI can be used to monitor the functional status of individual xylem vessels, providing the first method to study the process of cavitation and embolism repair in intact plants. C1 Harvard Univ, Dept Organism & Evolutionary Biol, Cambridge, MA 02138 USA. Carnegie Mellon Univ, Dept Biol Sci, Pittsburgh, PA 15213 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Holbrook, NM (reprint author), Harvard Univ, Dept Organism & Evolutionary Biol, Cambridge, MA 02138 USA. RI Zwieniecki, Maciej/D-3078-2011; Burns, Michael/D-2939-2011 OI Burns, Michael/0000-0001-9804-405X FU NCRR NIH HHS [RR13625]; NIDA NIH HHS [DA08944]; NIMH NIH HHS [MH61223] NR 21 TC 145 Z9 157 U1 8 U2 41 PU AMER SOC PLANT PHYSIOLOGISTS PI ROCKVILLE PA 15501 MONONA DRIVE, ROCKVILLE, MD 20855 USA SN 0032-0889 J9 PLANT PHYSIOL JI Plant Physiol. PD MAY PY 2001 VL 126 IS 1 BP 27 EP 31 DI 10.1104/pp.126.1.27 PG 5 WC Plant Sciences SC Plant Sciences GA 432LD UT WOS:000168692300009 PM 11351066 ER PT J AU Kim, JS Rao, MVVS Cappelli, MA Sharma, SP Meyyappan, M AF Kim, JS Rao, MVVS Cappelli, MA Sharma, SP Meyyappan, M TI Mass spectrometric and Langmuir probe measurements in inductively coupled plasmas in Ar, CHF3/As and CHF3/Ar/O-2 mixtures SO PLASMA SOURCES SCIENCE & TECHNOLOGY LA English DT Article ID CYCLOTRON-RESONANCE PLASMA; FLUOROCARBON PLASMAS; ELECTRON-DENSITY; GLOW-DISCHARGE; ION ENERGY; SILICON; SIO2; SPECTROSCOPY; MECHANISMS; CHEMISTRY AB Absolute fluxes and energy distributions of ions in inductively coupled plasmas of Ar, CHF3/Ar, and CHF3/Ar/O-2 have been measured. These plasmas were generated in a gaseous electronics conference cell modified for inductive coupling at pressures of 10-50 mTorr and 100-300 W of 13.56 MHz radio frequency (RF) power in various feed gas mixtures. In pure Ar plasmas, the Ar+ flux increases linearly with pressure as well as RF power. In mixtures, the Ar+ flux decreases with increase in pressure and CHF3 concentration in the mixture. The loss mechanism for Ar+ is attributed to resonance charge exchange (Ar+ + CHF3 --> products). Total ion flux in CHF3 mixtures decreases with increase in pressure and also CHF3 concentration. Relative ion fluxes observed in the present studies are analysed with the help of available cross sections for electron impact ionization and charge-exchange ion-molecule reactions. Measurements of plasma potential, electron and ion number densities, electron energy distribution function, and mean electron energy have also been made in the centre of the plasma with an RE-compensated Langmuir probe. Plasma potential values are compared with the mean ion energies determined from the measured ion energy distributions and art consistent. Electron temperature, plasma potential, and mean ion energy vary inversely with pressure, but increase with CHF3 content in the mixture. C1 NASA, Ames Res Ctr, Plasma Res Lab, Moffett Field, CA 94035 USA. Stanford Univ, Dept Mech Engn, Stanford, CA 94305 USA. RP Rao, MVVS (reprint author), NASA, Ames Res Ctr, Plasma Res Lab, Moffett Field, CA 94035 USA. NR 42 TC 31 Z9 31 U1 1 U2 5 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 MAY PY 2001 VL 10 IS 2 BP 191 EP 204 DI 10.1088/0963-0252/10/2/309 PG 14 WC Physics, Fluids & Plasmas SC Physics GA 441YY UT WOS:000169258200009 ER PT J AU Martin, EL Brandner, W Jewitt, DC Simon, T Wainscoat, R Connelley, M Marley, M Gelino, C AF Martin, EL Brandner, W Jewitt, DC Simon, T Wainscoat, R Connelley, M Marley, M Gelino, C TI Probing the substellar regime with SIRTF SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID LOW-MASS STARS; EXTRASOLAR GIANT PLANETS; TELESCOPE-FACILITY SIRTF; BROWN DWARFS; CLUSTER; MODELS; YOUNG; EVOLUTIONARY; COMPANION; DISCOVERY AB One of the main scientific drivers of the Space Infrared Telescope Facility (SIRTF) is the search for brown dwarfs and extrasolar superplanets. We present new calculations of the spectra of substellar objects and a prediction of their colors in the SIRTF passbands. We discuss observational strategies for identification of very low mass objects as free-floaters in the solar vicinity and provide estimates of their densities as a function of sensitivity and the mass function. C1 Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. New Mexico State Univ, Dept Astron, Las Cruces, NM 88003 USA. RP Martin, EL (reprint author), Univ Hawaii, Inst Astron, 2680 Woodlawn Dr, Honolulu, HI 96822 USA. RI Marley, Mark/I-4704-2013 NR 36 TC 9 Z9 9 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD MAY PY 2001 VL 113 IS 783 BP 529 EP 536 DI 10.1086/320285 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 427QF UT WOS:000168416400003 ER PT J AU Stark, AA Bally, J Balm, SP Bania, TM Bolatto, AD Chamberlin, RA Engargiola, G Huang, M Ingalls, JG Jacobs, K Jackson, JM Kooi, JW Lane, AP Lo, KY Marks, RD Martin, CL Mumma, D Ojha, R Schieder, R Staguhn, J Stutzki, J Walker, CK Wilson, RW Wright, GA Zhang, XL Zimmermann, P Zimmermann, R AF Stark, AA Bally, J Balm, SP Bania, TM Bolatto, AD Chamberlin, RA Engargiola, G Huang, M Ingalls, JG Jacobs, K Jackson, JM Kooi, JW Lane, AP Lo, KY Marks, RD Martin, CL Mumma, D Ojha, R Schieder, R Staguhn, J Stutzki, J Walker, CK Wilson, RW Wright, GA Zhang, XL Zimmermann, P Zimmermann, R TI The Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID 225-GHZ ATMOSPHERIC OPACITY; SOUTH-POLE; MICROWAVE SKY; ANGULAR SCALES; 90 GHZ; ANISOTROPY; RECEIVER; MIXERS; INTERFEROMETER; CALIBRATION AB The Antarctic Submillimeter Telescope and Remote Observatory, a 1.7 m diameter telescope for astronomy and aeronomy studies at wavelengths between 200 and 2000 mum, was installed at the South Pole during the 1994-1995 austral summer. The telescope operates continuously through the austral winter and is being used primarily for spectroscopic studies of neutral atomic carbon and carbon monoxide in the interstellar medium of the Milky Way and the Magellanic Clouds. The South Pole environment is unique among observatory sites for unusually low wind speeds, low absolute humidity, and the consistent clarity of the submillimeter sky. Especially significant are the exceptionally low values of sky noise found at this site, a result of the small water vapor content of the atmosphere. Four heterodyne receivers, an array receiver, three acousto-optical spectrometers, and an array spectrometer are currently installed. A Fabry-Perot spectrometer using a bolometric array and a terahertz receiver are in development. Telescope pointing, focus, and calibration methods as well as the unique working environment and logistical requirements of the South Pole are described. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Bell Labs, Holmdel, NJ 07733 USA. Univ Colorado, CASA, Boulder, CO 80309 USA. Boston Univ, Boston, MA 02215 USA. CALTECH Submillimeter Observ, Hilo, HI 96720 USA. Univ Illinois, Urbana, IL 61801 USA. Univ Calif Berkeley, Radio Astron Lab, Berkeley, CA 94720 USA. CALTECH, Pasadena, CA 91125 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. Radiometer Phys GmbH, D-53340 Meckenheim, Germany. RP Stark, AA (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. EM aas@cfa.harvard.edu; greg@astron.berkeley.edu; adair@cfa.harvard.edu; cmartin@cfa.harvard.edu; staguhn@stars.gsfc.nasa.gov; zhang@stars.gsfc.nasa.gov RI Bania, Thomas/H-2318-2014; OI Wilson, Robert/0000-0001-5694-6725 NR 51 TC 61 Z9 61 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD MAY PY 2001 VL 113 IS 783 BP 567 EP 585 DI 10.1086/320281 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 427QF UT WOS:000168416400007 ER PT J AU Ryutova, M Habbal, S Woo, R Tarbell, T AF Ryutova, M Habbal, S Woo, R Tarbell, T TI Photospheric network as the energy source for the quiet-Sun corona SO SOLAR PHYSICS LA English DT Article ID SOLAR-WIND; TRANSITION REGION; SCALE STRUCTURES; ATMOSPHERE; FLOW AB We propose a mechanism for the formation of a magnetic energy avalanche based on highly dynamic phenomena within the ubiquitous small-scale network magnetic elements in the quiet photosphere. We suggest that this mechanism may provide constant mass and energy supply for the corona and fast wind. Constantly emerging from sub-surface layers, flux tubes collide and reconnect generating magneto-hydrodynamic shocks that experience strong gradient acceleration in the sharply stratified photosphere/chromosphere region. Acoustic and fast magnetosonic branches of these waves lead to heating and/or jet formation due to cumulative effects (Tarbell et al., 1999). The Alfven waves generated by post-reconnection processes have quite a restricted range of parameters for shock formation, but their frequency, determined by the reconnection rate, may be high enough (omega similar or equal to 0.1-2.5 s(-1)) to carry the energy into the corona. We also suggest that the primary energy source for the fast wind lies far below the coronal heights, and that the chromosphere and transition region flows and also radiative transient form the base of the fast wind. The continuous supply of emerging magnetic flux tubes provides a permanent energy production process capable of explaining the steady character of the fast wind and its energetics. C1 Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94550 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Lockheed Martin Solar & Astrophys Lab, Palo Alto, CA 94304 USA. RP Ryutova, M (reprint author), Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94550 USA. EM ryutova@beowulf.ucllnl.org; habbal@cfassp31.harvard.edu; rwoo@mail1.jpl.nasa.gov; tarbell@lmsal.com NR 28 TC 27 Z9 27 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD MAY PY 2001 VL 200 IS 1-2 BP 213 EP 234 DI 10.1023/A:1010374005082 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 456DK UT WOS:000170067700016 ER PT J AU Rodell, M Famiglietti, JS AF Rodell, M Famiglietti, JS TI An analysis of terrestrial water storage variations in Illinois with implications for the Gravity Recovery and Climate Experiment (GRACE) SO WATER RESOURCES RESEARCH LA English DT Article ID FIELD; LEVEL AB Variations in terrestrial water storage affect weather, climate, geophysical phenomena, and life on land, yet observation and understanding of terrestrial water storage are deficient. However, estimates of terrestrial water storage changes soon may be derived from observations of Earth's time-dependent gravity field made by NASA's Gravity Recovery and Climate Experiment (GRACE). Previous studies have evaluated that concept using modeled soil moisture and snow data. This investigation builds upon their results by relying on observations rather than modeled results, by analyzing groundwater and surface water variations as well as snow and soil water variations, and by using a longer time series. Expected uncertainty in GRACE-derived water storage changes are compared to monthly, seasonal, and annual terrestrial water storage changes estimated from observations in Illinois (145,800 km(2)). Assuming those changes are representative of larger regions, detectability is possible given a 200,000 km(2) or larger area. Changes in soil moisture are typically the largest component of terrestrial water storage variations, followed by changes in groundwater plus intermediate zone storage. C1 Univ Texas, Dept Geol Sci, Austin, TX 78712 USA. RP Rodell, M (reprint author), NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Greenbelt, MD 20771 USA. RI Rodell, Matthew/E-4946-2012 OI Rodell, Matthew/0000-0003-0106-7437 NR 25 TC 104 Z9 108 U1 2 U2 18 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0043-1397 J9 WATER RESOUR RES JI Water Resour. Res. PD MAY PY 2001 VL 37 IS 5 BP 1327 EP 1339 DI 10.1029/2000WR900306 PG 13 WC Environmental Sciences; Limnology; Water Resources SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Water Resources GA 425AP UT WOS:000168266400019 ER PT J AU Borodin, O Smith, GD Jaffe, RL AF Borodin, O Smith, GD Jaffe, RL TI Ab initio quantum chemistry and molecular dynamics simulations studies of LiPF6/poly(ethylene oxide) interactions SO JOURNAL OF COMPUTATIONAL CHEMISTRY LA English DT Article DE polymer electrolytes; force field; quantum chemistry; molecular dynamics ID ELECTRONIC-STRUCTURE CALCULATIONS; NUCLEAR-MAGNETIC-RESONANCE; POLYMER ELECTROLYTES; POLY(ETHYLENE OXIDE); FORCE-FIELD; LITHIUM IODIDE; MODEL; POTENTIALS; EXCHANGE; DENSITY AB Ab initio and molecular mechanics studies of LiPF6 and the interaction of the salt with the poly(ethylene oxide) (PEO) oligomer dimethylether have been performed. Optimized geometries and energies of Li+/PF6- complexes obtained from quantum chemistry revealed a preference for C-3V symmetry structures for Li+-P separations under 2.8 Angstrom, C-2V symmetry for Li+-P in the range of 2.8-3.3 Angstrom and C-4V symmetry for Li+-P separations larger than 3.3 Angstrom. Electron correlation effects were found to make an insignificant contribution to binding in the Li+/PF6- complex. By contrast, analogous studies of PF6-/PF6- and PF6-/dimethyl ether complexes revealed important contributions of electron correlation to the complex interaction energy. A molecular mechanics force field for simulations of PEO/LiPF6 melts was parameterized to reproduce the geometries and energies of Li+/PF6-, PF6-/PF6-, PF6-/dimethylether complexes. Molecular dynamics simulations of PEO/LiPF6 melts were performed to validate this quantum chemistry-based force field. Accurate reproduction of the increase in solution density with addition of salt was found while the electrical conductivity of PEO/LiPF6 solutions was found to be within an order of magnitude of the experimental values. (C) 2001 John Wiley & Sons, Inc. C1 Univ Utah, Dept Mat Sci & Engn, Salt Lake City, UT 84112 USA. Univ Utah, Dept Chem & Fuels Engn, Salt Lake City, UT 84112 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Borodin, O (reprint author), Univ Utah, Dept Mat Sci & Engn, 122 S Cent Campus Dr,Rm 304, Salt Lake City, UT 84112 USA. RI Borodin, Oleg/B-6855-2012 OI Borodin, Oleg/0000-0002-9428-5291 NR 49 TC 53 Z9 53 U1 3 U2 22 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 USA SN 0192-8651 J9 J COMPUT CHEM JI J. Comput. Chem. PD APR 30 PY 2001 VL 22 IS 6 BP 641 EP 654 DI 10.1002/jcc.1033 PG 14 WC Chemistry, Multidisciplinary SC Chemistry GA 418FC UT WOS:000167879400005 ER PT J AU Shindell, DT Grenfell, JL Rind, D Grewe, V Price, C AF Shindell, DT Grenfell, JL Rind, D Grewe, V Price, C TI Chemistry-climate interactions in the Goddard Institute for Space Studies general circulation model 1. Tropospheric chemistry model description and evaluation SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CHEMICAL-TRANSPORT MODEL; GLOBAL SIMULATION; CARBON-MONOXIDE; ANTHROPOGENIC EMISSIONS; OZONE PRODUCTION; NITROGEN-OXIDES; DIAGNOSTIC-TOOL; ONLINE TRACERS; NORTH-ATLANTIC; FUTURE CHANGES AB A tropospheric chemistry model has been developed within the Goddard Institute for Space Studies general circulation model (GCM) to study interactions between chemistry and climate change. The model uses simplified chemistry based on CO-NO(x)-HO(x)-O(x)-CH(4) and also includes a parameterization for isoprene emissions, the most important non-methane hydrocarbon. The model reproduces observed annual cycles and mean distributions of key trace gases fairly well. It simulates preindustrial to present-day changes similar to those seen in other simulations. For example, the global tropospheric ozone burden increases 45%, within the 25% - 57% range of other studies. Annual average zonal mean surface ozone increases more than 125% at northern midlatitudes. Comparison between runs that allow calculated ozone to interact with the GCM and those that do not shows only minor ozone differences. The common usage of non-interactive ozone seems adequate to simulate ozone distributions. However, use of coupled chemistry does alter the tropospheric oxidation capacity, enlarging the preindustrial to present-day OH decrease by about 10% (-5.3% global annual average uncoupled, -5.9% coupled). Thus simulation of changes in oxidation capacity may be systematically biased (though a 10% difference is within the uncertainty). Global annual average radiative forcing from preindustrial to present-day ozone change is 0.32 W m(-2). The forcing p m tn increase by similar to 10% with coupled chemistry. Forcing greater than 0.8 W m(-2) is seen over the United States, the Mediterranean area, central Asia, and the Arctic, with values greater than 1.5 W m(-2) over parts of these areas during summer. Though there are local differences, the radiative forcing is overall in good agreement with other modeling studies in both magnitude and spatial distribution, demonstrating that the simplified chemistry is adequate for climate studies. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Tel Aviv Univ, Dept Geophys & Planetary Sci, IL-69978 Tel Aviv, Israel. Columbia Univ, Ctr Climate Syst Res, New York, NY USA. DLR, Inst Phys Atmosphaere, Oberpfaffenhofen, Germany. RP Shindell, DT (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM dshindell@giss.nasa.gov RI Shindell, Drew/D-4636-2012; Grewe, Volker/A-6147-2011 OI Grewe, Volker/0000-0002-8012-6783 NR 68 TC 47 Z9 49 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-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 2001 VL 106 IS D8 BP 8047 EP 8075 DI 10.1029/2000JD900704 PG 29 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 427ZW UT WOS:000168437500019 ER PT J AU Nielsen, JE Douglass, AR AF Nielsen, JE Douglass, AR TI Simulation of bromoform's contribution to stratospheric bromine SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LOWERMOST STRATOSPHERE; ORGANIC-COMPOUNDS; 3-DIMENSIONAL SIMULATION; 2-DIMENSIONAL MODEL; ANNUAL CYCLE; WATER-VAPOR; TRANSPORT; TROPOSPHERE; OZONE; CO2 AB The chlorine and bromine that are contained in gases emitted at the Earth's surface enter the stratosphere in two ways. First, those gases that are inert in the troposphere may be transported to the stratosphere before they are oxidized or photolyzed. In this case these compounds act as an in situ source of stratospheric reactive chlorine and bromine. Second, the chlorine and bromine that are released into the troposphere from those gases that are reactive in the troposphere may also be subsequently transported to the stratosphere. We evaluate the relative influence of these processes on stratospheric bromine in a three-dimensional chemistry and transport model that simulates the distribution of bromoform (CHBr3). Many of the observed features of CHBr3 are simulated well, and comparisons with observations show that the model represents aspects of transport in the upper troposphere and lower stratosphere that are critical to the evaluation. In particular, the model maintains the observed troposphere-stratosphere distinctness in transport pathways and reproduces the observed seasonal dependence of the mixture of air in the middle- and high-latitude lowermost stratosphere. CHBr3 is short-lived and is destroyed by photolysis and by reaction with hydroxyl (OH): which yields inorganic bromine (Br-y) In our simulations, stratospheric destruction of CHBr3 produces Br-y in amounts that are comparable to that transported into the stratosphere after photolysis and oxidation of CHBr3 in the troposphere. The mass of Br-y produced from the destruction of CHBr3 does not exceed the mass of Br-y produced from the destruction of the long-lived brominated compounds (halons and methyl bromide) globally at any level in the stratosphere. However. Bry from the loss of CHBr3 accounts for approximately one third of the total Br, in the lowest kilometer of the stratosphere. We estimate that adding CHBr3 to models that already include the long-lived organic brominated compounds will increase the simulated stratospheric mass of Br-y by, at most, 15%. C1 Emergent Informat Technol Inc, Largo, MD 20774 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Nielsen, JE (reprint author), Emergent Informat Technol Inc, 9315 Largo Dr W,Suite 250, Largo, MD 20774 USA. RI Douglass, Anne/D-4655-2012 NR 46 TC 39 Z9 40 U1 0 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 2001 VL 106 IS D8 BP 8089 EP 8100 DI 10.1029/2000JD900767 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 427ZW UT WOS:000168437500021 ER PT J AU Kraemer, SB Crenshaw, DM Hutchings, JB George, IM Danks, AC Gull, TR Kaiser, ME Nelson, CH Weistrop, D Vieira, GL AF Kraemer, SB Crenshaw, DM Hutchings, JB George, IM Danks, AC Gull, TR Kaiser, ME Nelson, CH Weistrop, D Vieira, GL TI Space telescope imaging spectrograph echelle observations of the Seyfert galaxy NGC 4151: Physical conditions in the ultraviolet absorbers SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 4151); galaxies : Seyfert; ultraviolet : galaxies ID NARROW-LINE REGION; X-RAY-ABSORPTION; SHORT-TIMESCALE VARIABILITY; LONG-SLIT SPECTROSCOPY; MULTIWAVELENGTH OBSERVATIONS; DETAILED OBSERVATIONS; NGC-4151; BROAD; EMISSION; SPECTRUM AB We have examined the physical conditions in intrinsic UV-absorbing gas in the Seyfert galaxy NGC 4151, using echelle spectra obtained with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope on 1999 July 19. We confirm the presence of the kinematic components detected in earlier Goddard High Resolution Spectrograph (GHRS) observations, all of which appear to be out-flowing from the nucleus, as well as a new broad absorption feature at a radial velocity of -1680 km s(-1). The UV continuum of NGC 4151 was a factor of about 4 lower than in observations taken over the previous 2 yr, and we argue that the changes in the column density of the low-ionization absorption lines associated with the broad component at -490 km s(-1) reflect the decrease in the ionizing flux. Most of the strong absorption lines (e.g., N V, C IV, Si IV, etc.) from this component are saturated but show substantial residual flux in their cores, indicating that the absorber does not fully cover the source of emission. Our interpretation is that the unocculted light is due to scattering by free electrons from an extended region, which reflects continuum, emission lines, and absorption lines. For the first time in such a study, we have been able to constrain the densities for this kinematic component and several others based on the strength of absorption lines from metastable states of C III and Fe II and/or the ratios of ground and fine structure lines of O I, CII, and Si II. We have generated a set of photoionization models that successfully match not only the ionic column densities for each component during the present low-flux state but also those seen in previous high-flux states with the GHRS and STIS, confirming that the absorbers are photoionized and respond to the changes in the continuum flux. Based on the model parameters (ionization parameter and density), we have been able to map the relative radial positions of the absorbers. We find that the absorbing gas decreases in density with distance. Finally, none of the UV absorbers is of sufficiently large column density or high enough ionization state to account for the observed X-ray absorption, while the scatterer is too highly ionized. Hence, the X-ray absorption must arise in a separate component of circumnuclear gas. C1 Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Natl Res Council Canada, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. Univ Maryland, Joint Ctr Astrophys, Baltimore, MD 21250 USA. NASA, Goddard Space Flight Ctr, Raytheon Polar Serv, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Nevada, Dept Phys, Las Vegas, NV 89154 USA. NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. RP Kraemer, SB (reprint author), Catholic Univ Amer, Dept Phys, 200 Hannan Hall, Washington, DC 20064 USA. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 52 TC 62 Z9 62 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 APR 26 PY 2001 VL 551 IS 2 BP 671 EP 686 DI 10.1086/320244 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 427AX UT WOS:000168383600007 ER PT J AU Hollis, JM Churchwell, E AF Hollis, JM Churchwell, E TI Functional molecular groups on interstellar grains SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : molecules; molecular processes ID ORION-KL; LINE SURVEY; DEUTERATED WATER; CLOUDS; GHZ; OMC-1; CORE AB Chemical routes in the synthesis of large interstellar molecules are quite obscure, but interstellar grains are believed to play a significant role. We suggest that functional molecular groups (e.g., OH, CH, CH2, CH3, NH2, etc.) on grain surfaces may provide the precursor basis for ensuing grain chemistries that produce complex molecules. Herein we report a first attempt to determine the relative abundance ratios of molecular groups toward the Galactic center and the Orion Nebula by using previously reported gasphase abundances of complex molecules observed with single antennas having arcminute resolutions. Specifically, for SgrB2(OH), which is an extended cloud possessing no concentrated molecular core, we obtain OH:CH3:CH2:CH:NH2:HCO:CN similar to 4190:100:29:71:36:57:178, and for OMC-1 we obtain OH:CH3:CH:NH2:HCO similar to [4040-8080]:100:36:25:[83-167], where both sets of relative abundances are normalized to the CH3 group. We suggest that these ratios may represent the relative abundance of the functional molecular groups on grain surfaces where the molecules were formed and subsequently released into the gas phase. We find that the relative functional group ratios in SgrB2 and OMC-1 are similar based on single-antenna beam-averaged abundances. We predict that higher spatial resolution (i.e., better beam-source coupling, as afforded by interferometric arrays) should be able to establish the role of functional molecular groups on grain surfaces in more compact interstellar molecular environments possessing a variety of different physical conditions. C1 NASA, Goddard Space Flight Ctr, Earth & Space Data Comp Div, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Univ Wisconsin, Washburn Observ, Madison, WI 53706 USA. RP Hollis, JM (reprint author), NASA, Goddard Space Flight Ctr, Earth & Space Data Comp Div, Code 930, Greenbelt, MD 20771 USA. NR 21 TC 11 Z9 11 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 APR 26 PY 2001 VL 551 IS 2 BP 803 EP 806 DI 10.1086/320214 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 427AX UT WOS:000168383600017 ER PT J AU Mukai, K Ishida, M AF Mukai, K Ishida, M TI The early X-ray emission from V382 Velorum (nova Velorum 1999): An internal shock model SO ASTROPHYSICAL JOURNAL LA English DT Article DE novae, cataclysmic variables; stars : individual (V382 Velorum); X-rays : stars ID HERCULIS 1991; PLASMAS; SHELL; V838 AB We present the results of ASCA and RXTE observations of the early X-ray emission from the classical nova V382 Velorum. Its ASCA spectrum was hard (kT similar to 10 keV) with strong (10(23) cm(-2)) intrinsic absorption. In the subsequent RXTE data, the spectra became softer, because of both a declining temperature and a diminishing column. We argue that this places the X-ray emission interior to the outermost ejecta produced by V382 Vel in 1999, and therefore it must have been the result of a shock internal to the nova ejecta. The weakness of the Fe K alpha lines probably indicates that the X-ray-emitting plasmas are not in ionization equilibrium. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298501, Japan. RP Mukai, K (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 27 TC 59 Z9 59 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 APR 26 PY 2001 VL 551 IS 2 BP 1024 EP 1030 DI 10.1086/320220 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 427AX UT WOS:000168383600033 ER PT J AU Sin, YK Qiu, Y Muller, RE Forouhar, S AF Sin, YK Qiu, Y Muller, RE Forouhar, S TI Laterally coupled InGaAsP/InP distributed feedback lasers at 1.5 mu m for chemical sensing applications SO ELECTRONICS LETTERS LA English DT Article ID DIODE AB Data is presented on stable, tunable singlemode operation from laterally coupled InGaAsP/InP ridge waveguide distributed feedback lasers at similar to1.5 mum. suitable for chemical sensing, realised bq a greatly simplified fabrication process requiring a single MOCVD growth step. Completed lasers show sidemode suppression ratios as high as 47dB and wavelength shifts with injection current of 0.03nm/mA (or 4.5GHz/mA). C1 CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. RP Sin, YK (reprint author), CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. NR 8 TC 6 Z9 6 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD SG1 2AY, ENGLAND SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD APR 26 PY 2001 VL 37 IS 9 BP 567 EP 569 DI 10.1049/el:20010375 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA 431TL UT WOS:000168646600015 ER PT J AU Singh, H Chen, Y Staudt, A Jacob, D Blake, D Heikes, B Snow, J AF Singh, H Chen, Y Staudt, A Jacob, D Blake, D Heikes, B Snow, J TI Evidence from the Pacific troposphere for large global sources of oxygenated organic compounds SO NATURE LA English DT Article ID IN-SITU MEASUREMENTS; NONMETHANE HYDROCARBONS; CARBONYL-COMPOUNDS; ATMOSPHERE; CHEMISTRY; NITRATE; ACETONE; FATE; AIR; HOX AB The presence of oxygenated organic compounds in the troposphere strongly influences key atmospheric processes. Such oxygenated species are, for example, carriers of reactive nitrogen and are easily photolysed, producing free radicals(1-3)-and so influence the oxidizing capacity and the ozone-forming potential of the atmosphere(4-6)-and may also contribute significantly to the organic component of aerosols(7,8). But knowledge of the distribution and sources of oxygenated organic compounds, especially in the Southern Hemisphere, is limited. Here we characterize the tropospheric composition of oxygenated organic species, using data from a recent airborne survey(9) conducted over the tropical Pacific Ocean (30 degrees N to 30 degrees S). Measurements of a dozen oxygenated chemicals (carbonyls, alcohols, organic nitrates, organic pernitrates and peroxides), along with several C-2-C-8 hydrocarbons, reveal that abundances of oxygenated species are extremely high, and collectively, oxygenated species are nearly five times more abundant than non-methane hydrocarbons in the Southern Hemisphere. Current atmospheric models are unable to correctly simulate these findings, suggesting that large, diffuse, and hitherto-unknown sources of oxygenated organic compounds must therefore exist. Although the origin of these sources is still unclear, we suggest that oxygenated species could be formed via the oxidation of hydrocarbons in the atmosphere, the photochemical degradation of organic matter in the oceans, and direct emissions from terrestrial vegetation. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Harvard Univ, Cambridge, MA 02138 USA. Univ Calif Irvine, Irvine, CA 92697 USA. Univ Rhode Isl, Narragansett, RI 02882 USA. RP Singh, H (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RI jianwu, shi/B-2557-2009 NR 27 TC 243 Z9 247 U1 8 U2 45 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD APR 26 PY 2001 VL 410 IS 6832 BP 1078 EP 1081 DI 10.1038/35074067 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 425HQ UT WOS:000168285500043 PM 11323667 ER PT J AU Farrell, WM Desch, MD AF Farrell, WM Desch, MD TI Is there a Martian atmospheric electric circuit? SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID DUST STORMS; MARS AB Laboratory, analytical, and simulation studies suggest that Martian dust clouds can become significantly charged via dust/dust contact electrification. If moderate-size dust clouds on Mars are like their terrestrial counterparts, they are expected to have the capacity to create electric fields in excess of 1 kV/m. As on Earth, there is an expectation that these storm-generated electric fields terminate into both the ground and the ionosphere, coupling directly to the capacitor created by these bounding surfaces. Such charged dust storms are expected to drive ionospheric and ground currents, which complete their current path through the "fairweather" atmosphere remote from the storm. This system forms a Martian atmospheric electric circuit analogous (but not identical) to that created in the terrestrial atmosphere via thunderstorms. Here we define the requirements on Martian dust storms and the surrounding environment to create such a global electric circuit and then model the system. We fmd that the variation in global electric field is a strong function of Martian season, with possible values ranging in excess of hundreds of volts per meter in the active storm season (southern summer) to less than a volt per meter during the nonstorm season. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Farrell, WM (reprint author), NASA, Goddard Space Flight Ctr, Code 695, Greenbelt, MD 20771 USA. RI Farrell, William/I-4865-2013 NR 24 TC 26 Z9 27 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-PLANET JI J. Geophys. Res.-Planets PD APR 25 PY 2001 VL 106 IS E4 BP 7591 EP 7595 DI 10.1029/2000JE001271 PG 5 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 425JW UT WOS:000168288300003 ER PT J AU Stoker, C AF Stoker, C TI Introduction to the special section: The Marsokhod Silver Lake field experiment SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Editorial Material C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Stoker, C (reprint author), NASA, Ames Res Ctr, Mail Stop 245-3, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 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-PLANET JI J. Geophys. Res.-Planets PD APR 25 PY 2001 VL 106 IS E4 BP 7637 EP 7637 DI 10.1029/2000JE001485 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 425JW UT WOS:000168288300007 ER PT J AU Stoker, CR Cabrol, NA Roush, TR Moersch, J Aubele, J Barlow, N Bettis, EA Bishop, J Chapman, M Clifford, S Cockell, CS Crumpler, L Craddock, R De Hon, R Foster, T Gulick, V Grin, E Horton, K Hovde, G Johnson, JR Lee, PC Lemmon, MT Marshall, J Newsom, HE Ori, GG Reagan, M Rice, JW Ruff, SW Schreiner, J Sims, M Smith, PH Tanaka, K Thomas, HJ Thomas, G Yingst, RA AF Stoker, CR Cabrol, NA Roush, TR Moersch, J Aubele, J Barlow, N Bettis, EA Bishop, J Chapman, M Clifford, S Cockell, CS Crumpler, L Craddock, R De Hon, R Foster, T Gulick, V Grin, E Horton, K Hovde, G Johnson, JR Lee, PC Lemmon, MT Marshall, J Newsom, HE Ori, GG Reagan, M Rice, JW Ruff, SW Schreiner, J Sims, M Smith, PH Tanaka, K Thomas, HJ Thomas, G Yingst, RA TI The 1999 Marsokhod rover mission simulation at Silver Lake, California: Mission overview, data sets, and summary of results SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID PATHFINDER LANDING SITE; INFRARED MULTISPECTRAL SCANNER; NATURAL SURFACES; DEATH-VALLEY; MARS; FIELD; ROCKS; VOLCANISM; GEOLOGY; CLIMATE AB We report on a field experiment held near Silver Lake playa in the Mojave Desert in February 1999 with the Marsokhod rover. The payload (Descent Imager, PanCam, Mini-TES, and Robotic Arm Camera), data volumes, and data transmission/receipt windows simulated those planned for the Mars Surveyor mission selected for 2001. A central mast with a pan and tilt platform at 150 cm height carried a high-resolution color stereo imager to simulate the PanCam and a visible/near-infrared fiberoptic spectrometer (operating range 0.35-2.5 mum). Monochrome stereo navigation cameras were mounted on the mast and the front and rear of the rover near the wheels. A field portable infrared spectroradiometer (operating range 8-14 mum) simulated the Mini-TES. A Robotic Arm Camera, capable of close-up color imaging at 23 mum/pixel resolution, was used in conjunction with the excavation of a trench into the subsurface. The science team was also provided with simulated images from the Mars Descent Imager and orbital panchromatic and multispectral imaging of the site obtained with the French SPOT, airborne Thermal Infrared Mapping Spectrometer, and Landsat Thematic Mapper instruments. Commands sequences were programmed and sent daily to the rover, and data returned were limited to 40 Mbits per communication cycle. During the simulated mission, 12 commands were uplinked to the rover, it traversed similar to 90 m, six sites were analyzed, 11 samples were collected for laboratory analysis, and over 5 Gbits of data were collected. Twenty-two scientists, unfamiliar with the location of the field site, participated in the science mission from a variety of locations, accessing data via the World Wide Web. Remote science interpretations were compared with ground truth from the field and laboratory analysis of collected samples. Using this payload and mission approach, the science team synergistically interpreted orbital imaging and infrared spectroscopy, descent imaging, rover-based imaging, infrared spectroscopy, and microscopic imaging to deduce a consistent and largely correct interpretation of the geology, mineralogy, stratigraphy, and exobiology of the site. Use of imaging combined with infrared spectroscopy allowed source outcrops to be identified for local rocks on an alluvial fan. Different lithologies were distinguished both near the rover and at distances of hundreds of meters or more. Subtle differences such as a contact between dolomite and calcite were identified at a distance of 0.5 km. A biomarker for endolithic microbiota, a plausible life form to be found on Mars, was successfully identified. Microscopic imaging of soils extracted from the surface and subsurface allowed the mineralogy and fluvial history of the trench site to be deduced. The scientific productivity of this simulation shows that this payload and mission approach has high science value and would contribute substantially to achieving the goals of Mars exploration. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Tennessee, Dept Geol Sci, Knoxville, TN 37996 USA. New Mexico Museum Nat Hist & Sci, Albuquerque, NM 87104 USA. Univ Cent Florida, Dept Phys, Orlando, FL 32816 USA. Univ Iowa, Dept Geosci, Iowa City, IA 52242 USA. US Geol Survey, Flagstaff, AZ 86001 USA. Lunar & Planetary Inst, Houston, TX 77058 USA. Smithsonian Inst, Washington, DC 20560 USA. NE Louisiana Univ, Dept Geosci, Monroe, LA 71209 USA. Univ Hawaii Manoa, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Univ New Mexico, Dept Earth & Planetary Sci, Albuquerque, NM 87131 USA. Univ Annunzio, Dipartimento Sci, I-65127 Pescara, Italy. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. Univ Iowa, Dept Ind Engn, Iowa City, IA 52242 USA. RP Stoker, CR (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RI Lemmon, Mark/E-9983-2010; Moersch, Jeffrey/F-7189-2010; Craddock, Robert/B-3884-2013; Johnson, Jeffrey/F-3972-2015; OI Lemmon, Mark/0000-0002-4504-5136; ORI, Gian Gabriele/0000-0002-6460-1476 NR 54 TC 11 Z9 11 U1 0 U2 1 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 APR 25 PY 2001 VL 106 IS E4 BP 7639 EP 7663 DI 10.1029/1999JE001178 PG 25 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 425JW UT WOS:000168288300008 ER PT J AU De Hon, RA Barlow, NG Reagan, MK Bettis, EA Foster, CT Gulick, VC Crumpler, LS Aubele, JC Chapman, MG Tanaka, KL AF De Hon, RA Barlow, NG Reagan, MK Bettis, EA Foster, CT Gulick, VC Crumpler, LS Aubele, JC Chapman, MG Tanaka, KL TI Observation of the geology and geomorphology of the 1999 Marsokhod test site SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article AB The Marsokhod rover returned data from six stations that were used to decipher the geomorphology and geology of a region not previously visited by members of the geomorphology field team. Satellite images and simulated descent images provided information about the regional setting. The landing zone was on an alluvial apron flanking a mountain block to the west and a playa surface to the east. Rover color images, infrared spectra analysis of the mountains, and the apron surface provided insight into the rock composition of the nearby mountains. From the return data the geomorphology team interpreted the region to consist of compressionally deformed, ancient marine sediments and igneous rocks exposed by more recent extensional tectonics. Unconsolidated alluvial materials blanket the lower flanks of the mountains. Bn ancient shoreline cut into alluvial material marks a high stand of water during a past, wetter climate period. Playa sediments floor a present-day, seasonally, dry lake. Observations made by the rover using panoramic and close-up (hand specimens-scale) image data and color scene data confirmed the presence of boulders, cobbles, and fines of various provinces. Rover traverses to sites identified as geologically distinct, such as fan, channel, shoreline, and playa, provided useful clues to the geologic interpretations. Analysis of local rocks was given concert only through comparison with distant geologic features. These results demonstrated the importance of a multifaceted approach to site interpretation through comparison of interpretations derived by differing geologic techniques. C1 NE Louisiana Univ, Dept Geosci, Monroe, LA 71209 USA. Univ Cent Florida, Dept Phys, Orlando, FL 32816 USA. Univ Iowa, Dept Geosci, Iowa City, IA 52242 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. New Mexico Museum Nat Hist, Albuquerque, NM 87104 USA. US Geol Survey, Flagstaff, AZ 86001 USA. RP De Hon, RA (reprint author), NE Louisiana Univ, Dept Geosci, Monroe, LA 71209 USA. NR 9 TC 0 Z9 0 U1 0 U2 1 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 APR 25 PY 2001 VL 106 IS E4 BP 7665 EP 7682 DI 10.1029/1999JE001167 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 425JW UT WOS:000168288300009 ER PT J AU Johnson, JR Ruff, SW Moersch, J Roush, T Horton, K Bishop, J Cabrol, NA Cockell, CS Gazis, P Newsom, HE Stoker, C AF Johnson, JR Ruff, SW Moersch, J Roush, T Horton, K Bishop, J Cabrol, NA Cockell, CS Gazis, P Newsom, HE Stoker, C TI Geological characterization of remote field sites using visible and infrared spectroscopy: Results from the 1999 Marsokhod field test SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID DEATH-VALLEY; EMISSION-SPECTROSCOPY; MULTISPECTRAL SCANNER; SPECTRAL REFLECTANCE; CARBONATE MINERALS; NATURAL SURFACES; DESERT VARNISH; CALIFORNIA; ROCKS; SOILS AB Upcoming Mars Surveyor lander missions will include extensive spectroscopic capabilities designed to improve interpretations of the mineralogy and geology of landing sites on Mars. The 1999 Marsokhod Field Experiment (MFE) was a Mars rover simulation designed in part to investigate the utility of visible/near-infrared and thermal infrared field spectrometers to contribute to the remote geological exploration of a Mars analog field site in the California Mojave Desert. The experiment simultaneously investigated the abilities of an off-site science: team to effectively analyze and acquire useful imaging and spectroscopic data and to communicate efficiently with rover engineers and an on-site field team to provide meaningful input to rover operations and traverse planning. Experiences gained during the MFE regarding effective communication between different mission operation teams will be useful to upcoming Mars mission teams. Field spectra acquired during the MFE mission exhibited features interpreted at the time as indicative of carbonates (both dolomitic and calcitic), mafic rocks and associated weathering products, and silicic rocks with desert varnish-like coatings. The visible/near-infrared spectra also suggested the presence of organic compounds, including chlorophyll in one rock. Postmission laboratory petrologic and spectral analyses of returned samples confirmed that all rocks identified as carbonates using field measurements alone were cafe-silicates and that chlorophyll associated with endolithic organisms was present in the one rock for which it was predicted. Rocks classified from field spectra as silicics and weathered mafics were recognized in the laboratory as metamorphosed monzonites and diorite schists. This discrepancy was likely due to rock coatings sampled by the field spectrometers compared to fresh rock interiors analyzed petrographically, in addition to somewhat different surfaces analyzed by laboratory thermal spectroscopy compared to field spectra. C1 US Geol Survey, Astrogeol Team, Flagstaff, AZ 86001 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Hawaii, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Univ New Mexico, Inst Meteorit, Albuquerque, NM 87131 USA. Univ New Mexico, Dept Earth & Planetary Sci, Albuquerque, NM 87131 USA. RP Johnson, JR (reprint author), US Geol Survey, Astrogeol Team, 2255 N Gemini Dr, Flagstaff, AZ 86001 USA. RI Moersch, Jeffrey/F-7189-2010; Johnson, Jeffrey/F-3972-2015 NR 28 TC 9 Z9 9 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-PLANET JI J. Geophys. Res.-Planets PD APR 25 PY 2001 VL 106 IS E4 BP 7683 EP 7711 DI 10.1029/1999JE001149 PG 29 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 425JW UT WOS:000168288300010 ER PT J AU Newsom, HE Bishop, JL Cockell, CS Roush, TL Johnson, JR AF Newsom, HE Bishop, JL Cockell, CS Roush, TL Johnson, JR TI Search for life on Mars in surface samples: Lessons from the 1999 Marsokhod rover field experiment SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID REFLECTANCE SPECTROSCOPY; CRYPTOENDOLITHIC LICHENS; SPECTRAL REFLECTANCE; VICTORIA-LAND; MARTIAN LIFE; ANTARCTICA; MINERALS; VALLEYS; EARTH AB The Marsokhod 1999 field experiment in the Mojave Desert included a simulation of a rover-based sample selection mission. As part of this mission, a test was made of strategies and analytical techniques for identifying past or present life in environments expected to be present on Mars. A combination of visual clues from high-resolution images and the detection of an important biomolecule (chlorophyll) with visible/near-infrared (NIR) spectroscopy led to the successful identification of a rock with evidence of cryptoendolithic organisms. The sample was identified in high-resolution images (3 times the resolution of the Imager for Mars Pathfinder camera) on the basis of a green tinge and textural information suggesting the presence of a thin, partially missing exfoliating layer revealing the organisms. The presence of chlorophyll bands in similar samples was observed in visible/NIR spectra of samples in the field and later confirmed in the laboratory using the same spectrometer. Raman spectroscopy in the laboratory, simulating a remote measurement technique, also detected evidence of carotenoids in samples from the same area. Laboratory analysis confirmed that the subsurface layer of the rock is inhabited by a community of coccoid Chroococcidioposis cyanobacteria. The identification of minerals in the held, including carbonates and serpentine, that are associated with aqueous processes was also demonstrated using the visible/NIR spectrometer. Other lessons learned that are applicable to future rover missions include the benefits of web-based programs for target selection and for daily mission planning and the need for involvement of the science team in optimizing image compression schemes based on the retention of visual signature characteristics. C1 Univ New Mexico, Inst Meteorit, Albuquerque, NM 87131 USA. Univ New Mexico, Dept Earth & Planetary Sci, Albuquerque, NM 87131 USA. NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Bay Area Environm Res Inst, Moffett Field, CA 94035 USA. US Geol Survey, Flagstaff, AZ 86001 USA. RP Newsom, HE (reprint author), Univ New Mexico, Inst Meteorit, Room 306D,Northrop Hall, Albuquerque, NM 87131 USA. RI Johnson, Jeffrey/F-3972-2015 NR 29 TC 4 Z9 4 U1 0 U2 3 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 APR 25 PY 2001 VL 106 IS E4 BP 7713 EP 7720 DI 10.1029/1999JE001159 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 425JW UT WOS:000168288300011 ER PT J AU Grin, EA Reagan, MK Cabrol, NA Bettis, EA Foster, CT Stoker, CR Moersch, JE AF Grin, EA Reagan, MK Cabrol, NA Bettis, EA Foster, CT Stoker, CR Moersch, JE TI Geological analysis of the Silver Lake Marsokhod field test from ground-truth sampling and mapping SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MOJAVE DESERT; LATE PLEISTOCENE; CALIFORNIA AB We compare the results of the observations and conclusions obtained from a remote science team and field geologists during the 1999 Marsokhod Silver Lake field experiment. This comparison is used to determine methods that enhance the ability of a remote team using a rover to determine the geology and paleoclimate of a landing site analogous to sites that may be encountered during the Mars Surveyor Program. The mobility of the field geologists and their ability to rapidly gain visual and physical data from the field site give an immediate confidence to their interpretation of the geology. The finite time of teleoperation and the initial decisions and mechanical problems that caused the rover to linger and collect data in a small area of the test site for the first 5 days of the test limited the ability of the remote science team to gain a similar confidence. Nevertheless, by appropriate use of "orbital" and "descent" images as well as the rover's science payload, the remote science team interpreted the present and former climates, the geology and geological history, and present-day biology relatively accurately. The few erroneous interpretations by the remote team resulted in part from biases brought to the test about the nature of the geology that was likely to be encountered. Data quality and variety also impacted the quality of the geological interpretations. Significant misinterpretations in the remotely determined geology resulted from the lack of detail in the optical imagery, a less than optimal understanding of the site's topography, and misinterpretation of some infrared data. All in all, this field test showed that the geology, paleoclimate, and biology of a site can be assessed to a reasonable level of confidence using a remotely controlled vehicle. It also showed that it is both feasible and desirable for a distributed science team to participate in long science missions from home institutions, as long as data flows efficiently to and from these institutions. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Univ Iowa, Dept Geosci, Iowa City, IA 52242 USA. SETI Inst, Mt View, CA USA. RP Grin, EA (reprint author), NASA, Ames Res Ctr, Div Space Sci, MS 245-3, Moffett Field, CA 94035 USA. RI Moersch, Jeffrey/F-7189-2010 NR 23 TC 1 Z9 1 U1 0 U2 1 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 APR 25 PY 2001 VL 106 IS E4 BP 7733 EP 7744 DI 10.1029/1999JE001171 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 425JW UT WOS:000168288300013 ER PT J AU Gulick, VC Morris, RL Ruzon, MA Roush, TL AF Gulick, VC Morris, RL Ruzon, MA Roush, TL TI Autonomous image analyses during the 1999 Marsokhod rover field test SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article AB A Martian rover capable of analyzing images autonomously could traverse greater path lengths and return data with greater scientific content. A more intelligent rover could, for example, automatically select targets of interest (e.g., rocks, layers), return spectral or high-resolution image data of these targets at the same time, remove less interesting or redundant parts of images before transmitting them, and provide compact information or representations of its environment. Three prototype algorithms, a horizon detector, a rock detector, and a layer detector have been developed and tested during the 1999 Marsokhod rover field test in Silver Lake, California. The results are encouraging and demonstrate the potential savings in time as well as the potential increase in the amount of relevant science data returned in each command cycle. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Stanford Univ, Dept Comp Sci, Robot Lab, Stanford, CA 94305 USA. RP Gulick, VC (reprint author), NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. NR 14 TC 32 Z9 32 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD APR 25 PY 2001 VL 106 IS E4 BP 7745 EP 7763 DI 10.1029/1999JE001182 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 425JW UT WOS:000168288300014 ER PT J AU Gazis, PR Roush, T AF Gazis, PR Roush, T TI Autonomous identification of carbonates using near-IR reflectance spectra during the February 1999 Marsokhod field tests SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MINERALS AB An autonomous system has been developed to identify the presence of carbonates in near-IR reflectance spectra (0.35-2.5 mum). This system consists of a set of feature-extraction algorithms that operate in conjunction with a rule-based system to identify carbonates on the basis of presence and characteristics of absorption bands near 2.33 and 2.5 mum This autonomous system was tested during the February 1999 Marsokhod held operations. While-performance was compromised to some extent by noise problems associated with the spectrometer, the autonomous system successfully rejected all noisy spectra. Among the nonnoisy spectra that it accepted, it identified carbonates with a success rate of: 70% compared with the performance of the field team, a success rate of 82-90% compared with the performance of the remote science team, and a false positive rate of 0%. C1 NASA, Ames Res Ctr, SJSU Fdn, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Planetary Syst Branch, Moffett Field, CA 94035 USA. RP Gazis, PR (reprint author), NASA, Ames Res Ctr, SJSU Fdn, MS 245-3, Moffett Field, CA 94035 USA. NR 16 TC 9 Z9 9 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-PLANET JI J. Geophys. Res.-Planets PD APR 25 PY 2001 VL 106 IS E4 BP 7765 EP 7773 DI 10.1029/1999JE001148 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 425JW UT WOS:000168288300015 ER PT J AU Thomas, G Reagan, M Bettis, EA Cabrol, N Rathe, A AF Thomas, G Reagan, M Bettis, EA Cabrol, N Rathe, A TI Analysis of science team activities during the 1999 Marsokhod Rover Field Experiment: Implications for automated planetary surface exploration SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article AB This work analyzes the behavior and effectiveness of a science team using the Marsokhod mobile robot to explore the Silver Lake region in the Mojave Desert near Baker, California. The work addresses the manner in which the geologists organized themselves, how they allocated their time in different activities, how they formed and communicated scientific hypotheses, and the frequency with which they requested different types of data from the mission archive during the first 3 days of the mission. Eleven scientists from the NASA Ames Research Center and three of the five scientists who participated from their home institutions were videotaped as they worked throughout the 3-day experiment. The videotape record indicates that 46% of available person-hours were consumed in semistructured or formal meetings and that only 1% of their time was spent studying immersive, three-dimensional virtual reality models of the robot's surroundings. The remainder of their time was spent in unstructured work sessions in groups Of two or three. Hypothesis formation and evolution patterns show a meager flow of information from the distributed science team to the on-site team and a bias against reporting speculative hypotheses. Analysis of the visual imagery received from the robot indicates that acquisition of the large panoramic information leads to high levels of redundancy in the data acquired. The scientists' archive requests indicate that small, specifically requested image targets were the most frequently accessed information. The work suggests alternative organizational structures that would expedite the flow of information within the geologic team. It also advocates emphasizing specific science targets over high-resolution, stereoscopic, panoramic imaging when programming a mobile robot's onboard cameras. C1 Univ Iowa, Dept Ind Engn, Seamans Ctr 4316, Iowa City, IA 52242 USA. Univ Iowa, Dept Geosci, Iowa City, IA 52242 USA. NASA, Ames Res Ctr, SST, SETI Inst, Moffett Field, CA 94035 USA. RP Thomas, G (reprint author), Univ Iowa, Dept Ind Engn, Seamans Ctr 4316, Iowa City, IA 52242 USA. NR 15 TC 3 Z9 3 U1 0 U2 3 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 APR 25 PY 2001 VL 106 IS E4 BP 7775 EP 7783 DI 10.1029/1999JE001180 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 425JW UT WOS:000168288300016 ER PT J AU Cabrol, NA Chong-Diaz, G Stoker, CR Gulick, VC Landheim, R Lee, P Roush, TL Zent, AP Lameli, CH Iglesia, AJ Arrerondo, MP Dohm, JM Keaten, R Wettergreen, D Sims, MH Schwher, K Bualat, MG Thomas, HJ Zbinden, E Christian, D Pedersen, L Bettis, A Thomas, G Witzke, B AF Cabrol, NA Chong-Diaz, G Stoker, CR Gulick, VC Landheim, R Lee, P Roush, TL Zent, AP Lameli, CH Iglesia, AJ Arrerondo, MP Dohm, JM Keaten, R Wettergreen, D Sims, MH Schwher, K Bualat, MG Thomas, HJ Zbinden, E Christian, D Pedersen, L Bettis, A Thomas, G Witzke, B TI Nomad Rover Field Experiment, Atacama Desert, Chile 1. Science results overview SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID NORTHERN CHILE AB Nomad was deployed for a 45 day traverse in the Atacama Desert, Chile, during the summer of 1997. During this traverse, I week was devoted to science experiments. The goal of the science experiments was to test different planetary surface exploration strategies that included(l) a Mars mission simulation, (2) a science on the fly experiment, where the rover was kept moving 75% of the operation time. (The goal of this operation was to determine whether or not successful interpretation of the environment is related to the time spent on a target. The role of mobility in helping the interpretation was also assessed.) (3) a meteorite search using visual and instrumental methods to remotely identify meteorites in extreme environments, and (4) a time-delay experiment with and without using the panospheric camera. The results were as follow: the remote science team positively identified the main characteristics of the test site geological environment. The science on the fly experiment showed that the selection of appropriate targets might be even more critical than the time spent on a study area to reconstruct the history of a site. During the same operation the science team members identified and sampled a rock from a Jurassic outcrop that they proposed to be a fossil. The presence of paleolife indicators in this rock was confirmed later by laboratory analysis. Both visual and instrumental modes demonstrated the feasibility, in at least some conditions, of carrying out a field search for meteorites by using remote-controlled vehicles. Finally, metrics collected from the observation of the science team operations, and the use team members made of mission data, provided critical information on what operation sequences could be automated on board revers in future planetary surface explorations. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Univ Iowa, Dept Geol, Iowa City, IA 52242 USA. Univ Catolica Norte, Dept Ciencias Geol, Antofagasta 1280, Chile. Netscape Commun Corp, Moffett Field, CA 94035 USA. Univ Arizona, Dept Geosci, Tucson, AZ 85721 USA. US Geol Survey, Menlo Pk, CA 94025 USA. Carnegie Mellon Univ, Inst Robot, Field Robot Ctr, Pittsburgh, PA 15213 USA. Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92037 USA. Univ Iowa, Seamans Ctr Engn Arts & Sci 4316, Iowa City, IA 52242 USA. Monterey Bay Aquarium Res Inst, Moss Landing, CA 95039 USA. LightLog Inc, Santa Clara, CA 95054 USA. RP Cabrol, NA (reprint author), NASA, Ames Res Ctr, Div Space Sci, MS 245-3, Moffett Field, CA 94035 USA. EM ncabrol@mail.arc.nasa.gov RI Dohm, James/A-3831-2014 NR 12 TC 11 Z9 12 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 APR 25 PY 2001 VL 106 IS E4 BP 7785 EP 7806 DI 10.1029/1999JE001166 PG 22 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 425JW UT WOS:000168288300017 ER PT J AU Cabrol, NA Bettis, EA Glenister, B Chong, G Herrera, C Jensen, A Pereira, M Stoker, CR Grin, EA Landheim, R Thomas, G Golden, J Saville, K Ludvigson, G Witzke, B AF Cabrol, NA Bettis, EA Glenister, B Chong, G Herrera, C Jensen, A Pereira, M Stoker, CR Grin, EA Landheim, R Thomas, G Golden, J Saville, K Ludvigson, G Witzke, B TI Nomad Rover Field Experiment, Atacama Desert, Chile 2. Identification of paleolife evidence using a robotic vehicle: Lessons and recommendations for a Mars sample return mission SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID CLIMATE AB During the Nomad Rover Field Experiment in the Atacama Desert (Chile), a potential fossil was identified in a boulder by the science team remotely located at NASA Ames Research Center, California. The science team requested the collecting of the boulder that was returned for laboratory analysis. This analysis confirmed the evidence of paleolife. As the first fossil identified and sampled by a remotely located science team using a rover, we use the case of sample I-250697 to describe the process, both in the field and later in the laboratory during the rock analysis, which led to the identification, characterization, and confirmation of the evidence of paleolife evidence in I-250697. We point out the lessons that this case provides for future Mars sample return missions. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Univ Iowa, Dept Geosci, Iowa City, IA 52242 USA. Univ Catolica Norte, Dept Ciencias Geol, Antofagasta 1280, Chile. RP Cabrol, NA (reprint author), NASA, Ames Res Ctr, Div Space Sci, MS 245-3, Moffett Field, CA 94035 USA. EM ncabrol@mail.arc.nasa.gov NR 19 TC 5 Z9 5 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 APR 25 PY 2001 VL 106 IS E4 BP 7807 EP 7815 DI 10.1029/1999JE001181 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 425JW UT WOS:000168288300018 ER PT J AU Harrington, KJ Laughlin, RB Liang, S AF Harrington, KJ Laughlin, RB Liang, S TI Balanced branching in transcription termination SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID ESCHERICHIA-COLI RNA; TERNARY COMPLEXES; ANGSTROM RESOLUTION; SECONDARY STRUCTURE; ELONGATION COMPLEX; CRYSTAL-STRUCTURE; SINGLE-MOLECULE; POLYMERASE-II; CLEAVAGE; SITES AB The theory of stochastic transcription termination based on free-energy competition [von Hippel. P. H. & Yager. T, D, (1992) Science 255, 809-812 and von Hippel. P. H. & Yager, T. D, (1991) Proc. Natl. Acad. Sci. USA 88, 2307-2311] requires two or more reaction rates to be delicately balanced over a wide range of physical conditions. A large body of work on glasses and large molecules suggests that this balancing should be impossible in such a large system in the absence of a new organizing principle of matter. We review the experimental literature of termination and find no evidence for such a principle, but do find many troubling inconsistencies. most notably, anomalous memory effects. These effects suggest that termination has a deterministic component and may conceivably not be stochastic at all. We find that a key experiment by Wilson and von Hippel [Wilson, K. S. & von Hippel. P. H, (1994) J. Moi. Biol, 244, 36-51] thought to demonstrate stochastic termination was an incorrectly analyzed regulatory effect of Mg2+ binding. C1 Stanford Univ, Dept Phys, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Laughlin, RB (reprint author), Stanford Univ, Dept Phys, Stanford, CA 94305 USA. NR 57 TC 8 Z9 8 U1 1 U2 2 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 APR 24 PY 2001 VL 98 IS 9 BP 5019 EP 5024 DI 10.1073/pnas.240431598 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 425VC UT WOS:000168311500041 PM 11309513 ER PT J AU Homer, L Charles, PA Hakala, P Muhli, P Shih, IC Smale, AP Ramsay, G AF Homer, L Charles, PA Hakala, P Muhli, P Shih, IC Smale, AP Ramsay, G TI On the multi-periodicities in the X-ray dipper XB 1916-053 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE binaries : close; stars : individual : XB 1916-053; X-rays : stars ID HERCULES X-1-HZ HERCULIS; 4U 1915-05; GINGA OBSERVATIONS; ACCRETION DISKS; VW HYDRI; SUPERHUMPS; BINARIES; PERIOD; ABSORPTION; DISCOVERY AB Using the Rossi X-ray Timing Explorer and the Nordic Optical Telescope, we have obtained the highest ever quality X-ray/white-light high-speed photometry of XB 1916-053. We refine the X-ray period (P-X) to 3000.6 +/- 0.2s via a restricted cycle counting approach. Using our complete optical light curve, we have extended the optical period (P-opt) ephemeris by another 4 yr, providing further evidence for its stability, although a slightly longer period of 3027.555 +/- 0.002 s now provides a marginally better fit. Moreover, modulations at both P-X and P-opt are present in the optical data, with the former dominating the nightly light curves (i.e. a few cycles of data). We have also attempted to determine the 'beat' period, as seen in the repeating evolution of the X-ray dip structure, and the variation in primary dip phase. We find that a quasi-period of 4.74 +/- 0.05 d provides the best fit to the data, even then requiring phase shifts between cycles, with the expected 3.90-d 'beat' of P-X and P-opt appearing to be less likely. Finally, considering the nature of each of these temporal phenomena, we outline possible models, which could explain all of the observed behaviour of this enigmatic source, focusing on which of P-X or P-opt is the binary period. C1 Univ Oxford, Dept Astrophys, Nucl Phys Lab, Oxford OX1 3RH, England. Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. Univ Helsinki, Astrophys Lab, FIN-00014 Helsinki, Finland. Univ Helsinki Observ, FIN-00014 Helsinki, Finland. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. UCL, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England. RP Univ Washington, Dept Astron, Box 351580, Seattle, WA 98195 USA. EM homer@astro.washington.edu NR 48 TC 29 Z9 29 U1 0 U2 0 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0035-8711 EI 1365-2966 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD APR 21 PY 2001 VL 322 IS 4 BP 827 EP 842 DI 10.1046/j.1365-8711.2001.04170.x PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 429XX UT WOS:000168544200015 ER PT J AU Sheth, RK Diaferio, A AF Sheth, RK Diaferio, A TI Peculiar velocities of galaxies and clusters SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE galaxies : clusters : general; cosmology : theory; dark matter ID REDSHIFT-DISTANCE SURVEY; TULLY-FISHER RELATION; DARK-MATTER HALOES; ANALYTIC MODEL; SC GALAXIES; DISPERSION; STATISTICS; DENSITY; MOTIONS; FIELDS AB We present a simple model for the shape of the distribution function of galaxy peculiar velocities. We show how both non-linear and linear theory terms combine to produce a distribution which has an approximately Gaussian core with exponential wings. The model is easily extended to study how the statistic depends on the type of particle used to trace the velocity field (dark matter particles, dark matter haloes, galaxies), and on the density of the environment in which the test particles are located. Comparisons with simulations suggest that our model is accurate. We also show that the evolution of the peculiar velocities depends on the local, rather than the global, density. Since clusters populate denser regions on average, using cluster velocities with the linear theory scaling may lead to an overestimate of the global value of Ohm (0). Conversely, using linear theory with the global value of Ohm (0) to scale cluster velocities from the initial to the present time results in an underestimate of their true velocities. In general, however, the directions of motions of haloes are rather well described by linear theory. Our results help to simplify models of redshift-space distortions considerably. C1 NASA, Fermilab Astrophys Grp, Batavia, IL 60510 USA. Univ Turin, Dipartimento Fis Gen Amedeo Avogadro, I-10124 Turin, Italy. RP NASA, Fermilab Astrophys Grp, Batavia, IL 60510 USA. EM sheth@fnal.gov; diaferio@ph.unito.it NR 44 TC 99 Z9 100 U1 1 U2 1 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0035-8711 EI 1365-2966 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD APR 21 PY 2001 VL 322 IS 4 BP 901 EP 917 DI 10.1046/j.1365-8711.2001.04202.x PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 429XX UT WOS:000168544200022 ER PT J AU Cageao, RP Blavier, JF McGuire, JP Jiang, YB Nemtchinov, V Mills, FP Sander, SP AF Cageao, RP Blavier, JF McGuire, JP Jiang, YB Nemtchinov, V Mills, FP Sander, SP TI High-resolution Fourier-transform ultraviolet-visible spectrometer for the measurement of atmospheric trace species: application to OH SO APPLIED OPTICS LA English DT Article ID HYDROXYL COLUMN ABUNDANCE; STRATOSPHERIC OH; ABSORPTION-MEASUREMENTS; EARTHS ATMOSPHERE; MIDDLE ATMOSPHERE; DOPPLER DETECTION; SPECTROSCOPY; BAND; IR; UV AB A compact, high-resolution Fourier-transform spectrometer for atmospheric near-ultraviolet spectroscopy has been installed at the Jet Propulsion Laboratory's Table Mountain Facility (34.4 degreesN, 117.7 degreesW, elevation 2290 m). This instrument is designed with an unapodized resolving power near 500,000 at 300 nm to provide high-resolution spectra from 290 to 675 nm for the quantification of column abundances The measurement technique used is spectral analysis of molecular absorptions of solar radiation. The instrument, accompanying systems designs, and results of the atmospheric trace atmospheric hydroxyl column observations are described. (C) 2001 Optical Society of America. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91109 USA. CALTECH, Div Engn & Appl Sci, Pasadena, CA 91109 USA. Opt Res Corp, Pasadena, CA 91107 USA. RP Cageao, RP (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM Richard.P.Cageao@jpl.nasa.gov NR 35 TC 25 Z9 25 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 APR 20 PY 2001 VL 40 IS 12 BP 2024 EP 2030 DI 10.1364/AO.40.002024 PG 7 WC Optics SC Optics GA 421RD UT WOS:000168076600021 PM 18357206 ER PT J AU Gerin, M Pearson, JC Roueff, E Falgarone, E Phillips, TG AF Gerin, M Pearson, JC Roueff, E Falgarone, E Phillips, TG TI Determination of the hyperfine structure of N-2 D+ SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : molecules; molecular data; radio lines : ISM ID CLOUDS; CORES; N2H+ AB We present new high spectral resolution observations of the N2D+ J = 2 --> 1 and J = 3 --> 2 as well as N2H+ J = 3 --> 2 lines toward dense molecular cores. The hyperfine structure of the N2H+ and N2D+ transitions is clearly resolved in these sources, in excellent agreement with quantum mechanical calculations. Optical depths are determined from the observed spectra, leading to D/H values on the order of 10%-30% for the N2D+/N2H+ system. There are a large number of hyperfine components, and in addition to providing satellites, they contribute to the broadening and asymmetric shapes of the N2H+ and N2D+ line profiles. It is therefore important to take into account the detailed hyperfine structure of the transitions when deducing astrophysical parameters from observed data. C1 ENS, Phys Lab, CNRS, UMR 8540, F-75231 Paris 05, France. Observ Paris, DEMIRM, F-75014 Paris, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Observ Paris, DAEC, CNRS, UMR 8631, F-92190 Meudon, France. CALTECH, Submillimeter Observ, Pasadena, CA 91125 USA. RP Gerin, M (reprint author), ENS, Phys Lab, CNRS, UMR 8540, 24 Rue Lhomond, F-75231 Paris 05, France. NR 13 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 APR 20 PY 2001 VL 551 IS 2 BP L193 EP L197 DI 10.1086/320029 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 427BJ UT WOS:000168384700017 ER PT J AU Marsden, D White, NE AF Marsden, D White, NE TI Correlations between spectral properties and spin-down rate in soft gamma-ray repeaters and anomalous X-ray pulsars SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : general; stars : neutron ID MAGNETIZED NEUTRON-STARS; 4U-0142+61; EMISSION; ASCA AB Anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) are X-ray sources with unusual properties distinguishing them from both rotation-powered and most accretion-powered pulsars. Using archival ASCA data over the energy range 0.5-10.0 keV, we have studied the spectra of the persistent emission from these sources and their variation with spin-down rate. Using a single-power-law spectral model, we find that the overall hardness of the spectra increase with increasing spin-down rate, and therefore the spectral and spin-down mechanism are inextricably linked in these objects. In terms of the two-component blackbody plus power law spectral model, this correlation is seen as an increasing hardness of the high-energy component with increasing spin-down rate, with the temperature of the low-energy blackbody component remaining essentially constant. Also, for the two component spectral model, the ratio of the 2-10 keV power-law and bolometric blackbody luminosities gradually increases with the spin-down rate. We discuss these results in terms of the various theoretical models for SGRs and AXPs. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Marsden, D (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 35 TC 39 Z9 39 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 APR 20 PY 2001 VL 551 IS 2 BP L155 EP L158 DI 10.1086/320025 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 427BJ UT WOS:000168384700008 ER PT J AU Goldin, DS Dahl, CA Olsen, KL Ostrach, LH Klausner, RD AF Goldin, DS Dahl, CA Olsen, KL Ostrach, LH Klausner, RD TI Biomedicine - The NASA-NCI collaboration on biomolecular sensors SO SCIENCE LA English DT Editorial Material C1 NCI, Off Technol & Ind Relat, Bethesda, MD 20892 USA. NASA, Off Biol & Phys Res, Washington, DC 20546 USA. RP Dahl, CA (reprint author), NCI, Off Technol & Ind Relat, Bethesda, MD 20892 USA. NR 3 TC 8 Z9 8 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 APR 20 PY 2001 VL 292 IS 5516 BP 443 EP 444 DI 10.1126/science.1059744 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 423QB UT WOS:000168187300025 PM 11330296 ER PT J AU Veverka, J Thomas, PC Robinson, M Murchie, S Chapman, C Bell, M Harch, A Merline, WJ Bell, JF Bussey, B Carcich, B Cheng, A Clark, B Domingue, D Dunham, D Farquhar, R Gaffey, MJ Hawkins, E Izenberg, N Joseph, J Kirk, R Li, H Lucey, P Malin, M McFadden, L Miller, JK Owen, WM Peterson, C Prockter, L Warren, J Wellnitz, D Williams, BG Yeomans, DK AF Veverka, J Thomas, PC Robinson, M Murchie, S Chapman, C Bell, M Harch, A Merline, WJ Bell, JF Bussey, B Carcich, B Cheng, A Clark, B Domingue, D Dunham, D Farquhar, R Gaffey, MJ Hawkins, E Izenberg, N Joseph, J Kirk, R Li, H Lucey, P Malin, M McFadden, L Miller, JK Owen, WM Peterson, C Prockter, L Warren, J Wellnitz, D Williams, BG Yeomans, DK TI Imaging of small-scale features on 433 Eros from NEAR: Evidence for a complex regolith SO SCIENCE LA English DT Article ID MULTISPECTRAL IMAGER; EJECTA BLOCKS; ASTEROIDS; 243-IDA AB On 25 October 2000, the Near Earth Asteroid Rendevous (NEAR)-Shoemaker spacecraft executed a low-altitude flyover of asteroid 433 Eros, making it possible to image the surface at a resolution of about 1 meter per pixel. The Images reveal an evolved surface distinguished by an abundance of ejecta blocks, a dearth of small craters, and smooth material infilling some topographic lows. The subdued appearance of craters of different diameters and the variety of blocks and different degrees of their burial suggest that ejecta from several impact events blanketed the region imaged at closest approach and led to the building up of a substantial and complex regolith consisting of fine materials and abundant meter-sized blocks. C1 Cornell Univ, Ithaca, NY 14853 USA. Northwestern Univ, Dept Geol Sci, Evanston, IL 60208 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. SW Res Inst, Boulder, CO 80302 USA. Rensselaer Polytech Inst, Ctr Sci, Dept Earth & Environm Sci, Troy, NY 12180 USA. US Geol Survey, Flagstaff, AZ 86001 USA. Univ Hawaii, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Malin Space Sci Syst, San Diego, CA 92191 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Veverka, J (reprint author), Cornell Univ, Space Sci Bldg, Ithaca, NY 14853 USA. RI Wellnitz, Dennis/B-4080-2012; McFadden, Lucy-Ann/I-4902-2013; Murchie, Scott/E-8030-2015; Izenberg, Noam/F-3952-2015 OI McFadden, Lucy-Ann/0000-0002-0537-9975; Murchie, Scott/0000-0002-1616-8751; Izenberg, Noam/0000-0003-1629-6478 NR 23 TC 93 Z9 93 U1 0 U2 2 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 APR 20 PY 2001 VL 292 IS 5516 BP 484 EP 488 DI 10.1126/science.1058651 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 423QB UT WOS:000168187300041 PM 11313490 ER PT J AU Cheng, AF Barnouin-Jha, O Zuber, MT Veverka, J Smith, DE Neumann, GA Robinson, M Thomas, P Garvin, JB Murchie, S Chapman, C Prockter, L AF Cheng, AF Barnouin-Jha, O Zuber, MT Veverka, J Smith, DE Neumann, GA Robinson, M Thomas, P Garvin, JB Murchie, S Chapman, C Prockter, L TI Laser altimetry of small-scale features on 433 Eros from NEAR-Shoemaker SO SCIENCE LA English DT Article ID SHAPE AB During the Near Earth Asteroid Rendezvous (NEAR)-Shoemaker's Low-altitude flyover of asteroid 433 Eros, observations by the NEAR Laser Rangefinder (NLR) have helped to characterize small-scale surface features. On scales from meters to hundreds of meters, the surface has a fractal structure with roughness dominated by blocks, structural features, and walls of small craters, This fractal structure suggests that a single process, possibly impacts, dominates surface morphology on these scales. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. NASA, Goddard Space Flight Ctr, Earth Sci Directorate, Greenbelt, MD 20771 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. Cornell Univ, Ithaca, NY 14853 USA. Northwestern Univ, Dept Geol Sci, Evanston, IL 60208 USA. SW Res Inst, Boulder, CO 80302 USA. RP Cheng, AF (reprint author), Johns Hopkins Univ, Appl Phys Lab, Johns Hopkins Rd, Laurel, MD 20723 USA. RI Neumann, Gregory/I-5591-2013; Murchie, Scott/E-8030-2015; Barnouin, Olivier/I-7475-2015 OI Neumann, Gregory/0000-0003-0644-9944; Murchie, Scott/0000-0002-1616-8751; Barnouin, Olivier/0000-0002-3578-7750 NR 19 TC 22 Z9 22 U1 0 U2 1 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 APR 20 PY 2001 VL 292 IS 5516 BP 488 EP 491 DI 10.1126/science.1058330 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 423QB UT WOS:000168187300042 PM 11313491 ER PT J AU Misselt, KA Gordon, KD Clayton, GC Wolff, MJ AF Misselt, KA Gordon, KD Clayton, GC Wolff, MJ TI The DIRTY model. II. Self-consistent treatment of dust heating and emission in a three-dimensional radiative transfer code SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; methods : numerical; radiative transfer ID TRANSIENTLY HEATED PARTICLES; VISUAL REFLECTION NEBULAE; ACTIVE GALACTIC NUCLEI; INTERSTELLAR DUST; INFRARED-EMISSION; TEMPERATURE-FLUCTUATIONS; ULTRAVIOLET EXTINCTION; STARBURST GALAXIES; SMALL GRAINS; SIZE DISTRIBUTION AB In this paper and a companion paper we present the DIRTY model, a Monte Carlo radiative transfer code, self-consistently including dust heating and emission and accounting for the effects of the transient heating of small grains. The code is completely general : the density structure of the dust, the number and type of heating sources, and their geometric configurations can be specified arbitrarily within the model space. Source photons are tracked through the scattering and absorbing medium using Monte Carlo techniques, and the effects of multiple scattering are included. The dust-scattering, -absorbing, and -emitting properties are calculated from realistic dust models derived by fitting observed extinction curves in Local Group galaxies, including the Magellanic Clouds and the Milky Way. The dust temperature and the emitted dust spectrum are calculated self-consistently from the absorbed energy, including the effects of temperature fluctuations in small grains. Dust self-absorption is also accounted for, allowing the treatment of high optical depths, by treating photons emitted by the dust as an additional heating source and adopting an iterative radiative transfer scheme. As an illustrative case, we apply the DIRTY radiative transfer code to starburst galaxies wherein the heating sources are derived from stellar evolutionary synthesis models. Within the context of the starburst model, we examine the dependence of the ultraviolet to far-infrared spectral energy distribution, dust temperatures, and dust masses predicted by DIRTY on variations of the input parameters. C1 Louisiana State Univ, Dept Phys & Astron, Baton Rouge, LA 70803 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. Space Sci Inst, Boulder, CO 80303 USA. RP Louisiana State Univ, Dept Phys & Astron, Baton Rouge, LA 70803 USA. NR 57 TC 74 Z9 74 U1 0 U2 3 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 APR 18 PY 2001 VL 551 IS 1 BP 277 EP 293 DI 10.1086/320083 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 423AF UT WOS:000168152200026 ER PT J AU Wilking, BA Bontemps, S Schuler, RE Greene, TP Andre, P AF Wilking, BA Bontemps, S Schuler, RE Greene, TP Andre, P TI Infrared properties of weak radio sources in the rho Ophiuchi molecular cloud SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (rho Ophiuchi Cloud); radio continuum : stars; stars : pre-main-sequence ID YOUNG STELLAR OBJECTS; MAIN-SEQUENCE STARS; T-TAURI STARS; X-RAY SOURCES; DARK-CLOUD; LOW-MASS; CIRCUMSTELLAR MATERIAL; EVOLUTIONARY STATUS; IRAS OBSERVATIONS; EXTINCTION LAW AB We report mid-infrared ISOCAM observations for a sample of radio continuum sources in the rho Ophiuchi molecular cloud core with unknown or poorly studied infrared counterparts. These data are combined with existing infrared photometry, including recently published ISOCAM data, for previously studied radio sources to investigate the evolutionary states of 35 radio-emitting young stars in the rho Oph cloud core. About 50% of the radio stars are found to have class I, flat, or class II spectral energy distributions with near-infrared excesses arising from circumstellar disks. Their radio emission is most likely thermal emission from gas ionized by stellar winds. The remaining radio emitters are young stars with class III spectral energy distributions that lack infrared excesses and circumstellar disks. Their radio emission likely is nonthermal emission from magnetic surface activity. The lack of young stars with weak infrared excesses supports earlier suggestions that disk dissipation is rapid. Class III sources are twice as common as class II sources in this radio-selected sample in comparison with extinction-limited samples, which underscores the importance of radio surveys in obtaining a complete census of young stellar objects. The concentration of diskless class III objects in the high column-density molecular core, and their median age of 0.3 Myr derived from their positions in a Hertzsprung-Russell diagram, indicate they are contemporaries of class II objects which include the classical T Tauri stars. It appears that these class III objects have shorter disk survival times than class II objects in the cloud. C1 Univ Missouri, Dept Phys & Astron, St Louis, MO 63121 USA. Observ Bordeaux, F-33270 Floirac, France. