FN Thomson Reuters Web of Science™ VR 1.0 PT J AU Gorjian, V Wright, EL Chary, RR AF Gorjian, V Wright, EL Chary, RR TI Tentative detection of the cosmic infrared background at 2.2 and 3.5 microns using ground-based and space-based observations SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; diffuse radiation; infrared : general ID UPPER LIMIT; DUST; GALAXIES; PERFORMANCE; ULTRAVIOLET; RADIATION; SPECTRUM; EMISSION; MODEL; LIGHT AB The cosmic infrared background (CIRB) is the sum total of the redshifted and reprocessed short-wavelength radiation from the era of galaxy formation, and hence contains vital information about the history of galactic evolution. One of the main problems associated with estimating an isotropic CIRB in the near-infrared (1-5 mu m) is the unknown contribution from stars within our own Galaxy. The optimal observational window to search for a background in the near-IR is at 3.5 mu m since that is the wavelength region where the other main foreground, the zodiacal dust emission, is the least. It is not possible to map out the entire 3.5 mu m sky at a resolution that will accurately estimate the flux from stars. However, since the CIRB is presumably isotropic, it can potentially be detected by selecting a smaller field and imaging it at good resolution to estimate the stellar intensity. We selected a 2 degrees x 2 degrees "dark spot" near the north Galactic pole which had the least intensity at 3.5 mu m after a zodiacal light model was subtracted from the all-sky maps generated by the Diffuse Infrared Background Experiment (DIRBE). Still, the large area of the held made it very difficult to mosaic at 3.5 mu m using the available arrays. Thus, the held was mosaicked at 2.2 mu m, then the bright stars were selected and reimaged at 2.2 and 3.5 mu m. The resulting total intensity of the bright stars was combined with a model for the contribution from dimmer stars and subtracted from the zodi-subtracted DIRBE map. The contribution from the interstellar medium was also subtracted, leaving a residual intensity at 2.2 mu m of 16.4 +/- 4.4 kJy sr(-1) or 22.4 +/- 6.0 nW m(-2) sr(-1), and at 3.5 mu m of 12.8 +/- 3.8 kJy sr(-1) or 11.0 +/- 3.3 nW m(-2) sr(-1). The nature of our analysis suggests that this excess emission is probably a detection of the cosmic background in the near-infrared. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM vg@jpl.nasa.gov; wright@astro.ucla.edu; rchary@astro.ucla.edu NR 41 TC 123 Z9 123 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 JUN 20 PY 2000 VL 536 IS 2 BP 550 EP 560 DI 10.1086/308974 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335EQ UT WOS:000088230900005 ER PT J AU Koide, S Meier, DL Shibata, K Kudoh, T AF Koide, S Meier, DL Shibata, K Kudoh, T TI General relativistic simulations of early jet formation in a rapidly rotating black hole magnetosphere SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; black hole physics; galaxies : jets; magnetic fields; methods : numerical; MHD; relativity ID MAGNETICALLY DRIVEN JETS; ACCRETION DISKS; ASTROPHYSICAL JETS; STEADY SOLUTIONS; ENERGY; EXTRACTION; FIELD; GALAXY; WINDS; MASS AB To investigate the formation mechanism of relativistic jets in active galactic nuclei and microquasars, we have developed a new general relativistic magnetohydrodynamic code in Kerr geometry. Here we report on the first numerical simulations of jet formation in a rapidly rotating (a = 0.95) Kerr black hole magnetosphere. Fire study cases in which the Keplerian accretion disk is both corotating and counterrotating with respect to the black hole rotation, and investigate the first similar to 50 light-crossing times. In the corotating disk case, our results are almost the same as those in Schwarzschild black hole cases: a gas pressure-driven jet is formed by a shock in the disk, and a weaker magnetically driven jet is also generated outside the gas pressure-driven jet. On the other hand, in the counter-rotating disk case, a new powerful magnetically driven jet is formed inside the gas pressure-driven jet. The newly found magnetically driven jet in the latter case is accelerated by a strong magnetic field created by frame dragging in the ergosphere. Through this process, the magnetic field extracts the energy of the black hole rotation. C1 Toyama Univ, Fac Engn, Toyama 9308555, Japan. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Kyoto Univ, Kwasan Observ, Kyoto 6078471, Japan. Kyoto Univ, Hida Observ, Kyoto 6078471, Japan. Natl Astron Observ, Mitaka, Tokyo 1818588, Japan. RP Toyama Univ, Fac Engn, Gofuku 3190, Toyama 9308555, Japan. NR 36 TC 108 Z9 108 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 2000 VL 536 IS 2 BP 668 EP 674 DI 10.1086/308986 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335EQ UT WOS:000088230900013 ER PT J AU Verter, F Magnani, L Dwek, E Rickard, LJ AF Verter, F Magnani, L Dwek, E Rickard, LJ TI Infrared properties of molecular cirrus. II. Cloud-to-cloud variations in graphite and polycyclic aromatic hydrocarbon content SO ASTROPHYSICAL JOURNAL LA English DT Review DE dust, extinction; ISM : clouds; ISM : molecules ID HIGH-LATITUDE CLOUDS; DIFFUSE GALACTIC EMISSION; H-2 CONVERSION FACTOR; X-RAY ENHANCEMENT; TEMPERATURE-FLUCTUATIONS; INTERSTELLAR GRAINS; IR EMISSION; DARK NEBULAE; ULTRAVIOLET EXTINCTION; TRANSLUCENT CLOUDS AB We have conducted a photometric survey of translucent molecular clouds in the four IRAS wave bands. We find notable cloud-to-cloud variations in mid-IR emission, with the ratio I,,II,, varying by up to 1 order of magnitude and often above unity. Because the clouds in our sample are nearby and translucent? the cloud heating is well constrained, so that the observed differences in infrared emission must represent differences in grain content. We show from first principles that a dust model containing only two components, Mathis-Rumpl-Nordsieck (MRN) grains in thermal equilibrium and very small grains undergoing stochastic heating, can never produce I-12/I-25 greater than or equal to 1 under the conditions that prevail in the cloudy interstellar medium. We fit the clouds in this sample with a three-component model which contains continuum emission from both MRN grains and very small graphite grains, plus emission features from a mixture of polycyclic aromatic hydrocarbon (PAH). The cloud-to-cloud variations in mid-IR emission require significant differences in their composition of small grains and PAH molecules. Models which describe the formation and evolution of these particles in the interstellar medium must explain the presence of these variations in a cloud sample which is located in the solar neighborhood. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. Univ Georgia, Dept Phys & Astron, Athens, GA 30602 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. USN, Res Lab, Remote Sensing Div, Washington, DC 20375 USA. RP NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 910-3, Greenbelt, MD 20771 USA. EM verter@dao.gsfc.nasa.gov; loris@milan.physast.uga.edu; eli.dwek@gsfc.nasa.gov; rickard@rsd.nrl.navy.mil NR 129 TC 11 Z9 11 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 2000 VL 536 IS 2 BP 831 EP 844 DI 10.1086/308945 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335EQ UT WOS:000088230900026 ER PT J AU Boden, AF Creech-Eakman, MJ Queloz, D AF Boden, AF Creech-Eakman, MJ Queloz, D TI The visual orbit and evolutionary state of 12 Bootis SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : spectroscopic; binaries : visual; stars : evolution; stars : individual (12 Bootis) ID PALOMAR TESTBED INTERFEROMETER; SOLAR-TYPE STARS; PROTOTYPE OPTICAL INTERFEROMETER; FLUX METHOD IRFM; ROTATIONAL VELOCITY; ANGULAR DIAMETERS; EVOLVED STARS; BINARY STARS; SYSTEMS; CATALOG AB We report on the determination of the visual orbit of the double-lined spectroscopic binary system 12 Bootis with data obtained by the Palomar Testbed Interferometer in 1998 and 1999. 12 Boo is a nearly equal-mass double-lined binary system whose spectroscopic orbit is well known. We have estimated the visual orbit of 12 Boo from our interferometric visibility data fitted both separately and in conjunction with archival and CORAVEL radial velocity data. Our 12 Boo orbit is in good agreement with the spectroscopic results, and the physical parameters implied by a combined fit to our visibility data and radial velocity data result in precise component masses. In particular, the orbital parallax of the system is determined to be 27.09 +/- 0.41 mas, and masses of the two components are determined to be 1.435 +/- 0.023 M-circle dot and 1.409 +/- 0.020 M-circle dot, respectively. Somewhat remarkably, even though the two components are nearly equal mass, the system exhibits a significant brightness difference between the components in the near-infrared and visible. We attribute this brightness difference to evolutionary differences between the two components in their transition between main-sequence and giant evolutionary phases, and based on theoretical isochrones we can estimate a system age. Further, because the atmospheres of the two components are becoming more convective, we suggest the system components are currently at or near synchronous rotation, and the system orbit is in the process of circularizing. C1 CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Observ Geneva, CH-1290 Sauverny, Switzerland. RP Boden, AF (reprint author), CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. NR 46 TC 38 Z9 38 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 2000 VL 536 IS 2 BP 880 EP 890 DI 10.1086/308976 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335EQ UT WOS:000088230900031 ER PT J AU Seward, FD Alpar, MA Flanagan, C Kiziloglu, U Markwardt, C McCulloch, P Ogelman, H AF Seward, FD Alpar, MA Flanagan, C Kiziloglu, U Markwardt, C McCulloch, P Ogelman, H TI ROSAT observations of the Vela pulsar SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : individual (Vela pulsar); stars : neutron; X-rays : stars ID X-RAY-EMISSION; NEUTRON-STAR; THERMAL RESPONSE; MATTER; EQUATION; GLITCHES AB The ROSAT HRI was used to monitor X-ray emission from the Vela pulsar. Six observations span 2.5 yr and three glitches. The summed data yield a determination of the pulse shape, and X-ray emission from the pulsar is found to be 12% pulsed with one broad and two narrow peaks. One observation occurred 15 days after a large glitch. No change in pulse structure was observed, and any change in X-ray luminosity, if present, was less than 3%. Implications for neutron star structure are discussed. C1 Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. Sabanci Univ, TR-81474 Istanbul, Turkey. Hartebeesthoek Radio Observ, ZA-1740 Krugersdorp, Transvaal, South Africa. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Tasmania, Sch Phys, Hobart, Tas, Australia. Univ Wisconsin, Dept Phys, Madison, WI 53706 USA. RP Seward, FD (reprint author), Smithsonian Astrophys Observ, 60 Garden St, Cambridge, MA 02138 USA. NR 28 TC 8 Z9 8 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 2000 VL 536 IS 2 BP 948 EP 953 DI 10.1086/308961 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335EQ UT WOS:000088230900038 ER PT J AU Brekke, P Thompson, WT Woods, TN Eparvier, FG AF Brekke, P Thompson, WT Woods, TN Eparvier, FG TI The extreme-ultraviolet solar irradiance spectrum observed with the coronal diagnostic spectrometer (CDS) on SOHO SO ASTROPHYSICAL JOURNAL LA English DT Article DE solar-terrestrial relations; Sun : atmosphere; Sun : corona; Sun : chromosphere; Sun : transition region; Sun : UV radiation ID EUV IRRADIANCE; QUIET SUN; SPECTROSCOPY; CALIBRATION AB We present a calibrated solar EUV irradiance spectrum in the ranges 307-380 Angstrom and 515-632 Angstrom. The "Sun as a star" spectrum was recorded by the Coronal Diagnostic Spectrometer (CDS) on SOHO on 1997 May 15 using the normal incidence spectrometer (NIS) with a spectral resolution between 0.3 and 0.6 Angstrom. The relatively high spectral resolution allows the separation of blends and the differentiation of weak emission lines. The full-disk spectrum is compared with simultaneous well-calibrated EUV irradiance measurements from a NASA/LASP rocket payload to validate the preflight calibration of CDS. Significant errors in the preflight calibration were found, and a new calibration has been established for the CDS/NIS system. The present spectrum includes emission lines formed in the temperature range 10(4) to over 10(6) K. Line fluxes for the most prominent lines are extracted for the calibration and for the solar irradiance studies. This measurement should represent well solar minimum conditions as the daily 10.7 cm radio flux was 73 (units of 10(-22) W m(-2) Hz(-1)). A modest spatial resolution, constrained by the observing mode used, allows for the discrimination between quiet and active sun. The calibrated quiet-Sun irradiance spectrum is compared with previous measurements. C1 NASA, Goddard Space Flight Ctr, ESA, Dept Space Sci, Greenbelt, MD 20771 USA. SM&A Corp, Div Space Sci, Largo, MD 20774 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. RP Brekke, P (reprint author), NASA, Goddard Space Flight Ctr, ESA, Dept Space Sci, Code 682-3, Greenbelt, MD 20771 USA. RI Thompson, William/D-7376-2012 NR 35 TC 39 Z9 39 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 2000 VL 536 IS 2 BP 959 EP 970 DI 10.1086/308966 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335EQ UT WOS:000088230900040 ER PT J AU Wang, HM Goode, PR Denker, C Yang, G Yurchishin, V Nitta, N Gurman, JB Cyr, CS Kosovichev, AG AF Wang, HM Goode, PR Denker, C Yang, G Yurchishin, V Nitta, N Gurman, JB Cyr, CS Kosovichev, AG TI Comparison of the 1998 April 29 M6.8 and 1998 November 5 M8.4 flares SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : corona; Sun : flares; Sun : magnetic fields ID CORONAL MASS EJECTION; SOHO MISSION; SOLAR-FLARES; EARTH; TELESCOPE; LASCO; EIT AB We combined, and analyzed in detail, the H alpha and magnetograph data from Big Bear Solar Observatory (BBSO), full-disk magnetograms from the Michelson Doppler Imager (MDI) on board Solar and Heliospheric Observatory (SOHO), coronagraph data from the Large Angle Spectrometric Coronagraph (LASCO) of SOHO, Fe XII 195 Angstrom data from the Extreme ultraviolet Imaging Telescope (EIT) of SOHO, and Yohkoh soft X-ray telescope (SXT) data of the M6.8 flare of 1998 April 29 in National Oceanic and Atmospheric Administration (NOAA) region 8375 and the M8.4 flare of 1998 November 5 in NOAA region 8384. These two flares have remarkable similarities: 1. Partial halo coronal mass ejections (CMEs) were observed for both events. For the 1998 April 29 event, even though the flare occurred in the southeast of the disk center, the ejected material moved predominantly across the equator, and the central part of the CME occurred in the northeast limb. The direction in which the cusp points in the postflare SXT images determines the dominant direction of the CMEs. 2. Coronal dimming was clearly observed in EIT Fe XII 195 Angstrom for both but was not observed in Yohkoh SXT for either event. Dimming started 2 hr before the onset of the flares, indicating large-scale coronal restructuring before both flares. 3. No global or local photospheric magnetic field change was detected from either event; in particular, no magnetic field change was found in the dimming areas. 4. Both events lasted several hours and, thus, could be classified as long duration events (LDEs). However, they are different in the following important aspects. For the 1998 April 29 event, the flare and the CME are associated with an erupting filament in which the two initial ribbons were well connected and then gradually separated. SXT preflare images show the classical S-shape sheared configuration (sigmoid structure). For the 1998 November 5 event, two initial ribbons were well separated, and the SXT preflare image shows the interaction of at least two loops. In addition, no filament eruption was observed. We conclude that even though these two events resulted in similar coronal consequences, they are due to two distinct physical processes: eruption of sheared loops and interaction of two loops. C1 New Jersey Inst Technol, Big Bear Solar Observ, Big Bear City, CA 92314 USA. Lockheed Martin Solar & Astrophys Lab, Palo Alto, CA USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USN, Res Lab, Computat Phys Inc, Washington, DC 20375 USA. Stanford Univ, WW Hansen Expt Phys Lab, Stanford, CA 94305 USA. RP Wang, HM (reprint author), New Jersey Inst Technol, Big Bear Solar Observ, 40386 N Shore Lane, Big Bear City, CA 92314 USA. NR 21 TC 33 Z9 35 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 2000 VL 536 IS 2 BP 971 EP 981 DI 10.1086/308964 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335EQ UT WOS:000088230900041 ER PT J AU Kashlinsky, A Atrio-Barandela, F AF Kashlinsky, A Atrio-Barandela, F TI Measuring cosmological bulk flows via the kinematic Sunyaev-Zeldovich effect in the upcoming cosmic microwave background maps SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; galaxies : clusters : general; large-scale structure of universe ID INTRACLUSTER GAS; T RELATION; CLUSTERS; GALAXIES AB We propose a new method for measuring the possible large-scale bulk flows in the universe from the cosmic microwave background (CMB) maps from the upcoming missions of the Microwave Anistropy Probe (MAP) and Planck. This can be done by studying the statistical properties of the CMB temperature field at many X-ray cluster positions. At each cluster position, the CMB temperature fluctuation will be a combination of the Sunyaev-Zeldovich (SZ) kinematic and thermal components, the cosmological fluctuations, and the instrument noise term. When averaged over many such clusters, the last three will integrate down, whereas the first one will be dominated by a possible bulk flow component. In particular, We propose to use all-sky X-ray cluster catalogs that should (or could) be available soon from X-ray satellites and then to evaluate the dipole component of the CMB field at the cluster positions. We show that for the MAP and Planck mission parameters, the dominant contributions to the dipole will be from the terms that are due to the SZ kinematic effect produced by the bulk flow (the signal we seek) and the instrument noise (the noise in our signal). Then, by computing the expected signal-to-noise ratio for such measurement, we find that at the 95% confidence level, the bulk flows on scales greater than or equal to 100 h(-1) Mpc can be probed down to the amplitude of less than 200 km s(-1) with the MAP data and down to only similar or equal to 30 km s(-1) with the Planck mission. C1 NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. Univ Salamanca, Fac Ciencias, E-37008 Salamanca, Spain. RP Kashlinsky, A (reprint author), NASA, Goddard Space Flight Ctr, Raytheon ITSS, Code 685, Greenbelt, MD 20771 USA. RI Atrio-Barandela, Fernando/A-7379-2017 OI Atrio-Barandela, Fernando/0000-0002-2130-2513 NR 25 TC 35 Z9 35 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 2000 VL 536 IS 2 BP L67 EP L71 DI 10.1086/312735 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335ER UT WOS:000088231000003 ER PT J AU Mauskopf, PD Ade, PAR de Bernardis, P Bock, JJ Borrill, J Boscaleri, A Crill, BP DeGasperis, G De Troia, G Farese, P Ferreira, PG Ganga, K Giacometti, M Hanany, S Hristov, VV Iacoangeli, A Jaffe, AH Lange, AE Lee, AT Masi, S Melchiorri, A Melchiorri, F Miglio, L Montroy, T Netterfield, CB Pascale, E Piacentini, F Richards, PL Romeo, G Ruhl, JE Scannapieco, E Scaramuzzi, F Stompor, R Vittorio, N AF Mauskopf, PD Ade, PAR de Bernardis, P Bock, JJ Borrill, J Boscaleri, A Crill, BP DeGasperis, G De Troia, G Farese, P Ferreira, PG Ganga, K Giacometti, M Hanany, S Hristov, VV Iacoangeli, A Jaffe, AH Lange, AE Lee, AT Masi, S Melchiorri, A Melchiorri, F Miglio, L Montroy, T Netterfield, CB Pascale, E Piacentini, F Richards, PL Romeo, G Ruhl, JE Scannapieco, E Scaramuzzi, F Stompor, R Vittorio, N TI Measurement of a peak in the cosmic microwave background power spectrum from the North American test flight of Boomerang SO ASTROPHYSICAL JOURNAL LA English DT Article DE balloons; cosmic microwave background; cosmology : observations; instrumentation : photometers; methods : data analysis; telescopes ID LOSING INFORMATION; ANISOTROPY; MAPS; SUBMILLIMETER; JUPITER AB We describe a measurement of the angular power spectrum of anisotropies in the cosmic microwave background (CMB) at scales of 0 degrees.3 to 5 degrees from the North American test flight of the Boomerang experiment. Boomerang is a balloon-borne telescope with a bolometric receiver designed to map CMB anisotropies on a long-duration balloon flight. During a 6 hr test flight of a prototype system 1997, we mapped more than 200 deg(2) at high Galactic latitudes in two bands centered at 90 and 150 GHz with a resolution of 26' and 16.'5 FWHM, respectively. Analysis of the maps gives a power spectrum with a peak at angular scales of 1 degrees with an amplitude 70 K-mu(CMB). C1 Univ Massachusetts, Dept Phys & Astron, Amherst, MA 01003 USA. Univ Wales, Dept Phys & Astron, Cardiff CF1 3NS, S Glam, Wales. Univ London Queen Mary & Westfield Coll, London E1 4NS, England. Univ La Sapienza, Dipartimento Fis, I-00185 Rome, Italy. CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Berkeley, Ctr Particle Astrophys, Berkeley, CA 94720 USA. LBNL, Natl Energy Res Sci Comp Ctr, Berkeley, CA USA. CNR, Ist Ric Onde Elettromagneitche, Florence, Italy. Univ Roma Tor Vergata, Dipartimento Fis, I-00173 Rome, Italy. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. Inst Super Tecn, Ctr Multidisciplinar Astrofis, Lisbon, Portugal. CERN, Div Theory, CH-1211 Geneva, Switzerland. Coll France, F-75231 Paris 05, France. Ctr Infrared Proc & Anal, Pasadena, CA USA. Univ Minnesota, Dept Phys, Minneapolis, MN 55455 USA. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. Univ Geneva, Dept Phys Theor, CH-1211 Geneva, Switzerland. Univ Toronto, Dept Phys, Toronto, ON, Canada. Univ Toronto, Dept Astron, Toronto, ON, Canada. Ist Nazl Geofis, I-00161 Rome, Italy. RP Mauskopf, PD (reprint author), Univ Massachusetts, Dept Phys & Astron, Amherst, MA 01003 USA. RI Jaffe, Andrew/D-3526-2009; de Gasperis, Giancarlo/C-8534-2012 OI de Gasperis, Giancarlo/0000-0003-2899-2171 NR 29 TC 115 Z9 116 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 2000 VL 536 IS 2 BP L59 EP L62 DI 10.1086/312743 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335ER UT WOS:000088231000001 ER PT J AU Melchiorri, A Ade, PAR de Bernardis, P Bock, JJ Borrill, J Boscaleri, A Crill, BP De Troia, G Farese, P Ferreira, PG Ganga, K de Gasperis, G Giacometti, M Hristov, VV Jaffe, AH Lange, AE Masi, S Mauskopf, PD Miglio, L Netterfield, CB Pascale, E Piacentini, F Romeo, G Ruhl, JE Vittorio, N AF Melchiorri, A Ade, PAR de Bernardis, P Bock, JJ Borrill, J Boscaleri, A Crill, BP De Troia, G Farese, P Ferreira, PG Ganga, K de Gasperis, G Giacometti, M Hristov, VV Jaffe, AH Lange, AE Masi, S Mauskopf, PD Miglio, L Netterfield, CB Pascale, E Piacentini, F Romeo, G Ruhl, JE Vittorio, N TI A measurement of Omega from the North American test flight of Boomerang SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; dark matter; methods : data analysis ID MICROWAVE BACKGROUND ANISOTROPIES; ANGULAR POWER SPECTRUM; OPEN UNIVERSE; CONSTRAINTS; INFLATION; LAMBDA AB We use the angular power spectrum of the cosmic microwave background, measured during the North American test flight of the Boomerang experiment, to constrain the geometry of the universe. Within the class of cold dark matter models, we find that the overall fractional energy density of the universe Omega is constrained to be 0.85 less than or equal to Omega less than or equal to 1.25 at the 68% confidence level. Combined with the COBE measurement, the data on degree scales from the Microwave Anisotropy Telescope in Chile, and the high-redshift supernovae data, we obtain new constraints on the fractional matter density and the cosmological constant. C1 Univ Rome La Sapienza, Dipartimento Fis, Rome, Italy. Univ Roma Tor Vergata, Dipartimento Fis, I-00173 Rome, Italy. Univ Geneva, Dept Phys Theor, CH-1211 Geneva, Switzerland. Univ London Queen Mary & Westfield Coll, London E1 4NS, England. CALTECH, Pasadena, CA 91125 USA. Jet Prop Lab, Pasadena, CA USA. Univ Calif Berkeley, Ctr Particle Astrophys, Berkeley, CA 94720 USA. Lawrence Berkeley Lab, Natl Energy Res Sci Comp Ctr, Berkeley, CA USA. CNR, Ist Ric Onde Elettromagneitche, Florence, Italy. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. Inst Super Tecn, Ctr Multidisciplinar Astrofis, Lisbon, Portugal. CERN, Div Theory, European Lab Particle Phys, CH-1211 Geneva, Switzerland. Coll France, F-75231 Paris 05, France. Univ Massachusetts, Dept Phys & Astron, Amherst, MA USA. Univ Toronto, Dept Phys, Toronto, ON, Canada. Univ Toronto, Dept Astron, Toronto, ON, Canada. Ist Nazl Geofis, I-00161 Rome, Italy. RP Melchiorri, A (reprint author), Univ Rome La Sapienza, Dipartimento Fis, Rome, Italy. RI Jaffe, Andrew/D-3526-2009; de Gasperis, Giancarlo/C-8534-2012; Piacentini, Francesco/E-7234-2010; OI de Gasperis, Giancarlo/0000-0003-2899-2171; Piacentini, Francesco/0000-0002-5444-9327; Melchiorri, Alessandro/0000-0001-5326-6003 NR 30 TC 142 Z9 142 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 2000 VL 536 IS 2 BP L63 EP L66 DI 10.1086/312744 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335ER UT WOS:000088231000002 ER PT J AU Weisskopf, MC Hester, JJ Tennant, AF Elsner, RF Schulz, NS Marshall, HL Karovska, M Nichols, JS Swartz, DA Kolodziejczak, JJ O'Dell, SL AF Weisskopf, MC Hester, JJ Tennant, AF Elsner, RF Schulz, NS Marshall, HL Karovska, M Nichols, JS Swartz, DA Kolodziejczak, JJ O'Dell, SL TI Discovery of spatial and spectral structure in the X-ray emission from the Crab Nebula SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (Crab Nebula); pulsars : individual (Crab Pulsar); radiation mechanisms : nonthermal; stars : neutron; supernova remnants; X-rays : general ID PULSAR WINDS; POLARIZATION; MODEL AB The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the Xray spectrum throughout the nebula. C1 NASA, Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. Arizona State Univ, Dept Phys & Astron, Tempe, AZ 85287 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. RP Weisskopf, MC (reprint author), NASA, Marshall Space Flight Ctr, Dept Space Sci, SD50, Huntsville, AL 35812 USA. NR 24 TC 260 Z9 262 U1 2 U2 5 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 2000 VL 536 IS 2 BP L81 EP L84 DI 10.1086/312733 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335ER UT WOS:000088231000006 ER PT J AU Tippett, MK Cohn, SE Todling, R Marchesin, D AF Tippett, MK Cohn, SE Todling, R Marchesin, D TI Conditioning of the stable, discrete-time Lyapunov operator SO SIAM JOURNAL ON MATRIX ANALYSIS AND APPLICATIONS LA English DT Article DE Lyapunov matrix equation; condition estimates; large-scale systems; radius of stability ID STABILITY; EQUATION; SYSTEMS; BOUNDS; SPACE AB The Schatten p-norm condition of the discrete-time Lyapunov operator L-A defined on matrices P is an element of R-nxn by LAP = P - APA(T) is studied for stable matrices A is an element of R-nxn. Bounds are obtained for the norm of L-A and its inverse that depend on the spectrum, singular values, and radius of stability of A. Since the solution P of the discrete-time algebraic Lyapunov equation ( DALE) LAP = Q can be ill-conditioned only when either L-A or Q is ill-conditioned, these bounds are useful in determining whether P admits a low-rank approximation, which is important in the numerical solution of the DALE for large n. C1 Columbia Univ, Lamont Doherty Earth Observ, IRI, Palisades, NY 10964 USA. Ctr Previsao Tempo & Estudos Climat, Cachoeira Paulista, SP, Brazil. NASA, Data Assimilat Off, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Gen Sci Corp, SAIC, GSFC,DAO, Greenbelt, MD 20771 USA. Inst Matemat Pura & Aplicada, Rio De Janeiro, Brazil. RP Tippett, MK (reprint author), Columbia Univ, Lamont Doherty Earth Observ, IRI, Palisades, NY 10964 USA. RI Tippett, Michael/C-6286-2011; Cohn, Stephen/K-1954-2012 OI Tippett, Michael/0000-0002-7790-5364; Cohn, Stephen/0000-0001-8506-9354 NR 23 TC 7 Z9 7 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 0895-4798 J9 SIAM J MATRIX ANAL A JI SIAM J. Matrix Anal. Appl. PD JUN 20 PY 2000 VL 22 IS 1 BP 56 EP 65 DI 10.1137/S0895479899354822 PG 10 WC Mathematics, Applied SC Mathematics GA 333AA UT WOS:000088105500005 ER PT J AU Vander Wal, RL Ticich, TM Curtis, VE AF Vander Wal, RL Ticich, TM Curtis, VE TI Diffusion flame synthesis of single-walled carbon nanotubes SO CHEMICAL PHYSICS LETTERS LA English DT Article ID SOOT FORMATION; HYDROCARBONS; CATALYSIS; TUBULES; FUEL AB Flame synthesis is demonstrated for the synthesis of single-wall nanotubes via a simple laboratory-scale diffusion flame. Results using different hydrocarbon reagents, the effects of dilution with an inert, the role of hydrogen and processes likely accountable for the deactivation of the catalyst particles are illustrated and discussed. Finally, a plot of the integrated residence time-temperature history of a fluid parcel along the flame axis indicates carbon nanotube growth occurring within 2.0 ms, thus demonstrating the great potential of flame synthesis for large-scale commercial production of nanotubes. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, NCMR, Cleveland, OH 44135 USA. Centenary Coll Louisiana, Dept Chem, Shreveport, LA 71134 USA. RP Vander Wal, RL (reprint author), NASA, NCMR, MS 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 34 TC 101 Z9 102 U1 1 U2 14 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JUN 16 PY 2000 VL 323 IS 3-4 BP 217 EP 223 DI 10.1016/S0009-2614(00)00522-4 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 326LW UT WOS:000087737900003 ER PT J AU Zhang, H Roehl, CM Sander, SP Wennberg, PO AF Zhang, H Roehl, CM Sander, SP Wennberg, PO TI Intensity of the second and third OH overtones of H2O2, HNO3, and HO2NO2 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ABSORPTION CROSS-SECTION; PERNITRIC ACID; TEMPERATURE-DEPENDENCE; NO2; HYDROGEN; RADICALS AB The 3 nu(OH) and 4 nu(OH) of H2O, HNO3, and HO2NO2 have been observed. The band strengths of 3 nu(OH) are (7.0 +/- 1.8) x 10(-20) (2.9 +/- 0.7) x 10(-20), and (3.8 +/- 1.1) x 10(-20) cm(2) molecules(-1) cm(-1) for H2O2 HNO3, and HO2NO2 respectively. Those of 4 nu(OH) are (4.5 +/- 1.6) x 10(-21), (2.8 +/- 1.0) x 10(-21) and (3.0 +/- 1.8) x 10(-21) cm molecules(-1) cml for H2O2, HNO3, and HO2NO2, respectively, The uncertainty is for one standard deviation. Assuming excitation of these modes by solar absorption is dissociative for HO2NO2, these measurements confirm that this process will play a small role in the atmospheric photochemistry of the lower stratosphere. C1 CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Program Environm Engn, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Zhang, H (reprint author), CALTECH, Div Geol & Planetary Sci, M-S 150-21, Pasadena, CA 91125 USA. EM hui@gps.caltech.edu; coleen@gps.caltech.edu; ssander@jpl.nasa.gov; wennberg@gps.caltech.edu RI Wennberg, Paul/A-5460-2012 NR 16 TC 34 Z9 34 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 16 PY 2000 VL 105 IS D11 BP 14593 EP 14598 DI 10.1029/2000JD900118 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 326LB UT WOS:000087736000019 ER PT J AU Leblanc, T McDermid, IS AF Leblanc, T McDermid, IS TI Stratospheric ozone climatology from lidar measurements at Table Mountain (34.4 degrees N, 117.7 degrees W) and Mauna Loa (19.5 degrees N, 155.6 degrees W) SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MIDDLE ATMOSPHERE; POLAR VORTEX; DIAL SYSTEM; NEW-ZEALAND; LATITUDES; LAUDER; MODEL AB Using more than 1600 nighttime profiles obtained by the Jet Propulsion Laboratory differential absorption lidars located at Table Mountain Facility (TMF, 34.4 degrees N) and Mauna Loa Observatory (MLO, 19.5 degrees N) stratospheric ozone climatology is presented ill this paper. These two systems have been providing high-resolution vertical profiles of ozone number density between 15 and 50 km for several nights a week since 1988 (TMF) and 1993 (MLO). The climatology presented here is typical of early night ozone values at both sites and typical of a low solar activity period fur MLO. The observed seasonal and vertical structure of the ozone concentration at TMF is consistent with that typical of middle to subtropical latitudes. A clear annual cycle in opposite phases below and above the ozone concentration peak is observed. The observed winter maximum below the ozone peak is associated with a maximum day-to-day variability, typical of a dynamically driven lower stratosphere. The maximum concentration observed in summer above the ozone peak emphasizes the more dominant role of photochemistry. Unlike TMF, the ozone concentration observed at MLO tends to be higher during the summer months and lower during the winter months throughout the entire stratospheric ozone layer. Only a weak signature of the extratropical latitudes is observed near 19-20 km, with a secondary maximum in late winter. The only large variability observed at MLO is in the lowermost stratosphere, which could be associated with the natural variability of the tropical tropopause. C1 CALTECH, Jet Prop Lab, Table Mt Facil, Wrightwood, CA 92397 USA. RP Leblanc, T (reprint author), CALTECH, Jet Prop Lab, Table Mt Facil, POB 367, Wrightwood, CA 92397 USA. EM leblanc@tmf.jpl.nasa.gov NR 38 TC 19 Z9 19 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 16 PY 2000 VL 105 IS D11 BP 14613 EP 14623 DI 10.1029/2000JD900030 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 326LB UT WOS:000087736000021 ER PT J AU Newchurch, MJ Bishop, L Cunnold, D Flynn, LE Godin, S Frith, SH Hood, L Miller, AJ Oltmans, S Randel, W Reinsel, G Stolarski, R Wang, R Yang, ES Zawodny, JM AF Newchurch, MJ Bishop, L Cunnold, D Flynn, LE Godin, S Frith, SH Hood, L Miller, AJ Oltmans, S Randel, W Reinsel, G Stolarski, R Wang, R Yang, ES Zawodny, JM TI Upper-stratospheric ozone trends 1979-1998 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID VERTICAL-DISTRIBUTION; NIMBUS-7 SBUV; UMKEHR; PROFILES; AEROSOL; DEPENDENCE; ATMOSPHERE; CHEMISTRY; MODEL; SAGE AB Extensive analyses of ozone observations between 1978 and 1998 measured by Dobson Umkehr, Stratospheric Aerosol and Gas Experiment (SAGE)I and II, and Solar Backscattered Ultraviolet (SBUV) and (SBUV)/2 indicate continued significant ozone decline throughout the extratropical upper stratosphere from 30-45 km altitude. The maximum annual linear decline of -0.8+/-0.2 % yr(-1)(2 sigma) occurs at 40 km and is well described in terms of a linear decline modulated by the 11-year solar variation. The minimum decline of -0.1+/-0.1% yr(-1)(2 sigma) occurs at 25 km in midlatitudes, with remarkable symmetry between the Northern and Southern Hemispheres at 40 km altitude. Midlatitude upper-stratospheric zonal trends exhibit significant seasonal variation (+/-30% in the Northern Hemisphere, +/-40% in the Southern Hemisphere) with the most negative trends of -1.2% yr(-1) occurring in the winter. Significant seasonal trends of -0.7 to -0.9% yr(-1) occur at 40 km in the tropics between April and September. Subjecting the statistical models used to calculate the ozone trends to intercomparison tests on a variety of common data sets yields results that indicate the standard deviation between trends estimated by 10 different statistical models is less than 0.1% yr(-1) in the annual-mean trend for SAGE data and less than 0.2% yr(-1) in the most demanding conditions (seasons with irregular, sparse data) [World Meteorological Organization (WMO), 1998]. These consistent trend results between statistical models together with extensive consistency between the independent measurement-system trend observations by Dobson Umkehr, SAGE I and TI, and SBUV and SBUV/2 provide a high degree of confidence in the accuracy of the declining ozone amounts reported here. Additional details of ozone trend results from 1978 to 1996 (2 years shorter than reported here) along with lower-stratospheric and tropospheric ozone trends, extensive intercomparisons to assess relative instrument drifts, and retrieval algorithm details are given by WMO [1998]. C1 Univ Alabama, Dept Atmospher Sci, Huntsville, AL 35899 USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Allied Signal Corp, Buffalo, NY 14210 USA. Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. NOAA, Natl Environm Satellite Data & Informat Serv, Washington, DC 20233 USA. Univ Paris 06, Serv Aeron, F-75252 Paris, France. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. NOAA, Natl Weather Serv, Climate Predict Ctr, Washington, DC 20233 USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. Univ Wisconsin, Dept Stat, Madison, WI 53706 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Newchurch, MJ (reprint author), Univ Alabama, Dept Atmospher Sci, Huntsville, AL 35899 USA. EM mike@atmos.uah.edu; lane.bishop@alliedsignal.com; cunnold@eas.gatech.edu; lflynn@orbit.nesdis.noaa.gov; sophie.godin@aero.jussieu.fr; lon@lpl.arizona.edu; miller@upair.wwb.noaa.gov; soltmans@cmdl.noaa.gov; randel@ncar.ucar.edu; reinsel@stat.wisc.edu; stolarski@polska.gsfc.nasa.gov; yes@atmos.uah.edu RI Flynn, Lawrence/B-6321-2009; Stolarski, Richard/B-8499-2013; Randel, William/K-3267-2016 OI Flynn, Lawrence/0000-0001-6856-2614; Stolarski, Richard/0000-0001-8722-4012; Randel, William/0000-0002-5999-7162 NR 36 TC 35 Z9 35 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 16 PY 2000 VL 105 IS D11 BP 14625 EP 14636 DI 10.1029/2000JD900037 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 326LB UT WOS:000087736000022 ER PT J AU Rinsland, CP Goldman, A Connor, BJ Stephen, TM Jones, NB Wood, SW Murcray, FJ David, SJ Blatherwick, RD Zander, R Mahieu, E Demoulin, P AF Rinsland, CP Goldman, A Connor, BJ Stephen, TM Jones, NB Wood, SW Murcray, FJ David, SJ Blatherwick, RD Zander, R Mahieu, E Demoulin, P TI Correlation relationships of stratospheric molecular constituents from high spectral resolution, ground-based infrared solar absorption spectra SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID HALOGEN OCCULTATION EXPERIMENT; SPECTROSCOPIC MEASUREMENTS; VERTICAL-DISTRIBUTION; ATMOS MEASUREMENTS; CARBON-MONOXIDE; ERROR ANALYSIS; KITT PEAK; OZONE; CH4; TRANSPORT AB Comparisons of chemically active species with chemically inert tracers are useful to quantify transport and mixing and assess the accuracy of model predictions. We report measurements of chemically active species and chemically inert tracers in the stratosphere derived from the analysis of infrared solar absorption spectra recorded with a ground-based Fourier transform spectrometer operated typically at 0.005- to 0.01-cm(-1) spectral resolution. The measurements were recorded from Kitt Peak in southern Arizona (latitude 31.9 degrees N, 111.6 degrees W, 2.09 km altitude). Time series of N2O, CH4, O-3, and HNO3 vertical profiles have been retrieved from measurements in microwindows. From these results, correlations between N2O and CH4 stratospheric mixing ratios and between O-3 and HNO3 lower stratospheric mixing ratios have been derived. The measured correlations between N2O versus CH4 mixing ratios are compact and show little variability with respect to season in quantitative agreement with Atmospheric Trace Molecule Spectroscopy Experiment (ATMOS) spring and autumn measurements recorded near the same latitude. Lower stratospheric O-3 versus HNO3 mixing ratios measured during low to moderate aerosol loading time periods also show a compact relations though the HNO3/O-3 slope is a factor of 2 lower than obtained from November 1994 ATMOS measurements near the Same latitude. We also compare Kitt Peak and ATMOS N2O versus CH4 and O-3 versus HNO3 relations obtained by averaging the measurements over two broad stratospheric layers. This comparison avoids bias from the a priori profiles and the limited vertical resolution of the ground-based observations. C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. Univ Denver, Dept Phys, Denver, CO 80208 USA. NIWA Climate, Lauder 9182, New Zealand. Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium. RP Rinsland, CP (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, Mail Stop 401A, Hampton, VA 23681 USA. EM c.p.rinsland@larc.nasa.gov; goldman@acd.ucar.edu; connor@kea.lauder.cri.nz; tstephen@du.edu; jones@kea.lauder.cri.nz; s.wood@niwa.cri.nz; fmurcray@acd.ucar.edu; Shelle@dove.phys.du.edu; blathe@meeker.ucar.edu; zander@atmosfer.astro.ulg.ac.be; Emmanuel.Mahieu@ulg.ac.be; demoulin@astro.ulg.ac.be RI Jones, Nicholas/G-5575-2011; OI Jones, Nicholas/0000-0002-0111-2368; Mahieu, Emmanuel/0000-0002-5251-0286 NR 54 TC 10 Z9 10 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 16 PY 2000 VL 105 IS D11 BP 14637 EP 14652 DI 10.1029/2000JD900139 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 326LB UT WOS:000087736000023 ER PT J AU Kato, S Bergin, MH Ackerman, TP Charlock, TP Clothiaux, EE Ferrare, RA Halthore, RN Laulainen, N Mace, GG Michalsky, J Turner, DD AF Kato, S Bergin, MH Ackerman, TP Charlock, TP Clothiaux, EE Ferrare, RA Halthore, RN Laulainen, N Mace, GG Michalsky, J Turner, DD TI A comparison of the aerosol thickness derived from ground-based and airborne measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LOWER GREAT-PLAINS; LIGHT-SCATTERING; UNITED-STATES; INTEGRATING NEPHELOMETER; TROPOSPHERIC CHEMISTRY; OPTICAL-PROPERTIES; APPORTIONMENT; PROFILES; GROWTH AB The extinction optical thickness of particles obtained from scattering and absorption coefficients measured by an airborne integrating nephelometer and particle soot absorption photometer, respectively, is compared with the aerosol optical thickness derived from a ground-based multifilter rotating shadowband radiometer, a Sun photometer, and a Raman lidar for 9 days. These 9 days are selected from intensive operation periods of the Atmospheric Radiation Measurement in April 1997, September 1997, and August 1998 at the southern Great Plains. For April 1997 and September 1997 cases the difference between the extinction optical thickness of particles estimated from vertical profiles and the extinction optical thickness of aerosol derived from the multifilter rotating shadowband radiometer is not significant. For August 1998 cases when the boundary layer relative humidity is higher than April 1997 and September 1997 cases, the extinction optical thickness of particles is 0.03 to 0.07 less than the extinction optical thickness of aerosol. The difference corresponds to 25% to 31% of the extinction optical thickness of aerosol. Based on these comparisons, the upper and lower limits of the single-scattering albedo of particles present in the lower part of troposphere are 0.97 and 0.84, respectively. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Penn State Univ, Dept Meteorol, University Pk, PA 16802 USA. Brookhaven Natl Lab, Dept Appl Sci, Upton, NY 11973 USA. Univ Utah, Dept Meteorol, Salt Lake City, UT 84112 USA. SUNY Albany, Atmospher Sci Res Ctr, Albany, NY 12205 USA. Pacific NW Lab, Richland, WA 99352 USA. Georgia Inst Technol, Sch Civil & Environm Engn, Atlanta, GA 30332 USA. Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. Hampton Univ, Ctr Atmospher Sci, Hampton, VA 23668 USA. RP Kato, S (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. EM s.katol@larc.nasa.gov NR 37 TC 30 Z9 30 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 16 PY 2000 VL 105 IS D11 BP 14701 EP 14717 DI 10.1029/2000JD900013 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 326LB UT WOS:000087736000027 ER PT J AU Yue, GK AF Yue, GK TI Retrieval of aerosol size distributions and integral properties from simulated extinction measurements at SAGE III wavelengths by the linear minimizing error method SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID HALOGEN OCCULTATION EXPERIMENT; STRATOSPHERIC AEROSOL; PINATUBO AEROSOL; POAM-II; SATELLITE; SPECTRA; OZONE AB The retrieval or aerosol size distribution and integral properties from simulated aerosol extinction measurements of the new satellite instrument, the Stratospheric Aerosol and Gas Experiment (SAGE) III, is investigated The retrieval method used in this study is the newly proposed linear minimizing error (LME) method, This approach assumes that the aerosol size distribution can be approximated by a histogram of number density as a function of particle size. The retrieved number density in each hin and the integral properties, including surface area and volume densities, are expressed as a linear combination of the SAGE III aerosol extinction coefficients at eight or fewer wavelengths. The coefficients in the weighted linear combination are obtained by minimizing the average of retrieval errors oa cr a set of testing size distributions. The choice of aerosol channels for retrieval was first determined by comparing the average composite errors of the integral properties retrieved from different combinations of aerosol extinctions, The accuracy of the proposed method was studied by comparing the actual and retrieved properties for six aerosol size distributions, Results of this investigation indicate that unimodal, as well as bimodal, lognormal size distributions call be retrieved with reasonable accuracy, When all eight aerosol extinctions are available for retrieval, the average composite errors, which include systematic errors and errors due to measurement uncertainties for the retrieval of surface area and volume densities, are 9.4+/-4.3 and 4.7+/-2.0%, respectively. The retrieved aerosol integral properties are more accurate than those retrieved from SAGE II. However, ii is not advantageous to use all eight SAGE III wavelengths for retrieval. The proper choice of aerosol extinctions for retrieval is elucidated. The derived formulas listed in this paper can be easily used by investigators to retrieve aerosol integral properties and estimate the retrieval errors from SAGE III aerosol extinctions at different altitudes for a variety of purposes. The application of the LME method to instrumental design is discussed. C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Yue, GK (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, 100 NASA Rd, Hampton, VA 23681 USA. EM g.k.yue@larc.nasa.gov NR 22 TC 6 Z9 6 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 16 PY 2000 VL 105 IS D11 BP 14719 EP 14736 DI 10.1029/2000JD900165 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 326LB UT WOS:000087736000028 ER PT J AU Oreopoulos, L Marshak, A Cahalan, RF Wen, GY AF Oreopoulos, L Marshak, A Cahalan, RF Wen, GY TI Cloud three-dimensional effects evidenced in Landsat spatial power spectra and autocorrelation functions SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID INDEPENDENT PIXEL APPROXIMATION; MARINE STRATOCUMULUS; RADIATIVE-TRANSFER; ABSORPTION AB An analysis of nadir reflectivity spatial Fourier power spectra and autocorrelation functions for solar wavelengths and cloudy conditions is presented. The data come from Landsat thematic mapper. (TM) observations, while Monte Carlo (MC) simulations are used to aid the interpretation of the observations and to examine sensitivity to various factors. We show that shortwave radiative processes produce consistent signatures in power spectra and autocorrelation functions. Power spectra take a variety of shapes not shown or explained in previous observational studies. We demonstrate that TM spectra call potentially be affected by radiative "roughening" at intermediate, scales (similar to 1-5 km) and radiative "smoothing" at small scales (<1 km). These processes are wavelength-dependent, with systematic differences between conservative (for cloud droplets) TM band 4 (similar to 0.8 mu m) and absorbing band 7 (similar to 2.2 mu m). Band 7 exhibits moro roughening and less smoothing than band 4 and faster decrease in autocorrelation. Roughening is more prevalent at large solar zenith angles due to optical and/or geometrical side illumination and shadowing. MC spectra illustrate that scale invariant optical depth fields can produce complex power spectra that take a variety of shapes under different conditions. Radiative roughening increases with decreasing single scattering albedo and increasing solar zenith angle (as in the observations). For low solar zenith angles, there is a clear shift in the radiative smoothing scale to smaller values as droplet absorption increases. Power spectra also show stronger decorrelations between optical depth and reflectivity when cloud top variations are more pronounced. Finally, it is shown that power spectral analysis is a useful tool for evaluating the skill of novel optical depth retrieval techniques in removing three-dimensional radiative effects. New techniques using inverse nonlocal independent pixel approximation and normalized difference of nadir reflectivity yield optical depth fields which better match the scale-by-scale variability of the true optical depth field. C1 NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. RP Oreopoulos, L (reprint author), NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Code 913, Greenbelt, MD 20771 USA. EM lazaros@climate.gsfc.nasa.gov; marshak@climate.gsfc.nasa.gov; cahalan@climate.gsfc.nasa.gov; wen@climate.gsfc.nasa.gov RI Oreopoulos, Lazaros/E-5868-2012; Cahalan, Robert/E-3462-2012; Marshak, Alexander/D-5671-2012 OI Oreopoulos, Lazaros/0000-0001-6061-6905; Cahalan, Robert/0000-0001-9724-1270; NR 21 TC 27 Z9 27 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 16 PY 2000 VL 105 IS D11 BP 14777 EP 14788 DI 10.1029/2000JD900153 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 326LB UT WOS:000087736000032 ER PT J AU Collins, WD Bucholtz, A Flatau, P Lubin, D Valero, FPJ Weaver, CP Pilewski, P AF Collins, WD Bucholtz, A Flatau, P Lubin, D Valero, FPJ Weaver, CP Pilewski, P TI Determination of surface heating by convective cloud systems in the central equatorial Pacific from surface and satellite measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RADIATION BUDGET EXPERIMENT; WATER-VAPOR; LONGWAVE RADIATION; INFRARED WINDOW; WESTERN PACIFIC; EL-NINO; FLUXES; OCEAN; MODEL; ERBE AB The heating of the ocean surface by longwave radiation from convective clouds has been estimated using measurements from the Central Equatorial Pacific Experiment (CEPEX). The ratio of the surface longwave cloud forcing to the cloud radiative forcing on the total atmospheric column is parameterized by the f factor. The f factor is a measure of the partitioning of the cloud radiative effect between the surface and the troposphere. Estimates of the f factor have been obtained by combining simultaneous observations from ship, aircraft, and satellite instruments. The cloud forcing near the ocean surface is determined from radiometers on board the National Oceanic and Atmospheric Administration P-3 aircraft and the R/V John Vickers. The longwave cloud forcing at the top of the atmosphere has been estimated from data obtained from the Japanese Geostationary Meteorological Satellite GMS 4. A new method for estimating longwave fluxes from satellite narrowband radiances is described. The method is based upon calibrating the satellite radiances against narrowband and broadband infrared measurements from the high-altitude NASA ER-2 aircraft. The average value of f derived from the surface and satellite observations of convective clouds is 0.15 +/- 0.02. The area-mean top-of-atmosphere longwave forcing by convective clouds in the region 10 degrees S-10 degrees N, 160 degrees E-160 degrees W is 40 W/m(2) during CEPEX. Those results indicate that the surface longwave forcing by convective clouds was approximately 5 W/m(2) in the central equatorial Pacific and that this forcing is the smallest radiative component of the surface energy budget. C1 Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Univ Calif San Diego, Scripps Inst Oceanog, Ctr Atmospher Sci, La Jolla, CA 92093 USA. Univ Calif San Diego, Scripps Inst Oceanog, Ctr Clouds Chem & Climate, La Jolla, CA 92093 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Rutgers State Univ, Dept Environm Sci, Ctr Environm Predict, New Brunswick, NJ 08901 USA. Univ Calif San Diego, Scripps Inst Oceanog, Atmospher Res Lab, La Jolla, CA 92093 USA. RP Collins, WD (reprint author), Natl Ctr Atmospher Res, POB 3000, Boulder, CO 80307 USA. EM wcollins@ucar.edu RI Weaver, Christopher/G-3714-2010; Collins, William/J-3147-2014; Flatau, Piotr/E-2219-2011 OI Weaver, Christopher/0000-0003-4016-5451; Collins, William/0000-0002-4463-9848; NR 41 TC 4 Z9 4 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 16 PY 2000 VL 105 IS D11 BP 14807 EP 14821 DI 10.1029/2000JD900109 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 326LB UT WOS:000087736000034 ER PT J AU Russell, GL Miller, JR Rind, D Ruedy, RA Schmidt, GA Sheth, S AF Russell, GL Miller, JR Rind, D Ruedy, RA Schmidt, GA Sheth, S TI Comparison of model and observed regional temperature changes during the past 40 years SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CLIMATE-CHANGE; SURFACE AB Results are presented fur six simulations of the Goddard Institute for Space Studies (GISS) global atmosphere-ocean model for the years 1950-2099. There are two control simulations with constant 1950 atmospheric composition from different initial states, two greenhouse gas (GHG) experiments with observed greenhouse gases Lip to 1990 and compounded 0.5% CO2 annual increases thereafter, and two greenhouse gas plus sulfate (GHG + SO4) experiments with the same varying greenhouse gases plus varying tropospheric sulfate aerosols. Surface air temperature trends in the two GHG experiments (with tl-le control simulations climate drift subtracted out) are compared between themselves and with changes in the observed temperature record between 1960 and 1998. All comparisons show high positive spatial correlation in the Northern Hemisphere except in summer when the greenhouse signal is weakest. The GHG + SO4 experiments show weaker correlations. In the Southern Hemisphere, correlations between any experiments ol observations are either weak or negative, in part because the model's interannual variability of southern sea ice cover is unrealistic. The model results imply that temperature changes due to forcing by increased greenhouse gases have risen above the level of regional interannual temperature variability in the Northern Hemisphere over the past 40 years. This period is thus an important test of the reliability of coupled climate models. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Russell, GL (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM grussell@giss.nasa.gov RI Schmidt, Gavin/D-4427-2012 OI Schmidt, Gavin/0000-0002-2258-0486 NR 23 TC 68 Z9 70 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 16 PY 2000 VL 105 IS D11 BP 14891 EP 14898 DI 10.1029/2000JD900156 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 326LB UT WOS:000087736000039 ER PT J AU Moghaddam, M Saatchi, S Cuenca, RH AF Moghaddam, M Saatchi, S Cuenca, RH TI Estimating subcanopy soil moisture with radar SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MICROWAVE DIELECTRIC SPECTRUM; WATER BALANCE; BOREAL FOREST; MODEL; VEGETATION; SCATTERING; CONSTANT AB The subcanopy soil moisture of a boreal old jack pine forest stand is estimated using polarimetric L and P band ail borne synthetic aperture radar (AIRSAR) data. Model simulations have shown that for this stand the principal scattering mechanism responsible for radar backscatter is the double-bounce mechanism between the tree trunks and the ground. The data to be used here were acquired during five flights from June to September 1994 as part of the Boreal Ecosystem-Atmosphere Study (BOREAS) project. The dielectric constants, or equivalently moisture contents, of the trunks and soil can change significantly during this period, To estimate these dynamic unknowns, parametric models of radar backscatter for the double-bounce mechanism are developed using a series of simulations of a numerical forest scattering model. A nonlinear optimization procedure is used to estimate the dielectric constants. Ground measurements of soil and trunk moisture content are used to validate the results. The trunk moisture content measurements are used to gain confidence that the respective estimation results are accurate enough not to corrupt the soil moisture estimation, which is the main focus of this paper. After conversion of the trunk moisture measurements to dielectric constants it is found that the estimated values are within 14% of the measurements. Owing to possible calibration uncertainties in the soil moisture measurements on the ground as well as in AIRSAR data, the variations rather than the absolute levels of the estimated soil moisture are considered. The results indicate: that the estimated variations closely track the measurements, The worst case average estimated change differs by <1% volumetric soil moisture from that measured on the ground. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Oregon State Univ, Dept Bioresource Engn, Corvallis, OR 97331 USA. RP Moghaddam, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 300-227, Pasadena, CA 91109 USA. EM mahta.moghaddam@jpl.nasa.gov; cuenca@engr.orst.edu NR 21 TC 44 Z9 44 U1 3 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 16 PY 2000 VL 105 IS D11 BP 14899 EP 14911 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 326LB UT WOS:000087736000040 ER PT J AU Lazzaro, D Michtchenko, T Carvano, JM Binzel, RP Bus, SJ Burbine, TH Mothe-Diniz, T Florczak, M Angeli, CA Harris, AW AF Lazzaro, D Michtchenko, T Carvano, JM Binzel, RP Bus, SJ Burbine, TH Mothe-Diniz, T Florczak, M Angeli, CA Harris, AW TI Discovery of a basaltic asteroid in the outer main belt SO SCIENCE LA English DT Article ID SPACE-TELESCOPE IMAGES; PARENT BODY; RESONANCES; VESTA; METEORITES; ELEMENTS; EUCRITE; 4-VESTA; MOTION AB Visible and near-infrared spectroscopic observations of the asteroid 1459 Magnya indicate that it:has a basaltic surface. Magnya is at 3.15 astronomical units (AU) from the sun and has no known dynamical link to any family, to any nearby Large asteroid, or to asteroid 4 Vesta at 2.36 AU, which is the only other known large basaltic asteroid. We show that the region of the belt around Magnya is densely filled by mean-motion resonances, generating slow orbital diffusion processes and providing a potential mechanism for removing other basaltic fragments that may have been created on the same:parent body as Magnya. Magnya may represent a rare surviving fragment from a Larger, differentiated planetesimal that was disrupted long ago. C1 Observ Nacl, Dept Astrofis, BR-20921400 Rio De Janeiro, Brazil. Univ Sao Paulo, Inst Astron & Geofis, BR-04301904 Sao Paulo, Brazil. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. Ctr Fed Educ Tecnol Parana, Dept Fis, BR-80230901 Curitiba, Parana, Brazil. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lazzaro, D (reprint author), Observ Nacl, Dept Astrofis, Rua Gal Jose Cristino 77, BR-20921400 Rio De Janeiro, Brazil. RI Mothe-Diniz, Thais/B-8987-2011; Lazzaro, Daniela/I-3509-2012; Ferreira Carvano, Jorge/I-4039-2016 OI Lazzaro, Daniela/0000-0002-4470-6043; Ferreira Carvano, Jorge/0000-0003-0670-639X NR 25 TC 72 Z9 72 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 JUN 16 PY 2000 VL 288 IS 5473 BP 2033 EP 2035 DI 10.1126/science.288.5473.2033 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 325QC UT WOS:000087687000047 ER PT J AU Nedoluha, GE Bevilacqua, RM Hoppel, KW Daehler, M Shettle, EP Hornstein, JH Fromm, MD Lumpe, JD Rosenfield, JE AF Nedoluha, GE Bevilacqua, RM Hoppel, KW Daehler, M Shettle, EP Hornstein, JH Fromm, MD Lumpe, JD Rosenfield, JE TI POAM III measurements of dehydration in the Antarctic lower stratosphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID POLAR VORTEX; DESCENT; WINTER; H2O AB We present measurements of stratospheric water vapor and aerosols in the Antarctic from the FOAM III instrument during the period April through December 1998. The measured variations in water vapor enable us to study both descent in the vortex and the effect of dehydration that occurs in the lower stratosphere below similar to 23 km when the temperature drops below the frost point in July. There is a temporal correlation between the dehydration that occurs in July and an increase in high aerosol optical depth events in the lower stratosphere, suggesting that these events are due to the presence of ice PSC's. When temperatures warm up there is some rehydration at the highest altitudes of the dehydrated region (similar to 20-23 km), probably resulting from descent within the vortex. At similar to 12 km rehydration is probably the result of mixing in of air from outside the vortex. The temperature increase in October produces little rehydration at 17 km and no clear rehydration at 14 km, suggesting that the water has precipitated out of these layers. C1 USN, Res Lab, Washington, DC 20375 USA. Computat Phys Inc, Fairfax, VA 22031 USA. NASA, Goddard Space Flight Ctr, Gen Sci Corp, Greenbelt, MD 20771 USA. RP Nedoluha, GE (reprint author), USN, Res Lab, Code 7227, Washington, DC 20375 USA. RI Fromm, Michael/F-4639-2010 NR 15 TC 39 Z9 39 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 JUN 15 PY 2000 VL 27 IS 12 BP 1683 EP 1686 DI 10.1029/1999GL011087 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 325CD UT WOS:000087658000001 ER PT J AU Marshak, A Knyazikhin, Y Davis, AB Wiscombe, WJ Pilewskie, P AF Marshak, A Knyazikhin, Y Davis, AB Wiscombe, WJ Pilewskie, P TI Cloud-vegetation interaction: Use of Normalized Difference Cloud Index for estimation of cloud optical thickness SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID RETRIEVAL AB A new technique to retrieve cloud optical depth for broken clouds above green vegetation using ground-based zenith radiance measurements is developed. By analogy with the Normalized Difference Vegetation Index (NDVI), the Normalized Difference Cloud Index(NDCI) is defined as a ratio between the difference and the sum of two zenith radiances measured for two narrow spectral bands in the visible and near-IR regions. The very different spectral behavior of cloud liquid water drops and green vegetation is the key physics behind the NDCI. It provides extra tools to remove the radiative effects of the 3D cloud structure. Numerical calculations based on fractal clouds and real measurements of NDCI and cloud liquid water path confirm the improvements. C1 NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. Boston Univ, Dept Geog, Boston, MA 02215 USA. Univ Calif Los Alamos Natl Lab, Space & Remote Sensing Sci NIS 2, Los Alamos, NM 87545 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. RP Marshak, A (reprint author), NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, MC 913, Greenbelt, MD 20771 USA. RI Wiscombe, Warren/D-4665-2012; Marshak, Alexander/D-5671-2012 OI Wiscombe, Warren/0000-0001-6844-9849; NR 20 TC 40 Z9 52 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 JUN 15 PY 2000 VL 27 IS 12 BP 1695 EP 1698 DI 10.1029/1999GL010993 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 325CD UT WOS:000087658000004 ER PT J AU Williams, CR Kruger, A Gage, KS Tokay, A Cifelli, R Krajewski, WF Kummerow, C AF Williams, CR Kruger, A Gage, KS Tokay, A Cifelli, R Krajewski, WF Kummerow, C TI Comparison of simultaneous rain drop size distributions estimated from two surface disdrometers and a UHF profiles SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SPECTRA; RADAR AB In support of the NASA Tropical Rainfall Measuring Mission (TRMM) Ground Validation Program, a suite of surface instruments and vertical pointing Doppler radar profilers were deployed in central Florida to quantify the number and size of the rain drops reaching the surface. Analyzing 276 minutes of simultaneous observations from two surface disdrometers and one profiler revealed good agreement among the instruments for drop sizes > 1.5 mm diameter but poor agreement for smaller drop sizes. The magnitude of the difference in small drop estimation was proportional to the reflectivity (and rainrate). At reflectivities greater than 40 dBZ, the differences in the estimation of the number of small drops yielded differences in estimates of mass-weighted diameter of > 13% and of rainrate > 25%. The combined effect of these uncertainties impact the interpretation of the precipitation processes and the development and validation of space-based precipitation retrieval algorithms. C1 NOAA, Aeron Lab, Boulder, CO 80303 USA. Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80309 USA. Univ Iowa, Iowa Inst Hydraul Res, Iowa City, IA 52242 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. RP Williams, CR (reprint author), NOAA, Aeron Lab, 325 Broadway,MS R-AL3, Boulder, CO 80303 USA. RI Williams, Christopher/A-2723-2015 OI Williams, Christopher/0000-0001-9394-8850 NR 17 TC 38 Z9 38 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 15 PY 2000 VL 27 IS 12 BP 1763 EP 1766 DI 10.1029/1999GL011100 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 325CD UT WOS:000087658000021 ER PT J AU Feldman, PD Strobel, DF Moos, HW Retherford, KD Wolven, BC McGrath, MA Roesler, FL Woodward, RC Oliversen, RJ Ballester, GE AF Feldman, PD Strobel, DF Moos, HW Retherford, KD Wolven, BC McGrath, MA Roesler, FL Woodward, RC Oliversen, RJ Ballester, GE TI Lyman-alpha imaging of the SO2 distribution on Io SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HUBBLE-SPACE-TELESCOPE; ATMOSPHERE AB Imaging spectroscopy of Io in the ultraviolet (1160 - 1720 Angstrom) was carried out with the Space Telescope Imaging Spectrograph on HST on three dates in October 1997 and August 1998. Among the initial results was the observation of concentrated regions of H I Lyman-a flux near the poles of Io that exhibited a morphology and temporal variability different from those of,the atomic oxygen and sulfur emission regions seen near the equatorial limbs. We examine the suggestion that the primary source of Lyman-a: emission is surface reflected solar radiation that penetrates the thin polar atmosphere, but is strongly absorbed by the thicker SO2 atmosphere near Io's equator. Spectral and spatial analyses lead to derived SO2 column densities that are in good agreement with those derived from earlier HST observations of Io's albedo in the 2000 - 2300 Angstrom wavelength range. The Lyman-a: images clearly illustrate features of Io's atmosphere that have been deduced from previous observations and theoretical modeling: a non-uniformity with respect to the sub-solar point dominated by a freezing out of the SO2 near the poles and variation with both longitude and time due to the variability of the sources of the atmospheric gas. Lyman-cr imaging is demonstrated to be an extremely powerful and direct way to globally map the dynamic atmosphere of Io. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Johns Hopkins Univ, Dept Earth & Planetary Sci, Baltimore, MD 21218 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Wisconsin, Dept Phys, Madison, WI 53706 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. RP Feldman, PD (reprint author), Johns Hopkins Univ, Dept Phys & Astron, Charles & 34th St, Baltimore, MD 21218 USA. NR 14 TC 33 Z9 33 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 JUN 15 PY 2000 VL 27 IS 12 BP 1787 EP 1790 DI 10.1029/1999GL011067 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 325CD UT WOS:000087658000027 ER PT J AU Descloitres, J Roy, DP Couvert, P AF Descloitres, J Roy, DP Couvert, P TI Evidence and implications of solar eclipses in short wavelength global remotely sensed data SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID AVHRR DATA; VEGETATION; INDEX; LAND; NDVI AB Solar eclipses evident in short wavelength data sensed by polar orbiting Sun-synchronous wide field of view instruments such as SeaWiFS and POLDER are illustrated, and some implications for global dataset production are considered. C1 Univ Maryland, NASA, Goddard Space Flight Ctr, Dept Geog, Greenbelt, MD 20771 USA. Ctr Etud Saclay, Lab Sci Climat & Environm, F-91191 Gif Sur Yvette, France. RP Descloitres, J (reprint author), Univ Maryland, NASA, Goddard Space Flight Ctr, Dept Geog, Code 922, Greenbelt, MD 20771 USA. NR 9 TC 0 Z9 0 U1 1 U2 1 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 JUN 15 PY 2000 VL 21 IS 9 BP 1961 EP 1967 DI 10.1080/014311600209887 PG 7 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 316PA UT WOS:000087175100016 ER PT J AU Panda, S Economou, DJ Meyyappan, M AF Panda, S Economou, DJ Meyyappan, M TI Effect of metastable oxygen molecules in high density power-modulated oxygen discharges SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID CYCLOTRON-RESONANCE PLASMA; CHEMICAL VAPOR-DEPOSITION; AVERAGED GLOBAL MODEL; PULSED-PLASMA; RF DISCHARGE; DISSOCIATIVE ATTACHMENT; FREQUENCY PLASMA; NEGATIVE-IONS; REACTOR; EXCITATION AB A spatially averaged (well mixed) reactor model was used to simulate a power-modulated (pulsed) high density oxygen discharge. Chemistry involving the high energy oxygen metastable molecules O-2(M)(A (3)Sigma(u)(+)+C (3)Delta(u)+c (1)Sigma(u)(-)) was included in the simulation. This chemistry was necessary to capture the experimentally observed increase in the O- negative ion density in the afterglow of the pulsed discharge. As the electron temperature drops in the afterglow, the rate coefficient of electron attachment with O-2(M) increases several fold. The wall recombination probability of oxygen atoms affected the O- density drastically. For the conditions studied, the maximum O- density in the afterglow increased with pressure, decreased with power, and showed a maximum with pulse period. The time in the afterglow at which the peak O- density occurred decreased with pressure and power, and was independent of the pulse period. Knowing the temporal evolution of O- in the afterglow may be important for applications requiring extraction of negative ions out of the discharge. (C) 2000 American Institute of Physics. [S0021-8979(00)07512-5]. C1 Univ Houston, Dept Chem Engn, Plasma Proc Lab, Houston, TX 77204 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Panda, S (reprint author), Univ Houston, Dept Chem Engn, Plasma Proc Lab, Houston, TX 77204 USA. NR 65 TC 52 Z9 53 U1 1 U2 9 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 JUN 15 PY 2000 VL 87 IS 12 BP 8323 EP 8333 AR PII [S0021-8979(00)07512-5] DI 10.1063/1.373544 PG 11 WC Physics, Applied SC Physics GA 319MU UT WOS:000087346400012 ER PT J AU Gurusinghe, KKMN Premaratne, K Andersson, TG Bandara, SV AF Gurusinghe, KKMN Premaratne, K Andersson, TG Bandara, SV TI Current-voltage analysis of a tunneling emitter-undoped single quantum well infrared photodetector SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID DETECTOR AB The electrical behavior of a tunneling emitter-undoped single quantum well infrared photodetector structure was studied theoretically and compared with experimental results. In order to understand the current generation and transport mechanisms, and to estimate the quantum well electron density variation and the applied bias voltage distribution, the current-voltage dependence was modeled and numerically analyzed using the known parameters of the structure. In this study, resonance and nonresonance currents from the emitter contact and the field emission and the thermionic emission currents from the quantum well, were taken into account. A simple analytical expression for resonance tunneling current was derived using the transfer Hamiltonian description of resonance tunneling. Effective mass variation of different materials in the heterostructure was considered. The model was developed by balancing the current across the quantum well layer, where the carrier density reached to a steady value. Resulting calculation accurately predicted the resonance behavior of the dark current through the device as bias voltage changed. The carrier density variation in the quantum well region and barrier band bending, as a function of bias voltage, were also calculated. (C) 2000 American Institute of Physics. [S0021-8979(00)03212-6]. C1 Univ Peradeniya, Dept Phys, Peradeniya, Sri Lanka. Chalmers Univ Technol, Dept Phys & Engn Phys, Div Microelect & Nanosci, S-41296 Gothenburg, Sweden. Univ Gothenburg, Gothenburg, Sweden. CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. RP Gurusinghe, KKMN (reprint author), Univ Peradeniya, Dept Phys, Peradeniya, Sri Lanka. NR 12 TC 2 Z9 2 U1 1 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 JUN 15 PY 2000 VL 87 IS 12 BP 8575 EP 8579 DI 10.1063/1.373581 PG 5 WC Physics, Applied SC Physics GA 319MU UT WOS:000087346400049 ER PT J AU Higurashi, A Nakajima, T Holben, BN Smirnov, A Frouin, R Chatenet, B AF Higurashi, A Nakajima, T Holben, BN Smirnov, A Frouin, R Chatenet, B TI A study of global aerosol optical climatology with two-channel AVHRR remote sensing SO JOURNAL OF CLIMATE LA English DT Article ID GREENHOUSE GASES; SIZE DISTRIBUTIONS; SULFATE AEROSOLS; MINERAL AEROSOLS; DUST; CALIBRATION; ALGORITHM; SCATTERING; RETRIEVAL; THICKNESS AB Global distributions of the aerosol optical thickness and Angstrom exponent are estimated from National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer channel-1 and -2 radiances for four months in 1990. Global distributions of those Angstrom parameters are consistent with present knowledge on the distributions of desert-derived, biomass-burning, and anthropogenic pollutant aerosols obtained by groundbased and aircraft measurements. Especially, it is found that thin anthropogenic aerosols can be identified with large Angstrom exponent values around the east coast of North America, Europe, and eastern Asia. Satellite-retrieved values of Angstrom parameters are further compared with measured spectral optical thickness obtained by the National Aeronautics and Space Administration Aerosol Robotic Network sky radiometer network. C1 NIES, Div Atmospher Environm, Tsukuba, Ibaraki 3050053, Japan. Univ Tokyo, Ctr Climate Syst Res, Tokyo, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA. Univ Paris 07, Lab Interuniv Syst Atmospher, Paris, France. Univ Paris 12, UMR CNRS, Paris, France. RP Higurashi, A (reprint author), NIES, Div Atmospher Environm, 16-2 Onogawa, Tsukuba, Ibaraki 3050053, Japan. RI Smirnov, Alexander/C-2121-2009; Nakajima, Teruyuki/H-2370-2013 OI Smirnov, Alexander/0000-0002-8208-1304; Nakajima, Teruyuki/0000-0002-9042-504X NR 42 TC 74 Z9 75 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD JUN 15 PY 2000 VL 13 IS 12 BP 2011 EP 2027 DI 10.1175/1520-0442(2000)013<2011:ASOGAO>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 324PU UT WOS:000087631200003 ER PT J AU Chu, PC Veneziano, JM Fan, CW Carron, MJ Liu, WT AF Chu, PC Veneziano, JM Fan, CW Carron, MJ Liu, WT TI Response of the South China Sea to Tropical Cyclone Ernie 1996 SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID OCEAN CURRENT RESPONSE; FREE-SURFACE; HURRICANE GILBERT; MOVING STORM; MIXED-LAYER; VARIABILITIES; CIRCULATION; DYNAMICS; MODELS AB A moving tropical cyclone is an intense localized source of surface wind stress and wind stress curl that produces a significant response in the ocean environment, especially in the ocean thermal structure, the upper ocean currents, and the sea surface elevation. Such a response has been well identified in the open-ocean region, but not in the coastal ocean region. In this study we use the Princeton Ocean Model with 20 km horizontal resolution and 23 sigma levels conforming to a realistic bottom topography to identify the response of the South China Sea to Tropical Cyclone Ernie 1996, Results show strong similarities in the responses between open ocean and coastal regions, including near-surface strong asymmetric response such as divergent currents with near-inertial oscillations, significant sea surface temperature cooling, blase to the right of the storm track, sea surface depressions in the wake of the storm, and subsurface intense upwelling and cooling at the base of the mixed layer to the right of the storm track. The unique features of the SCS response to Ernie are also discussed. C1 USN, Postgrad Sch, Dept Oceanog, Monterey, CA 93943 USA. USN, Oceanog Off, Stennis Space Ctr, MS 39529 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chu, PC (reprint author), USN, Postgrad Sch, Dept Oceanog, Monterey, CA 93943 USA. NR 39 TC 41 Z9 44 U1 2 U2 6 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 JUN 15 PY 2000 VL 105 IS C6 BP 13991 EP 14009 DI 10.1029/2000JC900035 PG 19 WC Oceanography SC Oceanography GA 324NB UT WOS:000087627300005 ER PT J AU Hirose, N Ostrovskii, AG AF Hirose, N Ostrovskii, AG TI Quasi-biennial variability in the Japan Sea SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID TROPICAL PACIFIC-OCEAN; SHALLOW-WATER MODEL; WIND-DRIVEN; ASSIMILATION AB The TOPEX/Poseidon (T/P) altimetry reveals quasi-biennial (QB) variability in the southern Japan Sea. Sea surface height anomalies of a biennial nature are most energetic in the Yamato Basin, the southeastern most part of the Japan Sea, where they can be as large as 20 cm and extend for 100-200 km. On the basis of the in situ measurements of Maizuru Marine Observatory, the 2-3 year variations are associated with thermohaline anomalies in the upper 300 m layer. The local QB oscillation is studied with a reduced gravity model of the Japan Sea. The model is forced by European Centre for Medium-Range Weather Forecasting daily wind and seasonal inflows/outflows through the three major straits of the sea. The model sensitivity experiments suggest that the QB variability can be associated with the sea's response to wind forcing of particular years, more specifically, 1992 and 1996, and to some extent, 1994. An approximate Kalman filter is employed for assimilation of the TIP altimeter data into the reduced gravity model. It filters out observational noise and intraseasonal sea level variability and allows the model to dynamically interpolate T/P observations. The results of the assimilation indicate that the QB anomalies are strongest at 37.5 degrees N, 134.5 degrees E and propagate west-northwest with a speed of similar to 0.01 m s(-1), contributing to variations of the Tsushima Warm Current. C1 Japan Marine Sci & Technol Ctr, Frontier Observat Res Syst Global Change, Minato Ku, Tokyo 105, Japan. Kyushu Univ, Interdisciplinary Grad Sch Engn Sci, Kasuga, Fukuoka 816, Japan. RP Hirose, N (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 300-323, Pasadena, CA 91109 USA. EM nick@pacific.jpl.nasa.gov RI Ostrovskii, Alexander/E-4315-2014; OI Ostrovskii, Alexander/0000-0002-5906-0361; Hirose, Naoki/0000-0001-6234-8676 NR 29 TC 16 Z9 20 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-OCEANS JI J. Geophys. Res.-Oceans PD JUN 15 PY 2000 VL 105 IS C6 BP 14011 EP 14027 DI 10.1029/2000JC900046 PG 17 WC Oceanography SC Oceanography GA 324NB UT WOS:000087627300006 ER PT J AU McFarquhar, GM Heymsfield, AJ Spinhirne, J Hart, B AF McFarquhar, GM Heymsfield, AJ Spinhirne, J Hart, B TI Thin and subvisual tropopause tropical cirrus: Observations and radiative impacts SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID MARSHALL ISLANDS; WARM POOL; CLOUDS; KWAJALEIN; CEPEX AB In situ microphysical, remote sensing, and satellite observations of thin and subvisible cirrus have been used to establish their frequency of occurrence, determine their mean optical depths and radiative forcings, and to analyze their association with deep convection. A spatially thin layer of cirrus, with both base and top above 15 km, was observed in the central Pacific Tropics 29% of the time, with a mean thickness of 0.47 km. using a nadir-pointing Nd:YAG lidar operating at 1.064 mu m during the Central Equatorial Pacific Experiment (CEPEX). In situ microphysical data collected in the mid-1970s acid mid-1980s by a WB-57 and Learjet near Kwajalein, Marshall islands, are revisited to determine typical ice crystal sizes and shapes that occur in this cloud type. Three observed vertical profiles, obtained from ascents/descents through cloud, are used with a delta-four-stream radiative transfer model to calculate observed hearing rates of up to 1.0 K day(-1), principally in the infrared, and cloud radiative forcings of up to 1.3 W m(-2). These calculations are extended using remotely sensed optical depths acquired with the airborne lidar on four days during CEPEX; the average tau estimated was 0.01, and the corresponding heating rates and cloud radiative forcings were 1.66 K day(-1) and 1.6 W m(-2), respectively. Using a visibility threshold fur tau of 0.03, this suggests that the majority of the thin cirrus observed are subvisible. The calculated radiative effects depend principally on the observed optical thickness of the cloud layers. Altitude-dependent average extinction coefficients between 0.001 and 0.004 km(-1) were calculated from the limb-viewing Stratospheric Aerosol and Gas Experiment (SAGE) II satellite, confirming that the lidar estimated tau is representative fur the Tropics. A comparison of the SAGE II observed occurrence times with cloud properties estimated from collocated International Satellite Cloud and Climatology Project retrievals for the closest time shows that 28% of the subvisible cirrus occurred within the same 2.5 degrees by 2.5 degrees grid box as deep convection. Although the effect of subvisible cirrus on the radiative budget of the Tropics is not as large as for other ice clouds, their effects are not negligible and their other impacts, such as enhancing upper-tropospheric vertical motions and the lower-stratospheric water vapor, should not be ignored. C1 Natl Ctr Atmospher Res, MMM, Boulder, CO 80307 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP McFarquhar, GM (reprint author), Natl Ctr Atmospher Res, MMM, POB 3000, Boulder, CO 80307 USA. RI Heymsfield, Andrew/E-7340-2011; OI McFarquhar, Greg/0000-0003-0950-0135 NR 36 TC 164 Z9 165 U1 2 U2 23 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 JUN 15 PY 2000 VL 57 IS 12 BP 1841 EP 1853 DI 10.1175/1520-0469(2000)057<1841:TASTTC>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 326CV UT WOS:000087715800001 ER PT J AU Wang, DY Ward, WE Shepherd, GG Wu, DL AF Wang, DY Ward, WE Shepherd, GG Wu, DL TI Stationary planetary waves inferred from WINDII wind data taken within altitudes 90-120 km during 1991-96 SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID MIDDLE ATMOSPHERE; LOWER THERMOSPHERE; IMAGING INTERFEROMETER; MESOSPHERIC WINDS; GLOBAL STRUCTURE; CIRCULATION; SIMULATION; MODEL; WINTER AB A climatology of stationary planetary waves (SPWs) in horizontal winds at latitudes 70 degrees S-70 degrees N and altitudes 90-120 km is obtained from Wind-Imaging Interferometer (WINDII) green line measurements in December-January and March-April of 1991-96. The observed solstitial SPW fields are relatively stronger and dominated by zonal wavenumber-1 variations. In contrast, the equinoctial SPW fields are weaker and characterized by zonal wavenumber-2 variations. The zonal amplitude maxima of 10-25 m s(-1) are generally centered at the midlatitudes of 35 degrees-40 degrees in both hemispheres around 96 km, with the eastward perturbation velocity maxima around 90 degrees E for wavenumber 1 and 60 degrees and 240 degrees E for wavenumber 2. The meridional amplitude maxima are about 5-15 m s(-1) and show more variabilities in their latitude-height distributions. The meridional phases indicated that Eliassen-Palm (EP) fluxes were downward-poleward for the winter maxima, vertically varying poleward for the summer maxima, and more variable during March-April. The hemispheric-seasonal-interannual variations in amplitude and phase are of 10 m s(-1) and 30 degrees, respectively. In particular, a distinguishable local summer maximum with an amplitude of 10-20 m s(-1) is found to exist in the wavenumber-1 variation of zonal wind component. The hemispheric asymmetry is also characterized by the nodal phase (or phase jump) lines shifted toward the winter hemisphere by 10 degrees-30 degrees. Wave penetrations across the equator are observed with amplitudes of 5 m s(-1) at 97-100 km. While the summer maximum of the wavenumber-1 component persisted during the four years, large variability is found in the winter hemisphere where the wavenumber-2 component became significant at the 90-105-km region during December 1992-January 1993 and December 1993-January 1994 and at the 105-120-km region during December 1991-January 1992. The excitation due to in situ forcing of atonal gravity wave drag, which varies longitudinally, is thought to be largely responsible for the observed SPW particularly for the summer maximum, while the leakage of upward propagating SPW from the lower to the higher atmosphere also plays a role, especially in the winter and the equinoctial periods. C1 York Univ, Ctr Res Earth & Space Technol, N York, ON M3J 1P3, Canada. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Wang, DY (reprint author), York Univ, Ctr Res Earth & Space Technol, Petrie 206,4700 Keele St, N York, ON M3J 1P3, Canada. RI Ward, William/F-6263-2012; Wu, Dong/D-5375-2012 NR 23 TC 29 Z9 29 U1 0 U2 1 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 JUN 15 PY 2000 VL 57 IS 12 BP 1906 EP 1918 DI 10.1175/1520-0469(2000)057<1906:SPWIFW>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 326CV UT WOS:000087715800005 ER PT J AU Egbert, GD Ray, RD AF Egbert, GD Ray, RD TI Significant dissipation of tidal energy in the deep ocean inferred from satellite altimeter data SO NATURE LA English DT Article ID INTERNAL TIDES; ENERGETICS; CIRCULATION; FRICTION AB How and where the ocean tides dissipate their energy are longstanding questions(1) that have consequences ranging from the history of the Moon(2) to the mixing of the oceans(3). Historically, the principal sink of tidal energy has been thought to be bottom friction in shallow seas(4,5). There has long been suggestive evidence(6,7), however, that tidal dissipation also occurs in the open ocean through the scattering by ocean-bottom topography of surface tides into internal waves, but estimates of the magnitude of this possible sink have varied widely(3,8-11). Here we use satellite altimeter data from Topex/Poseidon to map empirically the tidal energy dissipation. We show that approximately 10(12) watts-that is, 1 TW, representing 25-30% of the total dissipation-occurs in the deep ocean, generally near areas of rough topography. Of the estimated 2 TW of mixing energy required to maintain the large-scale thermohaline circulation of the ocean(12), one-half could therefore be provided by the tides, with the other half coming from action(13) on the surface of the ocean. C1 Oregon State Univ, Coll Ocean & Atmospher Sci, Corvallis, OR 97331 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Egbert, GD (reprint author), Oregon State Univ, Coll Ocean & Atmospher Sci, Corvallis, OR 97331 USA. RI Ray, Richard/D-1034-2012; OI Egbert, Gary/0000-0003-1276-8538 NR 30 TC 335 Z9 349 U1 5 U2 56 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JUN 15 PY 2000 VL 405 IS 6788 BP 775 EP 778 DI 10.1038/35015531 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 324KJ UT WOS:000087620600045 ER PT J AU Yu, MF Files, BS Arepalli, S Ruoff, RS AF Yu, MF Files, BS Arepalli, S Ruoff, RS TI Tensile loading of ropes of single wall carbon nanotubes and their mechanical properties SO PHYSICAL REVIEW LETTERS LA English DT Article ID ELASTIC PROPERTIES AB The mechanical response of 15 single wall carbon nanotube (SWCNT) ropes under tensile load was measured. For 8 of these ropes strain data were obtained and they broke at strain values of 5.3% or lower. The force-strain data are well fit by a model that assumes the load is carried by the SWCNTs on the perimeter of each rope. This model provides an average breaking strength of SWCNTs on the perimeter of each rope; the 15 values range from 13 to 52 GPa (mean 30 GPa). Based on the same model the 8 average Young's modulus values determined range from 320 to 1470 GPa (mean 1002 GPa). C1 Washington Univ, Dept Phys, St Louis, MO 63130 USA. NASA, Lyndon B Johnson Space Ctr, Mat & Proc Technol Branch, EM2, Houston, TX 77058 USA. GB Tech Lockheed Martin, Houston, TX 77058 USA. RP Ruoff, RS (reprint author), Washington Univ, Dept Phys, St Louis, MO 63130 USA. RI Ruoff, Rodney/B-7605-2009; Arepalli, Sivaram/A-5372-2010; Yu, Min-Feng/C-2809-2012; Ruoff, Rodney/K-3879-2015 NR 23 TC 1523 Z9 1563 U1 28 U2 280 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 JUN 12 PY 2000 VL 84 IS 24 BP 5552 EP 5555 DI 10.1103/PhysRevLett.84.5552 PG 4 WC Physics, Multidisciplinary SC Physics GA 322RH UT WOS:000087522200024 ER PT J AU Ghosh, P AF Ghosh, P TI The structure of black hole magnetospheres - I. Schwarzschild black holes SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE accretion, accretion discs; black hole physics; galaxies : active; galaxies : jets; galaxies : nuclei ID UNIFORM MAGNETIC-FIELD; ACTIVE GALACTIC NUCLEI; ACCRETION DISKS; ELECTROMAGNETIC EXTRACTION; JETS; ELECTRODYNAMICS; FORMULATION; TURBULENCE; ENERGY; DYNAMO AB We introduce a multipolar scheme for describing the structure of stationary, axisymmetric, force-free black hole magnetospheres in the '3+1' formalism. We focus here on Schwarzschild space-time, giving a complete classification of the separable solutions of the stream equation. We show a transparent term-by-term analogy of our solutions with the familiar multipoles of flat-space electrodynamics. We discuss electrodynamic processes around disc-fed black holes in which our solutions find natural applications: (i) 'interior' solutions in studies of the Blandford-Znajek process of extracting the rotational energy of holes, and of the formation of relativistic jets in active galactic nuclei and 'microquasars'; (ii) 'exterior' solutions in studies of accretion disc dynamos, disc-driven winds and jets. On the strength of existing numerical studies, we argue that the poloidal field structures found here are also expected to hold with good accuracy for rotating black holes, except for the cases of the maximum possible rotation rates. We show that the closed-loop exterior solutions found here are not in contradiction with the Macdonald-Thorne theorem, as these solutions, which diverge logarithmically on the horizon of the hole H, only apply to those regions that exclude H. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Tata Inst Fundamental Res, Bombay 400005, Maharashtra, India. RP Ghosh, P (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM pranab@tifr.res.in NR 31 TC 21 Z9 22 U1 1 U2 3 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUN 11 PY 2000 VL 315 IS 1 BP 89 EP 97 DI 10.1046/j.1365-8711.2000.03410.x PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 321XK UT WOS:000087480400014 ER PT J AU Galama, TJ Tanvir, N Vreeswijk, PM Wijers, RAMJ Groot, PJ Rol, E van Paradijs, J Kouveliotou, C Fruchter, AS Masetti, N Pedersen, H Margon, B Deutsch, EW Metzger, M Armus, L Klose, S Stecklum, B AF Galama, TJ Tanvir, N Vreeswijk, PM Wijers, RAMJ Groot, PJ Rol, E van Paradijs, J Kouveliotou, C Fruchter, AS Masetti, N Pedersen, H Margon, B Deutsch, EW Metzger, M Armus, L Klose, S Stecklum, B TI Evidence for a supernova in reanalyzed optical and near-infrared images of GRB 970228 SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; supernovae : general ID GAMMA-RAY-BURST; HUBBLE-SPACE-TELESCOPE; 28 FEBRUARY 1997; 25 APRIL 1998; X-RAY; LIGHT-CURVE; ERROR BOX; SN 1998BW; AFTERGLOW; GRB-970228 AB We present B-, V-, R-C-, I-C-, J-, H-, K-, and K'-band observations of the optical transient (OT) associated with GRB 970228, based on a reanalysis of previously used images and unpublished data. In order to minimize calibration differences, we have collected and analyzed most of the photometry and consistently determined the magnitude of the OT relative to a set of secondary held stars. We confirm our earlier finding that the early decay of the light curves (before 1997 March 6) was faster than that at intermediate times (between 1997 March 6 and April 7). At late times the light curves resume a fast decay (after 1997 April 7). The early-time observations of GRB 970228 are consistent with relativistic blast-wave models, but the intermediate- and late-time observations are hard to understand in this framework. The observations are well explained by an initial power-law decay with alpha = -1.51 +/- 0.06 modified at later times by a Type Ic supernova light curve. Together with the evidence for GRB 980326 and GRB 980425, this gives further support for the idea that at least some gamma-ray bursts are associated with a possibly rare type of supernova. C1 Ctr High Energy Astrophys, NL-1098 SJ Amsterdam, Netherlands. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Univ Hertfordshire, Dept Phys Sci, Hatfield AL10 9AB, Herts, England. SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. NASA, MSFC, Huntsville, AL 35812 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. CNR, I-40129 Bologna, Italy. Copenhagen Univ Observ, D-2100 Copenhagen A, Denmark. Univ Washington, Dept Astron, Seattle, WA 98195 USA. CALTECH, SIRTF Sci Ctr, Pasadena, CA 91125 USA. Thuringer Landessternwarte Tautenburg, D-07778 Tautenburg, Germany. RP Galama, TJ (reprint author), CALTECH, Palomar Observ, 105-24, Pasadena, CA 91125 USA. RI Margon, Bruce/B-5913-2012; Galama, Titus/D-1429-2014; Groot, Paul/K-4391-2016 OI Galama, Titus/0000-0002-1036-396X; Groot, Paul/0000-0002-4488-726X NR 56 TC 164 Z9 166 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 2000 VL 536 IS 1 BP 185 EP 194 DI 10.1086/308909 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 330LJ UT WOS:000087963300015 ER PT J AU Done, C Madejski, GM Zycki, PT AF Done, C Madejski, GM Zycki, PT TI The relativistic iron line profile in the Seyfert 1 galaxy IC 4329A SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; black hole physics; galaxies : individual (IC 4329A) galaxies : Seyfert; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; X-RAY REFLECTION; COLD MATTER; CYGNUS X-1; TIMING EXPLORER; ACCRETION DISK; PERFORMANCE; SPECTRA; GS-2023+338; EVOLUTION AB We present simultaneous ASCA and RXTE data on the bright Seyfert 1 galaxy IC 4329A. The iron line is significantly broadened, but not to the extent expected from an accretion disk that extends down to the last stable orbit around a black hole. We marginally detect a narrow-line component, presumably from the molecular torus, but even including this gives a line profile from the accretion disk that is significantly narrower than that seen in MCG - 6-30-15, and is much more like that seen from the low/hard-state galactic black hole candidates. This is consistent with the inner disk being truncated before the last stable orbit, forming a hot flow at small radii, as in the advection-dominated accretion how (ADAF) models. However, we cannot rule out the presence of an inner disk that does not contribute to the reflected spectrum, either because of extreme ionization suppressing the characteristic atomic features of the reflected spectrum or because the X-ray source is intrinsically anisotropic, so it does not illuminate the inner disk. The source was monitored by RXTE every 2 days for 2 months, and these snapshot spectra show that there is intrinsic spectral variability. The data are good enough to disentangle the power law from the reflected continuum, and we see that the power law softens as the source brightens. The lack of a corresponding increase in the observed reflected spectrum implies that either the changes in disk inner radial extent and/or ionization structure are small, or that the variability is actually driven by changes in the seed photons that are decoupled from the hard X-ray mechanism. C1 Univ Durham, Dept Phys, Durham DH1 3LE, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Nicolaus Copernicus Astron Ctr, PL-00716 Warsaw, Poland. RP Done, C (reprint author), Univ Durham, Dept Phys, South Rd, Durham DH1 3LE, England. RI done, chris/D-4605-2016 OI done, chris/0000-0002-1065-7239 NR 57 TC 72 Z9 72 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 2000 VL 536 IS 1 BP 213 EP 224 DI 10.1086/308911 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 330LJ UT WOS:000087963300017 ER PT J AU Mould, JR Ridgewell, A Gallagher, JS Bessell, MS Keller, S Calzetti, D Clarke, JT Trauger, JT Grillmair, C Ballester, GE Burrows, CJ Krist, J Crisp, D Evans, R Griffiths, R Hester, JJ Hoessel, JG Holtzman, JA Scowen, PA Stapelfeldt, KR Sahai, R Watson, A Meadows, V AF Mould, JR Ridgewell, A Gallagher, JS Bessell, MS Keller, S Calzetti, D Clarke, JT Trauger, JT Grillmair, C Ballester, GE Burrows, CJ Krist, J Crisp, D Evans, R Griffiths, R Hester, JJ Hoessel, JG Holtzman, JA Scowen, PA Stapelfeldt, KR Sahai, R Watson, A Meadows, V TI Jet-induced star formation in Centaurus A SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 5128); galaxies : jets; galaxies : stellar content; radio continuum : galaxies ID FILAMENTS; NGC-5128; CLUSTERS; WFPC2 AB The inner part of the northeast middle radio lobe of the radio galaxy Centaurus A is the site of complex interactions. This area contains a large H I cloud as well as filaments of ionized gas and associated blue knots, several of which exist along the northeastern edge of the radio-emitting zones. We observed the filaments and blue knots with the Hubble Space Telescope using WFPC5 and the ionized gas from the ground. Our sensitive, high angular resolution WFPC2 images reveal the presence of young stars, many concentrated in what appear to be OB associations, superimposed on a background sheet of older stars that is typical of the Cen A halo. The ages of the OB associations are estimated to be less than 15 Myr from a comparison of color-magnitude diagrams with those for the Large Magellanic Cloud star cluster NGC 2004, and younger stellar groups may be nearer regions of Ha emission. We discuss our data in the context of models for star formation stimulated by interactions between the radio jet and gas cloud. C1 Australian Natl Univ, Mt Stromlo Observ, Inst Adv Studies, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Michigan, Dept Atmospher & Ocean Sci, Ann Arbor, MI 48109 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, IPAC, Pasadena, CA 91125 USA. Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. Arizona State Univ, Dept Phys & Astron, Tempe, AZ 85287 USA. New Mexico State Univ, Dept Astron, Dept 4500, Las Cruces, NM 88003 USA. Univ Nacl Autonoma Mexico, Inst Astron, Morelia 58090, Michoacan, Mexico. RP Mould, JR (reprint author), Australian Natl Univ, Mt Stromlo Observ, Inst Adv Studies, Res Sch Astron & Astrophys, Weston Creek PO, Weston, ACT 2611, Australia. RI Stapelfeldt, Karl/D-2721-2012 NR 23 TC 44 Z9 44 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 2000 VL 536 IS 1 BP 266 EP 276 DI 10.1086/308927 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 330LJ UT WOS:000087963300021 ER PT J AU Gibb, EL Whittet, DCB Schutte, WA Boogert, ACA Chiar, JE Ehrenfreund, P Gerakines, PA Keane, JV Tielens, AGGM van Dishoeck, EF Kerkhof, O AF Gibb, EL Whittet, DCB Schutte, WA Boogert, ACA Chiar, JE Ehrenfreund, P Gerakines, PA Keane, JV Tielens, AGGM van Dishoeck, EF Kerkhof, O TI An inventory of interstellar ices toward the embedded protostar W33A SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; infrared : ISM : lines and bands; ISM : individual (W33A); ISM : molecules ID INFRARED BAND STRENGTHS; YOUNG STELLAR OBJECTS; CARBONYL SULFIDE OCS; ISO-SWS OBSERVATIONS; COMET HALE-BOPP; ABSORPTION FEATURES; MOLECULAR CLOUDS; MICRON SPECTRA; DARK CLOUD; MU-M AB This paper presents, for the first time, a complete 2.4-25 mu m spectrum of the dust-embedded young stellar object W33A. The spectrum was obtained with the Short Wavelength Spectrometer of the Infrared Space Observatory at a mean resolving power of similar to 750. The spectrum displays deep H(2)O ice and silicate absorptions centered at 3.0 and 9.7 mu m, respectively, together with absorption features identified with various other molecules in the solid phase. The 2.4-5.0 mu m region of the spectrum is used to investigate the long-standing problem of the H(2)O ice column density toward W33A, by means of the stretching and combination mode features at 3.0 and 4.5 mu m. Although no flux is seen at the center of the 3.0 mu m feature, its central depth may be constrained by fitting assumed profiles to the short- and long-wavelength wings in our spectrum. We deduce that a value of N(H(2)O) = (1.1 +/- 0.3) x 10(19) cm(-2) is consistent with these features, a factor of at least 3 less than predicted by the H(2)O bending mode at 6.0 mu m; the reason for this discrepancy is unclear. We report new results on the abundances of nitrogen-bearing species in the ices toward W33A. Solid NH, is detected for the first time in this line of sight, by means of the inversion-mode feature at 9.0 mu m. The column density is N(NH,)=(1.7 +/- 0.4) x 10(18) cm(-2) implying an abundance of similar to 15% relative to H(2)O, comparable to that recently reported toward the young star NGC 7538 IRS 9. However, we find no convincing evidence for absorptions associated with the C=N stretching mode of nitriles in the 4.4-4.6 mu m region of the spectrum. If nitriles are present in the ices along this line of sight, they must have column density no more than -10(17) cm(-2) or similar to 1% relative to H(2)O. This argues against identification of the deep 4.62 mu m 'XCN' feature with isonitriles, as an implausibly low nitrile to isonitrile abundance ratio (<0.1) would be implied. New and previously published results are combined to construct an inventory of column densities and abundances (normalized to H(2)O) for all known species detected in molecular ices toward W33A. A band strength appropriate to the cyanate ion is assumed to provide quantitative results for XCN. Results are compared with those for other well-studied lines of sight, including the Taurus held star Elias 16, the Galactic center source Sgr A*, and the young stellar objects NGC 7538 IRS 9, GL 2136, and GL 7009S. The CO and XCN abundances are used as indicators of thermal and energetic processing, respectively (where energetic processing may include either UV photolysis or energetic ion bombardment). Abundances for CH(3)OH vary from below 3% in unprocessed ices to similar to 20%-30% in W33A and GL 7009S, consistent with formation by energetic processing. In contrast, CH(4) shows little evidence of variation. Abundance data for cometary ices indicate some general similarities with interstellar and protostellar ices. CO and CH(3)OH show comet-to-comet variations that may provide clues to their origins. The highest CH(3)OH concentrations in comets are comparable with average values for interstellar/protostellar ices. 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. Leiden Observ, NL-2300 RA Leiden, Netherlands. Univ Groningen, Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SETI Inst, Mountain View, CA 94043 USA. RP Gibb, EL (reprint author), Rensselaer Polytech Inst, Dept Phys Appl Phys & Astron, Troy, NY 12180 USA. RI Gerakines, Perry/B-9705-2009; Gerakines, Perry/D-2226-2012 OI Gerakines, Perry/0000-0002-9667-5904 NR 70 TC 299 Z9 302 U1 0 U2 17 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 2000 VL 536 IS 1 BP 347 EP 356 DI 10.1086/308940 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 330LJ UT WOS:000087963300029 ER PT J AU Hall, TA Finley, JP Corbet, RHD Thomas, RC AF Hall, TA Finley, JP Corbet, RHD Thomas, RC TI RXTE observations of the X-ray binary 2S 0114+650 SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : individual (2S 0114+650); stars : neutron; X-rays : stars ID PERIODIC OUTBURSTS; 2S-0114+650; SYSTEM; PULSAR AB Observations from the proportional counter array experiment on board the Rossi X-Ray Timing Explorer (RXTE) of the temporal and spectral properties of the high-mass X-ray binary 2S 0114+ 650 are reported. We find highly variable X-ray emission modulated at a period of 2.73 hr. The temporal results indicate that 2S 0114+ 650 is the slowest neutron star rotator presently known. Spectral analysis reveals parameters typical of a high-mass X-ray binary system having an absorbed power law with an index of about 1.3 with a high-energy cutoff at approximately 8 keV. The introduction of a fluorescent iron line at 6.4 keV allowed better spectral fits, particularly during low states of emission. We have also determined that the intensity of 2S 0114+650 is strongly attenuated during part of the orbit, which makes it a member of the small class of eclipsing massive X-ray binaries. C1 Purdue Univ, Dept Phys, W Lafayette, IN 47907 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. Univ Oklahoma, Dept Phys & Astron, Norman, OK 73019 USA. RP Purdue Univ, Dept Phys, W Lafayette, IN 47907 USA. EM tahall@physics.purdue.edu; finley@physics.purdue.edu; corbet@lheamail.gsfc.nasa.gov; thomas@mail.nhn.ou.edu NR 20 TC 23 Z9 24 U1 1 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 JUN 10 PY 2000 VL 536 IS 1 BP 450 EP 454 DI 10.1086/308924 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 330LJ UT WOS:000087963300040 ER PT J AU Ragot, BR AF Ragot, BR TI Parallel mean free path of solar cosmic rays SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic rays; plasmas; scattering; solar wind; turbulence; waves ID QUASI-LINEAR THEORY; PITCH-ANGLE SCATTERING; ENERGETIC PARTICLES; FIELD APPROACH; TRANSPORT; ACCELERATION; COEFFICIENTS; DIFFUSION; WAVES AB Isotropic, nonresonant fast magnetosonic waves (FMWs) very efficiently scatter low-rigidity cosmic rays through the zero pitch-angle cosine mu. The derivation of this effect is generalized here to an anisotropic, conic turbulence of FMWs with an arbitrary spectral shape. Compared to the one of the FMWs, the contributions to the nonresonant scattering from both a slab electromagnetic turbulence and oblique Alfven waves are shown to be negligible. As a consequence, the nonresonant scattering rate by FMWs alone is combined with the scattering rates due to gyroresonance with the AlfvCn waves and transit-time damping with the FMWs to fit the parallel mean free path obtained from measurements of solar cosmic rays as a function of the particles' rigidities. The global fit of a large set of data points, resulting from many solar events, displays three distinct regions (plus a transition region between the two first ones), where the transit-time damping at / mu/ similar to 1, the nonresonant scattering by FMWs at mu approximate to 0, and the gyroresonance with AlfvCn waves at mu approximate to 0 successively determine the parallel mean free path for rigidities ranging from 10(-2) to 10(5) MV. Very accurate fits are further obtained for several independent solar events, during which particles were detected in the whole range of rigidities-from 1 to similar to 5 x 10(2) MV-where the nonresonant scattering determines the mean free path. Finally, the use of a conic turbulence of FMWs with an opening angle deduced from the damping rate of the waves relates the form of the FMW turbulence to the parameters of the plasma during each of the solar events. It argues in favor of a very strong anisotropy of the FMW spectrum above about 10-2 times the ion gyrofrequency. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Ragot, BR (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NR 27 TC 11 Z9 11 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 2000 VL 536 IS 1 BP 455 EP 464 DI 10.1086/308920 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 330LJ UT WOS:000087963300041 ER PT J AU Antiochos, SK MacNeice, PJ Spicer, DS AF Antiochos, SK MacNeice, PJ Spicer, DS TI The thermal nonequilibrium of prominences SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : chromosphere; Sun : corona; Sun : prominences ID SOLAR PROMINENCES; QUIESCENT PROMINENCES; CORONAL LOOPS; FILAMENTS; REGION; FIELDS; MODEL; FLOWS AB We present numerical simulations and analytic theory for the thermal nonequilibrium of solar coronal Bur tubes that have a stretched-out, dipped geometry, appropriate for a prominence/filament Our simulations indicate that if the heating in such a flux tube is localized near the chromosphere, then condensations appear which undergo a continuous cycle of formation, motion, and destruction, even though the heating and all other imposed conditions on the loop are purely time independent. We show how this nonsteady evolution can be understood in terms of simple scaling-law theory. The implications of thermal nonequilibrium for observations of the solar corona are discussed. We argue that the model can explain both the formation of prominence condensations and recent observations of their dynamics. C1 USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. Drexel Univ, Dept Phys & Atmospher Sci, Philadelphia, PA USA. NASA, Goddard Space Flight Ctr, NASA Ctr Computat Sci, Greenbelt, MD 20771 USA. RP USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. EM antiochos@nrl.navy.mil RI MacNeice, Peter/F-5587-2012; Antiochos, Spiro/D-4668-2012 OI Antiochos, Spiro/0000-0003-0176-4312 NR 29 TC 51 Z9 51 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 2000 VL 536 IS 1 BP 494 EP 499 DI 10.1086/308922 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 330LJ UT WOS:000087963300044 ER PT J AU Arendt, RG Fixsen, DJ Moseley, SH AF Arendt, RG Fixsen, DJ Moseley, SH TI Dithering strategies for efficient self-calibration of imaging arrays SO ASTROPHYSICAL JOURNAL LA English DT Article DE instrumentation : detectors; methods : data analysis; techniques : photometric ID COBE FIRAS INSTRUMENT; MICROWAVE AB With high-sensitivity imaging arrays, accurate calibration is essential to achieve the limits of detection of space observatories. One can simultaneously extract information about the scene being observed and the calibration properties of the detector and imaging system from redundant dithered images of a scene. There are large differences in the effectiveness of dithering strategies for allowing the separation of detector properties from sky brightness measurements. In this paper, we quantify these differences by developing a figure of merit (FOM) for dithering procedures based on their usefulness for allowing calibration on all spatial scales. The figure of merit measures how well the gain characteristics of the detector are encoded in the measurements, and is independent of the techniques used to analyze the data. Patterns similar to the antenna arrangements of radio interferometers with good u-nu plane coverage are found to have good figures of merit. We present patterns for both deep surveys of limited sky areas and for shallow surveys. By choosing a strategy that encodes the calibration in the observations in an easily extractable way, we enhance our ability to calibrate our detector systems and to reach the ultimate limits of sensitivity that are required to achieve the promise of many missions. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Arendt, RG (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 685, Greenbelt, MD 20771 USA. RI Moseley, Harvey/D-5069-2012 NR 15 TC 16 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 2000 VL 536 IS 1 BP 500 EP 512 DI 10.1086/308923 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 330LJ UT WOS:000087963300045 ER PT J AU Williams, RM Petre, R Chu, YH Chen, CHR AF Williams, RM Petre, R Chu, YH Chen, CHR TI Resolving SNR 0540-6944 from LMC X-l with CHANDRA SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (Large Magellanic Cloud); supernova remnants; x-rays : ISM ID LARGE-MAGELLANIC-CLOUD; SUPERNOVA-REMNANTS; OB-ASSOCIATIONS; LMC-X-1; HIDDEN AB We examine the supernova remnant SNR 0540-697 in the Large Magellanic Cloud (LMC) using data from the Chandra Advanced CCD Imaging Spectrometer. The X-ray emission from this supernova remnant (SNR) had previously been hidden in the bright emission of the nearby X-ray binary LMC X-1; however, new observations with Chandra can finally reveal the SNR's structure and spectrum. We find the SNR to be a thick-shelled structure about 19 pc in diameter, with a brightened northeast region. Spectral results suggest a temperature of 0.31 keV and an X-ray luminosity (0.3-3.0 keV) of 8.4 x 10(33) ergs s(-1). We estimate an age of 12,000-20,000 yr for this SNR, but note that this estimate does not take into account the possibility of cavity expansion or other environmental effects. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Illinois, Dept Astron, Urbana, IL 61801 USA. RP Williams, RM (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 16 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 2000 VL 536 IS 1 BP L27 EP L30 DI 10.1086/312729 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 330LL UT WOS:000087963500007 ER PT J AU Majumdar, D Raychaudhuri, A Kar, K Ray, A Sutaria, FK AF Majumdar, D Raychaudhuri, A Kar, K Ray, A Sutaria, FK TI Oscillation effects on neutrinos from the early phase of a nearby supernova SO INTERNATIONAL JOURNAL OF MODERN PHYSICS A LA English DT Article ID GRAVITATIONAL COLLAPSE; ELECTRON-CAPTURE; MASSES; STARS; SN1987A; FUTURE; SAMPLE; BURSTS AB Recent observations of atmospheric and solar neutrinos strongly support the phenomenon of neutrino oscillations - a manifestation of a nonzero and nondegenerate mass spectrum. Neutrinos emitted during stellar core collapse leading to a supernova are of the electron neutrino type at source - as for solar and reactor (anti-)neutrinos and provide another useful tool in the search for flavor oscillations. Their propagation to an earth-bound detector involves length scales that can uniquely probe very small neutrino mass differences hitherto unobservable. Although the number of neutrinos emitted during the collapse phase is much smaller than that emitted in the post-bounce epoch tin which all flavors of neutrinos are emitted), a nearby supernova event may nevertheless register a substantial number of detections from the collapse phase at SuperKamiokande (SK) and the Sudbury Neutrino Observatory (SNO). The measurement of the fluence of these neutrinos at SNO and the distortion of the spectrum detected at SK can yield valuable information about neutrino mass difference and mixing which are illustrated here in terms of two- and three-flavor oscillation models. In particular, we find that R-SNO, the ratio of the calorimetric detection of the neutrino fluence via the neutral current channel to the total energy integrated fluence observed via the charged current channel at SNO, is a sensitive probe for oscillations. We also find that ai,, the ratio of the nth central moments of the distributions seen at SK and SNO (charged current), can be a useful tool (especially for n = 3) to look for neutrino oscillations. C1 Univ Calcutta, Dept Phys, Calcutta 700009, W Bengal, India. Saha Inst Nucl Phys, Calcutta 700064, W Bengal, India. Tata Inst Fundamental Res, Bombay 400005, Maharashtra, India. NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20770 USA. Inter Univ Ctr Astron & Astrophys, Poona 411007, Maharashtra, India. RP Majumdar, D (reprint author), Univ Calcutta, Dept Phys, 92 Acharya Prafulla Chandra Rd, Calcutta 700009, W Bengal, India. NR 29 TC 0 Z9 0 U1 0 U2 0 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA JOURNAL DEPT PO BOX 128 FARRER ROAD, SINGAPORE 912805, SINGAPORE SN 0217-751X J9 INT J MOD PHYS A JI Int. J. Mod. Phys. A PD JUN 10 PY 2000 VL 15 IS 14 BP 2105 EP 2120 DI 10.1142/S0217751X00000872 PG 16 WC Physics, Nuclear; Physics, Particles & Fields SC Physics GA 326AQ UT WOS:000087709900006 ER PT J AU Povitsky, A Morris, PJ AF Povitsky, A Morris, PJ TI A higher-order compact method in space and time based on parallel implementation of the Thomas algorithm SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE parallel computing; processor scheduling; high-order numerical method; compact scheme; pipelined Gauss elimination; banded linear systems ID FINITE-DIFFERENCE SCHEMES; EQUATIONS AB In this study we propose a novel method to parallelize high-order compact numerical algorithms for the solution of three-dimensional PDEs in a space-time domain. For such a numerical integration most of the computer time is spent in computation of spatial derivatives at each stage of the Runge-Kutta temporal update. The most efficient direct method to compute spatial derivatives on a serial computer is a version of Gaussian elimination for narrow linear banded systems known as the Thomas algorithm. In a straightforward pipelined implementation of the Thomas algorithm processors are idle due to the forward and backward recurrences of the Thomas algorithm. To utilize processors during this time, we propose to use them for either nonlocal data-independent computations, solving lines in the next spatial direction, or local data-dependent computations by the Runge-Kutta method. To achieve this goal, control of processor communication and computations by a static schedule is adopted. Thus, our parallel code is driven by a communication and computation schedule instead of the usual "creative programming" approach. The obtained parallelization speed-up of the novel algorithm is about twice as much as that for the basic pipelined algorithm and close to that for the explicit DRP algorithm. Use of the algorithm is demonstrated and comparisons with other schemes are given. (C) 2000 Academic Press. C1 NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. Penn State Univ, Dept Aerosp Engn, University Pk, PA 16802 USA. RP Povitsky, A (reprint author), NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. NR 21 TC 15 Z9 15 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD JUN 10 PY 2000 VL 161 IS 1 BP 182 EP 203 DI 10.1006/jcph.2000.6497 PG 22 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 323HY UT WOS:000087561000010 ER PT J AU Twine, TE Kustas, WP Norman, JM Cook, DR Houser, PR Meyers, TP Prueger, JH Starks, PJ Wesely, ML AF Twine, TE Kustas, WP Norman, JM Cook, DR Houser, PR Meyers, TP Prueger, JH Starks, PJ Wesely, ML TI Correcting eddy-covariance flux underestimates over a grassland SO AGRICULTURAL AND FOREST METEOROLOGY LA English DT Article DE eddy-covariance; friction velocity; evapotranspiration flux ID LATENT-HEAT FLUX; WATER-VAPOR; BOWEN-RATIO; ENERGY-BALANCE; CARBON-DIOXIDE; PINE FOREST; SURFACE; EXCHANGES; SYSTEMS; ERRORS AB Independent measurements of the major energy balance flux components are not often consistent with the principle of conservation of energy. This is referred to as a lack of closure of the surface energy balance. Most results in the literature have shown the sum of sensible and latent heat fluxes measured by eddy covariance to be less than the difference between net radiation and soil heat fluxes. This under-measurement of sensible and latent heat fluxes by eddy-covariance instruments has occurred in numerous field experiments and among many different manufacturers of instruments. Four eddy-covariance systems consisting of the same models of instruments were set up side-by-side during the Southern Great Plains 1997 Hydrology Experiment and all systems under-measured fluxes by similar amounts. One of these eddy-covariance systems was collocated with three other types of eddy-covariance systems at different sites; all of these systems under-measured the sensible and latent-heat fluxes. The net radiometers and soil heat flux plates used in conjunction with the eddy-covariance systems were calibrated independently and measurements of net radiation and soil heat flux showed little scatter for various sites. The 10% absolute uncertainty in available energy measurements was considerably smaller than the systematic closure problem in the surface energy budget, which varied from 10 to 30%. When available-energy measurement errors are known and modest, eddy-covariance measurements of sensible and latent heat fluxes should be adjusted for closure. Although the preferred method of energy balance closure is to maintain the Bowen-ratio, the method for obtaining closure appears to be less important than assuring that eddy-covariance measurements are consistent with conservation of energy. Based on numerous measurements over a sorghum canopy, carbon dioxide fluxes, which are measured by eddy covariance, are underestimated by the same factor as eddy covariance evaporation measurements when energy balance closure is not achieved. Published by Elsevier Science B.V. C1 Univ Wisconsin, Dept Atmospher & Ocean Sci, Madison, WI 53706 USA. USDA ARS, Hydrol Lab, Beltsville, MD 20705 USA. Univ Wisconsin, Dept Soil Sci, Madison, WI 53706 USA. Argonne Natl Lab, Argonne, IL 60439 USA. NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Greenbelt, MD 20771 USA. Oak Ridge Natl Lab, NOAA, Atmospher Turbulence & Diffus, Oak Ridge, TN 37831 USA. USDA ARS, Natl Soil Tilth Lab, Ames, IA 50011 USA. USDA ARS, Grazinglands Res Lab, El Reno, OK 73036 USA. RP Twine, TE (reprint author), Univ Wisconsin, Dept Atmospher & Ocean Sci, 1225 W Dayton St, Madison, WI 53706 USA. RI Twine, Tracy/H-2337-2013; Houser, Paul/J-9515-2013; Meyers, Tilden/C-6633-2016 OI Twine, Tracy/0000-0002-8457-046X; Houser, Paul/0000-0002-2991-0441; NR 40 TC 805 Z9 855 U1 8 U2 125 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-1923 J9 AGR FOREST METEOROL JI Agric. For. Meteorol. PD JUN 8 PY 2000 VL 103 IS 3 BP 279 EP 300 DI 10.1016/S0168-1923(00)00123-4 PG 22 WC Agronomy; Forestry; Meteorology & Atmospheric Sciences SC Agriculture; Forestry; Meteorology & Atmospheric Sciences GA 322VQ UT WOS:000087530300004 ER PT J AU Parusel, ABJ Grimme, S AF Parusel, ABJ Grimme, S TI A theoretical study of the excited states of chlorophyll a and pheophytin a SO JOURNAL OF PHYSICAL CHEMISTRY B LA English DT Article ID DENSITY-FUNCTIONAL THEORY; FREE-BASE PORPHIN; SPECTRUM; EXCITATION AB The first six excited states of pheophytin a and chlorophyll a with the phytyl chain replaced by a hydrogen atom have been calculated using a combination of density functional theory and the multireference configuration interaction method (DFT/MRCI). The calculations accurately reproduce experimental absorption energies and intensities. Four and three excited states are calculated in the visible region of pheophytin a and chlorophyll a, respectively. We thus predict the existence of more than the two Q(x) and Q(y) electronic states in this energy range. These additional states are of significant double-excitation character and cannot be explained within the four frontier orbital model. Two strongly allowed states are calculated in the Soret region at 2.9 eV. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Munster, Inst Organ Chem, D-48149 Munster, Germany. RP Parusel, ABJ (reprint author), Inst Theoret Chem & Struct Biol, Althanstr 14, A-1090 Vienna, Austria. RI Grimme, Stefan/B-2873-2010 NR 18 TC 63 Z9 63 U1 0 U2 18 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5647 J9 J PHYS CHEM B JI J. Phys. Chem. B PD JUN 8 PY 2000 VL 104 IS 22 BP 5395 EP 5398 DI 10.1021/jp000346w PG 4 WC Chemistry, Physical SC Chemistry GA 347RN UT WOS:000088943100026 ER PT J AU Gaidos, EJ Nimmo, F AF Gaidos, EJ Nimmo, F TI Planetary science - Tectonics and water on Europa SO NATURE LA English DT Article ID GEOLOGICAL EVIDENCE; FRACTURE C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Cambridge, Dept Earth Sci, Bullard Labs, Cambridge CB3 0EZ, England. RP Gaidos, EJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 46 Z9 47 U1 2 U2 9 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JUN 8 PY 2000 VL 405 IS 6787 BP 637 EP + DI 10.1038/35015170 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 321QH UT WOS:000087465800035 PM 10864313 ER PT J AU Knauth, DC Federman, SR Lambert, DL Crane, P AF Knauth, DC Federman, SR Lambert, DL Crane, P TI Newly synthesized lithium in the interstellar medium SO NATURE LA English DT Article ID GALACTIC COSMIC-RAYS; LI-7/LI-6 RATIO; DIFFUSE CLOUDS; ISOTOPE RATIO; ZETA-OPHIUCHI; ELEMENTS; STARS; ABUNDANCES; CARBON; LINES AB Astronomical observations of elemental and isotopic abundances provide the means to determine the source of elements and to reveal their evolutionary pathways since the formation of the Galaxy some 15 billion years ago. The abundance of lithium is particularly interesting because, although some of it is thought to be primordial, most results from spallation reactions (in which Galactic cosmic rays break apart larger nuclei in the interstellar medium). Spallation reactions are crucial for the production of other light elements(1), such as beryllium and boron, so observations of lithium isotopic abundances can be used to test model predictions(2-5) for light-element synthesis in general. Here we report observations of Li-7 and Li-6 abundances in several interstellar clouds lying in the direction of the star o Persei. We rnd the abundance ratio Li-7/Li-6 to be about 2, which is significantly lower than the average Solar System value of 12.3 (refs 6, 7). An abundance ratio of 2 is clear evidence that the observed lithium must have resulted entirely from spallation, confirming a basic tenet of light-element synthesis(2-5). The total lithium abundance, however, is not enhanced as expected. C1 Univ Toledo, Dept Phys & Astron, Toledo, OH 43606 USA. Univ Texas, Dept Astron, Austin, TX 78712 USA. Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA. NASA Headquarters, Washington, DC 20546 USA. RP Federman, SR (reprint author), Univ Toledo, Dept Phys & Astron, Toledo, OH 43606 USA. NR 28 TC 36 Z9 37 U1 0 U2 5 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JUN 8 PY 2000 VL 405 IS 6787 BP 656 EP 658 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 321QH UT WOS:000087465800038 ER PT J AU Lewis, RM Torczon, V AF Lewis, RM Torczon, V TI Pattern search methods or linearly constrained minimization SO SIAM JOURNAL ON OPTIMIZATION LA English DT Article DE pattern search; linearly constrained minimization ID CONVERGENCE AB We extend pattern search methods to linearly constrained minimization. We develop a general class of feasible point pattern search algorithms and prove global convergence to a Karush-Kuhn-Tucker point. As in the case of unconstrained minimization, pattern search methods for linearly constrained problems accomplish this without explicit recourse to the gradient or the directional derivative of the objective. Key to the analysis of the algorithms is the way in which the local search patterns conform to the geometry of the boundary of the feasible region. C1 NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. Coll William & Mary, Dept Comp Sci, Williamsburg, VA 23187 USA. RP Lewis, RM (reprint author), NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Mail Stop 132C, Hampton, VA 23681 USA. NR 18 TC 183 Z9 194 U1 0 U2 9 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 1052-6234 J9 SIAM J OPTIMIZ JI SIAM J. Optim. PD JUN 6 PY 2000 VL 10 IS 3 BP 917 EP 941 DI 10.1137/S1052623497331373 PG 25 WC Mathematics, Applied SC Mathematics GA 321JH UT WOS:000087452000015 ER PT J AU Ruge, JW Li, Y McCormick, S Brandt, A Bates, JR AF Ruge, JW Li, Y McCormick, S Brandt, A Bates, JR TI A nonlinear multigrid solver for a semi-Lagrangian potential vorticity-based shallow-water model on the sphere SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE multigrid methods; shallow-water equations; atmospheric modeling; semi-Lagrangian methods; nonlinear PDEs ID EQUATIONS AB In an earlier paper, we developed a new formulation of the shallow-water equations on the sphere, based on the semi-Lagrangian advection of potential vorticity. An important feature of our two-time-level model is that forward extrapolation of the nonlinear terms is avoided. In this paper, we develop a multigrid algorithm for solving the resulting system of three coupled nonlinear equations. We include a discussion of basic multigrid methods, along with some more advanced techniques required for the development of the multigrid scheme for this system. Results are presented showing that usual optimal multigrid efficiency is obtained. C1 Front Range Sci Computat, Boulder, CO USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Colorado, Dept Appl Math, Boulder, CO 80309 USA. Weizmann Inst Sci, IL-76100 Rehovot, Israel. Univ Copenhagen, Copenhagen, Denmark. RP Ruge, JW (reprint author), Front Range Sci Computat, Boulder, CO USA. NR 12 TC 6 Z9 6 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 1064-8275 J9 SIAM J SCI COMPUT JI SIAM J. Sci. Comput. PD JUN 5 PY 2000 VL 21 IS 6 BP 2381 EP 2395 DI 10.1137/S1064827595284841 PG 15 WC Mathematics, Applied SC Mathematics GA 324UU UT WOS:000087640400024 ER PT J AU Ross, MD AF Ross, MD TI Changes in ribbon synapses and rough endoplasmic reticulum of rat utricular macular hair cells in weightlessness SO ACTA OTO-LARYNGOLOGICA LA English DT Article DE backpropagation; c synapses; reactive synaptogenesis; ribosomes; synaptic plasticity ID VESTIBULAR SYSTEM; GUINEA-PIG; NEURONS; ORGAN; CORTI; CAT AB This study combined ultrastructural and statistical methods to learn the effects of weightlessness on rat utricular maculae. A principle aim was to determine whether weightlessness chiefly affects ribbon synapses of type II cells, since the cells communicate predominantly with branches of primary vestibular afferent endings. Maculae were microdissected from Right and ground control rat inner ears collected on day 13 of a 14-day spaceflight (F13), landing day (R0) and day 14 postflight (R14) and were prepared for ultrastructural study. Ribbon synapses were counted in hair cells examined in a Zeiss 902 transmission electron microscope. Significance of synaptic mean differences was determined for all hair cells contained within 100 section series, and for a subset of complete hair cells, using SuperANOVA(TM) software. The synaptic mean for all type II hair cells of F13 flight rats increased by 100% and that for complete cells by 200%. Type I cells were less affected, with synaptic mean differences statistically insignificant in complete cells. Synapse deletion began within 8 h upon return to Earth. Additionally, hair cell laminated rough endoplasmic reticulum of flight rats was reversibly disorganized on RO. Results support the thesis that synapses in type II hair cells are uniquely affected by altered gravity. Type II hair cells may be chiefly sensors of gravitational and type I cells of translational linear accelerations. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Ross, MD (reprint author), Univ New Mexico, Hlth Sci Ctr, Telemed Program, 1005 Columbia NE, Albuquerque, NM 87131 USA. FU PHS HHS [47305] NR 25 TC 36 Z9 37 U1 0 U2 0 PU TAYLOR & FRANCIS AS PI OSLO PA CORT ADELERSGT 17, PO BOX 2562, SOLLI, 0202 OSLO, NORWAY SN 0001-6489 J9 ACTA OTO-LARYNGOL JI Acta Oto-Laryngol. PD JUN PY 2000 VL 120 IS 4 BP 490 EP 499 DI 10.1080/000164800750045983 PG 10 WC Otorhinolaryngology SC Otorhinolaryngology GA 336NF UT WOS:000088308600006 PM 10958400 ER PT J AU Sokolowska, J Pohorille, A AF Sokolowska, J Pohorille, A TI Models of risk and choice: challenge or danger SO ACTA PSYCHOLOGICA LA English DT Article; Proceedings Paper CT 17th Research Conference on Subjective Probability Utility and Decision Making (SPUDM 17) CY AUG 09-11, 1999 CL MANNHEIM, GERMANY SP European Assoc Decis Making, Univ Mannheim, Sonderforsch Bereich 504 DE risk perception; risk acceptance; dimensional model of risk perception; model of acceptance based on risk rates ID PERCEIVED RISK; PROSPECT-THEORY; PERCEPTION; DECISION; CONJOINT; PREFERENCES; ASPIRATION; JUDGMENTS; GAMBLES AB A dimensional model of perceived risk and a model of risk acceptance based on risk rates are proposed in this paper. In line with the proposed model of perceived risk, risk is a linear combination of the three basic dimensions of a risky situation: the amount and probability of loss and the amount of gain. It is assumed that psychological transformations are made on these dimensions. According to the model of acceptance, acceptance is judged by making a trade-off between perceived risk and the amount of gain. These models have been investigated in two experiments, in which risk judgments and acceptance rates for a set of descriptions of risky investments were collected from managers in Poland. The proposed dimensional model of perceived risk was compared to the distributional models of risk and to the risk models based on the expectation principle. The best fit was obtained for the proposed model. It was also found that perceived risk was useful in predicting acceptance rates. Better fits were obtained for the models of acceptance, based on perceived risk, than for the expected/weighted utility models, including bilinear models. (C) 2000 Elsevier Science B.V. All rights reserved. PsycINFO classification: 2340; 3650. C1 Polish Acad Sci, Inst Psychol, Warsaw, Poland. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Sokolowska, J (reprint author), 2070 Sand Hill Rd, Menlo Park, CA 94025 USA. OI Sokolowska, Joanna/0000-0001-5239-1435 NR 63 TC 10 Z9 10 U1 3 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0001-6918 J9 ACTA PSYCHOL JI Acta Psychol. PD JUN PY 2000 VL 104 IS 3 BP 339 EP 369 DI 10.1016/S0001-6918(00)00036-6 PG 31 WC Psychology, Experimental SC Psychology GA 328VR UT WOS:000087872000005 PM 10900700 ER PT J AU Effinger, MR Genge, GG Kiser, JD AF Effinger, MR Genge, GG Kiser, JD TI Ceramic composite - Turbine disks for rocket engines SO ADVANCED MATERIALS & PROCESSES LA English DT Article AB Results of this study indicate that the benefits of ceramic matrix composites include the ability to withstand damage, provide increased damping capacity, and reduce weight, all of which create a more robust rocket engine. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NASA, Glen Res Ctr, Cleveland, OH USA. RP Effinger, MR (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 0 TC 5 Z9 5 U1 0 U2 1 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 USA SN 0882-7958 J9 ADV MATER PROCESS JI Adv. Mater. Process. PD JUN PY 2000 VL 157 IS 6 BP 69 EP 73 PG 5 WC Materials Science, Multidisciplinary SC Materials Science GA 323KA UT WOS:000087563500005 ER PT J AU Long, D AF Long, D TI The AIPS-98 planning competition SO AI MAGAZINE LA English DT Article AB In 1998, the international planning community was invited to take part in the first planning competition, hosted by the Artificial Intelligence Planning Systems Conference, to provide a new impetus for empirical evaluation and direct comparison of automatic domain-independent planning systems. This article describes the systems that competed in the event, examines the results, and considers some of the implications for the future of the field. C1 Univ Durham, Durham DH1 3HP, England. Univ Washington, Dept Comp Sci & Engn, Seattle, WA 98195 USA. Cornell Univ, Ithaca, NY 14853 USA. Univ Simon Bolivar, Caracas 1080, Venezuela. Univ Freiburg, D-7800 Freiburg, Germany. NASA, Ames Res Ctr, Computat Sci Div, Moffett Field, CA 94035 USA. RP Long, D (reprint author), Univ Durham, Durham DH1 3HP, England. EM D.P.Long@dur.ac.uk NR 33 TC 13 Z9 14 U1 0 U2 0 PU AMER ASSOC ARTIFICIAL INTELL PI MENLO PK PA 445 BURGESS DRIVE, MENLO PK, CA 94025-3496 USA SN 0738-4602 J9 AI MAG JI AI Mag. PD SUM PY 2000 VL 21 IS 2 BP 13 EP 33 PG 21 WC Computer Science, Artificial Intelligence SC Computer Science GA 326VQ UT WOS:000087758000001 ER PT J AU Liu, TS Cattafesta, LN Radeztsky, RH Burner, AW AF Liu, TS Cattafesta, LN Radeztsky, RH Burner, AW TI Photogrammetry applied to wind-tunnel testing SO AIAA JOURNAL LA English DT Article ID CALIBRATION AB In image-based measurements, quantitative image data must be mapped to three-dimensional object space, Analytical photogrammetric methods, which mag be used to accomplish tl,is task, are discussed from the viewpoint of experimental fluid dynamicists. The direct linear transformation (DLT) for camera calibration, used in pressure-sensitive paint, is summarized, An optimization method for camera calibration is developed that can he used to determine the camera calibration parameters, including those describing lens distortion, from a single image. Combined with the DLT method, this method allows a rapid and comprehensive in situ camera calibration and, therefore, is particularly useful for quantitative flow visualization and other measurements such as model attitude and deformation in production wind tunnels. Also included is a brief description of typical photogrammetric applications to temperature- and pressure-sensitive paint measurements and model deformation measurements in wind tunnels. C1 High Technol Corp, Hampton, VA 23666 USA. NASA, Langley Res Ctr, Model Syst Branch, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Instrumentat Syst Dev Branch, Hampton, VA 23681 USA. RP Liu, TS (reprint author), NASA, Langley Res Ctr, Model Syst Branch, Mail Stop 238, Hampton, VA 23681 USA. RI Cattafesta, Louis/A-9545-2015 OI Cattafesta, Louis/0000-0002-5767-3383 NR 25 TC 43 Z9 49 U1 1 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 JUN PY 2000 VL 38 IS 6 BP 964 EP 971 DI 10.2514/2.1079 PG 8 WC Engineering, Aerospace SC Engineering GA 320WP UT WOS:000087424100003 ER PT J AU Maestrello, L AF Maestrello, L TI Control of shock loading from a jet in a flexible structure's presence SO AIAA JOURNAL LA English DT Article ID STRANGE ATTRACTORS; SUPERSONIC JETS; BOUNDARY-LAYER; CHAOS; SOUND AB The control of shock noise or screech from a jet near a flexible structure is discussed. The pressure from the supersonic jet consists of a shock with spiral and flapping nonaxisymmetric modes superimposed on broadband response. This shock induces a nonlinear-nonstationary loading problem associated with acoustic wave generation and propagation coupled with structural vibration. Control of the shock is achieved by placing a ring at the nuzzle lip oscillating at the shock fundamental frequency. The ring prevents the shock characteristics originating In the column of the shear layer from sustaining connection with the out-of-phase surface vibration. Shock-free flow is maintained over a large pressure ratio. The peak power spectral density of the pressure due to shock fundamental and harmonics is converted to broadband level. The experiment is motivated by consideration of aircraft structural fatigue and interior noise. C1 NASA, Langley Res Ctr, Struct Acoust Branch, Fluid Mech & Acoust Div, Hampton, VA 23681 USA. RP Maestrello, L (reprint author), NASA, Langley Res Ctr, Struct Acoust Branch, Fluid Mech & Acoust Div, Mail Stop 463, Hampton, VA 23681 USA. NR 23 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 2000 VL 38 IS 6 BP 972 EP 977 DI 10.2514/2.1080 PG 6 WC Engineering, Aerospace SC Engineering GA 320WP UT WOS:000087424100004 ER PT J AU Johnson, DP Morton, J Kellas, S Jackson, KE AF Johnson, DP Morton, J Kellas, S Jackson, KE TI Size effects in scaled fiber composites under four-point flexure loading SO AIAA JOURNAL LA English DT Article AB The effect of specimen size on the four-point flexural response of ply-level and sublaminate-level scaled composites was investigated. Two laminates were studied, namely, [+45/-45/+45/-45], and [+45/-45/0/90](x). The material system used was AS4/3502 graphite/epoxy. Enhanced x-ray radiography and edge photomicroscopy were used to examine damage development in specimens loaded to various fractions of their ultimate load. This nondestructive examination was coupled with observations of the load/deflection response to try to correlate scaling effects with the damage development in the specimens. Results were compared to previous studies involving tensile scaling effects. It was found that the strength of ply-level scaled laminates decreased as specimen size increased, and that this effect was modeled well using the typical fracture mechanics scaling law. Sublaminate-level scaled specimens did not show a pronounced scaling effect. Although there seemed to be a slight decrease in strength with increased specimen size, the effect was small and may not be statistically significant. C1 Mississippi State Univ, Dept Aerosp Engn, Mississippi State, MS 39762 USA. Royal Aerosp Estab, Def Res Agcy, Struct Mat Ctr, Farnborough GU14 6TD, Hants, England. Lockheed Engn & Sci Co, NASA, Langley Res Ctr, Hampton, VA 23681 USA. USA, Res Lab, Vehicle Technol Ctr, NASA,Langley Res Ctr, Hampton, VA 23681 USA. RP Johnson, DP (reprint author), Mississippi State Univ, Dept Aerosp Engn, Mail Stop 9549, Mississippi State, MS 39762 USA. NR 15 TC 7 Z9 7 U1 0 U2 6 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 JUN PY 2000 VL 38 IS 6 BP 1047 EP 1054 DI 10.2514/2.1066 PG 8 WC Engineering, Aerospace SC Engineering GA 320WP UT WOS:000087424100013 ER PT J AU Mack, WJ Xiang, M Selzer, RH Hodis, HN AF Mack, WJ Xiang, M Selzer, RH Hodis, HN TI Serial quantitative coronary angiography and coronary events SO AMERICAN HEART JOURNAL LA English DT Article ID COLESTIPOL-NIACIN THERAPY; ATHEROSCLEROSIS; PROGRESSION; DISEASE AB Background Although assessment of progression of atherosclerosis by quantitative coronary angiography (QCA) is used as a surrogate for coronary events, no validation study has compared the several QCA measures used. Methods and Results The Cholesterol Lowering Atherosclerosis Study was a clinico trial testing the efficacy of colestipol-niacin on the progression of coronary atherosclerosis. Baseline/2-year coronary angiograms were obtained on 156 men with prior coronary artery bypass graft surgery. Changes in percent diameter stenosis and minimum lumen diameter (both measured in coronary lesions and segments) and coronary segment measures of average diameter, percent involvement, and vessel edge roughness were measured by QCA. Coronary events ascertained over 12 years of follow-up included myocardial infarction (MI), coronary death, and coronary artery revascularizations. Proportional hazards models evaluated the relation between QCA change measures and coronary events. Changes in percent diameter stenosis and minimum lumen diameter of coronary artery lesions were significantly related to the risk of MJ/coronary death. All QCA measures were significantly related to the risk of any coronary event. Relative risks for each QCA measure were of similar magnitude when estimated separately within each treatment group. Change in minimum lumen diameter of lesions was the only measure independently associated with the risk of coronary events. Conclusions ail oca measures of progression of coronary artery disease were related to all coronary events (including revascularizations). Only QCA measures of lesion progression were related to MI/coronary death. QCA measures of lesion change may be better surrogate end points for "hard" coronary events than measures of change in coronary segments. C1 Univ So Calif, Dept Prevent Med, Los Angeles, CA 90089 USA. Univ So Calif, Dept Med, Atherosclerosis Res Unit, Div Cardiol, Los Angeles, CA 90089 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Mack, WJ (reprint author), Univ So Calif, Dept Prevent Med, 1540 Alcozar,CHP-218, Los Angeles, CA 90089 USA. FU NHLBI NIH HHS [R03-HL54532] NR 9 TC 27 Z9 28 U1 0 U2 0 PU MOSBY-YEAR BOOK INC PI ST LOUIS PA 11830 WESTLINE INDUSTRIAL DR, ST LOUIS, MO 63146-3318 USA SN 0002-8703 J9 AM HEART J JI Am. Heart J. PD JUN PY 2000 VL 139 IS 6 BP 993 EP 999 DI 10.1067/mhj.2000.105702 PG 7 WC Cardiac & Cardiovascular Systems SC Cardiovascular System & Cardiology GA 321RC UT WOS:000087467600011 PM 10827379 ER PT J AU Doran, PT Wharton, RA Lyons, WB Des Marais, DJ Andersen, DT AF Doran, PT Wharton, RA Lyons, WB Des Marais, DJ Andersen, DT TI Sedimentology and geochemistry of a perennially ice-covered epishelf lake in Bunger Hills Oasis, East Antarctica SO ANTARCTIC SCIENCE LA English DT Article DE Antarctic; geochemistry; isotopes; lake; radiocarbon; sedimentology ID MCMURDO DRY VALLEYS; HOARE; SEDIMENTATION; DEGLACIATION; LIFE; SNOW AB A process-oriented study was carried out in White Smoke lake, Bunger Hills, East Antarctica, a perennially ice-covered (1.8 to 2.8 m thick) epishelf (tidally-forced) lake. The lake water has a low conductivity and is relatively well mixed. Sediments are transferred from the adjacent glacier to the lake when glacier ice surrounding the sediment is sublimated at the surface and replaced by accumulating ice from below. The lake bottom at the west end of the lake is mostly rocky with a scant sediment cover. The east end contains a thick sediment profile. Grain size and delta(13)C increase with sediment depth, indicating a more proximal glacier ill the past. Sedimentary Pb-210 and Cs-137 signals are exceptionally strong, probably a result of the focusing effect of the large glacial catchment area. The post-bomb and pre-bomb radiocarbon reservoirs are c. 725 C-14 yr and c. 1950 C-14 yr, respectively. Radiocarbon dating indicates that the east end of the lake is >3 ka sp, while photographic evidence and the absence of sediment cover indicate that the west end has formed only over the last century. Our results indicate that the southern ice edge of Bunger Hills has been relatively stable with only minor fluctuations (on the scale of hundreds of metres) over the last 3000 years. C1 Univ Illinois, Chicago, IL 60607 USA. Univ Nevada, Desert Res Inst, Ctr Biol Sci, Reno, NV 89506 USA. Univ Alabama, Dept Geol, Tuscaloosa, AL 35487 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Doran, PT (reprint author), Univ Illinois, 845 W Taylor St, Chicago, IL 60607 USA. NR 34 TC 21 Z9 23 U1 0 U2 2 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 USA SN 0954-1020 J9 ANTARCT SCI JI Antarct. Sci. PD JUN PY 2000 VL 12 IS 2 BP 131 EP 140 PG 10 WC Environmental Sciences; Geography, Physical; Geosciences, Multidisciplinary SC Environmental Sciences & Ecology; Physical Geography; Geology GA 327CL UT WOS:000087775400002 PM 11543521 ER PT J AU Larruquert, JI Keski-Kuha, RAM AF Larruquert, JI Keski-Kuha, RAM TI Reflectance measurements and optical constants in the extreme ultraviolet for thin films of ion-beam-deposited SIC, Mo, Mg2Si, and InSb and of evaporated Cr SO APPLIED OPTICS LA English DT Article ID SILICON-CARBIDE; EUV REFLECTANCE; COATINGS; TA AB Reflectance measurements and optical constants of thin films of ion-beam-deposited SiC, Mo, Mg,Si, and InSb and of evaporated Or have been measured in the extreme-ultraviolet (EUV) spectral region from 49.0 to 200.0 nm. In this spectral region no optical constant data were available for materials deposited by ion-beam deposition. We compared our data with those far bulk samples and for thin films prepared by different techniques. The goal of this research has been to study candidate materials far multilayer coatings in the EUV. (C) 2000 Optical Society of America OCIS codes: 120.4530, 120.5700, 230.0310, 260.7210, 260.7200, 310.1620. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Larruquert, JI (reprint author), CSIC, Inst Fis Aplicada, C Serrano 144, E-28006 Madrid, Spain. EM larruquert@io.csic.es OI Larruquert, Juan/0000-0001-6356-9702 NR 30 TC 23 Z9 24 U1 0 U2 6 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 JUN 1 PY 2000 VL 39 IS 16 BP 2772 EP 2781 DI 10.1364/AO.39.002772 PG 10 WC Optics SC Optics GA 318XZ UT WOS:000087311100035 PM 18345201 ER PT J AU Hegner, SJ Mc Kevitt, P Norvig, P Wilensky, R AF Hegner, SJ Mc Kevitt, P Norvig, P Wilensky, R TI Intelligent help systems for UNIX: Planning and knowledge representation SO ARTIFICIAL INTELLIGENCE REVIEW LA English DT Editorial Material C1 Umea Univ, S-90187 Umea, Sweden. Univ Ulster, Coleraine BT52 1SA, Londonderry, North Ireland. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Berkeley, Berkeley, CA 94720 USA. RP Hegner, SJ (reprint author), Umea Univ, S-90187 Umea, Sweden. NR 4 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0269-2821 J9 ARTIF INTELL REV JI Artif. Intell. Rev. PD JUN PY 2000 VL 14 IS 3 BP 149 EP 152 DI 10.1023/A:1006715520815 PG 4 WC Computer Science, Artificial Intelligence SC Computer Science GA 380DA UT WOS:000165682100001 ER PT J AU Gardner, JP Satyapal, S AF Gardner, JP Satyapal, S TI Counts and sizes of galaxies in the Hubble Deep Field South: Implications for the Next Generation Space Telescope SO ASTRONOMICAL JOURNAL LA English DT Article DE cosmology : observations; galaxies : evolution; galaxies : statistics; instrumentation : spectrographs; space vehicles : instrumentation ID DATA REDUCTION; CLASSIFICATION; SPECTROMETER; PHOTOMETRY AB Science objectives for the Next Generation Space Telescope (NGST) include a large component of galaxy surveys, both imaging and spectroscopy. The Hubble Deep Field data sets include the deepest observations ever made in the ultraviolet, optical, and near-infrared, reaching depths comparable to that expected for NGST spectroscopy. We present the source counts, galaxy sizes, and isophotal filling factors of the Hubble Deep Field South (HDF-S) images. The observed integrated galaxy counts reach over 500 galaxies per square arcminute at magnitudes AB < 30. We extend these counts to fainter levels and further into the infrared using galaxy-count models. It was determined from the HDF (North) and other deep Wide Field Planetary Camera 2 imaging that fainter galaxies are smaller. This trend continues to AB = 29 in the high-resolution HDF-S Space Telescope Imaging Spectrograph (STIS) image, where galaxies have a typical half-light radius of 0 ".1. We have run extensive Monte Carlo simulations of the galaxy detection in the HDF-S, and we show that the small measured sizes are not due to selection effects until AB > 29. We compare observed sizes in the optical and near-infrared using the HDF-S Near Infrared Camera and Multi-Object Spectrometer image, showing that after taking into account the different point-spread functions and pixel sizes of the images, galaxies are smaller in the near-infrared than they are in the optical. We analyze the isophotal filling factor of the HDF-S STIS image and show that this image is mostly empty sky even at the limits of galaxy detection, a conclusion we expect to hold true for NGST spectroscopy. At the surface brightness limits expected for NGST imaging, however, about a quarter of the sky is occupied by the outer isophotes of AB < 30 galaxies, requiring deblending to detect the faintest objects. We discuss the implications of these data on several design concepts for the NGST near-infrared spectrography. We compare the effects of resolution and the confusion limit of various designs, as well as the multiplexing advantages of either multiobject or full-field spectroscopy. We argue that the optimal choice for NGST spectroscopy of high-redshift galaxies is a multiobject spectrograph (MOS) with target selection by a microelectromechanical systems (MEMS) device. If this technology does not become available in the next few years, then the second choice would be either a mechanical MOS using movable slits or fibers, or an integral field spectrograph. C1 Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. RP Gardner, JP (reprint author), Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. NR 40 TC 12 Z9 12 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 2000 VL 119 IS 6 BP 2589 EP 2597 DI 10.1086/301368 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335ET UT WOS:000088231100006 ER PT J AU Hunter, TR Churchwell, E Watson, C Cox, P Benford, DJ Roelfsema, PR AF Hunter, TR Churchwell, E Watson, C Cox, P Benford, DJ Roelfsema, PR TI 350 micron images of massive star formation regions SO ASTRONOMICAL JOURNAL LA English DT Article DE H Pi regions; infrared radiation; stars : formation ID H-II REGIONS; DUST TEMPERATURE DISTRIBUTIONS; ANGULAR-RESOLUTION CAMERA; ULTRACOMPACT HII-REGIONS; H2O MASER SOURCES; METHANOL MASERS; GALACTIC-CENTER; CONTINUUM OBSERVATIONS; VLA OBSERVATIONS; RADIO-SOURCES AB We present 350 mu m continuum images of 24 massive star formation regions obtained with the Caltech Submillimeter Observatory equipped with the SHARC focal-plane array. At this wavelength the spatial resolution is 11 ". The 350 mu m emission is compared with thermal radio continuum emission and OH, H2O, and CH3OH masers. Emission at 350 mu m is believed to be thermal emission from dust heated by embedded or nearby stars. Compact radio continuum sources are usually present in the mapped 350 mu m fields, and more than 60% of the 350 mu m peaks coincide with radio continuum peaks. This association lends strong support to the notion that the dust is heated primarily by hot stars. Masers are also a common property of massive star formation regions. Usually OH, H2O, and/or CH3OH masers are found near, but generally not coincident with, the 350 mu m peaks. Less than 25% of the 350 Irm peaks have no reported masers located close by. In most of the observed regions, the 350 mu m dust maps show one or more components surrounded by fainter extended emission. In total, we identify 28 separate 350 mu m components. Ten of the 28 components do not have radio continuum counterparts. These are luminous sources and should produce detectable H II regions. It is postulated that these sources may be undergoing such rapid accretion that the infalling matter quenches the H II region very close to the protostar, thereby making the H II region undetectable in free-free emission. Objects in this evolutionary state may well represent the long-sought precursors to ultracompact H II regions and should have the properties of accreting massive protostars (e.g., accretion disks, bipolar molecular outflows, hot shocked gas, infall with spin-up toward the protostar). We suggest that the 10 sources in this category in our sample merit further observational study for these properties. Two-temperature graybody models constrained by the observed infrared spectral energy distributions were calculated to estimate the total mass, luminosity, average dust temperature, and hydrogen column and number densities for each source. The graybody models do not account for possible low-level emission from the coolest dust (<25 K) and therefore may underestimate the total mass. There is, however, no evidence for emission in excess of the models at 1.3 mm, and we conclude that the mass contribution of dust colder than similar to 25 K cannot be large. Thus, the graybody models shown provide useful average global properties required to understand massive star formation environments. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Wisconsin, Dept Astron, Washburn Observ, Madison, WI 53706 USA. Univ Paris 11, Inst Astrophys Spatiale, F-91405 Orsay, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Space Res Org Netherlands, NL-9700 AV Groningen, Netherlands. RP Hunter, TR (reprint author), Harvard Smithsonian Ctr Astrophys, MS-78,60 Garden St, Cambridge, MA 02138 USA. RI Benford, Dominic/D-4760-2012 OI Benford, Dominic/0000-0002-9884-4206 NR 48 TC 60 Z9 60 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 2000 VL 119 IS 6 BP 2711 EP 2727 DI 10.1086/301391 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335ET UT WOS:000088231100015 ER PT J AU Matt, G de Martino, D Gansicke, BT Negueruela, I Silvotti, R Bonnet-Bidaud, JM Mouchet, M Mukai, K AF Matt, G de Martino, D Gansicke, BT Negueruela, I Silvotti, R Bonnet-Bidaud, JM Mouchet, M Mukai, K TI BeppoSAX observations of AM Herculis in intermediate and high states SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : binaries : close; stars : novae; cataclysmic variables; X-rays : stars; stars : individual : Am Herculis ID X-RAY SPECTROSCOPY; WHITE-DWARF; BINARIES; EMISSION; POLE AB Temporal and spectral analyses from BeppoSAX observations of AM Her performed during both an intermediate and a high stare are presented and discussed. Optical observations taken a few days after the X-ray ones are also presented. During the intermediate state observation, the source was in its "normal", one-pole accretion mode. In the high state it switched to an hitherto unobserved atypical "two-pole" accretion mode, with significant soft and hard X-ray emission from both poles. The emission from the second pole is much softer than that from the primary pole, while the soft X-ray excess of the primary pole is fairly modest in this accretion mode. These facts suggest that accretion onto the secondary is mainly due to blobs penetrating deeply in the photosphere, while that on the primary pole is mostly via a more homogeneous column, giving rise to the classical standing shock. A strong X-ray flaring activity is also observed in the soft X-ray band, but not in the hard X-ray and optical emissions indicating that flares are due to inhomogeneous blobby-accretion events. C1 Univ Roma Tre, Dipartimento Fis, I-00146 Rome, Italy. Osservatorio Astron Capodimonte, I-80131 Naples, Italy. Univ Sternwarte Gottingen, D-37083 Gottingen, Germany. SAX SDC Nuova Telepazio, I-00131 Rome, Italy. CEN Saclay, CEA, DSN, DAPNIA,Serv Astrophys, F-91191 Gif Sur Yvette, France. Observ Paris, DAEC, Sect Meudon, F-92195 Meudon, France. Univ Denis Diderot, F-75005 Paris, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Matt, G (reprint author), Univ Roma Tre, Dipartimento Fis, Via Vasca Navale 84, I-00146 Rome, Italy. EM matt@fis.uniroma3.it RI Gaensicke, Boris/A-9421-2012; Negueruela, Ignacio/L-5483-2014 OI Gaensicke, Boris/0000-0002-2761-3005; Negueruela, Ignacio/0000-0003-1952-3680 NR 26 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 JUN PY 2000 VL 358 IS 1 BP 177 EP 186 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 333VK UT WOS:000088151300024 ER PT J AU Schmieder, B Delannee, C Yong, DY Vial, JC Madjarska, M AF Schmieder, B Delannee, C Yong, DY Vial, JC Madjarska, M TI Multi-wavelength study of the slow "disparition brusque" of a filament observed with SOHO SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE Sun : activity; Sun : chromosphere; Sun : corona; Sun : filaments ID CORONAL MASS EJECTIONS; SOLAR; LASCO; EIT; SPECTROMETER; PROMINENCES; TELESCOPE; MODEL AB A mid-latitude filament was observed before and after its eruption with SOHO (EIT, SUMER, CDS and LASCO) and with ground based observatories (Meudon and Pic du Midi) in the context of a coordinated MEDOC campaign in Orsay. The eruption was followed by a large Coronal Mass Ejection well observed by LASCO. Few hours before its eruption, the filament is partially heated las seen in 195 Angstrom with EIT). The physical conditions of the filament before its eruption have been investigated by spectroscopic analysis of SUMER (the Lyman series L4 to L9) and of CDS combined with the Multi-channel Subtractive Double Pass Spectrograph (MSDP) spectra of H alpha. Five hours before the eruption, large broadenings of chromospheric and transition region lines (CDS) were observed in the main body of the filament suggesting strong turbulence as well as opposite Dopplershifts on each side of the filament (H alpha and He I) which could be interpreted as twist motions. The optical thickness of the filament is rather large. During the eruption the twist is largely developed as observed in 304 Angstrom. The Doppler shifts of the filament estimated from Lyman lines are in good agreement with the velocity of the front edge of the CME bright loop. We notice that both, the filament and the bright loop, are deviated towards the equator. This implies that they belong to the same global expansion event constrained to remain in the equatorial streamer. An X-ray bright point observed close to a filament footpoint could be the signature of reconnection process linked to the destabilization of the filament. It is interpreted in the framework of new MHD modeling of lateral filament footpoints (Aulanier & Demoulin 1998). C1 Observ Paris, Sect Meudon, F-92195 Meudon, France. Univ Oslo, Inst Astrophys, Blindern, Norway. NASA, Goddard Space Flight Ctr, SOHO EAF, Greenbelt, MD 20771 USA. Chinese Acad Sci, Natl Astron Observ, Beijing Astron Observ, Beijing 100012, Peoples R China. Univ Paris 11, Inst Astrophys Spatiale, CNRS, F-91405 Orsay, France. Inst Astron, Sofia 1784, Bulgaria. Armagh Observ, Armagh BT61 9DG, North Ireland. RP Schmieder, B (reprint author), Observ Paris, Sect Meudon, LPSH 2080, F-92195 Meudon, France. EM Schmieder@mesioa.obspm.fr NR 22 TC 34 Z9 34 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUN PY 2000 VL 358 IS 2 BP 728 EP 740 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 334JE UT WOS:000088182700046 ER PT J AU van den Ancker, ME Tielens, AGGM Wesselius, PR AF van den Ancker, ME Tielens, AGGM Wesselius, PR TI ISO Spectroscopy of the young bipolar nebulae S106IR and Cep A East SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE shock waves; stars : circumstellar matter; stars : formation; ISM : HII regions; ISM : jets and outflows; infrared : stars ID INTERSTELLAR MOLECULAR-HYDROGEN; STAR-FORMING REGION; CEPHEUS-A; PHOTODISSOCIATION REGIONS; INFRARED OBSERVATIONS; WAVELENGTH SPECTROMETER; LABORATORY SIMULATIONS; LINE EMISSION; STELLAR WIND; FEATURES AB We present the results of ISO SWS and LWS grating scans towards the embedded Young Stellar Objects (YSOs) S106 IR and Cep A East. Emission from the pure rotational lines of H(2) and the infrared fine structure lines of [C II], [O I], [S I], [Si II] and [Fe II], as well as absorption bands due to H(2)O, CO and CO(2) ice were detected toward Cep A. In S106 we detected emission lines of H(2), CO, H I, and a large number of ionized species including Fe, O, N, C, Si, S, Ne and Ar. S106 also shows many of the infrared PAH bands in emission. Excitation temperatures and molecular hydrogen masses were derived from the low-lying pure rotational levels of Hz and are 500 and 730 K and 8 and 3 x 10(-3) M(.) for S106 and Cep A, respectively. Since both objects are expected to have several solar masses of H(2) in their environment, we conclude that in both cases the bulk of the H(2) is cooler than a few hundred Kelvins. Excitation temperatures and line ratios were compared with those predicted by theoretical models for PDRs and dissociative and non-dissociative shocks. The [S I] 25.2 mu m/[Si II] 34.8 mu m ratio is a particularly useful shock versus PDR discriminant and we conclude that S106 IR is dominated by PDR emission while Cep A East has a large shock component. From an analysis of the ionic lines in S106 we conclude that the central star must have a temperature around 37,000 K, corresponding to a spectral type of O8. From its luminosity it is concluded that the driving source of Cep A must also be a massive early-type star. The absence of strong high-ionization ionic lines in its ISO spectrum shows that Cep A has not yet created a significant H Ir region and must be younger than S106, illustrating the process of the clearing of the surroundings of a massive young star. C1 Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Groningen, Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands. SRON, NL-9700 AV Groningen, Netherlands. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP van den Ancker, ME (reprint author), Univ Amsterdam, Astron Inst Anton Pannekoek, Kruislaan 403, NL-1098 SJ Amsterdam, Netherlands. EM mario@astro.uva.nl NR 69 TC 51 Z9 51 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUN PY 2000 VL 358 IS 3 BP 1035 EP 1048 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 338MQ UT WOS:000088424200029 ER PT J AU Mathys, G Stehle, C Brillant, S Lanz, T AF Mathys, G Stehle, C Brillant, S Lanz, T TI The physical foundations of stellar magnetic field diagnosis from polarimetric observations of hydrogen lines SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE line : formation; polarization; radiative transfer; stars : atmospheres; stars : magnetic fields ID PROFILE; STARS AB We have completed a new study of the formation of hydrogen lines in dense magnetized plasmas. We have developed a global formalism including the effects of the magnetic field and of the motional electric field. The latter, resulting from the motion of the radiating hydrogen atom in the magnetic field, modifies the structure of the matrices appearing in the equation of transfer of the Stokes vector and introduces a coupling between microscopic ("intrinsic") and macroscopic (Doppler) contributions to the line profiles. We have used this new treat ment of line formation to revisit the interpretation of photopolarimetric (Stokes I and V) observations of Balmer lines in terms of mean longitudinal magnetic field. C1 Observ Paris, DASGAL, F-92195 Meudon, France. European So Observ, Santiago 19, Chile. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Stehle, C (reprint author), Observ Paris, DASGAL, 5 Pl J Janssen, F-92195 Meudon, France. NR 19 TC 17 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 JUN PY 2000 VL 358 IS 3 BP 1151 EP 1156 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 338MQ UT WOS:000088424200040 ER PT J AU Egami, E Neugebauer, G Soifer, BT Matthews, K Ressler, M Becklin, EE Murphy, TW Dale, DA AF Egami, E Neugebauer, G Soifer, BT Matthews, K Ressler, M Becklin, EE Murphy, TW Dale, DA TI APM 08279+5255: Keck near- and mid-infrared high-resolution imaging SO ASTROPHYSICAL JOURNAL LA English DT Article DE gravitational lensing; infrared : galaxies; quasars : individual (APM 08279+5255) ID SPECTRAL ENERGY-DISTRIBUTIONS; HIGH-REDSHIFT OBJECTS; GRAVITATIONAL LENSES; HIRES SPECTROSCOPY; GALAXIES; QUASAR; TELESCOPE; APM-08279+5255; SUBMILLIMETER; CLOVERLEAF AB We present Keck high-resolution near-IR (2.2 mu m; FWHM similar to 0."15) and mid-IR (12.5 mu m; FWHM similar to 0."4) images of APM 08279 + 5255, a z = 3.91 IR-luminous broad absorption line quasi-stellar object with a prodigious apparent bolometric luminosity of 5 x 10(15) L., the largest known in the universe. The K-band image shows that this system consists of three components, all of which are likely to be the gravitationally lensed images of the same background object, and the 12.5 mu m image shows a morphology consistent with such an image configuration. Our lens model suggests that the magnification factor is similar to 100 from the rest-frame UV to mid-IR, where most of the luminosity is released. The intrinsic bolometric luminosity and IR luminosity of APM 08279 + 5255 are estimated to be 5 x 10(13) L. and 1 x 10(13) L., respectively. This indicates that APM 08279 + 5255 is intrinsically luminous, but it is not the most luminous object known. As for its dust contents, little can be determined with the currently available data because of the uncertainties associated with the dust emissivity and the possible effect of differential magnification. We also suggest that the lensing galaxy is likely to be a massive galaxy at z similar to 3. C1 CALTECH, Palomar Observ, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. CALTECH, IPAC, Pasadena, CA 91125 USA. RP CALTECH, Palomar Observ, 320-47, Pasadena, CA 91125 USA. EM egami@monk.caltech.edu; gxn@mop.caltech.edu; bts@mop.caltech.edu; kym@mop.caltech.edu; ressler@cougar.jpl.nasa.gov; becklin@astro.ucla.edu; tmurphy@mop.caltech.edu; dad@ipac.caltech.edu NR 35 TC 52 Z9 53 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 2000 VL 535 IS 2 BP 561 EP 574 DI 10.1086/308862 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327HY UT WOS:000087789500004 ER PT J AU Makishima, K Kubota, A Mizuno, T Ohnishi, T Tashiro, M Aruga, Y Asai, K Dotani, T Mitsuda, K Ueda, Y Uno, S Yamaoka, K Ebisawa, K Kohmura, Y Okada, K AF Makishima, K Kubota, A Mizuno, T Ohnishi, T Tashiro, M Aruga, Y Asai, K Dotani, T Mitsuda, K Ueda, Y Uno, S Yamaoka, K Ebisawa, K Kohmura, Y Okada, K TI The nature of ultraluminous compact X-ray sources in nearby spiral galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE black hole physics; galaxies : spiral; x-rays : galaxies ID RELATIVISTIC ACCRETION DISK; GAS IMAGING SPECTROMETER; SOURCE GRO J1655-40; BLACK-HOLE; LMC X-3; SUPERLUMINAL SOURCE; OPTICAL OBSERVATIONS; ASCA OBSERVATIONS; BINARY-SYSTEMS; MASS AB Studies were made of ASCA spectra of seven ultraluminous compact X-ray sources in nearby spiral galaxies: M33 X-8, M81 X-6, IC 342 source 1, Dwingeloo 1 X-1, NGC 1313 source B, and two sources in NGC 4565. With the 0.5-10 keV luminosities in the range 10(39)-10(40) ergs s(-1), they are thought to represent a class of enigmatic X-ray sources often found in spiral galaxies. For some of them, the ASCA data are newly processed or the published spectra are reanalyzed. For others, the published results are quoted. The ASCA spectra of all seven sources have been described successfully with so-called multicolor disk blackbody emission arising from optically thick standard accretion disks around black holes. Except for the case of M33 X-8, the spectra do not exhibit hard tails. For the source luminosities not to exceed the Eddington limits, the black holes are inferred to have rather high masses, up to similar to 100 M.. However, the observed innermost disk temperatures of these objects, T-in = 1.1-1.8 keV, are too high to be compatible with the required high black hole masses, as long as the standard accretion disks around Schwarzschild black holes are assumed. Similarly high disk temperatures are also observed from two Galactic transients with superluminal motions, GRO 1655-40 and GRS 1915 + 105. The issue of unusually high disk temperature may be explained by the black hole rotation, which makes the disk get closer to the black hole and hence hotter. C1 Univ Tokyo, Dept Phys, Bunkyo Ku, Tokyo 1130033, Japan. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Inst Phys & Chem Res, Harima Inst, Mikazuki, Hyogo 6795148, Japan. RP Makishima, K (reprint author), Univ Tokyo, Dept Phys, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1130033, Japan. RI Mitsuda, Kazuhisa/C-2649-2008; Tashiro, Makoto/J-4562-2012; Kohmura, Yoshiki/A-9967-2016 OI Kohmura, Yoshiki/0000-0001-5182-063X NR 84 TC 403 Z9 404 U1 1 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 2000 VL 535 IS 2 BP 632 EP 643 DI 10.1086/308868 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327HY UT WOS:000087789500012 ER PT J AU Yost, SA Bock, JJ Kawada, M Lange, AE Matsumoto, T Uemizu, K Watabe, T Wada, T AF Yost, SA Bock, JJ Kawada, M Lange, AE Matsumoto, T Uemizu, K Watabe, T Wada, T TI A search for near-infrared emission from the halo of NGC 5907 at radii of 10-30 kiloparsecs SO ASTROPHYSICAL JOURNAL LA English DT Article DE dark matter; galaxies : halos; galaxies : individual (NGC 5907); stars : low-mass, brown dwarfs ID SPIRAL GALAXY NGC5907; DARK-MATTER; NGC-5907; BAND; ATMOSPHERES; DWARFS; LIGHT AB We present a search for near-infrared (3.5-5 mu m) emission from baryonic dark matter in the form of low-mass stars and/or brown dwarfs in the halo of the nearby edge-on spiral galaxy NGC 5907. The observations were made using a 256 x 256 InSb array with a pixel scale of 17" at the focus of a liquid-helium-cooled telescope carried above the Earth's atmosphere by a sounding rocket. In contrast to previous experiments that have detected a halo around NGC 5907 in the V, R, I, J, and K bands at galactic radii 6 kpc < r < 10 kpc, our search finds no evidence for emission from a halo at 10 kpc < r < 30 kpc. Assuming a halo mass density scaling as r(-2), which is consistent with the flat rotation curves that are observed out to radii of 32 kpc, the lower limit of the mass-to-light ratio at 3.5-5 mu m for the halo of NGC 5907 is 250 (2 sigma) in solar units. This is comparable to the lower limit we have found previously for NGC 4565. Based on recent models, our nondetection implies that hydrogen-burning stars contribute less than 15% of the mass of the dark halo of NGC 5907. Our results are consistent with the previous detection of extended emission at r less than or equal to 10 kpc if the latter is caused by a stellar population that has been ejected from the disk because of tidal interactions. We conclude that the dark halo of NGC 5907, which is evident from rotation curves that extend far beyond 10 kpc, is not made up of hydrogen-burning stars. C1 CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Nagoya Univ, Nagoya, Aichi 4648602, Japan. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. RP Yost, SA (reprint author), CALTECH, Pasadena, CA 91125 USA. NR 27 TC 6 Z9 6 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 2000 VL 535 IS 2 BP 644 EP 649 DI 10.1086/308871 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327HY UT WOS:000087789500013 ER PT J AU Berkley, AJ Kazanas, D Ozik, J AF Berkley, AJ Kazanas, D Ozik, J TI Modeling the X-ray-ultraviolet correlations in NGC 7469 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; galaxies : active; galaxies : individual (NGC 7469)-galaxies : Seyfert; ultraviolet : galaxies; x-rays : galaxies ID ACTIVE GALACTIC NUCLEI; BROAD-LINE REGION; ACCRETION DISKS; QUASARS; CONTINUUM; VARIABILITY; NGC-7469; NGC-5548; EXCESS; STEPS AB We model the correlated X-ray-UV observations of NGC 7469, for which well-sampled data in both these bands have recently been obtained in a multiwavelength monitoring campaign. To this end, we derive the transfer function in wavelength lambda and time lag tau for reprocessing hard (X-ray) photons from a point source to softer ones (UV-optical) by an infiinite plane (representing a cool, thin accretion disk) located at a given distance below the X-ray source, under the assumption that the X-ray flux is absorbed and emitted locally by the disk as a blackbody of temperature appropriate to the incident flux. Using the observed X-ray light curve as input, we have computed the expected continuum UV emission as a function of time at several wavelengths (1315, 6962, 15000, and 30000 Angstrom), assuming that the X-ray source is located one Schwarzschild radius above the disk plane, with the mass of the black hole M and the latitude angle theta of the observer relative to the disk plane as free parameters. We have searched the parameter space of black hole masses and observer azimuthal angles, but we were unable to reproduce UV light curves that would resemble, even remotely, those observed. We also explored whether particular combinations of the values of these parameters could lead to light curves whose statistical properties (i.e., the autocorrelation and cross-correlation functions) would match those corresponding to the observed UV light curve at 1315 Angstrom. Even though we considered black hole masses as large as 10(9) M., no such match was possible. Our results indicate that some of the fundamental assumptions of this model will have to be modified to obtain even approximate agreement between the observed and model X-ray-UV light curves. C1 Univ Maryland, Dept Phys, College Pk, MD 20743 USA. NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Greenbelt, MD 20771 USA. RP Univ Maryland, Dept Phys, College Pk, MD 20743 USA. OI Berkley, Andrew/0000-0002-4235-8452 NR 17 TC 15 Z9 15 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 2000 VL 535 IS 2 BP 712 EP 720 DI 10.1086/308880 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327HY UT WOS:000087789500019 ER PT J AU Nayakshin, S Rappaport, S Melia, F AF Nayakshin, S Rappaport, S Melia, F TI Time-dependent disk models for the microquasar GRS 1915+105 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; black hole physics; quasars : individual (GRS 1915+105); X-rays : general ID QUASI-PERIODIC OSCILLATIONS; X-RAY BINARIES; SLIM ACCRETION DISKS; BLACK-HOLE; SEYFERT-GALAXIES; OBSERVATIONAL APPEARANCE; RXTE OBSERVATIONS; NEUTRON-STARS; CYGNUS X-1; GRS-1915+105 AB During the past three years, the Galactic black hole microquasar GRS 1915+105 has exhibited a bewildering diversity of large-amplitude, chaotic variability in X-rays. Although it is generally accepted that the variability in this source results from an accretion disk instability, the exact nature of the instability remains unknown. Here we investigate different accretion disk models and viscosity prescriptions in order to provide a basic explanation for some of the exotic temporal behavior in GRS 1915+105. We discuss a range of possible accretion flow geometries. Any geometrically thick disk (e.g., an advection-dominated accretion flow [ADAF] or a "slim" accretion disk) has trouble explaining the very long cycle times unless the a-parameter is exceedingly small (similar to 10(-4)). In addition, the rise/fall timescales in GRS 1915+105 can be a factor of 100 shorter than the cycle times, whereas thick disks predict that these two timescales should be comparable. We thus concentrate on geometrically thin (though not necessarily standard) Shakura-Sunyaev type disks. We argue that X-ray observations clearly require a quasi-stable accretion disk solution at a high accretion rate at which radiation pressure begins to dominate, which excludes the standard alpha-viscosity prescription. We have therefore devised a simplified model of a disk with a corona and a modified viscosity law that has a quasi-stable upper branch, and we have developed a code to solve the time-dependent equations to study the evolution of this configuration. Via numerical simulations, we show that the model does account for several gross observational features of GRS 1915+105, including its overall cyclic behavior on timescales of similar to 100-1000 s. On the other hand, the rise/fall timescales are not as short as those observed, no rapid oscillations on timescales less than or similar to 10 s emerge naturally from the model, and the computed cycle-time dependence on the average luminosity is stronger than is found in GRS 1915+105. We then consider, and numerically test, a more elaborate model that includes the "cold" disk, a corona, and plasma ejections from the inner disk region that occur when the luminosity of the source is near the Eddington luminosity. The inclusion of a jet allows us to reproduce several additional observed features of GRS 1915+105. We conclude that the most likely structure of the accretion flow in this source is that of a cold disk with a modified viscosity law, plus a corona that accounts for much of the X-ray emission and unsteady plasma ejections that occur when the luminosity of the source is high. The disk is geometrically thin las required by the data) because most of the accretion power is drained by the corona and the jet. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. MIT, Dept Phys, Cambridge, MA 02139 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. Univ Arizona, Dept Phys, Tucson, AZ 85721 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. RP Nayakshin, S (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. NR 58 TC 75 Z9 75 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 2000 VL 535 IS 2 BP 798 EP 814 DI 10.1086/308860 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327HY UT WOS:000087789500026 ER PT J AU Arnoult, KM Wdowiak, TJ Beegle, LW AF Arnoult, KM Wdowiak, TJ Beegle, LW TI Laboratory investigation of the contribution of complex aromatic/aliphatic polycyclic hybrid molecular structures to interstellar ultraviolet extinction and infrared emission SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; HII regions; infrared : ISM : lines and bands; ISM : molecules; methods : laboratory; molecular processes ID AROMATIC-HYDROCARBONS; AMORPHOUS-CARBON; MICRON EMISSION; EVOLUTION; CARRIER; SPECTRA; GRAINS; DUST; BUMP AB We have demonstrated by experiment that, in an energetic environment, a simple polycyclic aromatic hydrocarbon (PAH) such as naphthalene will undergo chemical reactions that produce a wide array of more complex species tan aggregate). For a stellar wind of a highly evolved star (post-asymptotic giant branch [post-AGB]), this process would be in addition to what is expected from reactions occurring under thermodynamic equilibrium. A surprising result of that work was that produced in substantial abundance are hydrogenated forms that are hybrids of polycyclic aromatic and polycyclic alkanes. Infrared spectroscopy described here reveals a spectral character for these materials that has much in common with that observed for the constituents of circumstellar clouds of post-AGE stars. It can be demonstrated that a methylene (-CH2-) substructure, as in cycloalkanes, is the likely carrier of the 6.9 mu m band emission of dust that has recently been formed around IRAS 22272+5433, NGC 7027, and CPD -56 8032. Ultraviolet spectroscopy previously done with a lower limit of 190 nm had revealed that this molecular aggregate can contribute to the interstellar extinction feature at 2175 Angstrom. We have now extended our UV spectroscopy of these materials to 110 nm by a vacuum ultraviolet technique. That work, described here, reveals new spectral characteristics and describes how material newly formed during the late stages of stellar evolution could have produced an extinction feature claimed to exist at 1700 Angstrom in the spectrum of HD 145502 and also how the newly formed hydrocarbon material would be transformed/aged in the general interstellar environment. The contribution of this molecular aggregate to the rise in interstellar extinction at wavelengths below 1500 Angstrom is also examined. The panspectral measurements of the materials produced in the laboratory, using plasmas of H, He, N, and O to convert the simple PAH naphthalene to an aggregate of complex species, provide insight into possible molecular structure details of newly formed hydrocarbon-rich interstellar dust and its transformation into aged material that becomes resident in the interstellar medium. Specifically the presence of naphthalene-like and butadiene-like conjugated structures as chromophores for the 2175 Angstrom ultraviolet extinction feature is indicated. C1 Univ Alabama, Dept Phys, Astro & Solar Syst Phys Program, Birmingham, AL 35294 USA. Jet Prop Lab, Pasadena, CA 91109 USA. RP Arnoult, KM (reprint author), Univ Alabama, Dept Phys, Astro & Solar Syst Phys Program, Birmingham, AL 35294 USA. RI Beegle, Luther/A-6354-2010 NR 31 TC 11 Z9 11 U1 0 U2 5 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 2000 VL 535 IS 2 BP 815 EP 822 DI 10.1086/308883 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327HY UT WOS:000087789500027 PM 11543517 ER PT J AU Schleuning, DA Vaillancourt, JE Hildebrand, RH Dowell, CD Novak, G Dotson, JL Davidson, JA AF Schleuning, DA Vaillancourt, JE Hildebrand, RH Dowell, CD Novak, G Dotson, JL Davidson, JA TI Probing the magnetic field structure in the W3 molecular cloud SO ASTROPHYSICAL JOURNAL LA English DT Article DE HII regions; infrared : ISM : continuum; ISM : individual (W3); ISM : magnetic fields; polarization; stars : formation ID FAR-INFRARED POLARIZATION; STAR-FORMATION; ARRAY POLARIMETRY; RADIO-CONTINUUM; SAGITTARIUS B2; SUBMILLIMETER; EMISSION; CORES; REGION; MASSES AB This paper presents polarization maps of the central 3' x 5' region of the W3 molecular cloud at far-infrared (60 and 100 mu m) and submillimeter (350 mu m) wavelengths. We use the multiwavelength polarization measurements to differentiate between the emission in warm and cool dust components. We infer that the submillimeter observations trace a layer of cool dust with high column density, which we attribute to a large scale ridge of material. This ambient ridge has an orderly magnetic field with evidence for "hourglass" field structure; however, the field structure is qualitatively different in size and orientation compared to previous studies. The far-infrared measurements are dominated by warm dust surrounding evolved H II regions or embedded young stars. The warm dust, in contrast to the ridge, has a disrupted magnetic field that varies rapidly in the plane of the sky and along the line of sight, suggesting that the field has been distorted by the expansion of H II regions. C1 Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Chicago, Dept Astron, Chicago, IL 60637 USA. Univ Chicago, Dept Phys, Chicago, IL 60637 USA. CALTECH, Pasadena, CA 91125 USA. Northwestern Univ, Dearborn Observ, Evanston, IL 60208 USA. NASA, Ames Res Ctr, SETI, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, USRA, SOFIS, Moffett Field, CA 94035 USA. RP Schleuning, DA (reprint author), Univ Chicago, Enrico Fermi Inst, 5640 S Ellis Ave, Chicago, IL 60637 USA. OI Vaillancourt, John/0000-0001-8916-1828 NR 43 TC 29 Z9 30 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 2000 VL 535 IS 2 BP 913 EP 927 DI 10.1086/308851 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327HY UT WOS:000087789500035 ER PT J AU Leggett, SK Allard, F Dahn, C Hauschildt, PH Kerr, TH Rayner, J AF Leggett, SK Allard, F Dahn, C Hauschildt, PH Kerr, TH Rayner, J TI Spectral energy distributions for disk and halo M dwarfs SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : stars; stars : atmospheres; stars : late-type; stars : low-mass, brown dwarfs ID LOW-MASS STARS; SOLAR NEIGHBORHOOD; MODEL ATMOSPHERES; CM-DRACONIS; METALLICITY; SEQUENCE; COOL AB We have obtained infrared (1-2.5 mu m) spectroscopy for 42 halo and disk dwarfs with spectral types M1-M6.5. These data are compared to synthetic spectra generated by the latest model atmospheres of Allard & Hauschildt. Photospheric parameters metallicity, effective temperature, and radius are determined for the sample. We find good agreement between observation and theory except for known problems due to incomplete molecular data for metal hydrides and H2O. The metal-poor M subdwarfs are well matched by the models, as oxide opacity sources are less important in this case. The derived effective temperatures for the sample range from 3600 to 2600 K; at these temperatures grain formation and extinction are not significant in the photosphere. The derived metallicities range from solar to 1/10 solar. The radii and effective temperatures derived agree well with recent models of low-mass stars. The spectra are available in electronic form upon request. C1 Joint Astron Ctr, Hilo, HI 96720 USA. Ecole Normale Super Lyon, Ctr Rech Astron Lyon, F-69364 Lyon, France. USN Observ, Flagstaff Stn, Flagstaff, AZ 86002 USA. Univ Georgia, Dept Phys & Astron, Athens, GA 30602 USA. Univ Georgia, Ctr Simulat Phys, Athens, GA 30602 USA. NASA, Infrared Telescope Facil, Honolulu, HI 96822 USA. RP Leggett, SK (reprint author), Joint Astron Ctr, 665 Komohana St, Hilo, HI 96720 USA. OI Leggett, Sandy/0000-0002-3681-2989 NR 30 TC 142 Z9 143 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 2000 VL 535 IS 2 BP 965 EP 974 DI 10.1086/308887 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327HY UT WOS:000087789500040 ER PT J AU Blasi, P Olinto, AV Stebbins, A AF Blasi, P Olinto, AV Stebbins, A TI The effect of a nonthermal tail on the Sunyaev-Zeldovich effect in clusters of galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : theory; galaxies : clusters : general ID COMA-CLUSTER; RELATIVISTIC CORRECTIONS; MAGNETIC-FIELD; COSMIC-RAYS; EMISSION AB We study the spectral distortions of the cosmic microwave background radiation induced by the effect in clusters of galaxies when the target electrons have a modified Maxwell-Boltzmann distribution with a high-energy nonthermal tail. Bremsstrahlung radiation from this type of electron distribution may explain the suprathermal X-ray emission observed in some clusters such as the Coma Cluster and A2199 and serve as an alternative to the classical but problematic inverse Compton scattering interpretation. We show that the Sunyaev-Zeldovich effect can be used as a powerful tool to probe the electron distribution in clusters of galaxies and discriminate among these different interpretations of the X-ray excess. The existence of a nonthermal tail can have important consequences for cluster-based estimators of cosmological parameters. C1 NASA, Fermilab Astrophys Grp, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. RP Blasi, P (reprint author), NASA, Fermilab Astrophys Grp, Fermi Natl Accelerator Lab, POB 500, Batavia, IL 60510 USA. RI Blasi, Pasquale/O-9345-2015 OI Blasi, Pasquale/0000-0003-2480-599X NR 21 TC 20 Z9 20 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 2000 VL 535 IS 2 BP L71 EP L74 DI 10.1086/312706 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327JA UT WOS:000087789700001 ER PT J AU Cui, W Shrader, CR Haswell, CA Hynes, RI AF Cui, W Shrader, CR Haswell, CA Hynes, RI TI Discovery of high-frequency quasi-periodic oscillations in the black hole candidate XTE J1859+226 SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : general; relativity; stars : individual (XTE J1859+226); stars : oscillations; X-rays : stars ID X-RAY BINARIES; RXTE OBSERVATIONS; ACCRETION DISKS; GRS-1915+105 AB We report the discovery of quasi-periodic oscillations (QPOs) at roughly 187 and 150 Hz in the X-ray intensity of X-ray nova XTE J1859+226. The source was observed during a recent outburst with the Rossi X-Ray, Timing Explorer. Besides these high-frequency QPOs, we have also detected QPOs (and sometimes their harmonics) at 6-7 Hz and significant broadband variability at low frequencies. These properties, as well as the observed hard X-ray spectrum, make XTE J1859+226 a black hole candidate (BHC). The detection of QPOs at two distinct frequencies greater than or similar to 100 Hz in two observations separated by about 4 hr provide additional insights into the high-frequency QPO phenomenon in BHCs. The importance lies in the proposed interpretations, which invariably involve the effects of strong gravity near a black hole, We compare our results to those of other BHCs and discuss the impact of the observational data on the models in a global context. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. Open Univ, Dept Phys & Astron, Milton Keynes MK7 6AA, Bucks, England. Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. MIT, Ctr Space Res, Cambridge, MA 02139 USA. RP Cui, W (reprint author), Purdue Univ, Dept Phys, W Lafayette, IN 47907 USA. NR 32 TC 39 Z9 40 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 2000 VL 535 IS 2 BP L123 EP L127 DI 10.1086/312712 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327JA UT WOS:000087789700014 ER PT J AU Madejski, G Zycki, P Done, C Valinia, A Blanco, P Rothschild, R Turek, B AF Madejski, G Zycki, P Done, C Valinia, A Blanco, P Rothschild, R Turek, B TI Structure of the circumnuclear region of Seyfert 2 galaxies revealed by Rossi X-ray Timing Explorer hard X-ray observations of NGC 4945 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 4945); galaxies : Seyfert; X-rays : galaxies ID NGC-4945 AB NGC 4945 is one of the brightest Seyfert galaxies on the sky at 100 keV, but is completely absorbed below 10 keV; its absorption column is probably the largest that still allows a direct view of the nucleus at hard X-ray energies. Our observations of it with the Rossi X-Ray Timing Explorer (RXTE) satellite confirm the large absorption, which for a simple phenomenological fit using an absorber with solar abundances implies a column of (4.5(-0.4)(+0.4)) x 10(24) cm(-2). Using a more realistic scenario (requiring Monte Carlo modeling of the scattering), we infer the optical depth to Thomson scattering of similar to 2.4. If such a scattering medium were to subtend a large solid angle from the nucleus, it should smear out any intrinsic hard X-ray variability on timescales shorter than the light-travel time through it. The rapid (with a timescale of similar to 1 day) hard X-ray variability of NGC 4945 discovered by us with RXTE implies that the bulk of the extreme absorption in this object does nor originate in a parsecsize, geometrically thick molecular torus. Instead, the optically thick material on parsec scales must be rather geometrically thin, subtending a half-angle less than 10 degrees, and it is likely to be the same disk of material that is responsible for the water maser emission observed in NGC 4945. Local number counts of Seyfert 1 and Seyfert 2 galaxies show a large population of heavily obscured active galactic nuclei (AGNs) which are proposed to make up the cosmic X-ray background (CXRB). However, for this to be the case, the absorption geometry in the context of axially symmetric unification schemes must have the obscuring material subtending a large scale height-contrary to our inferences about NGC 4945-implying that NGC 4945 is not a prototype of obscured ACNs postulated to make up the CXRB. The small solid angle of the absorber, together with the black hole mass (of similar to 1.4 x 10(6) M-circle dot) from megamaser measurements, allows a robust determination of the nuclear luminosity, which in turn implies that the source radiates at similar to 10% of the Eddington limit. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Nicholaus Copernicus Astron Ctr, PL-00716 Warsaw, Poland. Univ Durham, Dept Phys, Durham DH1 3LE, England. Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. Stanford Univ, Dept Phys, Palo Alto, CA 94304 USA. RP Madejski, G (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RI done, chris/D-4605-2016 OI done, chris/0000-0002-1065-7239 NR 22 TC 38 Z9 38 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 2000 VL 535 IS 2 BP L87 EP L90 DI 10.1086/312703 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327JA UT WOS:000087789700005 ER PT J AU Terashima, Y Ho, LC Ptak, AF Yaqoob, T Kunieda, H Misaki, K Serlemitsos, PJ AF Terashima, Y Ho, LC Ptak, AF Yaqoob, T Kunieda, H Misaki, K Serlemitsos, PJ TI Iron K line variability in the low-luminosity active galactic nucleus NGC 4579 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (NGC 4579); galaxies : nuclei; galaxies : Seyfert; X-rays : galaxies ID GAS IMAGING SPECTROMETER; X-RAY-PROPERTIES; ASCA OBSERVATION; EMISSION; GALAXIES; MCG-6-30-15; ACCRETION; MODELS; DISK; M81 AB We present results of new ASCA observations of the low-luminosity active galactic nucleus (LLAGN) NGC 4579 obtained on 1998 December 18 and 28, and we report on the detection of variability of an iron K emission line. The X-ray luminosities in the 2-10 keV band for the two observations are nearly identical (L-X approximate to 2 x 10(41) ergs s(-1)), but they are similar to 35% larger than that measured in 1995 July by Terashima et al. An Fe K emission line is detected at 6.39 +/- 0.09 keV (source rest frame), which is lower than the line energy 6.73(-0.12)(+0.13) keV in the 1995 observation. If we fit the Fe lines with a blend of two Gaussians centered at 6.39 and 6.73 keV, the intensity of the 6.7 keV line decreases, while the intensity of the 6.3 keV line increases, within an interval of 3.5 yr. This variability rules out thermal plasmas in the host galaxy as the origin of the ionized Fe line in this LLAGN. The detection and variability of the 6.4 keV line indicates that cold matter subtends a large solid angle viewed from the nucleus and that it is located within similar to 1 pc from the nucleus. It could be identified with an optically thick standard accretion disk. If this is the case, a standard accretion disk is present at the Eddington ratio of L-bol/L-Edd similar to 2 x 10(-3). A broad disk-line profile is not clearly seen, and the structure of the innermost part of accretion disk remains unclear. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Observ Carnegie Inst Washington, Pasadena, CA 91101 USA. Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. RP Terashima, Y (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 28 TC 19 Z9 19 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 2000 VL 535 IS 2 BP L79 EP L82 DI 10.1086/312710 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327JA UT WOS:000087789700003 ER PT J AU Ferrarese, L Ford, HC Huchra, J Kennicutt, RC Mould, JR Sakai, S Freedman, WL Stetson, PB Madore, BF Gibson, BK Graham, JA Hughes, SM Illingworth, GD Kelson, DD Macri, L Sebo, K Silbermann, NA AF Ferrarese, L Ford, HC Huchra, J Kennicutt, RC Mould, JR Sakai, S Freedman, WL Stetson, PB Madore, BF Gibson, BK Graham, JA Hughes, SM Illingworth, GD Kelson, DD Macri, L Sebo, K Silbermann, NA TI A database of Cepheid distance moduli and tip of the red giant branch, globular cluster luminosity function, planetary nebula luminosity function, and surface brightness fluctuation data useful for distance determinations SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Review DE cosmology : theory; galaxies : distances and redshifts ID HUBBLE-SPACE-TELESCOPE; SCALE KEY PROJECT; H-II REGIONS; DWARF IRREGULAR GALAXY; ABSOLUTE PEAK BRIGHTNESS; VIRGO CLUSTER; STANDARD CANDLES; STELLAR POPULATIONS; SPIRAL GALAXIES; FORNAX CLUSTER AB We present a compilation of Cepheid distance moduli and data for four secondary distance indicators that employ stars in the old stellar populations: the planetary nebula luminosity function (PNLF), the globular cluster luminosity function (GCLF), the tip of the red giant branch (TRGB), and the surface brightness fluctuation (SBF) method. The database includes all data published as of 1999 July 15. The main strength of this compilation resides in the fact that all data are on a consistent and homogeneous system: all Cepheid distances are derived using the same calibration of the period-luminosity relation, the treatment of errors is consistent for all indicators, and measurements that are not considered reliable are excluded. As such, the database is ideal for comparing any of the distance indicators considered, or for deriving a Cepheid calibration to any secondary distance indicator, such as the Tully-Fisher relation, the Type Ia supernovae, or the fundamental plane for elliptical galaxies. This task has already been undertaken by Ferrarese et at, Sakai et al., Kelson et al., and Gibson et al. Specifically the database includes (1) Cepheid distances, extinctions, and metallicities; (2) reddened apparent lambda 5007 Angstrom magnitudes of the PNLF cutoff; (3) reddened apparent magnitudes and colors of the turnover of the GCLF (in both the V and B bands); (4) reddened apparent magnitudes of the TRGB (in the I band) and V-I colors at 0.5 mag fainter than the TRGB; and (5) reddened apparent surface brightness fluctuation magnitudes measured in Kron-Cousin I, K', and K-short, and using the F814W filter with the Hubble Space Telescope (HST) WFPC2. In addition, for every galaxy in the database we give reddening estimates from IRAS/DIRBE as well as H I maps, J2000 coordinates, Hubble and T-type morphological classification, apparent total magnitude in B, and systemic velocity. C1 CALTECH, Pasadena, CA 91125 USA. Johns Hopkins Univ, Baltimore, MD 21218 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. Australian Natl Univ, Res Sch Astron & Astrophys, Inst Adv Studies, Weston, ACT 2611, Australia. Natl Opt Astron Observ, Kitt Peak Natl Observ, Tucson, AZ 85726 USA. Carnegie Observ, Pasadena, CA 91101 USA. Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. NASA, IPAC, Extragalact Database, Pasadena, CA 91125 USA. CALTECH, Pasadena, CA 91125 USA. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. Royal Greenwich Observ, Cambridge CB3 0HA, England. Univ Calif Santa Cruz, Lick Observ, Santa Cruz, CA 95064 USA. RP Ferrarese, L (reprint author), CALTECH, Pasadena, CA 91125 USA. RI Gibson, Brad/M-3592-2015 OI Gibson, Brad/0000-0003-4446-3130 NR 182 TC 134 Z9 135 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUN PY 2000 VL 128 IS 2 BP 431 EP 459 PG 29 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360QA UT WOS:000089677700002 ER PT J AU Hurley, K Lund, N Brandt, S Barat, C Cline, T Sunyaev, R Terekhov, O Kuznetsov, A Sazonov, S Castro-Tirado, A AF Hurley, K Lund, N Brandt, S Barat, C Cline, T Sunyaev, R Terekhov, O Kuznetsov, A Sazonov, S Castro-Tirado, A TI The Ulysses supplement to the Granat/WATCH catalog of cosmic gamma-ray bursts SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE catalogs; gamma rays : bursts ID ARRIVAL TIME LOCALIZATIONS; 28 FEBRUARY 1997; ERROR BOX AB We present third Interplanetary Network (IPN) localization data for 56 gamma-ray bursts in the Granat/WATCH catalog that occurred between 1990 November and 1994 September. These localizations are obtained by triangulation using various combinations of spacecraft and instruments in the IPN, which consisted of Ulysses, BATSE, Pioneer Venus Orbiter, Mars Observer, WATCH, and PHEBUS. The intersections of the triangulation annuli with the WATCH error circles produce error boxes with areas as small as 16 arcmin(2), reducing the sizes of the error circles by factors of up to 800. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Danish Space Res Inst, DK-2100 Copenhagen, Denmark. Ctr Etud Spatiale Rayonnements, F-31029 Toulouse, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Inst Kosmitcheskij Iseldovanja, Moscow 117810, Russia. INTA, LAEFF, E-28080 Madrid, Spain. RP Hurley, K (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. OI Castro-Tirado, A. J./0000-0003-2999-3563 NR 18 TC 14 Z9 14 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUN PY 2000 VL 128 IS 2 BP 549 EP 560 DI 10.1086/313400 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360QA UT WOS:000089677700008 ER PT J AU Fixsen, DJ Moseley, SH Arendt, RG AF Fixsen, DJ Moseley, SH Arendt, RG TI Calibrating array detectors SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE infrared : general; instrumentation : detectors AB The development of sensitive large-format imaging arrays for the infrared promises to provide revolutionary capabilities for space astronomy. For example, the Infrared Array Camera (IRAC) on SIRTF will use four 256 x 256 arrays to provide background limited high spatial resolution images of the sky in the 3 to 8 mu m spectral region. In order to reach the performance limits possible with this generation of sensitive detectors, calibration procedures must be developed so that uncertainties in detector calibration will always be dominated by photon statistics from the dark sky as a major system noise source. In the near-infrared, where the faint extragalactic sky is observed through the scattered and re-emitted zodiacal light from our solar system, calibration is particularly important. Faint sources must be detected on this brighter local foreground. We present a procedure for calibrating imaging systems and analyzing such data. In our approach, by proper choice of observing strategy, information about detector parameters is encoded in the sky measurements. Proper analysis allows us to simultaneously solve for sky brightness and detector parameters and provides accurate formal error estimates. This approach allows us to extract the calibration from the observations themselves; little or no additional information is necessary to allow full interpretation of the data. Further, this approach allows refinement and verification of detector parameters during the mission and thus does not depend on a priori knowledge of the system or ground calibration for interpretation of images. C1 NASA, Goddard Space Flight Ctr, Raytheon ITSS Corp, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Infrared Astrophys Branch, Greenbelt, MD 20771 USA. RP Fixsen, DJ (reprint author), NASA, Goddard Space Flight Ctr, Raytheon ITSS Corp, Code 685, Greenbelt, MD 20771 USA. RI Moseley, Harvey/D-5069-2012 NR 6 TC 28 Z9 28 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUN PY 2000 VL 128 IS 2 BP 651 EP 658 DI 10.1086/313390 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360QA UT WOS:000089677700014 ER PT J AU Mack, WJ LaBree, L Liu, CR Liu, CH Selzer, RH Hodis, HN AF Mack, WJ LaBree, L Liu, CR Liu, CH Selzer, RH Hodis, HN TI Correlations between measures of atherosclerosis change using carotid ultrasonography and coronary angiography SO ATHEROSCLEROSIS LA English DT Article DE atherosclerosis; angiography; ultrasonography; coronary disease; carotid arteries ID INTIMA-MEDIA THICKNESS; B-MODE ULTRASOUND; COLESTIPOL-NIACIN THERAPY; CHOLESTEROL-LOWERING ATHEROSCLEROSIS; RISK HYPERTENSIVE PATIENTS; CONTROLLED CLINICAL-TRIAL; ARTERY DISEASE; MYOCARDIAL-INFARCTION; CARDIOVASCULAR HEALTH; PROGRESSION AB Few studies have examined the correlation between change in carotid artery intima-media thickness (IMT) and change in coronary artery disease. In the Cholesterol Lowering Atherosclerosis Study, current nonsmoking men with coronary artery disease were randomized to colestipol-niacin or placebo. Among 133 subjects with baseline and on-trial coronary angiography and carotid ultrasonography, colestipol-niacin treatment significantly reduced progression of atherosclerosis by both end point measures (2-year average change in percent diameter stenosis by coronary angiography and rate of change in carotid IMT). Significant correlations between change in common carotid artery IMT and quantitative coronary angiographic measures of change were evident over all coronary artery lesions, and in mild/moderate (< 50% diameter stenosis), but not severe (greater than or equal to 50% diameter stenosis) coronary artery lesions. In mild/moderate lesions, correlations with change in common carotid IMT were: percent diameter stenosis (r = 0.28, P = 0.002), minimum lumen diameter (r = - 0.28, P = 0.002), and vessel edge roughness (r = 0.25, P = 0.003). While measures obtained by carotid ultrasonography and coronary angiography are correlated, they each assess different aspects of atherosclerosis change. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved. C1 Univ So Calif, Atherosclerosis Res Unit, Los Angeles, CA 90089 USA. Univ So Calif, Dept Prevent Med, Los Angeles, CA 90089 USA. Univ So Calif, Dept Med, Los Angeles, CA 90089 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Mack, WJ (reprint author), Univ So Calif, Atherosclerosis Res Unit, Los Angeles, CA 90089 USA. FU NHLBI NIH HHS [R01-HL49885, R03-HL54532] NR 40 TC 76 Z9 95 U1 0 U2 3 PU ELSEVIER SCI IRELAND LTD PI CLARE PA CUSTOMER RELATIONS MANAGER, BAY 15, SHANNON INDUSTRIAL ESTATE CO, CLARE, IRELAND SN 0021-9150 J9 ATHEROSCLEROSIS JI Atherosclerosis PD JUN PY 2000 VL 150 IS 2 BP 371 EP 379 DI 10.1016/S0021-9150(99)00383-4 PG 9 WC Cardiac & Cardiovascular Systems; Peripheral Vascular Disease SC Cardiovascular System & Cardiology GA 324NW UT WOS:000087629100015 PM 10856529 ER PT J AU Hamm, PB Nicogossian, AE Pool, SL Wear, ML Billica, RD AF Hamm, PB Nicogossian, AE Pool, SL Wear, ML Billica, RD TI Design and current status of the longitudinal study of astronaut health SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE astronauts; epidemiology; space medicine ID DIABETES-MELLITUS; PREVALENCE; MINNESOTA; HYPERTENSION; MORTALITY; ROCHESTER; MILITARY; SMOKING; TRENDS; COHORT AB Background: Information has been collected regarding the immediate physiological effects of spaceflight on humans. However, little is yet known regarding long-term effects. The purpose of this paper is to describe the Longitudinal Study of Astronaut Health (LSAH) and report current mortality data. Methods: All astronauts selected for the United States Space Program are followed from selection throughout their lifetime or until the end of the study. Comparisons are ground-based Johnson Space Center (JSC) employees matched to the astronauts at a 3:1 ratio by sex-specific age and body mass index. They are followed in the same manner as astronauts. Morbidity and mortality data are obtained from medical records supplemented with study questionnaires. Checks for death certificates are made to ascertain death of participants who miss routine examinations. Results: Current cause-specific mortality rates for astronauts selected from 1959 through 1991 are not statistically different from rates for comparison participants fbr cardiovascular (p = 0.8112), cancer (p = 0.2382), or other disease (p = 0.5040) mortality. Astronauts have a significantly higher mortality rate due to accidents and injuries (p < 0.0001). Conclusions: Astronauts have a similar risk of death due to chronic diseases as ground-based participants, but are at greater risk for occupational-related accidental death. C1 Wyle Life Sci, Houston, TX 77058 USA. NASA Headquarters, Washington, DC USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Wear, ML (reprint author), Wyle Life Sci, 1290 Hercules Dr,Suite 120, Houston, TX 77058 USA. NR 20 TC 8 Z9 9 U1 0 U2 1 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 JUN PY 2000 VL 71 IS 6 BP 564 EP 570 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 321TA UT WOS:000087469700002 PM 10870814 ER PT J AU Wade, CE Wang, TJ Lang, KC Corbin, BJ Steele, MK AF Wade, CE Wang, TJ Lang, KC Corbin, BJ Steele, MK TI Rat growth, body composition, and renal function during 30 days increased ambient CO2 exposure SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE hypercapnia; respiratory acidosis; acid-base balance; electrolyte excretion ID METABOLIC RESPONSES; CALCIUM-METABOLISM; HYPERCAPNIA; ACIDOSIS AB Background: In experiments using rodents onboard orbiting spacecraft, specimens may be exposed to an increase in ambient CO2. Hypothesis: Many of the physiological changes reported in rats (and humans) for spaceflight are similar to those observed with increased CO2, raising the question whether the observed changes are due to spaceflight or more specifically, the elevated ambient CO2. Methods: To evaluate the effects of increased CO2, at levels similar to those experienced during spaceflight, three groups of adult male rats (n = 10) were exposed to ambient CO2 concentrations of 0.3, 0.7 and 2.0% for 30 d. Control rats were exposed to atmospheric conditions (0.03% CO2) for each group. Results: There were alterations in water turnover, food intake, and renal function with increased CO2. Blood pH, total CO2, and plasma concentrations of Na+, Ca2+, and corticosterone were significantly elevated at the 2.0% exposure, while plasma PO43- was reduced. At the 0.3% and 0.7% CO2 exposures, many of these changes were not significant. Animals exposed to 0.3% CO2 showed a significant increase in total body Na+. Urinary Ca2+, K+, creatinine, corticosterone, and total CO2 excretion were higher at 2.0%, but only Ca2+ and CO2 excretion were significantly elevated at 0.7%, and there was no significant alteration in renal function at 0.3%. Conclusion: Chronic increased ambient CO2 levels, similar to those observed on the Space Shuttle and proposed for the International Space Station, elicit compensatory responses in rats which may affect interpretation of experiments designed to evaluate the effects of exposure to microgravity. C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. RP Wade, CE (reprint author), NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. NR 41 TC 1 Z9 1 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 JUN PY 2000 VL 71 IS 6 BP 599 EP 609 PG 11 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 321TA UT WOS:000087469700007 PM 10870819 ER PT J AU Wang, TJ Wade, CE AF Wang, TJ Wade, CE TI Effects of hindlimb suspension and elevated ambient CO2 on rat growth and renal function SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE microgravity; head-down tilt; hypercapnia; respiratory acidosis; acid-base balance ID CHRONIC RESPIRATORY-ACIDOSIS; HEAD-DOWN TILT; SIMULATED MICROGRAVITY; CALCIUM-METABOLISM; MUSCLE ATROPHY; SPACE-FLIGHT; MODEL; HYPOKINESIA; RESPONSES; EXERCISE AB Background: Previous studies show that an ambient CO2 concentration of 2.0% may complicate interpretation of animal experiments conducted in spaceflight, while 0.7% CO2 exposure produces minimal effects. Hypothesis: With additional spaceflight factors, such as microgravity, effects from the 0.7% CO2 exposure may be amplified. Methods: To investigate the combined effects from microgravity and elevated CO2 on growth and renal function, two groups of rats were hindlimb suspended for 37 d, and a third group served as an ambulatory vivarium control (AMB). One suspension group was exposed to 0.7% CO2 for 30 d (HLS + 0.7% CO2), while the other group (HLS) served as a suspended control. Both the AMB and HLS groups breathed room air at 0.03% CO2. Results: The HLS group showed responses consistent with past hindlimb suspension studies when compared with AMB, indicating similar reductions in organ and tissue weights and body weight gain. When comparing HLS + 0.7% CO2 animals to HLS controls, exposure to CO2 revealed lowered food consumption and increased urine volume, NH3 and CO2 excretion, with no differences in any of the other measured parameters, such as body weight gain, pH values, or electrolyte handling. Conclusion: This study shows that chronic exposure to both 0.7% ambient CO2 and hindlimb suspension together have little additional effect on rat growth and renal function. C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. RP Wang, TJ (reprint author), NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. NR 30 TC 4 Z9 4 U1 0 U2 1 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 JUN PY 2000 VL 71 IS 6 BP 610 EP 618 PG 9 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 321TA UT WOS:000087469700008 PM 10870820 ER PT J AU Palinkas, LA Gunderson, E Holland, AW Miller, C Johnson, JC AF Palinkas, LA Gunderson, E Holland, AW Miller, C Johnson, JC TI Predictors of behavior and performance in extreme environments: The Antarctic space analogue program SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE Antarctica; performance; extreme environments; personality; interpersonal needs ID ASTRONAUT EFFECTIVENESS; MISSIONS; STRESS AB Background: To determine which, if any, characteristics should be incorporated into a select-in approach to screening personnel for longduration spaceflight, we examined the influence of crewmember social/demographic characteristics, personality traits, interpersonal needs, and characteristics of station physical environments on performance measures in 657 American men who spent an austral winter in Antarctica between 1963 and 1974. Methods: During screening, subjects completed a Personal History Questionnaire which obtained information on social and demographic characteristics, the Deep Freeze Opinion Survey which assessed 5 different personality traits, and the Fundamental interpersonal Relations Orientation-Behavior (FIRO-B) Scale which measured 6 dimensions of interpersonal needs. Station environment included measures of crew size and severity of physical environment. Performance was assessed on the basis of combined peer-supervisor evaluations of overall performance, peer nominations of fellow crewmembers who made ideal winter-over candidates, and self-reported depressive symptoms. Results: Social/demographic characteristics, personality traits, interpersonal needs, and characteristics of station environments collectively accounted for 9-17% of the variance in performance measures. The following characteristics were significant independent predictors of more than one performance measure: military service, low levels Of neuroticism, extraversion and conscientiousness, and a low desire for affection from others. Conclusions: These results represent an important first step in the development of select-in criteria for personnel on long-duration missions in space and other extreme environments. These criteria must take into consideration the characteristics of the environment and the limitations they place on meeting needs for interpersonal relations and task performance, as well as the characteristics of the individuals and groups who live and work in these environments. C1 Univ Calif San Diego, Dept Family & Prevent Med, La Jolla, CA 92093 USA. USN, Hlth Res Ctr, San Diego, CA 92152 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. E Carolina Univ, Inst Coastal & Marine Studies, Greenville, NC USA. RP Palinkas, LA (reprint author), Univ Calif San Diego, Dept Family & Prevent Med, 9500 Gilman Dr, La Jolla, CA 92093 USA. NR 26 TC 36 Z9 37 U1 0 U2 12 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 JUN PY 2000 VL 71 IS 6 BP 619 EP 625 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 321TA UT WOS:000087469700009 PM 10870821 ER PT J AU Blythe, AE Burbank, DW Farley, KA Fielding, EJ AF Blythe, AE Burbank, DW Farley, KA Fielding, EJ TI Structural and topographic evolution of the central Transverse Ranges, California, from apatite fission-track, (U-Th)/He and digital elevation model analyses SO BASIN RESEARCH LA English DT Article ID SAN-BERNARDINO MOUNTAINS; WEST-CENTRAL ARIZONA; LOS-ANGELES BASIN; SOUTHERN-CALIFORNIA; GABRIEL-MOUNTAINS; STRAIN ACCUMULATION; ANNEALING KINETICS; HELIUM DIFFUSION; TECTONIC UPLIFT; ANDREAS FAULT AB Apatite fission-track (FT) and (U-Th)/He analyses are used to constrain the low-temperature thermal history of the San Gabriel and San Bernardino Mountains (SGM and SBM), which are part of the southern California Transverse Ranges. FT ages from 33 SGM samples range from 3 to 64 Ma. Helium ages, ranging from 3 to 43 Ma, were obtained from 13 of these samples: all of the He ages are the same or younger than their respective FT ages. FT ages from 10 SBM samples were older, ranging from 45 to 90 Ma. The FT and He data document at least three phases of cooling in the SGM, but only two in the SBM. Prior to similar to 7 Ma, the thermal history of the SGM appears to have been nearly identical to many of the core complexes in the Basin and Range of south-eastern California: a major phase of cooling is indicated from similar to 60 to 40 Ma, with a more recent phase beginning at similar to 23 Ma and continuing until similar to 10 Ma. The similarity of this timing to that of core complexes suggests that the SGM also originated as a core complex, when the rocks were adjacent to the Chocolate-Orocopia Mountains, and that some of the range-bounding faults were initially extensional. In the SBM, the two phases of cooling documented by the FT data occurred from similar to 65 to 55 Ma, and from similar to 18 Ma to the present. The timing on the second phase is very poorly constrained and, therefore, we do not speculate on the origin of the SBM. The most recent phase of cooling appears to have begun at similar to 7 Ma in the SGM, as the result of the onset of contractional deformation. A more accelerated phase of cooling may have begun at similar to 3 Ma. Distinct variations in the total amounts and rates of cooling between different fault-bounded blocks within the SGM are documented since 7 Ma. We use these variations in cooling rates to calculate denudation rates, which are then compared to topographic characteristics for each structural block. These comparisons suggest that more rapid bedrock uplift in the eastern and southern part of the range has strongly affected the present-day physiography. Despite a higher mean elevation, the SBM are much less dissected than the SGM, suggesting that the most recent phase of cooling and bedrock uplift began in the last 3 Myr, much later than the initiation of recent bedrock uplift in the SGM. C1 Univ So Calif, Dept Earth Sci, Los Angeles, CA 90089 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. Jet Prop Lab, Pasadena, CA 91109 USA. RP Blythe, AE (reprint author), Univ So Calif, Dept Earth Sci, Los Angeles, CA 90089 USA. RI Fielding, Eric/A-1288-2007 OI Fielding, Eric/0000-0002-6648-8067 NR 87 TC 66 Z9 66 U1 0 U2 7 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0950-091X J9 BASIN RES JI Basin Res. PD JUN PY 2000 VL 12 IS 2 BP 97 EP 114 PG 18 WC Geosciences, Multidisciplinary SC Geology GA 346QQ UT WOS:000088882900001 ER PT J AU Lau, KM Ding, YH Wang, JT Johnson, R Keenan, T Cifelli, R Gerlach, J Thiele, O Rickenbach, T Tsay, SC Lin, PH AF Lau, KM Ding, YH Wang, JT Johnson, R Keenan, T Cifelli, R Gerlach, J Thiele, O Rickenbach, T Tsay, SC Lin, PH TI A report of the field operations and early results of the South China Sea Monsoon Experiment (SCSMEX) SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article AB The South China Sea Monsoon Experiment (SCSMEX) is an international field experiment with the objective to better understand the key physical processes for the onset and evolution of the summer monsoon over Southeast Asia and southern China aiming at improving monsoon predictions. In this article, a description of the major meteorological observation platforms during the intensive observing periods of SCSMEX is presented. In addition, highlights of early results and discussions of the role of SCSMEX in providing valuable in situ data for calibration of satellite rainfall estimates from the Tropical Rainfall Measuring Mission are provided. Preliminary results indicate that there are distinctive stages in the onset of the South China Sea monsoon including possibly strong influences from extratropical systems as well as from convection over the Indian Ocean and the Bay of Bengal. There is some tantalizing evidence of complex interactions between the supercloud cluster development over the Indian Ocean, advancing southwest monsoon flow over the South China Sea, midlatitude disturbances, and the western Pacific subtropical high, possibly contributing to the disastrous flood of the Yangtze River Basin in China during June 1998. C1 NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. Natl Climate Ctr, Beijing, Peoples R China. Natl Cent Univ, Dept Atmospher Sci, Chungli 32054, Taiwan. Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. Bur Meteorol Res Ctr, Melbourne, Vic, Australia. NASA, Goddard Space Flight Ctr, TRMM Off, Greenbelt, MD 20771 USA. NASA, Wallops Space Flight Ctr, Wallops Island, VA USA. Natl Taiwan Univ, Dept Atmospher Sci, Taipei 10764, Taiwan. RP Lau, KM (reprint author), NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Code 913, Greenbelt, MD 20771 USA. RI Tsay, Si-Chee/J-1147-2014; Lau, William /E-1510-2012; OI Lau, William /0000-0002-3587-3691; LIN, PO-HSIUNG/0000-0002-6410-6221 NR 9 TC 111 Z9 127 U1 0 U2 11 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 JUN PY 2000 VL 81 IS 6 BP 1261 EP 1270 DI 10.1175/1520-0477(2000)081<1261:AROTFO>2.3.CO;2 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 319FF UT WOS:000087330300005 ER PT J AU Robock, A Vinnikov, KY Srinivasan, G Entin, JK Hollinger, SE Speranskaya, NA Liu, SX Namkhai, A AF Robock, A Vinnikov, KY Srinivasan, G Entin, JK Hollinger, SE Speranskaya, NA Liu, SX Namkhai, A TI The Global Soil Moisture Data Bank SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID SURFACE PARAMETERIZATION SCHEMES; MODEL INTERCOMPARISON PROJECT; TEMPERATURE-MEASUREMENTS; SNOW PARAMETERIZATION; WETNESS PROJECT; SIMULATIONS; VALIDATION; CLIMATE; VARIABILITY; BIOSPHERE AB Soil moisture is an important variable in the climate system. Understanding and predicting variations of surface temperature, drought, and flood depend critically on knowledge of soil moisture variations, as do impacts of climate change and weather forecasting. An observational dataset of actual in situ measurements is crucial for climatological analysis, for model development and evaluation, and as ground truth for remote sensing. To that end, the Global Soil Moisture Data Bank, a Web site (http://climate.envsci.rutgers.edu/soil_moisture) dedicated to collection, dissemination, and analysis of soil moisture data from around the globe, is described. The data bank currently has soil moisture observations for over 600 stations from a large variety of global climates, including the former Soviet Union, China, Mongolia, India, and the United States. Most of the data are in situ gravimetric observations of soil moisture; all extend for at least 6 years and most for more than 15 years. Most of the stations have grass vegetation, and some are agricultural. The observations have been used to examine the temporal and spatial scales of soil moisture variations, to evaluate Atmospheric Model Intercomparison Project, Project for Intercomparison of Land-Surface Parameterization Schemes, and Global Soil Wetness Project simulations of soil moisture, for remote sensing of soil moisture, for designing new soil moisture observational networks, and to examine soil moisture trends. For the top I-m soil layers, the temporal scale of soil moisture variation at all midlatitude sites is 1.5 to 2 months and the spatial scale is about 500 km. Land surface models, in general, do not capture the observed soil moisture variations when forced with either model-generated or observed meteorology. In contrast to predictions of summer desiccation with increasing temperatures, for the stations with the longest records summer soil moisture in the top 1 m has increased while temperatures have risen. The increasing trend in precipitation more than compensated for the enhanced evaporation. C1 Rutgers State Univ, Dept Environm Sci, New Brunswick, NJ 08901 USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Illinois State Water Survey, Champaign, IL 61820 USA. State Hydrol Inst, St Petersburg, Russia. Chinese Acad Sci, Inst Geog, Dept Hydrol, Beijing 100012, Peoples R China. Environm COnsulting & Assessment Co, Ulaanbaatar, Mongol Peo Rep. RP Robock, A (reprint author), Rutgers State Univ, Dept Environm Sci, 14 Coll Farm Rd, New Brunswick, NJ 08901 USA. RI Vinnikov, Konstantin/F-9348-2010; Robock, Alan/B-6385-2016; OI Robock, Alan/0000-0002-6319-5656 NR 79 TC 433 Z9 470 U1 10 U2 103 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 JUN PY 2000 VL 81 IS 6 BP 1281 EP 1299 DI 10.1175/1520-0477(2000)081<1281:TGSMDB>2.3.CO;2 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 319FF UT WOS:000087330300007 ER PT J AU Turner, DD Feltz, WF Ferrare, RA AF Turner, DD Feltz, WF Ferrare, RA TI Continuous water vapor profiles from operational ground-based active and passive remote sensors SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID RAMAN LIDAR MEASUREMENTS; ATMOSPHERIC RADIATION; AEROSOL EXTINCTION; TEMPERATURE; RADIANCE; BACKSCATTERING; SYSTEM AB The Atmospheric Radiation Measurement program's Southern Great Plains Cloud and Radiation Testbed site central facility near Lament, Oklahoma, offers unique operational water vapor profiling capabilities, including active and passive remote sensors as well as traditional in situ radiosonde measurements. Remote sensing technologies include an automated Raman lidar and an automated Atmospheric Emitted Radiance Interferometer (AERI), which are able to retrieve water vapor profiles operationally through the lower troposphere throughout the diurnal cycle. Comparisons of these two water vapor remote sensing methods to each other and to radiosondes over an 8-month period are presented and discussed, highlighting the accuracy and limitations of each method. Additionally, the AERI is able to retrieve profiles of temperature while the Raman lidar is able to retrieve aerosol extinction profiles operationally. These data, coupled with hourly wind profiles from a 915-MHz wind profiler, provide complete specification of the state of the atmosphere in noncloudy skies. Several case studies illustrate the utility of these high temporal resolution measurements in the characterization of mesoscale features within a 3-day time period in which passage of a dryline, warm air advection, and cold front occurred. C1 Pacific NW Lab, Climate Dynam Grp, Richland, WA 99352 USA. Univ Wisconsin, Cooperat Inst Meteorol Satellite Studies, Ctr Space Sci & Engn, Madison, WI USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Turner, DD (reprint author), Pacific NW Lab, Climate Dynam Grp, POB 999,MS K9-38, Richland, WA 99352 USA. NR 31 TC 52 Z9 52 U1 0 U2 4 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 JUN PY 2000 VL 81 IS 6 BP 1301 EP 1317 DI 10.1175/1520-0477(2000)081<1301:CWBPFO>2.3.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 319FF UT WOS:000087330300008 ER PT J AU Sigler, MF AF Sigler, MF TI Abundance estimation and capture of sablefish (Anoplopoma fimbria) by longline gear SO CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES LA English DT Article ID GADUS-MORHUA; BAIT; FISH; RESPONSES; BEHAVIOR; COD AB Longline surveys in Alaska measure sablefish (Anoplopoma fimbria) relative abundance and are the primary information source used for abundance and quota estimation. Hook timer, on-bottom (soak) time, hook density, hook pattern, bait type, and bait condition experiments and mathematical models were used to evaluate the performance of the longline surveys for estimating sablefish relative abundance. The rate that sablefish encountered the longline gear decreased with on-bottom time independently of sablefish density in the sampled area. Sablefish were adept at locating available baits, even when few remained. The decrease in encounter rate appears related to odor concentration at the leading edge of the odor plume. The ability to locate baits, even when few remain, differs from previous models of fish capture by longline in which the probability that a fish located a bait was proportional to the number of available baits. Decreased encounter rate and the ability to locate baits efficiently imply that longline catch rates likely provide an accurate index of fish abundance if the on-bottom time is long enough to cover the period when most fish encounter the gear and the initial bait density is high enough that baits remain available throughout the soak; the weak link between catch rate and abundance is the unknown extent that factors such as temperature and food availability affect the proportion of fish caught. C1 Natl Marine Fisheries Serv, NOAA, Alaska Fisheries Sci Ctr, Auke Bay Lab, Juneau, AK 99801 USA. RP Sigler, MF (reprint author), Natl Marine Fisheries Serv, NOAA, Alaska Fisheries Sci Ctr, Auke Bay Lab, 11305 Glacier Highway, Juneau, AK 99801 USA. NR 26 TC 21 Z9 22 U1 2 U2 6 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 JUN PY 2000 VL 57 IS 6 BP 1270 EP 1283 DI 10.1139/cjfas-57-6-1270 PG 14 WC Fisheries; Marine & Freshwater Biology SC Fisheries; Marine & Freshwater Biology GA 325YC UT WOS:000087703800017 ER PT J AU Koon, WS Lo, MW Marsden, JE Ross, SD AF Koon, WS Lo, MW Marsden, JE Ross, SD TI Heteroclinic connections between periodic orbits and resonance transitions in celestial mechanics SO CHAOS LA English DT Article ID PATTERN EVOCATION; SYSTEMS THEORY; 3-BODY PROBLEM; INTEGRATORS; TRANSFERS; SYMMETRY; EARTH AB In this paper we apply dynamical systems techniques to the problem of heteroclinic connections and resonance transitions in the planar circular restricted three-body problem. These related phenomena have been of concern for some time in topics such as the capture of comets and asteroids and with the design of trajectories for space missions such as the Genesis Discovery Mission. The main new technical result in this paper is the numerical demonstration of the existence of a heteroclinic connection between pairs of periodic orbits: one around the libration point L-1 and the other around L-2, with the two periodic orbits having the same energy. This result is applied to the resonance transition problem and to the explicit numerical construction of interesting orbits with prescribed itineraries. The point of view developed in this paper is that the invariant manifold structures associated to L-1 and L-2 as well as the aforementioned heteroclinic connection are fundamental tools that can aid in understanding dynamical channels throughout the solar system as well as transport between the "interior" and "exterior" Hill's regions and other resonant phenomena. (C) 2000 American Institute of Physics. [S1054-1500(00)00402-X]. C1 CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Koon, WS (reprint author), CALTECH, Pasadena, CA 91125 USA. RI Ross, Shane/B-7237-2009 OI Ross, Shane/0000-0001-5523-2376 NR 43 TC 265 Z9 272 U1 1 U2 16 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 1054-1500 J9 CHAOS JI Chaos PD JUN PY 2000 VL 10 IS 2 BP 427 EP 469 DI 10.1063/1.166509 PG 43 WC Mathematics, Applied; Physics, Mathematical SC Mathematics; Physics GA 319MT UT WOS:000087346300015 ER PT J AU Fletcher, GD Schmidt, MW Bode, BM Gordon, MS AF Fletcher, GD Schmidt, MW Bode, BM Gordon, MS TI The Distributed Data Interface in GAMESS SO COMPUTER PHYSICS COMMUNICATIONS LA English DT Article ID PERFORMANCE COMPUTATIONAL CHEMISTRY; MOLECULAR ELECTRONIC-STRUCTURE; COUPLED-CLUSTER ALGORITHM; PARALLEL DIRECT SCF; MEMORY COMPUTERS; IMPLEMENTATION; TRANSFORMATIONS; GRADIENT; ENERGY AB The Distributed Data Interface to permit storage of large data arrays in the aggregate memory of distributed memory, message passing computer systems is described. The design of this relatively small library is discussed, in regard to its implementation over SHMEM, MPI-1. or socket based message libraries. The good performance of a MP2 program using DDI is demonstrated on both PC and workstation cluster computers, and some details of the resulting message traffic are presented. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Iowa State Univ, Dept Chem, Ames, IA 50011 USA. US DOE, Ames Lab, Scalable Comp Lab, Ames, IA 50011 USA. RP Fletcher, GD (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 34 TC 94 Z9 94 U1 2 U2 9 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0010-4655 J9 COMPUT PHYS COMMUN JI Comput. Phys. Commun. PD JUN PY 2000 VL 128 IS 1-2 BP 190 EP 200 DI 10.1016/S0010-4655(00)00073-4 PG 11 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 327AH UT WOS:000087769100013 ER PT J AU Haworth, DC Jansen, K AF Haworth, DC Jansen, K TI Large-eddy simulation on unstructured deforming meshes: towards reciprocating IC engines SO COMPUTERS & FLUIDS LA English DT Article DE large-eddy simulation; unstructured-grid methods; dynamic subgrid-scale model ID REYNOLDS-NUMBER; STRESS MODEL; TURBULENCE; FLOW AB A variable explicit/implicit characteristics-based advection scheme that is second-order accurate in space and time has been developed recently for unstructured deforming meshes (O'Rourke PJ, Sahota MS. A variable explicit/implicit numerical method for calculating advection on unstructured meshes, J Comput Phys 1998;142:312-45), To explore the suitability of this methodology for large-eddy simulation (LES) in reciprocating internal combustion engines, three subgrid-scale turbulence models,have been implemented: a constant-coefficient Smagorinsky model, a dynamic Smagorinsky model for flows having one or more directions of statistical homogeneity, and a Lagrangian dynamic Smagorinsky model for flows having no spatial or temporal homogeneity (Meneveau C, Lund TS, Cabot WH. A Lagrangian dynamic subgrid-scale model of turbulence, J Fluid Mech 1996;319:353-85). Quantitative results are presented for three canonical flows (decaying homogeneous isotropic turbulence, non-solenoidal linear strains of homogeneous turbulence, planar channel flow) and for a simplified piston-cylinder assembly with moving piston and fixed central valve. Computations are compared to experimental measurements, to direct-numerical simulation data, and to rapid-distortion theory where appropriate. Generally satisfactory evolution of first, second, and some higher order moments is found. Computed mean and rms velocity profiles for the piston-cylinder configuration show better agreement with measurements than Reynolds-averaged turbulence models. These results demonstrate the suitability of this methodology for engineering LES, and the feasibility of LES for computing IC engine flows. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Thermal & Energy Syst Lab, GM R&D & NAO Planning, Warren, MI 48090 USA. Stanford Univ, NASA, Ames Ctr Turbulence Res, Stanford, CA 94305 USA. RP Haworth, DC (reprint author), Thermal & Energy Syst Lab, GM R&D & NAO Planning, Mail Code 480-106-252,30500 Mound Rd 106,Box 9055, Warren, MI 48090 USA. NR 33 TC 65 Z9 70 U1 2 U2 8 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD JUN PY 2000 VL 29 IS 5 BP 493 EP 524 DI 10.1016/S0045-7930(99)00015-8 PG 32 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA 302HC UT WOS:000086358800002 ER PT J AU Ebert, DS Rohrer, RM Shaw, CD Panda, P Kukla, JM Roberts, DA AF Ebert, DS Rohrer, RM Shaw, CD Panda, P Kukla, JM Roberts, DA TI Procedural shape generation for multi-dimensional data visualization SO COMPUTERS & GRAPHICS-UK LA English DT Article DE two-handed 3D user interfaces; procedural shapes; superquadrics; implicit surfaces; scientific and information visualization AB Visualization of multi-dimensional data is a challenging task. The goal is not the display of multiple data dimensions, but user comprehension of the multi-dimensional data. This paper explores several techniques for perceptually motivated procedural generation of shapes to increase the comprehension of multi-dimensional data. Our glyph-based system allows the visualization of both regular and irregular grids of volumetric data. A glyph's location, 3D size, color and opacity encode up to 8 attributes of scalar data per glyph. We have extended the system's capabilities to explore shape variation as a visualization attribute. We use procedural shape generation techniques because they allow flexibility, data abstraction, and freedom from specification of detailed shapes. We have explored three procedural shape generation techniques: fractal detail generation, superquadrics, and implicit surfaces. These techniques allow from 1 to 14 additional data dimensions to be visualized using glyph shape. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Maryland Baltimore Cty, CSEE Dept, Baltimore, MD 21250 USA. George Washington Univ, Dept EECS, Washington, DC 20052 USA. Univ Regina, Dept Comp Sci, Regina, SK S4S 0A2, Canada. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Georgia Tech Coll Comp, 801 Atlantic Dr, Atlanta, GA 30332 USA. EM ebert@csee.umbc.edu; roh-rer@seas.gwu.edu; cdshaw@cs.uregina.ca; panda@csee.umbc.edu; jkubla1@csee.umbc.edu; roberts@vayu.gsfc.nasa.go OI Ebert, David/0000-0001-6177-1296 NR 14 TC 22 Z9 22 U1 0 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0097-8493 EI 1873-7684 J9 COMPUT GRAPH-UK JI Comput. Graph.-UK PD JUN PY 2000 VL 24 IS 3 BP 375 EP 384 DI 10.1016/S0097-8493(00)00033-9 PG 10 WC Computer Science, Software Engineering SC Computer Science GA 328NM UT WOS:000087857000007 ER PT J AU Solomon, G AF Solomon, G TI Golay encoding/decoding via BCH-Hamming SO COMPUTERS & MATHEMATICS WITH APPLICATIONS LA English DT Article AB The (24, 12; 8) extended Golay Code can be generated as a 6 x 4 binary matrix from the (151 11; 3) BCH-Hamming Code, represented as a 5 x 3 matrix, by adding a row and column, both of odd or even parity. The odd parity case provides the additional 12(th) dimension. Furthermore, any three columns and five rows of the 6 x 4 Golay form a permuted BCH- Hamming (15, 11; 3) Code. Using the single-error correction of the BCH-Hamming Code, it is possible to decode in a primitive combinatoric fashion all three error patterns. Single- and double-error correction is almost immediate. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Solomon, G (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 4 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0898-1221 J9 COMPUT MATH APPL JI Comput. Math. Appl. PD JUN PY 2000 VL 39 IS 11 BP 103 EP 108 DI 10.1016/S0898-1221(00)00114-0 PG 6 WC Mathematics, Applied SC Mathematics GA 311BT UT WOS:000086865200016 ER PT J AU Hurd, WJ AF Hurd, WJ TI Maximum likelihood global positioning system receiver SO COMPUTERS & MATHEMATICS WITH APPLICATIONS LA English DT Article AB A maximum likelihood receiver concept has been developed for measuring the positions of vehicles using the signals from the Global Positioning System satellites. This receiver enables tracking when the vehicles are undergoing severe dynamics, including accelerations of 150 g and jerk of 150 g/s, as may be encountered in range testing of aircraft and missiles. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hurd, WJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0898-1221 J9 COMPUT MATH APPL JI Comput. Math. Appl. PD JUN PY 2000 VL 39 IS 11 BP 121 EP 125 DI 10.1016/S0898-1221(00)00117-6 PG 5 WC Computer Science, Interdisciplinary Applications; Mathematics, Applied SC Computer Science; Mathematics GA 311BT UT WOS:000086865200019 ER PT J AU Sergeev, B Madenci, E Ambur, DR AF Sergeev, B Madenci, E Ambur, DR TI Influence of bolt spacing and degree of anisotropy in single-lap joints SO COMPUTERS & STRUCTURES LA English DT Article; Proceedings Paper CT Conference of the NATO-Advanced-Study-Institue on Mechanics of Composite Materials and Structures CY JUL 12-24, 1998 CL TROIA, PORTUGAL SP NATO, Inst Adv Study, IDMEC, Inst Mech Engn, Inst Super Tecn, Tech Univ Lisbon DE multiple; bolt; spacing; composite; single-lap; joint AB This study concerns the effect of bolt spacing and degree of anisotropy on the bolt load distribution and nature of the failure mechanism. Bolt loads and failure prediction are determined using a solution method that treats the contact stresses and contact region as unknowns. Utilizing the boundary collocation technique, this method provides the non-linear solution while capturing the effects of finite geometry under general loading conditions. The nature of the failure mechanism is established by using the maximum strain criterion. Comparison of the predictions with experimental results reveals their close agreement. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Arizona, Dept Aeronaut & Mech Engn, Tucson, AZ 85721 USA. NASA, Langley Res Ctr, Struct Mech Branch, Hampton, VA 23665 USA. RP Madenci, E (reprint author), Univ Arizona, Dept Aeronaut & Mech Engn, Tucson, AZ 85721 USA. NR 4 TC 9 Z9 10 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD JUN PY 2000 VL 76 IS 1-3 BP 89 EP 103 DI 10.1016/S0045-7949(99)00142-X PG 15 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA 307CZ UT WOS:000086637000010 ER PT J AU Stone, M Remington, RW AF Stone, M Remington, RW TI Unintended cognitive processing in briefly attended locations. SO CONSCIOUSNESS AND COGNITION 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 ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 1053-8100 J9 CONSCIOUS COGN JI Conscious. Cogn. PD JUN PY 2000 VL 9 IS 2 SU S BP S45 EP S45 PN 2 PG 1 WC Psychology, Experimental SC Psychology GA 346YF UT WOS:000088898100054 ER PT J AU Parusel, ABJ Schamschule, R Kohler, G AF Parusel, ABJ Schamschule, R Kohler, G TI Reduction and radical addition: A theoretical study on chlorobenzonitriles SO CROATICA CHEMICA ACTA LA English DT Article DE chlorobenzonitriles; radical addition; reduction; semiempirical study AB The three isomers of chlorobenzonitrile (CBN) and the corresponding radical anions are investigated by semiempirical methods in order to study the regioselectivity of solvated hydrogen and hydroxy radical attacks. Additional negative charge is distributed upon reduction at the chlorine and cyano subunits and in para-position to the cyano group. Most of the negative charge (about 7056) is located in the aromatic ring. The different protonation sites for the negatively charged radical and neutral species are explained by distinctly different electro-negativities. The observed position of a hydroxy radical attack on 2-chlorobenzonitrile is correlated to the relative stabilities of the six possible addition products. The electron density contribution of 2-CBN as calculated by the Mulliken population analysis method is in excellent agreement with the experimentally observed formation of different products: The 2-chloro-5-hydroxybenzonitrile is the preferentially created species, with both the 4- and 6-hydroxy isomers as important sideproducts. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Vienna, Inst Theoret Chem & Struct Biol, A-1090 Vienna, Austria. RP Parusel, ABJ (reprint author), NASA, Ames Res Ctr, MS 239-4, Moffett Field, CA 94035 USA. NR 9 TC 3 Z9 3 U1 0 U2 3 PU CROATIAN CHEMICAL SOC PI ZAGREB PA MARULICEV TRG 19/II, 41001 ZAGREB, CROATIA SN 0011-1643 J9 CROAT CHEM ACTA JI Croat. Chem. Acta PD JUN PY 2000 VL 73 IS 2 BP 359 EP 366 PG 8 WC Chemistry, Multidisciplinary SC Chemistry GA 346NH UT WOS:000088877600004 ER PT J AU Carter, GA Bahadur, R Norby, RJ AF Carter, GA Bahadur, R Norby, RJ TI Effects of elevated atmospheric CO2 and temperature on leaf optical properties in Acer saccharum SO ENVIRONMENTAL AND EXPERIMENTAL BOTANY LA English DT Article DE Acer saccharum; carbon dioxide; air temperature; leaf optics ID CARBON-DIOXIDE ENRICHMENT; BARLEY PRIMARY LEAVES; CHLOROPHYLL CONTENT; REFLECTANCE; GROWTH; FOREST; TREE; RESPONSES; EXPOSURE AB Elevated partial pressures of atmospheric carbon dioxide, similar to numerous causes of plant stress, may alter leaf pigmentation and structure and thus would be expected to alter leaf optical properties. Hypotheses that elevated CO2 pressure and air temperature would alter leaf optical properties were tested for sugar maple (Acer saccharum) in the middle of its fourth growing season under treatment. The saplings had been growing since 1994 in open-top chambers and partial shade at Oak Ridge, Tennessee under the following treatments: (1) ambient CO2 pressure and air temperature (control); (2) CO2 pressure approximately 30 Pa above ambient; (3) air temperatures 3 degrees C above ambient; and (4) elevated CO2 and air temperature. Under elevated CO2 or temperature, spectral reflectance, transmittance and absorptance in the visible spectrum (400-720 nm) tended to change in patterns that generally are associated with chlorosis, with maximum differences from the control near 700 nm. However, these changes were not significant at P = 0.05. Although reflectance, transmittance and absorptance at 700 nm correlated strongly with leaf chlorophyll concentration, variability in chlorophyll concentration was greater within than among treatments. The lack of treatment effects on pigmentation explained the non-significant change in optical properties in the visible spectrum. Optical properties in the near-infrared (721-850 nm) were similarly unresponsive to treatment with the exception of an increased absorptance throughout the 739-850 nm range in leaves that developed under elevated air temperature alone. This response might have resulted from effects of air temperature on leaf internal structure. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Earth Syst Sci Off, Stennis Space Ctr, MS 39529 USA. Mississippi Valley State Univ, Itta Bena, MS 38941 USA. Oak Ridge Natl Lab, Div Environm Sci, Oak Ridge, TN 37831 USA. RP Carter, GA (reprint author), NASA, Earth Syst Sci Off, Room 212,Bldg 1100, Stennis Space Ctr, MS 39529 USA. RI Norby, Richard/C-1773-2012 OI Norby, Richard/0000-0002-0238-9828 NR 32 TC 11 Z9 14 U1 0 U2 9 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0098-8472 J9 ENVIRON EXP BOT JI Environ. Exp. Bot. PD JUN PY 2000 VL 43 IS 3 BP 267 EP 273 DI 10.1016/S0098-8472(00)00048-4 PG 7 WC Plant Sciences; Environmental Sciences SC Plant Sciences; Environmental Sciences & Ecology GA 320LJ UT WOS:000087402400008 ER PT J AU Lang, HR Baloga, SM AF Lang, HR Baloga, SM TI Validating airborne visible-infrared imaging spectrometer data at Ray Mine, Arizona SO ENVIRONMENTAL & ENGINEERING GEOSCIENCE LA English DT Article DE imaging spectroscopy; validation; acid mine drainage; field and laboratory spectra; AVIRIS; Ray Mine; Arizona; mineral mapping AB The fundamental promise of imaging spectroscopy is to provide surface mineralogy based on remotely-acquired, gridded reflectance spectra of comparable quality to those from high resolution laboratory and field spectrometers. For regulatory and environmental monitoring, validating imaging spectrometer data is a major issue with this emerging technology. In this paper we validate 1997 Airborne Visible-Infared Imaging Spectrometer (AVIRIS) reflectance spectra covering 0.4 mum-2.4 pm at a stable, flat, manmade target at Ray Mine, Arizona, for EPA/NASA assessment of the utility of remote sensing for monitoring acid drainage from an active open pit copper mine. For validation, we a) compare qualitatively, laboratory and field reflectance spectra with corresponding AVIRIS spectra; b) compare quantitatively, mineralogically diagnostic statistics from field spectra with the same statistics from AVIRIS spectra; and c) demonstrate a methodology for validating imaging spectrometer data for environmental applications. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Proxemy Res, Laytonsville, MD 20882 USA. RP Lang, HR (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 24 TC 2 Z9 2 U1 1 U2 5 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 SUM PY 2000 VL 6 IS 3 BP 187 EP 200 PG 14 WC Engineering, Environmental; Engineering, Geological; Geosciences, Multidisciplinary SC Engineering; Geology GA 383ZF UT WOS:000165914000001 ER PT J AU Carls, MG Hose, JE Thomas, RE Rice, SD AF Carls, MG Hose, JE Thomas, RE Rice, SD TI Exposure of Pacific herring to weathered crude oil: Assessing effects on ova SO ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY LA English DT Article DE Pacific herring; gametes; larvae; polynuclear aromatic hydrocarbons; Exxon Valdez oil spill ID EXXON-VALDEZ OIL; PRINCE-WILLIAM-SOUND; LIFE-HISTORY STAGES; PETROLEUM-HYDROCARBONS; CLUPEA-PALLASI; ATLANTIC CROAKER; SPILL; LARVAE; ALASKA; BENZOPYRENE AB In order to determine if exposure to Exxon Valdez oil would adversely affect progeny, reproductively mature Pacific herring were confined in water contaminated with weathered crude oil. Progeny were generally not affected by a 16-d parental exposure to initial aqueous concentrations of less than or equal to 58 mu g/L total polynuclear aromatic hydrocarbons (PAHs), yielding concentrations of up to 9.7 mu g/g in ova. In contrast, previous research indicated that a 16-d direct exposure of herring eggs to similarly weathered oil was detrimental to developing embryos at total initial PAH concentrations of 9 mu g/L. Progeny of exposed fish could have been insulated from toxic effects for two reasons. First, as an apparent result of partitioning and metabolism in parental tissues, lower concentrations and less toxic PAHs were preferentially accumulated by ova (primarily naphthalenes; 84-92%). Second, peak exposure concentrations occurred before cell differentiation. The opposite was true for directly exposed eegs; the more toxic multi-ring PAHs (e.g., phenanthrenes and chrysenes) and alkyl-substituted homologues were accumulated, and internal concentrations increased during cell division, differentiation, and organ development. Thus, Pacific herring embryos are more critically sensitive to oil pollution than are gametes. C1 Natl Ocean & Atmospher Adm, Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Auke Bay Lab, Juneau, AK 99801 USA. Occidental Coll, Los Angeles, CA 90041 USA. Calif State Univ Los Angeles, Dept Biol Sci, Chico, CA 91708 USA. RP Carls, MG (reprint author), Natl Ocean & Atmospher Adm, Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Auke Bay Lab, 11305 Glacier Highway, Juneau, AK 99801 USA. NR 39 TC 11 Z9 11 U1 1 U2 11 PU SETAC PI PENSACOLA PA 1010 NORTH 12TH AVE, PENSACOLA, FL 32501-3367 USA SN 0730-7268 J9 ENVIRON TOXICOL CHEM JI Environ. Toxicol. Chem. PD JUN PY 2000 VL 19 IS 6 BP 1649 EP 1659 DI 10.1897/1551-5028(2000)019<1649:EOPHTW>2.3.CO;2 PG 11 WC Environmental Sciences; Toxicology SC Environmental Sciences & Ecology; Toxicology GA 318CZ UT WOS:000087267500024 ER PT J AU Stehlik, LL Meise, CJ AF Stehlik, LL Meise, CJ TI Diet of winter flounder in a New Jersey estuary: Ontogenetic change and spatial variation SO ESTUARIES LA English DT Article ID PLAICE PLEURONECTES-PLATESSA; NEW-YORK BIGHT; PSEUDOPLEURONECTES-AMERICANUS; HIPPOGLOSSOIDES-PLATESSOIDES; PASSAMAQUODDY BAY; NEW-BRUNSWICK; DAILY RATION; FOOD; NEWFOUNDLAND; MOVEMENTS AB Juvenile and adult winter flounder, Pseudopleuronectes americanus Walbaum (Pleuronectidae), from the Navesink River and Sandy Hook Bay, New Jersey, U.S., were examined for ontogenetic, seasonal, and spatial variation in dietary content. Fish (n = 1291 non-empty) were placed by cluster analysis of dietary content into three size groups: 15-49, 50-299, and greater than or equal to 300 mm total length. Clear ontogenetic patterns were revealed, in particular the disappearance of calanoid copepods from the diet as fish grew >50 mm and an increase in number of taxa in the diet with growth. Fish in size group 1 fed upon spionid polychaetes, the calanoid copepod Eurytemora affinis, and ampeliscid amphipods. Fish in size group 2 added various species of polychaetes, amphipods, and siphons of the bivalve Mya arenaria to their diets. Size group 2 was present during all months of the survey, but only minor seasonal differences in their diet were apparent. One obvious change was the increase in consumption of the shrimp Crangon septemspinosa in summer and fall. Size group 3 fish, collected mainly in fall, ate large volumes of M. arenaria and glycerid polychaetes. Cluster analysis showed a large-scale spatial pattern in diet among fish of size group 1, related to the presence of E. affinis in winter flounder diets in the river and a marsh cove in the bay. Small-scale spatial differences in diets of fish in size group 2 were possibly related to prey distribution. C1 Natl Marine Fisheries Serv, US Dept Commerce, NOAA,NE Fisheries Sci Ctr, James J Howard Marine Sci Lab, Highlands, NJ 07732 USA. RP Stehlik, LL (reprint author), Natl Marine Fisheries Serv, US Dept Commerce, NOAA,NE Fisheries Sci Ctr, James J Howard Marine Sci Lab, Highlands, NJ 07732 USA. NR 49 TC 45 Z9 48 U1 0 U2 1 PU ESTUARINE RES FEDERATION PI LAWRENCE PA PO BOX 368, LAWRENCE, KS 66044 USA SN 0160-8347 J9 ESTUARIES JI Estuaries PD JUN PY 2000 VL 23 IS 3 BP 381 EP 391 DI 10.2307/1353330 PG 11 WC Environmental Sciences; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 333AG UT WOS:000088106100009 ER PT J AU Milesi, S Capelli, C Denoth, J Hutchinson, T Stussi, E AF Milesi, S Capelli, C Denoth, J Hutchinson, T Stussi, E TI Effects of 17 days bedrest on the maximal voluntary isometric torque and neuromuscular activation of the plantar and dorsal flexors of the ankle SO EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE bedrest; electromyography; maximal voluntary isometric contraction maximal isometric torque; muscle atrophy; plantar and dorsal flexor of the ankle ID BED REST; MUSCLE STRENGTH; LIMB SUSPENSION; JOINT POSITION; HUMANS; ADAPTATIONS; EXERCISE; POWER; ELECTROMYOGRAPHY AB Maximal voluntary isometric torque values of the ankle plantar (T-im,T-PF) and dorsal flexors (T-im,T-DF) were assessed in eight healthy adult males at 5 degrees and 15 degrees of dorsal flexion (DF) and at 5 degrees, 15 degrees and 25 degrees of plantar flexion (PF) with the knee at right angles, before (two times), during (three times) and after (three times) 17 days of 6 degrees head-down tilt bedrest (BR). Integrated electromyograms (iEMG) were also recorded from the gastrocnemius medialis and tibialis anterior. T-im,T-PF and the iEMG of the gastrocnemius medialis were significantly larger (by 14% and by 27%, respectively) at the end of recovery than before BR. This was probably the consequence of training and/or habituation leading to: (1) increased activation of the plantar flexors and (2) decreased co-activation of the antagonist muscles. Neither T-im,T-DF nor the tibialis anterior iEMG changed significantly. The effects of BR on muscle performance were evaluated as follows. The net torque generated by a given muscle group was assumed to be the algebraic sum of the torque generated by the agonists and by the antagonists. Thus, for the plantar flexors T-im,T-PF = alpha iEMG(Gm) - beta iEMG(Ta), where: (1) iEMG(Gm) and iEMG(Ta) are the iEMGs of gastrocnemius medialis and of tibialis anterior during maximal PF; and (2) the constants alpha and beta represent the electromechanical coupling of the plantar (a) and dorsal (beta) flexors. Similarly for the dorsal flexors: T-im,T-DF = beta iEMG(Ta) - alpha iEMG(Gm), where iEMG(Ta) and iEMG(Gm) are the iEMGs of tibialis anterior and gastrocnemius medialis during maximal DF. Torque and iEMG values were assessed for all subjects under all experimental conditions. Thus, since the biomechanical leverage of the system was constant, alpha and beta could be calculated. During BR, alpha decreased by 25% and it dropped by a further 30% during recovery. In contrast, beta remained almost unchanged. This suggests that, in spite of training and/or habituation, BR significantly impaired the maximal isometric performance of the plantar flexors, an effect that continued during the initial 10 days of recovery. C1 Fac Med & Chirurg, Dipartimento Sci & Tecnol Biomed, I-33100 Udine, Italy. ETH Zurich, Dept Mat, Biomech Lab, CH-8952 Schlieren, Switzerland. NASA, Ames Res Ctr, Gravitat Res Branch, Moffett Field, CA 94035 USA. RP Milesi, S (reprint author), Fac Med & Chirurg, Dipartimento Sci & Tecnol Biomed, Piazzale Kolbe 4, I-33100 Udine, Italy. OI Capelli, Carlo/0000-0002-3278-1337 NR 32 TC 10 Z9 10 U1 0 U2 2 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 1439-6319 J9 EUR J APPL PHYSIOL JI Eur. J. Appl. Physiol. PD JUN PY 2000 VL 82 IS 3 BP 197 EP 205 DI 10.1007/s004210050672 PG 9 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 335FF UT WOS:000088232600005 PM 10929213 ER PT J AU Arnedo, A Decoster, N Roux, SG AF Arnedo, A Decoster, N Roux, SG TI A wavelet-based method for multifractal image analysis. I. Methodology and test applications on isotropic and anisotropic random rough surfaces SO EUROPEAN PHYSICAL JOURNAL B LA English DT Review ID FRACTIONAL BROWNIAN-MOTION; FULLY-DEVELOPED TURBULENCE; LONG-RANGE CORRELATIONS; LOG-NORMAL STATISTICS; SINGULARITY SPECTRUM; FRACTAL SIGNALS; DNA-SEQUENCES; OSCILLATING SINGULARITIES; STRANGE ATTRACTORS; MULTIPLICATIVE PROCESSES AB We generalize the so-called wavelet transform modulus maxima (WTMM) method to multifractal image analysis. We show that the implementation of this method provides very efficient numerical techniques to characterize statistically the roughness fluctuations of fractal surfaces. We emphasize the wide range of potential applications of this wavelet-based image processing method in fundamental as well as applied sciences. This paper is the first one of a series of three articles. It is mainly devoted to the methodology and to test applications on random self-affine surfaces (e.g., isotropic fractional Brownian sufaces and anisotropic monofractal rough surfaces). Besides its ability to characterize point-wise regularity, the WTMM method is definitely a multiscale edge detection method which can be equally used for pattern recognition, detection of contours and image denoising. Paper II (N. Decoster, S.G. Roux, A. Arneodo, to be published in Fur. Phys. J. B 15 (2000)) will be devoted to some applications of the WTMM method to synthetic multifractal rough surfaces. In paper III (S.G. Roux, A. Arneodo, N. Decoster, to be published in fur. Phys. J. 15 (2000)), we will report the results of a comparative experimental analysis of high-resolution satellite images of cloudy scenes. C1 Ctr Rech Paul Pascal, F-33600 Pessac, France. NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. RP Ctr Rech Paul Pascal, Ave A Schweitzer, F-33600 Pessac, France. EM arneodo@crpp.u-bordeaux.fr NR 171 TC 88 Z9 92 U1 2 U2 10 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 1434-6028 EI 1434-6036 J9 EUR PHYS J B JI Eur. Phys. J. B PD JUN PY 2000 VL 15 IS 3 BP 567 EP 600 DI 10.1007/s100510051161 PG 34 WC Physics, Condensed Matter SC Physics GA 326GY UT WOS:000087726100021 ER PT J AU Decoster, N Roux, SG Arneodo, A AF Decoster, N Roux, SG Arneodo, A TI A wavelet-based method for multifractal image analysis. II. Applications to synthetic multifractal rough surfaces SO EUROPEAN PHYSICAL JOURNAL B LA English DT Review ID FULLY-DEVELOPED TURBULENCE; REYNOLDS-NUMBER TURBULENCE; PROBABILITY DENSITY-FUNCTIONS; FRACTIONAL BROWNIAN-MOTION; LOG-POISSON STATISTICS; VELOCITY STATISTICS; RANDOM CASCADES; SPATIAL CORRELATIONS; FRACTAL SIGNALS; SCALING LAWS AB We apply the 2D wavelet transform modulus maxima (WTMM) method to synthetic random multifractal rough surfaces. We mainly focus on two specific models that are, a priori, reasonnable candidates to simulate cloud structure in paper III (S.G. Roux, A. Ameodo, N. Decoster, fur. Phys. J. B 15. 765 (2000)). As originally proposed by Schertaer and Lovejoy, the first one consists in a simple power law filtering (known in the mathematical literature as "fractional integration") of singular cascade measures. The second one is the foremost attempt to generate log-infinitely divisible cascades on 2D orthogonal wavelet basis. We report numerical estimates of the tau(q) and D(h) multifractal spectra which are in very good agreement with the theoretical predictions. We emphasize the 2D WTMM method as a very efficient tool to resolve multifractal scaling. But beyond the statistical information provided by the multifractal description, there is much more to learn from the arborescent structure of the wavelet transform skeleton of a multifractal rough surface. Various statistical quantities such as the self-similarity kernel and the spacescale correlation functions can be used to characterize very precisely the possible existence of an underlying multiplicative process. We elaborate theoretically and test numerically on various computer synthetized images that these statistical quantities can be directly extracted from the considered multifractal function using its WTMM skeleton with an arbitrary analyzing wavelets. This study provides algorithms that are readily applicable to experimental situations. C1 Ctr Rech Paul Pascal, F-33600 Pessac, France. NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. RP Ctr Rech Paul Pascal, Ave A Schweitzer, F-33600 Pessac, France. EM arneodo@crpp.u-bordeaux.fr NR 108 TC 42 Z9 42 U1 2 U2 10 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 1434-6028 EI 1434-6036 J9 EUR PHYS J B JI Eur. Phys. J. B PD JUN PY 2000 VL 15 IS 4 BP 739 EP 764 DI 10.1007/s100510051179 PG 26 WC Physics, Condensed Matter SC Physics GA 332WZ UT WOS:000088098500018 ER PT J AU Roux, SG Arneodo, A Decoster, N AF Roux, SG Arneodo, A Decoster, N TI A wavelet-based method for multifractal image analysis. III. Applications to high-resolution satellite images of cloud structure SO EUROPEAN PHYSICAL JOURNAL B LA English DT Review ID FULLY-DEVELOPED TURBULENCE; REYNOLDS-NUMBER TURBULENCE; LIQUID WATER DISTRIBUTIONS; LOG-NORMAL STATISTICS; MARINE STRATOCUMULUS; RADIATIVE-TRANSFER; SCALE-INVARIANCE; SELF-SIMILARITY; PRESSURE-FLUCTUATIONS; VELOCITY STATISTICS AB We apply the 2D wavelet transform modulus maxima (WTMM) method to high-resolution LANDSAT satellite images of cloudy scenes. The computation of the tau(q) and D(h) multifractal spectra for both the optical depth and the radiance fields confirms the relevance of the multifractal description to account for the intermittent nature of marine stratocumulus clouds. When assisting the 2D WTMM method by the wavelet based deconvolution method designed to compute the self-similarity kernel, we show that our numerical tools are very efficient to disentangle the anisotropic texture induced by the presence of convective rolls from the background radiance fluctuations which are likely to display isotropic scale invariance. Moreover, this analysis reveals that with the available set of experimental data, there is no way to discriminate between various phenomenological cascade models recently proposed to account fur intermittency and their log-normal approximations. When further investigating the "two-point" space-scale correlation functions, we bring definite proof of the existence of an underlying multiplicative structure from an "integral" coarsest scale which is given by the characteristic width of the convective patterns. We emphasize the log-normal random W-cascade model on separable wavelet orthogonal basis introduced in paper II (N. Decoster, S.G. Roux, A. Ameodo, Fur. Phys. J. B 15, 739 (2000)), as a very attractive model (at least as: compared to the models commonly used in the literature) of the cloud architecture. Finally, we comment on the multifractal properties of marine stratocumulus radiance fields comparatively to previous experimental analysis of velocity and temperature fluctuations in high Reynolds number turbulence. C1 Ctr Rech Paul Pascal, F-33600 Pessac, France. NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. RP Ctr Rech Paul Pascal, Ave A Schweitzer, F-33600 Pessac, France. EM arneodo@crpp.u-bordeaux.fr NR 122 TC 48 Z9 48 U1 1 U2 9 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 1434-6028 EI 1434-6036 J9 EUR PHYS J B JI Eur. Phys. J. B PD JUN PY 2000 VL 15 IS 4 BP 765 EP 786 DI 10.1007/s100510051180 PG 22 WC Physics, Condensed Matter SC Physics GA 332WZ UT WOS:000088098500019 ER PT J AU Walker, RV Myers, KW Davis, ND Aydin, KY Friedland, KD Carlson, HR Boehlert, GW Urawa, S Ueno, Y Anma, G AF Walker, RV Myers, KW Davis, ND Aydin, KY Friedland, KD Carlson, HR Boehlert, GW Urawa, S Ueno, Y Anma, G TI Diurnal variation in thermal environment experienced by salmonids in the North Pacific as indicated by data storage tags SO FISHERIES OCEANOGRAPHY LA English DT Article DE Bering Sea; data storage tags; North Pacific; Pacific salmon; steelhead trout; tagging effects; thermal habitat ID ADULT SOCKEYE SALMON; VERTICAL MOVEMENTS; ONCORHYNCHUS-NERKA; BRITISH-COLUMBIA; ULTRASONIC TELEMETRY; COASTAL WATERS; CHUM SALMON; BEHAVIOR; TSHAWYTSCHA; MIGRATIONS AB Eight temperature-recording data storage tags were recovered from three salmonids in Alaska (pink and coho salmon and steelhead trout) and five chum salmon in Japan after 21-117 days, containing the first long-term records of ambient temperature from Pacific salmonids migrating at sea. Temperature data imply diel patterns of descents to deeper, cooler water and ascents to the surface. Fish were found at higher average temperatures at night, with narrower temperature ranges and fewer descents than during the day. Fish tagged in the Gulf of Alaska were at higher temperatures on average (10-12 degrees C) than chum salmon tagged in the Bering Sea (8-10 degrees C). Chum salmon were also found at a wider range of temperatures (-1-22 degrees C vs 5-15 degrees C). This is probably related both to the different oceanographic regions through which the fish migrated, as well as species differences in thermal range and vertical movements. Proportions of time that individual fish spent at different temperatures seemed to vary among oceanographic regions. Steelhead trout may descend to moderate depths (50 m) and not be limited to the top few metres, as had been believed. Japanese chum salmon may seek deep, cold waters as they encounter warm surface temperatures on their homeward migrations. Temperature data from all fish showed an initial period (4-21 days) of day and night temperatures near those of sea surface temperatures, suggesting a period of recuperation from tagging trauma. A period of tagging recuperation suggests that vertical movement data from short-term ultrasonic telemetry studies may not represent normal behaviour of fish. The considerable diurnal and shorter-term variation in ambient temperatures suggests that offshore ocean distribution may be linked more to prey distribution and foraging than to sea surface temperatures. C1 Univ Washington, Sch Fisheries, Fisheries Res Inst, Seattle, WA 98195 USA. Univ Massachusetts, NOAA, CMER Program, Amherst, MA 01003 USA. Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Auke bay Lab, Juneau, AK 99801 USA. Natl Marine Fisheries Serv, SW fisheries Sci Ctr, Pacific Fisheries Environm Lab, Pacific Grove, CA 93950 USA. Fisheries Agcy Japan, Natl Salmon Resources Ctr, Sapporo, Hokkaido 0620922, Japan. Fisheries Agcy Japan, Natl Res Inst Far Seas Fisheries, Shizuoka 4248633, Japan. Hokkaido Univ, Fac Fisheries, Hakodate, Hokkaido 0418611, Japan. RP Walker, RV (reprint author), Univ Washington, Sch Fisheries, Fisheries Res Inst, Box 355020, Seattle, WA 98195 USA. NR 36 TC 57 Z9 61 U1 0 U2 13 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 1054-6006 J9 FISH OCEANOGR JI Fish Oceanogr. PD JUN PY 2000 VL 9 IS 2 BP 171 EP 186 DI 10.1046/j.1365-2419.2000.00131.x PG 16 WC Fisheries; Oceanography SC Fisheries; Oceanography GA 346RT UT WOS:000088885400005 ER PT J AU Bogard, DD Garrison, DH McCoy, TJ AF Bogard, DD Garrison, DH McCoy, TJ TI Chronology and petrology of silicates from IIE iron meteorites: Evidence of a complex parent body evolution SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID RAY PRODUCTION-RATES; ORDINARY CHONDRITES; COSMOGENIC NUCLIDES; RB-87-SR-87 METHOD; OXYGEN-ISOTOPE; NOBLE-GASES; I-XE; AGES; ACHONDRITES; ORIGIN AB IIE iron meteorites contain silicate inclusions the characteristics of which suggest a parent body similar to that of H-chondrites. However, these silicates show a wide range of alteration, ranging from Netschaevo and Techado, the inclusions of which are little altered, to highly differentiated silicates like those in Kodaikanal, Weekeroo Station, and Colomera, which have lost metal and sulfur and are enriched in feldspar, We find these inclusions to show varying degrees of shock alteration. We made Ar-39-Ar-40 age determinations of Watson, Techado, Miles, Colomera, and Sombrerete. Watson has an Ar-Ar age of 3.677 +/- 0.007 Gyr, similar to previously reported ages for Kodaikanal and Netschaevo. We suggest that the various determined radiometric ages of these three meteorites were probably reset by a common impact event. The space exposure ages for these three meteorites are also similar to each other and are considerably younger than exposure ages of other IIEs, Ar-39-Ar-40 ages inferred for the other four meteorites analyzed are considerably older than Watson and are: Techado = 4.49 +/- 0.01 Gyr, Miles = 4.405 +/- 0.012 Gyr, Colomera = 4.470 +/- 0.010 Gyr, and Sombrerete = 4.541 +/- 0.0012 Gyr. These ages are in fair agreement with previously reported Rb-Sr isochron ages for Colomera and Weekeroo Station. Although several mechanisms to form IIE meteorites have been suggested, it is not obvious that a single mechanism could produce a suite of meteorites with very different degrees of silicate differentiation and with isotopic ages that differ by >0.8 Gyr. We suggest that those IIEs with older isotopic ages are a product of partial melting and differentiation within the parent body, followed by mixing of silicate and metal while both were relatively hot. Netschaevo and Watson may have formed by this same process or by impact mixing similar to 4.5 Gyr ago, but their isotopic ages may have been subsequently reset by shock heating. Kodaikanal apparently is required to have formed more recently, in which case impact melting and differentiation seems the only viable process. We see no compelling reasons to believe that IIE silicate and metal derived from different parent bodies or that the parent body of IIEs was the same as that of H-chondrites. Copyright (C) 2000 Elsevier Science Ltd. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin Engn, Houston, TX 77058 USA. Smithsonian Inst, Natl Museum Nat Hist, Dept Mineral Sci, Washington, DC 20560 USA. RP Bogard, DD (reprint author), NASA, Lyndon B Johnson Space Ctr, SN2, Houston, TX 77058 USA. NR 76 TC 44 Z9 44 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD JUN PY 2000 VL 64 IS 12 BP 2133 EP 2154 DI 10.1016/S0016-7037(00)00355-0 PG 22 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 329WH UT WOS:000087931100009 ER PT J AU Sarch, MT Birkett, C AF Sarch, MT Birkett, C TI Fishing and farming at Lake Chad: Responses to lake-level fluctuations SO GEOGRAPHICAL JOURNAL LA English DT Article DE Africa; Lake Chad; lake-level fluctuations; remote sensing; participatory research; agricultural development; rural development; flood warnings ID NIGERIA AB Lake Chad lies at the southern extreme of the Sahara Desert and is well known for large fluctuations in its surface area this century. Seasonal fluctuations, however, have received much less attention. This paper presents the results of two complimentary research efforts on the south-west shore of the lake. These illustrate how important both inter and intra-annual fluctuations in the level of the lake are, both in terms of their impact on the environment and in the response of the communities living on the lake shore. The paper compares a time series of the fluctuations in the level of Lake Chad as monitored by the TOPEX/POSEIDON satellite with findings from participatory research with the communities of the south-west lake shore. It shows how the communities of the lake have responded to lake-level fluctuations with their livelihood choices. These results are used to show that although vastly different in scope, a high degree of complimentarity exists between remotely-sensed information and community-based research and that they are of potentially great value to development initiatives on the shores of Lake Chad. C1 Middlesex Univ, Flood Hazard Res Ctr, Enfield EN3 4SF, Middx, England. NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. RP Sarch, MT (reprint author), Middlesex Univ, Flood Hazard Res Ctr, Enfield EN3 4SF, Middx, England. NR 55 TC 30 Z9 33 U1 1 U2 8 PU ROYAL GEOGRAPHICAL SOC PI LONDON PA 1 KENSINGTON GORE, LONDON SW7 2AR, ENGLAND SN 0016-7398 J9 GEOGR J JI Geogr. J. PD JUN PY 2000 VL 166 BP 156 EP 172 DI 10.1111/j.1475-4959.2000.tb00015.x PN 2 PG 17 WC Geography SC Geography GA 335KK UT WOS:000088242500004 ER PT J AU Kletetschka, G AF Kletetschka, G TI Intense remanence of hematite-ilmenite solid solution SO GEOLOGICA CARPATHICA LA English DT Article; Proceedings Paper CT 7th Scientific Meeting on New Trends Geomagnetism CY JUN 19-SEP 25, 2000 CL MORAVANY CASTLE, SLOVAKIA SP Acad Sci Czech Republ, Acad Sci Slovak Repub DE hematite-ilmenite solid solution; intense magnetic signature C1 NASA, NRC, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kletetschka, G (reprint author), NASA, NRC, Goddard Space Flight Ctr, Code 691, Greenbelt, MD 20771 USA. RI Kletetschka, Gunther/C-9996-2011 OI Kletetschka, Gunther/0000-0002-0645-9037 NR 0 TC 3 Z9 3 U1 0 U2 7 PU SLOVAK ACADEMIC PRESS LTD PI BRATISLAVA PA PO BOX 57 NAM SLOBODY 6, 810 05 BRATISLAVA, SLOVAKIA SN 1335-0552 J9 GEOL CARPATH JI Geol. Carpath. PD JUN PY 2000 VL 51 IS 3 BP 187 EP 187 PG 1 WC Geosciences, Multidisciplinary SC Geology GA 327PR UT WOS:000087802400029 ER PT J AU Whang, YC Burlaga, LF AF Whang, YC Burlaga, LF TI Anticipated Voyager crossing of the termination shock SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ANOMALOUS COSMIC-RAYS; SOLAR-WIND; DISTANT HELIOSPHERE; OUTER HELIOSPHERE; PICKUP IONS; MOTION; MODEL AB This paper studies the varying location and conditions of the termination shock over 34-year period (1966 - 2000). The shock location is anti-correlated with the sunspot number, moving inward or outward during the rising or declining phase of the solar cycle. For the shock in the upwind direction, plasma and magnetic field conditions in its immediately upstream are extrapolated from 1 AU data using MHD equations including pickup protons, and the shock location estimated by the ACR spectrum is used as a guide. Voyager 1 will cross the termination shock in the region of high-speed solar wind at latitude of similar to 34 degrees. Taking into consideration the high-latitude effects,the calculation indicates that the shock is now moving inward to within 85 AU. Voyager 1 could cross the shock before Year 2002, and the crossing may occur 3 or more times over a period of about 4 years. C1 Catholic Univ Amer, Dept Mech Engn, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Whang, YC (reprint author), Catholic Univ Amer, Dept Mech Engn, Washington, DC 20064 USA. NR 23 TC 23 Z9 23 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 JUN 1 PY 2000 VL 27 IS 11 BP 1607 EP 1610 DI 10.1029/2000GL003748 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 320GU UT WOS:000087394100011 ER PT J AU Winterhalter, D Smith, EJ Neugebauer, M Goldstein, BE Tsurutani, BT AF Winterhalter, D Smith, EJ Neugebauer, M Goldstein, BE Tsurutani, BT TI The latitudinal distribution of solar wind magnetic holes SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MIRROR-MODE STRUCTURES; PLASMA OBSERVATIONS; INSTABILITY; MECHANISM; FIELD AB Using the fast latitude scan period of the Ulysses spacecraft, the occurrence of magnetic holes in the solar wind is investigated from -80 degrees to +80 degrees hello-latitude. Near the ecliptic, the large average value and the large variations of the hole count rate appear to be correlated with interaction regions. It is found, however, that at 30 degrees north and south latitude, approximately, the hole count rate drops to about 10% of that in the low latitude region and stays constant at this level to near the poles. The small but non-zero hole count rate at high hello-latitudes indicates that these holes were formed by processes other than the large scale dynamic solar wind features operating in the ecliptic region. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Winterhalter, D (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 30 Z9 32 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 JUN 1 PY 2000 VL 27 IS 11 BP 1615 EP 1618 DI 10.1029/1999GL003717 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 320GU UT WOS:000087394100013 ER PT J AU Kallio, EI Pulkkinen, TI Koskinen, HEJ Viljanen, A Slavin, JA Ogilvie, K AF Kallio, EI Pulkkinen, TI Koskinen, HEJ Viljanen, A Slavin, JA Ogilvie, K TI Loading-unloading processes in the nightside ionosphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SUBSTORMS; MODEL AB The loading-unloading processes during magnetospheric substorms are examined using the 'IL index' from the IMAGE magnetometer chain together with solar wind and IMF data from the WIND spacecraft. The IL index is a local, midnight sector, AL index. Energy input throughout the substorm is evaluated by integrating the epsilon parameter from the start of the growth phase until the end of the substorm. Energy dissipated in the ionosphere is estimated by integrating the IL index from the substorm onset to the end of the substorm. We show that the best correlation with the energy dissipated in the ionosphere is given by the energy input to the system after the substorm onset. Hence, we con elude that the energy loaded during the growth phase is necessary for the magnetospheric reconfiguration before the substorm onset, but that the size of the substorm as measured by the IL index is mostly governed by the direct energy input during the expansion phase. C1 Finnish Meteorol Inst, FIN-00101 Helsinki, Finland. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kallio, EI (reprint author), Finnish Meteorol Inst, POB 503, FIN-00101 Helsinki, Finland. RI Slavin, James/H-3170-2012; Pulkkinen, Tuija/D-8403-2012; Koskinen, Hannu/B-4971-2017 OI Slavin, James/0000-0002-9206-724X; Pulkkinen, Tuija/0000-0002-6317-381X; Koskinen, Hannu/0000-0003-3839-6461 NR 12 TC 33 Z9 33 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 1 PY 2000 VL 27 IS 11 BP 1627 EP 1630 DI 10.1029/1999GL003694 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 320GU UT WOS:000087394100016 ER PT J AU Smirnov, A Holben, BN Savoie, D Prospero, JM Kaufman, YJ Tanre, D Eck, TF Slutsker, I AF Smirnov, A Holben, BN Savoie, D Prospero, JM Kaufman, YJ Tanre, D Eck, TF Slutsker, I TI Relationship between column aerosol optical thickness and in situ ground based dust concentrations over Barbados SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TROPICAL NORTH-ATLANTIC; MINERAL DUST; SAHARAN DUST; TRADE WINDS; TRANSPORT; LAYER; OCEAN AB Aerosol optical depth measurements over Barbados acquired through the AERONET network are analyzed. Optical depth shows a pronounced seasonal pattern, with a maximum observed during summer. The temporal trends of the sunphotometry data were similar to those of ground-based dust concentration measurements. A simple linear regression relationship has been established between mean monthly values of aerosol optical depth and dust concentrations (correlation coefficient r=0.93), which allows the estimation of optical depth for any specific time period when dust concentration measurements are available. The robustness of the regression was validated with an independent data set. C1 NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. Univ Miami, Div Marine & Atmospher Chem, Miami, FL 33152 USA. Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Miami, FL 33149 USA. NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. Univ Sci & Tech Lille Flandres Artois, Opt Atmospher Lab, Villeneuve Dascq, France. Raytheon ITSS Corp, Lanham, MD USA. RP Smirnov, A (reprint author), NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. RI Smirnov, Alexander/C-2121-2009; ECK, THOMAS/D-7407-2012; OI Smirnov, Alexander/0000-0002-8208-1304; Prospero, Joseph/0000-0003-3608-6160 NR 17 TC 59 Z9 62 U1 0 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 1 PY 2000 VL 27 IS 11 BP 1643 EP 1646 DI 10.1029/1999GL011336 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 320GU UT WOS:000087394100020 ER PT J AU Watson, KA Bass, RG AF Watson, KA Bass, RG TI Polymer synthesis via a Diels-Alder reaction between bis(isobenzofuran)s and bis(phenylacetylene)s containing preformed phthalimide rings SO HIGH PERFORMANCE POLYMERS LA English DT Article ID CYCLO-ADDITION REACTIONS; BENZOCYCLOBUTENE; BISISOBENZOFURAN; ISOBENZOFURANS; POLYIMIDES; DIENES AB Polymers have been prepared by the Diels-Alder reaction between novel bis(isobenzofuran)s and bis(phenylacetylene)s containing preformed phthalimide rings. The initial polymer undergoes a thermal rearrangement without volatile evolution that effectively prevents a retro Diels-Alder reaction from occurring. The polymers were soluble in common organic solvents such as chloroform. N-methyl-2-pyrrolidinone, N,N-dimethylacetamide and chlorinated aromatic solvents. The polymers exhibited glass transitions ranging from 251 to 359 degrees C and a 10% weight loss ranging from 451 to 486 degrees C in air and 482 to 520 degrees C in helium as determined by thermogravimetric analysis. This synthetic approach offers advantages over other Diels-Alder polymerizations since no volatile by-products are generated and a thermal rearrangement eliminates a retro Diels-Alder reaction. C1 Virginia Commonwealth Univ, Dept Chem, Richmond, VA 23284 USA. RP Watson, KA (reprint author), NASA, Langley Res Ctr, MS 226, Hampton, VA 23681 USA. NR 32 TC 6 Z9 6 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD JUN PY 2000 VL 12 IS 2 BP 299 EP 314 DI 10.1088/0954-0083/12/2/305 PG 16 WC Polymer Science SC Polymer Science GA 339JJ UT WOS:000088473700005 ER PT J AU Connell, JW Smith, JG Hergenrother, PM Rommel, ML AF Connell, JW Smith, JG Hergenrother, PM Rommel, ML TI Neat resin, adhesive and composite properties of reactive additive/PETI-5 blends SO HIGH PERFORMANCE POLYMERS LA English DT Article ID PHENYLETHYNYL AB FETI-5 (5000 g mol(-1)) is a relatively new adhesive and composite matrix that exhibits good processability and excellent properties. However in the fabrication of complex composite parts (i.e, skin stringer and support frames), better processability would offer distinct advantages, In an effort to improve the processability of PETI-5, a novel reactive additive was prepared and used to formulate blends. The reactive additive is a mixture of relatively simple phenylethynyl containing imides, As such, it exhibited solubility in a variety of solvents such as N-methyl-2-pyrrolidinone, a relatively low softening temperature (similar to 185 degrees C) and a low melt viscosity (similar to 0.1-0.3 Pa s at 250 degrees C). Neat resin blends prepared by physically mixing imide powders of the reactive additive and PETI-5 were thermally and rheologically characterized. Blends were also prepared by mixing NMP solutions of PETI-5 amide acid and the reactive additive (imide form). These solutions were subsequently used to prepare adhesive film and unidirectional carbon fibre tape using unsized IM7 fibre, The reactive additive/PETI-5 blends were used to fabricate titanium adhesive panels and composites under 0.54 MPa or less for 1 h at 350-371 degrees C. The effect of reactive additive content on the physical, rheological, adhesive and carbon fibre laminate properties was determined. One formulation exhibited a decrease in melt viscosity (i.e, improved processability) without effecting open hole compression, compression properties after impact or microcrack behaviour. The neat resin, adhesive and composite properties of these reactive additive/PETI-5 blends and their cured polymers will he discussed. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Northrop Grumman Corp, El Segundo, CA 90245 USA. RP Connell, JW (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 14 TC 17 Z9 22 U1 0 U2 7 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD JUN PY 2000 VL 12 IS 2 BP 323 EP 333 DI 10.1088/0954-0083/12/2/307 PG 11 WC Polymer Science SC Polymer Science GA 339JJ UT WOS:000088473700007 ER PT J AU Bottke, WF Rubincam, DP Burns, JA AF Bottke, WF Rubincam, DP Burns, JA TI Dynamical evolution of main belt meteoroids: Numerical simulations incorporating planetary perturbations and Yarkovsky thermal forces SO ICARUS LA English DT Article DE asteroids; asteroids, dynamics; celestial mechanics; meteoroids; meteorites; resonances ID SIZED ASTEROIDAL FRAGMENTS; ORDINARY CHONDRITES; PARENT BODY; TERRESTRIAL PLANETS; METEORITE DELIVERY; IRON-METEORITES; EXPOSURE AGES; LAGEOS ORBIT; RESONANCES; EARTH AB In the Yarkovsky effect, the recoil from asymmetric, reradiated thermal energy causes objects to undergo semimajor axis drift as a function of their spin, orbit, and material properties. We consider the role played by this mechanism in delivering meteoroids from parent bodies in the main belt to chaotic resonance zones where they can be transported to Earth-crossing orbits. Previous work has approximated the dynamical evolution of meteoroids via Yarkovsky forces, mostly through the use of the perturbations equation and simplified dynamics (e,g,, Monte Carlo codes). In this paper, we calculate more precise solutions by formulating the seasonal and diurnal variants of this radiation force and incorporating them into an efficient N-body integrator capable of tracking test bodies for tens of millions of years with all relevant planetary perturbations included, Tests of our code against published benchmarks and the perturbation equations verify its accuracy. Results from long-term numerical integration of meter-sized bodies started from likely meteoroid parent bodies (e,g,, 4 Vesta) indicate that dynamical evolution in the inner main belt can be complex. Chaotic effects produced by weaker planetary resonances allow many meteoroids to reach Mars-crossing orbits well before entering the 3: 1 mean-motion resonance with Jupiter or the nu(6) secular resonance. Outward-evolving meteoroids sometimes become captured in these weaker resonances, increasing e and/or i while a stays constant. Conversely, inward-evolving meteoroids frequently jump across mean-motion resonances with Jupiter, bypassing potential "escape hatches" from the main belt. Despite these effects, our simulations indicate that most stony meteoroids reach Earth-crossing orbits via the 3:1 or nu(6) resonance after tens of Myr of evolution in the main belt. These time scales correspond well to the measured cosmic ray exposure ages of chondrites and achondrites. The source of these meteorites, however, is less clear since Yarkovsky drift allows nearly any body in the main belt to add to the cumulate meteoroid flux. Our results suggest that small parent bodies dominate the meteoroid flux if the main belt size distribution at sub-km sizes is in collisional equilibrium, while big parent bodies dominate if observed population trends for km-sized bodies persist to smaller sizes. (C) 2000 Academic Press. C1 Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. NASA, Geodynam Branch, Terr Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Bottke, WF (reprint author), Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. RI Rubincam, David/D-2918-2012 NR 86 TC 78 Z9 78 U1 1 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 JUN PY 2000 VL 145 IS 2 BP 301 EP 331 DI 10.1006/icar.2000.6361 PG 31 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327KZ UT WOS:000087794200001 ER PT J AU Thomas, PC Joseph, J Carcich, B Clark, BE Veverka, J Miller, JK Owen, W Williams, B Robinson, M AF Thomas, PC Joseph, J Carcich, B Clark, BE Veverka, J Miller, JK Owen, W Williams, B Robinson, M TI The shape of Eros from NEAR imaging data SO ICARUS LA English DT Article ID MULTISPECTRAL IMAGER; ASTEROID 433-EROS; INVERSION; FLYBY AB Images obtained during the NEAR spacecraft flyby of 433 Eros in December 1998 reveal a curved object, of a mean size and shape close to those inferred from lightcurve and radar data. The resolution of the images was sufficient to identify landmarks and establish a surface-based coordinate system. (C) 2000 Academic Press. C1 Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Northwestern Univ, Dept Geol Sci, Evanston, IL 60208 USA. RP Thomas, PC (reprint author), Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. NR 19 TC 9 Z9 9 U1 0 U2 0 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 JUN PY 2000 VL 145 IS 2 BP 348 EP 350 DI 10.1006/icar.2000.6406 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327KZ UT WOS:000087794200003 ER PT J AU Mileikowsky, C Cucinotta, FA Wilson, JW Gladman, B Horneck, G Lindegren, L Melosh, J Rickman, H Valtonen, M Zheng, JQ AF Mileikowsky, C Cucinotta, FA Wilson, JW Gladman, B Horneck, G Lindegren, L Melosh, J Rickman, H Valtonen, M Zheng, JQ TI Natural transfer of viable microbes in space - 1. From Mars to Earth and Earth to Mars SO ICARUS LA English DT Article DE cosmic rays; cratering; exobiology; Mars; meteorites ID BACILLUS-SUBTILIS SPORES; ACID-SOLUBLE PROTEINS; DEOXYRIBONUCLEIC-ACID; EXTREME DRYNESS; DEINOCOCCUS-RADIODURANS; DNA; RESPONSES; SURVIVAL; EJECTION; CONDENSATION AB The possibility and probability of natural transfer of viable microbes from Mars to Earth and Earth to Mars traveling in meteoroids during the first 0.5 Ga and the following 4 Ga are investigated, including: radiation protection against the galactic cosmic ray nuclei and the solar rays; dose rates as a function of the meteorite's radial column mass (radius x density), combined with dose rates generated by natural radioactivity within the meteorite; and survival curves for some bacterial species using NASA's HZETRN transport code other factors affecting microbe survival: vacuum; central meteorite temperatures at launch, orbiting, and arrival; pressure and acceleration at launch; spontaneous DNA decay; metal ion migration mean sizes and numbers of unshocked meteorites ejected and percentage falling on Earth, using current semiempirical results viable flight times for the microbe species Bacillus subtilis and Deinococcus radiodurans R1 the approximate fraction of microbes (with properties like the two species studied) viably arriving on Earth out of those ejected from Mars during the period 4 Ga BP to the present time, and during the 700 Ma from 4.5 to 3.8 Ga. Similarly, from Earth to Mars. The conclusion is that if microbes existed or exist on Mars, viable transfer to Earth is not only possible but also highly probable, due to microbes' impressive resistance to the dangers of space transfer and to the dense traffic of billions of martian meteorites which have fallen on Earth since the dawn of our planetary system. Earth-to-Mars transfer is also possible but at a much lower frequency. (C) 2000 Academic Press. C1 Royal Inst Technol, Stockholm, Sweden. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NASA, Langley Space Res Ctr, Newport News, VA USA. Observ Cote Azur, F-06003 Nice, France. DLR, Cologne, Germany. Univ Lund, Lund Observ, S-22100 Lund, Sweden. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Uppsala Univ, Astron Observ, Uppsala, Sweden. Univ Turku, Observatory, SF-20500 Turku, Finland. RP Mileikowsky, C (reprint author), Royal Inst Technol, Stockholm, Sweden. NR 60 TC 212 Z9 216 U1 4 U2 32 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 JUN PY 2000 VL 145 IS 2 BP 391 EP 427 DI 10.1006/icar.1999.6317 PG 37 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327KZ UT WOS:000087794200007 PM 11543506 ER PT J AU Jarvis, KS Vilas, F Larson, SM Gaffey, MJ AF Jarvis, KS Vilas, F Larson, SM Gaffey, MJ TI JVI Himalia: New compositional evidence and interpretations for the origin of Jupiter's small satellites SO ICARUS LA English DT Article DE satellites; satellites, irregular; satellites, jovian; asteroids, spectrophotometry ID OUTER JOVIAN-SATELLITES; 8-COLOR ASTEROID SURVEY; GIANT PLANET FORMATION; SOLAR-SYSTEM; TROJAN ASTEROIDS; SPECTROSCOPY; EVOLUTION; BELT; INSTABILITY; PHOTOMETRY AB New narrowband spectrophotometric data of JVI Himalia support its C-type classification. Two spectra taken on successive nights are rotationally sampled. The new spectra confirm the presence of a weak absorption feature centered near 0.7 mu m attributed to oxidized iron in phyllosilicates, products of aqueous alteration. Evaluation of the UBV photometry of JVI Himalia and JVII Elara compared to the UBV photometry of C-class (and subclass) asteroids showing spectral evidence of the 0.7-mu m absorption feature, and the new spectra compared with ECAS photometry of B-, F-, and some C-class asteroids, suggests that JVI Himalia is an F-class asteroid, a subclass of the Cs, We propose that the parent body of the prograde outer jovian satellites originated as part of the dynamical Nysa asteroid family. Evolutionary models of the Jovian system are used to address the capture and dispersal of the irregular satellites. (C) 2000 Academic Press. C1 Lockheed Martin Space Operat, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Rensselaer Polytech Inst, Dept Earth & Environm Sci, Troy, NY USA. RP Jarvis, KS (reprint author), Lockheed Martin Space Operat, 2400 NASA Rd 1,C-23, Houston, TX 77058 USA. NR 43 TC 17 Z9 17 U1 0 U2 0 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 JUN PY 2000 VL 145 IS 2 BP 445 EP 453 DI 10.1006/icar.2000.6344 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327KZ UT WOS:000087794200009 ER PT J AU Simon-Miller, AA Conrath, B Gierasch, PJ Beebe, RF AF Simon-Miller, AA Conrath, B Gierasch, PJ Beebe, RF TI A detection of water ice on Jupiter with Voyager IRIS SO ICARUS LA English DT Article DE Jupiter, atmosphere; atmospheres, composition ID INFRARED OBSERVATIONS; ATMOSPHERE; VAPOR; ULTRAVIOLET; ABUNDANCE; CLOUDS AB Possible water ice spectral signatures have been detected on Jupiter using Voyager Infrared Interferometer Spectrometer and Radiometer (IRIS) spectra taken near closest approach of the Voyager 1 and 2 missions. Comparison with simultaneous imaging data shows that these IRIS footprints approximately correspond to locations on the planet where deep convection is suspected. Of the sample of 7500+ spectra, approximately l% show a water ice absorption feature near 44 mu m. The infrared optical depths of the absorption features, between 0.18 and 0,44, indicate that large amounts of ice particles need not be present to produce the observed spectral signature. The water ice clouds would have visible optical depths on the order of unity and would not be distinguishable above a thick ammonia cloud deck, which can have much larger visible optical depths. These thin clouds yield about 1 precipitable micrometer of water, comparable to Martian Tharsis Ridge clouds, (C) 2000 Academic Press. C1 Cornell Univ, Ithaca, NY 14853 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. New Mexico State Univ, Dept Astron, Las Cruces, NM 88003 USA. RP Simon-Miller, AA (reprint author), Cornell Univ, 326 Space Sci Bldg, Ithaca, NY 14853 USA. RI Simon, Amy/C-8020-2012 OI Simon, Amy/0000-0003-4641-6186 NR 24 TC 26 Z9 26 U1 0 U2 0 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 JUN PY 2000 VL 145 IS 2 BP 454 EP 461 DI 10.1006/icar.2000.6359 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327KZ UT WOS:000087794200010 ER PT J AU Meier, R Smith, BA Owen, TC Terrile, RJ AF Meier, R Smith, BA Owen, TC Terrile, RJ TI The surface of Titan from NICMOS observations with the Hubble Space Telescope SO ICARUS LA English DT Article DE Titan, surfaces; infrared observations; image processing ID ATMOSPHERE; IMAGES; TEMPERATURE; TROPOSPHERE; ASYMMETRY; AEROSOLS; THOLINS; ALBEDO; MODEL; HST AB From diffraction-limited images produced by the near-IR camera NICMOS aboard the Hubble Space Telescope we derived maps of Titan's surface in the methane windows near 1.1, 1.6, and 2.0 mu m. Each part of Titan's atmosphere and surface was imaged at least twice over a time period of 24 h to look for moving clouds. Despite careful analysis we found no evidence for cloud activity. On the contrary, we were able to reproduce most of the features identified by previous mapping efforts, indicating that the albedo landscape remained stable over several years and is most likely indigenous to the surface. At the 3 sigma level we confirmed two brightness peaks in the prominent, continent-sized bright feature on the leading side of Titan. Many smaller landmarks could be mapped, including distinct surface structures on the dark, trailing side of Titan. These rule out the presence of a single large ethane ocean on the "backside" of Titan. No obvious differences could be seen between the maps at different wavelengths, other than a gradual loss of spatial resolution due to the diffraction limit of the 2.4-m primary mirror. (C) 2000 Academic Press. C1 Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Meier, R (reprint author), Univ Hawaii, Inst Astron, 2680 Woodlawn Dr, Honolulu, HI 96822 USA. NR 32 TC 59 Z9 59 U1 0 U2 0 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 JUN PY 2000 VL 145 IS 2 BP 462 EP 473 DI 10.1006/icar.2000.6360 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327KZ UT WOS:000087794200011 ER PT J AU Nicholson, PD French, RG Tollestrup, E Cuzzi, JN Harrington, J Matthews, K Perkovic, O Stover, RJ AF Nicholson, PD French, RG Tollestrup, E Cuzzi, JN Harrington, J Matthews, K Perkovic, O Stover, RJ TI Saturn's rings I - Optical depth profiles from the 28 Sgr occultation SO ICARUS LA English DT Article DE planetary rings, Saturn; occultations ID PARTICLE-SIZE DISTRIBUTIONS; VOYAGER-1 RADIO OCCULTATION; F-RING; RESONANCE STRUCTURES; BENDING WAVES; B-RING; 28-SGR; FEATURES; IDENTIFICATION; WAVELENGTHS AB We present optical depth profiles for Saturn's rings at wavelengths of 0,9, 2.1, 3,3, and 3.9 mu m, obtained from the occultation of the star 28 Sgr on 3 July 1989 when the rings were near their maximum opening angle. The radial resolution of the data is similar to 18 km, as set by the angular diameter of the star. Very few, if any, structural changes are observed in the rings since the Voyager encounters in 1980/1981. Azimuthal variations in optical depth are restricted to the outermost part of the B Ring and to several previously known noncircular features. The mean optical depth in the heretofore unprobed central part of the B Ring is found to be 2.3 +/- 0.15 at 3.9 mu m. Quantitative comparisons of the optical depths with those measured by the Voyager PPS stellar occultation experiment at 0.27 mu m do reveal systematic differences between the major ring regions. In the C Ring, we find tau(28Sgr)/tau(PPS) similar or equal to 1.4, while in the B Ring and outer A Ring tau(28Sgr)/tau(PPS) similar or equal to 1.0. Only in the inner A Ring is tau(28Sgr) < tau(PPS) In agreement with previous studies at microwave and optical wavelengths, we conclude that there is very little evidence in the 28 Sgr data for a significant population of micrometer-sized particles anywhere in the main rings. Most of the observed variation in tau(28Sgr)/tau(PPS) can instead be attributed to variations in the particle size distribution in the rings in the centimeter to meter size range, which controls the angular width of the rings' forward-scattering cross section. This in turn controls the effective extinction efficiency for Earth-based occultation experiments, and thus the measured optical depth. In a companion paper we use these data to derive power-law models of the size distribution in each major ring region. (C) 2000 Academic Press. C1 Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. Wellesley Coll, Dept Astron, Wellesley, MA 02481 USA. Harvard Univ, Ctr Astrophys, Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. CALTECH, Palomar Observ, Pasadena, CA 91125 USA. Univ Calif Santa Cruz, Lick Observ, Santa Cruz, CA 95064 USA. RP Nicholson, PD (reprint author), Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. RI Harrington, Joseph/E-6250-2011; OI Harrington, Joseph/0000-0002-8955-8531 NR 60 TC 30 Z9 30 U1 0 U2 1 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 JUN PY 2000 VL 145 IS 2 BP 474 EP 501 DI 10.1006/icar.2000.6356 PG 28 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327KZ UT WOS:000087794200012 ER PT J AU Mischna, MA Kasting, JF Pavlov, A Freedman, R AF Mischna, MA Kasting, JF Pavlov, A Freedman, R TI Influence of carbon dioxide clouds on early martian climate SO ICARUS LA English DT Article DE Mars, climate; Mars, atmosphere; extrasolar planets ID EARLY MARS; EARLY EARTH; PLANETARY-ATMOSPHERES; CO2; ICE; ABSORPTION; WARM; WET AB Recent studies have shown that clouds made of carbon dioxide ice may have warmed the surface of early Mars by reflecting not only incoming solar radiation but upwelling IR radiation as well. However, these studies have not treated scattering self-consistently in the thermal TR. Our own calculations, which treat IR scattering properly, confirm these earlier calculations but show that CO2 clouds can also cool the surface, especially if they are low and optically thick. Estimating the actual effect of CO2 clouds on early martian climate will require three-dimensional models in which cloud location, height, and optical depth, as well as surface temperature and pressure, are determined self-consistently. Our calculations further confirm that CO2 clouds should extend the outer boundary of the habitable zone around a star but that there is still a finite limit beyond which above-freezing surface temperatures cannot be maintained by a CO2-H2O atmosphere. For our own Solar System, the absolute outer edge of the habitable zone is at similar to 2.4 AU, (C) 2000 Academic Press. C1 Penn State Univ, Dept Meteorol, University Pk, PA 16802 USA. Penn State Univ, Dept Geosci, University Pk, PA 16802 USA. NASA, Space Phys Res Inst, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Mischna, MA (reprint author), Penn State Univ, Dept Meteorol, 503 Walker Bldg, University Pk, PA 16802 USA. RI Pavlov, Alexander/F-3779-2012 OI Pavlov, Alexander/0000-0001-8771-1646 NR 19 TC 114 Z9 116 U1 0 U2 13 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 JUN PY 2000 VL 145 IS 2 BP 546 EP 554 DI 10.1006/icar.2000.6380 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327KZ UT WOS:000087794200016 PM 11543507 ER PT J AU Laughlin, G Adams, FC AF Laughlin, G Adams, FC TI The frozen Earth: Binary scattering events and the fate of the solar system SO ICARUS LA English DT Article DE stellar dynamics, stars and planetary systems ID SINGLE-STAR SCATTERING; MAIN-SEQUENCE; PLANETARY SYSTEM; ICE SHELL; STABILITY; EVOLUTION; MULTIPLICITY; BIOSPHERE; DIVERSITY; CALLISTO AB Planetary systems that encounter passing stars can experience severe orbital disruption, and the efficiency of this process is enhanced when the impinging systems are binary pairs rather than single stars. Using a Monte Carlo approach to perform more than 200,000 N-body integrations, we examine the ramifications of this scattering process for the long-term prospects of our own Solar System. After statistical processing of the results, we estimate an overall probability of order 2 x 10(-5) that Earth will find its orbit seriously disrupted prior to the emergence of a runaway greenhouse effect driven by the Sun's increasing luminosity. This estimate includes both direct disruption events and scattering processes that seriously alter the orbits of the jovian planets, which force severe changes upon the Earth's orbit. Our set of scattering experiments gives a number of other results. For example, there is about 1 chance in 2 million that Earth will be captured into orbit around another star before the onset of a runaway greenhouse effect. In addition, the odds of Neptune doubling its eccentricity are only one part in several hundred. We then examine the consequences of Earth being thrown into deep space. The surface biosphere would rapidly shut down under conditions of zero insolation, but the Earth's radioactive heat is capable of maintaining life deep underground, and perhaps in hydrothermal vent communities, for some time to come. Although unlikely for Earth, this scenario may be common throughout the universe, since many environments where liquid water could exist (e.g., Europa and Callisto) must derive their energy from internal (rather than external) heating. (C) 2000 Academic Press. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA. RP Laughlin, G (reprint author), NASA, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. NR 46 TC 25 Z9 25 U1 0 U2 0 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 JUN PY 2000 VL 145 IS 2 BP 614 EP 627 DI 10.1006/icar.2000.6355 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327KZ UT WOS:000087794200022 ER PT J AU Gaidos, EJ AF Gaidos, EJ TI A cosmochemical determinism in the formation of Earth-like planets SO ICARUS LA English DT Article DE cosmochemistry; planetary formation; extrasolar planets; exobiology; Earth ID LOW-MASS STARS; SOLAR NEBULA; CHEMICAL EVOLUTION; PROTOPLANETARY DISKS; GALACTIC-DISK; GIANT PLANETS; SYSTEM; JUPITER; OXYGEN; CARBON AB The discovery of giant planets around other Sun-like stars has stimulated interest in the search for planets capable of supporting life. Here, it is proposed that the abundance of water in the progenitor nebula is a fundamental determinant in the formation of planetary systems like our own, i.e., including an inner, water-rich planet (Earth) and an outer giant planet (Jupiter), The amount of water is a sensitive function of the elemental ratio of carbon to oxygen in the nebula. The Sun appears to be unusual in this respect since the ratio in most nearby stars suggests they formed from relatively water-poor nebulae. Chemical evolution models suggest that the Galactic disk is evolving from an oxidizing, water-rich state toward a carbon-rich, water-poor condition, This may have implications for the appearance and distribution of habitable worlds. (C) 2000 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gaidos, EJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 54 TC 24 Z9 24 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 JUN PY 2000 VL 145 IS 2 BP 637 EP 640 DI 10.1006/icar.2000.6407 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327KZ UT WOS:000087794200024 ER PT J AU Garvin, JB Sakimoto, SEH Frawley, JJ Schnetzler, CC Wright, HM AF Garvin, JB Sakimoto, SEH Frawley, JJ Schnetzler, CC Wright, HM TI Topographic evidence for geologically recent near-polar volcanism on Mars SO ICARUS LA English DT Article DE Mars; polar processes; volcanism ID ORBITER-LASER-ALTIMETER; ICELAND AB The Mars Orbiter Laser Altimeter (MOLA) was used to measure the topography of several putative near-polar martian volcanic craterforms. We believe they were formed by effusive lava shield building eruptions and were not hydromagmatic events, as previously suggested. Furthermore, these craterforms appear to be geologically recent, with ages between 1 and 20 million years, and may provide new evidence of localized thermal anomalies in the upper martian crustal column. (C) 2000 Academic Press. C1 NASA, Geodynam Branch, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Univ Space Res Assoc, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Raytheon STX, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Sci Syst & Applicat Inc, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Garvin, JB (reprint author), NASA, Geodynam Branch, Goddard Space Flight Ctr, Code 921, Greenbelt, MD 20771 USA. RI Wright, Heather/K-4500-2012 OI Wright, Heather/0000-0001-9013-507X NR 21 TC 32 Z9 33 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 JUN PY 2000 VL 145 IS 2 BP 648 EP 652 DI 10.1006/icar.2000.6409 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327KZ UT WOS:000087794200027 ER PT J AU Hudson, RL Moore, MH AF Hudson, RL Moore, MH TI IR spectra of irradiated cometary ice analogues containing methanol: a new assignment, a reassignment, and a nonassignment SO ICARUS LA English DT Article DE ices; comets, composition; radiation chemistry; organic chemistry; spectroscopy ID INTERSTELLAR; CHEMISTRY; SATELLITES; RELEVANT; MIXTURES AB The IR spectra and radiation chemistry of water-methanol ices near 16 K have been reinvestigated. In contrast to earlier work, no evidence is found for the formation of acetone, and a band previously attributed to ethanol is reassigned to ethylene glycol. Three new features are reported, assigned to the formate ion, and compared to the ISO spectrum of a protostellar source. (C) 2000 Academic Press. C1 Eckerd Coll, Dept Chem, St Petersburg, FL 33733 USA. NASA, Astrochem Branch, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Hudson, RL (reprint author), Eckerd Coll, Dept Chem, 4200 54th Ave S, St Petersburg, FL 33733 USA. RI Hudson, Reggie/E-2335-2012 NR 23 TC 64 Z9 64 U1 1 U2 7 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 JUN PY 2000 VL 145 IS 2 BP 661 EP 663 DI 10.1006/icar.2000.6377 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 327KZ UT WOS:000087794200030 ER PT J AU Tong, KF Luk, KM Lee, KF Lee, RQ AF Tong, KF Luk, KM Lee, KF Lee, RQ TI A broad-band U-slot rectangular patch antenna on a microwave substrate SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article DE broad-band antennas; printed antennas ID DIFFERENCE TIME-DOMAIN; FDTD; RADIATION; LAYER; WAVES AB A broad-band U-slot rectangular patch antenna printed on a microwave substrate is investigated. The dielectric constant of the substrate is 2.33, The antenna is fed by a coaxial probe, The characteristics of the U-slot patch antenna are analyzed by the finite-difference time-domain (FDTD) method. Experimental results for the input impedance and radiation patterns are obtained and compared with numerical results. The maximum impedance bandwidth achieved is 27%, centered around 3.1 GHz, with good pattern characteristics. C1 City Univ Hong Kong, Dept Elect Engn, Kowloon, Hong Kong, Peoples R China. Univ Missouri, Dept Elect Engn, Columbia, MO 65211 USA. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Tong, KF (reprint author), City Univ Hong Kong, Dept Elect Engn, Kowloon, Hong Kong, Peoples R China. NR 14 TC 119 Z9 124 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 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD JUN PY 2000 VL 48 IS 6 BP 954 EP 960 DI 10.1109/8.865229 PG 7 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 349TM UT WOS:000089061700014 ER PT J AU Shah, A Haimovich, AM Simon, MK Alouini, MS AF Shah, A Haimovich, AM Simon, MK Alouini, MS TI Exact bit-error probability for optimum combining with a Rayleigh fading Gaussian cochannel interferer SO IEEE TRANSACTIONS ON COMMUNICATIONS LA English DT Article DE cochannel interference; fading channels; optimum combining; space diversity AB We derive expressions for the exact bit-error probability (BEP) for the detection of coherent binary phase-shift keying signals of the optimum combiner employing space diversity when both the desired signal and a Gaussian cochannel interferer are subject to flat Rayleigh fading. Two different methods are employed to reach two different, but numerically identical, expressions. With the direct method, the conditional BEP is averaged over the fading of both signal and interference. With the moment generating function based method, expressions are derived from an alternative representation of the Gaussian Q-function. C1 Bell Labs Innovat, Lucent Technol, Wireless Networks Grp, Whippany, NJ 07981 USA. New Jersey Inst Technol, Dept Elect & Comp Engn, Ctr Commun & Signal Proc, Newark, NJ 07102 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Univ Minnesota, Dept Elect & Comp Engn, Minneapolis, MN 55455 USA. RP Shah, A (reprint author), Bell Labs Innovat, Lucent Technol, Wireless Networks Grp, Whippany, NJ 07981 USA. NR 10 TC 41 Z9 42 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 0090-6778 J9 IEEE T COMMUN JI IEEE Trans. Commun. PD JUN PY 2000 VL 48 IS 6 BP 908 EP 912 DI 10.1109/26.848546 PG 5 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 334WN UT WOS:000088208800003 ER PT J AU Xapsos, MA Summers, GP Barth, JL Stassinopoulos, EG Burke, EA AF Xapsos, MA Summers, GP Barth, JL Stassinopoulos, EG Burke, EA TI Probability model for cumulative solar proton event fluences SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 5th European Conference on Radiation and Its Effectson Components and Systems (RADECS '99) CY SEP 13-17, 1999 CL FONTEVRAUD, FRANCE AB A new model of cumulative solar proton event fluences is presented. It allows the expected total fluence to be calculated for a given confidence level and for time periods corresponding to space missions. The new model is in reasonable agreement with the JPL91 model over their common proton energy range of > 1 to > 60 MeV. The current model extends this energy range to > 300 MeV. It also incorporates more recent data which tends to make predicted fluences slightly higher than JPL91. For the first time, an analytic solution is obtained for this problem of accumulated fluence over a mission. Several techniques are used, including Maximum Entropy, to show the solution is well represented as a lognormal probability distribution of the total fluence. The advantages are that it is relatively easy to work with and to update as more solar proton event data become available. C1 USN, Res Lab, Washington, DC 20375 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Xapsos, MA (reprint author), USN, Res Lab, Washington, DC 20375 USA. NR 19 TC 44 Z9 44 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 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 2000 VL 47 IS 3 BP 486 EP 490 DI 10.1109/23.856469 PN 1 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 337TR UT WOS:000088378200004 ER PT J AU Barak, J AF Barak, J TI Empirical modeling of proton induced SEU rates SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 5th European Conference on Radiation and Its Effectson Components and Systems (RADECS '99) CY SEP 13-17, 1999 CL FONTEVRAUD, FRANCE ID UPSET AB A new method for calculating proton induced SEU (p-SEU) rates in orbit from heavy ion cross section data is presented. It is based on a simple expression to derive the p-SEU cross section fi-om the heavy ion results which leads to an 'effective LET flux' for the protons in the given orbit. The resulted p-SEU rates are in good agreement with those calculated from measured p-SEU cross section data. A comparison with other empirical models is given. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Soreq NRC, IL-81800 Yavne, Israel. RP Barak, J (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 13 TC 9 Z9 10 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 2000 VL 47 IS 3 BP 545 EP 550 DI 10.1109/23.856478 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 337TR UT WOS:000088378200013 ER PT J AU Johnston, AH Rax, BG AF Johnston, AH Rax, BG TI Proton damage in linear and digital optocouplers SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 5th European Conference on Radiation and Its Effectson Components and Systems (RADECS '99) CY SEP 13-17, 1999 CL FONTEVRAUD, FRANCE ID GAAS AB Fundamental differences in design influence the way that linear and digital optocouplers are degraded by radiation. Linear optocouplers are more affected by current drive conditions because the detector operates in a high-injection region when the LED produces normal light output, and do not have the extra operating margin that is inherent in digital optocouplers. Although LED degradation is often the dominant degradation mechanism in space environments, degradation of optocouplers with improved LEDs is limited by photoresponse degradation. Phototransistor gain has a relatively minor effect except at very high radiation levels. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Johnston, AH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 15 Z9 20 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 2000 VL 47 IS 3 BP 675 EP 681 DI 10.1109/23.856497 PN 1 PG 7 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 337TR UT WOS:000088378200032 ER PT J AU Barak, J Barth, JL Seidleck, CM Marshall, CJ Marshall, PW Carts, MA Reed, RA AF Barak, J Barth, JL Seidleck, CM Marshall, CJ Marshall, PW Carts, MA Reed, RA TI Single event upsets in the dual-port-board SRAMs of the MPTB experiment SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 5th European Conference on Radiation and Its Effectson Components and Systems (RADECS '99) CY SEP 13-17, 1999 CL FONTEVRAUD, FRANCE ID SEU AB The in-flight data of SEUs in the devices of panels B and C of the MPTB experiments are presented. Ground test data for M65656 are used to calculate the SEU rates in this device using the calculated flux of ions along the orbit. The models used are CREME96, simple expressions derived here, and the figure of merit model. A very good agreement is found between these calculations and the observed rates. C1 NASA, Raytheon ST Syst Corp, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. SFA Inc, NRL, Largo, MD 20785 USA. Soreq NRC, IL-81800 Yavne, Israel. RP Barak, J (reprint author), NASA, Raytheon ST Syst Corp, Goddard Space Flight Ctr, Code 562-1, Greenbelt, MD 20771 USA. NR 7 TC 5 Z9 5 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 2000 VL 47 IS 3 BP 712 EP 717 DI 10.1109/23.856503 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 337TR UT WOS:000088378200038 ER PT J AU Lu, CP Hager, GD Mjolsness, E AF Lu, CP Hager, GD Mjolsness, E TI Fast and globally convergent pose estimation from video images SO IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE LA English DT Article DE pose estimation; absolute orientation; optimization; weak-perspective camera models; numerical optimization ID CLOSED-FORM SOLUTION; QUATERNIONS; OBJECTS; MOTION AB Determining the rigid transformation relating 2D images to known 3D geometry is a classical problem in photogrammetry and computer vision. Heretofore, the best methods for solving the problem have relied on iterative optimization methods which cannot be proven to converge and/or which do not effectively account for the orthonormal structure of rotation matrices. We show that the pose estimation problem can be formulated as that of minimizing an error metric based on collinearity in object (as opposed to image) space. Using object space collinearity error, we derive an iterative algorithm which directly computes orthogonal rotation matrices and which is globally convergent. Experimentally, we show that the method is computationally efficient, that ii is no less accurate than the best currently employed optimization methods. and that it outperforms all tested methods in robustness to outliers. C1 iBEAM Broadcasting Corp, Sunnyvale, CA 94086 USA. Johns Hopkins Univ, Dept Comp Sci, Baltimore, MD 21218 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP iBEAM Broadcasting Corp, 645 Almore Ave,Suite 100, Sunnyvale, CA 94086 USA. EM cplu@ibeam.com; hager@cs.jhu.edu; eric.d.mjolsness@jpl.nasa.gov NR 46 TC 325 Z9 394 U1 1 U2 27 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 0162-8828 EI 1939-3539 J9 IEEE T PATTERN ANAL JI IEEE Trans. Pattern Anal. Mach. Intell. PD JUN PY 2000 VL 22 IS 6 BP 610 EP 622 DI 10.1109/34.862199 PG 13 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 342WE UT WOS:000088667700006 ER PT J AU Bayard, DS AF Bayard, DS TI A confluence matrix condition for exponential error convergence in overparametrized adaptive systems SO IEEE TRANSACTIONS ON SIGNAL PROCESSING LA English DT Article DE adaptive signal processing; asymptotic stability; feedforward systems; least mean square methods; persistent excitation ID FEEDFORWARD SYSTEMS; LMS ALGORITHM; INTERFERENCE; CANCELLATION; REGRESSORS; EXCITATION; STABILITY; SCHEMES; NOISE AB Many practical adaptive feedforward systems are overparametrized and, for this reason, will not satisfy persistent excitation (PE) conditions. For these systems, a weaker PE condition is proposed under which it is shown that the while parameters may not converge, the cancellation error (the error between the desired and estimated outputs) still converges exponentially. Bounds are given on the exponential rate of convergence useful for understanding the various tradeoffs and for systematic optimization and design purposes, The convergence rate is determined by properties of the confluence matrix (defined herein) that plays a role similar to that played by the autocorrelation matrix for fully PE systems. As a case study, the structure of the confluence matrix is examined in detail for adaptive systems with a tap delay line (TDL) regressor and sinusoid excitation. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bayard, DS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 23 TC 0 Z9 0 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1053-587X J9 IEEE T SIGNAL PROCES JI IEEE Trans. Signal Process. PD JUN PY 2000 VL 48 IS 6 BP 1656 EP 1666 DI 10.1109/78.845923 PG 11 WC Engineering, Electrical & Electronic SC Engineering GA 319RX UT WOS:000087356900012 ER PT J AU Jessup, JM Frantz, M Sonmez-Alpan, E Locker, J Skena, K Waller, H Battle, P Nachman, A Weber, ME Thomas, DA Curbeam, RL Baker, TL Goodwin, TJ AF Jessup, JM Frantz, M Sonmez-Alpan, E Locker, J Skena, K Waller, H Battle, P Nachman, A Weber, ME Thomas, DA Curbeam, RL Baker, TL Goodwin, TJ TI Microgravity culture reduces apoptosis and increases the differentiation of a human colorectal carcinoma cell line SO IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY-ANIMAL LA English DT Article DE microgravity; colon carcinoma; differentiation; apoptosis; CEA ID SHEAR-STRESS; GROWTH; EXPRESSION; KINASE; ALPHA; BETA AB Our hypothesis is that rotation increases apoptosis in standard tissue culture medium at shear stresses of greater than approximately 0.3 dyn/cm(2). Human MIP-101 poorly differentiated colorectal carcinoma cells were cultured for 6 d in complete medium in monolayers, on Teflon(R)-coated nonadherent surfaces (static three-dimensional [3D]) or in rotating 3D cultures either in microgravity in low-earth orbit (3D mu g) or in unit gravity on the ground (3D lg). Apoptosis (determined morphologically), proliferation (by MIB1 staining), and the expression of epidermal growth-factor receptor (EGF-R), TGF-alpha, or TGF-beta were assessed by immunohistochemistry, while the expression of the differentiation marker carcinoembryonic antigen (CEA) was assessed on Western blots. Over the course of 6 d, static 3D cultures displayed the highest rates of proliferation and lowest apoptosis. This was associated with high EGF-R, TGF-alpha, and TGF-beta expression which was greater than that of a monolayer culture. Both rotated 3D lg and 3D mu g cultures displayed lower expression of EGF-R, TGF-alpha, or TGF-beta and proliferation than that of monolayer or static 3D cultures. However, rotated 3D mu g displayed significantly less apoptosis and greater CEA expression than rotated 3D lg cultures. When rotated cultures of MIP-101 cells were grown under static conditions for another 3 d, proliferation increased and apoptosis decreased. Thus, rotation appears to increase apoptosis and decrease proliferation, whereas static 3D cultures in either unit or microgravity have less apoptosis, and reduced rotation in microgravity increases CEA expression. C1 Univ Pittsburgh, Med Ctr, Gastrointestinal Oncol Res Lab, Pittsburgh, PA 15213 USA. Univ Pittsburgh, Med Ctr, Dept Surg, Pittsburgh, PA 15213 USA. Univ Pittsburgh, Med Ctr, Inst Canc, Pittsburgh, PA 15213 USA. Univ Pittsburgh, Med Ctr, Dept Pathol, Pittsburgh, PA 15213 USA. NASA, Lyndon B Johnson Space Ctr, Biotechnol Program, Houston, TX 77058 USA. Wyle Life Sci, Biotechnol Program, Houston, TX 77058 USA. RP Jessup, JM (reprint author), Univ Pittsburgh, Med Ctr, Gastrointestinal Oncol Res Lab, Pittsburgh, PA 15213 USA. EM jessup@utscsa.edu NR 20 TC 16 Z9 19 U1 0 U2 2 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 JUN PY 2000 VL 36 IS 6 BP 367 EP 373 PG 7 WC Cell Biology; Developmental Biology SC Cell Biology; Developmental Biology GA 345KP UT WOS:000088815400007 PM 10949995 ER PT J AU Nickerson, CA Ott, CM Mister, SJ Morrow, BJ Burns-Keliher, L Pierson, DL AF Nickerson, CA Ott, CM Mister, SJ Morrow, BJ Burns-Keliher, L Pierson, DL TI Microgravity as a novel environmental signal affecting Salmonella enterica serovar Typhimurium virulence SO INFECTION AND IMMUNITY LA English DT Article ID SIMULATED MICROGRAVITY; SHEAR-STRESS; ESCHERICHIA-COLI; CELLS; PROTEINS; MUTANTS; ABILITY; TISSUES; SPACE; RPOS AB The effects of spaceflight on the infectious disease process have only been studied at the level of the host immune response and indicate a blunting of the immune mechanism in humans and animals. Accordingly, it is necessary to assess potential changes in microbial virulence associated with spaceflight which may impact the probability of in-flight infectious disease. In this study, we investigated the effect of altered gravitational vectors on Salmonella virulence in mice. Salmonella enterica serovar Typhimurium grown under modeled microgravity (MMG) were more virulent and were recovered in higher numbers from the murine spleen and liver following oral infection compared to organisms grown under normal gravity. Furthermore, MMG-grown salmonellae were more resistant to acid stress and macrophage killing and exhibited significant differences in protein synthesis than did normal-gravity-grown cells. Our results indicate that the environment created by simulated microgravity represents a novel environmental regulatory factor of Salmonella virulence. C1 Tulane Univ, Sch Med, Dept Microbiol & Immunol, New Orleans, LA 70112 USA. NASA, Lyndon B Johnson Space Ctr, EASI, Wyle Labs,Microbiol Lab, Houston, TX 77058 USA. Washington Univ, Dept Biol, St Louis, MO 63130 USA. Monsanto Co, Life Sci Informat, St Louis, MO 63167 USA. NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. RP Nickerson, CA (reprint author), Tulane Univ, Sch Med, Dept Microbiol & Immunol, 1430 Tulane Ave,SL38, New Orleans, LA 70112 USA. FU NIAID NIH HHS [AI-24533, R01 AI024533] NR 39 TC 99 Z9 107 U1 2 U2 13 PU AMER SOC MICROBIOLOGY PI WASHINGTON PA 1752 N ST NW, WASHINGTON, DC 20036-2904 USA SN 0019-9567 J9 INFECT IMMUN JI Infect. Immun. PD JUN PY 2000 VL 68 IS 6 BP 3147 EP 3152 DI 10.1128/IAI.68.6.3147-3152.2000 PG 6 WC Immunology; Infectious Diseases SC Immunology; Infectious Diseases GA 316LF UT WOS:000087167900012 PM 10816456 ER PT J AU Welch, RB AF Welch, RB TI Criteria for testing the visual-perceptual/visual-motor dissociation hypothesis SO INTERNATIONAL JOURNAL OF PSYCHOLOGY LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Ames, IA USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU PSYCHOLOGY PRESS PI HOVE PA 27 CHURCH RD, HOVE BN3 2FA, EAST SUSSEX, ENGLAND SN 0020-7594 J9 INT J PSYCHOL JI Int. J. Psychol. PD JUN-AUG PY 2000 VL 35 IS 3-4 SI SI BP 284 EP 284 PG 1 WC Psychology, Multidisciplinary SC Psychology GA 337XP UT WOS:000088388802775 ER PT J AU Sutton, MA Deng, XM Ma, FS Newman, JC James, M AF Sutton, MA Deng, XM Ma, FS Newman, JC James, M TI Development and application of a crack tip opening displacement-based mixed mode fracture criterion SO INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES LA English DT Article ID ELASTIC-PLASTIC MATERIALS; ALUMINUM-ALLOY; COMPUTER VISION; BEHAVIOR; GROWTH; DEFORMATION; TEMPERATURE; STATIONARY; SOLIDS; FIELDS AB Consistent with experimental observations, a crack tip opening displacement (CTOD)-based, mixed mode fracture criterion is developed for predicting the onset and direction of crack growth. The criterion postulates that crack growth occurs in either Mode I or Mode II direction, depending upon whether the maximum in either the opening or the shear component of CTOD, measured at a specified distance behind the crack tip, attains a critical value. The proposed CTOD-based fracture criterion is implemented in two finite element codes to predict the stable tearing behavior of (a) a modified Arcan test specimen made of AL 2024-T3 and (b) a double cantilever beam (DCB) specimen made of AL 7050. Using the measured load-crack extension data as input, results from simulations of stable crack growth along experimentally measured crack paths for the Arcan specimen demonstrate that the CTOD values obtained in the simulations are in excellent agreement with the proposed criterion. Then, using the CTOD criterion as input, simulations of the Arcan and DCB specimens demonstrate that the CTOD fracture criterion successfully predicts (a) load-crack path data for both specimens, (b) load-crack extension behavior for the Arcan specimen and (c) load-load point displacement data for the DCB specimen. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ S Carolina, Dept Mech Engn, Columbia, SC 29208 USA. NASA, Langley Res Ctr, Mat & Mech Branch, Hampton, VA USA. Kansas State Univ, Dept Mech Engn, Manhattan, KS 66506 USA. RP Deng, XM (reprint author), Univ S Carolina, Dept Mech Engn, Columbia, SC 29208 USA. EM deng@engr.sc.edu NR 49 TC 80 Z9 88 U1 2 U2 17 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 JUN PY 2000 VL 37 IS 26 BP 3591 EP 3618 DI 10.1016/S0020-7683(99)00055-4 PG 28 WC Mechanics SC Mechanics GA 299HQ UT WOS:000086193300005 ER PT J AU Gubarev, M Ciszak, E Ponomarev, I Gibson, W Joy, M AF Gubarev, M Ciszak, E Ponomarev, I Gibson, W Joy, M TI First results from a macromolecular crystallography system with a polycapillary collimating optic and a microfocus X-ray generator SO JOURNAL OF APPLIED CRYSTALLOGRAPHY LA English DT Article AB The design and performance of a high-flux X-ray crystallography system, optimized for diffraction measurements from small macromolecular crystals, is described. This system combines a microfocus X-ray generator [40 mu m full width at half-maximum (FWHM) spot size at a power level of 40 W] and a short focal length (F = 2.6 mm) polycapillary collimating optic, and produces a small-diameter quasi-parallel X-ray beam. Measurements of the X-ray flux, divergence and spectral purity of the resulting X-ray beam are presented. The X-ray flux through an aperture of 250 mu m diameter produced by the microfocus system is 16 times higher than that from a 3.15 kW rotating-anode generator equipped with a pyrolytic graphite monochromator. Diffraction data from lysozyme test crystals collected with the microfocus X-ray system are of high quality and can be reduced with standard crystallographic software, yielding an overall merging factor R-sym less than or equal to 6%. Significant additional improvements in flux are possible, and plans for achieving these goals are discussed. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Natl Res Council, Washington, DC 20418 USA. Univ Space Res Assoc, Huntsville, AL 35805 USA. Xray Opt Syst Inc, Albany, NY 12203 USA. SUNY Albany, Ctr Xray Opt, Albany, NY 12222 USA. RP Joy, M (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 5 TC 14 Z9 16 U1 0 U2 2 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0021-8898 J9 J APPL CRYSTALLOGR JI J. Appl. Crystallogr. PD JUN 1 PY 2000 VL 33 IS 2 BP 882 EP 887 DI 10.1107/S0021889800001837 PN 3 PG 6 WC Chemistry, Multidisciplinary; Crystallography SC Chemistry; Crystallography GA 317VZ UT WOS:000087248800003 ER PT J AU Hooker, SB Maritorena, S AF Hooker, SB Maritorena, S TI An evaluation of oceanographic radiometers and deployment methodologies SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID SEAWIFS QUALITY MONITOR; FIELD RADIOMETERS; LIGHT-SOURCE; SQM AB The primary objective of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project is to produce water-leaving radiances within an uncertainty of 5% in clear-water regions, and chlorophyll a concentrations within 35% over the range of 0.05-50 mg m(-3). Any global mission, like SeaWiFS, requires validation data from a wide variety of investigators. This places a significant challenge on quantifying the total uncertainty associated with the in situ measurements. because each investigator follows slightly different practices when it comes to implementing all of the steps associated with collecting field data, even those with a prescribed set of protocols. This study uses data from multiple cruises to quantify the uncertainties associated with implementing data collection procedures while using different in-water optical instruments and deployment methods. A comprehensive approach is undertaken and includes (a) the use of a portable light source and in water intercomparisons to monitor the stability of the field radiometers, (b) alternative methods for acquiring reference measurements, and (c) different techniques for making in-water profiles. Three optical systems had quadrature sum uncertainties sufficiently small to ensure a combined uncertainty for the spaceborne and in situ measurements within a total 5% vicarious calibration budget. A free-fall profiler using (relatively inexpensive) modular components performed best (2.7% quadrature sum uncertainty), although a more sophisticated (and comparatively expensive) profiler using integral components was very close and only 0.5% higher. A relatively inexpensive system deployed with a winch and crane was also close, but ship shadow contamination increased the quadrature sum uncertainty to approximately 3.4%. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, SeaWiFS Project, Greenbelt, MD 20771 USA. RP Hooker, SB (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, SeaWiFS Project, Code 970-2, Greenbelt, MD 20771 USA. RI Hooker, Stanford/E-2162-2012 NR 27 TC 43 Z9 45 U1 1 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD JUN PY 2000 VL 17 IS 6 BP 811 EP 830 DI 10.1175/1520-0426(2000)017<0811:AEOORA>2.0.CO;2 PG 20 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 326XR UT WOS:000087763000006 ER PT J AU Su, CH George, MA Palosz, W Feth, S Lehoczky, SL AF Su, CH George, MA Palosz, W Feth, S Lehoczky, SL TI Contactless growth of ZnSe single crystals by physical vapor transport SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE contactless growth; physical vapor transport; zinc selenide; atomic force microscopy ID MOLECULAR-BEAM EPITAXY; LIGHT-EMITTING-DIODES; PARTIAL PRESSURES; LASER-DIODES; MASS FLUX; BLUE; SUBLIMATION; DEGRADATION; DEFECTS; PHASE AB ZnSe crystals were grown by self-seeded physical vapor transport (PVT) technique in the horizontal configuration. The source materials were heat treated by H-2 reduction to remove the oxides followed by baking under dynamic vacuum to adjust the source composition toward that of congruent sublimation. Contactless growth of ZnSe single crystals have been performed using three different source materials. The crystals grew away from the ampoule wall with large (1 1 0) facets tending to align parallel to the gravity direction. The SEM micrographs and the AFM images showed that large (1 1 0) terraces and steps dominate the as-grown facets. The measured residual gas pressure and composition (mostly CO and H-2) in the processed ampoules were similar for all source materials used. One-dimensional diffusion model on the mass flux of a multi-species PVT system was employed to analyze the conditions for contactless growth. The calculated thermal profile for supersaturation is very close to the thermal profile measured inside the empty furnace bore in the region of contactless growth. The effects of convective flows in the vapor phase inside the ampoule on the growth processes are discussed. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, George C Marshall Space Flight Ctr, Micrograv Sci & Applicat Dept, Sci Directorate, Huntsville, AL 35812 USA. Univ Alabama, Dept Chem, Ctr Mat & Surface Sci, Huntsville, AL 35899 USA. RP Su, CH (reprint author), NASA, George C Marshall Space Flight Ctr, Micrograv Sci & Applicat Dept, Sci Directorate, SD 47, Huntsville, AL 35812 USA. RI Feth, Shari/F-6302-2013 OI Feth, Shari/0000-0003-3545-5649 NR 33 TC 10 Z9 13 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 JUN PY 2000 VL 213 IS 3-4 BP 267 EP 275 DI 10.1016/S0022-0248(00)00385-7 PG 9 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 320EX UT WOS:000087389800009 ER PT J AU Hard, JJ Connell, L Hershberger, WK Harrell, LW AF Hard, JJ Connell, L Hershberger, WK Harrell, LW TI Genetic variation in mortality of chinook salmon during a bloom of the marine alga Heterosigma akaskiwo SO JOURNAL OF FISH BIOLOGY LA English DT Article DE heritability; effective size; natural selection; HAB ID AKASHIWO RAPHIDOPHYCEAE; FAMILY-SIZE; RED TIDE; BAY; SURVIVAL; JAPAN AB Mortality in a netpen-reared population of 3-year-old chinook salmon Oncorhynchus tshawytscha during an extensive 1997 bloom of the alga Heterosigma akashiwo in Puget Sound, Washington, was low (7.2%), and corresponded to a reduction in variance effective population size of 9.4%. Under a liability threshold model, the heritability of mortality ( +/- S.E.), based on paternal half-sibs, was estimated at 0.15 +/- 0.04. No significant genetic variation was detected for date of death. Despite the low overall mortality, the consequences for variation in family size underscore the importance of maximizing genetic variation in cultured fish populations later released to the wild as a precaution against mortality and losses of genetic variation over the life cycle. The pattern of family variation in response to this algal bloom provides evidence for potentially selective mortality of anadromous salmonids in the marine environment during natural perturbations. C1 NOAA, Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Conservat Biol Div, Seattle, WA 98112 USA. NOAA, Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Environm Conservat Div, Seattle, WA 98112 USA. Univ Washington, Sch Fisheries WH10, Seattle, WA 98195 USA. Natl Marine Fisheries Serv, Manchester Marine Expt Stn, Resource Enhancement & Utilizat Technol Div, Manchester, WA 98353 USA. RP Hard, JJ (reprint author), NOAA, Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Conservat Biol Div, 2725 Montlake Blvd E, Seattle, WA 98112 USA. EM jeff.hard@noaa.gov RI Hard, Jeffrey/C-7229-2009 NR 42 TC 22 Z9 23 U1 1 U2 6 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0022-1112 J9 J FISH BIOL JI J. Fish Biol. PD JUN PY 2000 VL 56 IS 6 BP 1387 EP 1397 DI 10.1006/jfbi.2000.1258 PG 11 WC Fisheries; Marine & Freshwater Biology SC Fisheries; Marine & Freshwater Biology GA 331WG UT WOS:000088041200008 ER PT J AU Richardson, IG Dvornikov, VM Sdobnov, VE Cane, HV AF Richardson, IG Dvornikov, VM Sdobnov, VE Cane, HV TI Bidirectional particle flows at cosmic ray and lower (similar to 1 MeV) energies and their association with interplanetary coronal mass ejections/ejecta SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; MAGNETIC CLOUDS; LOOP STRUCTURE; EVENTS; EJECTA; DISCONTINUITIES; DEPENDENCE; DECREASES; TOPOLOGY; SHOCK AB We demonstrate a close relationship between bidirectional flows of galactic cosmic rays measured by the worldwide neutron monitor network and bidirectional flows of solar/shock-accelcrated particles at much lower energies (similar to 1 MeV) observed by near-Earth spacecraft, during January-September 1982. We find that similar to 80% of bidirectional cosmic ray flows are accompanied by bidirectional low energy ion flours. The observations indicate a close association between BCRFs and interplanetary coronal mass ejections/ejecta. The bidirectional flows suggest that particles of a wide range of energies are trapped on expanding, looped magnetic field lines: providing that their gyroradii are much smaller than the similar to 0.1 to few AU scale sizes of ejecta. Unidirectional now components are less well correlated at similar to 1 MeV and cosmic ray energies, presumably because they reflect gradients in different particle populations. We discuss several events in detail and illustrate how changes in particle flows may be related to substructures within these ejecta. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Inst Solar Terr Phys, Irkutsk 664033, Russia. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Univ Tasmania, Sch Math & Phys, Hobart, Tas, Australia. RP Richardson, IG (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. OI Richardson, Ian/0000-0002-3855-3634 NR 37 TC 29 Z9 32 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD JUN 1 PY 2000 VL 105 IS A6 BP 12579 EP 12591 DI 10.1029/1999JA000331 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 319QD UT WOS:000087351900003 ER PT J AU Wu, DJ Chao, JK Lepping, RP AF Wu, DJ Chao, JK Lepping, RP TI Interaction between an interplanetary magnetic cloud and the Earth's magnetosphere: Motions of the bow shock SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID OCTOBER 18-20; SOLAR-WIND; UNUSUAL LOCATIONS; FIELD; MAGNETOPAUSE; IMP-8; SHAPE; PROPAGATION; CROSSINGS; PASSAGE AB An interplanetary magnetic cloud (IMC) is an important solar-terrestrial connection event. It is an ideal object for the study of solar-terrestrial relations and space weather because the Earth's space environment can be affected considerably during an IMC passage. An IMC was observed to pass the Earth during October 18-20, 1995. Wind recorded its interplanetary characteristics at similar to 175 R-E upstream of the Earth's bow shock, and similar to 45 min later, Geotail, being near the nominal location of the dawn bow shock, detected IMC-related multiple bow shock crossing. Using simultaneous measurements from Wind and Geotail, we analyzed, with a semiempirical bow shock model with two parameters, the bow shock motion caused by the interaction of the IMC with the magnetosphere during the passage. We also compared the bow shock motion predicted by the model and hence the predicted Geotail bow shock crossings, with Geotail observations of the actual crossings. The results showed that the observed multiple bow shock crossings, which were obviously due to temporal variations of the upstream solar wind, can be well explained by the model-predicted bow shock motion. C1 Chinese Acad Sci, Purple Mt Observ, Nanjing 210008, Peoples R China. Natl Cent Univ, Inst Space Sci, Chungli 32054, Taiwan. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Chinese Acad Sci, Natl Astron Observ, Beijing, Peoples R China. RP Wu, DJ (reprint author), Chinese Acad Sci, Purple Mt Observ, 2 W Beijing Rd, Nanjing 210008, Peoples R China. NR 38 TC 13 Z9 17 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 JUN 1 PY 2000 VL 105 IS A6 BP 12627 EP 12638 DI 10.1029/1999JA000265 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 319QD UT WOS:000087351900007 ER PT J AU Woo, R Habbal, SR AF Woo, R Habbal, SR TI Connecting the Sun and the solar wired: Source regions of the fast wind observed in interplanetary space SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SCINTILLATION OBSERVATIONS; ACTIVITY MINIMUM; STREAMER BELT; CORONAL HOLE; SPEED; LATITUDE; CYCLE; DEPENDENCE; EVOLUTION; SLOW AB Highly sensitive radio occultation and white light measurements of path-integrated density have shown that the solar corona comprises three distinct morphological regions, streamer, quiet Sun, and polar coronal hole, which except for the streamer region, extend radially into interplanetary space from 1.15 R(s) to at least 30 R(s). In this paper we build on these results by comparing solar wind flow speeds observed at the same time as path-integrated density. Flow speeds are inferred from the Doppler dimming of O VI lines with the ultraviolet coronagraph spectrometer on the Solar and Heliospheric Observatory, while the simultaneous polarized brightness measurements of path-integrated density are from the High Altitude Observatory Mauna Loa Mk III K-coronamerer. The comparison of global flow speed and density observations in 1997 produces three new results. First, it shows, that the three distinct morphological regions, identified earlier in density measurements, are present in the latitudinal profile of the flow speed in the corona. In particular, the flow speed measurements provide evidence for the quiet Sun as an additional source of fast wind. Second, the comparison shows that flow spend and density are anticorrelated in the solar corona. Third, it demonstrates that the Mk III pB measurements can readily serve as a proxy for velocity distribution in the outer corona. The extensive Mk III data set that spans nearly two solar cycles therefore provides the framework of near-Sun measurements with which connections with solar wind measurements in interplanetary space can be made. Specifically, we show that fast wind regions in the heliosphere, observed directly by Ulysses and Wind plasma measurements and remotely by Nagoya interplanetary scintillation measurements, map radially back to fast wind regions at the Sun identified by the Mk III data. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Woo, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM richard.woo@jpl.nasa.gov NR 41 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-SPACE JI J. Geophys. Res-Space Phys. PD JUN 1 PY 2000 VL 105 IS A6 BP 12667 EP 12674 DI 10.1029/1999JA000255 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 319QD UT WOS:000087351900011 ER PT J AU Usmanov, AV Goldstein, ML Besser, BP Fritzer, JM AF Usmanov, AV Goldstein, ML Besser, BP Fritzer, JM TI A global MHD solar wind model with WKB Alfven waves: Comparison with Ulysses data SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Review ID INTERPLANETARY MAGNETIC-FIELD; RADIAL IMF COMPONENT; POLAR CORONAL HOLE; FAST LATITUDE SCAN; SELF-CONSISTENT; PLASMA OBSERVATIONS; HELMET-STREAMER; 2-FLUID MODEL; ACCELERATION; SPEED AB We use a steady state global axisymmetric MHD model to reproduce quantitatively the Ulysses observations during its first fast latitude traversal in 1994-1995. In particular, we are able to account for the transformation of a surface dipole magnetic field near the Sun into the configuration observed at large heliocentric distances. The MHD equations are solved by combining a time relaxation numerical technique with a marching-along-radius method. We assume that Alfven waves, propagating outward from the Sun, provide additional heating and acceleration to the flow. Only solutions with waves reproduce the plasma parameters observed in title high-latitude fast solar wind. We show that the meridional distribution of solar wind plasma and magnetic field parameters is dominated by two processes. First, inside similar to 24 R(circle dot) both the plasma velocity and magnetic field relax toward a latitude-independent profile outside the equatorial current sheet (where magnetic forces dominate over thermal and wave gradient forces). Second, outside similar to 24 R(circle dot) there is another meridional redistribution due to a poleward thermal pressure gradient that produces a slight poleward gradient in the radial velocity and an equatorward gradient in the radial component of the magnetic field. We reproduce the observed bimodal structure and morphology of both fast and slow wind and Show that computed parameters are generally in agreement with both in situ data and conditions inferred to be characteristic of the solar corona. C1 St Petersburg State Univ, Inst Phys, St Petersburg 198904, Russia. Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Usmanov, AV (reprint author), St Petersburg State Univ, Inst Phys, St Petersburg 198904, Russia. EM usmanov@snoopy.phys.spbu.ru; melvyn.goldstein@gsfc.nasa.gov; bruno.besser@oeaw.ac.at; johannes.fritzer@oeaw.ac.at RI Goldstein, Melvyn/B-1724-2008; Usmanov, Arcadi/A-9860-2013 NR 109 TC 105 Z9 112 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 JUN 1 PY 2000 VL 105 IS A6 BP 12675 EP 12695 DI 10.1029/1999JA000233 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 319QD UT WOS:000087351900012 ER PT J AU Richards, PG Buonsanto, MJ Reinisch, BW Holt, J Fennelly, JA Scali, JL Comfort, RH Germany, GA Spann, J Brittnacher, M Fok, MC AF Richards, PG Buonsanto, MJ Reinisch, BW Holt, J Fennelly, JA Scali, JL Comfort, RH Germany, GA Spann, J Brittnacher, M Fok, MC TI On the relative importance of convection and temperature to the behavior of the ionosphere in North America during January 6-12, 1997 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ELECTRON-DENSITY; THERMOSPHERIC MODEL; ULTRAVIOLET IMAGER; MILLSTONE HILL; STORM; FLUX; PLASMASPHERE; MIDLATITUDE; ALGORITHM; RADAR AB This paper is primarily concerned with the causes of the large density and temperature enhancements that are often observed during magnetically quiet periods on winter nights at midlatitudes in the North American sector. Measurements from a network of Digisondes and an incoherent scatter radar are compared with the field line interhemispheric plasma (FLIP) model for January 6-12, 1997, in order to examine the temporal evolution and geographical extent of the enhancements in eastern North Amer ica. Postsunset measurements at Millstone Hill show high electron temperatures accompanied by rapid density decay until midnight followed by a rapid temperature decay accompanied by a pronounced density enhancement in the early morning hours. The FLIP model reproduces the nighttime density enhancement well, provided the model is constrained to follow the topside electron temperature and also that the overlying plasmaspheric flux tube is full. The dramatic reduction in plasmaspheric heat flux near midnight results in a sharp decrease in ionospheric temperature, inducing a large downward flow of plasmaspheric ions which creates the nighttime enhancement in ionospheric density. We find that the nighttime plasmaspheric heat flux variation drives the nighttime ionospheric density variation, which is opposite to conclusions in previously published work. Although the plasmaspheric heat flux variation can explain the ionospheric density variation, the reasons for this heat flux variation are not understood. Convection of plasma from higher magnetic latitudes is now included in the FLIP model but is not needed to produce the observed nighttime density maximum. We have found that the fraction of light ions in the topside ionosphere at 500 km altitude in the model is very close to that obtained from chemical equilibrium and agrees well with the measured fraction. The model generally reproduces the daytime electron density very well at all stations except Bermuda, where the difference is as much as 50%. C1 Univ Alabama, Ctr Space Plasma Aeron & Astron Res, Dept Comp Sci, Huntsville, AL 35806 USA. MIT, Haystack Observ, Westford, MA 01886 USA. Univ Massachusetts, Ctr Atmospher Res, Lowell, MA 01854 USA. ITT Ind, Aerosp Commun Div, Ft Wayne, IN 46801 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Richards, PG (reprint author), Univ Alabama, Ctr Space Plasma Aeron & Astron Res, Dept Comp Sci, Huntsville, AL 35806 USA. RI Fok, Mei-Ching/D-1626-2012 NR 37 TC 36 Z9 36 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 JUN 1 PY 2000 VL 105 IS A6 BP 12763 EP 12776 DI 10.1029/1999JA000253 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 319QD UT WOS:000087351900019 ER PT J AU Sitnov, MI Sharma, AS Papadopoulos, K Vassiliadis, D Valdivia, JA Klimas, AJ Baker, DN AF Sitnov, MI Sharma, AS Papadopoulos, K Vassiliadis, D Valdivia, JA Klimas, AJ Baker, DN TI Phase transition-like behavior of the magnetosphere during substorms SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID QUASI-NEUTRAL SHEET; INTERPLANETARY MAGNETIC-FIELD; GEOMAGNETIC-ACTIVITY; THERMAL CATASTROPHE; LINEAR-STABILITY; NEURAL NETWORKS; TEARING MODE; DYNAMICS; FLUCTUATIONS; IONOSPHERE AB The behavior of substorms as sudden transitions of the magnetosphere is studied using the Bargatze et al. [1985] data set of the solar wind induced electric field vB(s) and the auroral electrojet index AL. The data set is divided into three subsets representing different levels of activity, and they are studied using the singular spectrum analysis. The points representing the evolution of the magnetosphere in the subspace of the eigenvectors corresponding to the three largest eigenvalues can be approximated by two-dimensional manifolds with a relative deviation of 10-20%. For the first two subsets corresponding to small and medium activity levels the manifolds have a pleated structure typical of the cusp catastrophe. The dynamics of the magnetosphere near these pleated structures resembles the hysteresis phenomenon typical of first-order phase transitions. The reconstructed manifold is similar to the "temperature-pressure-density" diagrams of equilibrium phase transitions, The singular spectra of vB(s), AL, and combined data have the power law dependence typical of second-order phase transitions and self-organized criticality. The magnetosphere thus exhibits the signatures of both self-organization and self-organized criticality. It is concluded that the magnetospheric substorm is neither a pure catastrophe of the low-dimensional system nor a random set of avalanches of different scales described by the simple sandpile models. The substorms behave like nonequilibrium phase transitions, with features of both first- and second-order phase transitions. C1 Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Univ Colorado, LASP, Boulder, CO 80302 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Univ Chile, Fac Ciencias, Dept Fis, Santiago, Chile. NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. RP Sitnov, MI (reprint author), Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RI Valdivia, Juan/A-3631-2008; Sitnov, Mikhail/H-2316-2016 OI Valdivia, Juan/0000-0003-3381-9904; NR 81 TC 68 Z9 68 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 JUN 1 PY 2000 VL 105 IS A6 BP 12955 EP 12974 DI 10.1029/1999JA000279 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 319QD UT WOS:000087351900035 ER PT J AU Grecu, M Anagnostou, EN Adler, RF AF Grecu, M Anagnostou, EN Adler, RF TI Assessment of the use of lightning information in satellite infrared rainfall estimation SO JOURNAL OF HYDROMETEOROLOGY LA English DT Article ID MESOSCALE CONVECTIVE SYSTEMS; UNITED-STATES; CLOUD; PRECIPITATION; STRATIFORM; RADAR AB In this paper, the combined use of cloud-to-ground lightning and satellite infrared (IR) data for rainfall estimation is investigated. Based on analysis of the correlation between satellite microwave and IR rainfall estimates and on the number of strikes in "contiguous" areas with lightning, where the contiguity is defined as a function of the distance between strikes, an empirical algorithm is developed for convective rainfall estimation. The rainfall in areas not associated with lightning is determined using a modified version of an existing IR-based rainfall estimation technique. The combined lightning and IR-based technique is evaluated based on 15 days of data in July 1997 provided by geostationary and polar-orbiting satellites and the National Lightning Detection Network. The general conclusion is that lightning data contain useful information for IR rainfall estimation. Results show a reduction of about 15% in the root-mean-square error of the estimates of rain volumes defined by convective areas associated with lightning. It is shown that the benefit of using lightning information extends to the whole rain domain, because the error caused by missing convective areas because of the absence of lightning is smaller than that caused by overestimating the convective rain areas because of cirrus that obscure underlying convective storms when only satellite IR data are used. C1 Univ Connecticut, Dept Civil & Environm Engn, Storrs, CT 06269 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Grecu, M (reprint author), Univ Connecticut, Dept Civil & Environm Engn, 261 Glenbrook Rd, Storrs, CT 06269 USA. NR 22 TC 25 Z9 27 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 1525-755X J9 J HYDROMETEOROL JI J. Hydrometeorol. PD JUN PY 2000 VL 1 IS 3 BP 211 EP 221 DI 10.1175/1525-7541(2000)001<0211:AOTUOL>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 357DM UT WOS:000089483300002 ER PT J AU Crucian, BE Cubbage, ML Sams, CF AF Crucian, BE Cubbage, ML Sams, CF TI Altered cytokine production by specific human peripheral blood cell subsets immediately following space flight SO JOURNAL OF INTERFERON AND CYTOKINE RESEARCH LA English DT Article ID PROTEIN-KINASE-C; FLOW-CYTOMETRY; SIMULATED MICROGRAVITY; DURATION MISSIONS; IMMUNE CHANGES; T-LYMPHOCYTES; EXPRESSION; SUBPOPULATION; HETEROGENEITY; INTERFERON AB In this study, flow cytometry was used to positively identify the specific lymphocyte subsets exhibiting space flight-induced alterations in cytokine production. Whole blood samples were collected from 27 astronauts at three points (one preflight, two postflight) surrounding four space shuttle missions. Assays performed included serum/urine stress hormones, white blood cell (WBC) phenotyping, and intracellular cytokine production following mitogenic stimulation. Absolute levels of peripheral granulocytes were significantly elevated following space flight, but the levels of circulating lymphocytes and monocytes were unchanged. Lymphocyte subset analysis demonstrated a decreased percentage of T cells, whereas percentages of B cells and natural killer (NK) cells remained unchanged after flight. Nearly all the astronauts exhibited an increased CD4/CD8 T cell ratio. Assessment of naive (CD45RA(+)) vs. memory (CD45RO(+)) CD4(+) T cell subsets was ambiguous, and subjects tended to group within specific missions. Although no significant trend was seen in absolute monocyte levels, a significant decrease in the percentage of the CD14(+)CD16(+) monocytes was seen following space flight in all subjects tested. T cell (CD3(+)) production of interleukin-2 (IL-2) was significantly decreased after space flight, as was IL-2 production by both CD4(+) and CD8(+) T cell subsets. Production of interferon-gamma (IFN-gamma) was not altered by space flight for the CD8(+) cell subset, but there was a significant decrease in IFN-gamma production for the CD4(+) T cell subset. Serum and urine stress hormone analysis indicated significant physiologic stresses in astronauts following space flight. Altered peripheral leukocyte subsets, altered serum and urine stress hormone levels, and altered T cell cytokine secretion profiles were all observed postflight. In addition, there appeared to be differential susceptibility to space flight regarding cytokine secretion by T cell subsets. These alterations may be the result of either microgravity exposure or the physiologic stresses of landing and readaptation to unit gravity. Future studies, including in-flight analysis or sampling, will be necessary to determine the cause of these alterations. C1 Wyle Labs, Cellular Mol Res Labs, Houston, TX 77058 USA. Baylor Coll Med, Pediat Hematol Oncol Dept, Houston, TX 77030 USA. NASA, Lyndon B Johnson Space Ctr, Cell & Mol Res Labs, Houston, TX 77058 USA. RP Sams, CF (reprint author), NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Mail Code SD3, Houston, TX 77058 USA. NR 29 TC 70 Z9 76 U1 0 U2 0 PU MARY ANN LIEBERT INC PUBL PI LARCHMONT PA 2 MADISON AVENUE, LARCHMONT, NY 10538 USA SN 1079-9907 J9 J INTERF CYTOK RES JI J. Interferon Cytokine Res. PD JUN PY 2000 VL 20 IS 6 BP 547 EP 556 DI 10.1089/10799900050044741 PG 10 WC Biochemistry & Molecular Biology; Cell Biology; Immunology SC Biochemistry & Molecular Biology; Cell Biology; Immunology GA 329CC UT WOS:000087887700003 PM 10888111 ER PT J AU Walsh, BM Barnes, NP Di Bartolo, B AF Walsh, BM Barnes, NP Di Bartolo, B TI The temperature dependence of energy transfer between the (TmF4)-F-3 and (HoI7)-I-5 manifolds of Tm-sensitized Ho luminescence in YAG and YLF SO JOURNAL OF LUMINESCENCE LA English DT Article DE energy transfer; Tm : Ho : YAG; Tm : Ho : YLF; thulium; holmium; Tm : Ho lasers ID LASER; DYNAMICS; TM,HO-YAG AB The temperature dependence of the energy transfer process between the Tm F-3(4) and Ho I-5(7) manifolds in Tm:Ho doped laser materials is investigated. Decay data of luminescence in Tm : Ho :YAG and Tm: Ho : YLF in the temperature range 243-323 K are analyzed to extract energy transfer rates and elucidate the theoretical description of the energy distribution between Tm and Ho ions in solid host materials. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Boston Coll, Dept Phys, Chestnut Hill, MA 02167 USA. NASA, LaRC, Langley Res Ctr, Hampton, VA 23681 USA. RP Walsh, BM (reprint author), NASA, LaRC, Langley Res Ctr, MS 474, Hampton, VA 23681 USA. NR 15 TC 45 Z9 52 U1 5 U2 16 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-2313 J9 J LUMIN JI J. Lumines. PD JUN PY 2000 VL 90 IS 1-2 BP 39 EP 48 DI 10.1016/S0022-2313(99)00604-3 PG 10 WC Optics SC Optics GA 318WK UT WOS:000087307500006 ER PT J AU Mehta, SK Pierson, DL Cooley, H Dubow, R Lugg, D AF Mehta, SK Pierson, DL Cooley, H Dubow, R Lugg, D TI Epstein-Barr virus reactivation associated with diminished cell-mediated immunity in antarctic expeditioners SO JOURNAL OF MEDICAL VIROLOGY LA English DT Article DE Antarctica; Epstein-Barr virus; cell-mediated immunity ID DELAYED-HYPERSENSITIVITY; DURATION MISSIONS; HERPES-SIMPLEX; HEALTHY-ADULTS; SPACE-FLIGHT; SYSTEM; SPACEFLIGHT; MULTITEST; STRESS AB Epstein-Barr virus (EBV) reactivation and cell-mediated immune (CMI) responses were followed in 16 Antarctic expeditioners during winter-over isolation at 2 Australian National Antarctic Research Expedition stations. Delayed-type hypersensitivity (DTH) skin testing was used as an indicator of the CMI response, that was evaluated 2 times before winter isolation and 3 times during isolation. At all 5 evaluation times, 8 or more of the 16 subjects had a diminished CMI response. Diminished DTH was observed on every test occasion in 4/16 subjects; only 2/16 subjects exhibited normal DTH responses for all 5 tests. A polymerase chain reaction (PCR) assay was used to detect EBV DNA in saliva specimens collected before, during, and after the winter isolation. EBV DNA was present in 17% (111/642) of the saliva specimens; all 16 subjects shed EBV in their saliva on at least 1 occasion. The probability of EBV shedding increased (P = 0.013) from 6% before or after winter isolation to 13% during the winter period. EBV appeared in saliva during the winter isolation more frequently (P < 0.0005) when DTH response was diminished than when DTH was normal. The findings indicate that the psychosocial, physical, and other stresses associated with working and living in physical isolation during the Antarctic winter result in diminished CMI and an accompanying increased reactivation and shedding of latent viruses. Published 2000 Wiley-Liss, Inc. C1 NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. Enterprise Advisory Serv Inc, Houston, TX USA. Australian Antarctic Div, Hobart, Tas, Australia. RP Pierson, DL (reprint author), NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Mail Code SD3, Houston, TX 77058 USA. NR 31 TC 54 Z9 55 U1 0 U2 5 PU WILEY-LISS PI NEW YORK PA DIV JOHN WILEY & SONS INC, 605 THIRD AVE, NEW YORK, NY 10158-0012 USA SN 0146-6615 J9 J MED VIROL JI J. Med. Virol. PD JUN PY 2000 VL 61 IS 2 BP 235 EP 240 DI 10.1002/(SICI)1096-9071(200006)61:2<235::AID-JMV10>3.0.CO;2-4 PG 6 WC Virology SC Virology GA 309JR UT WOS:000086765200010 PM 10797380 ER PT J AU Toth, RA AF Toth, RA TI Air- and N-2-Broadening parameters of water vapor: 604 to 2271 cm(-1) SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID 720-NM WAVELENGTH REGION; LINE POSITIONS; TRANSITION FREQUENCIES; LASER MEASUREMENTS; SPECTRAL REGION; HIGH-RESOLUTION; STRENGTHS; SHIFTS; SPECTROSCOPY; COEFFICIENTS AB High-resolution measurements of air- and N-2-broadened widths and pressure-induced frequency shifts of water vapor were obtained covering the spectral region between 604 and 2271 cm(-1). Over 1300 vibration-rotation transitions were measured including the (000)-(000). (010)-(010), (010)-(000), (020)-(010), and (100)-(020) vibrational bands of (H2O)-O-16. Also included were measurements of (H2O)-O-18 and (H2O)-O-17 from normal water vapor samples and (H2O)-O-18 + N-2 observations with oxygen-18-enriched gas samples. Collision-narrowing effects were observed in a few lines involving high J and low K-a transitions with the lowest measured linewidth coefficient equal to 0.0057(4) cm(-1)/atm (air-broadening) for the completely overlapping transitions, 17 0 17 <-- 18 1 18 and 17 1 17 <-- 18 0 18. at 1235.204 cm(-1). The majority of the linewidth values were derived from the measurements using a Voigt line profile. A few lines with air- or N-2-broadened half-width values of about 0.012 cm(-1) or less were found to exhibit collision-narrowing effects and were also analyzed with a profile proposed by Galatry. The results are compared to values given in previous studies. (C) 2000 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Toth, RA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 26 TC 56 Z9 59 U1 1 U2 2 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 JUN PY 2000 VL 201 IS 2 BP 218 EP 243 DI 10.1006/jmsp.2000.8098 PG 26 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 317RC UT WOS:000087239900004 ER PT J AU Naumenko, O Bertseva, E Campargue, A Schwenke, DW AF Naumenko, O Bertseva, E Campargue, A Schwenke, DW TI Experimental and ab initio studies of the HDO absorption spectrum in the 13165-13500 cm(-1) spectral region SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID OVERTONE; WATER; SPECTROSCOPY; HOD; PHOTODISSOCIATION; STRENGTHS; STATE; MODE AB The HDO absorption spectrum was recorded in the 13 165-13 500 cm(-1) spectral region by intracavity laser absorption spectroscopy. The spectrum (615 lines), dominated by the 2 nu(2) + 3 nu(3) and nu(1) + 3 nu(3) bands, was assigned and modeled leading to the derivation of 196 accurate energy levels of the (103) and (023) vibrational states. Finally, 150 of these levels were reproduced by an effective Hamiltonian involving two vibrational dark states interacting with the (023) and (103) bright states. The rms deviation achieved by variation of 28 parameters is 0.05 cm(-1), compared to an averaged experimental uncertainty of 0.007 cm(-1), indicating the limit of validity of the effective Hamiltonian approach for HDO at high-vibrational excitation. The predictions of previous ab initio calculations of the HDO spectrum (H. Partridge and D. Schwenke, J. Chern. Phys. 106, 4618-4639 (1997)) were extensively used in the assignment process. The particular spectral region under consideration was used to test and discuss the improvements of new ab initio calculations recently performed on the basis of the same potential energy surface but with an improved dipole-moment surface. The improvements concern both the energy levels and the line intensities. In particular, the strong hybrid character of the nu(1) + 3 nu(3) band is very well accounted for by the new ab initio calculations. (C) 2000 Academic Press. C1 Univ Grenoble 1, Spectrometrie Phys Lab, CNRS, UMR C5588, F-38402 St Martin Dheres, France. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Naumenko, O (reprint author), Univ Grenoble 1, Spectrometrie Phys Lab, CNRS, UMR C5588, BP 87, F-38402 St Martin Dheres, France. RI schwenke, david/I-3564-2013 NR 25 TC 28 Z9 30 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 JUN PY 2000 VL 201 IS 2 BP 297 EP 309 DI 10.1006/jmsp.2000.8087 PG 13 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 317RC UT WOS:000087239900012 ER PT J AU Andreev, AA Klimanov, VA AF Andreev, AA Klimanov, VA TI Quantitative Holocene climatic reconstruction from Arctic Russia SO JOURNAL OF PALEOLIMNOLOGY LA English DT Article DE fossil pollen; climate reconstruction; Holocene; Arctic Russia ID ICE CAP; POLLEN; ZEMLYA; REGION AB Vegetation changes reflected in fossil pollen spectra are a primary source of information about climate fluctuations in the past. A statistical-information (transfer function) method based on the correlation of recent pollen spectra with modern climate conditions has been used to reconstruct Holocene climatic changes from fossil pollen. Climatic variables used for the reconstructions are the mean annual, January, July temperatures and annual precipitation. Peat sections with pollen and C-14 data from the Arctic Russia were used for the reconstructions. The reconstructed climate fluctuations are similar to the climate changes obtained from many sites in the former USSR. A clear signal for Younger Dryas cooling, 11,000-10,000 yr BP and early Preboreal warming is apparent. The early Preboreal (10,000-9000 yr BP) was the warmest time for sites from modern coastal and island areas. The warm interval occurred in the Boreal period, about 8500 yr BP. According to the reconstructions the warmest time for non-coastal areas was the last half of Atlantic period, 6000-4500 yr BP. Other warm intervals were reconstructed about 3500 and 1000 yr BP. Reconstructions show that warming periods are primarily defined as times of increased summer temperatures, and cooling periods as time of decreased winter temperatures. The precipitation followed the temperatures: during the warming periods precipitation increased and during the cooling periods it decreased. Precipitation maximum, about 100 mm higher than present, are reconstructed for the warmest interval, 6000-4500 yr BP at all sites. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Russian Acad Sci, Inst Geog, Moscow 109017, Russia. RP Andreev, AA (reprint author), Alfred Wegener Inst Polar & Meerforsch, Telegrafenberg A43, D-14478 Potsdam, Germany. RI Andreev, Andrei/J-2701-2015 NR 39 TC 57 Z9 58 U1 0 U2 11 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0921-2728 J9 J PALEOLIMNOL JI J. Paleolimn. PD JUN PY 2000 VL 24 IS 1 BP 81 EP 91 DI 10.1023/A:1008121917521 PG 11 WC Environmental Sciences; Geosciences, Multidisciplinary; Limnology SC Environmental Sciences & Ecology; Geology; Marine & Freshwater Biology GA 316NZ UT WOS:000087175000007 ER PT J AU Smorawinski, J Kaciuba-Uscilko, H Nazar, K Kubala, P Kaminska, E Ziemba, AW Adrian, J Greenleaf, JE AF Smorawinski, J Kaciuba-Uscilko, H Nazar, K Kubala, P Kaminska, E Ziemba, AW Adrian, J Greenleaf, JE TI Effects of three-day bed rest on metabolic, hormonal and circulatory responses to an oral glucose load in endurance or strength trained athletes and untrained subjects SO JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY LA English DT Article DE oral glucose tolerance test; bed rest; insulin catecholamines; physical training ID HEAD-DOWN TILT; INSULIN-RESISTANCE; CARDIOVASCULAR-RESPONSES; SKELETAL-MUSCLE; HUMANS; INTOLERANCE; EXERCISE; FAT AB The study was designed to find out (1) whether the effect of 3-day bed rest on blood glucose (BG) acid plasma insulin (IRI) responses to glucose ingestion depends on preceding physical activity and (2) whether plasma adrenaline (A), noradrenaline (NA) and cardiovascular changes following a glucose load are modified by bed rest. Eleven sedentary students (22.5+/-0.3 yrs), 8 long distance runners (18.6+/-0.3 yrs) and 10 strength trained athletes (21.2+/-2.1 yrs) were examined before and after bed rest. Plasma IRI, BG, NA, A, heart rate (HR), and blood pressure (BP) were measured during 2 hrs following glucose (75 g) ingestion. The responses of BG and IRI to glucose load were calculated as incremental areas under the curves (auc). Both in athletes and untrained subjects bed rest markedly increased IRIauc, while BGauc was elevated only in sedentary subjects (p < 0.05). The greatest increases in IRIauc and IRI/BG ratios were found in the endurance athletes. The data from all subjects (n = 29) revealed that the initial plasma NA and glucose-induced increases in NA and A were lowered after bed rest (p < 0.01). These effects were most pronounced in the endurance athletes. Bed rest did not influence HR or BP in any group. It is concluded that (1) the athletes have more adequate compensation for the bed-rest-induced decrement in insulin sensitivity than sedentary men; (2) three-day bed rest diminishes basal sympathetic activity and attenuates sympathoadrenal response to oral glucose; (3) endurance athletes have greater sympathetic inhibition than strength athletes or sedentary men. C1 Polish Acad Sci, Med Res Ctr, Dept Appl Physiol, PL-02106 Warsaw, Poland. Acad Phys Educ, Dept Sports Med, Poznan, Poland. NASA, Ames Res Ctr, Gravitat Res Branch, Moffett Field, CA 94035 USA. RP Nazar, K (reprint author), Polish Acad Sci, Med Res Ctr, Dept Appl Physiol, 5 Pawinskiego Str, PL-02106 Warsaw, Poland. NR 29 TC 25 Z9 25 U1 1 U2 3 PU POLISH PHYSIOLOGICAL SOC PI GRZEGORZECKA PA JAGIELLONIAN UNIV SCHOOL MED, INST PHYSIOLOGY, 31-531 KRAKOW, 16 GRZEGORZECKA, POLAND SN 0867-5910 J9 J PHYSIOL PHARMACOL JI J. Physiol. Pharmacol. PD JUN PY 2000 VL 51 IS 2 BP 279 EP 289 PG 11 WC Physiology SC Physiology GA 330XQ UT WOS:000087987100009 PM 10898100 ER PT J AU Smith, DD Sibille, L Ignont, E Cronise, RJ Noever, DA AF Smith, DD Sibille, L Ignont, E Cronise, RJ Noever, DA TI Noble metal immersion spectroscopy of silica alcogels and aerogels SO JOURNAL OF POROUS MATERIALS LA English DT Article DE effective medium theory; surface plasmon resonance; aerogels; metal nanoparticles; silica ID CRYSTALLITE SIZE; ETHYLENE; CATALYSTS; OXIDATION; PARTICLES; SILVER; SELECTIVITY; MECHANISM; OXIDE AB We have fabricated aerogels containing gold and silver nanoparticles for gas catalysis applications. The technique of immersion spectroscopy is extended to porous or heterogeneous media allowing the surface area of metal available for catalytic gas reaction to be determined. Specifically, we apply the predominant effective medium theories to the heterogeneous interlayer surrounding each particle to determine the average fractional composition of each component in this inhomogeneous layer. The technique is satisfactory for statistically random metal particle distributions but needs further modification for aggregated or surfactant modified systems. Additionally, the kinetics suggest that collective particle interactions in coagulated clusters are perturbed during silica gelation resulting in a change in the aggregate geometry. C1 NASA, George C Marshall Space Flight Ctr, Sci Directorate, Huntsville, AL 35812 USA. NASA, Univ Space Res Assoc, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Alabama, Dept Chem, Huntsville, AL 35899 USA. RP Smith, DD (reprint author), NASA, George C Marshall Space Flight Ctr, Sci Directorate, SD-48, Huntsville, AL 35812 USA. NR 34 TC 5 Z9 5 U1 0 U2 3 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 1380-2224 J9 J POROUS MAT JI J. Porous Mat. PD JUN PY 2000 VL 7 IS 4 BP 499 EP 508 DI 10.1023/A:1009678811808 PG 10 WC Chemistry, Applied; Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 280DX UT WOS:000085087900010 ER PT J AU Lindstrom, DJ AF Lindstrom, DJ TI Analysis of clasts in thin sections of rocks by micro-coring INAA SO JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY LA English DT Article; Proceedings Paper CT 10th International Conference on Modern Trends in Activation Analysis (MTAA-10) CY APR 19-23, 1999 CL NIH, BETHESDA, MARYLAND SP Natl Inst Stand & Technol HO NIH ID LUNAR AB High-sensitivity micro-INAA (Instrumental Neutron Activation Analysis) techniques are used to obtain high quality analyses for a variety of geochemically interesting elements on samples weighing only a few tens of micrograms. In particular, small (similar to 100-500 mu m) core samples from specially selected regions of petrographic thin sections can be obtained using a micro-coring device and analyzed by micro-INAA. Uncertainties in weighing (or in normalizing the INAA data to results from other techniques in order to obtain weights) limit the accuracy of elemental concentrations to perhaps +/-5% relative for medium-grained samples. C1 NASA, Lyndon B Johnson Space Ctr, Planetary Sci Branch SN2, Houston, TX 77058 USA. RP Lindstrom, DJ (reprint author), NASA, Lyndon B Johnson Space Ctr, Planetary Sci Branch SN2, Houston, TX 77058 USA. NR 11 TC 1 Z9 1 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0236-5731 J9 J RADIOANAL NUCL CH JI J. Radioanal. Nucl. Chem. PD JUN PY 2000 VL 244 IS 3 BP 511 EP 515 DI 10.1023/A:1006774713121 PG 5 WC Chemistry, Analytical; Chemistry, Inorganic & Nuclear; Nuclear Science & Technology SC Chemistry; Nuclear Science & Technology GA 338GM UT WOS:000088410800008 ER PT J AU MacKenzie, CL McLaughlin, SM AF MacKenzie, CL McLaughlin, SM TI Life history and habitat observations of softshell clams Mya arenaria in northeastern New Jersey SO JOURNAL OF SHELLFISH RESEARCH LA English DT Article DE Mya arenaria; settlement densities; survival; mortality factors; growth ID SOFT-SHELL CLAM; CHESAPEAKE BAY; WADDEN SEA; POPULATION-DYNAMICS; BENTHIC MACROFAUNA; RARITAN ESTUARY; FOOD-INTAKE; BLUE CRABS; PREDATION; ABUNDANCE AB Population densities, survival, factors associated with mortalities, and growth of softshell clams, Mya arenaria, in two northeastern New Jersey estuaries were studied from 1993 through 1997. The study areas were near shore where low-tide water depths ranged from 15 to 90 cm. Juvenile densities were high only in 1993. Light sets of juveniles from 1994 to 1997 disappeared by the end of their first summer. The longest living softshells were the abundant 1993 year class, which survived for 26 mo in the Shrewsbury River. This contrasts with life spans of 7-12 years for softshells in New England. Mortalities of softshells were correlated with: (1) predation by the striped killifish, Fundulus majalis, and mummichog, F. heteroclitus; (2) mars of sea lettuce, Ulva lactusa; and (3) high temperatures (30-32 degrees C). Softshell sarcoma was also present and may have contributed to mortalities. The effects of the mortality agents varied among locations and years. The softshells of the Shrewsbury River averaged about 23 mm and 40 mm long at the end of their first and second growing seasons, respectively. C1 NOAA, Natl Marine Fisheries Serv, James J Howard Marine Sci Lab, Highlands, NJ 07732 USA. NOAA, Natl Marine Fisheries Serv, Cooperat Oxford Lab, Oxford, MD 21654 USA. RP MacKenzie, CL (reprint author), NOAA, Natl Marine Fisheries Serv, James J Howard Marine Sci Lab, Highlands, NJ 07732 USA. NR 65 TC 5 Z9 6 U1 1 U2 5 PU NATL SHELLFISHERIES ASSOC PI SOUTHAMPTON PA C/O DR. SANDRA E. SHUMWAY, NATURAL SCIENCE DIVISION, SOUTHAMPTON COLLEGE, SOUTHAMPTON, NY 11968 USA SN 0730-8000 J9 J SHELLFISH RES JI J. Shellfish Res. PD JUN PY 2000 VL 19 IS 1 BP 35 EP 41 PG 7 WC Fisheries; Marine & Freshwater Biology SC Fisheries; Marine & Freshwater Biology GA 342GC UT WOS:000088636000009 ER PT J AU Morscher, GN Hurst, J Brewer, D AF Morscher, GN Hurst, J Brewer, D TI Intermediate-temperature stress rupture of a woven Hi-Nicalon, BN-interphase, SiC-matrix composite in air SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID DAMAGE ACCUMULATION; SIC/SIC COMPOSITE; BORON-NITRIDE; OXIDATION; FIBERS; EMBRITTLEMENT; MECHANISMS; KINETICS; BEHAVIOR; LIFETIME AB Woven Hi-Nicalon(TM)-reinforced melt-infiltrated SiC-matrix composites were tested under tensile stress-rupture conditions in air at intermediate temperatures. A comprehensive examination of the damage state and the fiber properties at failure was performed. Modal acoustic emission analysis was used to monitor damage during the experiment. Extensive microscopy of the composite fracture surfaces and the individual fiber fracture surfaces was used to determine the mechanisms leading to ultimate failure. The rupture properties of these composites were significantly worse than expected compared with the fiber properties under similar conditions. This was due to the oxidation of the BN interphase, Oxidation occurred through the matrix cracks that intersected the surface or edge of a tensile bar. These oxidation reactions resulted in strong bonding of the fibers to one another at regions of near fiber-to-fiber contact. It was found that two regimes for rupture exist for this material: a high-stress regime where rupture occurs at a fast rate and a low-stress regime where rupture occurs at a slower rate. For the high-stress regime, the matrix damage state consisted of through-thickness cracks. The average fracture strength of fibers that were pulled out (the final fibers to break before ultimate failure) was controlled by the slow-crack-growth rupture criterion in the literature for individual Hi-Nicalon fibers. For the low-stress regime, the matrix damage state consisted of microcracks which grew during the rupture test. The average fracture strength of fibers that were pulled out in this regime was the same as the average fracture strength of individual fibers pulled out in as-produced composites tested at room temperature. C1 Ohio Aerosp Inst, Cleveland, OH 44142 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Morscher, GN (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 35 TC 45 Z9 45 U1 0 U2 16 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 JUN PY 2000 VL 83 IS 6 BP 1441 EP 1449 PG 9 WC Materials Science, Ceramics SC Materials Science GA 325AW UT WOS:000087655000021 ER PT J AU Prabhakara, C Iacovazzi, R Weinman, JA Dalu, G AF Prabhakara, C Iacovazzi, R Weinman, JA Dalu, G TI A TRMM microwave radiometer rain rate estimation method with convective and stratiform discrimination SO JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN LA English DT Article ID RADAR; PRECIPITATION; AREA; RETRIEVALS; CLOUDS AB Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) radiometer brightness temperature data, in the 85 GHz channel (T85) reveal distinct local minima (T85(min)) in a regional map containing a Mesoscale Convective System (MCS). This is because of relatively small footprint size (similar to 5.5 km) and strong extinction properties in this channel of the TMI. A map of surface rain rate for that region, deduced from simultaneous measurements made by the Precipitation Radar (PR) on board the TRMM satellite, reveals that these T85(min), produced by scattering, correspond to local PR rain maxima. Utilizing the PR rain rate map as a guide, we infer empirically from TMI data the presence of three different kinds of thunderstorms or Cbs. These Cbs are classified as young, mature, and decaying types, and are assumed to have a scale of about 20 km on the average. Two parameters are used to classify these three kinds of Cbs based on the T85 data: a) the magnitude of the scattering depression deduced from local T85(min), and b) the mean horizontal gradient of T85 around such minima. Knowing the category of a given Cb, we can estimate the rain rate associated with it. Such estimation is done with the help of relationships linking T85(min) to rain rate in each Cb type. Similarly, a weak background rain rate in all the areas where T85 is less than 260 K is deduced with another relationship linking T85 to rain rate. In our rain retrieval model, this background rain constitutes stratiform rain where the Cbs are absent. Initially, these relationships are optimized or tuned utilizing the PR and TMI data of a few MCS events. After such tuning, the model is applied to independent MCS cases. The areal distribution of light (1-10 mmhr(-1)), moderate (10-20 mmhr(-1)), and intense (greater than or equal to 20 mmhr(-1)) rain rates are retrieved satisfactorily. Accuracy in the estimates of the light, moderate, and intense rain areas and the mean rain rates associated with such areas in these independent MCS cases is on the average about 15 %. Taking advantage of this ability of our retrieval method, one could derive the latent heat input into the atmosphere over the 760 km wide swath of the TMI radiometer in the tropics. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. CNR, I-00185 Rome, Italy. 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 30 TC 24 Z9 26 U1 1 U2 2 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 JUN PY 2000 VL 78 IS 3 BP 241 EP 258 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 342UG UT WOS:000088663100004 ER PT J AU Gorodetsky, ML Pryamikov, AD Ilchenko, VS AF Gorodetsky, ML Pryamikov, AD Ilchenko, VS TI Rayleigh scattering in high-Q microspheres SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS LA English DT Article ID FUSED-SILICA MICROSPHERES; WHISPERING-GALLERY MODES; RESONATORS; FIBER AB The Rayleigh scattering has to be largely suppressed in high-Q whispering-gallery modes in microspheres because of restrictions imposed on scattering angles by cavity confinement. Earlier estimates of the fundamental limit for the quality factor in fused-silica microspheres are revisited, and Q similar or equal to 10(12) is predicted in few-millimeter-size fused-silica spheres, if the surface hydration problem is ovecome. Particular effects of surface scattering losses are analyzed, and the manifestation of scattering in the form of intermode coupling is calculated. The predominant effect of counterpropagating mode coupling (intracavity backscattering) is analyzed in the presence of a mode-matched traveling-wave coupler. As much as 100% resonance reflection regime is shown to be feasible. (C) 2000 Optical Society of America. C1 Moscow MV Lomonosov State Univ, Fac Phys, Moscow 119899, Russia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gorodetsky, ML (reprint author), Moscow MV Lomonosov State Univ, Fac Phys, Moscow 119899, Russia. RI Gorodetsky, Michael/C-5938-2008 OI Gorodetsky, Michael/0000-0002-5159-2742 NR 16 TC 210 Z9 211 U1 4 U2 39 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0740-3224 J9 J OPT SOC AM B JI J. Opt. Soc. Am. B-Opt. Phys. PD JUN PY 2000 VL 17 IS 6 BP 1051 EP 1057 DI 10.1364/JOSAB.17.001051 PG 7 WC Optics SC Optics GA 322XQ UT WOS:000087534900023 ER PT J AU Zhu, DM Miller, RA AF Zhu, DM Miller, RA TI Thermal conductivity and elastic modulus evolution of thermal barrier coatings under high heat flux conditions SO JOURNAL OF THERMAL SPRAY TECHNOLOGY LA English DT Article DE thermal barrier coating; laser sintering and creep; thermal conductivity change kinetics; elastic modulus AB Laser high heat flux test approaches have been established to obtain critical properties of ceramic thermal barrier coatings (TBCs) under near-realistic temperature and thermal gradients that mag be encountered in advanced engine systems. Thermal conductivity change kinetics of a thin ceramic coating mere continuously monitored in real time at various test temperatures. A significant thermal conductivity increase was observed during the laser-simulated engine heat flux tests. For a 0.25 mm thick ZrO2-8% Y2O3 coating system, the overall thermal conductivity increased from the initial value of 1.0 W/m K to 1.15, 1.19, and 1.5 W/m K after 30 h of testing at surface temperatures of 990, 1100, and 1320 degrees C, respectively. Hardness and elastic modulus gradients across a 1.5 mm thick TBC system were also determined as a function of laser testing time using the laser sintering/creep and microindentation techniques. The coating Knoop hardness values increased from the initial hardness value of 4 GPa to 5 GPa near the ceramic/bond coat interface and to 7.5 GPa at the ceramic coating surface after 120 h of testing. The ceramic surface modulus increased from an initial value of about 70 GPa to a final value of 125 GPa, The increase in thermal conductivity and the evolution of significant hardness and modulus gradients in the TBC systems are attributed to sintering-induced microporosity gradients under the laser-imposed high thermal gradient conditions. The test techniques provide a viable means for obtaining coating data for use in design, development, stress modeling, and life prediction for various TBC applications. C1 NASA, Ohio Aerosp Inst, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Zhu, DM (reprint author), NASA, Ohio Aerosp Inst, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 13 TC 115 Z9 117 U1 3 U2 35 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 USA SN 1059-9630 J9 J THERM SPRAY TECHN JI J. Therm. Spray Technol. PD JUN PY 2000 VL 9 IS 2 BP 175 EP 180 DI 10.1361/105996300770349890 PG 6 WC Materials Science, Coatings & Films SC Materials Science GA 336RM UT WOS:000088316800004 ER PT J AU Pint, BA Wright, IG Brindley, WJ AF Pint, BA Wright, IG Brindley, WJ TI Evaluation of thermal barrier coating systems on novel substrates SO JOURNAL OF THERMAL SPRAY TECHNOLOGY LA English DT Article DE thermal barrier coatings; NiAl; FeCrAl; NiCr; chromia; alumina; X-33 reusable launch vehicle ID PREDICTION MODEL DEVELOPMENT; HIGH-TEMPERATURE OXIDATION; REACTIVE ELEMENTS; SCALE ADHESION; ALLOYS; LIFE; PERFORMANCE; PROTECTION AB Testing was conducted on both plasma-sprayed (PS) and electron beam-physical vapor deposited (EB-PVD) Y2O3-stabilized ZrO2 (YSZ) thermal barrier coatings (TBCs) applied directly to oxidation-resistant substrates such as beta-NiAl, oxide-dispersed FeCrAl, and NiCr. On an alloy that forms a very adherent alumina scale, beta-NiAl + Zr, the coating Lifetime of YSZ in furnace cyclic tests was 6 or more times longer than on state-of-the-art, YSZ coatings on single crystal Ni-base superalloys with MCrAlY or Pt aluminide bond coats. Coatings on FeCrAl. alloys appear to be a viable option for applications such as the external skin of the X-33, single stage to orbit, reusable launch vehicle. Model chromia-forming bond coat compositions also show promise for power generation applications at temperatures where hot corrosion may be a major problem. In general, while this work examined unique materials systems, many of the same fundamental failure mechanisms observed in conventional TBCs were observed. C1 Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Pint, BA (reprint author), Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA. RI Pint, Bruce/A-8435-2008 OI Pint, Bruce/0000-0002-9165-3335 NR 23 TC 18 Z9 18 U1 2 U2 13 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 USA SN 1059-9630 J9 J THERM SPRAY TECHN JI J. Therm. Spray Technol. PD JUN PY 2000 VL 9 IS 2 BP 198 EP 203 DI 10.1361/105996300770349926 PG 6 WC Materials Science, Coatings & Films SC Materials Science GA 336RM UT WOS:000088316800007 ER PT J AU Clark, K Bielitzki, JT Wagner, EG AF Clark, K Bielitzki, JT Wagner, EG TI The International Space Station: Globalizing life sciences SO LAB ANIMAL LA English DT Article C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Int Space Stn, Headquarters, Washington, DC USA. NASA, Ames Res Ctr, Lockheed Martin, Anim Welf Program, Moffett Field, CA 94035 USA. RP Bielitzki, JT (reprint author), NASA, Ames Res Ctr, MS 261-1, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU NATURE AMERICA INC PI NEW YORK PA 345 PARK AVE SOUTH, NEW YORK, NY 10010-1707 USA SN 0093-7355 J9 LAB ANIMAL JI Lab Anim. PD JUN PY 2000 VL 29 IS 6 BP 38 EP 41 PG 4 WC Veterinary Sciences SC Veterinary Sciences GA 321MC UT WOS:000087458400009 ER PT J AU Bar-Cohen, Y Lih, SS AF Bar-Cohen, Y Lih, SS TI Experimental enhancements of leaky lamb wave dispersion data acquisition and implementation challenges to NDT of composites SO MATERIALS EVALUATION LA English DT Article DE leaky lamb waves; NDT; composites; stiffness constants; dispersion curves ID PROPAGATION AB The leaky lamb wave (LLW) technique is approaching a maturity level that is making it an attractive quantitative NDT tool for composites and bonded joints. Since it was first observed in 1982, the phenomenon has been studied extensively, particularly in composite materials. The leaky wave is induced by oblique insonification using a pitch-catch arrangement, and the resulting modes are acquired by identifying minima in the reflected spectra. These modes are recorded in the form of dispersion curves, which are evaluated in relation to analytical data. The wave behavior in multiorientation laminates has been well documented and corroborated experimentally with high accuracy. The sensitivity of the wave to the elastic constants of layered materials and to boundary conditions enables the measurement of the elastic properties of bonded joints. Recently, the authors significantly enhanced the LLW data acquisition experimental capability, significantly increasing the acquisition speed as well as the number of Discontinuity modes that can be identified. This capability greatly increased the accuracy of the data inversion and improved the characterization of anomalies and Delamination the practicality of the technique. Despite progress in the theoretical and experimental aspects, methods based on the oblique insonification of composites are still not used routinely in industrial applications. The authors investigated the possible causes that are hampering the transition of the LLW to industrial applications and identified four key issues. The recent experimental development and the issues affecting the transition of the technique to practical use are described in this paper. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bar-Cohen, Y (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 82-105, Pasadena, CA 91109 USA. NR 11 TC 2 Z9 4 U1 0 U2 0 PU AMER SOC NON-DESTRUCTIVE TEST PI COLUMBUS PA 1711 ARLINGATE LANE PO BOX 28518, COLUMBUS, OH 43228-0518 USA SN 0025-5327 J9 MATER EVAL JI Mater. Eval. PD JUN PY 2000 VL 58 IS 6 BP 801 EP 806 PG 6 WC Materials Science, Characterization & Testing SC Materials Science GA 320ZK UT WOS:000087430300007 ER PT J AU Padmakar Singh, KP Drake, SA Pandey, SK AF Padmakar Singh, KP Drake, SA Pandey, SK TI Optical, X-ray and radio observations of HD 61396: a probable new RS CVn-type binary SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE binaries : close; stars : coronae; stars : individual : HD 61396; stars : late-type; X-rays : stars ID EINSTEIN-SLEW SURVEY; CANUM-VENATICORUM; STARS; CONTINUUM; SYSTEMS; CATALOG AB We have carried out BVR photometric and H alpha spectroscopic observations of the star HD 61396 during 1998 March 20 to 1999 April 3. We have discovered regular optical photometric variability from this star, with an inferred period of 31.95 +/- 0.10 d: and an amplitude of similar to 0.18 mag. A possible period of 35.34 +/- 0.12 d, as determined with Hipparcos, cannot be completely ruled out, however. Modelling of its photometric light curve with two circular spots indicates that 5-21 per cent of the stellar surface is covered by dark starspots which are similar to 830 K cooler than the surrounding photosphere, and produce the observed rotational modulation of the optical flux. Optical spectroscopy reveals a variable H alpha emission feature, indicating that it is an unusually active star. In addition, we have analysed archival X-ray data of HD 61396, obtained from serendipitous observations with the ROSAT X-ray observatory, and we also discuss the radio properties of this star, based on both published Green Bank and unpublished VLA observations. The strong photometric variability and H alpha emission, the relatively hard X-ray spectrum, and the high X-ray and radio luminosities imply that HD 61396 is most likely to be a member of the RS CVn class of evolved active binary stars. Its X-ray and radio luminosities place it among the five most luminous active binaries detected so far. C1 Ravishankar Univ, Sch Studies Phys, Raipur 492010, Madhya Pradesh, India. Tata Inst Fundamental Res, Dept Astron & Astrophys, Mumbai 400005, India. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Univ Space Res Assoc, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Padmakar (reprint author), Ravishankar Univ, Sch Studies Phys, Raipur 492010, Madhya Pradesh, India. NR 31 TC 0 Z9 0 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 JUN 1 PY 2000 VL 314 IS 4 BP 733 EP 742 DI 10.1046/j.1365-8711.2000.03298.x PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 321XJ UT WOS:000087480300010 ER PT J AU Stathakis, RA Boyle, BJ Jones, DH Bessell, MS Galama, TJ Germany, LM Hartley, M James, DM Kouveliotou, C Lewis, IJ Parker, QA Russell, KS Sadler, EM Tinney, CG van Paradijs, J Vreeswijk, PM AF Stathakis, RA Boyle, BJ Jones, DH Bessell, MS Galama, TJ Germany, LM Hartley, M James, DM Kouveliotou, C Lewis, IJ Parker, QA Russell, KS Sadler, EM Tinney, CG van Paradijs, J Vreeswijk, PM TI Spectral evolution of the peculiar Ic Supernova 1998bw SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE stars : evolution; supernovae : general; supernovae : individual : SN 1998bw; gamma-rays : bursts ID GAMMA-RAY BURST; 25 APRIL 1998; SN 1998BW; MASS-LOSS; HELIUM; EXPLOSION; STARS; GRB-980425; PHASE AB Supernova 1998bw holds the record for the most energetic Type Ic explosion, one of the brightest radio supernovae and probably the first supernova associated with a gamma-ray burst. In this paper we present spectral observations of SN 1998bw observed in a cooperative monitoring campaign using the Anglo-Australian Telescope, the UK Schmidt Telescope and the Siding Springs Observatories 2.3-m telescope. We investigate the evolution of the spectrum between 7 and 94 d after V-band maximum in comparison with well-studied examples of Type Ic SNe in order to quantify the unusual properties of this supernova event. Though the early spectra differ greatly from observations of classical Ic supernovae (SNe), we find that the evolution from the photospheric to nebular phases is slow but otherwise typical. The spectra differ predominantly in the extensive line blending and blanketing which has been attributed to the high velocity of the ejecta, We find that by day 19, the absorption line minima blueshifts are 10-50 per cent higher than other SNe and on day 94 emission lines are 45 per cent broader, as expected if the progenitor had a massive envelope. However, it is difficult to explain the extent of line blanketing entirely by line broadening, and we argue that an additional contribution from other species is present, Indicating unusual relative abundances or physical conditions in the envelope. C1 Anglo Australian Observ, Epping, NSW 1710, Australia. Australian Natl Univ, Res Sch Astron & Astrophys, Weston Creek, ACT 2611, Australia. CALTECH, Robinson Lab, Pasadena, CA 91125 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Royal Observ, Edinburgh EH9 3HJ, Midlothian, Scotland. Univ Sydney, Sch Phys A29, Sydney, NSW 2006, Australia. Univ Amsterdam, Astron Inst Anton Pannekoek, Ctr High Energy Astrophys, NL-1098 SJ Amsterdam, Netherlands. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. RP Stathakis, RA (reprint author), Anglo Australian Observ, POB 296, Epping, NSW 1710, Australia. RI Galama, Titus/D-1429-2014; OI Galama, Titus/0000-0002-1036-396X; Sadler, Elaine/0000-0002-1136-2555; Tinney, Christopher/0000-0002-7595-0970 NR 30 TC 13 Z9 13 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 JUN 1 PY 2000 VL 314 IS 4 BP 807 EP 814 DI 10.1046/j.1365-8711.2000.03373.x PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 321XJ UT WOS:000087480300019 ER PT J AU Fox-Rabinovitz, MS Stenchikov, GL Suarez, MJ Takacs, LL Govindaraju, RC AF Fox-Rabinovitz, MS Stenchikov, GL Suarez, MJ Takacs, LL Govindaraju, RC TI A uniform- and variable-resolution stretched-grid GCM dynamical core with realistic orography SO MONTHLY WEATHER REVIEW LA English DT Article ID SHALLOW-WATER EQUATIONS; PRIMITIVE EQUATIONS; WEATHER PREDICTION; GLOBAL-MODEL; SIMULATION; SYSTEM; PART AB The impact of introducing a realistic orographic forcing into a uniform- and variable-resolution stretched-grid GCM dynamical core is investigated by performing long-term and medium-range integrations. Comparisons are made between various stretched-grid simulations and a control that consists of a uniform grid integration at high resolution. These comparisons include those where the orography has and has not been filtered to eliminate small-scale noise. Results from the region of interest with highest resolution show that 1) the stretched-grid GCM provides an efficient downscaling over the area of interest, that is, it properly simulates nor only large-scale but also mesoscale features; and 2) the introduction of orography has a greater impact than the effect of stretching. Results presented here suggest that dynamical core integrations with both uniform and stretched grids should consider orographic forcing as an integral parr of the model dynamics. C1 Univ Maryland, Dept Meteorol, ESSIC, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. Rutgers State Univ, Dept Environm Sci, New Brunswick, NJ USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Fox-Rabinovitz, MS (reprint author), Univ Maryland, Dept Meteorol, ESSIC, College Pk, MD 20742 USA. RI Georgiy, Stenchikov/J-8569-2013 NR 29 TC 21 Z9 21 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD JUN PY 2000 VL 128 IS 6 BP 1883 EP 1898 DI 10.1175/1520-0493(2000)128<1883:AUAVRS>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 322WW UT WOS:000087533100015 ER PT J AU Keppenne, CL AF Keppenne, CL TI Data assimilation into a primitive-equation model with a parallel ensemble Kalman filter SO MONTHLY WEATHER REVIEW LA English DT Article ID QUASI-GEOSTROPHIC MODEL; LEVEL AB Data assimilation experiments are performed using an ensemble Kalman filter (EnKF) implemented for a two-layer spectral shallow water model at triangular truncation T100 representing an abstract planet covered by a strongly stratified fluid. Advantage is taken of the inherent parallelism in the EnKF by running each ensemble member on a different processor of a parallel computer. The Kalman filter update step is parallelized by letting each processor handle the observations from a limited region. The algorithm is applied to the assimilation of synthetic altimetry data in the context of an imperfect model and known representation-error statistics. The effect of finite ensemble size on the residual errors is investigated and the error estimates obtained with the EnKF are compared to the actual errors. C1 NASA, Goddard Space Flight Ctr, Seasonal Interannual Predict Project, Greenbelt, MD 20771 USA. Gen Sci Corp, Beltsville, MD USA. RP Keppenne, CL (reprint author), NASA, Goddard Space Flight Ctr, Oceans & Ice Branch, Code 971, Greenbelt, MD 20771 USA. NR 20 TC 91 Z9 99 U1 5 U2 8 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD JUN PY 2000 VL 128 IS 6 BP 1971 EP 1981 DI 10.1175/1520-0493(2000)128<1971:DAIAPE>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 322WW UT WOS:000087533100022 ER PT J AU Arabshahi, P AF Arabshahi, P TI Giving Arabs credit for Persian works (again) SO NATURE LA English DT Letter C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Arabshahi, P (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 238-343, Pasadena, CA 91109 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JUN 1 PY 2000 VL 405 IS 6786 BP 508 EP 508 DI 10.1038/35014672 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 321HF UT WOS:000087449500020 ER PT J AU Fischer, DG Ovryn, B AF Fischer, DG Ovryn, B TI Interfacial shape and contact-angle measurement of transparent samples with confocal interference microscopy (vol 25, pg 478, 2000) SO OPTICS LETTERS LA English DT Correction C1 NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, Cleveland, OH 44135 USA. Case Western Reserve Univ, Dept Aerosp & Mech Engn, Cleveland, OH 44106 USA. RP Fischer, DG (reprint author), NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, MS 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 1 TC 1 Z9 1 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD JUN 1 PY 2000 VL 25 IS 11 BP 862 EP 862 DI 10.1364/OL.25.000862 PG 1 WC Optics SC Optics GA 321MH UT WOS:000087458900031 PM 18064209 ER PT J AU Tang, CM AF Tang, CM TI Ugly fossil syndrome SO PALAIOS LA English DT Editorial Material C1 NASA, Astrobiol Inst, Washington, DC 20546 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. RP Tang, CM (reprint author), NASA, Astrobiol Inst, Washington, DC 20546 USA. NR 0 TC 2 Z9 2 U1 0 U2 0 PU SEPM-SOC SEDIMENTARY GEOLOGY PI TULSA PA 1731 E 71ST STREET, TULSA, OK 74136-5108 USA SN 0883-1351 J9 PALAIOS JI Palaios PD JUN PY 2000 VL 15 IS 3 BP 175 EP 176 DI 10.2307/3515639 PG 2 WC Geology; Paleontology SC Geology; Paleontology GA 321CB UT WOS:000087436400001 ER PT J AU Swain, JA Hartz, RS AF Swain, JA Hartz, RS TI Assessing quality in cardiac surgery: why this is necessary in the twenty-first century SO PERFUSION-UK LA English DT Article; Proceedings Paper CT Pathophysiology of Cardiopulmonary Bypass Meeting CY FEB, 1999 CL SAN DIEGO, CALIFORNIA ID PREOPERATIVE RISK ASSESSMENT; MORTALITY; DATABASE AB The cost and high-profile nature of coronary surgery means that this is an area of close public scrutiny. As much pioneering work in data collection and risk analyses has been carried out by cardiac surgeons, substantial information exists and the correct interpretation of that data is identified as an important issue. This paper considers the background and history of risk-adjustment in cardiac surgery, the uses of quality data, examines the observed/expected mortality ratio and looks at issues such as cost and reactions to outliers. The conclusion of the study is that the continuation of accurate data collection by the whole operative team and a strong commitment to constantly improving quality is crucial to its meaningful application. C1 Univ Kentucky, Coll Med, Gill Heart Inst, Lexington, KY USA. Tulane Univ, Sch Med, Dept Surg, New Orleans, LA 70112 USA. RP Swain, JA (reprint author), NASA, Code U,300 E St SW, Washington, DC 20546 USA. NR 15 TC 1 Z9 1 U1 0 U2 0 PU ARNOLD, HODDER HEADLINE PLC PI LONDON PA 338 EUSTON ROAD, LONDON NW1 3BH, ENGLAND SN 0267-6591 J9 PERFUSION-UK JI Perfusion-UK PD JUN PY 2000 VL 15 IS 3 BP 181 EP 190 PG 10 WC Cardiac & Cardiovascular Systems; Peripheral Vascular Disease SC Cardiovascular System & Cardiology GA 324XP UT WOS:000087647400002 PM 10866419 ER PT J AU Dziczek, D Ajello, JM James, GK Hansen, DL AF Dziczek, D Ajello, JM James, GK Hansen, DL TI Cascade contribution to the H-2 Lyman band system from electron impact SO PHYSICAL REVIEW A LA English DT Article ID ULTRAVIOLET SPECTROMETER; RADIATIVE LIFETIMES; MOLECULAR-HYDROGEN; EXCITATION; EMISSION; STATES; SPECTRUM AB The intensity of UV resonance transitions excited by electron impact is determined by both direct excitation and cascade processes. The lifetime for decay by spontaneous emission from a resonant state is short (typically < 10 ns). Using a pulsed electron gun technique established to separate these two effects we report a laboratory study of the UV spectrum of H-2 attributed to cascade. We utilize the longer lifetimes (> 30 ns) for cascade channels to measure the intense spectrum of the Lyman band system (B (1)Sigma(u)(+)-X (1)Sigma(g)(+)) of H-2 populated by cascade from higher lying (EF,GK,H(1)Sigma(g)(+)) states. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Dziczek, D (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Dziczek, Dariusz/G-3620-2014 NR 19 TC 8 Z9 8 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD JUN PY 2000 VL 61 IS 6 AR 064702 PG 4 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 323LY UT WOS:000087567900119 ER PT J AU Omidvar, K AF Omidvar, K TI Electron capture into Rydberg states according to the Born approximation: Correction of an error SO PHYSICAL REVIEW A LA English DT Article ID CHARGE-TRANSFER AB A general expression is derived for the Born amplitude for electron capture by bare nuclei from hydrogenic atom targets, where capture takes place into high principal, and arbitrary angular momentum, quantum numbers, n and l. Cross sections for capture into high n and l = 0,1 are given in analytic forms. The limiting values of the ratios of the Born over the Oppenheimer-Brinkman-Kramers cross sections for n much greater than 1 and l = 0,1 are found, and shown that they confirm the empirical law of Jackson and Schiff only approximately. For high angular momenta, it is shown that the Born cross section approaches the OBK cross section. An error in a previous publication by the author has been corrected. C1 NASA, Data Assimilat Off, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Omidvar, K (reprint author), NASA, Data Assimilat Off, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM omidvar@dao.gsfc.nasa.gov NR 16 TC 0 Z9 0 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD JUN PY 2000 VL 61 IS 6 AR 064701 PG 4 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 323LY UT WOS:000087567900118 ER PT J AU Lallemand, P Luo, LS AF Lallemand, P Luo, LS TI Theory of the lattice Boltzmann method: Dispersion, dissipation, isotropy, Galilean invariance, and stability SO PHYSICAL REVIEW E LA English DT Article ID NAVIER-STOKES EQUATION; RAYLEIGH-TAYLOR INSTABILITY; GAS AUTOMATA; BGK MODELS; CIRCULAR-CYLINDER; NONIDEAL GASES; LIQUID-GAS; FLOW; SIMULATIONS; FLUID AB The generalized hydrodynamics (the wave vector dependence of the transport coefficients) of a generalized lattice Boltzmann equation (LBE) is studied in detail. The generalized lattice Boltzmann equation is constructed in moment space rather than in discrete velocity space. The generalized hydrodynamics of the model is obtained by solving the dispersion equation of the linearized LEE either analytically by using perturbation technique or numerically. The proposed LEE model has a maximum number of adjustable parameters for the given set of discrete velocities. Generalized hydrodynamics characterizes dispersion, dissipation (hyperviscosities), anisotropy, and lack of Galilean invariance of the model, and can be applied to select the values of the adjustable parameters that optimize the properties of the model. The proposed generalized hydrodynamic analysis also provides some insights into stability and proper initial conditions for LEE simulations. The stability properties of some two-dimensional LEE models are analyzed and compared with each Ether in the parameter space of the mean streaming velocity and the viscous relaxation time. The procedure described in this work can be applied to analyze other LEE models. As examples, LEE models with various interpolation schemes are analyzed. Numerical results on shear how with an initially discontinuous velocity profile (shock) with or without a constant streaming velocity are shown to demonstrate the dispersion effects in the LEE model: the results compare favorably with our theoretical analysis. We also show that whereas linear analysis of the LEE evolution operator is equivalent to Chapman-Enskog analysis in the long-wavelength limit (wave vector k=0), it can also provide results for large values of k. Such results are important for the stability and other hydrodynamic properties of the LEE method and cannot be obtained through Chapman-Enskog analysis. C1 NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. Univ Paris 11, Lab ASCI, F-91405 Orsay, France. RP Lallemand, P (reprint author), NASA, Langley Res Ctr, ICASE, MS 132C,3 W Reid St,Bldg 1152, Hampton, VA 23681 USA. RI Luo, Li-Shi/A-4561-2011 OI Luo, Li-Shi/0000-0003-1215-7892 NR 47 TC 749 Z9 774 U1 16 U2 147 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1063-651X J9 PHYS REV E JI Phys. Rev. E PD JUN PY 2000 VL 61 IS 6 BP 6546 EP 6562 DI 10.1103/PhysRevE.61.6546 PN A PG 17 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA 323PZ UT WOS:000087575300067 ER PT J AU Chang, ES Engleman, R Geller, M AF Chang, ES Engleman, R Geller, M TI The 3d(2) (1)G state and the 4sng series in neutral calcium SO PHYSICS ESSAYS LA English DT Article DE calcium; energy levels; series perturbation; high-l Rydberg states; dipole polarizability; atomic fine-structure splittings; laboratory FTS spectra; infrared solar spectra ID RYDBERG SERIES; ENERGY-LEVELS; CA-I; SPECTRUM AB We have observed and analyzed high-resolution Fourier transform spectrometer laboratory spectra of calcium to confirm lines in the solar infrared spectra with substantial improvement in wavenumber accuracy. In Ca I, we have identified the 3d(2) (1)G perturber level and the 4s ng series, the singlet and the triplet, for n = 5, 6, and 7. Fitting the (1)G data to the Langer formula, we show that this perturber is responsible for the inversion of the Tg configuration. An Edlen plot for the deperturbed ng and the newly discovered 6h, 7h, and 7i levels determines the dipole polarizability of the Ca II core to be 75.40 +/- 0.05a(o)(3). The high-P levels are combined with simple theory to yield an improved ionization potential of 49305.940 +/- 0.012 cm(-1). We discuss conflicting reports on the 3d(2) (1) G level and possible implications on the 3d(2) D-1 level, as well as other discrepant results on the core polarizability. C1 Univ Massachusetts, Dept Phys & Astron, Amherst, MA 01003 USA. Univ New Mexico, Dept Chem, Albuquerque, NM 87131 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chang, ES (reprint author), Univ Massachusetts, Dept Phys & Astron, Amherst, MA 01003 USA. NR 25 TC 1 Z9 1 U1 2 U2 3 PU PHYSICS ESSAYS PUBLICATION PI HULL PA C/O ALFT INC, 189 DEVEAULT ST, UNIT NO. 7, HULL, PQ J8Z1S7, CANADA SN 0836-1398 J9 PHYS ESSAYS JI Phys. Essays PD JUN-SEP PY 2000 VL 13 IS 2-3 SI SI BP 198 EP 205 PG 8 WC Physics, Multidisciplinary SC Physics GA 428YT UT WOS:000168489800005 ER PT J AU Okong'o, N Bellan, J AF Okong'o, N Bellan, J TI A priori subgrid analysis of temporal mixing layers with evaporating droplets SO PHYSICS OF FLUIDS LA English DT Article ID LARGE-EDDY SIMULATION; DIRECT NUMERICAL-SIMULATION; DISPERSED SOLID PARTICLES; TURBULENT CHANNEL FLOW; SCALE ESTIMATION MODEL; HOMOGENEOUS TURBULENCE; ISOTROPIC TURBULENCE; 2-WAY INTERACTION; DEPOSITION; JET AB Subgrid analysis of a transitional temporal mixing layer with evaporating droplets has been performed using three sets of results from a direct numerical simulation (DNS) database, with Reynolds numbers (based on initial vorticity thickness) as large as 600 and with droplet mass loadings as large as 0.5. In the DNS, the gas phase is computed using an Eulerian formulation, with Lagrangian droplet tracking. The large eddy simulation (LES) equations corresponding to the DNS are first derived, and key assumptions in deriving them are first confirmed by using the DNS database. Since LES of this flow requires the computation of droplet source terms, it is essential to obtain the unfiltered gas-phase variables at droplet locations from filtered gas-phase variables at the grid points. This paper proposes to model these unfiltered gas-phase variables at the drop locations by assuming the gas-phase variables to be the sum of the filtered variables and a correction based on the filtered standard deviation; this correction is then computed from the subgrid scale (SGS) standard deviation. This model predicts the unfiltered variables at droplet locations considerably better than simply interpolating the filtered variables. Three methods are investigated for modeling the SGS standard deviation: the Smagorinsky approach, the gradient model and the scale-similarity formulation. When the proportionality constant inherent in the SGS models is properly calculated, the gradient and scale-similarity methods give results in excellent agreement with the DNS. (C) 2000 American Institute of Physics. [S1070-6631(00)02306-0]. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Okong'o, N (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 125-109, Pasadena, CA 91109 USA. NR 35 TC 29 Z9 29 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 JUN PY 2000 VL 12 IS 6 BP 1573 EP 1591 AR PII [S1070-6631(00)02306-0] DI 10.1063/1.870405 PG 19 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 310KE UT WOS:000086826000026 ER PT J AU Allison, M AF Allison, M TI A similarity model for the windy jovian thermocline SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Symposium on The Jovian System after Galieo/The Saturnian System before Cassini-Huygens CY MAY 11-15, 1998 CL NANTES, FRANCE SP European Union, European Space Agency, CNES, French Minist Educ Natl, CNRS, City Nantes, Univ Nantes, Reg Pays Loire, COSPAR ID GALILEO PROBE; COMET SHOEMAKER-LEVY-9; VERTICAL STRUCTURE; ANGULAR-MOMENTUM; MOIST CONVECTION; OUTER PLANETS; GIANT PLANETS; ZONAL WINDS; JUPITER; ATMOSPHERES AB A new conceptual model for the observed banded wind structure of the giant outer planets is proposed, assuming a smoothly distributed potential vorticity (PV) atop a layer of deeply seated, latitudinally variable stratification. With a vanishing horizontal entropy contrast presumably enforced at the bottom of the flow layer by the underlying convection, the thermal-wind balance of observed cloud-top motions implies a mapping of constant potential temperature surfaces, nearly vertical at upper tropospheric levels, down to a deeper, flatter, but variably sloped "thermocline". For a generally colder-poleward distribution of isentropes consistent with the strong equatorial jets of both Jupiter and Saturn, this kind of mapping would also imply a poleward decreasing static stability. The proposed temperature-stability distribution is just the reverse of the Earth's troposphere, where the strongest latitudinal potential temperature gradients are at the bottom instead of the top, with static stability generally increasing toward the pole. The warmer-stabler correlation for Jupiter would be consistent, however, with a nearly monotonic distribution of PV from low to high latitudes, over planetary scales for which the planetary vorticity dominates the relative vorticity of the jets. In this way efficient PV mixing for the isentropically bounded thermocline can account for the dynamical maintenance of the cyclonic flanks of the equatorial jet. Over latitudinal intervals comparable to the internal deformation scale, however, the gradient of the absolute vorticity is dominated by the flow curvature, correlated for a well-mixed PV distribution with the local latitudinal gradient of the static stability, itself proportional for the assumed thermocline structure to the local potential temperature gradient and therefore the local departures in geostrophic velocity. The resulting correlation of velocities and vorticity gradients would imply an alternation of the flow over the internal deformation radius set by the vertical entropy contrast. The requisite size of the deep stability is itself roughly consistent with the diagnostic interpretation of the apparent dispersive character and vertical wavelength of observed temperature oscillations in Jupiter's upper troposphere and stratosphere, as well as a plausible extrapolation of the deep sub-adiabatic lapse rate detected by the Galileo probe. Published by Elsevier Science Ltd. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Allison, M (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 80 TC 26 Z9 26 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD JUN-JUL PY 2000 VL 48 IS 7-8 BP 753 EP 774 DI 10.1016/S0032-0633(00)00032-5 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 338PK UT WOS:000088428300010 ER PT J AU Hergenrother, PM Connell, JW Smith, JG AF Hergenrother, PM Connell, JW Smith, JG TI Phenylethynyl containing imide oligomers SO POLYMER LA English DT Article DE phenylethynyl groups; imide oligomers; composite matrices ID ADHESIVE PROPERTIES; PENDENT; ANHYDRIDES; POLYIMIDES; CHEMISTRY AB As part of a program to develop high performance/high temperature adhesives and composite matrices for a Mach 2.4 high speed civil transport, imide oligomers containing phenylethynyl groups were investigated. Phenylethynyl groups were placed on the ends of oligomers of different molecular weights (1250, 2500 and 5000 g/mol), pendent along the backbone of oligomers and both pendent and terminal on oligomers. Many different compositions of phenylethynyl containing imide oligomers had been previously prepared and evaluated before selecting the composition based upon 3,3',4,4'-biphenyltetracarboxcylic dianhydride (BPDA), 3,4'-oxydianiline (3,4'-ODA) and 1,3-bis(3-aminophenoxy)benzene (APB) for extensive work. 4-Phenylethynylphthalic anhydride (PEPA) was used to place phenylethynyl groups on the ends of the oligomers and 3,5-diamino-4'-phenylethynylbenzophenone (DPEB) was used to introduce pendent phenylethynyl groups along the oligomeric backbone. Upon heating above 300 degrees C, the phenylethynyl groups react to provide chain extension, branching and cross linking. Several of these materials exhibited excellent properties as adhesives and composite matrices. The chemistry, processability and properties of the oligomers, the cued polymers, bonded specimens and composites from phenylethynyl containing oligomers are presented. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Hergenrother, PM (reprint author), NASA, Langley Res Ctr, Mail Stop 226,6A W Taylor St, Hampton, VA 23681 USA. NR 28 TC 63 Z9 74 U1 4 U2 22 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0032-3861 J9 POLYMER JI Polymer PD JUN PY 2000 VL 41 IS 13 BP 5073 EP 5081 DI 10.1016/S0032-3861(99)00569-8 PG 9 WC Polymer Science SC Polymer Science GA 299EB UT WOS:000086181800032 ER PT J AU Ooi, IH Hergenrother, PM Harris, FW AF Ooi, IH Hergenrother, PM Harris, FW TI Synthesis and properties of phenylethynyl-terminated, star-branched, phenylquinoxaline oligomers SO POLYMER LA English DT Article DE polyphenylquinoxalines; star-branched; phenylquinoxaline oligomers AB The primary objective of this work was to prepare readily melt and solution processable phenylquinoxaline (PQ) oligomers that could be thermally crosslinked to solvent-resistant resins. Thus, a mixture of 2-(4-hydroxyphenyl)-3-phenyl-6-fluoroquinoxaline and 3-(4-hydroxy-phenyl)-2-phenyl-6-fluoroquinoxaline (HPFQ) was used to prepare star-branched PQ oligomers end-capped with 4-fluoro-4'-phenylethynylbenzophenone (FPEB). 1,1,1-Tris(4- hydroxyphenyl)ethane (THPE) was used as the branching unit. The oligomer number-average molecular weights ((M) over bar(n)s) as determined by size exclusion chromatography (SEC) were close to the calculated values of 2922, 4698, 6474, and 13,578 g/mol, and their intrinsic viscosities ranged from 0.16 to 0.57 dl/g (m-cresol at 30 degrees C). The oligomers, which were quite soluble in common organic solvents, had glass transition temperatures (T(g)s) that ranged from 181 to 233 degrees C (DSC, Delta T = 20 degrees C/min). They also underwent an exothermic cure with maxima from 377 to 443 degrees C. The T(g)s of the cured oligomers ranged from 259 to 284 degrees C depending on the oligomer (M) over bar(n) and the curing conditions. The oligomers had low melt viscosities, e.g. an oligomer (SPQ-46) with an (M) over bar(n), of 4816 g/mol (SEC) had a melt viscosity of 150 Pa s at 348 degrees C. A cured thin film of SPQ-46, which was insoluble in common organic solvents, had a room-temperature (RT) tensile strength of 100 MPa, a RT modulus of 2358 MPa, and a RT elongation of 5.9%. A cured sample of SPQ-46 displayed a RT titanium-titanium lap shear tensile strength of 35.2 MPa. SPQ-46/carbon fiber(IM-7) composites were prepared that displayed a RT flexural strength of 1902 MPa, a RT modulus of 1.38 GPa and a RT open hole compressive strength of 433 MPa. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Akron, Maurice Morton Inst, Akron, OH 44325 USA. Univ Akron, Dept Polymer Sci, Akron, OH 44325 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Harris, FW (reprint author), Univ Akron, Maurice Morton Inst, Akron, OH 44325 USA. NR 38 TC 14 Z9 14 U1 1 U2 5 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0032-3861 J9 POLYMER JI Polymer PD JUN PY 2000 VL 41 IS 13 BP 5095 EP 5107 DI 10.1016/S0032-3861(99)00572-8 PG 13 WC Polymer Science SC Polymer Science GA 299EB UT WOS:000086181800034 ER PT J AU Burian, BK Slimp, AOC AF Burian, BK Slimp, AOC TI Social dual-role relationships during internship: A decision-making model SO PROFESSIONAL PSYCHOLOGY-RESEARCH AND PRACTICE LA English DT Article ID ETHICS CODE; PSYCHOLOGISTS; PSYCHOTHERAPY; SUPERVISION; MANAGEMENT; BOUNDARIES AB During the predoctoral internship year, training staff and interns are often faced with the prospect of entering into social multiple-role relationships with each other. Such relationships can initially appear benign, and at times be beneficial but may pose some risk of harm both to interns and training staff. Building on the previous work of P. A. O' Connor Slimp and B. K. Burian (1994), a decision-making model is offered regarding social multiple-role relationships between interns and their trainers. It is designed to raise awareness of the issues involved in these relationships and provide structure in assessing their potential for harm. C1 Univ Baltimore, Baltimore, MD 21201 USA. RP Burian, BK (reprint author), NASA, Ames Res Ctr, IHS Mail Stop 262-4, Moffett Field, CA 94035 USA. NR 30 TC 11 Z9 11 U1 0 U2 2 PU AMER PSYCHOLOGICAL ASSOC PI WASHINGTON PA 750 FIRST ST NE, WASHINGTON, DC 20002-4242 USA SN 0735-7028 J9 PROF PSYCHOL-RES PR JI Prof. Psychol.-Res. Pract. PD JUN PY 2000 VL 31 IS 3 BP 332 EP 338 DI 10.1037//0735-7028.31.3.332 PG 7 WC Psychology, Multidisciplinary SC Psychology GA 324EK UT WOS:000087608700016 ER PT J AU Castellano, T AF Castellano, T TI A search for planetary transits of the star HD 187123 by spot filter CCD differential photometry SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article AB A novel method for performing high-precision, time-series CCD differential photometry of bright stars using a spot filter is demonstrated. Results for several nights of observing of the 51 Pegasi b-type planet-bearing star HD 187123 are presented. Photometric precision of 0.0015-0.0023 mag is achieved. No transits are observed at the epochs predicted from the radial velocity observations. If the planet orbiting HD 187123 at 0.04 AU is an inflated Jupiter similar in radius to HD 209458b, it would have been detected at greater than the 6 sigma level if the orbital inclination is near 90 degrees and at greater than the 3 sigma level if the orbital inclination is as small as 82 degrees.7. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Santa Cruz, Dept Astron & Astrophys, Santa Cruz, CA 95064 USA. RP Castellano, T (reprint author), NASA, Ames Res Ctr, MS 245-6, Moffett Field, CA 94035 USA. NR 18 TC 2 Z9 2 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD JUN PY 2000 VL 112 IS 772 BP 821 EP 826 DI 10.1086/316586 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 328PE UT WOS:000087858600007 ER PT J AU Feibelman, WA AF Feibelman, WA TI IUE spectra and emission-line fluxes for eight planetary nebulae SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID CENTRAL STARS; MAGNITUDES AB We present IUE spectra and observed emission-line fluxes for the planetary nebulae NGC 2438, NGC 2610, NGC 5307, NGC 6620, NGC 7354, K3-27, PB 8, and He 2-182. All data have been processed by the final archive NEWSIPS routines. PB 8 and He 2-182 display strong C rv lambda 1549 P Cygni profiles from which terminal wind velocities of -2835 +/- 500 km s(-1) and -2350 +/- 500 km s(-1), respectively, were determined. 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 12 TC 5 Z9 5 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD JUN PY 2000 VL 112 IS 772 BP 861 EP 866 DI 10.1086/316584 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 328PE UT WOS:000087858600014 ER PT J AU Ponomarev, AL Brenner, D Hlatky, LR Sachs, RK AF Ponomarev, AL Brenner, D Hlatky, LR Sachs, RK TI A polymer, random walk model for the size-distribution of large DNA fragments after high linear energy transfer radiation SO RADIATION AND ENVIRONMENTAL BIOPHYSICS LA English DT Article ID DOUBLE-STRAND BREAKS; FIELD GEL-ELECTROPHORESIS; INTERPHASE CHROMOSOMES; IONIZING-RADIATION; TRACK STRUCTURE; FUNCTIONAL COMPARTMENTALIZATION; MAMMALIAN-CELLS; SIMULATION; CLUSTERS; IRRADIATION AB DNA double-strand breaks (DSBs) produced by densely ionizing radiation are not located randomly in the genome: recent data indicate DSB clustering along chromosomes. Stochastic DSB clustering at large scales, from >100 Mbp down to <0.01 Mbp, is modeled using computer simulations and analytic equations. A random-walk, coarse-grained polymer model for chromatin is combined with a simple track structure model in Monte Carlo software called DNAbreak and is applied to data on alpha-particle irradiation of V-79 cells. The chromatin model neglects molecular details but systematically incorporates an increase in average spatial separation between two DNA loci as the number of base-pairs between the loci increases. Fragment-size distributions obtained using DNAbreak match data on large fragments about as well as distributions previously obtained with a less mechanistic approach. Dose-response relations, linear at small doses of high linear energy transfer (LET) radiation, are obtained. They are found to be non-linear when the dose becomes so large that there is a significant probability of overlapping or close juxtaposition, along one chromosome, for different DSB clusters from different tracks. The non-linearity is more evident for large fragments than for small. The DNAbreak results furnish an example of the RLC (randomly located clusters) analytic formalism, which generalizes the broken-stick fragment-size distribution of the random-breakage model that is often applied to low-LET data. C1 NASA, ISC, Houston, TX 77058 USA. Univ Calif Berkeley, Ctr Pure & Appl Math, Berkeley, CA 94720 USA. Columbia Univ, Ctr Radiol Res, New York, NY 10032 USA. Harvard Univ, Sch Med, Joint Ctr Radiat Therapy, Boston, MA 02115 USA. RP Ponomarev, AL (reprint author), NASA, ISC, Mail Code SN, Houston, TX 77058 USA. FU NCI NIH HHS [CA-49062]; NCRR NIH HHS [RR-11623]; NIGMS NIH HHS [GM 57245] NR 51 TC 17 Z9 18 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0301-634X J9 RADIAT ENVIRON BIOPH JI Radiat. Environ. Biophys. PD JUN PY 2000 VL 39 IS 2 BP 111 EP 120 DI 10.1007/s004119900040 PG 10 WC Biology; Biophysics; Environmental Sciences; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Environmental Sciences & Ecology; Radiology, Nuclear Medicine & Medical Imaging GA 334TC UT WOS:000088200900005 PM 10929379 ER PT J AU Cucinotta, FA Wilson, JW Williams, JR Dicello, JF AF Cucinotta, FA Wilson, JW Williams, JR Dicello, JF TI Analysis of MIR-18 results for physical and biological dosimetry: radiation shielding effectiveness in LEO SO RADIATION MEASUREMENTS LA English DT Article ID DOUBLE-STRAND BREAKS; LOW-ENERGY PROTONS; CHROMOSOMAL-ABERRATIONS; MAMMALIAN-CELLS; MUTATION-INDUCTION; IONIZING-RADIATION; BLOOD-LYMPHOCYTES; HEAVY-IONS; DNA-DAMAGE; V79 CELLS AB We compare models of radiation transport and biological response to physical and biological dosimetry results from astronauts on the Mir space station. Transport models are shown to be in good agreement with physical measurements and indicate that the ratio of equivalent dose from the Galactic Cosmic Rays (GCR) to protons is about 3/2:1 and that this ratio will increase for exposures to internal organs. Two biological response models are used to compare to the Mir biodosimetry for chromosome aberration in lymphocyte cells; a track-structure model and the linear-quadratic model with linear energy transfer (LET) dependent weighting coefficients. These models are fit to in vitro data for aberration formation in human lymphocytes by photons and charged particles. Both models are found to be in reasonable agreement with data for aberrations in lymphocytes of Mir crew members: however there are differences between the use of LET dependent weighting factors and track structure models for assigning radiation quality factors. The major difference in the models is the increased effectiveness predicted by the track model for low charge and energy ions with LET near 10 keV/mu m. The results of our calculations indicate that aluminum shielding, although providing important mitigation of the effects of trapped radiation, provides no protective effect from the galactic cosmic rays (GCR) in low-earth orbit (LEO) using either equivalent dose or the number of chromosome aberrations as a measure until about 100 g/cm(2) of material is used. Published by Elsevier Science Ltd. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NASA, Langley Res Ctr, Hampton, VA USA. Johns Hopkins Med Sch, Ctr Oncol, Baltimore, MD 21287 USA. RP Cucinotta, FA (reprint author), NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 50 TC 34 Z9 35 U1 3 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1350-4487 J9 RADIAT MEAS JI Radiat. Meas. PD JUN PY 2000 VL 32 IS 3 BP 181 EP 191 DI 10.1016/S1350-4487(99)00273-5 PG 11 WC Nuclear Science & Technology SC Nuclear Science & Technology GA 310YU UT WOS:000086857800006 PM 11543368 ER PT J AU Grubbs, R Lindblom, W George, S AF Grubbs, R Lindblom, W George, S TI NASA's myriad uses of digital video SO SMPTE JOURNAL LA English DT Article; Proceedings Paper CT 141st SMPTE Technical Conference CY NOV 19-22, 1999 CL NEW YORK, NEW YORK SP Soc Mot Picture & Televis Engineers AB Since its inception, NASA has created many of the most memorable images of the past century. From the fuzzy video of Neil Armstrong taking that first step on the moon to images of the Mars surface available to all on the internet, it has provided visuals to inspire a generation, all because a scientist or researcher had a requirement to see something unusual. Digital television technology will give NASA unprecedented new tools for acquiring, analyzing, and distributing video. This paper will explore its DTV future. The agency requires the realtime transfer of video between NASA centers. Specifics will be provided relating to the video infrastructure, including video from the space shuttle and various centers. The pros and cons of interlace and progressive scanned images will be presented and compared. Film is a major component of NASA's image acquisition for analysis usage. The future of film within the context of DTV will be explored. C1 NASA, George C Marshall Space Flight Ctr, DTV Working Grp, Huntsville, AL USA. Comp Sci Corp, Huntsville, AL USA. RP Grubbs, R (reprint author), NASA, George C Marshall Space Flight Ctr, DTV Working Grp, Huntsville, AL USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU SOC MOTION PICTURE TV ENG INC PI WHITE PLAINS PA 595 WEST HARTSDALE AVE, WHITE PLAINS, NY 10607 USA SN 0036-1682 J9 SMPTE J JI SMPTE J. PD JUN PY 2000 VL 109 IS 6 BP 484 EP 489 PG 6 WC Engineering, Electrical & Electronic; Instruments & Instrumentation; Imaging Science & Photographic Technology; Telecommunications SC Engineering; Instruments & Instrumentation; Imaging Science & Photographic Technology; Telecommunications GA 321WA UT WOS:000087476600005 ER PT J AU Plunkett, SP Vourlidas, A Simberova, S Karlicky, M Kotrc, P Heinzel, P Kupryakov, YA Guo, WP Wu, ST AF Plunkett, SP Vourlidas, A Simberova, S Karlicky, M Kotrc, P Heinzel, P Kupryakov, YA Guo, WP Wu, ST TI Simultaneous SOHO and ground-based observations of a large eruptive prominence and coronal mass ejection SO SOLAR PHYSICS LA English DT Article ID MAGNETIC-FLUX ROPE; LOOP TRANSIENTS; SOLAR MINIMUM; CLOUDS; LASCO; EIT; STREAMER; FIELDS; SKYLAB; SHOCK AB Coronal mass ejections (CMEs) are frequently associated with erupting prominences near the solar surface. A spectacular eruption of the southern polar crown prominence was observed on 2 June 1998, accompanied by a CME that was well-observed by the LASCO coronagraphs on SOHO. The prominence was observed in its quiescent state and was followed throughout its eruption by the SOHO EIT and later by LASCO as the bright, twisted core of the CME. Ground-based Hot observations of the prominence were obtained at the Ondrejov Observatory in the Czech Republic. A gnat deal of fine structure was observed within the prominence as it erupted. The prominence motion was found to rotate about its axis as it moved outward. The CME contained a helical structure that is consistent with the ejection of a magnetic flux rope from the Sun. Similar structures have been observed by LASCO in many other CMEs. The relationship of the Bur rope to other structures in the CME is often not clear. In this event, the prominence clearly lies near the trailing edge of the structure identified as a flux rope. This structure can be observed from the onset of the CME in the low corona all the way out to the edge of the LASCO field of view. The initiation and evolution of the CME are modeled using a fully self-consistent, 3D axisymmetric, MHD code. C1 USN, Res Lab, Univ Space Res Assoc, Washington, DC 20375 USA. George Mason Univ, Computat Sci Inst, Ctr Earth Observing & Space Res, Fairfax, VA 22030 USA. Acad Sci Czech Republic, Inst Astron, CS-25165 Ondrejov, Czech Republic. Moscow MV Lomonosov State Univ, Sternberg Astron Inst, Moscow 119899, Russia. Univ Alabama, Ctr Space Plasma & Aeron Res, Huntsville, AL 35899 USA. Univ Alabama, Dept Mech & Aerosp Engn, Huntsville, AL 35899 USA. RP NASA, Goddard Space Flight Ctr, Mail Code 682-3, Greenbelt, MD 20771 USA. EM plunkett@cronus.nrl.navy.mil RI Vourlidas, Angelos/C-8231-2009; Simberova, Stanislava/G-7515-2012; Karlicky, Marian/G-9023-2014; Kotrc, Pavel/G-9030-2014; Heinzel, Petr/G-9014-2014 OI Vourlidas, Angelos/0000-0002-8164-5948; Simberova, Stanislava/0000-0003-3277-3924; NR 38 TC 98 Z9 100 U1 0 U2 4 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 EI 1573-093X J9 SOL PHYS JI Sol. Phys. PD JUN PY 2000 VL 194 IS 2 BP 371 EP 391 DI 10.1023/A:1005287524302 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 362TY UT WOS:000089795400012 ER PT J AU Das, NC Monroy, C Jhabvala, M AF Das, NC Monroy, C Jhabvala, M TI Germanium junction field effect transistor for cryogenic applications SO SOLID-STATE ELECTRONICS LA English DT Article ID JFETS AB The n-channel germanium junction field effect transistor (Ge-JFET) was designed and fabricated for cryogenic applications. Ideal device current and voltage characteristics were obtained at cryogenic temperatures down to the liquid helium temperature (4.2 K). The Ge-JFET exhibits a superior noise performance at the liquid nitrogen temperature (77 K). From the device current voltage characteristics of n-channel JFETs, it is seen that the transconductance increases monotonically with the lowering of temperature to 4.2 K. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Solid State Device Branch, Greenbelt, MD 20771 USA. Raytheon ITSS, Lanham, MD 20706 USA. RP Das, NC (reprint author), NASA, Goddard Space Flight Ctr, Solid State Device Branch, Bldg 11 Rm E41,Code 553, Greenbelt, MD 20771 USA. NR 10 TC 5 Z9 7 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0038-1101 J9 SOLID STATE ELECTRON JI Solid-State Electron. PD JUN PY 2000 VL 44 IS 6 BP 937 EP 940 DI 10.1016/S0038-1101(00)00013-7 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied; Physics, Condensed Matter SC Engineering; Physics GA 312RG UT WOS:000086956200008 ER PT J AU Kimball, JS Keyser, AR Running, SW Saatchi, SS AF Kimball, JS Keyser, AR Running, SW Saatchi, SS TI Regional assessment of boreal forest productivity using an ecological process model and remote sensing parameter maps SO TREE PHYSIOLOGY LA English DT Article DE BIOME-BGC; BOREAS; carbon cycle; ecosystem modeling; net primary production; NPP; radar; SAR ID NET PRIMARY PRODUCTION; LEAF-AREA INDEX; CARBON EXCHANGE; BLACK SPRUCE; JACK PINE; CLIMATIC VARIABILITY; SEASONAL-VARIATION; ATMOSPHERIC CO2; PICEA-MARIANA; ASPEN FOREST AB An ecological process model (BIOME-BGC) was used to assess boreal forest regional net primary production (NPP) and response to short-term, year-to-year weather fluctuations based on spatially explicit, land cover and biomass maps derived by radar remote sensing, as well as soil, terrain and daily weather information. Simulations were conducted at a 30-m spatial resolution, over a 1205 km(2) portion of the BOREAS Southern Study Area of central Saskatchewan, Canada, over a 3-year period ( 1994-1996). Simulations of NPP for the study region were spatially and temporally complex, averaging 2.2 (+/- 0.6), 1.8 (+/- 0.5) and 1.7 (+/- 0.5) Mg C ha(-1) year(-1) for 1994, 1995 and 1996, respectively. Spatial variability of NPP was strongly controlled by the amount of aboveground biomass, particularly photosynthetic leaf area, whereas biophysical differences between broadleaf deciduous and evergreen coniferous vegetation were of secondary importance. Simulations of NPP were strongly sensitive to year-to-year variations in seasonal weather patterns, which influenced the timing of spring thaw and deciduous bud-burst. Reductions in annual NPP of approximately 17 and 22% for 1995 and 1996, respectively, were attributed to 3- and 5-week delays in spring thaw relative to 1994. Boreal forest stands with greater proportions of deciduous vegetation were more sensitive to the timing of spring thaw than evergreen coniferous stands. Similar relationships were found by comparing simulated snow depth records with 10-year records of aboveground NPP measurements obtained from biomass harvest plots within the BOREAS region. These results highlight the importance of sub-grid scale land cover complexity in controlling boreal forest regional productivity, the dynamic response of the biome to short-term interannual climate variations, and the potential implications of climate change and other large-scale disturbances. C1 NASA, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Montana, Sch Forestry, Numer Terradynam Simulat Grp, Missoula, MT 59812 USA. RP Kimball, JS (reprint author), Univ Montana, Flathead Lake Biol Stn, 311 Bio Stn Lane, Polson, MT 59860 USA. NR 75 TC 67 Z9 67 U1 2 U2 17 PU HERON PUBLISHING PI VICTORIA PA 202, 3994 SHELBOURNE ST, VICTORIA, BC V8N 3E2, CANADA SN 0829-318X J9 TREE PHYSIOL JI Tree Physiol. PD JUN PY 2000 VL 20 IS 11 BP 761 EP 775 PG 15 WC Forestry SC Forestry GA 325HT UT WOS:000087670700007 ER PT J AU Smith, LC Alsdorf, DE Magilligan, FJ Gomez, B Mertes, LAK Smith, ND Garvin, JB AF Smith, LC Alsdorf, DE Magilligan, FJ Gomez, B Mertes, LAK Smith, ND Garvin, JB TI Estimation of erosion, deposition, and net volumetric change caused by the 1996 Skeioararsandur jokulhlaup, Iceland, from synthetic aperture radar interferometry SO WATER RESOURCES RESEARCH LA English DT Article ID GJALP SUBGLACIAL ERUPTION; ICE-SHEET; LANDERS EARTHQUAKE; KILAUEA VOLCANO; SAR; RIVER; VATNAJOKULL; TOPOGRAPHY; DISCHARGE; SEDIMENT AB Using repeat-pass satellite synthetic aperture radar interferometry, we develop a methodology to measure flood-induced erosion and deposition and apply it to a record 1996 glacier outburst flood (jokulhlaup) on Skeioararsandur, Iceland. The procedures include (1) coregistration of backscatter intensity images to observe morphological differences; (2) mapping of interferometric phase correlation to identify preserved and modified surfaces; and (3) construction, correction, and differencing of pre-jokulhlaup and post-jokulhlaup topography. Procedures 1 and 2 are robust and should be widely applicable to other fluvial environments, while procedure 3 is complicated by uncertainties in phase measurement, baseline estimate, and atmospheric effects. After a correction procedure involving interpolation of digital elevation model elevation differences across low-correlation areas, we find similar to 4 m of elevation change are required to calculate volumes of erosion or deposition. This condition was satisfied for the 40 km(2) proglacial zone of Skeioararsandur, where we estimate +38 x 10(6) m(3) of net sediment deposition along the ice margin, -25 x 10(6) m(3) of net erosion in channels downstream, and a total net balance of +13 x 10(6). These estimates are supported by field observations and survey data collected in 1997. C1 Univ Calif Los Angeles, Dept Geog, Los Angeles, CA 90095 USA. Univ Calif Santa Barbara, Inst Computat Earth Syst Sci, Santa Barbara, CA 93106 USA. Dartmouth Coll, Dept Geog, Hanover, NH 03755 USA. Indiana State Univ, Geomorphol Lab, Terre Haute, IN 47809 USA. Univ Calif Santa Barbara, Dept Geog, Santa Barbara, CA 93106 USA. Univ Nebraska, Dept Geosci, Lincoln, NE 68588 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Smith, LC (reprint author), Univ Calif Los Angeles, Dept Geog, 1255 Bunche Hall,Box 951524,405 Hilgard Ave, Los Angeles, CA 90095 USA. EM lsmith@geog.ucla.edu; alsdorf@icess.ucsb.edu; Francis.J.Magilligan@Dartmouth.edu; gegomez@scifac.indstate; leal@pollux.ucsb.edu; nsmith@unl.edu; garvin@denali.gsfc.nasa.gov RI Smith, Laurence/E-7785-2012; Last, First/A-6350-2013 OI Smith, Laurence/0000-0001-6866-5904; NR 54 TC 36 Z9 39 U1 3 U2 7 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 JUN PY 2000 VL 36 IS 6 BP 1583 EP 1594 DI 10.1029/1999WR900335 PG 12 WC Environmental Sciences; Limnology; Water Resources SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Water Resources GA 317LL UT WOS:000087226800019 ER PT J AU Schwartz, BE Benjamin, SG Green, SM Jardin, MR AF Schwartz, BE Benjamin, SG Green, SM Jardin, MR TI Accuracy of RUC-1 and RUC-2 wind and aircraft trajectory forecasts by comparison with ACARS observations SO WEATHER AND FORECASTING LA English DT Article ID SYSTEM; TEMPERATURE; MODEL AB As part of an investigation into terminal airspace productivity sponsored by the NASA Ames Research Center, a study was performed at the Forecast Systems Laboratory to investigate sources of wind forecast error and to assess differences in wind forecast accuracy between the 60-km Rapid Update Cycle, version 1 (RUC-1), and the newer 40-km RUC-2. Improved knowledge of these errors is important for development of air traffic management automation tools under development at NASA Ames and elsewhere. This information is also useful for operational users of RUC forecast winds. To perform this study, commercial aircraft reports of wind reported through Aircraft Communications, Addressing, and Reporting System (ACARS) were collected in a region over the western and central United States for a 13-month period, along with RUC-1 and RUC-2 wind forecasts. Differences between forecasts and ACARS observations and estimates of ACARS wind observation error itself were both calculated. It was found that rms vector differences between observations and forecasts from either version of the RUC increased as wind speed increased, and also as altitude increased and in winter months (both associated with higher wind speed). Wind errors increased when thunderstorms were nearby and were smaller in wintertime precipitation situations. The study also showed that considerable progress has been made in the accuracy of wind forecasts to be used for air traffic management by the introduction of the RUC-2 system, replacing the previous RUC-1 system. Improvement was made both in the intrinsic accuracy as well as in the time availability, both contributing to the overall improvement in the actual wind forecast available for air traffic management purposes. Using 3-h forecasts, RUC-2 demonstrated a reduction in mean daily rms vectors of approximately 10% over that for RUC-1 based on accuracy improvements alone. This error reduction increased to about 22% when time availability improvements were added. it was also found that the degree of improvement from the RUC-2 increased substantially for periods with a large number of significant wind errors. The percentage of individual vector errors greater than 10 m s(-1) was reduced by RUC-2 from 8% (RUC-1) to 3% overall and from 17% to 7% during the worst month. Such peak error periods have a strong impact on air traffic management automation tools. Last, it was found that the estimated trajectory projection errors from the RUC-2 using 1-2-h forecasts averaged 9 s for ascent/descent flight segments of approximately 15 min, and about 10 s for en route segments of the same duration. C1 NOAA, ERL, Forecast Syst Lab, Boulder, CO 80301 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Schwartz, BE (reprint author), NOAA, ERL, Forecast Syst Lab, 325 Broadway, Boulder, CO 80301 USA. RI Benjamin, Stan/C-5818-2015 OI Benjamin, Stan/0000-0002-5751-8236 NR 23 TC 15 Z9 15 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0882-8156 J9 WEATHER FORECAST JI Weather Forecast. PD JUN PY 2000 VL 15 IS 3 BP 313 EP 326 DI 10.1175/1520-0434(2000)015<0313:AORARW>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 323AZ UT WOS:000087543800004 ER PT J AU Ghosh, A Wondimagegn, T Parusel, ABJ AF Ghosh, A Wondimagegn, T Parusel, ABJ TI Electronic structure of gallium, copper, and nickel complexes of corrole. High-valent transition metal centers versus noninnocent ligands SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID DENSITY-FUNCTIONAL CALCULATIONS; CATION RADICALS; IONIZATION-POTENTIALS; PORPHYRINS AB Using regular nonlocal density functional theory (DFT) as well as combined DFT and configuration interaction calculations, we have carried out a first theoretical study of the electronic structure of metallocorroles. The valence orbital energy spectra and the calculated electronic absorption spectrum of (Cor)Ga (Cor(3-) = corrolato), a prototype non-transition-metal carrole, are qualitatively similar to those of a metalloporphyrin such as zinc porphyrin. The "four-orbital model" holds well for corroles. The a(2) and b(1) KOMOs of (Cor)Ga are crude analogues of the well-known a(1u) and a(2u) porphyrin HOMOs, respectively. Thus, as in the case of porphyrins, there are two nearly equienergetic pi-cation radical states for corroles. DFT also appears to provide a good description of the stabilization of high-valent transition-metal centers and of Ligand noninnocence, two intertwined and central themes in metallocorrole chemistry. The calculated ground state of (Cor)Cu is a diamagnetic d(8) Cu(III) state, with Cu(II) pi-cation radical states only slightly higher in energy, which faithfully mirrors the experimental scenario. In contrast, there are no known Cu(UT) porphyrin complexes. For (Cor)Ni, low-spin Ni(II) x-cation radical states are significantly lower in energy than a Ni(III) state, again consistent with experiment, reflecting the favorable energetics of d(8) square planar complexes. The various optimized geometries reveal significant, characteristic structural changes accompanying the formation of A(2)- and B-1-type corrole pi-cation radicals. We predict that the resonance Raman spectra of metallocorroles should reflect these structural features and, thereby, assist in the assignment of valence tautomeric states of transition-metal corrole complexes. C1 Univ Tromso, Inst Chem, N-9037 Tromso, Norway. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Ghosh, A (reprint author), Univ Tromso, Inst Chem, N-9037 Tromso, Norway. RI Ghosh, Abhik/G-8164-2016 OI Ghosh, Abhik/0000-0003-1161-6364 NR 36 TC 123 Z9 124 U1 9 U2 53 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD MAY 31 PY 2000 VL 122 IS 21 BP 5100 EP 5104 DI 10.1021/ja9943243 PG 5 WC Chemistry, Multidisciplinary SC Chemistry GA 323HH UT WOS:000087559700010 ER PT J AU Pindera, MJ Aboudi, J Arnold, SM AF Pindera, MJ Aboudi, J Arnold, SM TI The effect of interface roughness and oxide film thickness on the inelastic response of thermal barrier coatings to thermal cycling SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article DE interfacial roughness; oxide film thickness; thermal barrier coating; thermal cycling ID BEHAVIOR AB The effects of interfacial roughness and oxide film thickness on thermally-induced stresses in plasma-sprayed thermal barrier coatings subjected to thermal cycling are investigated using the recently developed higher-order theory for functionally graded materials. The higher-order theory is shown to be a viable alternative to the finite-element approach, capable of modeling different interfacial roughness architectures in the presence of an aluminum oxide layer and capturing the high stress gradients that occur at the top coat-bond coat interface. The oxide layer thickness is demonstrated to have a substantially greater effect on the evolution of residual stresses than local variations in interfacial roughness. Further, the location of delamination initiation in the top coat is predicted to change with increasing oxide layer thickness. This result can be used to optimize the thickness of a pre-oxidized layer introduced at the top coat-bond coat interface in order to enhance TBC durability as suggested by some researchers. The results of our investigation also support a recently proposed hypothesis regarding delamination initiation and propagation in the presence of an evolving bond coat oxidation, while pointing to the importance of interfacial roughness details and specimen geometry in modeling this phenomenon. (C) 2000 Elsevier Science S.A. All rights reserved. C1 Univ Virginia, Dept Civil Engn & Appl Mech, Charlottesville, VA 22903 USA. Tel Aviv Univ, IL-69978 Tel Aviv, Israel. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Pindera, MJ (reprint author), Univ Virginia, Dept Civil Engn & Appl Mech, Thornton Hall, Charlottesville, VA 22903 USA. EM mp3g@smarek.ceam.virginia.edu NR 19 TC 38 Z9 38 U1 0 U2 17 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD MAY 31 PY 2000 VL 284 IS 1-2 BP 158 EP 175 DI 10.1016/S0921-5093(00)00750-4 PG 18 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 311VL UT WOS:000086906500019 ER PT J AU Byutner, OG Smith, GD AF Byutner, OG Smith, GD TI Quantum chemistry based force field for simulations of poly(vinylidene fluoride) SO MACROMOLECULES LA English DT Article ID MOLECULAR-DYNAMICS SIMULATIONS; MODEL MOLECULES; AB-INITIO; 1,2-DIMETHOXYETHANE; MELTS AB A classical potential function for simulations of poly(vinylidene fluoride) (PVDF) based upon quantum chemistry calculations on PVDF oligomers has been developed. Quantum chemistry analysis of the geometries and conformational energies of 1,1,1,3,3-pentafluorobutane (PFB), 1,1,1,3,3,5,5,5-octofluoropentane (OFP), 2,2,4,4-tetrafluoropentane (TFP), and 2,2,4,4,6,6-hexafluoroheptane (HFH) was undertaken. In addition, an ab initio investigation of the energies of CF4-CF4 and CH4-CF4 dimers was performed. The classical potential function accurately reproduces the molecular geometries and conformational energies of the PVDF oligomers as well as intermolecular interactions between CH4 and CF4. To validate the force field, molecular dynamics simulations of a PVDF melts have been carried out at several temperatures. Simulation results are in good agreement with extant experimental data for PVT properties for amorphous PVDF as well as for PVDF chain dimensions. 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 Smith, GD (reprint author), Univ Utah, Dept Mat Sci & Engn, 122 S Cent Campus Dr,Room 304, Salt Lake City, UT 84112 USA. NR 26 TC 27 Z9 27 U1 4 U2 12 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0024-9297 J9 MACROMOLECULES JI Macromolecules PD MAY 30 PY 2000 VL 33 IS 11 BP 4264 EP 4270 DI 10.1021/ma9918295 PG 7 WC Polymer Science SC Polymer Science GA 320AF UT WOS:000087378300045 ER PT J AU Guo, XZ Mathews, DF Mikaelian, G Khakoo, MA Crowe, A Kanik, I Trajmar, S Zeman, V Bartschat, K Fontes, CJ AF Guo, XZ Mathews, DF Mikaelian, G Khakoo, MA Crowe, A Kanik, I Trajmar, S Zeman, V Bartschat, K Fontes, CJ TI Differential cross sections for electron-impact excitation of krypton at low incident energies: I. Excitation of the 4p(5)5s configuration SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID HEAVY NOBLE-GASES; SPIN-POLARIZED ELECTRONS; NEAR-THRESHOLD; ORIENTATION PARAMETERS; RESONANCE RADIATION; R-MATRIX; SCATTERING; STATES; KR; XE AB The electron-impact excitation of the individual levels that constitute the 4p(5)5s configuration of Kr is experimentally and theoretically investigated at incident electron energies of 20.0, 15.0, 13.5 and 12.0 eV, for scattering angles ranging from 10 degrees to 135 degrees. High resolution electron energy-loss spectroscopy is used to obtain spectral intensities for the excitation of each of the four 4p55s levels from the ground state. The intensities lead to three differential cross section ratios. Absolute electron-impact excitation cross sections are then determined by normalization to elastic scattering cross sections using the conventional inelastic to elastic normalization method. The present theoretical cross sections are calculated using two different methods, namely the R-matrix method and the unitarized first-order many-body theory. Comparisons between the experimental and the theoretical results show some good agreement, but reveal areas where significant improvement of the present models is needed. Additionally, it is shown that in the present case, just as in general for the rare gases, differential cross section ratios provide a sensitive test of theoretical models as well as unique insights concerning relativistic effects in the scattering process. Comparisons with existing models and other experimental data are also presented. C1 Calif State Univ Fullerton, Dept Phys, Fullerton, CA 92834 USA. Univ Newcastle Upon Tyne, Dept Phys, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Drake Univ, Dept Phys & Astron, Des Moines, IA 50311 USA. Univ Calif Los Alamos Natl Lab, Div Appl Theoret & Compua, Los Alamos, NM USA. RP Guo, XZ (reprint author), Calif State Univ Fullerton, Dept Phys, Fullerton, CA 92834 USA. RI Bartschat, Klaus/I-2527-2012 NR 52 TC 22 Z9 22 U1 0 U2 4 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 28 PY 2000 VL 33 IS 10 BP 1895 EP 1919 DI 10.1088/0953-4075/33/10/306 PG 25 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 327HP UT WOS:000087788700007 ER PT J AU Guo, XZ Mathews, DF Mikaelian, G Khakoo, MA Crowe, A Kanik, I Trajmar, S Zeman, V Bartschat, K Fontes, CJ AF Guo, XZ Mathews, DF Mikaelian, G Khakoo, MA Crowe, A Kanik, I Trajmar, S Zeman, V Bartschat, K Fontes, CJ TI Differential cross sections for electron-impact excitation of krypton at low incident energies: II. Excitation of the 4p(5)5p, 4p(5)4d and 4p(5)6s configurations SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID AR; KR; XE AB This paper is the second part of two back-to-back papers concerning electron-impact excitation of Kr. This part concerns excitation of the individual levels that constitute the 4p(5)5p, 4p(5)4d and 4p(5)6s configurations of Kr, at incident electron energies (E-0) of 20.0 and 15.0 eV, for scattering angles (theta) ranging from 10 degrees to 130 degrees. As in part I, excitation cross sections are measured and calculated using the R-matrix (RM) and the unitarized first-order many-body theory (UFOMBT) methods. Comparisons between the present experimental and theoretical results, and also with other experimental results, are presented. C1 Calif State Univ Fullerton, Dept Phys, Fullerton, CA 92834 USA. Univ Newcastle Upon Tyne, Dept Phys, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Drake Univ, Dept Phys & Astron, Des Moines, IA 50311 USA. Univ Calif Los Alamos Natl Lab, Appl Theoret & Computat Phys Div, Los Alamos, NM 87545 USA. RP Guo, XZ (reprint author), Calif State Univ Fullerton, Dept Phys, Fullerton, CA 92834 USA. RI Bartschat, Klaus/I-2527-2012 NR 9 TC 6 Z9 6 U1 0 U2 2 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 28 PY 2000 VL 33 IS 10 BP 1921 EP 1933 DI 10.1088/0953-4075/33/10/307 PG 13 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 327HP UT WOS:000087788700008 ER PT J AU Stone, EM Pan, LW Sandor, BJ Read, WG Waters, JW AF Stone, EM Pan, LW Sandor, BJ Read, WG Waters, JW TI Spatial distributions of upper tropospheric water vapor measurements from the UARS Microwave Limb Sounder SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SURFACE-TEMPERATURE; GREENHOUSE; HUMIDITY; MLS; STRATOSPHERE; ATMOSPHERE AB We characterize measurements of upper tropospheric (similar to 300-150 hPa) water vapor obtained from the Microwave Limb Sounder (MLS) instrument on board the Upper Atmosphere Research Satellite (UARS) in terms of their spatial and temporal variability. We present the climatology of water vapor mixing ratio for October 1991-June 1997, which includes the seasonal means, the root-mean-square deviations, and the seasonal differences. The climatology of the divergent wind field is compiled to examine the relationship of upper tropospheric moisture fields and the tropical circulations. The tropical wet and dry patterns are latitudinally distributed in accordance with the Hadley circulation, and longitudinal distributions correspond well to the Walker circulation. We quantify the frequency of dry tropical observations in seasonal maps. The most prominent dry regions are located in the subtropics. On the 316 hPa surface there is some occurrence of low values of humidity throughout the majority of the tropics, while at 215 hPa it is primarily the subsidence regions that show dry values. Subtropical dry observations are more frequent in the Southern Hemisphere winter than in the Northern Hemisphere winter. The seasonal cycle of MLS water vapor is compared with Stratospheric Aerosol and Gas Experiment II (SAGE II) measurements. Good agreement is found between these two data sets for measurements near the extratropical tropopause. Potential vorticity analysis is used to indicate whether extratropical measurements were influenced primarily by stratospheric or tropospheric air. Frequency distributions display distinct characteristics and seasonal dependence for these two regions. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. RP NASA, Ames Res Ctr, Bay Area Environm Res Inst, Mail Stop 245-4, Moffett Field, CA 94035 USA. EM emstone@sky.arc.nasa.gov RI Pan, Laura/A-9296-2008 OI Pan, Laura/0000-0001-7377-2114 NR 33 TC 18 Z9 18 U1 0 U2 0 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 MAY 27 PY 2000 VL 105 IS D10 BP 12149 EP 12161 DI 10.1029/2000JD900125 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 319WL UT WOS:000087366600004 ER PT J AU Kodera, K Kuroda, Y Pawson, S AF Kodera, K Kuroda, Y Pawson, S TI Stratospheric sudden warmings and slowly propagating zonal-mean zonal wind anomalies SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID QUASI-BIENNIAL OSCILLATION; INTERANNUAL VARIABILITY; NORTHERN-HEMISPHERE; WINTER STRATOSPHERE; TROPOSPHERE; CIRCULATION AB The relationship between stratospheric sudden warming (SSWs) and slowly propagating zonal wind anomalies during the northern hemisphere cold season (November to March) is investigated using two leading empirical orthogonal functions (EOFs) of 15-day mean zonal-mean zonal wind. Poleward and downward propagation of the zonal-mean zonal wind anomalies can be translated as rotation of state vector in a plane spanned by the two EOFs. Major SSWs occur in phase with the slowly propagating zonal wind anomalies, which implies a "conditioning" of the atmosphere by the slowly varying state. Movement of the state vector suggests quasi-periodicity of the order of 4 months, although generally only one cycle is achieved during a major warming winter, This characteristic feature can be compared to the stratospheric vacillation cycle in a mechanistic model. It is also shown that changes in the tropospheric planetary waves associated with the slowly propagating zonal wind anomalies coincide with changes in the Arctic Oscillation. C1 Meteorol Res Inst, Tsukuba, Ibaraki 3050052, Japan. NASA, Goddard Space Flight Ctr, Data Assimiliat Off, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Seabrook, MD USA. RP Meteorol Res Inst, 1-1 Nagamine, Tsukuba, Ibaraki 3050052, Japan. EM kodera@mri-jma.go.jp; kuroda@mri-jma.go.jp; pawson@polska.gsfc.nasa.gov RI Pawson, Steven/I-1865-2014 OI Pawson, Steven/0000-0003-0200-717X NR 24 TC 49 Z9 59 U1 1 U2 6 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 MAY 27 PY 2000 VL 105 IS D10 BP 12351 EP 12359 DI 10.1029/2000JD900095 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 319WL UT WOS:000087366600022 ER PT J AU Chen, SS Hu, ZL White, MA Chen, H Krueger, DA She, CY AF Chen, SS Hu, ZL White, MA Chen, H Krueger, DA She, CY TI Lidar observations of seasonal variation of diurnal mean temperature in the mesopause region over Fort Collins, Colorado (41 degrees N, 105 degrees W) SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID THERMAL STRUCTURE; MIDDLE ATMOSPHERE; MIDLATITUDE MESOPAUSE; TIDES; CIRCULATION; MESOSPHERE; ENERGY; MODEL; HEAT AB Two campaigns from February 1997 to January 1999 have resulted in 18 sets of continuous temperature measurements in the mesopause region over Fort Collins, Colorado (41 degrees N, 105 degrees W), each covering a complete diurnal cycle, reasonably well distributed throughout the year. It is shown that the winter-summer transitions, based on diurnal means, are abrupt and clear, further strengthening the concept of two-level mesopause, and demonstrate the robustness of this picture. Similar to data taken at Urbana, Illinois, our data at Fort Collins also demonstrate the need to observe over a complete diurnal cycle to deduce the uncontaminated mean temperature structure and seasonal variations in the mesopause region. The difference between annual diurnal, nighttime, and daytime means may be ascribed to a temperature wave propagating with a downward phase speed of similar to 0.8 km/h. Our data show that the nighttime annual mean is colder than the diurnal annual mean by no more than 2 K below 88 km and warmer by no more than 3 K above 88 km where the three means are nearly the same. As in the Urbana data, we also observed the altitude of a secondary temperature minimum in the summer to be similar to 96 km, which without strong dynamical cooling in the summer would have been the summer mesopause altitude. C1 Colorado State Univ, Dept Phys, Ft Collins, CO 80523 USA. RP NASA, Langley Res Ctr, 5 N Dryden St,Mail Stop 474, Hampton, VA 23681 USA. EM s.chen@larc.nasa.gov; zhu@lamar.colostate.edu; white@psicorp.com; huailin@agnes.gsfc.nasa.gov; krueger@lamar.colostate.edu; joeshe@lamar.colostate.edu NR 26 TC 27 Z9 28 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 27 PY 2000 VL 105 IS D10 BP 12371 EP 12379 DI 10.1029/2000JD900045 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 319WL UT WOS:000087366600024 ER PT J AU Newman, PA Nash, ER AF Newman, PA Nash, ER TI Quantifying the wave driving of the stratosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DATA ASSIMILATION SYSTEM; NATIONAL-METEOROLOGICAL-CENTER; STATIONARY WAVES; FORECAST SYSTEM; POLAR VORTEX; MODEL; WINDS; NMC; TROPOSPHERE; HEIGHT AB The zonal-mean eddy heat flux is directly proportional to the wave activity that propagates from the troposphere into the stratosphere. This quantity is a simple eddy diagnostic which is calculated from conventional meteorological analyses. Because this "wave driving" of the stratosphere has a strong impact on the stratospheric temperature, it is necessary to compare the impact of the flux with respect to stratospheric radiative changes caused by greenhouse gas changes. Hence we must understand the precision and accuracy of the heat flux derived from our global meteorological analyses. Herein we quantify the stratospheric heat flux using five different meteorological analyses and show that there are 15% differences, on average, between these analyses during the disturbed conditions of the Northern Hemisphere winter. Such large differences result from the planetary differences in the stationary temperature and meridional wind fields. In contrast, planetary transient waves show excellent agreement among these five analyses, and this transient heat flux appears to have a long-term downward trend. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. SM&A Corp E, Largo, MD USA. RP NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA. EM newman@code916.gsfc.nasa.gov; nash@code916.gsfc.nasa.gov RI Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 39 TC 41 Z9 41 U1 0 U2 2 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 MAY 27 PY 2000 VL 105 IS D10 BP 12485 EP 12497 DI 10.1029/1999JD901191 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 319WL UT WOS:000087366600033 ER PT J AU Tabazadeh, A Santee, ML Danilin, MY Pumphrey, HC Newman, PA Hamill, PJ Mergenthaler, JL AF Tabazadeh, A Santee, ML Danilin, MY Pumphrey, HC Newman, PA Hamill, PJ Mergenthaler, JL TI Quantifying denitrification and its effect on ozone recovery SO SCIENCE LA English DT Article ID MICROWAVE LIMB SOUNDER; WINTER POLAR STRATOSPHERES; ARCTIC OZONE; NITRIC-ACID; WATER-VAPOR; ANTARCTIC STRATOSPHERE; ATMOSPHERIC CHEMISTRY; HNO3 OBSERVATIONS; CLAES EXPERIMENT; CLOUD FORMATION AB Upper Atmosphere Research Satellite observations indicate that extensive denitrification without significant dehydration currently occurs only in the Antarctic during mid to late June. The fact that denitrification occurs in a relatively warm month in the Antarctic raises concern about the likelihood of its occurrence and associated effects on ozone recovery in a colder and possibly more humid future Arctic lower stratosphere. Polar stratospheric cloud lifetimes required for Arctic denitrification to occur in the future are presented and contrasted against the current Antarctic cloud lifetimes. Model calculations show that widespread severe denitrification could enhance future Arctic ozone loss by up to 30%. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Atmospher & Environm Res Inc, Cambridge, MA 02139 USA. Univ Edinburgh, Dept Meteorol, Edinburgh EH9 3JZ, Midlothian, Scotland. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20904 USA. San Jose State Univ, Dept Phys, San Jose, CA 95192 USA. Lockheed Martin Adv Technol Ctr, Palo Alto, CA 94304 USA. RP Tabazadeh, A (reprint author), NASA, Ames Res Ctr, MS 245-4, Moffett Field, CA 94035 USA. EM atabazadeh@mail.arc.nasa.gov RI Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 59 TC 107 Z9 106 U1 1 U2 9 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD MAY 26 PY 2000 VL 288 IS 5470 BP 1407 EP 1411 DI 10.1126/science.288.5470.1407 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 318EL UT WOS:000087270900046 ER PT J AU Pavlov, AA Kasting, JF Brown, LL Rages, KA Freedman, R AF Pavlov, AA Kasting, JF Brown, LL Rages, KA Freedman, R TI Greenhouse warming by CH4 in the atmosphere of early Earth SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID CARBON-DIOXIDE CONCENTRATIONS; SURFACE-TEMPERATURE; TITANS ATMOSPHERE; BROADENED METHANE; OXIDATION-STATE; EARLY MARS; EVOLUTION; CO2; MANTLE; PHOTOCHEMISTRY AB Earth appears to have been warm during its early history despite the faintness of the young Sun. Greenhouse warming by gaseous CO2 and H2O by itself is in conflict with constraints on atmospheric CO2 levels derived from paleosols for early Earth. Here we explore whether greenhouse warning by methane could have been important. We find that a CH4 mixing ratio of 10(-4)(100 ppmv) or more in Earth's early atmosphere would provide agreement with the paleosol data from 2.8 Ga. Such a CH4 concentration could have been readily maintained by methanogenic bacteria, which are thought to have been an important component of the biota at that time. Elimination of the methane component of the greenhouse by oxidation of the atmosphere at about 2.3 - 2.4 Ca could have triggered the Earth's first widespread glaciation. C1 Penn State Univ, Dept Geosci, University Pk, PA 16802 USA. NASA, Ames Res Ctr, Space Phys Res Inst, Moffett Field, CA 94035 USA. RP Pavlov, AA (reprint author), Penn State Univ, Dept Geosci, Deike Bldg, University Pk, PA 16802 USA. RI Pavlov, Alexander/F-3779-2012 OI Pavlov, Alexander/0000-0001-8771-1646 NR 57 TC 258 Z9 267 U1 2 U2 76 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 MAY 25 PY 2000 VL 105 IS E5 BP 11981 EP 11990 DI 10.1029/1999JE001134 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 316DZ UT WOS:000087153500002 PM 11543544 ER PT J AU Marinangeli, L Gilmore, MS AF Marinangeli, L Gilmore, MS TI Geologic evolution of the Akna Montes-Atropos Tessera region, Venus SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID ISHTAR-TERRA; GLOBAL DISTRIBUTION; MAGELLAN DATA; TECTONICS; GRAVITY; HISTORY; PLAINS; BELTS; DEFORMATION; VOLCANISM AB The investigated area comprises an arcuate mountain belt, Akna Montes, in Western Ishtar Terra, associated with an outboard plateau, Atropos Tessera, to the west and a volcanic plateau, Lakshmi Planum, to the east. Eight geologic units have been recognized on the basis of their geomorphic and structural characteristics as they appear on Magellan radar images. Our stratigraphic analysis shows that the geological evolution of the study area can be explained by four main steps: (1) formation of the older substrata of Atropos Tessera and Lakshmi, (2) extensive plains emplacement, (3) an orogenic phase including the formation of Akna Montes, and (4) local emplacement of younger plains. The tectonic evolution shows a deformational sequence characterized by contraction, shear, and topographic relaxation. This sequence is interpreted to be a consequence of the variation of crustal stresses and crustal thickening during orogenic events as observed for terrestrial high plateaus associated with a mountain belt (i.e., Himalaya and Tibet, Andes and Altiplano). In order to estimate the amount of crustal shortening associated with the Akna Montes, we considered two end-members for structural style of the mountain belt: a symmetric fold model and a fault-bend fold model. The models are theoretical because terrestrial orogenic belts are often formed by a combination of different compressional structures. However, symmetric and fault-bend faults represent the minimum and maximum crustal shortening, respectively, and thus they do place bounds on the amount of strain recorded bq Akna Monies. The first model yields a shortening value less than 1%, whereas a range of 17-34% is derived for the second model. The large difference between these values underscores the importance of fold geometries for estimating strain and to place constraints on geodynamic models for mountain holt formation. On the basis of our study we think that a combination of mantle downwelling and horizontal convergence may provide a good explanation of the geology and tectonics we observed in the Akna Montes-Atropos Tessera region. C1 Univ dAnnunzio, IRSPS, I-65127 Pescara, Italy. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Marinangeli, L (reprint author), Univ dAnnunzio, IRSPS, Viale Pindaro 42, I-65127 Pescara, Italy. RI Gilmore, Martha/G-5856-2011 NR 81 TC 4 Z9 4 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 MAY 25 PY 2000 VL 105 IS E5 BP 12053 EP 12075 DI 10.1029/1999JE001184 PG 23 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 316DZ UT WOS:000087153500007 ER PT J AU Work, TM Balazs, GH Rameyer, RA Chang, SP Berestecky, J AF Work, TM Balazs, GH Rameyer, RA Chang, SP Berestecky, J TI Assessing humoral and cell-mediated immune response in Hawaiian green turtles, Chelonia mydas SO VETERINARY IMMUNOLOGY AND IMMUNOPATHOLOGY LA English DT Article DE green turtle; Chelonia mydas; enzyme linked immunosorbent assay; Freund's adjuvant; Gerbu; ISA-70; lymphocyte stimulation test ID MARINE TURTLES; BLOOD; FIBROPAPILLOMATOSIS; ANTIBODIES; PHYLOGENY; ISLANDS; SERUM AB Seven immature green turtles, Chelonia mydas, captured from Kaneohe Bay on the island of Oahu were used to evaluate methods for assessing their immune response. Two turtles each were immunized intramuscularly with egg white lysozyme (EWL) in Freund's complete adjuvant, Gerbu, or ISA-70; a seventh turtle was immunized with saline only and served as a control. Humoral immune response was measured with an indirect enzyme linked immunosorbent assay (ELISA). Cell-mediated immune response was measured using in vitro cell proliferation assays (CPA) using whole blood or peripheral blood mononuclear cells (PBM) cultured with concanavalin A (ConA), phytohaemagglutinin (PHA), or soluble egg EWL antigen. All turtles, except for one immunized with Gerbu and the control, produced a detectable humoral immune response by 6 weeks which persisted for at least 14 weeks after a single immunization. All turtles produced an anamnestic humoral immune response after secondary immunization. Antigen specific cell-mediated immune response in PBM was seen in all turtles either after primary or secondary immunization, but it was not as consistent as humoral immune response; antigen specific cell-mediated immune response in whole blood was rarely seen. Mononuclear cells had significantly higher stimulation indices than whole blood regardless of adjuvant, however, results with whole blood had lower variability. Both Gerbu and ISA-70 appeared to potentiate the cell-mediated immune response when PBM or whole blood were cultured with PHA. This is the first time cell proliferation assays have been compared between whole blood and PBM for reptiles. This is also the first demonstration of antigen specific cell-mediated response in reptiles. Cell proliferation assays allowed us to evaluate the cell-mediated immune response of green turtles. However, CPA may be less reliable than ELISA for detecting antigen specific immune response. Either of the three adjuvants appears suitable to safely elicit a detectable immune response in green turtles. (C) 2000 Elsevier Science B.V. All rights reserved. C1 US Geol Survey, Biol Resources Div, Natl Wildlife Hlth Ctr, Honolulu Field Stn, Honolulu, HI 96850 USA. NOAA, Natl Marine Fisheries Serv, SW Fisheries Sci Ctr, Honolulu Lab, Honolulu, HI 96822 USA. Univ Hawaii, Dept Trop Med, Honolulu, HI 96816 USA. Univ Hawaii, Kapiolani Community Coll, Dept Microbiol, Honolulu, HI 96816 USA. RP Work, TM (reprint author), US Geol Survey, Biol Resources Div, Natl Wildlife Hlth Ctr, Honolulu Field Stn, POB 50167, Honolulu, HI 96850 USA. RI Work, Thierry/F-1550-2015 OI Work, Thierry/0000-0002-4426-9090 NR 40 TC 26 Z9 26 U1 1 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0165-2427 J9 VET IMMUNOL IMMUNOP JI Vet. Immunol. Immunopathol. PD MAY 23 PY 2000 VL 74 IS 3-4 BP 179 EP 194 DI 10.1016/S0165-2427(00)00168-9 PG 16 WC Immunology; Veterinary Sciences SC Immunology; Veterinary Sciences GA 315EZ UT WOS:000087100800002 PM 10802287 ER PT J AU Anderson, MS AF Anderson, MS TI Locally enhanced Raman spectroscopy with an atomic force microscope SO APPLIED PHYSICS LETTERS LA English DT Article ID NEAR-FIELD; RESOLUTION; MOLECULES AB An atomic force microscope (AFM) tip has been used to selectively produce surface enhanced Raman scattering (SERS) for localized Raman spectroscopy. Spectra of thin films, undetectable with a Raman microprobe spectrometer alone, were readily acquired in contact with a suitably gold-coated AFM tip. Similarly, an AFM tip was used to remove sample layers at the nanometer scale and subsequently served as a SERS substrate for ultratrace analysis. This work demonstrates the interface of an AFM with a Raman spectrometer that provides increased sensitivity, selectivity, and spatial resolution over a conventional Raman microprobe. An AFM guiding the SERS effect has the potential for targeted single molecule spectroscopy. (C) 2000 American Institute of Physics. [S0003-6951(00)00721-X]. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Anderson, MS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Mis 125-109, Pasadena, CA 91109 USA. NR 21 TC 332 Z9 337 U1 12 U2 92 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 MAY 22 PY 2000 VL 76 IS 21 BP 3130 EP 3132 AR PII [S0003-6951(00)00721-X] DI 10.1063/1.126546 PG 3 WC Physics, Applied SC Physics GA 314QF UT WOS:000087066500052 ER PT J AU Lipa, JA Swanson, DR Nissen, JA Geng, ZK Williamson, PR Stricker, DA Chui, TCP Israelsson, UE Larson, M AF Lipa, JA Swanson, DR Nissen, JA Geng, ZK Williamson, PR Stricker, DA Chui, TCP Israelsson, UE Larson, M TI Specific heat of helium confined to a 57-mu m planar geometry near the lambda point SO PHYSICAL REVIEW LETTERS LA English DT Article ID SURFACE SPECIFIC-HEAT; SUPERFLUID TRANSITION; T-LAMBDA; HE-4; CAPACITY AB We report measurements of the specific heat of liquid helium confined to 57-mu m planar. gaps; extending to within a few nanokelvin of the bulk lambda transition. The data are in fair agreement with Monte Carlo estimates for finite-size effects and with renormalization-group-theory predictions above the transition. Far from the transition, we find surface specific heat exponents, alpha(s) = 0.64 +/- 0.05 below, and 0.65 +/- 0.2 above, which compare well with the prediction of 0.658. Comparison with other recent data on small Length soles shows some areas of agreement. C1 Stanford Univ, Dept Phys, Stanford, CA 94305 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lipa, JA (reprint author), Stanford Univ, Dept Phys, Stanford, CA 94305 USA. NR 18 TC 78 Z9 78 U1 1 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD MAY 22 PY 2000 VL 84 IS 21 BP 4894 EP 4897 DI 10.1103/PhysRevLett.84.4894 PG 4 WC Physics, Multidisciplinary SC Physics GA 315LC UT WOS:000087114400028 ER PT J AU Reynolds, JK Catling, D Blue, RC Maluf, NI Kenny, T AF Reynolds, JK Catling, D Blue, RC Maluf, NI Kenny, T TI Packaging a piezoresistive pressure sensor to measure low absolute pressures over a wide sub-zero temperature range SO SENSORS AND ACTUATORS A-PHYSICAL LA English DT Article; Proceedings Paper CT 10th International Conference on Solid-State Sensors and Actuators CY JUN 07-10, 1999 CL SENDAI, JAPAN SP Inst Elect Engineers DE piezoresistive; calibration; die attach; hysteresis ID MARS AB The packaging, calibration, and testing of a commercial silicon fusion bonded piezoresistive pressure sensor for a Martian deployment are described. Detail is provided on the sensor mounting and electronic instrumentation required for this environment. Flight testing procedures and the residual errors for packaged pressure sensors are presented. Pressure and temperature hysteresis are investigated as sources of this error. The data illustrates the potential high performance of off-the-shelf silicon fusion bonded piezoresistive pressure sensors, which are carefully packaged, instrumented, and individually calibrated. (C) 2000 Elsevier Science S.A. All rights reserved. C1 Stanford Univ, Dept Mech Engn, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Mountain View, CA 94035 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Lucas NovaSensor, Fremont, CA 94539 USA. RP Reynolds, JK (reprint author), Stanford Univ, Dept Mech Engn, Stanford, CA 94305 USA. EM kuthr@stanford.edu OI Catling, David/0000-0001-5646-120X NR 9 TC 21 Z9 22 U1 1 U2 6 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 MAY 22 PY 2000 VL 83 IS 1-3 BP 142 EP 149 DI 10.1016/S0924-4247(00)00294-6 PG 8 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 316AH UT WOS:000087144800023 ER PT J AU Chakraborty, I Tang, WC Bame, DP Tang, TK AF Chakraborty, I Tang, WC Bame, DP Tang, TK TI MEMS micro-valve for space applications SO SENSORS AND ACTUATORS A-PHYSICAL LA English DT Article; Proceedings Paper CT 10th International Conference on Solid-State Sensors and Actuators CY JUN 07-10, 1999 CL SENDAI, JAPAN SP Inst Elect Engineers DE MEMS; valve; piezoelectric; actuator; space AB We report on the development of a micro-electro-mechanical systems (MEMS) valve that is designed to meet the rigorous performance requirements for a variety of space applications, such as micro-propulsion, in situ chemical analysis of other planets, or microbiology. These systems often require very small yet reliable silicon valves with extremely low leak rates and long shelf lives. Also, they must survive the perils of space travel, which include unstoppable radiation, monumental shock and vibration forces, as well as extreme variations in temperature. Currently, no commercial MEMS valve meets these requirements. At JPL, we are developing a piezoelectric MEMS valve that attempts to address the unique problem of space. We begin with proven configurations that may seem familiar. However, we have implemented some major design innovations that should produce a superior valve. The JPL micro-valve is expected to have an extremely low leak rate, limited susceptibility to particulates, vibration or radiation, as well as a wide operational temperature range. Published by Elsevier Science S.A. All rights reserved. C1 JPL, Pasadena, CA 91109 USA. RP Chakraborty, I (reprint author), JPL, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 77 Z9 77 U1 4 U2 22 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 MAY 22 PY 2000 VL 83 IS 1-3 BP 188 EP 193 DI 10.1016/S0924-4247(99)00382-9 PG 6 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 316AH UT WOS:000087144800030 ER PT J AU Atwood, WB Ritz, S Anthony, P Bloom, ED Bosted, PE Bourotte, J Chaput, C Chen, X Chenette, DL Engovatov, D Erickson, R Fieguth, T Fleury, P Gearhart, R Godfrey, G Grove, JE Hernando, JA Hirayama, M Jaggar, S Johnson, RP Johnson, WN Jones, BB Kroger, W Lin, YC Meetre, C Michelson, PF Milne, PA Moiseev, A Nolan, P Norris, JP Oreglia, M Ormes, JF Phlips, BF Pocar, A Sadrozinski, HFW Szalata, Z Thompson, DJ Tompkins, WF AF Atwood, WB Ritz, S Anthony, P Bloom, ED Bosted, PE Bourotte, J Chaput, C Chen, X Chenette, DL Engovatov, D Erickson, R Fieguth, T Fleury, P Gearhart, R Godfrey, G Grove, JE Hernando, JA Hirayama, M Jaggar, S Johnson, RP Johnson, WN Jones, BB Kroger, W Lin, YC Meetre, C Michelson, PF Milne, PA Moiseev, A Nolan, P Norris, JP Oreglia, M Ormes, JF Phlips, BF Pocar, A Sadrozinski, HFW Szalata, Z Thompson, DJ Tompkins, WF TI Beam test of gamma-ray large area space telescope components SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article ID DETECTOR; GLAST AB A beam test of Gamma-ray Large Area Space Telescope (GLAST) components was performed at the Stanford Linear Accelerator Center in October 1997. These beam test components were simple versions of the planned flight hardware. Results on the performance of the tracker, calorimeter, and anti-coincidence charged particle veto are presented. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Stanford Linear Accelerator Ctr, Stanford, CA 94309 USA. Univ Calif Santa Cruz, Santa Cruz, CA 95064 USA. American Univ, Washington, DC 20016 USA. Ecole Polytech, Palaiseau, France. Columbia Univ, New York, NY 10027 USA. Lockheed Martin, Palo Alto, CA USA. USN, Res Lab, Washington, DC 20375 USA. Stanford Univ, Stanford, CA 94305 USA. Clemson Univ, Clemson, SC USA. Univ Space Res Assoc, Washington, DC USA. Univ Chicago, Chicago, IL 60637 USA. RP Ritz, S (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Nolan, Patrick/A-5582-2009; Thompson, David/D-2939-2012; Johnson, Neil/G-3309-2014; Hernando Morata, Jose Angel/L-7642-2014 OI Thompson, David/0000-0001-5217-9135; Hernando Morata, Jose Angel/0000-0002-8683-5142 NR 18 TC 26 Z9 26 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 21 PY 2000 VL 446 IS 3 BP 444 EP 460 DI 10.1016/S0168-9002(99)00980-8 PG 17 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 318YP UT WOS:000087312500004 ER PT J AU Abshire, JB Sun, XL Afzal, RS AF Abshire, JB Sun, XL Afzal, RS TI Mars Orbiter Laser Altimeter: receiver model and performance analysis SO APPLIED OPTICS LA English DT Article ID GLOBAL SURVEYOR AB The design, calibration, and performance of the Mars Orbiter Laser Altimeter (MOLA) receiver are described. The MOLA measurements include the range to the surface, which is determined by the laser-pulse time of flight; the height Variability within the footprint determined by the laser echo pulse width; and the apparent surface reflectivity determined by the ratio of the echo to transmitted pulse energies. OCIS codes: 280.3640, 280.3400, 120.1880, 350.6090, 040.6040, 120.0280. C1 NASA, Goddard Space Flight Ctr, Laser Remote Sensing Branch, Greenbelt, MD 20771 USA. RP Abshire, JB (reprint author), NASA, Goddard Space Flight Ctr, Laser Remote Sensing Branch, Code 924, Greenbelt, MD 20771 USA. EM james.abshire@gsfc.nasa.gov RI Sun, Xiaoli/B-5120-2013; Abshire, James/I-2800-2013 NR 20 TC 41 Z9 49 U1 2 U2 4 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAY 20 PY 2000 VL 39 IS 15 BP 2449 EP 2460 DI 10.1364/AO.39.002449 PG 12 WC Optics SC Optics GA 315NQ UT WOS:000087120200013 PM 18345159 ER PT J AU Kraemer, SB George, IM Turner, TJ Crenshaw, DM AF Kraemer, SB George, IM Turner, TJ Crenshaw, DM TI On the reddening in X-ray-absorbed Seyfert 1 galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : nuclei; galaxies : Seyfert; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; NEUTRAL HYDROGEN; WARM ABSORBERS; LINE REGIONS; NGC-3227; EMISSION; IRAS-17020+4544; ABSORPTION; SPECTRA; MODELS AB There are several Seyfert galaxies for which there is a discrepancy between the small column of neutral hydrogen deduced from X-ray observations and the much greater column derived from the reddening of the optical/UV emission lines and continuum. The standard paradigm has the dust within the highly ionized gas that produces O VII and O wr absorption edges (i.e., a "dusty warm absorber"). We present an alternative model in which the dust exists in a component of gas in which hydrogen has been stripped, but which is at too low an ionization state to possess significant columns of O VII and O VIII (i.e., a "lukewarm absorber"). The lukewarm absorber is at sufficient radial distance to encompass much of the narrow emission line region and thus accounts for the narrow-line reddening, unlike the dusty warm absorber. We test the model by using a combination of photoionization models and absorption edge fits to analyze the combined ROSAT/ASCA dataset for the Seyfert 1.5 galaxy, NGC 3227. We show that the data are well fitted by a combination of the lukewarm absorber and a more highly ionized component similar to that suggested in earlier studies. We predict that the lukewarm absorber will produce strong UV absorption lines of N V, C IV, Si IV, and Mg II. Finally, these results illustrate that singly ionized helium is an important, and often overlooked, source of opacity in the soft X-ray band (100-500 eV). C1 Catholic Univ Amer, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. Univ Maryland Baltimore Cty, Baltimore, MD 21228 USA. RP Kraemer, SB (reprint author), Catholic Univ Amer, Washington, DC 20064 USA. NR 37 TC 22 Z9 22 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2000 VL 535 IS 1 BP 53 EP 57 DI 10.1086/308849 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 325DW UT WOS:000087661900006 ER PT J AU Kriss, GA Peterson, BM Crenshaw, DM Zheng, W AF Kriss, GA Peterson, BM Crenshaw, DM Zheng, W TI A high signal-to-noise ultraviolet spectrum of NGC 7469: New support for reprocessing of continuum radiation SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (NGC 7469); galaxies : Seyfert; ultraviolet : galaxies; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; BROAD-LINE REGION; C-IV ABSORPTION; X-RAY; EMISSION-LINE; SEYFERT-GALAXIES; SPACE-TELESCOPE; NGC-5548; NGC-7469; QUASARS AB From 1996 June 10 to 1996 July 29, the International AGN Watch monitored the Seyfert I galaxy NGC 7469 using the International Ultraviolet Explorer, the Rossi X-Ray Timing Explorer, and a network of ground-based observatories. On 1996 June 18, in the midst of this intensive monitoring period, we obtained a high signal-to-noise snapshot of the UV spectrum from 1150 to 3300 Angstrom using the Faint Object Spectrograph (FOS) on the Hubble Space Telescope. This spectrum allows us to disentangle the UV continuum more accurately from the broad wings of the emission lines, to identify clean continuum windows free of contaminating emission and absorption, and to deblend line complexes such as Ly alpha + N V, C IV + He II + O III], Si III] + C III], and Mg II + Fe II. Using the FOS spectrum as a template, are have fitted and extracted line and continuum fluxes from the IUE monitoring data. The cleaner continuum extractions confirm the discovery of time delays between the different UV continuum bands by Wanders et al. Our new measurements show delays increasing with wavelength for continuum bands centered at 1485, 1740, and 1825 Angstrom relative to 1315 Angstrom with delays of 0.09, 0.28, and 0.36 days, respectively. Like many other Seyfert 1 galaxies, the UV spectrum of NGC 7469 shows intrinsic, blueshifted absorption in Ly alpha, N V, and C IV. Soft X-ray absorption is also visible in archival ASCA X-ray spectra. The strength of the UV absorption, however, is not compatible with a single-zone model in which the same material absorbs both the UV and X-ray light. Similar to other Seyfert galaxies, such as NGC 3516, the UV-absorbing gas in NGC 7469 has a lower ionization parameter and column density than the X-ray-absorbing material. While the UV and X-ray absorption does not arise in the same material, the frequent occurrence of both associated UV absorption and X-ray warm absorbers in the same galaxies suggests that the gas supply for each has a common origin. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. Johns Hopkins Univ, Dept Phys & Astron, Ctr Astrophys Sci, Baltimore, MD 21218 USA. Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. Catholic Univ Amer, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Kriss, GA (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. NR 45 TC 43 Z9 43 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2000 VL 535 IS 1 BP 58 EP 72 DI 10.1086/308840 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 325DW UT WOS:000087661900007 ER PT J AU Ingalls, JG Bania, TM Lane, AP Rumitz, M Stark, AA AF Ingalls, JG Bania, TM Lane, AP Rumitz, M Stark, AA TI Physical state of molecular gas in high galactic latitude translucent clouds SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : clouds; ISM : molecules; submillimeter ID SMALL-SCALE STRUCTURE; IRAM KEY-PROJECT; T-TAURI STARS; INTERSTELLAR-MEDIUM; VELOCITY STRUCTURE; FORMING REGIONS; CIRRUS CLOUDS; ATOMIC CARBON; CO; EMISSION AB The rotational transitions of carbon monoxide (CO) are the primary means of investigating the density and velocity structure of the molecular interstellar medium. Here we study the lowest four rotational transitions of CO toward high-latitude translucent molecular clouds (HLCs). We report new observations of the J = (4-3), (2-1), and (1-0) transitions of CO toward eight high-latitude clouds. The new observations are combined with data from the literature to show that the emission from all observed CO transitions is linearly correlated. This implies that the excitation conditions that lead to emission in these transitions are uniform throughout the clouds. Observed (CO)-C-13/(CO)-C-12 (1_0) integrated intensity ratios are generally much greater than the expected abundance ratio of the two species, indicating that the regions that emit (CO)-C-12 (1-0) radiation are optically thick. We develop a statistical method to compare the observed line ratios with models of CO excitation and radiative transfer. This enables us to determine the most likely portion of the physical parameter space that is compatible with the observations. The model enables us to rule out CO gas temperatures greater than similar to 30 K, since the most likely high-temperature configurations are 1 pc-sized structures aligned along the line of sight. The most probable solution is a high-density and low-temperature (HDLT) solution, with volume density, n=10(4.5+/-0.5) cm(-3), kinetic temperature, T-k approximate to 8 K, and CO column density per velocity interval N-CO/Delta V. = 10(16.6+/-0.3) cm(-2)/(km s(-1)). The CO cell size is L similar to 0.01 pc (similar to 2000 AU). These cells are thus tiny fragments within the similar to 100 times larger GO-emitting extent of a typical high-latitude cloud. We discuss the physical implications of HDLT cells, and we suggest ways to test for their existence. C1 Boston Univ, Dept Astron, Boston, MA 02215 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Ingalls, JG (reprint author), CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, 770 W Wilson Ave, Pasadena, CA 91125 USA. RI Bania, Thomas/H-2318-2014 NR 55 TC 15 Z9 15 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2000 VL 535 IS 1 BP 211 EP 226 DI 10.1086/308831 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 325DW UT WOS:000087661900018 ER PT J AU Hallenbeck, SL Nuth, JA Nelson, RN AF Hallenbeck, SL Nuth, JA Nelson, RN TI Evolving optical properties of annealing silicate grains: From amorphous condensate to crystalline mineral SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; dust, extinction; ISM : molecules; methods : laboratory; molecular processes ID EMISSION FEATURES; CIRCUMSTELLAR DUST; VARIABLES; SPECTRA; STARS AB Laboratory studies of the evolution of a magnesium silicate smoke from an amorphous condensate to a crystalline mineral by annealing in vacuum provide a foundation for the development of a silicate evolution index (SEI). The SEI can be used to predict the emergent IR spectrum of silicate dust in a circumstellar shell based on the time-temperature history of the silicate grains in the outflow. Optical constants for the magnesium silicate smoke samples compatible with those of Draine & Lee are derived over the range 0.001-1000 mu m. C1 NASA, Goddard Space Flight Ctr, Astrochem Branch, Greenbelt, MD 20771 USA. Georgia So Univ, Dept Chem, Statesboro, GA 30460 USA. RP Hallenbeck, SL (reprint author), NASA, Goddard Space Flight Ctr, Astrochem Branch, Code 691, Greenbelt, MD 20771 USA. RI Nuth, Joseph/E-7085-2012 NR 15 TC 75 Z9 75 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2000 VL 535 IS 1 BP 247 EP 255 DI 10.1086/308810 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 325DW UT WOS:000087661900021 ER PT J AU Markwick, AJ Millar, TJ Charnley, SB AF Markwick, AJ Millar, TJ Charnley, SB TI On the abundance gradients of organic molecules along the TMC-1 ridge SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : individual (Taurus Molecular Cloud); ISM : molecules; molecular processes ID GRAIN MANTLES; DENSE CLOUDS; DARK CLOUD; EXPLOSIVE DESORPTION; AMBIPOLAR DIFFUSION; CHEMISTRY; CORES; NH3; METHANOL; WAVES AB Gradients in molecular abundances along the TMC-1 ridge have been observed by several authors, most recently in a comprehensive study by Pratap et al. These can be explained by there being a difference in density, C/O ratio, or chemical evolutionary state along the ridge. The presence at the carbon-rich "cyanopolyyne peak" (CP) of specific oxygen-bearing molecules, believed to be products of grain surface reactions, leads us to investigate the possibility that the gradients are produced following the removal of icy grain mantles. We identify the mantle removal mechanism as the explosive desorption of photolyzed ices, induced by MHD waves as they propagate within the cloud. By identifying the protostellar object IRAS 03381+2540 as the source of these waves, we have constructed a dynamical-chemical model for the evolution of the TMC-1. ridge. The results of detailed chemical kinetic calculations are presented. We find that injection into the gas phase of the carbon-bearing species C2H2, C2H4 and CH4 can transiently enhance the production of many organic molecules, particularly the cyanopolyynes and polyacetylenes, and hence that the observed gradients can indeed be produced in this model. We suggest that other mantle-driven reaction pathways, involving formation of methylated chains (e.g., CH3C3N) by gas phase methyl cation transfer, as well as formation of carbenes and suboxides by fragmentation of surface-formed cumulenone compounds, might explain the presence of many other organic molecules in TMC-1. In our view the current chemical state of TMC-1 reflects a transient phase that accompanies the earliest epochs of low-mass formation and that regions rich in organic molecules should be observable around known "Class 0" protostellar sources and be offset from them by about an ion-neutral damping length. Molecular clumps in dense cores should also show structure on this scale-length. C1 UMIST, Dept Phys, Manchester M60 1QD, Lancs, England. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Markwick, AJ (reprint author), UMIST, Dept Phys, POB 88, Manchester M60 1QD, Lancs, England. RI Charnley, Steven/C-9538-2012; OI Millar, Tom/0000-0001-5178-3656 NR 56 TC 79 Z9 79 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2000 VL 535 IS 1 BP 256 EP 265 DI 10.1086/308814 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 325DW UT WOS:000087661900022 ER PT J AU Doyle, LR Deeg, HJ Kozhevnikov, VP Oetiker, B Martin, EL Blue, JE Rottler, L Stone, RPS Ninkov, Z Jenkins, JM Schneider, J Dunham, EW Doyle, MF Paleologou, E AF Doyle, LR Deeg, HJ Kozhevnikov, VP Oetiker, B Martin, EL Blue, JE Rottler, L Stone, RPS Ninkov, Z Jenkins, JM Schneider, J Dunham, EW Doyle, MF Paleologou, E TI Observational limits on terrestrial-sized inner planets around the CM Draconis system using the photometric transit method with a matched-filter algorithm SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : eclipsing; methods : statistical; planetary systems; stars : individual (CM Draconis); techniques : photometric ID EXTRASOLAR PLANETS; BINARY-SYSTEMS; DETECTABILITY; STABILITY; DWARF; DUST; STAR AB A light curve of the eclipsing binary CM Draconis has been analyzed for the presence of transits of planets of size greater than or equal to 2.5 Earth radii (R-E), with periods of 60 days or less, and in coplanar orbits around the binary system. About 400 million model light curves, representing transits from planets with periods ranging from 7 to 60 days, have been matched/correlated against these data. This process we call the "transit detection algorithm" or TDA. The resulting "transit statistics" for each planet candidate allow the quantification of detection probabilities, and of false-alarm rates. Our current light curve of CM Dra has a coverage of 1014 hr with 26,043 individual points, at a photometric precision between 0.2% and 0.7%. Planets significantly larger than 3R(E) would constitute a "supranoise" detection, and for periods of 60 days or less, they would have been detected with a probability greater than 90%. "Subnoise" detections of smaller planets are more constrained. For example, 2.5R(E) planets with 10 day periods or less would have been detected with an 80% probability. The necessity for predicted observations is illustrated with the nine top planet candidates that emerged from our TDA analysis. They are the planet candidates with the highest transit statistics from the 1994-1998 observing seasons, and for them transits for the 1999 observing season were predicted. Of the seven candidates that were then observationally tested in 1999, all were ruled out except one, which needs further observational confirmation. We conclude that the photometric transit method is a viable way to search for relatively small, inner extrasolar planets with moderate-sized telescopes using CCD photometry with a matching-filter analysis. C1 Search Extraterr Intelligence Inst, Mt View, CA 94043 USA. Inst Astrofis Canarias, E-38200 La Laguna, Spain. Ctr Astrobiol, E-28807 Madrid, Spain. Ural State Univ, Astron Observ, Ekaterinburg 620083, Russia. Univ New Mexico, Dept Phys & Astron, Albuquerque, NM 87131 USA. SRI Int, Menlo Park, CA 94025 USA. Univ Calif Santa Cruz, Lick Observ, Santa Cruz, CA 95040 USA. Rochester Inst Technol, Ctr Imaging Sci, Rochester, NY 14623 USA. NASA, Ames Res Ctr, Search Extraterr Intelligence Inst, Moffett Field, CA 94035 USA. CNRS, Observ Paris, F-92195 Meudon, France. Lowell Observ, Flagstaff, AZ USA. FIDM, Culver City, CA 90230 USA. Univ Crete, Skinakas Observ, Iraklion 71110, Greece. RP Doyle, LR (reprint author), Search Extraterr Intelligence Inst, 2035 Landings Dr, Mt View, CA 94043 USA. NR 32 TC 60 Z9 60 U1 1 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2000 VL 535 IS 1 BP 338 EP 349 DI 10.1086/308830 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 325DW UT WOS:000087661900030 ER PT J AU Andretta, V Jordan, SD Brosius, JW Davila, JM Thomas, RJ Behring, WE Thompson, WT AF Andretta, V Jordan, SD Brosius, JW Davila, JM Thomas, RJ Behring, WE Thompson, WT TI The role of velocity redistribution in enhancing the intensity of the He II 304 angstrom line in the quiet-Sun spectrum SO ASTROPHYSICAL JOURNAL LA English DT Article DE line : formation; line : profiles; Sun : atmospheric motions; Sun : chromosphere; Sun : corona; Sun : transition region ID CHROMOSPHERIC FINE-STRUCTURE; SOLAR TRANSITION REGION; ENERGY-BALANCE; HELIUM; EMISSION; SPECTROGRAPH; EXCITATION; FILTRATION; ABUNDANCE; OPACITY AB We present observational evidence of the effect of small-scale ("microturburent") velocities in enhancing the intensity of the He II lambda 304 line with respect to other transition region emission lines, a process we call "velocity redistribution,", We first show results from the 1991 and 1993 flights of SERTS (Solar EW Rocket Telescope and Spectrograph). The spectral resolution of the SERTS instrument was sufficient to infer that, at the spatial resolution of 5", the line profile is nearly Gaussian both in the quiet Sun and in active regions. We were then able to determine, for the quiet Sun, a lower limit for the amplitude of nonthermal motions in the region of formation of the 304 Angstrom line of the order of 10 km s(-1). We estimated that, in the presence of the steep temperature gradients of the solar transition region (TR), velocities of this magnitude can significantly enhance the intensity of that line, thus at least helping to bridge the gap between calculated and observed values. We also estimated the functional dependence of such an enhancement on the relevant parameters (nonthermal velocities, temperature gradient, and pressure). We then present results from a coordinated campaign, using SOHO/CDS and H alpha spectroheliograms from Coimbra Observatory, aimed at determining the relationship between legions of enhanced helium emission and chromospheric velocity fields and transition region emission in the quiescent atmosphere. Using these data, we examined the behavior of the He II lambda 304 line in the quiet-Sun supergranular network and compared it with other TR lines, in particular with O III lambda 600. We also examined the association of 304 A emission with the so-called coarse dark mottle, chromospheric structures seen in H alpha red-wing images and associated with spicules. We found that all these observations are consistent with the velocity redistribution picture. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Coimbra, Astron Observ, P-3040 Coimbra, Portugal. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. RP Andretta, V (reprint author), Osservatorio Astron Capodimonte, Via Moiariello 16, I-80131 Naples, Italy. RI Thompson, William/D-7376-2012 NR 43 TC 27 Z9 27 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2000 VL 535 IS 1 BP 438 EP 453 DI 10.1086/308833 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 325DW UT WOS:000087661900040 ER PT J AU Woods, PM Kouveliotou, C Finger, MH Gogus, E Scott, DM Dieters, S Thompson, C Duncan, RC Hurley, K Strohmayer, T Swank, J Murakami, T AF Woods, PM Kouveliotou, C Finger, MH Gogus, E Scott, DM Dieters, S Thompson, C Duncan, RC Hurley, K Strohmayer, T Swank, J Murakami, T TI Timing noise in SGR 1806-20 SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : general; stars : individual (SGR 1806-20); X-rays : bursts ID X-RAY PULSARS; MAGNETIZED NEUTRON-STARS; SOFT GAMMA-REPEATERS; SPIN-DOWN; MAGNETARS; PERIOD AB We have phase-connected a sequence of Rossi X-Ray Timing Explorer Proportional Counter Array observations of SGR 1806-20 covering 178 days. We find that a simple secular spin-down model does not adequately fit the data. The period derivative varies gradually during the observations between 8.1 x 10(-11) and 11.7 x 10(-11) s s(-1) (at its highest, similar to 40% larger than the long-term trend), while the average burst rate as seen with the Burst and Transient Source Experiment drops throughout the time interval. The phase residuals give no compelling evidence for periodicity, but more closely resemble timing noise as seen in radio pulsars. The magnitude of the timing noise, however, is large relative to the noise level typically found in radio pulsars (Delta(8) = 4.8; frequency derivative average power approximate to 7 x 10(-20) cycles(2) s(-3)). Combining these results with the noise levels measured for some anomalous X-ray pulsars, we find that all magnetar candidates have Delta(8) values larger than those expected from a simple extrapolation of the correlation found in radio pulsars. We find that the timing noise in SGR 1806-20 is greater than or equal to the levels found in some accreting systems (e.g,, Vela X-l, 4U 1538-52, and 4U 1626-67), but the spin-down of SGR 1806-20 has thus far maintained coherence over 6 yr. Alternatively, an orbital model with a period P-orb = 733 days provides a statistically acceptable fit to the data. If the phase residuals are created by Doppler shifts from a gravitationally bound companion, then the allowed parameter space for the mass function (small) and orbital separation (large) rule out the possibility of accretion from the companion sufficient to power the persistent emission from the SGR. 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. Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA. Univ Texas, Dept Astron, Austin, TX 78712 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 229, Japan. RP Woods, PM (reprint author), Univ Space Res Assoc, Columbia, MD 21044 USA. RI Swank, Jean/F-2693-2012 NR 31 TC 42 Z9 42 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2000 VL 535 IS 1 BP L55 EP L58 DI 10.1086/312698 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 325EA UT WOS:000087662300014 ER PT J AU Zhang, B Harding, AK AF Zhang, B Harding, AK TI High magnetic field pulsars and magnetars: A unified picture SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : general; pulsars : individual (1E 2259+586; PSR J1814-1744); stars : magnetic fields; stars : neutron ID SOFT GAMMA-REPEATERS; BOUND PAIR CREATION; X-RAY; NEUTRON-STARS; POLAR GAPS; EMISSION; BURSTS AB We propose a unified picture of high magnetic field radio pulsars and magnetars by arguing that they are all rotating high-field neutron stars but that their magnetic axes have different orientations with respect to their rotation axes. In strong magnetic fields where photon splitting suppresses pair creation near the surface, the high-field pulsars can have active inner accelerators while the anomalous X-ray pulsars cannot. This can account for the very different observed emission characteristics of the anomalous X-ray pulsar 1E 2259+586 and the high-field radio pulsar PSR J1814-1744. A predicted consequence of this picture is that radio pulsars having surface magnetic fields greater than about 2 x 10(14) G should not exist. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Zhang, B (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RI Harding, Alice/D-3160-2012 NR 36 TC 48 Z9 49 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2000 VL 535 IS 1 BP L51 EP L54 DI 10.1086/312694 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 325EA UT WOS:000087662300013 ER PT J AU Liou, MS AF Liou, MS TI Mass flux schemes and connection to shock instability SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE upwind methods; mass flux; shock (carbuncle) instability; AUSM schemes ID GODUNOV-TYPE METHODS; SPLITTING SCHEME; DIFFERENCE-SCHEMES; GAS-DYNAMICS; DISSIPATION AB We analyze numerical mass fluxes with an emphasis on their capability for accurately capturing shock and contact discontinuities. The study of mass flux is useful because it is the term common to all conservation equations and the numerical diffusivity introduced in it bears a direct consequence to the prediction of contact (stationary and moving) discontinuities, which are considered to be the limiting case of the boundary layer. We examine several prominent numerical flux schemes and analyze the structure of numerical diffusivity. This leads to a derailed investigation into the cause of certain catastrophic breakdowns by some numerical flux schemes. In particular, we identify the dissipative terms that are responsible for shock instabilities, such as the odd-even decoupling and the so-called "carbuncle phenomenon." As a result, we propose a conjecture staring the connection of the pressure difference term to these multidimensional shock instabilities and hence a cure to those difficulties. The validity of this conjecture has been confirmed by examining a wide class of upwind schemes. The conjecture is useful to the flux function development, for it indicates whether the Aux scheme under consideration will be afflicted with these kinds of failings. Thus, a class of shock-stable schemes can be identified. Interestingly, a shock-stable scheme's self-correcting capability is demonstrated with respect to carbuncle-contaminated profiles for flows at both low supersonic and high Mach numbers. C1 NASA, Glenn Res Ctr, Turbomachinery & Prop Syst Div, Cleveland, OH 44135 USA. RP Liou, MS (reprint author), NASA, Glenn Res Ctr, Turbomachinery & Prop Syst Div, Lewis Field, Cleveland, OH 44135 USA. NR 22 TC 65 Z9 76 U1 0 U2 7 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD MAY 20 PY 2000 VL 160 IS 2 BP 623 EP 648 DI 10.1006/jcph.2000.6478 PG 26 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 315BR UT WOS:000087093200012 ER PT J AU Zingg, DW De Rango, S Nemec, M Pulliam, TH AF Zingg, DW De Rango, S Nemec, M Pulliam, TH TI Comparison of several spatial discretizations for the Navier-Stokes equations SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE aerodynamics; Navier-Stokes equations; finite-difference methods; higher-order methods ID DISSIPATION SCHEMES; DIFFERENCE; COMPUTATIONS; ALGORITHM; FORM AB Grid convergence studies for subsonic and transonic flows over airfoils are presented in order to compare the accuracy of several spatial discretizations for the compressible Navier-Stokes equations. The discretizations include the following schemes for the inviscid fluxes: (1) second-order-accurate centered differences with third-order matrix numerical dissipation, (2) the second-order convective upstream split pressure scheme (CUSP), (3) third-order upwind-biased differencing with Roe's flux-difference splitting, and (4) fourth-order centered differences with third-order matrix numerical dissipation. The first three are combined with second-order differencing for the grid metrics and viscous terms. The fourth discretization uses fourth-order differencing for the grid metrics and viscous terms, as well as higher-order approximations near boundaries and for the numerical integration used to calculate forces and moments. The results indicate that the discretization using higher-order approximations for all terms is substantially more accurate than the others, producing less than two percent numerical error in lift and drag components on grids with less than 13,000 nodes for subsonic cases and less than 18,000 nodes for transonic cases. Since the cost per grid node of all of the discretizations studied is comparable, the higher-order discretization produces solutions of a given accuracy much more efficiently than the others. (C) 2000 Academic Press. C1 Univ Toronto, Inst Aerosp Studies, Toronto, ON, Canada. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Zingg, DW (reprint author), Univ Toronto, Inst Aerosp Studies, 4925 Dufferin St, Toronto, ON, Canada. NR 28 TC 34 Z9 37 U1 1 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD MAY 20 PY 2000 VL 160 IS 2 BP 683 EP 704 DI 10.1006/jcph.2000.6482 PG 22 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 315BR UT WOS:000087093200015 ER PT J AU Good, B Bozzolo, GH Abel, PB AF Good, B Bozzolo, GH Abel, PB TI Surface segregation in ternary alloys SO SURFACE SCIENCE LA English DT Article; Proceedings Paper CT 18th European Conference on Surface Science (ECOSS 18) CY SEP 21-24, 1999 CL VIENNA UNIV TECHNOL, VIENNA, AUSTRIA SP Inst Allgemeine Phys HO VIENNA UNIV TECHNOL DE computer simulations; copper; gold; nickel ID MONTE-CARLO; NI ALLOYS; AU3CU(001); SCATTERING; PROFILES; METAL AB Surface segregation profiles of binary (Cu-Ni, Au-Ni, Cu-Au) and ternary (Cu-Au-Ni) alloys are determined via Monte Carlo-Metropolis computer simulations using the BFS method for alloys for the calculation of the energetics. The behavior of Cu or Au in Ni is contrasted with their behavior when both are present. The interaction between Cu and Au and its effect on the segregation profiles for Cu-Au-Ni alloys is discussed. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Cleveland, OH 44142 USA. RP Bozzolo, GH (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 22 TC 14 Z9 14 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0039-6028 J9 SURF SCI JI Surf. Sci. PD MAY 20 PY 2000 VL 454 BP 602 EP 607 DI 10.1016/S0039-6028(00)00283-1 PG 6 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA 326ZB UT WOS:000087766200116 ER PT J AU Mosca, HO Garces, JE Bozzolo, GH AF Mosca, HO Garces, JE Bozzolo, GH TI Surface ternary alloys of(Cu,Au)/Ni(110) SO SURFACE SCIENCE LA English DT Article; Proceedings Paper CT 18th European Conference on Surface Science (ECOSS 18) CY SEP 21-24, 1999 CL VIENNA UNIV TECHNOL, VIENNA, AUSTRIA SP Inst Allgemeine Phys HO VIENNA UNIV TECHNOL DE alloys; computer simulations; semi-empirical models and model calculations; surface defects ID NI(110); GROWTH; AU AB The initial stages and trends in the process of surface alloy formation for copper and gold deposited on an Ni(110) substrate have been investigated by means of a simple theoretical modeling approach. The Bozzolo-Ferrante-Smith (BFS) method for alloys is used to compute the energetics of low-coverage surface alloys. Basic features observed in BFS modeling of (Cu,Au)/Ni(110) surface alloy formation include Cu-Au chains in the surface as well as structure characteristic of the Au/Ni(110) and Cu/Ni(110) cases. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Ohio Aerosp Inst, Cleveland, OH 44142 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Comis Nacl Energia Atom, Ctr Atom Bariloche, RA-8400 Bariloche, Rio Negro, Argentina. Univ Buenos Aires, Fac Ciencias Exactas & Nat, Dept Fis, RA-1428 Buenos Aires, DF, Argentina. Comis Nacl Energia Atom, RA-1429 Buenos Aires, DF, Argentina. RP Bozzolo, GH (reprint author), Ohio Aerosp Inst, 22800 Cedar Point Rd, Cleveland, OH 44142 USA. NR 6 TC 6 Z9 6 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0039-6028 J9 SURF SCI JI Surf. Sci. PD MAY 20 PY 2000 VL 454 BP 707 EP 711 DI 10.1016/S0039-6028(00)00112-6 PG 5 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA 326ZB UT WOS:000087766200134 ER PT J AU Bauschlicher, CW AF Bauschlicher, CW TI Hydrogen and fluorine binding to the sidewalls of a (10,0) carbon nanotube SO CHEMICAL PHYSICS LETTERS LA English DT Article ID GEOMETRY OPTIMIZATION; ELECTRON CORRELATION; MOLECULAR MECHANICS; ADSORPTION; ENERGY AB The ONIOM method is used to study the addition of H and F atoms to the side of a (10,0) carbon nanotube. The entire model uses 200 carbon atoms, while the accurate section includes 24 carbon atoms. The B3LYP functional is used for the accurate calculation of the reaction site, while the Universal Force Field (UFF) is used to describe the neighboring atoms. The F atoms appear to favor bonding next to existing F atoms. Unlike the addition of fluorine, the addition of two or four H atoms to a (10,0) tube is computed to be endothermic. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, Mail Stop 230-3,MS230-3, Moffett Field, CA 94035 USA. NR 18 TC 116 Z9 119 U1 0 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD MAY 19 PY 2000 VL 322 IS 3-4 BP 237 EP 241 DI 10.1016/S0009-2614(00)00426-7 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 318EX UT WOS:000087271900014 ER PT J AU McEwen, AS Belton, MJS Breneman, HH Fagents, SA Geissler, P Greeley, R Head, JW Hoppa, G Jaeger, WL Johnson, TV Keszthelyi, L Klaasen, KP Lopes-Gautier, R Magee, KP Milazzo, MP Moore, JM Pappalardo, RT Phillips, CB Radebaugh, J Schubert, G Schuster, P Simonelli, DP Sullivan, R Thomas, PC Turtle, EP Williams, DA AF McEwen, AS Belton, MJS Breneman, HH Fagents, SA Geissler, P Greeley, R Head, JW Hoppa, G Jaeger, WL Johnson, TV Keszthelyi, L Klaasen, KP Lopes-Gautier, R Magee, KP Milazzo, MP Moore, JM Pappalardo, RT Phillips, CB Radebaugh, J Schubert, G Schuster, P Simonelli, DP Sullivan, R Thomas, PC Turtle, EP Williams, DA TI Galileo at Io: Results from high-resolution imaging SO SCIENCE LA English DT Article ID SILICATE VOLCANISM; ACTIVE VOLCANISM; KILAUEA VOLCANO; MOUNTAINS; HAWAII; EARTH; FLOW; MOON AB During late 1999/early 2000, the solid state imaging experiment on the Galileo spacecraft returned more than 100 high-resolution (5 to 500 meters per pixel) images of volcanically active lo. We observed an active Lava lake, an active curtain of lava, active Lava flows, calderas, mountains, plateaus, and plains. Several of the sulfur dioxide-rich plumes are erupting from distal flows, rather than from the source of silicate Lava (caldera or fissure, often with red pyroclastic deposits). Most of the active flows in equatorial regions are being emplaced slowly beneath insulated crust, but rapidly emplaced channelized flows are also found at all latitudes. There is no evidence for high-viscosity Lava, but some bright flows may consist of sulfur rather than mafic silicates. The mountains, plateaus, and calderas are strongly influenced by tectonics and gravitational collapse. Sapping channels and scarps suggest that many portions of the upper similar to 1 kilometer are rich in volatiles. C1 Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Natl Opt Astron Observ, Tucson, AZ 85719 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. Brown Univ, Dept Geol Sci, Providence, RI 02913 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA. DLR, Inst Weltraumsensorik & Planetenerkundung, D-12489 Berlin, Germany. Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. RP McEwen, AS (reprint author), Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. RI Turtle, Elizabeth/K-8673-2012; Fagents, Sarah/B-3983-2014; Lopes, Rosaly/D-1608-2016 OI Turtle, Elizabeth/0000-0003-1423-5751; Lopes, Rosaly/0000-0002-7928-3167 NR 37 TC 98 Z9 99 U1 1 U2 6 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD MAY 19 PY 2000 VL 288 IS 5469 BP 1193 EP 1198 DI 10.1126/science.288.5469.1193 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 315KH UT WOS:000087112600038 PM 10817986 ER PT J AU Spencer, JR Rathbun, JA Travis, LD Tamppari, LK Barnard, L Martin, TZ McEwen, AS AF Spencer, JR Rathbun, JA Travis, LD Tamppari, LK Barnard, L Martin, TZ McEwen, AS TI Io's thermal emission from the Galileo photopolarimeter-radiometer SO SCIENCE LA English DT Article ID ACTIVE VOLCANISM; HOT-SPOTS; TEMPERATURE; EUROPA; PHOTOMETRY; SSI AB Galileo's photopolarimeter-radiometer instrument mapped to's thermal emission during the 124, 125, and 127 flybys with a spatial resolution of 2.2 to 300 kilometers. Mapping of Loki in 124 shows uniform temperatures for most of Loki Patera and high temperatures in the southwest corner, probably resulting from an eruption that began 1 month before the observation. Most of Loki Patera was resurfaced before 127. Pele's caldera floor has a low temperature of 160 kelvin, whereas flows at Pillan and Zamama have temperatures of up to 200 kelvin, Global maps of nighttime temperatures provide a means for estimating global heat flow. C1 Lowell Observ, Flagstaff, AZ 86001 USA. NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. RP Spencer, JR (reprint author), Lowell Observ, 1400 W Mars Hill Rd, Flagstaff, AZ 86001 USA. NR 22 TC 77 Z9 77 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 MAY 19 PY 2000 VL 288 IS 5469 BP 1198 EP 1201 DI 10.1126/science.288.5469.1198 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 315KH UT WOS:000087112600039 PM 10817987 ER PT J AU Lopes-Gautier, R Doute, S Smythe, WD Kamp, LW Carlson, RW Davies, AG Leader, FE McEwen, AS Geissler, PE Kieffer, SW Keszthelyi, L Barbinis, E Mehlman, R Segura, M Shirley, J Soderblom, LA AF Lopes-Gautier, R Doute, S Smythe, WD Kamp, LW Carlson, RW Davies, AG Leader, FE McEwen, AS Geissler, PE Kieffer, SW Keszthelyi, L Barbinis, E Mehlman, R Segura, M Shirley, J Soderblom, LA TI A close-up look at Io from Galileo's near-infrared mapping spectrometer SO SCIENCE LA English DT Article ID ACTIVE VOLCANISM; SILICATE AB Infrared spectral images of Jupiter's volcanic moon lo, acquired during the October and November 1999 and February 2000 flybys of the Galileo spacecraft, were used to study the thermal structure and sulfur dioxide distribution of active volcanoes. Loki Patera, the solar system's most powerful known volcano, exhibits Large expanses of dark, cooling lava on its caldera floor. Prometheus, the site of long-lived plume activity, has two major areas of thermal emission, which support ideas of plume migration. Sulfur dioxide deposits were mapped at local scales and show a more complex relationship to surface colors than previously thought, indicating the presence of other sulfur compounds. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, IGPP, Los Angeles, CA 90095 USA. SW Kieffer Sci Consulting Inc, Bolton, ON L7E 5T4, Canada. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. US Geol Survey, Flagstaff, AZ 86001 USA. RP Lopes-Gautier, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM rlopes@lively.jpl.nasa.gov RI Lopes, Rosaly/D-1608-2016 OI Lopes, Rosaly/0000-0002-7928-3167 NR 17 TC 66 Z9 66 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 19 PY 2000 VL 288 IS 5469 BP 1201 EP 1204 DI 10.1126/science.288.5469.1201 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 315KH UT WOS:000087112600040 PM 10817988 ER PT J AU Kieffer, SW Lopes-Gautier, R McEwen, A Smythe, W Keszthelyi, L Carlson, R AF Kieffer, SW Lopes-Gautier, R McEwen, A Smythe, W Keszthelyi, L Carlson, R TI Prometheus: Io's wandering plume SO SCIENCE LA English DT Article AB Unlike any volcanic behavior ever observed on Earth, the plume from Prometheus on Io has wandered 75 to 95 kilometers west over the last 20 years since it was first discovered by Voyager and more recently observed by Galileo. Despite the source motion, the geometric and optical properties of the plume have remained constant. We propose that this can be explained by vaporization of a sulfur dioxide and/or sulfur "snowfield" over which a Lava flow is moving. Eruption of a boundary-layer slurry through a rootless conduit with sonic conditions at the intake of the melted snow can account for the constancy of plume properties. C1 SW Kieffer Sci Consulting Inc, Bolton, ON L7E 5T4, Canada. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. RP Kieffer, SW (reprint author), SW Kieffer Sci Consulting Inc, 6 Queen St,Suite 206,POB 520, Bolton, ON L7E 5T4, Canada. RI Lopes, Rosaly/D-1608-2016 OI Lopes, Rosaly/0000-0002-7928-3167 NR 18 TC 61 Z9 62 U1 2 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 19 PY 2000 VL 288 IS 5469 BP 1204 EP 1208 DI 10.1126/science.288.5469.1204 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 315KH UT WOS:000087112600041 PM 10817989 ER PT J AU Bauschlicher, CW Ricca, A AF Bauschlicher, CW Ricca, A TI Heats of formation for CnFm, CnFm+, CHFm, and CHFm+ SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID GAUSSIAN-BASIS SETS; CORRELATED MOLECULAR CALCULATIONS; COUPLED-CLUSTER THEORY; ELECTRON CORRELATION; DISSOCIATION-ENERGY; WAVE-FUNCTIONS; THERMOCHEMISTRY; CF3; C-2 AB Heats of formation for CnFm, CnFm+, CHFm, and CHFm+ compounds are computed at the G3MP2 level. Calibration calculations are presented for C2F2, C2F, CHF, and CHF2. The results of these calibration calculations, in conjunction with the results of previous high-level calculations, show that the G3MP2 approach is accurate to +/-2 kcal/mol for these systems. The trends in bond energies are discussed. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Ricca, A (reprint author), NASA, Ames Res Ctr, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 33 TC 30 Z9 30 U1 0 U2 1 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 MAY 18 PY 2000 VL 104 IS 19 BP 4581 EP 4585 DI 10.1021/jp9942771 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 313MJ UT WOS:000087003200030 ER PT J AU Folkins, I Chatfield, R AF Folkins, I Chatfield, R TI Impact of acetone on ozone production and OH in the upper troposphere at high NOx SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID HYDROGEN RADICALS; HOX; PHOTOCHEMISTRY; CHEMISTRY; PEROXIDES; NITROGEN; PLUMES; O-3 AB The impact of acetone (or any HOx source) on tropospheric photochemistry is largest in the high NOx regime. The fractional increases in OH and ozone production associated with acetone increase rapidly with NOx when NOx mixing ratios become larger than 300 parts per trillion by volume (pptv). This occurs in part because the HOx yield of acetone is larger at higher NOx mixing ratios: going from about 1 HOx at NOx similar to 10 pptv to 3 HOx at NOx similar to 1000 pptv. We lso investigate the effect of acetone on the partitioning of the NOy family. Acetone increases the conversion of NO to NO2, HNO4, HNO3, and peroxyacetylnitrate (PAN). Conversion of NO to PAN dominatesat low NOx, while conversion of NO to HNO3 dominates at high NOx. These NO decreases significantly diminish the increases in OH and ozone production one would otherwise anticipate fr om the increases in HO2. In particular, acetone can be expected to reduce ozone production for NOx < 25 pptv. We also show that most of the changes in species concentrations arising from the introduction of a HOx source can be accurately predicted using simple expressions derived from linear perturbation theory. C1 Dalhousie Univ, Dept Oceanog, Halifax, NS B3H 4J1, Canada. Dalhousie Univ, Dept Phys, Atmospher Sci Program, Halifax, NS B3H 4J1, Canada. NASA, Ames Res Ctr, Div Earth Sci, Moffett Field, CA 94035 USA. RP Folkins, I (reprint author), Dalhousie Univ, Dept Oceanog, Halifax, NS B3H 4J1, Canada. EM Ian.Folkins@dal.ca; chatfield@clio.arc.nasa.gov NR 15 TC 34 Z9 34 U1 0 U2 12 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2000 VL 105 IS D9 BP 11585 EP 11599 DI 10.1029/2000JD900067 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 315RA UT WOS:000087125700006 ER PT J AU Jackman, CH Fleming, EL Vitt, FM AF Jackman, CH Fleming, EL Vitt, FM TI Influence of extremely large solar proton events in a changing stratosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID EARTHS MIDDLE ATMOSPHERE; 2-DIMENSIONAL MODEL; ODD NITROGEN; OZONE DEPLETION; PARTICLE EVENTS; NITRIC-OXIDE; OCTOBER 1989; CHEMISTRY AB Two periods of extremely large solar proton events (SPEs) occurred in the past 30 years, which forced significant long-term polar stratospheric changes. The August 2-10, 1972, and October 19-27, 1989, SPEs happened in stratospheres that were quite different chemically. The stratospheric chlorine levels were relatively small in 1972 (similar to 1.2 ppbv) and were fairly substantial in 1989 (similar to 3 ppbV). Although these SPEs produced both HOx and NOy constituents in the mesosphere and stratosphere, only the NOy constituents had lifetimes long enough to affect ozone for several months to years past the events. Our recently improved two-dimensional chemistry and transport atmospheric model was used to compute the effects of these gigantic SPEs in a changing stratosphere. Significant upper stratospheric ozone depletions >10% are computed to last for a few months past these SPEs. The long-lived SPE-produced NOy constituents were transported to lower levels during winter after these huge SPEs and caused impacts in the middle and lower stratosphere. During periods of high halogen loading, these impacts resulted in interference with the chlorine and bromine loss cycles for ozone destruction. This interference actually led to a predicted total ozone increase that was especially notable in the time period 1992-1994, a few years after the October 1989 SPE. The chemical state of the atmosphere, including the stratospheric sulfate aerosol density: substantially affected the predicted stratospheric influence of these extremely large SPEs. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sterling Sofware, Bellevue, NE 68005 USA. Steven Myers & Associates Corp, Arlington, VA USA. RP Jackman, CH (reprint author), NASA, Goddard Space Flight Ctr, Code 916,Greenbelt Rd, Greenbelt, MD 20771 USA. EM jackman@assess.gsfc.nasa.gov; fleming@kahuna.gsfc.nasa.gov; francis.vitt@sterling.com RI Jackman, Charles/D-4699-2012 NR 33 TC 81 Z9 82 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2000 VL 105 IS D9 BP 11659 EP 11670 DI 10.1029/2000JD900010 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 315RA UT WOS:000087125700012 ER PT J AU Webster, CR Michelsen, HA Gunson, MR Margitan, JJ Russell, JM Toon, GC Traub, WA AF Webster, CR Michelsen, HA Gunson, MR Margitan, JJ Russell, JM Toon, GC Traub, WA TI Response of lower stratospheric HCl/Cl-y to volcanic aerosol: Observations from aircraft, balloon, space shuttle, and satellite instruments SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SULFURIC-ACID; OZONE DEPLETION; MT-PINATUBO; ARCTIC STRATOSPHERE; BORNE MEASUREMENTS; ATMOS MEASUREMENTS; SULFATE AEROSOLS; ER-2 AIRCRAFT; CHLORINE; CLO AB Vertical profiles of HCl/Cl-y measured by space shuttle (Atmospheric Trace Molecule Spectroscopy (ATMOS)) and balloon (MkIV) instruments from 1985 through 1994 show that the increased volcanic aerosol from Mount Pinatubo had little effect on chlorine partitioning above 21 km. Below 21 km, however, large changes in HCl/l(y) were observed. Aircraft (Aircraft Laser Infrared Absorption Spectrometer), balloon (MkIV, Far Infrared Spectrometer 2), space shuttle (ATMOS), and satellite (Halogen Occultation Experiment) measurements below 21 km reveal an increase in HCl/Cl-y between early 1993 and late 1997 of 31 +/- 9%. This growth rate is 2 to 3 times larger than model estimates of the effect of the change in aerosol surface area and volume over this time period. For 1993 the five independent direct measurements of HCl/Cl-y produce a mean value of 0.57 +/- 0.05, whereas by 1997 the mean value was 0.75 +/- 0.07, in excellent agreement with the pre-Pinatubo mean of 0.74 +/- 0.11. Measurements made in 1992 at the peak of the post-Pinatubo midlatitude aerosol loading demonstrate large variability, which is qualitatively consistent with model predictions. This variability appears to be attributable to the temperature sensitivity of the Cl-y partitioning when aerosol abundances are high. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Sandia Natl Labs, Livermore, CA 94551 USA. Hampton Univ, Dept Phys, Hampton, VA 23668 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Webster, CR (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM cwebster@alpha1.jpl.nasa.gov NR 56 TC 6 Z9 6 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2000 VL 105 IS D9 BP 11711 EP 11719 DI 10.1029/1999JD901135 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 315RA UT WOS:000087125700015 ER PT J AU Rolland, P Liou, KN King, MD Tsay, SC McFarquhar, GM AF Rolland, P Liou, KN King, MD Tsay, SC McFarquhar, GM TI Remote sensing of optical and microphysical properties of cirrus clouds using Moderate-Resolution Imaging Spectroradiometer channels: Methodology and sensitivity to physical assumptions SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SOLAR-RADIATION MEASUREMENTS; EFFECTIVE PARTICLE RADIUS; MU-M WINDOW; LIGHT-SCATTERING; ICE CRYSTALS; WATER-VAPOR; PARAMETERIZATION; TEMPERATURE; SPECTROMETER; THICKNESS AB A methodology for the retrieval of cirrus cloud microphysical and optical properties based on observations of reflected sunlight is introduced. The retrieval method is based on correlation of the bidirectional reflectance of three channels, 0.65, 1.6, and 2.2 mu m, that are available onboard Earth Observing System (EOS) Moderate-Resolution Imaging Spectroradiometer (MODIS). Validation studies using microphysical measurements and MODIS airborne simulator (MAS) observations illustrate the nature of the potential errors associated with the retrieved optical depth and mean effective ice crystal size. The effects of the physical assumptions involving ice crystal size distribution and shape employed in the algorithm are subsequently assessed. In terms of the microphysical models used for radiation calculations the ice crystal shape assumption is found to have the most significant impact on the retrieved parameters. The effect of the background surface reflectance on the retrieval results is further examined, and we show that in order to reliably infer nonblack cirrus parameters from solar reflectance measurements it is essential to properly account for the background radiation over both land and ocean surfaces. Finally, we present the measured ice microphysical data for tropical cirrus as a function of cloud development and ambient temperature to illustrate the importance of vertical inhomogeneity for validation studies. C1 Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. RP Rolland, P (reprint author), Univ Calif Los Angeles, Dept Atmospher Sci, 7127 Math Sci Bldg,405 Hilgard Ave, Los Angeles, CA 90095 USA. EM prolland@atmos.ucla.edu RI King, Michael/C-7153-2011; Tsay, Si-Chee/J-1147-2014; OI King, Michael/0000-0003-2645-7298; McFarquhar, Greg/0000-0003-0950-0135 NR 47 TC 63 Z9 64 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2000 VL 105 IS D9 BP 11721 EP 11738 DI 10.1029/2000JD900028 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 315RA UT WOS:000087125700016 ER PT J AU Baum, BA Kratz, DP Yang, P Ou, SC Hu, YX Soulen, PF Tsay, SC AF Baum, BA Kratz, DP Yang, P Ou, SC Hu, YX Soulen, PF Tsay, SC TI Remote sensing of cloud properties using MODIS airborne simulator imagery during SUCCESS 1. Data and models SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OCTOBER 1986 FIRE; SOLAR RADIATIVE-TRANSFER; SMALL ICE CRYSTALS; LIGHT-SCATTERING; CIRRUS CLOUDS; SINGLE-SCATTERING; OPTICAL-CONSTANTS; SPECTRAL RANGE; WATER; LIDAR AB We investigate methods to infer cloud properties such as cloud optical thickness, thermodynamic phase, cloud particle size, and cloud overlap by comparing cloud and clear-sky radiative transfer computations to measurements provided by the Moderate Resolution Imaging Spectroradiometer (MODIS) airborne simulator (MAS). The MAS scanning spectroradiometer was flown on the NASA ER-2 during the Subsonic Aircraft Contrail and Cloud Effects Special Study (SUCCESS) field campaign during April and May 1996. The MAS bands chosen for this study correspond to wavelengths of 0.65, 1.63, 1.90, 2.15, 3.82, 8.52, 11, and 12 mu m. Clear-sky absorption due to water vapor, ozone, and other trace gases is calculated using a set of correlated k-distribution routines developed specifically for these MAS bands. Scattering properties (phase function, single scattering albedo, and extinction cross section) are derived for water droplet clouds using Mie theory. Scattering properties for ice-phase clouds are incorporated for seven cirrus models: cirrostratus, cirrus uncinus, cold cirrus, warm cirrus, and cirrus at temperatures of T = -20 degrees C, -40 degrees C, and -60 degrees C. The cirrus are composed of four crystal types: hexagonal plates, two-dimensional bullet rosettes, hollow columns, and aggregates. Results from comparison of MAS data from a liquid water cloud with theoretical calculations indicate that estimates of optical thickness and particle size are reasonably consistent with one another no matter which spectral bands are used in the analysis. However, comparison of MAS data from a cirrus cloud with theoretical calculations shows consistency in optical thickness but not with particle size among the various band combinations used in the analysis. The methods described in this paper are used in two companion papers to explore techniques to infer cloud thermodynamic phase and cloud overlap. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Calif State Univ Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90032 USA. Univ Maryland, Joint Ctr Earth Syst Technol, Catonsville, MD 21228 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Baum, BA (reprint author), NASA, CIMS, 1225 W Dayton St, Madison, WI 53706 USA. EM bryan.baum@ssec.wisc.edu RI Yang, Ping/B-4590-2011; Baum, Bryan/B-7670-2011; Tsay, Si-Chee/J-1147-2014; Hu, Yongxiang/K-4426-2012 OI Baum, Bryan/0000-0002-7193-2767; NR 34 TC 96 Z9 100 U1 2 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2000 VL 105 IS D9 BP 11767 EP 11780 DI 10.1029/1999JD901089 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 315RA UT WOS:000087125700019 ER PT J AU Baum, BA Soulen, PF Strabala, KI King, MD Ackerman, SA Menzel, WP Yang, P AF Baum, BA Soulen, PF Strabala, KI King, MD Ackerman, SA Menzel, WP Yang, P TI Remote sensing of cloud properties using MODIS airborne simulator imagery during SUCCESS 2. Cloud thermodynamic phase SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CIRRUS CLOUDS; WATER-VAPOR; MU-M; RADIATIVE PROPERTIES; SPECTROMETER; WINDOW; REGION; ICE AB Methods to infer cloud thermodynamic phase (ice or water) are investigated using multispectral imagery. An infrared (IR) trispectral algorithm using the 8.52-, 11-, and 12-mu m bands [Ackerman et al., 1990; Strabala et al., 1994] forms the basis of this work and will be applied to data from the Earth Observing System (EOS) Moderate-Resolution Imaging Spectroradiometer (MODIS) instrument. Since the algorithm uses IR bands, it can be applied to either daytime or nighttime data and is not sensitive to the presence of cloud shadows. A case study analysis is performed with a MODIS airborne simulator (MAS) scene collected during the Subsonic Aircraft Contrail and Cloud Effects Special Study (SUCCESS) on April 21, 1996, at 2000 UTC. The scene under scrutiny is quite complex, containing low-level broken water clouds, cirrus cells, cloud shadows, subvisual cirrus, and contrails. The IR trispectral algorithm is found to be less accurate in (1) regions where more than one cloud phase type occurs and (2) regions of thin cirrus overlying a lower-level cloud layer. To improve the phase retrieval accuracy in these areas of difficulty, additional bands located at 0.65, 1.63, and 1.90 mu m are incorporated, Radiative transfer (RT) calculations are performed to simulate the MAS bands using the cirrus and water cloud models detailed by Baum et al. [this issue]. The RT calculations are performed for singlelayer cirrus- and water-phase clouds as well as for the case of thin cirrus overlying a lower-level water droplet cloud. Both modeled results and application of the theory to a case study suggest that the cloud thermodynamic phase retrieval accuracy can be improved by inclusion of the visible and near infrared bands. C1 NASA, NESDIS, Adv Satellite Prod Team, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Joint Ctr Earth Syst Technol, Catonsville, MD 21228 USA. Sci Syst & Applicat Inc, Lanham, MD 20706 USA. RP Baum, BA (reprint author), NASA, CIMSS, 1225 W Dayton St, Madison, WI 53706 USA. EM bryan.baum@ssec.wisc.edu RI Menzel, W. Paul/B-8306-2011; Yang, Ping/B-4590-2011; King, Michael/C-7153-2011; Ackerman, Steven/G-1640-2011; Baum, Bryan/B-7670-2011 OI Menzel, W. Paul/0000-0001-5690-1201; King, Michael/0000-0003-2645-7298; Ackerman, Steven/0000-0002-4476-0269; Baum, Bryan/0000-0002-7193-2767 NR 23 TC 102 Z9 110 U1 2 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2000 VL 105 IS D9 BP 11781 EP 11792 DI 10.1029/1999JD901090 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 315RA UT WOS:000087125700020 ER PT J AU Baum, BA Spinhirne, JD AF Baum, BA Spinhirne, JD TI Remote sensing of cloud properties using MODIS airborne simulator imagery during SUCCESS 3. Cloud overlap SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID AVHRR DATA; RADIATION; VERIFICATION; SYSTEMS; CLIMATE AB The vertical distribution of cloud layers has a significant effect on atmospheric radiative heating/cooling distributions. While multiple cloud layers are often observed to occur simultaneously by surface observers, satellite cloud retrieval methodology typically assumes that any individual imager pixel contains a single cloud layer. The purpose of this paper is to demonstrate a bispectral method that detects imager pixels containing possible cloud overlap when an optically thin cirrus cloud overlies a low level water cloud, with at least a 2-km separation between layers. The method is developed from a scatterplot of the near-infrared 1.63-mu m band reflectances and the 11-mu m brightness temperatures using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) airborne simulator (MAS). The bispectral method is applied to a scene recorded by the MAS scanning spectrometer that was flown on the NASA ER-2 during the Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS)field campaign during April and May 1996, For a scene recorded on April 21, 1996, at 2000 UTC, the complex vertical cloud structure was captured by lidar backscatter measurements from the Cloud Lidar System (CLS). The bispectral method appears to have a promising facility for identifying areas containing potential cloud overlap. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Baum, BA (reprint author), NASA, CIMSS, 1225 W Dayton St, Madison, WI 53706 USA. EM bryan.baum@ssec.wisc.edu RI Baum, Bryan/B-7670-2011 OI Baum, Bryan/0000-0002-7193-2767 NR 24 TC 23 Z9 31 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2000 VL 105 IS D9 BP 11793 EP 11804 DI 10.1029/1999JD901091 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 315RA UT WOS:000087125700021 ER PT J AU Schoeberl, MR Morris, GA AF Schoeberl, MR Morris, GA TI A Lagrangian simulation of supersonic and subsonic aircraft exhaust emissions SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC O-3; TRANSPORT AB To estimate the effect of subsonic and supersonic aircraft exhaust on the stratospheric concentration of NOy, we employ a trajectory model initialized with air parcels based on the standard release scenarios. The supersonic exhaust simulations are in good agreement with two-dimensional (2-D) and 3-D model results and show a perturbation of about 1-2 ppbv of NOy in the stratosphere. The subsonic simulations show that subsonic emissions are almost entirely trapped below the 380 K potential temperature surface. Our subsonic results contradict results from most other models, which show exhaust products penetrating above 380 K, as summarized by Danilin et al. [1998] and Intergovernmental Panel on Climate Change (IPCC) [1999]. The disagreement can likely be attributed to the excessive model diffusion of the strong vertical gradient in NOy that forms at the boundary between the emission zone and the stratosphere above 380 K. Our results suggest that previous assessments of the impact of subsonic exhaust emission on the stratospheric region above 380 K should be considered to be an upper bound. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Valparaiso Univ, Dept Phys & Astron, Valparaiso, IN 46383 USA. RP Schoeberl, MR (reprint author), NASA, Goddard Space Flight Ctr, Code 910, Greenbelt, MD 20771 USA. EM schom@zephyr.gsfc.nasa.gov NR 20 TC 6 Z9 6 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2000 VL 105 IS D9 BP 11833 EP 11839 DI 10.1029/1999JD901151 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 315RA UT WOS:000087125700024 ER PT J AU McLandress, C Alexander, MJ Wu, DL AF McLandress, C Alexander, MJ Wu, DL TI Microwave Limb Sounder observations of gravity waves in the stratosphere: A climatology and interpretation SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MIDDLE ATMOSPHERE; SATELLITE-OBSERVATIONS; GENERAL-CIRCULATION; TEMPERATURE; CONVECTION; FLUCTUATIONS; VARIANCE; WIND; PARAMETERIZATION; TROPOSPHERE AB High-horizontal-resolution temperature data from the Microwave Limb Sounder (MLS) are analyzed to obtain information about high intrinsic frequency gravity waves in the stratosphere. Global climatologies of temperature variance at solstice are computed using six years of data. A linear gravity wave model is used to interpret the satellite measurements and to infer information about tropospheric wave sources. Globally uniform sources having several different spectral shapes are examined and the computed variances are filtered in three-dimensional space in a manner that simulates the MLS weighting functions. The model is able to reproduce the observed zonal mean structure, thus indicating that the observations reflect changes in background wind speeds and provide little information about the latitudinal variation of wave sources. Longitudinal variations in the summer hemisphere do reflect source variations since the modeled variances exhibit much less variation in this direction as a consequence of the zonal symmetry of the background winds. A close correspondence between the MLS variances and satellite observations of outgoing-longwave radiation suggests that deep convection is the probable source for these waves. The large variances observed over the tip of South America in winter are most certainly linked to orographic forcing but inferences about wave sources in Northern Hemisphere winter are difficult to make as a result of the high degree of longitudinal and temporal variability in the stratospheric winds. Comparisons of model results using different source spectra suggest that the tropospheric sources in the subtropics in summer have a broader phase speed spectrum than do sources at middle latitudes in winter. C1 York Univ, Dept Earth & Atmospher Sci, N York, ON M3J 1P3, Canada. Colorado Res Associates, Boulder, CO 80301 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP McLandress, C (reprint author), York Univ, Dept Earth & Atmospher Sci, 4700 Keele St, N York, ON M3J 1P3, Canada. EM mcland@stpl.cress.yorku.ca; alexand@leonardo.colorado-research.com; dwu@hutong.jpl.nasa.gov RI Wu, Dong/D-5375-2012 NR 34 TC 123 Z9 125 U1 3 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 16 PY 2000 VL 105 IS D9 BP 11947 EP 11967 DI 10.1029/2000JD900097 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 315RA UT WOS:000087125700034 ER PT J AU Short, JW Bruce, AW AF Short, JW Bruce, AW TI Repose to comment on "Natural hydrocarbon background in benthic sediments of Prince William Sound, Alaska: Oil vs coal" SO ENVIRONMENTAL SCIENCE & TECHNOLOGY LA English DT Letter ID SPILL C1 NOAA, Auke Bay Lab, Alaska Fisheries Sci Ctr, Natl Marine Fisheries Serv, Juneau, AK 99801 USA. US Geol Survey, Menlo Park, CA 94025 USA. RP Short, JW (reprint author), NOAA, Auke Bay Lab, Alaska Fisheries Sci Ctr, Natl Marine Fisheries Serv, 11305 Glacier Highway, Juneau, AK 99801 USA. NR 8 TC 2 Z9 2 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0013-936X J9 ENVIRON SCI TECHNOL JI Environ. Sci. Technol. PD MAY 15 PY 2000 VL 34 IS 10 BP 2066 EP 2067 DI 10.1021/es002001x PG 2 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA 314RT UT WOS:000087071900030 ER PT J AU Gopalswamy, N Kaiser, ML Thompson, BJ Burlaga, LF Szabo, A Lara, A Vourlidas, A Yashiro, S Bougeret, JL AF Gopalswamy, N Kaiser, ML Thompson, BJ Burlaga, LF Szabo, A Lara, A Vourlidas, A Yashiro, S Bougeret, JL TI Radio-rich solar eruptive events SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CORONAL MASS EJECTIONS; WIND SPACECRAFT; EMISSIONS; ORIGIN; SHOCKS AB We report on the analysis of a large number of solar eruptive events that produced radio emission in the dekameter-hectometric (DH) radio window (1-14 MHz), newly opened by the Wind/WAVES experiment. The distinguishing characteristics of coronal mass ejections (CMEs) associated with the DH type II radio bursts are larger-than-average width and speed. Flares of all sizes (X-ray importance B to X) occurring at all longitudes were associated with the DH type II bursts and CMEs. We found a global enhancement in EUV over an area much larger than the flaring active region in the beginning many events. A comparison between the 'Shock Associated' events and microwave bursts shows that at least half of the events do not have temporal relation. A majority of the DH type II bursts were associated with IP shocks and kilometric type II bursts. In particular, we found a very close relationship between the kilometric type II bursts and the IP shocks. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. George Mason Univ, CEOSR, CSI, Fairfax, VA 22030 USA. Natl Astron Observ, Mitaka, Tokyo 1818588, Japan. Observ Paris, Meudon, France. RP Gopalswamy, N (reprint author), NASA, Goddard Space Flight Ctr, Bldg 26,Room G1,Mailcode 682-3, Greenbelt, MD 20771 USA. RI Vourlidas, Angelos/C-8231-2009; Gopalswamy, Nat/D-3659-2012; Thompson, Barbara/C-9429-2012; OI Vourlidas, Angelos/0000-0002-8164-5948; Lara, Alejandro/0000-0001-6336-5291 NR 13 TC 73 Z9 74 U1 1 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 2000 VL 27 IS 10 BP 1427 EP 1430 DI 10.1029/1999GL003665 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 314NK UT WOS:000087062000001 ER PT J AU Thompson, BJ Cliver, EW Nitta, N Delannee, C Delaboudiniere, JP AF Thompson, BJ Cliver, EW Nitta, N Delannee, C Delaboudiniere, JP TI Coronal dimmings and energetic CMEs in April-May 1998 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MASS EJECTION; SOHO/EIT OBSERVATIONS; EIT AB We have analyzed the coronal dimmings for seven fast (> 600 km/s) coronal mass ejections (CMEs) occurring between 23 April and 9 May which were associated with flares from NOAA active region (AR) 8210. Each of these CMEs had at least one group of interplanetary radio bursts associated with them. These dimming regions were identified by their strong depletion in coronal EUV emission within a half hour of the estimated time of CME lift-off. They included areas which were as dark as quiescent coronal holes as well as other regions with weaker brightness depletions. While the location of the active region and the associated flare did not correspond well with the coronagraph observations, we found that the extended dimming areas in these events generally mapped out the apparent "footprint" of the CME as observed by white-light coronagraph. We briefly discuss the implications of these results on models of CME topology. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USAF, Res Lab, Hanscom AFB, MA USA. Lockheed Martin Solar & Astrophys Lab, Palo Alto, CA USA. Inst Astrophys Spatiale, Orsay, France. RP Thompson, BJ (reprint author), NASA, Goddard Space Flight Ctr, Code 682, Greenbelt, MD 20771 USA. RI Thompson, Barbara/C-9429-2012 NR 18 TC 128 Z9 129 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 MAY 15 PY 2000 VL 27 IS 10 BP 1431 EP 1434 DI 10.1029/1999GL003668 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 314NK UT WOS:000087062000002 ER PT J AU Lara, A Gopalswamy, N DeForest, C AF Lara, A Gopalswamy, N DeForest, C TI Change in photospheric magnetic flux during coronal mass ejections SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID FLARE; FIELDS AB We report on the variations of photospheric magnetic flux during coronal mass ejections (CMEs). Using magneograms from the SOHO/MDI instrument, we have computed the magnetic flux of 7 active regions and one disappearing filament region associated with CMEs. When we plotted the flux versus time over a period of few days before, during and after the CME event, we found changes in the mean magnetic flux per pixel (similar to 4 arcsec(2)), ranging from similar to 0.4 to similar to 3.1 x 10(17) Mx, in structures of size smaller than the active region. Flare onsets and the filament disappearance clearly occurred during periods of significant variations in the measured magnetic flux. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Washington, DC 20064 USA. RP Lara, A (reprint author), NASA, Goddard Space Flight Ctr, Bldg 26 Room G1,Mailstop 682-0, Greenbelt, MD 20771 USA. RI Gopalswamy, Nat/D-3659-2012; OI Lara, Alejandro/0000-0001-6336-5291 NR 12 TC 25 Z9 26 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 MAY 15 PY 2000 VL 27 IS 10 BP 1435 EP 1438 DI 10.1029/1999GL003666 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 314NK UT WOS:000087062000003 ER PT J AU Raymond, JC Thompson, BJ Cyr, OCS Gopalswamy, N Kahler, S Kaiser, M Lara, A Ciaravella, A Romoli, M O'Neal, R AF Raymond, JC Thompson, BJ Cyr, OCS Gopalswamy, N Kahler, S Kaiser, M Lara, A Ciaravella, A Romoli, M O'Neal, R TI SOHO and radio observations of a CME shock wave SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB A 1200 km s(-1) Coronal Mass Ejection was observed with the SOHO instruments EIT, LASCO and UVCS on June 11, 1998. Simultaneously, Type II radio bursts were observed with the WAVES experiment aboard the Wind spacecraft at 4 MHz and by groundbased instruments at metric wavelengths. The density in the shock wave implied by the higher frequency is close to that inferred from the SOHO/UVCS experiment. The drift rates of the Type II radio bursts suggest shock speeds lower than the speed derived from SOHO observations. The SOHO/UVCS spectrum shows enhanced emission in lines of O5+ and Si11+, consistent with modest compression in an MHD shock. C1 Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USAF, Res Lab, Bedford, MA 01731 USA. Catholic Univ Amer, Dept Solar Phys & Space Weather, Dept Phys, Washington, DC 20064 USA. Osserv Palermo, Palermo, Italy. Univ Florence, I-50125 Florence, Italy. RP Raymond, JC (reprint author), Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Gopalswamy, Nat/D-3659-2012; Romoli, Marco/H-6859-2012; Thompson, Barbara/C-9429-2012; OI Lara, Alejandro/0000-0001-6336-5291 NR 15 TC 68 Z9 68 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 2000 VL 27 IS 10 BP 1439 EP 1442 DI 10.1029/1999GL003669 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 314NK UT WOS:000087062000004 ER PT J AU Keating, GM Tolson, RH Bradford, MS AF Keating, GM Tolson, RH Bradford, MS TI Evidence of long term global decline in the Earth's thermospheric densities apparently related to anthropogenic effects SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID UPPER-ATMOSPHERE; CARBON-DIOXIDE; IONOSPHERIC TRENDS AB A study was performed of the long-term orbital decay of five Earth satellites with perigee altitudes averaging near 350km. To decouple long-term trend measurements from the effects of solar variability, measurements were evaluated during the years of solar minimum (1976, 1986 and 1996). Atmospheric densities derived from these essentially global measurements showed substantial evidence of a decline averaging 9.8 +/- 2.5% in thermospheric density over 20 years pointing toward a long-term cooling of the upper atmosphere. Increases in greenhouse gases induced by human activity are hypothesized to warm the Earth's surface and lower atmosphere, but strongly cool the upper atmosphere. Assuming that the 10% increase in CO2 over these 20 years caused cooling resulting in the 10% decline in density, a doubling of CO2 could cause the thermospheric densities measured near 350km to decrease by a factor of 3. This decrease may shrink the altitude of a constant density surface by 40km before the end of the 21(st) century. C1 George Washington Univ, NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Keating, GM (reprint author), George Washington Univ, NASA, Langley Res Ctr, MS 335, Hampton, VA 23681 USA. NR 21 TC 98 Z9 99 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 2000 VL 27 IS 10 BP 1523 EP 1526 DI 10.1029/2000GL003771 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 314NK UT WOS:000087062000025 ER PT J AU Wasilewski, P Kletetschka, G Dickinson, T AF Wasilewski, P Kletetschka, G Dickinson, T TI Magnetic characterization of reduction in Mount Fuji basaltic tree-mold SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CATION DIFFUSION; DEFECTS; MANTLE AB A Mount Fuji basaltic tree-mold presents the mineralogical record associated with a large oxygen fugacity gradient during the cooling of the basalt. Magnetic exchange anisotropy is postulated to be characteristic of cation excess in some spinel titanomagnetites. The exchange anisotropy is characterized by loop shifting along the field and magnetization axes when cooled in a magnetic field, large coercivity increase, and magnetic viscosity which has discrete activation fields and logarithmic to linear decay characteristics. The cryogenic loop characteristics attributable to exchange anisotropy are not found in the tree-mold where iron and ilmenite are the main phases. The coupling has been created in the laboratory with ordinary basalt artificially reduced in Hydrogen gas. The coupling is not found in spinel oxidation non-stoichiometry. These results imply that we are able to identify the presence of spinels that have equilibrated in the low oxygen fugacity range of the spinel stability field where cation excess is characteristic. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Wasilewski, P (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Kletetschka, Gunther/C-9996-2011 OI Kletetschka, Gunther/0000-0002-0645-9037 NR 16 TC 2 Z9 2 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 2000 VL 27 IS 10 BP 1543 EP 1546 DI 10.1029/1999GL008462 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 314NK UT WOS:000087062000030 ER PT J AU Bose, D Govindan, TR Meyyappan, M AF Bose, D Govindan, TR Meyyappan, M TI Ion dynamics model for collisionless radio frequency sheaths SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID ENERGY-DISTRIBUTIONS; PLASMA SHEATHS; RF DISCHARGES; REACTORS AB Full scale reactor model based on fluid equations is widely used to analyze high density plasma reactors. It is well known that the submillimeter scale sheath in front of a biased electrode supporting the wafer is difficult to resolve in numerical simulations, and the common practice is to use results for electric field from some form of analytical sheath model as boundary conditions for full scale reactor simulation. There are several sheath models in the literature ranging from Child's law to a recent unified sheath model [P. A. Miller and M. E. Riley, J. Appl. Phys. 82, 3689 (1997)]. In the present work, the cold ion fluid equations in the radio frequency sheath are solved numerically to show that the spatiotemporal variation of ion flux inside the sheath, commonly ignored in analytical models, is important in determining the electric field and ion energy at the electrode. Consequently, a semianalytical model that includes the spatiotemporal variation of ion flux is developed for use as boundary condition in reactor simulations. This semianalytical model is shown to yield results for sheath properties in close agreement with numerical solutions. (C) 2000 American Institute of Physics. [S0021-8979(00)02810-3]. C1 NASA, Ames Res Ctr, Eloret Corp, Moffett Field, CA 94035 USA. RP Bose, D (reprint author), NASA, Ames Res Ctr, Eloret Corp, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 11 TC 47 Z9 48 U1 0 U2 3 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 2000 VL 87 IS 10 BP 7176 EP 7184 DI 10.1063/1.372966 PG 9 WC Physics, Applied SC Physics GA 308TY UT WOS:000086730000006 ER PT J AU Karasik, BS McGrath, WR Gershenson, ME Sergeev, AV AF Karasik, BS McGrath, WR Gershenson, ME Sergeev, AV TI Photon-noise-limited direct detector based on disorder-controlled electron heating SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID ELECTROTHERMAL FEEDBACK; BOLOMETER; FILMS AB We present a concept for a hot-electron direct detector capable of counting single millimeter-wave photons. The detector is based on a microbridge (1 mu m size) transition edge sensor made from a disordered superconducting film. The electron-phonon coupling strength at temperatures of 100-300 mK is proportional to the elastic electron mean free path l and can be reduced by over an order of magnitude by decreasing l. The microbridge contacts are made from a different superconductor with higher critical temperature Nb, which blocks the thermal diffusion of hot carriers into the contacts. The low electron-phonon heat conductance and the high thermal resistance of the contacts determine the noise equivalent power of similar to 10(-20)-10(-21) W/root Hz at 100 mK, which is 10(2)-10(3) times better than that of state-of-the-art bolometers. Due to the effect of disorder, the electron cooling time is similar to 10(-1)-10(-2) s at 0.1 K. By exploiting negative electrothermal feedback, the detector time constant can be made as short as 10(-3)-10(-4) s without sacrificing sensitivity. (C) 2000 American Institute of Physics. [S0021-8979(00)00310-8]. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Rutgers State Univ, Dept Phys & Astron, Piscataway, NJ 08854 USA. Wayne State Univ, Dept Elect & Comp Engn, Detroit, MI 48202 USA. RP Karasik, BS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Karasik, Boris/C-5918-2011 NR 24 TC 39 Z9 39 U1 0 U2 0 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 2000 VL 87 IS 10 BP 7586 EP 7588 DI 10.1063/1.373026 PG 3 WC Physics, Applied SC Physics GA 308TY UT WOS:000086730000068 ER PT J AU Perigaud, C Melin, F Cassou, C AF Perigaud, C Melin, F Cassou, C TI ENSO simulated by intermediate coupled models and evaluated with observations over 1970-98. Part I: Role of the off-equatorial variability SO JOURNAL OF CLIMATE LA English DT Article ID NINO SOUTHERN OSCILLATION; OCEANIC ROSSBY WAVES; TROPICAL PACIFIC-OCEAN; EL-NINO; TEMPERATURE ANALYSES; RECHARGE PARADIGM; ATMOSPHERE MODEL; WESTERN PACIFIC; ZEBIAKS MODEL; SITU DATA AB ENSO simulations are investigated in 30-yr integrations of various intermediate coupled models and compared with observed SST, wind, and thermocline depth anomalies over the tropical Pacific. The Cane and Zebiak model simulates warm events with a period close to the observations, but with westerlies that are located 30 degrees east of them and thermocline anomalies in the western Pacific that are much shallower Between two warm events, the model simulates a series of three weak and short cold SST peaks and hardly ever simulates easterlies. The SST in the eastern equatorial Pacific is not sensitive to thermocline depth anomalies, but to the anomalous downwelling of surface currents induced by Ekman shear. The model simulates a pair of very strong cyclonic wind stress curl anomalies on both sides of the equator in the eastern off-equatorial domain between 7 degrees and 15 degrees lat. These are necessary to maintain the oscillatory regime-so are the ocean meridional Rossby modes higher than 5. The thermocline zonal slopes required to balance the off-equatorial curl anomalies are about three times steeper than the ones required to balance the zonal stress along the equator. Thus the off-equator exerts an excess of zonal pressure, which by continuity affects the equatorial ocean and plays a crucial role in reversing and triggering the growing events. Six months after the warm peaks, the whole ocean between 15 degrees S and 15 degrees N is significantly upwelled. The equatorial oceanic heat content is recharged from the south prior to a warm event. Contrary to simulations when the model is driven by observed wind anomalies, increasing the friction in the baroclinic ocean does not decrease the off-equatorial variability but significantly alters the low-frequency oscillations that are no longer ENSO-like. Introducing the parameterization of subsurface temperature derived from hydrographic profiles in the ocean component does not allow the coupled model to recover cold events as in a forced context, introducing the parameterization of convection derived from high-cloud temperature measurements is the most effective improvement, but results still poorly agree with observations and are in contrast with the simulations driven by observed SST, biased toward westerlies in the central Pacific, upwelled thermocline in the west, and warm SST in the east. Thus modifying the ocean component only or the atmosphere only does not have the same impact on simulations as in a forced context. The coupling allows new mechanisms to grow and govern the model behavior. One of them is the slow meridional oceanic mass adjusment in quasi-Sverdrup balance with the winds. C1 CALTECH, Jet Prop Lab, Ocean Sci Element, Pasadena, CA 91109 USA. RP Perigaud, C (reprint author), CALTECH, Jet Prop Lab, Ocean Sci Element, 4800 Oak Grove Dr,MS 300-323, Pasadena, CA 91109 USA. NR 42 TC 12 Z9 13 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD MAY 15 PY 2000 VL 13 IS 10 BP 1605 EP 1634 DI 10.1175/1520-0442(2000)013<1605:ESBICM>2.0.CO;2 PG 30 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 319PJ UT WOS:000087350100001 ER PT J AU Cassou, C Perigaud, C AF Cassou, C Perigaud, C TI ENSO simulated by intermediate coupled models and evaluated with observations over 1970-98. Part II: Role of the off-equatorial ocean and meridional winds SO JOURNAL OF CLIMATE LA English DT Article ID NINO SOUTHERN-OSCILLATION; INTERANNUAL VARIABILITY; ROSSBY WAVES; ATMOSPHERE; DYNAMICS AB Introducing new parameterizations of subsurface temperature and atmospheric convection in the Cane and Zebiak model allows the reproducing of oscillations with a period close to 4 yr; equatorial wind anomalies that are located close to the date line; and realistic amplitudes of SST, wind, and thermocline anomalies in the equatorial Pacific both in warm and cold phases. When the weight given to the atmospheric convection term is increased, the simulated wind maximum along the equator is displaced farther west, and the amplitude and duration of the warm events decrease. Compared to the simulations with the standard parameterization, the ENSO-like oscillations are not lost when the friction is increased with a decay time ranging from 30 to 12 months. Off-equatorial baroclinic ocean and wind anomalies are much less strong, but still necessary for the system to oscillate. Unrealistic easterlies are still present in the eastern Pacific. Replacing the atmospheric model by a statistical relationship between SST and wind stress anomalies allows further reducing of these deficiencies. The simulated ENSO-like events are in good agreement with observed oceanic and atmospheric fields in terms of amplitude and spatial patterns within 15 degrees of the equator. Sensitivity tests to the statistics prescribed in the atmospheric component show that the model simulates warm events with duration and amplitude that increase with the eastern penetration of the westerlies in the central Pacific, whereas cold events do not last longer and easterlies remain located at the date line whatever their strength. After warm events, the model simulates a gain of heat content on average in the north, and similar features are found in the 1983 and 1998 El Nino events, whereas the Cane and Zebiak model simulates a loss. The gain is due to northerlies along the ITCZ that are associated with an anticyclonic curl and a "recharge" of the oceanic heat content, whereas the loss is explained by the unrealistic easterlies in the eastern Pacific and by the weakness of the meridional winds. C1 CALTECH, Jet Prop Lab, Ocean Sci Element, Pasadena, CA 91109 USA. RP Perigaud, C (reprint author), CALTECH, Jet Prop Lab, Ocean Sci Element, 4800 Oak Grove Dr,MS 300-323, Pasadena, CA 91109 USA. NR 17 TC 10 Z9 10 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD MAY 15 PY 2000 VL 13 IS 10 BP 1635 EP 1663 DI 10.1175/1520-0442(2000)013<1635:ESBICM>2.0.CO;2 PG 29 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 319PJ UT WOS:000087350100002 ER PT J AU Comiso, JC AF Comiso, JC TI Variability and trends in Antarctic surface temperatures from in situ and satellite infrared measurements SO JOURNAL OF CLIMATE LA English DT Article ID HIGH-RESOLUTION RADIOMETER; SEA-ICE EXTENT; CLIMATE VARIABILITY; CIRCUMPOLAR WAVE; AIR-TEMPERATURE; TIME-SERIES; MINIMUM; SHEETS; OCEAN AB The surface air temperatures observed from stations in Antarctica have been shown to have predominantly positive trends that are as high as 0.5 degrees C decade(-1) along the Antarctic Peninsula. To evaluate whether the trends are caused by a local or large-scale phenomenon in the Antarctic region, surface temperatures inferred from infrared satellite data from 1979 to 1998 have been analyzed in combination with data from 21 stations that have long record lengths. The surface temperatures derived from infrared data are coherent spatially and temporally and are shown to agree well with Antarctic station data with a correlation coefficient of 0.98 and a standard deviation of about 3 degrees C. The trend analysis on station data yielded on the average 0.012 +/- 0.008 degrees C yr(-1) and -0.008 +/- 0.025 degrees C yr(-1) for the 45- and 20-yr record, respectively. The latter reasonably agrees with the trend of -0.042 +/- 0.067 degrees C yr(-1) inferred from the satellite 20-yr record. The 20-yr record length is shown to be about the minimum length required for a meaningful trend analysis study. However, interannual fluctuations of the temperatures are large and the 95% confidence level for the satellite trends ranges from -0.177 to 0.094 degrees C yr(-1) for the Antarctic ice sheet. Nevertheless, the observed cooling is intriguing, especially since it is compatible with the observed trend in the sea ice cover. In the sea ice regions, the northernmost positions of the ice edge are shown to be influenced by alternating warm and cold anomalies around the Continent. The pattern of these anomalies is consistent with that of the Antarctic circumpolar wave but with predominantly mode-3 instead of mode-2 wave as reported previously. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. RP Comiso, JC (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Code 971, Greenbelt, MD 20771 USA. NR 44 TC 224 Z9 232 U1 0 U2 19 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD MAY 15 PY 2000 VL 13 IS 10 BP 1674 EP 1696 DI 10.1175/1520-0442(2000)013<1674:VATIAS>2.0.CO;2 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 319PJ UT WOS:000087350100004 ER PT J AU Adamec, D AF Adamec, D TI Eddy flow characteristics and mean flow interactions in the North Pacific SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID OCEANIC GENERAL CIRCULATION; KUROSHIO EXTENSION; GEOSAT ALTIMETRY; MESOSCALE EDDIES; SOUTHERN-OCEAN; MOMENTUM FLUX; VARIABILITY; TOPEX/POSEIDON; PROPAGATION; TRANSPORT AB The strength, shape, orientation, mean flow interactions, and propagation characteristics of the time-varying (eddy) flow determined from TOPEX/Poseidon altimeter data in the North Pacific are investigated using equivalent barotropic diagnostic calculations as presented by Hoskins ct al. [1983]. Separate calculations for low- and high-pass flow fields, distinguished by periods greater than and less than 6 months, respectively, are performed and revealed a fundamental difference between the eddy characteristics of the two. The areas with largest values of surface eddy kinetic energy occur in the vicinity of the Kuroshio Extension and the subtropical front. Near the Kuroshio Extension the low-pass surface eddy kinetic energy is gl-eater than the high-pass energy, but in the subtropical frontal area the high-pass eddy Row accounts for more energy than the lowpass flow. For both areas the values of eddy kinetic energy are larger in summer than during winter, Low-pass eddy flow tends to be aligned zonally, and the high-pass eddy flow is aligned meridionally. Near the subtropical front the ratio of major to minor axis length is typically similar to 1.5:1, whereas near the Kuroshio Extension that ratio increases to values near 2:1. Along the southern boundary of the subtropical gyre the high-pass eddy flow tends to propagate eastward relative to the mean flow, tending to decrease the gyre strength. However, the low-pass eddy flow propagates westward relative to the mean flow and tends to increase the gyre strength. An additional computation of surface heat transport is used to deduce vertical propagation tendencies of the eddy flow and indicates that the low-pass flow field transports more heat than the high-pass flow with the largest eddy transports occurring near the coast of Honshu. The sign of the transport indicates a preference for upward energy propagation of the eddy flow there. Many of the characteristics, such as the orientation and propagation tendencies of the eddy flow, are similar to eddy now in the atmosphere: and accentuate a similarity between the general circulations of the atmosphere and ocean. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Oceans & Ice Branch, Greenbelt, MD 20771 USA. RP Adamec, D (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Oceans & Ice Branch, Greenbelt, MD 20771 USA. NR 22 TC 3 Z9 3 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-OCEANS JI J. Geophys. Res.-Oceans PD MAY 15 PY 2000 VL 105 IS C5 BP 11373 EP 11383 DI 10.1029/2000JC900016 PG 11 WC Oceanography SC Oceanography GA 316DU UT WOS:000087153000010 ER PT J AU Nakamura, M Chao, Y AF Nakamura, M Chao, Y TI Characteristics of three-dimensional quasi-geostrophic transient eddy propagation in the vicinity of a simulated Gulf Stream SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID BOUNDARY CURRENT CROSSOVER; NONZONAL OCEAN CURRENTS; LIMITED-AREA MODEL; NORTH-ATLANTIC; 3-DIMENSIONAL PROPAGATION; HORIZONTAL RESOLUTION; NUMERICAL EXPERIMENTS; GENERAL-CIRCULATION; WAVE RADIATION; EDDIES AB Output of an eddy-resolving model of the North Atlantic is diagnosed in the vicinity of the Gulf Stream (GS), using the three-dimensional quasi-geostrophic transient wave activity flux diagnostic developed by Plumb [1986]. The model North Atlantic shows large transient wave activity along the model GS and along the edge of the Mediterranean Outflow. The fluxes show advection of wave activity by the GS from the separation point and radiation of wave activity from the GS in the top 1000 m. The wave radiation from the model GS is particularly clear to its south and points southwestward in general. The fluxes in and around the Mediterranean Outflow appear to be generated and dissipated locally. The vertical component of the transient wave activity flux is downward on average at all depths, suggesting conversion of baroclinic energy supplied near the surface into kinetic energy distributed throughout the depth. Eddy fields show that transient eddies tend to reinforce quasi-stationary meanders in the GS just downstream of the separation point. We also find evidence for eddy forcing of the northern recirculation generated in the model, in agreement with the available observations. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, Mail Stop 300-323,4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM moto@pacific.jpl.nasa.gov NR 49 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9275 EI 2169-9291 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD MAY 15 PY 2000 VL 105 IS C5 BP 11385 EP 11406 DI 10.1029/2000JC900013 PG 22 WC Oceanography SC Oceanography GA 316DU UT WOS:000087153000011 ER PT J AU Hu, YX Wielicki, B Lin, B Gibson, G Tsay, SC Stamnes, K Wong, T AF Hu, YX Wielicki, B Lin, B Gibson, G Tsay, SC Stamnes, K Wong, T TI delta-Fit: A fast and accurate treatment of particle scattering phase functions with weighted singular-value decomposition least-squares fitting SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID DISCRETE-ORDINATE-METHOD; RADIATIVE-TRANSFER; APPROXIMATION; ATMOSPHERES AB With a limited number of polynomial terms (so-called "streams"), there are significant differences between a phase function and its Legendre polynomial expansion at large scattering angles, which are important to satellite observations. This study finds that while it takes hundreds of Legendre polynomial expansion terms to simulate the backscattering portion of cloud phase functions accurately, the backscattered radiance pattern can be accurately estimated with only 30 Legendre polynomial expansion terms by replacing the regular Legendre polynomial expansion coefficients by coefficients obtained by a weighted singular-value decomposition least-squares fitting procedure. Thus the computing time can be significantly reduced. For satellite remote-sensing purposes, the weighted least-squares Legendre polynomial fitting is an optimal estimation of the cloud phase function. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Hampton Univ, CAS, NASA, LaRC, Hampton, VA 23681 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. UAF, Inst Geophys, Fairbanks, AK USA. RP Hu, YX (reprint author), Hampton Univ, CAS, NASA, LaRC, MS 420, Hampton, VA 23681 USA. RI Tsay, Si-Chee/J-1147-2014; Hu, Yongxiang/K-4426-2012 NR 6 TC 65 Z9 71 U1 1 U2 4 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 MAY 15 PY 2000 VL 65 IS 4 BP 681 EP 690 DI 10.1016/S0022-4073(99)00147-8 PG 10 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 285KF UT WOS:000085387700007 ER PT J AU Raj, SV Freed, AD AF Raj, SV Freed, AD TI A phenomenological description of primary creep in class M materials SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article DE primary creep; creep microstructures; activation energy; transient creep; stress change experiments ID HIGH TEMPERATURE CREEP; SINGLE-CRYSTALS; INTERMEDIATE TEMPERATURES; SUBSTRUCTURE FORMATION; STRESS REDUCTIONS; POWER-LAW; COPPER; METALS; BEHAVIOR; DEFORMATION AB Observations of deformation microstructures in the primary creep region in class M materials show a remarkable similarity with those formed in the exponential creep regime. As a result, it is proposed that the constitutive creep law for normal primary creep is similar to that for the exponential creep regime. A phenomenological description is discussed to rationalize these microstructural observations in terms of a normalized strain rare versus stress plot. The implications of this plot in describing different testing procedures. steady-state flow, and on the observed deviations from the universal creep law are discussed. The plot is also extended to explain the observed similarities in the transient creep behavior in pre-strained materials and in stress change experiments. Published by Elsevier Science S.A. C1 NASA, Glenn Res Ctr, Div Mat, Cleveland, OH 44135 USA. RP Raj, SV (reprint author), NASA, Glenn Res Ctr, Div Mat, MS 24-1,21000 Brookpark Rd, Cleveland, OH 44135 USA. OI Freed, Alan/0000-0002-3492-0628 NR 37 TC 9 Z9 9 U1 0 U2 2 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD MAY 15 PY 2000 VL 283 IS 1-2 BP 196 EP 202 DI 10.1016/S0921-5093(99)00790-X PG 7 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 304HC UT WOS:000086476800025 ER PT J AU Anantram, MP Datta, S Xue, YQ AF Anantram, MP Datta, S Xue, YQ TI Coupling of carbon nanotubes to metallic contacts SO PHYSICAL REVIEW B LA English DT Article AB The modeling of carbon nanotube-metal contacts is important from both basic and applied viewpoints. For many applications, it is important to design contacts such that the transmission is dictated by intrinsic properties of the nanotube rather than by details of the contact. In this paper, we calculate the electron transmission probability from a nanotube to a free-electron metal, which is side contacted. If the metal-nanotube interface is sufficiently ordered, we find that k-vector conservation plays an important role in determining the coupling, with the physics depending on the area of contact, tube diameter, and chirality. The main results of this paper are (i) conductance scales with contact length, a phenomena that has been observed in experiments; (ii) in the case of uniform coupling between metal and nanotube, the threshold value of the metal Fermi wave vector (below which coupling is insignificant) depends on chirality; and (iii) an armchair tube couples better than a zigzag tube to ordered Au/Ag contacts. Disorder and small phase coherence length relax the need for k-vector conservation, thereby making the coupling stronger. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Purdue Univ, Dept Elect & Comp Engn, W Lafayette, IN 47907 USA. RP Anantram, MP (reprint author), NASA, Ames Res Ctr, Mail Stop T27A-1, Moffett Field, CA 94035 USA. EM anant@nas.nasa.gov NR 17 TC 73 Z9 75 U1 0 U2 10 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 2000 VL 61 IS 20 BP 14219 EP 14224 DI 10.1103/PhysRevB.61.14219 PG 6 WC Physics, Condensed Matter SC Physics GA 318LF UT WOS:000087284900114 ER PT J AU Ackerman, AS Toon, OB Stevens, DE Heymsfield, AJ Ramanathan, V Welton, EJ AF Ackerman, AS Toon, OB Stevens, DE Heymsfield, AJ Ramanathan, V Welton, EJ TI Reduction of tropical cloudiness by soot SO SCIENCE LA English DT Article ID MARINE BOUNDARY-LAYER; FRACTIONAL CLOUDINESS; INDIAN-OCEAN; CLOUDS; MODEL; STRATOCUMULUS; ALBEDO; MICROPHYSICS; SCATTERING; AEROSOLS AB Measurements and models show that enhanced aerosol concentrations can augment cloud albedo not only by increasing total droplet cross-sectional area, but also by reducing precipitation and thereby increasing cloud water content and cloud coverage. Aerosol pollution is expected to exert a net cooling influence on the global climate through these conventional mechanisms. Here, we demonstrate an opposite mechanism through which aerosols can reduce cloud cover and thus significantly offset aerosol-induced radiative cooling at the top of the atmosphere on a regional scale. In model simulations, the daytime clearing of trade cumulus is hastened and intensified by solar heating in dark haze las found over much of the northern Indian Ocean during the northeast monsoon). C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Colorado, Boulder, CO 80309 USA. Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94551 USA. Natl Ctr Atmospher Res, Boulder, CO 80301 USA. Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA. Sci Syst & Applicat, Greenbelt, MD 20771 USA. RP Ackerman, AS (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RI Heymsfield, Andrew/E-7340-2011; Welton, Ellsworth/A-8362-2012; Ackerman, Andrew/D-4433-2012 OI Ackerman, Andrew/0000-0003-0254-6253 NR 40 TC 669 Z9 702 U1 15 U2 109 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 12 PY 2000 VL 288 IS 5468 BP 1042 EP 1047 DI 10.1126/science.288.5468.1042 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 313EY UT WOS:000086988400035 ER PT J AU Roos-Serote, M Vasavada, AR Kamp, L Drossart, P Irwin, P Nixon, C Carlson, RW AF Roos-Serote, M Vasavada, AR Kamp, L Drossart, P Irwin, P Nixon, C Carlson, RW TI Proximate humid and dry regions in Jupiter's atmosphere indicate complex local meteorology SO NATURE LA English DT Article ID CLOUD STRUCTURE; WATER-VAPOR; ABUNDANCE; SPECTRA; 5-MU-M AB Models of Jupiter's formation and structure predict that its atmosphere is enriched in oxygen, relative to the Sun, and that consequently water clouds should be present globally near the 5-bar pressure level(1,2). Past attempts to confirm these predictions have led to contradictory results(3-5); in particular, the Galileo probe revealed a very dry atmosphere at the entry site, with no significant clouds at depths exceeding the 2-bar level(6,7). Although the entry site was known to be relatively cloud-free, the contrast between the observed local dryness and the expected global wetness was surprising. Here we analyse near-infrared (around 5 mu m) observations of Jupiter, a spectral region that can reveal the water vapour abundance and vertical cloud structure in the troposphere(8). We find that humid and extremely dry regions exist in close proximity, and that some humid regions are spatially correlated with bright convective clouds extending from the deep water clouds to the visible atmosphere. C1 Observ Astron Lisboa, P-1349018 Lisbon, Portugal. Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Observ Paris, CNRS, UMR 8632, Dept Spatial, F-92915 Meudon, France. Univ Oxford, Clarendon Lab, Atmospher Phys Dept, Oxford OX1 3PU, England. RP Roos-Serote, M (reprint author), Observ Astron Lisboa, P-1349018 Lisbon, Portugal. RI Nixon, Conor/A-8531-2009; OI Nixon, Conor/0000-0001-9540-9121; Irwin, Patrick/0000-0002-6772-384X NR 19 TC 25 Z9 25 U1 1 U2 4 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD MAY 11 PY 2000 VL 405 IS 6783 BP 158 EP 160 DI 10.1038/35012023 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 314WG UT WOS:000087080100042 PM 10821265 ER PT J AU Weth, C Meszaros, P Kallman, T Rees, MJ AF Weth, C Meszaros, P Kallman, T Rees, MJ TI Early X-ray/ultraviolet line signatures of gamma-ray burst progenitors and hypernovae SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : miscellaneous; gamma rays : bursts; stars : mass loss; supernovae : general; ultraviolet : general; X-rays : general ID IRON LINE; AFTERGLOW; REDSHIFT; EMISSION AB We calculate the X-ray/UV spectral line signatures expected from the interaction of a gamma-ray burst afterglow and a dense preburst environment produced by the progenitor. We explore the conditions under which Fe line and edge equivalent widths of similar to 1 keV can arise, and discuss the possibility of gaining information about possible progenitor scenarios using X-ray metal-line spectra in the first few days of a burst. A wind or supernova shell around the burst produces an X-ray absorption line spectrum and later emission lines, while a hypernova funnel model produces mainly emission lines. The Fe K-edge can in some cases be more prominent than the Fe K alpha line. Under simple assumptions for the input continuum luminosity, current reports of observed Fe line luminosities are compatible with an Fe-enriched funnel model, while lower values are expected in shell models. C1 Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16803 USA. Univ Tubingen, Inst Astron & Astrophys, D-72076 Tubingen, Germany. Univ Calif Santa Barbara, Inst Theoret Phys, Santa Barbara, CA 93106 USA. CALTECH, Dept Astron, Pasadena, CA 91125 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England. RP Weth, C (reprint author), Penn State Univ, Dept Astron & Astrophys, 525 Davey Lab, University Pk, PA 16803 USA. NR 26 TC 46 Z9 47 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2000 VL 534 IS 2 BP 581 EP 586 DI 10.1086/308792 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320ZA UT WOS:000087429400006 ER PT J AU Weaver, KA Heckman, TM Dahlem, M AF Weaver, KA Heckman, TM Dahlem, M TI An X-ray minisurvey of nearby edge-on starburst galaxies.. II. The question of metal abundance SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : evolution; galaxies : individual (NGC 253, NGC 3034=M82); galaxies : starburst; intergalactic medium; X-rays : galaxies ID INTRA-CLUSTER MEDIUM; INTRACLUSTER MEDIUM; GALACTIC SUPERWINDS; ELLIPTIC GALAXIES; STAR-FORMATION; EMISSION; M82; ENRICHMENT; NGC-253; DISK AB We have undertaken an X-ray survey of a far-infrared flux-limited sample of seven nearby edge-on starburst galaxies. The data are presented in the first paper of this series by Dahlem, Weaver, & Heckman. Here, we examine the two X-ray-brightest sample members, NGC 253 and M82, in a self-consistent manner, taking account of the spatial distribution of the X-ray emission in choosing our spectral models. Both galaxies require at least three components to model the 0.1-10.0 keV spectrum, but the modeling is by no means unique. There is significant X-ray absorption in the disk of NGC 253. When this is accounted for in spectral fits to the emission between similar to 0.2 and 2.0 keV, we find that multitemperature thermal plasma models with significant underlying soft X-ray absorption are more consistent with the imaging data than single-temperature models with highly subsolar abundances or models with minimal absorption and nonequilibrium thermal ionization conditions, as have been proposed by others. Our three-component models do not require absolute abundances that are inconsistent with solar values or unusually supersolar ratios of the alpha-burning elements with respect to Fe (as claimed previously). We conclude that with current data, the technique of measuring abundances in starburst galaxies via X-ray spectral modeling is highly uncertain. Much improved spatial/spectral resolution and increased sensitivity are required. Based on the pointlike nature of much of the X-ray emission in the PSPC hard-band image of NGC 253, we suggest that a significant fraction of the "extended" X-ray emission in the 3-10 keV band seen along the disk of the galaxy with ASCA and BeppoSAX (Cappi et al.) is composed of discrete sources in the disk, as opposed to purely diffuse, hot gas. If a significant amount of the hard X-ray emission were due to unresolved point sources with weak Fe K alpha emission (e.g., X-ray binaries), this could explain the low Fe abundances of similar to 1/4 solar derived by Cappi et al. for pure thermal models. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. European Space Agcy, European Space Res & Technol Ctr, Dept Space Sci, Div Astrophys, NL-2200 AG Noordwijk, Netherlands. RP Weaver, KA (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. EM kweaver@milkyway.gsfc.nasa.gov NR 47 TC 34 Z9 34 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2000 VL 534 IS 2 BP 684 EP 702 DI 10.1086/308786 PN 1 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320ZA UT WOS:000087429400015 ER PT J AU Nayakshin, S AF Nayakshin, S TI On the X-ray-heated skin of accretion disks SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; line : formation; radiation mechanisms : nonthermal; X-rays : general ID ACTIVE GALACTIC NUCLEI; EMISSION-LINE; BLACK-HOLES; REFLECTION; BINARIES; PROFILES; SPECTRA; CORONA; DISCS; MODEL AB We present a simple analytical formula for the Thomson depth of the X-ray-heated skin of accretion disks valid at any radius and for a broad range of spectral indices of the incident X-rays, accretion rates, and black hole masses. We expect that this formula may find useful applications in studies of geometry of the inner part of accretion flows around compact objects, and in several other astrophysically important problems, such as the recently observed X-ray "Baldwin" effect (i.e., monotonic decrease of the Fe line's equivalent width with the X-ray luminosity of active galactic nuclei [AGNs]), the problem of the missing Lyman edge in AGNs, and line and continuum variability studies in accretion disks around compact objects. We compute the reflected X-ray spectra for several representative cases and show that for hard X-ray spectra and large ionizing fluxes the skin represents a perfect mirror that does not produce any Fe lines or absorption features. At the same time, for soft X-ray spectra or small ionizing fluxes, the skin produces a very strong ionized absorption edge and highly ionized Fe lines that should be observable in the reflected spectra. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Nayakshin, S (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. NR 25 TC 47 Z9 47 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2000 VL 534 IS 2 BP 718 EP 722 DI 10.1086/308801 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320ZA UT WOS:000087429400018 ER PT J AU Ramaty, R Scully, ST Lingenfelter, RE Kozlovsky, B AF Ramaty, R Scully, ST Lingenfelter, RE Kozlovsky, B TI Light-element evolution and cosmic-ray energetics SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic rays; Galaxy : evolution; supernovae : general ID METAL-POOR STARS; EXTRAGALACTIC SUPERNOVA RATES; CHEMICAL EVOLUTION; HALO STARS; BIG-BANG; INTERSTELLAR-MEDIUM; GALACTIC EVOLUTION; ORION COMPLEX; EARLY GALAXY; NUCLEOSYNTHESIS AB Using cosmic-ray energetics as a discriminator, we investigate the viability of evolutionary models for the light elements Li, Be, and B (LiBeB). We find that models in which the cosmic rays are accelerated mainly out of the average interstellar medium which is increasingly metal-poor at early times significantly underpredict the measured Be abundance of the early Galaxy, the possible increase in [O/Fe] with decreasing [Fe/H] indicated by some recent data notwithstanding. On the other hand, if the cosmic-ray metals are accelerated primarily out of supernova ejecta-enriched superbubbles, such that the cosmic-ray source composition as a function of [Fe/H] remains similar to that of the current epoch, the measured Be abundances are consistent with a cosmic-ray acceleration efficiency that is in very good agreement with the current epoch data. This model requires the incorporation of neutrino-produced (11)B. We show that, even though the production histories of the cosmic-ray-produced B and Be and the neutrino-produced (11)B are different, B/Be can remain essentially constant as a function of [Fe/H]. We also find that neither the above cosmic-ray origin models nor a model employing low-energy cosmic rays originating from the supernovae of only very massive progenitors can account for the (6)Li data at values of [Fe/H] below -2. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. Tel Aviv Univ, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. RP Ramaty, R (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. EM ramaty@gsfc.nasa.gov; scully@gsfc.nasa.gov; rlingenfelter@ucsd.edu; benz@wise1.tau.ac.il NR 84 TC 80 Z9 80 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 2000 VL 534 IS 2 BP 747 EP 756 DI 10.1086/308793 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320ZA UT WOS:000087429400021 ER PT J AU Ahlen, SP Greene, NR Loomba, D Mitchell, JW Bower, CR Heinz, RM Mufson, SL Musser, J Pitts, JJ Spiczak, GM Clem, J Guzik, TG Lijowski, M Wefel, JP McKee, S Nutter, S Tomasch, A Beatty, JJ Ficenec, DJ Tobias, S AF Ahlen, SP Greene, NR Loomba, D Mitchell, JW Bower, CR Heinz, RM Mufson, SL Musser, J Pitts, JJ Spiczak, GM Clem, J Guzik, TG Lijowski, M Wefel, JP McKee, S Nutter, S Tomasch, A Beatty, JJ Ficenec, DJ Tobias, S TI Measurement of the isotopic composition of cosmic-ray helium, lithium, beryllium, and boron up to 1700 MeV per atomic mass unit SO ASTROPHYSICAL JOURNAL LA English DT Article DE balloons; cosmic rays; nuclear reactions, nucleosynthesis, abundances ID CROSS-SECTIONS; RELATIVISTIC NUCLEI; CARBON TARGETS; BE-10; AGE; ABUNDANCE; HYDROGEN; PROPAGATION; GALAXY; ENERGY AB We present data from the second flight of the superconducting magnet instrument for light isotopes (SMILI), which took place on 1991 July 24. This instrument was optimized to determine the isotopic composition of He, Li, Be, and B in the Galactic cosmic rays, up to an energy of 2 GeV amu(-1). The abundances of He, Li, and B are found to be consistent with standard models of cosmic-ray propagation. Our measurement of the abundances of the beryllium isotopes suggests an enhancement of the fraction of the isotope Be-10 over that found at low energy. Of 26 beryllium events, nine are found to be Be-10. Monte Carlo calculations based on this observation imply the mean lifetime of cosmic rays to be less than 6 Myr at the 97.5% confidence level. C1 Boston Univ, Dept Phys, Boston, MA 02215 USA. NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. Indiana Univ, Dept Phys, Bloomington, IN 47405 USA. Indiana Univ, Dept Astron, Bloomington, IN 47405 USA. Louisiana State Univ, Dept Phys & Astron, Baton Rouge, LA 70803 USA. Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA. Washington Univ, Dept Phys, St Louis, MO 63130 USA. RP Ahlen, SP (reprint author), Boston Univ, Dept Phys, 590 Commonwealth Ave, Boston, MA 02215 USA. RI Beatty, James/D-9310-2011; McKee, Shawn/B-6435-2012 OI Beatty, James/0000-0003-0481-4952; McKee, Shawn/0000-0002-4551-4502 NR 27 TC 28 Z9 28 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2000 VL 534 IS 2 BP 757 EP 769 DI 10.1086/308762 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320ZA UT WOS:000087429400022 ER PT J AU Palumbo, ME Strazzulla, G Pendleton, YJ Tielens, AGGM AF Palumbo, ME Strazzulla, G Pendleton, YJ Tielens, AGGM TI R-O-C N species produced by ion irradiation of ice mixtures: Comparison with astronomical observations SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : ISM : lines and bands; ISM : clouds; ISM : molecules; line : identification; molecular processes; stars : pre-main-sequence ID MAIN-SEQUENCE STARS; DENSE MOLECULAR CLOUDS; TAURUS DARK CLOUD; INFRARED-SPECTROSCOPY; GRAIN MANTLES; ABSORPTION FEATURES; INTERSTELLAR-MEDIUM; MICRON ABSORPTION; SOLID CO; XCN BAND AB We have investigated the effects induced by ion bombardment of mixtures containing nitrogen-bearing compounds at low temperatures. The results show the formation of a band at 2080 cm(-1) in binary mixtures, NH(3):CH(4) and N(2):CH(4), which we attribute to HCN embedded in the organic residue formed by ion irradiation. In addition to this band, ternary mixtures containing an oxygen-bearing species (i.e., H(2)O) form a compound with a prominent absorption band at about 2165 cm(-1) (4.62 mu m). We ascribe this band to a nitrile compound containing O that is bonded to the organic residue. A detailed comparison of the laboratory results with astronomical data of the 4.62 pm absorption band in protostellar spectra shows good agreement in peak position and profile. Our experimental studies show that N(2), which is a more likely interstellar ice component than NH(3), can be the molecular progenitor of the carrier of the interstellar band. This is an alternative to the pathway by which UV photolysis of NH(3)-containing ices produces the 4.62 mu m band and implies that ion bombardment may well play an important role in the evolution of interstellar ices. Here, we discuss the implications of our studies for the chemical route by which the carrier of the 4.62 mu m band is formed in these laboratory experiments. C1 Osserv Astrofis Catania, I-95125 Catania, Italy. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands. RP Palumbo, ME (reprint author), Osserv Astrofis Catania, Viale A Doria 6, I-95125 Catania, Italy. EM mepalumbo@alpha4.ct.astro.it; gianni@alpha4.ct.astro.it; ypendleton@mail.arc.nasa.gov; tielens@astro.rug.nl NR 48 TC 38 Z9 39 U1 0 U2 3 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 2000 VL 534 IS 2 BP 801 EP 808 DI 10.1086/308760 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320ZA UT WOS:000087429400025 PM 11543516 ER PT J AU Lenters, GT Miller, JA Sommer, JC AF Lenters, GT Miller, JA Sommer, JC TI A heuristic Coulomb collision operator for cylindrical velocity coordinates SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; plasmas; scattering; Sun : flares ID FAST-MODE WAVES; IMPULSIVE SOLAR-FLARES; ELECTRON ACCELERATION; RUNAWAY ELECTRONS; PARTICLE-ACCELERATION AB We consider the effect of Coulomb collisions on an arbitrary distribution of electrons immersed in a thermal fully ionized background distribution. We develop specifically a Coulomb collision operator in cylindrical velocity coordinates, which are the convenient or natural choice for many acceleration processes. We compare this new operator with the standard linearized Coulomb collision operator in spherical velocity coordinates and then apply the cylindrical operator to the problem of electron acceleration in impulsive solar flares. C1 Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. RP Lenters, GT (reprint author), NASA, Goddard Space Flight Ctr, Code 665, Greenbelt, MD 20771 USA. NR 24 TC 0 Z9 0 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2000 VL 534 IS 2 BP 997 EP 1007 DI 10.1086/308766 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320ZA UT WOS:000087429400042 ER PT J AU Bergstrom, D Boezio, M Carlson, P Francke, T Grinstein, S Khalchukov, F Suffert, M Hof, M Kremer, J Menn, W Simon, M Stephens, SA Ambriola, ML Bellotti, R Cafagna, F Ciacio, F Circella, M De Marzo, C Finetti, N Papini, P Piccardi, S Spillantini, P Bartalucci, S Ricci, M Casolino, M De Pascale, MP Morselli, A Picozza, P Sparvoli, R Bonvicini, V 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 Khalchukov, F Suffert, M Hof, M Kremer, J Menn, W Simon, M Stephens, SA Ambriola, ML Bellotti, R Cafagna, F Ciacio, F Circella, M De Marzo, C Finetti, N Papini, P Piccardi, S Spillantini, P Bartalucci, S Ricci, M Casolino, M De Pascale, MP Morselli, A Picozza, P Sparvoli, R Bonvicini, V Schiavon, P Vacchi, A Zampa, N Mitchell, JW Ormes, JF Streitmatter, RE Bravar, U Stochaj, SJ TI First mass-resolved measurement of high-energy cosmic-ray antiprotons SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; balloons; cosmic rays; dark matter; elementary particles ID ATMOSPHERIC DEPTHS; SPECTROMETER; PERFORMANCE; RADIATION; SPECTRUM; PROTON; HELIUM; FLUX AB We report new results for the cosmic-ray antiproton-to-proton ratio from 3 to 50 GeV at the top of the atmosphere. These results represent the first measurements, on an event-by-event basis, of mass-resolved antiprotons above 18 GeV. The results were obtained with the NMSU-WIZARD/CAPRICE98 balloon-borne magnet spectrometer equipped with a gas-RICH (Ring-Imaging Cerenkov) counter and a silicon-tungsten imaging calorimeter. The RICH detector was the first ever flown that is capable of identifying charge-one particles at energies above 5 GeV. The spectrometer was flown on 1998 May 28-29 from Fort Sumner, New Mexico. The measured (p) over bar/p ratio is in agreement with a pure secondary interstellar production. C1 Royal Inst Technol, S-10405 Stockholm, Sweden. Univ Trieste, Dipartimento Fis, I-34147 Trieste, Italy. Sezione INFN Trieste, I-34147 Trieste, Italy. Ctr Rech Nucl, F-67037 Strasbourg, France. Univ Gesamthsch Siegen, D-57068 Siegen, Germany. Tata Inst Fundamental Res, Bombay 400005, Maharashtra, India. Univ Bari, Dipartimento Fis, I-70126 Bari, Italy. Sezione INFN Bari, I-70126 Bari, Italy. Univ Florence, Dipartimento Fis, I-50125 Florence, Italy. Sezione INFN Firenze, I-50125 Florence, Italy. Ist Nazl Fis Nucl, Lab Nazl Frascati, I-00044 Frascati, Italy. Univ Roma Tor Vergata, Dipartimento Fis, I-00133 Rome, Italy. Sezione INFN Roma, I-00133 Rome, Italy. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. New Mexico State Univ, Las Cruces, NM 88003 USA. RP Bergstrom, D (reprint author), Royal Inst Technol, S-10405 Stockholm, Sweden. RI Morselli, Aldo/G-6769-2011; Cafagna, Francesco/A-9299-2010; Vacchi, Andrea/C-1291-2010 OI Morselli, Aldo/0000-0002-7704-9553; Cafagna, Francesco/0000-0002-7450-4784; Vacchi, Andrea/0000-0003-3855-5856 NR 25 TC 16 Z9 16 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2000 VL 534 IS 2 BP L177 EP L180 DI 10.1086/312665 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320ZB UT WOS:000087429500015 ER PT J AU Joffre, M Fischer, P Frieman, J McKay, T Mohr, JJ Nichol, RC Johnston, D Sheldon, E Bernstein, G AF Joffre, M Fischer, P Frieman, J McKay, T Mohr, JJ Nichol, RC Johnston, D Sheldon, E Bernstein, G TI Weak gravitational lensing by the nearby cluster Abell 3667 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : clusters : individual (Abell 3667); gravitational lensing ID DARK-MATTER; GALAXIES; A3667; ARC AB We present two weak lensing reconstructions of the nearby (z(cl) = 0.055) merging cluster Abell 3667, based on observations taken similar to 1 yr apart under different seeing conditions. This is the lowest redshift cluster with a weak lensing mass reconstruction to date. The reproducibility of features in the two mass maps demonstrates that weak lensing studies of low-redshift clusters are feasible. These data constitute the first results from an Xray luminosity-selected weak lensing survey of 19 low-redshift (z < 0.1) southern clusters. C1 Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. NASA, Fermilab Astrophys Ctr, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA. Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA. Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. RP Joffre, M (reprint author), Univ Chicago, Dept Astron & Astrophys, 5640 S Ellis Ave, Chicago, IL 60637 USA. RI McKay, Timothy/C-1501-2009 OI McKay, Timothy/0000-0001-9036-6150 NR 20 TC 28 Z9 28 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2000 VL 534 IS 2 BP L131 EP L134 DI 10.1086/312681 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320ZB UT WOS:000087429500004 ER PT J AU Ramaty, R Tatischeff, V Thibaud, JP Kozlovsky, B Mandzhavidze, N AF Ramaty, R Tatischeff, V Thibaud, JP Kozlovsky, B Mandzhavidze, N TI (6)Li from solar flares SO ASTROPHYSICAL JOURNAL LA English DT Article DE nuclear reactions, nucleosynthesis, abundances; solar wind; Sun : abundances; Sun : flares ID GAMMA-RAY SPECTROSCOPY; LITHIUM ABUNDANCE; COSMIC-RAYS; PARTICLES; LIGHT; HE-3; SUN AB By introducing a hitherto ignored (6)Li producing process, due to:accelerated (3)He reactions with (4)He, we show that accelerated particle interactions in solar flares produce much more (6)Li than (7)Li. By normalizing our calculations to gamma-ray data, we demonstrate that the (6)Li produced in solar hares, combined with photospheric (7)Li, can account for the recently determined solar wind lithium isotopic ratio, obtained from measurements in lunar soil, provided that the bulk of the flare-produced lithium is evacuated by the solar wind. Further research in this area could provide unique information on a variety of problems, including solar atmospheric transport and mixing, solar convection and the lithium depletion issue, and solar wind and solar particle acceleration. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. IN2P3, CNRS, Ctr Spectrometrie Nucl & Spectrometrie Masse, F-91495 Orsay, France. Tel Aviv Univ, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. USRA, Greenbelt, MD USA. RP Ramaty, R (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. EM ramaty@gsfc.nasa.gov; tatische@csnsm.in2p3.fr; benz@wise1.tau.ac.il; natalie@pair.gsfc.nasa.gov NR 29 TC 13 Z9 13 U1 1 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 2000 VL 534 IS 2 BP L207 EP L210 DI 10.1086/312671 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320ZB UT WOS:000087429500023 ER PT J AU White, SM Thomas, RJ Brosius, JW Kundu, MR AF White, SM Thomas, RJ Brosius, JW Kundu, MR TI The absolute abundance of iron in the solar corona SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic data; Sun : abundances; Sun : atmosphere; Sun : corona; Sun : radio radiation; X-rays ID ENERGETIC PARTICLES; CALCIUM ABUNDANCE; SPECTRA; EMISSION; SUN AB We present a measurement of the abundance of Fe relative to H in the solar corona using a technique that differs from previous spectroscopic and solar wind measurements. Our method combines EUV line data from the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory with thermal bremsstrahlung radio data from the VLA. The coronal Fe abundance is derived by equating the thermal bremsstrahlung radio emission calculated from the EUV Fe line data to that observed with the VLA, treating the Fe/H abundance as the sole unknown. We apply this technique to a compact cool active region and find Fe/H = 1.56 x 10(-4), or about 4 times its value in the solar photosphere. Uncertainties,in the CDS radiometric calibration, the VLA intensity measurements, the atomic parameters, and the assumptions made in the spectral analysis yield net uncertainties of similar to 20%. This result implies that low first ionization potential elements such as Fe are enhanced in the solar corona relative to photospheric values. C1 Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Raytheon ITSS, Lanham, MD 20771 USA. RP White, SM (reprint author), Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NR 24 TC 25 Z9 25 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2000 VL 534 IS 2 BP L203 EP L206 DI 10.1086/312673 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320ZB UT WOS:000087429500022 ER PT J AU Wong, AS Lee, AYT Yung, YL Ajello, JM AF Wong, AS Lee, AYT Yung, YL Ajello, JM TI Jupiter: Aerosol chemistry in the polar atmosphere SO ASTROPHYSICAL JOURNAL LA English DT Article DE planets and satellites : individual (Jupiter) ID HUBBLE-SPACE-TELESCOPE; SPECTRA; AURORA; PHOTOCHEMISTRY; ACETYLENE; URANUS; FLAMES AB Aromatic compounds have been considered a likely candidate for enhanced aerosol formation in the polar region of Jupiter. We develop a new chemical model for aromatic compounds in the Jovian auroral thermosphere/ ionosphere. The model is based on a previous model for hydrocarbon chemistry in the Jovian atmosphere and is constrained by observations from Voyager, Galileo, and the infrared Space Observatory. Precipitation of energetic electrons provides the major energy source for the production of benzene and other heavier aromatic hydrocarbons. The maximum mixing ratio of benzene in the polar model is 2 x 10(-9), a value that can be compared with the observed value of (2(-1)(+2)) x 10(-9) in the north polar auroral region. Sufficient quantities of the higher ring species are produced so that their saturated Vapor pressures are exceeded. Condensation of these molecules is expected to lead to aerosol formation. C1 CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wong, AS (reprint author), CALTECH, Div Geol & Planetary Sci, 150-21, Pasadena, CA 91125 USA. NR 22 TC 41 Z9 41 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2000 VL 534 IS 2 BP L215 EP L217 DI 10.1086/312675 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320ZB UT WOS:000087429500025 ER PT J AU Pelligra, R AF Pelligra, R TI Protection for human subjects in medical research SO JAMA-JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION LA English DT Letter C1 NASA, Moffett Field, CA 94035 USA. RP Pelligra, R (reprint author), NASA, Moffett Field, CA 94035 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU AMER MEDICAL ASSOC PI CHICAGO PA 515 N STATE ST, CHICAGO, IL 60610 USA SN 0098-7484 J9 JAMA-J AM MED ASSOC JI JAMA-J. Am. Med. Assoc. PD MAY 10 PY 2000 VL 283 IS 18 BP 2387 EP 2388 PG 2 WC Medicine, General & Internal SC General & Internal Medicine GA 310CD UT WOS:000086808200020 PM 10815072 ER PT J AU Freund, F AF Freund, F TI Time-resolved study of charge generation and propagation in igneous rocks SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Review ID NOMINALLY ANHYDROUS MINERALS; MAGNETIC-FIELD MEASUREMENTS; LOMA-PRIETA EARTHQUAKE; SINGLE-CRYSTAL MGO; ELECTRICAL-CONDUCTIVITY; MAGNESIUM-OXIDE; LOWER CRUST; ELECTROMAGNETIC-RADIATION; FRACTURE; EMISSION AB Electrical resistivity changes, ground potentials, electromagnetic (EM), and luminous signals preceding or accompanying earthquakes have been reported many times, in addition to ground uplift and tilt and other parameters. However, no concept exists that would tie these diverse phenomena together into a physically coherent model. Using low- to medium-velocity impacts to measure electrical signals with microsecond time resolution, it is observed that when gabbro and diorite cores are impacted at relatively low velocities, approximate to 100 m/s, highly mobile charge carriers are generated in a small volume near the impact point. They spread through the rocks, causing electric potentials exceeding +400 mV, EM, and light emission. As the charge cloud spreads, the rock becomes momentarily conductive. When a granite block: is impacted at higher velocity, approximate to 1.5 km/s, the propagation of the P and S waves is registered through the transient piezoelectric response of quartz. After the sound waves have passed, the surface of the granite block becomes positively charged, suggesting the same charge carriers as observed during the low velocity impact experiments, expanding from within the bulk. During the next 2-3 ms the surface potential oscillates, indicating pulses of electrons injected from ground and contact electrodes. The observations are consistent with positive holes, e.g., defect electrons in the O2- sublattice, traveling via the O 2p-dominated valence band of the silicate minerals. The positive holes propagate as charge clouds rather than as classical EM waves. Before activation, they lay dormant in form of electrically inactive positive hole pairs, PHP, chemically equivalent to peroxy links, O3X/(OO)\XO3 with X=Si4+, Al3+, etc. PHPs are introduced into the minerals by way of hydroxyl, O,X-OH, which all nominally anhydrous minerals incorporate when crystallizing in H2O-laden environments. The fact that positive holes can be activated by low-energy impacts, and their attendant sound waves, suggests that they can also be activated in the crust by microfractures during the dilatancy phase. Depending on where in the stressed rock volume the charge carriers are activated, they will form rapidly moving or fluctuating charge clouds that can account for earthquake-related electrical signals and EM emission. Wherever such charge clouds intersect the surface, high fields are expected, causing electric discharges and earthquake lights. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. San Jose State Univ, SETI Inst, San Jose, CA 95192 USA. San Jose State Univ, Dept Phys, San Jose, CA 95192 USA. RP NASA, Ames Res Ctr, MS 239-15, Moffett Field, CA 94035 USA. EM freund@mail.arc.nasa.gov NR 110 TC 89 Z9 101 U1 4 U2 14 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 2000 VL 105 IS B5 BP 11001 EP 11019 DI 10.1029/1999JB900423 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 313YM UT WOS:000087027400014 ER PT J AU Cerf, NJ AF Cerf, NJ TI Pauli cloning of a quantum bit SO PHYSICAL REVIEW LETTERS LA English DT Article AB A family of asymmetric quantum cloning machines is introduced that produce two approximate copies 8 MAY 2000 of a single quantum bit, each copy emerging from a Pauli channel. A no-cloning inequality is derived describing the balance between the quality of the copies. The Pauli cloning machine is also shown to put a limit on the quantum capacity of Pauli channels. C1 Free Univ Brussels, Ecole Polytech, B-1050 Brussels, Belgium. CALTECH, Jet Prop Lab, Informat & Comp Technol Res Sect, Pasadena, CA 91109 USA. CALTECH, WK Kellogg Radiat Lab, Pasadena, CA 91125 USA. RP Cerf, NJ (reprint author), Free Univ Brussels, Ecole Polytech, CP 165, B-1050 Brussels, Belgium. NR 10 TC 177 Z9 181 U1 0 U2 10 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 8 PY 2000 VL 84 IS 19 BP 4497 EP 4500 DI 10.1103/PhysRevLett.84.4497 PG 4 WC Physics, Multidisciplinary SC Physics GA 312KC UT WOS:000086941600061 ER PT J AU Ostro, SJ Hudson, RS Nolan, MC Margot, JL Scheeres, DJ Campbell, DB Magri, C Giorgini, JD Yeomans, DK AF Ostro, SJ Hudson, RS Nolan, MC Margot, JL Scheeres, DJ Campbell, DB Magri, C Giorgini, JD Yeomans, DK TI Radar observations of asteroid 216 Kleopatra SO SCIENCE LA English DT Article ID SHAPE; COLLISIONS; TOUTATIS AB Radar observations of the main-belt, M-class asteroid 216 Kleopatra reveal a dumbbell-shaped object with overall dimensions of 217 kilometers by 94 kilometers by 81 kilometers (+/-25%). The asteroid's surface properties are consistent with a regolith having a metallic composition and a porosity comparable to that of Lunar soil. Kleopatra's shape is probably the outcome of an exotic sequence of collisional events, and much of its interior may have an unconsolidated rubble-pile structure. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Washington State Univ, Sch Elect Engn & Comp Sci, Pullman, WA 99164 USA. Arecibo Observ, Arecibo, PR 00612 USA. Univ Michigan, Dept Aerosp Engn, Ann Arbor, MI 48109 USA. Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. Univ Maine, Farmington, ME 04938 USA. RP Ostro, SJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Margot, Jean-Luc/A-6154-2012; Nolan, Michael/H-4980-2012 OI Margot, Jean-Luc/0000-0001-9798-1797; Nolan, Michael/0000-0001-8316-0680 NR 28 TC 112 Z9 113 U1 1 U2 6 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD MAY 5 PY 2000 VL 288 IS 5467 BP 836 EP 839 DI 10.1126/science.288.5467.836 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 311DN UT WOS:000086869600030 ER PT J AU Meibom, A Desch, SJ Krot, AN Cuzzi, JN Petaev, MI Wilson, L Keil, K AF Meibom, A Desch, SJ Krot, AN Cuzzi, JN Petaev, MI Wilson, L Keil, K TI Large-scale thermal events in the solar nebula: Evidence from Fe,Ni metal grains in primitive meteorites SO SCIENCE LA English DT Article ID ACCRETION DISKS; CARBONACEOUS CHONDRITES; TEMPERATURE; HISTORY AB Chemical zoning patterns in some iron, nickel metal grains from CH carbonaceous chondrites imply formation at temperatures from 1370 to 1270 kelvin by condensation from a solar nebular gas cooling at a rare of similar to 0.2 kelvin per hour. This cooling rate requires a Large-scale thermal event in the nebula, in contrast to the localized, transient heating events inferred for chondrule formation. In our model, mass accretion through the protoplanetary disk caused Large-scale evaporation of precursor dust near its midplane inside of a few astronomical units. Gas convectively moved from the midplane to cooler regions above it, and the metal grains condensed in these parcels of rising gas. C1 Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Lancaster, Inst Environm & Nat Sci, Dept Environm Sci, Lancaster LA1 4YQ, England. Univ Hawaii Manoa, Hawaii Ctr Volcanol, Honolulu, HI 96822 USA. RP Meibom, A (reprint author), Stanford Univ, Dept Geol & Environm Sci, Bldg 320,Lomita Mall, Stanford, CA 94305 USA. NR 27 TC 56 Z9 57 U1 1 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 5 PY 2000 VL 288 IS 5467 BP 839 EP 841 DI 10.1126/science.288.5467.839 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 311DN UT WOS:000086869600031 ER PT J AU Dyall, KG AF Dyall, KG TI Bond dissociation energies of the tungsten fluorides and their singly charged ions: A density functional survey SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID COLLISIONAL IONIZATION; ELECTRON-AFFINITY; THERMOCHEMISTRY; SPECTROSCOPY; HEXAFLUORIDE; MODEL AB The dissociation of WF6 and the related singly charged cations and anions into the lower fluorides and fluorine atoms has been investigated theoretically using density functional theory (B3LYP) and relativistic effective core potentials, with estimates of spin-orbit effects included using a simple model. The inclusion of spinorbit effects is essential for a correct description of the thermochemistry. The total atomization energy of the neutral and anionic WF6 is reproduced to within 25 kcal/mol, but comparison of individual bond dissociation energies with available experimental data shows discrepancies of up to 10 kcal/mol. The results are nevertheless useful to help resolve discrepancies in experimental data and provide estimates of missing data. C1 NASA, Ames Res Ctr, Computat Chem Branch, Moffett Field, CA 94035 USA. RP Dyall, KG (reprint author), NASA, Ames Res Ctr, Computat Chem Branch, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 19 TC 20 Z9 20 U1 0 U2 10 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 MAY 4 PY 2000 VL 104 IS 17 BP 4077 EP 4083 DI 10.1021/jp994348w PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 311EY UT WOS:000086872800030 ER PT J AU Kniffen, DA AF Kniffen, DA TI Instrument's ability to do the job is NASA's priority SO NATURE LA English DT Letter C1 NASA, Off Space Sci, Res Program Management Div, Washington, DC 20546 USA. RP Kniffen, DA (reprint author), NASA, Off Space Sci, Res Program Management Div, Washington, DC 20546 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD MAY 4 PY 2000 VL 405 IS 6782 BP 14 EP 14 DI 10.1038/35011154 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 311TK UT WOS:000086901600018 ER PT J AU Nesterov, VN Deng, X Timofeeva, TV Antipin, MY Clark, RD Frazier, DO Penn, B AF Nesterov, VN Deng, X Timofeeva, TV Antipin, MY Clark, RD Frazier, DO Penn, B TI Structural characterization of monomers for non-linear optical polymers. X-ray analysis and molecular mechanics calculations of 2-(4-methacryloxy-3-methoxyphenyl)-1,1-dicyanoethylene, 2-(3-methacryloxy-4-methoxyphenyl)-1,1-dicyanoethylene, and 2-(2-methacryloxy-3-methoxyphenyl)-1,1-dicyanoethylene SO JOURNAL OF MOLECULAR STRUCTURE LA English DT Article DE non-linear optical polymers; molecular mechanics calculations; X-ray analysis; dicyanovinylbenzene derivatives ID CRYSTAL-STRUCTURES; POLARIZABILITIES; DERIVATIVES; DICYANOVINYLBENZENE AB The results of molecular mechanics calculations, hyperpolarizabilities calculations, synthesis, and X-ray analysis of three monomers for non-linear optical polymers are presented. All monomers are derivatives of dicyanovinylbenzene with methoxy and methacryloxy substituents in different positions (full isomers): 2-(4-methacryloxy-3-methoxyphenyl)-1,1-dicyanoethylene 6a, 2-(3-methacryloxy-4-methoxyphenyl)-1,1-dicyanoethylene 6b, and 2-(2-methacryloxy-3-methoxyphenyl)-1,1-dicyanoethylene 6c. On the basis of structural results for molecules 6a-c and calculations of molecular hyperpolarizability, monomer 6a was found to be the most prospective candidate for NLO polymer preparation. (C) 2000 Elsevier Science B.V. All rights reserved. C1 New Mexico Highlands Univ, Dept Phys Sci, Las Vegas, NM 87701 USA. Russian Acad Sci, Inst Organoelement Cpds, Moscow, Russia. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Timofeeva, TV (reprint author), New Mexico Highlands Univ, Dept Phys Sci, Las Vegas, NM 87701 USA. NR 19 TC 3 Z9 3 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-2860 J9 J MOL STRUCT JI J. Mol. Struct. PD MAY 2 PY 2000 VL 523 BP 309 EP 318 DI 10.1016/S0022-2860(99)00417-2 PG 10 WC Chemistry, Physical SC Chemistry GA 307WY UT WOS:000086678200029 ER PT J AU Powell, KA Mallasch, PG Obuchowski, NA Kerczewski, RJ Ganobcik, SN Cardenosa, G Chilcote, W AF Powell, KA Mallasch, PG Obuchowski, NA Kerczewski, RJ Ganobcik, SN Cardenosa, G Chilcote, W TI Clinical evaluation of wavelet-compressed digitized screen-film mammography SO ACADEMIC RADIOLOGY LA English DT Article DE breast radiography, comparative studies; diagnostic radiology, observer performance; radiography, digital; receiver operating characteristic curve (ROC) ID DIAGNOSTIC-TESTS; ROC CURVE; EQUIVALENCE AB Rationale and Objectives. The authors compared diagnostic accuracy and callback rates with conventional screen-film mammograms and wavelet-compressed digitized images. Materials and Methods. Sixty sets of mammograms (four views per case) were digitized at a spatial resolution of 100 mu m. The images were wavelet compressed to a mean compression ratio of 8:1 and reviewed by three mammographers. Five regions were evaluated in each breast. Suspicion of malignancy was graded on a scale of 0% to 100%, and receiver operating characteristic (ROC) analysis was performed. Callback rates were calculated by using the American College of Radiology's Breast Imaging Reporting and Data System lexicon scale. Results. The mean diagnostic accuracy with compressed and conventional images was 0.832 and 0.860, respectively. The upper 95% confidence bound for the difference in ROC areas was 0.061. The mean false-positive rate at a fixed sensitivity of 0.90 was 0.041 for compressed images and 0.059 for conventional images. The mean callback rates for normal, benign, and malignant regions were 0.023, 0.305, and 0.677, respectively, for compressed images and 0.036, 0.447, and 0.750, respectively, for conventional images. The upper 95% confidence bound for the (absolute) differences in callback rates was 0.012 for normal regions, 0.163 for benign regions, and 0.138 for malignant regions. Conclusion. Diagnostic accuracies were equivalent for both compressed and conventional images. The mean false-positive rate at fixed sensitivity was much better with the compressed images. However, the callback rates for malignant lesions were lower when the compressed images were used. C1 Cleveland Clin Fdn, Agnes Christine Roberts Breast Imaging Lab, Lerner Res Inst, Dept Biomed Engn ND20, Cleveland, OH 44195 USA. Cleveland Clin Fdn, Dept Biostat & Epidemiol, Cleveland, OH 44195 USA. Cleveland Clin Fdn, Div Radiol, Cleveland, OH 44195 USA. NASA, Glenn Res Ctr, Cleveland, OH USA. RP Powell, KA (reprint author), Cleveland Clin Fdn, Agnes Christine Roberts Breast Imaging Lab, Lerner Res Inst, Dept Biomed Engn ND20, 9500 Euclid Ave, Cleveland, OH 44195 USA. NR 19 TC 5 Z9 5 U1 0 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 1076-6332 J9 ACAD RADIOL JI Acad. Radiol. PD MAY PY 2000 VL 7 IS 5 BP 311 EP 316 DI 10.1016/S1076-6332(00)80004-5 PG 6 WC Radiology, Nuclear Medicine & Medical Imaging SC Radiology, Nuclear Medicine & Medical Imaging GA 309UW UT WOS:000086788500002 PM 10803610 ER PT J AU Jenkins, JM Doyle, LR Deeg, HJ AF Jenkins, JM Doyle, LR Deeg, HJ TI Ground-based photometric detection of extrasolar planets SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT International-Academy-of-Astronautics SETI Review Meeting of the 48th Congress of the International-Astronautical-Federation CY 1997 CL TURIN, ITALY SP Int Acad Astronaut, Int Astronaut Federat ID BINARY-SYSTEMS; CM-DRACONIS; TERRESTRIAL; DETECTABILITY; COMPANION; STARS AB The discovery of terrestrial-sized extrasolar planets around main-sequences stars is currently possible from the ground for several sub-solar, small-radii eclipsing binary systems. Terrestrial planets in these systems should form in the binary orbital plane, and are likely to have periods significantly smaller than those of the terrestrial planets in the Solar System, and hence, should be more easily detectable. Our observations of the CM Draconis system indicate that such detections are indeed possible, especially when the photometric data (differential light curve) can be correlated with possible planetary orbital models of the quasi-periodic signal expected (i.e. a matched-filter implementation). The importance of the discovery of the first habitable planets, and Follow-up observations for the detection of exobiology are outlined. In addition, non-transiting jovian-mass planets in such systems can also be detected by precisely timing the binary eclipse minima. Our preliminary observations of ten such systems have demonstrated the feasibility of this detection method. Over two hundred such systems could be surveyed for jovian-mass planets, providing a statistically meaningful sample for understanding the formation of giant planets around close double stars, thus complimenting our main objective: the detection of habitable-sized planets. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. RP Jenkins, JM (reprint author), NASA, Ames Res Ctr, SETI Inst, MS 245-3, Moffett Field, CA 94035 USA. NR 31 TC 2 Z9 2 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAY-JUN PY 2000 VL 46 IS 10-12 BP 693 EP 699 DI 10.1016/S0094-5765(00)00033-3 PG 7 WC Engineering, Aerospace SC Engineering GA 341HU UT WOS:000088585600013 ER PT J AU Israelsson, UE Lee, MC AF Israelsson, UE Lee, MC TI Getting down to the fundamentals SO AEROSPACE AMERICA LA English DT Article C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Israelsson, UE (reprint author), Jet Prop Lab, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD MAY PY 2000 VL 38 IS 5 BP 30 EP 33 PG 4 WC Engineering, Aerospace SC Engineering GA 316EV UT WOS:000087155400008 ER PT J AU Yang, Z Sun, CT Wang, J AF Yang, Z Sun, CT Wang, J TI Fracture mode separation for delamination in platelike composite structures SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA/ASME/ASCE/AHS/ASC 39th Structures, Structural Dynamics, and Materials Conference CY APR 20-23, 1998 CL LONG BEACH, CALIFORNIA SP Amer Inst Aeronaut & Astronaut, ASME, ASCE, AHS, ASC ID ENERGY-RELEASE RATES; DISSIMILAR ANISOTROPIC MEDIA; STRESS INTENSITY FACTORS; 2 ORTHOTROPIC SOLIDS; INTERFACIAL CRACKS; STRAIN; BIMATERIAL; SINGULARITIES AB A computationally efficient approach combining a plate crack-tip element model and a mixed-mode separation technique was developed to calculate mode mixities and stress intensity factors for delamination in platelike composite structures. The crack-tip element was based on classical plate theory, assuming the delamination surfaces to be traction free. Fracture mode separation was achieved by equating the total strain energy release rate from classical plate theory with that from the three-dimensional near-tip solution, along with two supplementary finite element analyses for special loadings. Using this approach, the separation of fracture modes under any other load combinations can easily be carried out. Numerical results showed that the present method gives good evaluations of the mixed-mode stress intensity factors. C1 Purdue Univ, Sch Aeronaut & Astronaut, W Lafayette, IN 47907 USA. NASA, Langley Res Ctr, Struct Div, Hampton, VA 23681 USA. RP Yang, Z (reprint author), Purdue Univ, Sch Aeronaut & Astronaut, W Lafayette, IN 47907 USA. NR 32 TC 6 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 2000 VL 38 IS 5 BP 868 EP 874 DI 10.2514/2.1041 PG 7 WC Engineering, Aerospace SC Engineering GA 311UD UT WOS:000086903300015 ER PT J AU Murad, E Bishop, JL AF Murad, E Bishop, JL TI The infrared spectrum of synthetic akaganeite, beta-FeOOH SO AMERICAN MINERALOGIST LA English DT Article ID SPECTROSCOPY; HYDROLYSIS; MOSSBAUER; PRODUCTS AB Fourier-transform infrared spectra of a synthetic akaganeite, beta-FeOOH, were acquired in transmittance, attenuated total reflectance (ATR) and diffuse reflectance. The transmittance spectra showed a distinct dependence on the mode of sample preparation: measurements taken on pellets prepared by pressing the sample with alkali halides (KBr or CsI) displayed bands at 1096, 1050, and 698 cm(-1) that were not observed in spectra of the neat material and must therefore be considered artifacts. Variations in the sampling environment (e.g., water and/or organic volatiles) were also observed to exert a noticeable influence on the development of the IR spectra. Infrared bands due to akaganeite were found at 3480 + 3390 (doublet), 1630, 850 + 820 (doublet), 650, 490, and similar to 420 cm(-1). Diffuse reflectance spectra dominated by volume scattering (loose), diffuse reflectance spectra comprised of both volume and surface scattering (compacted), ATR spectra (surface only), and transmittance spectra (absorbance only, inverse of ATR) showed compatible trends for the akaganeite features both above and below similar to 1000 cm(-1). This indicates that the multiple akaganeite measurements are consistent and confirms the band assignments. C1 Bayer Geol Landesamt, D-95615 Marktredwitz, Germany. NASA, Ames Res Ctr, Search Extraterr Intelligence Inst, Moffett Field, CA 94035 USA. RP Murad, E (reprint author), Bayer Geol Landesamt, Leopoldstr 30, D-95615 Marktredwitz, Germany. NR 31 TC 57 Z9 57 U1 1 U2 15 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 2000 VL 85 IS 5-6 BP 716 EP 721 PG 6 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA 313GV UT WOS:000086992700007 ER PT J AU Norfleet, WT AF Norfleet, WT TI Anesthetic concerns of spaceflight SO ANESTHESIOLOGY LA English DT Editorial Material DE airway management; immersion; microgravity; space craft ID CARDIAC-ARREST C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Texas, Med Branch, Houston, TX 77058 USA. RP Norfleet, WT (reprint author), NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 9 TC 22 Z9 22 U1 0 U2 0 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0003-3022 J9 ANESTHESIOLOGY JI Anesthesiology PD MAY PY 2000 VL 92 IS 5 BP 1219 EP 1222 DI 10.1097/00000542-200005000-00006 PG 4 WC Anesthesiology SC Anesthesiology GA 311CK UT WOS:000086867100002 PM 10781263 ER PT J AU Cerf, NJ Grover, LK Williams, CP AF Cerf, NJ Grover, LK Williams, CP TI Nested quantum search and NP-hard problems SO APPLICABLE ALGEBRA IN ENGINEERING COMMUNICATION AND COMPUTING LA English DT Article DE quantum computation; quantum algorithms; combinatorial search problems; NP-hard problems ID COMPUTERS AB A quantum algorithm is known that solves an unstructured search problem in a number of iterations of order root d, where d is the dimension of the search space, whereas any classical algorithm necessarily scales as O (d). It is shown here that an improved quantum search algorithm can be devised that exploits the structure of a tree search problem by nesting this standard search algorithm, The number of iterations required to find the solution of an average instance of a constraint satisfaction problem scales as root d(alpha), with a constant alpha < 1 depending on the nesting depth and the problem considered. When applying a single nesting level to a problem with constraints of size 2 such as the graph coloring problem, this constant ac is estimated to be around 0.62 for average instances of maximum difficulty. This corresponds to a square-root speedup over a classical nested search algorithm, of which our presented algorithm is the quantum counterpart. C1 Free Univ Brussels, Ecole Polytech, B-1050 Brussels, Belgium. CALTECH, Jet Prop Lab, Quantum Comp Technol Grp, Sect 367, Pasadena, CA 91109 USA. Bell Labs 3C404A, Murray Hill, NJ 07974 USA. RP Cerf, NJ (reprint author), Free Univ Brussels, Ecole Polytech, CP 165, B-1050 Brussels, Belgium. NR 24 TC 4 Z9 4 U1 0 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0938-1279 J9 APPL ALGEBR ENG COMM JI Appl. Algebr. Eng. Commun. Comput. PD MAY PY 2000 VL 10 IS 4-5 BP 311 EP 338 DI 10.1007/s002000050134 PG 28 WC Computer Science, Interdisciplinary Applications; Computer Science, Theory & Methods; Mathematics, Applied SC Computer Science; Mathematics GA 321RL UT WOS:000087468400006 ER PT J AU Mouroulis, P Green, RO Chrien, TG AF Mouroulis, P Green, RO Chrien, TG TI Design of pushbroom imaging spectrometers for optimum recovery of spectroscopic and spatial information SO APPLIED OPTICS LA English DT Article ID MODULATION TRANSFER-FUNCTION AB A modulation transfer function-based optimization method is described that generates optimal spectral and spatial uniformity of response from compact pushbroom imaging spectrometer designs. Such uniformity is essential for extracting accurate spectroscopic information from a pushbroom imaging spectrometer for Earth-observing remote sensing applications. Two simple and compact spectrometer design examples are described that satisfy stringent uniformity specifications. (C) 2000 Optical Society of America. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Mouroulis, P (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM pantazis.mouroulis@jpl.nasa.gov NR 18 TC 145 Z9 153 U1 3 U2 16 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 2000 VL 39 IS 13 BP 2210 EP 2220 DI 10.1364/AO.39.002210 PG 11 WC Optics SC Optics GA 306JJ UT WOS:000086593300026 PM 18345127 ER PT J AU Tanner, SP Street, KW AF Tanner, SP Street, KW TI Solid-phase luminescence of several rare earth ions on ion-exchange films SO APPLIED SPECTROSCOPY LA English DT Article DE luminescence; ion-exchange; lanthanides ID NATURAL-WATERS; TRACE AMOUNTS; SPECTROFLUOROMETRY; ALUMINUM; BERYLLIUM; TUNGSTEN AB The development acid characterization of a novel ion-exchange film for solid-phase fluorometry and phosphorimetry is reported. This new cation-exchange material is suitable for spectroscopic applications in the ultraviolet and visible regions. It is advantageous because it, as a single entity, is easily recovered from solution and mounted in the spectrofluorometers. After preconcentration on the film, the luminescence intensity of lanthanide ions is several orders of magnitude greater than that of the corresponding solution, depending on the volume of solution and the amount of film. This procedure allows emission spectral measurements and determination of lanthanide ions at solution concentrations of <5 mu g/L. The film may he stored for subsequent reuse or as a permanent record of the analysis. The major drawback to the use of the film is slow uptake of analyte due to diffusion limitations. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Univ W Florida, Dept Chem, Pensacola, FL 32514 USA. RP Street, KW (reprint author), NASA, Glenn Res Ctr, MS 23-2,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 23 TC 5 Z9 5 U1 1 U2 1 PU SOC APPLIED SPECTROSCOPY PI FREDERICK PA 201B BROADWAY ST, FREDERICK, MD 21701 USA SN 0003-7028 J9 APPL SPECTROSC JI Appl. Spectrosc. PD MAY PY 2000 VL 54 IS 5 BP 669 EP 675 DI 10.1366/0003702001950148 PG 7 WC Instruments & Instrumentation; Spectroscopy SC Instruments & Instrumentation; Spectroscopy GA 323RE UT WOS:000087578100009 ER PT J AU Conley, AH Holland, EA Seastedt, TR Parton, WJ AF Conley, AH Holland, EA Seastedt, TR Parton, WJ TI Simulation of carbon and nitrogen cycling in on alpine tundra SO ARCTIC ANTARCTIC AND ALPINE RESEARCH LA English DT Article ID NIWOT RIDGE; TERRESTRIAL ECOSYSTEMS; NUTRIENT AVAILABILITY; ARCTIC TUNDRA; RESPONSES; CLIMATE; COMMUNITIES; COLORADO; SOIL; DYNAMICS AB Simulations of an alpine tundra ecosystem using the CENTURY ecosystem model were conducted to test model descriptions of carbon and nitrogen cycling and to explore the alpine ecosystem response to physical and chemical components of global change. The parameterization of the alpine tundra for CENTURY was updated to reflect current knowledge of the sire, and sensitivity analyses were conducted. Verification of results from a 6-yr fertilization experiment in the alpine tested the predictive capabilities of the parameterization. Simulations with increased winter precipitation and with the climate predicted under doubled atmospheric carbon dioxide concentrations were then conducted. Modifications to the parameterization necessary to describe carbon and nitrogen cycling included decreasing the C:N ratios of plant tissues, increasing the amount of nitrogen retranslocated at the end of the growingr season, extending the length of the growing season, and lowering the rate of decomposition. The updated parameterization requires 30% greater than observed inputs of net primary productivity to simulate observed levels of total soil carbon suggesting that soil carbon sequestration is not well represented in the model. Carbon and nitrogen cycling showed greatest sensitivity to the length of the growing season and to the temperature regulation of decomposition. Simulation of the nitrogen fertilization experiment resulted in 11% greater productivity than observed empirically, a reasonable verification of the updated parameterization. The major impact from increasing winter precipitation was a 30% increase in the amount of nitrogen in stream flow. Simulation with the climate predicted for a doubling of current carbon dioxide levels reduced production 10% while total soil carbon remained constant. This response was largely controlled by reduced soil moisture during the growing season. C1 Univ Colorado, Dept Environm Populat & Organism Biol, Boulder, CO 80309 USA. Natl Ctr Atmospher Res, Div Atmospher Chem, Boulder, CO 80303 USA. Univ Colorado, Inst Arctic & Alpine Res, Boulder, CO 80309 USA. Univ Colorado, Nat Resource Ecol Lab, Boulder, CO 80309 USA. RP Conley, AH (reprint author), NASA, Goddard Space Flight Ctr, SSAI, Code 923, Greenbelt, MD 20771 USA. NR 41 TC 6 Z9 6 U1 2 U2 14 PU INST ARCTIC ALPINE RES PI BOULDER PA UNIV COLORADO, BOULDER, CO 80309 USA SN 1523-0430 J9 ARCT ANTARCT ALP RES JI Arct. Antarct. Alp. Res. PD MAY PY 2000 VL 32 IS 2 BP 147 EP 154 DI 10.2307/1552446 PG 8 WC Environmental Sciences; Geography, Physical SC Environmental Sciences & Ecology; Physical Geography GA 322GN UT WOS:000087502000005 ER PT J AU Chu, YH Kim, S Points, SD Petre, R Snowden, SL AF Chu, YH Kim, S Points, SD Petre, R Snowden, SL TI RX J050736-6847.8: A large supernova remnant around an X-ray binary in the Large Magellanic Cloud SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : ISM; Magellanic Clouds; supernova remnants; X-rays ID GLOBULAR-CLUSTERS AB RX J050736-6847.8 in the Large Magellanic Cloud (LMC) is an intriguing X-ray source consisting of a large ring (diameter similar to 150 pc) of diffuse emission and a central compact source. It is projected in the vicinity of the superbubble N103 around the star cluster NGC 1850. RX J050736-6847.8's ring of diffuse X-ray emission, offset from the superbubble N103, is not bounded by any optical shell structure, while RX J050736-6847.8's central compact X-ray source is projected within the cluster HS122. We have analyzed archival ROSAT observations of RX J050736-6847.8 to determine the physical properties of its X-ray-emitting gas. The X-ray luminosity of the diffuse X-ray emission is 5-6 x 10(35) ergs s(-1) in the 0.1-2.4 keV band, within the range for supernova remnants (SNRs). Assuming a shell geometry with a fractional shell thickness (Delta R/R) of 0.05-0.2, we find the density of the hot gas to be 0.05-0.09 cm(-3) and a hot gas mass of similar to 820 M.. The physical properties of this shell of hot gas are consistent cm with Sedov's solution for a similar to 5 x 10(4) yr old SNR in a low-density (similar to 0.015 cm(-3)) medium formed by a supernova of an explosion energy of 3 x 10(51) ergs. The density is so low that no detectable optical emission is expected. Therefore, we suggest that this ring of X-ray emission originates in a SNR, the largest known in the LMC. The large size, low density, and the regular X-ray morphology suggest that this SNR is located in the halo of the LMC; the small absorption column density further suggests that this SNR is on the near side of the LMC halo. The central compact source of RX J050736-6847.8 is probably an X-ray binary in the cluster HS122. The relationship between the compact source and the diffuse ring is unknown. 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. NR 29 TC 14 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 2000 VL 119 IS 5 BP 2242 EP 2247 DI 10.1086/301331 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 318YB UT WOS:000087311300017 ER PT J AU Danforth, CW Cornett, RH Levenson, NA Blair, WP Stecher, TP AF Danforth, CW Cornett, RH Levenson, NA Blair, WP Stecher, TP TI A comparison of ultraviolet, optical, and X-ray imagery of selected fields in the Cygnus Loop SO ASTRONOMICAL JOURNAL LA English DT Article DE shock waves; supernova remnants; ultraviolet emission ID RADIATIVE SHOCK-WAVE; SUPERNOVA REMNANT; INTERSTELLAR CLOUD; IMAGING TELESCOPE; EMISSION; NOVA; DYNAMICS; FILAMENT; FRONT AB During the Astro-1 and Astro-2 space shuttle missions in 1990 and 1995, far ultraviolet (FUV) images of five 40' diameter fields around the rim of the Cygnus Loop supernova remnant were observed with the Ultraviolet Imaging Telescope (UIT). These fields sampled a broad range of conditions, including both radiative and nonradiative shocks in various geometries and physical scales. In these shocks, the UIT B5-band samples predominantly C Iv lambda 1550 and the hydrogen two-photon recombination continuum. Smaller contributions are made by emission lines of [He II] lambda 1640 and O III] lambda 1665. We present these new FUV images and compare them with optical H alpha and [O III] images and ROSAT HRI X-ray images. Comparing the UIT images with those from the other bands provides new insights into the spatial variations and locations of these different types of emission. By comparing with shock-model calculations and published FUV spectroscopy at select locations, we surmise that resonance scattering in the strong FUV permitted lines is widespread in the Cygnus Loop, especially in the bright optical filaments typically selected for observation in most previous studies. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Raytheon ITSS, Lanham, MD 20706 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Danforth, CW (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. OI Levenson, Nancy A./0000-0003-4209-639X NR 38 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 2000 VL 119 IS 5 BP 2319 EP 2331 DI 10.1086/301365 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 318YB UT WOS:000087311300025 ER PT J AU Terebey, S Van Buren, D Matthews, K Padgett, DL AF Terebey, S Van Buren, D Matthews, K Padgett, DL TI The spectrum of TMR-1C is consistent with a background star SO ASTRONOMICAL JOURNAL LA English DT Article DE binaries : general; circumstellar matter; infrared radiation; planetary systems; stars : formation; stars : individual(TMR 1) ID YOUNG STELLAR OBJECTS; EXTRASOLAR GIANT PLANETS; BROWN DWARF CANDIDATES; SYSTEMS; MASS; TAURUS; EXTINCTION; EVOLUTION; SPECTROSCOPY; DISCOVERY AB In a previous paper we proposed that there may be a population of runaway planets and brown dwarfs that formed via ejection from multiple-star systems. We further suggested TMR-1C as a candidate runaway protoplanet. Hubble Space Telescope NICMOS images of the Class I protostar TMR-1 (IRAS 04361 + 2547) reveal TMR-1C as a faint near-infrared companion with 10." 0 = 1400 AU projected separation. The central protostar is itself resolved as a close binary with 0." 31 = 42 AU separation, surrounded by circumstellar reflection nebulosity. A long, narrow filament seems to connect the protobinary to the faint companion TMR-1C, suggesting a physical association, which can plausibly be explained if TMR-1C was ejected by the protobinary. This paper presents near-infrared grism spectroscopy to constrain the effective temperature of TMR-1C, obtained with the Near-Infrared Camera (NIRC) at Keck Observatory. To interpret the data, we construct a grid of extincted M dwarf spectra to compare with the low-resolution (R similar to 120) NIRC spectrum. The assumed extinction corresponds to standard interstellar dust. With the additional assumption that no near-infrared dust excess contributes to the spectrum, then M4.5 is the latest spectral type TMR-1C can have within the uncertainties. Adopting 2 sigma error bars, this translates to T(eff) > 2700 K effective temperature and A(K) = 2.5 +/- 0.75 extinction at K band (A(V) = 22 +/- 6.6 for standard dust). We compare the luminosity and effective temperature of TMR-1C with evolutionary tracks of young giant planets and brown dwarfs in a theoretical H-R diagram. Given a relatively low inferred luminosity of similar to 10(-3) L., then TMR-1C is hotter than predicted by available theoretical models. However, the models are very uncertain at such young ages, less than 300,000 yr, so that it is unclear whether the theoretical tracks by themselves provide a suitably strong test. Given the quality of the observed spectrum, only a partial answer is possible. The new data do not lend weight to the protoplanet interpretation, and the results remain consistent with the explanation that TMR-1C may be a background star. We discuss additional observational tests that may be useful. C1 Extrasolar Res Corp, Pasadena, CA 91101 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. CALTECH, Dept Phys, Pasadena, CA 91125 USA. RP Terebey, S (reprint author), Extrasolar Res Corp, 569 S Marengo Ave, Pasadena, CA 91101 USA. NR 44 TC 20 Z9 20 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 2000 VL 119 IS 5 BP 2341 EP 2348 DI 10.1086/301336 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 318YB UT WOS:000087311300027 ER PT J AU Girard, TM Wu, H Lee, JT Dyson, SE van Altena, WF Horch, EP Gilliland, RL Schaefer, KG Bond, HE Ftaclas, C Brown, RH Toomey, DW Shipman, HL Provencal, JL Pourbaix, D AF Girard, TM Wu, H Lee, JT Dyson, SE van Altena, WF Horch, EP Gilliland, RL Schaefer, KG Bond, HE Ftaclas, C Brown, RH Toomey, DW Shipman, HL Provencal, JL Pourbaix, D TI A redetermination of the mass of Procyon SO ASTRONOMICAL JOURNAL LA English DT Article DE astrometry; stars : individual (Procyon) ID PROGRAM AB The parallax and astrometric orbit of Procyon have been redetermined from PDS measurements of over 250 photographic plates spanning 83 years, with roughly 600 exposures used in the solution. These data are combined with two modern measurements of the primary-white dwarf separation, one utilizing a ground-based coronagraph, the other, the Planetary Camera (PC) of the Hubble Space Telescope. Together with the redetermined astrometric orbit and parallax, these yield new estimates of the component masses. The derived masses are 1.497 +/- 0.037 M. for the primary and 0.602 +/- 0.015M. for the white dwarf secondary. These mass values are heavily weighted by the PC separation measurement, which, while being somewhat discordant with the ground-based measures, we argue is more precise and more accurate and thus deserving of its greater weight. This stated, the long-standing discrepancy between previous determinations of the observed mass of Procyon A (1.75 M.) and the value supported by stellar evolution models (1.50 M.) appears to be reconciled. C1 Yale Univ, Dept Astron, New Haven, CT 06520 USA. Rochester Inst Technol, Ctr Imaging Sci, Rochester, NY 14623 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Towson State Univ, Dept Phys Astron & Geosci, Towson, MD 21252 USA. Michigan Technol Univ, Dept Phys, Houghton, MI 49931 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. NASA, Infrared Telescope Facil, Hilo, HI 96720 USA. Univ Delaware, Dept Phys & Astron, Sharp Lab, Newark, DE 19716 USA. Free Univ Brussels, Inst Astron & Astrophys, B-1050 Brussels, Belgium. RP Girard, TM (reprint author), Yale Univ, Dept Astron, POB 208101, New Haven, CT 06520 USA. NR 19 TC 58 Z9 58 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 2000 VL 119 IS 5 BP 2428 EP 2436 DI 10.1086/301353 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 318YB UT WOS:000087311300036 ER PT J AU Auer, LH Standish, EM AF Auer, LH Standish, EM TI Astronomical refraction: Computational method for all zenith angles SO ASTRONOMICAL JOURNAL LA English DT Article DE methods : numerical AB It is shown that the problem of computing astronomical refraction for any value of the zenith angle may be reduced to a simple, nonsingular, numerical quadrature when the proper choice is made for the independent variable of integration. The angle between the radius vector and the light ray is such a choice. The implementation of the quadrature method is discussed in its general form and illustrated by means of an application to a piecewise polytropic atmosphere. The flexibility, simplicity, and computational efficiency of the method are evident. C1 Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Auer, LH (reprint author), Univ Calif Los Alamos Natl Lab, Mail Stop B226, Los Alamos, NM 87545 USA. NR 4 TC 31 Z9 31 U1 0 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 2000 VL 119 IS 5 BP 2472 EP 2474 DI 10.1086/301325 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 318YB UT WOS:000087311300042 ER PT J AU Jarrett, TH Chester, T Cutri, R Schneider, S Skrutskie, M Huchra, JP AF Jarrett, TH Chester, T Cutri, R Schneider, S Skrutskie, M Huchra, JP TI 2MASS extended source catalog: Overview and algorithms SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : general; methods : data analysis; surveys; techniques : image processing techniques : miscellaneous; techniques : photometric ID FAINT GALAXIES; PHOTOMETRY; FIELD AB The Two Micron All Sky Survey (2MASS) will observe over 1,000,000 galaxies and extended Galactic sources covering the entire sky at wavelengths between 1 and 2 mu m. Most of these galaxies will be newly cataloged objects. The survey catalog will have both high completeness and reliability down to J = 15.0 mag and K(s) = 13.5 mag, equivalent to 1.6 and 2.9 mJy, respectively. Galaxies as small as 10 " are resolved, and those as large as similar to 2.'5 are fully imaged. 2MASS will discover galaxies never seen before in the "zone of avoidance" caused by the obscuring effects of Galactic dust and gas, limited only by the extreme number of stars at very low Galactic latitude, especially toward the Galactic center. This paper describes the basic algorithms used to detect and characterize extended sources in the 2MASS database and catalog. Critical procedures include tracking the point-spread function, image background removal, artifact removal, photometry and basic parameterization, star-galaxy discrimination, and object classification using a decision tree technique. We introduce and provide examples of the types of extended sources that 2MASS detects across the sky, including galaxies, Galactic nebulae and resolved stellar objects, multiple stars and clusters, and, finally, artifacts arising from bright stars and transient events. A future paper will provide a full statistical analysis and verification of the completeness, reliability, and integrity of the first release catalog, as well as some of the basic scientific results of the catalog, including galaxy colors, number counts, and redshift distribution. C1 CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Univ Massachusetts, Astron Program, Amherst, MA 01003 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Jarrett, TH (reprint author), CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Mail Stop 100-22, Pasadena, CA 91125 USA. EM jarrett@ipac.caltech.edu; tchester@ipac.caltech.edu; roc@ipac.caltech.edu; schneider@phast.umass.edu; skrutski@phast.umass.edu; huchra@cfa.harvard.edu NR 32 TC 581 Z9 597 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 2000 VL 119 IS 5 BP 2498 EP 2531 DI 10.1086/301330 PG 34 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 318YB UT WOS:000087311300045 ER PT J AU Canuto, VM AF Canuto, VM TI Turbulent convection: is 2D a good proxy of 3D? SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE convection; stars : interiors ID HYDRODYNAMICAL SIMULATIONS; MIXING-LENGTH; SOLAR; MODEL; STARS AB Several authors have recently carried out 2D simulations of turbulent convection for both solar and massive stars. Fitting the 2D results with the MLT, they obtain that alpha(MLT) > 1 specifically, 1.4 less than or equal to alpha(MLT) less than or equal to 1.8 The authors further suggest that this methodology could be used to calibrate the MLT used in stellar evolutionary codes. We suggest the opposite viewpoint: the 2D results show that MLT is internally inconsistent because the resulting alpha(MLT) > 1 violates the MLT basic assumption that alpha(MLT) < 1 When the 2D results are fitted with the CM model, alpha(MLT) < 1, in accord with the basic tenet of the model. On the other hand, since both MLT and CM are local models, they should be replaced by the next generation of non-local, time dependent turbulence models which we discuss in some detail. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Dept Appl Phys, New York, NY 10027 USA. RP Canuto, VM (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 20 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 MAY PY 2000 VL 357 IS 1 BP 177 EP 179 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 321GD UT WOS:000087447000032 ER PT J AU Hudson, RL Moore, MH AF Hudson, RL Moore, MH TI New experiments and interpretations concerning the "XCN" band in interstellar ice analogues SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE infrared : ISM : lines and bands; ISM : molecules; ISM : abundances; molecular processes; ISM : dust, extinction ID SOLID-STATE; MOLECULES; ABSORPTION; MIXTURES; COMETS; OCN AB Evidence for the formation of OCN- in interstellar ice analogues is summarized with an emphasis on the recent experiments of Demyk et al. (1998). Their experiments are reinterpreted in terms of two different types of chemical reactions, acid-base and oxidation-reduction. New spectra of UV-photolyzed and p(+)-irradiated ices are presented, and reasons for similarities considered. The role of e(-) and H+ scavengers in revealing ice photo- and radiation chemistries is stressed, and it is concluded that electron-transfer reactions may play a more important role than commonly thought. C1 Eckerd Coll, Dept Chem, St Petersburg, FL 33733 USA. NASA, Goddard Space Flight Ctr, Astrochem Branch, Greenbelt, MD 20771 USA. RP Hudson, RL (reprint author), Eckerd Coll, Dept Chem, St Petersburg, FL 33733 USA. EM hudsonrl@eckerd.edu RI Hudson, Reggie/E-2335-2012 NR 13 TC 39 Z9 39 U1 2 U2 6 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 2000 VL 357 IS 2 BP 787 EP 792 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 322NL UT WOS:000087515600047 ER PT J AU Gerakines, PA Moore, MH Hudson, RL AF Gerakines, PA Moore, MH Hudson, RL TI Carbonic acid production in H2O : CO2 ices - UV photolysis vs. proton bombardment SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE molecular data; molecular processes; methods : laboratory; comets : general; planets and satellites : general; ISM : molecules ID INTERSTELLAR ICES; MIXTURES; SURFACE; SATELLITES; ANALOGS; DIOXIDE; CLOUDS; COMETS; CO2 AB We have the unique ability to perform ultraviolet photolysis (similar to 10 eV photon(-1)) and ion irradiation (0.8 MeV p(+)) in the same experimental set-up, with ices created under identical conditions. We present experiments that show the formation of carbonic acid (H2CO3) from H2O:CO2 ice mixtures exposed to either UV photons or high-energy protons. CO and CO3 were also formed in these experiments. Results show that while H2CO3 is readily formed by p(+) bombardment, its formation by UV photolysis is limited by the penetration of UV photons into the ice. H2CO3 production pathways are investigated. Intrinsic IR band strengths are determined for eight IR features of H2CO3. Implications for ices found in various astrophysical environments are discussed. C1 NASA, Goddard Space Flight Ctr, Astrochem Branch, Greenbelt, MD 20771 USA. Eckerd Coll, Dept Chem, St Petersburg, FL 33733 USA. RP Gerakines, PA (reprint author), NASA, Goddard Space Flight Ctr, Astrochem Branch, Code 691, Greenbelt, MD 20771 USA. EM Perry.A.Gerakines@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 31 TC 123 Z9 123 U1 2 U2 13 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 2000 VL 357 IS 2 BP 793 EP 800 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 322NL UT WOS:000087515600048 ER PT J AU Van Kerckhoven, C Hony, S Peeters, E Tielens, AGGM Allamandola, LJ Hudgins, DM Cox, P Roelfsema, PR Voors, RHM Waelkens, C Waters, LBFM Wesselius, PR AF Van Kerckhoven, C Hony, S Peeters, E Tielens, AGGM Allamandola, LJ Hudgins, DM Cox, P Roelfsema, PR Voors, RHM Waelkens, C Waters, LBFM Wesselius, PR TI The C-C-C bending modes of PAHs: a new emission plateau from 15 to 20 mu m SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE ISM : molecules; ISM : dust, extinction; ISM : HII regions; ISM : planetary nebulae : general; stars : pre-main sequence; infrared : ISM : lines and bands ID POLYCYCLIC AROMATIC-HYDROCARBONS; FAR-INFRARED EMISSION; CIRCUMSTELLAR PAHS; ISO SPECTROSCOPY; INTERSTELLAR; FEATURES; MOLECULES; SPECTRA; NGC-7027; REGIONS AB We have obtained 2.5-45 mu m spectra of a sample of compact H II regions, YSOs and evolved stars in order to study the origin and evolution of interstellar Polycyclic Aromatic Hydrocarbon molecules (PAHs). Besides the well-known, strong PAH bands at 3.3, 6.2, 7.7, 8.6, and 11.2 mu m, these spectra reveal for the first time, a ubiquitous emission plateau from 15 to 20 mu m While the overall shape of this plateau is very similar in all sources, the detailed profiles vary from source to source. In particular, some sources show a distinct emission feature at 16.4 mu m. Moreover, the integrated intensity of this plateau varies relative to the PAH emission features by a factor 10 in our sample. We attribute this 15-20 mu m plateau to a blend of many emission features due to the interstellar or circumstellar PAH family present in these sources. Laboratory studies and quantum chemical calculations show that PAH molecules invariably possess emission features in this wavelength region, arising from C-CC bending modes which cause in- and out-of-plane distortion of the carbon skeleton. These modes are very sensitive to the molecular structure of the specific PAHs present and hence different molecules emit at different wavelengths. Analysis of the available data on the IR characteristics of PAHs show that a collection of PAHs will give rise to a broad plateau in this region. We have analyzed the size distribution of PAHs giving rise to the IR emission spectra of the sources in our samples. While much of the 15-20 mu m plateau is thought to arise in relatively large PAHs and PAH clusters, we attribute the 16.4 mu m feature to the small end of the interstellar PAH size distribution. We conclude that the observed increased strength of the 15-20 mu m plateau relative to the shorter wavelength IR emission features in regions of massive star formation is caused by a preponderance of larger PAHs and PAH clusters in those sources. Possibly this reflects the importance of coagulation in the dense molecular cloud environment from which these stars are formed. C1 Katholieke Univ Leuven, Inst Sterrenkunde, B-3001 Louvain, Belgium. Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. SRON, NL-9700 AV Groningen, Netherlands. Univ Groningen, Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Univ Paris 11, Inst Astrophys Spatiale, F-91405 Orsay, France. Univ Utrecht, Sterrekundig Inst, NL-3584 CA Utrecht, Netherlands. RP Van Kerckhoven, C (reprint author), Katholieke Univ Leuven, Inst Sterrenkunde, Celestijnenlaan 200B, B-3001 Louvain, Belgium. EM caroline@ster.kuleuven.ac.be NR 28 TC 114 Z9 114 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 2000 VL 357 IS 3 BP 1013 EP 1019 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 328KX UT WOS:000087851000032 ER PT J AU Haiman, Z Abel, T Rees, MJ AF Haiman, Z Abel, T Rees, MJ TI The radiative feedback of the first cosmological objects SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : theory; diffuse radiation; early universe; galaxies : formation; molecular processes; radiative transfer ID DWARF GALAXIES; HIGH-REDSHIFT; REIONIZATION; CLOUDS; MODEL AB hierarchical models of structure formation, an early cosmic UV background (UVB) is produced by the small (T(vir) less than or similar to 10(4) K) halos that collapse before reionization. The UVB at energies below 13.6 eV suppresses the formation of stars or black holes inside small halos by photodissociating their only cooling agent, molecular H(2). We self-consistently compute the buildup of the early UVB in Press-Schechter models, coupled with H(2) photodissociation both in the intergalactic medium (IGM) and inside virialized halos. We find that the intergalactic H(2) has a negligible effect on the UVB, both because its initial optical depth is small (less than or similar to 0.1) and because it is photodissociated at an early stage. If the UV sources in the first collapsed halos are stars, then their UV flux suppresses further star formation inside small halos. This results in a pause in the buildup of the UVB, and reionization is delayed until larger halos (T(vir) greater than or similar to 10(4) K) collapse. If the small halos host miniquasars with hard spectra extending to similar to 1 keV, then their X-rays balance the effects of the WE, the negative feedback does not occur, and reionization could be caused by the small halos. C1 NASA, Fermi Natl Accelerator Lab, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Illinois, Natl Ctr Supercomp Applicat, Lab Computat Astrophys, Urbana, IL 61801 USA. Max Planck Inst Astrophys, D-85748 Garching, Germany. Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England. RP Haiman, Z (reprint author), NASA, Fermi Natl Accelerator Lab, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. NR 31 TC 266 Z9 266 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 1 PY 2000 VL 534 IS 1 BP 11 EP 24 DI 10.1086/308723 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TC UT WOS:000087183300002 ER PT J AU Heap, SR Williger, GM Smette, A Hubeny, I Sahu, MS Jenkins, EB Tripp, TM Winkler, JN AF Heap, SR Williger, GM Smette, A Hubeny, I Sahu, MS Jenkins, EB Tripp, TM Winkler, JN TI STIS observations of HeII Gunn-Peterson absorption toward Q0302-003 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; intergalactic medium; quasars : absorption lines ID LY-ALPHA FOREST; HIGH-REDSHIFT; INTERGALACTIC MEDIUM; RADIATIVE-TRANSFER; HELIUM ABSORPTION; CLUMPY UNIVERSE; HIGH-RESOLUTION; IONIZED HELIUM; SPECTRA; TELESCOPE AB The ultraviolet spectrum (1145-1720 Angstrom) of the distant quasar Q0302-003 (z = 3.286) was observed at 1.8 Angstrom resolution with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. A total integration time of 23,280 s was obtained. The spectrum clearly delineates the Gunn-Peterson He II absorption trough, produced by He II Ly alpha along the line of sight over the redshift range z = 2.78-3.28. Its interpretation was facilitated by modeling based on Reck HIRES spectra of the H I Ly alpha forest (provided by A. Songaila and by M. Rauch and W. Sargent). We find that near the quasar, He II Ly alpha absorption is produced by discrete clouds, with no significant diffuse gas; this is attributed to a He II "proximity effect" in which the quasar fully ionizes He in the diffuse intergalactic medium, but not the He in denser clouds. By two different methods we calculate that the average He II Ly alpha opacity at z approximate to 3.15 is tau greater than or equal to 4.8. In the Dobrzycki-Bechtold void in the H I Ly alpha forest near z = 3.18, the average He II opacity z = 4.47(-0.33)(+0.48). Such large opacities require the presence of a diffuse gas component as well as a soft UV background spectrum, whose softness parameter, defined as the ratio of the photoionization rate in H I over the one in He II S = Gamma(H I)(J)/Gamma(He II)(J) similar or equal to 800, indicating a significant stellar contribution. At z = 3.05, there is a distinct region of high He II Ly alpha transmission that most likely arises in a region where helium is doubly ionized by a discrete local source, quite possibly an AGN. At redshifts z < 2.87, the He II Ly alpha opacity detected by STIS, tau = 1.88, is significantly lower than at z > 3. Such a reduction in opacity is consistent with Songaila's report that the hardness of the UV background spectrum increases rapidly from z = 3 to z = 2.9. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Opt Astron Observ, Tucson, AZ 85726 USA. Princeton Univ Observ, Princeton, NJ 08544 USA. Univ Oxford Queens Coll, Oxford OX1 4AW, England. RP Heap, SR (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. EM heap@srh.gsfc.nasa.gov; williger@tejut.gsfc.nasa.gov; asmette@band3.gsfc.nasa.gov; hubeny@tlusty.gsfc.nasa.gov; msahu@panke.gsfc.nasa.gov; ebj@astro.princeton.edu; tripp@astro.princeton.edu; jonathan.winkler@queens.oxford.ac.uk RI Jenkins, Edward/P-5684-2014 OI Jenkins, Edward/0000-0003-1892-4423 NR 56 TC 118 Z9 118 U1 1 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 1 PY 2000 VL 534 IS 1 BP 69 EP 89 DI 10.1086/308719 PN 1 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TC UT WOS:000087183300008 ER PT J AU Sikora, M Madejski, G AF Sikora, M Madejski, G TI On pair content and variability of subparsec jets in quasars SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : jets; plasmas; quasars : general; radiation mechanisms : nonthermal; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; X-RAY VARIABILITY; AMBIENT RADIATION; RELATIVISTIC JET; RADIO-SOURCES; GAMMA-RAYS; BLAZARS AB X-ray observations of blazars associated with optically violently variable (OVV) quasars put strong constraints on the e(+)e(-) pair content of radio-loud quasar jets. From those observations, we infer that jets in quasars contain many more e+e- pairs than protons, but dynamically are still dominated by protons. In particular, we show that pure e(+)e(-) jet models can be excluded, since they overpredict soft X-radiation; likewise, pure proton-electron jets can be excluded, since they predict too weak nonthermal X-radiation. An intermediate case is viable. We demonstrate that jets that are initially proton-electron ("protojets") can be pair-loaded via interaction with 100-300 keV photons produced in hot accretion disc coronae, likely to exist in active galactic nuclei in general. If the coronal radiation is powered by magnetic flares, the pair loading is expected to be nonuniform and nonaxisymmetric. Together with radiation drag, this leads to velocity and density perturbations in a jet and the formation of shocks, where the pairs are accelerated. Such a scenario can explain rapid (timescale of similar to a day) variability observed in OVV quasars. C1 Nicolaus Copernicus Astron Ctr, PL-00716 Warsaw, Poland. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Sikora, M (reprint author), Nicolaus Copernicus Astron Ctr, Bartycka 18, PL-00716 Warsaw, Poland. NR 35 TC 140 Z9 140 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2000 VL 534 IS 1 BP 109 EP 113 DI 10.1086/308756 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TC UT WOS:000087183300011 ER PT J AU Ebeling, H Jones, LR Perlman, E Scharf, C Horner, D Wegner, G Malkan, M Fairley, BW Mullis, CR AF Ebeling, H Jones, LR Perlman, E Scharf, C Horner, D Wegner, G Malkan, M Fairley, BW Mullis, CR TI The warps survey. III. The discovery of an X-ray luminous galaxy cluster at z=0.833 and the impact of X-ray substructure on cluster abundance measurements SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : clusters : individual (C1 J0152.7-1357); surveys; X-rays : galaxies ID MEDIUM-SENSITIVITY SURVEY; EVOLUTION; UNIVERSE; SAMPLE AB The Wide Angle ROSAT Pointed Survey team reviews the properties and history of the discovery of Cl J0152.7 - 1357, an X-ray luminous, rich cluster of galaxies at a redshift of z = 0.833. At L-X = 8 x 10(44) h(50)(-2) ergs s(-1) (0.5-2.0 keV) Cl J0152.7-1357 is the most X-ray luminous cluster known at redshifts z > 0.55. The high X-ray luminosity of the system suggests that massive clusters may begin to form at redshifts considerably greater than unity. This scenario is supported by the high degree of optical and X-ray substructure in Cl J0152.7-1357, which is similarly complex as that of other X-ray-selected clusters at comparable redshift and consistent with the hypothesized picture of cluster formation by mass infall along large-scale filaments. X-ray emission from Cl J0152.7-1357 was detected already in 1980 with the Einstein IPC. However, because the complex morphology of the emission caused its significance to be underestimated, the corresponding source was not included in the cluster sample of the Einstein Extended Medium-Sensitivity Survey (EMSS) and hence was not previously identified. Simulations of the EMSS source detection and selection procedure performed by us suggest a general, mild bias of the EMSS cluster sample against X-ray luminous clusters with pronounced substructure. If highly unrelaxed, merging clusters are common at intermediate-to-high redshift (as is suggested by the current data), they could create a bias in some samples as the morphological complexity of mergers may cause them to fall below the flux limit of surveys that make the implicit or explicit assumption of a unimodal spatial source geometry. Conversely, the enhanced X-ray luminosity of mergers might cause them to, temporarily, rise above the flux limit. Either effect could lead to erroneous conclusions about the evolution of the comoving cluster space density. A high fraction of morphologically complex clusters at high redshift would also call into question the validity of evolutionary studies (and, specifically, cosmological conclusions) which implicitly or explicitly assume that the systems under investigation are virialized. C1 Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Univ Birmingham, Sch Phys & Space Res, Birmingham B15 2TT, W Midlands, England. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, College Pk, MD 20742 USA. Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA. Univ Calif Los Angeles, Dept Astron, Los Angeles, CA 90024 USA. RP Univ Hawaii, Inst Astron, 2680 Woodlawn Dr, Honolulu, HI 96822 USA. NR 50 TC 71 Z9 71 U1 1 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 MAY 1 PY 2000 VL 534 IS 1 BP 133 EP 145 DI 10.1086/308729 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TC UT WOS:000087183300013 ER PT J AU Jones, DL Wehrle, AE Meier, DL Piner, BG AF Jones, DL Wehrle, AE Meier, DL Piner, BG TI The radio jets and accretion disk in NGC 4261 SO ASTROPHYSICAL JOURNAL LA English DT Article DE individual (NGC 4261, 3C 270); galaxies : jets; galaxies : nuclei ID ACTIVE GALACTIC NUCLEI; PARSEC-SCALE JETS; ELLIPTICAL GALAXIES; BLACK-HOLES; NGC-4261; DISCOVERY AB The structure of active galactic nucleus (AGN) accretion disks on subparsec scales can be probed through free-free absorption of synchrotron emission from the base of symmetric radio jets. For objects in which both jet and counterjet are detectable with very long baseline interferometry (VLBI), the accretion disk will cover part of the counterjet and produce diminished brightness whose angular size and depth as a function of frequency can reveal the radial distribution of free electrons in the disk. The nearby (41 Mpc, independent of H-0) FR I radio galaxy NGC 4261 contains a pair of symmetric kiloparsec-scale jets. On parsec scales, radio emission from the nucleus is strong enough for detailed imaging with VLBI. We present new Very Long Baseline Array (VLBA) observations of NGC 4261 at 22 and 43 GHz, which we combine with previous observations at 1.6 and 8.4 GHz to map absorption caused by an inner accretion disk. The relative closeness of NGC 4261 combined with the high angular resolution provided by the VLBA at 43 GHz gives us a very high linear resolution, approximately 2 x 10(-2) pc approximate to 4000 AU approximate to 400 Schwarzschild radii for a 5 x 10(8) M. black hole. The jets appear more symmetric at 1.6 GHz because of the low angular resolution available. The jets are also more symmetric at 22 and 43 GHz, presumably because the optical depth of free-free absorption is small at high frequencies. At 8.4 GHz, neither confusion effect is dominant and absorption of counterjet emission by the presumed disk is detectable. We find that the orientation of the radio jet axis is the same on parsec and kiloparsec scales, indicating that the spin axis of the inner accretion disk and black hole has remained unchanged for at least 10(6) (and more likely >10(7)) yr. This suggests that a single merger event may be responsible for the supply of gas in the nucleus of NGC 4261. The jet opening angle is between 0 degrees.3 and 20 degrees during the first 0.2 pc of the jet and must be less than 5 degrees during the first 0.8 pc. Assuming that the accretion disk is geometrically and optically thin and composed of a uniform 10(4) K plasma, the average electron density in the inner 0.1 pc of the disk is 10(3)-10(8) cm(-3). The mass of ionized gas in the inner pc of the disk is 10(1)-10(3) M., sufficient to power the radio source for similar to 10(4)-10(6) yr. Equating thermal gas pressure and magnetic field strength gives a disk magnetic field of similar to 10(-4) to 10-2 gauss at 0.1 pc. We include an appendix containing expressions for a simple, optically thin, gas-pressure-dominated accretion disk model that may be applicable to other galaxies in addition to NGC 4261. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jones, DL (reprint author), CALTECH, Jet Prop Lab, Mail Code 238-332,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 30 TC 39 Z9 40 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2000 VL 534 IS 1 BP 165 EP 171 DI 10.1086/308751 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TC UT WOS:000087183300015 ER PT J AU Edelson, R Koratkar, A Nandra, K Goad, M Peterson, BM Collier, S Krolik, J Malkan, M Maoz, D O'Brien, P Shull, JM Vaughan, S Warwick, R AF Edelson, R Koratkar, A Nandra, K Goad, M Peterson, BM Collier, S Krolik, J Malkan, M Maoz, D O'Brien, P Shull, JM Vaughan, S Warwick, R TI Intensive HST, RXTE, and ASCA monitoring of NGC 3516: Evidence against thermal reprocessing SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (NGC 3516); galaxies : Seyfert; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; BROAD-LINE REGION; SHORT-TIMESCALE VARIABILITY; X-RAY VARIABILITY; SEYFERT-GALAXIES; ULTRAVIOLET VARIABILITY; COLD MATTER; MULTIWAVELENGTH OBSERVATIONS; CONTINUUM; NGC-7469 AB During 1998 April 13-16, the bright, strongly variable Seyfert 1 galaxy NGC 3516 was monitored almost continuously with HST for 10.3 hr at ultraviolet wavelengths and 2.8 days at optical wavelengths, and simultaneous RXTE and ASCA monitoring covered the same period. The X-ray fluxes were strongly variable with the soft (0.5-2 keV) X-rays showing stronger variations (similar to 65% peak to peak) than the hard (2-10 keV) X-rays (similar to 50% peak to peak). The optical continuum showed much smaller but still highly significant variations: a slow similar to 2.5% rise followed by a faster similar to 3.5% decline. The short ultraviolet observation did not show significant variability. The soft and hard X-ray light curves were strongly correlated, with no evidence for a significant interband lag. Likewise, the optical continuum bands (3590 and 5510 Angstrom) were also strongly correlated, with no measurable lag, to 3 sigma limits of less than or similar to 0.15 day. However, the optical and X-ray light curves showed very different behavior, and no significant correlation or simple relationship could be found. These results appear difficult to reconcile with previous reports of correlations between X-ray and optical variations and of measurable lags within the optical band for some other Seyfert 1 galaxies. These results also present serious problems for "reprocessing" models in which the X-ray source heats a stratified accretion disk, which then reemits in the optical/ultraviolet: the synchronous variations within the optical would suggest that the emitting region is less than or similar to 0.3 It-day across, while the lack of correlation between X-ray and optical variations would indicate, in the context of this model, that any reprocessing region must be greater than or similar to 1 lt-day in size. It may be possible to resolve this conflict by invoking anisotropic emission or special geometry, but the most natural explanation appears to be that the bulk of the optical luminosity is generated by some mechanism other than reprocessing. C1 Univ Calif Los Angeles, Dept Astron, Los Angeles, CA 90095 USA. Univ Leicester, Xray Astron Grp, Leicester LE1 7RH, Leics, England. Space Telescope Sci Inst, Baltimore, MD 20771 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. Tel Aviv Univ, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. Tel Aviv Univ, Wise Observ, IL-69978 Tel Aviv, Israel. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. RP Edelson, R (reprint author), Univ Calif Los Angeles, Dept Astron, Los Angeles, CA 90095 USA. NR 39 TC 66 Z9 66 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2000 VL 534 IS 1 BP 180 EP 188 DI 10.1086/308752 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TC UT WOS:000087183300017 ER PT J AU Bower, GA Green, RF Quillen, AC Danks, A Gull, T Hutchings, J Joseph, C Kaiser, ME Weistrop, D Woodgate, B Malumuth, EM Nelson, C AF Bower, GA Green, RF Quillen, AC Danks, A Gull, T Hutchings, J Joseph, C Kaiser, ME Weistrop, D Woodgate, B Malumuth, EM Nelson, C TI The ionization source in the nucleus of M84 SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL Lacertae objects : general; galaxies : active; galaxies : elliptical and lenticular, cD; galaxies : individual (M84); galaxies : nuclei ID ACTIVE GALACTIC NUCLEI; NARROW-LINE-PROFILES; EARLY-TYPE GALAXIES; BLACK-HOLE; CENTAURUS-A; ENERGY-DISTRIBUTIONS; INTERSTELLAR MATTER; ELLIPTIC GALAXIES; BL LACERTAE; EMISSION AB We have obtained new Hubble Space Telescope observations of M84, a nearby massive elliptical galaxy whose nucleus contains a approximate to 1.5 x 10(9) M. dark compact object, which presumably is a supermassive black hole. Our Space Telescope Imaging Spectrograph spectrum provides the first clear detection of emission lines in the blue (e.g., [O II] lambda 3727, H beta, and [O III] lambda lambda 4959, 5007), which arise from a compact region approximate to 0 ".28 across centered on the nucleus. Our Near-Infrared Camera and Multiobject Spectrometer images exhibit the best view through the prominent dust lanes evident at optical wavelengths and provide a more accurate correction for the internal extinction. The relative fluxes of the emission lines we have detected in the blue together with those recently detected in the wavelength range 6295-6867 Angstrom by Bower et al. indicate that the gas at the nucleus is photoionized by a nonstellar process instead of hot stars. Stellar absorption features from cool stars at the nucleus are very weak. We update the spectral energy distribution of the nuclear point source and find that although it is roughly flat in most bands, the optical-to-UV continuum is very red, similar to the spectral energy distribution of BL Lac. Thus, the nuclear point source seen in high-resolution optical images by Bower et al. is not a star cluster but is instead a nonstellar source. Assuming isotropic emission from this source, we estimate that the ratio of bolometric luminosity to Eddington luminosity is similar to 5 x 10(-7). However, this could be underestimated if this source is a misaligned BL Lac object, which is a possibility suggested by the spectral energy distribution and the evidence of optical variability we describe. C1 Kitt Peak Natl Observ, Natl Opt Astron Observ, Tucson, AZ 85726 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. NASA, Goddard Space Flight Ctr, Raytheon ITSS, 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 62 TC 17 Z9 17 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2000 VL 534 IS 1 BP 189 EP 200 DI 10.1086/308741 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TC UT WOS:000087183300018 ER PT J AU Norris, JP Marani, GF Bonnell, JT AF Norris, JP Marani, GF Bonnell, JT TI Connection between energy-dependent lags and peak luminosity in gamma-ray bursts SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts ID IDENTIFICATION; EVOLUTION; REDSHIFT; BRIGHT AB We suggest a connection between the pulse paradigm at gamma-ray energies and the recently demonstrated luminosity distribution in gamma-ray bursts: The spectral evolution timescale of pulse structures is anticorrelated with peak luminosity and with quantities that might be expected to reflect the bulk relativistic Lorentz factor, such as spectral hardness ratio. We establish this relationship in two important burst samples using the cross-correlation lags between low (25-50 keV) and high (100-300 keV and >300 keV) energy bands. For a set of seven bursts (six with redshifts) observed by CGRO/BATSE and BeppoSAX that also have optical or radio counterparts, the gamma/X peak flux ratios and peak luminosities are anticorrelated with spectral lag. For the 174 brightest BATSE bursts with durations longer than 2 s and significant emission above 300 keV, a similar anticorrelation is evident between gamma-ray hardness ratio or peak flux and spectral lag. For the six bursts with redshifts, the connection between peak luminosity and spectral lag is well fitted by a power law, L-53 approximate to 1.3 x (tau/0.01 s)(-1.15). While GRB 980425 (if associated with SN 1998bw) would appear to extend this trend qualitatively, with a lag of similar to 4-5 s and luminosity of similar to 1.3 x 10(47) ergs s(-1), it falls below the power-law relationship by a factor of several hundred. As noted previously by Band, most lags are concentrated on the short end of the lag distribution, near 100 ms, suggesting that the gamma-ray burst luminosity distribution is peaked on its high end. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Natl Res Council, Washington, DC 20418 USA. RP Norris, JP (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 50 TC 388 Z9 401 U1 0 U2 6 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2000 VL 534 IS 1 BP 248 EP 257 DI 10.1086/308725 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TC UT WOS:000087183300023 ER PT J AU Hurley, K Feroci, M Cinti, MN Costa, E Preger, B Frontera, F Dal Fiume, D Orlandini, M Amati, L Nicastro, L Heise, J in'T Zand, JJM Cline, T AF Hurley, K Feroci, M Cinti, MN Costa, E Preger, B Frontera, F Dal Fiume, D Orlandini, M Amati, L Nicastro, L Heise, J in'T Zand, JJM Cline, T TI Integrating the BeppoSAX Gamma-Ray Burst Monitor into the third Interplanetary Network SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts ID FOLLOW-UP OBSERVATIONS; 28 FEBRUARY 1997; X-RAY; ERROR BOX; AFTERGLOW; COUNTERPART; DISCOVERY; ULYSSES; CATALOG AB We have added the BeppoSAX Gamma-Ray Burst Monitor to the third Interplanetary Network (IPN3) of burst detectors. We analyze 16 bursts whose positions are known to good accuracy from measurements at other wavelengths. We show that there is excellent agreement between the Ulysses/BeppoSAX triangulation annuli and the known positions of these events and that these annuli can in many cases provide useful constraints on the positions of bursts detected by the BeppoSAX Wide-Field Camera and Narrow-Field Instruments. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. CNR, Ist Astrofis Spaziale, I-00133 Rome, Italy. Ist Technol & Radiaz Extraterrestri, Bologna, Italy. Ist Fis Cosm & Appl Informat, Palermo, Italy. Space Res Org Netherlands, Utrecht, Netherlands. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Hurley, K (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RI Orlandini, Mauro/H-3114-2014; Nicastro, Luciano/F-5866-2015; Amati, Lorenzo/N-5586-2015; OI Orlandini, Mauro/0000-0003-0946-3151; Nicastro, Luciano/0000-0001-8534-6788; Amati, Lorenzo/0000-0001-5355-7388; Costa, Enrico/0000-0003-4925-8523; Feroci, Marco/0000-0002-7617-3421 NR 53 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2000 VL 534 IS 1 BP 258 EP 264 DI 10.1086/308737 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TC UT WOS:000087183300024 ER PT J AU Valinia, A Kinzer, RL Marshall, FE AF Valinia, A Kinzer, RL Marshall, FE TI Measurement of the galactic X-ray/gamma-ray background radiation: Contribution of discrete sources SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic rays; Galaxy : general; gamma rays : observations; ISM : structure; X-rays : ISM ID EMISSION; PLANE; COMPONENT; CONTINUUM; RIDGE AB The Galactic background radiation near the Scutum arm was observed simultaneously with RXTE and OSSE in order to determine the spectral shape and the origin of the emission in the hard X-ray/soft gamma-ray band. The spectrum in the 3 keV to 1 MeV band is well modeled by four components: a high-energy continuum dominating above 500 keV that can be characterized by a power law of photon index similar to 1.6 (an extrapolation from measurements above similar to 1 MeV), a positron annihilation line at 511 keV and positronium continuum, a variable hard X-ray/soft gamma-ray component that dominates between 10 and 200 keV (with a minimum detected flux of similar to 7.7 x 10(-7) photons cm(-2) s(-1) keV(-1) deg(-2) at 100 keV averaged over the field of view of OSSE) and that is well modeled by an exponentially cutoff power law of photon index similar to 0.6 and energy cutoff at similar to 41 keV, and finally a thermal plasma model of solar abundances and temperature similar to 2.6 keV that dominates below 10 keV. We estimate that the contribution of bright discrete sources to the minimum flux detected by OSSE was similar to 46% at 60 keV and similar to 20% at 100 keV. The remaining unresolved emission may be interpreted either as truly diffuse emission with a hard spectrum (such as that from inverse Compton scattering) or the superposition of discrete sources that have very hard spectra. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. RP Valinia, A (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 29 TC 26 Z9 26 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2000 VL 534 IS 1 BP 277 EP 282 DI 10.1086/308755 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TC UT WOS:000087183300026 ER PT J AU Wachter, S Smale, AP Bailyn, C AF Wachter, S Smale, AP Bailyn, C TI The reappearance of the transient low-mass X-ray binary X1658-298 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : close; binaries : eclipsing; stars : individual (V2134 Ophiuchi); stars : neutron; stars : variables : other; X-rays : stars ID ORBITAL PERIOD CHANGE; EXO 0748-676; MXB 1659-29; EXO-0748-676; CYGNUS-X-3; DISCOVERY; EPHEMERIS; ECLIPSES AB In April 1999 the transient low-mass X-ray binary X1658-298 resumed its strong and persistent X-ray emission after a 21 yr interval of quiescence. We present RXTE data obtained soon after the reappearance, including four eclipses with a mean duration of 901.9 +/- 0.8 s and ingress/egress times of 6-13 s. Our updated ephemeris for the source indicates that the 7.1 hr orbital period of the system is decreasing with a timescale of 10(7) yr. Contemporaneous optical observations provide the first ever light curve of V2134 Oph, the optical counterpart of X1658-298. The optical modulation is highly variable from night to night and exhibits a distinct, narrow eclipse feature of about 0.2 mag superposed on a gradual brightness variation with similar to 0.7-0.8 mag amplitude. Our data indicate that there is no significant offset between the time of mideclipse in the X-ray and optical and that the narrow optical eclipse feature is of the same duration as the X-ray eclipse. This implies an accretion disk structure characterized by enhanced optical emission coincident with the central X-ray-emitting area. C1 Natl Opt Astron Observ, Cerro Tololo Inter Amer Observ, La Serena, Chile. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Univ Space Res Assoc, Greenbelt, MD 20771 USA. Yale Univ, Dept Astron, New Haven, CT 06520 USA. RP Wachter, S (reprint author), Natl Opt Astron Observ, Cerro Tololo Inter Amer Observ, Casilla 603, La Serena, Chile. NR 32 TC 16 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2000 VL 534 IS 1 BP 367 EP 372 DI 10.1086/308754 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TC UT WOS:000087183300035 ER PT J AU Gu, PG Vishniac, ET Cannizzo, JK AF Gu, PG Vishniac, ET Cannizzo, JK TI Thermal equilibrium curves and turbulent mixing in Keplerian accretion disks SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; novae, cataclysmic variables; turbulence; X-rays : stars ID WEAKLY MAGNETIZED DISKS; ACTIVE GALACTIC NUCLEI; DWARF-NOVA OUTBURSTS; LOCAL SHEAR INSTABILITY; VERTICAL STRUCTURE; ROTATING STARS; COOLING FRONTS; SOLAR NEBULA; MODEL; TRANSPORT AB We consider vertical heat transport in Keplerian accretion disks, including the effects of radiation, convection, and turbulent mixing driven by the Balbus-Hawley instability, in astronomical systems ranging from dwarf novae (DNe) and soft X-ray transients (SXTs) to active galactic nuclei (AGNs). In order to account for the interplay between convective and turbulent energy transport in a shearing environment, we propose a modified, anisotropic form of mixing-length theory that includes radiative and turbulent damping. We also include turbulent heat transport, which acts everywhere within disks, regardless of whether or not they are stably stratified and can move entropy in either direction. We have generated a series of vertical structure models and thermal equilibrium curves using the scaling law for the viscosity parameter alpha suggested by the exponential decay of the X-ray luminosity in SXTs. We have also included equilibrium curves for DNe using an cc that is constant down to a small magnetic Reynolds number (similar to 10(4)). Our models indicate that weak convection is usually eliminated by turbulent radial mixing, even when mixing length estimates of convective vertical heat transport are much larger than turbulent heat transport. The substitution of turbulent heat transport for convection is more important on the unstable branches of thermal equilibrium S curves when alpha is larger. The low temperature turnover points Sigma(max) on the equilibrium S curves are significantly reduced by turbulent mixing in DN and SXT disks. However, in AGN disks the standard mixing-length theory for convection is still a useful approximation when we use the scaling law for alpha since these disks are very thin at the relevant radii. In accordance with previous work, we find that constant alpha models give almost vertical S curves in the Sigma-T plane and consequently imply very slow, possibly oscillating, cooling waves. C1 Univ Texas, Dept Phys, Austin, TX 78712 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Gu, PG (reprint author), Univ Texas, Dept Phys, Austin, TX 78712 USA. OI Vishniac, Ethan/0000-0002-2307-3857 NR 66 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2000 VL 534 IS 1 BP 380 EP 397 DI 10.1086/308726 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TC UT WOS:000087183300037 ER PT J AU Cannizzo, JK AF Cannizzo, JK TI On the role of irradiation and evaporation in strongly irradiated accretion disks in the black hole X-ray binaries: Toward an understanding of FREDs and secondary maxima SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; black hole physics; stars : individual (A0620-00) ID DWARF NOVA OUTBURSTS; COOLING FRONTS; MODEL; DECAY; INSTABILITY; ATMOSPHERES; QUIESCENCE; EVOLUTION; VISCOSITY; CORONAE AB We examine a new paradigm to account for the exponential decay seen in the light curves of some of the bright X-ray novae. These systems show an exponential decay in soft X-rays with an e-folding time constant of similar to 30 days. We investigate a scenario in which evaporation of matter into a corona is the dominant mass removal mechanism from the accretion disk. We utilize the thermal evaporative instability discovered by Shaviv & Wehrse. First we parametrize local mass-loss rates from the disk (fitted to vertical structure computations of the optically thin structure using the photoionization code CLOUDY), and then we utilize the scalings in our numerical time-dependent model for the decay. Both the similar to 30 day e-folding timescale for the decay and the secondary maximum with its rapid rise time of similar to 1-3 days which is seen in the X-ray nova light curves can be produced by adjusting the strength of the evaporation. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Cannizzo, JK (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 38 TC 14 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2000 VL 534 IS 1 BP L35 EP L38 DI 10.1086/312650 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TD UT WOS:000087183400009 ER PT J AU Canuto, VM AF Canuto, VM TI Semiconvection and overshooting: Schwarzschild and Ledoux criteria revisited SO ASTROPHYSICAL JOURNAL LA English DT Article DE convection; stars : interiors; turbulence ID STARS; EVOLUTION; CONVECTION; DIFFUSION AB We show that the Schwarzschild formalism, if accepted as the description of the structure of a semiconvective region, necessarily implies overshooting. The Ledoux formalism (if accepted) can be used without overshooting, provided a new relation for the mixing-length parameter or is satisfied. Should the latter not be satisfied, the Ledoux formalism would also require overshooting, that is, a nonlocal convection model. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Dept Appl Phys, New York, NY 10027 USA. RP Canuto, VM (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 10 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2000 VL 534 IS 1 BP L113 EP L115 DI 10.1086/312654 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TD UT WOS:000087183400028 ER PT J AU Hurley, K Cline, T Mazets, E Aptekar, R Golenetskii, S Frederiks, D Frail, D Kulkarni, S Trombka, J McClanahan, T Starr, R Goldsten, J AF Hurley, K Cline, T Mazets, E Aptekar, R Golenetskii, S Frederiks, D Frail, D Kulkarni, S Trombka, J McClanahan, T Starr, R Goldsten, J TI Interplanetary network localization of GRB 991208 and the discovery of its afterglow SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts ID GAMMA-RAY BURST; 28 FEBRUARY 1997 AB The extremely energetic (similar to 10(-4) ergs cm(-2)) gamma-ray burst (GRB) of 1999 December 8 was triangulated to an similar to 14 arcmin(2) error box similar to 1.8 days after its arrival at Earth with the third interplanetary network (IPN), which consists of the Ulysses, Near-Earth Asteroid Rendezvous, and Wind spacecraft. Radio observations with the Very Large Array similar to 2.7 days after the burst revealed a bright fading counterpart whose position is consistent with that of an optical transient source with a redshift of 0.707. We present the time history, peak flux, fluence, and refined 1.3 arcmin(2) error box of this event and discuss its energetics. This is the first time that a counterpart has been found for a GRB localized only by the IPN. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia. Natl Radio Astron Observ, Socorro, NM 87801 USA. CALTECH, Palomar Observ, Pasadena, CA 91125 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. RP Hurley, K (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RI McClanahan, Timothy/C-8164-2012; Frederiks, Dmitry/C-7612-2014; Aptekar, Raphail/B-3456-2015; Golenetskii, Sergey/B-3818-2015 NR 20 TC 19 Z9 19 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2000 VL 534 IS 1 BP L23 EP L25 DI 10.1086/312645 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TD UT WOS:000087183400006 ER PT J AU Torii, K Gotthelf, EV Vasisht, G Dotani, T Kinugasa, K AF Torii, K Gotthelf, EV Vasisht, G Dotani, T Kinugasa, K TI A giant glitch in the energetic 69 millisecond X-ray pulsar AXS J161730-505505 SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : general; pulsars : individual (AXS J161730-505505, PSR J1617-5055); stars : neutron; supernova remnants; X-rays : general ID SUPERNOVA REMNANT RCW-103 AB We present new results on the recently discovered 69 ms X-ray pulsar AXS J161730-505505, the sixth youngest example of a rotation-powered pulsar. We have undertaken a comprehensive X-ray-observing campaign of AXS J161730-505505 with the ASCA, BeppoSAX, and RXTE observatories and follow its long-term spin-down history between 1989 and 1999 using these observations and archival Ginga and ASCA data sets. The spin-down is not simply described by a linear function as originally thought, but instead we find evidence of a giant glitch (\Delta P/P \ greater than or equal to 10(-6)) between 1993 August and 1997 September, perhaps the largest yet observed from a young pulsar. The glitch is well described by steps in P and (P)over dot accompanied by a persistent P similar to those seen in the Vela pulsar. The pulse profile of AXS J161730-505505 presents a single asymmetric peak that is maintained over all observation epochs. The energy spectrum is also steady over time, characterized by a highly absorbed power law with a photon index Gamma = 1.4 +/- 0.2, consistent with that found for other young rotation powered pulsars. C1 Natl Space Develop Agcy Japan, Tsukuba Space Ctr, Space Utilizat Res Program, Tsukuba, Ibaraki 3058505, Japan. Columbia Astrophys Lab, New York, NY 10027 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. Gunma Astron Observ, Agatsuma, Gunma 3770702, Japan. RP Torii, K (reprint author), Natl Space Develop Agcy Japan, Tsukuba Space Ctr, Space Utilizat Res Program, 2-1-1 Sengen, Tsukuba, Ibaraki 3058505, Japan. NR 17 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2000 VL 534 IS 1 BP L71 EP L74 DI 10.1086/312656 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316TD UT WOS:000087183400018 ER PT J AU Snowden, SL Freyberg, MJ Kuntz, KD Sanders, WT AF Snowden, SL Freyberg, MJ Kuntz, KD Sanders, WT TI A catalog of soft X-ray shadows, and more contemplation of the 1/4 keV background SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE catalogs; galaxy : general; ISM : general; X-rays : galaxies; X-rays : general ID OPTICALLY THIN PLASMAS; INTERSTELLAR-MEDIUM; GALACTIC HALO; DRACO NEBULA; ROSAT PSPC; DIFFUSE; EMISSION; SPECTRUM; CLOUDS; MAPS AB This paper presents a catalog of shadows in the 1/4 keV soft X-ray diffuse background (SXRB) that were identified by a comparison between ROSAT All-Sky Survey maps and DIRBE-corrected IRAS 100 mu m maps. These "shadows" are the negative correlations between the surface brightness of the SXRB and the column density of the Galactic interstellar medium (ISM) over limited angular regions (a few degrees in extent). We have compiled an extensive but not exhaustive set of 378 shadows in the polar regions of the Galaxy (\b\ greater than or similar to 20 degrees) and determined their foreground and background X-ray intensities (relative to the absorbing features) and the respective hardness ratios of that emission. The portion of the sky that was examined to find these shadows was restricted in general to regions where the minimum column density is less than or similar to 4 x 10(20) H cm(-2), i.e., relatively high Galactic latitudes, and to regions away from distinct extended features in the SXRB such as supernova remnants and superbubbles. The results for the foreground intensities agree well with the recent results of a general analysis of the local a keV emission, while the background intensities show additional, but not unexpected scatter. The results also confirm the existence of a gradient in the hardness of the local 1/4 keV emission along a Galactic center/anticenter axis with a temperature that varies from 10(6.13) to 10(6.02) K, respectively. The average temperature of the foreground component from this analysis is 10(6.08) K, compared to 10(6.06) K in the previous analysis. Likewise, the average temperature for the distant component for the current and previous analyses are 10(6.00) and 10(6.02) K, respectively. Finally, the results for the 1/4 keV halo emission are compared to the observed fluxes at 3/4 keV, where the lack of correlation suggests that the Galactic halo's 1/4 and 3/4 keV fluxes are likely produced by separate emission regions. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Univ Wisconsin, Dept Phys, Madison, WI 53706 USA. RP Snowden, SL (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. RI Snowden, Steven/D-5292-2012 NR 57 TC 78 Z9 78 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD MAY PY 2000 VL 128 IS 1 BP 171 EP 212 DI 10.1086/313378 PG 42 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 344FV UT WOS:000088749300007 ER PT J AU Dotson, JL Davidson, J Dowell, CD Schleuning, DA Hildebrand, RH AF Dotson, JL Davidson, J Dowell, CD Schleuning, DA Hildebrand, RH TI Far-infrared polarimetry of Galactic clouds from the Kuiper Airborne Observatory SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE catalogs; HII regions; ISM : clouds; ISM : magnetic fields; polarization ID MOLECULAR CLOUD; ARRAY POLARIMETRY; SAGITTARIUS B2; CENTER ARC; POLARIZATION; EMISSION; REGION; M17; GALAXY; HERTZ AB In this paper we present a complete summary of the data obtained with the far-infrared polarimeter, Stokes, in flights of the Kuiper Airborne Observatory. We have observed 12 Galactic clouds and have made over 1100 individual measurements at 100 mu m and 60 mu m. The median P for all of the 60 mu m and 100 mu m measurements is 3.6% and 2.6% respectively. We also present flux maps obtained simultaneously with the polarimetry. C1 NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, USRA, Moffett Field, CA 94035 USA. CALTECH, Pasadena, CA 91125 USA. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Dotson, JL (reprint author), NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. NR 29 TC 78 Z9 79 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD MAY PY 2000 VL 128 IS 1 BP 335 EP 370 DI 10.1086/313384 PG 36 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 344FV UT WOS:000088749300013 ER PT J AU Chen, P Pearson, JC Pickett, HM Matsuura, S Blake, GA AF Chen, P Pearson, JC Pickett, HM Matsuura, S Blake, GA TI Submillimeter-wave measurements and analysis of the ground and v(2)=1 states of water SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE infrared : ISM : lines and bands; ISM : molecules; methods : laboratory; molecular data ID POTENTIAL-ENERGY SURFACE; PADE HAMILTONIAN OPERATOR; HIGH-RESOLUTION SPECTRUM; DIPOLE-MOMENT FUNCTION; ROTATIONAL LEVELS; LINE POSITIONS; TRIATOMIC-MOLECULES; BAND INTENSITIES; FTS MEASUREMENTS; H2O AB In order to facilitate further studies of water in the interstellar medium, the envelopes of late-type stars, jets, and shocked regions, the frequencies of 17 newly measured H-2 O-16 transitions between 0.841 and 1.575 THz are reported. A complete update of the available water line frequencies and a detailed calculation of unmeasured rotational transitions and transition intensities as a function of temperature are presented for the ground and nu(2) = 1 state levels below 3000 cm(-1) of excitation energy. The new terahertz transitions were measured with a recently developed laser difference frequency spectrometer. Six of these transitions arise from the nu(2) = 1 state, and the other 11 are in the ground state; all have lower state energies from 700 to 1750 cm(-1) and should be accessible to Stratospheric Observatory For Infrared Astronomy (SOFIA) through the atmosphere. The transitions near 0.850 THz are accessible from the ground with existing receivers. Observations of the newly measured nu(2) = 1 state transitions, which include the 1(1.1)-0(0.0) fundamental at 1.2057 THz and five other very low J transitions, should provide valuable insights into role played by the nu(2) = 1 state in the cooling dynamics of jets, shocks, masers, and strongly infrared-pumped regions. The line list is presented to assist in the planning of observational campaigns with the Far-infrared Space Telescope (FIRST) and other proposed space missions with which a full suite of water observations can be carried out. C1 Natl Inst Stand & Technol, Div Time & Frequency, Boulder, CO 80303 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. RP Chen, P (reprint author), Natl Inst Stand & Technol, Div Time & Frequency, Mail Stop 847-10,325 Broadway, Boulder, CO 80303 USA. RI Chen, Pin/B-1112-2008; Matsuura, Shuji/B-5658-2016 OI Chen, Pin/0000-0003-1195-9666; Matsuura, Shuji/0000-0002-5698-9634 NR 48 TC 28 Z9 28 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD MAY PY 2000 VL 128 IS 1 BP 371 EP 385 DI 10.1086/313377 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 344FV UT WOS:000088749300014 ER PT J AU Bellan, J AF Bellan, J TI Perspectives on large eddy simulations for sprays: Issues and solutions SO ATOMIZATION AND SPRAYS LA English DT Article ID DIRECT NUMERICAL-SIMULATION; FREE SHEAR-LAYER; TURBULENT CHANNEL FLOW; PLANE MIXING LAYER; PARTICLE DISPERSION; ISOTROPIC TURBULENCE; 2-PHASE; TRANSPORT; MODELS; DEPOSITION AB A review of the large eddy simulations (LES) methodology is presented in the context of sprays. Issues related to modeling both the drop interaction with the carrier flow and the interaction among drops are discussed. Appropriate direct numerical simulations (DNS) for use as precursors to LES, and the extraction of subgrid scale (SGS) models are both described. Particular attention is devoted to LES aspects which are different from those of single-phase flows. These include the correct portrayal of the drop interaction with small turbulent scales, the modeling of SGS stresses, SGS heat and SGS species fluxes, and the accurate representation in the carrier flow equations of the source terms associated with the presence of the drops. Recommendations for future work are also offered. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bellan, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 52 TC 22 Z9 22 U1 0 U2 2 PU BEGELL HOUSE INC PI NEW YORK PA 79 MADISON AVE, SUITE 1205, NEW YORK, NY 10016-7892 USA SN 1044-5110 J9 ATOMIZATION SPRAY JI Atom. Sprays PD MAY-OCT PY 2000 VL 10 IS 3-5 BP 409 EP 425 PG 17 WC Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical; Materials Science, Multidisciplinary; Physics, Applied SC Engineering; Materials Science; Physics GA 335QD UT WOS:000088254600007 ER PT J AU Nelson, RF Kimes, DS Salas, WA Routhier, M AF Nelson, RF Kimes, DS Salas, WA Routhier, M TI Secondary forest age and tropical forest biomass estimation using thematic mapper imagery SO BIOSCIENCE LA English DT Article ID LAND-USE; SATELLITE DATA; DEFORESTATION; CARBON; AMAZONIA; VEGETATION; BRAZIL; CONVERSION; PATTERNS; RONDONIA C1 NASA, Biospher Sci Branch, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ New Hampshire, Complex Syst Res Ctr, Durham, NH 03824 USA. RP Nelson, RF (reprint author), NASA, Biospher Sci Branch, Goddard Space Flight Ctr, Code 923, Greenbelt, MD 20771 USA. RI Nelson, Ross/H-8266-2014 NR 36 TC 90 Z9 97 U1 1 U2 9 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 MAY PY 2000 VL 50 IS 5 BP 419 EP 431 DI 10.1641/0006-3568(2000)050[0419:SFAATF]2.0.CO;2 PG 13 WC Biology SC Life Sciences & Biomedicine - Other Topics GA 310CJ UT WOS:000086808700005 ER PT J AU Koenig, CC Coleman, FC Grimes, CB Fitzhugh, GR Scanlon, KM Gledhill, CT Grace, M AF Koenig, CC Coleman, FC Grimes, CB Fitzhugh, GR Scanlon, KM Gledhill, CT Grace, M TI Protection of fish spawning habitat for the conservation of warm-temperate reef-fish fisheries of shelf-edge reefs of Florida SO BULLETIN OF MARINE SCIENCE LA English DT Article; Proceedings Paper CT 2nd William R and Lenore Mote International Symposium in Fisheries Ecology CY NOV 04-06, 1998 CL SARASOTA, FLORIDA SP Environm Defense Fund, Ctr Marine Conservat, Amer Fisheries Soc, Marine Fisheries Sect ID SOUTHEASTERN UNITED-STATES; MYCTEROPERCA-MICROLEPIS; CONTINENTAL-SHELF; OCULINA-VARICOSA; CORAL-REEFS; ATLANTIC; GULF; CONSEQUENCES; AGGREGATIONS; DISTURBANCE AB We mapped and briefly describe the surficial geology of selected examples of shelf-edge reefs (50 - 120 m deep) of the southeastern United States, which are apparently derived from ancient Pleistocene shorelines and are intermittently distributed throughout the region. These reefs are ecologically significant because they support a diverse array of fish and invertebrate species, and they are the only aggregation spawning sites of gag (Mycteroperca microlepis), scamp (M. phenax), and other economically important reef fish. Our studies on the east Florida shelf in the Experimental Oculina Research Reserve show that extensive damage to the habitat-structuring coral Oculina varicosa has occurred in the past, apparently from trawling and dredging activities of the 1970s and later. On damaged or destroyed Oculina habitat, reef-fish abundance and diversity are low, whereas on intact habitat, reef-fish diversity is relatively high compared to historical diversity on the same site. The abundance and biomass of the economically important reef fish was much higher in the past than it is now, and spawning aggregations of gag and scamp have been lost or greatly reduced in size. On the west Florida shelf, fishers have concentrated on shelf-edge habitats for over 100 yrs, but fishing intensity increased dramatically in the 1980s. Those reefs are characterized by low abundance of economically important species. The degree and extent of habitat damage there is unknown. We recommend marine fishery reserves to protect habitat and for use in experimentally examining the potential production of unfished communities. C1 Florida State Univ, Dept Biol Sci, Inst Fishery Resource Ecol, Tallahassee, FL 32306 USA. Natl Marine Fisheries Serv, Tiburon Lab, Tiburon, CA 94920 USA. Natl Marine Fisheries Serv, Panama City Lab, Panama City, FL 32408 USA. US Geol Survey, Woods Hole, MA 02543 USA. Natl Marine Fisheries Serv, Pascagoula Lab, Pascagoula, MS 39563 USA. RP Koenig, CC (reprint author), Florida State Univ, Dept Biol Sci, Inst Fishery Resource Ecol, B-157, Tallahassee, FL 32306 USA. NR 78 TC 93 Z9 97 U1 2 U2 7 PU ROSENSTIEL SCH MAR ATMOS SCI PI MIAMI PA 4600 RICKENBACKER CAUSEWAY, MIAMI, FL 33149 USA SN 0007-4977 J9 B MAR SCI JI Bull. Mar. Sci. PD MAY PY 2000 VL 66 IS 3 BP 593 EP 616 PG 24 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA 346WP UT WOS:000088894300007 ER PT J AU Geerts, B Heymsfield, GM Tian, L Halverson, JB Guillory, A Mejia, MI AF Geerts, B Heymsfield, GM Tian, L Halverson, JB Guillory, A Mejia, MI TI Hurricane Georges's landfall in the Dominican Republic: Detailed airborne Doppler radar imagery SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID TROPICAL CYCLONES; MELTING LAYER; FLORIDA; EVOLUTION; AIRCRAFT; TYPHOONS; SYSTEM AB Current understanding of landfalling tropical cyclones is limited, especially with regard to convective-scale processes. On 22 September 1998 Hurricane Georges made landfall on the island of Hispaniola, leaving behind a trail of death and devastation, largely the result of excessive rainfall, not storm surge or wind. Detailed airborne measurements were taken as part of the Third Convection and Moisture Experiment. Of particular interest are the ER-2 nadir X-band Doppler radar data, which provide a first-time, high-resolution view of the precipitation and airflow changes as a hurricane interacts with mountainous terrain. The circulation of Hurricane Georges obviously declined during landfall, evident in the rapid increase in minimum sea level pressure, the subsidence of the eyewall anvil, and the decrease in average ice concentrations in the eyewall. The eye, as seen in satellite imagery, disappeared as deep convection erupted within the eye. The main convective event within the eye, with upper-level updraft magnitudes over 20 m s(-1) and microwave brightness temperatures below 100 K at 89 GHz (implying large ice concentrations), occurred when the eye moved over the Cordillera Central, the island's main mountain chain. The location, intensity and evolution of this convection indicate that it was coupled to the surface orography. The authors speculate that orographic lifting released potential energy, which had been trapped beneath the eye's subsidence inversion. It is likely that surface rain rates increased during landfall, both in the convective and in the more widespread stratiform rainfall areas over the island. Evidence for this is the increase in radar reflectivity below the bright band down to ground level. Such increase was absent offshore. This low-level rain enhancement must be due to the ascent of boundary layer air over the topography. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Oficina Nacl Meteorol, Santa Domingo, Dominican Rep. RP Geerts, B (reprint author), Univ Wyoming, Dept Atmospher Sci, Laramie, WY 82071 USA. NR 44 TC 34 Z9 36 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 2000 VL 81 IS 5 BP 999 EP 1018 DI 10.1175/1520-0477(2000)081<0999:HGLITD>2.3.CO;2 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 306FY UT WOS:000086587700002 ER PT J AU DeFelice, TP Meyer, DJ Xian, G Christopherson, J Cahalan, R AF DeFelice, TP Meyer, DJ Xian, G Christopherson, J Cahalan, R TI Landsat-7 reveals more than just surface features in remote areas of the globe SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Letter C1 Raytheon Co, EROS Data Ctr, Dept Sci, Sci & Applicat Branch, Sioux Falls, SD USA. Raytheon Co, EROS Data Ctr, Satellite Syst Engn & Dev Dept, Satellite Syst Branch, Sioux Falls, SD USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP DeFelice, TP (reprint author), Raytheon Co, EROS Data Ctr, Dept Sci, Sci & Applicat Branch, Sioux Falls, SD USA. RI Cahalan, Robert/E-3462-2012 OI Cahalan, Robert/0000-0001-9724-1270 NR 1 TC 10 Z9 10 U1 0 U2 1 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 2000 VL 81 IS 5 BP 1047 EP 1049 PG 3 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 306FY UT WOS:000086587700006 ER PT J AU Druyan, LM Shah, KP Chandler , MA Rind, D AF Druyan, LM Shah, KP Chandler , MA Rind, D TI GCM hindcasts of SST forced climate variability over agriculturally intensive regions SO CLIMATIC CHANGE LA English DT Article ID GENERAL-CIRCULATION MODEL; MICROWAVE SOUNDING UNIT; SURFACE TEMPERATURE ANOMALIES; BRAZIL RAINFALL ANOMALIES; NORTHEAST BRAZIL; SOUTHERN OSCILLATION; DIAGNOSTIC-TOOL; ONLINE TRACERS; ANNUAL CYCLE; PRECIPITATION AB The NASA/Goddard Institute for Space Studies (GISS) climate model is forced with globally observed sea-surface temperatures (SST) in five simulations, 1969-1991, with individual runs beginning from altered initial atmospheric conditions. The interannual variability of modeled anomalies of the Southern Oscillation Index, mid-tropospheric temperatures, 850 mb zonal winds and Outgoing Longwave Radiation over the tropical Pacific Ocean, which has the largest SST anomaly forcing, are strongly correlated with observed trends which reflect ENSO cycles. The model's rainfall variability over three agriculturally intensive regions, two tropical and one mid-latitude, is investigated in order to evaluate the potential usefulness of GCM predictions for agricultural planning. The correct sign of Zimbabwe seasonal precipitation anomalies was hindcast within a useful range of consensus only for select seasons corresponding to extreme ENSO events for which anomalous circulation patterns were rather realistically simulated. The correlation between hindcasts of Nordeste monthly precipitation and observations increases with time smoothing, reaching 0.64 for 5-month running means. Consensus between individual runs is directly proportional to the absolute value of Nino3 SST so that during El Nino and La Nina years most simulations agree on the sign of predicted Nordeste rainfall anomalies. We show that during selected seasons the upper tropospheric divergent circulation and near surface meridional displacements of the ITCZ are realistically represented by the ensemble mean of the simulations. This realistic simulation of both the synoptic mechanisms and the resulting precipitation changes increases confidence in the GCM's potential for seasonal climate prediction. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Ctr Climate Syst Res, New York, NY 10025 USA. RP Druyan, LM (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 42 TC 3 Z9 3 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0165-0009 J9 CLIMATIC CHANGE JI Clim. Change PD MAY PY 2000 VL 45 IS 2 BP 279 EP 322 DI 10.1023/A:1005571213805 PG 44 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA 323FM UT WOS:000087554400001 ER PT J AU Stothers, RB AF Stothers, RB TI Climatic and demographic consequences of the massive volcanic eruption of 1258 SO CLIMATIC CHANGE LA English DT Article ID CENTRAL ENGLAND TEMPERATURES; SOUTHERN OSCILLATION EVENTS; GREENLAND ICE CORE; SUMMER TEMPERATURES; EXPLOSIVE VOLCANISM; RECORDS; SIGNAL; EUROPE; IMPACT; TELECONNECTIONS AB Somewhere in the tropics, a volcano exploded violently during the year 1258, producing a massive stratospheric aerosol veil that eventually blanketed the globe. Arctic and Antarctic ice cores suggest that this was the world's largest volcanic eruption of the past millennium. According to contemporary chronicles, the stratospheric dry fog possibly manifested itself in Europe as a persistently cloudy aspect of the sky and also through an apparently total darkening of the eclipsed Moon. Based on a sudden temperature drop for several months in England, the eruption's initiation date can be inferred to have been probably January 1258. The frequent cold and rain that year led to severe crop damage and famine throughout much of Europe. Pestilence repeatedly broke out in 1258 and 1259; it occurred also in the Middle East, reportedly there as plague. Another very cold winter followed in 1260-1261. The troubled period's wars, famines, pestilences, and earthquakes appear to have contributed in part to the rise of the European flagellant movement of 1260, one of the most bizarre social phenomena of the Middle Ages. Analogies can be drawn with the climatic aftereffects and European social unrest following another great tropical eruption, Tambora in 1815. Some generalizations about the climatic impacts of tropical eruptions are made from these and other data. C1 NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. RP Stothers, RB (reprint author), NASA, Goddard Space Flight Ctr, Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 94 TC 55 Z9 56 U1 2 U2 15 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0165-0009 J9 CLIMATIC CHANGE JI Clim. Change PD MAY PY 2000 VL 45 IS 2 BP 361 EP 374 DI 10.1023/A:1005523330643 PG 14 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA 323FM UT WOS:000087554400004 ER PT J AU Olson, SL T'ien, JS AF Olson, SL T'ien, JS TI Buoyant low-stretch diffusion flames beneath cylindrical PMMA samples SO COMBUSTION AND FLAME LA English DT Article ID EXTINCTION; MICROGRAVITY; COMBUSTION; FUEL AB To study flame structure and extinction characteristics in low-stretch environments, a normal gravity low-stretch diffusion flame was established beneath a cylindrical PMMA sample of varying large radii. Burning rates, visible flame thickness, visible flame standoff distance, temperature profiles in the solid and gas, and radiative loss from the system were measured. A transition from the blowoff side of the flammability map to the quenching side of the flammability map was observed at approximately 6-7 s(-1), as determined by curvefits to the nonmonotonic trends in peak temperatures, solid and gas-phase temperature gradients, and nondimensional standoff distances. A surface energy balance reveals that the fraction of heat transfer from the flame that is lost to in-depth conduction and surface radiation increases with decreasing stretch until quenching extinction is observed. This is primarily due to decreased heat transfer from the flame, while the magnitude of the losses remains the same. A unique local extinction flamelet phenomenon and associated preextinction oscillations are observed at very low stretch. An ultimate quenching extinction limit is found at low stretch with sufficiently high induced heat losses. (C) 2000 by The Combustion Institute. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Case Western Reserve Univ, Cleveland, OH 44106 USA. RP Olson, SL (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 21 TC 33 Z9 33 U1 0 U2 2 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 MAY PY 2000 VL 121 IS 3 BP 439 EP 452 DI 10.1016/S0010-2180(99)00161-3 PG 14 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA 296XD UT WOS:000086051300004 ER PT J AU Okai, K Moriue, O Araki, M Tsue, M Kono, M Sato, J Dietrich, DL Williams, FA AF Okai, K Moriue, O Araki, M Tsue, M Kono, M Sato, J Dietrich, DL Williams, FA TI Pressure effects on combustion of methanol and methanol/dodecanol single droplets and droplet pairs in microgravity SO COMBUSTION AND FLAME LA English DT Article ID FUEL DROPLETS; REDUCED-GRAVITY; EXTINCTION; TRANSPORT; DIFFUSION; WATER; MASS AB This paper presents the results of an experimental investigation on the combustion of single droplets and two-droplet arrays of pure methanol and methanol/dodecanol mixtures in air under microgravity conditions. The initial droplet diameters d(0), were nominally 0.9 mm. The independent experimental variables were the ambient pressure (0.1-9.0 MPa), fuel mixture ratio (methanol/dodecanol: 100/0-15/85), and interdroplet separation distance l (l/d(0) = 2.3-8.0). For pure methanol, the results show that the droplet lifetime decreases with increasing interdroplet separation distances at low pressures. At higher pressures (3.0 MPa and above) the droplet lifetime was independent of separation distance. The flame extinguished at a finite droplet size only for pure methanol at 0.1 MPa, in qualitative agreement with theoretical predictions. The extinction droplet diameter was nearly independent of the droplet spacing. Methanol/dodecanol-mixture droplets exhibited microexplosion for both single droplets and droplet arrays. The paper presents maps of the disruption regime for both single droplets and droplet pairs, The difference between the disruptive behavior of single droplets and droplet pairs is explained by differences in liquid-phase circulation induced by the gas-phase asymmetry of the droplet pair. The paper also presents results of the dependence of the onset of disruption (in terms of both volume and time) on the pressure and initial fuel mixture ratio. (C) 2000 by The Combustion Institute. C1 Univ Tokyo, Tokyo 1138656, Japan. Ishikawajima Harima Heavy Ind Co Ltd, Tokyo 1350061, Japan. NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. Univ Calif San Diego, La Jolla, CA 92093 USA. RP Okai, K (reprint author), Univ Tokyo, Tokyo 1138656, Japan. NR 30 TC 25 Z9 26 U1 1 U2 8 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 MAY PY 2000 VL 121 IS 3 BP 501 EP 512 DI 10.1016/S0010-2180(99)00160-1 PG 12 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA 296XD UT WOS:000086051300008 ER PT J AU Morris, RA Khatib, L AF Morris, RA Khatib, L TI Introduction to the special issue on time and temporal reasoning SO COMPUTATIONAL INTELLIGENCE LA English DT Editorial Material C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Morris, RA (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL PUBLISHERS PI MALDEN PA 350 MAIN STREET, STE 6, MALDEN, MA 02148 USA SN 0824-7935 J9 COMPUT INTELL JI Comput. Intell. PD MAY PY 2000 VL 16 IS 2 BP 135 EP 136 DI 10.1111/0824-7935.00109 PG 2 WC Computer Science, Artificial Intelligence SC Computer Science GA 304BQ UT WOS:000086463100001 ER PT J AU Morris, RA Khatib, L AF Morris, RA Khatib, L TI Constraint reasoning about repeating events: Satisfaction and optimization SO COMPUTATIONAL INTELLIGENCE LA English DT Article DE constraint satisfaction; temporal reasoning; constraint optimization; repeating events AB Effective manipulation of temporal information about periodic events is required for solving complex problems such as long-range scheduling or querying temporal information. Furthermore, many problems involving repeating events involve the optimization of temporal aspects of these events (e.g., minimizing make-span in job-shop scheduling). In this paper, a constraint-based formulation of reasoning problems with repeating events is presented, and its complexity is analyzed for a range of problems. Optimization constraints are interpreted formally using the Semiring CSPs (SCSP) representation of optimization in constraint reasoning. This allows for familiar algorithms such as branch-and-bound to be applied to solving them. C1 NASA, Adv Comp Sci Res Inst, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, RECOM, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Morris, RA (reprint author), NASA, Adv Comp Sci Res Inst, Ames Res Ctr, M-S 19-39, Moffett Field, CA 94035 USA. EM morris@ptolemy.arc.nasa.gov; lina@ptolemy.arc.nasa.gov NR 17 TC 0 Z9 0 U1 0 U2 2 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 0824-7935 EI 1467-8640 J9 COMPUT INTELL-US JI Comput. Intell. PD MAY PY 2000 VL 16 IS 2 BP 257 EP 278 DI 10.1111/0824-7935.00113 PG 22 WC Computer Science, Artificial Intelligence SC Computer Science GA 304BQ UT WOS:000086463100005 ER PT J AU Patnaik, SN Coroneos, RM Hopkins, DA AF Patnaik, SN Coroneos, RM Hopkins, DA TI Substructuring for structural optimization in a parallel processing environment SO COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING LA English DT Review ID ALGORITHMS; STRATEGY AB Design optimization of large structures can be attempted through a substructure strategy. In this strategy the structure is divided into smaller substructures that are clustered to obtain a sequence of subproblems. Solution to the large problem is obtained iteratively through repeated solutions to the modest subproblems. Substructure strategies, in sequential and parallel computational environments on a Cray-YMP computer have been implemented in a design test bed CometBoards. The issues encountered during substructure solution and their resolution are discussed under (I) coupling and constraint formulation, (2) differences in optimal solutions, and (3) amount of computation. Coupling between subproblems and separating constraints into local and global sets promote convergence of the iterative process. The substructure strategy can converge to different local optimal designs with equal minimum weight. Substructure optimization can be computation-intensive. However in a parallel computational mode, it can effectively use assigned processors. C1 Ohio Aerosp Inst, Brook Pk, OH 44142 USA. NASA, Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. RP Patnaik, SN (reprint author), Ohio Aerosp Inst, Brook Pk, OH 44142 USA. NR 38 TC 3 Z9 3 U1 0 U2 4 PU BLACKWELL PUBLISHERS PI MALDEN PA 350 MAIN STREET, STE 6, MALDEN, MA 02148 USA SN 1093-9687 J9 COMPUT-AIDED CIV INF JI Comput.-Aided Civil Infrastruct. Eng. PD MAY PY 2000 VL 15 IS 3 BP 209 EP 226 DI 10.1111/0885-9507.00185 PG 18 WC Computer Science, Interdisciplinary Applications; Construction & Building Technology; Engineering, Civil; Transportation Science & Technology SC Computer Science; Construction & Building Technology; Engineering; Transportation GA 373VC UT WOS:000165309100005 ER PT J AU Atkinson, P Quattrochi, DA AF Atkinson, P Quattrochi, DA TI Introduction to this special issue on Geostatistics and Geospatial Techniques in Remote Sensing SO COMPUTERS & GEOSCIENCES LA English DT Editorial Material C1 Univ Southampton, Dept Geog, Southampton SO17 1BJ, Hants, England. NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35812 USA. RP Atkinson, P (reprint author), Univ Southampton, Dept Geog, Southampton SO17 1BJ, Hants, England. RI Atkinson, Peter/L-9508-2013 NR 0 TC 4 Z9 4 U1 1 U2 11 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0098-3004 J9 COMPUT GEOSCI JI Comput. Geosci. PD MAY PY 2000 VL 26 IS 4 BP 359 EP 359 DI 10.1016/S0098-3004(99)00116-8 PG 1 WC Computer Science, Interdisciplinary Applications; Geosciences, Multidisciplinary SC Computer Science; Geology GA 302CF UT WOS:000086346800001 ER PT J AU Glatzmaier, GA Clune, T AF Glatzmaier, GA Clune, T TI Computational aspects of geodynamo simulations SO COMPUTING IN SCIENCE & ENGINEERING LA English DT Article ID ROTATING SPHERICAL-SHELL; COMPUTER-SIMULATION; THERMAL-CONVECTION; INNER-CORE; DYNAMO; DRIVEN; MODEL AB For almost 50 years, researchers have attempted to understand the geodynamo, a mechanism that maintains the Earth's geomagnetic field. Here, the authors discuss their results using the Glatzmaier-Roberts model to create numerical simulations of the geodynamo. C1 Univ Calif Santa Cruz, Ctr Origin Dynam & Evolut Planets, Dept Earth Sci, Santa Cruz, CA 95064 USA. NASA, Goddard Space Flight Ctr, SGI, Greenbelt, MD 20771 USA. RP Univ Calif Santa Cruz, Ctr Origin Dynam & Evolut Planets, Dept Earth Sci, EMS Bldg, Santa Cruz, CA 95064 USA. EM glatz@es.ucsc.edu; clune@zot.gsfc.nasa.gov NR 16 TC 4 Z9 4 U1 0 U2 2 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1521-9615 EI 1558-366X J9 COMPUT SCI ENG JI Comput. Sci. Eng. PD MAY-JUN PY 2000 VL 2 IS 3 BP 61 EP 67 DI 10.1109/5992.841797 PG 7 WC Computer Science, Interdisciplinary Applications SC Computer Science GA 307BA UT WOS:000086632500014 ER PT J AU Booth, JG Miller, RL McKee, BA Leathers, RA AF Booth, JG Miller, RL McKee, BA Leathers, RA TI Wind-induced bottom sediment resuspension in a microtidal coastal environment SO CONTINENTAL SHELF RESEARCH LA English DT Article DE resuspension; resuspended sediments; estuarine dynamics; remote sensing regional terms; USA; Louisiana; Barataria Basin ID CHESAPEAKE BAY; WORLD RIVERS; CALIFORNIA; ESTUARY; WATER; CALIBRATION; TRANSPORT; LOUISIANA; NITROGEN; CARBON AB Bottom sediment resuspension frequency, duration, and extent (i.e. areal percent of bottom sediments affected) were characterized for the 15 month period from September 1995 to January 1997 for select water bodies within the Barataria Basin, Louisiana, USA. An empirical model of sediment resuspension as a function of water depth, wind speed, direction, and fetch was derived from surface gravity wave theory. The model was validated with water-column turbidity imagery obtained from visible and near-IR AVHRR data. Based on model predictions, wind-induced resuspension occurred during all seasons of this study. Model predictions of the critical wind speed required to induce resuspension indicate that winds of 4 m s(-1) (averaged over all wind directions) resuspend approximately 50% of bottom sediments in the water bodies examined. Winds of this magnitude (4 m s(-1)) occurred for 80% of the time during the late fall, winter, and early spring and for approximately 30% of the time during the summer. More than 50% of the bottom sediments, on an areal basis, are resuspended throughout the year, indicating the importance of resuspension as a process affecting sediment and biogeochemical fluxes in the Barataria Basin. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Earth Syst Sci Off, Stennis Space Ctr, MS 39529 USA. Tulane Univ, Inst Earth & Ecosyst Sci, Dept Geol, New Orleans, LA 70118 USA. RP Booth, JG (reprint author), NASA, Earth Syst Sci Off, SA00 Bldg 1100, Stennis Space Ctr, MS 39529 USA. NR 55 TC 47 Z9 55 U1 3 U2 19 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 MAY PY 2000 VL 20 IS 7 BP 785 EP 806 DI 10.1016/S0278-4343(00)00002-9 PG 22 WC Oceanography SC Oceanography GA 307AA UT WOS:000086630000003 ER PT J AU Beck, LR Lobitz, BM Wood, BL AF Beck, LR Lobitz, BM Wood, BL TI Remote sensing and human health: New sensors and new opportunities SO EMERGING INFECTIOUS DISEASES LA English DT Article ID SATELLITE IMAGERY; MALARIA TRANSMISSION; SPATIAL-ANALYSIS; LYME-DISEASE; TSETSE-FLIES; LANDSAT TM; VALLEY; RISK; VILLAGES; HABITATS AB Since the launch of Landsat-1 28 years ago, remotely sensed data have been used to map features on the earth's surface. An increasing number of health studies have used remotely sensed data for monitoring, surveillance, or risk mapping, particularly of vector-borne diseases. Nearly all studies used data from Landsat, the French Systeme Pour I'Observation de la Terre, and the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer. New sensor systems are in orbit, or soon to be launched, whose data may prove useful for characterizing and monitoring the spatial and temporal patterns of infectious diseases. Increased computing power and spatial modeling capabilities of geographic information systems could extend the use of remote sensing beyond the research community into operational disease surveillance and control. This article illustrates how remotely sensed data have been used in health applications and assesses earth-observing satellites that could detect and map environmental variables related to the distribution of vector-borne and other diseases. C1 Calif State Univ, Monterey Bay, CA USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Beck, LR (reprint author), Calif State Univ, Monterey Bay, CA USA. NR 33 TC 161 Z9 170 U1 0 U2 23 PU CENTER DISEASE CONTROL PI ATLANTA PA ATLANTA, GA 30333 USA SN 1080-6040 J9 EMERG INFECT DIS JI Emerg. Infect. Dis PD MAY-JUN PY 2000 VL 6 IS 3 BP 217 EP 227 PG 11 WC Immunology; Infectious Diseases SC Immunology; Infectious Diseases GA 319CB UT WOS:000087321300001 PM 10827111 ER PT J AU Hard, JJ Berejikian, BA Tezak, EP Schroder, SL Knudsen, CM Parker, LT AF Hard, JJ Berejikian, BA Tezak, EP Schroder, SL Knudsen, CM Parker, LT TI Evidence for morphometric differentiation of wild and captively reared adult coho salmon: a geometric analysis SO ENVIRONMENTAL BIOLOGY OF FISHES LA English DT Article DE relative warps; thin-plate spline; domestication; reproductive behavior; salmonid fish ID SOUTHERN BRITISH-COLUMBIA; ONCORHYNCHUS-KISUTCH; PACIFIC SALMON; PINK SALMON; REPRODUCTIVE-BEHAVIOR; ATLANTIC SALMON; BREEDING COMPETITION; BODY MORPHOLOGY; SOCKEYE-SALMON; PUGET-SOUND AB As part of a comprehensive genetic evaluation of reproduction in naturally spawning coho salmon, Oncorhynchus kisutch, we examined morphometric variation in captively reared and wild adults from Hood Canal, Washington (U.S.A.) for evidence of differentiation between these groups. We collected captively reared fish as parr from two stocks and reared to adulthood at a freshwater hatchery, maturing in 1995 and 1996; we sampled closely size-matched wild fish as they returned to a neighboring stream in both years. Multivariate analysis of shape variation by Procrustes coordinates, visualized by thin-plate splines, indicated that the captively reared adults were differentiated from the wild fish by sharply reduced sexual dimorphism as well as smaller heads and less hooked snouts, increased trunk depth, larger caudal peduncles, shorter dorsal fins, larger hindbodies and a reduction in body streamlining. The differences between the captively reared and wild fish were similar to but more pronounced than some differences previously reported between hatchery and wild coho salmon. The magnitude and pattern of differences suggested that at least some of them were environmentally induced. Shape variation showed an allometric relationship with variation in body (measured as centroid) size. Morphometric variation was a poor correlate of most spawning behaviors. Nevertheless, our results suggest that the morphometric consequences of captive rearing for mate selection and reproductive activity of spawning fish may limit its effectiveness as a restorative tool. C1 NOAA, Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Seattle, WA 98112 USA. Natl Marine Fisheries Serv, Manchester Marine Expt Stn, Manchester, WA 98353 USA. Washington Dept Fish & Wildlife, Olympia, WA 98501 USA. Frank Orth & Associates Inc, Bellevue, WA 98004 USA. RP Hard, JJ (reprint author), NOAA, Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, 2725 Montlake Blvd E, Seattle, WA 98112 USA. EM jeff.hard@noaa.gov RI Hard, Jeffrey/C-7229-2009; Rohlf, F/A-8710-2008 NR 42 TC 52 Z9 54 U1 1 U2 12 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0378-1909 J9 ENVIRON BIOL FISH JI Environ. Biol. Fishes PD MAY PY 2000 VL 58 IS 1 BP 61 EP 73 DI 10.1023/A:1007646332666 PG 13 WC Ecology; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 306WT UT WOS:000086622100006 ER PT J AU Fleck, B Brekke, P Haugan, S Duarte, LS Domingo, V Gurman, JB Poland, AI AF Fleck, B Brekke, P Haugan, S Duarte, LS Domingo, V Gurman, JB Poland, AI TI Four years of SOHO discoveries - Some highlights SO ESA BULLETIN-EUROPEAN SPACE AGENCY LA English DT Article AB Since its launch on 2 December 1995, the Solar and Heliospheric Observatory (SOHO) has provided an unparalleled breadth and depth of information about the Sun, from its interior, through the hot and dynamic atmosphere, out to the solar wind. Analysis of the helioseismology data from SOHO has shed new light on a number of structural and dynamic phenomena in the solar interior, such as the absence of differential rotation in the radiative zone, subsurface zonal and meridional flows, sub-convection-zone mixing, a possible circumpolar jet, and very slow polar rotation. The ultraviolet imagers and spectrometers have revealed an extremely dynamic solar atmosphere in which plasma flows play an important role. Evidence for an upward transfer of magnetic energy from the Sun's surface toward the corona has been found. Electrons in coronal holes have been found to be relatively 'cool', whereas heavy ions are extremely hot and have highly anisotropic velocity distributions. The source region for the high-speed solar wind has been identified and the acceleration profiles of both the slow and fast solar wind have been measured. C1 NASA, Goddard Space Flight Ctr, ESA, Dept Space Sci,Solar Syst Div, Greenbelt, MD USA. RP Fleck, B (reprint author), NASA, Goddard Space Flight Ctr, ESA, Dept Space Sci,Solar Syst Div, Greenbelt, MD USA. RI Fleck, Bernhard/C-9520-2012 NR 0 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI NOORDWIJK PA ESTEC, PO BOX 299, 2200 AG NOORDWIJK, NETHERLANDS SN 0376-4265 J9 ESA BULL-EUR SPACE JI ESA Bull.-Eur. Space Agency PD MAY PY 2000 IS 102 BP 69 EP 86 PG 18 WC Engineering, Aerospace SC Engineering GA 331PG UT WOS:000088027000008 ER PT J AU Courtney, DL Mortensen, DG Orsi, JA Munk, KM AF Courtney, DL Mortensen, DG Orsi, JA Munk, KM TI Origin of juvenile Pacific salmon recovered from coastal southeastern Alaska identified by otolith thermal marks and coded wire tags SO FISHERIES RESEARCH LA English DT Article; Proceedings Paper CT 2nd International Symposium on Fish Otolith Research and Application CY JUN, 1998 CL BERGEN, NORWAY DE otolith; thermal mark; Pacific salmon; stock origin identification; coded wire tag ID MARINE DISTRIBUTION AB First ocean-year juvenile Pacific salmon (Oncorhynchus spp.) in the marine waters of southeastern Alaska were examined for origin identification in the summers of 1993-1997. Over 31,000 juvenile pink (O. gorbuscha), chum (O. keta), sockeye (O. nerka), coho (O. kisutch), and chinook (O. tshawytscha) salmon were scanned electronically for coded wire tags (cwt's). Cwt's were decoded to indicate tagging origins and release sites. Few (49) fish examined contained cwt's. A sub-sample of the scanned juvenile pink (1,698), chum (1,685), and sockeye (189) salmon were also examined for thermally induced otolith marks (thermal marks). Sagittal otoliths were processed, and thermal mark code patterns were resolved to identify marking facilities and release sites. Many of the pink (45), chum (483), and sockeye (12) salmon examined contained thermal marks. Most recovered cwt's and thermal marks originated in southeastern Alaska. Most thermally marked juveniles had migrated 100-150 km in 60-90 days from release locations in northern and central southeastern Alaska and were recaptured along a primary migration corridor in northern southeastern Alaska. The high proportion (15.1%) of otolith thermal mark recoveries has broad implications for the study of Pacific salmon life histories. In particular, systematic sampling for thermal marks may provide stock-specific insight into the early marine life histories of Pacific salmon species, especially pink and chum salmon, which otherwise are underrepresented in cwt recoveries. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Auke Bay Lab, Juneau, AK 99801 USA. RP Courtney, DL (reprint author), Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Auke Bay Lab, 11305 Glacier Highway, Juneau, AK 99801 USA. NR 15 TC 17 Z9 18 U1 1 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0165-7836 J9 FISH RES JI Fish Res. PD MAY PY 2000 VL 46 IS 1-3 BP 267 EP 278 DI 10.1016/S0165-7836(00)00151-X PG 12 WC Fisheries SC Fisheries GA 317ZY UT WOS:000087259700026 ER PT J AU Tierney, C Wahr, J Bryan, F Zlotnicki, V AF Tierney, C Wahr, J Bryan, F Zlotnicki, V TI Short-period oceanic circulation: implications for satellite altimetry SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Atmospherically forced, high-frequency oceanic variability is investigated using different configurations of an ocean general circulation model. At periods less than 20 days, the dynamic response of the sea surface to pressure loading exceeds that due to wind stress, and is mostly barotropic. Energy at these periods aliases into satellite altimeter measurements of sea surface height (SSHT). The global variance of collinear (approximate to 10 day) differences of this modelled aliased SSHT is between (2 cm)(2) and (3.5 cm)(2), depending on the model configuration used. The local variance can reach (14 cm)(2) at some high latitude locations. We use the ocean model predictions to remove the high-frequency signals from TOPEX/Poseidon (T/P) observations. We obtain a global variance reduction in collinear differences of up to (2 cm)(2), about 7% of the T/P signal. Our model has difficulty in predicting the variability at periods less than 5 days. C1 Univ Colorado, CIRES, Boulder, CO 80309 USA. Univ Colorado, Dept Phys, Boulder, CO 80309 USA. NCAR, Climate & Global Dynam Div, Boulder, CO USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Tierney, C (reprint author), Univ Colorado, CIRES, CB 216, Boulder, CO 80309 USA. RI Bryan, Frank/I-1309-2016 OI Bryan, Frank/0000-0003-1672-8330 NR 10 TC 62 Z9 63 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 2000 VL 27 IS 9 BP 1255 EP 1258 DI 10.1029/1999GL010507 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 309BX UT WOS:000086748600005 ER PT J AU Thomas, RH Abdalati, W Akins, TL Csatho, BM Frederick, EB Gogineni, SP Krabill, WB Manizade, SS Rignot, EJ AF Thomas, RH Abdalati, W Akins, TL Csatho, BM Frederick, EB Gogineni, SP Krabill, WB Manizade, SS Rignot, EJ TI Substantial thinning of a major east Greenland outlet glacier SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID AIRBORNE LASER ALTIMETRY; ICE-SHEET AB Aircraft laser-altimeter surveys in 1993 and 1998 over Kangerdlugssuaq Glacier in east Greenland reveal thinning, over the 5-year interim, of several meters for all surveyed areas within 70 km of the seaward ice front, rising to 50 meters in the final 5 km. Such rapid thinning is best explained by increased discharge velocities and associated creep thinning, most probably caused by enhanced lubrication of the glacier bed. The calving ice front over the past decade has occupied approximately the same location as in 1966. Velocity estimates for 1995/96 are about the same as those for 1966 and 1988, but significantly less than for 1999, suggesting that major thinning began after 1995. C1 EG&G Inc, Wallops Flight Facil, Wallops Island, VA 23337 USA. NASA, Goddard Space Flight Ctr, Lab Hydospher Proc, Wallops Flight Facil, Wallops Island, VA 23337 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Ohio State Univ, Byrd Polar Res Ctr, Columbus, OH 43210 USA. Univ Kansas, Radar Syst & Remote Sensing Lab, Lawrence, KS 66045 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Thomas, RH (reprint author), EG&G Inc, Wallops Flight Facil, Bldg N-159, Wallops Island, VA 23337 USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 14 TC 50 Z9 50 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 MAY 1 PY 2000 VL 27 IS 9 BP 1291 EP 1294 DI 10.1029/1999GL008473 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 309BX UT WOS:000086748600014 ER PT J AU Fillingim, MO Parks, GK Chen, LJ Brittnacher, M Germany, GA Spann, JF Larson, D Lin, RP AF Fillingim, MO Parks, GK Chen, LJ Brittnacher, M Germany, GA Spann, JF Larson, D Lin, RP TI Coincident POLAR/UVI and WIND observations of pseudobreakups SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETIC ACTIVITY; FLOW BURSTS; SUBSTORM; MAGNETOTAIL; IONOSPHERE; MAGNETOSPHERE; PARTICLE; ONSET AB Using POLAR/UVI global images, we have identified a period of successive minor auroral activations during which WIND was making a perigee pass (X similar to - 11 R-E) These auroral brightenings are interpreted to be pseudobreakups due to the lack of global expansion. Large magnetic field fluctuations and high earthward ion velocity moments measured by the WIND spacecraft show a nearly one-to-one correspondence with the auroral intensifications. Analysis of the plasma parameters indicates that there is no difference in the behavior of the plasma during pseudobreakups as compared to substorm expansive phase onset. Inspection of the ion distribution functions during high velocity moment events reveals the presence of a two component plasma. The particles contributing to the large mean velocities are energetic ions with energies from similar to 2 to 27 keV. We conclude that pseudobreakups are the ionospheric signature of high velocity moment events. C1 Univ Washington, Geophys Program, Seattle, WA 98195 USA. Univ Alabama, Ctr Space Plasma & Aeron Res, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Calif Berkeley, SSL, Berkeley, CA 94720 USA. RP Fillingim, MO (reprint author), Univ Washington, Geophys Program, Seattle, WA 98195 USA. RI Chen, Li-Jen/C-2106-2012 NR 16 TC 22 Z9 22 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 MAY 1 PY 2000 VL 27 IS 9 BP 1379 EP 1382 DI 10.1029/1999GL010773 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 309BX UT WOS:000086748600036 ER PT J AU Rinsland, CP Salawitch, RJ Osterman, GB Irion, FW Sen, B Zander, R Mahieu, E Gunson, MR AF Rinsland, CP Salawitch, RJ Osterman, GB Irion, FW Sen, B Zander, R Mahieu, E Gunson, MR TI Stratospheric CO at tropical and mid-latitudes: ATMOS measurements and photochemical steady-state model calculations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TRANSPORT; SPACE AB We characterize the spring and fall stratospheric distribution of CO at 49 degrees N-55 degrees S latitude from ATMOS profiles measured during 4 shuttle flights, Measured mixing ratios increase with potential temperature (theta) from 12 ppbv (10(-9) per unit volume) at 525 K, to 30-40 ppbv at 1750 K with only minor variations with latitude and season at a theta level. Evidence for some confinement near 1150 K in the developing November 1994 vortex is indicated from comparison of CO and N2O horizontal gradients. Measured CO mixing ratios at the tropical tropopause are a factor of 10 higher than values calculated with a steady-state model using standard photochemistry constrained by correlative temperatures and pressures, and ATMOS measurements including CH4 as inputs, Differences decrease with latitude at constant theta and are <20% at 800 K and all latitudes, where the CO photochemical lifetime is 40-50 days. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. Univ Liege, Inst Astrophys & Geophys, Liege, Belgium. RP Rinsland, CP (reprint author), NASA, Langley Res Ctr, Mail Stop 401A, Hampton, VA 23681 USA. RI Salawitch, Ross/B-4605-2009; OI Salawitch, Ross/0000-0001-8597-5832; Mahieu, Emmanuel/0000-0002-5251-0286 NR 15 TC 6 Z9 6 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 MAY 1 PY 2000 VL 27 IS 9 BP 1395 EP 1398 DI 10.1029/1999GL011184 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 309BX UT WOS:000086748600040 ER PT J AU Burns, JA Lissauer, JJ Makalkin, A AF Burns, JA Lissauer, JJ Makalkin, A TI Victor Sergeyevich Safronov (1917-1999) - In Memoriam SO ICARUS LA English DT Biographical-Item C1 Cornell Univ, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Burns, JA (reprint author), Cornell Univ, Ithaca, NY 14853 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 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 2000 VL 145 IS 1 BP 1 EP 3 DI 10.1006/icar.2000.6367 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309ZX UT WOS:000086801000001 ER PT J AU Zappala, V Bendjoya, P Cellino, A Di Martino, M Doressoundiram, A Manara, A Migliorini, F AF Zappala, V Bendjoya, P Cellino, A Di Martino, M Doressoundiram, A Manara, A Migliorini, F TI Fugitives from the Eos family: First spectroscopic confirmation SO ICARUS LA English DT Article DE asteroids, dynamics; resonances; spectroscopy ID ASTEROID FAMILIES; METEORITES; RESONANCES; EARTH AB The fact that some asteroids presently located in the 9/4 mean-motion resonance with Jupiter could be "Eos fugitives," that is, original members of this asteroid family injected into the resonance and experiencing a gradual eccentricity increase, was first suggested a few years ago (Morbidelli, A., V. Zappala, M, Moons, A. Cellino, and R. Gonczi 1995, Icarus 118, 132-154), We present here the results of a campaign of spectroscopic observations of candidate Eos fugitives, and we confirm that some of these objects should come from this family, according to their observed spectral characteristics. We find also indications that these objects are probably relatively young. We can conclude that Eos fugitives are a first example of family objects observed during the dynamical process of leaving the asteroid main belt. The results confirm current ideas about the dynamics governing bodies injected into the 9/4 resonance. This can be important also from the point of view of a possible relationship between the Eos family and CV/CO chondrites as suggested by spectral analogies. (C) 2000 Academic Press. C1 Osservatorio Astron Torino, I-10025 Pino Torinese, Italy. Univ Nice, F-06108 Nice, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Osservatorio Astron Brera, I-20121 Milan, Italy. RP Zappala, V (reprint author), Osservatorio Astron Torino, I-10025 Pino Torinese, Italy. RI Cellino, Alberto/N-1570-2015 OI Cellino, Alberto/0000-0002-6645-334X NR 23 TC 18 Z9 18 U1 0 U2 0 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 2000 VL 145 IS 1 BP 4 EP 11 DI 10.1006/icar.2000.6349 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309ZX UT WOS:000086801000002 ER PT J AU Cabrol, NA Grin, EA Pollard, WH AF Cabrol, NA Grin, EA Pollard, WH TI Possible frost mounds in an ancient Martian lake bed SO ICARUS LA English DT Article DE Mars; ices; impact processes; exobiology ID WESTERN-ARCTIC-COAST; IMPACT CRATER LAKES; NORTHERN PLAINS; FORT NORMAN; BEAR ROCK; MARS; GROWTH; THERMOKARST; DURATION; CHANNELS AB Circular to elongated mounds are observed in Gusev crater in the Aeolis subquadrangle of Mars. They are arranged in a large cluster and show different stages of evolution, from fresh to scar structures. Their morphology and morphometric ratios are comparable to those of terrestrial frost mounds. This study shows how the paleolacustrine environment of the Ma'adim Vallis/Gusev crater hydrogeologic system may have provided a suitable environment for the formation of frost mounds. Alternate hypotheses of formation including volcanism, fluvial erosion, and eolian erosion are discussed. Other features such as heavings, curvilinear troughs, hills, ridges, and depressions support the idea of a sediment/ice interaction. The typology of the mounds and plausible mechanisms for their formation are proposed. Their presence could support the model of a massive water body in Gusev during the Amazonian and provide indicators of paleoenvironmental conditions at the time of their formation. (C) 2000 Academic Press. C1 NASA, Ames Res Ctr, SETI Inst, Div Space Sci, Moffett Field, CA 94035 USA. McGill Univ, Dept Geog, Montreal, PQ H3A 2K6, Canada. RP Cabrol, NA (reprint author), NASA, Ames Res Ctr, SETI Inst, Div Space Sci, Moffett Field, CA 94035 USA. NR 74 TC 28 Z9 28 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 MAY PY 2000 VL 145 IS 1 BP 91 EP 107 DI 10.1006/icar.1999.6326 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309ZX UT WOS:000086801000010 ER PT J AU Bottke, WF Love, SG Tytell, D Glotch, T AF Bottke, WF Love, SG Tytell, D Glotch, T TI Interpreting the elliptical crater populations on Mars, Venus, and the Moon SO ICARUS LA English DT Article DE impact processes; Mars, surface; Moon, surface; Venus, surface ID DOUBLET CRATERS; IMPACTS AB Asteroids or comets striking a planetary surface at very shallow angles produce elliptical-shaped craters. According to laboratory impact experiments (D. E. Gault and J. A. Wedekind 1978, Proc. Lunar Planet. Sci. Conf. 9th, 3843-3875), elliptical craters result from impact angles within similar to 5 degrees of horizontal and less than 1% of projectiles with isotropic impact trajectories create elliptical craters. This result disagrees with survey results which suggest that approximately 5% of all kilometer-sized craters formed on Mars, Venus, and the Moon have elliptical shapes. To explain this discrepancy, we examined the threshold incidence angle necessary to produce elliptical craters in laboratory impact experiments. Recent experiments show that aluminum targets produce elongated craters at much steeper impact angles than sand targets. This suggests that target properties are as important as the projectile's impact angle in determining the eventual ellipticity of the crater. Creating a model which interpolates between impact data produced using sand and aluminum targets, we derive a new elliptical crater threshold angle of 12 degrees from horizontal for Mars, Venus, and the Moon. This leads to a predicted proportion of elliptical craters that matches observations within uncertainty given a random projectile population. We conclude that the observed proportion of elliptical craters on these bodies is a natural by-product of projectiles striking at random angles, and that no additional formation mechanisms are needed. (C) 2000 Academic Press. C1 Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. RP Bottke, WF (reprint author), Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. NR 24 TC 57 Z9 57 U1 0 U2 1 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 2000 VL 145 IS 1 BP 108 EP 121 DI 10.1006/icar.1999.6323 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309ZX UT WOS:000086801000011 ER PT J AU Poulet, F Sicardy, B Dumas, C Jorda, L Tiphene, D AF Poulet, F Sicardy, B Dumas, C Jorda, L Tiphene, D TI The crossings of Saturn ring plane by the Earth in 1995: Ring thickness SO ICARUS LA English DT Article DE planetary rings; Saturn; photometry ID F-RING; JOVIAN PLANETS; BENDING WAVES; SPECTROPHOTOMETRY; METHANE; PERTURBATIONS; PRECESSION; PHOTOMETRY; SATELLITES; PARTICLES AB The crossings of Saturn's ring plane by Earth were observed in the near infrared on May 22 and August 10, 1995, from the 2.2-m telescope of the University of Hawaii, the 2-m telescope at Pic du Midi, France, and with the Adonis adaptive optics camera at the 3.6-m telescope of the European Southern Observatory in Chile. Images from the Hubble Space Telescope, obtained in August 1995, are also reanalyzed. The radial brightness profiles of the rings indicate that the outer and usually faint F ring dominates the edge-on brightness of the system, thus hiding the vertical structure of the main rings within a few hours around the ring plane crossing. The photometric behaviors of the A, B, and C rings and of the Cassini Division are analyzed, using a radiative transfer code which includes the illuminations by the Sun and by the planet. The F ring is modeled as a physically thick ribbon of height H, composed of large particles embedded in dust of fractional optical depth f. The observed profiles, combined with previous results, can be explained if the F ring is both optically thick (radial optical depth similar to 0.20) and physically thick (H = 21 +/- 4 km). We suggest that this vertical distribution results from the interactions between ring particles and shepherding satellites and/or from gravitational stirring by large bodies. The dust particles dominate the F ring's photometric behavior even in backscattered light (f > 0.80). Constraints on the particle properties of the other rings are also derived. (C) 2000 Academic Press. C1 Inst Univ France, Dept Rech Spatiale, Observ Meudon, F-92195 Meudon, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Max Planck Inst Aeron, D-37191 Katlenburg Lindau, Germany. RP Poulet, F (reprint author), Inst Univ France, Dept Rech Spatiale, Observ Meudon, F-92195 Meudon, France. NR 46 TC 13 Z9 13 U1 0 U2 0 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 2000 VL 145 IS 1 BP 147 EP 165 DI 10.1006/icar.1999.6314 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309ZX UT WOS:000086801000014 ER PT J AU Moses, JI Lellouch, E Bezard, B Gladstone, GR Feuchtgruber, H Allen, M AF Moses, JI Lellouch, E Bezard, B Gladstone, GR Feuchtgruber, H Allen, M TI Photochemistry of Saturn's atmosphere II. Effects of an influx of external oxygen SO ICARUS LA English DT Review DE Saturn, atmosphere; photochemistry; interplanetary dust; infrared observations; meteoroids ID ABSORPTION CROSS-SECTIONS; SCHUMANN-RUNGE BANDS; INTERPLANETARY DUST PARTICLES; EVALUATED KINETIC DATA; SHORT-PERIOD COMETS; INTERSTELLAR DUST; CARBON-MONOXIDE; TEMPERATURE-DEPENDENCE; SOLAR-SYSTEM; KUIPER BELT AB We use a one-dimensional diurnally averaged model of photochemistry and diffusion in Saturn's stratosphere to investigate the influence of extraplanetary debris on atmospheric chemistry, In particular, we consider the effects of an influx of oxygen from micrometeoroid ablation or from ring-particle diffusion; the contribution from cometary impacts, satellite debris, or ring vapor is deemed to be less important. The photochemical model results are compared directly with Infrared Space Observatory (ISO) observations to constrain the influx of extraplanetary oxygen to Saturn. From the ISO observations, we determine that the column densities of CO2 and H2O above 10 mbar in Saturn's atmosphere are (6.3 +/- 1) x 10(14) and (1.4 +/- 0.4) x 10(15) cm(-2), respectively; our models indicate that a globally averaged oxygen influx of (4 +/- 2) x 10(6) O atoms cm(-2) s(-1) is required to explain these observations. Models with a locally enhanced influx of H2O operating over a small fraction of the projected area do not provide as good a fit to the ISO H2O observations. If volatile oxygen compounds comprise one-third to one-half of the exogenic source by mass, then Saturn is currently being bombarded with (3 +/- 2) x 10(-16) g cm(-2) s(-1) of extraplanetary material. To reproduce the observed CO2/H2O ratio in Saturn's stratosphere, some of the exogenic oxygen must arrive in the form of a carbon-oxygen bonded species such as CO or CO2. An influx consistent with the composition of cometary ices fails to reproduce the high observed CO2/H2O ratio, suggesting that (i) the material has ices that are slightly more carbon-rich than is typical for comets, (ii) a contribution from an organic-rich component is required, or (iii) some of the hydrogen-oxygen bonded material is converted to carbon-oxygen bonded material without photochemistry (e.g., during the ablation process). We have also reanalyzed the 5-mu m CO observations of Noll and Larson (Icarus 89, 168-189, 1990) and determine that the CO lines are most sensitive to the 100- to 400-mbar column density for which we derive a range of (0.7-1.5)x 10(17) cm(-2); the CO observations do not allow us to distinguish between an external or internal source of CO on Saturn. If we assume that all the extraplanetary oxygen derives from a micrometeoroid source, then the unfocused dust flux at 9.5 AU must be (i) (1 +/- 0.7) x 10(-16) g cm(-2) s(-1) if interstellar grains are the source of the external oxygen on Saturn, (ii) (4 +/- 3) x 10(-17) g cm(-2) s-' if IDPs on randomly inclined, highly eccentric orbits (e.g., Halley-type comet grains) are the source of the external oxygen, or (iii) (2 i 1.4) x 10(-18) g cm(-2) s(-1) if IDPs on low inclination, low eccentricity orbits (e.g., Kuiper-belt grains) are the source of the external oxygen. These estimates can be used in combination with future Cassini dust detection data to determine the ultimate source of the dust at Saturn's distance from the Sun. (C) 2000 Academic Press. C1 Lunar & Planetary Inst, Houston, TX 77058 USA. Observ Paris, DESPA, F-92195 Meudon, France. SW Res Inst, Dept Space Sci, San Antonio, TX 78228 USA. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. RP Moses, JI (reprint author), Lunar & Planetary Inst, 3600 Bay Area Blvd, Houston, TX 77058 USA. RI Moses, Julianne/I-2151-2013 OI Moses, Julianne/0000-0002-8837-0035 NR 194 TC 104 Z9 104 U1 1 U2 10 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 2000 VL 145 IS 1 BP 166 EP 202 DI 10.1006/icar.1999.6320 PG 37 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309ZX UT WOS:000086801000015 ER PT J AU Moore, MH Hudson, RL AF Moore, MH Hudson, RL TI IR detection of H2O2 at 80 K in ion-irradiated laboratory ices relevant to Europa SO ICARUS LA English DT Article DE radiation chemistry; ices; Europa; infrared observations; satellites of Jupiter ID GALILEAN SATELLITES; INFRARED SPECTROSCOPY; PROTON IRRADIATION; GANYMEDE; SPECTRA; MOLECULES; MATRICES; METHANOL; CALLISTO; JUPITER AB We present the first in situ laboratory detection of H2O2 in H+ irradiated ices at temperatures relevant to the icy Galilean satellites. These experiments were motivated by the recent Galileo NIMS detection on Europa of a 3.5-mu m band identified with H2O2 (R. W. Carlson et al. 1999, Science 283, 2062-2064). In our laboratory experiments, the IR signature of H2O2 was easily observed after irradiation of pure H2O at 16 K, but it was not seen after irradiation at 80 K. Radiolysis of mixtures of H2O with O-2 or CO2 at 80 K did produce H2O2 These results show that ices more complex than pure H2O are involved in the radiolysis pathway to form H2O2 On Europa. We also report the intrinsic band strength and radiation yield of H2O2 in ice mixtures, along with possible formation and destruction mechanisms. Sufficient concentrations of H2O2 can be formed in H2O ices containing O-2 to explain the NIMS observation. (C) 2000 Academic Press. C1 NASA, Goddard Space Flight Ctr, Astrochem Branch, Greenbelt, MD 20771 USA. Eckerd Coll, Dept Chem, St Petersburg, FL 33733 USA. RP Moore, MH (reprint author), NASA, Goddard Space Flight Ctr, Astrochem Branch, Code 691, Greenbelt, MD 20771 USA. RI Hudson, Reggie/E-2335-2012 NR 32 TC 109 Z9 109 U1 2 U2 9 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 2000 VL 145 IS 1 BP 282 EP 288 DI 10.1006/icar.1999.6325 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309ZX UT WOS:000086801000023 ER PT J AU Ferrante, RF Moore, MH Nuth, JA Smith, T AF Ferrante, RF Moore, MH Nuth, JA Smith, T TI Laboratory studies of catalysis of CO to organics on grain analogs SO ICARUS LA English DT Article DE atmospheric composition; atmospheric evolution; organic chemistry; prebiotic chemistry; solar nebula ID HYDROCARBONS; SMOKES AB Experiments simulating heterogeneous conversion of H-2 and CO into simple hydrocarbons in astrophysical environments have been performed, utilizing realistic cosmic grain analogs of Fe-doped silicates as Fischer-Tropsch-Type catalysts. Catalysis was studied for temperatures from 470-670 K and reactant gas mixtures of H-2/CO with a ratio of 2-100. The total gas pressure was near 0.5 bar. Maximum conversion rates of a few percentage points were achieved over a 3-h time period. Major products were methane, ethane, ethylene, carbon dioxide, and water. Products were identified by IR. spectroscopy. (C) 2000 Academic Press. C1 USN Acad, Dept Chem, Annapolis, MD 21402 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ferrante, RF (reprint author), USN Acad, Dept Chem, Annapolis, MD 21402 USA. RI Nuth, Joseph/E-7085-2012 NR 19 TC 21 Z9 21 U1 3 U2 7 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 2000 VL 145 IS 1 BP 297 EP 300 DI 10.1006/icar.2000.6350 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309ZX UT WOS:000086801000025 ER PT J AU Padin, S Cartwright, JK Joy, M Meitzler, JC AF Padin, S Cartwright, JK Joy, M Meitzler, JC TI A measurement of the coupling between close-packed shielded cassegrain antennas SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article DE multireflector antennas; mutual coupling AB Design and performance details are given for a 0.9-m-diameter shielded cassegrain antenna, which will be used in a 13-element close-packed array. The array is designed to make images of brightness fluctuations in the cosmic microwave background radiation. Coupling between a pair of the shielded cassegrain antennas with a separation of 1 m is in the range - 110 to - 130 dB over the 26- to 36-GHz band. C1 CALTECH, Dept Astron, Pasadena, CA 91125 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. Univ Alabama, Huntsville, AL 35899 USA. RP Padin, S (reprint author), CALTECH, Dept Astron, Pasadena, CA 91125 USA. NR 6 TC 9 Z9 9 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD MAY PY 2000 VL 48 IS 5 BP 836 EP 838 DI 10.1109/8.855504 PG 3 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 338GG UT WOS:000088410300024 ER PT J AU Gunapala, SD Bandara, SV Singh, A Liu, JK Rafol, SB Luong, EM Mumolo, JM Tran, NQ Ting, DZY Vincent, JD Shott, CA Long, J LeVan, PD AF Gunapala, SD Bandara, SV Singh, A Liu, JK Rafol, SB Luong, EM Mumolo, JM Tran, NQ Ting, DZY Vincent, JD Shott, CA Long, J LeVan, PD TI 640 x 486 long-wavelength two-color GaAs/AlGaAs quantum well infrared photodetector (QWIP) focal plane array camera SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article DE dualband infrared; focal plane arrays; gallium arsenide; large format imaging arrays; long-wavelength infrared; quantum well infrared photodetectors; target discrimination ID FABRICATION; PERFORMANCE; DETECTORS AB We have designed and fabricated an optimized long-wavelength/very-long-wavelength two-color quantum well infrared photodetector (QWIP) device structure. The device structure was grown on a 3-in semi-insulating GaAs substrate by molecular beam epitaxy (MBE), The wafer was processed into several 640 x 486 format monolithically integrated 8-9 and 14-15 mu m two-color (or dual wavelength) QWIP focal plane arrays (FPA's), These FPA's were then hybridized to 640 x 486 silicon CMOS readout multiplexers. A thinned (i.e,, substrate removed) FPA hybrid was integrated into a liquid helium cooled dewar for electrical and optical characterization and to demonstrate simultaneous two-color imagery. The 8-9 mu m detectors in the FPA have shown background limited performance (BLIP) at 70 K operating temperature for 300 K background with f/2 cold stop. The 14-15 mu m detectors of the FPA reaches BLIP at 40 K operating temperature under the same background conditions. In this paper we discuss the performance of this long-wavelength dualband QWIP FPA in terms of quantum efficiency, detectivity, noise equivalent temperature difference (NE Delta T), uniformity, and operability. C1 CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. Raytheon Infrared Ctr Excellence, Goleta, CA 93117 USA. USAF, Res Lab, Kirtland AFB, NM 87117 USA. RP Gunapala, SD (reprint author), CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. NR 17 TC 101 Z9 111 U1 7 U2 16 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 MAY PY 2000 VL 47 IS 5 BP 963 EP 971 DI 10.1109/16.841227 PG 9 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 314WZ UT WOS:000087081700009 ER PT J AU Endreny, TA Wood, EF Hsu, A AF Endreny, TA Wood, EF Hsu, A TI Correction of errors in SPOT-derived DEM's using GTOPO30 data SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE digital elevation model (DEM); GTOPO30; hydrology; SPOT; stereocorrelation AB In hydrological studies of the Little Washita River Watershed. OK, a 1000 km(2) section of a satellite probatoire d'observation de la terre (SPOT)-derived digital elevation model (DEM) was observed to contain systematic elevation errors, and a technique for minimizing these errors was developed. Error minimization was achieved by first overlaying the Little Washita section of GTOPO30, the latest DEM providing global land coverage, and then computing GTOP030-SPOT elevation residuals, Spatial analysis of these elevation residuals revealed a systematic elevation error oriented about a single axis, and rotating the SPOT-derived DEM scene about this asis minimized the GTOP030-SPOT root mean square error (RMSE) by nearly 10%. The axis intercept, slope, and degree of rotation identified using the relatively coarse 1 km resolution GTOPO30 product were nearly identical to those identified using three separate DEM's of 30 and 90 m resolution. Forty ground control points (GCP's not used in the original stereocorrelation of the SPOT-derived DEM confirmed that rotation improved the Little Washita SPOT-derived DEM RMSE by nearly 26%. This research indicates that 60 x 60 km2 SPOT-derived DEM scenes may have interior subsections that contain systematic elevation error, and that the GTOPO30 data set has an adequate systematic accuracy for identifying and correcting this error. C1 Princeton Univ, Dept Civil & Environm Engn, Program Environm Engn & Water Resources, Princeton, NJ 08544 USA. NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. RP Endreny, TA (reprint author), SUNY Coll Environm Sci & Forestry, Syracuse, NY 13210 USA. OI Endreny, Theodore/0000-0002-1891-261X NR 11 TC 1 Z9 1 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 2000 VL 38 IS 3 BP 1234 EP 1241 DI 10.1109/36.843015 PG 8 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 320EM UT WOS:000087388900009 ER PT J AU Ranson, KJ Sun, G AF Ranson, KJ Sun, G TI Effects of environmental conditions on boreal forest classification and biomass estimates with SAR SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE biomass; classification; forest; SIR-C/X-SAR; temperature effects ID SIR-C/X-SAR; IMAGING RADAR AB During both SIR-C/X-SAR missions (April and October of 1994), periods of freezing and above freezing temperatures were experienced within the southern study area (SSA) of the boreal ecosystem-atmosphere study (BOREAS). This paper discusses the observed effects of different environmental conditions on forest classification and biomass estimates derived from the SAR data of a portion of this Canadian boreal forest test site. The SIR-C backscatter was found to be lowest when the trees and background were frozen, in agreement with other studies. Simple linear regression models relating measured above-ground woody biomass to SIR-C backscatter were not the same for each date, but statistical tests showed that the slopes were not significantly different, suggesting that a simple correction hg an offset is possible. The classification results indicated that forest type classifications are more variable than the biomass estimates due to temperature conditions. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, College Pk, MD 20742 USA. RP Ranson, KJ (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Ranson, Kenneth/G-2446-2012 OI Ranson, Kenneth/0000-0003-3806-7270 NR 27 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 2000 VL 38 IS 3 BP 1242 EP 1252 DI 10.1109/36.843016 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 320EM UT WOS:000087388900010 ER PT J AU Davis, CH Kluever, CA Haines, BJ Perez, C Yoon, YT AF Davis, CH Kluever, CA Haines, BJ Perez, C Yoon, YT TI Improved elevation-change measurement of the southern Greenland ice sheet from satellite radar altimetry SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE Arctic regions; radar altimetry ID GROWTH; TOPEX/POSEIDON; RETRACKING; ERRORS; HEIGHT; GEOSAT AB A new anal, sis of Seasat and Geosat satellite radar altimeter measurements over the Greenland ice sheet was performed to determine surface elevation change. The new analysis includes twice as many measurements and has 50% greater spatial coverage than our previous study, In addition, a precise global ocean reference network created from four years of Topex/Poseidon altimeter data is used to obtain improved estimates of altimeter orbit errors and measurement system biases, The results show that the average elevation change of the southern Greenland ice sheet above 2000 m from 1978 to 1988 is not significantly different than zero. This contradicts earlier and even more recent studies that reported positive ice sheet growth rates and suggested increased precipitation due to a warmer polar climate. C1 Univ Missouri, Dept Elect Engn, Columbia, MO 65211 USA. Univ Missouri, Dept Aerosp & Mech Engn, Columbia, MO 65211 USA. CALTECH, Jet Prop Lab, Earth Orbiter Syst Grp, Pasadena, CA 91109 USA. Sprint PCS, Overland Pk, KS 66210 USA. Univ Texas, Space Res Ctr, Austin, TX 78759 USA. RP Davis, CH (reprint author), Univ Missouri, Dept Elect Engn, Columbia, MO 65211 USA. NR 35 TC 15 Z9 16 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 2000 VL 38 IS 3 BP 1367 EP 1378 DI 10.1109/36.843031 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 320EM UT WOS:000087388900025 ER PT J AU Keihm, SJ Zlotnicki, V Ruf, CS AF Keihm, SJ Zlotnicki, V Ruf, CS TI TOPEX Microwave Radiometer performance evaluation, 1992-1998 SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE microwave radio propagation; microwave radiometry; meteorological factors; path delay; radiosondes; remote sensing ID MEAN SEA-LEVEL; OCEAN ALGORITHM; TMR; STABILITY; ERS-1 AB The stability and accuracy of the TOPEX Microwave Radiometer (TMR) measurement of the atmospheric path delay due to water vapor is assessed over the interval from launch (August 1992) through June 1998, Detailed global comparisons are made with path delays derived from the special sensor microwave imager (SSM/I) instruments and a network of 15 island radiosondes. The results provide consistent evidence that the TMR path delay measurements included an instrument-related downward drift of 1.0-1.5 mm/yr between October 1992 and December of 1996, The four-year drift correlates with an upward drift seen in the coldest TMR 18-GHz brightness temperature time series and is further supported by independent comparisons of TMR with ERS-1 and 2, GPS, and the Harvest Platform water vapor radiometer measurements. From January 1997 through June 1998, no significant relative path delay drift between TMR and SSM/I is seen in the comparison data, although anomalies do appear in early 1998, In terms of accuracy, both the SSM/I and radiosonde comparisons indicate no significant (>2%) scale error in the TMR path delay. An overall bias of <10 mm may be present, but the comparisons are not consistent in this determination. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Penn State Univ, University Pk, PA 16802 USA. RP Keihm, SJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Ruf, Christopher/I-9463-2012 NR 20 TC 46 Z9 46 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 2000 VL 38 IS 3 BP 1379 EP 1386 DI 10.1109/36.843032 PG 8 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 320EM UT WOS:000087388900026 ER PT J AU Markus, T Cavalieri, DJ AF Markus, T Cavalieri, DJ TI An enhancement of the NASA Team sea ice algorithm SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE algorithms; passive microwave; sea ice ID SIGNATURES; GHZ AB An enhancement of the NASA Team sea ice concentration algorithm overcomes the problem of a low ice concentration bias associated with surface snow effects that are particularly apparent in Southern Ocean sea ice retrievals. The algorithm has the same functional form as the NASA Team algorithm, but uses a wider range of frequencies (19-85 GHz). It accommodates ice temperature variability through the use of radiance ratios as in the original NASA Team algorithm, and has the added advantage of providing weather-corrected sea ice concentrations through the utilization of a forward atmospheric radiative transfer model, Retrievals of sea ire concentration with this new algorithm for both the Arctic and Antarctic do not reveal the deficiencies present in either the NASA Team or Bootstrap algorithms. Furthermore, quantitative comparisons with infrared AVHRR data show that the enhanced algorithm provides more accurate ice concentrations with much less bias than the other two algorithms. C1 Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Joint Ctr Earth Syst Technol, Greenbelt, MD 20771 USA. RP Markus, T (reprint author), Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Joint Ctr Earth Syst Technol, Greenbelt, MD 20771 USA. RI Markus, Thorsten/D-5365-2012 NR 22 TC 192 Z9 201 U1 2 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 2000 VL 38 IS 3 BP 1387 EP 1398 DI 10.1109/36.843033 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 320EM UT WOS:000087388900027 ER PT J AU Walthall, CL Halthore, RN Loechel, SE Elman, GC Markham, BL AF Walthall, CL Halthore, RN Loechel, SE Elman, GC Markham, BL TI Measuring aerosol optical thickness with a helicopter-based sunphotometer SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE aerosol optcal thickness; airborne measurements; helicopters; sun photometer ID REFLECTANCES; PLATFORM AB The use of airborne sunphotometers and radiometrically calibrated sensors with fixed wing remote sensing platforms is a reliable method for obtaining atmospherically corrected surface reflectance. Here we describe a variation of such an instrument for use with helicopters. This system tracks the sun once positioned within 30 degrees of the solar disk. The electronics sample fast enough to collect data between passes of the rotor blades. Calibration for converting voltages to atmospheric transmittance was via the Langley plot method and by intercomparison with calibrated surface sunphotometers, Aerosol optical thickness can be inferred at discrete wavelengths in the visible and near-infrared portions of the spectrum. Aerosol optical thickness data collected with the system agrees reasonably well with data collected using other surface-based sunphotometers. C1 USDA ARS, Remote Sensing & Modeling Lab, Beltsville, MD 20705 USA. Brookhaven Natl Lab, Dept Appl Sci, Upton, NY 11973 USA. Univ Maryland, Dept Geog, Lab Global Remote Sensing Studies, College Pk, MD 20742 USA. Corvis Corp, Columbus, MD 21046 USA. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. RP Walthall, CL (reprint author), USDA ARS, Remote Sensing & Modeling Lab, Beltsville, MD 20705 USA. RI Markham, Brian/M-4842-2013 OI Markham, Brian/0000-0002-9612-8169 NR 16 TC 1 Z9 1 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 2000 VL 38 IS 3 BP 1410 EP 1416 DI 10.1109/36.843035 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 320EM UT WOS:000087388900029 ER PT J AU Behn, MD Zuber, MT AF Behn, MD Zuber, MT TI A comparison of ocean topography derived from the shuttle laser altimeter-01 and TOPEX/POSEIDON SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE distance measurement; geodesy; remote sensing; sea; semiconductor lasers ID SATELLITE ALTIMETRY; GENERAL-CIRCULATION; MISSION AB To assess the utility of laser altimetry for studies in dynamical oceanography, we present a comparison of the Shuttle Laser Altimeter (SLA)-01 and the TOPEX/POSEIDON (T/P) radar altimeter on global and regional scales. We compare all similar to 1.1 million SLA-01 range measurements over the oceans to the CSRMSS95 gridded mean sea surface model and find the overall root mean square (RMS) difference to be 2.33 m, The misfit mas improved significantly by removing the mean and trend from individual SLA-01 profiles, often resulting in RMS differences less than 1 m, We also show that in regions where sea surface height varies dramatically over relatively short horizontal scales such as across major subduction zones, SLA-01 was capable of resolving rapid changes in sea surface height. Finally, we examine a number of coastal zones and illustrate SLA-01's ability to track continuously across the land-sea interface, even in regions of dramatic coastal topography, The dominant sources of radial error in the SLA-01 data are time-interval unit (TIU) error (+/-0.75 m) and radial orbit error (1 m RMS), Therefore, limitations of the SLA-01 data set are caused primarily by system constraints as opposed to instrumentation error. Our results indicate that future laser altimeters will provide valuable information regarding ocean topography, In particular, laser altimetry data can be used to supplement orbiting microwave ranging systems in coastal areas where such sensors are incapable of maintaining lock across the continent-ocean transition. C1 MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. Woods Hole Oceanog Inst, Marine Geol & Geophys Program, Woods Hole, MA 02543 USA. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. RP Behn, MD (reprint author), MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. RI Behn, Mark/F-5813-2012 OI Behn, Mark/0000-0002-2001-1335 NR 34 TC 2 Z9 2 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 2000 VL 38 IS 3 BP 1425 EP 1438 DI 10.1109/36.843037 PG 14 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 320EM UT WOS:000087388900031 ER PT J AU Imhoff, ML Johnson, P Holford, W Hyer, J May, L Lawrence, W Harcombe, P AF Imhoff, ML Johnson, P Holford, W Hyer, J May, L Lawrence, W Harcombe, P TI BioSAR (TM): An inexpensive airborne VHF multiband SAR system for vegetation biomass measurement SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE airborne remote sensing; biomass; low frequency radar; VHF radar ID FOREST BIOMASS; RADAR BACKSCATTER AB A pulse coherent synthetic aperture radar (SAR) operating between 80-120 MHz has been developed in an attempt to measure heavy forest biomass. The sensor uses a nadir-pointing antenna configuration and collects data in a 300-m wide swath on the ground along the flight line. C1 NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. Amer Elect Inc, Zimmerman Associates Inc, Vienna, VA 22182 USA. Bowie State Univ, Dept Nat Sci, Bowie, MD 20715 USA. Rice Univ, Dept Ecol & Evolutionary Biol, Houston, TX 77005 USA. RP Imhoff, ML (reprint author), NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Code 923, Greenbelt, MD 20771 USA. NR 13 TC 13 Z9 14 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 2000 VL 38 IS 3 BP 1458 EP 1462 DI 10.1109/36.843042 PG 5 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 320EM UT WOS:000087388900036 ER PT J AU Belegradek, B Kalpakis, K Yesha, Y AF Belegradek, B Kalpakis, K Yesha, Y TI Strategies for maximizing seller's profit under unknown buyer's valuations SO INFORMATION SCIENCES LA English DT Article DE pricing strategies; market models; electronic commerce; computational learning theory; dynamic programming; search trees; discrete algorithms ID DURABLE GOODS MONOPOLY; UNCERTAINTY AB Suppose there is a seller that has an unlimited number of units of a-single product for sale. The seller at each moment of time posts a price for his/her product. Based on the posted pricer at each moment of time, a buyer decides whether or not to buy a unit of that product from the seller. The only information about the buyer available to the seller is,the seller's sales history. Further, we assume that the maximal unit price the buyer is willing to pay does not change over time. The question then is how should the seller price his/her product to maximize profits? To address this question, we use the notion of loss functions. Intuitively, a loss function is a measure, at each moment of time, of the lost opportunity to make a profit. In particular, we provide a polynomial-time algorithm that finds a:pricing algorithm (strategy) for the seller that minimizes the average (total) losses over time, Further, we provide efficient algorithms for finding pricing strategies for maximizing the cumulative seller's profits when the sales period is limited, there is a limited supply of the product for sale, and the buyer's valuation is a non-increasing function of time, where those functions are known to the seller. We also present preliminary results on pricing strategies that minimize the maximum loss, and we show show that there is no strategy minimizing both the total loss and the maximum loss at the same time. (C) 2000 Elsevier Science Inc. All rights reserved. C1 Univ Maryland Baltimore Cty, Dept Comp Sci & Elect Engn, Baltimore, MD 21250 USA. NASA, Goddard Space Flight Ctr, Ctr Excellence Space Data & Informat Sci, Greenbelt, MD 20771 USA. RP Yesha, Y (reprint author), Univ Maryland Baltimore Cty, Dept Comp Sci & Elect Engn, 1000 Hilltop Circle, Baltimore, MD 21250 USA. NR 13 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0020-0255 J9 INFORM SCIENCES JI Inf. Sci. PD MAY PY 2000 VL 124 IS 1-4 BP 219 EP 239 DI 10.1016/S0020-0255(99)00138-3 PG 21 WC Computer Science, Information Systems SC Computer Science GA 291ZC UT WOS:000085768800011 ER PT J AU Thorn, RP Payne, WA Chillier, XDF Stief, LJ Nesbitt, FL Tardy, DC AF Thorn, RP Payne, WA Chillier, XDF Stief, LJ Nesbitt, FL Tardy, DC TI Rate constant and RRKM product study for the reaction between CH3 and C2H3 at T=298 K SO INTERNATIONAL JOURNAL OF CHEMICAL KINETICS LA English DT Article ID TEMPERATURE RATE COEFFICIENTS; VERTICAL-DISTRIBUTION; ENERGY-TRANSFER; VINYL RADICALS; ATMOSPHERE; PHOTOCHEMISTRY; NEPTUNE; ATOMS; METHYL; KINETICS AB The total rate constant k(1) has been determined at P = 1 Torr nominal pressure (He) and at T = 298 K for the vinyl-methyl cross-radical reaction: (1) CH3 + C2H3 --> Products. The measurements were performed in a discharge flow system coupled with collision-free sampling to a mass spectrometer operated at low electron energies. Vinyl and methyl radicals were generated by the reactions of F with C2H4 and CH4, respectively. The kinetic studies were performed by monitoring the decay of C2H3 with methyl in excess, 6 < [CH3](0)/ [C2H3](0) < 21. The overall rate coefficient was determined to be k(1)(298 K) = (1.02 +/- 0.53) X 10(-10) cm(3) molecule(-1) s(-1) with the quoted uncertainty representing total errors. Numerical modeling was required to correct for secondary vinyl consumption by reactions such as C2H3 + H and C2H3 + C2H3. The present result for k(1) at T = 298 K is compared to two previous studies at high pressure (100-700 Torr He) and to a very recent study at low pressure (0.9-3.7 Torr He). Comparison is also made with the rate constant for the similar reaction CH3 + C2H5 and with a value For k(1) estimated by the geometric mean rule employing values for k(CH3 + CH3) and k(C2H3 + C2H3). Qualitative product studies at T = 298 K and 200 K indicated formation of C3H6, C2H2, and C3H5 as products of the combination-stabilization, disproportionation, and combination-decomposition channels, respectively, of the CH3 + C2H3 reaction. We also observed the secondary C4H8 product of the subsequent reaction of C3H5 with excess CH3; this observation provides convincing evidence For the combination-decomposition channel yielding C3H5 + H. RRKM calculations with helium as the deactivator support the present and very recent experimental observations that allylic C-H bond rupture is an important path in the combination reaction. The pressure and temperature dependencies of the branching fractions are also predicted. (C) 2000 John Wiley & Sons. Inc. Int J Chem Kinet 32: 104-316, 2000. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Coppin State Coll, Dept Nat Sci, Baltimore, MD 21216 USA. Univ Iowa, Dept Chem, Iowa City, IA 52242 USA. RP Thorn, RP (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. NR 61 TC 15 Z9 15 U1 0 U2 5 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 USA SN 0538-8066 J9 INT J CHEM KINET JI Int. J. Chem. Kinet. PD MAY PY 2000 VL 32 IS 5 BP 304 EP 316 PG 13 WC Chemistry, Physical SC Chemistry GA 304TV UT WOS:000086501000006 ER PT J AU Shabbir, A Taulbee, DB AF Shabbir, A Taulbee, DB TI Experimental balances for the second moments for a buoyant plume and their implication on turbulence modeling SO INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER LA English DT Article DE buoyant plume; turbulence models ID SHEAR-FLOW; SCALAR; LAYERS AB The experimental budgets for the transport equations for heat flux and Reynolds stress are presented for a round turbulent buoyant plume. The pressure correlation terms are deduced as the closing terms and are found to constitute a substantial part of these budgets. Even though a buoyant plume is initiated by buoyancy, it is found that the production of heat flux and Reynolds stress is largely maintained by the mean flow gradients, because the buoyancy production terms are not as large. The results are used to assess the local equilibrium assumption, which implies that the production and destruction terms of the transport equations balance each other. The results are also used to investigate why the mechanical to thermal time scale ratio for a buoyant plume is different than the commonly used value. Finally, some simpler models for the pressure correlation terms, which appear in the heat flux and the Reynolds stress equations, are assessed against those deduced from the experiment. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Inst Computat Mech Prop, Glenn Res Ctr, Cleveland, OH 44135 USA. SUNY Buffalo, Buffalo, NY 14260 USA. RP Shabbir, A (reprint author), NASA, Inst Computat Mech Prop, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 14 TC 3 Z9 3 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0017-9310 J9 INT J HEAT MASS TRAN JI Int. J. Heat Mass Transf. PD MAY PY 2000 VL 43 IS 10 BP 1777 EP 1790 DI 10.1016/S0017-9310(99)00253-7 PG 14 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA 293JP UT WOS:000085848700008 ER PT J AU Whittle, J AF Whittle, J TI Evaluating environments for functional programming SO INTERNATIONAL JOURNAL OF HUMAN-COMPUTER STUDIES LA English DT Article DE functional programming; transformational programming; structure editors ID PROLOG AB Functional programming presents new challenges in the design of programming environments. In a strongly typed functional language, such as ML, much conventional debugging of runtime errors is replaced by dealing with compile-time error reports. On the other hand, the cleanness of functional programming opens up new possibilities for incorporating sophisticated correctness-checking techniques into such environments. C(Y)NTHIA is a novel editor for ML that both addresses the challenges and explores the possibilities. It uses an underlying proof system as a framework for automatically checking for semantic errors such as non-termination. In addition, C(Y)NTHIA embodies the idea of programming by analogy-whereby users write programs by applying abstract transformations to existing programs. This paper investigates C(Y)NTHIA's potential as a novice ML programming environment. We report on two studies in which it was found that students using C(Y)NTHIA commit fewer errors and correct errors more quickly than when using a compiler/text editor approach. (C) 2000 Academic Press. C1 NASA, Ames Res Ctr, Recom Technol, Moffett Field, CA 94035 USA. Univ Edinburgh, Edinburgh EH8 9YL, Midlothian, Scotland. Napier Univ, Dept Comp Studies, Edinburgh EH14 1DJ, Midlothian, Scotland. RP Whittle, J (reprint author), NASA, Ames Res Ctr, Recom Technol, Moffett Field, CA 94035 USA. NR 35 TC 2 Z9 2 U1 1 U2 1 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 1071-5819 J9 INT J HUM-COMPUT ST JI Int. J. Hum.