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. CEA, DSM, DAPNIA, Serv Astrophys,Ctr Etud Saclay, F-91191 Gif Sur Yvette, France. RP Univ Missouri, Dept Phys & Astron, 8001 Nat Bridge Rd, St Louis, MO 63121 USA. EM brucew@newton.umsl.edu; bontemps@observ.u-bordeaux.fr; schuler@newton.umsl.edu; tgreene@mail.arc.nasa.gov; pandre@cea.fr NR 67 TC 45 Z9 45 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 APR 18 PY 2001 VL 551 IS 1 BP 357 EP 366 DI 10.1086/320067 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 423AF UT WOS:000168152200031 ER PT J AU Galli, D Shu, FH Laughlin, G Lizano, S AF Galli, D Shu, FH Laughlin, G Lizano, S TI Singular isothermal disks. II. Nonaxisymmetric bifurcations and equilibria SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : general; hydrodynamics; ISM : clouds; ISM : molecules; MHD; stars : formation ID DENSE INTERSTELLAR CLOUDS; SELF-SIMILAR COLLAPSE; STAR-FORMING REGIONS; T-TAURI STARS; MAGNETIC-FIELDS; PROTOSTELLAR DISKS; MOLECULAR CLOUDS; DARK CLOUDS; AMBIPOLAR DIFFUSION; HIGH-RESOLUTION AB We review the difficulties of the classical fission and fragmentation hypotheses for the formation of binary and multiple stars. A crucial missing ingredient in previous theoretical studies is the inclusion of dynamically important levels of magnetic fields. As a minimal model for a candidate precursor to the formation of binary and multiple stars, we therefore formulate and solve the problem of the equilibria of isopedically magnetized, singular isothermal disks, without the assumption of axial symmetry. Considerable analytical progress can be made if we restrict our attention to models that are scale-free, i.e., that have surface densities that vary inversely with distance <()over bar> from the rotation axis of the system. In agreement with earlier analysis by Syer & Tremaine, we find that lopsided (M = 1) configurations exist at any dimensionless rotation rate, including zero. Multiple-lobed (M = 2, 3, 4,...) configurations bifurcate from an underlying axisymmetric sequence at progressively higher dimensionless rates of rotation, but such nonaxisymmetric sequences always terminate in shock waves before they have a chance to fission into M = 2, 3, 4,... separate bodies. On the basis of our experience in this paper and the preceding Paper I, we advance the hypothesis that binary and multiple star formation from smooth (i.e., not highly turbulent) starting states that are supercritical but in unstable mechanical balance requires the rapid (i.e., dynamical) loss of magnetic flux at some stage of the ensuing gravitational collapse. C1 Osserv Astrofis Arcetri, I-50125 Florence, Italy. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Nacl Autonoma Mexico, Inst Astron, Mexico City 4510, DF, Mexico. RP Osserv Astrofis Arcetri, Largo E Fermi 5, I-50125 Florence, Italy. EM galli@arcetri.astro.it; shu@vshu.berkeley.edu; gpl@acetylene.arc.nasa.gov; lizano@astrosmo.unam.mx OI Galli, Daniele/0000-0001-7706-6049 NR 86 TC 33 Z9 33 U1 1 U2 2 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 APR 18 PY 2001 VL 551 IS 1 BP 367 EP 386 DI 10.1086/320074 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 423AF UT WOS:000168152200032 ER PT J AU Dyer, KK Reynolds, SP Borkowski, KJ Allen, GE Petre, R AF Dyer, KK Reynolds, SP Borkowski, KJ Allen, GE Petre, R TI Separating thermal and nonthermal X-rays in supernova remnants. I. Total fits to SN 1006 AD SO ASTROPHYSICAL JOURNAL LA English DT Article DE radiation mechanisms : nonthermal; supernova remnants; X-rays : ISM ID NONLINEAR SHOCK ACCELERATION; HIGH-ENERGY ELECTRONS; RX J1713.7-3946; COSMIC-RAYS; GAMMA-RAYS; SN-1006; EMISSION; SHELL; TEV; MODELS AB The remnant of SN 1006 has an X-ray spectrum dominated by nonthermal emission, and pre-ASCA observations were well described by a synchrotron calculation with electron energies limited by escape. We describe the results of a much more stringent test : fitting spatially integrated ASCA GIS (0.6-8 keV) and RXTE PCA (3-10 keV) data with a combination of the synchrotron model SRESC newly ported to XSPEC and a new thermal shock model VPSHOCK. The new model can describe the continuum emission above 2 keV well, in both spatial distribution and spectrum. We find that the emission is dominantly nonthermal, with a small but noticeable thermal component: Mg and Si are clearly visible in the integrated spectrum. The synchrotron component rolls off smoothly from the extrapolated radio spectrum, with a characteristic rolloff frequency of 3.1 x 10(17) Hz, at which the spectrum has dropped about a factor of 6 below a power-law extrapolation from the radio spectrum. Comparison of TeV observations with new TeV model images and spectra based on the X-ray model fits gives a mean postshock magnetic field strength of about 9 muG, implying (for a compression ratio of 4) an upstream magnetic field of 3 muG, and fixing the current energy content in relativistic electrons at about 7 x 10(48) ergs, resulting in a current electron-acceleration efficiency of about 5%. This total energy is about 100 times the energy in the magnetic field. The X-ray fit also implies that electrons escape ahead of the shock above an energy of about 30 TeV. This escape could result from an absence of scattering magnetohydrodynamic waves above a wavelength of about 10(17) cm. Our results indicate that joint thermal and nonthermal fitting, using sophisticated models, will be required for analysis of most supernova-remnant X-ray data in the future. C1 N Carolina State Univ, Dept Phys, Raleigh, NC 27695 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Dyer, KK (reprint author), N Carolina State Univ, Dept Phys, Box 8202, Raleigh, NC 27695 USA. NR 43 TC 55 Z9 56 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 APR 18 PY 2001 VL 551 IS 1 BP 439 EP 453 DI 10.1086/320085 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 423AF UT WOS:000168152200037 ER PT J AU Suttner, G Yorke, HW AF Suttner, G Yorke, HW TI Early dust evolution in protostellar accretion disks SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; hydrodynamics; radiative transfer; solar system : formation; stars : formation ID GRAIN-GROWTH; SOLAR NEBULA; SIZE DISTRIBUTION; COAGULATION; ENVELOPES; CLOUDS; APPEARANCE; DIFFUSION AB We investigate dust dynamics and evolution during the formation of a protostellar accretion disk around intermediate-mass stars via two-dimensional numerical simulations. Using three different detailed dust models, compact spherical particles, fractal ballistic particle cluster agglomeration (BPCA) grains, and ballistic cluster cluster agglomeration (BCCA) grains, we find that even during the early collapse and the first similar to 10(4) yr of dynamical disk evolution, the initial dust size distribution is strongly modified. Close to the disk's midplane coagulation produces dust particles of sizes of several times 10 mum (for compact spherical grains) up to several millimeters (for fluffy BCCA grains), whereas in the vicinity of the accretion shock front (located several density scale heights above the disk), large velocity differences inhibit coagulation. Dust particles larger than about 1 mum segregate from the smaller grains behind the accretion shock. Because of the combined effects of coagulation and grain segregation, the infrared dust emission is modified. Throughout the accretion disk a Mathis, Rumpl, & Nordsieck dust distribution provides a poor description of the general dust properties. Estimates of the consequences of the "freezing out" of molecules in protostellar disks should consider strongly modified grains. Physical model parameters such as the limiting sticking strength and the grains' resistivity against shattering are crucial factors determining the degree of coagulation reached. In dense regions (e.g., in the midplane of the disk) a steady state is quickly attained; for the parameters used here the coagulation timescale for 0.1 mum dust particles is similar to1 yr (10(-12) g cm(-3)/rho). High above the equatorial plane coagulation equilibrium is not reached as a result of the much lower densities. Here the dust size distribution is affected primarily by differential advection, rather than coagulation. The influence of grain evolution and grain dynamics on the disk's near-infrared continuum appearance during the disk's formation phase is only slight because the most strongly coagulated grains are embedded deep within the accretion disk. C1 Univ Wurzburg, Astron Inst, D-97074 Wurzburg, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Suttner, G (reprint author), Univ Wurzburg, Astron Inst, D-97074 Wurzburg, Germany. NR 39 TC 37 Z9 37 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 APR 18 PY 2001 VL 551 IS 1 BP 461 EP 477 DI 10.1086/320061 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 423AF UT WOS:000168152200039 ER PT J AU Wahlgren, GM Brage, T Brandt, JC Fleming, J Johansson, S Leckrone, DS Proffitt, CR Reader, J Sansonetti, CJ AF Wahlgren, GM Brage, T Brandt, JC Fleming, J Johansson, S Leckrone, DS Proffitt, CR Reader, J Sansonetti, CJ TI The bismuth abundance in the HgMn stars chi Lupi and HR 7775 and improved atomic data for selected transitions of BiI, BiII, and BiIII SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic data; stars : abundances; stars : chemically peculiar; stars : individual (chi Lupi, HR 7775); ultraviolet : stars ID OSCILLATOR-STRENGTHS; PATHFINDER PROJECT; ELEMENTS; PLATINUM; SPECTROSCOPY; DIFFUSION; ENVELOPES; SPECTRUM; PACKAGE; PROGRAM AB High-resolution spectra of the chemically peculiar HgMn stars chi Lupi and HR 7775, obtained with the Hubble Space Telescope/Goddard High Resolution Spectrograph, are investigated for their abundance of bismuth by comparison with LTE synthetic spectrum modeling. HR 7775, previously known from International Ultraviolet Explorer spectra to display strong lines of Bi II, is determined to have bismuth present at an enhancement level of nearly 5 orders of magnitude from the lines Bi II lambda lambda 1436, 1902 and Bi III lambda 1423. The bismuth enhancement for chi Lupi is found to be near a level of 1.5 dex, and an ionization anomaly between Bi+ and Bi++ is apparent. HR 7775 abundance enhancements of the heavy elements platinum, [Pt/H] = 4.7 dex, and gold, [Au/H] = 3.8 dex, have also been determined. New laboratory measurements for wavelengths and hyperfine structure patterns of Bi I/Bi II/Bi III lines are presented, as well as the results of calculations for hyperfine structure constants and oscillator strengths for selected lines of Bi II and Bi III. C1 Univ Lund, Dept Phys, S-22100 Lund, Sweden. NASA, Goddard Space Flight Ctr, Comp Sci Corp, Sci Program, Greenbelt, MD 20771 USA. Univ Colorado, Lab Astron & Space Phys, Boulder, CO 80309 USA. Queens Univ Belfast, Dept Appl Math, Belfast BT7 1NN, Antrim, North Ireland. Univ Lund, Lund Observ, S-22100 Lund, Sweden. NASA, Goddard Space Flight Ctr, Hubble Space Telescope Project, Greenbelt, MD 20771 USA. Comp Sci Corp, Sci Program, Baltimore, MD 21218 USA. Catholic Univ Amer, Dept Phys, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. Natl Inst Stand & Technol, Gaithersburg, MD 20899 USA. RP Wahlgren, GM (reprint author), Univ Lund, Dept Phys, Box 118, S-22100 Lund, Sweden. NR 44 TC 17 Z9 17 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 APR 18 PY 2001 VL 551 IS 1 BP 520 EP 535 DI 10.1086/320063 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 423AF UT WOS:000168152200045 ER PT J AU Joy, M LaRoque, S Grego, L Carlstrom, JE Dawson, K Ebeling, H Holzapfel, WL Nagai, D Reese, ED AF Joy, M LaRoque, S Grego, L Carlstrom, JE Dawson, K Ebeling, H Holzapfel, WL Nagai, D Reese, ED TI Sunyaev-Zeldovich effect imaging of massive clusters of galaxies at redshift z > 0.8 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations; galaxies : clusters : individual (Cl J0152.7-1357, Cl J1226.9+3332, MS 1054.4-0321); techniques : interferometric ID X-RAY-CLUSTERS; MS-1054-03; DENSITY; ABUNDANCE; UNIVERSE; Z=0.83 AB We present Sunyaev-Zeldovich effect (SZE) imaging observations of three distant (z > 0.8) and highly X-ray luminous clusters of galaxies, Cl J1226.9+3332, Cl J0152.7-1357, and MS 1054.4-0321. Two of the clusters, Cl J1226.9+3332 and Cl J0152.7-1357, were recently discovered in deep ROSAT X-ray images. Their high X-ray luminosity suggests that they are massive systems, which, if confirmed, would provide strong constraints on the cosmological parameters of structure formation models. Our SZE data provide confirmation that they are massive clusters similar to the well-studied cluster MS 1054.4-0321. Assuming the clusters have the same gas mass fraction as that derived from SZE measurements of 18 known massive clusters, we are able to infer their mass and electron temperature from the SZE data. The derived electron temperatures are 9.8(-1.9)(+4.7), 8.7(-1.8)(+4.1), and 10.4(-2.0)(+5.0) keV, respectively, and we infer total masses of similar to2 x 10(14) h(100)(-1) M. within a radius of 65 " (340 h(100)(-1) kpc) for all three clusters. For Cl J0152.7-1357 and MS 1054.4-0321, we find good agreement between our SZE-derived temperatures and those inferred from X-ray spectroscopy. No X-ray-derived temperatures are available for Cl J1226.9+3332, and thus the SZE data provide the first confirmation that it is indeed a massive system. The demonstrated ability to determine cluster temperatures and masses from SZE observations without access to X-ray data illustrates the power of using deep SZE surveys to probe the distant universe. C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. RP Joy, M (reprint author), NASA, George C Marshall Space Flight Ctr, Dept Space Sci, SD50, Huntsville, AL 35812 USA. RI Holzapfel, William/I-4836-2015 NR 32 TC 32 Z9 32 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 APR 18 PY 2001 VL 551 IS 1 BP L1 EP L4 DI 10.1086/319833 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 423AR UT WOS:000168153300001 ER PT J AU Laughlin, G Chambers, JE AF Laughlin, G Chambers, JE TI Short-term dynamical interactions among extrasolar planets SO ASTROPHYSICAL JOURNAL LA English DT Article DE planetary systems AB We show that short-term perturbations among massive planets in multiple planet systems can result in radial velocity variations of the central star that differ substantially from velocity variations derived assuming the planets are executing independent Keplerian motions. We discuss two fitting methods that can lead to an improved dynamical description of multiple planet systems. In the first method, the osculating orbital elements are determined via a Levenberg-Marquardt minimization scheme driving an N-body integrator. The second method is an improved analytic model in which orbital elements are allowed to vary according to a simple model for resonant interactions between the planets. Both of these methods can determine the true masses for the planets by eliminating the degeneracy inherent in fits that assume independent Keplerian motions. We apply our fitting methods to the sin i GJ 876 radial velocity data and argue that the mass factors for the two planets are likely in the 1.25-2.0 range. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Armagh Observ, Armagh BT61 9DG, North Ireland. RP Laughlin, G (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 6 TC 144 Z9 147 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 APR 18 PY 2001 VL 551 IS 1 BP L109 EP L113 DI 10.1086/319847 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 423AR UT WOS:000168153300026 ER PT J AU Nayakshin, S Svensson, R AF Nayakshin, S Svensson, R TI On the "failure" of the standard model for soft X-ray transients in quiescence SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : close; line : formation; novae, cataclysmic variables ID ACCRETION DISK; DWARF NOVA; BLACK-HOLE; GALACTIC NUCLEI; LINE EMISSION; SIMULATIONS; INSTABILITY; OUTBURSTS; ECLIPSE; CORONAE AB It is currently believed that the "standard" accretion disk theory underpredicts the observed X-ray luminosity from soft X-ray transients (SXTs) in quiescence by as much as 4-6 orders of magnitude. This failure of the standard model is considered to be an important argument for the existence of an alternative mode of accretion, i.e., advection-dominated accretion flows in astrophysics; these flows allow a much higher level of X-ray emission in quiescence, in agreement with the observations. Here we point out that, in stark contrast to steady state standard disks, such disks in quiescence (being nonsteady) produce most of the X-ray emission very far from the last stable orbit. Taking this into account, these disks can accommodate the observed X-ray luminosities of SXTs rather naturally. Our theory predicts that Fe K alpha lines from standard accretion disks in quiescence should be narrow even though the cold disk goes all the way down to the last stable orbit. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. Stockholm Observ, SE-13336 Saltsjobaden, Sweden. RP Nayakshin, S (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. NR 44 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 APR 18 PY 2001 VL 551 IS 1 BP L67 EP L71 DI 10.1086/319825 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 423AR UT WOS:000168153300016 ER PT J AU Roberge, A Des Etangs, AL Grady, CA Vidal-Madjar, A Bouret, JC Feldman, PD Deleuil, M Andre, M Boggess, A Bruhweiler, FC Ferlet, R Woodgate, B AF Roberge, A Des Etangs, AL Grady, CA Vidal-Madjar, A Bouret, JC Feldman, PD Deleuil, M Andre, M Boggess, A Bruhweiler, FC Ferlet, R Woodgate, B TI FUSE and Hubble Space Telescope/STIS observations of hot and cold gas in the AB Aurigae system SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; stars : atmospheres; stars : individual (AB Aurigae) ID HERBIG AE/BE STARS; MOLECULAR-HYDROGEN; BAND SYSTEM; SPECTRA; TABLE AB We present the first observations of a Herbig Ae star with a circumstellar disk by the Far-Ultraviolet Spectroscopic Explorer (FUSE) as well as a simultaneous observation of the star obtained with the Hubble Space Telescope/Space Telescope Imaging Spectrograph (STIS). The spectra of AB Aurigae show emission and absorption features arising from gases that have a wide range in temperature, from hot O VI emission to cold H-2 and CO absorption. Emissions from the highly ionized species O VI and C III present in the FUSE spectrum are redshifted, while absorption features arising from low-ionization species like O I, NI, and Si II are blueshifted and show characteristic stellar wind line profiles. We find that the total column density of H-2 toward AB Aur from the FUSE spectrum is N(H-2) = (6.8 +/- 0.5) x 10(19) cm(-2). The gas kinetic temperature of the H-2 derived from the ratio N(J = 1)/N(J = 0) is 65 +/- 4 K. The column density of the CO observed in the STIS spectrum is N(CO) = (7.1 +/- 0.5) x 10(19) cm(-2), giving a CO/H-2 ratio of (1.04 +/- 0.11) x 10(-6). We also use the STIS spectrum to find the column density of H I, which permits us to calculate the total column density of hydrogen atoms, the fractional abundance of H-2, and the gas-to-dust ratio. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Lab Astron Marseille, F-13376 Marseille, France. Catholic Univ Amer, Dept Phys, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. RP Roberge, A (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. RI Roberge, Aki/D-2782-2012 OI Roberge, Aki/0000-0002-2989-3725 NR 18 TC 56 Z9 56 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 APR 18 PY 2001 VL 551 IS 1 BP L97 EP L100 DI 10.1086/319831 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 423AR UT WOS:000168153300023 ER PT J AU Shindell, DT Schmidt, GA Miller, RL Rind, D AF Shindell, DT Schmidt, GA Miller, RL Rind, D TI Northern Hemisphere winter climate response to greenhouse gas, ozone, solar, and volcanic forcing SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; TROPOSPHERE-STRATOSPHERE SYSTEM; MIDDLE ATMOSPHERE MODEL; INTERANNUAL VARIABILITY; ANNULAR MODES; POLAR VORTEX; EXTRATROPICAL CIRCULATION; ATLANTIC OSCILLATION; ARCTIC OSCILLATION; PLANETARY-WAVES AB The Goddard Institute for Space Studies (GISS) climate-middle atmosphere model has been used to study the impacts of increasing greenhouse gases, polar ozone depletion, volcanic eruptions, and solar cycle variability. We focus on the projection of the induced responses onto Northern Hemisphere winter surface climate. Changes in the model's surface climate take place largely through enhancement of existing variability patterns, with greenhouse gases, polar ozone depletion, and volcanic eruptions primarily affecting the Arctic Oscillation (AO) pattern. Perturbations descend from the stratosphere to the surface in the model by altering the propagation of planetary waves coming up from the surface, in accord with observational evidence. Models lacking realistic stratospheric dynamics fail to capture these wave flux changes. The results support the conclusion that the stratosphere plays a crucial role in recent AO trends. We show that in our climate model, while ozone depletion has a significant effect, greenhouse gas forcing is the only one capable of causing the large, sustained increase in the AO observed over recent decades. This suggests that the AO trend, and a concurrent strengthening of the stratospheric vortex over the Arctic, are very likely anthropogenic in origin. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Ctr Climate Syst Res, New York, NY USA. RP Shindell, DT (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM dshindell@giss.nnsa.gov RI Shindell, Drew/D-4636-2012; Schmidt, Gavin/D-4427-2012; Miller, Ron/E-1902-2012 OI Schmidt, Gavin/0000-0002-2258-0486; NR 67 TC 202 Z9 209 U1 1 U2 20 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 16 PY 2001 VL 106 IS D7 BP 7193 EP 7210 DI 10.1029/2000JD900547 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 423QZ UT WOS:000168189400002 ER PT J AU Chou, MD Chan, PK Yan, MMH AF Chou, MD Chan, PK Yan, MMH TI A sea surface radiation data set for climate applications in the tropical western Pacific and South China Sea SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERIC ABSORPTION; SOLAR-RADIATION; WATER-VAPOR; WARM POOL; CLOUDS; UNCERTAINTIES; TEMPERATURE; IRRADIANCE; BUDGETS; MODELS AB The sea surface shortwave and longwave radiative fluxes have been retrieved from the radiances measured by Japan's Geostationary Meteorological Satellite 5. The surface radiation data set covers the domain 40 degreesS-40 degreesN and 90 degreesE-170 degreesW and a period starting from January 1998. The temporal resolution is 1 day, and the spatial resolution is 0.5 degrees x0.5 degrees latitude-longitude. The retrieved surface radiation has been validated with the radiometric measurements at the Atmospheric Radiation Measurement (ARM) site on Manus Island in the equatorial western Pacific. It has also been validated with the measurements at the radiation site on Dungsha Island during the South China Sea Monsoon Experiment (SCSMEX) (May and June 1998). The data set is used to study the effect of El Nine and East Asian summer monsoon on the heating of the ocean. Interannual variations of clouds associated with El Nine and the East Asian summer monsoon have a large impact on the radiative heating of the ocean, exceeding 40 W m(-2) in seasonal mean over large areas. Together with the Clouds and the Earth's Radiant Energy System (CERES) shortwave fluxes at the top of the atmosphere and the radiative transfer calculations of dear-sky fluxes, this surface radiation data set is also used to study the impact of clouds on the solar heating of the atmosphere. It is found that clouds enhance the atmospheric solar heating by similar to 21 W m in the tropical western Pacific and the South China Sea. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. RP Chou, MD (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Mail Code 913, Greenbelt, MD 20771 USA. NR 32 TC 6 Z9 6 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 16 PY 2001 VL 106 IS D7 BP 7219 EP 7228 DI 10.1029/2000JD900661 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 423QZ UT WOS:000168189400004 ER PT J AU Zhang, JL Christopher, SA Holben, BN AF Zhang, JL Christopher, SA Holben, BN TI Intercomparison of smoke aerosol optical thickness derived from GOES 8 imager and ground-based Sun photometers SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SCAR-B; MICROPHYSICAL PROPERTIES; SOUTH-AMERICA; GOES-I; BIOMASS; BRAZIL; SATELLITE; PARTICLES; AIRBORNE; SEASON AB Using high temporal resolution GOES 8 imager data and radiative transfer calculations, smoke aerosol optical thickness (tau) is retrieved over selected sites in South America and Central America. The degradation of the signal response in the GOES 8 visible channel is estimated and the satellite-retrieved tau values are then compared against ground-based Sun photometer derived values. The satellite-retrieved values are in good agreement with ground-based tau for two sites in South America with mean linear correlation coefficients of 0.97. For Central America the mean correlation coefficient is 0.80. A single scattering albedo of 0.90 (at 0.67 mum) yields the best agreement between ground-based and satellite retrieved values and is consistent with previous studies. However, our results show that the retrieved optical thickness results are sensitive to single scattering albedo and surface reflectance. For example, a +/-3.3% change in single scattering albedo (0.90 +/- 0.03) yields an uncertainty in tau of 10% for small optical thickness (tau = 0.5) and an uncertainty of abut 25% for larger optical thickness values 1(tau = 1.5). Although the GOES 8 visible channel has undergone significant degradation in signal response Since launch, smoke aerosol optical thickness can be estimated if proper procedures re used to account for this effect. C1 Univ Alabama, Dept Atmospher Sci, Huntsville, AL 35806 USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. RP Christopher, SA (reprint author), Univ Alabama, Dept Atmospher Sci, Huntsville, AL 35806 USA. RI Christopher, Sundar/E-6781-2011 NR 47 TC 38 Z9 38 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 16 PY 2001 VL 106 IS D7 BP 7387 EP 7397 DI 10.1029/2000JD900540 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 423QZ UT WOS:000168189400015 ER PT J AU Schulz, A Rex, M Harris, NRP Braathern, GO Reimer, E Alfier, R Kilbane-Dawe, I Eckermann, S Allaart, M Alpers, M Bojkov, B Cisneros, J Claude, H Cuevas, E Davies, J De Backer, H Dier, H Dorokhov, V Fast, H Godin, S Johnson, B Kois, B Kondo, Y Kosmidis, E Kyro, E Litynska, Z Mikkelsen, IS Molyneux, MJ Murphy, G Nagai, T Nakane, H O'Connor, F Parrondo, C Schmidlin, FJ Skrivankova, P Varotsos, C Vialle, C Viatte, P Yushkov, V Zerefos, C von der Gathen, P AF Schulz, A Rex, M Harris, NRP Braathern, GO Reimer, E Alfier, R Kilbane-Dawe, I Eckermann, S Allaart, M Alpers, M Bojkov, B Cisneros, J Claude, H Cuevas, E Davies, J De Backer, H Dier, H Dorokhov, V Fast, H Godin, S Johnson, B Kois, B Kondo, Y Kosmidis, E Kyro, E Litynska, Z Mikkelsen, IS Molyneux, MJ Murphy, G Nagai, T Nakane, H O'Connor, F Parrondo, C Schmidlin, FJ Skrivankova, P Varotsos, C Vialle, C Viatte, P Yushkov, V Zerefos, C von der Gathen, P TI Arctic ozone loss in threshold conditions: Match observations in 1997/1998 and 1998/1999 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID WINTER; DEPLETION; STRATOSPHERE; VORTEX AB Chemical ozone loss rates inside the Arctic polar vortex were determined in early 1998 and early 1999 by using the Match technique based on coordinated ozonesonde measurements. These two winters provide the only opportunities in recent years to investigate chemical ozone loss in a warm Arctic vortex under threshold conditions, i.e., where the preconditions for chlorine activation, and hence ozone destruction, only occurred occasionally. In 1998, results were obtained in January and February between 410 and 520 K. The overall ozone loss was observed to be largely insignificant; with the exception of late February, when those air parcels exposed to temperatures below 195 K were affected by chemical ozone loss. In 1999, results are confined to the 475 K isentropic level, where no significant ozone loss was observed. Average temperatures were some 8 degrees - 10 degrees higher than those in 1995, 1996, and 1997, when substantial chemical ozone loss occurred. The results underline the strong dependence of the chemical ozone loss on the stratospheric temperatures. This study shows that enhanced chlorine alone does not provide a sufficient condition for ozone loss. The evolution of stratospheric temperatures over the next decade will be the determining factor for the amount of wintertime chemical ozone loss in the Arctic stratosphere. C1 Alfred Wegener Inst Polar & Marine Res, D-14401 Potsdam, Germany. European Ozone Res Coordinating Unit, Cambridge CB2 1EW, England. Norwegian Inst Air Res, Kjeller, Norway. FU Berlin, Inst Meteorol, D-12165 Berlin, Germany. USN, Res Lab, Washington, DC 20375 USA. Royal Netherlands Meteorol Inst, NL-3730 AE De Bilt, Netherlands. Leibniz Inst Atmospher Phys, D-18221 Kuhlungsborn, Germany. Inst Nacl Meteorol, Madrid 28071, Spain. Deutsch Wetterdienst, Observ Hohenpeissenberg, D-82383 Hohenpeissenberg, Germany. Inst Nacl Meteorol, Tenerife, Spain. Atmospher Environm Serv, Downsview, ON M3H 5T4, Canada. Royal Meteorol Inst, B-1180 Brussels, Belgium. Meteorol Observ Lindenberg, D-15864 Lindenberg, Germany. Cent Aerol Observ, Dolgoprudnyi 141700, Moscow Region, Russia. Univ Paris 06, Serv Aeron, CNRS, F-75230 Paris 05, France. NOAA, Climate Monitoring & Diagnost Lab, Ozone & Water Vapour Grp, Boulder, CO 80303 USA. Ctr Aerol, Inst Meteorol & Water Management, PL-95119 Legionowo, Poland. Univ Tokyo, Adv Sci & Technol Res Ctr, Meguro Ku, Tokyo 1538904, Japan. Univ Thessaloniki, Lab Atmospher Phys, Salonika 45006, Greece. Sodankyla Meteorol Observ, Sodankyla 99600, Finland. Danish Meteorol Inst, DK-2100 Copenhagen, Denmark. Meteorol Off, Wokingham RG40 3DN, Berks, England. Irish Meteorol Serv, Valentia Observ, Cahirciveen, County Kerry, Ireland. Meteorol Res Inst, Tsukuba, Ibaraki 3050052, Japan. Natl Inst Environm Studies, Tsukuba, Ibaraki 3050053, Japan. Inst Nacl Tecn Aerosp, Madrid 28850, Spain. NASA, Goddard Space Flight Ctr, Wallops Flight Facil, Wallops Island, VA 23337 USA. Czech Hydrometeorol Inst, Uppsala Air & Surface Observat Dept, Prague 14306, Czech Republic. Univ Athens, Dept Appl Phys, Athens 15784, Greece. Inst Pierre Simon Laplace, Serv Observat, F-91371 Verrieres Buisson, France. Swiss Meteorol Inst, CH-1530 Payerne, Switzerland. RP Schulz, A (reprint author), Alfred Wegener Inst Polar & Marine Res, POB 600149, D-14401 Potsdam, Germany. RI Rex, Markus/A-6054-2009; von der Gathen, Peter/B-8515-2009; Kondo, Yutaka/D-1459-2012; Varotsos, Costas/H-6257-2013; Cuevas, Emilio/L-2109-2013; OI Rex, Markus/0000-0001-7847-8221; von der Gathen, Peter/0000-0001-7409-1556; Varotsos, Costas/0000-0001-7215-3610; Cuevas, Emilio/0000-0003-1843-8302; Nakane, Hideaki/0000-0002-9032-6105; Harris, Neil/0000-0003-1256-3006 NR 17 TC 53 Z9 54 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 16 PY 2001 VL 106 IS D7 BP 7495 EP 7503 DI 10.1029/2000JD900653 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 423QZ UT WOS:000168189400022 ER PT J AU Callis, LB Natarajan, M Lambeth, JD AF Callis, LB Natarajan, M Lambeth, JD TI Solar-atmospheric coupling by electrons (SOLACE) 3. Comparisons of simulations and observations, 1979-1997, issues and implications SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MIDDLE ATMOSPHERE; ODD NITROGEN; PRECIPITATING ELECTRONS; COOLING RATES; POLAR OZONE; STRATOSPHERE; VARIABILITY; CYCLE; NOY; SPECTROSCOPY AB Several middle atmospheric simulations have been carried out from January 1979 to December 1997 including most effects important to stratospheric O-3 Results of these simulations for several species and species ratios have been compared in detail with observations made by the Halogen Occultation Experiment, the Polar Ozone and Aerosol Measurement II, the Total Ozone Mapping Spectrometer, the Jet Propulsion Laboratory Mark IV Interferometer, and during the Photochemistry of Ozone Loss in the Arctic Summer mission. For the simulation including all effects, comparisons of all species and ratios show excellent agreement. Comparisons of simulated sunset NO2 with and without the effects of energetic electron precipitation show excellent agreement with observations with the effects of the electrons included but poor agreement when they are excluded. The validated simulations indicate that the effects of a polar source of NOy must be included for an adequate simulation of stratospheric O-3 and NOy. A comparison of simulations, during the 11-year solar cycle, of the relative effects on O-3 of-solar UV flux variations and the energetic electron precipitation has been made. For global total O-3 the effects are comparable. For the global column above 25 km, the effects of energetic electron precipitation are significantly larger. The implications of, and some issues raised by, these findings are briefly discussed. 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. NR 49 TC 45 Z9 45 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 16 PY 2001 VL 106 IS D7 BP 7523 EP 7539 DI 10.1029/2000JD900615 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 423QZ UT WOS:000168189400025 ER PT J AU Jaffe, AH Ade, PAR Balbi, A Bock, JJ Bond, JR Borrill, J Boscaleri, A Coble, K Crill, BP de Bernardis, P Farese, P Ferreira, PG Ganga, K Giacometti, M Hanany, S Hivon, E Hristov, VV Iacoangeli, A Lange, AE Lee, AT Martinis, L Masi, S Mauskopf, PD Melchiorri, A Montroy, T Netterfield, CB Oh, S Pascale, E Piacentini, F Pogosyan, D Prunet, S Rabii, B Rao, S Richards, PL Romeo, G Ruhl, JE Scaramuzzi, F Sforna, D Smoot, GF Stompor, R Winant, CD Wu, JHP AF Jaffe, AH Ade, PAR Balbi, A Bock, JJ Bond, JR Borrill, J Boscaleri, A Coble, K Crill, BP de Bernardis, P Farese, P Ferreira, PG Ganga, K Giacometti, M Hanany, S Hivon, E Hristov, VV Iacoangeli, A Lange, AE Lee, AT Martinis, L Masi, S Mauskopf, PD Melchiorri, A Montroy, T Netterfield, CB Oh, S Pascale, E Piacentini, F Pogosyan, D Prunet, S Rabii, B Rao, S Richards, PL Romeo, G Ruhl, JE Scaramuzzi, F Sforna, D Smoot, GF Stompor, R Winant, CD Wu, JHP TI Cosmology from MAXIMA-1, BOOMERANG, and COBE DMR cosmic microwave background observations SO PHYSICAL REVIEW LETTERS LA English DT Article ID HUBBLE CONSTANT; POWER SPECTRUM; NUCLEOSYNTHESIS; UNIVERSE; CONSTRAINTS; PARAMETERS; SUPERNOVAE; RADIATION; SCALE AB Recent results from BOOMERANG-98 and MAXIMA-1, taken together with COBE DMR, provide consistent and high signal-to-noise measurements of the cosmic microwave background power spectrum at spherical harmonic multipole bands over 2 < l 800. Analysis of the combined data yields 68% (95%) confidence limits on the total density, Omega (tot) similar or equal to 1.11 +/- 0.07 ((+0.13)(-0.12)), the baryon density, Omega (b)h(2) similar or equal to 0.032(-0.004+)(0.005) ((+0.009)(-0.008)), and the scalar spectral tilt, n(s) similar or equal to 1.01(-0.07)(+0.09) ((+0.17)(-0.14)). These data are consistent with inflationary initial conditions for structure formation. Taken together with other cosmological observations, they imply the existence of both nonbaryonic dark matter and dark energy in the Universe. C1 Univ Calif Berkeley, Ctr Particle Astrophys, Berkeley, CA 94720 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Queen Mary Univ London, London E1 4NS, England. Univ Roma Tor Vergata, Dipartimento Fis, I-00173 Rome, Italy. Univ Calif Berkeley, Lawrence Berkeley Lab, Div Phys, Berkeley, CA 94720 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Toronto, Canadian Inst Theoret Astrophys, Toronto, ON M5S 3H8, Canada. Univ Calif Berkeley, Lawrence Berkeley Lab, Natl Energy Res Sci Comp Ctr, Berkeley, CA 94720 USA. IROE, CNR, Florence, Italy. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. CALTECH, Pasadena, CA 91125 USA. Univ Roma La Sapienza, Dipartimento Fis, Rome, Italy. Univ Oxford, Astrophys, NAPL, Oxford OX2 6HT, England. Inst Super Tecn, CENTRA, Lisbon, Portugal. Coll France, F-75231 Paris 05, France. Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. ENEA Ctr Ric Frascati, I-00044 Frascati, Italy. Univ Wales Coll Cardiff, Cardiff CF24 3YB, S Glam, Wales. Univ Toronto, Dept Phys & Astron, Toronto, ON M5S 3H8, Canada. Ist Nazl Geofis, Rome, Italy. Copernicus Astron Ctr, Warsaw, Poland. RP Jaffe, AH (reprint author), Univ Calif Berkeley, Ctr Particle Astrophys, Berkeley, CA 94720 USA. RI Jaffe, Andrew/D-3526-2009; Piacentini, Francesco/E-7234-2010; OI Piacentini, Francesco/0000-0002-5444-9327; WU, JIUN-HUEI/0000-0001-9608-7662; ROMEO, Giovanni/0000-0002-5535-7803; Hivon, Eric/0000-0003-1880-2733; Masi, Silvia/0000-0001-5105-1439; de Bernardis, Paolo/0000-0001-6547-6446 NR 32 TC 416 Z9 416 U1 1 U2 10 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD APR 16 PY 2001 VL 86 IS 16 BP 3475 EP 3479 DI 10.1103/PhysRevLett.86.3475 PG 5 WC Physics, Multidisciplinary SC Physics GA 422GH UT WOS:000168109800005 PM 11328002 ER PT J AU Hysom, D Pothen, A AF Hysom, D Pothen, A TI A scalable parallel algorithm for incomplete factor preconditioning SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE incomplete factorization; ILU; preconditioning; parallel preconditioning ID LINEAR-SYSTEMS; FACTORIZATIONS AB We describe a parallel algorithm for computing incomplete factor (ILU) preconditioners. The algorithm attains a high degree of parallelism through graph partitioning and a two-level ordering strategy. Both the subdomains and the nodes within each subdomain are ordered to preserve concurrency. We show through an algorithmic analysis and through computational results that this algorithm is scalable. Experimental results include timings on three parallel platforms for problems with up to 20 million unknowns running on up to 216 processors. The resulting preconditioned Krylov solvers have the desirable property that the number of iterations required for convergence is insensitive to the number of processors. C1 Old Dominion Univ, Norfolk, VA 23529 USA. NASA, ICASE, Langley Res Ctr, Hampton, VA 23681 USA. RP Hysom, D (reprint author), Old Dominion Univ, Norfolk, VA 23529 USA. OI Pothen, Alex/0000-0002-3421-3325 NR 37 TC 59 Z9 61 U1 0 U2 1 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 APR 16 PY 2001 VL 22 IS 6 BP 2194 EP 2215 DI 10.1137/S1064827500376193 PG 22 WC Mathematics, Applied SC Mathematics GA 430RB UT WOS:000168588400017 ER PT J AU Conley, CA Fritz-Six, KL Almenar-Queralt, A Fowler, VM AF Conley, CA Fritz-Six, KL Almenar-Queralt, A Fowler, VM TI Leiomodins: Larger members of the tropomodulin (Tmod) gene family SO GENOMICS LA English DT Article ID THYROID-ASSOCIATED OPHTHALMOPATHY; ACTIN-FILAMENTS; DILATED CARDIOMYOPATHY; TROPOMYOSIN-BINDING; SKELETAL-MUSCLE; POINTED ENDS; LOCALIZATION; PROTEIN; AUTOANTIGEN; EXPRESSION AB The 64-kDa autoantigen D1 or 1D, first identified as a potential autoantigen in Graves' disease, is similar to the tropomodulin (Tmod) family of actin filament pointed end-capping proteins. A novel gene with significant similarity to the 64-kDa human autoantigen D1 has been cloned from both humans and mice, and the genomic sequences of both genes have been identified. These genes form a subfamily closely related to the Tmods and are here named the Leiomodins (Lmods), Both Lmod genes display a conserved intron-exon structure, as do three Tmod genes, but the intron-exon structure of the Lmods and the Tmods is divergent. mRNA expression analysis indicates that the gene formerly known as the 64-kDa autoantigen D1 is most highly expressed in a variety of human tissues that contain smooth muscle, earning it the name smooth muscle Leiomodin (SM-Lmod; HGMW-approved symbol LMOD1). Transcripts encoding the novel Lmod gene are present exclusively in fetal and adult heart and adult skeletal muscle, and it is here named cardiac Leiomodin (C-Lmod; HGMW-approved symbol LMOD2), Human C-Lmod is located near the hypertrophic cardiomyopathy locus CMH6 on human chromosome 7q8, potentially implicating it in this disease. Our data demonstrate that the Lmods are evolutionarily related and display tissue-specific patterns of expression distinct from, but overlapping with, the expression of Tmod isoforms, (C) 2001 Academic Press. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Scripps Res Inst, Dept Cell Biol, La Jolla, CA 92037 USA. RP Conley, CA (reprint author), NASA, Ames Res Ctr, MS 239-11, Moffett Field, CA 94035 USA. FU NIGMS NIH HHS [GM-34225] NR 34 TC 68 Z9 73 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0888-7543 J9 GENOMICS JI Genomics PD APR 15 PY 2001 VL 73 IS 2 BP 127 EP 139 DI 10.1006/geno.2000.6501 PG 13 WC Biotechnology & Applied Microbiology; Genetics & Heredity SC Biotechnology & Applied Microbiology; Genetics & Heredity GA 428DU UT WOS:000168446700001 PM 11318603 ER PT J AU Goldberg, RA Pfaff, RF Holzworth, RH Schmidlin, FJ Voss, HD Tuzzolino, AJ Croskey, CL Mitchell, JD Friedrich, M Murtagh, D Witt, G Gumbel, J von Zahn, U Singer, W Hoppe, UP AF Goldberg, RA Pfaff, RF Holzworth, RH Schmidlin, FJ Voss, HD Tuzzolino, AJ Croskey, CL Mitchell, JD Friedrich, M Murtagh, D Witt, G Gumbel, J von Zahn, U Singer, W Hoppe, UP TI DROPPS: A study of the polar summer mesosphere with rocket, radar and lidar SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NOCTILUCENT CLOUDS; CHARGED DUST; MESOPAUSE; ECHOES; NLC-91 AB DROPPS (The Distribution and Role of Particles in the Polar Summer Mesosphere) was a highly coordinated international study conducted in July, 1999 from the Norwegian rocket range (Andoya, Norway). Two sequences of rockets were launched. Each included one NASA DROPPS payload, containing instruments to measure the electrodynamic and optical properties of dust/aerosol layers, accompanied by European payloads (MIDAS, Mini-MIDAS, and/or Mini-DUSTY) to study the same structures in a complementary manner. Meteorological rockets provided winds and temperature. ALOMAR lidars and radars (located adjacent to the launch site) monitored the mesosphere for noctilucent clouds (NLCs) and polar mesosphere summer echoes (PMSEs), respectively. EISCAT radars provided PMSE and related information at a remote site (Tromso, Norway). Sequence 1 (5-6 July) was launched into a strong PMSE with a weak NLC present; sequence 2 (14 July) occurred during a strong NLC with no PMSE evident. Here we describe program details along with preliminary results. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Washington, Seattle, WA 98195 USA. NASA, Goddard Space Flight Ctr, WFF, Wallops Island, VA 23337 USA. Taylor Univ, Upland, IN 46989 USA. Univ Chicago, Chicago, IL 60637 USA. Penn State Univ, University Pk, PA 16802 USA. Graz Tech Univ, Graz, Austria. Univ Stockholm, S-10691 Stockholm, Sweden. Leibniz Inst Atmospher Phys, D-18225 Kuhlungsborn, Germany. FFI, N-2007 Kjeller, Norway. RP Goldberg, RA (reprint author), NASA, Goddard Space Flight Ctr, Code 690, Greenbelt, MD 20771 USA. RI Goldberg, Richard /E-1881-2012; Pfaff, Robert/F-5703-2012; Murtagh, Donal/F-8694-2011 OI Pfaff, Robert/0000-0002-4881-9715; Murtagh, Donal/0000-0003-1539-3559 NR 18 TC 38 Z9 38 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 APR 15 PY 2001 VL 28 IS 8 BP 1407 EP 1410 DI 10.1029/2000GL012415 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 421LP UT WOS:000168066100001 ER PT J AU Schmidlin, FJ Schauer, AG AF Schmidlin, FJ Schauer, AG TI Mesospheric clouds and the neutral atmosphere during the 1999 DROPPS/MIDAS Campaign SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SUMMER AB Inflatable passive falling spheres launched in conjunction with the DROPPS/MIDAS campaign during July 1999 are used to infer thermal advection and its relationship to Polar Mesospheric Summer Echoes (PMSE) and Noctilucent Cloud (NLC) events. Hodograph analysis, although not new, is used at mesospheric altitudes where non-hydrostatic conditions may possibly inhibit useful results. Nonetheless, the concept of applying thermal advection to PMSE and NLC events is tried here with a possibility of interpreting neutral atmosphere measurements and their relationship with the electrodynamic environment. Although the material presented represents only results from the DROPPS/MIDAS campaign; it shows changes in the temperature structure within a few hours at the time of the PMSE event that indicate thermal advection may be connected to temperature changes of a few degrees. The warm advection between 80 and 86 km may be significantly related to the height of the PMSE, i.e., 85 km. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Observat Sci Branch, Wallops Island, VA 23337 USA. Sci & Engn Serv Inc, Observat Sci Branch, Wallops Flight Facil, Wallops Island, VA 23339 USA. RP Schmidlin, FJ (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Observat Sci Branch, Wallops Island, VA 23337 USA. NR 6 TC 5 Z9 5 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 APR 15 PY 2001 VL 28 IS 8 BP 1411 EP 1413 DI 10.1029/2000GL012422 PG 3 WC Geosciences, Multidisciplinary SC Geology GA 421LP UT WOS:000168066100002 ER PT J AU Mitchell, JD Croskey, CL Goldberg, RA AF Mitchell, JD Croskey, CL Goldberg, RA TI Evidence for charged aerosols and associated meter-scale structure in identified PMSE/NLC regions SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID DUST; MESOSPHERE AB Evidence for the existence of negatively charged aerosols/dust in PMSE/NLC regions has been obtained by the unique combination of rocket probes flown during the DROPPS Program. Simultaneous current measurements of charged aerosols, ions, and electrons were accomplished by using a configuration of blunt probes, Gerdien condenser, and DC Langmuir probe. The two blunt probes, with different fixed-bias voltages to discriminate the collection of mobile charge carriers, consistently demonstrated the presence of impacting negatively charged aerosols. Their occurrence coincided with an electron bite-out, thus confirming the associated loss process as aerosol attachment. C1 Penn State Univ, Dept Elect Engn, Commun & Space Sci Lab, University Pk, PA 16802 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Mitchell, JD (reprint author), Penn State Univ, Dept Elect Engn, Commun & Space Sci Lab, University Pk, PA 16802 USA. RI Goldberg, Richard /E-1881-2012 NR 7 TC 39 Z9 39 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 APR 15 PY 2001 VL 28 IS 8 BP 1423 EP 1426 DI 10.1029/2000GL012685 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 421LP UT WOS:000168066100005 ER PT J AU Croskey, CL Mitchell, JD Friedrich, M Torkar, KM Hoppe, UP Goldberg, RA AF Croskey, CL Mitchell, JD Friedrich, M Torkar, KM Hoppe, UP Goldberg, RA TI Electrical structure of PMSE and NLC regions during the DROPPS program SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MST RADAR AB The electrical structure of NLC/PMSE regions was investigated by different rocket-borne in situ probe techniques as part of the DROPPS program. Gerdien condenser measurements of very small mobility values suggest concentrations of positively charged aerosols/dust comparable to the density of more mobile positive ions at PMSE/NLC altitudes. Relative electron density values and associated large- and small-scale vertical structure measured by DC Langmuir probes revealed very deep (by a factor of 50) biteouts in PMSE/NLC regions. These biteouts were seen during strong and weak NLC conditions when PMSEs were either present or absent. C1 Penn State Univ, Dept Elect Engn, Commun & Space Sci Lab, University Pk, PA 16802 USA. Graz Tech Univ, Dept Commun & Wave Propagat, A-8010 Graz, Austria. Austrian Acad Sci, Inst Space Res, A-1010 Vienna, Austria. Forsvarets Forskningsingstitutt, Kjeller, Norway. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Croskey, CL (reprint author), Penn State Univ, Dept Elect Engn, Commun & Space Sci Lab, University Pk, PA 16802 USA. RI Goldberg, Richard /E-1881-2012 NR 9 TC 60 Z9 60 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 APR 15 PY 2001 VL 28 IS 8 BP 1427 EP 1430 DI 10.1029/2000GL012540 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 421LP UT WOS:000168066100006 ER PT J AU Pfaff, R Holzworth, R Goldberg, R Freudenreich, H Voss, H Croskey, C Mitchell, J Gumbel, J Bounds, S Singer, W Latteck, R AF Pfaff, R Holzworth, R Goldberg, R Freudenreich, H Voss, H Croskey, C Mitchell, J Gumbel, J Bounds, S Singer, W Latteck, R TI Rocket probe observations of electric field irregularities in the polar summer mesosphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID AEROSOLS; ECHOES AB Electric field wave measurements gathered on a sounding rocket flown in the presence of polar mesospheric summer echoes reveal a distinct layer of irregularities between 83 - 86 km with broadband amplitudes of > 10 mV/m rms. The waves are characterized by bursty, spiky waveforms with lower frequencies (similar to 10 Hz) dominant in the upper portion of the layer near 85 km and broader band emissions, extending to higher frequencies (similar to 1000 Hz) dominant in the lower portion of the layer near 83.5 km. The lower altitudes correspond to a region of weak optical emissions associated with a noctilucent cloud. The waves appear in and around regions where charged/neutral aerosols (1 - 10 nm) and large electron density depletions were observed. The irregularities likely result from a variety of processes including space charge inhomogeneities, mixed neutral and plasma motions, and complex effects associated with charged aerosols of varying sizes. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Washington, Seattle, WA 98195 USA. Taylor Univ, Upland, IN USA. Penn State Univ, University Pk, PA 16802 USA. Stockholm Univ, Dept Meteorol, S-10691 Stockholm, Sweden. Univ Iowa, Iowa City, IA USA. Leibniz Inst Atmospher Phys, Kuhlungsborn, Germany. RP Pfaff, R (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Goldberg, Richard /E-1881-2012; Pfaff, Robert/F-5703-2012 OI Pfaff, Robert/0000-0002-4881-9715 NR 12 TC 21 Z9 23 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 APR 15 PY 2001 VL 28 IS 8 BP 1431 EP 1434 DI 10.1029/2000GL012677 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 421LP UT WOS:000168066100007 ER PT J AU Holzworth, RH Pfaff, RF Goldberg, RA Bounds, SR Schmidlin, FJ Voss, HD Tuzzolino, AJ Croskey, CL Mitchell, JD von Cossart, G Singer, W Hoppe, UP Murtagh, D Witt, G Gumbel, J Friedrich, M AF Holzworth, RH Pfaff, RF Goldberg, RA Bounds, SR Schmidlin, FJ Voss, HD Tuzzolino, AJ Croskey, CL Mitchell, JD von Cossart, G Singer, W Hoppe, UP Murtagh, D Witt, G Gumbel, J Friedrich, M TI Large electric potential perturbations in PMSE during DROPPS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MESOSPHERE SUMMER ECHOES; NOCTILUCENT CLOUDS; POLAR MESOSPHERE; FIELDS; RADAR; AEROSOLS; NLC-91 AB Comprehensive vector electric field detectors were flown during the DROPPS rocket experiment to study electrodynamic processes near the mesopause. This paper will discuss the first DROPPS rocket flight, which penetrated a strong polar mesosphere summer echo (PMSE) event that also included a weak noctilucent cloud (NLC) layer. During this flight, strong potential perturbations were observed which at first appeared to be caused by large geophysical electric fields. However, as shown here, the potential perturbations resulted from the rocket wake, and were not caused by an environmental electric field. This result strongly differs from other previous in-situ experiments, which have reported large electric fields in PMSE regions. C1 Univ Washington, Dept Earth & Space Sci, Seattle, WA 98195 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, WFF, Wallops Island, VA 23337 USA. Taylor Univ, Sci Res Training Program, Upland, IN 46989 USA. Univ Chicago, Lab Astrophys & Space Res, Chicago, IL 60637 USA. Penn State Univ, University Pk, PA 16802 USA. Inst Atmospher Phys, D-18221 Kuhlungsborn, Germany. Norwegian Def Res Estab, Div Elect, N-2007 Kjeller, Norway. Univ Stockholm, Dept Meteorol, Arrhenius Lab, S-10691 Stockholm, Sweden. Graz Tech Univ, Inst Nachrichtentechn & Wellenausbreitung, Graz, Austria. RP Holzworth, RH (reprint author), Univ Washington, Dept Earth & Space Sci, Box 351650, Seattle, WA 98195 USA. RI Goldberg, Richard /E-1881-2012; Pfaff, Robert/F-5703-2012; Murtagh, Donal/F-8694-2011 OI Pfaff, Robert/0000-0002-4881-9715; Murtagh, Donal/0000-0003-1539-3559 NR 19 TC 21 Z9 21 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 APR 15 PY 2001 VL 28 IS 8 BP 1435 EP 1438 DI 10.1029/2000GL012517 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 421LP UT WOS:000168066100008 ER PT J AU Sandel, BR King, RA Forrester, WT Gallagher, DL Broadfoot, AL Curtis, CC AF Sandel, BR King, RA Forrester, WT Gallagher, DL Broadfoot, AL Curtis, CC TI Initial results from the IMAGE extreme ultraviolet imager SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID WHISTLER EVIDENCE; ELECTRON-DENSITY; MAGNETOSPHERE; PLASMASPHERE; RADIATION; MODEL; IONS AB The Extreme Ultraviolet Imager (EUV) of the IMAGE mission is providing the first global images of the He+ distribution in Earth's plasmasphere. The EUV instrument images the He+ resonance line emission at 30.4 nm at a time resolution of 10 minutes and a spatial resolution of 0.1 R-E Each image encompasses the entire plasmasphere in a single frame, to permit study of the structure and dynamics of the plasmasphere in its entirety. Here we survey several of the most striking features of the plasmasphere as seen by EUV. These features include convection tails, depleted regions that we call "voids," isolated magnetic flux tubes filled to higher He+ density than their neighbors, and "shoulders" in the He+ distribution. C1 Univ Arizona, Lunar & Planetary Lab W, Tucson, AZ 85721 USA. Natl Space Sci & Technol Ctr, Dept Space Sci, NASA, Marshall Space Flight Ctr, Huntsville, AL 35805 USA. Univ Arizona, Dept Phys, Tucson, AZ 85721 USA. RP Sandel, BR (reprint author), Univ Arizona, Lunar & Planetary Lab W, 1040 E 4th St Room 901, Tucson, AZ 85721 USA. NR 25 TC 134 Z9 135 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 15 PY 2001 VL 28 IS 8 BP 1439 EP 1442 DI 10.1029/2001GL012885 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 421LP UT WOS:000168066100009 ER PT J AU Fainberg, J Osherovich, VA Stone, RG AF Fainberg, J Osherovich, VA Stone, RG TI Pioneer Venus Orbiter observations of a solar wind quasi-invariant SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The recently suggested solar wind quasi-invariant [QI equivalent to (B-2/8 pi)/(rhoupsilon(2)/2)} is a combination of magnetic field strength B, plasma density rho and solar wind speed upsilon. Measured in the solar wind near the Earth, the median value of QI was shown to be a reliable index of solar activity for the 28 year period holding a linear relation with sunspot numbers (SSN) with a high correlation coefficient (cc) of 0.98 [Osherovich, Fainberg and Stone, 1999]. Here,using hourly data from the Pioneer Venus Orbiter for the period from 1978-1988, we demonstrate that QI near Venus also closely follow SSN with a correlation coefficient of 0.94 for the yearly mean values. We found that the calibration coefficient between QI(Venus) and QI(Earth) is slightly larger than unity, namely, QI(Venus) = a*(.)QI(Earth) where a* = 1.134 +/- 0.001. We suggest that, for any point in the heliosphere, QI can be viewed as a useful measure of solar activity. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Fainberg, J (reprint author), NASA, Goddard Space Flight Ctr, Code 692, Greenbelt, MD 20771 USA. NR 6 TC 10 Z9 10 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 APR 15 PY 2001 VL 28 IS 8 BP 1447 EP 1449 DI 10.1029/2000GL012160 PG 3 WC Geosciences, Multidisciplinary SC Geology GA 421LP UT WOS:000168066100011 ER PT J AU Kaufman, YJ Tanre, D Dubovik, O Karnieli, A Remer, LA AF Kaufman, YJ Tanre, D Dubovik, O Karnieli, A Remer, LA TI Absorption of sunlight by dust as inferred from satellite and ground-based remote sensing SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MINERAL AEROSOLS; NETWORK; AERONET AB Dust absorption of solar radiation is not well known due to limitations in the accuracy of in situ measurements. Here we report two new independent remote sensing techniques that provide sensitive measurements of dust absorption. One uses satellite spectral measurements, the second ground based sky measurements. Both techniques demonstrate that Saharan dust absorption of solar radiation is several times smaller than the current international standards. For example, at wavelength of 0.64 mum the dust single scattering albedo is reported here as 0.97 +/-0.02 rather than 0.87 +/-0.04 in recent review. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Sci & Tech Lille Flandres Artois, CNRS, Opt Atmospher Lab, Villeneuve Dascq, France. Sci Syst & Applicat Inc, Lanham, MD 20706 USA. Ben Gurion Univ Negev, J Blaustein Inst Desert Res, IL-84990 Sede Boker, Israel. RP Kaufman, YJ (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Dubovik, Oleg/A-8235-2009 OI Dubovik, Oleg/0000-0003-3482-6460 NR 21 TC 223 Z9 230 U1 0 U2 10 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 APR 15 PY 2001 VL 28 IS 8 BP 1479 EP 1482 DI 10.1029/2000GL012647 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 421LP UT WOS:000168066100019 ER PT J AU Ben Liley, J Rosen, JM Kjome, NT Jones, NB Rinsland, CP AF Ben Liley, J Rosen, JM Kjome, NT Jones, NB Rinsland, CP TI Springtime enhancement of upper tropospheric aerosol at 45 degrees S SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EXPERIMENT-II MEASUREMENTS; STRATOSPHERIC-AEROSOL AB Monthly sonde data for Lauder in Central Otago, New Zealand show profiles of aerosol backscatter from the surface to over 30 km altitude. The tropospheric data vary by season, with greater aerosol backscatter throughout the free troposphere in springtime. Aerosol mixing ratios in layers in the upper troposphere at these times are often much higher than anywhere else above the boundary layer, suggesting that they arise from horizontal transport. Ozone measurements from the sonde show correspondence in vertical structure to the backscatter data and also seasonal enhancement. The latter correlates with aerosol, but competing causes of ozone enhancement make the correspondence indistinct. High concentrations of carbon monoxide are observed by Fourier transform spectroscopy in spring, and altitude profiles derived from line shape suggest that the peak in CO occurs in the same altitude range as the aerosol enhancement. C1 Natl Inst Water & Atmospher Res, Lauder, Cent Otago, New Zealand. Univ Wyoming, Dept Phys & Astron, Laramie, WY 82071 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Ben Liley, J (reprint author), Natl Inst Water & Atmospher Res, Lauder, Cent Otago, New Zealand. RI Jones, Nicholas/G-5575-2011 OI Jones, Nicholas/0000-0002-0111-2368 NR 14 TC 0 Z9 0 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 APR 15 PY 2001 VL 28 IS 8 BP 1495 EP 1498 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 421LP UT WOS:000168066100023 ER PT J AU Shindell, DT AF Shindell, DT TI Climate and ozone response to increased stratospheric water vapor SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MIDDLE ATMOSPHERE; DOUBLED CO2; TRENDS; DEPLETION AB Stratospheric water vapor abundance affects ozone, surface climate, and stratospheric temperatures. From 30-50 km altitude, temperatures show global decreases of 3-6 It over recent decades. These may be a proxy for water vapor increases, as the GISS climate model reproduces these trends only when stratospheric water vapor is allowed to increase. Observations suggest that stratospheric water vapor is indeed increasing, though measurements are extremely limited in either spatial coverage or duration. Model results suggest that the observed changes may be part of a global, long-term trend. Furthermore, the required water vapor change cannot be accounted for by increased stratospheric production, suggesting that climate change may be altering tropospheric input. The calculated water vapor increase contributes an additional approximate to 24% (approximate to0.2 W/m(2)) to the global warming from well-mixed greenhouse gases over the past two decades. Observed ozone depletion is also better reproduced when destruction due to increased water vapor is included. If the trend continues, it could increase future global warming and impede stratospheric ozone recovery. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, New York, NY USA. RP Shindell, DT (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. RI Shindell, Drew/D-4636-2012 NR 24 TC 85 Z9 88 U1 0 U2 4 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 APR 15 PY 2001 VL 28 IS 8 BP 1551 EP 1554 DI 10.1029/1999GL011197 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 421LP UT WOS:000168066100037 ER PT J AU Seki, MP Polovina, JJ Brainard, RE Bidigare, RR Leonard, CL Foley, DG AF Seki, MP Polovina, JJ Brainard, RE Bidigare, RR Leonard, CL Foley, DG TI Biological enhancement at cyclonic eddies tracked with GOES thermal imagery in Hawaiian waters SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MESOSCALE EDDY; UPPER OCEAN; PACIFIC; SEA AB In November 1999, ship and satellite platforms were used to track, target and map the vertical and horizontal structure of two cyclonic eddies in the lee of Hawaii. Depth-integrated nitrate+nitrite levels within the photic zone of the eddy cores were 3- to 15- fold higher than those observed for control stations. The depth and magnitude of the deep chlorophyll maximum were significantly elevated in the more mature of the two eddies. HPLC analyses revealed that the enhanced chlorophyll was largely contributed by chromophyte microalgae. Modeled primary productivity rates were up to twofold higher at the stations within the eddies. C1 NOAA, Natl Marine Fisheries Serv, SW Fisheries Sci Ctr, Honolulu Lab, Honolulu, HI 96822 USA. Univ Hawaii, Dept Oceanog, SOEST, Honolulu, HI 96822 USA. Univ Hawaii, Joint Inst Marine & Atmospher Res, SOEST, Honolulu, HI 96822 USA. RP Seki, MP (reprint author), NOAA, Natl Marine Fisheries Serv, SW Fisheries Sci Ctr, Honolulu Lab, 2570 Dole St, Honolulu, HI 96822 USA. NR 14 TC 87 Z9 91 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 15 PY 2001 VL 28 IS 8 BP 1583 EP 1586 DI 10.1029/2000GL012439 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 421LP UT WOS:000168066100045 ER PT J AU Lakshmi, V Susskind, J AF Lakshmi, V Susskind, J TI Utilization of satellite data in land surface hydrology: sensitivity and assimilation SO HYDROLOGICAL PROCESSES LA English DT Article DE hydrological modeling; satellite data; sensitivity; assimilation ID ATMOSPHERE TRANSFER SCHEME; LOW-LEVEL PARAMETERS; SOIL-MOISTURE; SEQUENTIAL ASSIMILATION; AIR-TEMPERATURE; MODEL; CLIMATE; TRANSPIRATION; VARIABLES; ERRORS AB This paper investigates the sensitivity of potential evapotranspiration to input meteorological variables, i.e. surface air temperature and surface vapor pressure. The sensitivity studies have been carried out for a wide range of land surface variables such as wind speed, leaf area index and surface temperatures, Errors in the surface air temperature and surface vapor pressure result in errors of different signs in the computed potential evapotranspiration. This result has implications for use of estimated values from satellite data or analysis of surface air temperature and surface vapor pressure in large-scale hydrological modeling. The comparison of cumulative potential evapotranspiration estimates using ground observations and satellite observations over Manhattan, Kansas for a period of several months shows a variable difference between the two estimates, The use of satellite estimates of surface skin temperature in hydrological modeling to update the soil moisture using a physical adjustment concept is studied in detail, including the extent of changes in soil moisture resulting from the assimilation of surface skin temperature. The soil moisture of the 1 cm surface layer was adjusted by 0.09 mm over a 10-day period as a result of a 3 K difference between the predicted and the observed surface temperature. This is a considerable amount given the fact that the top layer can hold only 5 mm of moisture. Copyright (C) 2001 John Wiley & Sons, Ltd. C1 Univ S Carolina, Dept Geol Sci, Columbia, SC 29208 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Lakshmi, V (reprint author), Univ S Carolina, Dept Geol Sci, Columbia, SC 29208 USA. RI Lakshmi, Venkat/I-3078-2016 OI Lakshmi, Venkat/0000-0001-7431-9004 NR 34 TC 10 Z9 10 U1 1 U2 4 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0885-6087 J9 HYDROL PROCESS JI Hydrol. Process. PD APR 15 PY 2001 VL 15 IS 5 BP 877 EP 892 DI 10.1002/hyp.193 PG 16 WC Water Resources SC Water Resources GA 418VK UT WOS:000167914700010 ER PT J AU Li, XF Zheng, QN Pichel, WG Yan, XH Liu, WT Clemente-Colon, P AF Li, XF Zheng, QN Pichel, WG Yan, XH Liu, WT Clemente-Colon, P TI Analysis of coastal lee waves along the coast of Texas observed in advanced very high resolution radiometer images SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID ATMOSPHERE AB We examine a group of wave-like cloud patterns that occurred along the coast of Texas on a National Oceanic and Atmospheric Administration satellite advanced very high resolution radiometer IR images taken on January 22, 1999. These wave-like cloud patterns were interpreted to be signatures of a coastal lee wave packet on the basis of simultaneous field observations and theories developed by Zheng et al. [1998a]. The wave packet contains 13 waves with crest lines generally parallel to the coastline. The lengths of leading wave crest lines are longer than 500 km. The average wavelength is 9.5 km, ranging from 6.2 to 14.7 km. The width of the horizontal distribution band of the wave packet is as wide as 113 km. This case represents the most energetic coastal lee wave packet that has ever been reported. C1 NOAA, NESDIS, Camp Springs, MD 20746 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Delaware, Coll Marine Studies, Newark, DE 19716 USA. RP Li, XF (reprint author), NOAA, NESDIS, E-RA3,Room 102,WWBG,5200 Auth Rd, Camp Springs, MD 20746 USA. RI Clemente-Colon, Pablo/F-5581-2010; Zheng, Quanan/F-9025-2010; Pichel, William/F-5619-2010; Li, Xiaofeng/B-6524-2008 OI Pichel, William/0000-0001-6332-0149; Li, Xiaofeng/0000-0001-7038-5119 NR 13 TC 16 Z9 16 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 APR 15 PY 2001 VL 106 IS C4 BP 7017 EP 7025 DI 10.1029/1999JC000019 PG 9 WC Oceanography SC Oceanography GA 422UJ UT WOS:000168137400013 ER PT J AU Su, WY Suzuki, M AF Su, WY Suzuki, M TI Evaluation of star in the UV region for the application of GCOM-A1/ODUS SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article DE ODUS; STAR; MODTRAN ID DISCRETE-ORDINATE-METHOD; RADIATIVE-TRANSFER; SCATTERING; ATMOSPHERES; OCLO AB Radiative transfer code plays an important role in climate study and remote sensing by acting as a tool for calculating the radiation received by the land surface and by remote sensors. Though there are many radiative transfer codes available, little work has been done to compare them. The Ozone Dynamics Ultraviolet Spectrometer (ODUS) is one of the successors to TOMS and is the core instrument for GCOM-A1 project. ODUS is a spectrometer to measure the ultraviolet (UV) band from; 306 to 420 nm with a spectral step of 0.5 nm. The STAR code is one of the candidate codes for the ODUS retrieval algorithm and was compared with MODTRAN4.0 to test its accuracy. The comparison revealed major discrepancies between the original STAR and MODTRAN4.0. After the solar irradiance data in STAR was modified and the wavenumber was used for solar irradiance calculation, the relative differences that appear like spikes in the spectral domain were greatly reduced. However, relative differences in the UV-B band are still a bit large (up to +/- 6%) and spikes remain. Examining these two codes, we found that the ozone cross section data used in STAR differs from that in MODTRAN4.0 due to a 15 cm(-1) shift toward higher wavenumbers. The relative differences between STAR and MODTRAN4.0 were reduced to 2% for wavelengths exceeding 310 nm. For wavelengths shorter than 310 nm, however, the differences increased as wavelengths decreased and reached 5.5% at 300 nm. This resulted from dividing by small radiances because of strong ozone absorption. Increasing the number of atmospheric layers from 36 to 50 in MODTRAN4.0 resulted in differences of less than 2% for wavelengths exceeding 306 nm and 4.5% at 300 nm. The STAR code uses a fitting formula for Rayleigh optical depth calculation that may significantly influence the precision in the UV band. It is modified by using an accurate calculation of the Rayleigh optical depth instead. The relative differences from the fitting formula and the accurate calculation of the Rayleigh optical depth can be as large as 0.5% at 300 nm. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. Natl Space Dev Agcy Japan, Earth Observ Res Ctr, Minato Ku, Tokyo 1060032, Japan. RP Su, WY (reprint author), Hampton Univ, Ctr Atmospher Sci, Hampton, VA 23668 USA. NR 32 TC 0 Z9 0 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 APR 15 PY 2001 VL 69 IS 2 BP 205 EP 216 DI 10.1016/S0022-4073(00)00077-7 PG 12 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 411FD UT WOS:000167486700007 ER PT J AU Moreau, G Boissoles, J Le Doucen, R Boulet, C Tipping, RH Ma, Q AF Moreau, G Boissoles, J Le Doucen, R Boulet, C Tipping, RH Ma, Q TI Experimental and theoretical study of the collision-induced fundamental absorption spectra of N-2-O-2 and O-2-N-2 pairs SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article DE collision-induced absorption; oxygen-nitrogen pairs; fundamental vibration-rotational bands ID QUADRUPOLE-MOMENT FUNCTIONS; TEMPERATURE-DEPENDENCE; N2-N2 PAIRS; N-2; BAND; HF AB New experimental and theoretical studies of the collision-induced fundamental absorption spectra of N-2-O-2 and O-2-N-2 pairs, where the first molecule makes the vibrational transition, are presented for a range of temperatures. Most of the absorption arises from the long-range quadrupolar and hexadecapolar mechanisms for which accurate matrix elements are available from other experimental measurements or from ab initio calculations. As in previous studies for N-2-N-2 and O-2-O-2, we vary the molecular matrix elements and the coefficients of the short-range induced dipole moments within realistic limits to obtain the best global fit to the temperature-dependent integrated intensities for all the experimental data. This procedure provides a more stringent test of the theory than the previous studies in which the parameters for N-2 and O-2 were optimized independently. Using the parameters thus determined, we then calculate the spectral profiles assuming the line shapes calculated quantum mechanically for N-2. The agreement between theoretical and experimental profiles is good, but discrepancies in the plateau region of the S-branch, which we attribute to metastable dimer effects, and in the wings of the bands, which we attribute to the neglect of line mixing and higher-order induction mechanisms, still remain. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. Univ Paris Sud, CNRS, Photophys Mol Lab, F-91405 Orsay, France. Univ Rennes 1, Unite Mixte Rech PALMS, F-35042 Rennes, France. Columbia Univ, Dept Appl Phys, New York, NY 10025 USA. Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. RP Tipping, RH (reprint author), Univ Alabama, Dept Phys & Astron, 206 Gallalee,Box 870324, Tuscaloosa, AL 35487 USA. NR 19 TC 14 Z9 14 U1 1 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 APR 15 PY 2001 VL 69 IS 2 BP 245 EP 256 DI 10.1016/S0022-4073(00)00082-0 PG 12 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 411FD UT WOS:000167486700010 ER PT J AU Stewart, ED Cohn, JD AF Stewart, ED Cohn, JD TI Inflationary models with a flat potential enforced by non-Abelian discrete gauge symmetries SO PHYSICAL REVIEW D LA English DT Article ID COSMOLOGICAL MODULI PROBLEM; SUPERHEAVY DARK-MATTER; SUPERSYMMETRY BREAKING THEORIES; AFFLECK-DINE BARYOGENESIS; LARGE-SCALE STRUCTURE; THERMAL INFLATION; HYBRID INFLATION; OBSERVATIONAL CONSTRAINTS; DENSITY PERTURBATIONS; QUANTUM CORRECTIONS AB Non-Abelian discrete gauge symmetries can provide the inflaton with a flat potential even when one takes into account gravitational strength effects. The discreteness of the symmetries also provide special field values where inflation can end via a hybrid-type mechanism. An interesting feature of this method is that it can naturally lead to extremely flat potentials and so, in principle, to inflation at unusually low energy scales. Two examples of effective field theories with this mechanism are given: one with a hybrid exit and one with a mutated hybrid exit. They include an explicit example in which the single field consistency condition is violated. C1 NASA, Fermilab Astrophys Grp, FNAL, Batavia, IL 60510 USA. Korea Adv Inst Sci & Technol, Dept Phys, Taejon 305701, South Korea. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Stewart, ED (reprint author), NASA, Fermilab Astrophys Grp, FNAL, Batavia, IL 60510 USA. EM ewan@kaist.ac.kr; jcohn@cfa.harvard.edu RI Stewart, Ewan/C-1565-2011 NR 70 TC 15 Z9 15 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 APR 15 PY 2001 VL 63 IS 8 AR 083519 DI 10.1103/PhysRevD.63.083519 PG 11 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 423XQ UT WOS:000168203400028 ER PT J AU Merayo, JMG Primdahl, F Brauer, P Risbo, T Olsen, N Sabaka, T AF Merayo, JMG Primdahl, F Brauer, P Risbo, T Olsen, N Sabaka, T TI The orthogonalization of magnetic systems SO SENSORS AND ACTUATORS A-PHYSICAL LA English DT Article DE magnetic systems; calibration; instrumentation; non-orthogonal systems ID FLUXGATE SENSOR; MAGNETOMETER; SATELLITE AB The construction of an orthogonal reference frame based on a set of three skew axes for a magnetic coil system and a magnetic sensor is discussed and presented. For a skew system, it is possible to define the coil axes and the magnetic axes as a dual set of axes that are linked to the system. Therefore, one orthogonal reference frame can be identified from the coil axes and another from the magnetic axes. Although this representation is not unique, it is the most intuitive visual representation as it is shown. The parametrizations based on the operation of the fluxgate transducer for the magnetic sensors compact spherical coil (CSC) (Orsted satellite) and compact detector coil (CDC) (Astrid-2 satellite) are analyzed and identified. In principle, only the transformation matrix that orthogonalizes the sensor is needed, but it is customary to express this matrix as a function of some non-orthogonal angles. Therefore, most relevant conventions from the literature are presented for comparison. All the representations agree for the case of small angle approximation, which is valid for most sensors. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Tech Univ Denmark, DK-2800 Lyngby, Denmark. Danish Space Res Inst, DK-2100 Copenhagen OE, Denmark. Univ Copenhagen, Dept Geophys, DK-2100 Copenhagen O, Denmark. NASA, Goddard Space Flight Ctr, Geodynam Branch, Greenbelt, MD 20771 USA. RP Merayo, JMG (reprint author), Tech Univ Denmark, Bldg 327, DK-2800 Lyngby, Denmark. RI Olsen, Nils/H-1822-2011; Sabaka, Terence/D-5618-2012 OI Olsen, Nils/0000-0003-1132-6113; NR 28 TC 11 Z9 12 U1 1 U2 8 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 APR 15 PY 2001 VL 89 IS 3 BP 185 EP 196 DI 10.1016/S0924-4247(00)00515-X PG 12 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 417QJ UT WOS:000167845400002 ER PT J AU Mallis, MM Neri, DF Oyung, R Colletti, L Nguyen, T Dinges, DF AF Mallis, MM Neri, DF Oyung, R Colletti, L Nguyen, T Dinges, DF TI Factors associated with behavioral alertness in pilots flying simulated night flights SO SLEEP LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Ames, IA 50011 USA. San Jose State Univ, San Jose, CA 95192 USA. Univ Penn, Philadelphia, PA 19104 USA. NR 1 TC 2 Z9 2 U1 0 U2 0 PU AMER ACAD SLEEP MEDICINE PI ROCHESTER PA 6301 BANDEL RD, STE 101, ROCHESTER, MN 55901 USA SN 0161-8105 J9 SLEEP JI Sleep PD APR 15 PY 2001 VL 24 SU S MA 202 BP A123 EP A124 PG 2 WC Clinical Neurology; Neurosciences SC Neurosciences & Neurology GA 424KF UT WOS:000168230900204 ER PT J AU Rosekind, MR Neri, DF Gregory, KB Mallis, MM Bowman, SL Oyung, RL AF Rosekind, MR Neri, DF Gregory, KB Mallis, MM Bowman, SL Oyung, RL TI A NASA education and training module on alertness management: A survey of implementation and application SO SLEEP LA English DT Meeting Abstract C1 Off Naval Res, Arlington, VA USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Raytheon STX, Lexington, MA USA. San Jose State Univ, San Jose, CA 95192 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER ACAD SLEEP MEDICINE PI ROCHESTER PA 6301 BANDEL RD, STE 101, ROCHESTER, MN 55901 USA SN 0161-8105 J9 SLEEP JI Sleep PD APR 15 PY 2001 VL 24 SU S MA 737 BP A415 EP A416 PG 2 WC Clinical Neurology; Neurosciences SC Neurosciences & Neurology GA 424KF UT WOS:000168230900735 ER PT J AU Levenson, NA Weaver, KA Heckman, TM AF Levenson, NA Weaver, KA Heckman, TM TI The Seyfert-starburst connection in X-rays. I. The data SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE galaxies : Seyfert; X-rays : galaxies ID BROAD-LINE REGIONS; ACTIVE GALACTIC NUCLEI; ASCA OBSERVATIONS; NGC 7582; BLACK-HOLE; 2 GALAXIES; STELLAR POPULATION; SPIRAL GALAXIES; STAR-FORMATION; H-I AB We analyze X-ray spectra and images of a sample of Seyfert 2 galaxies that unambiguously contain starbursts, based on their optical and UV characteristics. Although all sample members contain active galactic nuclei (AGNs), supermassive black holes or other related processes at the galactic centers alone cannot account for the total X-ray emission in all instances. Eleven of the 12 observed galaxies are significantly resolved with the ROSAT High Resolution Imager, while six of the eight sources observed with the lower resolution Position Sensitive Proportional Counter also appear extended on larger scales. The X-ray emission is extended on physical scales of 10 kpc and greater, which we attribute to starburst-driven outflows and supernova heating of the interstellar medium. Spectrally, a physically motivated composite model of the X-ray emission that includes a heavily absorbed (N-H > 10(23) cm(-2)) nuclear component (the AGN), power-law-like scattered AGN flux, and a thermal starburst describes this sample well. Half the sample exhibit iron K alpha lines, which are typical of AGNs. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Levenson, NA (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. NR 70 TC 45 Z9 45 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0067-0049 EI 1538-4365 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD APR 13 PY 2001 VL 133 IS 2 BP 269 EP 295 DI 10.1086/320355 PN 1 PG 27 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 421FQ UT WOS:000168054500001 ER PT J AU Wehrle, AE Piner, BG Unwin, SC Zook, AC Xu, W Marscher, AP Terasranta, H Valtaoja, E AF Wehrle, AE Piner, BG Unwin, SC Zook, AC Xu, W Marscher, AP Terasranta, H Valtaoja, E TI Kinematics of the Parsec-scale relativistic jet in quasar 3C 279: 1991-1997 SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE galaxies : active; galaxies : jets; quasars : individual (3C 279); radiation mechanisms : nonthermal; radio continuum : galaxies ID EXTRAGALACTIC RADIO-SOURCES; ACTIVE GALACTIC NUCLEI; FLUX-DENSITY VARIATIONS; LONG-BASELINE INTERFEROMETRY; SPACE VLBI OBSERVATIONS; GAMMA-RAY SOURCES; HIGH-ENERGY FLARE; 3C 279; BRIGHTNESS TEMPERATURE; MULTIWAVELENGTH OBSERVATIONS AB We present results of long-term high-frequency VLBI monitoring of the relativistic jet in 3C 279, consisting of 18 epochs at 22 GHz from 1991 to 1997 and 10 epochs at 43 GHz from 1995 to 1997. Three major results of this study are apparent speeds measured for six superluminal components range from 4.8c to 7.5c (H(0) = 70 km s(-1) Mpc(-1), q(0) = 0.1), variations in the total radio flux are due primarily to changes in the VLBI core flux, and the uniform-sphere brightness temperature of the VLBI core is similar to1 x 10(13) K at 22 GHz after 1995, one of the highest direct estimates of a brightness temperature. If the variability brightness temperature measured for 3C 279 by & Valtaoja is an actual Lahteenmaki value and not a lower limit, then the rest-frame brightness temperature of 3C 279 is quite high and limited by inverse Compton effects rather than equipartition. The parsec-scale morphology of 3C 279 consists of a bright, compact VLBI core, a jet component (C4) that moved from similar to2 to similar to3.5 mas from the core during the course of our monitoring, and an inner jet that extends from the core to a stationary component, C5, at similar to1 mas from the core. Component C4 followed a curved path, and we reconstruct its three-dimensional trajectory using polynomial fits to its position versus time. Component C5 faded with time, possibly due to a previous interaction with C4 similar to interactions seen in simulations by et al. Components in the inner jet are relatively short lived and fade by the time they reach similar to1 Gomez mas from the core. The components have different speeds and position angles from each other, but these differences do not match the differences predicted by the precession model of Abraham & Carrara. Although VLBI components were born about six months prior to each of the two observed gamma -ray high states, the sparseness of the gamma -ray data prevents a statistical analysis of possible correlations. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Whittier Coll, Dept Phys & Astron, Whittier, CA 90608 USA. Pomona Coll, Dept Phys & Astron, Claremont, CA 91711 USA. CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Boston Univ, Inst Astrophys Res, Boston, MA 02215 USA. Metsahovi Radio Observ, Kylmala 02540, Finland. Tuorla Observ, FIN-21500 Piikkio, Finland. Univ Turku, Dept Phys, FIN-20100 Turku, Finland. RP Wehrle, AE (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM Ann.E.Wehrle@jpl.nasa.gov; B.G.Piner@jpl.nasa.gov; Stephen.C.Unwin@jpl.nassa.gov; azook@pomona.edu; marscher@bu.edu; hte@kurp.hut.fi; valtaoja@deneb.astro.utu.fi NR 76 TC 54 Z9 55 U1 1 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD APR 13 PY 2001 VL 133 IS 2 BP 297 EP 320 DI 10.1086/320353 PN 1 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 421FQ UT WOS:000168054500002 ER PT J AU Lean, J Rind, D AF Lean, J Rind, D TI Earth's response to a variable sun SO SCIENCE LA English DT Editorial Material ID CLIMATE-CHANGE; UNITED-STATES; VARIABILITY; SOLAR; TEMPERATURE; IRRADIANCE; DROUGHT; SIGNALS; RECORD; OZONE C1 USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Lean, J (reprint author), USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. OI Lean, Judith/0000-0002-0087-9639 NR 26 TC 67 Z9 76 U1 2 U2 3 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 APR 13 PY 2001 VL 292 IS 5515 BP 234 EP 236 DI 10.1126/science.1060082 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 421QA UT WOS:000168074000033 PM 11305317 ER PT J AU Allen, SW Fabian, AC Johnstone, RM Arnaud, KA Nulsen, PEJ AF Allen, SW Fabian, AC Johnstone, RM Arnaud, KA Nulsen, PEJ TI ASCA and ROSAT observations of nearby cluster cooling flows SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE galaxies : clusters : general; cooling flows; intergalactic medium; X-rays : galaxies ID INTRACLUSTER MEDIUM ENRICHMENT; RAY-LUMINOUS CLUSTERS; FAR-INFRARED EMISSION; FLUX-LIMITED SAMPLE; X-RAY; STAR-FORMATION; GALAXY CLUSTERS; COLD CLOUDS; METALLICITY GRADIENTS; PERSEUS CLUSTER AB We present a detailed analysis of the X-ray properties of the cooling flows in a sample of nearby, X-ray-bright clusters of galaxies using high-quality ASCA spectra and ROSAT X-ray images. We demonstrate the need for multiphase models to consistently explain the spectral and imaging X-ray data for the clusters. The mass deposition rates of the cooling flows, independently determined from the ASCA spectra and ROSAT images, exhibit reasonable agreement. We confirm the presence of intrinsic X-ray absorption in the clusters using a variety of spectral models. We also report detections of 100-mum infrared emission, spatially coincident with the cooling flows, in several of the systems studied. The observed infrared fluxes and flux limits are in good agreement with the predicted values owing to reprocessed X-ray emission from the cooling flows. We present precise measurements of the abundances of iron, magnesium, silicon and sulphur in the central regions of the Virgo and Centaurus clusters, Our results firmly favour models in which a high mass fraction (70-80 per cent) of the iron in the X-ray gas in these regions originates from Type Ia supernovae. Finally, we present a series of methods which may be used to estimate the ages of cooling flows from Xray data. The results for the present sample of clusters indicate ages of between 2.5 and 7 Gyr. If the ages of cooling flows are primarily set by subcluster merger events, then our results suggest that in the largest clusters, mergers with subclusters with masses of similar to 30 per cent of the final cluster mass are likely to disrupt cooling flows. C1 Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Wollongong, Dept Engn Phys, Wollongong, NSW 2522, Australia. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Allen, SW (reprint author), Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England. NR 94 TC 88 Z9 89 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD APR 11 PY 2001 VL 322 IS 3 BP 589 EP 613 DI 10.1046/j.1365-8711.2001.04135.x PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 422NZ UT WOS:000168126300014 ER PT J AU King, RA Breuer, KS AF King, RA Breuer, KS TI Acoustic receptivity and evolution of two-dimensional and oblique disturbances in a Blasius boundary layer SO JOURNAL OF FLUID MECHANICS LA English DT Article; Proceedings Paper CT AIAA Fluids 2000 Conference CY JUN 19-22, 2000 CL DENVER, COLORADO SP AIAA ID TOLLMIEN-SCHLICHTING WAVES; LEADING-EDGE AB An experimental investigation was conducted to examine acoustic receptivity and subsequent boundary-layer instability evolution for a Blasius boundary layer formed on a flat plate in the presence of two-dimensional and oblique (three-dimensional) surface waviness. The effect of the non-localized surface roughness geometry and acoustic wave amplitude on the receptivity process was explored. The surface roughness had a well-defined wavenumber spectrum with fundamental wavenumber k(w). A planar downstream-travelling acoustic wave was created to temporally excite the flow near the resonance frequency of an unstable eigenmode corresponding to k(ts) = k(w). The range of acoustic forcing levels, is an element of, and roughness heights, Deltah, examined resulted in a linear dependence of receptivity coefficients, however, the larger values of the forcing combination is an element of Deltah resulted in subsequent nonlinear development of the Tollmien-Schlichting (T-S) wave. This study provides the first experimental evidence of a marked increase in the receptivity coefficient with increasing obliqueness of the surface waviness in excellent agreement with theory. Detuning of the two-dimensional and oblique disturbances was investigated by varying the streamwise wall-roughness wavenumber alpha (w) and measuring the T-S response. For the configuration where laminar-to-turbulent breakdown occurred, the breakdown process was found to be dominated by energy at the fundamental and harmonic frequencies, indicative of K-type breakdown. 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. NR 38 TC 4 Z9 4 U1 0 U2 2 PU CAMBRIDGE UNIV PRESS PI PORT CHESTER PA 110 MIDLAND AVE, PORT CHESTER, NY 10573-4930 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD APR 10 PY 2001 VL 432 BP 69 EP 90 PG 22 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 427TT UT WOS:000168422100003 ER PT J AU Bamber, JL Ekholm, S Krabill, WB AF Bamber, JL Ekholm, S Krabill, WB TI A new, high-resolution digital elevation model of Greenland fully validated with airborne laser altimeter data SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID SATELLITE RADAR INTERFEROMETRY; ICE-SHEET; BALANCE VELOCITIES; SURFACE-PROPERTIES; ACCURACY AB A new digital elevation model of the Greenland ice sheet and surrounding rock outcrops has been produced at 1-km postings from a comprehensive suite of satellite remote sensing and cartographic data sets. Height data over the ice sheet were mainly from ERS-1 and Geosat radar altimetry. These data were corrected for a slope-dependent bias that had been identified in a previous study. The radar altimetry was supplemented with stereophotogrammetric data sets, synthetic aperture radar interferometry, and digitized cartographic maps over regions of bare rock and where gaps in the satellite altimeter coverage existed. The data were interpolated onto a regular grid with a spacing of similar to1 km. The accuracy of the resultant digital elevation model over the ice sheet was assessed using independent and spatially extensive measurements from an airborne laser altimeter that had an accuracy of between 10 and 12 cm. In a comparison with the laser altimetry the digital elevation model was found to have a slope-dependent accuracy ranging from -1.04 +/-1.98 m to -0.06 +/- 14.33 m over the ice sheet for a slope range of 0.0-1.0 degrees. The mean accuracy over the whole ice sheet was -0.33 +/-6.97 m. Over the bare rock areas the accuracy ranged from 20 to 200 m, dependent on the data source available. The new digital elevation model was used as an input data set for a positive degree day model of ablation. The new elevation model was found to reduce ablation by only 2% compared with using an older, 2.5-km resolution model, which suggests that resolution-induced errors in estimating ablation are no longer important. C1 Univ Bristol, Sch Geol Sci, Bristol Glaciol Ctr, Bristol BS8 1SS, Avon, England. Kort & Matrikelstyelsen, Natl Survey & Cadastre, DK-2400 Copenhagen, Denmark. NASA, Goddard Space Flight Ctr, Wallops Flight Facil, Wallops Island, VA 23337 USA. RP Bamber, JL (reprint author), Univ Bristol, Sch Geol Sci, Bristol Glaciol Ctr, Univ Rd, Bristol BS8 1SS, Avon, England. EM j.l.bamber@bristol.ac.uk; krabill@osb1.wff.nasa.gov RI Bamber, Jonathan/C-7608-2011 OI Bamber, Jonathan/0000-0002-2280-2819 NR 36 TC 131 Z9 132 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 APR 10 PY 2001 VL 106 IS B4 BP 6733 EP 6745 DI 10.1029/2000JB900365 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 418XU UT WOS:000167920500025 ER PT J AU Deelman, PW Bicknell-Tassius, RN Nikishin, S Kuryatkov, V Temkin, H AF Deelman, PW Bicknell-Tassius, RN Nikishin, S Kuryatkov, V Temkin, H TI Low-noise GaN Schottky diodes on Si(111) by molecular beam epitaxy SO APPLIED PHYSICS LETTERS LA English DT Article ID N-TYPE GAN; ULTRAVIOLET PHOTODETECTORS; BARRIER DETECTORS; AVALANCHE PHOTODIODES; PERFORMANCE; RESPONSIVITY; AMMONIA AB We report on the achievement of mesa-isolated Schottky diodes fabricated from n-GaN epilayers grown by gas-source molecular beam epitaxy on Si(111) that exhibit extremely low noise and dark current. Silicon dioxide grown by plasma-enhanced chemical vapor deposition provided both surface passivation and electrical isolation, and the Schottky contact was a 10 nm Pd thin film. The dark current of an 86x86 mum(2) diode was 2.10x10(-8) A/cm(2) at -2 V bias, and the zero-bias noise power density at 1 Hz is as low a 9x10(-29) A(2)/Hz. (C) 2001 American Institute of Physics. C1 CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. Texas Tech Univ, Dept Elect Engn, Lubbock, TX 79409 USA. RP Deelman, PW (reprint author), CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 33 TC 15 Z9 19 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD APR 9 PY 2001 VL 78 IS 15 BP 2172 EP 2174 DI 10.1063/1.1357448 PG 3 WC Physics, Applied SC Physics GA 418GA UT WOS:000167881500027 ER PT J AU Vrinceanu, D Msezane, AZ Bessis, D Temkin, A AF Vrinceanu, D Msezane, AZ Bessis, D Temkin, A TI Exchange forces in dispersion relations investigated using circuit relations SO PHYSICAL REVIEW LETTERS LA English DT Article ID ELECTRON-ATOM SCATTERING AB We propose a novel method to compute in an exact manner the left-hand cut discontinuity of the electron-atom partial wave scattering amplitude in the complex energy plane within the static exchange approximation. Zero energy dispersion relations for electron-hydrogen scattering are computed numerically for illustration. C1 Clark Atlanta Univ, Ctr Theoret Studies Phys Syst, Atlanta, GA 30314 USA. Georgia Inst Technol, Sch Phys, Atlanta, GA 30332 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Vrinceanu, D (reprint author), Clark Atlanta Univ, Ctr Theoret Studies Phys Syst, Atlanta, GA 30314 USA. NR 16 TC 3 Z9 3 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 APR 9 PY 2001 VL 86 IS 15 BP 3256 EP 3259 DI 10.1103/PhysRevLett.86.3256 PG 4 WC Physics, Multidisciplinary SC Physics GA 421CZ UT WOS:000168045700010 PM 11327944 ER PT J AU Van Keuls, FW Chevalier, CT Miranda, FA Carlson, CM Rivkin, TV Parilla, PA Perkins, JD Ginley, DS AF Van Keuls, FW Chevalier, CT Miranda, FA Carlson, CM Rivkin, TV Parilla, PA Perkins, JD Ginley, DS TI Comparison of the experimental performance of ferroelectric CPW circuits with method-of-moment simulations and conformal mapping analysis SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Article DE thin-film ferroelectric; coplanar waveguide; phase shifter ID THIN-FILMS; PHASE SHIFTERS; MICROWAVE PERMITTIVITY; BAND; CAPACITORS; FREQUENCY; GHZ AB Experimental measurements of coplanar waveguide circuits atop thin films of ferroelectric BaxSr1-xTiO3 (BST) were made as a function of dc bias from 0 to 200 V and frequency from 0.045 to 20 GHz. The resulting phase shifts are compared with method-of-moments electromagnetic simulations and a conformal mapping analysis to determine the dielectric constant of the BST films. The accuracy of the resulting dielectric constants is analyzed and compared to low-frequency measurements of interdigitated capacitor circuits on the same films. (C) 2001 John Wiley & Sons, Inc. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Micron Technol Inc, Boise, ID 83707 USA. NREL, Golden, CO 80401 USA. RP Van Keuls, FW (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 13 TC 5 Z9 5 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 USA SN 0895-2477 J9 MICROW OPT TECHN LET JI Microw. Opt. Technol. Lett. PD APR 5 PY 2001 VL 29 IS 1 BP 34 EP 37 DI 10.1002/mop.1074 PG 4 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA 409YA UT WOS:000167412200010 ER PT J AU Withers, P Neumann, GA AF Withers, P Neumann, GA TI Enigmatic northern plains of Mars - A network of ridges in this region opens a new tectonic window onto this planet. SO NATURE LA English DT Article C1 Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. RP Withers, P (reprint author), Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. RI Neumann, Gregory/I-5591-2013; Withers, Paul/H-2241-2014 OI Neumann, Gregory/0000-0003-0644-9944; NR 4 TC 23 Z9 23 U1 0 U2 1 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD APR 5 PY 2001 VL 410 IS 6829 BP 651 EP 651 DI 10.1038/35070640 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 418DJ UT WOS:000167875400033 PM 11287941 ER PT J AU Anantram, MP AF Anantram, MP TI Which nanowire couples better electrically to a metal contact: Armchair or zigzag nanotube? SO APPLIED PHYSICS LETTERS LA English DT Article ID MULTIWALLED CARBON NANOTUBES; SINGLE-WALL; CONDUCTANCE AB The fundamental question of how chirality affects the electronic coupling of a nanotube to metal contacts is important for the application of nanotubes as nanowires. We show that metallic-zigzag nanotubes are superior to armchair nanotubes as nanowires, by modeling the metal-nanotube interface. More specifically, we show that as a function of coupling strength, the total electron transmission of armchair nanotubes increases and tends to be pinned close to unity for a metal with Fermi wave vector close to that of gold. In contrast, the total transmission of zigzag nanotubes increases to the maximum possible value of two. The origin of these effects lies in the details of the wave function, which is explained. (C) 2001 American Institute of Physics. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Anantram, MP (reprint author), NASA, Ames Res Ctr, Mail Stop T27A-1, Moffett Field, CA 94035 USA. NR 18 TC 32 Z9 32 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD APR 2 PY 2001 VL 78 IS 14 BP 2055 EP 2057 DI 10.1063/1.1360228 PG 3 WC Physics, Applied SC Physics GA 415VT UT WOS:000167744800033 ER PT J AU Zhu, DM Miller, RA Nagaraj, BA Bruce, RW AF Zhu, DM Miller, RA Nagaraj, BA Bruce, RW TI Thermal conductivity of EB-PVD thermal barrier coatings evaluated by a steady-state laser heat flow technique SO SURFACE & COATINGS TECHNOLOGY LA English DT Article DE thermal conductivity; electron beam-physical vapor deposition (EB-PVD); steady state heat flux laser; thermal barrier coatings ID BEHAVIOR AB The thermal conductivity of electron beam-physical vapor deposited (EB-PVD) ZrO2-8 wt.%Y2O3 thermal barrier coatings was determined by a steady-state laser heat flux technique. Thermal conductivity change kinetics of the EB-PVD ceramic coatings were also obtained in real time, at high temperatures, under the laser high heat flux, long-term test conditions. The thermal conductivity increase due to micro-pore sintering and the decrease due to coating micro-delaminations in the EB-PVD coatings were evaluated for grooved and non-grooved EB-PVD coating systems under isothermal and thermal cycling conditions. The coating failure modes under the high heat flux test conditions were also investigated. The test technique provides a viable means for obtaining coating thermal conductivity data for use in design, development, and life prediction for engine applications. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. Gen Elect Aircraft Engines, Cincinnati, OH 45215 USA. RP Zhu, DM (reprint author), NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. NR 17 TC 73 Z9 77 U1 2 U2 12 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0257-8972 J9 SURF COAT TECH JI Surf. Coat. Technol. PD APR 2 PY 2001 VL 138 IS 1 BP 1 EP 8 DI 10.1016/S0257-8972(00)01145-2 PG 8 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA 409CF UT WOS:000167366400001 ER PT J AU Adamson, DH Harrison, CK Cheng, ZD Sebastian, JM Sethuraman, S Huse, DA Register, RA Chaikin, PM AF Adamson, DH Harrison, CK Cheng, ZD Sebastian, JM Sethuraman, S Huse, DA Register, RA Chaikin, PM TI Kinetics of coarsening in striped patterns. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Princeton Univ, Princeton Mat Inst, Princeton, NJ 08540 USA. Princeton Univ, Dept Phys, Princeton, NJ 08544 USA. Princeton Univ, Dept Chem Engn, Princeton, NJ 08544 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RI Adamson, Douglas/C-8721-2009 NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 173-PMSE BP U384 EP U384 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824802303 ER PT J AU Belz, AP Andrews, M Nealson, KH Ahn, CC AF Belz, AP Andrews, M Nealson, KH Ahn, CC TI Surface complexation effects in bacterial metal reduction. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Dept Mat Sci, Pasadena, CA 91109 USA. EM andrea.p.belz@jpl.nasa.gov NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 99-GEOC BP U531 EP U531 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PH UT WOS:000168824703512 ER PT J AU Brinton, K Belz, A McDonald, GD AF Brinton, K Belz, A McDonald, GD TI Amino acid racemization on Mars. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH, Jet Prop Lab, Ctr Life Detect, Pasadena, CA 91109 USA. EM gene.D.mcdonald@jpl.nasa.gov NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 172-GEOC BP U544 EP U544 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PH UT WOS:000168824703585 ER PT J AU Chaban, GM Gerber, RB Jung, JO Gregurick, SK AF Chaban, GM Gerber, RB Jung, JO Gregurick, SK TI Anharmonic vibrational spectroscopy of biological molecules: Use of ab initio, empirical, and hybrid (QM/MM) potentials. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Computat Chem Branch, Moffett Field, CA 94035 USA. Univ Calif Irvine, Dept Chem, Irvine, CA 92717 USA. Columbia Univ, Dept Mol Biophys, New York, NY 10027 USA. Columbia Univ, Dept Chem, New York, NY 10027 USA. NR 0 TC 2 Z9 2 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 340-PHYS BP U284 EP U285 PN 2 PG 2 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824801662 ER PT J AU Chiar, JE AF Chiar, JE TI Observations of organic material in the interstellar medium. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Astron Branch, Moffett Field, CA 94035 USA. EM chiar@misty.arc.nasa.gov NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 145-GEOC BP U539 EP U539 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PH UT WOS:000168824703558 ER PT J AU Cooper, GW Kimmich, N Sarinana, J Brabham, K Garrel, L Belisle, WA AF Cooper, GW Kimmich, N Sarinana, J Brabham, K Garrel, L Belisle, WA TI Sugar-related compounds in carbonaceous meteorites. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Exobiol Branch, Moffett Field, CA 94035 USA. EM gcooper@mail.arc.nasa.gov NR 0 TC 0 Z9 0 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 147-GEOC BP U540 EP U540 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PH UT WOS:000168824703560 ER PT J AU Curtis, VE Ticich, TM Vander Wal, RL Millard, MW AF Curtis, VE Ticich, TM Vander Wal, RL Millard, MW TI Laser-induced incandescence measurements in turbulent ethylene diffusion flames. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Centenary Coll Louisiana, Dept Chem, Shreveport, LA 71134 USA. NASA, Glenn Res Ctr, NCMR, Cleveland, OH 44135 USA. EM ecurtis@centenary.edu NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 832-CHED BP U223 EP U223 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PH UT WOS:000168824701797 ER PT J AU Delzeit, LD Cassel, A Stevens, RMD Nguyen, C Meyyappan, M AF Delzeit, LD Cassel, A Stevens, RMD Nguyen, C Meyyappan, M TI Novel catalyst deposition technique for the growth of carbon nanotubes. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. EM ldelzeit@mail.arc.nasa.gov NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 401-IEC BP U628 EP U628 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PH UT WOS:000168824703999 ER PT J AU Drouin, BJ Cohen, EA Pearson, JC Miller, CE Pickett, HM AF Drouin, BJ Cohen, EA Pearson, JC Miller, CE Pickett, HM TI New sources and software for submillimeter spectroscopy. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH, Jet Prop Lab, Microwave Millimeter & Submillimeter Spect Lab, Pasadena, CA 91109 USA. Haverford Coll, Dept Chem, Haverford, PA 19041 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 210-PHYS BP U266 EP U266 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824801532 ER PT J AU Freund, F AF Freund, F TI Catalysis in the 3-D: How organic molecules may be formed. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. EM ffreund@mail.arc.nasa.gov NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 157-GEOC BP U541 EP U541 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PH UT WOS:000168824703570 ER PT J AU Gallagher, RM Ferrante, RF Moore, MH AF Gallagher, RM Ferrante, RF Moore, MH TI Radiation-induced conversions of hydrocarbons in environments relevant to Pluto. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 USN Acad, Dept Aerosp Engn, Annapolis, MD 21402 USA. USN Acad, Dept Chem, Annapolis, MD 21402 USA. NASA, Astrochem Branch, Washington, DC 20546 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 353-PHYS BP U287 EP U287 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824801675 ER PT J AU Gordon, MS Fedorov, D Chaban, GM Ng, C AF Gordon, MS Fedorov, D Chaban, GM Ng, C TI Excited state potential energy surfaces: From diatomics to biomolecules. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Iowa State Univ Sci & Technol, Dept Chem, Ames, IA 50011 USA. Univ Tokyo, Dept Chem, Tokyo, Japan. NASA, Ames Res Ctr, Computat Chem Branch, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 372-PHYS BP U289 EP U289 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824801694 ER PT J AU Greene, B Beeson, H AF Greene, B Beeson, H TI Using humor in laboratory safety training. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Honeywell Technol Solut Inc, Dept Lab, Las Cruces, NM 88004 USA. NASA, Lyndon B Johnson Space Ctr, Lab Off, White Sands Missile Range, NM USA. EM bgreene@wstf.nasa.gov NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 14-CHAS BP U271 EP U271 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PH UT WOS:000168824702081 ER PT J AU Hergenrother, PM AF Hergenrother, PM TI Design and durability of high-performance/high-temperature polymers. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 232-POLY BP U329 EP U329 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824801953 ER PT J AU Hockensmith, CM Goldsby, J AF Hockensmith, CM Goldsby, J TI Coordination compounds of indium-tin oxides: Synthesis and decomposition studies of precursors to sensor materials. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 New Mexico Inst Min & Technol, Dept Chem, Socorro, NM 87801 USA. NASA, John H Glenn Res Ctr, Cleveland, OH USA. EM chocken@nmt.edu NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 391-INOR BP U697 EP U697 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PH UT WOS:000168824704422 ER PT J AU Islam, M Dean, DR Small, S Campbell, S AF Islam, M Dean, DR Small, S Campbell, S TI Synthesis of PMR-15/layered silicate nanocomposites. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Tuskegee Univ, Ctr Adv Mat, Tuskegee, AL 36088 USA. NASA Glenn Res Ctr, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 354-PMSE BP U412 EP U412 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824802484 ER PT J AU Jaffe, RL Jarvis, B AF Jaffe, RL Jarvis, B TI Models of carbon nanotube reactivity. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Computat Chem Branch, Moffett Field, CA 94035 USA. EM rjaffe@mail.arc.nasa.gov NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 243-IEC BP U591 EP U591 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PH UT WOS:000168824703849 ER PT J AU Kiefer, RL Weakley, JA McGlothlin, DR Dueber, JL Thibeault, SA AF Kiefer, RL Weakley, JA McGlothlin, DR Dueber, JL Thibeault, SA TI Development of shielding materials for human space exploration. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Coll William & Mary, Dept Chem, Williamsburg, VA 23187 USA. NASA, Langley Res Ctr, Adv Mat & Proc Branch, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 48-POLY BP U301 EP U301 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824801770 ER PT J AU Lewis, DK Glenar, DA Hughes, SM Kalra, BL Schlier, J Shukla, RJ Baldwin, JE AF Lewis, DK Glenar, DA Hughes, SM Kalra, BL Schlier, J Shukla, RJ Baldwin, JE TI Stereochemistry of the retro Diels-Alder reaction of cis,exo-5,6-d2-bicyclo[2.2.2]oct-2-ene. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Connecticut Coll, Dept Chem, New London, CT 06320 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Hollins Univ, Dept Chem, Hollins, VA 24020 USA. Wesleyan Univ, Dept Chem, Middletown, CT 06457 USA. Syracuse Univ, Dept Chem, Syracuse, NY 13244 USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 355-PHYS BP U287 EP U287 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824801677 ER PT J AU MacDougall, PJ Henze, CE AF MacDougall, PJ Henze, CE TI Identification of molecular reactive sites with an interactive volume rendering tool. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Middle Tennessee State Univ, Dept Chem, Murfreesboro, TN 37132 USA. NASA, Ames Res Ctr, Data Anal Grp, Moffett Field, CA 94035 USA. EM pamcdougall@mtsu.edu; chenze@nas.nasa.gov RI MacDougall, Preston/N-2515-2016 OI MacDougall, Preston/0000-0002-0403-000X NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 49-CINF BP U285 EP U285 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PH UT WOS:000168824702164 ER PT J AU Mann, JA Wegdam, GH Fenistein, D Crouser, P Meyer, WV AF Mann, JA Wegdam, GH Fenistein, D Crouser, P Meyer, WV TI Surface fluctuation spectroscopy of thin wetting films. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Case Western Reserve Univ, Dept Chem Engn, Cleveland, OH 44106 USA. Univ Amsterdam, Van Der Waals Zeeman Inst, NL-1012 WX Amsterdam, Netherlands. NASA, Glenn Natl Lab, Micro Grav Ctr, Cleveland, OH USA. EM jam12@po.cwru.edu NR 0 TC 0 Z9 0 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 5-COLL BP U307 EP U307 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PH UT WOS:000168824702253 ER PT J AU Miller, CE Drouin, BJ Cohen, EA AF Miller, CE Drouin, BJ Cohen, EA TI chi(1) (2)pi(3/2) and chi(2) (2)pi(1/2) potentials of the halogen monoxides (Xo). SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Haverford Coll, Dept Chem, Haverford, PA 19041 USA. CALTECH, NASA, Jet Propuls Lab, Pasadena, CA 91125 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 370-PHYS BP U289 EP U289 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824801692 ER PT J AU Nicholson, LM Whitley, KS Gates, TS AF Nicholson, LM Whitley, KS Gates, TS TI Crosslink density and molecular weight effects on the viscoelastic response of a glassy high-performance polyimide. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Langley Res Ctr, ICASE, Struct & Mat Div, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Mech & Durabil Branch, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 364-POLY BP U349 EP U349 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824802085 ER PT J AU Pohorille, A Wilson, MA Chipot, C AF Pohorille, A Wilson, MA Chipot, C TI Simulations of peptides at aqueous interfaces. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Ctr Computat Astrobiol, Moffett Field, CA 94035 USA. Univ Henri Poincare Nancy 1, Chim Theor Lab, Nancy, France. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 8-PHYS BP U229 EP U229 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824801335 ER PT J AU Southward, RE Dean, CJ Scott, JL Broadwater, ST Thompson, DW AF Southward, RE Dean, CJ Scott, JL Broadwater, ST Thompson, DW TI Silvered polyimide films for space applications via a single stage synthesis using 6FDA-based polyimides. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Langley Res Ctr, Williamsburg, VA 23681 USA. Coll William & Mary, Dept Chem, Williamsburg, VA 23185 USA. Coll William & Mary, Dept Biol, Williamsburg, VA 23185 USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 192-PMSE BP U387 EP U387 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824802322 ER PT J AU Thompson, DS Thompson, DW Southward, RE AF Thompson, DS Thompson, DW Southward, RE TI Thermal and mechanical properties of oxo-lanthanide(III)-polyimide nanocomposites and comparisons with montmorillonite-polyimide hybrid materials imide nanocomposites. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Coll William & Mary, Dept Chem, Williamsburg, VA 23187 USA. NASA, Langley Res Ctr, Mat & Struct Competency, Hampton, VA 23665 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 503-PMSE BP U434 EP U434 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PJ UT WOS:000168824802633 ER PT J AU Wilson, ES DeMore, WB Evans, BL Scott, NW AF Wilson, ES DeMore, WB Evans, BL Scott, NW TI Kinetics studies of C4-C6 hydrocarbons with OH radicals. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Harding Univ, Dept Phys Sci, Searcy, AR 72149 USA. Jet Propuls Lab, Atmospher Sci, Los Osos, CA 93402 USA. EM wilson@harding.edu; wdemore@earthlink.net NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 1 PY 2001 VL 221 MA 259-ENVR BP U486 EP U486 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 434PH UT WOS:000168824703276 ER PT J AU Allman, M Paxson, V AF Allman, M Paxson, V TI On estimating end-to-end network path properties SO ACM SIGCOMM COMPUTER COMMUNICATION REVIEW LA English DT Article; Proceedings Paper CT Workshop on Data Communication in Latin America and the Caribbean CY APR 03-05, 2001 CL SAN JOSE, COSTA RICA AB The more information about current network conditions available to a transport protocol, the more efficiently it can use the network to transfer its data. In networks such as the Internet, the transport protocol must often form its own estimates of network properties based on measurements performed by the connection endpoints. We consider two basic transport estimation problems: determining the setting of the retransmission timer (RTO) for a reliable protocol, and estimating the bandwidth available to a connection as it begins. We look at both of these problems in the context of TCP, using a large TCP measurement set [Pax97b] for trace-driven simulations. For RTO estimation, we evaluate a number of different algorithms, finding that the performance of the estimators is dominated by their minimum values, and to a lesser extent, the timer granularity, while being virtually unaffected by how often round-trip time measurements are made or the settings of the parameters in the exponentially-weighted moving average estimators commonly used. For bandwidth estimation, we explore techniques previously sketched in the literature [Hoe96, AD98] and find that in practice they perform less well than anticipated. We then develop a receiver-side algorithm that performs significantly better. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. GTE Internetworking, Cleveland, OH 44135 USA. ICSI, AT&T Ctr Internet Res, Berkeley, CA 94704 USA. Lawrence Berkeley Natl Lab, Berkeley, CA 94704 USA. RP Allman, M (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd,MS 54-2, Cleveland, OH 44135 USA. EM mallman@grc.nasa.gov; vern@aciri.org NR 33 TC 4 Z9 6 U1 0 U2 0 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 2 PENN PLAZA, STE 701, NEW YORK, NY 10121-0701 USA SN 0146-4833 EI 1943-5819 J9 ACM SIGCOMM COMP COM JI ACM SIGCOMM Comp. Commun. Rev. PD APR PY 2001 VL 31 IS 2 SU S BP 124 EP + DI 10.1145/844193.844203 PG 12 WC Computer Science, Information Systems SC Computer Science GA 473AB UT WOS:000171016200009 ER PT J AU Elachi, C AF Elachi, C TI Space imaging radar in planetary exploration and earth observation SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA 38th Aerospace Sciences Meeting and Exhibit CY JAN 10-15, 2000 CL RENO, NEVADA SP Amer Inst Aeronatu & Astronaut ID SYNTHETIC APERTURE RADAR; INTERFEROMETRY AB Spaceborne imaging radars are becoming key tools for mapping Earth and planetary surfaces and near subsurface. Developments in the past decade are leading to capabilities for three-dimensional surface imaging, detection of surface subtle motion due to earthquakes or volcanic activities, color mapping of surface properties, assessment of vegetation cover, etc, In planetary exploration, the radar capability to penetrate through cloud and haze cover and the possibility of sounding below the surface cover are providing a special perspective on the planetary surface and near surface evolution, An overview of the techniques and technology of spaceborne imaging radars and their present and future potential applications is provided. C1 CALTECH, Jet Prop Lab, Space & Earth Sci Program, Pasadena, CA 91109 USA. RP Elachi, C (reprint author), CALTECH, Jet Prop Lab, Space & Earth Sci Program, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 26 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 0001-1452 J9 AIAA J JI AIAA J. PD APR PY 2001 VL 39 IS 4 BP 553 EP 563 PG 11 WC Engineering, Aerospace SC Engineering GA 416RP UT WOS:000167794200001 ER PT J AU Maestrello, L AF Maestrello, L TI Controlling vibrational chaos of a curved structure SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA/CEAS 6th Aeroacousties Conference CY JUN 12-14, 2000 CL LAHAINA, HAWAII SP AIAA, CEAS ID WEAK PERIODIC PERTURBATIONS; TIME-SERIES; BOUNDARY-LAYER; SYSTEM; DYNAMICS; SOUND; PANEL; NONLINEARITY; EXPONENTS AB Nonlinear response of a flexible curved panel exhibiting bifurcation to fully developed chaos is demonstrated along with the sensitivity to small perturbations from the initial forcing. The response is determined from the measured time series at two fixed points. The panel is forced by an external nonharmonic multifrequency and monofrequency sound field. Using a low-power time-continuous control, carefully tuned to each initial forcing condition, produces large long-term effects on the dynamics toward taming chaos. Without knowledge of the initial forcing, control may be achieved by destructive interference. In this case, the control power is proportional to the loading power. Calculation of the correlation dimension and the estimation of positive Lyapunov exponents, in practice, are the proof of chaotic response. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Maestrello, L (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 42 TC 3 Z9 3 U1 1 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 APR PY 2001 VL 39 IS 4 BP 581 EP 589 DI 10.2514/2.1379 PG 9 WC Engineering, Aerospace SC Engineering GA 416RP UT WOS:000167794200004 ER PT J AU Coleman, CP Poll, DIA AF Coleman, CP Poll, DIA TI Roughness-induced attachment-line transition on a swept cylinder in supersonic flow SO AIAA JOURNAL LA English DT Article ID BOUNDARY-LAYER-TRANSITION AB Experiments were conducted on a 76-deg swept cylinder to establish the conditions for transition onset at the attachment line with and without surface roughness in a low-disturbance (quiet), Mach 1.6 airflow, Local flow parameters were estimated from surface pressure measurements, and hot wires and schlieren photography were used to determine the state of the boundary layer. It was found that, for a near-adiabatic wall condition and a smooth surface, the attachment-line boundary layer remained laminar up to the highest Reynolds number ((R) over bar of 790) attainable in the tunnel. Transition under the influence of trip wires was Found to depend on wind-tunnel disturbance levels, and the onset conditions have been established. C1 NASA, Ames Res Ctr, Dept Fluid Mech Labs, Moffett Field, CA 94035 USA. Cranfield Univ, Coll Aeronaut, Cranfield MK43 0AL, Beds, England. RP Coleman, CP (reprint author), NASA, Ames Res Ctr, Dept Fluid Mech Labs, MS 260-1, Moffett Field, CA 94035 USA. NR 22 TC 2 Z9 2 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 APR PY 2001 VL 39 IS 4 BP 590 EP 596 DI 10.2514/2.1380 PG 7 WC Engineering, Aerospace SC Engineering GA 416RP UT WOS:000167794200005 ER PT J AU Chen, KS Spearing, SM Nemeth, NN AF Chen, KS Spearing, SM Nemeth, NN TI Structural design of a silicon micro-turbo-generator SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA/ASME/ASCE/AHS/ASC 40th Structures, Structural Dynamics, and Materials Conference CY APR 12-15, 1999 CL ST LOUIS, MISSOURI SP Amer Inst Aeronaut & Astronaut, ASME, ASCE, AHS, ASC ID FRACTURE; STRESS AB The probabilistic structural analysis and design of a silicon micro-turbo-generator rotor are presented, This rotor was designed to have a tip speed of 500 m/s. Three-dimensional finite element analysis, fracture strength characterization of single crystal silicon, and structural failure probability calculations were performed. The results show that the design of micro-turbine-generator rotor, although highly stressed, is feasible. However, it is important to note that this feasibility is very dependent on the etching process achieving a high surface quality The overall approach and tests employed are equally applicable to other highly stressed microelectromechanical systems. C1 Natl Cheng Kung Univ, Dept Mech Engn, Tainan 70001, Taiwan. MIT, Dept Aeronaut & Astronaut, Cambridge, MA 02139 USA. NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. RP Chen, KS (reprint author), Natl Cheng Kung Univ, Dept Mech Engn, Room 91710, Tainan 70001, Taiwan. NR 27 TC 18 Z9 18 U1 1 U2 4 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 APR PY 2001 VL 39 IS 4 BP 720 EP 728 DI 10.2514/2.1367 PG 9 WC Engineering, Aerospace SC Engineering GA 416RP UT WOS:000167794200021 ER PT J AU Carter, GA Knapp, AK AF Carter, GA Knapp, AK TI Leaf optical properties in higher plants: Linking spectral characteristics to stress and chlorophyll concentration SO AMERICAN JOURNAL OF BOTANY LA English DT Article DE absorptance; chlorophyll; leaf optics; light; reflectance; stress; transmittance ID INCREASED ATMOSPHERIC OZONE; REFLECTANCE RED EDGE; REMOTE ESTIMATION; EUCALYPTUS LEAVES; WATER-CONTENT; CORN LEAVES; SLASH PINE; NITROGEN; WAVEBANDS; SPECTROSCOPY AB A number of studies have linked responses in leaf spectral reflectance, transmittance, or absorptance to physiological stress. A variety of stressors including dehydration, flooding, freezing, ozone, herbicides, competition, disease, insects. and deficiencies in ectomycorrhizal development and N fertilization have been imposed on species ranging from grasses to conifers and deciduous trees. In all cases, the maximum difference in reflectance within the 400-850 nm wavelength range between control and stressed states occurred as a reflectance increase at wavelengths near 700 nm. In studies that included transmittance and absorptance as well as reflectance, maximum differences occurred as increases and decreases, respectively, near 700 nm. This common optical response to stress could be simulated closely by varying the chlorophyll concentration of model leaves (fiberglass filter pads) and by the natural variability in leaf chlorophyll concentrations in senescent leaves of five species. The optical response to stress near 700 nm, as well as corresponding changes in reflectance that occur in the green-yellow spectrum, can be explained by the general tendency of stress to reduce leaf chlorophyll concentration. C1 NASA, Earth Syst Sci Off, Stennis Space Ctr, MS 39529 USA. Kansas State Univ, Div Biol, Manhattan, KS 66506 USA. RP Carter, GA (reprint author), NASA, Earth Syst Sci Off, Stennis Space Ctr, MS 39529 USA. RI Knapp, Alan/A-2931-2008 NR 53 TC 296 Z9 319 U1 13 U2 91 PU BOTANICAL SOC AMER INC PI COLUMBUS PA OHIO STATE UNIV-DEPT BOTANY, 1735 NEIL AVE, COLUMBUS, OH 43210 USA SN 0002-9122 J9 AM J BOT JI Am. J. Bot. PD APR PY 2001 VL 88 IS 4 BP 677 EP 684 DI 10.2307/2657068 PG 8 WC Plant Sciences SC Plant Sciences GA 422GY UT WOS:000168111200016 PM 11302854 ER PT J AU Serabyn, E Colavita, MM AF Serabyn, E Colavita, MM TI Fully symmetric nulling beam combiners SO APPLIED OPTICS LA English DT Article ID BROAD-BAND; LIGHT; DEEP AB A simple method of nulling broadband Light is presented. A mirror-symmetric pair of right-angle periscopes is first used to introduce a geometric field flip between two incident light beams, after which the light is combined by means of one of a number of constructive two-beam interferometers. A reciprocal pair of beam-splitter passages provides for complete symmetry. Such an approach greatly eases beam-splitter design requirements and should find use both in initial ground-based nulling experiments and ultimately in space-borne interferometers targeted at direct extrasolar planet detection. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Serabyn, E (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 171-113, Pasadena, CA 91109 USA. EM gene.serabyn@jpl.nasa.gov NR 9 TC 95 Z9 95 U1 0 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 APR 1 PY 2001 VL 40 IS 10 BP 1668 EP 1671 DI 10.1364/AO.40.001668 PG 4 WC Optics SC Optics GA 417MY UT WOS:000167839800012 PM 18357162 ER PT J AU Adams, JD Stauffer, JR Monet, DG Skrutskie, MF Beichman, CA AF Adams, JD Stauffer, JR Monet, DG Skrutskie, MF Beichman, CA TI The mass and structure of the Pleiades star cluster from 2MASS SO ASTRONOMICAL JOURNAL LA English DT Article DE astrometry; celestial mechanics; open clusters and associations : individual (Pleiades); stars : low-mass, brown dwarfs ID N-BODY SIMULATIONS; PROPER-MOTION MEMBERSHIP; SOLAR-TYPE STARS; BROWN DWARFS; UNEQUAL MASSES; FAINT MEMBERS; EVOLUTION; SEARCH; FIELD; PROBABILITIES AB We present the results of a large-scale search for new members of the Pleiades star cluster using 2MASS near-infrared photometry and proper motions derived from POSS plates digitized by the USNO PMM program. The search extends to a 10 degrees radius around the cluster, well beyond the presumed tidal radius, to a limiting magnitude of R similar to 20, corresponding to similar to0.07 M-. at the distance and age of the Pleiades. Multiobject spectroscopy for 528 candidates verifies that the search was extremely effective at detecting cluster stars in the 1-0.1 M-. mass range using the distribution of H alpha emission strengths as an estimate of sample contamination by field stars. When combined with previously identified, higher mass stars, this search provides a sensitive measurement of the stellar mass function and dynamical structure of the Pleiades. The degree of tidal elongation of the halo agrees well with current N-body simulation results. Tidal truncation affects masses below similar to1 M-.. The cluster contains a total mass similar to 800 M-.. Evidence for a flatter mass function in the core than in the halo indicates the depletion of stars in the core with mass less than similar to0.5 M-., relative to stars with mass similar to1-0.5 M-., and implies a preference for very low-mass objects to populate the halo or escape. The overall mass function is best fitted with a lognormal form that becomes flat at similar to0.1 M-.. Whether sufficient dynamical evaporation has occurred to detectably flatten the initial mass function, via preferential escape of very low-mass stars and brown dwarfs, is undetermined, pending better membership information for stars at large radial distances. C1 Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. USN Observ, Flagstaff Stn, Flagstaff, AZ 86002 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Boston Univ, Inst Astrophys Res, 725 Commonwealth Ave, Boston, MA 02215 USA. EM jdadams@bu.edu; stauffer@ipac.caltech.edu; dgm@nofs.navy.mil; skrutski@astro.umass.edu; chas@pop.jpl.nasa.gov NR 73 TC 50 Z9 53 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 EI 1538-3881 J9 ASTRON J JI Astron. J. PD APR PY 2001 VL 121 IS 4 BP 2053 EP 2064 DI 10.1086/319965 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420UA UT WOS:000168022600019 ER PT J AU Brandt, JC Heap, SR Walter, FM Beaver, EA Boggess, A Carpenter, KG Ebbets, DC Hutchings, JB Jura, M Leckrone, DS Linsky, JL Maran, SP Savage, BD Smith, AM Trafton, LM Weymann, RJ Norman, D Redfield, S AF Brandt, JC Heap, SR Walter, FM Beaver, EA Boggess, A Carpenter, KG Ebbets, DC Hutchings, JB Jura, M Leckrone, DS Linsky, JL Maran, SP Savage, BD Smith, AM Trafton, LM Weymann, RJ Norman, D Redfield, S TI AB Dor in '94. I. Hubble Space Telescope Goddard High Resolution Spectrograph observations of the quiescent chromosphere of an active star SO ASTRONOMICAL JOURNAL LA English DT Article DE ISM : kinematics and dynamics; stars : activity; stars : chromospheres; stars : individual (AB Doradus) ID EVOLUTIONARY STATUS; INTERSTELLAR GAS; FAR-ULTRAVIOLET; EMISSION-LINE; LOCAL CLOUD; HD 36705; DORADUS; SOLAR; SPECTROSCOPY; ABUNDANCES AB We analyze Hubble Space Telescope/Goddard High Resolution Spectrograph spectra of AB Doradus, the prototypical, ultrarapidly rotating K dwarf. We observed chromospheric (Mg II) and transition-region (C II, Si IV, C IV, and N V) lines periodically throughout the stellar rotation period and provide a low-dispersion stellar atlas of 78 emission lines. The quiescent line profiles of the chromospheric and transition-region lines show narrow cores superposed on very broad wings. The broad wings of the Mg II k and h lines and of the transition-region lines can be explained by emission from gas corotating with the star and extending out to near the Keplerian corotation radius (2.8 stellar radii). While this is not a unique solution, it is consistent with previous studies of Ha emission, which are naturally explained by large corotating prominences. We find no evidence for rotational modulation of the emission-line fluxes. The density diagnostics suggest that the transition region is formed at constant pressure, with an electron density of 2-3 x 10(12) cm(-3) at a temperature of 3 x 10(4) K. The electron pressure is about 100 times larger than that for the quiet Sun. The emission-measure distribution shows a minimum between log T = 5 and 5.5. The Mg II line exhibits three interstellar absorption components along the 15 pc line of sight. We identify the lowest velocity component with the G Cloud, but the other components are not identified with any interstellar clouds previously detected from other lines of sight. C1 Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA. Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. Ball Aerosp & Technol Corp, Boulder, CO 80306 USA. Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Space Sci Directorate, Greenbelt, MD 20771 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Univ Texas, MacDonald Observ, Austin, TX 78712 USA. Univ Texas, Dept Astron, Austin, TX 78712 USA. Observ Carnegie Inst Washington, Pasadena, CA 91101 USA. RP Univ New Mexico, Dept Phys & Astron, Inst Astrophys, 800 Yale Blvd, Albuquerque, NM 87131 USA. RI heap, sara/E-2237-2012; Carpenter, Kenneth/D-4740-2012 NR 51 TC 20 Z9 20 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 EI 1538-3881 J9 ASTRON J JI Astron. J. PD APR PY 2001 VL 121 IS 4 BP 2173 EP 2184 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420UA UT WOS:000168022600029 ER PT J AU Santos-Lleo, M Clavel, J Schulz, B Altieri, B Barr, P Alloin, D Berlind, P Bertram, R Crenshaw, DM Edelson, RA Giveon, U Horne, K Huchra, JP Kaspi, S Kriss, GA Krolik, JH Malkan, MA Malkov, YF Netzer, H O'Brien, PT Peterson, BM Pogge, RW Pronik, VI Qian, BC Reichert, GA Rodriguez-Pascual, PM Sergeev, SG Tao, J Tokarz, S Wagner, RM Wamsteker, W Wilkes, BJ AF Santos-Lleo, M Clavel, J Schulz, B Altieri, B Barr, P Alloin, D Berlind, P Bertram, R Crenshaw, DM Edelson, RA Giveon, U Horne, K Huchra, JP Kaspi, S Kriss, GA Krolik, JH Malkan, MA Malkov, YF Netzer, H O'Brien, PT Peterson, BM Pogge, RW Pronik, VI Qian, BC Reichert, GA Rodriguez-Pascual, PM Sergeev, SG Tao, J Tokarz, S Wagner, RM Wamsteker, W Wilkes, BJ TI Monitoring of the optical and 2.5-11.7 mu m spectrum and mid-IR imaging of the Seyfert 1 galaxy Mrk 279 with ISO SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE galaxies : active; galaxies : individual : Mrk 279; galaxies : nuclei; galaxies : Seyfert; infrared : galaxies ID ACTIVE GALACTIC NUCLEI; BROAD-LINE REGION; ADAPTIVE OPTICS; X-RAY; INFRARED VARIABILITY; HOMOGENEOUS SAMPLE; HOT DUST; EMISSION; QUASARS; SPECTROSCOPY AB Mid-infrared images of the Seyfert 1 galaxy Mrk 279 obtained with the ISO satellite are presented together with the results of a one-year monitoring campaign of the 2.5-11.7 mum spectrum. Contemporaneous optical photometric and spectrophotometric observations are also presented. The galaxy appears as a point-like source at the resolution of the ISOCAM instrument (4-5 "). The 2.5-11.7 mum average spectrum of the nucleus in Mrk 279 shows a strong power law continuum with alpha = -0.80 +/- 0.05 (F nu proportional to nu (alpha)) and weak PAK emission features. The Mrk 279 spectral energy distribution shows a mid-IR bump, which extends from 2 to 15-20 mum The mid-IR bump is consistent with thermal emission from dust grains at a distance of greater than or similar to 100 It-d. No significant variations of the mid-IR flux have been detected during our observing campaign, consistent with the relatively low amplitude (similar to 10% rms) of the optical variability during the campaign. The time delay for H beta line emission in response to the optical continuum variations is tau = 16.7(-5.6)(+5.3), days, consistent with previous measurements. C1 ESA, Dept Space Sci, Div Astrophys, Sci Operat Ctr XMM, E-28080 Madrid, Spain. ESA, Dept Space Sci, Div Astrophys, Sci Operat Ctr ISO, E-28080 Madrid, Spain. European Space Agcy, Estec, Dept Space Sci, Astrophys Div,Integral Sci Operat Ctr, NL-2200 AG Noordwijk, Netherlands. European So Observ, Santiago 19, Chile. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Comp Sci Corp, Greenbelt, MD 20771 USA. Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England. Tel Aviv Univ, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. Tel Aviv Univ, Wise Observ, Raymond & Beverly Sackler Fac Exact Sci, IL-69978 Tel Aviv, Israel. Univ St Andrews, Sch Phys & Astron, St Andrews KY16 9SS, Fife, Scotland. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Calif Los Angeles, Dept Astron, Los Angeles, CA 90024 USA. Crimean Astrophys Observ, UA-334413 Nauchnyi, Ukraine. Shanghai Astron Observ, Shanghai 200030, Peoples R China. NASA, Goddard Space Flight Ctr, Space Sci Data Operat Off, Raytheon ITSS, Greenbelt, MD 20771 USA. Univ Europea Madrid, Dept Fis, Madrid 28670, Spain. ESA, IUE Observ, Madrid 28080, Spain. RP ESA, Dept Space Sci, Div Astrophys, Sci Operat Ctr XMM, POB 50727, E-28080 Madrid, Spain. EM msantos@xmm.vilspa.esa.es OI Wilkes, Belinda/0000-0003-1809-2364; Altieri, Bruno/0000-0003-3936-0284 NR 47 TC 24 Z9 24 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD APR PY 2001 VL 369 IS 1 BP 57 EP 64 DI 10.1051/0004-6361:20010103 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 423UH UT WOS:000168195800009 ER PT J AU Leinert, C Beck, TL Ligori, S Simon, M Woitas, J Howell, RR AF Leinert, C Beck, TL Ligori, S Simon, M Woitas, J Howell, RR TI The near-infrared and ice-band variability of Haro 6-10 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : binaries : close; infrared : stars; stars : individual : Haro-10; stars : pre-main sequence; stars : variables : general ID T-TAURI STARS; YOUNG STARS; OBJECTS; SPECTROSCOPY; COMPANION; IMAGES AB We have monitored the angularly resolved near infrared and 3.1 mum ice-band flux of the components of the young binary Haro 6-10 on 23 occasions during the years 1988 to 2000. Our observations reveal that both the visible star Hare 6-10 (Haro 6-10S) and its infrared companion (Haro 6-10N) show significant variation in flux on time scales as short as a month. The substantial flux decrease of Hare 6-10S over the last four years carries the reddening signature of increased extinction. However, a comparable K-band flux increase observed in the IRC is associated with a dimming in the H-band and cannot be explained by lower extinction. Absorption in the 3.1 mum water-ice feature was always greater towards the IRC during our observations, indicating a larger amount of obscuring material along its line of sight. We detect variability in the ice-band absorption towards Hare 6-10S and Hare 6-10N, significant at the 3.5 sigma and 2.0 sigma levels, respectively. C1 Max Planck Inst Astron, D-69117 Heidelberg, Germany. SUNY Stony Brook, Stony Brook, NY 11974 USA. Univ Hawaii, NASA, Honolulu, HI 96822 USA. Univ Wyoming, Laramie, WY 82071 USA. RP Leinert, C (reprint author), Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany. EM leinert@mpia-hd.mpg.de OI Ligori, Sebastiano/0000-0003-4172-4606 NR 23 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 APR PY 2001 VL 369 IS 1 BP 215 EP 221 DI 10.1051/0004-6361:20010111 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 423UH UT WOS:000168195800023 ER PT J AU Fynbo, JU Jensen, BL Gorosabel, J Hjorth, J Pedersen, H Moller, P Abbott, T Castro-Tirado, AJ Delgado, D Greiner, J Henden, A Magazzu, A Masetti, N Merlino, S Masegosa, J Ostensen, R Palazzi, E Pian, E Schwarz, HE Cline, T Guidorzi, C Goldsten, J Hurley, K Mazets, E McClanahan, T Montanari, E Starr, R Trombka, J AF Fynbo, JU Jensen, BL Gorosabel, J Hjorth, J Pedersen, H Moller, P Abbott, T Castro-Tirado, AJ Delgado, D Greiner, J Henden, A Magazzu, A Masetti, N Merlino, S Masegosa, J Ostensen, R Palazzi, E Pian, E Schwarz, HE Cline, T Guidorzi, C Goldsten, J Hurley, K Mazets, E McClanahan, T Montanari, E Starr, R Trombka, J TI Detection of the optical afterglow of GRB 000630: Implications for dark bursts SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE cosmology : observations; gamma rays : bursts ID GAMMA-RAY BURST; 28 FEBRUARY 1997; ERROR BOX; EMISSION; SUPERNOVA; GRB-970228 AB We present the discovery of the optical transient of the long-duration gamma-ray burst GRB 000630. The optical transient was detected with the Nordic Optical Telescope 21.1 hours after the burst. At the time of discovery the magnitude of the transient was R = 23.04 +/- 0.08. The transient displayed a power-law decline characterized by a decay slope of alpha = -1.035 +/- 0.097. A deep image obtained 25 days after the burst shows no indication of a contribution from a supernova or a host galaxy at the position of the transient. The closest detected galaxy is a R = 324.68 +/- 0.15 galaxy 2.0 arcsec north of the transient. The magnitudes of the optical afterglows of GRB 980329, GRB 980613 and GRB 000630 were all R greater than or similar to 23 less than 24 hours from the burst epoch. We discuss the implications of this for our understanding of GRBs without detected optical transients. We conclude that i) based on the gamma-ray: properties of the current sample we cannot conclude that GRBs with no detected OTs belong to another class of GRBs than GRBs with detected OTs and ii) the majority (greater than or similar to 75%) of GRBs for which searches for optical afterglow have been unsuccessful are consistent with no detection if they were similar to bursts like GRP, 000630 at optical wavelengths. C1 Univ Copenhagen, Astron Observ, DK-2100 Copenhagen O, Denmark. European So Observ, D-85748 Garching, Germany. Danish Space Res Inst, DK-2100 Copenhagen O, Denmark. Nord Opt Telescope, Santa Cruz La Palma 38700, Spain. CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain. Stockholm Observ, S-13336 Saltsjobaden, Sweden. Inst Astrophys, D-14482 Potsdam, Germany. USN Observ, Univ Space Res Assoc, Flagstaff, AZ USA. Telescopio Nazl Galileo, Santa Cruz La Palma, Spain. CNR, Ist Tecnol & Studio Radiaz Extraterr, I-40129 Bologna, Italy. Univ Tromso, Dept Phys, N-9001 Tromso, Norway. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Ferrara, Dipartmento Fis, I-44100 Ferrara, Italy. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. AF Ioffe Physicotech Inst, St Petersburg 194021, Russia. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. RP Fynbo, JU (reprint author), Univ Copenhagen, Astron Observ, Juliane Maries Vej 30, DK-2100 Copenhagen O, Denmark. EM jfynbo@eso.org RI McClanahan, Timothy/C-8164-2012; Jensen, Brian Lindgren/E-1275-2015; Palazzi, Eliana/N-4746-2015; OI Jensen, Brian Lindgren/0000-0002-0906-9771; Masegosa, J./0000-0002-3170-4137; Magazzu, Antonio/0000-0003-1259-4371; Palazzi, Eliana/0000-0002-8691-7666; Castro-Tirado, A. J./0000-0003-2999-3563; Masetti, Nicola/0000-0001-9487-7740; Pian, Elena/0000-0001-8646-4858 NR 44 TC 129 Z9 130 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD APR PY 2001 VL 369 IS 2 BP 373 EP 379 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 426GZ UT WOS:000168342600007 ER PT J AU Suchkov, AA AF Suchkov, AA TI Evidence for prolonged main sequence stellar evolution of F stars in close binaries SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE binaries : close; stars : evolution ID HIPPARCOS PHOTOMETRY; ECLIPSING BINARIES; NDAC REDUCTIONS; BETA PHOTOMETRY; OPEN CLUSTERS; CALIBRATIONS; VELOCITY; UVBY AB Binary F stars exhibit large brightness anomaly; which is defined here as the difference between. the absolute magnitude from the uvby photometry and the actual absolute magnitude of the star. we have found that the anomaly inversely correlates with thf binary components separation. There is evidence that the correlation reflects actual population differences between close and wide binary pairs, in which case it indicates that the anomaly is somehow associated with the interaction of binary's components, The anomaly has also been found to correlate with both kinematics and metallicity. The sense of the correlations implies that the anomaly increases as the star evolves, suggesting a peculiar evolution of a primary F star in a tight binary pair. This conclusion has further been supported by the study of the age-velocity relation (AVR) of F stars that are cataloged in the HIPPARCOS as single. Among these stars, those with brightness anomaly were previously shown to be most likely unidentified close binaries. We have found that the AVR of these binary; candidates is different from that of the "truly single": F stars. The discrepancy between the two AVRs indicates that the putative binaries are, on average; older than similar normal single F stars at the same effective temperature and luminosity, which is consistent with the inferred peculiar evolution in close binaries. It all appears that this peculiarity is caused by the impact of the components interaction in a tight pair on stellar evolution. which results in the prolonged main sequence lifetime of the primary F star. C1 NASA, Space Telescope Sci Inst, Baltimore, MD 21218 USA. RP Suchkov, AA (reprint author), NASA, Space Telescope Sci Inst, Baltimore, MD 21218 USA. EM suchkov@stsci.edu NR 19 TC 4 Z9 4 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 APR PY 2001 VL 369 IS 2 BP 554 EP 560 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 426GZ UT WOS:000168342600023 ER PT J AU Davies, AG AF Davies, AG TI Volcanism on Io: the view from Galileo SO ASTRONOMY & GEOPHYSICS LA English DT Article ID INFRARED MAPPING SPECTROMETER; SILICATE VOLCANISM; THERMAL EMISSION; TIDAL DISSIPATION; ACTIVE VOLCANISM; LAVA FLOWS; HEAT-FLOW; HOT-SPOTS; TEMPERATURE; MODELS C1 Jet Prop Lab, Galileo NIMS Team, Pasadena, CA 91109 USA. RP Davies, AG (reprint author), Jet Prop Lab, Galileo NIMS Team, Pasadena, CA 91109 USA. NR 45 TC 10 Z9 10 U1 0 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 1366-8781 J9 ASTRON GEOPHYS JI Astron. Geophys. PD APR PY 2001 VL 42 IS 2 BP 10 EP 15 DI 10.1046/j.1468-4004.2001.42210.x PG 6 WC Astronomy & Astrophysics; Geochemistry & Geophysics SC Astronomy & Astrophysics; Geochemistry & Geophysics GA 421AP UT WOS:000168040200016 ER PT J AU Gorham, PW AF Gorham, PW TI On the possibility of radar echo detection of ultra-high energy cosmic ray- and neutrino-induced extensive air showers SO ASTROPARTICLE PHYSICS LA English DT Article DE cosmic-rays; cosmic-ray detectors; extensive air showers; neutrinos; radar AB We revisit and extend the analysis supporting a 60-year-old suggestion that cosmic rays air showers resulting from primary particles with energies above 10(18) eV should be straightforward to detect with radar ranging techniques, where the radar echoes are produced by scattering from the column of ionized air produced by the shower. The idea has remained curiously untested since it was proposed, but if our analysis is correct, such techniques could provide a significant alternative approach to air shower detection in a standalone array with high duty cycle, and might provide highly complementary measurements of air showers detected in existing and planned ground arrays such as the Fly's Eye or the Auger Project. The method should be particularly sensitive to showers that are transverse to and relatively distant from the detector, and is thus effective in characterizing penetrating horizontal showers such as those that might be induced by ultra-high energy neutrino primaries. Published by Elsevier Science B.V. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gorham, PW (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 49 TC 25 Z9 25 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-6505 J9 ASTROPART PHYS JI Astropart Phys. PD APR PY 2001 VL 15 IS 2 BP 177 EP 202 DI 10.1016/S0927-6505(00)00143-2 PG 26 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 417PG UT WOS:000167842900003 ER PT J AU Blasi, P AF Blasi, P TI The non-thermal radiation-cluster merger connection SO ASTROPARTICLE PHYSICS LA English DT Article ID COSMIC-RAY ELECTRONS; MAGNETIC-FIELDS; COMA-CLUSTER; RELATIVISTIC ELECTRONS; SHOCK ACCELERATION; NONTHERMAL ENERGY; MERGING CLUSTERS; GALAXIES; EMISSION; ORIGIN AB There is compelling evidence that at least some clusters of galaxies are powerful sources of non-thermal radiation. In all cases where this radiation has been detected, a general trend is that high energy densities of cosmic rays and correspondingly low values of the average magnetic field are required in order to have a self-consistent picture of the multiwavelength observations. Mergers of clusters of galaxies might provide large enough cosmic ray injection rates and at the same time provide the mechanism for the heating of the intracluster medium to the observed temperatures. In this paper we analyze critically all the components that play a role in the non-thermal emission of clusters during a merger, with special attention to mergers occurred in the past of the cluster. We outline the consequences of this model for high energy gamma ray observations and for Faraday rotation measurements of the intracluster magnetic field. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Fermilab Natl Accelerator Lab, NASA, Fermilab Theoret Astrophys Grp, Batavia, IL 60510 USA. RP Blasi, P (reprint author), Fermilab Natl Accelerator Lab, NASA, Fermilab Theoret Astrophys Grp, Box 500, Batavia, IL 60510 USA. RI Blasi, Pasquale/O-9345-2015 OI Blasi, Pasquale/0000-0003-2480-599X NR 49 TC 55 Z9 55 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-6505 J9 ASTROPART PHYS JI Astropart Phys. PD APR PY 2001 VL 15 IS 2 BP 223 EP 240 DI 10.1016/S0927-6505(00)00149-3 PG 18 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 417PG UT WOS:000167842900007 ER PT J AU Smith, DA Georgantopoulos, I Warwick, RS AF Smith, DA Georgantopoulos, I Warwick, RS TI Variable X-ray absorption in the Seyfert 2 galaxy Markarian 348 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (Markarian 348); galaxies : Seyfert; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; COUNTER ARRAY PCA; TIMING EXPLORER; ASCA OBSERVATIONS; LINE REGIONS; COLD MATTER; EMISSION; REFLECTION; SPECTRUM; SPECTROPOLARIMETRY AB We present Rossi X-Ray Timing Explorer monitoring observations of the Seyfert 2 galaxy Mrk 348 spanning a 6 month period. The time-averaged spectrum in the 3-20 keV band shows many features characteristic of a Compton-thin Seyfert 2 galaxy, namely, a hard underlying power-law continuum (Gamma approximate to 1.8) with heavy soft X-ray absorption (N-H similar to 10(23) cm(-2)) plus measurable iron K alpha emission (equivalent width similar to 100 eV) and, at high energy, evidence for a reflection component (R less than or similar to 1). During the first half of the monitoring period, the X-ray continuum flux from Mrk 348 remained relatively steady. However, this was followed by a significant brightening of the source (by roughly a factor of 4) with the fastest change corresponding to a doubling of its X-ray flux on a timescale of about 20 days. The flux increase was accompanied by a marked softening of the X-ray spectrum most likely attributable to a factor of similar to3 decline in the intrinsic line-of-sight column density. In contrast, the iron K alpha line and the reflection components showed no evidence of variability. These observations suggest a scenario in which the central X-ray source is surrounded by a patchy distribution of absorbing material located within about a light-week of the nucleus of Mrk 348. The random movement of individual clouds within the absorbing screen, across our line of sight, produces substantial temporal variations in the measured column density on timescales of weeks to months and gives rise to the observed X-ray spectral variability. However, as viewed from the nucleus, the global coverage and typical thickness of the cloud layer remains relatively constant. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Natl Observ Athens, Athens 15236, Greece. Univ Leicester, Dept Phys & Astron, Leicester LEI 7RH, Leics, England. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Smith, DA (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. RI Georgantopoulos, Ioannis/L-3687-2013 NR 62 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 APR 1 PY 2001 VL 550 IS 2 BP 635 EP 643 DI 10.1086/319778 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FM UT WOS:000167993900011 ER PT J AU Kazanas, D Nayakshin, S AF Kazanas, D Nayakshin, S TI Modeling the X-ray-optical correlations in NGC 3516 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; galaxies : active; galaxies : individual (NGC 3516); galaxies : Seyfert; ultraviolet : galaxies; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; ACCRETION DISK MODELS; BROAD-LINE REGION; COLD MATTER; BLACK-HOLE; TIME LAGS; NGC 7469; ULTRAVIOLET EXCESS; COMPTON REFLECTION; SPECTRA AB We test the "reprocessing paradigm" of optical-UV active galactic nucleus (AGN) variability, according to which the variations in this wavelength range are driven by a variable X-ray component, by detailed modeling of the correlated X-ray-optical (3590 and 5510 Angstrom) variability of the recent multi- wavelength campaign of NGC 3516. To this end we produce model optical light curves by convolving the observed X-ray flux with the response function of an infinite, thin accretion disk, illuminated by a pointlike X-ray source located at a given height h(X) above the compact object (the lamppost model). We also produce the ionized X-ray reflection and Fe K alpha line spectra that result from the reprocessing of the same X-rays on the disk surface. Then we compare the properties of the model light curves (amplitude, morphology, lags) as well as those of the Fe K alpha line profiles to those observed. Our calculations improve on those of similar past treatments by including the effects of an X-ray-heated ionized layer in hydrostatic equilibrium on its surface, which greatly affects its X-ray timing and spectral properties. The results of our calculations do not provide a clear-cut picture that would either support or refute the reprocessing paradigm: despite the large (similar or equal to 50%) amplitude excursions of the X-ray flux, the model optical light curves exhibit variability amplitudes of only 3%-4% and vary in synchrony in the two bands, in agreement with observations. However, the model light curves, when viewed in detail, do not have a direct correspondence to those observed. Futhermore, while the observed intraband synchrony generally points toward smaller values for the black hole mass (M = 10(7) M.), the X-ray Fe K alpha line, X-ray reflection, and optical-UV spectra seem to favor larger mass values (M = 10(8) M.). Generally, no combination of the model parameters seems to produce agreement with the ensemble of the constraints imposed by optical/ UV/X-ray spectral and timing observations; we are thus led to believe that the simplest version of the lamppost model geometry is inconsistent with the NGC 3516 observations. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. NR 34 TC 17 Z9 17 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 APR 1 PY 2001 VL 550 IS 2 BP 655 EP 667 DI 10.1086/319786 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FM UT WOS:000167993900013 ER PT J AU Joseph, CL Merritt, D Olling, R Valluri, M Bender, R Bower, G Danks, A Gull, T Hutchings, J Kaiser, ME Maran, S Weistrop, D Woodgate, B Malumuth, E Nelson, C Plait, P Lindler, D AF Joseph, CL Merritt, D Olling, R Valluri, M Bender, R Bower, G Danks, A Gull, T Hutchings, J Kaiser, ME Maran, S Weistrop, D Woodgate, B Malumuth, E Nelson, C Plait, P Lindler, D TI The nuclear dynamics of M32. I. Data and stellar kinematics SO ASTROPHYSICAL JOURNAL LA English DT Article DE celestial mechanics, stellar dynamics; galaxies : elliptical and lenticular, cD; galaxies : individual (M32); galaxies : kinematics and dynamics; galaxies : nuclei; galaxies : structure ID MASSIVE BLACK-HOLE; VELOCITY PROFILES; PENALIZED LIKELIHOOD; ELLIPTIC GALAXIES; SPACE-TELESCOPE; MODELS; DISTRIBUTIONS; RESOLUTION AB We have obtained optical long-slit spectroscopy of the nucleus of M32 using the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. The stellar rotation velocity and velocity dispersion, as well as the full line-of-sight velocity distribution (LOSVD), were determined as a function of position along the slit using two independent spectral deconvolution algorithms. We see three clear kinematical signatures of the nuclear black hole : a sudden upturn, at similar to0."3 from the center, in the stellar velocity dispersions; a flat or rising rotation curve into the center; and strong, non-Gaussian wings on the central LOSVD. The central velocity dispersion is similar to 130 km s(-1) (Gaussian fit) or greater than or similar to 175 km s(-1) (corrected for the wings). The central kinematics are consistent with the presence of a supermassive compact object in M32 with a mass in the range (2-4) x 10(6) M.. C1 Rutgers State Univ, Dept Phys & Astron, Piscataway, NJ 08855 USA. Univ Chicago, Chicago, IL 60637 USA. Univ Sternwarte Gottingen, D-81679 Munich, Germany. Natl Opt Astron Observ, Tucson, AZ 85726 USA. NASA, Goddard Space Flight Ctr, RPSC, Greenbelt, MD 20771 USA. Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Nevada, Dept Phys, Las Vegas, NV 89154 USA. Adv Comp Concepts Inc, Potomac, MD 20854 USA. RP Joseph, CL (reprint author), Rutgers State Univ, Dept Phys & Astron, POB 849, Piscataway, NJ 08855 USA. RI Gull, Theodore/D-2753-2012; Valluri, Monica/A-3974-2013 OI Gull, Theodore/0000-0002-6851-5380; NR 32 TC 46 Z9 46 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 APR 1 PY 2001 VL 550 IS 2 BP 668 EP 690 DI 10.1086/319781 PN 1 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FM UT WOS:000167993900014 ER PT J AU Feibelman, WA AF Feibelman, WA TI Electron densities, radial and terminal wind velocities for the planetary nebula NGC 6302 and its O VI-type binary nucleus SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : general; line : identification; planetary nebulae : general; planetary nebulae : individual (NGC 6302); ultraviolet : general ID ULTRAVIOLET-SPECTRA; GASEOUS NEBULAE; IUE SPECTRA; EMISSION-LINES; CENTRAL STAR; NGC-6302; REGIONS; IV; NGC-6537; SEQUENCE AB Archival high- and low-dispersion IUE spectra of NGC 6302 and its nucleus have been analyzed. The spectra in the NEWSIPS format reveal many high-excitation emission features, including stellar O V, O VI, O VII, and O VIII that identify the nucleus as a new member of the "O VI sequence." Fe II features that are resonantly excited by O VI lambda 1032 are also observed. Other high-excitation species include [Ne IV], [Ne V], [Mg VI], and [Si VII]. Electron densities were determined from C III], N III], N IV], and [Ne IV] and are compared to IR [Ne V] densities. Radial velocities of strong emission features cluster around -55 km s(-1) except for the Bowen O III and [O II] lines that show large positive radial velocities. Results from IUE, optical, ground-based IR, and KAO IR data are summarized. A relatively low terminal wind velocity of -520 +/- 200 km s(-1) was estimated from the P Cygni profile of the C IV lambda 1548 feature. A G-type companion to the very hot white dwarf central star is indicated by the LWR/LWP low-dispersion spectra. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Feibelman, WA (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. NR 40 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 APR 1 PY 2001 VL 550 IS 2 BP 785 EP 792 DI 10.1086/319798 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FM UT WOS:000167993900023 ER PT J AU Whittet, DCB Pendleton, YJ Gibb, EL Boogert, ACA Chiar, JE Nummelin, A AF Whittet, DCB Pendleton, YJ Gibb, EL Boogert, ACA Chiar, JE Nummelin, A TI Observational constraints on the abundance and evolution of " XCN" in interstellar grain mantles SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; infrared : ISM : lines and bands; ISM : molecules ID INFRARED-SPECTROSCOPY; MOLECULAR CLOUDS; ICE ANALOGS; DARK CLOUD; SOLID CO; ISOTOPIC-SUBSTITUTION; CHEMICAL-COMPOSITION; MICRON ABSORPTION; PHASE CO; BAND AB The 4.62 mum "XCN" absorption feature, attributed to CN-bearing molecules in solids, is potentially an important diagnostic of the evolution of organic matter in the interstellar medium and the envelopes of newly formed stars. We report quantitative limits on the strength of this feature in the diffuse interstellar medium toward the reddened B-type star Cyg OB2 No. 12 and in the dark cloud toward the young stellar object R CrA IRS 2. On the basis of an assumed band strength for the carrier species, we estimate that less than 0.3% and less than 0.1% of the elemental nitrogen is in CN bonds along these lines of sight, respectively; if they are typical of diffuse and dense environments, it follows that the carrier of XCN is no more than a trace constituent of either organic-refractory or icy interstellar grain mantles. Appreciable XCN abundances seem to occur only in the envelopes of certain young stellar objects (YSOs), most notably the high-mass objects W33A and AFGL 7009S. We confirm the presence of XCN in the spectrum of the low-mass YSO R CrA IRS 7. The strengths of the XCN absorptions in R CrA IRS 7 and other low-mass YSOs indicate mean XCN concentrations relative to H2O in the ices of similar to1%, comparable with the abundance of CN-bearing species in comets. C1 Rensselaer Polytech Inst, Dept Phys Appl Phys & Astron, Troy, NY 12180 USA. Rensselaer Polytech Inst, New York Ctr Studies Origins Life, Troy, NY 12180 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. CALTECH, Downs Lab Phys, Pasadena, CA 91125 USA. SETI Inst, Mt View, CA 94043 USA. RP Whittet, DCB (reprint author), Rensselaer Polytech Inst, Dept Phys Appl Phys & Astron, Troy, NY 12180 USA. NR 49 TC 40 Z9 40 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 APR 1 PY 2001 VL 550 IS 2 BP 793 EP 798 DI 10.1086/319794 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FM UT WOS:000167993900024 ER PT J AU Boroson, B Kallman, T Blondin, JM Owen, MP AF Boroson, B Kallman, T Blondin, JM Owen, MP TI Testing hydrodynamic models of LMC X-4 with ultraviolet and X-ray spectra SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : close; hydrodynamics; X-rays : stars ID DRIVEN STELLAR WINDS; SEMIDETACHED BINARIES; LINE-PROFILES; GAS-DYNAMICS; VELA X-1; LMC-X-4; PHOTOIONIZATION; ACCRETION; SYSTEMS; STARS AB We compare the predictions of hydrodynamic models of the LMC X-4 X-ray binary system with observations of UV P Cygni lines with the Goddard High Resolution Spectrograph and Space Telescope Imaging Spectrograph on the Hubble Space Telescope. The hydrodynamic model determines density and velocity fields of the stellar wind, wind-compressed disk, accretion stream, Keplerian accretion disk, and accretion disk wind. We use a Monte Carlo code to determine the UV P Cygni line profiles by simulating the radiative transfer of UV photons that originate on the star and are scattered in the wind. The qualitative orbital variation predicted is similar to that observed, although the model fails to reproduce the strong orbital asymmetry (the observed absorption is strongest for phi > 0.5). The model predicts a mideclipse X-ray spectrum, caused almost entirely by Compton scattering, with a factor of 4 less flux than observed with ASCA. We discuss how the model may need to be altered to explain the spectral variability of the system. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. N Carolina State Univ, Dept Phys, Raleigh, NC 27695 USA. RP Boroson, B (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 45 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 APR 1 PY 2001 VL 550 IS 2 BP 919 EP 930 DI 10.1086/319773 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FM UT WOS:000167993900036 ER PT J AU Smale, AP Church, MJ Balucinska-Church, M AF Smale, AP Church, MJ Balucinska-Church, M TI The ephemeris and dipping spectral behavior of 4U 1624-49 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : close; circumstellar matter; stars : individual (4U 1624-49); stars : neutron; X-rays : stars ID RAY TIMING EXPLORER; QUASI-PERIODIC OSCILLATION; BINARY EXO 0748-676; X-RAY; ASCA OBSERVATION; DISCOVERY; PERFORMANCE; ABSORPTION; 4U1624-49; INTENSITY AB We present striking results from Rossi X-Ray Timing Explorer (RXTE) observations of the 21 hr low-mass X-ray binary 4U 1624-49, showing five complex dips in unprecedented detail. For the first time, dipping is detected up to 15 keV. Prominent flares are also observed in the light curves, limited to energies above similar to8 keV. Spectra selected by intensity during dip episodes can be well fitted with a two-component model consisting of a pointlike blackbody from the neutron star and progressive covering of an extended Comptonized region, presumably an accretion disk corona (ADC), corrected for photons scattered into and out of the X-ray beam by a interstellar dust halo. We find that the outer regions of the absorber are highly ionized and that electron scattering is totally responsible for the X-ray attenuation during shallow dipping. The timescales of dip ingress and egress indicate that the envelope of material absorbing the ADC has smaller angular size than the ADC itself and that the ADC is likely limited to a height-to-radius ratio of 10% rather than being spherical in extent. In addition, we have analyzed similar to4.5 yr of RXTE All-Sky Monitor (ASM) coverage to derive the first accurate orbital ephemeris for 4U 1624-49, with phase zero (the time of dip centers) well described by the relation 2,450,088.63918(69) + N + 0. 869907(12) (JD). C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. Univ Space Res Assoc, Columbia, MD 21044 USA. RP Smale, AP (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 29 TC 33 Z9 33 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 APR 1 PY 2001 VL 550 IS 2 BP 962 EP 969 DI 10.1086/319800 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FM UT WOS:000167993900039 ER PT J AU Ebisawa, K Mukai, K Kotani, T Asai, K Dotani, T Nagase, F Hartmann, HW Heise, J Kahabka, P Van Teeseling, A AF Ebisawa, K Mukai, K Kotani, T Asai, K Dotani, T Nagase, F Hartmann, HW Heise, J Kahabka, P Van Teeseling, A TI X-ray energy spectra of the supersoft X-ray sources CAL 87 and RX J0925.7-4758 observed with ASCA SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; stars : individual (CAL 87, RX J0925.7-4758); white dwarfs; X-rays : stars ID NLTE MODEL ATMOSPHERES; LARGE MAGELLANIC CLOUD; WHITE-DWARFS; BINARY; STARS; FIELDS; MASS; LMC AB We report observation results of the supersoft X-ray sources CAL 87 and RX J0925.7-4758 with the X-ray CCD cameras (Solid-State Imaging Spectrometers [SISs]) on board ASCA. Because of the superior energy resolution of the SIS (DeltaE/E similar to 10% at 1 keV) relative to previous instruments, we could study detailed X-ray spectral structures of these sources for the first time. We have applied theoretical spectral models to CAL 87 and constrained the white dwarf mass and intrinsic luminosity as 0.8-1.2 M. and 4 x 10(37)-1.2 x 10(38) ergs s(-1), respectively. However, we have found the observed luminosity is an order of magnitude smaller than the theoretical estimate, which indicates that the white dwarf is permanently blocked by the accretion disk, and we are observing a scattering emission by a fully ionized accretion disk corona (ADC) whose column density is similar to1.5 x 10(23) cm(-2). Through simulation we have shown that the orbital eclipse can be explained by the ADC model, such that a part of the extended X-ray emission from the ADC is blocked by the companion star filling its Roche lobe. We have found that very high surface gravity and temperature, similar to 10(10) cm s(-2) and similar to 100 eV, respectively, as well as a strong absorption edge at similar to1.02 keV, are required to explain the X-ray energy spectrum of RX J0925.7-4758. These values are only possible for an extremely heavy white dwarf near the Chandrasekhar limit. Although the supersoft source luminosity should be similar to 10(38) ergs s(-1) at the Chandrasekhar limit, the observed luminosity of RX J0925.7-4758 is nearly 2 orders of magnitude smaller, even assuming an extreme distance of similar to 10 kpc. To explain the luminosity discrepancy, we propose a model in which very thick matter that was previously ejected from the system, as a form of jets, intervenes the line of sight and reduces the luminosity significantly because of Thomson scattering. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. SRON, Space Res Lab, NL-3584 CA Utrecht, Netherlands. Univ Amsterdam, Inst Astron, NL-1098 SJ Amsterdam, Netherlands. Univ Amsterdam, Ctr High Energy Astrophys, NL-1098 SJ Amsterdam, Netherlands. Univ Sternwarte Gottingen, D-37083 Gottingen, Germany. Univ Space Res Assoc, Columbia, MD 21044 USA. Natl Res Council, Washington, DC 20418 USA. RP Ebisawa, K (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NR 34 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 APR 1 PY 2001 VL 550 IS 2 BP 1007 EP 1022 DI 10.1086/319806 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FM UT WOS:000167993900043 ER PT J AU Miyata, E Ohta, K Torii, K Takeshima, T Tsunemi, H Hasegawa, T Hashimoto, Y AF Miyata, E Ohta, K Torii, K Takeshima, T Tsunemi, H Hasegawa, T Hashimoto, Y TI On the nature of AX J2049.6+2939/AX J2050.0+2914 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (Cygnus loop); stars : neutron; X-rays : general; X-rays : stars ID GAS IMAGING SPECTROMETER; LOOP SUPERNOVA REMNANT; IN-ORBIT PERFORMANCE; X-RAY; CYGNUS-LOOP; BLACK-HOLE; BOARD ASCA C1 Osaka Univ, Grad Sch Sci, Dept Earth & Space Sci, Toyonaka, Osaka 5600043, Japan. Japan Sci & Technol Corp, CREST, Tsukuba, Ibaraki 3050047, Japan. Kyoto Univ, Fac Sci, Dept Astron, Kyoto 6068502, Japan. NASDA, TKSC, SURP, Tsukuba, Ibaraki 3058505, Japan. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Seabrook, MD 20706 USA. Univ Space Res Assoc, Maebashi, Gumma, Japan. Carnegie Observ, Pasadena, CA 91101 USA. RP Miyata, E (reprint author), Osaka Univ, Grad Sch Sci, Dept Earth & Space Sci, 1-1 Machikaneyama, Toyonaka, Osaka 5600043, Japan. NR 23 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 APR 1 PY 2001 VL 550 IS 2 BP 1023 EP 1029 DI 10.1086/319770 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FM UT WOS:000167993900044 ER PT J AU Reames, DV Ng, CK Berdichevsky, D AF Reames, DV Ng, CK Berdichevsky, D TI Angular distributions of solar energetic particles SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; shock waves; Sun : corona; Sun : particle emission ID INTERPLANETARY TRAVELING SHOCKS; HYDROMAGNETIC WAVE EXCITATION; CORONAL MASS EJECTIONS; MAGNETIC-FIELD; ION-ACCELERATION; EVENTS; TRANSPORT; WIND; HELIOSPHERE; ABUNDANCES AB We report observations, using data from the Wind spacecraft, of temporal variations in the angular distributions of H, He, O, and Fe ions at MeV energies during solar energetic particle (SEP) events under a variety of conditions. Detailed time-dependent angular distributions of O and Fe during SEP events are reported for the first time. Extended periods of particle streaming in small gradual events are consistent with continued acceleration that is expected at shock waves driven from the Sun by coronal mass ejections (CMEs). Particles accelerated from SEP events of moderate size show especially strong streaming along the magnetic fields inside an old CME. For the largest events, however, streaming rapidly diminishes, showing behavior that is qualitatively consistent with the theory of Ng et al. In very intense events, that theory predicts rapid growth of proton-generated waves, even near and Alfven beyond 1 AU, that soon scatter and isotropize the particles. We show, for the first time, cases where SEP streaming is organized by the value of the plasma beta beta (p), the ratio of the proton thermal energy to magnetic energy. Higher initial turbulence in the high-beta (p) plasma may require less additional wave high-b p growth to reach significant levels of scattering in the largest SEP events. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Raytheon ITSS Corp, Lanham, MD 20706 USA. RP Reames, DV (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 38 TC 34 Z9 34 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 APR 1 PY 2001 VL 550 IS 2 BP 1064 EP 1074 DI 10.1086/319810 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FM UT WOS:000167993900048 ER PT J AU Hudson, RL Moore, MH Gerakines, PA AF Hudson, RL Moore, MH Gerakines, PA TI The formation of cyanate ion (OCN-) in interstellar ice analogs SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : molecules; line : formation; line : identification; molecular processes ID XCN BAND; INFRARED-SPECTROSCOPY; ABSORPTION FEATURES; MICRON ABSORPTION; ORGANIC-MOLECULES; GRAIN MANTLES; IRRADIATION; MIXTURES; SPECTRUM; FROZEN AB Although the 2165 cm(-1) (4.62 mum) "XCN" IR absorption in interstellar ices was first detected over 20 years ago, its assignment has remained controversial, and its mode of formation has seldom been studied. Here we report an extensive laboratory investigation of this band's formation in interstellar ice analogs. Ices with known or suspected interstellar molecules were proton-irradiated at 15-25 K to simulate interstellar energetic processing, and their IR spectra were recorded. Reactions for irradiated mixtures showing an XCN spectral band have been developed based on results with chemically related systems and with over 60 ices examined here. Combined with previous work, our new results leave no doubt that the band produced in the laboratory is due to OCN-, the cyanate anion. Tests of the reactions leading to OCN- are described, and independent methods of producing OCN- are reported. The results of all of these new experiments help reveal the chemistry underlying this ion's formation and establish some of the conditions under which OCN- might be found in interstellar ices. They also show that energetic processing is an efficient way to produce OCN- in interstellar ices and that temperature increases to promote acid-base chemistry are unnecessary. C1 Eckerd Coll, Dept Chem, St Petersburg, FL 33733 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Alabama Birmingham, Dept Phys, Birmingham, AL 35294 USA. RP Eckerd Coll, Dept Chem, St Petersburg, FL 33733 USA. EM hudsonrl@eckerd.edu; ummhm@lepvax.gsfc.nasa.gov; gerakine@phy.uab.edu RI Gerakines, Perry/B-9705-2009; Hudson, Reggie/E-2335-2012; Gerakines, Perry/D-2226-2012 OI Gerakines, Perry/0000-0002-9667-5904 NR 48 TC 68 Z9 68 U1 1 U2 14 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 APR 1 PY 2001 VL 550 IS 2 BP 1140 EP 1150 DI 10.1086/319799 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FM UT WOS:000167993900055 ER PT J AU Chiar, JE Tielens, AGGM AF Chiar, JE Tielens, AGGM TI Circumstellar carbonaceous material associated with late-type dusty WC Wolf-Rayet stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; Galaxy : center; infrared : ISM; lines and bands; infrared : stars; ISM : molecules ID HYDROGENATED AMORPHOUS-CARBON; GALACTIC-CENTER; ABUNDANCES; GRAINS; SPECTROSCOPY; EXTINCTION; MOLECULES; BANDS AB We have studied the 5-8.5 mum infrared spectra of the late-type Wolf-Rayet stars WR 118, WR 112, and WR 104, the WN star WR 147, the B5 hypergiant Cygnus OB2 No. 12, and the Galactic center luminous blue variable Pistol Star using the Short Wavelength Spectrometer on the Infrared Space Observatory. We attribute an absorption feature at 6.2 mum in the spectra of WC stars to amorphous carbon dust. This absorption feature is not detected in the diffuse interstellar medium toward the WR 147, Cyg OB2 No. 12, or the Pistol Star, and therefore we suggest that it is circumstellar in nature. In addition, we detect a broad absorption feature extending from approximately 6.5 to 8 mum. We tentatively attribute this absorption to the C-C stretching modes that accompany the 6.2 mum band in aromatic materials. Our analysis of the 6.2 mum absorption profile suggests that the dust grains have to be rather large (similar to1 mum) and point toward dense clumps as the sites of dust formation. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SETI Inst, Mt View, CA 94043 USA. Kapteyn Astron Inst, SRON, NL-9700 AV Groningen, Netherlands. RP Chiar, JE (reprint author), NASA, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. NR 34 TC 29 Z9 29 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 APR 1 PY 2001 VL 550 IS 2 BP L207 EP L211 DI 10.1086/319631 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FN UT WOS:000167994000020 ER PT J AU Jayawardhana, R Wolk, SJ Navascues, DBY AF Jayawardhana, R Wolk, SJ Navascues, DBY TI Protoplanetary disks in the nearest star-forming cloud: Mid-infrared imaging and optical spectroscopy of MBM 12 members SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; circumstellar matter; open clusters and associations : individual (MBM 12); planetary systems; stars : formation; stars : pre-main-sequence ID T-TAURI STARS; EMISSION; SEARCH AB The recent identification of several groups of young stars within 100 pc of the Sun has generated widespread interest. Given their proximity and possible age differences, these systems are ideally suited for detailed studies of star and planet formation. Here we report on the first investigation of protoplanetary disks in one such group, the high-latitude cloud MBM 12 at a distance of similar to 65 pc. We present mid-infrared observations of the eight candidate pre-main-sequence (PMS) members and the two main-sequence (MS) stars in the same line of sight, which may or may not be associated with the group. We have also derived H alpha and Li line widths from medium-resolution optical spectra. We report the discovery of significant mid-infrared excess from six PMS stars-LkH alpha 262, LkH alpha 263, LkH alpha 264, E02553 + 2018, RX J0258.3 + 1947, and S18-presumably due to optically thick circumstellar disks. Our flux measurements for the other two PMS stars and the two MS stars are consistent with photospheric emission, allowing us to rule out dusty inner disks. The disks we have found in MBM 12 represent the nearest known sample of very young protoplanetary systems and thus are prime targets for high-resolution imaging at infrared and millimeter wavelengths. C1 Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Autonoma Madrid, Dept Fis Teor, E-28049 Madrid, Spain. Max Planck Inst Astron, D-69117 Heidelberg, Germany. Univ Florida, Dept Astron, Gainesville, FL 32611 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jayawardhana, R (reprint author), Univ Calif Berkeley, Dept Astron, 601 Campbell Hall, Berkeley, CA 94720 USA. RI Barrado Navascues, David/C-1439-2017; OI Barrado Navascues, David/0000-0002-5971-9242; Wolk, Scott/0000-0002-0826-9261 NR 20 TC 25 Z9 25 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 APR 1 PY 2001 VL 550 IS 2 BP L197 EP L200 DI 10.1086/319647 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FN UT WOS:000167994000018 ER PT J AU Witt, AN Smith, RK Dwek, E AF Witt, AN Smith, RK Dwek, E TI X-ray halos and large grains in the diffuse interstellar medium SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; ISM : abundances; scattering; X-rays : ISM ID IN-SITU MEASUREMENTS; SIZE DISTRIBUTION; OPTICAL-PROPERTIES; DUST PARTICLES; SCATTERING; POLARIZATION; GRAPHITE; CARBON; METEORITES; EVOLUTION AB Recent observations with dust detectors on board the interplanetary spacecrafts Ulysses and Galileo have recorded a substantial flux of large interstellar grains with radii between 0.25 and 2.0 mum entering the solar system from the local interstellar cloud. The most commonly used interstellar grain size distribution is characterized by an a(-3.5) power law in grain radii a and extends to a maximum grain radius of 0.25 mum. The extension of the interstellar grain size distribution to such large radii will have a major effect on the median grain size and on the amount of mass needed to be tied up in dust for a given visual optical depth. It is therefore important to investigate whether this population of larger dust particles prevails in the general interstellar medium or whether it is merely a local phenomenon. The presence of large interstellar grains can be inferred mainly from their effect on the intensity and radial profile of scattering halos around X-ray sources. In this Letter, we examine the grain size distribution that gives rise to the X-ray halo around Nova Cygni 1992. The results of our study confirm the need to extend the interstellar grain size distribution in the direction of this source to and possibly beyond 2 mum. The model that gives the best fit to the halo data is characterized by (1) a grain size distribution that follows an power law up to a(-3.)5 a 0.50 mum, followed by an a(-4.0) extension from 0.50 to 2.0 mum, and (2) silicate and graphite (carbon) dust-to-gas mass ratios of 0.0044 and 0.0022, respectively, consistent with solar abundance constraints. Additional observations of X-ray halos probing other spatial directions are badly needed to test the general validity of this result. C1 Univ Toledo, Ritter Astrophys Res Ctr, Toledo, OH 43606 USA. Harvard Smithsonian Ctr Astrophys, High Energy Astrophys Div, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Witt, AN (reprint author), Univ Toledo, Ritter Astrophys Res Ctr, 2801 W Bancroft St, Toledo, OH 43606 USA. OI Witt, Adolf/0000-0003-0760-4483 NR 39 TC 28 Z9 29 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 APR 1 PY 2001 VL 550 IS 2 BP L201 EP L205 DI 10.1086/319630 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420FN UT WOS:000167994000019 ER PT J AU Whitson, PA Pietrzyk, RA Sams, CF AF Whitson, PA Pietrzyk, RA Sams, CF TI Urine volume and its effects on renal stone risk in astronauts SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE urine volume; spaceflight; renal calculi ID NEPHROLITHIASIS; FLIGHTS AB Background Urine composition in astronauts during and immediately after spaceflight changes in ways that increase the renal stone-forming potential for calcium oxalate, calcium phosphate, and uric acid saturation. We examined the effect of urine volume on the risk of renal stone formation in 356 astronauts. Methods: Renal stone-forming risk was evaluated from 24-h urine samples collected from astronauts before and after 4- to 17-d Space Shuttle flights. Urinary chemistries were performed and the relative supersaturations of calcium oxalate, brushite, sodium urate, struvite, and uric acid saturation were calculated from the biochemical results. Results: Urinary supersaturation levels of stone-forming salts were inversely related to urinary output both before and after spaceflight. Urine volume > 2 L. d(-1) reduced the risk of renal-stone development without affecting urinary citrate concentrations as compared with the increased risk observed in those astronauts who excreted urine volumes < L. d(-1). Conclusion: Results from this study indicate that increasing daily urinary output alone is an effective countermeasure to reduce the renal stone-forming risk immediately after spaceflight. However, increasing urinary output during flight may not be entirely effective in minimizing the potential risk of renal stone formation due to the changes in the urine chemistry in astronauts exposed to microgravity. C1 NASA, Lyndon B Johnson Space Ctr, Astronaut Off, Houston, TX 77058 USA. Life Sci Res Labs, Biomed Operat & Res Branch, Houston, TX USA. Wyle Labs, Cellular & Mol Res Lab, Houston, TX USA. RP Whitson, PA (reprint author), NASA, Lyndon B Johnson Space Ctr, Astronaut Off, Mail Code CB, Houston, TX 77058 USA. NR 20 TC 18 Z9 19 U1 0 U2 2 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 APR PY 2001 VL 72 IS 4 BP 368 EP 372 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 415HM UT WOS:000167715400007 PM 11318017 ER PT J AU Margulis, L Rummel, JD AF Margulis, L Rummel, JD TI Life in NASA and the rest of the universe: New scientific opportunities SO BIOSCIENCE LA English DT Editorial Material C1 Univ Massachusetts, Dept Geosci, Amherst, MA 01003 USA. NASA, Off Space Sci, Washington, DC 20546 USA. RP Margulis, L (reprint author), Univ Massachusetts, Dept Geosci, Amherst, MA 01003 USA. NR 2 TC 0 Z9 0 U1 0 U2 1 PU AMER INST BIOLOGICAL SCI PI WASHINGTON PA 1444 EYE ST, NW, STE 200, WASHINGTON, DC 20005 USA SN 0006-3568 J9 BIOSCIENCE JI Bioscience PD APR PY 2001 VL 51 IS 4 BP 317 EP 317 DI 10.1641/0006-3568(2001)051[0317:LINATR]2.0.CO;2 PG 1 WC Biology SC Life Sciences & Biomedicine - Other Topics GA 436XA UT WOS:000168960100016 ER PT J AU Dutta, S AF Dutta, S TI Fracture toughness and reliability in high-temperature structural ceramics and composites: Prospects and challenges for the 21st Century SO BULLETIN OF MATERIALS SCIENCE LA English DT Article; Proceedings Paper CT International Conference on Fatigue and Fracture of Glasses, Ceramics and Composites CY SEP, 1999 CL KOLKATA, INDIA SP Mat Res Soc India DE CFCC; toughening; fracture toughness; beta-Si3N4 AB The importance of high fracture toughness and reliability in Si3N4, and SiC-based structural ceramics and ceramic matrix composites is reviewed. The potential of these ceramics and ceramic matrix composites for high temperature applications in defence and aerospace applications such as gas turbine engines, radomes, and other energy conversion hardware have been well recognized. Numerous investigations were pursued to improve fracture toughness and reliability by incorporating various reinforcements such as particulate-, whisker-, and continuous fibre into Si3N4 and SIC matrices. All toughening mechanisms, e,g, crack deflection, crack branching, crack bridging, etc essentially redistribute stresses at the crack tip and increase the energy needed to propagate a crack through the composite material, thereby resulting in improved fracture toughness and reliability, Because of flaw insensitivity, continuous fibre reinforced ceramic composite (CFCC) was Found to have the highest potential for higher operating temperature and longer service conditions. However, the ceramic fibres should display sufficient high temperature strength and creep resistance at service temperatures above 1000 degreesC. The greatest challenge to date is the development of high quality ceramic fibres with associate coatings able to maintain their high strength in oxidizing environment at high temperature. In the area of processing, critical issues are preparation of optimum matrix precursors, precursor infiltration into fibre array, and matrix densification at a temperature, where grain crystallization and fibre degradation do not occur. A broad scope of effort is required for improved processing and properties with a better understanding of all candidate composite systems. C1 NASA, John Glenn Res Ctr, Cleveland, OH 44135 USA. RP Dutta, S (reprint author), NASA, John Glenn Res Ctr, Cleveland, OH 44135 USA. NR 8 TC 9 Z9 9 U1 3 U2 18 PU INDIAN ACADEMY SCIENCES PI BANGALORE PA P B 8005 C V RAMAN AVENUE, BANGALORE 560 080, INDIA SN 0250-4707 J9 B MATER SCI JI Bull. Mat. Sci. PD APR PY 2001 VL 24 IS 2 BP 117 EP 120 DI 10.1007/BF02710086 PG 4 WC Materials Science, Multidisciplinary SC Materials Science GA 431NA UT WOS:000168636400006 ER PT J AU Hou, AY Zhang, SQ da Silva, AM Olson, WS Kummerow, CD Simpson, J AF Hou, AY Zhang, SQ da Silva, AM Olson, WS Kummerow, CD Simpson, J TI Improving global analysis and short-range forecast using rainfall and moisture observations derived from TRMM and SSM/I passive microwave sensors SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID VARIATIONAL DATA ASSIMILATION; NUMERICAL WEATHER PREDICTION; PRECIPITATION DATA; DIABATIC INITIALIZATION; PHYSICAL INITIALIZATION; SATELLITE DATA; MODEL; TROPICS; ALGORITHM; PROFILES AB As a follow-on to the Tropical Rainfall Measuring Mission (TRMM) the National Aeronautics and Space Administration in the United States, the National Space Development Agency of Japan, and the European Space Agency are considering a satellite mission to measure the global rainfall. The plan envisions an improved TRMM-like satellite and a constellation of eight satellites carrying passive microwave radiometers to provide global rainfall measurements at 3-h intervals. The success of this concept relies on the merits of rainfall estimates derived from passive microwave radiom eters. This article offers a proof-of-concept demonstration of the benefits of using rainfall and total precipitable water (TPW) information derived from such instruments in global data assimilation with observations from the TRMM Microwave Imager (TMI) and two Special Sensor Microwave/Imager (SSM/I) instruments. Global analyses that optimally combine observations from diverse sources with physical models of atmospheric and land processes can provide a comprehensive description of the climate systems. Currently, such data analyses contain significant errors in primary hydrological fields such as precipitation and evaporation, especially in the Tropics. It is shown that assimilating the 6-h-averaged TMI and SSM/I surface rain rate and TPW retrievals improves not only the hydrological cycle but also key climate parameters such as clouds, radiation, and the upper-tropospheric moisture in the analysis produced by the Goddard Earth Observing System Data Assimilation System, as verified against radiation measurements by the Clouds and the Ear-th's Radiant Energy System instrument and brightness temperature observations by the Television Infrared Observational Satellite Operational Vertical Sounder instruments. Typically, rainfall assimilation improves clouds and radiation in areas of active convection, as well as the latent heating and large-scale motions in the Tropics, while TPW assimilation leads to reduced moisture biases and improved radiative fluxes in clear-sky regions. Ensemble forecasts initialized with analyses that incorporate TMI and SSM/I rainfall and TPW data also yield better short-range predictions of geopotential heights, winds, and precipitation in the Tropics. These results were obtained using a variational procedure based on a 6-h time integration of a column model of moist physics with prescribed dynamical and other physical tendencies. The procedure estimates moisture tendency cor rctions at observation locations by minimizing the least squares differences between the observed TPW and rain rates those generated by the column model over a 6-h analysis window. These tendency corrections are then applied during the assimilation cycle to compensate for errors arising from both initial conditions and deficiencies in model physics. Our results point to the importance of addressing deficiencies in model physics in assimilating data types such as precipitation, for which the forward model based on convective parameterizations may have significant systematic errors. This study offers a compelling illustration of the potential of using rainfall and TPW information derived from passive microwave instruments to significantly improve the quality of four-dimensional global datasets for climate analysis and weather forecasting applications. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Gen Sci Corp, Sci Applicat Int Corp, Beltsville, MD USA. Univ Maryland Baltimore Cty, Baltimore, MD 21228 USA. RP Hou, AY (reprint author), NASA, Goddard Space Flight Ctr, Code 9103, Greenbelt, MD 20771 USA. RI da Silva, Arlindo/D-6301-2012; Hou, Arthur/D-8578-2012 OI da Silva, Arlindo/0000-0002-3381-4030; NR 35 TC 53 Z9 53 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD APR PY 2001 VL 82 IS 4 BP 659 EP 679 DI 10.1175/1520-0477(2001)082<0659:IGAASF>2.3.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 419KF UT WOS:000167947300007 ER PT J AU Berejikian, BA Tezak, EP Park, L LaHood, E Schroder, SL Beall, E AF Berejikian, BA Tezak, EP Park, L LaHood, E Schroder, SL Beall, E TI Male competition and breeding success in captively reared and wild coho salmon (Oncorhynchus kisutch) SO CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES LA English DT Article ID ATLANTIC SALMON; REPRODUCTIVE-BEHAVIOR; AGONISTIC BEHAVIOR; SOCKEYE-SALMON; PACIFIC SALMON; RAINBOW-TROUT; HATCHERY; PERFORMANCE; SELECTION; TACTICS AB In the Pacific Northwest, releasing captively reared adult salmon (Oncorhynchus spp.) for natural spawning is an evolving strategy for the recovery of imperiled populations. However, the ability of captively reared fish to spawn naturally may be compromised by their artificial rearing environments. In this study, wild coho salmon (O. kisutch) males outcompeted captively reared males and controlled access to spawning females in 11 of 14 paired trials in laboratory stream channels. In two cases where satellite males were observed participating in spawning, DNA genotyping results determined that they did not sire any of the progeny. When spawning occurred at night and was not observed, DNA results confirmed behavior-based determinations of dominance made before dark. Dominance was established soon after the males were introduced into a common arena containing a sexually active female. We hypothesize that decisions by subordinate males to avoid direct competition may have minimized conflict. The competitive inferiority of captively reared coho salmon in this and a previous study probably reflects deficiencies in rearing environments, which fail to produce appropriate body coloration and body shape and perhaps alter natural behavioral development. C1 Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Resource Enhancement & Utilizat Technol Div, Manchester, WA 98353 USA. NOAA, Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Conservat Biol Div, Seattle, WA 98112 USA. Washington Dept Fish & Wildlife, Olympia, WA 98501 USA. Inst Natl Rech Agron, Stn Hydrobiol, F-64210 St Pee Sur Nivelle, France. RP Berejikian, BA (reprint author), Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Resource Enhancement & Utilizat Technol Div, POB 130, Manchester, WA 98353 USA. NR 37 TC 33 Z9 35 U1 1 U2 10 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA, ONTARIO K1A 0R6, CANADA SN 0706-652X J9 CAN J FISH AQUAT SCI JI Can. J. Fish. Aquat. Sci. PD APR PY 2001 VL 58 IS 4 BP 804 EP 810 DI 10.1139/cjfas-58-4-804 PG 7 WC Fisheries; Marine & Freshwater Biology SC Fisheries; Marine & Freshwater Biology GA 418TG UT WOS:000167907000016 ER PT J AU Charles, CD Rind, D Healy, R Webb, R AF Charles, CD Rind, D Healy, R Webb, R TI Tropical cooling and the isotopic composition of precipitation in general circulation model simulations of the ice age climate SO CLIMATE DYNAMICS LA English DT Article ID LAST GLACIAL MAXIMUM; SEA-SURFACE TEMPERATURE; RECORDS; OCEAN; ATMOSPHERE; SHEETS; CORE; DELTA-O-18; CYCLES; LEVEL AB We test the climate effects of changes in the tropical ocean by imposing three different patterns of tropical SSTs in ice age general circulation model simulations that include water source tracers and water isotope tracers. The continental air temperature and hydrological cycle response in these simulations is substantial and should be directly comparable to the paleoclimatic record. With tropical cooling imposed, there is a strong temperature response in mid- to high-latitudes resulting from changes in sea ice and disturbance of the planetary waves; the results suggest that tropical/subtropical ocean cooling leads to significant dynamical and radiative feedbacks that might amplify ice age cycles, The isotopes in precipitation generally follow the temperature response at higher latitudes, but regional delta O-18/air temperature scaling factors differ greatly among the experiments. In low-latitudes, continental surface temperatures decrease congruently with the adjacent SSTs in the cooling experiments. Assuming CLIMAP SSTs, O-18/O-16 ratios in low-latitude precipitation show no change from modern values. However, the experiments with additional cooling of SSTs produce much lower tropical continental delta O-18 values, and these low values result primarily from an enhanced recycling of continental moisture (as marine evaporation is reduced). The water isotopes are especially sensitive to continental aridity, suggesting that they represent an effective tracer of the extent of tropical cooling and drying. Only one of the tropical cooling simulations produces generalized low-latitude aridity. These results demonstrate that the geographic pattern of cooling is most critical for promoting much drier continents, and they underscore the need for accurate reconstructions of SST gradients in the ice age ocean. C1 Scripps Inst Oceanog, La Jolla, CA 92093 USA. Goddard Inst Space Studies, New York, NY 10025 USA. Woods Hole Oceanog Inst, Woods Hole, MA 02543 USA. NOAA, OAR, CDC, Boulder, CO 80303 USA. RP Charles, CD (reprint author), Scripps Inst Oceanog, La Jolla, CA 92093 USA. RI Healy, Richard/J-9214-2015 OI Healy, Richard/0000-0002-5098-8921 NR 43 TC 13 Z9 15 U1 0 U2 5 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0930-7575 J9 CLIM DYNAM JI Clim. Dyn. PD APR PY 2001 VL 17 IS 7 BP 489 EP 502 DI 10.1007/s003820000126 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 427AZ UT WOS:000168383800001 ER PT J AU Olson, SL Kashiwagi, T Fujita, O Kikuchi, M Ito, K AF Olson, SL Kashiwagi, T Fujita, O Kikuchi, M Ito, K TI Experimental observations of spot radiative ignition and subsequent three-dimensional flame spread over thin cellulose fuels SO COMBUSTION AND FLAME LA English DT Article ID SPEED CONCURRENT FLOW; SOLID-FUEL; MICROGRAVITY ENVIRONMENT; TRANSITION; OXYGEN; MODEL AB Non-piloted radiative ignition and transition to flame spread over thin cellulose fuel samples was studied aboard the USMP-3 STS-75 Space Shuttle mission, and in three test series in the 10 second Japan Microgravity Center (JAMIC). A focused beam from a tungsten/halogen lamp was used to ignite the center of the fuel sample while an external air flow was varied from 0 to 10 cm/s. Non-piloted radiative ignition of the paper was found to occur more easily in microgravity than in normal gravity. ignition of the sample was achieved under all conditions studied (shuttle cabin air, 21%-50% O-2 in JAMIC), with transition to flame spread occurring for all but the lowest oxygen and Bow conditions. Although radiative ignition in a quiescent atmosphere was achieved, the flame quickly extinguished in air. The ignition delay time was proportional to the gas-phase mixing time, which is estimated by using the inverse flow rate. The ignition delay was a much stranger function of Bow at lower oxygen concentrations. After ignition, the flame initially spread only upstream, in a fan-shaped pattern. The fan angle increased with increasing external flow and oxygen concentration from zero angle (tunneling flame spread) at the limiting 0.5 cm/s external air Bow, to 90 degrees (semicircular flame spread) for external Bows at and above 5 cm/s, and higher oxygen concentrations. The fan angle was shown to be directly related to the limiting air flow velocity. A surface energy balance reveals chat the heat feedback rate from the upstream flame to the surface decreases with decreasing oxygen mass transport via either imposed flow velocity or ambient oxygen concentration. Quenching extinction occurs when the heat feedback rate from the flame is no longer sufficient to offset the ongoing surface radiative heat losses. Despite the convective heating from the upstream flame. the downstream flame was inhibited due to the 'oxygen shadow' of the upstream flame for the air Bow conditions studied. Downstream flame spread rates in air, measured alter upstream flame spread was complete and extinguished, were slower than upstream flame spread rates at the same Bow. The quench regime for the transition to flame spread was skewed toward the downstream, because of the augmenting role of diffusion for opposed Bow flame spread, versus the canceling effect of diffusion at very low cocurrent flows. (C) 2001 by The Combustion Institute. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Natl Inst Stand & Technol, Gaithersburg, MD 20899 USA. Hokkaido Univ, Div Mech Sci, Sapporo, Hokkaido 0608628, Japan. RP Olson, SL (reprint author), NASA, Glenn Res Ctr, Mail Stop 5003-115, Cleveland, OH 44135 USA. RI Fujita, Osamu/D-6797-2012 NR 18 TC 23 Z9 28 U1 1 U2 9 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0010-2180 J9 COMBUST FLAME JI Combust. Flame PD APR PY 2001 VL 125 IS 1-2 BP 852 EP 864 DI 10.1016/S0010-2180(00)00249-2 PG 13 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA 427EB UT WOS:000168390900010 ER PT J AU Nayagam, V Williams, FA AF Nayagam, V Williams, FA TI Diffusion-flame dynamics in von Karman boundary layers SO COMBUSTION AND FLAME LA English DT Article ID EDGE-FLAMES AB Experimental and theoretical results are reported for fiat diffusion flames adjacent to a spinning fuel disk in on oxidizing atmosphere. Disk-shaped flames are observed. the radii of which increase or decrease with time, depending on whether an appropriate Damkohler number is large or small. Experimentally, initially large flame disks expand at sufficiently high Damkohler numbers, while at sufficiently small Damkohler numbers, initially small flame disks contract, as predicted by theory. A stability map is derived theoretically in a plane of the Damkohler number and the flame-disk radius normalized by a diffusion length scale, showing regimes of disk growth and shrinkage. (C) 2001 by The Combustion Institute. C1 Univ Calif San Diego, Ctr Energy & Combust Res, Dept Mech & Aerosp Engn, La Jolla, CA 92093 USA. NASA, Lewis Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. RP Williams, FA (reprint author), Univ Calif San Diego, Ctr Energy & Combust Res, Dept Mech & Aerosp Engn, La Jolla, CA 92093 USA. NR 8 TC 7 Z9 8 U1 0 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0010-2180 J9 COMBUST FLAME JI Combust. Flame PD APR PY 2001 VL 125 IS 1-2 BP 974 EP 981 DI 10.1016/S0010-2180(00)00253-4 PG 8 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA 427EB UT WOS:000168390900020 ER PT J AU Tessler, A Annett, MS Gendron, G AF Tessler, A Annett, MS Gendron, G TI A {1,2}-order plate theory accounting for three-dimensional thermoelastic deformations in thick composite and sandwich laminates SO COMPOSITE STRUCTURES LA English DT Article; Proceedings Paper CT ASME Mechanics and Materials Conference CY JUN 27-30, 1999 CL BLACKSBURG, VA ID HIGHER-ORDER THEORY; STRESSES; PANELS; SHELLS; BEAMS AB A (1,2)-order theory for laminated composite and sandwich plates is extended to include thermoelastic effects. The theory incorporates all three-dimensional strains and stresses. Mixed-field assumptions are introduced which include linear in-plane displacements, parabolic transverse displacement and shear strains, and a cubic distribution of the transverse normal stress. Least squares strain compatibility conditions and exact traction boundary conditions are enforced to yield higher polynomial degree distributions for the transverse shear strains and transverse normal stress through the plate thickness. The principle of virtual work is used to derive a 10th-order system of equilibrium equations and associated Poisson boundary conditions. The predictive capability of the theory is demonstrated using a closed-form analytic solution for a simply-supported rectangular plate subjected to a linearly varying temperature field across the thickness. Several thin and moderately thick laminated composite and sandwich plates are analyzed. Numerical comparisons are made with corresponding solutions of the first-order shear deformation theory and three-dimensional elasticity theory. These results, which closely approximate the three-dimensional elasticity solutions, demonstrate that through-the-thickness deformations even in relatively thin and, especially in thick, composite and sandwich laminates can be significant under severe thermal gradients. The (1,2)-order kinematic assumptions insure an overall accurate theory that is in general superior and, in some cases, equivalent to the first-order theory. (C) 2001 Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Analyt & Computat Methods Branch, Hampton, VA 23681 USA. Orbital Sci Corp, Germantown, MD USA. Univ Laval, Ste Foy, PQ G1K 7P4, Canada. RP Tessler, A (reprint author), NASA, Langley Res Ctr, Analyt & Computat Methods Branch, Mail Stop 240, Hampton, VA 23681 USA. EM a.tessler@larc.nasa.gov RI Tessler, Alexander/A-4729-2009 NR 28 TC 12 Z9 12 U1 0 U2 6 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0263-8223 EI 1879-1085 J9 COMPOS STRUCT JI Compos. Struct. PD APR PY 2001 VL 52 IS 1 BP 67 EP 84 DI 10.1016/S0263-8223(00)00192-6 PG 18 WC Materials Science, Composites SC Materials Science GA 422TK UT WOS:000168135200007 ER PT J AU Whittle, J AF Whittle, J TI An achievable dream encounters barriers and bottlenecks SO COMPUTER LA English DT Letter C1 NASA, Ames Res Ctr, QSS, Moffett Field, CA 94035 USA. RP Whittle, J (reprint author), NASA, Ames Res Ctr, QSS, Moffett Field, CA 94035 USA. NR 0 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 90720-1314 USA SN 0018-9162 J9 COMPUTER JI Computer PD APR PY 2001 VL 34 IS 4 BP 4 EP 4 PG 1 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering SC Computer Science GA 417QU UT WOS:000167846300001 ER PT J AU Naimie, CE Blain, CA Lynch, DR AF Naimie, CE Blain, CA Lynch, DR TI Seasonal mean circulation in the Yellow Sea - a model-generated climatology SO CONTINENTAL SHELF RESEARCH LA English DT Article DE seasonal cycle; climatology; Yellow Sea ID EAST-CHINA-SEA; GEORGES-BANK; FRONTS; FLOWS; OCEAN; MAINE AB The three-dimensional climatological circulation is computed for the Yellow and Bohai Seas in a series of six bimonthly realizations, The model (QUODDY, Lynch et al., Continental Shelf Res, 16(7) (1996) 875) is nonlinear, tide-resolving, and baroclinic with level 2.5 turbulence closure. Data inputs include seasonal hydrography, seasonal mean wind and river input, and oceanic tides. Results for winter and summer exhibit two distinct circulation modes. In winter, strong northerly wind drives southward flow at the surface and along both Korean and Chinese coasts. This is compensated by deep return flow - the Yellow Sea Warm Current - in the central trough of the Yellow Sea, penetrating to the Bohai. The Changjiang discharge exits to the southwest in winter, trapped alone the Chinese coast. In summer, a water mass produced by winter cooling - the Yellow Sea Cold Water - is isolated in the deep central trough, setting up cyclonic circulation over the eastern Yellow Sea. Summer winds from the south drive northeastward flow along the Chinese coast. The net result is a qualitative reversal of the winter pattern. The Changjiang discharge is driven offshore toward the Korean Strait by the summer wind. The winter and summer circulations are partitioned dynamically among tidal rectification, baroclinic pressure gradients, wind response, and river input from the Changjiang. Wind dominates the winter pattern. In summer, baroclinic pressure gradients dominate the eastern Yellow Sea; with wind, tidal rectification, and input from the Changjiang dominant to the west of the cyclonic gyre, The seasonal cycle indicates that January and March exhibit the same basic winter pattern. May is quiescent, followed by July which defines the summer mode. September shows the same general summer pattern, with features shifted westward. November is a transition period followed by winter conditions, (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Dartmouth Coll, Hanover, NH 03755 USA. USN, Res Lab, Ocean Dynam & Predict Branch, Stennis Space Ctr, Stennis Space Ctr, MS 39529 USA. RP Lynch, DR (reprint author), Dartmouth Coll, Hanover, NH 03755 USA. NR 61 TC 99 Z9 118 U1 0 U2 16 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0278-4343 J9 CONT SHELF RES JI Cont. Shelf Res. PD APR-MAY PY 2001 VL 21 IS 6-7 BP 667 EP 695 PG 29 WC Oceanography SC Oceanography GA 420BT UT WOS:000167984600006 ER PT J AU Rosenzweig, C Solecki, WD AF Rosenzweig, C Solecki, WD TI Climate change and a global city - Learning from New York SO ENVIRONMENT LA English DT Article C1 NASA, Goddard Inst Space Studies, Climate Impacts Grp, Greenbelt, MD 20771 USA. Columbia Univ, Earth Inst, New York, NY 10027 USA. Columbia Univ Barnard Coll, New York, NY 10027 USA. Montclair State Univ, Montclair, NJ USA. RP Rosenzweig, C (reprint author), NASA, Goddard Inst Space Studies, Climate Impacts Grp, Greenbelt, MD 20771 USA. NR 18 TC 12 Z9 12 U1 1 U2 7 PU HELDREF PUBLICATIONS PI WASHINGTON PA 1319 EIGHTEENTH ST NW, WASHINGTON, DC 20036-1802 USA SN 0013-9157 J9 ENVIRONMENT JI Environment PD APR PY 2001 VL 43 IS 3 BP 8 EP 18 PG 11 WC Environmental Sciences; Environmental Studies SC Environmental Sciences & Ecology GA 450XE UT WOS:000169769500002 ER PT J AU Castellanos, DL Rozas, LP AF Castellanos, DL Rozas, LP TI Nekton use of submerged aquatic vegetation, marsh, and shallow unvegetated bottom in the Atchafalaya River Delta, a Louisiana tidal freshwater ecosystem SO ESTUARIES LA English DT Article ID LOWER CHESAPEAKE BAY; CALLINECTES-SAPIDUS RATHBUN; ZOSTERA-MARINA MEADOWS; SALT-MARSH; SEAGRASS MEADOWS; FISH COMMUNITIES; SAMPLING CHARACTERISTICS; STRUCTURAL COMPONENTS; HABITAT COMPLEXITY; ABUNDANCE AB We sampled nekton (fishes and decapod crustaceans) in submerged aquatic vegetation (SAV) (Potamogeton nodosus, Najas guadalupensis), in emergent marsh vegetation (Sagittaria spp. and Scirpus americanus), and over unvegetated bottom associated with three islands in the Atchafalaya River Delta, Louisiana. The purpose of our study was to quantify nekton densities in these major aquatic habitat types and to document the relative importance of these areas to numerically dominant aquatic organisms. We collected a total of 33 species of fishes and 7 species of crustaceans in 298 1-m(2) throw trap samples taken over three seasons: summer (July and August 1994), fall (September and October 1994), and spring (May and June 1995). Fishes numerically accounted for > 65% of the total organisms collected. Vegetated areas generally supported much higher nekton densities than unvegetated sites, although bay anchovies Anchoa mitchilli were more abundant over unvegetated bottom than in most vegetated habitat types. Among vegetation types, most species showed no apparent preference between SAV and marsh. However, inland silversides Menidia beryllina and freshwater gobies Gobionellus shufeldti were most abundant in Scirpus marsh in summer, and blue crabs Callinectes sapidus were most abundant in SAV (Potamogeton) in spring. Several species (sheepshead minnow Cyprinodon variegatus, rainwater killifish Lucania parva, and blue crab) apparently selected the vegetated backmarsh of islands (opposite of riverside) over streamside Scirpus marsh. Freshwater gobies, in contrast, were most abundant in streamside Scirpus marsh. Densities of juvenile blue crabs were high (up to 17 m(-2)) in vegetated delta habitat types and comparable to values reported from more saline regions of Gulf Coast estuaries. Shallow vegetated habitat types of the Atchafalaya River Delta and other tidal freshwater systems of the Gulf Coast may be: important nursery areas for blue crabs and other estuarine species. C1 Univ Louisiana Lafayette, Dept Biol, Lafayette, LA 70504 USA. NOAA, Natl Marine Fisheries Serv, SE Fisheries Sci Ctr, Fishery Ecol Branch,Galveston Lab, Galveston, TX 77551 USA. RP Castellanos, DL (reprint author), Louisiana Dept Nat Resources, Coastal Restorat Div, POB 639, Abbeville, LA 70511 USA. NR 65 TC 40 Z9 41 U1 1 U2 17 PU ESTUARINE RES FEDERATION PI LAWRENCE PA PO BOX 368, LAWRENCE, KS 66044 USA SN 0160-8347 J9 ESTUARIES JI Estuaries PD APR PY 2001 VL 24 IS 2 BP 184 EP 197 DI 10.2307/1352943 PG 14 WC Environmental Sciences; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 438KR UT WOS:000169052900004 ER PT J AU Kaufman, GD Wood, SJ Gianna, CC Black, FO Paloski, WH AF Kaufman, GD Wood, SJ Gianna, CC Black, FO Paloski, WH TI Spatial orientation and balance control changes induced by altered gravitoinertial force vectors SO EXPERIMENTAL BRAIN RESEARCH LA English DT Article DE adaptation; vestibular deficient; hypergravity; sensory conflict; motion sickness; centrifugation; graviceptors; proprioceptors; artificial gravity; human ID 1 HOUR CENTRIFUGATION; MOTION SICKNESS; VESTIBULOOCULAR REFLEX; CENTRIPETAL ACCELERATION; POSTURAL CONTROL; OCULAR TORSION; FOS EXPRESSION; SPACE-FLIGHT; PERCEPTION; ADAPTATION AB To better understand the mechanisms of human adaptation to rotating environments, we exposed 19 healthy subjects and 8 vestibular-deficient subjects ("abnormal"; four bilateral and four unilateral lesions) to an interaural centripetal acceleration of Ig (resultant 45 degrees roll-tilt of 1.4g) on a 0.8-m-radius centrifuge for periods of 90 min. The subjects sat upright (body z-axis parallel to centrifuge rotation axis) in the dark with head stationary, except during 4 min of every 10 min, when they performed head saccades toward visual targets switched on at 3- to 5-s intervals at random locations (within +/- 30 degrees) in the earth-horizontal plane. Eight of the normal subjects also performed the head saccade protocol in a stationary chair adjusted to a static roll-tilt angle of 45 degrees for 90 min (reproducing the change in orientation but not the magnitude of the gravitoinertial force on the centrifuge). Eye movements, including voluntary saccades directed along perceived earth- and head-referenced planes, were recorded before, during, and immediately after centrifugation. Postural center of pressure (COP) and multisegment body kinematics were also gathered before and within 10 min after centrifugation. Normal subjects overestimated roll tilt during centrifugation and revealed errors in perception of head-vertical provided by directed saccades. Errors in this perceptual response tended to increase with time and became significant after approximately 30 min. Motion-sickness symptoms caused approximately 25% of normal subjects to limit their head movements during centrifugation and led three normal subjects to stop the test early. Immediately after centrifugation, subjects reported feeling tilted 10 degrees in the opposite direction, which was in agreement with the direction of their earth-referenced directed saccades. Postural COP, segmental body motion amplitude, and hip-sway frequency increased significantly after centrifugation. These postural effects were short-lived, however, with a recovery time of several postural test trials (minutes). There were also asymmetries in the direction of postcentrifugation COP and head tilt which depended on the subject's orientation during the centrifugation adaptation period (left ear or right ear out). The amount of total head movements during centrifu gation correlated poorly or inversely with postcentrifugation postural stability, and the most unstable subject made no head movements. There was no decrease in postural stability after static tilt, although these subjects also reported a perceived tilt briefly after return to upright, and they also had COP asymmetries. Abnormal subjects underestimated roll-tilt during centrifugation, and their directed saccades revealed permanent spatial distortions. Bilateral abnormal subjects started out with poor postural control, but showed no postural decrements after centrifugation, while unilateral abnormal subjects had varying degrees of postural decrement, both in their everyday function and as a result of experiencing the centrifugation. In addition, three unilateral, abnormal subjects, who rode twice in opposite orientations, revealed a consistent orthogonal pattern of COP offsets after centrifugation. These results suggest that both orientation and magnitude of the gravitoinertial vector are used by the central nervous system for calibration of multiple orientation systems. A change in the background gravitoinertial force (otolith input) can rapidly initiate postural and perceptual adaptation in several sensorimotor systems independent of a structured visual surround. C1 NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. Baylor Coll Med, Bobby R Alford Dept Ontorhinolaryngol, Houston, TX USA. Legacy Hlth Syst, Portland, OR USA. RP Paloski, WH (reprint author), NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Mail Code SD-3, Houston, TX 77058 USA. EM wpaloski@ems.jsc.nasa.gov FU NIDCD NIH HHS [DC 00205] NR 76 TC 14 Z9 14 U1 0 U2 6 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0014-4819 EI 1432-1106 J9 EXP BRAIN RES JI Exp. Brain Res. PD APR PY 2001 VL 137 IS 3-4 BP 397 EP 410 PG 14 WC Neurosciences SC Neurosciences & Neurology GA 427FH UT WOS:000168393800012 PM 11355385 ER PT J AU Wernet, MP AF Wernet, MP TI New insights into particle image velocimetry data using fuzzy-logic-based correlation/particle tracking processing SO EXPERIMENTS IN FLUIDS LA English DT Article AB Digital particle image velocimetry (DPIV) data processing has been developed to the point where DPIV image data are processed via auto- or cross-correlation techniques in near real time and the results are displayed on screen as they are processed. Correlation techniques are highly desirable, since they provide velocity measurements on a regular grid, which are readily comparable to CFD predictions of the flow held. In high-speed flows, particle lag effects are always of concern; however, the correlation operation does not provide any means for minimization or elimination of systematic errors in the recorded particle image data. In this paper, we present a combined correlation processing/particle tracking technique providing "super-resolution" velocity measurements. Fuzzy-logic principles are employed to maximize the information recovery in the correlation operation and to determine the correct particle pairings in the tracking operation. The combined correlation/particle tracking technique is applied to DPIV data obtained in the diffuser region of a highspeed centrifugal compressor producing velocity vector maps with an average density of 6 vectors/mm(2). Inspection of the particle tracking results revealed large particles that were not following the flow. Using preknowledge of the flow field, the biased velocity estimates arising from large particles in the flow were removed, thereby improving the accuracy of the measurements. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Wernet, MP (reprint author), NASA, Glenn Res Ctr, MS-77-1,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 18 TC 8 Z9 10 U1 0 U2 2 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0723-4864 J9 EXP FLUIDS JI Exp. Fluids PD APR PY 2001 VL 30 IS 4 BP 434 EP 447 DI 10.1007/s003480000223 PG 14 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 427FN UT WOS:000168394300010 ER PT J AU Jacobson, LD Brodziak, J Rogers, J AF Jacobson, LD Brodziak, J Rogers, J TI Depth distributions and time-varying bottom trawl selectivities for Dover sole (Microstomus pacificus), sablefish (Anoplopoma fimbria), and thornyheads (Sebastolobus alascanus and S-altivelis) in a commercial fishery SO FISHERY BULLETIN LA English DT Article ID SAMPLING TRAWL; CATCH; GROUNDFISH AB We estimated size-specific depth distributions and commercial bottom trawl fishery selectivities for Dover sole (Microstomus pacificus), shortspine thornyhead (Sebastolobus alascanus), longspine thornyhead (S. altivelis), and sablefish (Anoplopoma fimbria) along the U.S, west coast. Depth distributions are size-specific because fish migrate ontogenetically to deep water: With ontogenetic migration, fishery selectivities of commercial bottom trawls depend on depth of fishing because large fish ale most common in deep water. Depth distributions were similar for northern and southern areas and for males and females. Results show ontogenetic migration in sablefish, suggest a possible weak ontogenetic migration in longspine thornyhead, and confirm ontogenetic migration patterns already reported for Dover sole and shortspine thornyhead. Fishery selectivities varied among species, between areas, and changed dramatically over time for most species as fishing effort moved into deep water: Our approach used biological data collected during research bottom trawl surveys but was generally not affected by size selectivity of bottom trawl survey gear. Uncertainty in our commercial bottom trawl selectivity estimates was mostly from length-specific capture probabilities (or vulnerabilities) for fish in the path of commercial bottom trawls. Our estimates complement selectivity estimates fi om stock assessment models. The approach may be useful whenever the geographic distribution of fish depends on size ol age, fishing effort is not randomly distributed geographically, and sun ey estimates of fish density, bathymetric data, and commercial fishing effort information ar e available. C1 NOAA, Natl Marine Fisheries Serv, SW Fisheries Sci Ctr, La Jolla, CA 92038 USA. NOAA, Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Newport, OR 97365 USA. RP Jacobson, LD (reprint author), NOAA, Natl Marine Fisheries Serv, NE Fisheries Sci Ctr, 166 Water St, Woods Hole, MA 02543 USA. NR 37 TC 16 Z9 16 U1 0 U2 0 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 USA SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD APR PY 2001 VL 99 IS 2 BP 309 EP 327 PG 19 WC Fisheries SC Fisheries GA 429ET UT WOS:000168503600009 ER PT J AU Rashed, H Cutts, T Cowings, P Toscano, W Abell, TL AF Rashed, H Cutts, T Cowings, P Toscano, W Abell, TL TI Biofeedback training exercise in heating patients with chronic gastric motility disorders: Possible predictors for the outcome SO GASTROENTEROLOGY LA English DT Meeting Abstract C1 Univ Tennessee, Ctr Hlth Sci, Memphis, TN 38163 USA. NASA, Moffett Field, CA USA. Univ Arkansas Med Sci, Little Rock, AR 72205 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU W B SAUNDERS CO PI PHILADELPHIA PA INDEPENDENCE SQUARE WEST CURTIS CENTER, STE 300, PHILADELPHIA, PA 19106-3399 USA SN 0016-5085 J9 GASTROENTEROLOGY JI Gastroenterology PD APR PY 2001 VL 120 IS 5 SU 1 MA 3255 BP A642 EP A642 PG 1 WC Gastroenterology & Hepatology SC Gastroenterology & Hepatology GA 429KA UT WOS:000168514703185 ER PT J AU Komatsu, G Gulick, VC Baker, VR AF Komatsu, G Gulick, VC Baker, VR TI Valley networks on Venus SO GEOMORPHOLOGY LA English DT Article DE Venus; valley networks; lavas ID MAGELLAN DATA; CHANNELS AB Valley networks on Venus are classified as rectangular, labyrinthic and pitted, or irregular. The venusian valley networks are structurally controlled, as indicated by the morphological patterns of valley branches, consistency between valley and fracture orientations, and associations with the deformed terrains. The morphologies resemble those of terrestrial and martian sapping valleys. Valley networks on Venus probably formed initially from fracture systems and became enlarged by low viscosity lava sapping processes. Subsurface flow of lava may locally have been assisted by surface flows. The lavas probably moved through permeable media and fractures. Venusian valley networks have a higher degree of network integration than do lunar sinuous rilles, but they are less integrated than martian and terrestrial sapping valleys. The viscosity of valley-forming lavas must have been very low, but was not low enough to exploit the permeable media so extensively as to attain a high degree of network integration. The compositions of these lavas may have been mafic to ultramafic or made alkaline. Alternatively, the lavas could have had more exotic compositions, such as carbonatite and sulfur. Valley networks are often associated with corona and corona-like features, which are hypothesized to be the surface expressions of mantle plumes. A plume association could mean that the lavas came from the mantle. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Univ Annunzio, Int Res Sch Planetary Sci, I-65127 Pescara, Italy. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Univ Arizona, Dept Hydrol & Water Resources, Tucson, AZ 85721 USA. RP Komatsu, G (reprint author), Univ Annunzio, Int Res Sch Planetary Sci, Via Pindaro 42, I-65127 Pescara, Italy. RI Komatsu, Goro/I-7822-2012 OI Komatsu, Goro/0000-0003-4155-108X NR 15 TC 13 Z9 13 U1 2 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-555X J9 GEOMORPHOLOGY JI Geomorphology PD APR PY 2001 VL 37 IS 3-4 SI SI BP 225 EP 240 DI 10.1016/S0169-555X(00)00084-2 PG 16 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA 413YF UT WOS:000167638600004 ER PT J AU Gulick, VC AF Gulick, VC TI Origin of the valley networks on Mars: a hydrological perspective SO GEOMORPHOLOGY LA English DT Article DE Mars; valley networks; hydrothermal systems ID SMALL MARTIAN VALLEYS; FLUVIAL VALLEYS; CLIMATE; REGION; EVOLUTION; CHANNELS; PATERA; WARM; WET AB The geomorphology of the martian valley networks is examined from a hydrological perspective for the compatibility with an origin by rainfall, globally higher heat flow, and localized hydrothermal systems. Comparison of morphology and spatial distribution of valleys on geologic surfaces with terrestrial fluvial valleys suggests that most martian valleys are probably not indicative of a rainfall origin, nor are they indicative of formation by an early global uniformly higher heat flow. In general, valleys are not uniformly distributed within geologic surface materials as are terrestrial fluvial valleys. Valleys tend to form either as isolated systems or in clusters on a geologic surface unit leaving large expanses of the unit virtually untouched by erosion. With the exception of fluvial valleys on some volcanoes, most martian valleys exhibit a sapping morphology and do not appear to have formed along with those that exhibit runoff morphology. In contrast, terrestrial sapping valleys form from and along with runoff valleys. The isolated or clustered distribution of valleys suggests localized water sources were important in drainage development, Persistent groundwater outflow driven by localized, but vigorous hydrothermal circulation associated with magmatism, volcanism, impacts, or tectonism is, however, consistent with valley morphology and distribution, Snowfall From sublimating ice-covered lakes or seas may have provided an atmospheric source of water for the formation of some valleys in regions where the surface is easily eroded and where localized geothermal/hydrothermal activity is sufficient to melt accumulated snowpacks. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. New Mexico State Univ, Dept Astron, Las Cruces, NM 88003 USA. RP Gulick, VC (reprint author), NASA, Ames Res Ctr, Div Space Sci, MS 245-3, Moffett Field, CA 94035 USA. EM vgulick@mail.arc.nasa.gov NR 57 TC 90 Z9 91 U1 0 U2 15 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-555X J9 GEOMORPHOLOGY JI Geomorphology PD APR PY 2001 VL 37 IS 3-4 SI SI BP 241 EP 268 DI 10.1016/S0169-555X(00)00086-6 PG 28 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA 413YF UT WOS:000167638600005 ER PT J AU Cabrol, NA Grin, EA AF Cabrol, NA Grin, EA TI Composition of the drainage network on early Mars SO GEOMORPHOLOGY LA English DT Article DE Mars; drainage network; first-order stream ID MARTIAN VALLEYS; WATER; MORPHOLOGY; ORIGIN AB Among the 2208 martian fluvial features plotted in a previous study [Z. Geomorphol. 37-1 (1993) 57], the hydrological characteristics of 71 pristine fluvial valley networks, located between 18.0 degreesN and 55.0 degreesS, were surveyed using Viking Orbiter photomosaic bases at 1:2 million scale. The surveyed networks display: (1) systems organized mainly as first-order streams, 85% of which have lengths not exceeding 1000 km with a large amount of the statistical sample having lengths between 200 and 500 km (generally shorter than the degraded valleys studied by Baker and Partridge [J. Geophys. Res. 91 (1986) 3561]), (2) drainage basins with average areas of about 5000 km(2), (3) a random distribution, and (4) headwater tributary drainage densities (k(d)) ranging systematically between 0.03 and 0.2 km(-1), which are comparable to terrestrial drainage densities in arid climates. The compositions of the surveyed pristine valley networks are comparable to the degraded fluvial systems that dissect older martian surface materials. Thus, it appears that no dramatic changes occurred in martian hydrology since the earlier period of formation of the "degraded valleys", such as described by Baker and Partridge [J. Geophys. Res. 91 (1986) 3561]. Subsurface aquifer drainage may have been a large contributor to drainage basin formation since early in Mars history. (C) 2001 Published by Elsevier Science B.V. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Cabrol, NA (reprint author), NASA, Ames Res Ctr, Div Space Sci, MS 245-3, Moffett Field, CA 94035 USA. NR 32 TC 20 Z9 20 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-555X J9 GEOMORPHOLOGY JI Geomorphology PD APR PY 2001 VL 37 IS 3-4 SI SI BP 269 EP 287 DI 10.1016/S0169-555X(00)00087-8 PG 19 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA 413YF UT WOS:000167638600006 ER PT J AU Parker, TJ Currey, DR AF Parker, TJ Currey, DR TI Extraterrestrial coastal geomorphology SO GEOMORPHOLOGY LA English DT Article DE Earth; Mars; solar system ID MARTIAN NORTHERN PLAINS; CRUSTAL DICHOTOMY; TIDAL DISSIPATION; LAYERED DEPOSITS; VALLES-MARINERIS; TITANS SURFACE; IMPACT CRATERS; MARS; VENUS; WATER AB Earth is the only planet in the solar system where large amounts of liquid water have been stable at the surface throughout geologic time. This unique trait has resulted in the production of characteristic landforms and massive accumulations of aqueous sediments, as well as enabled the evolution of advanced and diverse forms of life. But while Earth is the only planet with large bodies of water on its surface today, Venus and Mars may have once had lakes or oceans as well. More exotic fluids may be stable in the outer solar system. Prior to the: Voyager flybys of the outer planets during the 1970s and 1980s, the moon of Neptune, Triton, was thought to be much larger than the Voyager cameras revealed it to be, and predictions that liquid nitrogen lakes or oceans might be found were made. The moon of Saturn, Titan, however, was found to have a massive atmosphere, so the possibility remains that it may have, or may once have had, lakes or oceans of liquid hydrocarbons. The recent, high-resolution synthetic aperture radar imaging of Venus has failed to reveal any evidence of any putative clement period, but the results fur Mars are much more intriguing. Herein, we briefly review work on this subject by a number of investigators, and discuss problems of identifying and recognizing martian landforms as lacustrine or marine. In addition, we present additional examples of possible martian coastal landforms. The former presence of lakes or oceans on Mars has profound implications with regard to the climate history of that planet. (C) 2001 Published by Elsevier Science B.V. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Utah, Dept Geog, Salt Lake City, UT 84112 USA. RP Parker, TJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 93 TC 17 Z9 17 U1 2 U2 10 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-555X J9 GEOMORPHOLOGY JI Geomorphology PD APR PY 2001 VL 37 IS 3-4 SI SI BP 303 EP 328 DI 10.1016/S0169-555X(00)00089-1 PG 26 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA 413YF UT WOS:000167638600008 ER PT J AU Nakajima, T Higurashi, A Kawamoto, K Penner, JE AF Nakajima, T Higurashi, A Kawamoto, K Penner, JE TI A possible correlation between satellite-derived cloud and aerosol microphysical parameters SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID OPTICAL-THICKNESS; SULFATE AEROSOLS; CLIMATE MODEL; NOAA AVHRR; ALGORITHM; POLLUTION; DROPLETS; RADIUS AB The column aerosol particle number and low cloud microphysical parameters derived from AVHRR remote sensing are compared over ocean for four months in 1990. There is a positive correlation between cloud optical thickness and aerosol number concentration, whereas the effective particle radius has a negative correlation with aerosol number. The cloud liquid water path (LWP), on the other hand, tends to be constant with no large dependence on aerosol number. This result contrasts with results from recent model simulations which imply that there is a strong positive feedback between LWP and aerosol number concentration. Estimates for indirect forcing over oceans derived from the satellite data/model comparison range from -0.7 to -1.7 Wm(-2). C1 Univ Tokyo, Ctr Climate Syst Res, Meguro Ku, Tokyo 1538904, Japan. Natl Inst Environm Studies, Tsukuba, Ibaraki 3050053, Japan. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. RP Nakajima, T (reprint author), Univ Tokyo, Ctr Climate Syst Res, Meguro Ku, 4-6-1 Komaba, Tokyo 1538904, Japan. RI Nakajima, Teruyuki/H-2370-2013; Penner, Joyce/J-1719-2012 OI Nakajima, Teruyuki/0000-0002-9042-504X; NR 29 TC 194 Z9 200 U1 0 U2 17 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 APR 1 PY 2001 VL 28 IS 7 BP 1171 EP 1174 DI 10.1029/2000GL012186 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 415GZ UT WOS:000167714000001 ER PT J AU Waugh, DW Considine, DB Fleming, EL AF Waugh, DW Considine, DB Fleming, EL TI Is upper stratospheric chlorine decreasing as expected? SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CONFIRMATION; TRANSPORT AB The monthly-mean total chlorine abundance (CL) at 55 km inferred from HALOE HCl observations increases from 1992 to 1997 and then subsequently decreases. The pre-1997 increase is consistent with surface measurements of Cl-T time-lagged by around 6 years. However, a decrease after 1997 is inconsistent with such a time lag, which would predict a peak in late 1999. Accounting for stratospheric mixing processes produces an expected stratosphere CIT which is in agreement with the HALOE Cl-T time series considering the uncertainty in the HALOE data. However, the peak in Cl-T is still predicted to occur in later 1999 rather than 1997. We find that reasonable low frequency changes in transport, chlorine partitioning, anomalous buildup of organic chlorine at 55 km, and tropospheric rainout of inorganic chlorine do not reconcile the expected and HALOE Cl-T time series. At present, we are unable to explain hear upper stratospheric Cl-T could decrease as early as 1997. C1 Johns Hopkins Univ, Dept Earth & Planetary Sci, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, College Pk, MD 20742 USA. Sci Syst & Applicat Inc, Lanham, MD USA. RP Waugh, DW (reprint author), Johns Hopkins Univ, Dept Earth & Planetary Sci, Baltimore, MD 21218 USA. RI Waugh, Darryn/K-3688-2016 OI Waugh, Darryn/0000-0001-7692-2798 NR 7 TC 29 Z9 29 U1 0 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 APR 1 PY 2001 VL 28 IS 7 BP 1187 EP 1190 DI 10.1029/2000GL011745 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 415GZ UT WOS:000167714000005 ER PT J AU Rosenlof, KH Oltmans, SJ Kley, D Russell, JM Chiou, EW Chu, WP Johnson, DG Kelly, KK Michelsen, HA Nedoluha, GE Remsberg, EE Toon, GC McCormick, MP AF Rosenlof, KH Oltmans, SJ Kley, D Russell, JM Chiou, EW Chu, WP Johnson, DG Kelly, KK Michelsen, HA Nedoluha, GE Remsberg, EE Toon, GC McCormick, MP TI Stratospheric water vapor increases over the past half-century SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TROPOPAUSE TEMPERATURES; AIRCRAFT MEASUREMENTS; ATMOSPHERIC METHANE; SOUTHERN ENGLAND; HUMIDITY; TRENDS; OZONE; VARIABILITY; WASHINGTON; HYGROMETER AB Ten data sets covering the period 1954-2000 are analyzed to show a 1%/yr increase in stratospheric water vapor. The trend has persisted for at least 45 years, hence is unlikely the result of a single event, but rather indicative of long-term climate change. A long-term change in the transport of water vapor into the stratosphere is the most probable cause. C1 NOAA, Aeron Lab, Boulder, CO 80305 USA. NOAA, CMDL, Boulder, CO 80305 USA. Forschungszentrum Julich, Julich, Germany. Hampton Univ, Dept Phys, Hampton, VA 23668 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Sandia Natl Labs, Livermore, CA 94551 USA. USN, Res Lab, Washington, DC 20375 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Rosenlof, KH (reprint author), NOAA, Aeron Lab, 325 Broadway, Boulder, CO 80305 USA. EM krosenlof@al.noaa.gov RI Rosenlof, Karen/B-5652-2008; Johnson, David/F-2376-2015 OI Rosenlof, Karen/0000-0002-0903-8270; Johnson, David/0000-0003-4399-5653 NR 29 TC 198 Z9 205 U1 2 U2 19 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 APR 1 PY 2001 VL 28 IS 7 BP 1195 EP 1198 DI 10.1029/2000GL012502 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 415GZ UT WOS:000167714000007 ER PT J AU Ray, RD Cartwright, DE AF Ray, RD Cartwright, DE TI Estimates of internal tide energy fluxes from Topex/Poseidon altimetry: Central North Pacific SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SURFACE MANIFESTATION; DEEP-OCEAN AB Energy fluxes for first-mode M-2 internal tides are deduced throughout the central North Pacific Ocean from Topex/Poseidon satellite altimeter data. Temporally coherent internal tide signals in the altimetry, combined with climatological hydrographic data, determine the tidal displacements, pressures, and currents at depth, which yield power transmission rates. For a variety of reasons the deduced rates should be considered lower bounds. Internal tides are found to emanate from several large bathymetric structures, especially the Hawaiian Ridge, where the integrated flux amounts to about 6 gigawatts. Internal tides are generated at the Aleutian Trench near 172 degreesW and propagate southwards nearly 2000 km. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ray, RD (reprint author), NASA, Goddard Space Flight Ctr, Code 926, Greenbelt, MD 20771 USA. RI Ray, Richard/D-1034-2012 NR 13 TC 67 Z9 69 U1 2 U2 11 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 APR 1 PY 2001 VL 28 IS 7 BP 1259 EP 1262 DI 10.1029/2000GL012447 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 415GZ UT WOS:000167714000023 ER PT J AU Buti, B Tsurutani, BT Neugebauer, M Goldstein, BE AF Buti, B Tsurutani, BT Neugebauer, M Goldstein, BE TI Generation mechanism for magnetic holes in the solar wind SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NONLINEAR ALFVEN WAVES; ULYSSES OBSERVATIONS; FIELD; EVOLUTION; PACKETS AB A new mechanism for generation of magnetic holes in the solar wind is presented. In the high speed solar wind, large-amplitude right-hand polarized Alfvenic wave packets propagating at large angles to the ambient magnetic field are shown to generate magnetic holes (MHs). Characteristics of these holes crucially depend on plasma beta (beta being the ratio of kinetic pressure to magnetic pressure) and the ratio of electron temperature T-e to proton temperature T-i. Proton temperature anisotropy is found to be favorable but not essential for the development of MHs. From our simulations we observe MHs with microstructures bounded by sharp gradients (magnetic decreases) in some cases. The holes generated by this process have thicknesses of hundreds of ion Larmor radii, typical of many of the solar wind hole observations, the depths of the holes are also comparable. The theory can explain the presence of MHs seen in the solar wind for those cases when anisotropies are not favorable for the development of the mirror mode instability. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Buti, B (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 21 TC 45 Z9 47 U1 0 U2 3 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 APR 1 PY 2001 VL 28 IS 7 BP 1355 EP 1358 DI 10.1029/2000GL012592 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 415GZ UT WOS:000167714000047 ER PT J AU Noren, C Kanik, I Ajello, JM McCartney, P Makarov, OP McClintock, WE Drake, VA AF Noren, C Kanik, I Ajello, JM McCartney, P Makarov, OP McClintock, WE Drake, VA TI Emission cross section of OI (135.6 nm) at 100 eV resulting from electron-impact dissociative excitation of O-2. SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID COMPLETE UV SPECTRUM; ULTRAVIOLET-SPECTRUM; OXYGEN; ATMOSPHERE; GANYMEDE; MISSION; EUROPA; SO2 AB In this Letter, we report for the first time, the ratio of the O I (135.6 nm)/O I (130.4 nm) absolute emission cross sections from electron-impact dissociative excitation of O-2 at 100 eV using facilities located at the University of Colorado, Laboratory for Atmospheric and Space Physics (LASP). The O I (135.6 nm) emission glow produced in the laboratory from the long-lived transition O I g(3)P <-- S-5(degrees) was measured in a large collision chamber (1m diameter) with a long focal length (50 cm) electrostatic electron gun. The ratio of the absolute emission cross sections of the O I (135.6 nm) and O I (130.4 nm) features resulting from electron-impact dissociative excitation of O-2 at 100 eV was found to be 2.3 +/-0.6. From this ratio, the absolute emission cross section for the O I (135.6 nm) feature at 100 eV electron-impact energy was determined to be (6.4 +/-2.2)x10(-18) cm(2). The O I (135.6 nm) cross section reported here can be used to better understand the recent Hubble Space Telescope observations of the O I (130.4 nn) and O I (135.6 nm) emission intensities from Ganymede [Feldman et al., 2000] and Europa [Hall et al., 1995]. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80303 USA. RP Noren, C (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 17 TC 9 Z9 9 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 APR 1 PY 2001 VL 28 IS 7 BP 1379 EP 1382 DI 10.1029/2000GL012577 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 415GZ UT WOS:000167714000053 ER PT J AU Mertens, CJ Mlynczak, MG Lopez-Puertas, M Wintersteiner, PP Picard, RH Winick, JR Gordley, LL Russell, JM AF Mertens, CJ Mlynczak, MG Lopez-Puertas, M Wintersteiner, PP Picard, RH Winick, JR Gordley, LL Russell, JM TI Retrieval of mesospheric and lower thermospheric kinetic temperature from measurements of CO2 15 mu m Earth limb emission under non-LTE conditions SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NONLOCAL THERMODYNAMIC-EQUILIBRIUM; ATMOSPHERE; EXCITATION; RADIANCE; MODEL AB We present a new algorithm for the retrieval of kinetic temperature in the terrestrial mesosphere and lower thermosphere from measurements of CO2 15 mum earth limb emission. Non-local-thermodynamic-equilibrium (non-LTE) processes are rigorously included in the new algorithm, necessitated by the prospect of satellite-based limb radiance measurements to be made from the TIMED/SABER platform in the near future between 15 km and 120 km tangent altitude. The algorithm requires 20 seconds to retrieve temperature to better than 3 K accuracy on a desktop computer, easily enabling its use in operational processing of satellite data. We conclude this letter with a study of the sensitivity of the retrieved temperatures to parameters used in the non-LTE models, including sensitivity to the rate constant for physical quenching of CO2 bending mode vibrations by atomic oxygen. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. ARCON Corp, Waltham, MA USA. CSIC, Inst Astrofis Andalucia, Granada, Spain. USAF, Res Labs, Space Vehicles Directorate, Hanscom AFB, MA USA. Hampton Univ, Hampton, VA 23668 USA. RP Mertens, CJ (reprint author), NASA, Langley Res Ctr, 21 Langley Blvd,Mail Stop 401B, Hampton, VA 23681 USA. RI Mlynczak, Martin/K-3396-2012; Lopez Puertas, Manuel/M-8219-2013 OI Lopez Puertas, Manuel/0000-0003-2941-7734 NR 16 TC 164 Z9 167 U1 1 U2 6 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 APR 1 PY 2001 VL 28 IS 7 BP 1391 EP 1394 DI 10.1029/2000GL012189 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 415GZ UT WOS:000167714000056 ER PT J AU Yorio, NC Goins, GD Kagie, HR Wheeler, RM Sager, JC AF Yorio, NC Goins, GD Kagie, HR Wheeler, RM Sager, JC TI Improving spinach, radish, and lettuce growth under red light-emitting diodes (LEDs) with blue light supplementation SO HORTSCIENCE LA English DT Article DE spectral quality; Spinacea oleracea; Raphanus sativus; Lactuca sativa; bioregenerative life support systems; photomorphogenesis ID HIGH-PRESSURE SODIUM; PHOTOSYNTHETIC EFFICIENCY; STEM GROWTH; PLANTS; PHOTOMORPHOGENESIS; WHEAT; YIELD; PRODUCTIVITY; ENVIRONMENTS; SPECTRUM AB Radish (Raphanus sativus L. cv. Cherriette), lettuce (Lactuca sativa L. cv. Waldmann's Green), and spinach (Spinacea oleracea L. cv. Nordic IV) plants were grown under 660-nm rod light-emitting diodes (LEDs) and were compared at equal photosynthetic photon flux (PPF) with either plants grown under cool-white fluorescent lamps (CWF) or red LEDs supplemented with 10% (30 mu mol.m(-2).s(-1)) blue light (400-500 nm) from blue fluorescent (BF) lamps. At 21 days after planting (DAP), leaf photosynthetic rates and stomatal conductance mere greater for plants grown under CWF light than for those grown under red LEDs, with or without supplemental blue light. At harvest (21 DAP), total dry-weight accumulation was significantly lower for all species tested when grown under red LEDs alone than when grown under CWF light or red LEDs + 10% BF light. Moreover, total dry weight for radish and spinach was significantly lower under red LEDs + 10% BF than under CWF light, suggesting that addition of blue light to the red LEDs was still insufficient for achieving maximal growth for these crops. C1 Dynamac Corp, Kennedy Space Ctr, FL 32899 USA. NASA, Biomed Operat Off, Kennedy Space Ctr, FL 32899 USA. RP Yorio, NC (reprint author), Dynamac Corp, Mail Code DYN-3, Kennedy Space Ctr, FL 32899 USA. NR 31 TC 133 Z9 158 U1 5 U2 58 PU AMER SOC HORTICULTURAL SCIENCE PI ALEXANDRIA PA 113 S WEST ST, STE 200, ALEXANDRIA, VA 22314-2851 USA SN 0018-5345 J9 HORTSCIENCE JI Hortscience PD APR PY 2001 VL 36 IS 2 BP 380 EP 383 PG 4 WC Horticulture SC Agriculture GA 423DY UT WOS:000168161200046 PM 12542027 ER PT J AU Dyudina, UA Ingersoll, AP Danielson, GE Baines, KH Carlson, RW AF Dyudina, UA Ingersoll, AP Danielson, GE Baines, KH Carlson, RW TI Interpretation of NIMS and SSI images on the Jovian Cloud Structure SO ICARUS LA English DT Article DE atmospheric structure; jovian atmosphere; image processing ID GREAT RED-SPOT; GALILEAN SATELLITES; JUPITER ATMOSPHERE; SPECTROMETER; EARTH AB We present maps of jovian cloud properties derived from images taken simultaneously by the Galileo solid state imaging system (SSI) and the near-infrared mapping spectrometer (NIMS) at 26 visible and near-infrared wavelengths, ranging from 0.41 to 5.2 mum. Three regions-the Great Red Spot (GRS), a 5-micron Hot Spot, and one of the White ovals-were studied, We perform a principal component analysis (PCA) on the multispectral images. The principal components (PCs), also known as empirical orthogonal functions, depend only on wavelength, The first PC is that spectral function which, when multiplied by an optimally chosen number (amplitude factor) at each pixel location and subtracted from the spectrum there, minimizes the variance for the image as a whole, Succeeding PCs minimize the residual variance after the earlier PCs have been subtracted off. We find that the pixel-to-pixel variations at the different wavelengths are highly correlated, such that the first three PCs explain 91% of the variance in the spectra, Further, one can estimate the amplitudes of the first two PCs using only the four SSI wavelengths and still explain 62% of the variance of the entire spectrum. This can be an advantage when trying to classify features that are resolved in the SSI images but not in the NIMS images. The first PC in all three regions shows negative correlation between 5 mum emission and reflected solar light in both atmospheric windows and the methane and ammonia absorption bands. Thus most of the bright, optically thick clouds blocking thermal emission are also extended vertically to the upper troposphere, The first PC at the GRS shows a negative correlation between the violet and all other bands except 5 mum, for which the correlation is positive, Thus in the GRS there is a red chromophore (absorbing in the violet, reflecting at longer wavelengths) which is associated with clouds that block 5-mum emission, There is no such correlation at the hot spot and white oval regions and therefore no chromophore associated with clouds. The second PC shows a positive correlation between the depth of the methane and ammonia absorption bands and brightness at other visible and near-IR wavelengths; there is also a negative correlation between these quantities and 5-mum emission. Thus some of the bright, optically thick clouds blocking thermal emission are deep and do not extend vertically to the upper troposphere. A color image composed using the first three PCs shows areas of unusual spectra, which appear in distinct colors. An example is the small convective stormlike cloud to the northwest of the GRS, This cloud is highly reflective at long wavelengths (4 mum) and might indicate unusually large particles. (C) 2001 Academic Press. C1 CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Dyudina, UA (reprint author), CALTECH, 150-21, Pasadena, CA 91125 USA. NR 20 TC 19 Z9 19 U1 2 U2 3 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 2001 VL 150 IS 2 BP 219 EP 233 DI 10.1006/icar.2000.6582 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 428BX UT WOS:000168442200003 ER PT J AU Sromovsky, LA Fry, PM Dowling, TE Baines, KH Limaye, SS AF Sromovsky, LA Fry, PM Dowling, TE Baines, KH Limaye, SS TI Neptune's atmospheric circulation and cloud morphology: Changes revealed by 1998 HST imaging SO ICARUS LA English DT Article DE Neptune; Neptune, atmosphere; Neptune, clouds ID FEATURES; METHANE; MOTIONS AB On 11-12 August 1998, we imaged Neptune using the Hubble Space Telescope WFPC2 CCD camera and NICMOS InSb camera to obtain high-spatial-resolution, absolutely calibrated imagery from the visible through the near infrared. We used nine HST orbits to intensively sample one rotation of Neptune, and four additional orbits to sample cloud evolution and motions one and two rotations later. In 1998 Neptune displayed more bright cloud features at southern mid-latitudes (mainly at 30 degreesS and 45 degreesS) than in 1996, producing small, but significant, increases in Neptune's disk-integrated albedo of 1.4 +/- 1, 1.9 +/- 1, and 9.5 +/- 1% for F467M, F673N, and F850LP filters respectively. Averages over longitude regions relatively free of discrete bright clouds did not show substantial brightness changes for most filters. Although we were unable to directly confirm the continued presence in 1998 of the 1996 Northern Great Dark Spot NGDS-32, we did find what we believe to be its bright northern companion cloud at 39-N. The increased extent of both northern and southern companions in 1998 may have obscured the normally dark core of this circulation feature. The 1996 Great Dark Spot NGDS-15 was not visible in 1998. The 1996 dark circumpolar band near 60 degrees -70 degreesS was present in 1998, with somewhat enhanced contrast. Significant evolution of cloud features was found over short time intervals of one and two rotations of Neptune, especially at 31 degreesS, 45 degreesS, and 70 degreesS. Cloud motions in 1998 agree relatively well with the 1989 Voyager smoothed profile of L. A. Sromovsky et al. (1983, Icarus 105, 110-141), with some exceptions associated with bright companion clouds, and with small but significant deviations that are consistent with those observed in 1995 and 1996 (Sromovsky et al. 2001, Icarus 149, 459-488). These wind profile deviations contribute important modifications to the potential vorticity gradients that control latitudinal drift rates of GDS-scale vortices on Neptune (according to numerical simulations of R. P. LeBeau and T. E. Dowling (1998, Icorus 132, 239-265)). However, these modifications alone do not explain the zero latitudinal drift of 1996 NGDS-32. (C) 2001 Academic Press. C1 Univ Wisconsin, Ctr Space Sci & Engn, Madison, WI 53706 USA. Univ Louisville, Comparat Plantetol Lab, Louisville, KY 40292 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sromovsky, LA (reprint author), Univ Wisconsin, Ctr Space Sci & Engn, 1225 W Dayton St, Madison, WI 53706 USA. RI Dowling, Timothy/J-4537-2013 OI Dowling, Timothy/0000-0002-7400-2274 NR 26 TC 26 Z9 26 U1 0 U2 2 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 2001 VL 150 IS 2 BP 244 EP 260 DI 10.1006/icar.2000.6574 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 428BX UT WOS:000168442200005 ER PT J AU Kim, YH Pesnell, WD Grebowsky, JM Fox, JL AF Kim, YH Pesnell, WD Grebowsky, JM Fox, JL TI Meteoric ions in the ionosphere of Jupiter SO ICARUS LA English DT Article ID PHOTOIONIZATION CROSS-SECTIONS; RADIO OCCULTATION MEASUREMENTS; AURORAL OXYGEN PRECIPITATION; DENSE INTERSTELLAR CLOUD; UPPER-ATMOSPHERE; DISSOCIATIVE RECOMBINATION; ASSOCIATION REACTIONS; HYDROCARBON IONS; ELECTRON-PRECIPITATION; RADIATIVE ASSOCIATION AB A reanalysis of the Voyager 2 radio occultation data has recently revealed a low-altitude layer in the jovian ionosphere (Hinson et al. 1998, J. Geophys. Res. 103, 9505-9520). The peak electron density of the layer measured on egress, which was at 93 degrees solar zenith angle near the morning terminator, was inferred to be of the order of 10(4) cm(-3). A substantial low-altitude layer of hydrocarbon ions in the jovian ionosphere was predicted by Kim and Fox (1994), but the peak total ion density at predawn was about 10(2) cm(-3) two orders of magnitude smaller than the noon values, due to the efficient recombination of molecular ions during the night. The existence of large electron densities in the jovian ionospheric E region at predawn suggests the presence of ions with long lifetimes and/or those produced by a source that exhibits little local time dependence, such as ions originating from meteoroid ablation in Jupiter's atmosphere. We have modeled the production rates and subsequent chemistry of seven meteoric ions, including O+, C-, Si+ Fe+, Mg+, Na+,and S+, their compounds with H, H-2, and hydrocarbons, and the corresponding neutral species, The models predict a layer of meteoric ions in the altitude region of 350-450 km above the 1-bar level, with peak total ion densities of several times 10(4) cm-3 which are comparable to the observed values. The peak of the meteoric atomic ion layer is most apparent at predawn and is located higher than that of the hydrocarbon ion layer during the daytime and higher than the altitude of peak production of ions by meteor ablation. At the altitude of peak ablation, about 350 km, meteoric ions are mainly removed by reactions with hydrocarbons in either two-body or three-body reactions, and the molecular ions produced are neutralized efficiently by dissociative recombination. Meteoric ions may also form adduct ions by termolecular reactions with hydrogen molecules, but metallic ions, such as Na+, Mg+, and Fe+, may be reformed from the adduct ions by a series of reactions with H atoms. Thus the net ion loss process at the metal ion peak may be dominated by rediative recombination, and the meteoric ion density profiles show little diurnal variation. The predicted peak electron density and altitude and the relative densities of the ions are dependent on the rate coefficients assumed for many of the reactions involved, and measurements of key rate coefficients are needed to further constrain the models. (C) 2001 Academic Press. C1 SUNY Stony Brook, Inst Terr & Planetary Atmospheres, Stony Brook, NY 11794 USA. Chungnam Natl Univ, Dept Astron & Space Sci, Daejon, South Korea. Nomad Res, Bowie, MD USA. NASA, Goddard Space Flight Ctr, Lab Planetary Atmospheres, Greenbelt, MD 20771 USA. RP Kim, YH (reprint author), SUNY Stony Brook, Inst Terr & Planetary Atmospheres, Stony Brook, NY 11794 USA. RI Pesnell, William/D-1062-2012; Grebowsky, Joseph/I-7185-2013 OI Pesnell, William/0000-0002-8306-2500; NR 83 TC 27 Z9 27 U1 1 U2 4 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 2001 VL 150 IS 2 BP 261 EP 278 DI 10.1006/icar.2001.6590 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 428BX UT WOS:000168442200006 ER PT J AU Abbott, LW Cox, G Nguyen, H AF Abbott, LW Cox, G Nguyen, H TI A cost effective critical space systems design approach SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB NASA-JSC requires avionics platforms capable of serving a wide range of applications in a cost-effective manner. In part, making the avionics platform cost effective means adhering to open standards and supporting the integration of COTS products with custom products. Inherently, operation in space requires low power, mass, and volume while retaining high performance, reconfigurability, scalability, and upgradability. The Universal Mini-Controller (UMC) project is based on a modified PC/104-Plus architecture while maintaining full compatibility with standard COTS PC/I04 products. The architecture consists of a library of stackable building block modules, which can be mixed and matched to meet a specific application. A set of NASA developed core building blocks, (e.g. processor card, analog input/output card, high level analog card, and a Mil-Std-1553 card) were constructed to meet critical functions and unique interfaces. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Abbott, LW (reprint author), NASA, Lyndon B Johnson Space Ctr, Code E02,2101 NASA Rd 1, Houston, TX 77058 USA. NR 1 TC 1 Z9 1 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 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD APR PY 2001 VL 16 IS 4 BP 7 EP 10 DI 10.1109/62.918017 PG 4 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA 424LM UT WOS:000168233800004 ER PT J AU Asenov, A Slavcheva, G Brown, AR Davies, JH Saini, S AF Asenov, A Slavcheva, G Brown, AR Davies, JH Saini, S TI Increase in the random dopant induced threshold fluctuations and lowering in sub-100 nm MOSFETs due to quantum effects: A 3-D density-gradient simulation study SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article DE dopant fluctuation; quantum effects; MOSFETs; numerical simulation; 3-D; threshold ID INVERSION-LAYERS; VOLTAGE; ELECTRON; EQUATION AB In this paper, we present a detailed simulation study of the influence of quantum mechanical effects in the inversion layer on random dopant induced threshold voltage fluctuations and lowering in sub-100 nm MOSFETs. The simulations have been performed using a three-dimensional (3-D) implementation of the density gradient (DG) formalism incorporated in our established 3-D atomistic simulation approach, This results in a self-consistent 3-D quantum mechanical picture, which implies not only the vertical inversion layer quantization but also the lateral confinement effects related to current filamentation in the "valleys" of the random potential fluctuations. We have shown that the net result of including quantum mechanical effects, while considering statistical dopant fluctuations, is an increase in both threshold voltage fluctuations and lowering, At the same time, the random dopant induced threshold voltage lowering partially compensates for the quantum mechanical threshold voltage shift in aggressively scaled MOSFETs with ultrathin gate oxides. C1 Univ Glasgow, Dept Elect & Elect Engn, Device Modeling Grp, Glasgow G12 8QQ, Lanark, Scotland. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Asenov, A (reprint author), Univ Glasgow, Dept Elect & Elect Engn, Device Modeling Grp, Glasgow G12 8QQ, Lanark, Scotland. RI Slavcheva, Gabriela/D-4570-2009; Slavcheva, Gabriela/L-6044-2013 OI Slavcheva, Gabriela/0000-0001-5474-9808 NR 32 TC 140 Z9 142 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 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD APR PY 2001 VL 48 IS 4 BP 722 EP 729 DI 10.1109/16.915703 PG 8 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 420BY UT WOS:000167985100015 ER PT J AU Gatebe, CK King, MD Tsay, SC Ji, Q Arnold, GT Li, JY AF Gatebe, CK King, MD Tsay, SC Ji, Q Arnold, GT Li, JY TI Sensitivity of off-nadir zenith angles to correlation between visible and near-infrared reflectance for use in remote sensing of aerosol over land SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID AIRBORNE SPECTRAL MEASUREMENTS; SATELLITE MEASUREMENTS; OPTICAL-THICKNESS; PATH RADIANCE; ATMOSPHERE; ANISOTROPY; TURBIDITY; REGION; MODIS; MASS AB Cloud absorption radiometer (CAR) multispectral and multiangular data, collected during the Smoke, Clouds, and Radiation-Brazil (SCAR-B) Experiment, was used to examine the ratio technique, the official method for remote sensing of aerosols over land from the moderate resolution imaging spectroradiometer (MODIS) data, for view angles from nadir to 65 degrees off-nadir. The strategy we used is to first select a pristine, low aerosol optical thickness flight, and we then computed ratios of reflectance at 0.47 and 0.68 mum to corresponding values at 2.20 mum, separately for backward and forward scattering directions. Similarly, we analyzed data from high turbidity flights for comparison purposes. For both flights, we removed the effects of atmospheric absorption and scattering using 6S, a radiative transfer code, and then recomputed the ratios again for different values of aerosol optical thickness. Finally, we analyzed bidirectional reflection function (BRF) data to examine the dependence of the ratio technique on the relative azimuth angle. Results of this analysis show that a relationship between visible reflectance and near infrared (TR) reflectance exists for view angles from nadir to 400 off-nadir, and that simple parametric relationships can be derived. In spite of these observed relationships, the relationship R-0.47 = R-2.20/4, used in remote sensing of aerosol over land, does not seem to hold for the cases tested, both in the forward and backward scattering directions and that R-0.68 = R-2.20 /2 seems to hold for view angles from nadir to 45 degrees off-nadir but only in the backward scattering direction. These ratios show little variation with azimuth view angle and this seems to hold well for backward scattering directions over dark targets. C1 Univ Maryland Baltimore Cty, Goddard Earth Sci & Technol Ctr, Baltimore, MD 21228 USA. NASA, Goddard Space Flight Ctr, Earth Sci Directorate, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Sci Syst Applicat Inc, Greenbelt, MD 20771 USA. Emergent Informat Technol Inc, Vienna, VA 22180 USA. RP Univ Maryland Baltimore Cty, Goddard Earth Sci & Technol Ctr, Baltimore, MD 21228 USA. EM gatebe@climate.gsfc.nasa.gov RI King, Michael/C-7153-2011; Gatebe, Charles/G-7094-2011; Tsay, Si-Chee/J-1147-2014 OI King, Michael/0000-0003-2645-7298; Gatebe, Charles/0000-0001-9261-2239; NR 41 TC 31 Z9 35 U1 0 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0196-2892 EI 1558-0644 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD APR PY 2001 VL 39 IS 4 BP 805 EP 819 DI 10.1109/36.917901 PG 15 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 424RX UT WOS:000168246200011 ER PT J AU Chin, TM AF Chin, TM TI On Kalman filter solution of space-time interpolation SO IEEE TRANSACTIONS ON IMAGE PROCESSING LA English DT Letter DE data assimilation; Kalman filter; Markov random field; recursive least-squares; satellite imaging ID DATA ASSIMILATION AB The approximate Kalman filtering algorithm presented in [1] for image sequence processing can introduce unacceptable negative eigenvalues in the information matrix and can have degraded performance in some applications. The improved algorithm presented in this note guarantees a positive definite information matrix, leading to more stable filter performance. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chin, TM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 6 Z9 7 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 1057-7149 J9 IEEE T IMAGE PROCESS JI IEEE Trans. Image Process. PD APR PY 2001 VL 10 IS 4 BP 663 EP 666 DI 10.1109/83.913601 PG 4 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 418DB UT WOS:000167873500018 PM 18249656 ER PT J AU Hodel, AS Hall, CE AF Hodel, AS Hall, CE TI Variable-structure PID control to prevent integrator windup SO IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS LA English DT Article; Proceedings Paper CT 31st Southeastern Symposium on System Theory CY MAR 21-23, 1999 CL AUBURN, ALABAMA DE limiting; proportional control; variable-structure systems ID ANTIWINDUP COMPENSATORS; CONDITIONING TECHNIQUE; SATURATION AB In this paper, we propose a new variable-structure (switching) method for the prevention of proportional-integral-derivative controller integrator windup in both continuous and discrete-time implementations. The method is easily implemented and tuned by practicing engineers. This new method is compared with several existing methods for the prevention of integrator windup. C1 Auburn Univ, Dept Elect & Comp Engn, Auburn, AL 36849 USA. NASA, Marshall Space Flight Ctr, Control Syst Grp, Huntsville, AL 35812 USA. RP Hodel, AS (reprint author), Auburn Univ, Dept Elect & Comp Engn, Auburn, AL 36849 USA. NR 31 TC 69 Z9 85 U1 1 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0278-0046 J9 IEEE T IND ELECTRON JI IEEE Trans. Ind. Electron. PD APR PY 2001 VL 48 IS 2 BP 442 EP 451 DI 10.1109/41.915424 PG 10 WC Automation & Control Systems; Engineering, Electrical & Electronic; Instruments & Instrumentation SC Automation & Control Systems; Engineering; Instruments & Instrumentation GA 420BZ UT WOS:000167985200025 ER PT J AU Heavner, TP Hollberg, L Jefferts, SR Kitching, J Klipstein, WM Meekhof, DM Robinson, HG AF Heavner, TP Hollberg, L Jefferts, SR Kitching, J Klipstein, WM Meekhof, DM Robinson, HG TI Characterization of a cold cesium source for PARCS: Primary atomic reference clock in space SO IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT LA English DT Article AB The Primary Atomic Reference Clock in Space (PARCS) project is a joint NIST-JPL-University of Colorado venture aimed at placing a Cs atomic clock aboard the International Space Station (ISS). This orbiting clock will achieve high accuracy, in part due to the long Ramsey times afforded by the microgravity environment, and allow for precision tests of fundamental physics including relativity theory. As pare of this effort, we are evaluating the characteristics of a prototype cold Cs source based on launching atoms from an optical molasses, Experimental results, in conjunction with theoretical modeling of atom flux requirements, will be applied to the design and construction of a robust, space-qualified device. The apparatus described here will be used to develop other PARCS components such as the microwave cavity structure and detection systems, and to investigate two-dimensional cooling schemes for future Cs fountains and space clocks. C1 Natl Inst Stand & Technol, Div Time & Frequency, Boulder, CO 80303 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Natl Inst Stand & Technol, Div Time & Frequency, Boulder, CO 80303 USA. NR 6 TC 7 Z9 9 U1 0 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9456 EI 1557-9662 J9 IEEE T INSTRUM MEAS JI IEEE Trans. Instrum. Meas. PD APR PY 2001 VL 50 IS 2 BP 500 EP 502 DI 10.1109/19.918176 PG 3 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 424LF UT WOS:000168233200083 ER PT J AU DiDomenico, LD Rebeiz, GM AF DiDomenico, LD Rebeiz, GM TI Digital communications using self-phased arrays SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article DE adaptive beam forming; digital communications; phase conjugation; phase filtering AB A new technique for full duplex digital communications using adaptive phase conjugation is presented in this paper. The technique is based on mixing the RF signal to an IF where it can be easily processed, and filtering the phase of the IF signal to separate the geometry phase and message phase, The retrodirective array automatically tracks communicating platforms and transmits a directive return signal without the use of phase shifters. A 6-GHz microstrip retrodirective antenna array was built, together with the signal IF processing needed for full duplex operation. The measured RCS values of a linear six-element array are in good agreement with theory and results in a 0- to -5-dB RCS for angles up to +/- 60 degrees. The measured RCS values of a circular array are much flatter and are 0 to -5 db up to +/- 80 degrees. Two-way digital communications at a baud rate of 78 kb/s was also demonstrated with BER < 10(-6) for signal-to-noise ratios around 10 dB, The application areas are in high-performance digital mobile telecommunications for commercial and military applications. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Michigan, Elect Engn & Comp Sci Dept, Ann Arbor, MI 48109 USA. RP DiDomenico, LD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 19 TC 44 Z9 44 U1 1 U2 3 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 APR PY 2001 VL 49 IS 4 BP 677 EP 684 DI 10.1109/22.915442 PN 1 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA 419PF UT WOS:000167957000013 ER PT J AU Savary, CA Grazziutti, ML Przepiorka, D Tomasovic, SP McIntyre, BV Woodside, DG Pellis, NR Pierson, DL Rex, JH AF Savary, CA Grazziutti, ML Przepiorka, D Tomasovic, SP McIntyre, BV Woodside, DG Pellis, NR Pierson, DL Rex, JH TI Characteristics of human dendritic cells generated in a microgravity analog culture system SO IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY-ANIMAL LA English DT Article; Proceedings Paper CT World Congress on In Vitro Biology CY JUN 10-15, 2000 CL SAN DIEGO, CA DE antigen-presenting cells; dendritic cells; fungus; immunity; microgravity; space flight ID DR ANTIGEN EXPRESSION; PERIPHERAL-BLOOD; SPACE-FLIGHT; BONE-MARROW; T-CELLS; IN-VIVO; SPACEFLIGHT; PROGENITORS; CYTOKINE; ASPERGILLOSIS AB Generation of an effective immune response requires that antigens be processed and presented to T lymphocytes by antigen-presenting cells, the most efficient of which are dendritic cells (DC). Because of their influence on both the innate and the acquired arms of immunity, a defect in DC would be expected to result in a broad impairment of immune function, not unlike that observed in astronauts during or after space flight, In the study reported here, we investigated whether DC generation and function are altered in a culture environment that models microgravity, i.e., the rotary-cell culture system (RCCS). We observed that RCCS supported the generation of DC identified by morphology, phenotype (HLA-DR+ and lacking lineage-associated markers), and function (high allostimulatory activity). However, the yield of DC from RCCS was significantly lower than that from static cultures. RCCS-generated DC were less able to phagocytose Aspergillus fumigatus conidia and expressed a lower density of surface HLA-DR. The proportion of DC expressing CD80 was also significantly reduced in RCCS compared to static cultures. When exposed to fungal antigens, RCCS-generated DC produced lower levels of interleukin-12 and failed to upregulate some costimulatory/adhesion molecules involved in antigen presentation, These data suggest that DC generation, and some functions needed to mount an effective immune response to pathogens, may be disturbed in the microgravity environment of space. C1 Univ Texas, MD Anderson Canc Ctr, Dept Surg Oncol, Houston, TX 77054 USA. Univ Texas, MD Anderson Canc Ctr, Dept Immunol, Houston, TX 77054 USA. Univ Texas, MD Anderson Canc Ctr, Dept Mol & Cellular Oncol, Houston, TX 77054 USA. Baylor Coll Med, Ctr Cell & Gene Therapy, Houston, TX 77030 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Texas, Sch Med, Dept Internal Med, Houston, TX 77030 USA. RP Savary, CA (reprint author), Univ Texas, MD Anderson Canc Ctr, Dept Surg Oncol, 7777 Knight Rd,Box 182, Houston, TX 77054 USA. EM csavary@mdanderson.org NR 37 TC 1 Z9 4 U1 1 U2 3 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 1071-2690 EI 1543-706X J9 IN VITRO CELL DEV-AN JI In Vitro Cell. Dev. Biol.-Anim. PD APR PY 2001 VL 37 IS 4 BP 216 EP 222 PG 7 WC Cell Biology; Developmental Biology SC Cell Biology; Developmental Biology GA 442MC UT WOS:000169288700004 PM 11409686 ER PT J AU Jessup, JM Pellis, NR AF Jessup, JM Pellis, NR TI NASA biotechnology: Cell science in microgravity SO IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY-ANIMAL LA English DT Editorial Material C1 Univ Texas, Hlth Sci Ctr, San Antonio, TX 78284 USA. NASA, Johnson Space Ctr, Cellular Biotechnol Program, Houston, TX 77058 USA. RP Jessup, JM (reprint author), Univ Texas, Hlth Sci Ctr, 7703 Floyd Curl Dr, San Antonio, TX 78284 USA. NR 7 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 APR PY 2001 VL 37 IS 4 BP U2 EP U3 PG 2 WC Cell Biology; Developmental Biology SC Cell Biology; Developmental Biology GA 442MC UT WOS:000169288700001 ER PT J AU Garg, VK AF Garg, VK TI Modeling film-coolant flow characteristics at the exit of shower-head holes SO INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW LA English DT Article; Proceedings Paper CT ASME International Mechanical Engineering Congress and Exposition CY NOV, 2000 CL ORLANDO, FLORIDA DE film cooling; modeling; shower-head holes; heat transfer ID COOLED ROTATING BLADE; TURBULENCE MODELS; TURBINE-BLADES; LEADING-EDGE AB The coolant flow characteristics at the hole exits of a film-cooled blade are derived from an earlier study where the hole pipes and coolant plenum were also discretized. The blade chosen is the VKI rotor with three staggered rows of shower-head holes. The present analysis applies these flow characteristics at the shower-head hole exits. A multi-block three-dimensional Navier-Stokes code with Wilcox's k-omega model is used to compute the heat transfer coefficient on the film-cooled turbine blade. A reasonably good comparison with the experimental data as well as with the more complete earlier analysis where the hole pipes and coolant plenum were also gridded is obtained. If the 1/7th power law is assumed for the coolant flow velocity and temperature distributions at the hole exits, considerable differences in the heat transfer coefficient on the blade surface, especially in the leading-edge region, are observed even though the span-averaged values of h match well with the experimental data. This calls for spatially-resolved experimental data near film-cooling holes on a blade for better validation of the code. (C) 2001 Elsevier Science Inc. All rights reserved. C1 NASA, Glenn Res Ctr, AYT Res Corp, Cleveland, OH 44135 USA. RP Garg, VK (reprint author), NASA, Glenn Res Ctr, AYT Res Corp, Mail Stop 5-11,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 21 TC 9 Z9 12 U1 1 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0142-727X J9 INT J HEAT FLUID FL JI Int. J. Heat Fluid Flow PD APR PY 2001 VL 22 IS 2 BP 134 EP 142 DI 10.1016/S0142-727X(00)00083-7 PG 9 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA 413TA UT WOS:000167627000003 ER PT J AU Prakash, A Fielding, EJ Gens, R Van Genderen, JL Evans, DL AF Prakash, A Fielding, EJ Gens, R Van Genderen, JL Evans, DL TI Data fusion for investigating land subsidence and coal fire hazards in a coal mining area SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID SAR INTERFEROMETRY; JHARIA COALFIELD; INDIA; CALIFORNIA; RADAR AB Coal mining areas all over the world are often threatened by serious environmental hazards such as the occurrence of coal fires, land subsidence, etc. Coal fires burn away the natural non-renewable coal resources, locally raise the temperature of the area, emit polluting gases such as oxides of carbon, sulphur and nitrogen, and when present underground are even the cause of land subsidence. Mining-induced subsidences, on the other hand, cause horizontal and vertical movements in the land surface, and open cracks and fissures that serve as inlets for oxygen, which in turn aggravate the problem of coal fires. These inter-related phenomena often render the mining areas unfit for human inhabitation and the commercial exploitation of coal nearly impossible in some parts. In this study, satellite data acquired in three regions of the electromagnetic spectrum, namely optical, thermal and microwave, along with field data, are used to identify the areas affected by coal fires and land subsidence in a coalfield in north-west China. Data fusion techniques are used for an integrated analysis of this complex problem. C1 Int Inst Aerosp Survey & Earth Sci, NL-7500 AA Enschede, Netherlands. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Delft Univ Technol, DEOS, NL-2629 JA Delft, Netherlands. RP Prakash, A (reprint author), Int Inst Aerosp Survey & Earth Sci, POB 6, NL-7500 AA Enschede, Netherlands. RI Fielding, Eric/A-1288-2007; OI Fielding, Eric/0000-0002-6648-8067; van Genderen, John/0000-0002-8900-4774 NR 15 TC 30 Z9 33 U1 1 U2 14 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD APR PY 2001 VL 22 IS 6 BP 921 EP 932 DI 10.1080/014311601300074441 PG 12 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 423QX UT WOS:000168189200002 ER PT J AU Vermote, EF Justice, CO Descloitres, J El Saleous, N Roy, DP Ray, J Margerin, B Gonzalez, L AF Vermote, EF Justice, CO Descloitres, J El Saleous, N Roy, DP Ray, J Margerin, B Gonzalez, L TI A SeaWiFS global monthly coarse-resolution reflectance dataset SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID EOS-MODIS; VEGETATION; INDEXES; IMAGES AB A global monthly reflectance dataset from September 1997 to December 1999 at 8 km spatial resolution was derived from Sea Wide Field of view Sensor ( SeaWiFS). This dataset, used for prototyping MODIS Land/Atmosphere algorithms, is now available for release to the broader community. This Letter describes the data processing, data format, and how these value-added data and some tools for their analysis may be obtained. C1 Univ Maryland, Dept Geog, College Pk, MD 20742 USA. Univ Virginia, Dept Environm Sci, Charlottesville, VA 22903 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. Univ Sci & Tech Lille, Opt Atmospher Lab, Villeneuve Dascq, France. RP Vermote, EF (reprint author), Univ Maryland, Dept Geog, College Pk, MD 20742 USA. RI Vermote, Eric/K-3733-2012 NR 13 TC 4 Z9 4 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD APR PY 2001 VL 22 IS 6 BP 1151 EP 1158 DI 10.1080/01431160117982 PG 8 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 423QX UT WOS:000168189200014 ER PT J AU Mauget, BR Minnetyan, L Chamis, CC AF Mauget, BR Minnetyan, L Chamis, CC TI Large deformation nonlinear response of soft composite structures via laminate analogy SO JOURNAL OF ADVANCED MATERIALS LA English DT Article AB The large deformation behavior of fiber preform and angle ply composites with very soft matrix is the subject of this paper. For these materials, large strains and therefore significant changes in the fiber orientations occur due to the application of small traction, thus drastically changing their mechanical properties. The present method uses a laminate analogy with very low stiffness matrix to compute the finite element properties. The assumptions are that fibers do not elongate, the laminate is made of symmetrically woven fibers and that during a finite element step the properties can be considered constant. Based on these assumptions, a simple way to compute the fiber angle changes is proposed. It is noted that a rectangular box on the soft matrix composite with fibers as its diagonal will deform into a box of different aspect ratio. The large displacement approach is valid since the properties depend on the global Poisson's ratio computation that is proven accurate. A traction test is simulated to demonstrate the method. C1 Clarkson Univ, Potsdam, NY 13699 USA. NASA, Glenn Res Ctr, Cleveland, OH USA. RP Mauget, BR (reprint author), Clarkson Univ, Potsdam, NY 13699 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 USA SN 1070-9789 J9 J ADV MATER JI J. Adv. Mater. PD APR PY 2001 VL 33 IS 2 BP 21 EP 26 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA 423GY UT WOS:000168168600004 ER PT J AU Mankins, JC AF Mankins, JC TI Space solar power: A major new energy option? SO JOURNAL OF AEROSPACE ENGINEERING LA English DT Article AB Large space solar-power systems have intermittently been a topic for consideration during the past 30 years. However, the last major studies in the United States on these concepts were conducted in the late 1970s. After two decades of relative inactivity, large-scale space solar power (SSP), including the generation of solar power in space for transmission to terrestrial markets, has recently reemerged as a potential energy option. This occurrence is timely because global energy demand continues to grow dramatically while environmental concerns increase. Demand for power in space is also likely to increase during the same time frame. A wide range of technology advances would be needed to enable such systems. In addition to very low cost space transportation and highly efficient and high voltage solar arrays, significant developments must also take place in technologies such as wireless power transmission, large space structures, robotic assembly and maintenance, and others. However, recent NASA studies and focused research and development progress in a number of key areas suggest that such systems are technically feasible. This paper presents an overview of the subject of space solar power, including results of recent NASA activities. C1 NASA Headquarters, Ofc Space Flight, Washington, DC 20546 USA. RP Mankins, JC (reprint author), NASA Headquarters, Ofc Space Flight, Washington, DC 20546 USA. NR 17 TC 19 Z9 19 U1 0 U2 5 PU ASCE-AMER SOC CIVIL ENGINEERS PI RESTON PA 1801 ALEXANDER BELL DR, RESTON, VA 20191-4400 USA SN 0893-1321 J9 J AEROSPACE ENG JI J. Aerosp. Eng. PD APR PY 2001 VL 14 IS 2 BP 38 EP 45 DI 10.1061/(ASCE)0893-1321(2001)14:2(38) PG 8 WC Engineering, Aerospace; Engineering, Civil SC Engineering GA 415MW UT WOS:000167726200002 ER PT J AU Mankins, JC AF Mankins, JC TI Space solar power: An assessment of challenges and progress SO JOURNAL OF AEROSPACE ENGINEERING LA English DT Article AB The capability to generate power in space for transmission to terrestrial markets is a long-term visionary goal that embodies a wide range of technical challenges. Space solar-power (SSP) systems will be very large, but they must be affordable if they are to be developed some day. Addressing the technologies required to construct gigawatt-class, commercial "solar-power satellites" in the distant future can open many other applications opportunities in space and on Earth in the near future. Technical hurdles have been explored and characterized by NASA's recent SSP Exploratory Research and Technology Program. The strategic technology areas examined include solar power generation: wireless power transmission; onboard power management and distribution: structural concepts, materials, and controls; and others. Important progress has been achieved since major space power system studies were conducted in the 1970s. However, significant and highly challenging research and technology development must be conducted successfully across a wide range of areas so that affordable and abundant SSP can be realized. C1 NASA Headquarters, Ofc Space Flight, Washington, DC 20546 USA. RP Mankins, JC (reprint author), NASA Headquarters, Ofc Space Flight, Washington, DC 20546 USA. NR 8 TC 3 Z9 3 U1 0 U2 1 PU ASCE-AMER SOC CIVIL ENGINEERS PI RESTON PA 1801 ALEXANDER BELL DR, RESTON, VA 20191-4400 USA SN 0893-1321 J9 J AEROSPACE ENG JI J. Aerosp. Eng. PD APR PY 2001 VL 14 IS 2 BP 46 EP 51 DI 10.1061/(ASCE)0893-1321(2001)14:2(46) PG 6 WC Engineering, Aerospace; Engineering, Civil SC Engineering GA 415MW UT WOS:000167726200003 ER PT J AU Whittaker, W Staritz, P Ambrose, R Kennedy, B Fredrickson, S Parrish, J Urmson, C AF Whittaker, W Staritz, P Ambrose, R Kennedy, B Fredrickson, S Parrish, J Urmson, C TI Robotic assembly of space solar-power facilities SO JOURNAL OF AEROSPACE ENGINEERING LA English DT Article AB This paper profiles research relating to the robotic assembly, inspection, and maintenance of space solar-power facilities. Free-flying robots, fixed-base manipulators, and attached mobile manipulators are examined, the technical challenges facing them are outlined, and their roles in the construction process are illuminated. Themes include autonomous materials delivery, warehousing, large-scale payload handling and mating, payload attachment in confined spaces, and inspection. Research has addressed a fraction of the technologies needed to perform reliable autonomous assembly, inspection, and maintenance. Areas in need of further development are examined and potential research is outlined. Current technology cannot fulfill the requirements of orbital construction. The research and development needed can be completed in the near future. and substantive assembly inspection and maintenance can be achieved. C1 Carnegie Mellon Univ, Pittsburgh, PA 15213 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NASA, Jet Prop Lab, Pasadena, CA 91109 USA. NASA Headquarters, Washington, DC 20546 USA. RP Whittaker, W (reprint author), Carnegie Mellon Univ, 5000 Forbes Ave, Pittsburgh, PA 15213 USA. NR 9 TC 6 Z9 6 U1 0 U2 3 PU ASCE-AMER SOC CIVIL ENGINEERS PI RESTON PA 1801 ALEXANDER BELL DR, RESTON, VA 20191-4400 USA SN 0893-1321 J9 J AEROSPACE ENG JI J. Aerosp. Eng. PD APR PY 2001 VL 14 IS 2 BP 59 EP 64 DI 10.1061/(ASCE)0893-1321(2001)14:2(59) PG 6 WC Engineering, Aerospace; Engineering, Civil SC Engineering GA 415MW UT WOS:000167726200005 ER PT J AU Su, CH Feth, S Wang, LJ Lehoczky, SL AF Su, CH Feth, S Wang, LJ Lehoczky, SL TI Photoluminescence studies of ZnSe starting materials and vapor grown bulk crystals SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE characterization; growth from vapor; zinc compounds; semiconducting II-VI materials ID MOLECULAR-BEAM EPITAXY; INTENSITY-DEPENDENT ENERGY; VI COMPOUND SEMICONDUCTORS; SELENIDE SINGLE-CRYSTALS; ACCEPTOR-PAIR BANDS; NITROGEN-DOPED ZNSE; ZINC SELENIDE; HIGH-PURITY; DONOR; LUMINESCENCE AB Low-temperature photoluminescence (PL) spectra were measured on ZnSe starting materials provided by various vendors and on bulk crystals grown from these starting materials by physical vapor transport (PVT) to study the effects of purification and contamination during PVT process. The impurity levels in one set of starting material/grown crystal were also measured by grow discharge mass spectroscopy (GDMS). The purification effect of pre-growth heat treatments and the PVT process is evidenced from the GDMS results which showed orders of magnitude reduction in the Li and Na concentration and a factor of 3 reduction in the O content after growth. The PL spectra showed that the strong emissions associated with Li (or Na) In one of the starting materials disappeared after growth. The GDMS results also showed increases in the Al and Si contents by orders of magnitude after growth. To evaluate the contamination of the crystal during the high temperature,growth process, three growth runs were processed using similar growth parameters but different furnace environments, The PL spectra suggest that the Al contamination originated from the fused silica ampoule and that the Inconel cartridge might have been the cause of the broad Cu green and Cu red bands observed in one of the grown crystals. Published by Elsevier Science B.V. C1 NASA, Marshall Space Flight Ctr, Sci Directorate, Micrograv Sci & Applicat Dept, Huntsville, AL 35812 USA. Univ Tennessee, Dept Phys Geol & Astron, Chattanooga, TN 37403 USA. RP Su, CH (reprint author), NASA, Marshall Space Flight Ctr, Sci Directorate, Micrograv Sci & Applicat Dept, SD47, Huntsville, AL 35812 USA. RI Feth, Shari/F-6302-2013 OI Feth, Shari/0000-0003-3545-5649 NR 39 TC 13 Z9 18 U1 0 U2 3 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 APR PY 2001 VL 224 IS 1-2 BP 32 EP 40 DI 10.1016/S0022-0248(01)00770-9 PG 9 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 423BX UT WOS:000168156500005 ER PT J AU Vetter, WM Huang, W Neudeck, P Powell, JA Dudley, M AF Vetter, WM Huang, W Neudeck, P Powell, JA Dudley, M TI Synchrotron white-beam topographic studies of 2H-SiC crystals SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE X-ray topography; growth from vapor; single crystal growth; semiconducting materials ID SINGLE-CRYSTALS; DEFECTS AB Synchrotron white beam X-ray topography (SWBXT) has been used to characterize 2H-silicon carbide crystals grown by the chemical reduction of methyltrichlorosilane at 1400 degreesC. The crystals studied had the form of tapered needles around 1 mm long with hexagonal cross-sections 0.4 mm in diameter. SWBXT images recorded from two different crystals showed their excellent quality, as evidenced by the presence of Pendellosung fringes. Topographs recorded with various diffraction vectors revealed no evidence of the axial screw dislocations reported in 2H-SiC by Setaka and Ejiri, based on their observations of spiral growth steps. Neither were there any dislocations with Burgers vectors lying in the crystals' basal planes. The absence of axial screw dislocations indicates that the growth was not screw dislocation assisted, but occurced by diffusion-controlled growth; and some other influence such as thermodynamics, initial nucleation, and/or impurity assisted growth, was responsible for the isolation of the 2H polytype. (C) 2001 Published by Elsevier Science B.V. C1 SUNY Stony Brook, Dept Mat Sci & Engn, Stony Brook, NY 11794 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Vetter, WM (reprint author), SUNY Stony Brook, Dept Mat Sci & Engn, Stony Brook, NY 11794 USA. NR 15 TC 3 Z9 4 U1 0 U2 0 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 APR PY 2001 VL 224 IS 3-4 BP 269 EP 273 DI 10.1016/S0022-0248(01)00971-X PG 5 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 427VH UT WOS:000168425800013 ER PT J AU Choi, SR Gyekenyesi, JP AF Choi, SR Gyekenyesi, JP TI Slow crack growth analysis of advanced structural ceramics under combined loading conditions: Damage assessment in life prediction testing SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 45th International Gas Turbine and Aeroengine Congress and Exhibition CY MAY 08-11, 2000 CL MUNICH, GERMANY ID BRITTLE MATERIALS; FLAW SYSTEM; FATIGUE; STRENGTH AB Slow crack growth analysis was performed with three different loading histories including constant stress-rate/constant stress-rate testing (Case I loading), constant stress/constant stress-rate testing (Case II loading), and cyclic stress/constant stress-rate testing (Case III loading). Strength degradation due to slow crack growth and/or damage accumulation was determined numerically as a function of percentage of interruption time between the two loading sequences for a given loading history. The numerical solutions were examined with the experimental data determined at elevated temperatures using Sour different advanced ceramic materials, two silicon nitrides, one silicon carbide and one alumina for the Case I loading history, and alumina for the Case II loading history. The numerical solutions were in reasonable agreement with the experimental data, indicating that notwithstanding some degree of deep deformation presented for some test materials slow crack growth was a governing mechanism associated with failure Sor all the test materials. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Cleveland, OH 44142 USA. RP Choi, SR (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 18 TC 6 Z9 6 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD APR PY 2001 VL 123 IS 2 BP 277 EP 287 DI 10.1115/1.1365160 PG 11 WC Engineering, Mechanical SC Engineering GA 438AL UT WOS:000169031500003 ER PT J AU Singh, M Lara-Curzio, E AF Singh, M Lara-Curzio, E TI Design, fabrication, and testing of ceramic joints for high temperature SiC/SiC composites SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 45th International Gas Turbine and Aeroengine Congress and Exhibition CY MAY 08-11, 2000 CL MUNICH, GERMANY ID SILICON-CARBIDE CERAMICS AB Various issues associated with the design and mechanical evaluation of joints of ceramic matrix composites are discussed. The specific case of an affordable, robust ceramic joining technology (ARCJoinT) to join silicon cal bide (CG-Nicnlon (TM)) fiber-reinforced-chemically vapor infiltrated (CVI) silicon carbide matrix composites is addressed. Experimental results are presented for the time and temperature dependence of the shear strength of these joints in air lip to 1200 degreesC. From compression testing of double-notched joint specimens with a notch separation of 4 mm, it was found that the apparent shear strength of the joints decreased from 92 MPa at room temperature to 71 MPa at 1200 degreesC. From shear stress-rupture testing in air at 1200 degreesC it was found that the shear strength of the joints decreased rapidly with time from an initial shear strength of 71 MPa to a value of 17.5 MPa after 14.3 h. The implications of these results in relation to the expected long-term service life of these joints in applications at Elevated temperatures al e discussed. C1 NASA, Glenn Res Ctr, Dynacs Engn Co, Cleveland, OH 44135 USA. Oak Ridge Natl Lab, Div Met & Ceram, Oak Ridge, TN 37831 USA. RP Singh, M (reprint author), NASA, Glenn Res Ctr, Dynacs Engn Co, Cleveland, OH 44135 USA. NR 16 TC 14 Z9 15 U1 2 U2 9 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD APR PY 2001 VL 123 IS 2 BP 288 EP 292 DI 10.1115/1.1362664 PG 5 WC Engineering, Mechanical SC Engineering GA 438AL UT WOS:000169031500004 ER PT J AU Collins, MM Cooper, CD Dietz, JD Clausen, CA Tazi, LM AF Collins, MM Cooper, CD Dietz, JD Clausen, CA Tazi, LM TI Pilot-scale evaluation of H2O2 injection to control to NOx emissions SO JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE LA English DT Article ID HYDROGEN-PEROXIDE; OXIDATION AB Nitric oxide (NO) in combustion flue gasses can be converted to higher oxidation states by the injection of aqueous solutions of hydrogen peroxide (H2O2) into the hot flue gases. The NO is oxidized to NO2, HNO2, and HNO3, which can then be removed in a wet scrubber. A pilot plant system that was designed, constructed, and operated at Kennedy Space Center confirmed previous results that H2O2 is very effective at oxidizing NO; conversions of NO above 90% were obtained at temperatures of about 500 degreesC (930 degreesF) using mole ratios of H2O2:NOx slightly above 1.0. The mole ratios of H2O2/NOx needed to obtain high conversions of NO were significantly lower in the pilot plant that they had been in previous laboratory studies. demonstrating that this process can be an economically feasible method for NO, control. The position of the injector and the type of atomization were very important to the efficient utilization of peroxide. When SO2 was present in the flue gas, both NO and SO2 were oxidized without increasing the demand for peroxide. C1 NASA, Biol Sci Branch, Kennedy Space Ctr, FL 32899 USA. Univ Cent Florida, Dept Civil & Environm Engn, Orlando, FL 32816 USA. Univ Cent Florida, Dept Chem, Orlando, FL 32816 USA. RP Collins, MM (reprint author), NASA, Biol Sci Branch, YA-D3, Kennedy Space Ctr, FL 32899 USA. NR 16 TC 7 Z9 10 U1 0 U2 10 PU ASCE-AMER SOC CIVIL ENGINEERS PI RESTON PA 1801 ALEXANDER BELL DR, RESTON, VA 20191-4400 USA SN 0733-9372 J9 J ENVIRON ENG-ASCE JI J. Environ. Eng.-ASCE PD APR PY 2001 VL 127 IS 4 BP 329 EP 336 DI 10.1061/(ASCE)0733-9372(2001)127:4(329) PG 8 WC Engineering, Environmental; Engineering, Civil; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA 415HE UT WOS:000167714700008 ER PT J AU Neugebauer, M Goldstein, BE Winterhalter, D Smith, EJ MacDowall, RJ Gary, SP AF Neugebauer, M Goldstein, BE Winterhalter, D Smith, EJ MacDowall, RJ Gary, SP TI Ion distributions in large magnetic holes in the fast solar wind SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MIRROR-MODE STRUCTURES; ANISOTROPY INSTABILITIES; ULYSSES; DISCONTINUITIES; FIELD; WAVES; MAGNETOSHEATH; DEPRESSIONS; SIMULATIONS AB Magnetic holes are isolated localized depressions in the magnitude of the interplanetary magnetic field. Six examples of long-duration (9 to 30 min) magnetic holes observed by the Ulysses spacecraft at high heliographic latitudes near 3 AU are studied in detail. Each of the holes was in pressure balance with its surroundings. The proton-proton and alpha-proton differential streaming typically observed in the fast solar wind dropped to very low levels within the holes. The ion temperatures perpendicular to the magnetic field also increased, leading to marginal mirror-mode stability. Possible causes of these high-latitude magnetic holes are discussed. A new method of deconvolving the three-dimensional angular distributions of the protons and alpha particles from the ion instrument's angular response is described in an appendix. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. RP Neugebauer, M (reprint author), CALTECH, Jet Prop Lab, MS 169-506, Pasadena, CA 91109 USA. RI MacDowall, Robert/D-2773-2012 NR 33 TC 54 Z9 54 U1 0 U2 1 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 APR 1 PY 2001 VL 106 IS A4 BP 5635 EP 5648 DI 10.1029/2000JA000331 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 418MC UT WOS:000167895100010 ER PT J AU Reisenfeld, DB Gary, SP Gosling, JT Steinberg, JT McComas, DJ Goldstein, BE Neugebauer, M AF Reisenfeld, DB Gary, SP Gosling, JT Steinberg, JT McComas, DJ Goldstein, BE Neugebauer, M TI Helium energetics in the high-latitude solar wind: Ulysses observations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ELECTROMAGNETIC PROTON/PROTON INSTABILITIES; MAGNETIC-FIELD; MAGNETOSONIC INSTABILITY; CYCLOTRON-RESONANCE; KINETIC-PROPERTIES; CORONAL HOLES; IONS; ACCELERATION; DISTRIBUTIONS; EQUATION AB We present a study of the interplanetary evolution of solar wind helium (alpha particle) energetics. The analysis of Ulysses observations of the fast high-latitude solar wind concentrates on the radial evolution of the alpha-proton differential streaming V-alphap, the alpha temperature, and the alpha temperature anisotropy. Ulysses observations show that the average v(alphap) steadily decreases with radius, ranging from similar to 40 km s(-1) at 1.5 AU to similar to 15 km s(-1) at 4.2 AU. In addition, observations indicate that the alphas cool more slowly than what would be expected from adiabatic expansion. The radial increase in the nonadiabatic heat content of the alphas matches the free energy liberated as v(alphap) decreases with distance, suggesting that the dissipated energy acts to heat the alpha particles. The alphas also exhibit a temperature anisotropy of T-perpendicular to alpha/T \ \ (alpha) = 0.87, which is essentially constant with distance. These and other observations reported here place stringent constraints on recent plasma microinstability models that attempt to explain the evolution of alpha-proton differential streaming and ion heating in the heliosphere. C1 Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. SW Res Inst, Instrumentat & Space Res Div, San Antonio, TX 78228 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Reisenfeld, DB (reprint author), Univ Calif Los Alamos Natl Lab, MS D466, Los Alamos, NM 87545 USA. RI Reisenfeld, Daniel/F-7614-2015 NR 45 TC 44 Z9 44 U1 0 U2 1 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 APR 1 PY 2001 VL 106 IS A4 BP 5693 EP 5708 DI 10.1029/2000JA000317 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 418MC UT WOS:000167895100014 ER PT J AU Meziane, K Mazelle, C Lin, RP LeQueau, D Larson, DE Parks, GK Lepping, RP AF Meziane, K Mazelle, C Lin, RP LeQueau, D Larson, DE Parks, GK Lepping, RP TI Three-dimensional observations of gyrating ion distributions far upstream from the Earth's bow shock and their association with low-frequency waves SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID GYROPHASE-BUNCHED IONS; SOLAR-WIND; DIFFUSE IONS; ISEE-2 OBSERVATIONS; REFLECTED IONS; INSTABILITIES; POPULATIONS; PLASMA; INTERMEDIATE; SIMULATIONS AB This report discusses the nature of gyrating ion distributions observed on board the Wind spacecraft by the three-dimensional ion electrostatic analyzer with high geometrical factor (3DP PESA-High). The gyrating ion distributions are observed near the inner ion beam foreshock boundary at distances between similar to9 and similar to 83 R-E Our upstream measurements confirm several features previously reported using two-dimensional measurements. These distributions are observed in association with low-frequency waves with substantial amplitude (\ deltaB \ /B > 0.2). The analysis of the waves shows that they propagate in the right-hand mode roughly along the background magnetic field. The ions are bunched in gyrophase angle when the associated waves are quasi-monochromatic and high in amplitude. The peak of the ion distribution function rotates in the gyrophase plane. If the wave train is nonmonochromatic, the particle phase angle distribution is extended over a larger range, suggesting the occurrence of a phase mixing effect or a source at the shock. The phase angle distribution also seems to be energy-dependent, and no,gyrophase rotation is observed in this case. Furthermore, we have characterized the ion distributions by computing their densities as well as parallel and perpendicular velocities. The results clearly indicate that the waves are cyclotron-resonant with the field-aligned beams observed just upstream. The resonance condition strongly suggests the local production of these gyrating ions in a field-aligned-beam disruption. Such a resonant wave-particle interaction may be a dominant characteristic of the back-streaming ion population in the foreshock at large distances from the Earth's bow shock. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Ctr Etud Spatiale Rayonnements, F-31029 Toulouse, France. Univ Washington, Geophys Program, Seattle, WA 98195 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Meziane, K (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NR 35 TC 43 Z9 43 U1 1 U2 3 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 APR 1 PY 2001 VL 106 IS A4 BP 5731 EP 5742 DI 10.1029/2000JA900079 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 418MC UT WOS:000167895100017 ER PT J AU Giles, BL Hoffman, RA AF Giles, BL Hoffman, RA TI Special section: Insights from the Polar spacecraft - Foreword SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Editorial Material C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Giles, BL (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Code 692, Greenbelt, MD 20771 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD APR 1 PY 2001 VL 106 IS A4 BP 5761 EP 5762 DI 10.1029/2001JA000030 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 418MC UT WOS:000167895100019 ER PT J AU Chua, D Parks, G Brittnacher, M Peria, W Germany, G Spann, J Carlson, C AF Chua, D Parks, G Brittnacher, M Peria, W Germany, G Spann, J Carlson, C TI Energy characteristics of auroral electron precipitation: A comparison of substorms and pressure pulse related auroral activity SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MASS EJECTIONS; SOURCE REGION; EMISSIONS; IMAGES; MAGNETOSPHERE; SHOCKS; EVENT AB The Polar Ultraviolet Imager (UVI) observes auroral responses to incident solar wind pressure pulses and interplanetary shocks such as those associated with coronal mass ejections (CMEs). The arrival of a CME pressure pulse at the front of the magnetosphere results in highly disturbed geomagnetic conditions and a substantial increase in both dayside and nightside auroral precipitation. Our observations show a simultaneous brightening over broad areas of the dayside and nightside aurora in response to a pressure pulse, indicating that more magnetospheric regions participate as sources for auroral precipitation than during isolated substorms. We estimate the average energies of incident auroral electrons using Polar UVI images and compare the precipitation energies during pressure pulse associated events with those during isolated auroral-substorms. Electron precipitation during substorms has average energies greater than 10 keV and is structured both in local time and magnetic latitude. For auroral intensifications following the arrival of a pressure pulse or interplanetary shock, electron precipitation is less spatially structured and has greater flux of lower-energy electrons (E-ave less than or equal to 7 keV) than during isolated substorm onsets. The average energies of the precipitating electrons inferred from UVI are consistent with those measured in situ by the Fast Auroral Snapshot (FAST) spacecraft. These observations quantify the differences between global and local auroral precipitation processes and will provide a valuable experimental check for models of sudden storm commencements and magnetospheric response to perturbations in the solar wind. C1 Univ Washington, Geophys Program, Seattle, WA 98195 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Alabama, Huntsville, AL 35899 USA. NASA Headquarters, Washington, DC 20546 USA. RP Chua, D (reprint author), Univ Washington, Geophys Program, Box 351650, Seattle, WA 98195 USA. NR 36 TC 50 Z9 52 U1 1 U2 1 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 APR 1 PY 2001 VL 106 IS A4 BP 5945 EP 5956 DI 10.1029/2000JA003027 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 418MC UT WOS:000167895100033 ER PT J AU Angelopoulos, V Mozer, FS Bonnell, J Temerin, M Somoza, M Peterson, WK Collin, HL Giles, B AF Angelopoulos, V Mozer, FS Bonnell, J Temerin, M Somoza, M Peterson, WK Collin, HL Giles, B TI Wave power studies of cusp crossings with the Polar satellite SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID TRANSVERSE ION ENERGIZATION; ELECTRIC-FIELD STRUCTURES; HIGH-LATITUDE IONOSPHERE; KINETIC ALFVEN WAVES; ELECTROSTATIC SHOCKS; MAGNETOSPHERE; INSTRUMENT; FREQUENCY; ACCELERATION; TURBULENCE AB Burst data from the electric field instrument (EFI) on the Polar satellite are used to classify cusp wave properties and the association of the observed waves with particle populations. The most intense wave type (most commonly triggering burst mode data collection) are the broadbanded waves which are then studied in detail using the three-dimensional resolution of the EFI. Finite wavelength effects are removed using two techniques: time-shifting of the sphere potentials to a spacecraft body reference time and spin angle selection. The corrected electric field signal exhibits a uniform spectrum in two dimensions. The wave properties are consistent with two-dimensional turbulence, with phase velocities smaller than the spacecraft velocity and frequency as low as (or lower than) the oxygen gyrofrequency. Owing to their low frequency, we conclude that these waves cannot resonate with and thus heat the ions. The broad k-spectrum and very low frequency in the plasma frame points toward drift or shear instabilities for wave excitation. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Lockheed Martin, Space Phys Lab, Palo Alto, CA 94304 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Angelopoulos, V (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RI Peterson, WK/A-8706-2009 OI Peterson, WK/0000-0002-1513-6096 NR 37 TC 15 Z9 15 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-SPACE JI J. Geophys. Res-Space Phys. PD APR 1 PY 2001 VL 106 IS A4 BP 5987 EP 6006 DI 10.1029/2000JA900127 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 418MC UT WOS:000167895100037 ER PT J AU Elliott, HA Comfort, RH Craven, PD Chandler, MO Moore, TE AF Elliott, HA Comfort, RH Craven, PD Chandler, MO Moore, TE TI Solar wind influence on the oxygen content of ion outflow in the high-altitude polar cap during solar minimum conditions SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY MAGNETIC-FIELD; PLASMA SOURCE INSTRUMENT; LATITUDE ELECTRIC POTENTIALS; DAYSIDE MAGNETOSPHERE; DYNAMICS EXPERIMENT; BIRKELAND CURRENTS; O+ IONS; SHEET; CONVECTION; IMF AB We correlate solar wind and interplanetary magnetic field (IMF) properties with the properties of O+ and H+ during early 1996 (solar minimum) at altitudes between 5.5 and 8.9 RE geocentric using the Thermal Ion Dynamics Experiment (TIDE) on the Polar satellite. Throughout the high-altitude polar cap we observe H+ to be more abundant than O+. O+ is found to be more abundant at lower latitudes when the solar wind speed is low (and Kp is low), while at higher solar wind speeds (and high Kp), O+ is observed across most of the polar cap. The O+ density and parallel flux are well organized by solar wind dynamic pressure, both increasing with solar wind dynamic pressure. Both the O+ density and parallel flux have positive correlations with both VswBIMF and E-sw. No correlation is found between O+ density and IMF Bz, although a nonlinear relationship with IMF By is observed, possibly due to a strong linear correlation with the dynamic pressure. H+ is not as highly correlated with solar wind and IMF parameters, although H+ density and parallel flux are negatively correlated with IMF By and positively correlated with both VswBIMF and E-sw In this solar minimum data set, H+ is dominant, so that contributions of this plasma to the plasma sheet would have very low O+ to H+ ratios. C1 Univ Alabama, CSPAR, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Directorate, Huntsville, AL 35812 USA. NASA, Goddard Space Flight Ctr, Interplanetary Phys Branch, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Elliott, HA (reprint author), Univ Alabama, CSPAR, Huntsville, AL 35899 USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 55 TC 51 Z9 51 U1 0 U2 3 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 APR 1 PY 2001 VL 106 IS A4 BP 6067 EP 6084 DI 10.1029/2000JA003022 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 418MC UT WOS:000167895100043 ER PT J AU Su, YJ Borovsky, JE Thomsen, MF Dubouloz, N Chandler, MO Moore, TE Bouhram, M AF Su, YJ Borovsky, JE Thomsen, MF Dubouloz, N Chandler, MO Moore, TE Bouhram, M TI Plasmaspheric material on high-latitude open field lines SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETOPAUSE RECONNECTION; PLASMA; CUSP; ORIGIN AB During periods of increased geomagnetic activity, cold and dense plasmaspheric material is observed to drain from the inner magnetosphere toward the dayside magnetopause. Geosynchronous observations have shown that plasmaspheric material may participate in the dayside reconnection. However, predictions of plasmaspheric material passing through the polar region on recently opened field lines have not yet been confirmed by observations. We present evidence for the existence of such plasmaspheric material on high-latitude open magnetic field lines based on our investigations of 20 months of Interball/Hyperboloid observations and 11 months of Polar/Thermal Ion Dynamics Experiment (TIDE) observations. In order to distinguish plasmaspheric material from the low-energy portion of entering magnetosheath plasma from the solar wind, observed phase-space densities are compared to modeled magnetosheath and plasmaspheric phase-space densities. The phase-space density distribution function of magnetosheath ions is estimated from upstream solar wind parameters using the gasdynamic theory. Twenty-one events were found in which Interball passed through open field lines on the dayside during periods of increased geomagnetic activity, two of which show evidence for the presence of plasmaspheric material. Additionally, six such events were identified from the Polar/TIDE database. Although the occurrence frequency is low, evidence of cold plasmaspheric material being transported on high-latitude open field lines does exist. C1 Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80303 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Ctr Etud Environm Terrestre & Planetaire, F-94107 St Maur, France. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Su, YJ (reprint author), Univ Colorado, Atmospher & Space Phys Lab, 1234 Innovat Dr, Boulder, CO 80303 USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 22 TC 21 Z9 21 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 APR 1 PY 2001 VL 106 IS A4 BP 6085 EP 6095 DI 10.1029/2000JA003008 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 418MC UT WOS:000167895100044 ER PT J AU Nagy, AF Liu, YF Hansen, KC Kabin, K Gombosi, TI Combi, MR DeZeeuw, DL Powell, KG Kliore, AJ AF Nagy, AF Liu, YF Hansen, KC Kabin, K Gombosi, TI Combi, MR DeZeeuw, DL Powell, KG Kliore, AJ TI The interaction between the magnetosphere of Saturn and Titan's ionosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID 3-DIMENSIONAL MHD SIMULATION; SOLAR-WIND INTERACTION; UPPER-ATMOSPHERE; PLASMA ENVIRONMENT; VOYAGER-1; MODEL; VENUS; WAKE; PHOTOCHEMISTRY; MARS AB A three-dimensional (3-D) multi-species magnetohydrodynamic model was used to study the interaction of Titan's ionosphere and Saturn's magnetosphere. The three generic species which were considered are light (e.g., H+, H-2(+), and H-3(+)), medium (e.g., N+ and CH5+), amd heavy (e.g., N-2(+) and HCNH+) ion species. The effects of exospheric mass loading, major chemical reactions, and ion-neutral collisions were considered. The upstream parameters were selected to be the nominal values for the case when Titan is in the magnetosphere of Saturn. The simulation results are compared with Voyager measurements as well as related model calculations. The 3-D three-species model results reproduce reasonably well the global features such as magnetic barrier, magnetotail, and the distributions of the major ionospheric species. The outward escape flux of the major ionospheric species (i.e., the heavy ion species) from the tail is calculated to be approximately 6.5 x 10(24) s(-1). C1 Univ Michigan, Dept Atmospher Ocean & Space Sci, Space Phys Res Lab, Ann Arbor, MI 48109 USA. Univ Michigan, Dept Aerosp Engn, Ann Arbor, MI 48109 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Nagy, AF (reprint author), Univ Michigan, Dept Atmospher Ocean & Space Sci, Space Phys Res Lab, Ann Arbor, MI 48109 USA. RI De Zeeuw, Darren/F-3667-2011; Hansen, Kenneth/F-3693-2011; Combi, Michael/J-1697-2012; Gombosi, Tamas/G-4238-2011; OI Hansen, Kenneth/0000-0002-8502-1980; Combi, Michael/0000-0002-9805-0078; Gombosi, Tamas/0000-0001-9360-4951; Powell, Kenneth/0000-0002-3708-8814 NR 41 TC 54 Z9 54 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD APR 1 PY 2001 VL 106 IS A4 BP 6151 EP 6160 DI 10.1029/2000JA000183 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 418MC UT WOS:000167895100048 ER PT J AU Goldstein, J Denton, RE Hudson, MK Miftakhova, EG Young, SL Menietti, JD Gallagher, DL AF Goldstein, J Denton, RE Hudson, MK Miftakhova, EG Young, SL Menietti, JD Gallagher, DL TI Latitudinal density dependence of magnetic field lines inferred from Polar plasma wave data SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETOSPHERE; IONOSPHERE; MODEL; EQUATOR; HE+ AB Using observations of the electron density n(e) based on measurement of the upper hybrid resonance frequency by the Polar spacecraft Plasma Wave Instrument, we have examined the radial density dependence along field lines in the outer plasmasphere and the near plasma trough. Our technique depends, on the fact that Polar crosses particular L values at two different points with different radial distance R. Sampled L values range from 2.5 to 6.3. In our plasmaspheric data set (n(e) greater than or equal to 100 cm(-3)) we find that, on average, n(e) is flat along field lines from the equator up to the latitudes sampled by Polar (R greater than or similar to 2 R-E) In the plasma trough data set (n(e) < 100 cm(-3)) there is, on average, a mild radial dependence n(e) R-1.7. C1 Dartmouth Coll, Dept Phys & Astron, Wilder Lab 6127, Hanover, NH 03755 USA. Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Goldstein, J (reprint author), Rice Univ, Dept Phys & Astron, MS-108,6100 Main St, Houston, TX 77005 USA. RI Young, Shawn/M-3601-2016 OI Young, Shawn/0000-0001-9592-8095 NR 27 TC 51 Z9 51 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-SPACE JI J. Geophys. Res-Space Phys. PD APR 1 PY 2001 VL 106 IS A4 BP 6195 EP 6201 DI 10.1029/2000JA000068 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 418MC UT WOS:000167895100051 ER PT J AU Rinsland, CP Goldman, A Zander, R Mahieu, E AF Rinsland, CP Goldman, A Zander, R Mahieu, E TI Enhanced tropospheric HCN columns above Kitt Peak during the 1982-1983 and 1997-1998 El Nino warm phases SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID INFRARED SPECTROSCOPIC MEASUREMENTS; ATMOSPHERIC HYDROGEN-CYANIDE; SEASONAL-VARIATIONS; CARBON-MONOXIDE; EMISSIONS; NORTHERN; GASES; FIRES; C2H6; CO AB Free tropospheric HCN columns have been derived from infrared solar spectra recorded with the National Solar Observatory Fourier transform spectrometer on Kitt Peak, Arizona (31.9 degreesN latitude, 111.6 degreesW longitude, 2.09 km altitude) between May 1978 and May 2000. The time series show up to a factor of 2.4 enhancement during the strong Fl Ninos of 1982-1983 and 1997-1998, the most intense since 1970. The observations provide confirmation that HCN is a sensitive tracer of biomass burning emissions transported to the free troposphere. No statistically significant long-term trend in the HCN-free tropospheric column has been detected over the 22-year measurement period. The results illustrate the importance of long-term spectroscopic measurements for quantifying climate and atmospheric chemistry-related atmospheric changes. Published by Elsevier Science Ltd. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Univ Denver, Dept Phys, Denver, CO 80208 USA. Univ Liege, Inst Astrophys & Geophys, Liege, Belgium. RP Rinsland, CP (reprint author), NASA, Langley Res Ctr, Mail Stop 401A,21 Langley Boulevar, Hampton, VA 23681 USA. NR 19 TC 16 Z9 16 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 APR 1 PY 2001 VL 69 IS 1 BP 3 EP 8 DI 10.1016/S0022-4073(00)00122-9 PG 6 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 406QY UT WOS:000167227700002 ER PT J AU Lewinsohn, CA Henager, CH Jones, RH Eldridge, JI AF Lewinsohn, CA Henager, CH Jones, RH Eldridge, JI TI Measuring interphase recession by fiber push-in testing SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID CERAMIC-MATRIX COMPOSITES; INTERMEDIATE TEMPERATURES; STRESS-RUPTURE; OXIDATION; CRACKING; MECHANISMS; INTERFACE; KINETICS; CFCCS AB A novel technique for measuring interphase recession in ceramic-matrix composites (CMCs) due to oxidation is described, The technique involves fiber push-in testing and analysis of the load-displacement curves. Fiber push-in tests were conducted on carbon-coated Hi-Nicalon SiC fibers in a CVI SiC matrix, where the carbon interphase had recessed due to oxidation, Estimates of interphase recession distances from analysis of fiber push-in tests are in reasonable agreement with measurements made by optical microscopy, Besides measuring the recession distance, the fiber push-in test can be used to investigate environmental effects on fiber bridging. C1 Pacific NW Natl Lab, Richland, WA 99352 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Lewinsohn, CA (reprint author), Pacific NW Natl Lab, Richland, WA 99352 USA. OI Henager, Chuck/0000-0002-8600-6803 NR 29 TC 5 Z9 5 U1 1 U2 8 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 USA SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD APR PY 2001 VL 84 IS 4 BP 866 EP 868 DI 10.1111/j.1151-2916.2001.tb00754.x PG 3 WC Materials Science, Ceramics SC Materials Science GA 421BM UT WOS:000168042300028 ER PT J AU Acree, CW Peyran, RJ Johnson, W AF Acree, CW Peyran, RJ Johnson, W TI Rotor design options for improving tiltrotor whirl-flutter stability margins SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB Rotor design changes intended to improve tiltrotor whirl-flutter stability margins were analyzed. A baseline analytical model similar to the XV-15 (23% thick wing) was established, and then a 15% thick wing was designed to be representative of a high-speed tiltrotor. While the thinner wing has lower drag, it also has lower stiffness, reducing whirl-flutter stability. The rotor blade design was modified to increase the stability speed margin for the thin-wing design. Small rearward offsets of the aerodynamic-center locus with respect to the blade elastic axis created. large increases in the stability boundary. The effect was strongest for offsets at the outboard part of the blade, where an offset of the aerodynamic center by 10% of tip chord improved the stability margin by over 100 knots. Forward offsets of the blade center of gravity had similar but less pronounced effects. Equivalent results were seen for swept-tip blades. Combinations of tip sweep, control-system stiffness, and delta-three were also investigated. A limited investigation of blade loads in helicopter and airplane configuration indicated that proper choice of parametric variations can avoid excessive increases in rotor loads. C1 NASA, Ames Res Ctr, Ames, IA USA. USA, Aeroflightdynam Directorate, Washington, DC 20310 USA. RP Acree, CW (reprint author), NASA, Ames Res Ctr, Ames, IA USA. NR 17 TC 2 Z9 3 U1 1 U2 1 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD APR PY 2001 VL 46 IS 2 BP 87 EP 95 PG 9 WC Engineering, Aerospace SC Engineering GA 466UR UT WOS:000170665000001 ER PT J AU Fulton, MV Ormiston, RA AF Fulton, MV Ormiston, RA TI Hover testing of a small-scale rotor with on-blade elevons SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article; Proceedings Paper CT 53rd Annual Forum of the American-Helicopter-Society CY APR 29-MAY 01, 1997 CL VIRGINIA BEACH, VIRGINIA SP Amer Helicopter Soc AB A two-bladed, 7.5-ft diameter dynamic rotor model with 10% chord on-blade elevons driven by piezoceramic bimorph actuators was designed and tested in hover at tip speeds up to 298 ft/s. The elevon actuator succeeded in achieving deflections of +/-5 deg at the nominal rotor speed of 760 RPM. Aeroelastic and structural dynamic response characteristics were evaluated over a wide rotor speed range using frequency sweep excitation of the elevon up to 100 Hz. The CIFER (R) post processing method was very useful for determining frequency response magnitude, phase, and coherence of measured blade root flap bending and torsion moments to elevon input, as well as elevon response to actuator input voltage. Experimental results include actuator effectiveness, effects of low Reynolds number on elevon pitching moments, elevon reversal, and variation of flap bending mode responses with rotor speed and elevon excitation. The active rotor performed satisfactorily and the results provide an encouraging basis for future wind tunnel testing that will evaluate on-blade elevon effectiveness for reducing rotor blade vibratory loads. C1 USA, Aviat & Missile Command, Ames Res Ctr,AMRDEC, NASA Rotocraft Div, Moffett Field, CA USA. RP Fulton, MV (reprint author), USA, Aviat & Missile Command, Ames Res Ctr,AMRDEC, NASA Rotocraft Div, Moffett Field, CA USA. NR 30 TC 25 Z9 26 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD APR PY 2001 VL 46 IS 2 BP 96 EP 106 PG 11 WC Engineering, Aerospace SC Engineering GA 466UR UT WOS:000170665000002 ER PT J AU Cicolani, LS McCoy, AH Sahai, R Tyson, PH Tischler, MB Rosen, A Tucker, GE AF Cicolani, LS McCoy, AH Sahai, R Tyson, PH Tischler, MB Rosen, A Tucker, GE TI Flight test identification and simulation of a UH-60A helicopter and slung load SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB Helicopter slung-load operations are common in both military and civil contexts. Helicopters and loads are often qualified for these operations by means of flight tests that can be expensive and time consuming. There is significant potential to reduce such costs both through changes in flight-test methods and by using validated simulation models. To these ends, flight tests were conducted at Moffett Field to demonstrate the identification of key dynamic parameters during flight tests (aircraft stability margins and handling-qualities parameters, and load pendulum stability), and to accumulate a data base for simulation development and validation. The test aircraft was a UH-60A Black Hawk and the primary test load was an instrumented 8- by 6- by 6-ft cargo container. Tests were focused on the lateral and longitudinal axes, which are the axes most affected by the load pendulum modes in the frequency range of interest for handling qualities; tests were conducted at airspeeds from hover to 80 knots. Using telemetered data, the key dynamic parameters were evaluated in near real time after each test airspeed, and before clearing the aircraft to the next test point. These computations were completed in under I min. A simulation model was implemented by integrating an advanced model of the UH-60A aerodynamics, dynamic equations for the two-body slung-load system with multi-cable suspension, and load static aerodynamics obtained from wind-tunnel measurements. Comparisons with flight data for the helicopter alone and with a slung load showed good overall agreement for all parameters and test points; however, unmodeled secondary dynamic losses around 10 rad/sec were found in the helicopter model and they resulted in conservative stability margin estimates. C1 USA, Ames Res Ctr, Army Rotorcraft Div,Aviat & Missile Command, NASA,Aeroflightdynam Directorate, Moffett Field, CA 94035 USA. USN, Postgrad Sch, Monterey, CA USA. Technion Israel Inst Technol, Dept Aerosp Engn, Haifa, Israel. RP Cicolani, LS (reprint author), USA, Ames Res Ctr, Army Rotorcraft Div,Aviat & Missile Command, NASA,Aeroflightdynam Directorate, Moffett Field, CA 94035 USA. NR 44 TC 4 Z9 4 U1 1 U2 2 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD APR PY 2001 VL 46 IS 2 BP 140 EP 160 PG 21 WC Engineering, Aerospace SC Engineering GA 466UR UT WOS:000170665000006 ER PT J AU Prabhakara, C Iacovazzi, R Yoo, JM AF Prabhakara, C Iacovazzi, R Yoo, JM TI TRMM observations of polarization difference in 85 GHz: Information about hydrometeors and rain rate SO JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN LA English DT Article ID RADAR MEASUREMENTS; PASSIVE MICROWAVE; COLORADO AB Observations made by the Precipitation Radar (PR) and the Microwave Imager (TMI) radiometer on board the Tropical Rainfall Measuring Mission (TRMM) satellite help us to show the significance of the 85 GHz polarization difference, PD85, measured by TMI. Rain type, convective or stratiform, deduced from the PR allows us to infer that PD85 is generally positive in stratiform rain clouds, while PD85 can be markedly negative in deep convective rain clouds. Furthermore, PD85 increases in a gross manner as stratiform rain rate increases. On the contrary, in a crude fashion PD85 decreases as convective rain rate increases. From the observations of TMI and PR, we find that PD85 is a weak indicator of rain rate. Utilizing information from existing polarimetric radar studies, we infer that negative values of PD85 are likely associated with vertically-oriented small oblate or wet hail that are found in deep convective updrafts. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Raytheon ITSS Corp, Lanham, MD USA. Ewha Womans Univ, Seoul, South Korea. RP Prabhakara, C (reprint author), NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. EM cuddapah@climate.gsfc.nasa.gov RI Iacovazzi Jr, Robert/G-3867-2010 NR 12 TC 1 Z9 1 U1 0 U2 0 PU METEOROLOGICAL SOC JAPAN PI TOKYO PA C/O JAPAN METEOROLOGICAL AGENCY 1-3-4 OTE-MACHI, CHIYODA-KU, TOKYO, 100-0004, JAPAN SN 0026-1165 EI 2186-9057 J9 J METEOROL SOC JPN JI J. Meteorol. Soc. Jpn. PD APR PY 2001 VL 79 IS 2 BP 701 EP 707 DI 10.2151/jmsj.79.701 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 438BR UT WOS:000169034300008 ER PT J AU Wang, TS AF Wang, TS TI Thermophysics characterization of kerosene combustion SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID OXIDATION; MODEL AB A one-formula surrogate fuel formulation and its quasi-global combustion kinetics model are developed to support the design of injectors and thrust chambers of kerosene-fueled rocket engines. This surrogate fuel model depicts a fuel blend that properly represents the general physical and chemical properties of kerosene. The accompanying gaseous-phase thermodynamics of the surrogate fuel is anchored with the heat of formation of kerosene and verified by comparing a series of one-dimensional rocket thrust chamber calculations. The quasi-global combustion kinetics model consists of several global steps for parent fuel decomposition, soot formation, and soot oxidation and a detailed wet-CO mechanism to complete the combustion process. The final thermophysics formulations are incorporated with a computational fluid dynamics model for prediction of the combustion efficiency of an unielement, tripropellant combustor and the radiation of a kerosene-fueled thruster plume. The model predictions agreed reasonably well with those of the tests. C1 NASA, George C Marshall Space Flight Ctr, Space Transportat Directorate, Appl Fluid Dynam Anal Grp, Huntsville, AL 35812 USA. RP Wang, TS (reprint author), NASA, George C Marshall Space Flight Ctr, Space Transportat Directorate, Appl Fluid Dynam Anal Grp, Huntsville, AL 35812 USA. NR 34 TC 35 Z9 36 U1 1 U2 15 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD APR-JUN PY 2001 VL 15 IS 2 BP 140 EP 147 DI 10.2514/2.6602 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA 424ZX UT WOS:000168264800002 ER PT J AU Sakai, T Sawada, K Mitsuda, M AF Sakai, T Sawada, K Mitsuda, M TI Application of Planck-Rosseland-Gray model for high-enthalpy arc heaters SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article; Proceedings Paper CT AIAA/ASME 7th Joint Thermophysics and Heat Transfer Conference CY JUN 15-18, 1998 CL ALBUQUERQUE, NEW MEXICO SP AIAA, ASME ID MARS AB The existing ARCFLO computer code for numerically simulating the flow in the constrictor of a constricted-arc wind tunnel is upgraded by replacing the two-band gray-gas radiation model with the Planck-Rosseland-Gray model developed recently. The code is now applicable to both air and carbon dioxide flows. For the airflows thermochemical nonequilibrium is accounted for approximately in determining the thermodynamic variables. For the carbon dioxide flows condensation of solid carbon on the wall is accounted for. Turbulence parameters are adjusted to accommodate the change in the radiation model. For airflows the present modification reproduces the existing experimental data well. For carbon dioxide flows the present code predicts operating characteristics that are similar to those for airflows and a thin carbon deposit layer on the wall. C1 Tohoku Univ, Dept Aeronaut & Space Engn, Sendai, Miyagi 9808579, Japan. Kobe Steel Ltd, Mech Engn Res Lab, Kobe, Hyogo 6512271, Japan. RP Sakai, T (reprint author), NASA, Ames Res Ctr, Reacting Flow Environm Branch, Mail Stop 230-2, Moffett Field, CA 94035 USA. NR 21 TC 9 Z9 9 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD APR-JUN PY 2001 VL 15 IS 2 BP 176 EP 183 DI 10.2514/2.6606 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA 424ZX UT WOS:000168264800006 ER PT J AU Kassemi, M Kaforey, M Matthiesen, D AF Kassemi, M Kaforey, M Matthiesen, D TI Effect of void-generated thermocapillary convection on dopant segregation in microgravity solidification SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article; Proceedings Paper CT AIAA 38th Aerospace Sciences Meeting and Exhibit CY JAN 10-15, 2000 CL RENO, NEVADA SP Amer Inst Aeronatu & Astronaut ID GALLIUM-ARSENIDE; SURFACE-TENSION AB Three recent microgravity experiments have been hampered by convection caused by unwanted voids and/or bubbles in the melt. We present a numerical study to delineate the influence of void-generated thermocapillary convection on solidification of a doped single crystal from its dilute binary melt in microgravity. A detailed numerical model for the Bridgman solidification process is developed. The finite element numerical model solves the quasisteady Navier-Stokes equations, together with the conservation equations for transport of energy and species. The complicating effects of thermocapillary convection generated by the void and solutal rejection at the melt-solid interface are included. Through a quasi-steady analysis, it is shown that the convection generated by the void can affect radial segregation drastically, especially if the thermocapillary vortex penetrates the solutal boundary layer at the growth interface. From a transport point of view, three different regimes are identified based on the distance between the void and the growth interface. These range from a diffusion-controlled regime, where most of the radial nonuniformity in the interfacial composition is due to interface curvature with minimal flow effects, to a fully mixed regime, where the penetration of the solutal boundary layer by the thermocapillary vortex tends to homogenize the interfacial compositions. C1 NASA, John H Glenn Res Ctr Lewis Field, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. Case Western Reserve Univ, Dept Mat Sci, Cleveland, OH 44106 USA. RP Kassemi, M (reprint author), NASA, John H Glenn Res Ctr Lewis Field, Natl Ctr Micrograv Res, MS 110-3,21000 Brook Pk Rd, Cleveland, OH 44135 USA. NR 13 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 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD APR-JUN PY 2001 VL 15 IS 2 BP 219 EP 227 DI 10.2514/2.6597 PG 9 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA 424ZX UT WOS:000168264800012 ER PT J AU Arakere, NK Swanson, G AF Arakere, NK Swanson, G TI Fretting stresses in single crystal superalloy turbine blade attachments SO JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT STLE/ASME 2000 Tribology Conference CY OCT 01-04, 2000 CL SEATTLE, WASHINGTON SP STLE, Amer Soc Mechn Engineers DE fretting; fatigue; high cycle fatigue (HCF); single crystal; crystal orientation; nickel-base superalloy; face centered cubic (FCC); turbine blade; blade attachment ID FATIGUE; MECHANICS AB Single crystal nickel base superalloy turbine blades are being utilized in rocket engine turbopumps and turbine engines because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over polycrystalline alloys. High cycle fatigue induced failures in aircraft gas turbine and rocket engine turbopump blades is a pervasive problem. Blade attachment regions are prone to fretting fatigue failures. Single crystal nickel base superalloy turbine blades are especially prone to fretting damage because the subsurface shear stresses induced by fretting action at the attachment regions ran result in crystallographic initiation and crack growth along octahedral planes. This paper presents contact stress evaluation in the attachment region for single crystal turbine blades used in the NASA alternate advanced high pressure fuel turbo pump for the space shuttle main engine. Single crystal materials have highly anisotropic properties making the position of the crystal lattice relative to the part geometry a significant factor in the overall analysis. Blades and the attachment region are modeled using a large-scale three-dimensional finite element model capable of accounting for contact friction, material anisotropy, and variation in primary and secondary crystal orientation. Contact stress analysis in the blade attachment regions is presented as a function of coefficient of friction and primary and secondary crystal orientation, Fretting stresses at the attachment region are seen to vary significantly as a function of crystal orientation. The stress variation as a function of crystal orientation is a direct consequence of the elastic anisotropy of the material. Fatigue life calculations and fatigue failures are discussed for the airfoil and the blade attachment regions. C1 Univ Florida, Dept Mech Engn, Gainesville, FL 32611 USA. NASA, George C Marshall Space Flight Ctr, Strength Anal Grp ED22, Huntsville, AL 35812 USA. RP Arakere, NK (reprint author), Univ Florida, Dept Mech Engn, Gainesville, FL 32611 USA. NR 29 TC 12 Z9 14 U1 2 U2 14 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0742-4787 J9 J TRIBOL-T ASME JI J. Tribol.-Trans. ASME PD APR PY 2001 VL 123 IS 2 BP 413 EP 423 DI 10.1115/1.1308032 PG 11 WC Engineering, Mechanical SC Engineering GA 426HM UT WOS:000168343800026 ER PT J AU Volino, RJ Hultgren, LS AF Volino, RJ Hultgren, LS TI Measurements in separated and transitional boundary layers under low-pressure turbine airfoil conditions SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 45th International Gas Turbine and Aeroengine Congress and Exhibition CY MAY 08-11, 2000 CL MUNICH, GERMANY ID FREE-STREAM TURBULENCE; FLOW; CURVATURE; GRADIENT; MODEL AB Derailed velocity measurements were made along a flat plate subject to the same dimensionless pressure gradient as the suction side of a modern low-pressure turbine airfoil. Reynolds numbers based on wetted plate length and nominal exit velocity were varied from 50,000 to 300,000, covering cruise to takeoff conditions. Low and high inlet free-stream turbulence intensities (0.2 and 7 percent) were set using passive grids. The location of boundary-layer separation does not depend strongly on the free-stream turbulence level of Reynolds number, as long as the boundary layer remains nonturbulent prior to separation. Strong acceleration prevents transition on the upstream part of the plate in all cases. Both free-stream turbulence and Reynolds number have strong effects on transition in the adverse pressure gradient region. Under low free-stream turbulence conditions, transition is induced by instability waves in the shear layer of the separation bubble. Reattachment generally occurs at the transition start. At Re = 50,000 the separation bubble does not close before the trailing edge of the modeled airfoil. Ar higher Re, transition moves upstream, and the boundary, layer reattaches. With high free-stream turbulence levels, transition appears to occur in a bypass mode, similar to that in attached boundary layers. Transition moves upstream, resulting in shorter separation regions. At Be above 200,000 transition begins before separation. Mean velocity, turbulence, and intermittency profiles are presented. C1 USN Acad, Dept Mech Engn, Annapolis, MD 21402 USA. NASA, Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. RP Volino, RJ (reprint author), USN Acad, Dept Mech Engn, Annapolis, MD 21402 USA. EM volino@usna.edu; hultgren@grc.nasa.gov RI Volino, Ralph/G-9293-2011 NR 32 TC 65 Z9 67 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD APR PY 2001 VL 123 IS 2 BP 189 EP 197 DI 10.1115/1.1350408 PG 9 WC Engineering, Mechanical SC Engineering GA 439XG UT WOS:000169142400002 ER PT J AU Heidmann, JD Lucci, BL AF Heidmann, JD Lucci, BL TI An experimental study of the effect of wake passing on turbine blade film cooling SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 42nd International Gas Turbine and Aeroengine Congress and Exhibition CY JUN 02-05, 1997 CL ORLANDO, FLORIDA SP Int Gas Turbine Inst ID FREE-STREAM TURBULENCE; HEAT-TRANSFER; UNSTEADY WAKE; INJECTION; FLOW; DISTRIBUTIONS; CASCADE; AIR AB The effect of wake passing on the showerhead film cooling performance of a turbine blade has been investigated experimentally. The experiments were performed in an annular turbine cascade with art upstream rotating row of cylindrical rods. Nickel thin-film gauges were used to determine local film effectiveness and Nusselt number values for various injectants, blowing ratios, and Strouhal numbers. Results indicated a reduction in film effectiveness with increasing Strouhal number as well as the expected increase in film effectiveness with blowing ratio. A,I equation was developed to correlate the span-average film effective ness darn. The primary effect of wake unsteadiness was found to be correlated by a streamwise-constant decrement of 0.094St. Steady computations were found to be in excellent agreement with experimental Nusselt numbers, but to overpredict experimental film effectiveness value. This is likely du to the inability to match actual hole exit velocity profiles and the absence of a credible turbulence model for film cooling. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Case Western Reserve Univ, Dept Mech & Aerosp Engn, Cleveland, OH 44106 USA. RP Heidmann, JD (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 33 TC 22 Z9 22 U1 0 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD APR PY 2001 VL 123 IS 2 BP 214 EP 221 DI 10.1115/1.1354621 PG 8 WC Engineering, Mechanical SC Engineering GA 439XG UT WOS:000169142400005 ER PT J AU Slater, JW Paynter, GC AF Slater, JW Paynter, GC TI Implementation of a compressor face boundary condition based on small disturbances SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 45th International Gas Turbine and Aeroengine Congress and Exhibition CY MAY 08-11, 2000 CL MUNICH, GERMANY AB A compressor-face boundary condition that models the unsteady interactions of acoustic and convective velocity disturbances with a compressor has been implemented into a three-dimensional computational fluid dynamics code. Locally one-dimensional characteristics along with a small-disturbance model are used to compute the acoustic response as a function of the local stagger angle and the strength and direction of the disturbance. Simulations of the inviscid flow in a straight duct, a duct coupled to a compressor, and a supersonic inlet demonstrate the behavior of the boundary condition in relation to existing boundary conditions. Comparisons with experimental data show a large improvement in accuracy over existing boundary conditions in the ability to pi-edict the reflected disturbance from the interaction of an acoustic disturbance with a compressor. C1 John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. Boeing Co, Seattle, WA 98124 USA. RP Slater, JW (reprint author), John H Glenn Res Ctr Lewis Field, MS 86-7,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 11 TC 1 Z9 1 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD APR PY 2001 VL 123 IS 2 BP 386 EP 391 DI 10.1115/1.1344884 PG 6 WC Engineering, Mechanical SC Engineering GA 439XG UT WOS:000169142400025 ER PT J AU Wernet, MP Bright, MM AF Wernet, MP Bright, MM TI An investigation of surge in a high-speed centrifugal compressor using digital PIV SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article ID PARTICLE IMAGE VELOCIMETRY AB Compressor stall is a catastrophic breakdown of the flow in a compressor, which can lead to a lass of engine power, large pressure transients in the inlet/nacelle, and engine flameout. The implementation of active or passive strategies for controlling rotating stall and surge cart significantly extend the stable operating range of a compressor without substantially sacrificing performance. It is crucial to identify rite dynamic changes occurring irt the flow field prior to rotating stall and surge in order to control these events successfully. Generally, pressure transducer measurements are made to capture the transient response of a compressor prior to rotating stall. In this investigation, Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to capture transient velocity and pressure measurements simultaneously in the nonstationary flow field daring compressor surge. DPIV is an instantaneous, planar measurement technique that is ideally suited for studying transient flow phenomena in high-speed turbomachinery and has been used previously to map the stable operating point flow field in the diffuser of a high-speed centrifugal compressor. Through the acquisition of both DPN images and transient pressure data, the time evolution of the unsteady flow during surge is revealed. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. USA, Vehicle Technol Directorate, Glenn Res Ctr, Res Lab, Cleveland, OH 44135 USA. RP Wernet, MP (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 18 TC 31 Z9 31 U1 0 U2 18 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD APR PY 2001 VL 123 IS 2 BP 418 EP 428 DI 10.1115/1.1343465 PG 11 WC Engineering, Mechanical SC Engineering GA 439XG UT WOS:000169142400029 ER PT J AU Daidzic, NE Alexander, JID Camardo, CA AF Daidzic, NE Alexander, JID Camardo, CA TI Some aspects of the fluid flow in a porous media in the microgravity conditions for the space plant production systems SO MAGNETIC RESONANCE IMAGING LA English DT Editorial Material C1 NASA, John H Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, NCMRfc, Cleveland, OH 44135 USA. RP Daidzic, NE (reprint author), NASA, John H Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, NCMRfc, 2100 Brookpk Rd,Mail Stop 110-3, Cleveland, OH 44135 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0730-725X J9 MAGN RESON IMAGING JI Magn. Reson. Imaging PD APR-MAY PY 2001 VL 19 IS 3-4 BP 593 EP 593 DI 10.1016/S0730-725X(01)00367-8 PG 1 WC Radiology, Nuclear Medicine & Medical Imaging SC Radiology, Nuclear Medicine & Medical Imaging GA 455YU UT WOS:000170056000062 PM 11486789 ER PT J AU Roth, DJ Kautz, HE Abel, PB Whalen, MF Hendricks, JL Bodis, JR AF Roth, DJ Kautz, HE Abel, PB Whalen, MF Hendricks, JL Bodis, JR TI Three dimensional surface depression profiling using focused air coupled ultrasonic pulses SO MATERIALS EVALUATION LA English DT Article DE surface profiling; ultrasonics; ultrasonic imaging; air coupling AB Surface topography is an important variable in the performance of many industrial components and is normally measured with diamond tip profilometry over a small area or by using optical scattering methods for larger area measurement. This article shows quantitative surface topography profiles as obtained using 1 MHz focused air coupled ultrasonic pulses. The profiles were obtained using a system developed by NASA Glenn Research Center and Sonix, Inc., via a formal cooperative agreement. The method is simple and reproducible because it relies mainly on knowledge and constancy of the sound velocity through the air. The air transducer is scanned across the surface and sends pulses to the sample surface where they are reflected back from the surface along the same path as the incident wave. Time of flight images of the sample surface are acquired and converted to depth/surface profile images using the simple relation (d = V x t/2) between distance d, time of flight t and the velocity of sound in air V. In this article, resolution is determined and results are shown for platelike and cylindrical (curved) samples. Impressive results were obtained for all samples when compared with diamond tip profiles and measurements from micro thickness gages. The method is completely nondestructive, noninvasive, noncontact and does not require light reflective surfaces. C1 NASA Headquarters, Washington, DC 20546 USA. Sonix Inc, Springfield, VA 22152 USA. Cleveland State Univ, Cleveland, OH 44115 USA. RP Roth, DJ (reprint author), NASA Headquarters, Code Ug,Room 8034,300 E St SW, Washington, DC 20546 USA. NR 7 TC 7 Z9 7 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 APR PY 2001 VL 59 IS 4 BP 543 EP 548 PG 6 WC Materials Science, Characterization & Testing SC Materials Science GA 418BM UT WOS:000167869900012 ER PT J AU Meyers, JF Lee, JW Schwartz, RJ AF Meyers, JF Lee, JW Schwartz, RJ TI Characterization of measurement error sources in Doppler global velocimetry SO MEASUREMENT SCIENCE AND TECHNOLOGY LA English DT Article DE Doppler global velocimetry; optical measurement techniques; lasers; aerodynamic measurements; wind tunnel testing ID HIGH-SPEED FLOWS AB Doppler global velocimetry uses the absorption characteristics of iodine vapour to provide instantaneous three-component measurements of flow velocity within a plane defined by a laser light sheet. Although the technology is straightforward, its utilization as a flow diagnostics tool requires hardening of the optical system and careful attention to detail during data acquisition and processing if routine use in wind tunnel applications is to be achieved. A development programme that reaches these goals is presented. Theoretical and experimental investigations were conducted on each technology element to determine methods that increase measurement accuracy and repeatability. Enhancements resulting from these investigations included methods to ensure iodine vapour calibration stability, single frequency operation of the laser and image alignment to sub-pixel accuracies. Methods were also developed to improve system calibration, and eliminate spatial variations of optical frequency in the laser output, spatial variations in optical transmissivity and perspective and optical distortions in the data images. Each of these enhancements is described and experimental examples given to illustrate the improved measurement performance obtained by the enhancement. The culmination of this investigation was the measured velocity profile of a rotating wheel resulting in a 1.75% error in the mean with a standard deviation of 0.5 m s(-1). Comparing measurements of a jet flow with corresponding Pitot measurements validated the use of these methods for flow field applications. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. FDC, NYMA Inc, Langley Res Ctr, Hampton, VA 23681 USA. RP NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 31 TC 28 Z9 29 U1 0 U2 0 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 APR PY 2001 VL 12 IS 4 BP 357 EP 368 DI 10.1088/0957-0233/12/4/301 PG 12 WC Engineering, Multidisciplinary; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 425KV UT WOS:000168290500003 ER PT J AU Reinath, MS AF Reinath, MS TI Doppler global velocimeter development for large wind tunnels SO MEASUREMENT SCIENCE AND TECHNOLOGY LA English DT Article DE Doppler global velocimetry; planar Doppler velocimetry; optical measurement techniques; photogrammetry; aerodynamic measurements; wind tunnel testing AB An optical, laser-based flow-field measurement technique for large wind tunnels is described. The technique, Doppler global velocimetry (DGV), uses laser sheet illumination and digital imaging to rapidly measure velocity distributions over large planar regions of the flow. DGV measures the Doppler shift of laser light scattered by aerosol particles that are added to the flow. An optical filter cell containing iodine vapour functions as a sensitive frequency discriminator that converts Doppler frequency to image intensity. The procedure used to process image intensity to yield three-component velocity maps is described. Measurement uncertainty is analysed and discussed, and sample measurements are presented. C1 NASA, Ames Res Ctr, Expt Phys Branch, Moffett Field, CA 94035 USA. RP NASA, Ames Res Ctr, Expt Phys Branch, Mail Stop 274-2, Moffett Field, CA 94035 USA. NR 12 TC 4 Z9 4 U1 1 U2 4 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 APR PY 2001 VL 12 IS 4 BP 432 EP 441 DI 10.1088/0957-0233/12/4/307 PG 10 WC Engineering, Multidisciplinary; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 425KV UT WOS:000168290500009 ER PT J AU Fichter, WB AF Fichter, WB TI Transverse stress decay in a specially orthotropic strip under localized normal edge loading SO MECHANICS OF COMPOSITE MATERIALS AND STRUCTURES LA English DT Article AB Solutions are presented for the stresses in a specially orthotropic infinite strip which is subjected to localized uniform normal loading on one edge while the other edge is either restrained against normal displacement only, or completely fixed The solutions are used to investigate the diffusion of load into the strip and in particular the decay of normal stress across the width of the strip. For orthotropic strips representative of a broad range of balanced and symmetric angle-ply composite laminates, minimum strip widths are found that ensure at least 90% decay of the normal stress across the strip. In addition, in a few cases where, on the fixed edge the peak shear stress exceeds the normal stress in magnitude, minimum strip widths that ensure 90% decay of both stresses are found. To help in putting these results into perspective, and to illustrate the influence of material properties on load diffusion in orthotropic materials, closed-form solutions for the stresses in similarly loaded orthotropic half-planes are obtained. These solutions are used to generate illustrative stress contour plots for several representative laminates. Among the laminates, those composed of intermediate-angle plies, i.e., from about 30 degrees to 60 degrees, exhibit marked changes in normal stress contour shape with stress level. The stress contours are also used to find 90% decay distances in the half-planes. In all cases, the minimum strip widths for 90% decay of the normal stress exceed the 90% decay distances in the corresponding half-planes, in amounts ranging from only a few percent to about 50% of the half-plane decay distances. The 90% decay distances depend on both material properties and the boundary conditions on the supported edge. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Fichter, WB (reprint author), 113 Pierces Court, Williamsburg, VA 23185 USA. NR 6 TC 0 Z9 0 U1 1 U2 1 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 1075-9417 J9 MECH COMPOS MATER ST JI Mech. Compos. Mater. Struct. PD APR-JUN PY 2001 VL 8 IS 2 BP 157 EP 179 DI 10.1080/10759410120544 PG 23 WC Materials Science, Multidisciplinary; Materials Science, Characterization & Testing; Materials Science, Composites SC Materials Science GA 424VR UT WOS:000168255100005 ER PT J AU Mikouchi, T Miyamoto, M McKay, GA AF Mikouchi, T Miyamoto, M McKay, GA TI Mineralogy and petrology of the Dar al Gani 476 martian meteorite: Implications for its cooling history and relationship to other shergottites SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID ELEPHANT MORAINE A79001; NOBLE-GASES; ORIGIN; CRYSTALLIZATION; PETROGENESIS; OLIVINE; EETA-79001; DIFFUSION; CHEMISTRY; PYROXENES AB Dar al Gani 476, the 13th martian meteorite, was recovered from the Sahara in 1998. It is a basaltic shergottitic rock composed of olivine megacrysts reaching 5 mm (24 vol%) set in a fine-grained groundmass of pyroxene (59 vol%) and maskelynitized plagioclase (12 vol%) with minor amounts of accessory phases (spinel, merrillite, ilmenite). Dar al Gani 476 is similar to lithology A of Elephant Moraine A79001 (EETA79001) in petrography and mineralogy, but is distinct in several aspects. Low-Ca pyroxenes in the Dar al Gani 476 groundmass are more magnesian (En(76)Fs(21) Wo(3)similar to En(58)Fs(30)Wo(12)) than those in lithology A of EETA79001 (En(73)Fs(22)Wo(5)similar to En(45)Fs(43)Wo(12)), rather similar to pyroxenes in Iherzolitic martian meteorites (En(76)Fs(21)Wo(3)similar to En(63)Fs(22)Wo(15)) Dar al Gani 476 olivine is less magnesian and shows a narrower compositional range (Fo(76-58)) than EETA79001 olivine (Fo(81-53)), and is also similar to olivines in Iherzolitic martian meteorites (Fo(74-65)). The orthopyroxene-olivine-chromite xenolith typical in the lithology A of EETA79001 is absent in Dar al Gani 476. It seems that Dar al Gani 476 crystallized from a slightly more primitive mafic magma than lithology A of EETA79001 and several phases (olivine, pyroxene, chromite, and ilmenite) in Dar al Gani 476 may have petrogenetic similarities to those of Iherzolitic martian meteorites. Olivine megacrysts in Dar al Gani 476 are in disequilibrium with the bulk composition. The presence of fractured olivine grains in which the most Mg-rich parts are in contact with the groundmass suggests that little diffusive modification of original olivine compositions occurred during cooling. This observation enabled us to estimate the cooling rates of Dar al Gani 476 and EETA79001 olivines, giving similar cooling rates of 0.03-3 degreesC/h for Dar al Gani 476 and 0.05-5 degreesC/h for EETA79001. This suggests that they were cooled near the surface (burial depth shallower than about 3 m at most), probably in lava flows during crystallization of groundmass. As is proposed for lithology A of EETA79001, it may be possible to consider that Dar al Gani 476 has an impact melt origin, a mixture of martian Iherzolite and other martian rock (Queen Alexandra Range 94201, nakhlites?). C1 Univ Tokyo, Grad Sch Sci, Dept Earth & Planetary Sci, Bunkyo Ku, Tokyo 1130033, Japan. NASA, Lyndon B Johnson Space Ctr, Planetary Sci Branch, Houston, TX 77058 USA. RP Mikouchi, T (reprint author), NASA, Lyndon B Johnson Space Ctr, Planetary Sci Branch, Mail Code SN2, Houston, TX 77058 USA. NR 52 TC 36 Z9 37 U1 0 U2 5 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD APR PY 2001 VL 36 IS 4 BP 531 EP 548 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 445FW UT WOS:000169448300007 ER PT J AU Lowman, PD AF Lowman, PD TI John A. O'Keefe (1916-2000) - Memorial SO METEORITICS & PLANETARY SCIENCE LA English DT Biographical-Item C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Lowman, PD (reprint author), NASA, Goddard Space Flight Ctr, Code 921, Greenbelt, MD 20771 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD APR PY 2001 VL 36 IS 4 BP 573 EP 574 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 445FW UT WOS:000169448300010 ER PT J AU Poulet, F Sicardy, B AF Poulet, F Sicardy, B TI Dynamical evolution of the Prometheus-Pandora system SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE celestial mechanics; planets and satellites : individual : Saturn ID RING-PLANE CROSSINGS; SATURNS F-RING; URANIAN SATELLITES; TIDAL EVOLUTION; NOVEMBER 1995; RESONANCE; HISTORY; MIRANDA; TORQUES; AUGUST AB The system of Saturn's inner satellites is saturated with many resonances. Its structure should be strongly affected by tidal forces driving the satellites through several orbit-orbit resonances. The evolution of these satellites is investigated using analytic and numerical methods. We show that the pair of satellites Prometheus and Pandora has a particularly short lifetime (<20 Myr) if the orbits of the satellites converge without capture into a resonance. The capture of Pandora into a resonance with Prometheus increases the lifetime of the couple by a few tens of Myr. However, resonances of the system are not well separated, and capture results in a chaotic motion. Secondary resonances also disrupt the resonant configurations. In all cases, the converging orbits of these two satellites result in a close encounter. The implications for the origin of Saturn's rings are discussed. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Observ Paris, DESPA, F-92195 Meudon, France. RP Poulet, F (reprint author), NASA, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. NR 42 TC 18 Z9 18 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD APR 1 PY 2001 VL 322 IS 2 BP 343 EP 355 DI 10.1046/j.1365-8711.2001.04128.x PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 421EU UT WOS:000168049800013 ER PT J AU Bonvicini, V Barbiellinia, G Boezio, M Mocchiutti, E Schiavon, P Scian, G Vacchi, A Zampa, G Zampa, N Bergstrom, D Carlson, P Francke, T Lund, J Pearce, M Hof, M Menn, W Simon, M Stephens, SA Ambriola, M Bellotti, R Cafagna, F Ciacio, F Circella, M De Marzo, C Giglietto, N Marangelli, B Mirizzi, N Spinelli, P Adriani, O Boscherini, M D'Alessandro, R Finetti, N Grandi, M Papini, P Perego, A Piccardi, S Spillantini, P Vannuccini, E Bartalucci, S Marino, L Ricci, M Spataro, B Bidoli, V Casolino, M De Pascale, MP Furano, G Morselli, A Picozza, P Sparvoli, R Barbier, LM Christian, ER Krizmanic, JF Mitchell, JW Ormes, JF Streitmatter, RE Bravar, U Stochaj, SJ Bertazzoni, S Salsano, A Bazilcvskaja, G Grigorjeva, A Mukhametshin, R Stozhokov, Y Bogomolv, E Krutkov, S Vasiljev, G Galper, AM Koldashov, SV Korotkov, MG Mikhailov, VV Moissev, AA Ozerov, JV Voronov, SA Yurkin, Y Castellini, G Gabbanini, A Taccetti, F Tesi, M Vignoli, V AF Bonvicini, V Barbiellinia, G Boezio, M Mocchiutti, E Schiavon, P Scian, G Vacchi, A Zampa, G Zampa, N Bergstrom, D Carlson, P Francke, T Lund, J Pearce, M Hof, M Menn, W Simon, M Stephens, SA Ambriola, M Bellotti, R Cafagna, F Ciacio, F Circella, M De Marzo, C Giglietto, N Marangelli, B Mirizzi, N Spinelli, P Adriani, O Boscherini, M D'Alessandro, R Finetti, N Grandi, M Papini, P Perego, A Piccardi, S Spillantini, P Vannuccini, E Bartalucci, S Marino, L Ricci, M Spataro, B Bidoli, V Casolino, M De Pascale, MP Furano, G Morselli, A Picozza, P Sparvoli, R Barbier, LM Christian, ER Krizmanic, JF Mitchell, JW Ormes, JF Streitmatter, RE Bravar, U Stochaj, SJ Bertazzoni, S Salsano, A Bazilcvskaja, G Grigorjeva, A Mukhametshin, R Stozhokov, Y Bogomolv, E Krutkov, S Vasiljev, G Galper, AM Koldashov, SV Korotkov, MG Mikhailov, VV Moissev, AA Ozerov, JV Voronov, SA Yurkin, Y Castellini, G Gabbanini, A Taccetti, F Tesi, M Vignoli, V TI The PAMELA experiment in space SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 8th Pisa Meeting on Advanced Detectors CY MAY 21-27, 2000 CL LA BIODOLA, ITALY DE satellite instrumentation; cosmic rays ID SILICON AB We provide in this paper a status report of the space experiment PAMELA. PAMELA aims primarily to measure the flux of antiparticles, namely antiprotons and positrons, in cosmic rays with unprecedented statistics over a large energy range. Tn addition, it will measure the light nuclear components of cosmic rays, investigate phenomena connected to Solar and Earth physics and it will search for cosmic ray antinuclei with sensitivity better than 10(-7) in the He/He ratio. PAMELA consists of a magnet spectrometer, a transition radiation detector, an imaging calorimeter, a time of flight system and an anticoincidence detector. The apparatus will be installed on board of the Russian satellite of the Resurs type in a polar orbit at about 680 km of altitude. The launch is foreseen for late 2002/early 2003. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Univ Trieste, INFN Sect, I-34127 Trieste, Italy. Univ Trieste, Dept Phys, I-34127 Trieste, Italy. Royal Inst Technol, KTH, Stockholm, Sweden. Univ Siegen, D-5900 Siegen, Germany. Tata Inst Fundamental Res, Bombay 400005, Maharashtra, India. Univ Bari, INFN Sect, I-70121 Bari, Italy. Univ Bari, Dept Phys, Bari, Italy. Univ Florence, Dept Phys, Florence, Italy. Univ Florence, INFN Sect, Florence, Italy. Ist Nazl Fis Nucl, Nazl Frascati Lab, I-00044 Frascati, Italy. Univ Roma Tor Vergata, INFN Sect, Rome, Italy. Univ Roma Tor Vergata, Dept Phys, Rome, Italy. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. New Mexico State Univ, Las Cruces, NM 88003 USA. Univ Roma Tor Vergata, Dept Elect Engn, Rome, Italy. AF Ioffe Phys Tech Inst, St Petersburg, Russia. PN Lebedev Phys Inst, Moscow, Russia. Moscow Engn & Phys Inst, Moscow, Russia. CNR, Ist Ric Onde Elettromagnet, I-50127 Florence, Italy. RP Bonvicini, V (reprint author), Univ Trieste, INFN Sect, Via A Valerio 2, I-34127 Trieste, Italy. RI Christian, Eric/D-4974-2012; Morselli, Aldo/G-6769-2011; giglietto, nicola/I-8951-2012; Cafagna, Francesco/A-9299-2010; D'Alessandro, Raffaello/F-5897-2015; Galper, Arkady/M-9610-2015; Voronov, Sergey/P-9654-2016; Mocchiutti, Emiliano/I-8049-2013; Mikhailov, Vladimir/B-5368-2014; Krutkov, Sergey/E-7561-2014; Vasilyev, Gennady/E-4843-2014; Vacchi, Andrea/C-1291-2010; OI Christian, Eric/0000-0003-2134-3937; Morselli, Aldo/0000-0002-7704-9553; giglietto, nicola/0000-0002-9021-2888; Cafagna, Francesco/0000-0002-7450-4784; D'Alessandro, Raffaello/0000-0001-7997-0306; Voronov, Sergey/0000-0002-9209-0618; Taccetti, Francesco/0000-0003-2657-2990; Mocchiutti, Emiliano/0000-0001-7856-551X; Mikhailov, Vladimir/0000-0003-3851-2901; Vacchi, Andrea/0000-0003-3855-5856; 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; Vignoli, Valerio/0000-0003-2509-6566; Papini, Paolo/0000-0003-4718-2895; Boezio, Mirko/0000-0002-8015-2981 NR 7 TC 27 Z9 27 U1 1 U2 7 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 APR 1 PY 2001 VL 461 IS 1-3 BP 262 EP 268 DI 10.1016/S0168-9002(00)01221-3 PG 7 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 430HE UT WOS:000168567800068 ER PT J AU Barbiellini, G Bartalucci, S Bellotti, R Bergstrom, D Bidoli, V Boezio, M Bonvicini, V Bravar, U Cafagna, F Carlson, P Casolino, M Ciacio, F Circella, M De Marzo, C De Pascale, MP Finetti, N Francke, T Griastein, S Hof, M Khalchukov, F Kremer, J Menn, W Mitchell, JW Morselli, A Ormes, JF Papini, P Piccardi, S Picozza, P Ricci, M Simon, M Schiavon, P Sparvoli, R Spillantini, P Stochaj, SJ Streitmatter, RE Stephens, SA Suffert, M Vacchi, A Weber, N Zampa, N AF Barbiellini, G Bartalucci, S Bellotti, R Bergstrom, D Bidoli, V Boezio, M Bonvicini, V Bravar, U Cafagna, F Carlson, P Casolino, M Ciacio, F Circella, M De Marzo, C De Pascale, MP Finetti, N Francke, T Griastein, S Hof, M Khalchukov, F Kremer, J Menn, W Mitchell, JW Morselli, A Ormes, JF Papini, P Piccardi, S Picozza, P Ricci, M Simon, M Schiavon, P Sparvoli, R Spillantini, P Stochaj, SJ Streitmatter, RE Stephens, SA Suffert, M Vacchi, A Weber, N Zampa, N TI CAPRICE98: a balloon-borne magnetic spectrometer equipped with a gas RICH and a silicon calorimeter to study cosmic rays SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 8th Pisa Meeting on Advanced Detectors CY MAY 21-27, 2000 CL LA BIODOLA, ITALY DE balloon instrumentation; cosmic rays AB CAPRICE98 is a superconducting magnetic spectrometer, equipped with a gas RICH and a silicon calorimeter, launched from FI. Sumner (USA), on the 28th of May 1998, by the WiZard collaboration. For the first time a gas RICH detector flew together with a silicon electromagnetic calorimeter, allowing mass resolved antiprotons, with E > 18 GeV, to be detected. The detector configuration was completed by a time of flight For particle identification, and a set of three drift chambers for rigidity measurement. The science objectives are the study of antimatter in cosmic rays and the cosmic ray composition in the atmosphere with special focus on muons. (C) 2001 Elsevier Science B,V. All rights reserved. C1 Univ Bari, INFN Sect, I-70121 Bari, Italy. Univ Bari, Dept Phys, I-70121 Bari, Italy. Univ Trieste, INFN Sect, Trieste, Italy. Univ Trieste, Dept Phys, I-34127 Trieste, Italy. Ist Nazl Fis Nucl, Nazl Frascati Lab, I-00044 Frascati, Italy. Royal Inst Technol, Stockholm, Sweden. Univ Roma Tor Vergata, INFN Sect, Rome, Italy. Univ Roma Tor Vergata, Dept Phys, Rome, Italy. NMSU, RL Golden Particle Astrophys Lab, Las Cruces, NM USA. Univ Florence, INFN Sect, Florence, Italy. Univ Florence, Dept Phys, Florence, Italy. Univ Siegen, D-5900 Siegen, Germany. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Inst Fundamental Res, Bombay, Maharashtra, India. Ctr Rech Nucl, Strasbourg, France. RP Bonvicini, V (reprint author), Univ Bari, INFN Sect, I-70121 Bari, Italy. RI Vacchi, Andrea/C-1291-2010; Morselli, Aldo/G-6769-2011; Cafagna, Francesco/A-9299-2010 OI Vacchi, Andrea/0000-0003-3855-5856; Bellotti, Roberto/0000-0003-3198-2708; casolino, marco/0000-0001-6067-5104; Sparvoli, Roberta/0000-0002-6314-6117; Picozza, Piergiorgio/0000-0002-7986-3321; Papini, Paolo/0000-0003-4718-2895; Boezio, Mirko/0000-0002-8015-2981; Morselli, Aldo/0000-0002-7704-9553; Cafagna, Francesco/0000-0002-7450-4784 NR 4 TC 2 Z9 2 U1 1 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 APR 1 PY 2001 VL 461 IS 1-3 BP 269 EP 271 DI 10.1016/S0168-9002(00)01222-5 PG 3 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 430HE UT WOS:000168567800069 ER PT J AU Chaturvedi, U Favara, A Gataullin, M Gratta, G Kirkby, D Lu, W Newman, H Shvorob, A Tully, C Zhu, R AF Chaturvedi, U Favara, A Gataullin, M Gratta, G Kirkby, D Lu, W Newman, H Shvorob, A Tully, C Zhu, R TI Calibration of the L3 BGO calorimeter using an RFQ accelerator SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 8th Pisa Meeting on Advanced Detectors CY MAY 21-27, 2000 CL LA BIODOLA, ITALY DE calibration; BGO calorimeter AB An improved calibration technique based on a radio-frequency-quadrupole (RFQ) accelerator is presented. A high-intensity flux of 17.6 MeV photons, produced by radiative capture of 1.85 MeV protons from the RFQ in a lithium target, is used to calibrate in situ 11000 crystals of the L3 EGO calorimeter. We present results obtained for the calibration of 1997-1999 L3 data samples. For the first time a calibration precision better than 0.5% is reached for the entire EGO calorimeter. The importance of such a technique is also outlined in view of extensive use of crystal calorimetry at the LHC. (C) 2001 Elsevier Science B.V. All rights reserved. C1 CERN, Div EP, CH-1211 Geneva 23, Switzerland. Princeton Univ, Dept Phys, Princeton, NJ 08544 USA. Jet Prop Lab, Pasadena, CA 91109 USA. Stanford Univ, Stanford, CA 94305 USA. CALTECH, Dept Phys, Pasadena, CA 91125 USA. RP CERN, Div EP, CH-1211 Geneva 23, Switzerland. EM alvise.favara@cern.ch NR 3 TC 6 Z9 6 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 EI 1872-9576 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD APR 1 PY 2001 VL 461 IS 1-3 BP 376 EP 377 DI 10.1016/S0168-9002(00)01248-1 PG 2 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 430HE UT WOS:000168567800099 ER PT J AU Koch, GJ Cook, AL Fitzgerald, CM Dharamsi, AN AF Koch, GJ Cook, AL Fitzgerald, CM Dharamsi, AN TI Frequency stabilization of a diode laser to absorption lines of water vapor in the 944-nm wavelength region SO OPTICAL ENGINEERING LA English DT Article DE frequency stabilization; modulation spectroscopy; lidar; DIAL ID MODULATION SPECTROSCOPY; ND AB The frequency of an external-cavity diode laser has been stabilized to absorption lines of water vapor at wavelengths around 944 nm. The primary application of this stabilized laser is to provide a frequency reference for differential absorption lidar measurements of atmospheric water vapor. A wavelength modulation technique is used to provide derivative-like error signals for a control loop to continuously tune the laser to line center. The design of the stabilization scheme is provided including the optical layout and feedback loop. Spectroscopic data are presented on several different absorption lines, showing the derivative-like signals used for stabilization. Results of the stabilization show the laser frequency locked to within 10 MHz of absorption line center, well within the precision needed for lidar applications. (C) 2001 Society of Photo-Optical Instrumentation Engineers. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Old Dominion Univ, Dept Elect & Comp Engn, Norfolk, VA 23529 USA. RP Koch, GJ (reprint author), NASA, Langley Res Ctr, MS 474, Hampton, VA 23681 USA. NR 12 TC 11 Z9 12 U1 1 U2 2 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 APR PY 2001 VL 40 IS 4 BP 525 EP 528 DI 10.1117/1.1354628 PG 4 WC Optics SC Optics GA 423BQ UT WOS:000168155900006 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 On the effectiveness of a message-driven confidence-driven protocol for guarded software upgrading SO PERFORMANCE EVALUATION LA English DT Article; Proceedings Paper CT 11th International Conference on Modelling Tools and Techniques for Computer and Communication System Performance Evaluation (Tools 2000) CY MAR, 2000 CL SCHAUMBURG, IL SP ACM Sigmetr, IEEE Comp Soc Techn Comm Fault Tolerant Comp, IFIP Working Grp, Performance Com Syst, IFIP Working Grp, Comp Syst Modelling, IFIP Working Grp, Depend Comp & Fault Tolerance, L&S Comp Technol, RWTH Aachen, Dept Comp Sci DE guarded software upgrading; inherent resource redundancy; error containment and recovery; checkpointing; stochastic activity networks; reliability improvement; model-based evaluation ID SYSTEMS; ARCHITECTURE; DESIGN AB A methodology called guarded software upgrading (GSU) is proposed to accomplish dependable onboard evolution for long-life deep-space missions. The core of the methodology is a low-cost error containment and recovery protocol that escorts an upgraded software component through onboard validation and guarded operation, mitigating the effect of residual faults in the upgraded component. The message-driven confidence-driven (MDCD) nature of the protocol eliminates the need for costly process coordination or atomic action, yet guarantees that the system will reach a consistent global state upon the completion of the rollback or roll-forward actions carried out by individual processes during error recovery. To validate the ability of the MDCD protocol to enhance system reliability when a software component undergoes onboard upgrading in a realistic, non-ideal environment, we conduct a stochastic activity network model-based analysis. The results confirm the effectiveness of the protocol as originally surmised. Moreover, a comparative study reveals that the dynamic confidence-driven approach is superior to static approaches and is the key to the attainment of cost-effectiveness. (C) 2001 Elsevier Science B.V. All rights reserved. C1 IA Tech Inc, Los Angeles, CA 90024 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Illinois, ECE Dept, Urbana, IL 61801 USA. RP Tai, AT (reprint author), IA Tech Inc, 10501 Kinnard Ave, Los Angeles, CA 90024 USA. EM a.t.tai@ieee.org NR 19 TC 7 Z9 7 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0166-5316 EI 1872-745X J9 PERFORM EVALUATION JI Perform. Eval. PD APR PY 2001 VL 44 IS 1-4 BP 211 EP 236 DI 10.1016/S0166-5316(00)00054-7 PG 26 WC Computer Science, Hardware & Architecture; Computer Science, Theory & Methods SC Computer Science GA 414YT UT WOS:000167694300011 ER PT J AU Hinkel, KM Doolittle, JA Bockheim, JG Nelson, FE Paetzold, R Kimble, JM Travis, R AF Hinkel, KM Doolittle, JA Bockheim, JG Nelson, FE Paetzold, R Kimble, JM Travis, R TI Detection of subsurface permafrost features with ground-penetrating radar, Barrow, Alaska SO PERMAFROST AND PERIGLACIAL PROCESSES LA English DT Article DE active layer; Alaska; frozen ground; geophysical techniques; ground-penetrating radar; permafrost ID ACTIVE-LAYER THICKNESS; TUNDRA; USA AB A ground-penetrating radar (GPR) survey was conducted in May 1999 on the 1 km(2) Circumpolar Active Layer Monitoring (CALM) grid 5km east of Barrow, Alaska. Spatially continuous measurements were collected along established transects while the active layer remained frozen. The primary objectives were to determine the 'long-term' position of the permafrost table, to recognize ice wedges and ice lenses, and to locate the organic-mineral soil interface. GPR signal and core collection were performed in tandem to verify signal interpretation, to calibrate the instrument, and to determine optimal GPR data-collection parameters. Two-way travel times from the antenna to subsurface reflectors were compared with measured depths obtained from soil cores to estimate an average pulse propagation velocity of 0.13 m/ns through the frozen soil. The most conspicuous subsurface reflectors were ice wedges, which gave high-amplitude hyperbolic reflections. Owing to its higher ice content, the approximate long-term position of the permafrost table could be traced laterally across the profile. Radar interpretations were obscured by the effects of cryoturbation, and because some horizons lack sufficient contrast in electrical properties. Highly detailed information can be obtained by collecting radar data at relatively slow speeds of advance, by using faster scanning rates (> 32 scans/s), and by employing high-frequency antennas (> 400 MHz). Copyright (C) 2001 John Wiley & Sons, Ltd. C1 Univ Cincinnati, Dept Geog, Cincinnati, OH 45221 USA. USDA, NRCS, Newtown Sq, PA 19073 USA. Univ Wisconsin, Dept Soil Sci, Madison, WI 53706 USA. Univ Delaware, Dept Geog, Newark, DE 19716 USA. USDA, NRCS, NSSC, Lincoln, NE 68508 USA. NASA, Stennis Space Ctr, MS 39529 USA. RP Hinkel, KM (reprint author), Univ Cincinnati, Dept Geog, Cincinnati, OH 45221 USA. NR 49 TC 75 Z9 76 U1 3 U2 16 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 1045-6740 J9 PERMAFROST PERIGLAC JI Permafrost Periglacial Process. PD APR-JUN PY 2001 VL 12 IS 2 BP 179 EP 190 DI 10.1002/ppp.369 PG 14 WC Geography, Physical; Geology SC Physical Geography; Geology GA 447JD UT WOS:000169567400003 ER PT J AU Ryan, R Kuper, P Stanley, T Mondello, C AF Ryan, R Kuper, P Stanley, T Mondello, C TI The ASPRS digital imagery product guideline project SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Editorial Material C1 John C Stennis Space Ctr, NASA, Commercial Remote Sensing Program Off, Stennis Space Ctr, MS USA. Earth Data Inc, Rochester, NY USA. NR 1 TC 0 Z9 0 U1 0 U2 0 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 APR PY 2001 VL 67 IS 4 BP 421 EP + PG 2 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA 418GP UT WOS:000167882800002 ER PT J AU Menges, CH Hill, GJE Ahmad, W van Zyl, JJ AF Menges, CH Hill, GJE Ahmad, W van Zyl, JJ TI Incidence angle correction of AirSAR data to facilitate land-cover classification SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article ID RADAR BACKSCATTER; SOIL-MOISTURE; BOREAL FORESTS; PINE STANDS; SAR IMAGES; BARE SOIL; BIOMASS; MODEL; VEGETATION AB Three image-based methods for correcting the effect of changes in incidence angle on backscatter data are proposed and evaluated for AirSAR data of a coastal tropical savanna landscape in Australia's Northern Territory. These correction methods require little field knowledge and do not assume a linear relationship between SAR backscatter and incidence angle. The correction methods are applied to five independent components of the Stokes Matrix. The results are evaluated using an existing land-cover classification to extract mean backscatter values for individual land-cover classes before and after the correction procedures. It is shown, for the vegetation communities involved, that the slope method provides a successful correction for the amplitude components of the backscatter data. The real and imaginary parts of the co-polarized returns are best corrected using the LUT method. The proposed correction procedure allowed the use of a maximum-likelihood classification for the discrimination of ten land-cover types with an overall accuracy of 87 percent across the complete swath width of the AirSAR data. C1 No Terr Univ, Fac Sci, Darwin, NT 0909, Australia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Menges, CH (reprint author), No Terr Univ, Fac Sci, Darwin, NT 0909, Australia. NR 37 TC 9 Z9 10 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 APR PY 2001 VL 67 IS 4 BP 479 EP 489 PG 11 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA 418GP UT WOS:000167882800009 ER PT J AU Lozano, JA Niimura, M Smith, SJ Chutjian, A Tayal, SS AF Lozano, JA Niimura, M Smith, SJ Chutjian, A Tayal, SS TI Experimental and theoretical cross sections for electron-impact excitation of the 2s -> 2p transition in O5+ SO PHYSICAL REVIEW A LA English DT Article ID SPECTRUM; SOLAR; SUMER; C3+ AB Experimental and R-matrix calculated cross sections are reported for the resonance 2s-->2p transition in O5+. Use is made in the measurements of the electron-energy-loss technique, with center-of-mass interaction energies in the range 10.5 (below threshold) through 12.0 (threshold) to 17.0 eV. The present results are in good agreement with calculations using the R matrix with pseudostates theory, which includes nine physical states and 18 pseudostates. They are also in good agreement with near-threshold data of Bell et al. [Phys. Rev. A 49, 4585 (1994)], and with a 41-state calculation of Griffin et al. C1 Univ Connecticut, Dept Phys, Storrs, CT 06269 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Clark Atlanta Univ, Dept Phys, Atlanta, GA 30314 USA. RP Univ Connecticut, Dept Phys, Storrs, CT 06269 USA. NR 17 TC 10 Z9 10 U1 0 U2 0 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 APR PY 2001 VL 63 IS 4 AR 042713 DI 10.1103/PhysRevA.63.042713 PG 4 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 422AG UT WOS:000168095300066 ER PT J AU Beacom, JF Boyd, RN Mezzacappa, A AF Beacom, JF Boyd, RN Mezzacappa, A TI Black hole formation in core-collapse supernovae and time-of-flight measurements of the neutrino masses SO PHYSICAL REVIEW D LA English DT Review ID HADRONIC PHASE-TRANSITIONS; TRITIUM BETA-SPECTRUM; X-RAY BINARIES; UPPER LIMIT; GALACTIC SUPERNOVA; STELLAR COLLAPSES; DELAYED COLLAPSE; ANGULAR-DISTRIBUTION; FLAVOR OSCILLATIONS; WEIGHING NEUTRINOS AB In large stars that have exhausted their nuclear fuel, the stellar core collapses to a hot and dense proto-neutron star that cools by the radiation of neutrinos and antineutrinos of all flavors. Depending on its final mass, this may become either a neutron star or a black hole. Black hole formation may be triggered by mass accretion or a change in the high-density equation of state. We consider the possibility that black hole formation happens when the flux of neutrinos is still measurably high. If this occurs, then the neutrino signal from the supernova will be terminated abruptly (the transition takes less than or similar to0.5 ms). The properties and duration of the signal before the cutoff are important measures of both the physics and astrophysics of the cooling proto-neutron star. For the event rates expected in present and proposed detectors, the cutoff will generally appear sharp, thus allowing model-independent time-of-flight mass tests for the neutrinos after the cutoff. If black hole formation occurs relatively early, within a few (similar to1) seconds after core collapse, then the expected luminosities are of order L-BH=10(52) erg/s per flavor. In this case, the neutrino mass sensitivity can be extraordinary. For a supernova at a distance D=10 kpc, SuperKamiokande can detect a <()over bar>(e) mass down to 1.8 eV by comparing the arrival times of the high-energy and low-energy neutrinos in <()over bar>(e)+p-->e(+)+n. This test will also measure the cutoff time, and will thus allow a mass test of nu (mu) and nu (tau) relative to <()over bar>(e). Assuming that nu (mu) and nu (tau) are nearly degenerate, as suggested by the atmospheric neutrino results, masses down to about 6 eV can be probed with a proposed lead detector of mass M-D=4 kton (OMNIS). Remarkably, the neutrino mass sensitivity scales as (D/LBHMD)(1/2). Therefore, direct sensitivity to all three neutrino masses in the interesting few-eV range is realistically possible; there are no other known techniques that have this capability. C1 CALTECH, Phys Dept 161 33, Pasadena, CA 91125 USA. NASA, Fermilab Astrophys Ctr, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. Ohio State Univ, Dept Phys, Columbus, OH 43210 USA. Oak Ridge Natl Lab, Div Phys, Oak Ridge, TN 37831 USA. RP CALTECH, Phys Dept 161 33, Pasadena, CA 91125 USA. EM beacom@fnal.gov; boyd@mps.ohio-state.edu; mezz@nova.phy.ornl.gov RI Mezzacappa, Anthony/B-3163-2017; OI Mezzacappa, Anthony/0000-0001-9816-9741; Beacom, John/0000-0002-0005-2631 NR 138 TC 70 Z9 71 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2470-0010 EI 2470-0029 J9 PHYS REV D JI Phys. Rev. D PD APR 1 PY 2001 VL 63 IS 7 AR 073011 DI 10.1103/PhysRevD.63.073011 PG 16 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 416QT UT WOS:000167792200018 ER PT J AU Tangeman, J Xirouchakis, D AF Tangeman, J Xirouchakis, D TI High-temperature heat capacity and thermodynamic properties for end-member titanite (CaTiSiO5) SO PHYSICS AND CHEMISTRY OF MINERALS LA English DT Article DE titanite; heat capacity; enthalpy; entropy; lambda transition ID PRESSURE PHASE-TRANSITION; SYSTEM NA2O-K2O-CAO-MGO-FEO-FE2O3-AL2O3-SIO2-TIO2-H2O-CO2; SPHENE; CATIOSIO4; MINERALS; QUARTZ; EQUILIBRIA; ILMENITE; CRYSTALS; OLIVINE AB The heat capacity of end-member titanite and (CaTiSiO5) glass has been measured in the range 328-938 K using differential scanning calorimetry. The data show a weak lambda -shaped anomaly at 483 +/- 5 K, presumably associated with the well-known low-pressure P2(1)/a <----> A2/a transition, in good agreement with previous studies. A value of 0.196 +/- 0.007 kJ mol(-1) for the enthalpy of the P2(1)/a <----> A2/a transition was determined by integration of the area under the curve for a temperature interval of 438-528 K, bracketing the anomaly. The heat capacity data for end-member titanite and (CaTiSiO5) glass can be reproduced within <1% using the derived empirical equations (temperature in K, pressure in bars): C-p(glass) = 114.7155 x 10(6)/T-3+-908.3 x 10(-3)/T-2 +0.3170 x 10(5)/T+-0.8484 x 10(4)/rootT +0.5796 x 10(3) + (-21.75) X 10(-2) T +7.8731 x 10(-5) T-2 C-p(solid) = -2.3952 x 10(6)/T3+-5.8601 x 10(-3)/T-2 +0.2230 x 10(5)/T+-0.5913 x 10(4)/rootT +0.4277 x 10(3) + (-7.772) x 10(-2) T + 1.3751 x 10(-5) T-2 +3.0877 Sigma (k=2)(1)tau (3.(2k-1))/2k - 1 for tau = T/T-transition less than or equal to 1 or 2.3034 Sigma (k=2)(1)tau (-5.(2k-1))/2k - 1 for tau = T/T-transition greater than or equal to 1 C1 Univ Michigan, Dept Geol Sci, Ann Arbor, MI 48109 USA. NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, Houston, TX 77058 USA. RP Tangeman, J (reprint author), Univ Calif Davis, Dept Chem Engn & Mat Sci, Thermochem Fac, Davis, CA 95616 USA. NR 50 TC 3 Z9 3 U1 2 U2 6 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0342-1791 J9 PHYS CHEM MINER JI Phys. Chem. Miner. PD APR PY 2001 VL 28 IS 3 BP 167 EP 176 DI 10.1007/s002690000124 PG 10 WC Materials Science, Multidisciplinary; Mineralogy SC Materials Science; Mineralogy GA 422GT UT WOS:000168110700003 ER PT J AU Fillingim, MO Parks, GK Chen, LJ McCarthy, M Spann, JF Lin, RP AF Fillingim, MO Parks, GK Chen, LJ McCarthy, M Spann, JF Lin, RP TI Comparison of plasma sheet dynamics during pseudobreakups and expansive aurorae SO PHYSICS OF PLASMAS LA English DT Article; Proceedings Paper CT Spring Meeting of the American-Geophysical-Union CY 2000 CL WASHINGTON, D.C. SP Amer Geophys Union ID TAIL CURRENT SHEET; FLOW BURSTS; MAGNETOTAIL AB Global auroral images and plasma sheet ion distributions and magnetic field data are examined for two intervals when the Ultraviolet Imager (UVI) onboard the Polar spacecraft was imaging the entire northern auroral oval and, at the same time, the Wind spacecraft was passing through the near-Earth plasma sheet. On 26 July 1997, UVI recorded a series of brief, localized auroral brightenings known as pseudobreakups. On 27 March 1996, UVI observed several global expansions of auroral activity. Large variations in the magnetic field were observed by the Wind magnetometer, large velocity moments were derived from Wind ion measurements, and ions were accelerated to mega-electron-volt energies during both types of activity. The plasma sheet dynamics appear very similar during these two different types of auroral activities. Closer inspection of the ion distribution functions and energy spectra indicate that the plasma sheet dynamics need to be characterized kinetically. (C) 2001 American Institute of Physics. C1 Univ Washington, Geophys Program, Seattle, WA 98195 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RP Fillingim, MO (reprint author), Univ Washington, Geophys Program, Box 351650, Seattle, WA 98195 USA. RI Chen, Li-Jen/C-2106-2012 NR 15 TC 10 Z9 10 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 1070-664X J9 PHYS PLASMAS JI Phys. Plasmas PD APR PY 2001 VL 8 IS 4 BP 1127 EP 1132 DI 10.1063/1.1355679 PG 6 WC Physics, Fluids & Plasmas SC Physics GA 413LF UT WOS:000167613100007 ER PT J AU Cabane, M Coll, P Rodier, C Israel, G Raulin, F Sternberg, R Niemann, H Mahaffy, P Jambon, A Rannou, P AF Cabane, M Coll, P Rodier, C Israel, G Raulin, F Sternberg, R Niemann, H Mahaffy, P Jambon, A Rannou, P TI In situ inorganic and organic analysis (Pyr/CD-GC/MS) of the Martian soil, on the Mars 2005 mission SO PLANETARY AND SPACE SCIENCE LA English DT Article ID GAS-CHROMATOGRAPHY; LIFE; ATMOSPHERE; REGOLITH; HUYGENS; SEARCH AB In order to obtain mineralogical information, the Mars Sample Return mission, in 2003 and 2005, will include sub-surface sampling. One expects that the effects of UV radiations and oxidizing agents are attenuated at depths corresponding to the bottom of the drilled cavity. In this case? such sampling will also allow to determine if life is or has been present at the surface of Mars. We propose to perform a preliminary in situ analysis of Martian samples: SAM (Sample Analysis on Mars) on MSR 2005 lander. Such an analysis, performed on some parts of dedicated samples, will have the advantage of producing a ground-truth for the Earth-based analysis. Indeed, IL ISR 2003:2005 samples will be delivered to Earth laboratories in 2008, or 2009, depending on the duration of the quarantine, and it is not stated that some of their properties will remain unaltered during these three to 6 years. Moreover, there is a possibility that Martian sub-surface drilling delivers redundant samples: SAM could help to select, amongst the samples, which ones deserve to be sent to Earth, and, should the occasion arise, what are their unexpected peculiarities. To analyze inorganics and organics sampled at various depths, we propose to use the pyrolysis;chemical derivatization/gas chromatography:'mass spectrometry technique. This experiment may be performed using techniques already developed in the frame of other planetary (ACP/HUYGENS) or cometary (COSAC/ROSETTA) missions, which can easily be adapted to the proposed mission objective, according to the three following topics: search for organics, starch for inorganics and isotope characterization. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Univ Paris 06, CNRS, Serv Aeron, IPSL,UMR 7620, F-75005 Paris, France. Univ Paris 07, UMR 7583, Lab Interuniv Syst Atmospher, F-94010 Creteil, France. Univ Paris 12, UMR 7583, Lab Interuniv Syst Atmospher, F-94010 Creteil, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20777 USA. Univ Paris 06, Lab Petrol, F-75005 Paris, France. RP Cabane, M (reprint author), Univ Paris 06, CNRS, Serv Aeron, IPSL,UMR 7620, T15,B102, F-75005 Paris, France. RI Mahaffy, Paul/E-4609-2012; RANNOU, Pascal/I-9059-2012 NR 29 TC 20 Z9 20 U1 1 U2 9 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 PY 2001 VL 49 IS 5 BP 523 EP 531 DI 10.1016/S0032-0633(00)00135-5 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 423ZX UT WOS:000168208600010 ER PT J AU Kern, VD Smith, JD Schwuchow, JM Sack, FD AF Kern, VD Smith, JD Schwuchow, JM Sack, FD TI Amyloplasts that sediment in protonemata of the moss Ceratodon purpureus are nonrandomly distributed in microgravity SO PLANT PHYSIOLOGY LA English DT Article ID GRAVITROPIC PROTONEMATA; STATOLITHS; CELLS AB Little is known about whether or how plant cells regulate the position of heavy organelles that sediment toward gravity. Dark-grown protonemata of the moss Ceratodon purpureus displays a complex plastid zonation in that only some amyloplasts sediment along the length of the tip cell. If gravity is the major force determining the position of amyloplasts that sediment, then these plastids should be randomly distributed in space. Instead, amyloplasts were clustered in the subapical region in microgravity. Cells rotated on a clinostat on earth had a roughly similar non-random plastid distribution. Subapical clusters were also found in ground controls that were inverted and kept stationary, but the distribution profile differed considerably due to amyloplast sedimentation. These findings indicate the existence of as yet unknown endogenous forces and mechanisms that influence amyloplast position and that are normally masked in stationary cells grown on earth. It is hypothesized that a microtubule-based mechanism normally compensates for g-induced drag while still allowing for regulated amyloplast sedimentation. C1 NASA, Ames Res Ctr, Lockheed Martin Space Operat, Ctr Bioinformat, Moffett Field, CA 94035 USA. Ohio State Univ, Dept Plant Biol, Columbus, OH 43210 USA. RP Kern, VD (reprint author), NASA, Ames Res Ctr, Lockheed Martin Space Operat, Ctr Bioinformat, POB 168, Moffett Field, CA 94035 USA. EM vkern@mail.arc.nasa.gov NR 21 TC 14 Z9 14 U1 1 U2 3 PU AMER SOC PLANT BIOLOGISTS PI ROCKVILLE PA 15501 MONONA DRIVE, ROCKVILLE, MD 20855 USA SN 0032-0889 EI 1532-2548 J9 PLANT PHYSIOL JI Plant Physiol. PD APR PY 2001 VL 125 IS 4 BP 2085 EP 2094 DI 10.1104/pp.125.4.2085 PG 10 WC Plant Sciences SC Plant Sciences GA 424CU UT WOS:000168215200056 PM 11299388 ER PT J AU Borucki, WJ Caldwell, D Koch, DG Webster, LD Jenkins, JM Ninkov, Z Showen, R AF Borucki, WJ Caldwell, D Koch, DG Webster, LD Jenkins, JM Ninkov, Z Showen, R TI The vulcan photometer: A dedicated photometer for extrasolar planet searches SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID STELLAR PHOTOMETRY; GIANT PLANETS; STABILITY; COMPANION; PRECISION; TRANSITS; LIMITS; STAR AB A small CCD photometer dedicated to the detection of extrasolar planets has been developed and put into operation at Mount Hamilton, California. It simultaneously monitors 6000 stars brighter than 13th magnitude in its 49 deg(2) field of view. Observations are conducted all night every clear night of the year. A single field is monitored at a cadence of eight images per hour for a period of about 3 months. When the data are folded for the purpose of discovering low-amplitude transits, transit amplitudes of 1% are readily detected. This precision is sufficient to find Jovian-size planets orbiting solar-like stars, which have signal amplitudes from 1% to 2% depending on the inflation of the planet's atmosphere and the size of the star. An investigation of possible noise sources indicates that neither star field crowding, scintillation noise, nor photon shot noise are the major noise sources for stars brighter than visual magnitude 11.6. Over one hundred variable stars have been found in each star field. About 50 of these stars are eclipsing binary stars, several with transit amplitudes of only a few percent. Three stars that showed only primary transits were examined with high-precision spectroscopy. Two were found to be nearly identical stars in binary pairs orbiting at double the photometric period. Spectroscopic observations showed the third star to be a high mass ratio single-lined binary. On 1999 November 22 the transit of a planet orbiting HD 209458 was observed and the predicted amplitude and immersion times were confirmed. These observations show that the photometer and the data reduction and analysis algorithms have the necessary precision to find companions with the expected area ratio for Jovian-size planets orbiting solar-like stars. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SETI Inst, Mt View, CA 94043 USA. Rochester Inst Technol, Rochester, NY 14623 USA. Raytheon Syst Co, Moffett Field, CA 94035 USA. RP Borucki, WJ (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RI Caldwell, Douglas/L-7911-2014 OI Caldwell, Douglas/0000-0003-1963-9616 NR 23 TC 53 Z9 53 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD APR PY 2001 VL 113 IS 782 BP 439 EP 451 DI 10.1086/319537 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 420HF UT WOS:000167999000004 ER PT J AU Stajner, I Riishojgaard, LP Rood, RB AF Stajner, I Riishojgaard, LP Rood, RB TI The GEOS ozone data assimilation system: Specification of error statistics SO QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY LA English DT Article DE anisotropic; constituent assimilation; error covariance modelling; real-time ozone; three-dimensional system; TOMS and SBUV instruments ID MOUNT-PINATUBO AEROSOLS; KALMAN FILTER; TRANSPORT; PREDICTION; DYNAMICS AB A global three-dimensional ozone data assimilation system has been developed at the Data Assimilation Office of the NASA Goddard Space Flight Center. The Total Ozone Mapping Spectrometer (TOMS) total ozone data and the Solar Backscatter UItraviolet/2 (SBUV/2) partial ozone profile observations are assimilated. The assimilation. into an off-lint ozone transport model, is done using the global Physical-space statistical Analysis Scheme. This system became operational in December 1999. A detailed description of the statistical analysis scheme and, in particular, of the forecast- and observation-error covariance models is given. A new global anisotropic horizontal forecast-error correlation model accounts for a varying distribution of observations with latitude. Correlations are largest in the zonal direction in the tropics where data are sparse. Forecast-error variance is assumed to be proportional to the ozone field. The forecast-error covariance parameters were determined by maximum-likelihood estimation. The error covariance models are validated using chi (2) statistics. The analysed ozone fields in the winter 1992 are validated against independent observations from ozone sondes and the Halogen Occultation Experiment (HALOE). The difference between the mean HALOE observations and the analysis fields is less than 10% at pressure levels between 70 and 0.2 hPa. The global root-mean-square difference between TOMS observed and forecast values is less than 4%. The global root-mean-square difference between SBUV observed and analysed ozone between 50 and 3 hPa is less than 15%. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Baltimore, MD 21228 USA. RP Stajner, I (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 910-3, Greenbelt, MD 20771 USA. RI Rood, Richard/C-5611-2008; Stajner, Ivanka/B-5228-2009 OI Rood, Richard/0000-0002-2310-4262; Stajner, Ivanka/0000-0001-6103-3939 NR 37 TC 62 Z9 63 U1 0 U2 0 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 2001 VL 127 IS 573 BP 1069 EP 1094 DI 10.1002/qj.49712757320 PN A PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 429DD UT WOS:000168500000019 ER PT J AU Zheng, QN Yan, XH Liu, WT Klemas, V Sun, DC AF Zheng, QN Yan, XH Liu, WT Klemas, V Sun, DC TI Space shuttle observations of open ocean oil slicks SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID INTERNAL WAVES; PHOTOGRAPHS AB We observed oil slicks along a ship wake in the northern Arabian Sea. The slicks were recorded on photographs taken by astronauts onboard Space Shuttle Columbia during mission STS62 in March 1994. The longest slick had a length of 21.25 km and an average width of 1.67 km. The total volume of oil discharged into the sea was estimated at 108 +/- 37 m(3) assuming a reasonable thickness of the oil film to be 3 +/- 1 mum. The oil slick width increased with the distance from the ship. This image feature was converted into information in the time domain with the ship speed being a conversion parameter. Using this method, we determined that the average oil slick spreading velocity with respect to the ship wake was 13.6 cm s(-1). The analysis indicated that turbulent diffusion and wind drag were the dominant forcing for the oil slick spreading. (C) 2001 Elsevier Science Inc. All rights reserved. C1 Univ Delaware, Coll Marine Studies, Ctr Remote Sensing, Newark, DE 19716 USA. CALTECH, Jet Prop Lab 300 323, Pasadena, CA 91109 USA. Shengli Petr Adm Bur, Shandong 257237, Peoples R China. RP Klemas, V (reprint author), Univ Delaware, Coll Marine Studies, Ctr Remote Sensing, Newark, DE 19716 USA. RI Zheng, Quanan/F-9025-2010 NR 18 TC 12 Z9 14 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD APR PY 2001 VL 76 IS 1 BP 49 EP 56 DI 10.1016/S0034-4257(00)00191-7 PG 8 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 421JN UT WOS:000168061400004 ER PT J AU Hook, SJ Myers, JEJ Thome, KJ Fitzgerald, M Kahle, AB AF Hook, SJ Myers, JEJ Thome, KJ Fitzgerald, M Kahle, AB TI The MODIS/ASTER airborne simulator (MASTER) - a new instrument for earth science studies SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID RADIOMETRIC CALIBRATION; MODIS; SPECTROMETER; WATER AB The MODIS/ASTER Airborne Simulator was developed for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Moderate Resolution Imaging Spectroradiometer (MODIS) projects. ASTER and MODIS are both spaceborne imaging instruments on the Tel-ra platform launched in the fall of 1999. Currently MASTER is flown on the Department of Energy (DOE) King Air Beachcraft B200 aircraft and the NASA DC-8. In older to validate the in-flight performance of the instrument, the Jet Propulsion Laboratory and the University of Arizona conducted a joint experiment in December 1998. The experiment involved overflights of the MASTER instrument at two sites at three elevations (2000, 4000, and 6000 m). The two sites: Ivanpah Playa, California, and Lake Mead, Nevada, were selected to validate the visible-shortwave infrared and thermal infrared (TIR) channels, respectively. At Ivanpah Playa, a spectrometer was used to determine the surface reflectance and a sun photometer used to obtain the optical depth. At Lake Mead contact and radiometric surface lake temperatures were measured by buoy-mounted thermistors and self-calibrating radiometers, respectively. Atmospheric profiles of temperature, pressure, and relative humidity were obtained by launching an atmospheric sounding balloon. The measured surface radiances were then propagated to the at-sensor radiance using radiative transfer models driven by the local atmospheric data. There was excellent agreement between the predicted radiance at sensor and the measured radiance at sensor at all three altitudes. The percent difference between the channels not strongly affected by the atmosphere in the visible-shortwave infrared was typically 1-5% and the percent difference between the TIR channels not strongly affected by the atmosphere was typically less than 0.5%. These results indicate the MASTER instrument should provide a well-calibrated instrument for Earth Science Studies. It should prove particularly valuable for those studies that leverage information across the electromagnetic spectrum from the visible to the TIR. (C) 2001 Elsevier Science Inc. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91009 USA. NASA, Ames Res Ctr, SAIC, Moffett Field, CA 94035 USA. Univ Arizona, Ctr Opt Sci, Tucson, AZ 85721 USA. RP Hook, SJ (reprint author), CALTECH, Jet Prop Lab, Mail Stop 183-501, Pasadena, CA 91009 USA. RI Thome, Kurtis/D-7251-2012 NR 22 TC 146 Z9 155 U1 0 U2 24 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD APR PY 2001 VL 76 IS 1 BP 93 EP 102 DI 10.1016/S0034-4257(00)00195-4 PG 10 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 421JN UT WOS:000168061400008 ER PT J AU Simpson, JJ Berg, JS Koblinsky, CJ Hufford, GL Beckley, B AF Simpson, JJ Berg, JS Koblinsky, CJ Hufford, GL Beckley, B TI The NVAP global water vapor data set: independent cross-comparison and multiyear variability SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID MICROWAVE RADIOMETER; LIQUID WATER; TEMPERATURE; ALGORITHM; SSM/I; CLIMATOLOGY; PREDICTION; MOISTURE; INCREASE; OCEANS AB Space-time variability in the global distribution of atmospheric total column water vapor (tcwp) greatly impacts the hydrologic cycle. NASA's Water Vapor Project (NVAP) produced a global 1 degrees x1 degrees tcwp data set for use as a tool to investigate, among other things, atmospheric variability. An independent cross-comparison of the NVAP tcwp product was performed using the TOPEX/POSEIDON (TIP) TOPEX microwave radiometer (TMR) data and the European Centre for Medium-Range Weather Forecasts (ECMWF)-based range delay data set produced by Meteo-France (MF) and distributed with T/P data. When these T/P range delay data are converted to tcwp, they show that NVAP is biased dry and ECMWF/MF is biased wet relative to the independent TMR measurement. Although the absolute accuracy of the NVAP tcwp product is uncertain, results indicate its relative accuracy is sufficient for variability studies. Empirical orthogonal function (EOF) analysis and spectral analysis applied to this data set show that seasonal variability over the annual cycle accounts for about 20% of the variance (EOF1). An El Nino-southern oscillation (ENSO) signal is found in the annually demeaned data; the magnitude of the crosscorrelation between the temporal amplitude (TA) of EOF1 and the Nino 3.3 (SST) time series is .9. Comparisons also were made between the NVAP patterns of variability in tcwp and independent reanalysis and interpretation of numerical model generated atmospheric fields. In general, there is good agreement between the NVAP data and the reanalysis fields. Finally, specific recommendations are made for: (1) improvement of the NVAP data set upon reanalysis and (2) use of the NVAP data, in place of ECMWF/MF-based range delay data, for T/P retrievals when TMR data are not available if and when T/P data are reanalyzed. This latter recommendation is especially important for regions of the tropical Indo-Pacific (e.g., Indonesia) where islands can interfere with valid TMR retrievals. (C) 2001 Elsevier Science Inc. All rights reserved. C1 Scripps Inst Oceanog, La Jolla, CA 92093 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Simpson, JJ (reprint author), Univ Calif Los Angeles, Digital Image Anal Lab, 9500 Gilman Dr,MS 0237, Los Angeles, CA 90093 USA. NR 50 TC 29 Z9 29 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD APR PY 2001 VL 76 IS 1 BP 112 EP 129 DI 10.1016/S0034-4257(00)00199-1 PG 18 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 421JN UT WOS:000168061400010 ER PT J AU Hahn, I Weilert, M AF Hahn, I Weilert, M TI Digital signal processor-based dc superconducting quantum interference device controller SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID RESOLUTION THERMOMETER AB We report on the design and evaluation of a convenient digital signal processor-based (DSP) controller for a dc superconducting quantum interference device (SQUID). Program algorithms for the DSP conveniently replace major functions of an analog flux-locked loop: current bias, modulation signal, demodulation, filtering, integration, feedback, and reset. For the controller described here, the entire system was built using commercially available electronics and sensor units with the addition of a simple operational amplifier circuit for the required gain. The noise level of the nonoptimized dc SQUID controller system at 1 Hz was similar to 50 mu Phi (0)/root Hz. Application of the system was demonstrated as a readout system for a low-temperature magnetic susceptibility thermometer that required flux counting. (C) 2001 American Institute of Physics. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hahn, I (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 9 TC 2 Z9 2 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD APR PY 2001 VL 72 IS 4 BP 2203 EP 2206 DI 10.1063/1.1350646 PG 4 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 415FE UT WOS:000167709500043 ER PT J AU Tey, SJ Huang, WM Sokolowski, WM AF Tey, SJ Huang, WM Sokolowski, WM TI Influence of long-term storage in cold hibernation on strain recovery and recovery stress of polyurethane shape memory polymer foam SO SMART MATERIALS & STRUCTURES LA English DT Article ID SERIES; FILM AB In this paper, the effects of long-term storage in compressed cold hibernated elastic memory (CHEM) polyurethane foam, a kind of shape memory polymer, are investigated experimentally. The foams were pre-strained at a high temperature, which was above the glass transition temperature, to 80% and 93.4%, respectively, and then cooled back to room temperature. After various periods of cold hibernation (up to two months), they were heated up at fixed length or against different constant loads. It is found that: (1) the maximum stress that the foam could exert at fixed length depends heavily on the amount of pre-strain; (2) expansion rates of 380 and 1273% from the hibernated size against a 1 N load (pre-strained by 80 and 93.4%, respectively) are achievable. However, upon further increases in load, the expansion is reduced dramatically. It appears that the tested CHEM polyurethane foam retains its shape memory properties even after being stored in a compacted state for a long period. Complete strain recovery is attainable for a hibernation period of up to two months. C1 Nanyang Technol Univ, Sch Mech & Prod Engn, Singapore 639798, Singapore. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RI NTU, S'gapore/F-4683-2012; Huang , Wei Min/A-3851-2011 OI Huang , Wei Min/0000-0003-0338-4858 NR 7 TC 79 Z9 81 U1 3 U2 25 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0964-1726 J9 SMART MATER STRUCT JI Smart Mater. Struct. PD APR PY 2001 VL 10 IS 2 BP 321 EP 325 DI 10.1088/0964-1726/10/2/318 PG 5 WC Instruments & Instrumentation; Materials Science, Multidisciplinary SC Instruments & Instrumentation; Materials Science GA 433UF UT WOS:000168777600018 ER PT J AU Bates, JR Fang, PH AF Bates, JR Fang, PH TI Some astronomical effects observed by solar cells from Apollo missions on lunar surface SO SOLAR ENERGY MATERIALS AND SOLAR CELLS LA English DT Article DE solar cells; astronomical effects AB The solar cell performance in lunar environment, including the August 1972 solar flare, two lunar eclipses pre- and post-solar flare observed by their effect on the solar cells installed on the lunar surface are reported in this paper. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. FS Lab, Belmont, MA 02478 USA. RP Bates, JR (reprint author), NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 3 TC 2 Z9 2 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-0248 J9 SOL ENERG MAT SOL C JI Sol. Energy Mater. Sol. Cells PD APR PY 2001 VL 68 IS 1 BP 23 EP 29 DI 10.1016/S0927-0248(00)00343-3 PG 7 WC Energy & Fuels; Materials Science, Multidisciplinary; Physics, Applied SC Energy & Fuels; Materials Science; Physics GA 394FD UT WOS:000166512700003 ER PT J AU Nyquist, LE Bogard, DD Shih, CY Greshake, A Stoffler, D Eugster, O AF Nyquist, LE Bogard, DD Shih, CY Greshake, A Stoffler, D Eugster, O TI Ages and geologic histories of Martian meteorites SO SPACE SCIENCE REVIEWS LA English DT Review DE shock effects; crystallization ages; cosmic ray exposure ages; ejection ages; provenance ID ALLAN HILLS 84001; POLYCYCLIC AROMATIC-HYDROCARBONS; CALCIUM-RICH ACHONDRITES; ND ISOTOPIC SYSTEMATICS; LIGHT NOBLE-GASES; ANGRA-DOS-REIS; AL GANI 476; SNC METEORITES; SHOCK METAMORPHISM; ORTHOPYROXENITE ALH84001 AB We review the radiometric ages of the 16 currently known Martian meteorites, classified as 11 shergottites (8 basaltic and 3 lherzolitic), 3 nakhlites (clinopyroxenites), Chassigny (a dunite), and the orthopyroxenite ALH84001. The basaltic shergottites represent surface lava flows, the others magmas that solidified at depth. Shock effects correlate with these compositional types, and, in each case, they can be attributed to a single shock event, most likely the meteorite's ejection from Mars. Peak pressures in the range 15 - 45 GPa appear to be a "launch window": shergottites experienced similar to 30 - 45 GPa, nakhlites similar to 20 +/- 5 GPa, Chassigny similar to 35 GPa, and ALH84001 similar to 35 - 40 GPa. Two meteorites, lherzolitic shergottite Y-793605 and orthopyroxenite ALH84001, are monomict breccias, indicating a two-phase shock history in toto: monomict brecciation at depth in a first impact and later shock metamorphism in a second impact, probably the ejection event. Crystallization ages of shergottites show only two pronounced groups designated S-1 (similar to 175 Myr), including 4 of 6 dated basalts and all 3 lherzolites, and S-2 (330 - 475 Myr), including two basaltic shergottites and probably a third according to preliminary data. Ejection ages of shergottites, defined as the sum of their cosmic ray exposure ages and their terrestrial residence ages, range from the oldest (similar to 20 Myr) to the youngest (similar to0.7 Myr) values for Martian meteorites. Five groups are distinguished and designated S-Dho (one basalt, similar to 20 Myr), S-L (two lherzolites of overlapping ejection ages, 3.94 +/- 0.40 Myr and 4.70 +/- 0.50 Myr), S (four basalts and one lherzolite, similar to2.7 - 3.1 Myr), S-DaG (two basalts, similar to1.25 Myr), and S-E (the youngest basalt, 0.73 +/- 0.15 Myr). Consequently, crystallization age group S-1 includes ejection age groups S-L, S-E and 4 of the 5 members of S, whereas S-2 includes the remaining member of S and one of the two members of S-DaG. Shock effects are different for basalts and lherzolites in group S/S-1. Similarities to the dated meteorite DaG476 suggest that the two shergottites that are not dated yet belong to group S-2. Whether or not S-2 is a single group is unclear at present. If crystallization age group S-1 represents a single ejection event, pre-exposure on the Martian surface is required to account for ejection ages of S-L that are greater than ejection ages of S, whereas secondary breakup in space is required to account for ejection ages of S-E less than those of S. Because one member of crystallization age group S-2 belongs to ejection group S, the maximum number of shergottite ejection events is 6, whereas the minimum number is 2. Crystallization ages of nakhlites and Chassigny are concordant at similar to1.3 Gyr. These meteorites also have concordant ejection ages, i.e., they were ejected together in a single event (NC). Shock effects vary within group NC between the nakhlites and Chassigny. The orthopyroxenite ALH84001 is characterized by the oldest crystallization age of similar to4.5 Gyr. Its secondary carbonates are similar to3.9 Gyr old, an age corresponding to the time of Ar-outgassing from silicates. Carbonate formation appears to have coincided with impact metamorphism, either directly, or indirectly, perhaps via precipitation from a transient impact crater lake. The crystallization age and the ejection age of ALH84001, the second oldest ejection age at 15.0 +/- 0.8 Myr, give evidence for another ejection event (O). Consequently, the total number of ejection events for the 16 Martian meteorites lies in the range 4 - 8. The Martian meteorites indicate that Martian magmatism has been active over most of Martian geologic history, in agreement with the inferred very young ages of flood basalt flows observed in Elysium and Amazonis Planitia with the Mars Orbital Camera (MOC) on the Mars Global Surveyor (MGS). The provenance of the youngest meteorites must be found among the youngest volcanic surfaces on Mars, i.e., in the Tharsis, Amazonis, and Elysium regions. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin Space Operat, Basic & Appl Res Dept, Houston, TX 77058 USA. Museum Nat Kunde, Inst Mineral, D-10115 Berlin, Germany. Univ Bern, Inst Phys, CH-3012 Bern, Switzerland. RP NASA, Lyndon B Johnson Space Ctr, 2101 NASA Rd 1, Houston, TX 77058 USA. EM laurence.e.nyquist1@jsc.nasa.gov NR 223 TC 363 Z9 370 U1 6 U2 46 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 2001 VL 96 IS 1-4 BP 105 EP 164 DI 10.1023/A:1011993105172 PG 60 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 475FC UT WOS:000171150700005 ER PT J AU Spohn, T Acuna, MH Breuer, D Golombek, M Greeley, R Halliday, A Hauber, E Jaumann, R Sohl, F AF Spohn, T Acuna, MH Breuer, D Golombek, M Greeley, R Halliday, A Hauber, E Jaumann, R Sohl, F TI Geophysical constraints on the evolution of Mars SO SPACE SCIENCE REVIEWS LA English DT Review ID LARGE VISCOSITY VARIATIONS; MARTIAN MANTLE IMPLICATIONS; THERMAL EVOLUTION; GLOBAL SURVEYOR; MAGNETIC-FIELD; TERRESTRIAL PLANETS; PHASE-TRANSITIONS; CHEMICAL-COMPOSITION; DEPENDENT VISCOSITY; INTERIOR STRUCTURE AB The evolution of Mars is discussed using results from the recent Mars Global Surveyor (MGS) and Mars Pathfinder missions together with results from mantle convection and thermal history models and the chemistry of Martian meteorites. The new MGS topography and gravity data and the data on the rotation of Mars from Mars Pathfinder constrain models of the present interior structure and allow estimates of present crust thickness and thickness variations. The data also allow estimates of lithosphere thickness variation and heat flow assuming that the base of the lithosphere is an isotherm. Although the interpretation is not unambiguous, it can be concluded that Mars has a substantial crust. It may be about 50 km thick on average with thickness variations of another +/- 50 km. Alternatively, the crust may be substantially thicker with smaller thickness variations. The former estimate of crust thickness can be shown to be in agreement with estimates of volcanic production rates from geologic mapping using data from the camera on MGS and previous missions. According to these estimates most of the crust was produced in the Noachian, roughly the first Gyr of evolution. A substantial part of the lava generated during this time apparently poured onto the surface to produce the Tharsis bulge, the largest tectonic unit in the solar system and the major volcanic center of Mars. Models of crust growth that couple crust growth to mantle convection and thermal evolution are consistent with an early 1 Gyr long phase of vigorous volcanic activity. The simplest explanation for the remnant magnetization of crustal units of mostly the southern hemisphere calls for an active dynamo in the Noachian, again consistent with thermal history calculations that predict the core to become stably stratified after some hundred Myr of convective cooling and dynamo action. The isotope record of the Martian meteorites suggest that the core formed early and rapidly within a few tens of Myr. These data also suggest that the silicate rock component of the planet was partially molten during that time. The isotope data suggest that heterogeneity resulted from core formation and early differentiation and persisted to the recent past. This is often taken as evidence against vigorous mantle convection and early plate tectonics on Mars although the latter assumption can most easily explain the early magnetic field. The physics of mantle convection suggests that there may be a few hundred km thick stagnant, near surface layer in the mantle that would have formed rapidly and may have provided the reservoirs required to explain the isotope data. The relation between the planform of mantle convection and the tectonic features on the surface is difficult to entangle. Models call for long wavelength forms of flow and possibly a few strong plumes in the very early evolution. These plumes may have dissolved with time as the core cooled and may have died off by the end of the Noachian. C1 Univ Munster, Inst Planetol, D-48149 Munster, Germany. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. ETH Zentrum, Dept Earth Sci, CH-8092 Zurich, Switzerland. Deutsch Zentrum Luft & Raumfahrt DLR, D-12489 Berlin, Germany. RP Univ Munster, Inst Planetol, W Klemmstr 10, D-48149 Munster, Germany. NR 94 TC 66 Z9 67 U1 0 U2 9 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 2001 VL 96 IS 1-4 BP 231 EP 262 DI 10.1023/A:1011949306989 PG 32 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 475FC UT WOS:000171150700008 ER PT J AU Head, JW Greeley, R Golombek, MP Hartmann, WK Hauber, E Jaumann, R Masson, P Neukum, G Nyquist, LE Carr, MH AF Head, JW Greeley, R Golombek, MP Hartmann, WK Hauber, E Jaumann, R Masson, P Neukum, G Nyquist, LE Carr, MH TI Geological processes and evolution SO SPACE SCIENCE REVIEWS LA English DT Review ID ORBITER LASER ALTIMETER; MARS GLOBAL SURVEYOR; MARTIAN NORTHERN PLAINS; PATHFINDER LANDING SITE; THARSIS REGION; VALLES MARINERIS; MOLA DATA; TERRESTRIAL ANALOGS; CRATER OBLITERATION; TECTONIC HISTORY AB Geological mapping and establishment of stratigraphic relationships provides an overview of geological processes operating on Mars and how they have varied in time and space. Impact craters and basins shaped the crust in earliest history and as their importance declined, evidence of extensive regional volcanism emerged during the Late Noachian. Regional volcanism characterized the Early Hesperian and subsequent to that time, volcanism was largely centered at Tharsis and Elysium, continuing until the recent geological past. The Tharsis region appears to have been largely constructed by the Late Noachian, and represents a series of tectonic and volcanic centers. Globally distributed structural features representing contraction characterize the middle Hesperian. Water-related processes involve the formation of valley networks in the Late Noachian and into the Hesperian, an ice sheet at the south pole in the middle Hesperian, and outflow channels and possible standing bodies of water in the northern lowlands in the Late Hesperian and into the Amazonian. A significant part of the present water budget occurs in the present geologically young polar layered terrains. In order to establish more firmly rates of processes, we stress the need to improve the calibration of the absolute timescale, which today is based on crater count systems with substantial uncertainties, along with a sampling of rocks of unknown provenance. Sample return from carefully chosen stratigraphic units could calibrate the existing timescale and vastly improve our knowledge of Martian evolution. C1 Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Planetary Sci Inst, Tucson, AZ 85705 USA. DLR Inst Space Sensor Technol & Planetary Explora, D-12484 Berlin, Germany. Univ Paris 11, F-91405 Orsay, France. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. US Geol Survey, Branch Astrogeol Studies, Menlo Pk, CA 94025 USA. RP Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. EM james_head_iii@brown.edu NR 155 TC 53 Z9 53 U1 0 U2 7 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 2001 VL 96 IS 1-4 BP 263 EP 292 DI 10.1023/A:1011953424736 PG 30 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 475FC UT WOS:000171150700009 ER PT J AU Bridges, JC Catling, DC Saxton, JM Swindle, TD Lyon, IC Grady, MM AF Bridges, JC Catling, DC Saxton, JM Swindle, TD Lyon, IC Grady, MM TI Alteration assemblages in martian meteorites: Implications for near-surface processes SO SPACE SCIENCE REVIEWS LA English DT Review ID ALLAN HILLS 84001; OXYGEN-ISOTOPIC COMPOSITION; ATMOSPHERIC CARBON-DIOXIDE; ION MASS-SPECTROMETRY; SNC METEORITES; LOW-TEMPERATURE; NAKHLA METEORITE; EARLY MARS; WEATHERING PRODUCTS; LAFAYETTE METEORITE AB The SNC (Shergotty-Nakhla-Chassigny) meteorites have recorded interactions between martian crustal fluids and the parent igneous rocks. The resultant secondary minerals - which comprise up to similar to1 vol.% of the meteorites - provide information about the timing and nature of hydrous activity and atmospheric processes on Mars. We suggest that the most plausible models for secondary mineral formation involve the evaporation of low temperature (25 - 150 degreesC) brines. This is consistent with the simple mineralogy of these assemblages - Fe-Mg-Ca carbonates, anhydrite, gypsum, halite, clays - and the chemical fractionation of Ca-to Mg-rich carbonate in ALH84001 "rosettes". Longer-lived, and higher temperature, hydrothermal systems would have caused more silicate alteration than is seen and probably more complex mineral assemblages. Experimental and phase equilibria data on carbonate compositions similar to those present in the SNCs imply low temperatures of formation with cooling taking place over a short period of time (e.g. days). The ALH84001 carbonate also probably shows the effects of partial vapourisation and dehydration related to an impact event post-dating the initial precipitation. This shock event may have led to the formation of sulphide and some magnetite in the Fe-rich outer parts of the rosettes. Radiometric dating (K-Ar, Rb-Sr) of the secondary mineral assemblages in one of the nakhlites (Lafayette) suggests that they formed between 0 and 670 Myr, and certainly long after the crystallisation of the host igneous rocks. Crystallisation of ALH84001 carbonate took place 0.5 Gyr after the parent rock. These age ranges and the other research on these assemblages suggest that environmental conditions conducive to near-surface liquid water have been present on Mars periodically over the last similar to1 Gyr. This fluid activity cannot have been continuous over geological time because in that case much more silicate alteration would have taken place in the meteorite parent rocks and the soluble salts would probably not have been preserved. The secondary minerals could have been precipitated from brines with seawater-like composition, high bicarbonate contents and a weakly acidic nature. The co-existence of siderite (Fe-carbonate) and clays in the nakhlites suggests that the pCO(2) level in equilibrium with the parent brine may have been 50 mbar or more. The brines could have originated as flood waters which percolated through the top few hundred meters of the crust, releasing cations from the surrounding parent rocks. The high sulphur and chlorine concentrations of the martian soil have most likely resulted from aeolian redistribution of such aqueously-deposited salts and from reaction of the martian surface with volcanic acid volatiles. The volume of carbonates in meteorites provides a minimum crustal abundance and is equivalent to 50-250 mbar of CO2 being trapped in the uppermost 200-1000 m of the martian crust. Large fractionations in delta O-18 between igneous silicate in the meteorites and the secondary minerals (less than or equal to 30 parts per thousand) require formation of the latter below temperatures at which silicate-carbonate equilibration could have taken place (similar to 400 degreesC) and have been taken to suggest low temperatures (e.g. less than or equal to 150 degreesC) of precipitation from a hydrous fluid. C1 Nat Hist Museum, Dept Mineral, London SW7 5BD, England. NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Univ Manchester, Dept Earth Sci, Manchester M13 9PL, Lancs, England. RP Nat Hist Museum, Dept Mineral, Cromwell Rd, London SW7 5BD, England. EM j.bridges@nhm.ac.uk RI Catling, David/D-2082-2009; OI Catling, David/0000-0001-5646-120X; Grady, Monica/0000-0002-4055-533X NR 109 TC 165 Z9 166 U1 5 U2 26 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 2001 VL 96 IS 1-4 BP 365 EP 392 DI 10.1023/A:1011965826553 PG 28 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 475FC UT WOS:000171150700013 ER PT J AU Greeley, R Kuzmin, RO Haberle, RM AF Greeley, R Kuzmin, RO Haberle, RM TI Aeolian processes and their effects on understanding the chronology of Mars SO SPACE SCIENCE REVIEWS LA English DT Review ID PATHFINDER LANDING SITE; GENERAL-CIRCULATION; MARTIAN SURFACE; GLOBAL SURVEYOR; ORBITER CAMERA; WIND EROSION; SAND; FEATURES; SIMULATIONS; DEPOSITS AB Aeolian (wind) processes can transport particles over large distances on Mars, leading to the modification or removal of surface features, formation of new landforms, and mantling or burial of surfaces. Erosion of mantling deposits by wind deflation can exhume older surfaces. These processes and their effects on the surface must be taken into account in using impact crater statistics to derive chronologies on Mars. In addition, mapping the locations, relative ages, and orientations of aeolian features can provide insight into Martian weather, climate, and climate history. C1 Arizona State Univ, Dept Geol Sci, Tempe, AZ 85287 USA. Russian Acad Sci, Vernadsky Inst, Moscow 117975, Russia. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Arizona State Univ, Dept Geol Sci, Box 871404, Tempe, AZ 85287 USA. EM greeley@asu.edu NR 35 TC 11 Z9 12 U1 0 U2 2 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 2001 VL 96 IS 1-4 BP 393 EP 404 DI 10.1023/A:1011917910624 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 475FC UT WOS:000171150700014 ER PT J AU Bogard, DD Clayton, RN Marti, K Owen, T Turner, G AF Bogard, DD Clayton, RN Marti, K Owen, T Turner, G TI Martian volatiles: Isotopic composition, origin, and evolution SO SPACE SCIENCE REVIEWS LA English DT Review ID ALLAN HILLS 84001; METEORITE ALH84001 EVIDENCE; ANCIENT OXYGEN EXOSPHERE; TRAPPED NOBLE-GASES; SNC METEORITES; CHEMICAL-COMPOSITION; SOLAR-WIND; ORTHOPYROXENITE ALH84001; ATMOSPHERE EVOLUTION; MASS FRACTIONATION AB Information about the composition of volatiles in the Martian atmosphere and interior derives from Viking spacecraft and ground-based measurements, and especially from measurements of volatiles trapped in Martian meteorites, which contain several distinct components. One volatile component, found in impact glass in some shergottites, gives the most precise measurement to date of the composition of Martian atmospheric Ar, Kr, and Xe, and also contains significant amounts of atmospheric nitrogen showing elevated N-15/N-14. Compared to Viking analyses, the Ar-36/Xe-132 and Kr-84/Xe-132 elemental ratios are larger in shergottites, the Xe-129/Xe-132 ratio is similar, and the Ar-40/Ar-36 and Ar-36/Ar-38 ratios are smaller. The isotopic composition of atmospheric Kr is very similar to solar Kr, whereas the isotopes of atmospheric Xe have been strongly mass fractionated in favor of heavier isotopes. The nakhlites and ALH84001 contain an atmospheric component elementally fractionated relative to the recent atmospheric component observed in shergottites. Several Martian meteorites also contain one or more Martian interior components that do not show the mass fractionation observed in atmospheric noble gases and nitrogen. The D/H ratio in the atmosphere is strongly mass fractionated, but meteorites contain a distinct Martian interior hydrogen component. The isotopic composition of Martian atmospheric carbon and oxygen have not been precisely measured, but these elements in meteorites appear to show much less variation in isotopic composition, presumably in part because of buffering of the atmospheric component by larger condensed reservoirs. However, differences in the oxygen isotopic composition between meteorite silicate minerals (on the one hand) and water and carbonates indicate a lack of recycling of these volatiles through the interior. Many models have been presented to explain the observed isotopic fractionation in Martian atmospheric N, H, and noble gases in terms of partial loss of the planetary atmosphere, either very early in Martian history, or over extended geological time. The number of variables in these models is large, and we cannot be certain of their detailed applicability. Evolutionary data based on the radiogenic isotopes (i.e., Ar-40/Ar-36, Xe-129/Xe-132, and Xe-136/Xe-132 ratios) are potentially important, but meteorite data do not yet permit their use in detailed chronologies. The sources of Mars' original volatiles are not well defined. Some Martian components require a solar-like isotopic composition, whereas volatiles other than the noble gases (C, N, and H2O) may have been largely contributed by a carbonaceous (or cometary) veneer late in planet formation. Also, carbonaceous material may have been the source of moderate amounts of water early in Martian history. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Calif San Diego, Dept Chem, La Jolla, CA 92093 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Univ Manchester, Dept Earth Sci, Manchester M13 9PL, Lancs, England. RP NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. EM donald.d.bogard1@jsc.nasa.gov NR 114 TC 60 Z9 60 U1 1 U2 21 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 2001 VL 96 IS 1-4 BP 425 EP 458 DI 10.1023/A:1011974028370 PG 34 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 475FC UT WOS:000171150700017 ER PT J AU Grewe, V Dameris, M Hein, R Sausen, R Steil, B AF Grewe, V Dameris, M Hein, R Sausen, R Steil, B TI Future changes of the atmospheric composition and the impact of climate change SO TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY LA English DT Article ID AIRCRAFT NOX EMISSIONS; TROPOSPHERIC OZONE; STRATOSPHERIC OZONE; TRANSIENT RESPONSES; GRADUAL CHANGES; MODEL; CHEMISTRY; CO2; GREENHOUSE AB The development of the future atmospheric chemical composition is investigated with respect to NOy and O-3 by means of the off-line coupled dynamic-chemical general circulation model ECHAM3/CHEM. Two time slice experiments have been performed for the years 1992 and 2015. which include changes in sea surface temperatures. greenhouse gas concentrations. emissions of CFCs, NOx and other species. i.e., the 2015 simulation accounts fur changes in chemically relevant emissions and for a climate change and its impact on air chemistry. The 2015 simulation clearly shows a global increase in ozone except for large areas of the lower stratosphere, where no significant changes or even decreases in the ozone concentration are found. For a better understanding of the importance of (A) emissions. like NOx and CFCs. ( B) future changer of air temperature and water vapour concentration. and (C) other dynamical parameters, like precipitation and changes in the circulation diabatic circulation. stratosphere-troposphere-exchange. the simulation of the future atmosphere has been performed stepwise. This method requires a climate-chemistry modal without interactive coupling of chemical species. Model results show that the direct effect of emissions (A) plays a major role for the composition of the future atmosphere, but they also clearly show that climate change (B and C) has a significant impact and strongly reduces the NO, and ozone concentration in the lower stratosphere. C1 DLR, Inst Phys Atmosphare, D-82234 Wessling, Germany. Columbia Univ, NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Max Planck Inst Chem, D-55020 Mainz, Germany. RP Grewe, V (reprint author), DLR, Inst Phys Atmosphare, D-82234 Wessling, Germany. RI Grewe, Volker/A-6147-2011 OI Grewe, Volker/0000-0002-8012-6783 NR 53 TC 20 Z9 21 U1 0 U2 2 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0280-6509 J9 TELLUS B JI Tellus Ser. B-Chem. Phys. Meteorol. PD APR PY 2001 VL 53 IS 2 BP 103 EP 121 DI 10.1034/j.1600-0889.2001.d01-10.x PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 451PP UT WOS:000169810700001 ER PT J AU Lanyi, JK Pohorille, A AF Lanyi, JK Pohorille, A TI Proton pumps: mechanism of action and applications SO TRENDS IN BIOTECHNOLOGY LA English DT Review ID CYTOCHROME-C-OXIDASE; INFLUENZA-A VIRUS; F0F1 ATP SYNTHASE; 2.8-ANGSTROM RESOLUTION; ION-TRANSPORT; BACTERIORHODOPSIN; LIPOSOMES; CHANNEL; TRANSLOCATION; F1-ATPASE AB Recent progress in understanding the molecular structures and mechanisms of action of proton pumps has paved the way to their novel applications in biotechnology. Proton pumps, bacteriorhodopsin and AIP synthases in particular, are capable of continuous, renewable conversion of light to chemical, mechanical or electrical energy, which can be used in macro- or nano-scale devices. The capability of protein systems incorporated into liposomes to generate ATP, which can be used to drive chemical reactions and to act as molecular motors has been already demonstrated. Of her possible applications of such biochemical devices include targeted drug delivery and biocatalytic reactors. All these devices might prove superior to their inorganic alternatives. C1 Univ Calif Irvine, Dept Physiol & Biophys, Irvine, CA 92697 USA. Univ Calif San Francisco, Dept Pharmaceut Chem, San Francisco, CA 94140 USA. NASA, Ames Res Ctr, Exobiol Branch, Moffett Field, CA 94035 USA. RP Lanyi, JK (reprint author), Univ Calif Irvine, Dept Physiol & Biophys, Irvine, CA 92697 USA. RI Lanyi, Janos/C-3808-2011 NR 31 TC 43 Z9 44 U1 2 U2 15 PU ELSEVIER SCIENCE LONDON PI LONDON PA 84 THEOBALDS RD, LONDON WC1X 8RR, ENGLAND SN 0167-7799 J9 TRENDS BIOTECHNOL JI Trends Biotechnol. PD APR PY 2001 VL 19 IS 4 BP 140 EP 144 DI 10.1016/S0167-7799(01)01576-1 PG 5 WC Biotechnology & Applied Microbiology SC Biotechnology & Applied Microbiology GA 432VP UT WOS:000168716700007 PM 11250031 ER PT J AU Phillips, RJ Zuber, MT Solomon, SC Golombek, MP Jakosky, BM Banerdt, WB Smith, DE Williams, RME Hynek, BM Aharonson, O Hauck, SA AF Phillips, RJ Zuber, MT Solomon, SC Golombek, MP Jakosky, BM Banerdt, WB Smith, DE Williams, RME Hynek, BM Aharonson, O Hauck, SA TI Ancient geodynamics and global-scale hydrology on Mars SO SCIENCE LA English DT Article ID INTERNAL STRUCTURE; EVOLUTION; TOPOGRAPHY; SURVEYOR; SUPPORT; GRAVITY; RISE AB Loading of the Lithosphere of Mars by the Tharsis rise explains much of the global shape and Long-wavelength gravity field of the planet, including a ring of negative gravity anomalies and a topographic trough around Tharsis, as well as gravity anomaly and topographic highs centered in Arabia Terra and extending northward toward Utopia. The Tharsis-induced trough and antipodal high were largely in place by the end of the Noachian Epoch and exerted control on the location and orientation of valley networks. The release of carbon dioxide and water accompanying the emplacement of similar to3 x 10(8) Cubic kilometers of Tharsis magmas may have sustained a warmer climate than at present, enabling the formation of ancient valley networks and fluvial landscape denudation in and adjacent to the large-scale trough. C1 Washington Univ, McDonnell Ctr Space Sci, St Louis, MO 63110 USA. Washington Univ, Dept Earth & Planetary Sci, St Louis, MO 63110 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. NASA, Earth Sci Directorate, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. RP Phillips, RJ (reprint author), Washington Univ, McDonnell Ctr Space Sci, St Louis, MO 63110 USA. RI Hauck, Steven/A-7865-2008 OI Hauck, Steven/0000-0001-8245-146X NR 28 TC 300 Z9 301 U1 7 U2 30 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 30 PY 2001 VL 291 IS 5513 BP 2587 EP 2591 DI 10.1126/science.1058701 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 417XP UT WOS:000167861000037 PM 11283367 ER PT J AU Tabazadeh, A Jensen, EJ Toon, OB Drdla, K Schoeberl, MR AF Tabazadeh, A Jensen, EJ Toon, OB Drdla, K Schoeberl, MR TI Role of the stratospheric polar freezing belt in denitrification SO SCIENCE LA English DT Article ID NITRIC-ACID TRIHYDRATE; CLOUD FORMATION; ANTARCTIC STRATOSPHERE; HYDROGEN-CHLORIDE; PARTICLE-SIZE; WINTER; OZONE; HNO3; AEROSOLS; RECOVERY AB Homogeneous freezing of nitric acid hydrate particles can produce a polar freezing belt in either hemisphere that can cause denitrification. Computed denitrification profiles for one Antarctic and two Arctic cold winters are presented. The vertical range over which denitrification occurs is normally quite deep in the Antarctic but limited in the Arctic. A 4 kelvin decrease in the temperature of the Arctic stratosphere due to anthropogenic and/or natural effects can trigger the occurrence of widespread severe denitrification. Ozone loss is amplified in a denitrified stratosphere, so the effects of falling temperatures in promoting denitrification must be considered in assessment studies of ozone recovery trends. C1 NASA, Ames Res Ctr, Div Earth Sci, Moffett Field, CA 94035 USA. Univ Colorado, Program Atmospher & Ocean Sci, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Tabazadeh, A (reprint author), NASA, Ames Res Ctr, Div Earth Sci, MS-245-4, Moffett Field, CA 94035 USA. NR 32 TC 84 Z9 83 U1 0 U2 3 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 30 PY 2001 VL 291 IS 5513 BP 2591 EP 2594 DI 10.1126/science.1057228 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 417XP UT WOS:000167861000038 PM 11283368 ER PT J AU Behrenfeld, MJ Randerson, JT McClain, CR Feldman, GC Los, SO Tucker, CJ Falkowski, PG Field, CB Frouin, R Esaias, WE Kolber, DD Pollack, NH AF Behrenfeld, MJ Randerson, JT McClain, CR Feldman, GC Los, SO Tucker, CJ Falkowski, PG Field, CB Frouin, R Esaias, WE Kolber, DD Pollack, NH TI Biospheric primary production during an ENSO transition SO SCIENCE LA English DT Article ID 1997-98 EL-NINO; SOUTHERN-OCEAN; INTERANNUAL VARIATIONS; EQUATORIAL PACIFIC; SATELLITE; SURFACE; MODEL; SEAWIFS; PHOTOSYNTHESIS; LIGHT AB The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) provides global monthly measurements of both oceanic phytoplankton chlorophyll biomass and light harvesting by land plants. These measurements allowed the comparison of simultaneous ocean and land net primary production (NPP) responses to a major El Nino to La Nina transition. Between September 1997 and August 2000, biospheric NPP varied by 6 petagrams of carbon per year (from 111 to 117 petagrams of carbon per year). Increases in ocean NPP were pronounced in tropical regions where EL Nino-Southern Oscillation (ENSO) impacts on upwelling and nutrient availability were greatest. Globally, land NPP did not exhibit a clear ENSO response, although regional changes were substantial. C1 NASA, Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. Univ Wales, Dept Geog, Swansea SA2 8PP, W Glam, Wales. Rutgers State Univ, Inst Marine & Coastal Sci, New Brunswick, NJ 08901 USA. Carnegie Inst Washington, Dept Plant Biol, Stanford, CA 94305 USA. Scripps Inst Oceanog, La Jolla, CA 92037 USA. RP Behrenfeld, MJ (reprint author), NASA, Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. RI Los, Sietse/G-8985-2012; Reboreda, Rosa/A-2518-2012; OI Los, Sietse/0000-0002-1325-3555 NR 28 TC 259 Z9 270 U1 10 U2 84 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 30 PY 2001 VL 291 IS 5513 BP 2594 EP 2597 DI 10.1126/science.1055071 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 417XP UT WOS:000167861000039 PM 11283369 ER PT J AU Lobell, DB Asner, GP Law, BE Treuhaft, RN AF Lobell, DB Asner, GP Law, BE Treuhaft, RN TI Subpixel canopy cover estimation of coniferous forests in Oregon using SWIR imaging spectrometry SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LEAF-AREA INDEX; SPECTRAL MIXTURE ANALYSIS; VEGETATION INDEX; SOIL-MOISTURE; UNDERSTORY VEGETATION; AVIRIS DATA; LAND-COVER; REFLECTANCE; ATMOSPHERE; VARIABILITY AB The percent cover of vegetation canopies is an important variable for many land-surface biophysical and biogeochemical models and serves as a useful measure of land cover change. Remote sensing methods to estimate the subpixel fraction of vegetation canopies with spectral mixture analysis (SMA) require knowledge of the reflectance properties of major land cover units, called endmembers. However, variability in endmember reflectance across space and time has limited the interpretation and general applicability of SMA approaches. In this study, a subpixel vegetation cover of coniferous forests in Oregon, United States, was successfully estimated by employing shortwave infrared reflectance measurements (SWIR2 region, 2080-2280 nm) collected by the NASA Airborne Visible Infrared Imaging Spectrometer (AVIRIS). The approach presented here, referred to as AutoSWIR [Asner- and Lobell, 2000], was originally developed for semiarid and arid environments and exploits the low SWIR2 variability of materials found in most ecosystems. SWIR2 field spectra from Oregon were compared with spectra from an arid systems database, revealing significant differences only for soil reflectance. However, SWIR2 variability remained low, as indicated by field spectra and principal component analysis, and AutoSWIR was then modified to use coniferous forest spectra collected in Oregon. Subsequent high spatial resolution estimates of forest canopy cover agreed well with estimates from low-altitude air photos (rms = 3%), demonstrating the successful extension of AutoSWIR to a coniferous forest ecosystem. The generality of AutoSWIR facilitates accurate estimates of vegetation cover that can be automatically retrieved from SWIR2 spectral measurements collected by forthcoming spaceborne imaging spectrometers such as NASA's New Millenium Program EO-1 Hyperion. These estimates can then be used to characterize landscape heterogeneity important for land-surface, atmospheric, and biogeochemical research. C1 Univ Colorado, Dept Geol Sci, Boulder, CO 80209 USA. Univ Colorado, Environm Studies Program, Boulder, CO 80309 USA. Oregon State Univ, Coll Forestry, Corvallis, OR 97331 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Univ Colorado, Dept Geol Sci, Campus Box 399,Benson Earth Sci Bldg, Boulder, CO 80209 USA. EM gregory.asner@colorado.edu RI Asner, Gregory/G-9268-2013; OI Asner, Gregory/0000-0001-7893-6421; Law, Beverly/0000-0002-1605-1203 NR 56 TC 24 Z9 26 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 27 PY 2001 VL 106 IS D6 BP 5151 EP 5160 DI 10.1029/2000JD900739 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 413XB UT WOS:000167635900003 ER PT J AU Whiteman, DN Evans, KD Demoz, B Starr, DO Eloranta, EW Tobin, D Feltz, W Jedlovec, GJ Gutman, SI Schwemmer, GK Cadirola, M Melfi, SH Schmidlin, FJ AF Whiteman, DN Evans, KD Demoz, B Starr, DO Eloranta, EW Tobin, D Feltz, W Jedlovec, GJ Gutman, SI Schwemmer, GK Cadirola, M Melfi, SH Schmidlin, FJ TI Raman lidar measurements of water vapor and cirrus clouds during the passage of Hurricane Bonnie SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article; Proceedings Paper CT 2nd AGU Chapman Conference on Water Vapor in the Climate System CY OCT 12-15, 1999 CL POTOMAC, MARYLAND SP Amer Geophysic Union ID EXTINCTION; SCATTERING; METHODOLOGY; TEMPERATURE; ABSORPTION; ATMOSPHERE; RETRIEVAL; PROFILES; HUMIDITY; AEROSOLS AB The NASA GSFC Scanning Raman Lidar (SRL) was stationed on Andros Island in the Bahamas during August-September 1998 as a part of the third Convection and Moisture Experiment (CAMEX 3) which focused on hurricane development and tracking. During the period August 21-24, Hurricane Bonnie passed near Andros Island and influenced the water vapor and cirrus cloud measurements acquired by the SRL. Two drying signatures related to the hurricane were recorded by the SRL and other sensors. Cirrus cloud optical depths (at 351 nm) were also measured during this period. Optical depth values ranged from less than 0.01 to 1.5, The influence of multiple scattering on these optical depth measurements was studied. A correction technique is presented which minimizes the influences of multiple scattering and derives information about cirrus cloud optical and physical properties. The UV/IR cirrus cloud optical depth ratio was estimated on the basis of a comparison of lidar and GOES 8 measurements. Simple radiative transfer model calculations compared with GOES satellite brightness temperatures indicate that satellite radiances are significantly affected by the presence of cirrus clouds if IR optical depths are similar to0.005 or greater. Using the International Satellite Cloud Climatology Project (ISCCP) detection threshold for cirrus clouds on the GOES data presented here, a high bias of up to 40% was found in the GOES precipitable water retrieval. C1 NASA, Goddard Space Flight Ctr, Earth Sci Directorate, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Catonsville, MD 21228 USA. Univ Wisconsin, Ctr Space Sci & Engn, Madison, WI 53706 USA. NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35812 USA. NOAA, Forecast Syst Lab, Golden, CO 80401 USA. RP Whiteman, DN (reprint author), NASA, Goddard Space Flight Ctr, Earth Sci Directorate, Greenbelt, MD 20771 USA. RI Demoz, Belay/N-4130-2014 NR 51 TC 49 Z9 49 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 27 PY 2001 VL 106 IS D6 BP 5211 EP 5225 DI 10.1029/2000JD900621 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 413XB UT WOS:000167635900009 ER PT J AU Escoffier, C Bates, JJ Chedin, A Rossow, WB Schmetz, J AF Escoffier, C Bates, JJ Chedin, A Rossow, WB Schmetz, J TI Comparison of upper tropospheric humidity retrievals from TOVS and Meteosat SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article; Proceedings Paper CT 2nd AGU Chapman Conference on Water Vapor in the Climate System CY OCT 12-15, 1999 CL POTOMAC, MARYLAND SP Amer Geophysic Union ID WATER-VAPOR CHANNEL; RELATIVE-HUMIDITY; SATELLITE; CALIBRATION; CLIMATOLOGY; BUDGET; FIELD AB Two different methods for retrieving upper tropospheric humidity (UTH) from the TIROS Operational Vertical Sounder (TOVS) instruments aboard NOAA polar orbiting satellites are presented and compared. The first one, from the Environmental Technology Laboratory, computed by J. J. Bates and D. L. Jackson, estimates UTH from a simplified radiative transfer analysis of the upper tropospheric infrared water vapor channel at 6.7 mum wavelength measured by High-resolution Infrared Radiation Sounder (HIRS). The second one results from a neural network analysis of the TOVS (HIRS and Microwave Sounding Unit (MSU)) data developed at the Laboratoire de Meteorologie Dynamique. Although the two methods give very similar retrievals in temperate regions (30 degrees -60 degreesN and S), the latter is larger by up to 16% in the tropics. The two data sets have also been compared with the UTH retrievals from infrared radiance measurements at 6.3 mum wavelength from the geostationary satellite Meteosat. These products are taken from the archive without any reprocessing that would take care of known biases. Since the Meteosat UTH in 1989 was confined to clear-sky areas, it has a dry bias. The differences observed among the three data sets can be explained. UTH computation is sensitive to assumed air temperature and humidity profiles. Despite the biases the spatial and temporal correlations are very good. Overall, the comparison of the two TOVS retrievals provides an assessment of the UTH uncertainties, about 15-25% (relative). With regard to the Meteosat UTH it is concluded that the archived product performs well in depicting spatial and temporal changes. For future quantitative analyses, a reprocessing of the Meteosat UTH is suggested. C1 Columbia Univ, Goddard Inst Space Studies, New York, NY 10025 USA. NOAA, ERL, Environm Technol Lab, Boulder, CO 80303 USA. Ecole Polytech, Meteorol Dynam Lab, F-91128 Palaiseau, France. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. European Org Exploitat Meteorol Satellites, D-64295 Darmstadt, Germany. RP Escoffier, C (reprint author), Columbia Univ, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. RI Bates, John/D-1012-2009; Rossow, William/F-3138-2015 OI Bates, John/0000-0002-8124-0406; NR 32 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 27 PY 2001 VL 106 IS D6 BP 5227 EP 5238 DI 10.1029/2000JD900553 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 413XB UT WOS:000167635900010 ER PT J AU Herman, JR Celarier, E Larko, D AF Herman, JR Celarier, E Larko, D TI UV 380 nm reflectivity of the Earth's surface, clouds and aerosols SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article; Proceedings Paper CT 2nd AGU Chapman Conference on Water Vapor in the Climate System CY OCT 12-15, 1999 CL POTOMAC, MARYLAND SP Amer Geophysic Union ID SATELLITE MEASUREMENTS; ULTRAVIOLET-RADIATION; TOTAL OZONE; ERBE DATA; TOMS; RADIANCES; ISCCP AB The 380 nm radiance measurements of the Total Ozone Mapping Spectrometer (TOMS) have been converted into a global data set of daily (1979-1992) Lambert equivalent reflectivities R of the Earth's surface and boundary layer (clouds, aerosols, surface haze, and snow/ice) and then corrected to R,, for the presence of partly clouded scenes. Since UV surface reflectivity is between 2 and 8% for both land and water during all seasons of the year (except for ice and snow cover), reflectivities larger than the surface value indicate the presence of clouds, haze, or aerosols in the satellite field of view. A statistical analysis of 14 years of daily reflectivity data shows that most snow-/ice-free scenes observed by TOMS have a reflectivity less than 10% for the majority of days during a year. The 380 nm reflectivity data show that the true surface reflectivity is 2-3% lower than the most frequently occurring reflectivity value for each TOMS scene as seen from space. Most likely the cause is a combination of frequently occurring boundary layer water and/or aerosol haze. For most regions the observation of extremely clear conditions needed to estimate the surface reflectivity from space is a comparatively rare occurrence. Certain areas (e.g., Australia, southern Africa, portions of northern Africa) are cloud-free more than 80% of the year, which exposes these regions to larger amounts of UV radiation than at comparable latitudes in the Northern Hemisphere. Regions over rain forests, jungle areas, Europe and Russia, the bands surrounding the Arctic and Antarctic regions, and many ocean areas have significant cloud cover (R > 15%) more than half of each year. In the low to middle latitudes the areas with the heaviest cloud cover (highest reflectivity for most of the year) are the forest areas of northern South America, southern Central America, the jungle areas of equatorial Africa, and high mountain regions such as the Himalayas or the Andes. The TOMS reflectivity data show both the presence of large nearly clear ocean areas and the effects of the major ocean currents on cloud production. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. SGT Corp, Greenbelt, MD 20770 USA. Raytheon ITSS, Lanham, MD 20706 USA. RP Herman, JR (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. OI Herman, Jay/0000-0002-9146-1632 NR 26 TC 30 Z9 30 U1 2 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 27 PY 2001 VL 106 IS D6 BP 5335 EP 5351 DI 10.1029/2000JD900584 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 413XB UT WOS:000167635900017 ER PT J AU Herman, JR Larko, D Celarier, E Ziemke, J AF Herman, JR Larko, D Celarier, E Ziemke, J TI Changes in the Earth's UV reflectivity from the surface, clouds, and aerosols SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article; Proceedings Paper CT 2nd AGU Chapman Conference on Water Vapor in the Climate System CY OCT 12-15, 1999 CL POTOMAC, MARYLAND SP Amer Geophysic Union ID ULTRAVIOLET-RADIATION; SATELLITE ESTIMATION; OPTICAL-THICKNESS; TOTAL OZONE; TOMS; IRRADIANCE AB Measurements of the Earth's 380 nm UV reflectivity combine the effects of surface reflectivity, aerosols, haze, cloud optical thickness, and the fraction of the scene covered by clouds. Changes in UV cloud and aerosol reflectivity would imply similar changes over a wide range of wavelengths, UV, visible, and near infrared (at least 0.3 to 2 mum), affecting both the transmission of radiation to the Earth's surface and the reflection back to space. Using the TOMS (Total Ozone Mapping Spectrometer) 380 nm reflectivity data, the 14-year annual mean power reflected back to space is 385.3 +/- 31 W/m(2), mostly by clouds, aerosols, and snow/ice. On the basis of measured long-term changes in global reflectivity, it is estimated that there is an additional 2.8 +/- 2.8 W/m(2) per decade reflected back to space (2 standard deviation error estimate) during the TOMS observing period of 1979-1992. Since the 380 nm surface reflectivity is low (2-8%) over most surfaces, water and land, the observed reflectivity changes are mostly caused by changes in the amount of snow/ice, cloudiness, and aerosols. Time series analysis of TOMS reflectivity over the period from 1979 to 1992 shows that there were no significant changes in annually averaged zonal-average reflectivity at latitudes within 60 degreesS-60 degreesN, even though there were changes at higher latitudes (e.g., 3% per decade, in reflectivity units, between 60 degreesN and 70 degreesN). When the effects of the 11.3-year solar cycle and ENSO (El Nino-Southern Oscillation) are removed from the data, statistically significant reflectivity changes are observed poleward of both 40 degreesS and 40 degreesN. The presence of a statistically significant 11.3-year periodicity in the reflectivity time series correlates with the solar cycle and suggests a possible Sun-weather relationship. There are significant regional changes in reflectivity R over land and ocean areas that affect the amount of solar radiation reaching the surface. The largest of these regions have decreases in R of 3 to 6 +/- 1% per decade in central Europe, the western United States, central China, and western Russia. These decreases are offset by increases in the same latitude bands mostly over the oceans. The largest regions showing an increase in R are off the western coast of South America (near Chile and Peru), 5 to 8 +/- 1%/decade and over the Weddell Sea in Antarctica of 10%/decade, but no change over the ice shelf and continent. The largest increase in R occurs over the ocean just to the north of Antarctica. This change is important because it reduces UV radiation overall (290-400 nm) and partially offsets the effect of the increased amount of UV-B radiation (290-320 nm) caused by decreasing Antarctic ozone. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Raytheon STX Corp, Lanham, MD 20706 USA. Software Corp Amer, Beltsville, MD USA. RP Herman, JR (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Code 916, Greenbelt, MD 20771 USA. OI Herman, Jay/0000-0002-9146-1632 NR 25 TC 22 Z9 22 U1 1 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 27 PY 2001 VL 106 IS D6 BP 5353 EP 5368 DI 10.1029/2000JD900435 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 413XB UT WOS:000167635900018 ER PT J AU Sleep, NH Zahnle, K Neuhoff, PS AF Sleep, NH Zahnle, K Neuhoff, PS TI Initiation of clement surface conditions on the earliest Earth SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID THERMODYNAMIC PROPERTIES; ASTEROID IMPACTS; OCEANIC-CRUST; LAYER 2A; EVOLUTION; MANTLE; SYSTEM; RIDGE; ASSIMILATION; ATMOSPHERE AB In the beginning the surface of the Earth was extremely hot, because the Earth as we know it is the product of a collision between two planets, a collision that also created the Moon. Most of the heat within the very young Earth was lost quickly to space while the surface was still quite hot. As it cooled, the Earth's surface passed monotonically through every temperature regime between silicate vapor to liquid water and perhaps even to ice, eventually reaching an equilibrium with sunlight. Inevitably the surface passed through a time when the temperature was around 100 degreesC at which modern thermophile organisms live. How long this warm epoch lasted depends on how long a thick greenhouse atmosphere can be maintained by heat flow from the Earth's interior, either directly as a supplement to insolation, or indirectly through its influence on the nascent carbonate cycle. In both cases, the duration of the warm epoch would have been controlled by processes within the Earth's interior where buffering by surface conditions played little part. A potentially evolutionarily significant warm period of between 10(5) and 10(7) years seems likely, which nonetheless was brief compared to the vast expanse of geological time. C1 Stanford Univ, Dept Geophys, Stanford, CA 94305 USA. Stanford Univ, Dept Geog & Environm Sci, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Sleep, NH (reprint author), Stanford Univ, Dept Geophys, Stanford, CA 94305 USA. NR 49 TC 84 Z9 84 U1 0 U2 21 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 27 PY 2001 VL 98 IS 7 BP 3666 EP 3672 DI 10.1073/pnas.071045698 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 417KG UT WOS:000167833700012 PM 11259665 ER PT J AU Saltzberg, D Gorham, P Walz, D Field, C Iverson, R Odian, U Resch, G Schoessow, P Williams, D AF Saltzberg, D Gorham, P Walz, D Field, C Iverson, R Odian, U Resch, G Schoessow, P Williams, D TI Observation of the Askaryan effect: Coherent microwave Cherenkov emission from charge asymmetry in high-energy particle cascades SO PHYSICAL REVIEW LETTERS LA English DT Article ID RADIO PULSES; NEUTRINOS; SHOWERS; ICE AB We present the first direct experimental evidence for the charge excess in high-energy particle showers and corresponding radio emission predicted nearly 40 years ago by Askaryan. We directed picosecond pulses of GeV bremsstrahlung photons at the SLAG Final Focus Test Beam into a 3.5 ton silica sand target, producing electromagnetic showers several meters long. A series of antennas spanning 0.3 to 6 GHz detected strong, subnanosecond radio-frequency pulses produced by the showers. Measurements of the polarization, coherence, timing, field strength vs shower depth, and field strength vs frequency are completely consistent with predictions. These measurements thus provide strong support for experiments designed to detect high-energy cosmic rays such as neutrinos via coherent radio emission from their cascades. C1 Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Stanford Univ, Stanford Linear Accelerator Ctr, Stanford, CA 94309 USA. Argonne Natl Lab, Argonne, IL 60439 USA. RP Saltzberg, D (reprint author), Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. NR 23 TC 166 Z9 168 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 MAR 26 PY 2001 VL 86 IS 13 BP 2802 EP 2805 DI 10.1103/PhysRevLett.86.2802 PG 4 WC Physics, Multidisciplinary SC Physics GA 414YD UT WOS:000167693000026 PM 11290043 ER PT J AU Morris, RV Golden, DC Ming, DW Shelfer, TD Jorgensen, LC Bell, JF Graff, TG Mertzman, SA AF Morris, RV Golden, DC Ming, DW Shelfer, TD Jorgensen, LC Bell, JF Graff, TG Mertzman, SA TI Phyllosilicate-poor palagonitic dust from Mauna Kea Volcano (Hawaii): A mineralogical analogue for magnetic Martian dust? SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID PRIMITIVE CLAY PRECURSORS; LOW-TEMPERATURE OXIDATION; MARS PATHFINDER; REFLECTANCE SPECTRA; IRON-OXIDES; SOIL; HEMATITE; MOSSBAUER; OXISOLS; SURFACE AB The mineralogical and elemental composition of dust size fractions (<2 and <5 mum) of eight samples of phyllosilicate-poor palagonitic tephra from the upper slopes of Mauna Kea Volcano (Hawaii) were studied by X-ray diffraction (XRD), X-ray fluorescence (XRF), visible and near-IR reflectance spectroscopy, Mossbauer spectroscopy, magnetic properties methods, and transmission electron microscopy (TEM). The palagonitic dust samples are spectral analogues of Martian bright regions at visible and near-IR wavelengths. The crystalline phases in the palagonitic dust are, in variable proportions, plagioclase feldspar, Ti-containing magnetite, minor pyroxene, and trace hematite. No basal reflections resulting from crystalline phyllosilicates were detected in XRD data. Weak, broad XRD peaks corresponding to X-ray amorphous phases (allophane, nanophase ferric oxide (possibly ferrihydrite), and, for two samples, hisingerite) were detected as oxidative alteration products of the glass; residual unaltered glass was also present. Mossbauer spectroscopy showed that the iron-bearing phases are nanophase ferric oxide, magnetite/titanomagnetite, hematite, and minor glass and ferrous silicates. Direct observation by TEM showed that the crystalline and X-ray amorphous phases observed by XRD and Mossbauer are normally present together in composite particles and not normally present as discrete single-phase particles. Ti-bearing magnetite occurs predominantly as 5-150 nm particles embedded in noncrystalline matrix material and most likely formed by crystallization from silicate liquids under conditions of rapid cooling during eruption and deposition of glassy tephra and prior to palagonitization of glass. Rare spheroidal halloysite was observed in the two samples that also had XRD evidence for hisingerite. The saturation magnetization J(s) and low-field magnetic susceptibility for bulk dust range from 0.19 to 0.68 Am-2/kg and 3.4x10(-6) to 15.5x10(-6) m(3)/kg at 293 K, respectively. Simulation of the Mars Pathfinder Magnet Array (MA) experiment was performed on Mauna Kea Volcano in areas with phyllosilicate-poor palagonitic dust and with copies of the Pathfinder MA. On the basis of the magnetic properties of dust collected by all five MA magnets and the observation that the Pathfinder MAs collected dust on the four strongest magnets, the value for the saturation magnetization of Martian dust collected in the MA experiments is revised downward from 4+/-2 Am-2/kg to 2.5+/-1.5 Am-2/kg. The revised value corresponds to 2.7+/-1.6 wt % magnetite if the magnetic mineral is magnetite (using J(s) = 92 Am-2/kg for pure magnetite, Fe3O4) or to 5.0+/-3.0 to 3.4+/-2.0 wt % maghemite if the magnetic mineral is pure maghemite (using J(s) = 50 to 74 Am-2/kg for pure maghemite, gamma -Fe2O3). Comparison of the magnetic properties of bulk Mauna Kea palagonitic dust to those for dust collected by MA magnets shows that the MA magnets extracted (culled) a subset (25-34 wt %) of composite magnetic particles from bulk dust. The extent of culling of Martian dust is not well constrained. Because the Mauna Kea palagonitic dust satisfies the essential constraints of the Pathfinder magnetic properties experiment (composite and magnetic particles capable of being collected by five MA magnets), a working hypothesis for the strongly magnetic mineral present in Martian dust and soil is magnetite (possibly Ti-bearing) formed by rapid crystallization from silicate liquids having volcanic and/or impact origins. Subsequent palagonitization of the glass produces the nanophase ferric oxide phases that dominate the spectral properties of Martian bright regions at visible and near-iii wavelengths. Magnetic and phyllosilicate-poor palagonitic dust from Mauna Kea Volcano is thus a spectral and magnetic analogue for magnetic Martian dust. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Hernandez Engn Inc, Houston, TX 77058 USA. Lockheed Martin Space Operat Co, Houston, TX 77078 USA. Univ Copenhagen, Niels Bohr Inst Astron Phys & Geophys, Orsted Lab, DK-2100 Copenhagen O, Denmark. Cornell Univ, Dept Astron, Ithaca, NY USA. Franklin & Marshall Coll, Dept Geosci, Lancaster, PA USA. RP Morris, RV (reprint author), NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. EM richard.v.morris1@jsc.nasa.gov NR 94 TC 68 Z9 68 U1 1 U2 19 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 2001 VL 106 IS E3 BP 5057 EP 5083 DI 10.1029/2000JE001328 PG 27 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 413HL UT WOS:000167606900003 ER PT J AU Cho, JYK Juarez, MD Ingersoll, AP Dritschel, DG AF Cho, JYK Juarez, MD Ingersoll, AP Dritschel, DG TI A high-resolution, three-dimensional model of Jupiter's Great Red Spot SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID NUMERICAL-SIMULATION; POTENTIAL VORTICITY; OUTER PLANETS; ATMOSPHERE; FLOW AB The turbulent flow at the periphery of the Great Red Spot (GRS) contains many fine-scale filamentary structures, while the more quiescent core: bounded by a narrow high-velocity ring, exhibits organized, possibly counterrotating, motion. Past studies have neither been able to capture this complexity nor adequately study the effects of vertical stratification L-R(z) on the GRS. We present results from a series of high-resolution, three-dimensional simulations that advect the dynamical tracer, potential vorticity. The detailed flow is successfully captured with a characteristic value of L-R approximate to 2000 km, independent of the precise vertical stratification profile. C1 CALTECH, Jet Prop Lab, Div Geol & Planetary Sci, Pasadena, CA 91109 USA. Univ St Andrews, Inst Math, St Andrews KY16 9SS, Fife, Scotland. Natl Res Council, Jet Prop Lab, Pasadena, CA USA. RP Cho, JYK (reprint author), Spectral Sci Inc, 99 S Bedford St,7, Burlington, MA 01803 USA. RI Dritschel, David/D-8131-2013; Dritschel, David/M-8200-2014 OI Dritschel, David/0000-0001-6489-3395 NR 18 TC 25 Z9 25 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-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 2001 VL 106 IS E3 BP 5099 EP 5105 DI 10.1029/2000JE001287 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 413HL UT WOS:000167606900005 ER PT J AU Schwenke, DW AF Schwenke, DW TI Beyond the potential energy surface: Ab initio corrections to the Born-Oppenheimer approximation for H2O SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID MOLECULES; BREAKDOWN; WATER AB It is customary when computing re-vibrational transitions in molecules to invoke the Born-Oppenheimer separation between nuclear and electronic motion. However, it is known from accurate calculations on H-2(+) and H-2 that the first-order (diagonal adiabatic) and second-order (nonadiabatic) corrections are not negligible and are both important. In the present work, we have made an ab initio implementation of the Bunker and Moss formalism for the nonadiabatic correction and applied it to H-2 and H2O. From comparison to accurate calculations for H-2, we find that we can obtain good results for the nonadiabatic correction using Cl singles to treat the electronically excited states if we scale the results, but we must go beyond the SCF approximation to obtain an accurate diagonal adiabatic correction. For H2O, we find that the first-order correction is more important than the second-order correction for bending energy levels, but the second-order correction is more important than the first-order correction for stretching energy levels. The correction to rotational levels is also significant. Thus, first- and second-order corrections are vital for accurate ab initio predictions of transition frequencies. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Schwenke, DW (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RI schwenke, david/I-3564-2013 NR 20 TC 91 Z9 92 U1 0 U2 19 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 22 PY 2001 VL 105 IS 11 BP 2352 EP 2360 DI 10.1021/jp0032513 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 413VN UT WOS:000167632400030 ER PT J AU Nalli, NR Smith, WL Huang, B AF Nalli, NR Smith, WL Huang, B TI Quasi-specular model for calculating the reflection of atmospheric-emitted infrared radiation from a rough water surface SO APPLIED OPTICS LA English DT Article ID SEA-SURFACE; TEMPERATURE; OCEAN; EMISSIVITY; WINDOW; MU AB A numerical model is developed for computation of the reflection of atmospheric-emitted IR radiance from a wind-roughened water body. The model assumes the Kirchhoff approximation for rough surface scattering. This allows application of the postulates of geometrical optics to determine the reflection of rays from an ensemble of wave facets. We;performed the hemispherical integration with Gaussian quadrature by using an uplooking fast transmittance model. This calculation is simplified further through the concept of a reflection-diffusivity angle. The model compares favorably with observed radiance spectra obtained from the Marine-Atmospheric Emitted Radiance Interferometer during the Combined Sensor Program research cruise. (C) 2001 Optical Society of America. C1 Univ Wisconsin, Dept Atmospher & Ocean Sci, Madison, WI 53706 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Nalli, NR (reprint author), NOAA, Natl Environm Satellite Data & Informat Serv, Washington, DC 20233 USA. RI Nalli, Nicholas/F-6731-2010 OI Nalli, Nicholas/0000-0002-6914-5537 NR 36 TC 15 Z9 15 U1 0 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 MAR 20 PY 2001 VL 40 IS 9 BP 1343 EP 1353 DI 10.1364/AO.40.001343 PG 11 WC Optics SC Optics GA 413RX UT WOS:000167626700006 PM 18357120 ER PT J AU Yang, P Gao, BC Baum, BA Hu, YX Wiscombe, WJ Mishchenko, MI Winker, DM Nasiri, SL AF Yang, P Gao, BC Baum, BA Hu, YX Wiscombe, WJ Mishchenko, MI Winker, DM Nasiri, SL TI Asymptotic solutions for optical properties of large particles with strong absorption SO APPLIED OPTICS LA English DT Article ID HEXAGONAL ICE CRYSTALS; DIFFERENCE TIME-DOMAIN; SOLAR RADIATIVE-TRANSFER; LIGHT-SCATTERING; CIRRUS CLOUDS; SINGLE-SCATTERING; PARAMETERIZATION; COMPUTATION; MODELS; APPROXIMATION AB The transverse wave condition is not applicable to the refracted electromagnetic wave within the context of geometrical optics when absorption is involved. Either the TM or the TE wave condition can be assumed for the wave to locally satisfy the electromagnetic boundary condition in a ray-tracing calculation. The assumed wave mode affects both the reflection and the refraction coefficients. As a result, nonunique solutions for these coefficients are inevitable. In this study the appropriate solutions for the Fresnel reflection-refraction coefficients are identified in light-scattering calculations based on the ray-tracing technique. In particular, a 3 x 2 refraction or transmission matrix is derived to account for the inhomogeneity of the refracted wave in an absorbing medium. An asymptotic solution that completely includes the effect of medium absorption on Fresnel coefficients is obtained for the scattering properties of a general polyhedral particle. Numerical results are presented for hexagonal plates and columns with both preferred and random orientations. (C) 2001 Optical Society of America. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD 20706 USA. USN, Res Lab, Remote Sensing Div, Washington, DC 20375 USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Univ Wisconsin, Cooperat Inst Meteorol Satellite Studies, Madison, WI 53706 USA. RP Yang, P (reprint author), NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. EM pyang@climate.gsfc.nasa.gov RI Yang, Ping/B-4590-2011; Baum, Bryan/B-7670-2011; Nasiri, Shaima/C-8044-2011; Wiscombe, Warren/D-4665-2012; Hu, Yongxiang/K-4426-2012; Mishchenko, Michael/D-4426-2012 OI Baum, Bryan/0000-0002-7193-2767; Wiscombe, Warren/0000-0001-6844-9849; NR 43 TC 16 Z9 16 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 2001 VL 40 IS 9 BP 1532 EP 1547 DI 10.1364/AO.40.001532 PG 16 WC Optics SC Optics GA 413RX UT WOS:000167626700032 PM 18357146 ER PT J AU Bower, GA Green, RF Bender, R Gebhardt, K Lauer, TR Magorrian, J Richstone, DO Danks, A Gull, T Hutchings, J Joseph, C Kaiser, ME Weistrop, D Woodgate, B Nelson, C Malumuth, EM AF Bower, GA Green, RF Bender, R Gebhardt, K Lauer, TR Magorrian, J Richstone, DO Danks, A Gull, T Hutchings, J Joseph, C Kaiser, ME Weistrop, D Woodgate, B Nelson, C Malumuth, EM TI Evidence of a supermassive black hole in the galaxy NGC 1023 from the nuclear stellar dynamics SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : elliptical and lenticular, cD; galaxies : individual (NGC 1023); galaxies : kinematics and dynamics; galaxies : nuclei ID ELLIPTIC GALAXIES; GALACTIC NUCLEI; CENTERS; DISTRIBUTIONS; HST; EVOLUTION; PROFILES; EMISSION; MODELS; MASS AB We analyze the nuclear stellar dynamics of the SB0 galaxy NGC 1023, utilizing observational data both from the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope and from the ground. The stellar kinematics measured from these long-slit spectra show rapid rotation (V approximate to 70 km s(-1) at a distance of 0."1 = 4.9 pc from the nucleus) and increasing velocity dispersion toward the nucleus (where sigma = 295 +/- 30 km s(-1)). We model the observed stellar kinematics assuming an axisymmetric mass distribution with both two and three integrals of motion. Both modeling techniques point to the presence of a central dark compact mass (which presumably is a supermassive black hole) with confidence greater than 99%. The isotropic two-integral models yield a best-fitting black hole mass of (6.0 +/- 1.4) x 10(7) M. and mass-to-light ratio (M/L-V) of 5.38 +/- 0.08, and the goodness of fit (chi (2)) is insensitive to reasonable values for the galaxy's inclination. The three-integral models, which nonparametrically Dt the observed line-of-sight velocity distribution as a function of position in the galaxy, suggest a black hole mass of (3.9 +/- 0.4) x 10(7) M. and M/L-V of 5.56 +/- 0.02 (internal errors), and the edge-on models are vastly superior fits over models at other inclinations. The internal dynamics in NGC 1023 as suggested by our best-Dt three-integral model shows that the velocity distribution function at the nucleus is tangentially anisotropic, suggesting the presence of a nuclear stellar disk. The nuclear line-of-sight velocity distribution has enhanced wings at velocities greater than or equal to 600 km s(-1) from systemic, suggesting that perhaps we have detected a group of stars very close to the central dark mass. C1 Kitt Peak Natl Observ, Natl Opt Astron Observ, Tucson, AZ 85726 USA. Univ Sternwarte, D-81679 Munich, Germany. Univ Texas, Dept Astron, Austin, TX 78712 USA. Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England. Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA. NASA, Raytheon ITSS, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Natl Res Council Canada, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. Rutgers State Univ, Dept Phys & Astron, Piscataway, NJ 08855 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Nevada, Dept Phys, Las Vegas, NV 89154 USA. RP Bower, GA (reprint author), Kitt Peak Natl Observ, Natl Opt Astron Observ, POB 26732, Tucson, AZ 85726 USA. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 29 TC 58 Z9 59 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 2001 VL 550 IS 1 BP 75 EP 86 DI 10.1086/319730 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 417YN UT WOS:000167863200008 ER PT J AU Weaver, KA Gelbord, J Yaqoob, T AF Weaver, KA Gelbord, J Yaqoob, T TI Variable iron K alpha lines in Seyfert 1 galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (Markarian 279); galaxies : nuclei; galaxies : Seyfert; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; X-RAY REFLECTION; ASCA; MCG-6-30-15; VARIABILITY; EMISSION; NGC-4151; QUASARS; DISK AB We find that variability of the iron K-alpha line is common in Seyfert 1 galaxies. Using data from the ASCA archive for objects that have been observed more than once during the mission, we study the time-averaged spectra from individual observations, thereby probing variability on timescales that range from days to years. Since the statistics of the data do not warrant searches for line variability in terms of a complex physical model, we use a simple Gaussian to model the gross shape of the line and then use the centroid energy, intensity, and equivalent width as robust indicators of changes in the line profile. We find that similar to 70% of Seyfert 1 galaxies (10 out of 15) show variability in at least one of these parameters : the centroid energy, intensity, and equivalent width vary in six, four, and eight sources, respectively. Because of the low signal-to-noise ratio, limited sampling, and time averaging, we consider these results to represent lower limits to the rate of incidence of variability. In most cases changes in the line do not appear to track changes in the continuum. In particular, we find no evidence for variability of the line intensity in NGC 4151, suggesting an origin in a region larger than the putative accretion disk, where most of the iron line has been thought to originate. Mrk 279 is investigated on short timescales. The time-averaged effective line energy (as measured by the Gaussian center energy, which is weighted by emission in the entire line profile) is 6.5 keV in the galaxy rest frame. As the continuum flux increases by 20% in a few hours, the Fe K line responds within similar to 10,000 s, with the effective line energy increasing by 0.22 keV (similar to 10,500 km s(-1)). We also examine the ROSAT PSPC spectrum of Mrk 279 but find inconsistencies with ASCA. Problems with the ASCA and ROSAT calibration that affect simultaneous spectral fits at low energies are discussed in an appendix. C1 NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RP Weaver, KA (reprint author), NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 35 TC 62 Z9 65 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 2001 VL 550 IS 1 BP 261 EP 279 DI 10.1086/319713 PN 1 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 417YN UT WOS:000167863200024 ER PT J AU Desch, SJ Mouschovias, TC AF Desch, SJ Mouschovias, TC TI The magnetic decoupling stage of star formation SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : magnetic fields; MHD; plasmas; stars : formation; solar system : formation ID CYLINDRICALLY SYMMETRICAL CONTRACTION; DENSE INTERSTELLAR CLOUDS; RADIATION MAGNETOHYDRODYNAMICS CODE; TIME-DEPENDENT SOLUTION; YOUNG STELLAR OBJECTS; LOW-MASS PROTOSTARS; 2 SPACE DIMENSIONS; AMBIPOLAR DIFFUSION; MOLECULAR CLOUDS; AXISYMMETRICAL SOLUTIONS AB We present the results of the first numerical calculations to model magnetic decoupling in a collapsing molecular cloud core. Magnetic decoupling is the stage during which the motion of the neutrals ceases to significantly affect the magnetic field strength and the magnetic field ceases to significantly affect this motion. We have analyzed the resistivity of a weakly ionized, magnetic gas, and we have separated the contributions of ohmic dissipation and ambipolar diffusion. The chemical model used to determine the abundances of ionized particles accounts for, among other things, a distribution of grain radii. The evolution of an axisymmetric, magnetic molecular cloud core is followed from central densities of 300 to 2x10(12) cm(-3). Typically, magnetic decoupling begins at a central density of 3x10(10) cm(-3) and is complete by a density of 2x10(12) cm(-3). We find that the mechanism responsible for magnetic decoupling is ambipolar diffusion, not ohmic dissipation, and that decoupling precedes the formation of a central stellar object. When the central density is a few times 10(12) cm(-3), a nearly uniform magnetic field of B(dec) approximate to 0.1 G extends over a region approximate to 20 AU in radius that contains a mass approximate to0.01 M(.). This value of B(dec) is consistent with measurements of remanent magnetization in meteorites. Magnetic decoupling at this stage is not accompanied by hydromagnetic shocks. We estimate that the "magnetic flux problem II of star formation is resolved by ambipolar diffusion before the magnetic field is refrozen in the matter because of thermal ionization. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Illinois, Dept Phys, Urbana, IL 61801 USA. Univ Illinois, Dept Astron, Urbana, IL 61801 USA. RP Desch, SJ (reprint author), Carnegie Inst Washington, Dept Terr Magnetism, 5241 Broad Branch Rd NW, Washington, DC 20015 USA. NR 78 TC 72 Z9 72 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 20 PY 2001 VL 550 IS 1 BP 314 EP 333 DI 10.1086/319703 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 417YN UT WOS:000167863200029 ER PT J AU Marsden, D Lingenfelter, RE Rothschild, RE Higdon, JC AF Marsden, D Lingenfelter, RE Rothschild, RE Higdon, JC TI Nature versus nurture: The origin of soft gamma-ray repeaters and anomalous X-ray pulsars SO ASTROPHYSICAL JOURNAL LA English DT Review DE gamma rays : observations; pulsars : general; stars : neutron; supernova remnants; X-rays : stars ID MAGNETIZED NEUTRON-STARS; INTERPLANETARY NETWORK LOCALIZATION; SUPERNOVA REMNANT CANDIDATES; HIGH-RESOLUTION RADIO; INTER-STELLAR MEDIUM; MHZ MASER EMISSION; 1979 MARCH 5; H-II REGION; SGR 1900+14; 1E 2259+586 AB Soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are young and radio-quiet X-ray pulsars that have been rapidly spun-down to slow spin periods clustered in the range 5-12 s. Most of these unusual pulsars also appear to be associated with supernova shell remnants (SNRs) with typical ages less than 30 kyr. By examining the sizes of these remnants versus their ages, we demonstrate that the interstellar media that surrounded the SGR and AXP progenitors and their SNRs were unusually dense compared to the environments around most young radio pulsars and SNRs. We explore the implications of this evidence on magnetar and propeller-based models for the rapid spin-down of SGRs and AXPs. We find that evidence of dense environments is not consistent with the magnetar model unless a causal link can be shown between the development of magnetars and the external interstellar medium. Propeller-driven spin-down by fossil accretion disks for SGRs and AXPs appears to be consistent with dense environments since the environment can facilitate the formation of such a disk. This may occur in two ways: (1) formation of a "pushback" disk from the innermost ejecta pushed back by prompt reverse shocks from supernova remnant interactions with massive progenitor wind material stalled in dense surrounding gas or (2) acquisition of disks by a high-velocity neutron stars, which may be able to capture sufficient amounts of comoving outflowing ejecta slowed by the prompt reverse shocks in dense environments. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. Claremont Coll, WM Keck Sci Ctr, Claremont, CA 91711 USA. RP NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 131 TC 78 Z9 82 U1 1 U2 3 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 2001 VL 550 IS 1 BP 397 EP 409 DI 10.1086/319701 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 417YN UT WOS:000167863200037 ER PT J AU Bohm-Vitense, E Mena-Werth, J Carpenter, KG Robinson, RD AF Bohm-Vitense, E Mena-Werth, J Carpenter, KG Robinson, RD TI MgII emission lines of Hyades F stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : chromospheres; ultraviolet : stars ID MAIN-SEQUENCE; MAGNETIC-STRUCTURE; COOL STARS; K-LINE; CHROMOSPHERES; EVOLUTION; DISTANCE; FLUXES AB With the Hubble Space Telescope (HST) we have observed Hyades F stars, using the Space Telescope Imaging Spectrograph (STIS), in order to get more information about the heating mechanism(s) for the chromospheres and transition layers and their dependence on rotation and age. In this paper we study the Mg II lines at 2800 Angstrom. We include earlier observations with the International Ultraviolet Explorer (IUE) satellite. The Mg II emission lines become observable for B-V >0.3. The emission line fluxes increase steeply until B-V similar to 0.40. For single stars there is a steep decrease in flux between B-V = 0.41 and B-V = 0.44, similar to the behavior of the Ca II emission line cores. For larger B-V the Mg II emission line fluxes again increase, but much more slowly than for the Ca II lines. Generally, the low point of the emission is reached between B-V = 0.43 and B-V = 0.45, i.e., similar to the Ca II emission cores. For the Hyades F stars there appears to be a difference between the emissions for single stars and those for binaries. We find that for Hyades stars with surface line fluxes larger than 10(6) ergs cm(-2) s(-1) the emission line fluxes decrease with increasing v sin i. For smaller fluxes they may increase with increasing v sin i. We have only three stars that perhaps show this. We study the flux ratios of the Mg II k and h lines at 2795.7 and 2802.5 Angstrom in order to determine where the lines fall on the AZ curve of growth. For the earliest F stars studied here the ratio is close to 2, as expected for optically thin lines. Generally, it seems that the optical depths in the line centers are less than 10. There remain problems in understanding the size of the line widths. We discuss the interpretation of the Wilson-Bappu effect. For the Hyades F stars there is a strong dependence of the line width on the effective temperature. C1 Univ Washington, Dept Astron, Seattle, WA 98195 USA. Univ Nebraska, Dept Phys, Kearney, NE 68849 USA. NASA, LASP, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Dept Phys, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. RP Bohm-Vitense, E (reprint author), Univ Washington, Dept Astron, Box 351 580, Seattle, WA 98195 USA. NR 25 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 2001 VL 550 IS 1 BP 457 EP 469 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 417YN UT WOS:000167863200042 ER PT J AU Ehrenfreund, P Bernstein, MP Dworkin, JP Sandford, SA Allamandola, LJ AF Ehrenfreund, P Bernstein, MP Dworkin, JP Sandford, SA Allamandola, LJ TI The photostability of amino acids in space SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : ISM : lines and bands; ISM : abundances; ISM : molecules; methods : laboratory; molecular processes ID INTERSTELLAR-MEDIUM; ORGANIC-MOLECULES; RADIATION-FIELD; UV-RADIATION; EARLY EARTH; CLOUDS; GLYCINE; SEARCH; COMETS; MATTER AB Organic compounds observed in the interstellar medium and in solar system bodies are of particular importance for revealing the chemistry that may have led to life's origin. Among these compounds, amino acids may have played a crucial role since they are basic components of proteins, which are the essential constituents of all organisms. We present laboratory studies testing the stability of amino acids against ultraviolet (UV) photolysis. Two biological and two nonbiological amino acids have been irradiated in frozen Ar, N(2), and H(2)O to simulate conditions in the interstellar gas and on interstellar grains. The experimental results can be interpreted to indicate that amino acids in the gas phase will likely be destroyed during the lifetime of a typical interstellar cloud. In regions with relatively low UV radiation, amino acids might be present as transient gas-phase species. Their survival in interstellar icy grain mantles and the surface layers of comets and planets is strongly limited in the presence of UV irradiation. The rate of destruction is rather insensitive to the amino acid structure and to the ice matrix. We consider the implications of these results for the survival and transfer of amino acids in space environments, and thus their possible availability for prebiotic chemistry. C1 Leiden Observ, Sackler Lab Astrophys, NL-2300 RA Leiden, Netherlands. NASA, Div Space Sci, Ames Res Ctr, Moffett Field, CA 94305 USA. SETI Inst, Mountain View, CA 94043 USA. RP Ehrenfreund, P (reprint author), Leiden Observ, Sackler Lab Astrophys, POB 9513, NL-2300 RA Leiden, Netherlands. EM pascale@strw.leidenuniv.nl RI Dworkin, Jason/C-9417-2012 OI Dworkin, Jason/0000-0002-3961-8997 NR 31 TC 121 Z9 122 U1 3 U2 33 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 2001 VL 550 IS 1 BP L95 EP L99 DI 10.1086/319491 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 413GZ UT WOS:000167605400021 ER PT J AU Sturrock, PA Scargle, JD AF Sturrock, PA Scargle, JD TI Histogram analysis of GALLEX, GNO, and SAGE neutrino data: Further evidence for variability of the solar neutrino flux SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : particle emission ID RESONANT AMPLIFICATION; SUNSPOT NUMBER; CAPTURE RATE; OSCILLATIONS; MATTER; MODULATION; PRECESSION; ROTATION AB If the solar neutrino flux were constant, as is widely assumed, the histogram of flux measurements would be unimodal. On the other hand, sinusoidal or square-wave modulation (either periodic or stochastic) may lead to a bimodal histogram. We here present evidence that the neutrino flux histogram is in fact bimodal. We analyze all available data from gallium experiments, coordinating results from the GALLium EXperiment and the Gallium Neutrino Observatory experiment into one data set and adopting results from the Soviet-American Gallium Experiment as another data set. The two histograms, from the two data sets, are consistent in showing peaks in the ranges 45-75 and 90-120 SNU, with a valley in between. By combining the data into one data set, we may form more detailed histograms; these strengthen the case that the flux is bimodal. A preliminary statistical analysis indicates that the bimodal character of the solar neutrino flux is highly significant. Since the upper peak is close to the expected flux (120-140 SNU), we may infer that the neutrino deficit is due to time-varying attenuation of the flux produced in the core. We estimate the timescale of this variation to be in the range 10-60 days. Attenuation that varies on such a timescale is suggestive of the influence of solar rotation and points toward a process involving the solar magnetic field in conjunction with a nonzero neutrino magnetic moment. C1 Stanford Univ, Ctr Space Sci & Astrophys, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Sturrock, PA (reprint author), Stanford Univ, Ctr Space Sci & Astrophys, Varian 302G, Stanford, CA 94305 USA. NR 34 TC 30 Z9 30 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 2001 VL 550 IS 1 BP L101 EP L104 DI 10.1086/319482 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 413GZ UT WOS:000167605400022 ER PT J AU Yashiro, S Shibata, K AF Yashiro, S Shibata, K TI Relation between thermal and magnetic properties of active regions as a probe of coronal heating mechanisms SO ASTROPHYSICAL JOURNAL LA English DT Article DE magnetic fields; Sun : corona; Sun : X-rays, gamma rays ID SOLAR-A MISSION; X-RAY TELESCOPE; ALFVEN WAVES; RECONNECTION; OSO-8; MODEL AB We study the relation between thermal and magnetic properties of active regions in the corona observed with the soft X-ray telescope aboard Yohkoh. We derive the mean temperature and pressure of 64 mature active regions using the filter ratio technique, and examine the relationship of region size with temperature and pressure. We find that the temperature T of active regions increases with increasing region size L as T proportional to L-0.28, while the pressure, We P slightly decreases with the region size as P proportional to L-0.16. We confirm the scaling law T proportional to (PL)(1/3) for mature active regions found by R. Rosner, W. H. Tucker, & G. S. Vaiana. We examined the magnetic properties of active regions by analyzing 31 active regions observed with the Solar and Heliospheric Observatory/Michelson Doppler Imager and find the following empirical scaling law between thermal and magnetic properties, U-th proportional to Phi (1.33), P proportional to B-0.78, where U-th, Phi, and B are the total thermal energy content, total magnetic flux, and average magnetic flux density of active regions, respectively. The former is consistent with the results of L. Golub et al., but the latter is not. Implications of our findings for coronal heating mechanisms are discussed. C1 Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. Kyoto Univ, Kwasan Observ, Kyoto 6078471, Japan. RP NASA, Goddard Space Flight Ctr, Code 682-3,Bldg 26,Room G-1, Greenbelt, MD 20771 USA. EM yashiro@cdaw.gsfc.nasa.gov NR 27 TC 25 Z9 25 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 20 PY 2001 VL 550 IS 1 BP L113 EP L116 DI 10.1086/319486 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 413GZ UT WOS:000167605400025 ER PT J AU Menges, CH Van Zyl, JJ Hill, GJE Ahmad, W AF Menges, CH Van Zyl, JJ Hill, GJE Ahmad, W TI A procedure for the correction of the effect of variation in incidence angle on AIRSAR data SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID RADAR BACKSCATTER; SOIL-MOISTURE; PINE STANDS; BARE SOIL; FOREST; BIOMASS; MODEL; SAR AB Radar imaging is a valuable tool for the monitoring and management of tropical ecosystems. One of the obstacles to its successful usage is the variation of the radar backscatter with incidence angle caused by the side-looking mode of the sensor. Available research has modelled the effect of changes in incidence angle for soil, grass and scattering mechanisms in tree-covered areas. The effect varies depending on the scattering mechanism. To model the radar backscatter behaviour of a natural landscape, therefore, implies precise knowledge of the land-cover composition. A method for estimating and correcting the effect of changes in look angle on backscatter data is consequently proposed; it requires little field knowledge and encompasses the effects on most land-cover types in the study area. The method is based on the assumption that each line in azimuth direction contains a similar composition in regard to land-cover types. The backscatter frequency distribution of each azimuth line can then be employed to model and correct for the effect of variation in incidence angle. The results are evaluated using an existing land-cover classification to extract mean backscatter values for individual land-cover classes before and after the correction procedure. The correction procedure is shown to successfully adjust backscatter intensities to a nominal incidence angle for the vegetation communities in a coastal tropical savanna landscape in Australia's Northern Territory. C1 No Terr Univ, Fac Sci, RS GIS Lab, Darwin, NT 0909, Australia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Menges, CH (reprint author), No Terr Univ, Fac Sci, RS GIS Lab, Darwin, NT 0909, Australia. NR 19 TC 10 Z9 11 U1 0 U2 3 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD MAR 20 PY 2001 VL 22 IS 5 BP 829 EP 841 DI 10.1080/01431160051060264 PG 13 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 414RE UT WOS:000167679300010 ER PT J AU Yamada, T AF Yamada, T TI Modeling of electronic transport in scanning tunneling microscope tip-carbon nanotube systems SO APPLIED PHYSICS LETTERS LA English DT Article ID FIELD-EFFECT TRANSISTORS; SINGLE-WALL; SURFACE AB A model is proposed for two observed current-voltage (I-V) patterns in a recent experiment with a scanning tunneling microscope tip and a carbon nanotube [Collins , Science 278, 100 (1997)]. We claim that there are two mechanical contact modes for a tip (metal)-nanotube (semiconductor) junction (1) with or (2) without a tiny vacuum gap (0.1-0.2 nm). With the tip grounded, the tunneling case in (1) would produce large dI/dV with V >0, small dI/dV with V <0, and I = 0 near V = 0 for an either n or p nanotube; the Schottky mechanism in (2) would result in I not equal 0 only with V <0 for an n nanotube, and the bias polarities would be reversed for a p nanotube. The two observed I-V patterns are thus entirely explained by a tip-nanotube contact of the two types, where the nanotube must be n-type. (C) 2001 American Institute of Physics. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. CSC, Wallops Island, VA USA. RP Yamada, T (reprint author), NASA, Ames Res Ctr, M-S T27A-1, Moffett Field, CA 94035 USA. RI Yamada, Toshishige/E-7834-2012 OI Yamada, Toshishige/0000-0001-7145-9212 NR 20 TC 19 Z9 19 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD MAR 19 PY 2001 VL 78 IS 12 BP 1739 EP 1741 DI 10.1063/1.1357206 PG 3 WC Physics, Applied SC Physics GA 410JF UT WOS:000167436300031 ER PT J AU Boccippio, DJ Heckman, S Goodman, SJ AF Boccippio, DJ Heckman, S Goodman, SJ TI A diagnostic analysis of the Kennedy Space Center LDAR network 1. Data characteristics SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TIME-OF-ARRIVAL; THUNDERSTORMS; SYSTEM; STORM; CLOUD AB An analytic framework is developed in which to analyze climatological VHF (66 MHz) radiation measurements taken by the Kennedy Space Center Lightning Detection and Ranging (LDAR) network. A 19 month noise-filtered sample of LDAR observations is examined using this framework. It is found that the climatological impulsive VHF source density as observed by LDAR falls off similar to 10 dB every 71 km of ground range away from the network centroid (a 31 km e-folding scale). The underlying vertical distribution of impulsive VHF sources is approximately normally distributed with a mean altitude of 9 km and a standard deviation of 2.7 km; this implies that the loss of below-horizon sources has a negligible effect on column-integrated source densities within a 200 km ground range. At medium to far ranges, location errors are primarily radial and have a slightly asymmetric distribution whose standard deviation increases as r(2). Error moments estimated from observed lightning are significantly higher than those from aircraft-based signal generator or analytic estimates. LDAR bulk flash detection efficiency is predicted to be above 90% to 94-113 km range from the network centroid and to fall below 10% at ranges greater than 200-240 km. C1 NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35806 USA. RP Boccippio, DJ (reprint author), NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, SD-60, Huntsville, AL 35812 USA. NR 30 TC 27 Z9 32 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 16 PY 2001 VL 106 IS D5 BP 4769 EP 4786 DI 10.1029/2000JD900687 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 411DM UT WOS:000167482900008 ER PT J AU Boccippio, DJ Heckman, S Goodman, SJ AF Boccippio, DJ Heckman, S Goodman, SJ TI A diagnostic analysis of the Kennedy Space Center LDAR network 2. Cross-sensor studies SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OPTICAL TRANSIENT DETECTOR; CLOUD AB Range dependencies in total (intracloud and cloud to ground) lightning observed by the Kennedy Space Center Lightning Detection and Ranging (LDAR) network are established through cross comparison with other lightning sensors. Using total lightning observed from space by the Lightning Imaging Sensor (LIS), LDAR flash detection efficiency is shown to remain above 90% out to 90-100 km range, and to be below 25% at 200 km range. LDAR VHF source location error distributions are also determined as a function of range and are found to be asymmetric with standard deviation increasing roughly as r(2). Range normalization schemes for total VHF source density are tested and shown to yield significant improvements in correlation with National Lightning Detection Network (NLDN) ground flash density at hourly, daily, monthly, and climatological timescales (up to 50% over uncorrected source densities using an exponential-in-range correction factor with 40-50 km e-folding scale). C1 NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35806 USA. RP Boccippio, DJ (reprint author), NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, SD-60, Huntsville, AL 35812 USA. NR 17 TC 5 Z9 5 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 16 PY 2001 VL 106 IS D5 BP 4787 EP 4796 DI 10.1029/2000JD900688 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 411DM UT WOS:000167482900009 ER PT J AU Lin, JS Tabazadeh, A AF Lin, JS Tabazadeh, A TI A parameterization of an aerosol physical chemistry model for the NH3/H2SO4/HNO3/H2O system at cold temperatures SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MULTICOMPONENT THERMODYNAMIC MODEL; NITRIC-ACID; 298.15 K; EQUILIBRIUM; AMMONIUM; SULFATE; NITRATE; NUCLEATION; DEPLETION; PARTICLES AB Simple expressions are fitted to the results obtained from ion interaction thermodynamic models for calculating HNO3 and H2O vapor pressures over the NH3/H2SO4/HNO3/H2O system at cold temperatures. The vapor pressure expressions are incorporated into a mass conserving equilibrium solver for computing aerosol compositions in the lower stratosphere and upper troposphere. The compositions calculated from the aerosol physical chemistry model (APCM) are compared against previous parameterizations. The APCM compositions are in better agreement with the compositions obtained from ion interaction models than from other previous formulations of the NH3/H2SO4/HNO3/H2O system. The only advantage of the APCM over the ion interaction approach is that the numerical scheme used in the model is fast and efficient for incorporation into large-scale models. The APCM is used to calculate HNO3 solubility in ammoniated aerosols as a function of HNO3, H2SO4 and NH3 mass loadings in the lower stratosphere and upper troposphere. While the uptake of HNO3 by ammoniated aerosols is strongly dependent upon the solution neutrality (or pH), we find that in both the lower stratosphere and upper troposphere a significant fraction of HNO3 will exist in aerosol solutions near and below the ice frost point irrespective of solution neutrality. C1 Bay Area Environm Res Inst, San Francisco, CA USA. RP Lin, JS (reprint author), NASA, Ames Res Ctr, MS 245-4, Moffett Field, CA 94035 USA. NR 36 TC 17 Z9 17 U1 1 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 16 PY 2001 VL 106 IS D5 BP 4815 EP 4829 DI 10.1029/2000JD900598 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 411DM UT WOS:000167482900011 ER PT J AU Kreidenweis, SM Remer, LA Bruintjes, R Dubovik, O AF Kreidenweis, SM Remer, LA Bruintjes, R Dubovik, O TI Smoke aerosol from biomass burning in Mexico: Hygroscopic smoke optical model SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SKY RADIANCE MEASUREMENTS; UNITED-STATES; HUMIDIFICATION FACTORS; BRAZIL; PARTICLES; RADIATION; INVERSION; NETWORK; AERONET; CARBON AB The May 1998 transport of smoke from fires in Mexico and Central America into the United States is examined. We combine data from ground-based Interagency Monitoring of Protected Visual Environments aerosol chemical sampling sites with in situ airborne and Sun photometer measurements to develop a consistent picture of the transported smoke-impacted aerosol optical and chemical properties. The aerosol observed in Mexico and the southern United States is found to have a higher sulfate mass fraction, higher single-scattering albedo, and larger accumulation mode radius than biomass burning aerosols observed by similar instrumentation in South America and Africa. We postulate that the smoke-impacted aerosol in the 1998 event was more hygroscopic than that observed in the other locations, because of the higher mass fractions of sulfate, and show that a simple model of corresponding changes in aerosol water content yields agreement with the observed variations in refractive index and radii. We further show that the single-scattering albedo cannot be fully explained by hygroscopic growth alone. Modifications to the model invoking variations in aerosol light-absorbing carbon content, which are consistent with differences in observed composition among the various smoke-impacted aerosols, bring the predictions of single-scattering albedo into alignment with our observations. The model demonstrates that the panicle size, single-scattering albedo, and real refractive index of smoke-impacted aerosols are not independent but vary in tandem with variations in particle hygroscopicity and with variations in black carbon content. This relationship is an important consideration in the assessment of the effects of biomass burning aerosols, particularly those subject to long-range transport, on radiative forcing and climate. C1 Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Natl Ctr Atmospher Res, Boulder, CO 80301 USA. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. RP Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. EM soniak@aerosol.atmos.colostate.edu; remer@climate.gsfc.nasa.gov; roelof@ucar.edu; dubovik@aeronet.gsfc.nasa.gov RI Dubovik, Oleg/A-8235-2009; Kreidenweis, Sonia/E-5993-2011 OI Dubovik, Oleg/0000-0003-3482-6460; Kreidenweis, Sonia/0000-0002-2561-2914 NR 26 TC 40 Z9 41 U1 0 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 16 PY 2001 VL 106 IS D5 BP 4831 EP 4844 DI 10.1029/2000JD900488 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 411DM UT WOS:000167482900012 ER PT J AU Duda, DP Minnis, P Nguyen, L AF Duda, DP Minnis, P Nguyen, L TI Estimates of cloud radiative forcing in contrail clusters using GOES imagery SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CIRRUS CLOUDS; PARAMETERIZATION; SATELLITE; AIRCRAFT; SURFACE; FLUXES AB Using data from the Geostationary Operational Environmental Satellite (GOES), the evolution of solar and longwave radiative forcing in contrail clusters is presented in several case studies. The first study examines contrails developing over the midwestern United States in a region of upper tropospheric moisture enhanced by the remnants of Hurricane Nora on September 26, 1997. Two other cases involve contrail clusters that formed over the Chesapeake Bay and the Atlantic Ocean on February 11 and March 5, 1999, respectively. The last study includes contrails forming over the tropical Pacific near Hawaii. Observations of tropical contrails near Hawaii show that the contrail optical properties are similar to those measured from satellite in the midlatitudes, with visible optical depths between 0.3 and 0.5 and particle sizes between 30 and 60 mum as the contrails mature into diffuse cloudiness. Radiative transfer model simulations of the tropical contrail case suggest that ice crystal shape may have an important effect on radiative forcing in contrails. The magnitudes of the observed solar and longwave radiative forcings were 5.6 and 3.2 W m(-2) less than those from the corresponding model simulations, and these differences are attributed to the subpixel scale low clouds and uncertainties in the anisotropic reflectance and limb-darkening models used to estimate the observed forcing. Since the broadband radiative forcing in contrails often changes rapidly, contrail forcing estimates based only on the polar orbiting advanced very high resolution radiometer (AVHRR) data could be inaccurate due to the lack of sufficient temporal sampling. C1 Hampton Univ, NASA, Langley Res Ctr, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Hampton, VA USA. Analyt Serv & Mat Inc, Hampton, VA 23666 USA. RP Duda, DP (reprint author), Hampton Univ, NASA, Langley Res Ctr, Mail Stop 420,21 Landley Blvd, Hampton, VA 23681 USA. RI Minnis, Patrick/G-1902-2010 OI Minnis, Patrick/0000-0002-4733-6148 NR 27 TC 23 Z9 23 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 16 PY 2001 VL 106 IS D5 BP 4927 EP 4937 DI 10.1029/2000JD900393 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 411DM UT WOS:000167482900018 ER PT J AU Thompson, AM Witte, JC Hudson, RD Guo, H Herman, JR Fujiwara, M AF Thompson, AM Witte, JC Hudson, RD Guo, H Herman, JR Fujiwara, M TI Tropical tropospheric ozone and biomass burning SO SCIENCE LA English DT Article ID GROUND-BASED OBSERVATIONS; MODIFIED-RESIDUAL METHOD; MAPPING SPECTROMETER; SOUTH-ATLANTIC; INDIAN-OCEAN; EL-NINO; AEROSOL; TRANSPORT; TOMS; CHEMISTRY AB New methods for retrieving tropospheric ozone column depth and absorbing aerosol (smoke and dust) from the Earth Probe-Total Ozone Mapping Spectrometer (EP/TOMS) are used to follow pollution and to determine interannual variability and trends. During intense fires over Indonesia (August to November 1997), ozone plumes, decoupled from the smoke below, extended as far as India, This ozone overlay a regional ozone increase triggered by atmospheric responses to the El Nino and Indian Ocean Dipole. Tropospheric ozone and smoke aerosol measurements from the Nimbus 7 TOMS instrument show El Nino signals but no tropospheric ozone trend in the 1980s. Offsets between smoke and ozone seasonal maxima point to multiple factors determining tropical tropospheric ozone variability. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Comp Sci, College Pk, MD 20742 USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. Sci Syst & Applicat, Lanham, MD 20706 USA. Hokkaido Univ, Grad Sch Environm Earth Sci, Sapporo, Hokkaido 0600810, Japan. RP Thompson, AM (reprint author), NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA. RI Hudson, Robert/F-4506-2010; Fujiwara, Masatomo/F-7852-2012; Thompson, Anne /C-3649-2014; OI Thompson, Anne /0000-0002-7829-0920; Herman, Jay/0000-0002-9146-1632 NR 36 TC 141 Z9 145 U1 3 U2 25 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 16 PY 2001 VL 291 IS 5511 BP 2128 EP 2132 DI 10.1126/science.291.5511.2128 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 412PP UT WOS:000167563800033 PM 11251113 ER PT J AU Seidler, RD Bloomberg, JJ Stelmach, GE AF Seidler, RD Bloomberg, JJ Stelmach, GE TI Context-dependent arm pointing adaptation SO BEHAVIOURAL BRAIN RESEARCH LA English DT Article; Proceedings Paper CT 29th Annual Meeting of the Society-for-Neuroscience CY OCT 23-28, 1999 CL MIAMI BEACH, FL SP Soc Neurosci DE motor control; adaption; arm; head posture; context ID VESTIBULOOCULAR REFLEX; DUAL ADAPTATION; HEAD; DISPLACEMENT; MOVEMENTS; COORDINATION; CONTINGENT; ROTATION; HAND; EYE AB We sought to determine the effectiveness of head posture as a contextual cue to facilitate adaptive transitions in manual control during visuomotor distortions. Subjects performed arm pointing movements by drawing on a digitizing tablet, with targets and movement trajectories displayed in real time on a computer monitor. Adaptation was induced by presenting the trajectories in an altered gain format on the monitor. The subjects were shown visual displays of their movements that corresponded to either 0.5 or 1.5 scaling of the movements made. Subjects were assigned to three groups: the head orientation group tilted the head towards the right shoulder when drawing under a 0.5 gain of display and towards the left shoulder when drawing under a 1.5 gain of display; the target orientation group had the home and target positions rotated counterclockwise when drawing under the 0.5 gain and clockwise for the 1.5 gain; the arm posture group changed the elbow angle of the arm they were not drawing with from full flexion to full extension with 0.5 and 1.5 gain display changes. To determine if contextual cues were associated with display alternations, the gain changes were returned to the standard (1.0) display. Aftereffects were assessed to determine the efficacy of the head orientation contextual cue compared to the two control cues. The head orientation cue was effectively associated with the multiple gains. The target orientation cue also demonstrated some effectiveness while the arm posture cue did not. The results demonstrate that contextual cues can be used to switch between multiple adaptive states. These data provide support for the idea that static head orientation information is a crucial component to the arm adaptation process. These data further define the functional linkage between head pasture and arm pointing movements. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Arizona State Univ, Motor Control Lab, Tempe, AZ 85287 USA. NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. RP Stelmach, GE (reprint author), Arizona State Univ, Motor Control Lab, POB 870404, Tempe, AZ 85287 USA. EM stelmach@asu.edu NR 32 TC 32 Z9 32 U1 0 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0166-4328 J9 BEHAV BRAIN RES JI Behav. Brain Res. PD MAR 15 PY 2001 VL 119 IS 2 BP 155 EP 166 DI 10.1016/S0166-4328(00)00347-8 PG 12 WC Behavioral Sciences; Neurosciences SC Behavioral Sciences; Neurosciences & Neurology GA 404VQ UT WOS:000167123100004 PM 11165331 ER PT J AU Kumar, B Scanlon, L Marsh, R Mason, R Higgins, R Baldwin, R AF Kumar, B Scanlon, L Marsh, R Mason, R Higgins, R Baldwin, R TI Structural evolution and conductivity of PEO : LiBF4-MgO composite electrolytes SO ELECTROCHIMICA ACTA LA English DT Article; Proceedings Paper CT 7th International Symposium on Polymer Electrolytes (ISPE-7) CY AUG 06-11, 2000 CL NOOSA, AUSTRALIA DE polymer-ceramic; electrolyte; lithium-ion; conductivity; structure ID POLYMER ELECTROLYTES; BATTERIES AB This paper explores and proposes a structure-conductivity correlation in the PEO:LiBF4-MgO composite electrolyte system. The proposed correlation is derived from interpretations of DSC and conductivity measurements. Thermal cycling in the 0-100 degreesC range yields an amorphous polymer structure believed to be beneficial for enhanced conductivity. The proposed roles of MgO are to depress the PEO melting temperature and retard the kinetics of its crystallization. A resistivity relaxation or conductivity enhancement below the melting temperature of PEO (68 degreesC) occurs, which appears to be a characteristic of these electrolytes and related to an interaction of dipoles associated with polymer chains and MgO. A higher concentration (similar or equal to 30%) of MgO leads to its segregation and reduction in conductivity resulting from crystallization of PEG. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Univ Dayton, Res Inst, Dayton, OH 45469 USA. USAF, Res Lab, Prop Directorate, Wright Patterson AFB, OH 45433 USA. Eagle Picher Technol LLC, Joplin, MO 64802 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Kumar, B (reprint author), Univ Dayton, Res Inst, 300 Coll Pk,KL 501, Dayton, OH 45469 USA. NR 7 TC 67 Z9 71 U1 1 U2 12 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0013-4686 J9 ELECTROCHIM ACTA JI Electrochim. Acta PD MAR 15 PY 2001 VL 46 IS 10-11 BP 1515 EP 1521 DI 10.1016/S0013-4686(00)00747-7 PG 7 WC Electrochemistry SC Electrochemistry GA 418ZB UT WOS:000167924000017 ER PT J AU Newman, PA Wilson, JC Ross, MN Brock, CA Sheridan, PJ Schoeberl, MR Lait, LR Bui, TP Loewenstein, M Podolske, JR AF Newman, PA Wilson, JC Ross, MN Brock, CA Sheridan, PJ Schoeberl, MR Lait, LR Bui, TP Loewenstein, M Podolske, JR TI Chance encounter with a stratospheric kerosene rocket plume from Russia over California SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID AEROSOL; MIDLATITUDES; TROPOSPHERE; VORTEX; OZONE AB A high-altitude aircraft flight on April 18, 1997, detected an enormous aerosol cloud at 20 km altitude near California (37 degreesN). Not visually observed, the cloud had high concentrations of soot and sulfate aerosol, and was over 180 km in horizontal extent. The cloud was probably a large hydrocarbon-fueled rocket vehicle, most likely burning liquid oxygen and kerosene. One of two Russian Soyuz rockets could have produced the cloud: a launch from the Baikonur Cosmodrome, Kazakhstan on April 6; or one from Plesetsk, Russia on April 9. Parcel trajectories and long-lived trace gas concentrations suggest the Baikonur launch as the cloud source. Cloud trajectories do not trace the Soyuz plume from Asia to North America, illustrating the uncertainties of point-to-point trajectories. This cloud encounter is the only stratospheric measurement of a hydrocarbon-fueled rocket. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Denver, Dept Engn, Denver, CO 80208 USA. Aerospace Corp, Environm Syst Directorate, Los Angeles, CA 90009 USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NOAA, Aeron Lab, Boulder, CO 80303 USA. Raytheon ITSS, Lanham, MD USA. RP Newman, PA (reprint author), NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA. RI Brock, Charles/G-3406-2011; Newman, Paul/D-6208-2012 OI Brock, Charles/0000-0002-4033-4668; Newman, Paul/0000-0003-1139-2508 NR 15 TC 9 Z9 9 U1 0 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 15 PY 2001 VL 28 IS 6 BP 959 EP 962 DI 10.1029/2000GL011972 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 411JD UT WOS:000167494200003 ER PT J AU Lin, B Minnis, P Fan, A Curry, JA Gerber, H AF Lin, B Minnis, P Fan, A Curry, JA Gerber, H TI Comparison of cloud liquid water paths derived from in situ and microwave radiometer data taken during the SHEBA/FIREACE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MODEL AB Mean cloud liquid water path LWP derived from microwave measurements using the standard ARM retrieval technique is nearly twice as large as coincident in situ aircraft data taken over the SHEBA ice camp in the Arctic during FIRE ACE. Using an algorithm adopted from satellite remote sensing that more completely accounts for the temperature dependence of water absorption and atmospheric gas absorption results in a 25 to 4.5 % reduction in LWP values relative to the standard ARM estimates. If possible precipitation cases are excluded, the mean results from the new technique differ by only 3% from the in situ data. Greater differences for heavier clouds may result from in situ probe uncertainties. This algorithm should provide accurate LWP retrievals for a variety of cloud conditions from the tropics to the highly supercooled Arctic clouds. C1 NASA, Langley Res Ctr, Atmospher Sci Res, Hampton, VA 23681 USA. Sci Applicat Int Corp, Hampton, VA USA. Univ Colorado, Program Atmospher & Ocean Sci, Boulder, CO 80309 USA. Gerber Sci Inc, Reston, VA 20190 USA. RP Lin, B (reprint author), NASA, Langley Res Ctr, Atmospher Sci Res, MS 420, Hampton, VA 23681 USA. RI Minnis, Patrick/G-1902-2010 OI Minnis, Patrick/0000-0002-4733-6148 NR 13 TC 29 Z9 29 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 15 PY 2001 VL 28 IS 6 BP 975 EP 978 DI 10.1029/2000GL012386 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 411JD UT WOS:000167494200007 ER PT J AU Mlynczak, MG Morgan, F Yee, JH Espy, P Murtagh, D Marshall, B Schmidlin, F AF Mlynczak, MG Morgan, F Yee, JH Espy, P Murtagh, D Marshall, B Schmidlin, F TI Simultaneous measurements of the O-2((1)Delta) and O-2((1)Sigma) airglows and ozone in the daytime mesosphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MODEL; NM AB We report simultaneous measurements of the O-2((1)Delta) and O-2((1)Sigma) airglow volume emission rate profiles in the daytime mesosphere. We use these measurements to derive ozone concentrations separately from each airglow. The measurements were made as part of the Mesosphere-Thermosphere Emissions for Ozone Remote Sensing (METEORS) sounding rocket project launched from White Sands Missile Range, New Mexico. These data offer the opportunity to assess the consistency of ozone profiles derived from measurements of the oxygen airglows and thus provide a fundamental test of our understanding of dayglow physics and solar energy deposition. In both airglow-derived profiles the ozone decreases with altitude throughout the middle mesosphere and a pronounced secondary maximum exists near 90 km. The derived ozone profiles are in agreement to within measurement uncertainty. This agreement confirms that the major processes responsible for the generation of mesospheric oxygen dayglow are well understood via measurement. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Johns Hopkins Appl Phys Lab, Laurel, MD USA. British Antarctic Survey, Cambridge CB3 0ET, England. Stockholm Univ, S-10691 Stockholm, Sweden. G&A Tech Software, Hampton, VA USA. NASA, Wallops Flight Facil, Wallops Island, VA USA. RP Mlynczak, MG (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. RI Mlynczak, Martin/K-3396-2012; Murtagh, Donal/F-8694-2011 OI Murtagh, Donal/0000-0003-1539-3559 NR 15 TC 22 Z9 23 U1 2 U2 4 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 15 PY 2001 VL 28 IS 6 BP 999 EP 1002 DI 10.1029/2000GL012423 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 411JD UT WOS:000167494200013 ER PT J AU Katsaros, KB Forde, EB Chang, P Liu, WT AF Katsaros, KB Forde, EB Chang, P Liu, WT TI QuikSCAT's SeaWinds facilitates early identification of tropical depressions in 1999 hurricane season SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SCATTEROMETER; SYSTEM; OCEAN AB Far from land and surface ship observations, most tropical depressions are identified by examining images from geostationary satellites for the presence of rotation of the convective cloud masses. During the 1999 hurricane season, surface wind vectors obtained by the SeaWinds scatterometer on the QuikSCAT satellite for the tropical Atlantic and Caribbean Sea were examined to test the hypothesis that developing tropical depressions (TDs) could be observed with this satellite sensor, before identification by the traditional means. QuikSCAT was able to detect the presence of closed circulation in the surface winds before the systems were designated as depressions. The satellite's unprecedented large swath width of 1800 km allows twice a day observation of most of the tropical oceans. SeaWinds data can, therefore, provide valuable guidance that are an important addition to the tools available to the tropical cyclone forecasting community. C1 NOAA, Atlantic Oceanog & Meteorol Lab, Miami, FL 33149 USA. NOAA, Natl Environm Satellite Data & Informat Serv, Camp Springs, MD 20746 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Katsaros, KB (reprint author), NOAA, Atlantic Oceanog & Meteorol Lab, 4301 Rickenbacker Causeway, Miami, FL 33149 USA. RI Chang, Paul/F-5580-2010 OI Chang, Paul/0000-0001-5113-0938 NR 16 TC 49 Z9 50 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 15 PY 2001 VL 28 IS 6 BP 1043 EP 1046 DI 10.1029/2000GL011646 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 411JD UT WOS:000167494200024 ER PT J AU Cummer, SA Reiner, MJ Reinisch, BW Kaiser, ML Green, JL Benson, RF Manning, R Goetz, K AF Cummer, SA Reiner, MJ Reinisch, BW Kaiser, ML Green, JL Benson, RF Manning, R Goetz, K TI A test of magnetospheric radio tomographic imaging with IMAGE and WIND SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ELECTRON-DENSITY; SPACECRAFT AB Theoretical studies have shown the potential scientific value of multi-spacecraft: radio tomographic imaging of the magnetosphere. The < 10 R-E WIND perigee passes during August 2000 afforded a unique opportunity to test and verify the capabilities of radio tomography by measuring interspacecraft electromagnetic wave propagation parameters using the Radio Plasma Imager (RPI) on IMAGE as the transmitter and the WAVES instrument on WIND as the receiver. The primary goal of this experiment was to measure Faraday rotation variations in the RPI signal and interpret them in terms of the path-integrated magnetic field and electron density. A special 6 W linearly-polarized 828 kHz RPI signal was clearly detected by WAVES more than 6 R-E away and showed a distinct signature of time-varying Faraday rotation. We show how changes in the path-integrated electron density/magnetic field product can be unambiguously measured from this continuous, low signal to noise ratio, single frequency measurement. C1 Duke Univ, Dept Elect & Comp Engn, Durham, NC 27708 USA. NASA, Goddard Space Flight Ctr, RITSS, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Univ Massachusetts, Ctr Atmospher Res, Lowell, MA 01854 USA. NASA, Goddard Space Flight Ctr, Space Sci Data Operat Off, Greenbelt, MD 20771 USA. Observ Paris, Meudon, France. Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA. RP Cummer, SA (reprint author), Duke Univ, Dept Elect & Comp Engn, Box 90291, Durham, NC 27708 USA. RI Cummer, Steven/A-6118-2008 OI Cummer, Steven/0000-0002-0002-0613 NR 14 TC 10 Z9 10 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 15 PY 2001 VL 28 IS 6 BP 1131 EP 1134 DI 10.1029/2000GL012683 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 411JD UT WOS:000167494200046 ER PT J AU Frey, HU Mende, SB Carlson, CW Gerard, JC Hubert, B Spann, J Gladstone, R Immel, TJ AF Frey, HU Mende, SB Carlson, CW Gerard, JC Hubert, B Spann, J Gladstone, R Immel, TJ TI The electron and proton aurora as seen by IMAGE-FUV and FAST SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LYMAN-ALPHA; MODEL; FREJA AB The Far Ultraviolet Instrument (FUV) on the IMAGE spacecraft observes the aurora in three different channels. One of them (SI12) is sensitive to the signal from precipitating protons, while the other two (WIC and SI13) observe auroral emissions which are not only excited by precipitating electrons, but also by protons. We examine a period when in-situ particle measurements by the FAST spacecraft were available simultaneously with global imaging with FUV. The measured electron and proton energy spectra are used to calculate the auroral brightness along the FAST orbit. The comparison with the FUV/IMAGE observations shows good quantitative agreement and demonstrates that under certain circumstances high proton fluxes may produce significant amounts of auroral FUV emission. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Liege, LPAP, B-4000 Liege, Belgium. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. SW Res Inst, San Antonio, TX 78228 USA. RP Frey, HU (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. OI Frey, Harald/0000-0001-8955-3282; GERARD, Jean-Claude/0000-0002-8565-8746 NR 14 TC 56 Z9 56 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 15 PY 2001 VL 28 IS 6 BP 1135 EP 1138 DI 10.1029/2000GL012352 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 411JD UT WOS:000167494200047 ER PT J AU Moore, TE Collier, MR Burch, JL Chornay, DJ Fuselier, SA Ghielmetti, AG Giles, BL Hamilton, DC Herrero, FA Keller, JW Ogilvie, KW Peko, BL Quinn, JM Stephen, TM Wilson, GR Wurz, P AF Moore, TE Collier, MR Burch, JL Chornay, DJ Fuselier, SA Ghielmetti, AG Giles, BL Hamilton, DC Herrero, FA Keller, JW Ogilvie, KW Peko, BL Quinn, JM Stephen, TM Wilson, GR Wurz, P TI Low energy neutral atoms in the magnetosphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB We report observations of low energy neutral atoms (LENA) from the solar wind and the ionosphere, obtained by the LENA Imager on the IMAGE spacecraft. The LENA Imager detects and images LENAs arriving at the spacecraft from within a 90 degrees field of view (8 degrees x8 degrees pixels), swept through 360 degrees every two minutes by spacecraft spin. Neutral atoms arriving at the sensor are converted to negative ions by a conversion surface. The resulting negative ions are separated in energy (3 bins, 10 - 250 eV) and arrival direction (+/-45 degrees). They are then accelerated, detected, and time-of-flight mass analyzed. The solar wind and the ionosphere both emit measurable neutral atom fluxes, the latter responding rapidly to to variations of the former. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. SW Res Inst, San Antonio, TX USA. Univ Maryland, Dept Phys, College Pk, MD 20742 USA. Lockheed Martin ATC, Palo Alto, CA USA. Univ Denver, Dept Phys, Denver, CO 80208 USA. Univ New Hampshire, Inst EOS, Durham, NH USA. Mission Res Corp, Nashua, NH USA. Univ Bern, Inst Phys, Bern, Switzerland. RP Moore, TE (reprint author), NASA, Goddard Space Flight Ctr, Code 692, Greenbelt, MD 20771 USA. RI Moore, Thomas/D-4675-2012; Keller, John/I-5097-2013; Collier, Michael/I-4864-2013; OI Moore, Thomas/0000-0002-3150-1137; Collier, Michael/0000-0001-9658-6605; Hamilton, Douglas/0000-0001-6103-8019 NR 6 TC 36 Z9 36 U1 0 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 15 PY 2001 VL 28 IS 6 BP 1143 EP 1146 DI 10.1029/2000GL012500 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 411JD UT WOS:000167494200049 ER PT J AU Fuselier, SA Ghielmetti, AG Moore, TE Collier, MR Quinn, JM Wilson, GR Wurz, P Mende, SB Frey, HU Jamar, C Gerard, JC Burch, JL AF Fuselier, SA Ghielmetti, AG Moore, TE Collier, MR Quinn, JM Wilson, GR Wurz, P Mende, SB Frey, HU Jamar, C Gerard, JC Burch, JL TI Ion outflow observed by IMAGE: Implications for source regions and heating mechanisms SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETOSPHERE AB Images of the Earth's proton aurora from the IMAGE spacecraft on 8 June 2000 indicate a temporally and spatially isolated ionospheric response to a shock that impinged on the Earth's magnetopause. Sometime after this ionospheric response, the Low Energy Neutral Atom imager on IMAGE detected enhanced ionospheric outflow. The time delay between the ionospheric response and the enhanced outflow is consistent with the travel time of similar to 30 eV neutral Oxygen (created by charge exchange of outflowing O+ with the exosphere) from the low altitude ionosphere to the spacecraft. The prompt ionospheric outflow implies that the shock deposited sufficient energy in the topside ionosphere near or above the O+ exobase to initiate the outflow. C1 Lockheed Martin Adv Technol Ctr, Dept L9 42, Palo Alto, CA 94304 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ New Hampshire, Durham, NH 03824 USA. Mission Res Corp, Nashau, NH 03062 USA. Univ Bern, Inst Phys, CH-3012 Bern, Switzerland. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Ctr Spatiale Liege, B-4000 Liege, Belgium. Univ Liege, B-4000 Liege, Belgium. SW Res Inst, San Antonio, TX USA. RP Fuselier, SA (reprint author), Lockheed Martin Adv Technol Ctr, Dept L9 42, Bldg 255,3251 Hanover St, Palo Alto, CA 94304 USA. RI Moore, Thomas/D-4675-2012; Collier, Michael/I-4864-2013; OI Moore, Thomas/0000-0002-3150-1137; Collier, Michael/0000-0001-9658-6605; Frey, Harald/0000-0001-8955-3282; GERARD, Jean-Claude/0000-0002-8565-8746 NR 15 TC 36 Z9 37 U1 0 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 15 PY 2001 VL 28 IS 6 BP 1163 EP 1166 DI 10.1029/2000GL012450 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 411JD UT WOS:000167494200054 ER PT J AU Reinisch, BW Huang, X Haines, DM Galkin, IA Green, JL Benson, RF Fung, SF Taylor, WWL Reiff, PH Gallagher, DL Bougeret, JL Manning, R Carpenter, DL Boardsen, SA AF Reinisch, BW Huang, X Haines, DM Galkin, IA Green, JL Benson, RF Fung, SF Taylor, WWL Reiff, PH Gallagher, DL Bougeret, JL Manning, R Carpenter, DL Boardsen, SA TI First results from the Radio Plasma Imager on IMAGE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID AURORAL KILOMETRIC RADIATION; CONTINUUM RADIATION; SOURCE LOCATION; WAVES AB The Radio Plasma Imager (RPI) is a 3 kHz to 3 MHz radio sounder, incorporating modern digital processing techniques and long electronically-tuned antennas, that is flown to large radial distances into the high-latitude magnetosphere on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite. Clear echoes, similar to those observed by ionospheric topside sounders, are routinely observed from the polar-cap ionosphere by RPI even when IMAGE is located at geocentric distances up to approximately 5 Earth radii. Using an inversion technique, these echoes have been used to determine electron-density distributions from the polar-cap ionosphere to the location of the IMAGE satellite. Typical echoes from the plasmapause boundary, observed from outside the plasmasphere, are of a diffuse nature indicating persistently irregular structure. Echoes attributed to the cusp and the magnetopause have also been identified, those from the cusp have been identified more often and with greater confidence. C1 Univ Massachusetts, Ctr Atmospher Res, Lowell, MA 01854 USA. NASA, Goddard Space Flight Ctr, Raytheon ITSS Corp, Greenbelt, MD 20771 USA. Rice Univ, Dept Phys & Astron, Houston, TX 77251 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Observ Paris, DESPA, URA CNRS 264, F-92195 Meudon, France. Stanford Univ, STAR Lab, Stanford, CA 94305 USA. NASA, Goddard Space Flight Ctr, Emergent Informat Technol Inc, Greenbelt, MD 20771 USA. RP Reinisch, BW (reprint author), Univ Massachusetts, Ctr Atmospher Res, 600 Suffolk St, Lowell, MA 01854 USA. RI Fung, Shing/F-5647-2012; Reiff, Patricia/D-2564-2014 OI Reiff, Patricia/0000-0002-8043-5682 NR 22 TC 49 Z9 49 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 15 PY 2001 VL 28 IS 6 BP 1167 EP 1170 DI 10.1029/2000GL012398 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 411JD UT WOS:000167494200055 ER PT J AU Ansari, RR Giblin, FJ King, JF AF Ansari, RR Giblin, FJ King, JF TI Early radiogenic- and hyperbaric oxygen-induced changes in animal lenses assessed in vivo by dynamic light scattering (DLS). SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NCMR, Cleveland, OH 44135 USA. Oakland Univ, Eye Res Inst, Rochester, MI 48309 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ASSOC RESEARCH VISION OPHTHALMOLOGY INC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 2001 VL 42 IS 4 SU S MA 548 BP S100 EP S100 PG 1 WC Ophthalmology SC Ophthalmology GA 427EP UT WOS:000168392100538 ER PT J AU Mulligan, JB Huemer, VA AF Mulligan, JB Huemer, VA TI Effects of color-coding on search in air traffic displays assessed by scan-path analysis. SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ASSOC RESEARCH VISION OPHTHALMOLOGY INC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 2001 VL 42 IS 4 SU S MA 4976 BP S927 EP S927 PG 1 WC Ophthalmology SC Ophthalmology GA 427EP UT WOS:000168392104939 ER PT J AU Scharff, LV Ahumada, AJ AF Scharff, LV Ahumada, AJ TI Predicting readability of transparent text on textured backgrounds. SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 Stephen F Austin State Univ, Nacogdoches, TX 75962 USA. NASA, Ames Res Ctr, Human Informat Proc Res Branch, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ASSOC RESEARCH VISION OPHTHALMOLOGY INC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 2001 VL 42 IS 4 SU S MA 3932 BP S733 EP S733 PG 1 WC Ophthalmology SC Ophthalmology GA 427EP UT WOS:000168392103895 ER PT J AU Phelan, BA Manderson, JP Stoner, AW Bejda, AJ AF Phelan, BA Manderson, JP Stoner, AW Bejda, AJ TI Size-related shifts in the habitat associations of young-of-the-year winter flounder (Pseudopleuronectes americanus): field observations and laboratory experiments with sediments and prey SO JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY LA English DT Article DE burying; food; habitat; sediment; substrata; winter flounder ID PLEURONECTES-PLATESSA L; PARALICHTHYS-DENTATUS; SPATIAL VARIATION; BURYING ABILITY; GROWTH-RATES; GRAIN-SIZE; BODY-SIZE; JUVENILE; FLATFISHES; PREFERENCE AB Field surveys and laboratory studies were used to determine the role of substrata in habitat selection by young-of-the year winter flounder. A synoptic field survey of winter flounder and sediments in the Navesink River-Sandy Hook Bay estuarine system in New Jersey demonstrated that winter flounder distribution was related to sediment grain size. Analysis using a generalized additive model indicated that the probability of capturing 10-49 mm SL winter flounder was high on sediments with a mean grain diameter of less than or equal to 0.5 mm, while fish 50-95 mm were least likely to be collected on fine sediments and most commonly on sediments with a grain-size near 1.0 mm. In the laboratory, sediment preferences and the burying ability of winter flounder (15-69 mm SL) were tested by exposing fish in 10-mm size groups to a choice of azoic sediments of different sediment grain sizes. Smaller individuals ( < 40 mm SL) preferred fine-grained sediments while larger individuals ( 40 mm SL) preferred coarse-grained sediments. Burying ability increased with size and all flounders avoided sediments that prevented burial. Subsequent laboratory experiments revealed that the presence of live prey (Mya arenaria) can over-ride sediment choice by winter flounder (50-68 mm SL) indicating the complexity of interrelated factors in habitat choice. (C) Published by Elsevier Science B.V. C1 James J Howard Marine Sci Lab, Natl Marine Fisheries Serv, NE Fisheries Sci Ctr, Behav Ecol Branch, Highlands, NJ 07732 USA. RP Phelan, BA (reprint author), James J Howard Marine Sci Lab, Natl Marine Fisheries Serv, NE Fisheries Sci Ctr, Behav Ecol Branch, 74 Magruder Rd, Highlands, NJ 07732 USA. NR 47 TC 52 Z9 53 U1 1 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0981 J9 J EXP MAR BIOL ECOL JI J. Exp. Mar. Biol. Ecol. PD MAR 15 PY 2001 VL 257 IS 2 BP 297 EP 315 DI 10.1016/S0022-0981(00)00340-3 PG 19 WC Ecology; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 414BV UT WOS:000167646800010 ER PT J AU Gloersen, P White, WB AF Gloersen, P White, WB TI Reestablishing the circumpolar wave in sea ice around Antarctica from one winter to the next SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SOUTHERN OSCILLATION; SURFACE TEMPERATURE; OCEAN; PRECIPITATION; VARIABILITY; PRESSURE; EXTENT AB Remarkable correlation exists between warm water, poleward winds over the ocean, and low sea ice concentrations and extents over the winter sea ice pack around Antarctica, even to the point of continuing paterns across the ice-sea boundary. Since the wind stress associated with poleward wind is expected to compact the ice during sea ice edge retraction, we conclude that the memory of the Antarctic circumpolar wave in the sea ice pack is carried from one austral winter to the next by the neighboring water temperatures since the sea ice pack retracts nearly to Antarctica in austral summer. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Sci, Oceans & Ice Branch, Greenbelt, MD 20771 USA. Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA. RP Gloersen, P (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Sci, Oceans & Ice Branch, Code 661, Greenbelt, MD 20771 USA. NR 18 TC 32 Z9 34 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 MAR 15 PY 2001 VL 106 IS C3 BP 4391 EP 4395 DI 10.1029/2000JC000230 PG 5 WC Oceanography SC Oceanography GA 409WX UT WOS:000167409600003 ER PT J AU Carr, ME Rossby, HT AF Carr, ME Rossby, HT TI Pathways of the North Atlantic Current from surface drifters and subsurface floats SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID EDDY KINETIC-ENERGY; MEAN CIRCULATION AB The North Atlantic east of the Grand Banks presents a thermal front from 40 degrees to 50 degreesN between the warm North Atlantic Current (NAC) and the cold Labrador Current. Here we use the trajectories of 84 isopycnal RAFOS floats deployed on the 27.2 and 27.5 sigma (T) surface in 1993-1995 and 218 surface drifters deployed by the International Ice Patrol and the Institut fur Meereskunde (Kiel, Germany) between 1978 and 1993 to understand the pathways of the NAG. The mean flow pattern, kinetic energy, directional stability, and most probable path through 1 degrees by 1 degrees boxes are derived for each of the three surfaces. Speed and kinetic energy decrease with depth, although directional stability is comparable at all levels. The axis of the NAG, which follows the 4000 m isobath along the western boundary, is described by mean kinetic energy (MKE) Values surpassing 100 cm(2) s(-2) on the float surfaces and correspond to regions with directional stabilities in excess of 60%. Maximum values of eddy kinetic energy are found just offshore of the maximum MKE associated with the NAC main pathway and decrease rapidly to the east. Two cyclonic meanders are identified at 44 degreesN, 45 degreesW near the Newfoundland Seamounts and at 46 degreesN, 42 degreesW near Flemish Cap. The main difference between the patterns derived for the surface drifters and floats was the greater eastward extent of the cyclonic trough st 44 degreesN and intensity of the Mann Eddy (42 degreesN, 44 degreesW) during the float sampling period (1993-1995). C1 Univ Rhode Isl, Grad Sch Oceanog, Narragansett, RI 02882 USA. RP Carr, ME (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 300-323, Pasadena, CA 91109 USA. NR 24 TC 23 Z9 23 U1 1 U2 4 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 2001 VL 106 IS C3 BP 4405 EP 4419 DI 10.1029/2000JC900106 PG 15 WC Oceanography SC Oceanography GA 409WX UT WOS:000167409600005 ER PT J AU Vandemark, D Mourad, PD Bailey, SA Crawford, TL Vogel, CA Sun, J Chapron, B AF Vandemark, D Mourad, PD Bailey, SA Crawford, TL Vogel, CA Sun, J Chapron, B TI Measured changes in ocean surface roughness due to atmospheric boundary layer rolls SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SYNTHETIC-APERTURE-RADAR; COLD-AIR OUTBREAK; SEA-SURFACE; WIND FIELDS; IMAGERY; SATELLITE; SAR; TURBULENCE; WAVES AB A research aircraft was recently flown over the Mid-Atlantic Eight during a mild cold air outbreak to sample the planetary boundary layer at low levels of 15-20 m above the sea surface. Aircraft sensors measured near-surface atmospheric turbulence and, at the same time, variations in sea surface roughness using laser and radar. The aircraft turbulence observations indicate a coherent secondary flow consistent with boundary layer roll vortices of crosswind scale 1.5-2.0 km. Modulation in measured laser and radar-inferred sea surface slope variance occurs at similar scales. Remarkable correlation is found between the radar backscatter and near-surface wind speed data, showing that the short wave slope variance is responsive to these large eddies. Associated small but periodic changes in wind direction do not appear to impact the short wave slope signature. Differentiation between short- and intermediate-scale wave roughness using aircraft laser and radar data leads us to conclude that observed fluctuations in intermediate-scale wave slope were not directly linked to the local wind. A synthetic aperture radar (SAR) image was acquired by the Canadian Space Agency's RADARSAT coincident with the aircraft measurements. Widespread streaking in the SAR image suggests the surface impacts of atmospheric longitudinal rolls. Our aircraft results indicate that the dominant term dictating SAR backscatter modulations at the eddy scale of 1-2 km is the fluctuation of the along-wind velocity, nominally associated with regions of near-surface convergence or divergence. Wind speed fluctuations of 7-10% estimated from the SAR and aircraft radar are consistent with the aircraft's measured variations in near-surface wind speed. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Wallops Isl, VA 23337 USA. Univ Washington, Coll Ocean & Fishery Sci, Appl Phys Lab, Seattle, WA 98105 USA. NOAA, Appl Res Lab, Field Res Div, Idaho Falls, ID 83402 USA. NOAA, Atmospher Turbulence & Diffus Div, Oak Ridge, TN USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. IFREMER, Ctr Brest, F-29280 Plouzane, France. RP Vandemark, D (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Wallops Isl, VA 23337 USA. EM vandemark@gsfc.nasa.gov RI Sun, Jielun/H-6576-2015; Chapron, Bertrand/O-6527-2015 OI Sun, Jielun/0000-0003-3271-7914; NR 31 TC 16 Z9 17 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-OCEANS JI J. Geophys. Res.-Oceans PD MAR 15 PY 2001 VL 106 IS C3 BP 4639 EP 4654 DI 10.1029/1999JC000051 PG 16 WC Oceanography SC Oceanography GA 409WX UT WOS:000167409600022 ER PT J AU Elfouhaily, T Thompson, DR Chapron, B Vandemark, D AF Elfouhaily, T Thompson, DR Chapron, B Vandemark, D TI Improved electromagnetic bias theory: Inclusion of hydrodynamic modulations SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SEA-STATE BIAS; JOINT DISTRIBUTION; RADAR ALTIMETRY; WAVES; WIND; SCATTERING; AMPLITUDES; PERIODS; TOPEX AB The modulation of short ocean waves by longer ones is a likely contributor to the radar altimeter's electromagnetic ranging bias (EM bias). An analytic model to account for this component of the EM bias is developed here under a two-scale two-dimensional hydrodynamic assumption. Following the principle of wave action balance, a standard hydrodynamic modulation transfer function is used to establish that the longer modulating waves enter the EM bias formulation not only through their elevation and slope variables but also through their quadratures. These latter contributions help to explain the role of long-wave slope and orbital velocity fields within the EM bias problem. Simplified analytical expressions are derived using linear Gaussian statistics for both modulating and modulated waves. For the sake of completeness an outline of the possible extension to nonlinear interacting waves is provided. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. IFREMER, Dept Oceanog Spatiale, F-29280 Brest, France. NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Wallops Isl, VA 23337 USA. RP Elfouhaily, T (reprint author), Johns Hopkins Univ, Appl Phys Lab, Johns Hopkins Rd, Laurel, MD 20723 USA. EM Elfouhaily@jhuapl.edu RI Chapron, Bertrand/O-6527-2015 NR 19 TC 20 Z9 21 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-OCEANS JI J. Geophys. Res.-Oceans PD MAR 15 PY 2001 VL 106 IS C3 BP 4655 EP 4664 DI 10.1029/1999JC000086 PG 10 WC Oceanography SC Oceanography GA 409WX UT WOS:000167409600023 ER PT J AU Walch, SP Dateo, CE AF Walch, SP Dateo, CE TI Thermal decomposition pathways and rates for silane, chlorosilane, dichlorosilane, and trichlorosilane SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID N = 0-4; AB-INITIO; HYDROGEN; KINETICS; SILICON AB Calculations have been carried out for the thermal decomposition of silane, chlorosilane; dichlorosilane, and trichlorosilane. In each case, the stationary point geometries and harmonic frequencies were characterizing using CASSCF/derivative methods and the cc-pVDZ basis set. Accurate energetics were obtained by combining the CCSD(T) results using the a-cc-pVTZ basis set with an extrapolation to the basis set limit using the a-cc-pVDZ, a-cc-pVTZ, and a-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. The barrier heights obtained in the present work (kcal/mol) are the following: SiH4 --> SiH2 + H-2 (61.9); SiClH3 --> SiClH + H-2 (66.7); SiClH3 --> SiH2 + HCl (76.9); SiCl2H2 --> SiCl2 + H-2 (77.2); SiCl2H2 --> SiClH + HCl (74.8); SiCl3H --> SiCl2 + HCl (72.7). The computed barrier heights are believed to be accurate to within 1 kcal/mol. The rate coefficients obtained in the present work are in fair accord with most of the experimental results. 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 26 TC 39 Z9 39 U1 3 U2 23 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 15 PY 2001 VL 105 IS 10 BP 2015 EP 2022 DI 10.1021/jp003559u PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 413CN UT WOS:000167592500041 ER PT J AU Dickens, JE Irvine, WM Nummelin, A Mollendal, H Saito, S Thorwirth, S Hjalmarson, A Ohishi, M AF Dickens, JE Irvine, WM Nummelin, A Mollendal, H Saito, S Thorwirth, S Hjalmarson, A Ohishi, M TI Searches for new interstellar molecules, including a tentative detection of aziridine and a possible detection of propenal SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article DE interstellar molecules; rotational spectra; propenal; aziridine; cyclopropenone; furan; hydroxyethanal ID SUBMILLIMETER-WAVE SPECTRUM; MILLIMETER-WAVE; MICROWAVE-SPECTRUM; METHYL FORMATE; ETHYLENE-OXIDE; YOUNG STARS; LINE SURVEY; BASIS-SETS; GHZ; C3H2 AB Rotational spectroscopy at millimeter wavelengths is a powerful means of investigating the chemistry of dense interstellar clouds. These regions can exhibit an interesting complement of gas phase molecules, including relatively complex organics. Here we report the tentative first astronomical detection of aziridine (ethylenimine), the possible detection of propenal (acrolein), and upper limits on the abundances of cyclopropenone, furan, hydroxyethanal (glycolaldehyde), thiohydroxylamine (NH2SH), and ethenol (vinyl alcohol) in various interstellar clouds. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Rensselaer Polytech Inst, Dept Phys, Troy, NY 12180 USA. Univ Oslo, Dept Chem, N-0315 Oslo, Norway. Fukui Univ, Res Ctr Dev Far IR Reg, Fukui 9108507, Japan. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. Chalmers Univ Technol, Onsala Space Observ, S-43992 Onsala, Sweden. Natl Astron Observ, Tokyo 181, Japan. RP Irvine, WM (reprint author), Univ Massachusetts, Dept Astron, 619 LGRT, Amherst, MA 01003 USA. RI Thorwirth, Sven/C-6217-2011; Bohall, Kenji/A-7498-2011 OI Thorwirth, Sven/0000-0001-8200-6710; NR 78 TC 34 Z9 34 U1 0 U2 3 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 15 PY 2001 VL 57 IS 4 SI SI BP 643 EP 660 DI 10.1016/S1386-1425(00)00434-0 PG 18 WC Spectroscopy SC Spectroscopy GA 418RY UT WOS:000167906200004 PM 11345244 ER PT J AU Charnley, SB Ehrenfreund, P Kuan, YJ AF Charnley, SB Ehrenfreund, P Kuan, YJ TI Spectroscopic diagnostics of organic chemistry in the protostellar environment SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article DE molecular; spectroscopy; astrophysics; astrochemistry ID POLYCYCLIC AROMATIC-HYDROCARBONS; INTERSTELLAR GRAIN MANTLES; MOLECULAR CLOUD CORES; DIPOLE-MOMENT; ASTROPHYSICAL IMPLICATIONS; MICROWAVE-SPECTRUM; SAGITTARIUS B2(N); ETHYLENE-OXIDE; CARBON-DIOXIDE; STAR-FORMATION AB A combination of astronomical observations, laboratory studies, and theoretical modelling is necessary to determine the organic chemistry of dense molecular clouds. We present spectroscopic evidence for the composition and evolution of organic molecules in protostellar environments. The principal reaction pathways to complex molecule formation by catalysis on dust grains and by reactions in the interstellar gas are described. Protostellar cores, where warming of dust has induced evaporation of icy grain mantles, are excellent sites in which to study the interaction between gas phase and grain-surface chemistries. We investigate the link between organics that are observed as direct products of grain surface reactions and those which are formed by secondary gas phase reactions of evaporated surface products. Theory predicts observable correlations between specific interstellar molecules, and also which new organics are viable for detection. We discuss recent infrared observations obtained with the Infrared Space Observatory, laboratory studies of organic molecules, theories of molecule formation, and summarise recent radioastronomical searches for various complex molecules such as ethers, azaheterocyclic compounds, and amino acids. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Div Space Sci, Planetary Syst Branch, Moffett Field, CA 94035 USA. Leiden Observ, Raymond & Beverly Sackler Lab Astrophys, NL-2300 RA Leiden, Netherlands. Natl Taiwan Normal Univ, Acad Sinica, Inst Astron & Astrophys, Dept Earth Sci, Taipei, Taiwan. RP NASA, Ames Res Ctr, Div Space Sci, Planetary Syst Branch, MS 245-3, Moffett Field, CA 94035 USA. RI Charnley, Steven/C-9538-2012 NR 87 TC 77 Z9 77 U1 0 U2 8 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 15 PY 2001 VL 57 IS 4 SI SI BP 685 EP 704 DI 10.1016/S1386-1425(00)00437-6 PG 20 WC Spectroscopy SC Spectroscopy GA 418RY UT WOS:000167906200007 PM 11345247 ER PT J AU Beegle, LW Wdowiak, TJ Harrison, JG AF Beegle, LW Wdowiak, TJ Harrison, JG TI Hydrogenation of polycyclic aromatic hydrocarbons as a factor affecting the cosmic 6.2 micron emission band SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article DE hydrogeneration; cosmic 6.2 micron; UIR; PAH; DFT; interstellar; circumstellar ID UNIDENTIFIED INFRARED-EMISSION; IR EMISSION; SPECTRA; NAPHTHALENE; HYPOTHESIS; EXCITATION; MOLECULES; FEATURES; NGC-7027; DUST AB While many of the characteristics of the cosmic unidentified infrared (UIR) emission bands observed for interstellar and circumstellar sources within the Milky Way and other galaxies, can be best attributed to vibrational modes of the variants of the molecular family known as polycyclic aromatic hydrocarbons (PAH), there are open questions that need to be resolved. Among them is the observed strength of the 6.2 micron (1600 cm(-1)) band relative to other strong bands, and the generally low strength for measurements in the laboratory of the 1600 cm(-1) skeletal vibration band of many specific neutral PAH molecules. Also, experiments involving laser excitation of some gas phase neutral PAH species while producing long lifetime state emission in the 3.3 micron (3000 cm(-1)) spectral region, do not result in significant 6.2 micron (1600 cm(-1)) emission. A potentially important variant of the neutral PAH species, namely hydrogenated-PAM (H-N-PAH) which exhibit intriguing spectral correlation with interstellar and circumstellar infrared emission and the 2175 Angstrom extinction feature, may be a factor affecting the strength of 6.2 micron emission. These species are hybrids of aromatic and cycloalkane structures. Laboratory infrared absorption spectroscopy augmented by density function theory (DFT) computations of selected partially hydrogenated-PAM molecules, demonstrates enhanced 6.2 micron (1600 cm(-1)) region skeletal vibration mode strength for these molecules relative to the normal PAH form. This along with other factors such as ionization or the incorporation of nitrogen or oxygen atoms could be a reason for the strength of the cosmic 6.2 micron (1600 cm(-1)) feature. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Univ Alabama Birmingham, Dept Phys, Astro & Solar Syst Phys Program, Birmingham, AL 35294 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Alabama Birmingham, Dept Phys, Birmingham, AL 35294 USA. RP Univ Alabama Birmingham, Dept Phys, Astro & Solar Syst Phys Program, Birmingham, AL 35294 USA. EM wdowiak@uab.edu RI Beegle, Luther/A-6354-2010 NR 28 TC 23 Z9 23 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 15 PY 2001 VL 57 IS 4 SI SI BP 737 EP 744 DI 10.1016/S1386-1425(00)00440-6 PG 8 WC Spectroscopy SC Spectroscopy GA 418RY UT WOS:000167906200010 PM 11345250 ER PT J AU Moore, MH Hudson, RL Gerakines, PA AF Moore, MH Hudson, RL Gerakines, PA TI Mid- and far-infrared spectroscopic studies of the influence of temperature, ultraviolet photolysis and ion irradiation on cosmic-type ices SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article DE IR spectroscopy; condensed-phase; ices; energetic processing; radiation chemistry; UV photolysis ID WATER-ICE; MU-M; ASTROPHYSICAL IMPLICATIONS; LABORATORY SIMULATIONS; ABSORPTION FEATURES; INTERSTELLAR ICES; CARBON-MONOXIDE; GRAIN MANTLES; HALE-BOPP; SPECTRUM AB Infrared (IR) studies of laboratory ices can provide information on the evolution of cosmic-type ices as a function of different simulated space environments involving thermal, ultraviolet (UV), or ion processing. Laboratory radiation experiments can lead to the formation of complex organic molecules. However, because of our lack of knowledge about UV photon and ion fluxes, and exposure lifetimes, it is not certain how well our simulations represent space conditions. Appropriate laboratory experiments are also limited by the absence of knowledge about the composition, density, and temperature of ices in different regions of space. Our current understanding of expected doses due to W photons and cosmic rays is summarized here, along with an inventory of condensed-phase molecules identified on outer solar system surfaces, comets and interstellar grains. Far-IR spectra of thermally cycled H2O are discussed since these results reflect the dramatic difference between the amorphous and crystalline phases of H2O ice, the most dominant condensed-phase molecule in cosmic ices. A comparison of mid-IR spectra of products in proton-irradiated and UV-photolyzed ices shows that few differences are observed for these two forms of processing for the simple binary mixtures studied to date. IR identification of radiation products and experiments to determine production rates of new molecules in ices during processing are discussed. A new technique for measuring intrinsic IR band strengths of several unstable molecules is presented. An example of our laboratory results applied to Europa observations is included. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Astrochem Branch, Greenbelt, MD 20771 USA. Eckerd Coll, Dept Chem, St Petersburg, FL 33733 USA. NASA, Goddard Space Flight Ctr, NRC, Astrochem Branch, Greenbelt, MD 20771 USA. RP NASA, Goddard Space Flight Ctr, Astrochem Branch, Code 691, Greenbelt, MD 20771 USA. EM ummhm@lepvax.gsfc.nasa.gov RI Gerakines, Perry/B-9705-2009; Hudson, Reggie/E-2335-2012; Gerakines, Perry/D-2226-2012 OI Gerakines, Perry/0000-0002-9667-5904 NR 55 TC 87 Z9 87 U1 2 U2 19 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 15 PY 2001 VL 57 IS 4 SI SI BP 843 EP 858 DI 10.1016/S1386-1425(00)00448-0 PG 16 WC Spectroscopy SC Spectroscopy GA 418RY UT WOS:000167906200018 PM 11345258 ER PT J AU Schwenke, DW Partridge, H AF Schwenke, DW Partridge, H TI Vibrational energy levels for CH4 from an ab initio potential SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article DE methane; potential energy surface ID VARIATIONAL CALCULATIONS; ISOTOPOMERS; METHANE; MOLECULES; DATABASE AB Many areas of astronomy and astrophysics require an accurate high temperature spectrum of methane (CH,). The goal of the present research is to determine an accurate ab initio potential energy surface (PES) for CH,. As a first step towards this goal, we have determined a PES including up to octic terms. We compare our results with experiment and to a PES based on a quartic expansion. Our octic PES gives good agreement with experiment for all levels, while the quartic PES only for the lower levels. (C) 2001 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. RI schwenke, david/I-3564-2013 NR 24 TC 105 Z9 108 U1 0 U2 4 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 15 PY 2001 VL 57 IS 4 SI SI BP 887 EP 895 DI 10.1016/S1386-1425(00)00451-0 PG 9 WC Spectroscopy SC Spectroscopy GA 418RY UT WOS:000167906200021 PM 11345261 ER PT J AU Hudgins, DM Bauschlicher, CW Allamandola, LJ AF Hudgins, DM Bauschlicher, CW Allamandola, LJ TI Closed-shell polycyclic aromatic hydrocarbon cations: a new category of interstellar polycyclic aromatic hydrocarbons SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article DE infrared spectroscopy; polycyclic aromatic hydrocarbon; harmonic frequencies and intensities; interstellar molecules ID INFRARED-EMISSION BANDS; PERDEUTERATED NAPHTHALENE; VIBRATIONAL-SPECTRA; ELECTRONIC-SPECTRA; RADICAL CATIONS; SPECTROSCOPY; FEATURES; PAHS; MOLECULES; PHENANTHRENE AB Density functional theory has been employed to calculate the harmonic frequencies and intensities of a range of polycyclic aromatic hydrocarbon (PAH) cations that explore both size and electronic structure effects on the infrared spectroscopic properties of these species. The sample extends the size range of PAH species considered to more than 50 carbon atoms and includes several representatives from each of two heretofore unexplored categories of PAH cations: (1) fully benzenoid PAH cations whose carbon skeleton is composed of an odd number of carbon atoms (C-odd PAHs); and (2) protonated PAH cations (HPAH(+)). Unlike the radical electronic structures of the PAH cations that have been the subject of previous theoretical and experimental work, the species in these two classes have a 'closed'-shell electronic configuration. The calculated spectra of circumcoronene, C54H18, in both neutral and (radical) cationic form are also reported and compared with those of the other species. Overall, the C-odd PAHs spectra are dominated by strong CC stretching modes near 1600 cm(-1) and display spectra that are remarkably insensitive to molecular size. The HPAH+ species evince a more complex spectrum consistent with the added contributions of aliphatic modes and their generally lower symmetry. Finally, for both classes of closed-shell cations, the intensity of the aromatic CH stretching modes is found to increase with molecular size far out of proportion with the number of CH groups, approaching a value more typical of neutral PAHs for the largest species studied. (C) 2001 Published by Elsevier Science B.V. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, MS 230-3, Moffett Field, CA 94035 USA. NR 67 TC 90 Z9 90 U1 0 U2 11 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 15 PY 2001 VL 57 IS 4 SI SI BP 907 EP 930 DI 10.1016/S1386-1425(00)00453-4 PG 24 WC Spectroscopy SC Spectroscopy GA 418RY UT WOS:000167906200023 PM 11345263 ER PT J AU Weisman, JL Lee, TJ Head-Gordon, M AF Weisman, JL Lee, TJ Head-Gordon, M TI Electronic spectra and ionization potentials of a stable class of closed shell polycyclic aromatic hydrocarbon cations SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article DE electronic spectra; ionization potentials; PAH; DFT ID DIFFUSE INTERSTELLAR BANDS; DENSITY-FUNCTIONAL THEORY; EXCITATION-ENERGIES; ASTROPHYSICAL IMPLICATIONS; PHOTODISSOCIATION REGIONS; PAH; SPECTROSCOPY; ABSORPTION; CHEMISTRY; APPROXIMATION AB Due to their stability, closed shell polycyclic aromatic hydrocarbon (PAH) cations are possible candidates as carriers for some of the diffuse interstellar bands (DIBs). The electronic absorption spectra and ionization potentials of several closed shell PAH cations are determined in this study. We use density functional theory (DFT) at the BLYP/6-31G* level to determine the ionization potentials and thus confirm the stability of the PAH cations of interest. We use time-dependent density functional theory (TDDFT), again at the BLYP/6-31G* level, to calculate the vertical excitation energies and oscillator strengths of the PAH cations. We observe dominant single absorptions within the DIB spectral region of interest in all of the PAH cation spectra except for the smallest member of the series. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA. Lawrence Berkeley Lab, Div Chem Sci, Berkeley, CA 94720 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Head-Gordon, M (reprint author), Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA. RI Lee, Timothy/K-2838-2012 NR 32 TC 32 Z9 32 U1 0 U2 3 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 15 PY 2001 VL 57 IS 4 SI SI BP 931 EP 945 DI 10.1016/S1386-1425(00)00454-6 PG 15 WC Spectroscopy SC Spectroscopy GA 418RY UT WOS:000167906200024 PM 11345264 ER PT J AU Chandrasekhar, P Birur, GC Stevens, P Rawal, S Pierson, EA Miller, KL AF Chandrasekhar, P Birur, GC Stevens, P Rawal, S Pierson, EA Miller, KL TI Far infrared electrochromism in unique conducting polymer systems SO SYNTHETIC METALS LA English DT Article; Proceedings Paper CT 16th International Conference on Science and Technology of Synthetic Metals (ICSM 2000) CY JUL 15-21, 2000 CL GASTEIN, AUSTRIA DE infrared; reflectance; electrochromic; emittance; conducting; polymer AB We report herein the first significant infrared (IR) electrochromism in Conducting Polymers (CPs), to our knowledge, with applications in battlefield countermeasures against night vision devices, and thermal control panels for spacecraft. Thin (<2 mm), flexible, variable area (1 cm(2) to 1 m(2)), entirely solid state, CP flat panels were developed, showing: high Reflectance variation, e.g. 15% to 68% at 10.5 microns, 45% to 73% at 16.5 microns, and 31% to 77% at 620 nm; switching times of < 1 sec; cyclabilities of 10(5) cycles; For spacecraft application: Gier-Dunkle measurements showed Emittance variations from 0.32 to 0.79, Solar Absorptance 0.39 to 0.79; operating temperatures -35 to + 85 C; ability to withstand gamma radiation to 7.6 MRad, vacuum to 10(-7) torr. Poly(aniline) with a polymeric-matrix dopant was the primary CP used. Recent issuance of our primary US patents permit disclosure of these data and discussion of the unique device design. C1 Ashwin Ushas Corp Inc, Lakewood, NJ 08701 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Lockheed Martin Astronaut, Denver, CO 80201 USA. RP Chandrasekhar, P (reprint author), Ashwin Ushas Corp Inc, 500 James St, Lakewood, NJ 08701 USA. NR 8 TC 34 Z9 38 U1 4 U2 13 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0379-6779 J9 SYNTHETIC MET JI Synth. Met. PD MAR 15 PY 2001 VL 119 IS 1-3 SI SI BP 293 EP 294 DI 10.1016/S0379-6779(00)01455-7 PG 2 WC Materials Science, Multidisciplinary; Physics, Condensed Matter; Polymer Science SC Materials Science; Physics; Polymer Science GA 433EC UT WOS:000168741500130 ER PT J AU Vuilleumier, P Sagiv, N Hazeltine, E Poldrack, RA Swick, D Rafal, RD Gabrieli, JDE AF Vuilleumier, P Sagiv, N Hazeltine, E Poldrack, RA Swick, D Rafal, RD Gabrieli, JDE TI Neural fate of seen and unseen faces in visuospatial neglect: A combined event-related functional MRI and event-related potential study SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID HUMAN EXTRASTRIATE CORTEX; PRIMARY VISUAL-CORTEX; HUMAN FUSIFORM GYRUS; UNILATERAL NEGLECT; SPATIAL NEGLECT; HUMAN BRAIN; PERCEPTION; ATTENTION; EXTINCTION; AWARENESS AB To compare neural activity produced by visual events that escape or reach conscious awareness, we used event-related MRI and evoked potentials in a patient who had neglect and extinction after focal right parietal damage, but intact visual fields. This neurological disorder entails a loss of awareness for stimuli in the field contralateral to a brain lesion when stimuli are simultaneously presented on the ipsilateral side, even though early visual areas may be intact, and single contralateral stimuli may still be perceived. Functional MRI and event-related potential study were performed during a task where faces or shapes appeared in the right, left, or both fields. Unilateral stimuli produced normal responses in V1 and extrastriate areas. In bilateral events, left faces that were not perceived still activated right V1 and inferior temporal cortex and evoked nonsignificantly reduced N1 potentials, with preserved face-specific negative potentials at 170 ms. When left faces were perceived, the same stimuli produced greater activity in a distributed network of areas including right V1 and cuneus, bilateral fusiform gyri, and left parietal cortex. Also, effective connectivity between visual, parietal, and frontal areas increased during perception of faces. These results suggest that activity can occur in V1 and ventral temporal cortex without awareness, whereas coupling with dorsal parietal and frontal areas may be critical for such activity to afford conscious perception. C1 UCL, Inst Cognit Neurosci, London WC1 3AR, England. Univ Calif Davis, Dept Neurol, Davis, CA 95616 USA. Vet Adm Med Ctr, Martinez, CA 94553 USA. Univ Calif Berkeley, Dept Psychol, Berkeley, CA 94720 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Stanford Univ, Dept Psychol, Stanford, CA 94305 USA. Massachusetts Gen Hosp, NMR Ctr, Charlestown, MA 02129 USA. Sch Psychol, Bangor LLS7 2DG, Gwynedd, Wales. RP Vuilleumier, P (reprint author), UCL, Inst Cognit Neurosci, Alexandra House,17 Queen Sq, London WC1 3AR, England. EM p.vuilleumier@ucl.ac.uk NR 49 TC 143 Z9 146 U1 4 U2 10 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 13 PY 2001 VL 98 IS 6 BP 3495 EP 3500 DI 10.1073/pnas.051436898 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 411WB UT WOS:000167521300100 PM 11248106 ER PT J AU Arepalli, S Nikolaev, P Holmes, W Files, BS AF Arepalli, S Nikolaev, P Holmes, W Files, BS TI Production and measurements of individual single-wall nanotubes and small ropes of carbon SO APPLIED PHYSICS LETTERS LA English DT Article AB This work focuses on the size and spatial dependence of single-wall carbon nanotubes produced by the pulsed-laser vaporization technique. The study indicates that very long (tens of microns) individual nanotubes form in the vicinity of the target, and subsequently coalesce into bundles. The role of the inner flow tube is confirmed to restrict plume expansion and improve interactions between carbon atoms resulting in nanotube and rope formation. The effect of the flowing buffer gas seems to influence the dispersion of particulate contaminant material in the nanotube product. More particulate matter is produced at lower oven temperatures. (C) 2001 American Institute of Physics. C1 GB Tech Inc Lockheed Martin, Houston, TX 77258 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Arepalli, S (reprint author), GB Tech Inc Lockheed Martin, POB 58561,Mail Stop C61, Houston, TX 77258 USA. RI Arepalli, Sivaram/A-5372-2010; Nikolaev, Pavel/B-9960-2009 NR 15 TC 36 Z9 36 U1 0 U2 6 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD MAR 12 PY 2001 VL 78 IS 11 BP 1610 EP 1612 DI 10.1063/1.1352659 PG 3 WC Physics, Applied SC Physics GA 409BM UT WOS:000167364700050 ER PT J AU Warner, JX Gille, JC Edwards, DP Ziskin, DC Smith, MW Bailey, PL Rokke, L AF Warner, JX Gille, JC Edwards, DP Ziskin, DC Smith, MW Bailey, PL Rokke, L TI Cloud detection and clearing for the Earth Observing System Terra satellite Measurements of Pollution in the Troposphere (MOPITT) experiment SO APPLIED OPTICS LA English DT Article ID RADIATIVE-TRANSFER; CARBON-MONOXIDE; INSTRUMENT; RADIOMETER; SURFACE; ISCCP; VARIABILITY; ATMOSPHERES; RADIANCES; METHANE AB The Measurements of Pollution in the Troposphere (MOPITT) instrument, which was launched aboard the Earth Observing System (EOS) Terra spacecraft on 18 December 1999, is designed to; measure tropospheric CO and CH4 by use of a nadir-viewing geometry. The measurements are taken at 4.7 mum in the thermal emission and absorption for the CO mixing ratio profile retrieval and at 2.3 and 2.2 mum in the reflected solar region for the total CO column amount and CH4 column amount retrieval, respectively. To achieve the required measurement accuracy, it is critical to identify and remove cloud contamination in the radiometric signals. We describe an algorithm to detect cloudy pixels, to reconstruct clear column radiance for pixels with partial cloud covers, and to estimate equivalent cloud top height for overcast conditions to allow CO profile retrievals above clouds. The MOPITT channel radiances, as well as the first-guess calculations, are simulated with a fast forward model with input atmospheric profiles from ancillary data sets. The precision of the retrieved CO profiles and total column amounts in cloudy atmospheres is within the expected +/-10% range. Validations of the cloud-detecting thresholds with the moderate-resolution imaging spectroradiometer airborne simulator data and MOPITT airborne test radiometer measurements were performed. The validation results showed that the MOPITT cloud detection thresholds work well for scenes covered with more than 5-10% cloud cover if the uncertainties in the model input profiles are less than 2 K for temperature, 10% for water vapor, and 5% for CO and CH4. (C) 2001 Optical Society of America. C1 Natl Ctr Atmospher Res, Div Atmospher Chem, Boulder, CO 80307 USA. NASA, Goddard Space Flight Ctr, Off Data Assimilat, Greenbelt, MD 20771 USA. RP Warner, JX (reprint author), Natl Ctr Atmospher Res, Div Atmospher Chem, POB 3000, Boulder, CO 80307 USA. EM juying@ncar.ucar.edu RI Rokke, Laurie/I-5642-2015 OI Rokke, Laurie/0000-0002-5696-7240 NR 33 TC 22 Z9 22 U1 1 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 10 PY 2001 VL 40 IS 8 BP 1269 EP 1284 DI 10.1364/AO.40.001269 PG 16 WC Optics SC Optics GA 409KN UT WOS:000167383000013 PM 18357114 ER PT J AU Macri, LM Calzetti, D Freedman, WL Gibson, BK Graham, JA Huchra, JP Hughes, SMG Madore, BF Mould, JR Persson, SE Stetson, PB AF Macri, LM Calzetti, D Freedman, WL Gibson, BK Graham, JA Huchra, JP Hughes, SMG Madore, BF Mould, JR Persson, SE Stetson, PB TI NICMOS observations of extragalactic Cepheids. I. Photometry database and a test of the standard extinction law SO ASTROPHYSICAL JOURNAL LA English DT Article DE Cepheids; distance scale; galaxies : stellar content ID HUBBLE-SPACE-TELESCOPE; SCALE KEY PROJECT; DISTANCE SCALE; PEAK BRIGHTNESS; DISCOVERY; CALIBRATION AB We present the results of near-infrared observations of extragalactic Cepheids made with the Near-Infrared Camera and Multi-Object Spectrometer on board the Hubble Space Telescope (HST). The variables are located in the galaxies IC 1613, IC 4182, M31, M81, M101, NGC 925, NGC 1365, NGC 2090, NGC 3198, NGC 3621, NGC 4496A, and NGC 4536. All fields were observed in the F160W bandpass; additional images were obtained in the F110W and F205W filters. Photometry was performed using the DAOPHOT II/ALLSTAR package. Self-consistent distance moduli and color excesses were obtained by fitting period-luminosity relations in the H, I, and V bands. Our results support the assumption of a standard reddening law adopted by the HST Key Project on the Extragalactic Distance Scale. A companion paper will determine true distance moduli and explore the effects of metallicity on the Cepheid distance scale. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Carnegie Inst Washington Observ, Pasadena, CA 91101 USA. Swinburne Univ Technol, Ctr Astrophys & Supercomp, Hawthorn, Vic 3122, Australia. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. Royal Greenwich Observ, Cambridge CB3 0EZ, England. CALTECH, NASA, IPAC, Pasadena, CA 91125 USA. Australian Natl Univ, Inst Adv Studies, Res Sch Astron & Astrophys, Mt Stromlo Observ, Weston Creek, ACT 2611, Australia. Natl Res Council Canada, Herzberg Inst Astrophys, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. RP Macri, LM (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St,MS 20, Cambridge, MA 02138 USA. RI Gibson, Brad/M-3592-2015; OI Gibson, Brad/0000-0003-4446-3130; Macri, Lucas/0000-0002-1775-4859 NR 28 TC 59 Z9 59 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 2001 VL 549 IS 2 BP 721 EP 744 DI 10.1086/319465 PN 1 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 413GX UT WOS:000167605200007 ER PT J AU Soker, M White, RE David, LP McNamara, BR AF Soker, M White, RE David, LP McNamara, BR TI A moderate cluster cooling flow model SO ASTROPHYSICAL JOURNAL LA English DT Article DE cooling flows; galaxies : clusters : general; intergalactic medium ID EMISSION-LINE NEBULAE; RAY LUMINOUS CLUSTERS; H-I ABSORPTION; GALAXY HYDRA-A; MAGNETIC-FIELDS; RADIO JETS; FARADAY-ROTATION; INTRACLUSTER MEDIUM; STAR-FORMATION; MOLECULAR GAS AB We propose that the outer portions of cooling flows in clusters of galaxies are frequently disrupted by radio jets and that their effective ages are much shorter than the cluster ages. The inner regions, where the gas density is higher, are more difficult to disrupt and may continue to harbor cooling flows even after disruption events. The main assumption of the proposed scenario is that, on a timescale of similar to2-4 x 10(9) yr, the cD galaxies in cooling flow clusters undergo powerful bursts of active galactic nucleus (AGN) activity that produce strong radio jets. The radio jets excite shocks in the inner regions (r less than or similar to 100 kpc) of cooling flow clusters. A radio burst may result from the accretion of cooling material by the central black hole or from a collision with a subcluster. We assume that the jets remain strong, with kinetic powers of similar to 10(47) ergs s(-1) for similar to 10(7) yr. The jets excite shock waves moving at several times 10(3) km s(-1) and heat the cooling flow region, hence terminating it in the outer regions. The proposed scenario predicts that the total accreted mass due to the cooling flow is an order of magnitude lower than the mass accreted according to the "standard" cooling flow model (which assumes an undisturbed cooling flow for a time equal to the age of the cluster). The scenario, therefore, brings into agreement the observations that (1) a large fraction of clusters harbor cooling flows, (2) strong optical and radio activity are present only in the very inner regions of cooling flows, and (3) there is a lack of a satisfactory reservoir of the expected (in the standard cooling flow model) large mass that has been cooling over the life of the cluster. C1 Univ Haifa Oranim, Dept Phys, IL-36006 Tivon, Israel. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Soker, M (reprint author), Univ Haifa Oranim, Dept Phys, IL-36006 Tivon, Israel. NR 66 TC 9 Z9 9 U1 1 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 2001 VL 549 IS 2 BP 832 EP 839 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 413GX UT WOS:000167605200014 ER PT J AU Habbal, SR Woo, R AF Habbal, SR Woo, R TI Connecting the sun and the solar wind: Comparison of the latitudinal profiles of coronal and Ulysses measurements of the fast wind SO ASTROPHYSICAL JOURNAL LA English DT Article DE solar wind; Sun : corona ID MAGNETIC-FIELD; INTERPLANETARY SPACE; HOLE; POLE AB A quantitative comparison of the latitudinal profile of polarized brightness (pB) measurements nearest the Sun at 1.15 R. by the Mauna Loa Solar Observatory K-Coronameter and Ulysses interplanetary measurements of the fast solar wind during its first south polar pass, at the declining phase of the solar cycle, is made for the first time to identify the sources of the fast solar wind in the context of coronal density structure. Both profiles are found to have the same shape. At the Sun, the minimum coincides with the radial extension of the coronal hole boundaries. The slight rise and plateau following this minimum toward lower latitudes are identified with the coronal extension of the quiet Sun. The corresponding profile of the in situ measured velocity has a maximum within the angular extent of the polar coronal hole and decreases gradually beyond its boundaries. The latitudinal profile of the proton flux mimics the density profile, implying that the mass-loss rate is lowest within the angular extent of the polar coronal hole. The association of the fast wind with a density profile that reflects the polar coronal hole and the surrounding quiet Sun suggests that the fast wind observed by Ulysses originates from both regions. That these conclusions differ from earlier published analyses of the same Ulysses measurements is a consequence of the quantitative and systematic comparison made between Ulysses and coronal measurements at 1.15 R.. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Habbal, SR (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. NR 29 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 MAR 10 PY 2001 VL 549 IS 2 BP L253 EP L256 DI 10.1086/319172 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 417JB UT WOS:000167830900023 ER PT J AU Lakshmi, V Czajkowski, K Dubayah, R Susskind, J AF Lakshmi, V Czajkowski, K Dubayah, R Susskind, J TI Land surface air temperature mapping using TOVS and AVHRR SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID HIGH-RESOLUTION RADIOMETER; NORMALIZED DIFFERENCE; VEGETATION INDEX; EVAPOTRANSPIRATION; LANDSCAPE AB Surface air temperature is an important variable in land surface hydrological studies. This paper evaluates the ability of satellites to map air temperature across large land surface areas. Algorithms recently have been developed that derive surface air temperature using observations from the TOVS (TIROS Operational Vertical Sounder) suite of instruments and also from the AVHRR (Advanced Very High Resolution Radiometer), which have flown on the NOAA operational sun synchronous satellites TIROS-N NOAA-14 In this study we evaluate TOVS soundings from NOAA-10 (nominal local time of overpass 7:30 a.m./p.m.) and data from AVHRR aboard NOAA-9 (nominal local time 2:30 a.m./p.m.). Instantaneous estimates from the AVHRR and TOVS were compared with the hourly ground observations collected from 26 meteorological stations in the Red River-Arkansas River basin for a 3-month period from Map to July 1987. Detailed comparisons between the satellite and ground estimates of surface air temperatures are reported and the feasibility of estimating the diurnal variation is explored. The comparisons are interpreted in the geographical context, i.e. land cover and topography, and in the seasonal context, i.e. early and midsummer. The results show that the average bias over the 3-month period compared with ground-based observations is approximately 2 degreesC or less for the three times of day with TOVS having lower biases than AVHRR. Knowledge of these error estimates will greatly benefit use of satellite data in hydrological modelling. C1 NASA, Atmospheres Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Toledo, Dept Geog & Planning, Toledo, OH 43606 USA. Univ Maryland, Dept Geog, College Pk, MD 20742 USA. RP Lakshmi, V (reprint author), NASA, Atmospheres Lab, Goddard Space Flight Ctr, Code 910-4, Greenbelt, MD 20771 USA. RI Lakshmi, Venkat/I-3078-2016 OI Lakshmi, Venkat/0000-0001-7431-9004 NR 35 TC 31 Z9 35 U1 0 U2 9 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD MAR 10 PY 2001 VL 22 IS 4 BP 643 EP 662 DI 10.1080/01431160050505900 PG 20 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 410FM UT WOS:000167429400010 ER PT J AU Katzberg, SJ Garrison, JL AF Katzberg, SJ Garrison, JL TI Surface reflected signals from the Global Positioning System for ionospheric measurements: experimental results at aircraft altitudes SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article AB Several spaceborne altimeters have been built and flown, and others are being developed, to provide measurements of ocean and ice sheet topography. Until the launch of TOPEX (Ocean Topography Experiment), altimeters were single-frequency systems that were incapable of removing the effects of ionospheric delay on the radar pulse. With the current state-of-the-art in satellite altimetry, the ionosphere causes the largest single error when using single-frequency altimeters. Ionospheric models provide the only recourse short of adding a second frequency to the altimeter. Unfortunately, measurements of the ionosphere are lacking over the oceans or ice sheets where they are most needed. A possible solution to the lack of data density may result from an expanded use of the Global Positioning System (GPS). This paper discusses how the reflection of the GPS signal from the ocean can be used to extend ionospheric measurements by simply adding a GPS receiver and downward-pointing antenna to satellites carrying single-frequency altimeters. The viability of this concept hinges upon the ability to acquire and code-track the reflected signal for an extended period of time over a variety of sea states. The theory of specularly and diffusely reflected radio frequency radiation from a rough surface is reviewed. Results of experiments to demonstrate tracking of a reflected signal are presented for three aircraft flights over the Chesapeake Bay and the Eastern Shore of Virginia. The experimental hardware consisted of two off-the-shelf receivers configured such that one received the GPS signal in the conventional manner using a right-hand circularly polarized (RHCP) antenna on top of the fuselage and the other could receive the reflected signal using a left-hand circularly polarized (LHCP) antenna on the bottom of the fuselage. Three tests were performed on the data to verify that the signals received in the bottom antenna were sea surface reflections: pseudorange double differences were compared against predicted geometric range double differences, characteristics of a signal reflected from a random surface were observed in the carrier to noise ratio and predicted specular points were plotted which demonstrate reflection only from wet areas. These tests indicated tracking of reflected signals for extended periods of time at altitudes of up to 5500 m and sporadic signal acquisition at higher altitudes. C1 NASA, Spacecraft & Sensors Branch, Langley Res Ctr, Hampton, VA 23681 USA. RP Katzberg, SJ (reprint author), NASA, Spacecraft & Sensors Branch, Langley Res Ctr, Hampton, VA 23681 USA. NR 12 TC 3 Z9 3 U1 0 U2 4 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD MAR 10 PY 2001 VL 22 IS 4 BP 663 EP 689 DI 10.1080/01431160050505919 PG 27 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 410FM UT WOS:000167429400011 ER PT J AU Vander Wal, RL Ticich, TM AF Vander Wal, RL Ticich, TM TI Comparative flame and furnace synthesis of single-walled carbon nanotubes SO CHEMICAL PHYSICS LETTERS LA English DT Article ID SPRAY-PYROLYSIS; DECOMPOSITION; PARTICLES; CO; DISPROPORTIONATION; HYDROCARBONS; MORPHOLOGY; DEPOSITION; ETHYLENE; MIXTURES AB In this Letter, results are reported for flame synthesis of single-wailed carbon nanotubes. A pyrolysis flame of CO/H-2 is established with introduction of the nanocatalyst precursor particles as an aerosol created by drying a nebulized solution of iron or iron colloid (in the form of ferrofluid). Results are compared to those produced by entraining the same catalyst aerosol into a tube furnace. Optimum flame gas flows and overall gas composition are reported and interpreted in terms of temperature and particle residence time. (C) 2001 Elsevier Science B.V. AII rights reserved. C1 NASA, Glenn Res Ctr, NCMR, Cleveland, OH 44135 USA. Centenary Coll Louisiana, Dept Chem, Shreveport, LA 71134 USA. RP Vander Wal, RL (reprint author), NASA, Glenn Res Ctr, NCMR, MS 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 35 TC 33 Z9 33 U1 3 U2 16 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 9 PY 2001 VL 336 IS 1-2 BP 24 EP 32 DI 10.1016/S0009-2614(01)00114-2 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 411YL UT WOS:000167527200005 ER PT J AU Baer, LA Wade, CE Plaut, K Ronca, AE AF Baer, LA Wade, CE Plaut, K Ronca, AE TI Effects of hypergravity exposure on plasma prolactin concentrations in pregnant, parturient and lactating rat dams SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Lockheed Martin, Moffett Field, CA 94035 USA. Univ Vermont, Burlington, VT 05405 USA. NR 0 TC 3 Z9 3 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 8 PY 2001 VL 15 IS 5 BP A796 EP A796 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454200478 ER PT J AU Barrett, JE Yu, DS Dalton, BP AF Barrett, JE Yu, DS Dalton, BP TI Nutritional evaluation of NASA's rodent Food Bar diet SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Lockheed Martin, 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 8 PY 2001 VL 15 IS 5 BP A960 EP A960 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454201421 ER PT J AU Clarke, MSF Hammond, DK Caldwell, RW Bamman, MM Vanderburg, CR Feeback, DL AF Clarke, MSF Hammond, DK Caldwell, RW Bamman, MM Vanderburg, CR Feeback, DL TI Cholesterol-mediated modulation of skeletal muscle membrane calcium pump function during mechanical unloading SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ Space Res Assoc, Houston, TX 77058 USA. Wiley Labs, Houston, TX 77058 USA. Med Coll Georgia, Augusta, GA 30912 USA. Univ Alabama, Birmingham, AL 35294 USA. Massachusetts Gen Hosp, Boston, MA 02114 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 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 8 PY 2001 VL 15 IS 5 BP A1116 EP A1116 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454202327 ER PT J AU D'Aunno, D Reyes, C Meck, J AF D'Aunno, D Reyes, C Meck, J TI P-R interval is prolonged after long- but not short-duration spaceflight. SO FASEB JOURNAL LA English DT Meeting Abstract C1 Natl Space Biomed Res Inst, Houston, TX USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Wyle Labs, Houston, TX 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 8 PY 2001 VL 15 IS 5 BP A1134 EP A1134 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454202430 ER PT J AU Davis-Street, JE Flory, SL Fanselow, SA Smith, SM AF Davis-Street, JE Flory, SL Fanselow, SA Smith, SM TI Validation and evaluation of body composition measurement methods for spaceflight. SO FASEB JOURNAL LA English DT Meeting Abstract C1 Enterprise Advisory Serv Inc, Houston, TX 77058 USA. Depauw Univ, Indiana, PA USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 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 8 PY 2001 VL 15 IS 5 BP A1003 EP A1003 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454201669 ER PT J AU Evans, JM Stenger, MB Kwong, E McIntosh, CM Brown, DR Patwardhan, AR Knapp, CF Simonson, SR Stocks, JM Cowell, SA Bailey, KN Vener, JM Evetts, SN Moore, FB Ziegler, MG AF Evans, JM Stenger, MB Kwong, E McIntosh, CM Brown, DR Patwardhan, AR Knapp, CF Simonson, SR Stocks, JM Cowell, SA Bailey, KN Vener, JM Evetts, SN Moore, FB Ziegler, MG TI Human powered centrifuge training effects on cardiovascular responses to head up tilt SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ Kentucky, Ctr Biomed Engn, Lexington, KY 40506 USA. NASA, Ames Res Ctr, Lab Human Environ Physiol, Moffett Field, CA USA. Univ Calif San Diego, San Diego, CA 92103 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 8 PY 2001 VL 15 IS 5 BP A795 EP A795 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454200475 ER PT J AU Fung, CK Baer, LA Moran, MM Wang, TJ Yuan, F Daunton, NG Corcoran, ML Wade, CE AF Fung, CK Baer, LA Moran, MM Wang, TJ Yuan, F Daunton, NG Corcoran, ML Wade, CE TI Effects of age on temperature responses during exposure to hypergravity SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Educ Associates, Moffett Field, CA 94035 USA. Lockheed Martin, Moffett Field, CA USA. NASA, Ames Res Ctr, Moffett Field, CA 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 8 PY 2001 VL 15 IS 5 BP A796 EP A796 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454200480 ER PT J AU Gillman, PL Davis-Street, JE Greer, VM Serfass, RE Smith, SM AF Gillman, PL Davis-Street, JE Greer, VM Serfass, RE Smith, SM TI Iodine intake and excretion: closed chamber studies using iodine as a bactericidal agent. SO FASEB JOURNAL LA English DT Meeting Abstract C1 Enterprise Advisory Serv Inc, Houston, TX 77058 USA. Texas Christian Univ, Ft Worth, TX 76129 USA. Univ Texas, Med Branch, Galveston, TX 77555 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 0 TC 1 Z9 1 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 8 PY 2001 VL 15 IS 5 BP A971 EP A971 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454201488 ER PT J AU Hales, NW Yamauchi, K Ramesh, V Yamamoto, S Pellis, NR Kulkarni, AD AF Hales, NW Yamauchi, K Ramesh, V Yamamoto, S Pellis, NR Kulkarni, AD TI Immunomodulatory nutritional countermeasure maintains immune response in microgravity. SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ Texas, Hlth Sci Ctr, Houston, TX 77030 USA. Univ Tokushima, Tokushima 770, Japan. 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 8 PY 2001 VL 15 IS 5 BP A1025 EP A1025 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454201800 ER PT J AU Knapp, CF Stenger, MB Kwong, E McIntosh, CM Brown, DR Patwardhan, AP Evans, JM Simonson, SR Stocks, JM Biagini, HW Cowell, SA Bailey, KN Vener, JM Evetts, SN Moore, FB Ziegler, MG AF Knapp, CF Stenger, MB Kwong, E McIntosh, CM Brown, DR Patwardhan, AP Evans, JM Simonson, SR Stocks, JM Biagini, HW Cowell, SA Bailey, KN Vener, JM Evetts, SN Moore, FB Ziegler, MG TI Passive acceleration training and cardiovascular responses to head up tilt SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ Kentucky, Lexington, KY 40506 USA. Univ Kentucky, Ctr Biomed Engn, Lexington, KY 40506 USA. NASA, Ames Res Ctr, Moffett Field, CA USA. Univ Calif San Diego, San Diego, CA 92103 USA. NR 0 TC 0 Z9 0 U1 1 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 8 PY 2001 VL 15 IS 5 BP A795 EP A795 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454200473 ER EF