-Comput. Stud. PD MAY PY 2000 VL 52 IS 5 BP 847 EP 878 DI 10.1006/ijhc.1999.0356 PG 32 WC Computer Science, Cybernetics; Ergonomics; Psychology, Multidisciplinary SC Computer Science; Engineering; Psychology GA 317MN UT WOS:000087229300004 ER PT J AU Vogel, BF Venkateswaran, K Christensen, H Falsen, E Christiansen, G Gram, L AF Vogel, BF Venkateswaran, K Christensen, H Falsen, E Christiansen, G Gram, L TI Polyphasic taxonomic approach in the description of Alishewanella fetalis gen. nov., sp nov., isolated from a human foetus SO INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY LA English DT Article DE Alishewanella fetalis gen. nov sp nov.; polyphasic taxonomy; 16S rRNA; DNA gyrase; human isolate ID PSEUDOMONAS-PUTREFACIENS BACTEREMIA; RIBOSOMAL-RNA GENE; SHEWANELLA-PUTREFACIENS; PHYLOGENETIC ANALYSIS; NUCLEOTIDE-SEQUENCE; MAXIMUM-LIKELIHOOD; DNA-SEQUENCES; GYRB GENES; ALGA; STRAINS AB A taxonomically unique bacterium is described on the basis of a physiological and biochemical characterization, fatty acid profiling and sequence analyses of 16S rRNA and gyrase B (gyrB) genes. This non-motile, non-fermentative bacterium was isolated from a human foetus in Uppsala, Sweden, and originally misidentified as ii Shewanella putrefaciens by conventional biochemical testing. The bacterium grew well at mesophilic temperatures with optimum growth at 37 degrees C. It was facultatively anaerobic and utilized various electron accepters (trimethylamine oxide, nitrate, nitrite and thiosulphate). The dominant fatty acids were 17:1B, 16:1 cis9 17:0 and 16:0. Fatty acids 13:0 iso and 15:0 iso, which have been found to be typical of Shewanella species were not detected. The G+C content of the DNA was 50.6 mol%. Phylogenetic analysis of the 16S rRNA gene sequence revealed a clear affiliation with members of the gamma subclass of the Proteobacteria. No relationship was seen with any of the established genera in the gamma subclass of the Proteobacteria, although a distinct relationship with Vibrionaceae was observed. That the bacterium represents a novel bacterial genus distinct from Vibrionaceae was also supported by gyrB sequence analysis. Considering the source and close proximity to the genus Shewanella, the name Alishewanella fetalis gen. nov., sp. nov. is proposed, for which the type strain is strain CCUG 30811(T). C1 Tech Univ Denmark, Dept Seafood Res, Danish Inst Fisheries Res, DK-2800 Lyngby, Denmark. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Royal Vet & Agr Univ, Dept Vet Microbiol, DK-1870 Frederiksberg, Denmark. Gothenburg Univ, Dept Clin Bacteriol, Culture Collect, S-41346 Gothenburg, Sweden. Aarhus Univ, Dept Med Microbiol & Immunol, DK-8000 Aarhus C, Denmark. RP Vogel, BF (reprint author), Tech Univ Denmark, Dept Seafood Res, Danish Inst Fisheries Res, Bldg 221, DK-2800 Lyngby, Denmark. NR 40 TC 30 Z9 30 U1 0 U2 0 PU SOC GENERAL MICROBIOLOGY PI READING PA MARLBOROUGH HOUSE, BASINGSTOKE RD, SPENCERS WOODS, READING RG7 1AE, BERKS, ENGLAND SN 1466-5026 J9 INT J SYST EVOL MICR JI Int. J. Syst. Evol. Microbiol. PD MAY PY 2000 VL 50 BP 1133 EP 1142 PN 3 PG 10 WC Microbiology SC Microbiology GA 316PK UT WOS:000087176500023 PM 10843055 ER PT J AU Man, KF AF Man, KF TI Surface tension measurements of liquid metals by the quasi-containerless pendant drop method SO INTERNATIONAL JOURNAL OF THERMOPHYSICS LA English DT Article DE digital image analysis; electron beam melting; high-temperature liquid metals; melting point; pendant drop; quasi-containerless; surface tension ID LEVITATED DROPLET; NICKEL AB The surface tensions of liquid metals, Zr, Ni, Ti, Mo, and Nb, have been measured at their molting points using the quasi-containerless pendant drop method. This method involves melting the end of a high-purity metal rod by bombardment with an electron beam to form a pendant drop under ultrahigh-vacuum conditions to minimize surface contamination. The magnified image of the drop is captured from a high-resolution CCD camera and digitized using a frame-grabber, The digital image is analyzed by reading the pixel intensities from a graphics file. The edge coordinates of the drop along rows and columns of pixels art: searched by a computer program and stored in an array. An optimized theoretical drop shape is computed From the edge coordinates by solving the Young Laplace differential equation to deduce the surface tension. The measured surface tensions are compared with available experimental results and theoretical calculations. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Man, KF (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 30 TC 16 Z9 16 U1 0 U2 11 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0195-928X J9 INT J THERMOPHYS JI Int. J. Thermophys. PD MAY PY 2000 VL 21 IS 3 BP 793 EP 804 DI 10.1023/A:1006601821432 PG 12 WC Thermodynamics; Chemistry, Physical; Mechanics; Physics, Applied SC Thermodynamics; Chemistry; Mechanics; Physics GA 333BH UT WOS:000088108500013 ER PT J AU Singleton, JD Yeager, WT AF Singleton, JD Yeager, WT TI Important scaling parameters for testing model-scale helicopter rotors SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA 20th Advanced Measurement and Ground Testing Technology Conference CY JUN 15-18, 1998 CL ALBUQUERQUE, NEW MEXICO SP Amer Inst Aeronaut & Astronaut AB An investigation into the effects of aerodynamic and aeroelastic scaling parameters on model-scale helicopter rotors has been conducted in the NASA Langley Research Center Transonic Dynamics Tunnel. The effect of varying Reynolds number, blade Lock number, and structural elasticity on rotor performance has been studied, and the performance results are discussed herein for two different rotor blade sets at two rotor advance ratios. One set of rotor blades was rigid and the other set of blades was dynamically scaled to be representative of a main rotor design for a utility class helicopter. The investigation was conducted by wind-tunnel simulations of forward flight at rotor advance ratios of 0.15 and 0.35. Additionally, the rotors were tested over a range of nominal test medium densities from 0.00382 to 0.009 slugs/ft(3). This range of densities permits the acquisition of data for several Reynolds and Lock number combinations. C1 NASA, Langley Res Ctr, Aeroelast Branch, Hampton, VA 23681 USA. RP Singleton, JD (reprint author), NASA, Langley Res Ctr, Aeroelast Branch, Hampton, VA 23681 USA. NR 15 TC 3 Z9 4 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 2000 VL 37 IS 3 BP 396 EP 402 DI 10.2514/2.2639 PG 7 WC Engineering, Aerospace SC Engineering GA 322FY UT WOS:000087500600006 ER PT J AU Bartels, RE AF Bartels, RE TI Mesh strategies for accurate computation of unsteady spoiler and aeroelastic problems SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA 14th Computational Fluid Dynamics Conference CY JUN 28-JUL 01, 1999 CL NORFOLK, VIRGINIA SP Amer Inst Aeronaut & Astronaut ID GEOMETRIC CONSERVATION AB A modification of the spring analogy scheme that uses axial linear spring stiffness with selective spring stiffening/relaxation is presented. An alternate approach to solving the geometric conservation law is taken that eliminates the need for storage of metric Jacobians at previous time steps. The method is applied to the computation of the turbulent flow about an airfoil with a two-dimensional moving spoiler surface. The aeroelastic response at low dynamic pressure of an airfoil to a single large-scale oscillation of a spoiler surface is simulated in a study of the effect of fluid domain convergence and subiterative strategies. A critical issue in the computation of aeroelastic response with a strongly nonlinear flowfield is shown to be the convergence of the fluid domain. It is confirmed that it is possible to achieve accurate solutions with a very large time step for aeroelastic problems using the fluid solver and aeroelastic integrator as discussed. Furthermore, it is shown that a local pseudo-time-based subiterative method is essential for the computation of the present cases. C1 NASA, Langley Res Ctr, Aeroelast Branch, Hampton, VA 23681 USA. RP Bartels, RE (reprint author), NASA, Langley Res Ctr, Aeroelast Branch, Hampton, VA 23681 USA. NR 21 TC 10 Z9 10 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 2000 VL 37 IS 3 BP 521 EP 525 DI 10.2514/2.2629 PG 5 WC Engineering, Aerospace SC Engineering GA 322FY UT WOS:000087500600023 ER PT J AU Graetz, J Good, N Fultz, B Dooley, J Chave, R AF Graetz, J Good, N Fultz, B Dooley, J Chave, R TI Magnetomechanical effects in textured polycrystalline Tb76Dy24 SO JOURNAL OF APPLIED PHYSICS LA English DT Article; Proceedings Paper CT 44th Annual Conference on Magnetism and Magnetic Materials CY NOV 15-18, 1999 CL SAN JOSE, CALIFORNIA SP Amer Inst Phys, Magnet Soc Inst Elect & Electr Engineers, Minerals Met & Mat Soc, Amer Soc Testing & Mat, USN Off Res, Amer Ceram Soc, Amer Phys Soc ID MAGNETOSTRICTION AB Uniaxial stress-strain measurements were performed on polycrystalline Tb76Dy24 alloys which exhibit "giant magnetostriction" at cryogenic temperatures. The Young's moduli were reduced by up to a factor of five at 77 K, in comparison to their values at 300 K. We attribute this reduction to a mechanical compliance from domain rotation. Large mechanical hysteresis is also found in nominally elastic stress-strain curves measured below the Curie temperature. Hysteretic curves from 0 to 25 MPa demonstrate up to 19% dissipation of the applied mechanical energy. The anisotropy of thermal expansion was also measured and used as a parameter for the degree of crystallographic texture. This anisotropy was correlated to bulk magnetostriction and to mechanical hysteresis. (C) 2000 American Institute of Physics. [S0021-8979(00)16408-4]. C1 CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Graetz, J (reprint author), CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. NR 7 TC 3 Z9 3 U1 2 U2 2 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 1 PY 2000 VL 87 IS 9 BP 5795 EP 5797 DI 10.1063/1.372525 PN 2 PG 3 WC Physics, Applied SC Physics GA 308RT UT WOS:000086727200364 ER PT J AU Teter, JP Horner, GC Bromberg, L AF Teter, JP Horner, GC Bromberg, L TI Precision cryogenic magnetostrictive actuator using a persistent high TC magnet SO JOURNAL OF APPLIED PHYSICS LA English DT Article; Proceedings Paper CT 44th Annual Conference on Magnetism and Magnetic Materials CY NOV 15-18, 1999 CL SAN JOSE, CALIFORNIA SP Amer Inst Phys, Magnet Soc Inst Elect & Electr Engineers, Minerals Met & Mat Soc, Amer Soc Testing & Mat, USN Off Res, Amer Ceram Soc, Amer Phys Soc AB Cryogenic magnetostrictive materials, such as rare earth zinc crystals, offer high strains and high forces with minimally applied magnetic fields, making the material ideally suited for deformable optics applications. For cryogenic temperature applications, such as Next Generation Space Telescope, the use of superconducting magnets offer the possibility of a persistent mode of operation, i.e., the magnetostrictive material will maintain a strain field without power. High temperature superconductors (HTS) are attractive options if the temperature of operation is higher than 10 degrees Kelvin (K) and below 77 K. However, HTS wires have constraints that limit the minimum radius of winding, and even if good wires can be produced, the technology for joining superconducting wires does not exist. In this article, the design and capabilities of a rare earth zinc magnetostrictive actuator using bulk HTS is described. Bulk superconductors can be fabricated in the sizes required with excellent superconducting properties. Equivalent permanent magnets, made with this inexpensive material, are persistent, do not require a persistent switch as in HTS wires, and can be made very small. These devices are charged using a technique which is similar to the one used for charging permanent magnets, e.g., by driving them into saturation. A small normal conducting coil can be used for charging or discharging. Very fast charging and discharging of HTS tubes, as short as 100 mu s, has been demonstrated. Because of the magnetic field capability of the superconductor material, a very small amount of superconducting magnet material is needed to actuate the rare earth zinc. In this article, several designs of actuators using YBCO and BSCCO 2212 superconducting materials are presented. Designs that include magnetic shielding to prevent interaction between adjacent actuators will also be described. Preliminary experimental results and comparison with theory for BSSCO 2212 with a magnetostrictive element will be discussed. (C) 2000 American Institute of Physics. [S0021-8979(00)82208-2]. C1 USN, Ctr Surface Warfare, Carderock, MD 20817 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. MIT, Cambridge, MA 02139 USA. RP Teter, JP (reprint author), USN, Ctr Surface Warfare, Carderock, MD 20817 USA. NR 7 TC 4 Z9 4 U1 0 U2 3 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 1 PY 2000 VL 87 IS 9 BP 6313 EP 6315 DI 10.1063/1.372690 PN 3 PG 3 WC Physics, Applied SC Physics GA 308TK UT WOS:000086728800137 ER PT J AU Meneghini, R Liao, L AF Meneghini, R Liao, L TI Effective dielectric constants of mixed-phase hydrometeors SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID RADAR BACKSCATTERING; COMPOSITE-MATERIALS; SCATTERING; PARTICLES; PERMITTIVITY; ABSORPTION; DROPLETS; SNOW AB Melting snow, graupel, and hail are often modeled as uniform mixtures of air-ice-water or ice-water. Two-layered models have also been proposed in which the particle consists of a dry snow or ice core surrounded by water or a wet snow mixture. For bath types of particle models, the mixtures are characterized by effective dielectric constants. This information, along with particle shape, size, and orientation, provides the necessary data for calculating the scattering characteristics of the particles. The most commonly used formulas for the effective dielectric constant, epsilon(eff), are those of Maxwell Garnett and Bruggeman. To understand the applicability and limitations of these formulas, an expression for epsilon(eff) is derived that depends on the mean internal electric fields within each component of the mixture. Using a conjugate gradient numerical method, the calculations are carried out for ice-water mixtures. Parameterization of the results in terms of the fractional water volume and the electromagnetic wavelength provides an expression for epsilon(eff) for wavelengths between 3 and 28 mm. To circumvent the laborious task of parameterizing epsilon(eff) with wavelength for air-ice-water mixtures, several approximate formulations are proposed. Tests of the accuracy of the formulas are made by calculating the mean and variance from different particle realizations and by comparison to a previous method. Tests of the applicability of the formulas for epsilon(eff) are made by changing the shape, size, and orientations of the inclusions. While the formulas are adequate over a certain range of inclusion sizes and for a change in shape from cubic to spherical, they are not applicable to highly eccentric, aligned inclusions such as rods or plates. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Caelum Res Co, Rockville, MD USA. RP Meneghini, R (reprint author), NASA, Goddard Space Flight Ctr, Code 975, Greenbelt, MD 20771 USA. EM bob@priam.gsfc.nasa.gov NR 32 TC 30 Z9 31 U1 1 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0739-0572 EI 1520-0426 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD MAY PY 2000 VL 17 IS 5 BP 628 EP 640 DI 10.1175/1520-0426(2000)017<0628:EDCOMP>2.0.CO;2 PG 13 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 319ET UT WOS:000087329100004 ER PT J AU Vitt, FM Cravens, TE Jackman, CH AF Vitt, FM Cravens, TE Jackman, CH TI A two-dimensional model of thermospheric nitric oxide sources and their contributions to the middle atmospheric chemical balance SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article ID PARABOLIC METHOD PPM; ODD NITROGEN; 2-DIMENSIONAL MODEL; UPPER-STRATOSPHERE; POLAR VORTEX; MESOSPHERE; TRANSPORT; NO; SIMULATIONS; VARIABILITY AB The NASA/Goddard Space Flight Center two-dimensional (GSFC 2D) photochemical transport model has been used to study the influence of thermospheric NO on the chemical balance of the middle atmosphere. Lower thermospheric NO sources are included in the GSFC 2D model in addition to the sources that are relevant to the stratosphere. A time series of hemispheric auroral electron power has been used to modulate the auroral NO production in the auroral zone. A time series of the Ottawa 10.7-cm solar flux index has been used as a proxy to modulate NO production at middle and low latitudes by solar EUV and soft X-rays. An interhemispheric asymmetry is calculated for the amounts of odd nitrogen in the polar stratosphere. We compute a 50 degrees) due to thermospheric sources, whereas we compute a < similar to 8% enhancement in the NOy budget in the south polar stratosphere (latitude > 50 degrees). (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Sterling Software, Bellevue, NE 68055 USA. Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Vitt, FM (reprint author), 1278 Banner Circle, Erie, CO 80516 USA. RI Jackman, Charles/D-4699-2012 NR 49 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 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD MAY PY 2000 VL 62 IS 8 BP 653 EP 667 DI 10.1016/S1364-6826(00)00049-3 PG 15 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 335HG UT WOS:000088237600004 ER PT J AU Vitt, FM Armstrong, TP Cravens, TE Dreschhoff, GAM Jackman, CH Laird, CM AF Vitt, FM Armstrong, TP Cravens, TE Dreschhoff, GAM Jackman, CH Laird, CM TI Computed contributions to odd nitrogen concentrations in the Earth's polar middle atmosphere by energetic charged particles SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article ID SOLAR PROTON EVENTS; COSMIC-RAYS; ICE CORES; 2-DIMENSIONAL MODEL; ANTARCTIC FIRN; NITRIC-OXIDE; NITRATE FLUX; SOUTH-POLE; PRECIPITATION; STRATOSPHERE AB A two-dimensional photochemical transport model which has inputs that characterize the odd nitrogen production associated with galactic cosmic rays, solar particle events (SPEs), and lower thermospheric contributions (auroral electrons and solar EUV and soft X-rays) is used to compute odd nitrogen concentrations in the polar middle atmosphere from 1 January 1970 to 31 December 1994. We are able to separate out of the total odd nitrogen budget the contributions of the energetic charged particles according to type. The SPE contributions to annual average odd nitrogen concentrations in the polar stratosphere (latitudes > 50 degrees) are computed to be significant (>10%) only for the larger events of August 1972 and October 1989. The SPE contributions to odd nitrogen concentrations in the polar middle atmosphere are found to be asymmetric with respect to hemispheres. The computed SPE contributions to odd nitrogen concentrations at 30 km are significant more often over the South Pole than the North Pole. The thermospheric contributions to odd nitrogen concentrations in the polar middle atmosphere are asymmetric with respect to hemispheres. A stronger thermospheric influence in the stratosphere is computed over the South Pole than the North Pole, An attempt has been made to compare the modeled odd nitrogen of the polar middle atmosphere to an ultra-high resolution polar ice cap nitrate sequence to examine the hypothesis that the nitrate sequences exhibit a signal associated with energetic particles. Variations of odd nitrogen production and modeled concentrations associated with energetic particles themselves cannot explain all of the huge variations observed in the fine structure present in nitrate data from the polar ice cap nitrates, but may be able to explain Darts of some of them, (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Sterling Software, Bellevue, NE 68055 USA. Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA. Univ Kansas, Space Technol Ctr, Radiat Phys Lab, Lawrence, KS 66045 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Fundamental Technol LLC, Lawrence, KS USA. RP Vitt, FM (reprint author), Sterling Software, 1404 Ft Crook Rd S, Bellevue, NE 68055 USA. EM francis.vitt@sterling.com RI Jackman, Charles/D-4699-2012 NR 57 TC 22 Z9 22 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD MAY PY 2000 VL 62 IS 8 BP 669 EP 683 DI 10.1016/S1364-6826(00)00048-1 PG 15 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 335HG UT WOS:000088237600005 ER PT J AU Tarasov, PE Volkova, VS Webb, T Guiot, J Andreev, AA Bezusko, LG Bezusko, TV Bykova, GV Dorofeyuk, NI Kvavadze, EV Osipova, IM Panova, NK Sevastyanov, DV AF Tarasov, PE Volkova, VS Webb, T Guiot, J Andreev, AA Bezusko, LG Bezusko, TV Bykova, GV Dorofeyuk, NI Kvavadze, EV Osipova, IM Panova, NK Sevastyanov, DV TI Last glacial maximum biomes reconstructed from pollen and plant macrofossil data from northern Eurasia SO JOURNAL OF BIOGEOGRAPHY LA English DT Article DE biomes; Former Soviet Union; last glacial maximum; Mongolia; plant functional types; pollen data; vegetation changes; vegetation map ID GENERAL-CIRCULATION MODEL; ATMOSPHERIC CIRCULATION; ICE SHEETS; EUROPE; PATTERNS; SENSITIVITY; INSOLATION; VEGETATION; CLIMATE; RECORD AB Pollen and plant macrofossil data from northern Eurasia were used to reconstruct the vegetation of the last glacial maximum (LGM: 18,000 +/- 2000 C-14 yr BP) using an objective quantitative method for interpreting pollen data in terms of the biomes they represent (Prentice Et al., 1996). The results confirm previous qualitative vegetation reconstructions at the LGM but provide a more comprehensive analysis of the data. Tundra dominated a large area of northern Eurasia (north of 57 degreesN) to the west, south and east of the Scandinavian ice sheet at the LGM. Steppe-like vegetation was reconstructed in the latitudinal band from western Ukraine, where temperate deciduous forests grow today, to western Siberia, where taiga and cold deciduous forests grow today. The reconstruction shows that steppe graded into tundra in Siberia, which is not the case today. Taiga grew on the northern coast of the Sea of Azov, about 1500 km south of its present limit in European Russia. In contrast, taiga was reconstructed only slightly south of its southern limit today in south-western Siberia. Broadleaved trees were confined to small refuges, e.g. on the eastern coast of the Black Sea, where cool mixed forest was reconstructed from the LGM data. Cool conifer forests in western Georgia were reconstructed as growing more than 1000 m lower than they grow today. The few scattered sites with LGM data from the Tien-Shan Mountains and from northern Mongolia yielded biome reconstructions of steppe and taiga, which are the biomes growing there today. C1 Moscow MV Lomonosov State Univ, Dept Geog, Moscow 119899, Russia. Fac St Jerome, Lab Bot Hist & Palynol, CNRS, UA 1152, F-13397 Marseille 20, France. Russian Acad Sci, Siberian Branch, Inst Geol, Novosibirsk 630090, Russia. Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Natl Acad Sci Ukraine, Inst Bot, UA-252601 Kiev, Ukraine. Russian Acad Sci, Ural Branch, Inst Plant & Anim Ecol, Sverdlovsk 620219, Russia. Russian Acad Sci, Inst Evolut & Ecol, Moscow 109017, Russia. Georgian Acad Sci, Inst Palaeobiol, GE-380004 Tbilisi, Rep of Georgia. Cent Geol Lab, Moscow, Russia. Russian Acad Sci, Ural Branch, Forest Inst, Ekaterinburg 620134, Russia. St Petersburg State Univ, Dept Geog & Geoecol, St Petersburg 199178, Russia. RP Tarasov, PE (reprint author), Moscow MV Lomonosov State Univ, Dept Geog, Moscow 119899, Russia. RI Guiot, Joel/G-7818-2011; Sevastyanov, Dmitrii/G-3100-2015; Andreev, Andrei/J-2701-2015 OI Guiot, Joel/0000-0001-7345-4466; Sevastyanov, Dmitrii/0000-0002-5141-3679; NR 85 TC 172 Z9 186 U1 5 U2 51 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0305-0270 J9 J BIOGEOGR JI J. Biogeogr. PD MAY PY 2000 VL 27 IS 3 BP 609 EP 620 DI 10.1046/j.1365-2699.2000.00429.x PG 12 WC Ecology; Geography, Physical SC Environmental Sciences & Ecology; Physical Geography GA 388KP UT WOS:000166179900005 ER PT J AU Khine, YY Walker, JS Szofran, FR AF Khine, YY Walker, JS Szofran, FR TI Thermoelectric magnetohydrodynamic flow during crystal growth with a moderate or weak magnetic field SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE thermoelectromagnetic convection; Bridgman growth AB This paper treats a steady, axisymmetric melt motion in a cylindrical ampoule with a uniform, axial magnetic field and with an electric current due to a radial temperature variation along the crystal-melt interface, where the values of the absolute thermoelectric power for the crystal and melt an different. The radial component of the thermoelectric current in the melt produces an azimuthal body force, and the axial variation of the centrifugal force due to the azimuthal motion drives a meridional circulation with radial and axial velocities. For moderate magnetic field strengths, the azimuthal velocity and magnetic field produce a radially induced electric field which partially cancels the Seebeck electromotive force in the melt, so that the thermoelectric current and the melt motion are coupled. For weak magnetic fields, the thermoelectric current is decoupled from the melt motion, which is an ordinary hydrodynamic flow driven by a known azimuthal body force. The results show how the flow varies with the strength of the magnetic field and with the magnitude of the temperature variation along the crystal-melt interface. They also define the parameter ranges for which the simpler weak-field decoupled analysis gives accurate predictions. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Illinois, Dept Mech & Ind Engn, Urbana, IL 61801 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Walker, JS (reprint author), Univ Illinois, Dept Mech & Ind Engn, 1206 W Green St, Urbana, IL 61801 USA. NR 11 TC 12 Z9 16 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 2000 VL 212 IS 3-4 BP 584 EP 596 DI 10.1016/S0022-0248(00)00209-8 PG 13 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 310GY UT WOS:000086819200029 ER PT J AU Grun, E Landgraf, M AF Grun, E Landgraf, M TI Collisional consequences of big interstellar grains SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article; Proceedings Paper CT ISSI Workshop on Interstellar Dust and the Heliosphere CY 1998 CL BERN, SWITZERLAND SP ISSI ID SIZE DISTRIBUTION; DUST; ULYSSES; INTERPLANETARY; DESTRUCTION; DISCOVERY; VELOCITY; GALILEO; SHOCKS; GAS AB Identification by the Ulysses spacecraft of interstellar grains inside the planetary system provides a new window for the study of diffuse interstellar matter. Dust particles observed by Ulysses and confirmed by Galileo are more massive (greater than or equal to 10(-13) g) than the "classical" interstellar grains. Even bigger grains (approximate to 10(-7) g) were observed in form of interstellar meteors. We analyze the consequences of the plentiful existence of massive grains in the diffuse interstellar medium. Astronomically observed classical interstellar grains can be described by a size distribution ranging from similar to 5 to 250 nm in radius (similar to 10(-18) to 10(-13) g). Lifetimes of these particles, owing to mutual collisions in interstellar space, can be as short as 10(5) f years, where f = 10 to 1000, is the fraction of total lifetime to the time when grains are exposed to supernova shocks. Shattering is a source of the smallest of these grains, but grains more massive than similar to 10(-16) g Of the classical interstellar grain population are rapidly destroyed. When applying the same shattering mechanism to the more massive grains found recently, we suggest that collisions of particles bigger than similar to 10(-15) g provide a source for smaller grains. Because massive grains couple to the interstellar gas only over large (100 to 1000 pc) length scales, the cosmic abundance ratio of gas-to-dust needs only to be preserved averaged over corresponding volumes of space. C1 Max Planck Inst Kernphys, D-69117 Heidelberg, Germany. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Grun, E (reprint author), Max Planck Inst Kernphys, D-69117 Heidelberg, Germany. NR 28 TC 27 Z9 27 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 2000 VL 105 IS A5 BP 10291 EP 10297 DI 10.1029/1999JA900424 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309AQ UT WOS:000086745400007 ER PT J AU Landgraf, M AF Landgraf, M TI Modeling the motion and distribution of interstellar dust inside the heliosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTER-STELLAR GRAINS; MAGNETIC-FIELD; ULYSSES; PARTICLES; GALILEO AB The interaction of dust grains originating from the local interstellar cloud with the environment inside the heliosphere is investigated. As a consequence of this interaction, the spatial distribution of interstellar dust grains changes with time. Since dust grains are charged in the interplanetary plasma and radiation environment, the interaction of small grains with the heliosphere is dominated by their coupling to the solar wind magnetic field. The change of the field polarity with the solar cycle imposes a temporal variation of the spatial distribution and the flux of small (radius smaller than 0.4 mu m) interstellar dust grains in the solar system, whereas the flux of large grains is constant because of their negligible coupling to the solar wind magnetic field. The flux variation observed by in situ measurements of the Galileo and Ulysses spacecraft are reproduced by simulating the interaction of interstellar grains with charge-to-mass ratios between 0.5 and 1.4 C kg(-1) with the interplanetary environment. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Landgraf, M (reprint author), NASA, Lyndon B Johnson Space Ctr, Mailcode SN2,2101 NASA Rd 1, Houston, TX 77058 USA. NR 26 TC 71 Z9 72 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 MAY 1 PY 2000 VL 105 IS A5 BP 10303 EP 10316 DI 10.1029/1999JA900243 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309AQ UT WOS:000086745400009 ER PT J AU Landgraf, M Baggaley, WJ Grun, E Kruger, H Linkert, G AF Landgraf, M Baggaley, WJ Grun, E Kruger, H Linkert, G TI Aspects of the mass distribution of interstellar dust grains in the solar system from in situ measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SIZE DISTRIBUTION; ULYSSES; GALILEO; PARTICLES; SHOCKS; GAS AB The in situ detection of interstellar dust grains in the solar system by the dust instruments on-board the Ulysses and Galileo spacecraft as well as the recent measurements of hyperbolic radar meteors give information on the properties of the interstellar solid particle population in the solar vicinity. Especially the distribution of grain masses is indicative of growth and destruction mechanisms that govern the grain evolution in the interstellar medium. The mass of an impacting dust grain is derived from its impact velocity and the amount of plasma generated by the impact. Because the initial velocity and the dynamics of interstellar particles in the solar system are well known, we use an approximated theoretical instead of the measured impact velocity to derive the mass of interstellar grains from the Ulysses and Galileo in situ data. The revised mass distributions are steeper and thus contain less large grains than the ones that use measured impact velocities, but large grains still contribute significantly to the overall mass of the detected grains. The flux of interstellar grains with masses > 10(-14) kg is determined to be 1 x 10(-6) m(-2) s(-1) The comparison of radar data with the extrapolation of the Ulysses and Galileo mass distribution indicates that the very large (m > 10(-10) kg) hyperbolic meteoroids detected by the radar are not kinematically related to the interstellar dust population detected by the spacecraft. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Max Planck Inst Kernphys, D-69117 Heidelberg, Germany. Univ Canterbury, Dept Phys & Astron, Christchurch 1, New Zealand. RP Baggaley, WJ (reprint author), NASA, Lyndon B Johnson Space Ctr, Mailcode SN2,2101 NASA Rd 1, Houston, TX 77058 USA. NR 22 TC 114 Z9 114 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 MAY 1 PY 2000 VL 105 IS A5 BP 10343 EP 10352 DI 10.1029/1999JA900359 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309AQ UT WOS:000086745400012 ER PT J AU Nuth, JA Hallenbeck, SL Rietmeijer, FJM AF Nuth, JA Hallenbeck, SL Rietmeijer, FJM TI Laboratory studies of silicate smokes: Analog studies of circumstellar materials SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID RICH AGB STARS; INTERSTELLAR GRAINS; SIZE DISTRIBUTION; DUST GRAINS; CONDENSATION; SHOCKS; MINERALOGY; ENVELOPES; ABUNDANCE; SYSTEM AB Grains entering our solar system at the heliopause or encountered by an interstellar probe will be dominated by materials formed in carbon-rich and oxygen-rich outflows from high mass-loss-rate AGE stars with moderate contributions from novae and supernovae. Laboratory studies of the condensation and thermal evolution of silicate grains have greatly increased our understanding of grain formation processes and may provide the basis for theoretical prediction of chemical speciation and spectral evolution of grains produced in specific stellar outflows. These grains will be modified by long-term exposure to high-energy cosmic rays, thus rendering them amorphous, and will potentially be coated by one or more layers of refractory carbonaceous material. This coating results when radiation-damaged organic-rich water ices are allowed to sublime in vacuum during the transition from the interior of a dense molecular cloud to the warm interstellar medium. Measurement of the chemical compositions of large numbers of individual grains in the local interstellar medium could lead to a better understanding of the life cycle of grains in the general interstellar medium. Such measurements might also serve as a diagnostic indicator of the primary source of interstellar grains: origin in stellar outflows or in the interstellar medium itself. These measurements would be possible using an impact-ionization, time-of-flight, mass spectrometer during the cruise phase of an interstellar probe mission. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA Headquarters, Washington, DC 20546 USA. Univ New Mexico, Inst Meteorit, Dept Earth & Planetary Sci, Albuquerque, NM USA. RP Nuth, JA (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM nuth@gsfc.nasa.gov RI Nuth, Joseph/E-7085-2012 NR 40 TC 41 Z9 41 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 MAY 1 PY 2000 VL 105 IS A5 BP 10387 EP 10396 DI 10.1029/1999JA900432 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309AQ UT WOS:000086745400016 ER PT J AU Grun, E Landgraf, M Horanyi, M Kissel, J Kruger, H Srama, R Svedhem, H Withnell, P AF Grun, E Landgraf, M Horanyi, M Kissel, J Kruger, H Srama, R Svedhem, H Withnell, P TI Techniques for galactic dust measurements in the heliosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article; Proceedings Paper CT ISSI Workshop on Interstellar Dust and the Heliosphere CY 1998 CL BERN, SWITZERLAND SP ISSI ID INTERSTELLAR DUST; ULYSSES; GRAINS; SPACECRAFT; PARTICLES; DISCOVERY; DETECTORS; VELOCITY; GALILEO; MISSION AB Galactic interstellar dust (ISD) is the major ingredient in planetary formation. However, information on this important material has been extremely limited. Recently, the Ulysses dust detector has identified and measured interstellar dust outside 1.8 AU from the Sun at ecliptic latitudes above 50 degrees, Inside this distance it could not reliably distinguish interstellar from interplanetary dust. Modeling the Ulysses data suggests that up to 30% of dust flux with masses above 10(-16) kg at 1 AU is of interstellar origin. From the Hiten satellite in high eccentric orbit about the Earth, there are indications that ISD indeed reaches the Earth's orbit. Two new missions carrying dust detectors, Cassini and Stardust, will greatly increase our observational knowledge. In this paper we briefly review instruments used on these missions and compare their capabilities. The Stardust mission [Brownlee et al,, 1996] will analyze the local interstellar dust population by an in situ chemical analyzer and collect ISD between 2 and 3 AU from the Sun. The dust analyzer on the Cassini mission will determine the interstellar dust flux outside Venus' orbit and will provide also some compositional information. Techniques to identify the ISD flux levels at 1 AU are, described that can quantify the interstellar dust flux in high Earth orbit (outside the debris belts) and provide chemical composition information of galactic dust. C1 Max Planck Inst Kernphys, D-69029 Heidelberg, Germany. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. European Space Technol Ctr, NL-2200 AG Noordwijk, Netherlands. RP Grun, E (reprint author), Max Planck Inst Kernphys, Postfach 10 39 80, D-69029 Heidelberg, Germany. OI Horanyi, Mihaly/0000-0002-5920-9226 NR 26 TC 24 Z9 24 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 MAY 1 PY 2000 VL 105 IS A5 BP 10403 EP 10410 DI 10.1029/1999JA900376 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309AQ UT WOS:000086745400018 ER PT J AU McComas, DJ Barraclough, BL Funsten, HO Gosling, JT Santiago-Munoz, E Skoug, RM Goldstein, BE Neugebauer, M Riley, P Balogh, A AF McComas, DJ Barraclough, BL Funsten, HO Gosling, JT Santiago-Munoz, E Skoug, RM Goldstein, BE Neugebauer, M Riley, P Balogh, A TI Solar wind observations over Ulysses' first full polar orbit SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID STREAMER BELT; PLASMA; HELIUM; SPEED; LATITUDES; MINIMUM AB This study examines solar wind plasma and magnetic field observations from Ulysses' first full polar orbit in order to characterize the high-latitude solar wind under conditions of decreasing and low solar activity. By comparing observations taken over nearly all heliolatitudes and two different intervals covering the same radial distances, we are able to separate the radial and latitudinal variations in the solar wind. We find that once the radial gradients are removed, none of the high-latitude solar wind parameters show much latitudinal variation, indicating that the solar wind emanating from the polar coronal holes is extremely uniform. In addition, by examining nearly 6 years of data starting in the declining phase of the last solar cycle and extending through the most recent solar minimum, we are able to address hemispheric asymmetries in the observations. We find that these asymmetries are most likely driven by differences in the solar wind source over the solar cycle and indicate that Inert energy goes into the polar solar wind during the declining phase of the solar cycle than around minimum. Because the mass flux is larger in the declining phase while the speeds are very similar, we conclude that this energy is introduced at an altitude below the solar wind acceleration critical point. Finally, we provide details of the statistics of over 20 solar wind parameters so that upcoming observations from Ulysses' second polar orbit, during much more active times on the Sun, can be readily compared to the quieter first orbit results. C1 Los Alamos Natl Lab, Los Alamos, NM USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Sci Applicat Int Corp, San Diego, CA 92121 USA. Univ London Imperial Coll Sci Technol & Med, Dept Phys, London SW7 2AZ, England. RP McComas, DJ (reprint author), Los Alamos Natl Lab, MS-D466, Los Alamos, NM USA. RI Funsten, Herbert/A-5702-2015 OI Funsten, Herbert/0000-0002-6817-1039 NR 36 TC 292 Z9 294 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 MAY 1 PY 2000 VL 105 IS A5 BP 10419 EP 10433 DI 10.1029/1999JA000383 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309AQ UT WOS:000086745400020 ER PT J AU Berger, MA Ruzmaikin, A AF Berger, MA Ruzmaikin, A TI Rate of helicity production by solar rotation SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MAGNETIC-FIELDS; QUIESCENT PROMINENCES; ATMOSPHERE; STRENGTH; MODEL; SUN AB In recent years, solar observers have discovered a striking pattern in the distribution of coronal magnetic structures: northern hemisphere structures tend to have negative magnetic helicity, while structures in the south tend to have positive magnetic helicity. This hemispheric dependence extends from photospheric observations to in situ measurements of magnetic clouds in the solar wind. Understanding the source of the hemispheric sign dependence, as well as its implications for solar and space physics has become known as the solar chirality problem. Rotation of open fields creates the Parker spiral which carries outward 10(47) Mx(2) of magnetic helicity tin each hemisphere) during a solar cycle. In addition, rough estimates suggest that each hemisphere sheds on the order 10(45) Mx(2) in coronal mass ejections each cycle. Both the alpha effect (arising from helical turbulence) and the Omega effect (arising from differential rotation) should contribute to the hemispheric chirality. We show that the Omega effect contribution can be captured in a surface integral, even though the helicity itself is stored deep in the convection zone. We then evaluate this surface integral using solar magnetogram data and differential rotation curves. Throughout the 22 year cycle studied (1976 -1998) the helicity production in the interior by differential rotation had the correct sign compared to observations of coronal structures - negative in the north and positive in the south. The net helicity flow into each hemisphere over this cycle was approximately 4 x 10(46) Mx(2). For comparison, we estimate the ct effect contribution; this may well be as high or higher than the differential rotation contribution. The subsurface helicity can be transported to the corona with buoyant rising flux tubes. Evidently only a small fraction of the subsurface helicity escapes to the surface to supply coronal mass ejections. C1 UCL, Dept Math, London WC1E 6BT, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Berger, MA (reprint author), UCL, Dept Math, Gower St, London WC1E 6BT, England. EM m.berger@ucl.ac.uk; aruzmaik@jpl.nasa.gov NR 46 TC 92 Z9 94 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 2000 VL 105 IS A5 BP 10481 EP 10490 DI 10.1029/1999JA900392 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309AQ UT WOS:000086745400024 ER PT J AU Burlaga, LF Richardson, JD AF Burlaga, LF Richardson, JD TI North-south flows at 47 AU: A heliospheric vortex street? SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; OUTER HELIOSPHERE; PLASMA-FLOW; DISTANT HELIOSPHERE; PICKUP PROTONS; MAGNETIC-FIELD AB A north-south how pattern with a recurrence period approximately equal to the solar rotation period was observed by Voyager 2 during 1995 at 47 AU, nearly a solar cycle after the north-south flows were first observed near 21 AU during 1986. The north-south flow deflections observed during 1995 were less regular than those observed in 1986. One finds the same qualitative associations between the north-south flows and bulk speed and temperature that were observed in 1986, but the correlations are weaker at the larger distances and higher latitudes. Thus it appears that the flow observed during 1995 is basically the same kind of flow observed in 1986, but it is much less regular owing to evolutionary effects as the flow moves from 21 AU to 47 AU. The observations are consistent with the several predictions of the vortex street model. They fail to support some predictions of both the interaction region model and the vortex street models. It is possible that both a vortex street and interaction regions are significant near solar minimum between 20 and 50 AU. Further development of the models is needed. The interaction models must be extended to include time variations, and the effects of pickup protons should be included in future models of the north-south flows. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. RP Burlaga, LF (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Mail Code 692, Greenbelt, MD 20771 USA. EM burlaga@lepvax.gsfc.nasa.gov; jdr@space.mit.edu NR 24 TC 11 Z9 11 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 2000 VL 105 IS A5 BP 10501 EP 10507 DI 10.1029/1999JA000376 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309AQ UT WOS:000086745400026 ER PT J AU Feynman, J Gabriel, SB AF Feynman, J Gabriel, SB TI On space weather consequences and predictions SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Review ID CORONAL MASS EJECTIONS; COSMIC-RAY MODULATION; SOLAR MAGNETIC-FIELD; GEOMAGNETIC-ACTIVITY; IN-SPACE; 3-DIMENSIONAL PROPAGATION; RELATIVISTIC ELECTRONS; PROTON EVENTS; WIND; INTERPLANETARY AB This paper focuses on the question of what needs to be predicted and what processes need to be understood to predict and forecast space weather conditions that are hazardous to current technology. The paper's aim is to see if we are working on the correct space parameters to permit prediction of those quantities that actually present hazards to current space technology. The paper is not intended to be encyclopedic. We conclude that although the sunspot number is a general proxy for many space hazards, there is surprisingly little direct need for its accurate prediction or for the prediction of solar flares as such. We also find that knowledge of Kp and other geomagnetic indices are rarely directly required. Important gaps in our knowledge exist concerning the variations of storm time electron, proton, and ion populations within the magnetosphere. Work is also required in predicting fast coronal mass ejections (CMEs) and in understanding the processes of CME initiation and acceleration within the corona and high energy solar particle acceleration and propagation. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Southampton, Dept Aeronaut & Astronaut, Southampton SO9 5NH, Hants, England. RP Feynman, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 104 TC 88 Z9 89 U1 1 U2 8 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 2000 VL 105 IS A5 BP 10543 EP 10564 DI 10.1029/1999JA000141 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309AQ UT WOS:000086745400031 ER PT J AU Kauristie, K Sergeev, VA Kubyshkina, M Pulkkinen, TI Angelopoulos, V Phan, T Lin, RP Slavin, JA AF Kauristie, K Sergeev, VA Kubyshkina, M Pulkkinen, TI Angelopoulos, V Phan, T Lin, RP Slavin, JA TI Ionospheric current signatures of transient plasma sheet flows SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID BURSTY BULK FLOWS; HIGH-SPEED FLOWS; FLUX TUBES; TAIL; MAGNETOTAIL; ASSOCIATION; DIPOLARIZATION; MAGNETOSPHERE; ALGORITHM; GEOTAIL AB The plasma flow in the central plasma sheet of the magnetospheric tail often includes short impulsive bursts. Here we investigate the ionospheric signatures of such bursts. The Wind satellite recorded several transient fast flows in the plasma sheet (at geocentric distances of similar to 12 R-E) on December 21-22, 1995. The data are compared with magnetic field observations made in the Scandinavian sector, at the ionospheric conjugate point of the satellite. Superposed epoch analysis of the satellite data suggests that most of the events are Earthward flow bursts accompanied by magnetic dipolarizations, increases in the convection electric field, and drops in the plasma pressure and density. Occasionally, also isolated tailward flow bursts within closed flux tubes can be observed. We demonstrate that in both cases the transient plasma sheet flows are systematically associated with distinct ground magnetic field variations which (after 90 degrees rotation) have specific vortex-like spatial distributions. The vortex patterns have similar duration to that of the flows at Wind and their longitudinal extent (less than or equal to 1 hour in local time) is consistent with the azimuthal scale sizes (similar to 3 R-E) Of the transient flows reported earlier. In many cases the sense of flow rotation observed at Wind and at Wind's ionospheric footpoint agree with our expectation. Despite the care taken in accounting for the instantaneous and local currents that affect the mapping, uncertainties in the footpoint location may still be responsible of the absence of a higher degree for compliance with theory. C1 Finnish Meteorol Inst, FIN-00101 Helsinki, Finland. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. St Petersburg State Univ, Inst Phys, St Petersburg 198904, Russia. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Kauristie, K (reprint author), Finnish Meteorol Inst, POB 503, FIN-00101 Helsinki, Finland. RI Slavin, James/H-3170-2012; Kubyshkina, Marina/G-9436-2013; Pulkkinen, Tuija/D-8403-2012; Sergeev, Victor/H-1173-2013 OI Slavin, James/0000-0002-9206-724X; Kubyshkina, Marina/0000-0001-5897-9547; Pulkkinen, Tuija/0000-0002-6317-381X; Sergeev, Victor/0000-0002-4569-9631 NR 31 TC 64 Z9 65 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-SPACE JI J. Geophys. Res-Space Phys. PD MAY 1 PY 2000 VL 105 IS A5 BP 10677 EP 10690 DI 10.1029/1999JA900487 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309AQ UT WOS:000086745400041 ER PT J AU Gary, SP Winske, D Hesse, M AF Gary, SP Winske, D Hesse, M TI Electron temperature anisotropy instabilities: Computer simulations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID AURORAL KILOMETRIC RADIATION; WHISTLER-MODE WAVES; POLAR-CAP; DE-1 OBSERVATIONS; RADIO EMISSIONS; PLASMA; MAGNETOSPHERE; GENERATION; DAYSIDE; REGION AB An electron temperature anisotropy T-perpendicular to e/T-parallel to e > 1 leads to excitation of three distinct modes, the whistler, the electrostatic, and the Z-mode instabilities, in collisionless plasmas at frequencies below the electron cyclotron frequency \Omega(e)\. (Here perpendicular and parallel subscripts denote directions relative to the background magnetic field.) Two-and-one-half-dimensional particle-in-cell simulations are used to study the nonlinear consequences of the growth of these modes in homogeneous plasmas with omega(e) similar to \Omega(e)\, where omega(e) is the electron plasma frequency. The simulations show that wave-particle scattering by enhanced fluctuations from the whistler and electrostatic anisotropy instabilities imposes a beta-dependent upper bound on the electron temperature anisotropy at beta(parallel to e) less than or equal to 0.10 The simulations also demonstrate that the maximum value of the dimensionless fluctuating magnetic fields increases with PII, and that at sufficiently low beta the electrostatic instability leads to non-Maxwellian suprathermal enhancements on the reduced electron velocity distribution f(e)(nu(parallel to)). C1 Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Gary, SP (reprint author), Univ Calif Los Alamos Natl Lab, MS D466, Los Alamos, NM 87545 USA. RI Hesse, Michael/D-2031-2012 NR 29 TC 29 Z9 30 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 2000 VL 105 IS A5 BP 10751 EP 10759 DI 10.1029/1999JA000322 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 309AQ UT WOS:000086745400047 ER PT J AU Schroeder, JA Chung, WWY AF Schroeder, JA Chung, WWY TI Simulator platform motion effects on pilot-induced oscillation prediction SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article; Proceedings Paper CT AIAA Atmospheric Flight Mechanics Conference CY AUG 10-12, 1998 CL BOSTON, MASSACHUSETTS SP Amer Inst Aeronaut & Astronaut AB Simulator motion platform characteristics were examined to determine if the amount of motion affects pilot-induced oscillation prediction. Five test pilots evaluated how susceptible 18 different sets of pitch dynamics were to pilot-induced oscillations with three different levels of simulation motion platform displacement: large, small, and none. The pitch dynamics were those of a previous in-flight experiment, some of which elicited oscillations. These in-flight results served as truth data for the simulation. As such, the in-flight experiment was replicated as much as possible. Objective and subjective data were collected and analyzed. With large motion, pilot-induced oscillation and handling qualities ratings matched the flight data more closely than with small motion or no motion, Also, regardless of the aircraft dynamics, targe motion increased pilot confidence in assigning handling qualities ratings, reduced safety pilot trips, and lowered touchdown velocities. Whereas both large and small motion provided a pitch rate cue of high fidelity, only large motion presented the pilot with a high fidelity vertical acceleration cue. C1 NASA, Ames Res Ctr, Flight Control & Cockpit Integrat Branch, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Logicon Informat Syst & Serv, Moffett Field, CA 94035 USA. RP Schroeder, JA (reprint author), NASA, Ames Res Ctr, Flight Control & Cockpit Integrat Branch, Moffett Field, CA 94035 USA. NR 21 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 2000 VL 23 IS 3 BP 438 EP 444 DI 10.2514/2.4578 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 313DT UT WOS:000086985600008 ER PT J AU Scheeres, DJ Williams, BG Miller, JK AF Scheeres, DJ Williams, BG Miller, JK TI Evaluation of the dynamic environment of an asteroid: Applications to 433 Eros SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID ORBITS; BODY; POLYHEDRON; 433-EROS; MISSION AB Methods of analysis to quickly and systematically evaluate the dynamical environment close to an asteroid are presented, concentrating on the effect of the asteroid's gravity field and rotation state on a spacecraft orbit, Such an analysis is useful and needed for missions to small solar system bodies such as asteroids and comets, where the true mass, gravity field, and rotation state will not be known until after the spacecraft rendezvous with the body and these quantities are estimated. Generally, after these quantities have been estimated, the complete mission profile must be redesigned in accordance with the actual values found at the asteroid, An integral part of this, redesign is the characterization of dynamics close to the asteroid, specifically the computation of orbit stability. close to the body and the practical limits on how close the spacecraft can fly to the body before large perturbations are experienced, Numerical computations of such an evaluation applied to the asteroid 433 Eros, the target of the Near Earth Asteroid Rendezvous (NEAR) mission, using preliminary models of the asteroid obtained during NEAR's December 1998 flyby of Eros are presented. C1 Univ Michigan, Dept Aerosp Engn, Ann Arbor, MI 48109 USA. CALTECH, Jet Prop Lab, Navigat & Flight Mech Sect, Pasadena, CA 91109 USA. RP Scheeres, DJ (reprint author), Univ Michigan, Dept Aerosp Engn, 3048 FXB, Ann Arbor, MI 48109 USA. NR 25 TC 88 Z9 94 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 2000 VL 23 IS 3 BP 466 EP 475 DI 10.2514/2.4552 PG 10 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 313DT UT WOS:000086985600012 ER PT J AU Vadali, SR Nah, R Braden, E Johnson, IL AF Vadali, SR Nah, R Braden, E Johnson, IL TI Fuel-optimal planar Earth-Mars trajectories using low-thrust exhaust-modulated propulsion SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID INTERPLANETARY TRAJECTORIES; OPTIMIZATION AB The determination of fuel-optimal, planar, Earth-Mars trajectories of spacecraft using low-thrust, variable specific impulse I-sp propulsion is discussed. The characteristics of a plasma thruster currently being developed for crewed/cargo missions to Mars are used. This device can generate variable I-sp within the range of 1000-,35,000s, at constant power. The state equations are written in rotating, polar coordinates, and the trajectory is divided into two phases, patched together at an intermediate point between the Earth and Mars, The gravitational effects of the sun, Earth, and Mars are included in the two phases. The formulation of the problem treats the spacecraft mass as a state variable, thus, coupling the spacecraft design to the trajectory design. The optimal control problem is solved using an indirect, multiple shooting method. Results for a 144-day crewed mission to Mars are presented. The variation of the I-sp during spacecraft's escape from the Earth's gravitational field shows an interesting periodic behavior with respect to time. The results obtained are also compared with those obtained by assuming a three-phase trajectory, with the Earth, sun, and Mars, influencing the spacecraft, one per phase, in sequence. C1 Texas A&M Univ, Dept Aerosp Engn, College Stn, TX 77843 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Vadali, SR (reprint author), Texas A&M Univ, Dept Aerosp Engn, College Stn, TX 77843 USA. NR 15 TC 37 Z9 41 U1 0 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 2000 VL 23 IS 3 BP 476 EP 482 DI 10.2514/2.4553 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 313DT UT WOS:000086985600013 ER PT J AU Carr, GC Erzberger, H Neuman, F AF Carr, GC Erzberger, H Neuman, F TI Fast-time study of airline-influenced arrival sequencing and scheduling SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB The basic objective of arrival sequencing and scheduling in air traffic control automation is to match traffic demand and airport capacity while minimizing delays. The principle underlying practical sequencing and scheduling algorithms currently in use Is referred to as first-come-first-served (FCFS). Although this principle generates fair schedules when delays must be absorbed, it does not take into account airline priorities among individual flights. The development of new scheduling techniques that consider priorities expressed by air carriers will reduce the economic impact of air traffic management (ATM) restrictions on the airlines. This will also lead to increased airline economic efficiency by affording airlines greater control over their individual arrival banks of aircraft. NASA is exploring the possibility of allowing airlines to express relative arrival priorities to ATM through the development of new sequencing and scheduling algorithms that take into account airline preferences. A method of scheduling a bank of arrival aircraft according to a preferred order of arrival instead of according to an FCFS sequence based on estimated time of arrival at the runway is investigated. past-time simulation is used to evaluate this scheduling method in terms of the algorithm's ability to produce a preferred order of arrival and In terms of its ability to minimize delays (scheduling efficiency). Results show that compared with FCFS scheduling, the alternative scheduling method is often successful in reducing deviations from the preferred bank arrival order while causing little or no increase in delays that must be absorbed. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Raytheon STX Corp, Moffett Field, CA 94035 USA. RP Carr, GC (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 11 TC 8 Z9 9 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 2000 VL 23 IS 3 BP 526 EP 531 DI 10.2514/2.4559 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 313DT UT WOS:000086985600019 ER PT J AU Crassidis, JL Vadali, SR Markley, FL AF Crassidis, JL Vadali, SR Markley, FL TI Optimal variable-structure control tracking of spacecraft maneuvers SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID LARGE-ANGLE MANEUVERS; SLIDING-MODE CONTROL; FEEDBACK C1 Texas A&M Univ, Dept Aerosp Engn, College Stn, TX 77843 USA. NASA, Goddard Space Flight Ctr, Guidance Navigat & Control Ctr, Greenbelt, MD 20771 USA. RP Crassidis, JL (reprint author), Texas A&M Univ, Dept Aerosp Engn, College Stn, TX 77843 USA. NR 9 TC 36 Z9 39 U1 0 U2 5 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 2000 VL 23 IS 3 BP 564 EP 566 DI 10.2514/2.4568 PG 3 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 313DT UT WOS:000086985600027 ER PT J AU Turner, TL AF Turner, TL TI A new thermoelastic model for analysis of shape memory alloy hybrid composites SO JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES LA English DT Article; Proceedings Paper CT 4th Workshop on Smart Structures CY AUG 16-18, 1999 CL PENN STATE UNIV, UNIVERSITY PK, PENNSYLVANIA SP USA, Off Res HO PENN STATE UNIV ID NITINOL-REINFORCED PLATES; ACTIVE VIBRATION; LAMINATED PLATES; FIBERS AB A constitutive model and a finite element formulation are developed for predicting the thermomechanical response of SMA hybrid composite structures subjected to combined thermal and mechanical loads. The constitutive model is valid for constrained, restrained, or free recovery behavior with appropriate measurements of basic SMA material properties. The model captures the material nonlinearity of the SMA with temperature and more accurately captures the mechanics of composites with embedded SMA actuators as compared to other recently developed approaches. The constitutive and finite element models are amenable to commercial code implementation. The fundamental thermoelastic behavior of such structures is described in physical terms and related to the governing equations. It is shown that alloy selection is imperative for achieving the desired performance with respect to the application environment. It is also shown that fundamental efforts to strategically place actuators can produce dramatic performance improvements. Numerical results are shown for glass-epoxy beam specimens with embedded Nitinol actuators. Control of critical buckling temperature, thermal post-buckling deflection, and random response are demonstrated. C1 NASA, Langley Res Ctr, Struct Acoust Branch, Hampton, VA 23681 USA. RP Turner, TL (reprint author), NASA, Langley Res Ctr, Struct Acoust Branch, MS 463, Hampton, VA 23681 USA. NR 33 TC 31 Z9 31 U1 0 U2 7 PU TECHNOMIC PUBL CO INC PI LANCASTER PA 851 NEW HOLLAND AVE, BOX 3535, LANCASTER, PA 17604 USA SN 1045-389X J9 J INTEL MAT SYST STR JI J. Intell. Mater. Syst. Struct. PD MAY PY 2000 VL 11 IS 5 BP 382 EP 394 DI 10.1106/DTFJ-UFL3-XV0U-WJNA PG 13 WC Materials Science, Multidisciplinary SC Materials Science GA 413QP UT WOS:000167623500007 ER PT J AU Lee, MC AF Lee, MC TI Microgravity Fundamental Physics Program for the new millennium SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 2nd International Chernogolovka Workshop on Low Temperature Physics in Microgravity Environment (CWS 99) CY JUL 28-AUG 02, 1999 CL CHERNOGOLOVKA, RUSSIA SP Inst Solid State Physics RAS, RAS Council Cosm Sci, Sect Cosm Mat Sci AB In the new millennium, NASA will probe deeper into space, will search for 'blue' planets and life in the universe, will send humans and robots to other planets and beyond and will bring back space knowledge to enhance quality of life on earth. Far the microgravity fundamental physics program to be vital and relevant, it mv,st contribute to this overall endeavor. NASA's Microgravity Fundamental Physics Program has been designed to serve these bigger goals at the onset of the new millennium. C1 NASA, Washington, DC 20546 USA. RP Lee, MC (reprint author), NASA, Washington, DC 20546 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD MAY PY 2000 VL 119 IS 3-4 BP 195 EP 202 DI 10.1023/A:1004628727386 PG 8 WC Physics, Applied; Physics, Condensed Matter SC Physics GA 305ZF UT WOS:000086571100003 ER PT J AU Israelsson, UE AF Israelsson, UE TI NASA roadmap for fundamental physics research in space SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 2nd International Chernogolovka Workshop on Low Temperature Physics in Microgravity Environment (CWS 99) CY JUL 28-AUG 02, 1999 CL CHERNOGOLOVKA, RUSSIA SP Inst Solid State Physics RAS, RAS Council Cosm Sci, Sect Cosm Mat Sci AB Last year, about 100 fundamental physics researchers met twice to develop plans for the future in this research area. The results of these meetings have been documented in a presentation package titled "A Roadmap for Fundamental Physics in Space". A summary of the Roadmap is presented along with an overview of the current program. Research is being performed in Low Temperature and Condensed Matter Physics, Laser Cooling and Atomic Physics, and Gravitational and Relativistic Physics. There are currently over 50 investigators in the program of which 9 are being evaluated as potential flight experiments. The number of investigators is expected to grow further during the next selection cycle, planned to start toward the end of 1999. Experimentation in Space has until now been limited to short duration flights aboard the Space Shuttle. In the near future, our investigators will be able to take advantage of long duration experimentation in Space using a suite of different carriers tinder development. Experiments needing Lour Temperatures will be performed in a liquid helium facility being developed by JPL and Ball Aerospace. This apparatus will allow multiple investigations each flight and will attach to the ISS Japanese Experiment Module's Ea;posed Facility. Experiments in the Laser Cooling area are developing experiments for the EXPRESS racks inside the ISS US module. Experiments in Gravitational Physics can be performed in the low temperature facility, or can be independent free flyers to fully maximize the benefits inherent in the space environment. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Israelsson, UE (reprint author), CALTECH, Jet Prop Lab, Mailstop 233-200,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 3 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD MAY PY 2000 VL 119 IS 3-4 BP 213 EP 221 DI 10.1023/A:1004632828294 PG 9 WC Physics, Applied; Physics, Condensed Matter SC Physics GA 305ZF UT WOS:000086571100005 ER PT J AU Liu, FC Adriaans, MJ Pensinger, J Israelsson, UE AF Liu, FC Adriaans, MJ Pensinger, J Israelsson, UE TI Research opportunities on The Low Temperature Microgravity Physics Facility on the International Space Station SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 2nd International Chernogolovka Workshop on Low Temperature Physics in Microgravity Environment (CWS 99) CY JUL 28-AUG 02, 1999 CL CHERNOGOLOVKA, RUSSIA SP Inst Solid State Physics RAS, RAS Council Cosm Sci, Sect Cosm Mat Sci ID HIGH-RESOLUTION MEASUREMENTS; SUPERFLUID TRANSITION; HEAT; POINT; HE-4 AB The Low Temperature Microgravity Physics Facility (LTMPF) is a state-of-the-art facility for long duration science investigations whose objectives can only be achieved in microgravity and at low temperature. LTMPF consists of two reusable, cryogenic facilities with self-contained electronics, soft ware and communication capabilities. The Facility will be first launched by Japanese HIIA Rock:et in 2004 with at least five months cryogen lifetime on the Japanese Experiment Module Exposed Facility (JEM EF) of the International Space Station (ISS). Future missions will be launched and retrieved by the Space Shuttle. A number of high precision sensors of temperature, pressure and capacitance will be available, which can be further tailored to accommodate a wide variety of low temperature experiments. This paper will describe the LTMPF and its goals and design requirements. Currently there are six candidate experiments in the flight definition phase to fly on LTMPF. Future candidate experiments will be selected through the NASA Research Announcement(NRA) process. Opportunities for utilization and collaboration with international partners will also be discussed. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Liu, FC (reprint author), CALTECH, Jet Prop Lab, 79-24,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD MAY PY 2000 VL 119 IS 3-4 BP 233 EP 239 DI 10.1023/A:1004636929203 PG 7 WC Physics, Applied; Physics, Condensed Matter SC Physics GA 305ZF UT WOS:000086571100007 ER PT J AU Duncan, RV Sergatskov, DA Boyd, STP McCready, SS McCarson, TD Babkin, AV Day, PK Liu, FC Elliott, D AF Duncan, RV Sergatskov, DA Boyd, STP McCready, SS McCarson, TD Babkin, AV Day, PK Liu, FC Elliott, D TI Dynamic and gravitational effects on the correlation volume: Experimental methods SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 2nd International Chernogolovka Workshop on Low Temperature Physics in Microgravity Environment (CWS 99) CY JUL 28-AUG 02, 1999 CL CHERNOGOLOVKA, RUSSIA SP Inst Solid State Physics RAS, RAS Council Cosm Sci, Sect Cosm Mat Sci ID THERMAL-BOUNDARY RESISTANCE; NONLINEAR HEAT-TRANSPORT; SUPERFLUID TRANSITION; T-LAMBDA; HE-4; CONDUCTIVITY; GRAVITY; HELIUM; POINT AB We report on the design of a new prototype flight instrument that will be used to repeat previous Earth-based measurements of nonlinear heat transport near the superfluid transition is the microgravity laboratory. Since this nonlinear conductivity is associated with dynamic limitations to the divergent correlation length, and since gravitational acceleration also limits the correlation length's divergence, we anticipate that the nonlinear conductivity will depend strongly on gravitational acceleration. The apparatus, data taking procedure, systematic corrections, and error sources are discussed here. C1 Univ New Mexico, Albuquerque, NM 87131 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Duncan, RV (reprint author), Univ New Mexico, Albuquerque, NM 87131 USA. NR 26 TC 2 Z9 2 U1 0 U2 0 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD MAY PY 2000 VL 119 IS 3-4 BP 265 EP 275 DI 10.1023/A:1004645231020 PG 11 WC Physics, Applied; Physics, Condensed Matter SC Physics GA 305ZF UT WOS:000086571100011 ER PT J AU Zhu, S Su, CH Lehoczky, SL George, MA Lowndes, DH AF Zhu, S Su, CH Lehoczky, SL George, MA Lowndes, DH TI Surface texture and structure of ZnO films synthesized by off-axis sputtering deposition SO JOURNAL OF MATERIALS RESEARCH LA English DT Article AB Morphology and structure of ZnO films deposited on (0001) sapphire and glass substrates by off-axis sputtering were investigated at various temperatures and pressures. All films show highly textured structures on glass substrates and epitaxial growth on sapphire substrates. The full width at half-maximum of theta rocking curves for epitaxial films is less than 0.5 degrees. In textured films, it rises to several degrees. The trend of surface textures in films grown at low pressures is similar to those grown at high temperatures. A morphology transition from large well-defined hexagonal grains to flat surface was observed at a pressure of 50 mtorr and temperature of 550 degrees C The experiment results are explained by the transport behavior of depositing species. C1 NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Micrograv Sci & Applicat Dept, Huntsville, AL 35812 USA. Univ Alabama, Dept Chem, Huntsville, AL 35899 USA. Oak Ridge Natl Lab, Div Solid State, Oak Ridge, TN 37831 USA. RP Zhu, S (reprint author), NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. NR 3 TC 11 Z9 11 U1 1 U2 1 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 2000 VL 15 IS 5 BP 1125 EP 1130 DI 10.1557/JMR.2000.0160 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA 311DR UT WOS:000086869900014 ER PT J AU Muller, HSP Farhoomand, J Cohen, EA Brupbacher-Gatehouse, B Schafer, M Bauder, A Winnewisser, G AF Muller, HSP Farhoomand, J Cohen, EA Brupbacher-Gatehouse, B Schafer, M Bauder, A Winnewisser, G TI The rotational spectrum of SO2 and the determination of the hyperfine constants and nuclear magnetic shielding tensors of (SO2)-S-33 and (SOO)-O-17 SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID SUBMILLIMETER-WAVE SPECTRUM; TERAHERTZ REGION; (OOO)-O-16-O-17-O-16; SPECTROSCOPY; (OOO)-O-17-O-16-O-16; O-17; LINE AB Precise frequencies for the 1(11)-2(02) transition of (SO2)-S-33 and (SOO)-O-17 in natural isotopic abundance have been obtained near 12 GHz by microwave Fourier transform spectroscopy in order to yield improved hyperfine constants. Nuclear spin-rotation coupling constants have been determined experimentally for (SO2)-S-32 for the first time. The spin-rotation constants have been used to derive nuclear magnetic shielding, parameters. These parameters are compared with values for the isoelectronic O-3 molecule. The transition mentioned above was also measured for (SO2)-S-32, (SO2)-S-34 (SOO)-O-18, and vibrationally excited (v(2) = 1) (SO2)-S-32. For (SO2)-S-33,, some transitions with large hyperfine splitting were also recorded in the millimeter-wave region. Continuing our investigations of the rotational spectra of SO2 in the submillimeter region, several transitions of (SOO)-O-17 have been recorded with the Cologne terahertz spectrometer between 540 and 840 GHz with J and K-a, up to 63 and 16, respectively. Transitions with high K-a, up to 28, have been recorded with the JPL laser sideband spectrometer between 1.8 and 3.2 THz. (C) 2000 Academic Press. C1 Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. ETH Zentrum, Phys Chem Lab, CH-8092 Zurich, Switzerland. RP Muller, HSP (reprint author), Univ Cologne, Inst Phys 1, Zulpicher Str 77, D-50937 Cologne, Germany. OI Mueller, Holger/0000-0002-0183-8927 NR 32 TC 25 Z9 25 U1 0 U2 4 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 2000 VL 201 IS 1 BP 1 EP 8 DI 10.1006/jmsp.2000.8072 PG 8 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 304EX UT WOS:000086471100001 ER PT J AU Fejard, L Champion, JP Jouvard, JM Brown, LR Pine, AS AF Fejard, L Champion, JP Jouvard, JM Brown, LR Pine, AS TI The intensities of methane in the 3-5 mu m region revisited SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article DE methane; high resolution; infrared; absolute intensities ID LINE PARAMETERS; TETRAHEDRAL MOLECULES; DIPOLE-MOMENT; NU-3 BAND; (CH4)-C-12; FREQUENCY; SPECTRUM; SYSTEM; LASER; CH4 AB The analysis of the linestrengths of the infrared spectrum of methane (12 and 13) in the 3-5 mu m region has been revisited on the basis of new measurements from Fourier transform spectra recorded at Kitt Peak under various optical densities. A simultaneous fit of these new data with previously reported tunable difference-frequency laser data has been done. An effective transition moment model in tensorial form up to the third order of approximation within the Pentad scheme has been used. The standard deviations achieved are very close to the experimental precision: 3 and 1.5%, respectively, for the two sets of data for the (CH4)-C-12 molecule, representing a substantial improvement with respect to earlier studies. The integrated bandstrengths obtained in the present work differ from previously reported values by factors ranging from -5 to +6%. The correction for the v(3), band, the strongest band of the Pentad system, is +2% with respect to the study of Hilico et al. [J. C. Hilico, J. P. Champion, S. Toumi, V. G, Tyuterev, and S. A. Tashkun, J. Mot Spectrosc. 168, 455-476 (1994)]. (C) 2000 Academic Press. C1 Univ Bourgogne, CNRS, Phys Lab, F-21078 Dijon, France. IUT, Lab Thermomecan, F-71200 Le Creusot, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Alpine technol, Germantown, MD 20874 USA. RP Fejard, L (reprint author), Univ Bourgogne, CNRS, Phys Lab, 9 Ave A Savary,BP 47870, F-21078 Dijon, France. RI Champion, Jean-Paul/C-3963-2009 NR 27 TC 25 Z9 25 U1 1 U2 9 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 2000 VL 201 IS 1 BP 83 EP 94 DI 10.1006/jmsp.2000.8065 PG 12 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 304EX UT WOS:000086471100009 ER PT J AU Stephen, TM Goldman, A Perrin, A Flaud, JM Keller, F Rinsland, CP AF Stephen, TM Goldman, A Perrin, A Flaud, JM Keller, F Rinsland, CP TI New high-resolution analysis of the 3 nu(3) and 2 nu(1)+nu(3) bands of nitrogen dioxide (NO2) by Fourier transform spectroscopy SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article DE IR spectroscopy; NO2; nonlocal thermodynamic equilibrium; NLTE ID NONLOCAL THERMODYNAMIC-EQUILIBRIUM; ELECTRON-SPIN ROTATION; LINE POSITIONS; CONTACT RESONANCES; (NO2)-N-14-O-16; INTENSITIES; PARAMETERS; STRATOSPHERE; SPECTRUM; DATABASE AB Using new high-resolution Fourier transform spectra recorded at the University of Denver in the 2-mu m region, a new and more extended analysis of the 2v(1), + v(3), and 3v(3), bands of nitrogen dioxide, located at 4179.9374 and 4754.2039 cm(-1) respectively, has been performed. The spin-rotation energy levels were satisfactorily reproduced using a theoretical model that takes into account both the Coriolis interactions between the spin-rotation energy levels of the (201) vibrational "bright" state with those of the (220) "dark" state. The interactions between the (003) bright state with the (022) dark stare were similarly treated. The spin-rotation resonances within each of the NO, vibrational states were also taken into account. The precise vibrational energies and the rotational, spin-rotational, and coupling constants were obtained for the two dyads [(220), (201)] and ((022), (003)) of the (NO2)-N-14-O-16 interacting states. From the experimental line intensities of the 2v(1) + v(3) and 3v(3) bands, a determination of their vibrational transition moment constants was performed. A comprehensive list of line positions and line intensities of the (2v(1) + 2v(2), 2v(1) + v(3)) and the (2v(2) + 2v(3), 3v(3)) interacting bands of (NO2)-N-14-O-16 was generated. In addition, assuming the harmonic approximation and using the Hamiltonian constants derived in this work and in previous studies (A. Perrin, J.-M. Flaud, A. Goldman, C, Camy-Peyret, W. J. Lafferty, Ph. Areas, and C. P. Rinsland, J, Quant. Spectrosc. Radiat. Transfer 60, 839- 850 (1998)), we have generated synthetic spectra for the ((022), (003))-((040), (021), (002)) hot bands at 6.3 mu m and for the ((220), (201))-((100), (020), (001)) hot bands at 3.5 mu m, which are in good agreement with the observed spectra. (C) 2000 Academic Press. C1 Univ Denver, Dept Phys, Denver, CO 80208 USA. Univ Paris 11, CNRS, Photophys Mol Lab, F-91405 Orsay, France. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23682 USA. RP Stephen, TM (reprint author), Univ Denver, Dept Phys, Denver, CO 80208 USA. NR 34 TC 11 Z9 14 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 2000 VL 201 IS 1 BP 134 EP 142 DI 10.1006/jmsp.2000.8064 PG 9 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 304EX UT WOS:000086471100015 ER PT J AU Gaede, R Li, FL Hyde, D Shen, DS AF Gaede, R Li, FL Hyde, D Shen, DS TI Amorphous silicon photodetector for optical interconnections SO JOURNAL OF NON-CRYSTALLINE SOLIDS LA English DT Article; Proceedings Paper CT 18th International Conference on Amorphous and Microcrystalline Semiconductors (ICAMS 18) CY AUG 23-27, 1999 CL SNOWBIRD, UTAH SP Energy Convers Devices, Japan Steelworks Ltd, MVSystems Inc, Natl Renewable Energy Lab, Princeton Univ, Sanyo Elect Corp, Sony Corp, Syracuse Univ, United Solar Syst Corp, Univ Utah, Xerox Corp ID SENSE-AMPLIFIER; DEVICES AB This paper discusses the feasibility of using hydrogenated amorphous silicon photodetectors in optical interconnections. Our analysis of the transient carrier transport in amorphous silicon pointed out that individual detectors could operate in the 100 MHz-1. GHz range. The parallelism afforded by fabricating large arrays of receivers can provide communication bandwidth in excess of electronic interconnects. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Alabama, Dept Elect & Comp Engn, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Gaede, R (reprint author), Univ Alabama, Dept Elect & Comp Engn, Huntsville, AL 35899 USA. NR 15 TC 1 Z9 1 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-3093 J9 J NON-CRYST SOLIDS JI J. Non-Cryst. Solids PD MAY PY 2000 VL 266 BP 1208 EP 1212 DI 10.1016/S0022-3093(00)00043-0 PN B PG 5 WC Materials Science, Ceramics; Materials Science, Multidisciplinary SC Materials Science GA 315TW UT WOS:000087129900109 ER PT J AU Howden, SD AF Howden, SD TI The three-dimensional secondary circulation in developing Gulf Stream meanders SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID INVERTED ECHO SOUNDERS; DEEP-OCEAN BENEATH; BAROCLINIC DISTURBANCES; VERTICAL MOTION; 68-DEGREES-W; EXCHANGE; FLOW; RECIRCULATION; 73-DEGREES-W; CYCLOGENESIS AB From June 1988 until August 1990 an array of 12 inverted echo sounders (IES), 12 additional IES with pressure gauges to measure the abyssal pressure signal, and 12 tall current meter moorings instrumented at depths 400 m, 700 m, 1000 m, and 3500 m was deployed in the Gulf Stream near 68 degrees W. The current meter array spanned an area of approximately 260 km by 200 km with nominal horizontal instrument spacing of 56 km in the cross-stream direction and 65 km in the downstream direction. Six events were observed during the two year deployment during which a steep Gulf Stream meander trough and an abyssal cyclone developed concurrently. Two of the meander troughs eventually pinched off to form cold core rings. As the abyssal flows spun up they became nearly barotropic with strong [O(30 cm s(-1))] swirl speeds that advected the main thermocline and helped steepen the meanders. Although the geostrophic barotropic flow played a large role in the development of the system, ageostrophic flow was also required. In this study the three-dimensional mesoscale ageostrophic flow within the main thermocline is diagnosed during two steep meander trough events and one steep meander crest event. It is shown that in addition to the alongstream horizontal ageostrophic flow associated with the curvature of the main jet (cyclostrophic speeds greater than 25 cm s(-1) are not unusual on trough axes) there is significant horizontal cross-stream ageostrophic flow. Cross-stream ageostrophic flow as high as 18 cm s(-1) is diagnosed. Vertical momentum advection is also shown to be an important contributor to cross-stream ageostrophic how, with values as high as 7 cm s(-1) diagnosed. The patterns of the ageostrophic flow are shown to be tied to the phasing between the upper-level meander and the abyssal vortex. Both rotational and divergent patterns in the ageostrophic flow are evident. For parcels on main thermocline isopycnals, the ageostrophic flow provides an asymmetric cross-frontal flow relative to the symmetric cross-frontal flow associated with the barotropic vortices. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Greenbelt, MD USA. RP Howden, SD (reprint author), NASA, Goddard Space Flight Ctr, Mailcode 971, Greenbelt, MD 20771 USA. NR 48 TC 10 Z9 10 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD MAY PY 2000 VL 30 IS 5 BP 888 EP 915 DI 10.1175/1520-0485(2000)030<0888:TTDSCI>2.0.CO;2 PG 28 WC Oceanography SC Oceanography GA 316DT UT WOS:000087152900008 ER PT J AU Gundy-Burlet, KL Dorney, DJ AF Gundy-Burlet, KL Dorney, DJ TI Effects of radial location on the migration of hot streaks in a turbine SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID ROTOR-STATOR INTERACTION; STOKES; REDISTRIBUTION; SIMULATIONS; STAGE AB Experimental data have shown that combustor temperature nonuniformities can lead to the excessive heating of first-stage rotor blades in turbines. This heating of the rotor blades can lead to thermal fatigue and degrade turbine performance. The results of recent studies have shown that variations in the circumferential location, or clocking, of the first-stage stator airfoils can be used to control the adverse effects of the hot streaks by mixing hot streak fluid with the cooler fluid contained in the first-stage stator wake. Less emphasis has been placed on determining the optimal radial location of the hot streaks at the inlet to the first-stage stator blade row. In the present investigation, three-dimensional unsteady Navier-Stokes simulations have been performed for a If-stage high-pressure turbine geometry operating in subsonic how Combustor hot streaks were included in the simulations. The radial location and the clocking position of the hot streak were varied across the inlet relative to the first-stage stator. C1 NASA, Ames Res Ctr, Computat Phys & Simulat Branch, Moffett Field, CA 94035 USA. Virginia Commonwealth Univ, Dept Mech Engn, Richmond, VA 23284 USA. RP Gundy-Burlet, KL (reprint author), NASA, Ames Res Ctr, Computat Phys & Simulat Branch, Moffett Field, CA 94035 USA. NR 18 TC 8 Z9 8 U1 0 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 2000 VL 16 IS 3 BP 377 EP 387 DI 10.2514/2.5589 PG 11 WC Engineering, Aerospace SC Engineering GA 315MB UT WOS:000087116600001 ER PT J AU Castiglone, LA Northam, GB Baker, NR Roe, LA AF Castiglone, LA Northam, GB Baker, NR Roe, LA TI Wall drag in internal Mach-2 flow with cavity and transpiration injection SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/ASME/SAE/ASEE 33rd Joint Propulsion Conference CY JUL 06-09, 1997 CL SEATTLE, WASHINGTON SP Amer Inst Aeronaut & Astronaut, ASME, SAE, ASEE AB A drag-measurement facility was used to evaluate potential scramjet fuel-injection/wall-cooling configurations. Mach-2 airflow containing a train of weak, unsteady, reflecting shocks was supplied to test plates equipped with force and static-pressure instrumentation, ii nonporous flat plate, a partially porous Rat plate, and a wall cavity plate (the latter two with mass injection) were tested. The nonporous plate results were within 10% of both theoretical and numerical predictions. The porous plate exhibited reduced drag (relative to the nonporous flat plate), even without mass addition, caused by pressure equalization across the impinging shocks. Addition of mass decreased the drag 46% relative to the flat-plate value. The rectangular wall cavity had a geometric aspect ratio (length in fl ow direction to depth) of 5.0. The cavity plate produced the highest drag of the cases tested. without secondary injection cavity-plate drag exceeded the instrumentation range, but was estimated as higher than the Rat plate by approximately one order of magnitude. A minimum amount of secondary Row injected into the cavity reduced the drag to a value 50% higher than the Rat plate. Further cavity mass addition increased the drag. The porous Bat plate! provided drag reduction, whereas the cavity configuration demonstrated drag penalties when compared to the flat plate. C1 Univ Washington, Seattle, WA 98195 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. Univ Arkansas, Fayetteville, AR 72701 USA. RP Castiglone, LA (reprint author), Univ Washington, Seattle, WA 98195 USA. NR 21 TC 4 Z9 5 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 2000 VL 16 IS 3 BP 472 EP 477 DI 10.2514/2.5592 PG 6 WC Engineering, Aerospace SC Engineering GA 315MB UT WOS:000087116600012 ER PT J AU Tajmar, M Wang, J AF Tajmar, M Wang, J TI Three-dimensional numerical simulation of field-emission-electric-propulsion neutralization SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB A three-dimensional full-particle-simulation model is developed for simulation of a field-emission-electric-propulsion (FEEP) thruster operation in an ambient plasma. Simulations are performed with ion-to-electron mass ratios close to actual values (m(i)/m(e), = 80,000 to resolve the basic characteristics of the propellant ions emitted from a FEEP thruster and their neutralization in an ambient plasma environment or by a thermionic neutralizer. The slit geometry allows a FEEP emitter to transmit reasonable values of emission current, even when no neutralization mechanism is present. However, to neutralize the FEEP beam, one must either ope rate the FEEP in an ambient plasma with a density comparable with the density of the FEEP beam ions and/or plate a neutralizer at a location sufficiently far from the FEEP emitter. Because the electric field from the exposed high-voltage accelerator dominates the neighboring region of FEEP thrusters, a neutralizer placed on the spacecraft surface beside the FEEP Emitter will not provide effective neutralization. C1 Vienna Univ Technol, Inst Allgemeine Elektron & Quantenelekron, A-1040 Vienna, Austria. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Tajmar, M (reprint author), Vienna Univ Technol, Inst Allgemeine Elektron & Quantenelekron, Gusshausstr 27-29, A-1040 Vienna, Austria. OI Tajmar, Martin/0000-0002-7406-7588 NR 9 TC 12 Z9 12 U1 1 U2 5 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 2000 VL 16 IS 3 BP 536 EP 544 DI 10.2514/2.5602 PG 9 WC Engineering, Aerospace SC Engineering GA 315MB UT WOS:000087116600021 ER PT J AU Fouke, BW Farmer, JD Des Marais, DJ Pratt, L Sturchio, NC Burns, PC Discipulo, MK AF Fouke, BW Farmer, JD Des Marais, DJ Pratt, L Sturchio, NC Burns, PC Discipulo, MK TI Depositional facies and aqueous-solid geochemistry of travertine-depositing hot springs (Angel Terrace, Mammoth Hot Springs, Yellowstone National Park, USA) SO JOURNAL OF SEDIMENTARY RESEARCH LA English DT Review ID CARBON-ISOTOPE FRACTIONATION; PYRAMID LAKE SUBBASIN; CALCITE PRECIPITATION; DEVILS-HOLE; NEW-ZEALAND; SEDIMENTARY CARBONATES; BIOLOGICAL CARBONATES; OXYGEN ISOTOPES; URANIUM-SERIES; NORTH-ISLAND AB Petrographic and geochemical analyses of travertine depositing hot springs at Angel Terrace, Mammoth Hot Springs, Yellowstone National Park, have been used to define five depositional facies along the spring drainage system. Spring waters are expelled in the vent facies at 71 to 73 degrees C and precipitate mounded travertine composed of aragonite needle botryoids. The apron and channel facies (43-72 degrees C) is floored by hollow tubes composed of aragonite needle botryoids that encrust sulfide-oxidizing Aquificales bacteria. The travertine of the pond facies (30-62 degrees C) varies in composition from aragonite needle shrubs formed at higher temperatures to ridged networks of calcite and aragonite at lower temperatures. Calcite "ice sheets", calcified bubbles, and aggregates of aragonite needles ("fuzzy dumbbells") precipitate at the air-water interface and settle to pond floors. The proximal-slope facies (28-54 degrees C), which forms. the margins of terracette pools, is composed of arcuate aragonite needle shrubs that create small microterracettes on the steep slope face. Finally, the distal-slope facies (28-30 degrees C) is composed of calcite spherules and calcite "feather" crystals. Despite the presence of abundant microbial mat communities and their observed role in providing substrates for mineralization, the com positions of spring-water and travertine predominantly reflect abiotic physical and chemical processes, Vigorous CO2 degassing causes a +2 unit increase in spring water pH, as well as Rayleigh type covariations between the concentration of dissolved inorganic carbon and corresponding delta(13)C. Travertine delta(13)C and delta(18)O are nearly equivalent to aragonite and calcite equilibrium values calculated from spring water in the higher-temperature (similar to 50-73 degrees C) depositional facies. Conversely, travertine precipitating in the lower-temperature (< similar to 50 degrees C) depositional facies exhibits delta(13)C and delta(18)O values that are as much as 4%0 less than predicted equilibrium values, This isotopic shift may record microbial respiration as well as downstream transport of travertine crystals, Despite the production of H2S anti the abundance of sulfide-oxidizing microbes, preliminary delta(34)S data do not uniquely define the microbial metabolic pathways present in the spring system. This suggests that the high extent of CO2 degassing and large open-system solute reservoir in these thermal systems overwhelm biological controls on travertine crystal chemistry. C1 Univ Illinois, Dept Geol, Urbana, IL 61801 USA. NASA, Ames Res Ctr, Exobiol Branch, Moffett Field, CA 94035 USA. Indiana Univ, Dept Geol Sci, Biogeochem Labs, Bloomington, IN 47405 USA. Argonne Natl Lab, Div Environm Res, Argonne, IL 60439 USA. Univ Notre Dame, Dept Civil Engn & Geol Sci, Notre Dame, IN 46556 USA. RP Fouke, BW (reprint author), Univ Illinois, Dept Geol, 245 Nat Hist Bldg,1301 W Green St, Urbana, IL 61801 USA. RI Burns, Peter/J-3359-2013; OI Burns, Peter/0000-0002-2319-9628 NR 129 TC 150 Z9 152 U1 6 U2 43 PU SEPM-SOC SEDIMENTARY GEOLOGY PI TULSA PA 1731 E 71ST STREET, TULSA, OK 74136-5108 USA SN 1073-130X J9 J SEDIMENT RES JI J. Sediment. Res. PD MAY PY 2000 VL 70 IS 3 BP 565 EP 585 DI 10.1306/2DC40929-0E47-11D7-8643000102C1865D PN A PG 21 WC Geology SC Geology GA 319EQ UT WOS:000087328900015 PM 11543518 ER PT J AU Whitmore, SA Moes, TR AF Whitmore, SA Moes, TR TI Base-drag-reduction experiments on the X-33 Linear Aerospike SR-71 flight program SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Drag-reduction tests were conducted on the Linear Aerospike SR-71 experiment. The Linear Aerospike SR-71 experiment flight tested a 20% scale model of an X-33 forebody with a linear-aerospike engine mounted at the rear of the body. The entire apparatus was mounted on top of an SR-71 aircraft. This paper suggests a method for reducing base drag by adding surface roughness along the forebody. Calculations show a potential for base-drag reductions of 8-14%. Flight results corroborate the base drag reduction, with actual reductions of 15% in the high-subsonic flight regime. An unexpected result is that drag benefits persist well into the supersonic flight regime. Flight results show no overall net drag reduction. The applied roughness caused forebody pressures to rise and offset base-drag reductions. Apparently, the grit displaced streamlines outward, causing forebody flow compression. Clearly the drag optimization must be modified to include not only the base pressure drag and viscous forebody drag coefficients but must also include the forebody pressure distribution. Because of the mixed experimental results-there was no overall net drag reduction, the existence of an optimal forebody surface roughness must still be proven. Clearly, however, the forebody grit method has been proven as a viable drag-reduction tool. C1 NASA, Dryden Flight Res Ctr, Aerodynam Branch, Edwards, CA 93532 USA. RP Whitmore, SA (reprint author), NASA, Dryden Flight Res Ctr, Aerodynam Branch, POB 273,Mail Stop D-2228, Edwards, CA 93532 USA. NR 11 TC 1 Z9 1 U1 2 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 2000 VL 37 IS 3 BP 297 EP 303 DI 10.2514/2.3569 PG 7 WC Engineering, Aerospace SC Engineering GA 322YC UT WOS:000087536100001 ER PT J AU Curry, DM Pham, VT Norman, I Chao, DC AF Curry, DM Pham, VT Norman, I Chao, DC TI Oxidation of hypervelocity impacted reinforced carbon-carbon SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT AIAA 33rd Thermophysics Conference CY JUN 28-JUL 01, 1999 CL NORFOLK, VIRGINIA SP Amer Inst Aeronaut & Astronaut AB Results from arcjet tests conducted at the NASA Johnson Space Center on reinforced carbon-carbon samples subjected to hypervelocity impact are presented. The test specimens are representative of reinforced carbon-carbon component used on the Space Shuttle Orbiter. The arcjet testing established the oxidation characteristics of reinforced carbon-carbon when hypervelocity projectiles, simulating meteoroid/orbital debris, impact the reinforced carbon-carbon material. In addition, analytical modeling of the increased material oxidation in the impacted area, using measured hole growth data, to develop correlations for use in trajectory simulations is discussed. Entry flight simulations are useful in assessing the increased Space Shuttle reinforced carbon-carbon component degradation as a result of impact damage and the hot gas flow through an enlarging hole into the wing leading-edge cavity. C1 NASA, Lyndon B Johnson Space Ctr, Struct & Mech Div, Houston, TX 77058 USA. Boeing Co, Reusable Space Syst Div, Houston, TX 77058 USA. RP Curry, DM (reprint author), NASA, Lyndon B Johnson Space Ctr, Struct & Mech Div, Houston, TX 77058 USA. NR 5 TC 5 Z9 5 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 2000 VL 37 IS 3 BP 310 EP 317 DI 10.2514/2.3580 PG 8 WC Engineering, Aerospace SC Engineering GA 322YC UT WOS:000087536100003 ER PT J AU Hause, T Johnson, TE Librescu, L AF Hause, T Johnson, TE Librescu, L TI Effect of face-sheet anisotropy on buckling and postbuckling of sandwich plates SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID CURVED PANELS; FLAT AB A study of the effect of anisotropy of face sheets on buckling and postbuckling of sandwich flat panels subjected to both mechanical and thermal loads is presented. The mechanical loads consist of uniaxial compressive/tensile edge loads, while the temperature is assumed to exhibit an antisymmetric variation through the panel thickness. The study is carried out in the context of a geometrically nonlinear theory of sandwich structures that also incorporates the effect of unavoidable stress-free initial geometric imperfections. A detailed analysis of the influence of a large number of parameters associated with the panel geometry, material properties of the core, fiber orientation and stacking sequence in the face sheet, and character of tangential boundary conditions (i.e., movable or immovable) on buckling strength and postbuckling response is accomplished, and pertinent conclusions are outlined. C1 Virginia Polytech Inst & State Univ, Dept Engn Sci & Mech, Blacksburg, VA 24061 USA. NASA, Langley Res Ctr, Thermal Struct Branch, Hampton, VA 23081 USA. RP Hause, T (reprint author), Virginia Polytech Inst & State Univ, Dept Engn Sci & Mech, Blacksburg, VA 24061 USA. NR 16 TC 10 Z9 10 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 2000 VL 37 IS 3 BP 331 EP 341 DI 10.2514/2.3583 PG 11 WC Engineering, Aerospace SC Engineering GA 322YC UT WOS:000087536100006 ER PT J AU Townsend, JS Peck, J Ayala, S AF Townsend, JS Peck, J Ayala, S TI Probabilistic structural analysis of solid rocket booster aft skirt external fitting modification SO JOURNAL OF SPACECRAFT AND ROCKETS 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 AB NASA has funded several major programs (the Probabilistic Structural Analysis Methods Project is an example) to develop probabilistic structural analysis methods and tools for engineers to apply in the design and assessment of aerospace hardware. A probabilistic finite element software code, known as NESSUS, is used to determine the reliability of a critical weld of the Space Shuttle solid rocket booster aft skirt. An external bracket modification to the aft skirt provides a comparison basis for examining the details of the probabilistic analysis and its contributions to the design process. Also, analysis findings are compared with measured Space Shuttle flight data. C1 NASA, George C Marshall Space Flight Ctr, Struct Mech & Thermal Dept, Engn Directorate, Huntsville, AL 35812 USA. Sverdrup Technol Inc, Struct & Dynam Grp, Huntsville, AL 35806 USA. RP Townsend, JS (reprint author), NASA, George C Marshall Space Flight Ctr, Struct Mech & Thermal Dept, Engn Directorate, ED21, Huntsville, AL 35812 USA. NR 8 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 2000 VL 37 IS 3 BP 350 EP 358 DI 10.2514/2.3585 PG 9 WC Engineering, Aerospace SC Engineering GA 322YC UT WOS:000087536100008 ER PT J AU Luthcke, SB Rowlands, DD McCarthy, JJ Pavlis, DE Stoneking, E AF Luthcke, SB Rowlands, DD McCarthy, JJ Pavlis, DE Stoneking, E TI Spaceborne laser-altimeter-pointing bias calibration from range residual analysis SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID TOPEX/POSEIDON AB For many science applications of laser altimetry, the precise location of the point on the Earth's surface from which the laser energy reflects is required. The geolocation accuracy of this illuminated laser bounce point is primarily dependent on the accuracy of the laser-pointing knowledge. Laser and spacecraft body systematic misalignments are significant contributors to the pointing knowledge error. We present a method fur accounting for these systematic misalignments through a Bayesian least-squares-estimation process using laser-altimeter range residuals. This range-residual calibration method uses commanded spacecraft attitude maneuvers and ocean range residuals for the recovery of the pointing and range biases. The performance of this method is evaluated through both consider-covariance and simulation studies applied to the upcoming Vegetation Canopy Lidar and the Ice and Cloud Elevation Satellite missions. The results of these analyses suggest are-second level pointing bias knowledge can be achieved. A calibration maneuver is developed for both the Vegetation Canopy Lidar and the Ice and Cloud Elevation Satellite mission. The laser altimeter-range measurement model algorithm is presented. C1 NASA, Raytheon ITSS, Space Geodesy Branch, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Raytheon ITSS, Geodynam, Greenbelt, MD 20770 USA. Orbital Sci Corp, Beltsville, MD 20705 USA. RP Luthcke, SB (reprint author), NASA, Raytheon ITSS, Space Geodesy Branch, Goddard Space Flight Ctr, Code 926, Greenbelt, MD 20771 USA. RI Rowlands, David/D-2751-2012; Luthcke, Scott/D-6283-2012 NR 18 TC 22 Z9 25 U1 3 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 2000 VL 37 IS 3 BP 374 EP 384 DI 10.2514/2.3571 PG 11 WC Engineering, Aerospace SC Engineering GA 322YC UT WOS:000087536100011 ER PT J AU Ganapathi, GB Engelbrecht, CS AF Ganapathi, GB Engelbrecht, CS TI Performance of the xenon feed system on Deep Space One SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Propulsion for the Deep Space One (DS1) spacecraft is provided by a xenon ion engine. Xenon is stored in a supercritical state and is delivered as a low-pressure gas to the thruster and two cathodes (called the main cathode and neutralizer) by a xenon feed system (XFS). This mission requires tight constraints on thruster performance, which in turn requires separate and very accurate throttling of the thruster and cathode flows; the DS1 spacecraft is the first of its type to utilize a xenon ion engine that can be throttled. Flow is regulated separately to the thruster and cathodes to an accuracy of +/-3% using three calibrated flow control devices that are each fed by a dedicated plenum tank. Bang-bang regulators are used to control the set pressures in the plena. The resulting XFS control algorithms are quite complex. The XFS is controlled by a digital control interface unit and the control algorithm for achieving steady-state xenon flow is presented. The worst-case error in flow is shown to be less than +/-3%, accounting for random and systematic errors. At the time of writing, the individual components are in excellent health and the performance of the XFS is as expected. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. PRIMEX Aerosp Corp, Redmond, WA 98073 USA. RP Ganapathi, GB (reprint author), CALTECH, Jet Prop Lab, M-S 125-109,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 8 TC 13 Z9 14 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 2000 VL 37 IS 3 BP 392 EP 398 DI 10.2514/2.3573 PG 7 WC Engineering, Aerospace SC Engineering GA 322YC UT WOS:000087536100013 ER PT J AU Boltz, FW AF Boltz, FW TI Avionics module recovery system for expendable launch vehicles SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article C1 NASA, Ames Res Ctr, Aeronaut Div, Moffett Field, CA 94035 USA. NR 6 TC 1 Z9 1 U1 1 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 2000 VL 37 IS 3 BP 421 EP 424 DI 10.2514/2.3578 PG 4 WC Engineering, Aerospace SC Engineering GA 322YC UT WOS:000087536100018 ER PT J AU Caldwell, DW Rennels, DA AF Caldwell, DW Rennels, DA TI A minimalist fault-tolerant microcontroller design for embedded spacecraft computing SO JOURNAL OF SUPERCOMPUTING LA English DT Article DE microcontroller; fault-tolerance; embedded computing; real-time computing; fault-insertion testing; space radiation; single-event effects (SEE) AB Inexpensive commodity microcontrollers are extremely attractive for offloading low-level, real-time computations from high-performance spacecraft computers due to their high functional density and low power, but they have not been widely used because of their low radiation tolerance. This paper presents a fault-tolerant microcontroller configuration specifically designed to tolerate space-radiation effects that be used for embedded real-time control in spacecraft. The requirements and fault-environment are examined, then an architecture is presented. An experimental testbed is described along with fault-insertion test results. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Dept Comp Sci, Los Angeles, CA 90024 USA. RP Caldwell, DW (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 2 Z9 2 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0920-8542 J9 J SUPERCOMPUT JI J. Supercomput. PD MAY PY 2000 VL 16 IS 1 BP 7 EP 25 DI 10.1023/A:1008142728784 PG 19 WC Computer Science, Hardware & Architecture; Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 298HE UT WOS:000086132600002 ER PT J AU Somani, AK Sansano, AM AF Somani, AK Sansano, AM TI Achieving robustness and minimizing overhead in parallel algorithms through overlapped communication/computation SO JOURNAL OF SUPERCOMPUTING LA English DT Article DE Proteus Parallel Computer System; communication overhead; overlapping computing and communication; partitioning and scheduling for high-performance; fault tolerance; complete exchange ID ARCHITECTURES; HYPERCUBES AB One of the major goals in the design of parallel processing machines and algorithms is to achieve robustness and reduce the effects of the overhead introduced when a given problem is parallelized or a fault occurs. A key contributor to overhead is communication time, in particular when a node is faulty and another node is substuiting for its operation. Many architectures try to reduce this overhead by minimizing the actual time for a communication to occur, including latency and bandwidth figures. Another approach is to hide communication by overlapping it with computation assuming that the computation is the most prominent factor. This paper presents the mechanisms provided in the Proteus parallel computer and its effective use of communication hiding through overlapping communication/computation techniques with and without the presence of a fault. These techniques are easily extended for use in compiler support of parallel programming. We also address the complexity (or rather simplicity) in achieving complete exchange on the Proteus Machine. C1 Iowa State Univ, Ames, IA 50011 USA. C Cube Microsyst, Milpitas, CA 95035 USA. NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. RP Somani, AK (reprint author), Iowa State Univ, Ames, IA 50011 USA. RI Somani, Arun /C-5961-2017 OI Somani, Arun /0000-0002-6248-4376 NR 22 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0920-8542 J9 J SUPERCOMPUT JI J. Supercomput. PD MAY PY 2000 VL 16 IS 1 BP 27 EP 52 DI 10.1023/A:1008129412855 PG 26 WC Computer Science, Hardware & Architecture; Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 298HE UT WOS:000086132600003 ER PT J AU Barta, DJ Tibbitts, TW AF Barta, DJ Tibbitts, TW TI Calcium localization and tipburn development in lettuce leaves during early enlargement SO JOURNAL OF THE AMERICAN SOCIETY FOR HORTICULTURAL SCIENCE LA English DT Article DE Lactuca sativa; physiological disorder; deficiency; magnesium; potassium; electron microprobe; x-ray analysis ID NUTRIENT SOLUTION CONCENTRATION; HIGH RELATIVE-HUMIDITY; CHINESE-CABBAGE; LEAF TIPBURN; PLANTS; ASSIMILATION; TRANSPORT; NITRATE; GROWTH; FRUIT AB Tissue concentrations of Ca, Mg, and K were determined across immature leaves of lettuce (Lactuca sativa L. 'Buttercrunch') at different stages of enlargement using electron microprobe x-ray analysis. The analysis was with a wavelength dispersive spectrometer to permit detection of low concentrations of Ca. Patterns of mineral accumulation in immature leaves that were exposed were compared to patterns of accumulation in leaves that were enclosed within a dec-eloping head. The leaves developing without enclosure were free to transpire and developed normally whereas leaves developing with enclosure were restricted in transpiration and developed an injury that was characteristic of Ca deficiency. In the exposed leaves, Ca concentrations increased from an average of 1.0 to 2.1 mg.g(-1) dry weight (DW) as the leaves enlarged from 5 to 30 mm in length. In the enclosed leaves, Ca concentrations decreased from 1.0 to 0.7 mg.g(-1) DW as the leaves enlarged from 5 to 30 mm in length. At the tips of these enclosed leaves a larger decrease was found, from 0.9 to 0.3 mg.g(-1) DW during enlargement. Necrotic injury first became apparent in this tip area when the concentration was approximate to 0.4 mg.g(-1) DW. Magnesium concentrations across the exposed leaves were similar to concentrations across the enclosed leaves, and did not change with enlargement. Magnesium concentrations averaged 3.5. mg.g(-1) DW in both enclosed and exposed leaves during enlargement from 5 to 30 mm, In both exposed and enclosed leaves, IC concentrations increased during enlargement from 40 to approximate to 60 mg.g(-1) DW. Potassium concentrations were highest toward the leaf apex and upper margin where injury symptoms occurred, and this may have enhanced injury development. This research documents the critical low levels of Ca (0.2 to 0.4 mg.g(-1) DW) that can occur in enclosed leaves of plants and which apparently leads to the marginal apex necrosis of developing Leaves seen frequently on lettuce and other crops. C1 Univ Wisconsin, Dept Hort, Madison, WI 53706 USA. RP Barta, DJ (reprint author), NASA, Lyndon B Johnson Space Ctr, Mailcode EC3, Houston, TX 77058 USA. NR 36 TC 27 Z9 33 U1 1 U2 24 PU AMER SOC HORTICULTURAL SCIENCE PI ALEXANDRIA PA 701 NORTH SAINT ASAPH STREET, ALEXANDRIA, VA 22314-1998 USA SN 0003-1062 J9 J AM SOC HORTIC SCI JI J. Am. Soc. Hortic. Sci. PD MAY PY 2000 VL 125 IS 3 BP 294 EP 298 PG 5 WC Horticulture SC Agriculture GA 333UV UT WOS:000088149900004 PM 11543566 ER PT J AU Eckert, MP Carter, GA AF Eckert, MP Carter, GA TI Flowers produce variations in color saturation by arranging petals at oblique and varying angles SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID INSECT POLLINATORS; ECOLOGY; VISION AB Large color variations can be observed across the face of a flower even when individual petals are the same color. We investigated whether these color variations could be explained by a model that incorporates multiple reflections of light between petals and transmissions of light through petals before the light returns to the observer. The three flowers that we selected for the study exhibited large color variations across the face of the intact flower but had no significant observable difference in color saturation across a single petal or between petals when petals were removed from the flower. We used a spectroradiometer to measure the spectrum across the faces of intact flowers and across individual petals. The measured spectra for all of the flowers were consistent with the proposed model. (C) 2000 Optical Society of America [S0740-3232(00)00105-8]. C1 Univ Technol Sydney, Fac Engn, Sydney, NSW 2007, Australia. NASA, Earth Syst Sci Off, Stennis Space Ctr, MS 39529 USA. RP Eckert, MP (reprint author), Univ Technol Sydney, Fac Engn, POB 123, Sydney, NSW 2007, Australia. NR 7 TC 3 Z9 3 U1 3 U2 4 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0740-3232 J9 J OPT SOC AM A JI J. Opt. Soc. Am. A-Opt. Image Sci. Vis. PD MAY PY 2000 VL 17 IS 5 BP 825 EP 830 DI 10.1364/JOSAA.17.000825 PG 6 WC Optics SC Optics GA 309JJ UT WOS:000086764500001 PM 10795629 ER PT J AU Mishchenko, M Luck, JM Nieuwenhuizen, TM AF Mishchenko, M Luck, JM Nieuwenhuizen, TM TI Full angular profile of the coherent polarization opposition effect SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID DISCRETE RANDOM-MEDIA; MULTIPLE-SCATTERING; ENHANCED BACKSCATTERING; LIGHT; WAVES AB We use the rigorous vector theory of weak photon localization for a semi-infinite medium composed of nonabsorbing Rayleigh scatterers to compute the full angular profile of the polarization opposition effect. The effect is caused by coherent backscattering of unpolarized incident light and accompanies the well-known backscattering intensity peak. (C) 2000 Optical Society of America [S0740-3232(00)00905-4]. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. CEA Saclay, Serv Phys Theor, F-91191 Gif Sur Yvette, France. Univ Amsterdam, Zeeman Lab, NL-1018 XE Amsterdam, Netherlands. RP Mishchenko, M (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. RI Nieuwenhuizen, Theodorus Maria/G-8953-2012; Mishchenko, Michael/D-4426-2012 OI Nieuwenhuizen, Theodorus Maria/0000-0002-2942-7986; NR 17 TC 72 Z9 74 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0740-3232 J9 J OPT SOC AM A JI J. Opt. Soc. Am. A-Opt. Image Sci. Vis. PD MAY PY 2000 VL 17 IS 5 BP 888 EP 891 DI 10.1364/JOSAA.17.000888 PG 4 WC Optics SC Optics GA 309JJ UT WOS:000086764500009 ER PT J AU Balla, RJ Exton, RJ AF Balla, RJ Exton, RJ TI Density measurement in air by optically exciting the Cordes bands of I-2 SO MEASUREMENT SCIENCE AND TECHNOLOGY LA English DT Article DE optical instrumentation; laser-induced fluorescence of iodine; wake-density measurements ID ARF EXCIMER-LASER; MOLECULAR-IODINE; FLUORESCENCE; STATE; I2; SPECTRUM; CONSTANTS; ARGON; FLOWS AB We describe an optical method based on laser-induced fluorescence for obtaining instantaneous measurements of density along a line in low-density air seeded with I-2 The Cordes bands of I-2 (D (1)Sigma(u)(+) <-- X (1)Sigma(g)(+)) are excited with a turntable ArF excimer laser. Air densities in the range (0.1-6.5) x 10(17) cm(-3) are measured over 295-583 K using the density-dependent emission ratio of two emission bands of I-2; the 340 nm bands and the diffuse-structured McLennan bands near 320 nm. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP NASA, Langley Res Ctr, MS 493, Hampton, VA 23681 USA. EM r.j.balla@larc.nasa.gov NR 29 TC 3 Z9 3 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 MAY PY 2000 VL 11 IS 5 BP 459 EP 466 DI 10.1088/0957-0233/11/5/303 PG 8 WC Engineering, Multidisciplinary; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 317DW UT WOS:000087211900003 ER PT J AU Golden, DC Ming, DW Schwandt, CS Morris, RV Yang, SV Lofgren, GE AF Golden, DC Ming, DW Schwandt, CS Morris, RV Yang, SV Lofgren, GE TI An experimental study on kinetically-driven precipitation of calcium-magnesium-iron carbonates from solution: Implications for the low-temperature formation of carbonates in martian meteorite Allan Hills 84001 SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID PETROLOGIC EVIDENCE; SEA-ICE; ALH84001; ORIGIN; LIFE; MARS AB Spherical carbonate globules of similar composition, size, and radial Ca-, Mg-, and Fe-zonation to those in martian meteorite Allan Hills (ALH) 84001 were precipitated from Mg-rich, supersaturated solutions of Ca-Mg-Fe-CO(2)-H(2)O at 150 OC. The supersaturated solutions (pH congruent to 6-7) were prepared at room temperature and contained in Teflon(TM)-lined stainless steel vessels, which were sealed and heated to 150 degrees C for 24 h. Experiments were also conducted at 25 degrees C and no globules comparable to those of ALH 84001 were precipitated. Instead, amorphous Fe-rich carbonates were formed after 24 h and Mg-Fe calcites formed after 96 h. These experiments suggest a possible low-temperature inorganic origin for the carbonates in martian meteorite ALH 84001. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Hernandez Engn, Houston, TX 77058 USA. Lockheed Martin, Houston, TX 77058 USA. RP Ming, DW (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code SN2, Houston, TX 77058 USA. EM douglas.w.ming1@jsc.nasa.gov NR 34 TC 44 Z9 44 U1 0 U2 9 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAY PY 2000 VL 35 IS 3 BP 457 EP 465 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 319GL UT WOS:000087333100004 ER PT J AU Wasilewski, P Dickinson, T AF Wasilewski, P Dickinson, T TI Aspects of the validation of magnetic remanence in meteorites SO METEORITICS & PLANETARY SCIENCE LA English DT Article AB Meteorite magnetic records constitute physical evidence of processes acting during early solar system evolution. Consequently, the validation of these records is important in meteorite research. The first step in the validation process should be the REM value, The REM value is the ratio of natural remanence (NRM) to saturation remanent magnetization imparted by a 1 T magnetic field (SIRM). The REM values range over 3 to 4 orders of magnitude for stony meteorites and for chondrules from Allende (C3V-S1), Bjurbole (L4-S1), and Chainpur (LL3-S1) meteorites. The REM values computed from published NRM and SIRM data identify many orders of magnitude range in the REM values including REM values >100 x 10(-3). These data suggest a dependence for the NRM intensity on the curatorial location from which the sample was obtained. Any earth rock acquiring thermoremanent magnetization (TRM) in the geomagnetic field has a restricted range in REM mostly between 5 and 50 x 10(-3), the exception being the mineral hematite in the multidomain size range, The only terrestrial samples with REM much greater than 100 x 10(-3) are those struck by lightning. The REM value provides a physical basis for recognition between valid records and those that "might be contaminated," The isothermal remanence acquisition (RA) curve is presented as a contamination curve that allows an indication of the level of magnetic field contamination required to give the computed "REM" (RM/SIRM) value. In the case of the Bjurbole and Chainpur chondrules, with REM values >100 x 10-3, the RA curve indicates that unrealistically large contamination magnetic fields would be required to give REM values greater than 100 x 10-3. This would suggest contamination other than by a hand magnet that is normally available to an experimenter. This would require an explanation that would involve large magnetic fields during chondrule formation, or some extraordinary remanence acquisition mechanism that remains to be described. Magnetic contamination experiments, using similar to 80 and similar to 40 mT magnets, demonstrate that the "REM" values and extent of modification of the magnetic vector record are mineralogy dependent, and this is mostly related to the amount and characteristics of the mineral tetrataenite. The complexity of the meteorite records suggest validation of the record as a first step. The REM value is the first physical statement that can be made in this validation. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. RP Wasilewski, P (reprint author), NASA, Goddard Space Flight Ctr, Mail Code 691, Greenbelt, MD 20771 USA. NR 21 TC 27 Z9 27 U1 2 U2 6 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 2000 VL 35 IS 3 BP 537 EP 544 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 319GL UT WOS:000087333100010 ER PT J AU Buchanan, PC Mittlefehldt, DW Hutchison, R Koeberl, C Lindstrom, DJ Pandit, MK AF Buchanan, PC Mittlefehldt, DW Hutchison, R Koeberl, C Lindstrom, DJ Pandit, MK TI Petrology of the Indian eucrite Piplia Kalan SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID HISTORY; ABUNDANCES; PYROXENES AB Piplia Kalan is an equilibrated eucrite consisting of 60-80 vol% lithic clasts in a subordinate brecciated matrix. Ophitic/subophitic clasts fall into two groups: finer-grained lithology A and coarser-grained lithology B. Very fine-grained clasts with equigranular textures (lithology C) also occur and originally were hypocrystalline in texture. The variety of materials represented in Piplia Kalan suggests cooling histories ranging from quenching to slower crystallization. Despite textural differences, clasts and matrix have similar mineral and bulk compositions. Thus, Piplia Kalan is probably best classified as a genomict breccia that could represent fragments of a single lava flow or shallow intrusive body, including fine-grained or glassy outer margin and more slowly cooled coarser-grained interior. Bulk composition suggests that the meteorite is most closely related to the main group eucrites, but it probably was affected by minor amounts of fractional crystallization. Piplia Kalan displays evidence of an early shock event, including brecciated matrix and areas of lithic clasts that contain very fine-grained, granular pyroxene between deformed feldspar laths. The meteorite also displays evidence of at least one episode of extensive thermal metamorphism: hypocrystalline materials are recrystallized to hornfelsic textures and minerals throughout the meteorite contain abundant inclusions that are relatively large in size. Veins of brown glass transect both clasts and matrix and indicate a second, postmetamorphism shock event. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin, Houston, TX 77058 USA. Nat Hist Museum, Dept Mineral, London SW7 5BD, England. Univ Vienna, Inst Geochem, A-1090 Vienna, Austria. Univ Rajasthan, Dept Geol, Jaipur 302004, Rajasthan, India. RP Buchanan, PC (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code SN2, Houston, TX 77058 USA. NR 26 TC 8 Z9 8 U1 1 U2 3 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 2000 VL 35 IS 3 BP 609 EP 615 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 319GL UT WOS:000087333100017 ER PT J AU Marcinkevicius, S Leon, R AF Marcinkevicius, S Leon, R TI Carrier capture and relaxation in quantum dot structures with different dot densities SO MICROELECTRONIC ENGINEERING LA English DT Article; Proceedings Paper CT 3rd International Conference on Low Dimensional Structures and Devices (LDSD 99) CY SEP 15-17, 1999 CL ANTALYA, TURKEY DE quantum dots; time-resolved photoluminescence; carrier capture ID ELECTRONIC-STRUCTURE; TRANSPORT; PHONONS AB Carrier dynamics has been measured by time-resolved photoluminescence in self-assembled InGaAs/GaAs quantum dot structures with dot density of the order of 10(8) to 10(10) cm(2). The time of carrier transfer into a dot, which is in the region from 2 to 20 PS, has been found to decrease with increasing quantum dot density. The temperature and photoexcited carrier density dependencies of the carrier transfer times suggest that potential barriers at the barrier, wetting layer and quantum dot interfaces hinder carrier capture in low-density quantum dot structures. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Royal Inst Technol, Dept Phys Opt, S-10044 Stockholm, Sweden. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Marcinkevicius, S (reprint author), Royal Inst Technol, Dept Phys Opt, S-10044 Stockholm, Sweden. NR 15 TC 0 Z9 1 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-9317 J9 MICROELECTRON ENG JI Microelectron. Eng. PD MAY PY 2000 VL 51-2 BP 79 EP 83 DI 10.1016/S0167-9317(99)00467-0 PG 5 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Optics; Physics, Applied SC Engineering; Science & Technology - Other Topics; Optics; Physics GA 320ZY UT WOS:000087431500011 ER PT J AU Barstow, MA Dreizler, S Holberg, JB Finley, DS Werner, K Hubeny, I Sion, EM AF Barstow, MA Dreizler, S Holberg, JB Finley, DS Werner, K Hubeny, I Sion, EM TI The discovery of photospheric nickel in the hot DO white dwarf REJ 0503-289 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE stars : abundances; stars : atmospheres; white dwarfs; ultraviolet : stars ID MODEL STELLAR ATMOSPHERES; TEMPERATURE SCALE; MASS-DISTRIBUTION; SPECTRAL-ANALYSIS; ULTRAVIOLET; STARS; IRON; RE-0503-289; ABUNDANCES; ELEMENTS AB We present the first evidence for the direct detection of nickel in the photosphere of the hot DO white dwarf REJ 0503-289, While this element has been seen previously in the atmospheres of hot H-rich white dwarfs, this is one of the first similar discoveries in a He-rich object. Intriguingly, iron, which is observed to be more abundant than Ni in the hot DA stars, is not detected, the upper limit to its abundance (Fe/He = 10(-6)) implying an Fe/Ni ratio a factor of 10 lower than seen in the H-rich objects (Ni/He = 10(-5) for REJ 0503-289), The abundances of nickel and various other elements heavier than He were determined from Goddard High Resolution Spectrograph spectra, We used two completely independent sets of non-local thermodynamic equilibrium model atmospheres, which both provide the same results. This not only reduces the possibility of systematic errors in our analysis, but is also an important consistency check for both model atmosphere codes. We have also developed a more objective method of determining T-eff and log g, from the He lines in the optical spectrum, in the form of a formal fitting of the line profiles to a grid of model spectra, an analogue of the standard procedure utilizing the Balmer lines in DA white dwarfs. This gives the assigned uncertainties in T-eff and log g a firm statistical basis and allows us to demonstrate that inclusion of elements heavier than H, He and C in the spectral calculations, exclusively considered in most published optical analyses, yields a systematic downward shift in the measured value of T-eff. C1 Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England. Univ Tubingen, Inst Astron & Astrophys, D-72076 Tubingen, Germany. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Eureka Sci Inc, Oakland, CA 94602 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20711 USA. Villanova Univ, Dept Astron & Astrophys, Villanova, PA 19085 USA. RP Barstow, MA (reprint author), Univ Leicester, Dept Phys & Astron, Univ Rd, Leicester LE1 7RH, Leics, England. NR 42 TC 11 Z9 11 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 MAY 1 PY 2000 VL 314 IS 1 BP 109 EP 122 DI 10.1046/j.1365-8711.2000.03295.x PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 317CY UT WOS:000087209800015 ER PT J AU Stothers, RB AF Stothers, RB TI Turbulent eddy viscosity and large-scale convection in the Sun SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE convection; turbulence; Sun : granulation; Sun : interior ID COMPRESSIBLE CONVECTION; SOLAR GRANULATION; SIMULATIONS; SURFACE AB It is suggested here that the laminar character of the large-scale deep convective flows appearing in numerical simulations of the convective envelope of the Sun arises from the effect of turbulent eddy viscosity. Previously, M. Schwarzschild suggested the same idea to explain the observed surface granulation in the Sun. C1 NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. RP Stothers, RB (reprint author), NASA, Goddard Space Flight Ctr, Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 28 TC 4 Z9 4 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 MAY 1 PY 2000 VL 314 IS 1 BP L7 EP L9 DI 10.1046/j.1365-8711.2000.03499.x PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 317CY UT WOS:000087209800002 ER PT J AU Ishihara, A Ohira, Y Roy, RR Nagaoka, S Sekiguchi, C Hinds, WE Edgerton, VR AF Ishihara, A Ohira, Y Roy, RR Nagaoka, S Sekiguchi, C Hinds, WE Edgerton, VR TI Comparison of the response of motoneurons innervating perineal and hind limb muscles to spaceflight and recovery SO MUSCLE & NERVE LA English DT Article DE cell body size; microgravity; spinal motoneurons; succinate dehydrogenase activity ID SUCCINATE-DEHYDROGENASE ACTIVITY; OXIDATIVE ENZYME-ACTIVITY; RAT SPINAL NUCLEUS; SOMA SIZE RELATIONSHIPS; ROOT GANGLION NEURONS; ALPHA-MOTONEURONS; MOTOR NUCLEUS; TIBIALIS ANTERIOR; METABOLIC VARIATION; CYTOCHROME-OXIDASE AB The succinate dehydrogenase (SDH) activities and cell body sizes of motoneurons in the dorsomedial (DM) region of the ventral horn at the lower portion of the L5 and the LS segmental levels of the rat spinal cord were determined following 14 days of spaceflight and after 9 days of recovery on Earth and compared with those in the retrodorsolateral (RDL) region of the ventral horn at the same segmental levels. No changes in the mean SDH activity of motoneurons in the DM region were observed following spaceflight or after recovery. However, a decrease in the mean SDH activity of motoneurons with cell body sizes between 500 and 900 mu m(2) in the RDL region was observed following spaceflight and after recovery. These data indicate that moderate-sized motoneurons in the RDL region, which are most likely associated with the hind limb musculature, were responsive to the microgravity environment; In contrast, the motoneurons in the DM region associated with the perineal muscles (associated with predominantly fast, low-oxidative muscles which are recruited for relatively brief periods at high activation levels and have no load-bearing function at 1G) were not affected by microgravity. (C) 2000 John Wiley & Sons. Inc. C1 Kyoto Univ, Fac Integrated Human Studies, Neurochem Lab, Kyoto 6068501, Japan. Natl Inst Fitness & Sports, Dept Physiol & Biomech, Kanoya, Japan. Univ Calif Los Angeles, Inst Brain Res, Los Angeles, CA 90024 USA. Natl Space Dev Agcy Japan, Space Expt Grp, Tsukuba, Ibaraki 3058799, Japan. NASA, Ames Res Ctr, Payloads Off, Moffett Field, CA 94035 USA. Univ Calif Los Angeles, Dept Physiol Sci, Los Angeles, CA 90095 USA. RP Ishihara, A (reprint author), Kyoto Univ, Fac Integrated Human Studies, Neurochem Lab, Kyoto 6068501, Japan. NR 60 TC 22 Z9 24 U1 0 U2 1 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 USA SN 0148-639X J9 MUSCLE NERVE JI Muscle Nerve PD MAY PY 2000 VL 23 IS 5 BP 753 EP 762 DI 10.1002/(SICI)1097-4598(200005)23:5<753::AID-MUS13>3.0.CO;2-J PG 10 WC Clinical Neurology; Neurosciences SC Neurosciences & Neurology GA 310DB UT WOS:000086810300013 PM 10797399 ER PT J AU Zimmerman, RL Ila, D Williams, EK Gasic, B Elsamadicy, A Evelyn, AL Poker, DB Hensley, DK Larkin, DJ AF Zimmerman, RL Ila, D Williams, EK Gasic, B Elsamadicy, A Evelyn, AL Poker, DB Hensley, DK Larkin, DJ TI Gold, silver and copper nanocrystal formation in SiC by MeV implantation SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS LA English DT Article; Proceedings Paper CT 10th International Conference on Radioation Effects in Insulators (REI-10) CY JUL 18-23, 1999 CL JENA, GERMANY SP Deutsch Forsch Gemeinsch, Friedrich Schiller Univ Jena, Thruinger Minist Wissensch, Forsch & Kultur, Elsevier Sci BV, Amsterdam, High Voltage Engn Europa BV, Amersfoort, Carl Zeiss Jena GmbH, Jena, Jenoptik AG, Jena, Layertec GmbH, Mellingen, VACOM GmbH, Jena, JENION, Jena, PINK GmbH, Wertheim DE implantation; nanocrystals; nonlinear optical materials ID ION-IMPLANTATION; SILICA; NANOCLUSTERS AB Nanoclusters gold, silver and copper are produced in 6H-SiC by implanting 1.0 MeV Au, 2.0 MeV Ag and 2.0 MeV Cu into the Si face of SiC at room or elevated temperature followed by annealing at various temperatures. The absorption bands for each type of metal nanoclusters in SIC were determined using optical absorption spectrophotometry, Elevated temperature implantation reduces optical absorption due to ion implantation induced defects. Using the Mie theory, we determined the index of refraction in the implanted volume. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Alabama A&M Univ, Ctr Irradiat Mat, Normal, AL 35762 USA. Oak Ridge Natl Lab, Div Solid State, Oak Ridge, TN 37831 USA. NASA, Gleen Res Ctr, Cleveland, OH 44135 USA. RP Zimmerman, RL (reprint author), Alabama A&M Univ, Ctr Irradiat Mat, POB 1447, Normal, AL 35762 USA. RI Hensley, Dale/A-6282-2016 OI Hensley, Dale/0000-0001-8763-7765 NR 13 TC 15 Z9 17 U1 3 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-583X J9 NUCL INSTRUM METH B JI Nucl. Instrum. Methods Phys. Res. Sect. B-Beam Interact. Mater. Atoms PD MAY PY 2000 VL 166 BP 892 EP 896 DI 10.1016/S0168-583X(99)01040-X PG 5 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Atomic, Molecular & Chemical; Physics, Nuclear SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 320VU UT WOS:000087422200154 ER PT J AU Riasati, VR Zhou, HY Chao, TH Gregory, DA AF Riasati, VR Zhou, HY Chao, TH Gregory, DA TI Data reduction via the wavelet transform for the synthesis of the projection-slice filter SO OPTICAL ENGINEERING LA English DT Article DE projection-slice filter; wavelet transforms; synthetic discriminant functions; optical pattern recognition ID OPTICAL-PATTERN RECOGNITION; PERFORMANCE AB The projection-slice synthetic discriminant function, which was described earlier, reduces significant portions of the training data in the synthesis process as compared to the normal synthetic discriminant function filters. This enables the matching of particular features of each training image. The wavelet transform is utilized to further reduce the data in the synthesis stage and thereby reduce the data overlap in filters. The method for this type of filter synthesis is discussed and simulation results of the algorithms involved are presented to show that the relative performance of the newly synthesized filter is improved. while the data representing the training images has been reduced. (C) 2000 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(00)01505-1]. C1 Univ S Alabama, Mobile, AL 36688 USA. CALTECH, Jet Prop Lab, Adv Comp Technol Grp, Pasadena, CA 91109 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. RP Riasati, VR (reprint author), Univ S Alabama, Mobile, AL 36688 USA. NR 19 TC 0 Z9 0 U1 0 U2 0 PU SPIE-INT SOCIETY OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, BELLINGHAM, WA 98225 USA SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD MAY PY 2000 VL 39 IS 5 BP 1218 EP 1222 DI 10.1117/1.602489 PG 5 WC Optics SC Optics GA 313FZ UT WOS:000086990800016 ER PT J AU Post, RB Welch, RB Clark, VD AF Post, RB Welch, RB Clark, VD TI Why do pitched horizontal lines have such a small effect on visually perceived eye level? SO PERCEPTION & PSYCHOPHYSICS LA English DT Article ID GREAT-CIRCLE MODEL; SPATIAL SUMMATION; ELEVATION; LOCALIZATION; PERCEPTION; FIELD AB In two experiments, visually perceived eye level (VPEL) was measured while subjects viewed two-dimensional displays that were either upright or pitched 20 degrees top-toward or 20 degrees top-away from them. In Experiment I, it was demonstrated that binocular exposure to a pair of pitched vertical lines or to a pitched random dot pattern caused a substantial upward VPEL shift for the top-toward pitched array and a similarly large downward shift for the top-away array. On the other hand, the same pitches of a pair of horizontal lines (viewed binocularly or monocularly) produced much smaller VPEL shifts. Because the perceived pitch of the pitched horizontal line display was nearly the same as the perceived pitch of the pitched vertical line and dot array, the relatively small influence of pitched horizontal lines on VPEL cannot be attributed simply to an underestimation of their pitch. In Experiment 2, the effects of pitched vertical lines, dots, and horizontal lines on VPEL were again measured, together with their effects on resting gaze direction (in the vertical dimension). As in Experiment 1, vertical lines and dots caused much larger VPEL shifts than did horizontal lines. The effects of the displays on resting gaze direction were highly similar to their effects on VPEL. These results are consistent with the hypothesis that VPEL shifts caused by pitched visual arrays are due to the direct influence of these arrays on the oculomotor system and are not mediated by perceived pitch. C1 Univ Calif Davis, Dept Psychol, Davis, CA 95616 USA. NASA, Ames Res Ctr, Mt View, CA USA. RP Post, RB (reprint author), Univ Calif Davis, Dept Psychol, Davis, CA 95616 USA. NR 20 TC 5 Z9 5 U1 0 U2 1 PU PSYCHONOMIC SOC INC PI AUSTIN PA 1710 FORTVIEW RD, AUSTIN, TX 78704 USA SN 0031-5117 J9 PERCEPT PSYCHOPHYS JI Percept. Psychophys. PD MAY PY 2000 VL 62 IS 4 BP 726 EP 734 DI 10.3758/BF03206919 PG 9 WC Psychology; Psychology, Experimental SC Psychology GA 321HJ UT WOS:000087449800007 PM 10883581 ER PT J AU Duncan, RV Sergatskov, DA Boyd, STP McCarson, TD Babkin, A Day, PK Elliott, D AF Duncan, RV Sergatskov, DA Boyd, STP McCarson, TD Babkin, A Day, PK Elliott, D TI Onset of superfluidity far from equilibrium: dynamical effects on the correlation length SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE critical phenomena; heat transport; microgravity; nonequilibrium superfluidity ID NONLINEAR HEAT-TRANSPORT; THERMAL-BOUNDARY RESISTANCE; HIGH-RESOLUTION THERMOMETER; T-LAMBDA; VAPOR-PRESSURE; HE-4; TRANSITION; HELIUM; CONDUCTIVITY; POINT AB Nonlinear heat conduction has recently been measured near the superfluid transition in pure He-4 at very low heat flux Q. Since both dynamic effects and gravity limit the divergence of the superfluid correlation length near the transition at low-Q, these measurements must be repeated in the microgravity environment in order to observe the dynamic effects in isolation. Comparison of the microgravity data to similar data obtained on Earth will provide experimental insight into the effect of gravity on this nonlinear conduction region at low heat flux when theoretical predictions are lacking. While some measurement advantages exist in the microgravity laboratory, it is the study of the direct effect of gravity on the nonlinear conduction measurements that motivate the microgravity need. (C) 2000 Published by Elsevier Science B.V. All rights reserved. C1 Univ New Mexico, Dept Phys & Astron, Albuquerque, NM 87131 USA. Jet Propuls Lab, Pasadena, CA 91109 USA. RP Duncan, RV (reprint author), Univ New Mexico, Dept Phys & Astron, 800 Yale Blvd NE, Albuquerque, NM 87131 USA. NR 52 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4526 J9 PHYSICA B JI Physica B PD MAY PY 2000 VL 280 IS 1-4 BP 45 EP 49 DI 10.1016/S0921-4526(99)01445-3 PG 5 WC Physics, Condensed Matter SC Physics GA 301WP UT WOS:000086333700011 ER PT J AU Israelsson, UE Lee, MC AF Israelsson, UE Lee, MC TI NASA/JPL plans for fundamental physics research in space SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE microgravity; International Space Station (ISS); technology AB In 1998, about 100 researchers met twice to develop plans for the future in this research area. The results of these meetings have been collected in a package titled "A Roadmap for Fundamental Physics in Space". A summary of the Roadmap will be presented along with an overview of the current program. Research is being performed in Low Temperature and Condensed Matter Physics, Laser Cooling and Atomic Physics, and Gravitational and Relativistic Physics. There are currently over 50 investigators in the program of which 8 are being evaluated as potential flight experiments. The number of investigators is expected to grow further during the next selection cycle, planned to start toward the end of this year. In the near future, our investigators will be able to take advantage of long duration experimentation in Space using a suite of different carriers under development. (C) 2000 Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Washington, DC 20546 USA. RP Israelsson, UE (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mailstop 233-200, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4526 J9 PHYSICA B JI Physica B PD MAY PY 2000 VL 280 IS 1-4 BP 499 EP 500 DI 10.1016/S0921-4526(99)01847-5 PG 2 WC Physics, Condensed Matter SC Physics GA 301WP UT WOS:000086333700145 ER PT J AU Yeh, NC Strayer, DM Anderson, VL Asplund, N AF Yeh, NC Strayer, DM Anderson, VL Asplund, N TI Superconducting-cavity-stabilized oscillators (SCSO) for precise frequency measurements SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE cavity stabilized oscillators; SCSO; precise frequency measurements ID HIGH-RESOLUTION THERMOMETER AB We report our progress in achieving precise frequency measurements by integrating high-Q superconducting-cavity-stabilized oscillators (SCSO) with high-resolution thermometry and phase-locked-loop (PLL) techniques. The relevant effects that influence the ultimate frequency stability of SCSO (10(-17)-10(-18)) are described, and applications of this technique to precise measurements of the liquid helium critical phenomena are discussed. (C) 2000 Elsevier Science B.V. All rights reserved. C1 CALTECH, Dept Phys, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Yeh, NC (reprint author), CALTECH, Dept Phys, Pasadena, CA 91125 USA. NR 7 TC 3 Z9 6 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4526 J9 PHYSICA B JI Physica B PD MAY PY 2000 VL 280 IS 1-4 BP 557 EP 558 DI 10.1016/S0921-4526(99)01863-3 PG 2 WC Physics, Condensed Matter SC Physics GA 301WP UT WOS:000086333700161 ER PT J AU Gingrich, RM Williams, CP Cerf, NJ AF Gingrich, RM Williams, CP Cerf, NJ TI Generalized quantum search with parallelism SO PHYSICAL REVIEW A LA English DT Article ID NUCLEAR-MAGNETIC-RESONANCE; COMPUTATION; ALGORITHM; COMPUTER AB We generalize Grover's unstructured quantum search algorithm to enable it to work with arbitrary starting superpositions and arbitrary unitary operators. We show that the generalized quantum search algorithm, when cast in a special orthonormal basis, can be understood as performing an exact rotation of a starting superposition into a target superposition. We derive a formula for the success probability of the generalized quantum search algorithm after n rounds of amplitude amplification. We then use this formula to determine the optimal strategy for a punctuated quantum search algorithm, i.e., one in which the amplitude amplified state is observed before the point of maximum success probability. On average, the optimal strategy is about 12% better than the naive use of Grover's algorithm. The speedup obtained is not dramatic but it illustrates that a hybrid use of quantum computing and classical computing techniques can yield a performance that is better than either alone. In addition, we show that a punctuated quantum algorithm that takes the same average computation lime as Grover's standard algorithm only requires half the coherence time. We then extend the analysis to the case of a society of k quantum searches acting in parallel. We derive an analytic formula that connects the degree of parallelism with the expected computation time for k-parallel quantum search. The resulting parallel speedup scales as O(root k), while the minimum number of agents needed to ensure success, k, decreases as the inverse of the square of the achievable coherence time. This result has practical significance for the design of rudimentary quantum computers that are likely to have a limited coherence time. C1 CALTECH, WK Kellogg Radiat Lab, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Informat & Comp Technol Res Sect, Pasadena, CA 91109 USA. Free Univ Brussels, Ecole Polytech, B-1050 Brussels, Belgium. RP Gingrich, RM (reprint author), CALTECH, WK Kellogg Radiat Lab, Pasadena, CA 91125 USA. NR 18 TC 5 Z9 5 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD MAY PY 2000 VL 61 IS 5 BP art. no. EP 052313 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 312QD UT WOS:000086953200041 ER PT J AU Han, D Kim, YS Noz, ME AF Han, D Kim, YS Noz, ME TI Interferometers and decoherence matrices SO PHYSICAL REVIEW E LA English DT Article ID POLARIZATION OPTICS; BEAM SPLITTER; WIGNER; FORMALISM; ROTATIONS; SU(2) AB It is shown that the Lorentz group is the natural language for two-beam interferometers if there are no decoherence effects. This aspect of the interferometer can be translated into six-parameter representations of the Lorentz group, as in the case of polarization optics where there are two orthogonal components of one light beam. It is shown that there are groups of transformations which leave the coherency or density matrix invariant, and this symmetry property is formulated within the framework of Wigner's little groups. An additional mathematical apparatus is needed for the transition from a pure state to an impure state. Decoherence matrices are constructed for this process, and their properties are studied in detail. Experimental tests of this symmetry property are possible. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Phys, College Pk, MD 20742 USA. NYU, Dept Radiol, New York, NY 10016 USA. RP Han, D (reprint author), NASA, Goddard Space Flight Ctr, Code 935, Greenbelt, MD 20771 USA. NR 22 TC 16 Z9 16 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1063-651X J9 PHYS REV E JI Phys. Rev. E PD MAY PY 2000 VL 61 IS 5 BP 5907 EP 5913 DI 10.1103/PhysRevE.61.5907 PN B PG 7 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA 314RK UT WOS:000087071200060 ER PT J AU Hatchett, SP Brown, CG Cowan, TE Henry, EA Johnson, JS Key, MH Koch, JA Langdon, AB Lasinski, BF Lee, RW Mackinnon, AJ Pennington, DM Perry, MD Phillips, TW Roth, M Sangster, TC Singh, MS Snavely, RA Stoyer, MA Wilks, SC Yasuike, K AF Hatchett, SP Brown, CG Cowan, TE Henry, EA Johnson, JS Key, MH Koch, JA Langdon, AB Lasinski, BF Lee, RW Mackinnon, AJ Pennington, DM Perry, MD Phillips, TW Roth, M Sangster, TC Singh, MS Snavely, RA Stoyer, MA Wilks, SC Yasuike, K TI Electron, photon, and ion beams from the relativistic interaction of Petawatt laser pulses with solid targets SO PHYSICS OF PLASMAS LA English DT Article; Proceedings Paper CT 41st Annual Meeting of the Division of Plasma Physics of the American-Physical-Society CY NOV 15-19, 1999 CL SEATTLE, WASHINGTON SP Amer Phys Soc, Div Plasma Phys ID PLASMA INTERACTIONS AB In recent Petawatt laser experiments at Lawrence Livermore National Laboratory, several hundred joules of 1 mu m laser light in 0.5-5.0-ps pulses with intensities up to 3 x 10(20) W cm(-2) were incident on solid targets and produced a strongly relativistic interaction. The energy content, spectra, and angular patterns of the photon, electron, and ion radiations have all been diagnosed in a number of ways, including several novel (to laser physics) nuclear activation techniques. About 40%-50% of the laser energy is converted to broadly beamed hot electrons. Their beam centroid direction varies from shot to shot, but the resulting bremsstrahlung beam has a consistent width. Extraordinarily luminous ion beams (primarily protons) almost precisely normal to the rear of various targets are seen-up to 3 x 10(13) protons with kT(ion) similar to several MeV representing similar to 6% of the laser energy. Ion energies up to at least 55 MeV are observed. The ions appear to originate from the rear target surfaces. The edge of the ion beam is very sharp, and collimation increases with ion energy. At the highest energies, a narrow feature appears in the ion spectra, and the apparent size of the emitting spot is smaller than the full back surface area. Any ion emission from the front of the targets is much less than from the rear and is not sharply beamed. The hot electrons generate a Debye sheath with electrostatic fields of order MV per micron, which apparently accelerate the ions. (C) 2000 American Institute of Physics. [S1070-664X(00)93905-3]. C1 Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. GSI Lab, Darmstadt, Germany. RP Hatchett, SP (reprint author), Univ Calif Lawrence Livermore Natl Lab, POB 808, Livermore, CA 94550 USA. RI MacKinnon, Andrew/P-7239-2014; Cowan, Thomas/A-8713-2011 OI MacKinnon, Andrew/0000-0002-4380-2906; Cowan, Thomas/0000-0002-5845-000X NR 16 TC 760 Z9 774 U1 3 U2 44 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 MAY PY 2000 VL 7 IS 5 BP 2076 EP 2082 DI 10.1063/1.874030 PN 2 PG 7 WC Physics, Fluids & Plasmas SC Physics GA 304XZ UT WOS:000086511000059 ER PT J AU Birn, J Thomsen, MF Borovsky, JE Reeves, GD Hesse, M AF Birn, J Thomsen, MF Borovsky, JE Reeves, GD Hesse, M TI Particle acceleration in the dynamic magnetotail SO PHYSICS OF PLASMAS LA English DT Article; Proceedings Paper CT 41st Annual Meeting of the Division of Plasma Physics of the American-Physical-Society CY NOV 15-19, 1999 CL SEATTLE, WASHINGTON SP Amer Phys Soc, Div Plasma Phys ID GEOSYNCHRONOUS OBSERVATIONS; INJECTIONS; SIMULATIONS; ORBIT AB The acceleration of charged particles to suprathermal energies is investigated in the context of magnetospheric substorms. Ion and electron test particle orbits are studied in dynamically evolving fields obtained from a three-dimensional resistive magnetohydrodynamic (MHD) simulation of reconnection in the near magnetotail. The simulation leads to plasmoid formation and ejection into the distant tail and an earthward collapse of the field in the inner tail. Energization of particles takes place predominantly in the inner tail region earthward of the neutral line, rather than in the vicinity of the neutral line. The test particle studies reproduce major observed characteristics of energetic particle flux increases ("injections") in the inner magnetotail; a fast rise, a limited energy range of the flux increases, and spatially varying delays between the onsets of ion and electron injections. Acceleration mechanisms include a "quasipotential" acceleration, resulting from nonadiabatic particle motion in the direction of the cross-tail electric field, as well as betatron and Fermi-type acceleration. The major source region for accelerated ions (electrons) in the hundreds of keV range is the central plasma sheet at the dawn (dusk) flank, outside the reconnection site. Since this source plasma is already hot and dense, a moderate energization by a factor of approximately 2 is sufficient to explain the observed increases in the energetic particle fluxes. Differences between ions and electrons at energies of a few tens of keV are found to be associated with differences in the bounce periods, which enables ions to circumvent the acceleration region, so that only electron fluxes in that energy range become enhanced. (C) 2000 American Institute of Physics. [S1070-664X(00)93805-9]. C1 Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20770 USA. RP Birn, J (reprint author), Univ Calif Los Alamos Natl Lab, MS D466, Los Alamos, NM 87545 USA. RI Hesse, Michael/D-2031-2012; Reeves, Geoffrey/E-8101-2011 OI Reeves, Geoffrey/0000-0002-7985-8098 NR 20 TC 17 Z9 17 U1 0 U2 2 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 MAY PY 2000 VL 7 IS 5 BP 2149 EP 2156 DI 10.1063/1.874035 PN 2 PG 8 WC Physics, Fluids & Plasmas SC Physics GA 304XZ UT WOS:000086511000068 ER PT J AU Kletetschka, G Wasilewski, PJ Taylor, PT AF Kletetschka, G Wasilewski, PJ Taylor, PT TI Hematite vs. magnetite as the signature for planetary magnetic anomalies? SO PHYSICS OF THE EARTH AND PLANETARY INTERIORS LA English DT Article DE hematite; magnetite; magnetic anomalies; magnetic remanence; induced magnetization; thermoremanent magnetization; magnetic susceptibility; TRM; remanence acquisition; hematite morphology; hysteresis properties; coercivity; National Museum of Natural History; REM; SIRM; saturation isothermal remanent magnetization; mixtures ID HYSTERESIS AB Crustal magnetic anomalies are the result of adjacent geologic units having contrasting magnetization. This magnetization arises from induction and/or remanence. In a planetary context we now know that Mars has significant crustal magnetic anomalies due to remanent magnetization, while on the Earth both remanence and induction can contribute to the magnetic anomaly, because of the presence of the Earth's magnetic field. If there is a significant induced magnetization (IM) then magnetite is commonly assumed as the source, since it has a much greater magnetic susceptibility, when compared with other magnetic minerals. We investigated the thermoremanent magnetization (TRM) acquisition of hematite to determine if the remanent and induced magnetization of hematite could compete with magnetite in weak magnetic fields up to 1 mT. TRM acquisition curves of magnetite and hematite show that multidomain hematite approaches TRM saturation (0.3-0.4 A m(2)/kg) in fields as low as 0.1 mT, However, multidomain magnetite reaches only a few percent of its TRM saturation in a field of 0.1 mT (0.02-0.06 A m(2)/kg). These results suggest that a mineral such as multidomain hematite and, perhaps, other minerals with significant remanence and minor induced magnetization may play an important role in providing requisite magnetization contrast, Consequently, we should reevaluate where multidomain hematite exists in significant concentration, allowing a better insight into the role of remanent magnetization in the interpretation of the magnetic anomalies. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kletetschka, G (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Kletetschka, Gunther/C-9996-2011; Taylor, Patrick/D-4707-2012 OI Kletetschka, Gunther/0000-0002-0645-9037; Taylor, Patrick/0000-0002-1212-9384 NR 23 TC 48 Z9 48 U1 0 U2 9 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0031-9201 J9 PHYS EARTH PLANET IN JI Phys. Earth Planet. Inter. PD MAY PY 2000 VL 119 IS 3-4 BP 259 EP 267 DI 10.1016/S0031-9201(00)00141-2 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 317UP UT WOS:000087245600006 ER PT J AU Formisano, V Grassi, D Piccioni, G Pearl, J Hanel, R Bjoraker, G Conrath, B AF Formisano, V Grassi, D Piccioni, G Pearl, J Hanel, R Bjoraker, G Conrath, B TI IRIS Mariner 9 data revisited: 1. An instrumental effect SO PLANETARY AND SPACE SCIENCE LA English DT Article DE IRIS Mariner 9 instrument; Fourier spectrometry ID INFRARED SPECTROSCOPY AB Small spurious features are present in data from the Mariner 9 Infrared Interferometer Spectrometer (IRIS). These represent a low amplitude replication of the spectrum with a doubled wavenumber scale. This replication arises principally from an internal reflection of the interferogram at the input window. An algorithm is provided to correct for the effect, which is at the 2% level. We believe that the small error in the uncorrected spectra does not materially affect previous results; however, it may be significant for some future studies at short wavelengths. The IRIS spectra are also affected by a coding error in the original calibration that results in only positive radiances. This reduces the effectiveness of averaging spectra to improve the signal to noise ratio at small signal levels. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 CNR, IFIS, Area Tor Vergata, I-00131 Rome, Italy. CNR, IAS, Area Tor Vergata, I-00131 Rome, Italy. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cornell Univ, Ithaca, NY USA. RP Formisano, V (reprint author), CNR, IFIS, Area Tor Vergata, I-00131 Rome, Italy. RI Bjoraker, Gordon/D-5032-2012; OI Piccioni, Giuseppe/0000-0002-7893-6808 NR 9 TC 6 Z9 6 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD MAY PY 2000 VL 48 IS 6 BP 569 EP 576 DI 10.1016/S0032-0633(00)00041-6 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 334HL UT WOS:000088181000004 ER PT J AU Morton, TL Chock, R Long, KJ Bailey, S Messenger, SR Walters, RJ Summers, GP AF Morton, TL Chock, R Long, KJ Bailey, S Messenger, SR Walters, RJ Summers, GP TI Use of displacement damage dose in an engineering model of GaAs solar cell radiation damage SO PROGRESS IN PHOTOVOLTAICS LA English DT Article; Proceedings Paper CT 16th Conference on Space Photovoltaic Research and Technology (SPRAT XVI) CY 1999 CL NASA GLENN RES CTR, CLEVELAND, OHIO HO NASA GLENN RES CTR ID PROTON AB In this study we have combined a method of calculating radiation induced damage to solar cells using Non-Ionizing Energy Loss (NIEL), with models of Ear rh orbiting radiation in arbitrary orbits, to assess the lifetime of solar cells. This paper provides a comparison of the NIEL technique to results from the JPL Radiation Handbook, and to actual space experimental damage results. In addition, we discuss ways of extending the calculation to newel solar cell materials, as well as environments outside of the Earth's orbit. Copyright (C) 2000 John Wiley & Sons, Ltd. C1 Ohio Aerosp Inst, Brook Pk, OH 44142 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. SFA Inc, Largo, MD 20774 USA. USN, Res Lab, Washington, DC 20375 USA. Univ Maryland Baltimore Cty, Baltimore, MD 21250 USA. RP Morton, TL (reprint author), Ohio Aerosp Inst, Brook Pk, OH 44142 USA. NR 8 TC 1 Z9 1 U1 0 U2 3 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 1062-7995 J9 PROG PHOTOVOLTAICS JI Prog. Photovoltaics PD MAY-JUN PY 2000 VL 8 IS 3 BP 339 EP 343 DI 10.1002/1099-159X(200005/06)8:3<339::AID-PIP318>3.0.CO;2-V PG 5 WC Energy & Fuels; Materials Science, Multidisciplinary; Physics, Applied SC Energy & Fuels; Materials Science; Physics GA 330KZ UT WOS:000087962400007 ER PT J AU Tsang, L Chen, CT Chang, ATC Guo, JJ Ding, KH AF Tsang, L Chen, CT Chang, ATC Guo, JJ Ding, KH TI Dense media radiative transfer theory based on quasicrystalline approximation with applications to passive microwave remote sensing of snow SO RADIO SCIENCE LA English DT Article ID MONTE-CARLO SIMULATIONS; PAIR DISTRIBUTION-FUNCTIONS; EXTINCTION RATE; PARTICLES; MODEL AB Dense media radiative transfer (DMRT) equations based on quasicrystalline approximation (QCA) for densely distributed moderate size particles are developed. We first compute the effective propagation constant and coherent transmission into a dense medium on the basis of the generalized Lorentz-Lorenz law and the generalized Ewald-Oseen extinction theorem. The absorption coefficient of the dense media is then calculated. The distorted Born approximation is next applied to a thin layer to determine the bistatic scattering coefficients and the scattering coefficient. The phase matrix in DMRT is then obtained as bistatic scattering coefficient per unit volume. The model is applied to multiple sizes and for sticky particles. Numerical results are illustrated for extinction and brightness temperatures in passive remote sensing using typical parameters in snow terrain. The QCA-based DMRT is also used to compare with satellite Special Sensor Microwave Imager (SSM/I) brightness temperatures for four channels at 19 and 37 GHz with vertical and horizontal polarizations and for two snow seasons. It shows reasonable agreement to snow depth of 1 m. C1 Univ Washington, Dept Elect Engn, Seattle, WA 98195 USA. NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Greenbelt, MD 20771 USA. USAF, Res Lab, Sensors Directorate,SNHE,Electromagnet Technol Di, Electromagnet Scattering Branch, Hanscom AFB, MA 01731 USA. RP Tsang, L (reprint author), Univ Washington, Dept Elect Engn, Box 352500, Seattle, WA 98195 USA. NR 15 TC 105 Z9 117 U1 1 U2 15 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD MAY-JUN PY 2000 VL 35 IS 3 BP 731 EP 749 DI 10.1029/1999RS002270 PG 19 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA 320AB UT WOS:000087377700007 ER PT J AU Simpson, JJ Hufford, G Pieri, D Berg, J AF Simpson, JJ Hufford, G Pieri, D Berg, J TI Failures in detecting volcanic ash from satellite-based technique SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID SOUFRIERE HILLS VOLCANO; ERUPTION COLUMNS; RADIATIVE-TRANSFER; WATER-VAPOR; MONTSERRAT; CLOUDS; AVHRR AB Immediate and accurate detection of airborne volcanic ash is an operational imperative of the aviation industry, especially jet aircraft. Ash encounters place passengers aboard these aircraft at severe risk and significantly impact, via forced rerouting, both the safety and profit margins of freight carriers due to their limited fuel supply. Moreover the airlines can suffer high economic costs for repair and -replacement of equipment. Operational detection. and tracking of volcanic ash by most national weather services has relied heavily on a split window differencing technique of thermal longwave infrared channels on currently operational satellites. Unfortunately, prior work on volcanic ash defection has not emphasised the dynamical interaction between the erupting volcano and the effects of overlying atmospheric Lr;ater vapor phreatic and phreatomagmatic water sources. Six volcanic ash eruptions from around the globe were chosen for study because they have wide variation in ambient atmospheric water vapor, available ground and surface water and different magma types. Results show that the present differencing technique is not uniformly effective in properly classifying volcanic ash pixels in the satellite scene and often falsely interprets meteorological clouds as volcanic ash clouds and conversely. Moreover it is not always a robust early detector, an operational aviation requirement. Seasonal variability in global integrated atmospheric water vapor coupled with the geographical distribution of currently active volcanoes, suggests the concerns discussed herein with regard to six specific eruptions, have applicability to the global aviation industry. Operational implications are discussed and a strategic proposal is presented on necessary steps to improve detection. (C) Elsevier Science Inc., 2000. C1 Univ Calif San Diego, Scripps Inst Oceanog, Digital Image Anal Lab, La Jolla, CA 92093 USA. Natl Weather Serv, Alaska Reg, Anchorage, AK USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Simpson, JJ (reprint author), Univ Calif San Diego, Scripps Inst Oceanog, Digital Image Anal Lab, La Jolla, CA 92093 USA. NR 53 TC 62 Z9 62 U1 1 U2 13 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 MAY PY 2000 VL 72 IS 2 BP 191 EP 217 DI 10.1016/S0034-4257(99)00103-0 PG 27 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 307YY UT WOS:000086682800006 ER PT J AU Birkett, CM AF Birkett, CM TI Synergistic remote sensing of Lake Chad: Variability of basin inundation SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID AREA; FLOODPLAIN; RADAR; AVHRR; RIVER AB During recent decades, drought and anthropogenic influences have led to the diminishment of Lake Chad with adverse effects on both food and water resources. The local population has learned to adapt to the reduced seasonal inundation of the lake basin but are vulnerable to both droughts and excessive inflows. Here synergistic satellite radar altimetry and near-infrared imagery are employed to gain knowledge of the current flooding patterns. Variations in surface level for the inflowing rivers and the permanent and seasonal lake waters are derived for the 1990s using data from the TOPEX/POSEIDON satellite. National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer images provide additional variations of basin inundation from 1995 to 1998, using a simple pixel histogram technique. With accuracy greater than or equal to 10cm rms, the altimetry reveals seasonal water-level variations of the order 0.5-6 m and there is a notable rise in minimum levels, 15-35 cm year(-1) within the lake basin. Peak-level phase lags of 4 to 5 months are also observed between the headwaters of the Chari/Logone rivers and the western lake marshes. Image results reveal that the permanent lake area is similar to 1.385 km(2), and that with an accuracy of similar to 5% the surrounding regions have been additionally flooding by up to similar to 3,600 km(2) year (-1). Despite current basin complexities, the synergistic area/level measurements corroborate the know hydraulic relationship at low water levels. Both measurement sets reflect the poor inundation years of 1993/1994 and 1997/1998, despite the indication of a general recovery in regional precipitation, inundation extent, and surface water level offers these remote sensing techniques as an additional tool for flood/drought forecasting and the availability of future fast delivery data, a mechanism for near-real time monitoring. (C) Elsevier Science Inc., 2000. C1 NASA, Univ Space Res Assoc, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Birkett, CM (reprint author), NASA, Univ Space Res Assoc, Goddard Space Flight Ctr, Mail Code 971, Greenbelt, MD 20771 USA. NR 40 TC 101 Z9 112 U1 4 U2 29 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 MAY PY 2000 VL 72 IS 2 BP 218 EP 236 DI 10.1016/S0034-4257(99)00105-4 PG 19 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 307YY UT WOS:000086682800007 ER PT J AU Chubb, DL Wolford, DS AF Chubb, DL Wolford, DS TI Rare earth optical temperature sensor SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB A new optical temperature sensor suitable for high temperatures (greater than or equal to 1700 K) and harsh environments is introduced. The key component of the sensor is the rare earth material contained at the end of a sensor that is in contact with the sample being measured. The measured narrow wavelength band emission from the rare earth is used to deduce the sample temperature. A simplified relation between the temperature and measured radiation was verified experimentally. The upper temperature limit of the sensor is determined by material limits to be approximately 2000 degrees C. The lower limit, determined by the minimum detectable radiation, is found to be approximately 700 K. At high temperatures 1 K resolution is predicted. Also, millisecond response times are calculated. [S0034-6748(00)04705-5]. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Chubb, DL (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 10 TC 7 Z9 7 U1 0 U2 5 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 MAY PY 2000 VL 71 IS 5 BP 2233 EP 2240 DI 10.1063/1.1150616 PG 8 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 309XJ UT WOS:000086794300053 ER PT J AU Balla, RJ Herring, GC AF Balla, RJ Herring, GC TI Raman shifting a tunable ArF laser to wavelengths of 190-240 nm SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID EXCIMER-LASER; RADIATION AB Tunable radiation at far-ultraviolet wavelengths is produced by Raman shifting a modified (285 mJ at 1-100 Hz repetition rate) ArF excimer laser. Multiple Stokes outputs are observed in H-2(20%), CH4(22%), D-2(53%), N-2(21%), SF6(2.1%), and CF4(0.35%). Numbers in parentheses are the first vibrational Stokes energy conversion efficiencies. We can access 70% of the frequency range 42 000-52 000 cm(-1) (190-240 nm), with Stokes pulse energies that vary from 0.2 mu J to 58 mJ inside the Raman cell. One of our better results, using 110 mJ of pump energy and D-2, is an energy conversion efficiency of 53% and a tunable Stokes energy that varies over the range 29-58 mJ/pulse for the wavelength range 204-206 nm. (C) 2000 American Institute of Physics. [S0034-6748(00)00105-2]. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Herring, GC (reprint author), NASA, Langley Res Ctr, M-S 493, Hampton, VA 23681 USA. NR 7 TC 8 Z9 8 U1 2 U2 2 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 MAY PY 2000 VL 71 IS 5 BP 2246 EP 2247 DI 10.1063/1.1150617 PG 2 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 309XJ UT WOS:000086794300055 ER PT J AU Balaram, J AF Balaram, J TI Kinematic state estimation for a Mars rover SO ROBOTICA LA English DT Article DE Mars rover; navigation; estimation techniques; process models; kinematic configuration ID MOBILE ROBOT; NAVIGATION AB The Jet Propulsion Laboratory (JPL) is embarking on a series of exploration missions to Mars. Long-range revers with several science instruments on board will traverse many kilometers on the surface. This paper describes some of the research underway at JPL as they pertain to navigation of these long-range revers. A brief description is provided of the Sojourner rover which recently completed a short-range, near-lander Mars mission. A research rover called Rocky-7 under development at JPL implements a number of new technologies for long-range Mars traverses. The kinematic configuration of this vehicle is described as is the sensor set. The paper then focuses on state estimation techniques used on-board Rocky-7. A brief review of rover-related state-estimation work is presented and an Extended Kalman Filter framework is introduced. This includes process models for translation, small-angle/quaternion based rotations, gyro bias and wheel contact as well as observation models for a gyro, sun-sensor, and accelerometer. A novel slip constraint technique is developed to allow incorporation into the filter of the highly non-linear kinematics resulting from the rover's rocker-bogey suspension mechanism and wheel-to-ground contact point variations. Simulation results are discussed to allow detailed comparisons with ground-truth data and experimental results from Rocky-7 are presented. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 19 TC 14 Z9 14 U1 1 U2 1 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0263-5747 EI 1469-8668 J9 ROBOTICA JI Robotica PD MAY-JUN PY 2000 VL 18 BP 251 EP 262 DI 10.1017/S0263574799002234 PN 3 PG 12 WC Robotics SC Robotics GA 322VR UT WOS:000087530400004 ER PT J AU Criss, JM Arendt, CP Connell, JW Smith, JG Hergenrother, PM AF Criss, JM Arendt, CP Connell, JW Smith, JG Hergenrother, PM TI Resin transfer molding and resin infusion fabrication of high-temperature composites SO SAMPE JOURNAL LA English DT Article ID TERMINAL PHENYLETHYNYL GROUPS; IMIDE OLIGOMERS; POLYIMIDE OLIGOMERS; ADHESIVE; PENDENT; ANHYDRIDES AB Resin transfer molding (RTM) and resin infusion (RI) are cost-effective processes for the fabrication of composite parts, particularly support structures such as frames and spars, As part of the high-speed research (HSR) program to develop technology for a Mach 2.4 high-speed civil transport with performance requirements for long term at 177 degrees C, phenylethynyl containing imide oligomers were developed for RTM and RI fabrication of composite parts. Two of these new materials, designated PETI-RTM and RFI, exhibited low-melt viscosity (similar to 0.1 - 1.0 Pa.s) at 260-280 degrees C with exceptional melt stability (>4 hours). The cured resins and their composites had high glass transition temperatures (Tgs), acceptable toughness, and good mechanical properties. The chemistry, mechanical, and physical properties of the resins, fabrication, and properties of composites via RTM and RI are discussed. C1 Boeing Co, Seattle, WA 98124 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 37 TC 28 Z9 31 U1 6 U2 11 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 USA SN 0091-1062 J9 SAMPE J JI Sampe J. PD MAY-JUN PY 2000 VL 36 IS 3 BP 32 EP 41 PG 10 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 310JH UT WOS:000086822400006 ER PT J AU Hidalgo, MA Cid, C Medina, J Vinas, AF AF Hidalgo, MA Cid, C Medina, J Vinas, AF TI A new model for the topology of magnetic clouds in the solar wind SO SOLAR PHYSICS LA English DT Article ID IMP-8 AB We present a model that describes the topology of a magnetic cloud. The model relates the magnetic field vector and current density of the cloud without assuming the force-fret condition. Fitting the model to the experimental data we obtain the current density, the attitude of the axis and the relative closest-approach distance between the spacecraft and the cloud axis. In this paper, several magnetic clouds of 1997 are analyzed. The results indicate that the topology presented in this paper explains the magnetic field inside a MC better than force-free models. A current density of the order of 10(-12) C m(-2) s(-1) is obtained in the fitting of all the events. C1 Univ Alcala de Henares, Dept Fis, Madrid, Spain. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Hidalgo, MA (reprint author), Univ Alcala de Henares, Dept Fis, Madrid, Spain. RI Hidalgo, Miguel/L-5826-2014; OI Hidalgo, Miguel/0000-0003-1617-2037; CID, CONSUELO/0000-0002-2863-3745 NR 17 TC 32 Z9 36 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD MAY PY 2000 VL 194 IS 1 BP 165 EP 174 DI 10.1023/A:1005206107017 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 362TX UT WOS:000089795300016 ER PT J AU Jong, JY Dorland, WD Fiorucci, T Zoladz, TF Nesman, TE AF Jong, JY Dorland, WD Fiorucci, T Zoladz, TF Nesman, TE TI Space shuttle engine signature analysis techniques SO SOUND AND VIBRATION LA English DT Article AB A Space Shuttle launch relies on its main engines to reach orbit. Engine measurements produce complex and unpredictable dynamic signals that are frequently corrupted with noise from many sources within the engine system. Examination of these measurements has stimulated the development of a hierarchy of advanced signal analysis techniques. These methods process and display pertinent diagnostic intelligence that is hidden within a measurement signal. Vital fault signature components can be enhanced and identified to provide better insight into defect symptoms thereby reducing false alarms or misinterpretations. The more useful techniques are described in this article with application examples drawn from actual engine tests. C1 Al Signal Res Inc, Huntsville, AL USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Jong, JY (reprint author), Al Signal Res Inc, Huntsville, AL USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU ACOUSTICAL PUBL INC PI BAY VILLAGE PA 27101 E OVIATT RD PO BOX 40416, BAY VILLAGE, OH 44140 USA SN 0038-1810 J9 SOUND VIB JI Sound Vib. PD MAY PY 2000 VL 34 IS 5 BP 24 EP 27 PG 4 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 324GD UT WOS:000087612700006 ER PT J AU Dickinson, RM AF Dickinson, RM TI Safety issues in SPS wireless power transmission SO SPACE POLICY LA English DT Article ID MICROWAVE-POWER AB The use of wireless power transmission in Space Solar Power (SSP) activities creates significant policy issues regarding the beam right-of-way. There will not be a single beam, there may well be hundreds of beams for economical systems. Are some or all of these power beams to be afforded priorities of space for unobstructed power delivery, or must the beaming systems be designed to be capable of detecting any and all potential beam interceptions and appropriately responding? The repeated interruptions for guaranteed safety of transit for freely moving air and space traffic are of great consequence. The safety issues are critical, but the implications for equipment transient protection, energy storage system costs and the quality of power delivery service are also significant for wireless power transmission economics. A scenario of precursor wireless power transmission developments leading up to and including SSP applications will be used to frame and to discuss the beamed power technology implications and policy issues. (C) 2000 Published by Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Dickinson, RM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 3 Z9 4 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0265-9646 J9 SPACE POLICY JI Space Policy PD MAY PY 2000 VL 16 IS 2 BP 117 EP 122 DI 10.1016/S0265-9646(00)00013-8 PG 6 WC International Relations; Social Sciences, Interdisciplinary SC International Relations; Social Sciences - Other Topics GA 316LP UT WOS:000087168900006 ER PT J AU ERb, RB Grey, J Kaya, N AF ERb, RB Grey, J Kaya, N TI International coordination of space solar power related activities SO SPACE POLICY LA English DT Article AB Because the need for energy is global, and many energy networks are already interdependent, because no one country has sufficient technological capability or sufficient funds to provide a space solar powered solution on its own, and because any such solution will require international regulation, international coordination will be vital to any attempt to produce energy for Earth from space. This will be made easier by the fact that work on the subject has already been widely publicized and distributed and cooperative efforts have already been made. Various coordinating approaches are described and the need to forge partnerships between government, industry and academia - with greater involvement of all non-space groups concerned with energy - is emphasized. A "terracing approach" to the actual implementation of SPS is suggested and outlined. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Canadian Space Agcy, Friendswood, TX 77546 USA. Amer Inst Aeronaut & Astronaut, Reston, VA 20191 USA. Kobe Univ, Kobe, Hyogo 657, Japan. RP ERb, RB (reprint author), NASA, JSC, Canadian Space Power Initiat, Mail Code OR, Houston, TX 77058 USA. NR 19 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0265-9646 J9 SPACE POLICY JI Space Policy PD MAY PY 2000 VL 16 IS 2 BP 123 EP 128 PG 6 WC International Relations; Social Sciences, Interdisciplinary SC International Relations; Social Sciences - Other Topics GA 316LP UT WOS:000087168900007 ER PT J AU Krymskii, AM Breus, TK Ness, NF Acuna, MH AF Krymskii, AM Breus, TK Ness, NF Acuna, MH TI The IMF pile-up regions near the Earth and Venus: Lessons for the solar wind - Mars interaction SO SPACE SCIENCE REVIEWS LA English DT Review ID GLOBAL HYBRID SIMULATION; MAGNETIC-FIELD; MHD SIMULATION; SUBSOLAR MAGNETOPAUSE; BOUNDARY-LAYER; PLASMA-WAVES; IONOSPHERE; IONOPAUSE; DAYSIDE; MISSION AB The Mars Global Surveyor mission has revealed that localized crustal paleomagnetic anomalies are a common feature of the Southern Hemisphere of Mars. The magnetometer measured small-scale magnetic fields associated with many individual magnetic anomalies have magnitudes ranging from hundreds to thousands nT at altitude above 120 km. That makes Mars globally different from both Venus and Earth. The data collected by Lunar Prospector near the Moon were interpreted as evidence that above regions of inferred strong surface magnetic fields on the Moon the SW flow is deflected, and a small-scale mini-magnetosphere exists under some circumstances. With a factor of 100 stronger magnetic fields at Mars and a lower SW dynamic pressure, those conditions offer the opportunity for a larger size of small `magnetospheres' which can be formed by the crustal magnetic fields. Outside the regions of the magnetic anomalies, the SW/Mars interaction is Venus-like. Thus, at Mars the distinguishing feature of the magnetic field pile-up boundary most likely varies from Venus-like to Earth-like above the crustal magnetic field regions. The observational data regarding the IMF pile-up regions near Venus and the Earth are initially reviewed. As long as the SW/Mars interaction remains like that at Venus, the IMF penetrates deep into the Martian ionosphere under the `overpressure' conditions. Results of numerical simulations and theoretical expectations regarding the temporal evolution of the IMF inside the Venus ionosphere and appearance of superthermal electrons are also reviewed and assessed. C1 Rostov Don State Univ, Space Phys Dept, Rostov On Don 344000, Russia. Russian Acad Sci, Inst Space Res, Moscow 117810, Russia. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD USA. RP Krymskii, AM (reprint author), Rostov Don State Univ, Space Phys Dept, Rostov On Don 344000, Russia. NR 48 TC 2 Z9 2 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 2000 VL 92 IS 3-4 BP 535 EP 564 DI 10.1023/A:1005206515578 PG 30 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 362WM UT WOS:000089801300002 ER PT J AU Wang, WF Stevenson, A Reuter, DC Sirota, JM AF Wang, WF Stevenson, A Reuter, DC Sirota, JM TI Absolute band intensities in the nu(19)/nu(23) (530 cm(-1)) and nu(7) (777 cm(-1)) bands of acetone ((CH3)(2)CO) from 232 to 295 K SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article DE acetone (CH3)(2)CO spectra; absolute band intensities; infrared; temperature dependence ID UPPER TROPOSPHERE; HYDROGEN RADICALS; STRATOSPHERE; FATE AB Absolute band intensities of acetone ((CH3)(2)CO) in the v(19)/v(23) and v(7) band systems near 530 and 777 cm(-1) respectively, were measured at temperatures of 232, 262 and 295 K, using a Fourier transform infrared (FTIR) spectrometer. No evident temperature dependence for the band intensities was observed. The dipole moments and the fundamental band intensities were derived in the harmonic oscillator approximation. The results are useful for the spectroscopic retrieval of acetone concentrations in the upper atmosphere. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21250 USA. NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Greenbelt, MD 20771 USA. Univ Alabama, Ctr Space Plasma Aeron & Astrophys Res, Huntsville, AL 35899 USA. RP Wang, WF (reprint author), Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, 1000 Hilltop Circle, Baltimore, MD 21250 USA. NR 20 TC 3 Z9 3 U1 0 U2 1 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 MAY PY 2000 VL 56 IS 6 BP 1111 EP 1116 DI 10.1016/S1386-1425(99)00208-5 PG 6 WC Spectroscopy SC Spectroscopy GA 310JJ UT WOS:000086822500007 PM 10845539 ER PT J AU Klimeck, G Bowen, RC Boykin, TB Cwik, TA AF Klimeck, G Bowen, RC Boykin, TB Cwik, TA TI sp3s* tight-binding parameters for transport simulations in compound semiconductors SO SUPERLATTICES AND MICROSTRUCTURES LA English DT Article; Proceedings Paper CT 3rd International Workshop on Surgaces and Interfaces in Mesoscopic Devices (SIMD 99) CY DEC 06-10, 1999 CL MAUI, HAWAII SP USN, Off Res, Univ Illinois, Beckman Inst DE sp3s*tight-binding; genetic algorithm; effective mass; parametrization; III-V material; GaAs; InAs; AlAs; GaP; InP; AlP; GaSb; InSb; AlSb AB A genetic algorithm approach is used to fit orbital interaction energies of sp3s* tight binding models for the nine binary compound semiconductors consistent of Ga, Al, In and As, P, Sb at room temperature. The new parameters are optimized to reproduce the bandstructure relevant to carrier transport in the lowest conduction band and the highest three valence bands. The accuracy of the other bands is sacrificed for the better reproduction of the effective masses in the bands of interest. Relevant band edges are reproduced to within a few meV and the effective masses deviate from the experimental values typically by less than 10%. (C) 2000 Academic Press. C1 CALTECH, Jet Prop Lab, ECE Dept, Pasadena, CA 91109 USA. Univ Alabama, Huntsville, AL 35899 USA. CALTECH, Jet Prop Lab, LICOS, Pasadena, CA 91109 USA. RP Klimeck, G (reprint author), CALTECH, Jet Prop Lab, ECE Dept, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Klimeck, Gerhard/A-1414-2012 OI Klimeck, Gerhard/0000-0001-7128-773X NR 6 TC 72 Z9 72 U1 1 U2 10 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0749-6036 J9 SUPERLATTICE MICROST JI Superlattices Microstruct. PD MAY-JUN PY 2000 VL 27 IS 5-6 BP 519 EP 524 DI 10.1006/spmi.2000.0862 PG 6 WC Physics, Condensed Matter SC Physics GA 340AR UT WOS:000088511400042 ER PT J AU Ricca, A AF Ricca, A TI Reactivity of CFn (n=1-3) species with a silica surface SO SURFACE SCIENCE LA English DT Article DE clusters; density functional calculations; silicon oxides; surface chemical reaction ID EXACT EXCHANGE; RADICALS AB The trends in reactivity of CFn neutrals with a silica surface are studied using two different cluster models. CF appears to be the most reactive species. The energetics, the activation energies, and the forward reaction rates are computed for two reactions involving the Si-O bond breaking. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Ricca, A (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 16 TC 1 Z9 1 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0039-6028 J9 SURF SCI JI Surf. Sci. PD MAY 1 PY 2000 VL 452 IS 1-3 BP 117 EP 124 DI 10.1016/S0039-6028(00)00307-1 PG 8 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA 310JE UT WOS:000086822100014 ER PT J AU Dubovik, O Smirnov, A Holben, BN King, MD Kaufman, YJ Eck, TF Slutsker, I AF Dubovik, O Smirnov, A Holben, BN King, MD Kaufman, YJ Eck, TF Slutsker, I TI Accuracy assessments of aerosol optical properties retrieved from Aerosol Robotic Network (AERONET) Sun and sky radiance measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SCATTERING PHASE FUNCTION; SIZE DISTRIBUTION; TROPOSPHERIC AEROSOLS; BRIGHTNESS MEASUREMENTS; REFRACTIVE-INDEX; DATA INVERSION; SCAR-B; PARTICLES; APPROXIMATION; ABSORPTION AB Sensitivity studies are conducted regarding aerosol optical property retrieval from radiances measured by ground-based Sun-sky scanning radiometers of the Aerosol Robotic Network (AERONET). These studies focus on testing a new inversion concept for simultaneously retrieving aerosol size distribution, complex refractive index, and single-scattering albedo from spectral measurements of direct and diffuse radiation. The perturbations of the inversion resulting from random errors, instrumental offsets, and known uncertainties in the atmospheric radiation model are analyzed. Sun or sky channel miscalibration, inaccurate azimuth angle pointing during sky radiance measurements, and inaccuracy in accounting for surface reflectance are considered as error sources. The effects of these errors on the characterization of three typical and optically distinct aerosols with bimodal size distributions (weakly absorbing water-soluble aerosol, absorbing biomass-burning aerosol, and desert dust) are considered. The aerosol particles are assumed in the retrieval to be polydispersed homogeneous spheres with the same complex refractive index. Therefore we also examined how inversions with such an assumption bias the retrievals in the case of nonspherical dust aerosols and in the case of externally or internally mixed spherical particles with different refractive indices. The analysis shows successful retrieval of all aerosol characteristics (size distribution, complex refractive index, and single-scattering albedo), provided the inversion includes the data combination of spectral optical depth together with sky radiances in the full solar almucantar (with angular coverage of scattering angles up to 100 degrees or more). The retrieval accuracy is acceptable for most remote sensing applications even in the presence of rather strong systematic or random uncertainties in the measurements. The major limitations relate to the characterization of low optical depth situations for all aerosol types, where high relative errors may occur in the direct radiation measurements of aerosol optical depth. Also, the results of tests indicate that a decrease of angular coverage of scattering (scattering angles of 75 degrees or less) in the sky radiance results in the loss of practical information about refractive index. Accurate azimuth angle pointing is critical for the characterization of dust. Scattering by nonspherical dust particles requires special analysis, whereby approximation of the aerosol by spheres allows us to derive single-scattering albedo by inverting spectral optical depth together with sky radiances in the full solar almucantar. Inverting sky radiances measured in the first 40 degrees scattering angle only, where nonspherical effects are minor, results in accurate retrievals of aerosol size distributions of nonspherical particles. C1 NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. NASA, Goddard Space Flight Ctr, Earth Sci Directorate, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Lab Atmospheres, Greenbelt, MD 20771 USA. Raytheon Co, ITSS, Lanham, MD USA. RP Dubovik, O (reprint author), NASA, Goddard Space Flight Ctr, Terr Phys Lab, Code 923, Greenbelt, MD 20771 USA. EM dubovik@spamer.gsfc.nasa.gov RI Dubovik, Oleg/A-8235-2009; Smirnov, Alexander/C-2121-2009; King, Michael/C-7153-2011; ECK, THOMAS/D-7407-2012 OI Dubovik, Oleg/0000-0003-3482-6460; Smirnov, Alexander/0000-0002-8208-1304; King, Michael/0000-0003-2645-7298; NR 47 TC 806 Z9 858 U1 6 U2 70 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 2000 VL 105 IS D8 BP 9791 EP 9806 DI 10.1029/2000JD900040 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 307ND UT WOS:000086658600004 ER PT J AU Hartley, WS Hobbs, PV Ross, JL Russell, PB Livingston, JM AF Hartley, WS Hobbs, PV Ross, JL Russell, PB Livingston, JM TI Properties of aerosols aloft relevant to direct radiative forcing off the mid-Atlantic coast of the United States SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SIZE-DISTRIBUTION; NATIONAL-PARK; NEPHELOMETER; ABSORPTION; EXTINCTION; DROPLETS; TARFOX AB Comparisons are presented of ambient aerosol optical depths (AOD) derived from airborne in situ measurements of aerosol properties and from Sun photometer measurements off the mideastern seaboard of the United States in July 1996. At 450 nm the Sun photometer measurements of AOD were greater than the in situ measurements by, on average, (12 +/- 5)%. Possible reasons for this difference are discussed. Comparisons of Angstrom coefficients for the ambient aerosol, based on in situ and Sun photometer measurements, are presented, as well as estimates of the ambient aerosol single-scattering albedo. At a wavelength of 550 nm, the mean value of the ambient single-scattering albedo was (0.95 +/- 0.03). Also compared are various optical properties of the dry aerosol derived from airborne in situ measurements with values calculated from a model of the dry aerosol. At a wavelength of 550 nm, measurements and calculations of the total light scattering and light backscattering coefficients for the dry aerosol agree, on average, to within (23 +/- 2)% and (8 +/- 2)%. The calculated and measured dry aerosol absorption coefficients at 535 nm are in agreement for an assumed value of the mass absorption efficiency for the black carbon content of the dry aerosol of 14 m(2) g(-1). C1 Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SRI Int, Menlo Pk, CA 94025 USA. RP Hartley, WS (reprint author), Univ Washington, Dept Atmospher Sci, Box 351640, Seattle, WA 98195 USA. EM seth@atmos.washington.edu; phobbs@atmos.washington.edu; John.Ross2@PSS.Boeing.com; prussell@mail.arc.nasa.gov; jlivingston@mail.arc.nasa.gov NR 34 TC 45 Z9 45 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 2000 VL 105 IS D8 BP 9859 EP 9885 DI 10.1029/1999JD900844 PG 27 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 307ND UT WOS:000086658600009 ER PT J AU Smirnov, A Holben, BN Dubovik, O O'Neill, NT Remer, LA Eck, TF Slutsker, I Savoie, D AF Smirnov, A Holben, BN Dubovik, O O'Neill, NT Remer, LA Eck, TF Slutsker, I Savoie, D TI Measurement of atmospheric optical parameters on US Atlantic coast sites, ships, and Bermuda during TARFOX SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MARINE BOUNDARY-LAYER; AEROSOL; OCEAN; DEPTH AB The Aerosol Robotic Network (AERONET) of automatic Sun/sky radiometers collected data on U.S. Atlantic coast sites, ships, and Bermuda in 1996 during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). Spatial and temporal analysis of Sun photometry data was supported by synoptic analysis of air mass evolution. The spatial distribution of aerosol optical depth is presented. In several cases the aerosol size distributions deduced from sky almucantar measurements and solar disk attenuation measurements at the various coastal sites yielded similar results within the same air masses. Ship-based measurements in the Atlantic Ocean showed significant maritime aerosol optical property variations which for the most part could be attributed to the influence of continental sources and Saharan dust events. The Bermuda data (optical depths and;Angstrom parameter values) illustrated changes in atmospheric optical properties for various air masses and trajectories. Almost no correlation was observed between aerosol optical depth and water vapor content when the data from all stations and ship measurements were considered together. In the case of individual stations or ship transects, different degrees of correlation could be observed. In continental conditions on the east coast, optical depth and water vapor are well correlated, while in a maritime environment, optical depth can be relatively small despite high water vapor contents. C1 NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. Univ Sherbrooke, Ctr Applicat & Rech Teledetect, Sherbrooke, PQ J1K 2R1, Canada. Raychem ITS Corp, Lanham, MD USA. Univ Miami, Div Marine & Atmospher Chem, Gainesville, FL 32601 USA. RP Smirnov, A (reprint author), NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Code 923, Greenbelt, MD 20771 USA. EM asmirnov@spamer.gsfc.nasa.gov 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 23 TC 43 Z9 43 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 2000 VL 105 IS D8 BP 9887 EP 9901 DI 10.1029/1999JD901067 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 307ND UT WOS:000086658600010 ER PT J AU Ismail, S Browell, EV Ferrare, RA Kooi, SA Clayton, MB Brackett, VG Russell, PB AF Ismail, S Browell, EV Ferrare, RA Kooi, SA Clayton, MB Brackett, VG Russell, PB TI LASE measurements of aerosol and water vapor profiles during TARFOX SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MID-ATLANTIC COAST; LIDAR MEASUREMENTS; OPTICAL-PROPERTIES; ERROR ANALYSIS; UNITED-STATES; AIRBORNE; SENSITIVITY; RETRIEVAL; REGION; DEPTH AB The Lidar Atmospheric Sensing Experiment (LASE) was operated autonomously from the NASA high-altitude ER-2 aircraft on nine flights during July 1.0-26, 1996, as part of the Tropospheric Aerosol Radiative Forcing Observational Experiment(TARFOX). LASE measured high-resolution profiles of water vapor and aerosols in regions of urban haze plumes over the U.S. eastern seaboard. Real-time LASE aerosol measurements were used to guide the in situ aircraft to sample haze layers. In this paper the vertical and horizontal distributions of aerosol backscatter measured by LASE are presented along with the temporal evolution of the haze layers. The aerosol backscatter data also identify the presence of gradients in the aerosol plumes, the presence of low-altitude clouds, and optically thin cirrus. This information is useful for many of the radiometeric observations made during TARFOX and can help explain observational differences among ground, airborne, and satellite observations. An iterative procedure is discussed which was used to invert lidar data to retrieve aerosol scattering ratios, extinction, and total optical depths from the LASE measurements. The sensitivity of these retrievals to assumed parameters is discussed and the results of retrievals are also compared to the well-known Bernoulli method. LASE water vapor measurements were made across the entire troposphere using a three "line pair" method to cover the range of water vapor mixing ratio from <0.01 g/kg near the tropopause to similar to 20 g/kg near the surface in a single aircraft pass over the experiment region. These measurements also show two-dimensional distributions of large spatial gradients in water vapor in the lower and upper troposphere. These observations are useful in the calculation of IR radiation fields and relative humidity fields, since relative humidity has a strong influence on the growth of aerosols and their scattering properties. Water vapor profiles, aerosol scattering ratios, aerosol extinction coefficients and aerosol optical depths were derived using the methodology presented in this paper from LASE measurements during TARFOX. These measurements are compared with other in situ and remote measurements during TARFOX in the companion papers [Ferrare et al., this issue (a, b)]. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. NASA, Langley Res Ctr, SAIC, Hampton, VA 23665 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Ismail, S (reprint author), NASA, Langley Res Ctr, MS 401A,Bldg 1250,Room 136B, Hampton, VA 23681 USA. EM s.ismail@larc.nasa.gov NR 32 TC 15 Z9 15 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 2000 VL 105 IS D8 BP 9903 EP 9916 DI 10.1029/1999JD901198 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 307ND UT WOS:000086658600011 ER PT J AU Ferrare, R Ismail, S Browell, E Brackett, V Clayton, M Kooi, S Melfi, SH Whiteman, D Schwemmer, G Evans, K Russell, P Livingston, J Schmid, B Holben, B Remer, L Smirnov, A Hobbs, PV AF Ferrare, R Ismail, S Browell, E Brackett, V Clayton, M Kooi, S Melfi, SH Whiteman, D Schwemmer, G Evans, K Russell, P Livingston, J Schmid, B Holben, B Remer, L Smirnov, A Hobbs, PV TI Comparison of aerosol optical properties and water vapor among ground and airborne lidars and Sun photometers during TARFOX SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MID-ATLANTIC COAST; RAMAN LIDAR; UNITED-STATES; TROPOSPHERIC AEROSOL; EXTINCTION; BACKSCATTERING; SUNPHOTOMETER; INVERSION; RATIO AB We compare aerosol optical thickness (AOT) and precipitable water vapor (PWV) measurements derived from ground and airborne lidars and Sun photometers during the Tropospheric Aerosol Radiative Forcing Observational Experiment. Such comparisons are important to verify the consistency between various remote sensing measurements before employing them in any assessment of the impact of aerosols on the global radiation balance. Total scattering ratio and extinction profiles measured by the ground-based NASA Goddard Space Flight Center scanning Raman Iidar system, which operated from Wallops Island, Virginia (37.86 degrees N, 75.51 degrees W), are compared with those measured by the Lidar Atmospheric Sensing Experiment (LASE) airborne lidar system aboard the NASA ER-2 aircraft. Bias and root-mean-square differences indicate that these measurements generally agreed within about 10%. Aerosol extinction profiles and estimates of AOT are derived from both lidar measurements using a value for the aerosol extinction/ backscattering ratio S-a = 60 sr for the aerosol extinction/backscattering ratio, which was determined from the Raman lidar measurements. The lidar measurements of AOT are found to be generally within 25% of the AOT measured by the NASA Ames Airborne Tracking Sun Photometer (AATS-6). However, during certain periods the lidar and Sun photometer measurements of AOT differed significantly, possibly because of variations in the aerosol physical characteristics (e.g., size, composition) which affect S-a. Estimates of PWV, derived from water vapor mixing ratio profiles measured by LASE, are within 5-10% of PWV derived from the airborne Sun photometer. Aerosol extinction profiles measured by both lidars show that aerosols were generally concentrated in the lowest 2-3 km. C1 NASA, Langley Res Ctr, SAIC, Hampton, VA 23681 USA. Univ Maryland Baltimore Cty, Baltimore, MD 21250 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SRI Int, Menlo Pk, CA 94025 USA. BAER Inst, Moffett Field, CA 94035 USA. NASA, Goddard Space Flight Ctr, SSAI, Greenbelt, MD 20771 USA. Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. RP Ferrare, R (reprint author), NASA, Langley Res Ctr, SAIC, Mail Stop 401A, Hampton, VA 23681 USA. EM r.ferrare@larc.nasa.gov RI Smirnov, Alexander/C-2121-2009 OI Smirnov, Alexander/0000-0002-8208-1304 NR 41 TC 36 Z9 36 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 2000 VL 105 IS D8 BP 9917 EP 9933 DI 10.1029/1999JD901202 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 307ND UT WOS:000086658600012 ER PT J AU Ferrare, R Ismail, S Browell, E Brackett, V Kooi, S Clayton, M Hobbs, PV Hartley, S Veefkind, JP Russell, P Livingston, J Tanre, D Hignett, P AF Ferrare, R Ismail, S Browell, E Brackett, V Kooi, S Clayton, M Hobbs, PV Hartley, S Veefkind, JP Russell, P Livingston, J Tanre, D Hignett, P TI Comparisons of LASE, aircraft, and satellite measurements of aerosol optical properties and water vapor during TARFOX SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MODIS AIRBORNE SIMULATOR; RAMAN LIDAR MEASUREMENTS; SIZE DISTRIBUTION; EXTINCTION; DEPTH; BACKSCATTERING; RETRIEVAL; OCEAN AB We examine aerosol extinction and optical thickness from the Lidar Atmospheric Sensing Experiment (LASE), the in situ nephelometer and absorption photometer on the University of Washington C-131A aircraft, and the NASA Ames Airborne Tracking Sun Photometer (AATS-6) on the C-131A measured during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) over the east coast of the United States in July 1996. On July 17 and 24 the LASE profiles of aerosol extinction and aerosol optical thickness (AOT) had a bias difference of 0.0055 km(-1) (10%) and a root-mean-square difference of 0.026 km(-1) (42%) when compared to corresponding profiles derived from the airborne in situ data when the nephelometer measurements are adjusted to ambient relative humidities. Larger differences for two other days were associated with much smaller aerosol optical thicknesses (July 20) and differences in the locations sampled by the two aircraft (July 26). LASE profiles of AOT are about 10% higher than those derived from the airborne Sun photometer, which in turn are about 10-15% higher than those derived from the airborne in situ measurements. These differences are generally within the error estimates of the various measurements. The LASE measurements of AOT generally agree with AOT derived from both the Along-Track and Scanning Radiometer 2 (ATSR 2) sensor flown on the European Remote Sensing Satellite 2 (ERS-2) and from the Moderate-Resolution Imaging Spectroradiometer (MODIS) airborne simulator (MAS) which flew with LASE on the NASA ER-2 aircraft. Effective particle sizes derived from the MAS data indicate that the LASE retrievals of AOT are valid for effective particle radii less than 0.4 mu m. Variations in the relative humidity derived from the LASE water vapor measurements on July 26 are found to be highly correlated with Variations in the effective particle size derived from the MAS. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. NASA, Langley Res Ctr, SAIC, Hampton, VA 23681 USA. Netherlands Org Appl Sci Res, Phys & Elect Lab, The Hague, Netherlands. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Opt Atmospher Lab, F-59655 Villeneuve Dascq, France. RP Ferrare, R (reprint author), NASA, Langley Res Ctr, Mail Stop 401A,1250, Hampton, VA 23681 USA. EM r.ferrare@larc.nasa.gov NR 21 TC 16 Z9 16 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 2000 VL 105 IS D8 BP 9935 EP 9947 DI 10.1029/1999JD901201 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 307ND UT WOS:000086658600013 ER PT J AU Redemann, J Turco, RP Liou, KN Russell, PB Bergstrom, RW Schmid, B Livingston, JM Hobbs, PV Hartley, WS Ismail, S Ferrare, RA Browell, EV AF Redemann, J Turco, RP Liou, KN Russell, PB Bergstrom, RW Schmid, B Livingston, JM Hobbs, PV Hartley, WS Ismail, S Ferrare, RA Browell, EV TI Retrieving the vertical structure of the effective aerosol complex index of refraction from a combination of aerosol in situ and remote sensing measurements during TARFOX SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SCATTERING SPECTROMETER PROBE; RAMAN LIDAR MEASUREMENTS; MID-ATLANTIC COAST; ANTHROPOGENIC AEROSOLS; RADIATIVE PROPERTIES; UNITED-STATES; BACKSCATTERING; WAVELENGTHS; EXTINCTION AB The largest uncertainty in estimates of the effects of atmospheric aerosols on climate stems from uncertainties in the determination of their microphysical properties, including the aerosol complex index of refraction, which in turn determines their optical properties. A novel technique is used to estimate the aerosol complex index of refraction in distinct vertical layers from a combination of aerosol in situ size distribution and remote sensing measurements during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). In particular, aerosol backscatter measurements using the NASA Langley LASE (Lidar Atmospheric Sensing Experiment) instrument and in situ aerosol size distribution data are utilized to derive vertical profiles of the "effective" aerosol complex index of refraction at 815 nm (i.e., the refractive index that would provide the same backscatter signal in a forward calculation on the basis of the measured in situ particle size distributions for homogeneous, spherical aerosols). A sensitivity study shows that this method yields small errors in the retrieved aerosol refractive indices, provided the errors in the lidar-derived aerosol backscatter are less than 30% and random in nature. Absolute errors in the estimated aerosol refractive indices are generally less than 0.04 for the real part and can be as much as 0.042 for the imaginary part in the case of a 30% error in the lidar-derived aerosol backscatter. The measurements of aerosol optical depth from the NASA Ames Airborne Tracking Sunphotometer (AATS-6) are successfully incorporated into the new technique and help constrain the retrieved aerosol refractive indices. An application of the technique to two TARFOX case studies yields the occurrence of vertical layers of distinct aerosol refractive indices. Values of the estimated complex aerosol refractive index range from 1.33 to 1.45 for the real part and 0.001 to 0.008 for the imaginary part. The methodology devised in this study provides, for the first time, a complete set of vertically resolved aerosol size distribution and refractive index data, yielding the vertical distribution of aerosol optical properties required for the determination of aerosol-induced radiative flux changes. C1 Bay Area Environm Res Inst, San Francisco, CA 94122 USA. Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SRI Int, Menlo Pk, CA 94025 USA. Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Redemann, J (reprint author), Bay Area Environm Res Inst, San Francisco, CA 94122 USA. EM jredemann@mail.arc.nasa.gov NR 35 TC 42 Z9 42 U1 1 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 2000 VL 105 IS D8 BP 9949 EP 9970 DI 10.1029/1999JD901044 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 307ND UT WOS:000086658600014 ER PT J AU Redemann, J Turco, RP Liou, KN Hobbs, PV Hartley, WS Bergstrom, RW Browell, EV Russell, PB AF Redemann, J Turco, RP Liou, KN Hobbs, PV Hartley, WS Bergstrom, RW Browell, EV Russell, PB TI Case studies of the vertical structure of the direct shortwave aerosol radiative forcing during TARFOX SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SENSITIVITY AB The vertical structure of aerosol-induced radiative flux changes in the Earth's troposphere affects local heating rates and thereby convective processes, the formation and lifetime of clouds, and hence the distribution of chemical constituents. We present observationally based estimates of the vertical structure of direct shortwave aerosol radiative forcing for two case studies from the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) which took place on the U.S. east coast in July 1996. The aerosol radiative forcings are computed using the Fu-Liou broadband radiative transfer model. The aerosol optical properties used in the radiative transfer simulations are calculated from independent vertically resolved estimates of the complex aerosol indices of refraction in two to three distinct vertical layers, using profiles:of in situ particle size distributions measured aboard the University of Washington research aircraft. Aerosol single-scattering albedos at 450 nm thus determined range from 0.9 to 0.985, while the asymmetry factor varies from 0.6 to 0.8 The instantaneous shortwave aerosol radiative forcings derived from the optical properties of the aerosols are of the order of -36 W m(-2) at the top of the atmosphere and about -56 W m(-2) at the surface for both case studies. C1 Bary Area Environm Res Inst, San Francisco, CA 94122 USA. Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Redemann, J (reprint author), Bary Area Environm Res Inst, San Francisco, CA 94122 USA. EM jredemann@mail.arc.nasa.gov NR 21 TC 25 Z9 27 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 2000 VL 105 IS D8 BP 9971 EP 9979 DI 10.1029/1999JD901042 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 307ND UT WOS:000086658600015 ER PT J AU Soulen, PF King, MD Tsay, SC Arnold, GT Li, JY AF Soulen, PF King, MD Tsay, SC Arnold, GT Li, JY TI Airborne spectral measurements of surface-atmosphere anisotropy during the SCAR-A, Kuwait oil fire, and TARFOX experiments SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID BIDIRECTIONAL REFLECTANCE; CANOPIES; AEROSOL; SMOKE AB During the SCAR-A, Kuwait Oil Fire Smoke Experiment, and TARFOX deployments, angular distributions of spectral reflectance for various surfaces were measured using the scanning Cloud Absorption Radiometer (CAR) mounted on the nose of the University of Washington C-131A research aircraft. The CAR contains 13 narrowband spectral channels between 0.47 and 2.3 mu m with a 190 degrees scan aperture (5 degrees before zenith to 5 degrees past nadir) and 1 degrees instantaneous field of view. The bidirectional reflectance is obtained by flying a clockwise circular orbit above the surface, resulting in a ground track approximately 3 km in diameter within about 2 min. Spectral bidirectional reflectances of four surfaces are presented: the Great Dismal Swamp in Virginia with overlying haze layer, the Saudi Arabian Desert and the Persian Gulf in the Middle East, and the Atlantic Ocean measured east of Richmond, Virginia. Although the CAR measurements are contaminated by atmospheric effects, results show distinct spectral characteristics for various types of surface-atmosphere systems, including hot spots, limb brightening and darkening, and Sun glint. In addition, the-hemispherical albedo of each surface-atmosphere system is calculated directly by integrating over all high angular-resolution CAR measurements for each spectral channel. Comparing the nadir reflectance with the overall hemispherical albedo of each surface, we find that using nadir reflectances as a surrogate for hemispherical albedo can cause albedos to be underestimated by as much as 95% and overestimated by up to 160%, depending on the type of surface and solar zenith angle. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. SM&A Corp East, Vienna, VA 22180 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Catonsville, MD USA. RP King, MD (reprint author), NASA, Goddard Space Flight Ctr, Code 900, Greenbelt, MD 20771 USA. EM king@climate.gsfc.nasa.gov RI King, Michael/C-7153-2011; Tsay, Si-Chee/J-1147-2014 OI King, Michael/0000-0003-2645-7298; NR 25 TC 17 Z9 17 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 27 PY 2000 VL 105 IS D8 BP 10203 EP 10218 DI 10.1029/1999JD901115 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 307ND UT WOS:000086658600031 ER PT J AU Bauschlicher, CW Zhou, MF Andrews, L AF Bauschlicher, CW Zhou, MF Andrews, L TI A study of the products of the reaction of phosphorus and dioxygen SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID DENSITY-FUNCTIONAL CALCULATIONS; MATRIX INFRARED-SPECTRA; SOLID ARGON; ELECTRON CORRELATION; O-3 MOLECULES; PO2; ABSORPTION; ATOMS; P-2 AB The products of the reaction of laser-ablated red phosphorus and dioxygen have been studied using experiment and theory. The bands at 480.3 and 1273.3 cm(-1), previously attributed to PO3 in the matrix isolation IR experiments, are reassigned to PO3-. Also observed in experiment are PO2, PO2-, P2O, OPOPO, P-4, and higher oxides. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Virginia, Charlottesville, VA 22901 USA. RP Andrews, L (reprint author), NASA, Ames Res Ctr, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 29 TC 13 Z9 13 U1 0 U2 1 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 APR 27 PY 2000 VL 104 IS 16 BP 3566 EP 3571 DI 10.1021/jp993623b PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 329GZ UT WOS:000087900400017 ER PT J AU Hudgins, DM Bauschlicher, CW Allamandola, LJ Fetzer, JC AF Hudgins, DM Bauschlicher, CW Allamandola, LJ Fetzer, JC TI Infrared spectroscopy of matrix-isolated polycyclic aromatic hydrocarbon ions. 5. PAHs incorporating a cyclopentadienyl ring SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID ISOLATED NAPHTHALENE; VIBRATIONAL-SPECTRA; ELECTRONIC-SPECTRA; RADICAL CATIONS; MOLECULES; EMISSION; ANTHRACENE; TETRACENE; PENTACENE; ANIONS AB The matrix-isolation technique has been employed to measure the mid-infrared spectra of the ions of several polycyclic aromatic hydrocarbons whose structures incorporate a cyclopentadienyl ring. These include the cations of fluoranthene (C16H10), benzo[b]fluoranthene, benzo[b]fluoranthene, benzo-[k]fluoranthene, and benzo[k]fluoranthene (all C20H12 isomers), as well as the anions of benzo[a]fluoranthene and benzo[j]fluoranthene. With the exception of fluoranthene, which presented significant theoretical difficulties, the experimental data art: compared to theoretically calculated values obtained using density functional theory (DFT) at the B3LYP/4-31G level. In general, there is good overall agreement between the two data sets, with the positional agreement between the experimentally measured and theoretically predicted bands somewhat better than that associated with their intensities. The results are also consistent with previous experimental studies of polycyclic aromatic hydrocarbon ions. Specifically, in both the cationic and anionic species the strongest ion bands typically cluster in the 1450 to 1300 cm(-1) range, reflecting an order-of-magnitude enhancement in the CC stretching and CH in-plane bending modes between 1600 and 1100 cm(-1) in these species. The aromatic CH out-of-plane bending modes, on the other hand, are usually modestly suppressed (less than or equal to 2x - 5x) in the cations relative to those of the neutral species, with the nonadjacent CH modes most strongly affected. The ionization effect on the analogous anion modes is more varied, with both enhancements and suppressions observed. Finally, while no cation features have been observed in the 3100-2950 cm(-1) aromatic CH stretching region, bands arising from these modes are observed for each of the anions addressed in these studies. This agrees qualitatively with the theoretical calculations which predict that, in stark contrast to the order of magnitude suppression encountered in the cations, the total intensity in these modes is actually enhanced by about a factor of 3 in the anions relative to the neutral species. This is the first time that the CH stretching features of an isolated PAH ion have been observed experimentally. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Chevron Res Co, Richmond, CA 94802 USA. RP Hudgins, DM (reprint author), NASA, Ames Res Ctr, MS 245-6, Moffett Field, CA 94035 USA. NR 43 TC 58 Z9 58 U1 1 U2 11 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 APR 27 PY 2000 VL 104 IS 16 BP 3655 EP 3669 DI 10.1021/jp993940i PG 15 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 329GZ UT WOS:000087900400028 ER PT J AU de Bernardis, P Ade, PAR Bock, JJ Bond, JR Borrill, J Boscaleri, A Coble, K Crill, BP De Gasperis, G Farese, PC Ferreira, PG Ganga, K Giacometti, M Hivon, E Hristov, VV Iacoangeli, A Jaffe, AH Lange, AE Martinis, L Masi, S Mason, PV Mauskopf, PD Melchiorri, A Miglio, L Montroy, T Netterfield, CB Pascale, E Piacentini, F Pogosyan, D Prunet, S Rao, S Romeo, G Ruhl, JE Scaramuzzi, F Sforna, D Vittorio, N AF de Bernardis, P Ade, PAR Bock, JJ Bond, JR Borrill, J Boscaleri, A Coble, K Crill, BP De Gasperis, G Farese, PC Ferreira, PG Ganga, K Giacometti, M Hivon, E Hristov, VV Iacoangeli, A Jaffe, AH Lange, AE Martinis, L Masi, S Mason, PV Mauskopf, PD Melchiorri, A Miglio, L Montroy, T Netterfield, CB Pascale, E Piacentini, F Pogosyan, D Prunet, S Rao, S Romeo, G Ruhl, JE Scaramuzzi, F Sforna, D Vittorio, N TI A flat Universe from high-resolution maps of the cosmic microwave background radiation SO NATURE LA English DT Article ID ANISOTROPY; SUPERNOVAE; EMISSION AB The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73 K cosmic microwave background. Tiny inhomogeneities in the early Universe left their imprint on the microwave background in the form of small anisotropies in its temperature. These anisotropies contain information about basic cosmological parameters, particularly the total energy density and curvature of the Universe. Here we report the first images of resolved structure in the microwave background anisotropies over a significant part of the sky. Maps at four frequencies clearly distinguish the microwave background from foreground emission. We compute the angular power spectrum of the microwave background, and rnd a peak at Legendre multipole I-peak = (197 +/- 6), with an amplitude Delta T-200 = (69 +/- 8) mu K. This is consistent with that expected for cold dark matter models in a flat (euclidean) Universe, as favoured by standard inflationary models. C1 Univ Rome La Sapienza, Dipartimento Fis, I-00185 Rome, Italy. Univ London Queen Mary & Westfield Coll, Dept Phys, London E1 4NS, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Toronto, CITA, Toronto, ON M5S 3H8, Canada. LBNL, NERSC, Berkeley, CA 94720 USA. CNR, IROE, I-50127 Florence, Italy. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. CALTECH, Pasadena, CA 91125 USA. Univ Roma Tor Vergata, Dipartimento Fis, I-00133 Rome, Italy. Univ Oxford, Oxford OX1 3RH, England. Coll France, PCC, F-75231 Paris 05, France. Univ Calif Berkeley, Ctr Particle Astrophys, Berkeley, CA 94720 USA. ENEA, Ctr Ric Frascati, I-00044 Frascati, Italy. Cardiff Univ, Dept Phys & Astron, Cardiff CF2 3YB, S Glam, Wales. Univ Massachusetts, Dept Phys & Astron, Amherst, MA 01003 USA. Univ Toronto, Dept Phys & Astron, Toronto, ON M5S 3H8, Canada. Ist Nazl Geofis, I-00143 Rome, Italy. RP de Bernardis, P (reprint author), Univ Rome La Sapienza, Dipartimento Fis, P A Moro 2, I-00185 Rome, Italy. RI Jaffe, Andrew/D-3526-2009; de Gasperis, Giancarlo/C-8534-2012; Piacentini, Francesco/E-7234-2010; OI de Gasperis, Giancarlo/0000-0003-2899-2171; Piacentini, Francesco/0000-0002-5444-9327; Masi, Silvia/0000-0001-5105-1439; de Bernardis, Paolo/0000-0001-6547-6446; ROMEO, Giovanni/0000-0002-5535-7803; Melchiorri, Alessandro/0000-0001-5326-6003; Hivon, Eric/0000-0003-1880-2733 NR 47 TC 1814 Z9 1817 U1 4 U2 125 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 27 PY 2000 VL 404 IS 6781 BP 955 EP 959 DI 10.1038/35010035 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 309HG UT WOS:000086762000045 ER PT J AU Phelan, BA Goldberg, R Bejda, AJ Pereira, J Hagan, S Clark, P Studholme, AL Calabrese, A Able, KW AF Phelan, BA Goldberg, R Bejda, AJ Pereira, J Hagan, S Clark, P Studholme, AL Calabrese, A Able, KW TI Estuarine and habitat-related differences in growth rates of young-of-the-year winter flounder (Pseudopleuronectes americanus) and tautog (Tautoga onitis) in three northeastern US estuaries SO JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY LA English DT Article DE growth; habitat quality; estuarine quality; juvenile fish; winter flounder; tautog; caging ID JUVENILE SOUTHERN FLOUNDER; EARLY-LIFE-HISTORY; DISSOLVED-OXYGEN; WAQUOIT BAY; NORTH-CAROLINA; NEW-JERSEY; PARALICHTHYS-LETHOSTIGMA; EUTROPHIC ESTUARY; COASTAL WATERS; ULVA-LACTUCA AB Instantaneous growth rates of young-of-the-year winter flounder Pseudopleuronectes americanus (Walbaum) (12.0-60.4 mm standard length, SL) and tautog Tautoga onitis (Linnaeus) (21.4-73.8 mm total length, TL) from three estuarine systems in New Jersey (Great Bay-Little Egg Harbor and Navesink River) and Connecticut (Hammonasset River) were used in an attempt to assess the relative quality of selected nominal habitats. A series of short-term field caging experiments were conducted during 1994 and 1995 in: macroalgae (primarily, Ulva lactuca), eelgrass (Zostera marina), unvegetated areas adjacent to macroalgae and eelgrass and tidal creeks in Spartina dominated marsh. Growth rates varied with habitat, estuary and year. Comparisons across nominal habitats within and among estuaries did not show any one habitat with consistently higher growth, and growth was relatively independent of whether a habitat was vegetated or adjacent to vegetation. The growth rates of winter flounder and tautog from the Hammonasset River were not different among habitats in either year of the study. In the Great Bay-Little Egg Harbor, both winter flounder and tautog had higher growth rates in macroalgae with growth in eelgrass varying significantly between years. Conversely, in the Navesink River both species had higher growth rates in eelgrass. Environmental changes associated with temperature and dissolved oxygen appeared to influence growth rates. Winter flounder growth rate and survival was depressed in tidal marsh creeks in the three estuaries and in vegetated macroalgae habitats in the Navesink River where dissolved oxygen levels were often very low (<2 mg l(-1)) for extended periods. In summary, the growth rates of the young-of-the-year of these two species varied temporally and were dependent on the interaction or both the specific estuary and habitat in which the experiments took place. Further, habitat quality, as defined by relative growth rare, was difficult to evaluate because it can be variable and nominal habitat designations are often not sufficient to define the boundaries of a species habitat requirements. Published by Elsevier Science B.V. C1 James J Howard Marine Sci Lab, Natl Marine Fisheries Serv, Highlands, NJ 07732 USA. Natl Marine Fisheries Serv, Milford Lab, Milford, CT 06460 USA. Rutgers State Univ, Marine Field Stn, Inst Marine & Coastal Sci, Tuckerton, NJ 08087 USA. RP Phelan, BA (reprint author), James J Howard Marine Sci Lab, Natl Marine Fisheries Serv, 74 Magruder Rd, Highlands, NJ 07732 USA. EM beth.phelan@noaa.gov NR 58 TC 103 Z9 104 U1 1 U2 17 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 APR 26 PY 2000 VL 247 IS 1 BP 1 EP 28 DI 10.1016/S0022-0981(99)00184-7 PG 28 WC Ecology; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 300JK UT WOS:000086249700001 ER PT J AU Conrath, BJ Pearl, JC Smith, MD Maguire, WC Christensen, PR Dason, S Kaelberer, MS AF Conrath, BJ Pearl, JC Smith, MD Maguire, WC Christensen, PR Dason, S Kaelberer, MS TI Mars Global Surveyor Thermal Emission Spectrometer (TES) observations: Atmospheric temperatures during aerobraking and science phasing SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID GENERAL-CIRCULATION MODEL; GREAT DUST STORMS; MARTIAN ATMOSPHERE; INFRARED SPECTROSCOPY; PRESSURE CYCLE; SIMULATION; MARINER-9; SURFACE AB Between September 1997, when the Mars Global Surveyor spacecraft arrived at Mars, and September 1998, when the final aerobraking phase of the mission began, the Thermal Emission Spectrometer has acquired an extensive data set spanning approximately half of a Martian year. Nadir-viewing spectral measurements from this data set within the 15 mu m CO2 absorption band are inverted to obtain atmospheric temperature profiles from the surface up to about the 0.1 mbar level. The computational procedure used to retrieve the temperatures is presented. Mean meridional cross sections of thermal structure are calculated for periods of time near Northern Hemisphere fall equinox, winter solstice, and spring equinox as well as for a time interval immediately following the onset of the Noachis Terra dust storm. Gradient thermal wind cross sections are calculated from the thermal structure. Regions of possible wave activity are identified using cross sections of rms temperature deviations from the mean. Results from both near-equinox periods show some hemispheric asymmetry with peak eastward thermal winds in the north about twice the magnitude of those in the south. The results near solstice show an intense circumpolar vortex at high northern latitudes and waves associated with the vortex jet core. Warming of the atmosphere aloft at northern midlatitudes suggests the presence of a strong cross-equatorial Hadley circulation. Although the Noachis dust storm did not become global in scale, strong perturbations to the atmospheric structure are found, including an enhanced temperature maximum aloft at high northern latitudes resulting from intensification of the Hadley circulation. TES results for the various seasonal conditions are compared with published results from Mars general circulation models, and generally, good qualitative agreement is found. C1 Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. Solutio Internet Guides, Laurel, MD 20724 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Raytheon ITSS, Lanham, MD 20706 USA. RP Conrath, BJ (reprint author), Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. RI Smith, Michael/C-8875-2012 NR 27 TC 135 Z9 135 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 2000 VL 105 IS E4 BP 9509 EP 9519 DI 10.1029/1999JE001095 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 306HG UT WOS:000086590800008 ER PT J AU Banfield, D Conrath, B Pearl, JC Smith, MD Christensen, P AF Banfield, D Conrath, B Pearl, JC Smith, MD Christensen, P TI Thermal tides and stationary waves on Mars as revealed by Mars Global Surveyor thermal emission spectrometer SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MARTIAN ATMOSPHERE AB Atmospheric temperature retrievals from thermal emission spectrometer (TES) observed radiances make possible the most complete separation of the constituent wave modes evident in Mars atmosphere to date. We use all of the data from the first aerobraking period as well as the science phasing orbits, which affords good sampling of the diurnal tides and stationary waves. TES retrievals of atmospheric temperature on a grid of pressure levels are the fundamental data set in this study. We then fit this data to selected Fourier modes in longitude and time for altitude, latitude, and L-s bins. From this we have identified the amplitudes and phases of the diurnal and semidiurnal tides, the first few (gravest) stationary waves, and a few modes which arise because of couplings between sun-fixed tides and topography. We also retrieve estimates of the zonal and time of day mean temperature meridional cross sections and their rates of change. The zonal and time of day mean temperature meridional cross sections agree with those of Conrath et al. [this issue] to within 1 K where we can reliably retrieve this mode (90 degrees S to similar to 20 degrees S). Heating rates of up to 2.4 K/sol were observed around three scale heights above 60 degrees S-90 degrees S during the L-s = 310 degrees - 320 degrees dust storm. Diurnal tide amplitudes of greater than 8 K were observed during the Noachis ard L-s = 310 degrees - 320 degrees dust storms. From L-s = 255 degrees - 285 degrees an unexplained phase reversal at two scale heights was observed in the diurnal tide from 60 degrees S-80 degrees S. Convective penetration above the unstable boundary layer may explain anomalous (180 degrees out of phase with the sun) diurnal tide phases between 0.5 and one scale height above the subsolar point. Semidiurnal tides are of order 2 K throughout the southern extratropics. A stationary mode of wavenumber one was observed with amplitude 1-4 K in the southern extratropics. Topographically coupled tidal modes were also quantified. C1 Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Banfield, D (reprint author), Cornell Univ, Dept Astron, 420 Space Sci, Ithaca, NY 14853 USA. RI Smith, Michael/C-8875-2012; OI Banfield, Don/0000-0003-2664-0164 NR 13 TC 41 Z9 42 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 2000 VL 105 IS E4 BP 9521 EP 9537 DI 10.1029/1999JE001161 PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 306HG UT WOS:000086590800009 ER PT J AU Smith, MD Pearl, JC Conrath, BJ Christensen, PR AF Smith, MD Pearl, JC Conrath, BJ Christensen, PR TI Mars Global Surveyor Thermal Emission Spectrometer (TES) observations of dust opacity during aerobraking and science phasing SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MARTIAN ATMOSPHERE; INFRARED-SPECTROSCOPY; SURFACE-COMPOSITION; PHYSICAL-PROPERTIES; MARINER-9; VIKING; STORMS; MISSION; MAPPER; CAMERA AB The Mars Global Surveyor (MGS) arrived at Mars in September 1997 near Mars's southern spring equinox and has now provided monitoring of conditions in the Mars atmosphere for more than half a Mars year. The large majority of the spectra taken by the Thermal Emission Spectrometer (TES) are in a nadir geometry (downward looking mode) where Mars is observed through the atmosphere. Most of these contain the distinct spectral signature of atmospheric dust. For these nadir-geometry spectra we retrieve column-integrated infrared aerosol (dust) opacities. TES observations during the aerobraking and science-phasing portions of the MGS mission cover the seasonal range L-s = 184 degrees-28 degrees. Excellent spatial coverage was obtained in the southern hemisphere. Northern hemisphere coverage is generally limited to narrow strips taken during the periapsis pass but is still very valuable. At the beginning of the mission the 9-mu m dust opacity at midsouthern latitudes was low (0.15-0.25). As the season advanced through southern spring and into summer, TES observed several regional dust storms (including the Noachis dust storm of November 1997) where peak 9-mu m dust opacities approached or exceeded unity, as well as numerous smaller local storms. Both large and small dust storms exhibited significant changes in both spatial coverage and intensity over a timescale of a day. Throughout southern spring and summer the region at the edge of the retreating southern seasonal polar ice cap was observed to be consistently more dusty than other latitudes. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. RP Smith, MD (reprint author), NASA, Goddard Space Flight Ctr, Code 693, Greenbelt, MD 20771 USA. RI Smith, Michael/C-8875-2012 NR 41 TC 90 Z9 91 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD APR 25 PY 2000 VL 105 IS E4 BP 9539 EP 9552 DI 10.1029/1999JE001097 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 306HG UT WOS:000086590800010 ER PT J AU Clancy, RT Sandor, BJ Wolff, MJ Christensen, PR Smith, MD Pearl, JC Conrath, BJ Wilson, RJ AF Clancy, RT Sandor, BJ Wolff, MJ Christensen, PR Smith, MD Pearl, JC Conrath, BJ Wilson, RJ TI An intercomparison of ground-based millimeter, MGS TES, and Viking atmospheric temperature measurements: Seasonal and interannual variability of temperatures and dust loading in the global Mars atmosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MARTIAN ATMOSPHERE; MODEL; MARINER-9; PHOBOS; STORMS; MICROWAVE; SURVEYOR; APHELION; BEHAVIOR; CLIMATE AB During the period October 1997 to September 1999 we obtained and analyzed over 100 millimeter-wave observations of Mars atmospheric CO line absorption for atmospheric temperature profiles. These measurements extend through one full Mars year (solar longitudes L-S of 190 degrees in 1997 to 180 degrees in 1999) and coincide with atmospheric temperature profile and dust column measurements from the Thermal Emission Spectrometer (TES) experiment on board the Mars Global Surveyor (MGS) spacecraft. A comparison of Mars atmospheric temperatures retrieved by these distinct methods provides the first opportunity to place the long-term (1982-1999) millimeter retrievals of Mars atmospheric temperatures within the context of contemporaneous, spatially mapped spacecraft observations. Profile comparisons of 0-30 km altitude atmospheric temperatures retrieved with the two techiques agree typically to within the 5 K calibration accuracy of the millimeter observations. At the 0.5 mbar pressure level (similar to 25 km altitude) the 30 degrees N/30 degrees S average for TES infrared temperatures and the disk-averaged millimeter temperatures are also well correlated in their seasonal and dust-storm-related variations over the 1997-1999 period. This period includes the Noachis Terra regional dust storm, which led to very abrupt heating (similar to 15 K at 0.5 mbar) of the global Mars atmosphere at L-S = 224 degrees in 1997 [Christensen et al., 1998; Conrath et al., this issue; Smith et al., this issue]. Much colder (10-20 It) global atmospheric temperatures were observed during the 1997 versus 1977 perihelion periods (L-S = 200 degrees-330 degrees), consistent with the much (2 to 8 times) lower global dust loading of the atmosphere during the 1997 perihelion dust storm season versus the Viking period of the 1977a,b storms. The 1998-1999 Mars atmosphere revealed by both the millimeter and TES observations is also 10-15 K colder than presented by the Viking climatology during the aphelion season (L-S = 0 degrees-180 degrees, northern spring/summer) of Mars. We reassess the observational basis of the Viking dusty-warm climatology for this season to conclude that the global aphelion atmosphere of Mars is colder, less dusty, and cloudier than indicated by the established Viking climatology even for the Viking period. We also conclude that Mars atmospheric temperatures exhibit their most significant interannual variations during the perihelion dust storm season (10-20 K for L-S = 200 degrees-340 degrees) and during the post-aphelion northern summer season (5-10 K for L-S = 100 degrees-200 degrees). C1 Space Sci Inst, Boulder, CO 80303 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Natl Ctr Atmospher Res, Boulder, CO 80303 USA. NOAA, Geophys Fluid Dynam Lab, Princeton, NJ 08542 USA. RP Clancy, RT (reprint author), Space Sci Inst, 3100 Marine St,Suite A353, Boulder, CO 80303 USA. RI Smith, Michael/C-8875-2012 NR 58 TC 213 Z9 215 U1 1 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 2000 VL 105 IS E4 BP 9553 EP 9571 DI 10.1029/1999JE001089 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 306HG UT WOS:000086590800011 ER PT J AU Bandfield, JL Christensen, PR Smith, MD AF Bandfield, JL Christensen, PR Smith, MD TI Spectral data set factor analysis and end-member recovery: Application to analysis of Martian atmospheric particulates SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID THERMAL EMISSION; INFRARED-SPECTROSCOPY; MULTISPECTRAL IMAGES; MIXTURE ANALYSIS; MARINER-9; ABUNDANCE; MARS; SPECTROMETER; SURFACES; VIKING AB A method is described that uses target transformation factor analysis techniques to determine the number of independently variable components and recover the spectral end-members present in a set of mixed spectra. These techniques were tested on two sets of synthetic spectral mixtures and several subsets of Thermal Emission Spectrometer (TES) data. In both synthetic mixture sets, the correct numbers of components were determined, and the original spectral end-members were accurately recovered. An initial application of this method was used with several subsets of TES apparent emissivity spectra that contain only minor surface spectral components. This method has demonstrated that the spectra can be modeled using linear combinations of three spectral end-members: atmospheric dust (with atmospheric gas absorptions that vary in unison with the dust shape), water ice cloud, and blackbody. The atmospheric dust and water ice cloud spectral shapes were recovered from several orbits with a wide variety of atmospheric dust opacities during the southern spring and summer seasons. The atmospheric dust spectral shape is nearly constant except for the relative contribution of atmospheric gasses that vary in unison with the dust shape. The water ice spectral shape is also constant with the exception of a small shift in the position of the similar to 800 cm(-1) absorption that was observed during a period of high opacity. C1 Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Bandfield, JL (reprint author), Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. RI Smith, Michael/C-8875-2012 NR 39 TC 94 Z9 96 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 2000 VL 105 IS E4 BP 9573 EP 9587 DI 10.1029/1999JE001094 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 306HG UT WOS:000086590800012 ER PT J AU Smith, MD Bandfield, JL Christensen, PR AF Smith, MD Bandfield, JL Christensen, PR TI Separation of atmospheric and surface spectral features in Mars Global Surveyor Thermal Emission Spectrometer (TES) spectra SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID SPECTROSCOPY AB We present two algorithms for the separation of spectral features caused by atmospheric and surface components in Thermal Emission Spectrometer (TES) data. One algorithm uses radiative transfer and successive least squares fitting to find spectral shapes first for atmospheric dust, then for water-ice aerosols, and then, finally, for surface emissivity. A second independent algorithm uses a combination of factor analysis, target transformation, and deconvolution to simultaneously find dust, water ice, and surface emissivity spectral shapes. Both algorithms have been applied to TES spectra, and both find very similar atmospheric and surface spectral shapes. For TES spectra taken during aerobraking and science phasing periods in nadir-geometry these two algorithms give meaningful and usable surface emissivity spectra that can be used for mineralogical identification. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. RP Smith, MD (reprint author), NASA, Goddard Space Flight Ctr, Code 693, Greenbelt, MD 20771 USA. RI Smith, Michael/C-8875-2012 NR 23 TC 110 Z9 111 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 2000 VL 105 IS E4 BP 9589 EP 9607 DI 10.1029/1999JE001105 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 306HG UT WOS:000086590800013 ER PT J AU Christensen, PR Bandfield, JL Smith, MD Hamilton, VE Clark, RN AF Christensen, PR Bandfield, JL Smith, MD Hamilton, VE Clark, RN TI Identification of a basaltic component on the Martian surface from Thermal Emission Spectrometer data SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID SNC METEORITES; MARS; REFLECTANCE; VIKING; DUST; SPECTROSCOPY; CALIFORNIA; SPECTRA; IMAGES; ALBEDO AB The Mars Global Surveyor Thermal Emission Spectrometer (TES) instrument collected 4.8 x 10(6) spectra of Mars during the initial aerobraking and science-phasing periods of the mission (September 14, 1997, through April 29, 1998). Two previously developed atmosphere-removal models were applied to data from Cimmeria Terra (25 degrees S, 213 degrees W). The surface spectra derived for these two models agree well, indicating that the surface and atmosphere emission can be separated and that the exact atmosphere-removal model used has little effect on the derived surface composition. The Cimmeria spectra do not match terrestrial high-silica igneous rocks (granite and rhyolite), ultramafic igneous rocks, limestone, or quartz- and clay-rich sandstone and siltstone. A particulate (sand-sized) sample of terrestrial flood basalt does provide an excellent match in both spectral shape and band depth to the Cimmeria spectrum over the entire TES spectral range. No unusual particle size effects are required to account for the observed spectral shape and depth. The implied grain size is consistent with the thermal inertia and albedo of this region, which indicate a sand-sized surface with little dust. The identification of basalt is consistent with previous indications of pyroxene and basalt-like compositions from visible/near-infrared and thermal-infrared spectral measurements. A linear spectral deconvolution model was applied to both surface-only Cimmeria spectra using a library of 60 minerals to determine the composition and abundance of the component minerals. Plagioclase feldspar (45%; 53%) and clinopyroxene (26%; 19%) were positively identified above an estimated detection threshold of 10-15% for these minerals. The TES observations provide the first identification of feldspars on Mars. The best fit to the Mars data includes only clinopyroxene compositions; no orthopyroxene compositions are required to match the Cimmeria spectra. Olivine (12%; 12%) and sheet silicate (15%; 11%) were identified with lower confidence. Carbonates, quartz, and sulfates were not identified in Cimmeria at detection limits of similar to 5, 5, and 10%, respectively. Their presence elsewhere, however, remains open. The Cimmeria spectra are not well matched by any one SNC meteorite spectrum, indicating that this region is not characterized by a single SNC lithology. The occurrence of unweathered feldspar and pyroxene in Cimmeria, together with the inferred presence of pyroxene and unweathered basalts in other dark regions and at the Viking and Pathfinder landing sites, provides evidence that extensive global chemical weathering of materials currently exposed on the Martian surface has not occurred. C1 Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. US Geol Survey, Denver, CO 80225 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Christensen, PR (reprint author), Arizona State Univ, Dept Geol, Campus Box 871404, Tempe, AZ 85287 USA. RI Smith, Michael/C-8875-2012 NR 55 TC 186 Z9 188 U1 4 U2 18 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 2000 VL 105 IS E4 BP 9609 EP 9621 DI 10.1029/1999JE001127 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 306HG UT WOS:000086590800014 ER PT J AU Christensen, PR Bandfield, JL Clark, RN Edgett, KS Hamilton, VE Hoefen, T Kieffer, HH Kuzmin, RO Lane, MD Malin, MC Morris, RV Pearl, JC Pearson, R Roush, TL Ruff, SW Smith, MD AF Christensen, PR Bandfield, JL Clark, RN Edgett, KS Hamilton, VE Hoefen, T Kieffer, HH Kuzmin, RO Lane, MD Malin, MC Morris, RV Pearl, JC Pearson, R Roush, TL Ruff, SW Smith, MD TI Detection of crystalline hematite mineralization on Mars by the Thermal Emission Spectrometer: Evidence for near-surface water SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID SPECTRAL PROPERTIES; GOETHITE; VIKING; SPECTROSCOPY; MOSSBAUER; MINERALS; DEPOSITS; BRAZIL; OXIDES; CLOUD AB The Thermal Emission Spectrometer (TES) instrument on the Mars Global Surveyor (MGS) mission has discovered a remarkable accumulation of crystalline hematite (alpha-Fe2O3) that covers an area with very sharp boundaries approximately 350 by 350-750 km in size centered near 2 degrees S latitude between 0 degrees and 5 degrees W longitude (Sinus Meridiani). Crystalline hematite is uniquely identified by the presence of fundamental vibrational absorption features centered near 300, 450, and >525 cm(-1) and by the absence of silicate fundamentals in the 1000 cm(-1) region. Spectral features resulting from atmospheric CO2, dust, and water ice were removed using a radiative transfer model. The spectral properties unique to Sinus Meridiani were emphasized by removing the average spectrum of the surrounding region. The depth and shape of the hematite fundamental bands show that the hematite is crystalline and relatively coarse grained (>5-10 mu m). Diameters up to and greater than hundreds of micrometers are permitted within the instrumental noise and natural variability of hematite spectra. Hematite particles <5-10 mu m in diameter (as either unpacked or hard-packed powders) fail to match the TES spectra. The spectrally derived areal abundance of hematite: varies with particle size from similar to 10% (>30 mu m diameter) to 40-60% (10 mu m diameter). The hematite in Sinus Meridiani is thus distinct from the fine-grained (diameter <5-10 mu m), red, crystalline hematite considered, on the basis of visible, near-IR data, to be a minor spectral component in Martian bright regions like Olympus-Amazonis. Sinus Meridiani hematite is closely associated with a smooth, layered, friable surface that is interpreted to be sedimentary in origin. This material may be the uppermost surface in the region, indicating that it might be a late stage sedimentary unit or a layered portion of the heavily cratered plains units. We consider five possible mechanisms for the formation of coarse-grained, crystalline hematite. These processes fall into two classes depending on whether they require a significant amount of near-surface water: the first is chemical precipitation that includes origin by (1) precipitation from standing, oxygenated, Fe-rich water (oxide iron formations), (2) precipitation from Fe-rich hydrothermal fluids, (3) low-temperature dissolution and precipitation through mobile ground water leaching, and (4) formation of surface coatings, and the second is thermal oxidation of magnetite-rich lavas. Weathering and alteration processes, which produce nanophase and red hematite, are not consistent with the coarse, crystalline hematite observed in Sinus Meridiani. We prefer chemical precipitation models and favor precipitation from Fe-rich water on the basis of the probable association with sedimentary materials, large geographic size, distance from a regional heat source, and lack of evidence for extensive groundwater processes elsewhere on Mars. The TES results thus provide mineralogic evidence for probable large-scale water interactions. The Sinus Meridiani region may be an ideal candidate for future landed missions searching for biotic and prebiotic environments, and the physical characteristics of this site satisfy all of the engineering requirements for the missions currently planned. C1 Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. US Geol Survey, Denver, CO 80225 USA. Malin Space Sci Syst, San Diego, CA 92191 USA. US Geol Survey, Flagstaff, AZ 86001 USA. Vernadsky Inst, Moscow, Russia. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Christensen, PR (reprint author), Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. RI Smith, Michael/C-8875-2012; OI Edgett, Kenneth/0000-0001-7197-5751 NR 82 TC 298 Z9 303 U1 9 U2 52 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 2000 VL 105 IS E4 BP 9623 EP 9642 DI 10.1029/1999JE001093 PG 20 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 306HG UT WOS:000086590800015 ER PT J AU Marcinkevicius, S Leon, R AF Marcinkevicius, S Leon, R TI Photoexcited carrier transfer in InGaAs quantum dot structures: Dependence on the dot density SO APPLIED PHYSICS LETTERS LA English DT Article ID TRANSITIONS; CAPTURE AB Carrier dynamics has been measured by time-resolved photoluminescence in self-assembled InGaAs/GaAs quantum-dot structures with dot density of the order of 10(8)-10(10) cm(-2). The time of carrier transfer into a dot, which ranges from 2 to 20 ps, has been found to decrease with increasing quantum dot density. The temperature and photoexcited carrier density dependencies of the carrier transfer times suggest that potential barriers at wetting layer and quantum-dot interfaces hinder carrier capture in low-density quantum-dot structures. (C) 2000 American Institute of Physics. [S0003-6951(00)05017-8]. C1 Royal Inst Technol, Dept Phys Opt, S-10044 Stockholm, Sweden. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Marcinkevicius, S (reprint author), Royal Inst Technol, Dept Phys Opt, S-10044 Stockholm, Sweden. NR 18 TC 37 Z9 38 U1 1 U2 1 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 24 PY 2000 VL 76 IS 17 BP 2406 EP 2408 PG 3 WC Physics, Applied SC Physics GA 305KJ UT WOS:000086538700028 ER PT J AU Bekey, I AF Bekey, I TI The next century of flight SO AVIATION WEEK & SPACE TECHNOLOGY LA English DT Article C1 NASA Headquarters, Off Space Flight, Adv Programs, Washington, DC USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU MCGRAW HILL INC PI NEW YORK PA 1221 AVENUE OF THE AMERICAS, NEW YORK, NY 10020 USA SN 0005-2175 J9 AVIAT WEEK SPACE TEC JI Aviat. Week Space Technol. PD APR 24 PY 2000 VL 152 IS 17 BP 86 EP 86 PG 1 WC Engineering, Aerospace SC Engineering GA 307UY UT WOS:000086673600038 ER PT J AU Streich, S Briggs, G Blacic, J Schilte, P Peterson, C AF Streich, S Briggs, G Blacic, J Schilte, P Peterson, C TI Drilling technology for Mars research useful for oil, gas industries SO OIL & GAS JOURNAL LA English DT Article C1 Halliburton Energy Serv Inc, Duncan, OK 73533 USA. NASA, Moffett Field, CA USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM USA. Shell Oil Co, Rijswijk, Netherlands. NADET Inst, Boxford, MA USA. RP Streich, S (reprint author), Halliburton Energy Serv Inc, Duncan, OK 73533 USA. NR 0 TC 0 Z9 0 U1 1 U2 2 PU PENNWELL PUBL CO ENERGY GROUP PI TULSA PA 1421 S SHERIDAN RD PO BOX 1260, TULSA, OK 74101 USA SN 0030-1388 J9 OIL GAS J JI Oil Gas J. PD APR 24 PY 2000 VL 98 IS 17 BP 46 EP + PG 5 WC Energy & Fuels; Engineering, Petroleum SC Energy & Fuels; Engineering GA 311KQ UT WOS:000086883700018 ER PT J AU Hellier, C Kemp, J Naylor, T Bateson, FM Jones, A Overbeek, D Stubbings, R Mukai, K AF Hellier, C Kemp, J Naylor, T Bateson, FM Jones, A Overbeek, D Stubbings, R Mukai, K TI Outbursts of EX Hydrae: mass-transfer events or disc instabilities? SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE accretion, accretion discs; binaries : close; stars : individual : EX Hydrae; novae, cataclysmic variables; X-rays : stars ID INTERMEDIATE POLAR; TV-COLUMBAE; ACCRETION; PHOTOMETRY AB We present the 45-yr record of the light curve of EX Hya, and discuss the characteristics of its 15 observed outbursts. We then concentrate on the 1998 outburst, reporting the first outburst X-ray observations. We discover an X-ray beat-cycle modulation, indicating that an enhanced accretion stream couples directly with the magnetosphere in outburst, confirming our previous prediction. Optical eclipse profiles late in outburst show that the visible light is dominated by an enhanced mass-transfer stream overflowing the accretion disc. We are uncertain whether the enhanced mass transfer is triggered by a disc instability, or by some other cause. While in outburst, EX Hya shows some of the characteristics of SW Sex stars. C1 Univ Keele, Dept Phys, Keele ST5 5BG, Staffs, England. Columbia Univ, Biosphere Ctr 2, Astron Programs, Oracle, AZ 85623 USA. Royal Astron Soc New Zealand, Variable Star Sect, Greerton, Tauranga, New Zealand. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Hellier, C (reprint author), Univ Keele, Dept Phys, Keele ST5 5BG, Staffs, England. RI Naylor, Tim /A-9465-2015 NR 34 TC 27 Z9 27 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 21 PY 2000 VL 313 IS 4 BP 703 EP 710 DI 10.1046/j.1365-8711.2000.03301.x PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 302WZ UT WOS:000086390600012 ER PT J AU Reichardt, J Hess, M Macke, A AF Reichardt, J Hess, M Macke, A TI Lidar inelastic multiple-scattering parameters of cirrus particle ensembles determined with geometrical-optics crystal phase functions SO APPLIED OPTICS LA English DT Article ID HEXAGONAL ICE CRYSTALS; SOLAR RADIATIVE-TRANSFER; T-MATRIX COMPUTATIONS; LIGHT-SCATTERING; HIGH CLOUDS; AXISYMMETRICAL PARTICLES; MICROPHYSICAL PROPERTIES; NONSPHERICAL PARTICLES; SINGLE-SCATTERING; SNOW CRYSTALS AB Multiple-scattering correction factors for cirrus particle extinction coefficients measured with Raman and high spectral resolution lidars are calculated with a radiative-transfer model. Cirrus particle-ensemble phase functions are computed from single-crystal phase functions derived in a geometrical-optics approximation. Seven crystal types are considered. In cirrus clouds with height in dependent particle extinction coefficients the general pattern of the multiple-scattering parameters has a steep onset at cloud base with values of 0.5-0.7 followed by a gradual and monotonic decrease to 0.1-0.2 at cloud top. The larger the scattering particles are, the more gradual is the rate of decrease. Multiple-scattering parameters of complex crystals and of imperfect hexagonal columns and plates can be well approximated by those of projected-area equivalent ice spheres, whereas perfect hexagonal crystals show values as much as 70% higher than those of spheres. The dependencies of the multiple-scattering parameters on cirrus particle spectrum, base height, and geometric depth and on the lidar parameters laser wavelength and receiver field of view, are discussed, and a set of multiple-scattering parameter profiles for the correction of extinction measurements in homogeneous cirrus is provided. (C) 2000 Optical Society of America. C1 NASA, Goddard Space Flight Ctr, Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol,Atmospher Chem & Dyn, Greenbelt, MD 20771 USA. GKSS Forschungszentrum Geesthacht GmbH, Inst Phys & Chem Analyt, D-21494 Geesthacht, Germany. Deutsch Zentrum Luft & Raumfahrt Oberpfaffenhofen, Deutsch Fernerkundungsdatenzenturm, D-82234 Wessling, Germany. Inst Meereskunde, D-24105 Kiel, Germany. RP Reichardt, J (reprint author), NASA, Goddard Space Flight Ctr, Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol,Atmospher Chem & Dyn, Code 916, Greenbelt, MD 20771 USA. EM reichardt@code916.gsfc.nasa.gov; michael.hess@dlr.de; amacke@ifm.uni-kiel.de NR 61 TC 20 Z9 20 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 APR 20 PY 2000 VL 39 IS 12 BP 1895 EP 1910 DI 10.1364/AO.39.001895 PG 16 WC Optics SC Optics GA 306LQ UT WOS:000086598500005 PM 18345086 ER PT J AU Williamson, CK De Young, RJ AF Williamson, CK De Young, RJ TI Method for the reduction of signal-induced noise in photomultiplier tubes SO APPLIED OPTICS LA English DT Article ID STRATOSPHERIC OZONE; SYSTEM AB A new method to reduce photomultiplier tube detector signal-induced noise (SIN) in a lidar system is successfully demonstrated. A metal ring electrode placed external to the photomultiplier tube photocathode is pulsed during the intense near-field lidar return with a potential between 15 and 500 V, resulting in a significant reduction in SIN. The effect of the metal ring voltage on the decay time constant and the magnitude of a simulated lidar signal is presented. Optimal experimental conditions for the use of this device in lidar receivers, such that the lidar decay time constant is not affected, are determined. Mechanisms for this SIN suppression system are discussed in detail, and data were recorded to show that the voltage on the metal ring functions by altering the photomultiplier electron optics. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Williamson, CK (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 12 TC 4 Z9 4 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 APR 20 PY 2000 VL 39 IS 12 BP 1973 EP 1979 DI 10.1364/AO.39.001973 PG 7 WC Optics SC Optics GA 306LQ UT WOS:000086598500015 PM 18345096 ER PT J AU Yi, S Brown, TM Heap, S Hubeny, I Landsman, W Lanz, T Sweigart, A AF Yi, S Brown, TM Heap, S Hubeny, I Landsman, W Lanz, T Sweigart, A TI On the age estimation of LBDS 53W091 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : elliptical and lenticular, cD; galaxies : evolution; galaxies : formation; galaxies : individual (53W091); galaxies : photometry; galaxies : stellar content ID COLOR-MAGNITUDE DIAGRAM; ELLIPTIC GALAXIES; ULTRAVIOLET EXTINCTION; STARS; MODELS; UPTURN AB The recent spectral analysis of LBDS 53W091 by Spinrad and his collaborators has suggested that this red galaxy at z = 1.552 is at least 3.5 Gyr old. This imposes an important constraint on cosmology, suggesting that this galaxy formed at z greater than or similar to 6.5, assuming recent estimates of cosmological parameters. While their analysis was heavily focused on the use of some UV spectral breaks as age indicators, we have performed chi(2) tests to the continuum of this galaxy using its UV spectrum and photometric data (R, J, H, and K: 2000-9000 Angstrom in rest frame). We have used the updated Yi models that are based on the Yale tracks. We find it extremely difficult to reproduce such large age estimates, under the assumption of the most probable input parameters. Using the same configuration as in Spinrad et al. (conventional solar abundance models), our analysis suggests an age of approximately 1.4-1.8 Gyr. We have improved our models over conventional ones by taking into account convective core overshoot in the stellar model calculations and realistic metallicity distributions in the galaxy population synthesis. Overshoot affects the visible continuum normalized to the UV and raises the photometry-based age estimates by 25%. The use of metallicity mixtures affects the whole spectrum and raises all continuum-based age estimates by up to a factor of 2. If the mean metallicity of the stars in this galaxy is assumed to be twice solar, the models including these two effects match the UV spectrum and photometric data of LBDS 53W091 near the age of 1.5-2.0 Gyr. Our results cannot be easily reconciled with that of Spinrad et al. The discrepancy between Spinrad et al.'s age estimate (based on the Jimenez models) and ours originates from the large difference in the model integrated spectrum: the Jimenez models are much bluer than the Yi models and the Bruzual & Chariot models. We propose to apply some viable tests to them for verification and search for the origin of the difference through a more thorough investigation. Considering the significance of the age estimates of distant galaxies as probes of cosmology, it would be an urgent task. C1 Yonsei Univ, Ctr Space Astrophys, Seoul 120749, South Korea. CALTECH, Pasadena, CA 91125 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Yi, S (reprint author), Yonsei Univ, Ctr Space Astrophys, Seoul 120749, South Korea. EM yi@srl.caltech.edu NR 27 TC 35 Z9 35 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 2000 VL 533 IS 2 BP 670 EP 681 DI 10.1086/308681 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 313GA UT WOS:000086990900009 ER PT J AU Kommers, JM Lewin, WHG Kouveliotou, C van Paradijs, J Pendleton, GN Meegan, CA Fishman, GJ AF Kommers, JM Lewin, WHG Kouveliotou, C van Paradijs, J Pendleton, GN Meegan, CA Fishman, GJ TI The intensity distribution of faint gamma-ray bursts detected with BATSE SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; methods : statistical ID 25 APRIL 1998; LUMINOSITY FUNCTION; HOST GALAXIES; UNUSUAL SUPERNOVA; STAR-FORMATION; ERROR BOX; CONSTRAINTS; REDSHIFT; IDENTIFICATION; EMISSION AB We have recently completed a search of 6 years of archival BATSE data for gamma-ray bursts (GRBs) that were too faint to activate the real-time burst detection system running on board the spacecraft. These "nontriggered" bursts can be combined with the "triggered" bursts detected on board to produce a GRB intensity distribution that reaches peak fluxes a factor of similar to 2 lower than could be studied previously. The value of the [V/V(max)] statistic (in Euclidean space) for the bursts we detect is 0.177 +/- 0.006. This surprisingly low value is obtained because we detected very few bursts on the 4.096 s and 8.192 s timescales (where most bursts have their highest signal-to-noise ratio) that were not already detected on the 1.024 s timescale. If allowance is made for a power-law distribution of intrinsic peak luminosities, the extended peak flux distribution is consistent with models in which the redshift distribution of the gamma-ray burst rate approximately traces the star formation history of the universe. We argue that this class of models is preferred over those in which the burst rate is independent of redshift. We use the peak flux distribution to derive a limit of 10% (99% confidence) on the fraction of the total burst rate that could be contributed by a spatially homogeneous (in Euclidean space) subpopulation of burst sources, such as type Ib/c supernovae. These results lend support to the conclusions of previous studies predicting that relatively few faint "classical" GRBs will be found below the BATSE onboard detection threshold. C1 MIT, Dept Phys, Cambridge, MA 02139 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. Univ Space Res Assoc, Huntsville, AL 35800 USA. NASA, Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Alabama, Huntsville, AL 35812 USA. Univ Amsterdam, Amsterdam, Netherlands. RP Kommers, JM (reprint author), MIT, Dept Phys, Cambridge, MA 02139 USA. NR 66 TC 42 Z9 44 U1 0 U2 3 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 APR 20 PY 2000 VL 533 IS 2 BP 696 EP 709 DI 10.1086/308674 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 313GA UT WOS:000086990900011 ER PT J AU Hubeny, I Agol, E Blaes, O Krolik, JH AF Hubeny, I Agol, E Blaes, O Krolik, JH TI Non-LTE models and theoretical spectra of accretion disks in active galactic nuclei. III. Integrated spectra for hydrogen-helium disks SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; galaxies : active; galaxies : nuclei ID QUASAR EMISSION MECHANISM; VERTICAL STRUCTURE; LYMAN EDGE; BLACK-HOLE; CONTINUUM POLARIZATION; STELLAR ATMOSPHERES; TRANSPORT AB We have constructed a grid of non-LTE disk models for a wide range of values of black hole mass and mass accretion rate, for several values of the viscosity parameter alpha, and for two extreme values of the black hole spin: the maximum-rotation Kerr black hole, and the Schwarzschild (nonrotating) black hole. Our procedure calculates self-consistently the vertical structure of all disk annuli together with the radiation field, without any approximations imposed on the optical thickness of the disk, and without any ad hoc approximations to the behavior of the radiation intensity. The total spectrum of a disk is computed by summing the spectra of the individual annuli, taking into account the general relativistic transfer function. The grid covers nine values of the black hole mass between M = 1/8 x 10(9) and 32 x 10(9) M. with a twofold increase of mass for each subsequent value; and eleven values of the mass accretion rate, each a power of 2 times 1 M.yr(-1). The highest value of the accretion rate corresponds to the total luminosity L/L-Edd approximate to 0.3. We show the vertical structure of individual annuli within the set of accretion disk models, along with their local emergent flux, and discuss the internal physical self-consistency of the models. We then present the full disk-integrated spectra and discuss a number of observationally interesting properties of the models, such as optical/ultraviolet colors, the behavior of the hydrogen Lyman limit region, polarization, and the number of ionizing photons. Our calculations are far from definitive in terms of the input physics, but generally we find that our models exhibit rather red optical/UV colors. Flux discontinuities in the region of the hydrogen Lyman limit are only present in cool, low-luminosity models, while hotter models exhibit blueshifted changes in spectral slope. C1 NASA, Goddard Space Flight Ctr, NOAO, AURA, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. RP Hubeny, I (reprint author), NASA, Goddard Space Flight Ctr, NOAO, AURA, Code 681, Greenbelt, MD 20771 USA. RI Agol, Eric/B-8775-2013 OI Agol, Eric/0000-0002-0802-9145 NR 52 TC 101 Z9 102 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 2000 VL 533 IS 2 BP 710 EP 728 DI 10.1086/308708 PN 1 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 313GA UT WOS:000086990900012 ER PT J AU Terashima, Y Ho, LC Ptak, AF Mushotzky, RF Serlemitsos, PJ Yaqoob, T Kunieda, H AF Terashima, Y Ho, LC Ptak, AF Mushotzky, RF Serlemitsos, PJ Yaqoob, T Kunieda, H TI ASCA observations of "type 2" liners: Evidence for a stellar source of ionization SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : nuclei ID X-RAY-EMISSION; LUMINOSITY ACTIVE GALAXIES; GAS IMAGING SPECTROMETER; DWARF SEYFERT NUCLEI; H-ALPHA EMISSION; GALACTIC NUCLEI; STARBURST GALAXIES; BLACK-HOLES; BOARD ASCA; NGC-1052 AB We present ASCA observations of low-ionization nuclear emission-line regions (LINERs) without broad H alpha emission in their optical spectra. The sample of " type 2 " LINERs consists of NGC 404, 4111, 4192, 4457, and 4569. We have detected X-ray emission from all the objects except for NGC 404; among the detected objects are two so-called transition objects (NGC 4192 and NGC 4569), which have been postulated to be composite nuclei having both an H II region and a LINER component. The images of NGC 4111 and NGC 4569 in the soft (0.5-2 keV) and hard (2-7 keV) X-ray bands are extended on scales of several kiloparsecs. The X-ray spectra of NGC 4111, NGC 4457, and NGC 4569 are well fitted by a two-component model that consists of soft thermal emission with kT similar to 0.65 keV and a hard component represented by a power law (photon index similar to 2) or by thermal bremsstrahlung emission (kT several keV). The extended hard X-rays probably come from discrete sources, while the soft emission most likely originates from hot gas produced by active star formation in the host galaxy. We have found no clear evidence for the presence of active galactic nuclei (AGNs) in the sample. Using black hole masses estimated from host galaxy bulge luminosities, we obtain an upper limit on the implied Eddington ratios less than 5 x 10(-5). If an AGN component is the primary ionization source of the optical emission lines, then it must be heavily obscured with a column density significantly larger than 10(23) cm(-2), since the observed X-ray luminosity is insufficient to drive the luminosities of the optical emission lines. Alternatively, the optical emission could be ionized by a population of exceptionally hot stars. This interpretation is consistent with the small [O I] lambda 6300/H alpha ratios observed in these sources, the ultraviolet spectral characteristics in the cases where such information exists, and the X-ray results reported here. We also analyze the X-ray properties of NGC 4117, a low-luminosity Seyfert 2 galaxy serendipitously observed in the field of NGC 4111. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Carnegie Observ, Pasadena, CA 91101 USA. Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. Nagoya Univ, Dept Phys, Chikusa Ku, Nagoya, Aichi 4648602, Japan. RP Terashima, Y (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 88 TC 42 Z9 42 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 2000 VL 533 IS 2 BP 729 EP 743 DI 10.1086/308690 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 313GA UT WOS:000086990900013 ER PT J AU Hurley, K Laros, J Brandt, S Fenimore, EE Klebesadel, RW Terrell, J Cline, T Barat, C Boer, M Dezalay, JP Sunyaev, R Terekhov, O Kuznetsov, A Sazonov, S Lund, N Claret, A Paul, J Castro-Tirado, A AF Hurley, K Laros, J Brandt, S Fenimore, EE Klebesadel, RW Terrell, J Cline, T Barat, C Boer, M Dezalay, JP Sunyaev, R Terekhov, O Kuznetsov, A Sazonov, S Lund, N Claret, A Paul, J Castro-Tirado, A TI Gamma-ray burst arrival-time localizations: Simultaneous observations by Ulysses, Pioneer Venus Orbiter, SIGMA, WATCH, and PHEBUS SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts ID CATALOG; SUPPLEMENT; REDSHIFT AB Between the launch of the Ulysses spacecraft in 1990 October and the entry of Pioneer Venus Orbiter (PVO) into the atmosphere of Venus in 1992 October, concurrent coverage by Ulysses, PVO, the WATCH experiments aboard the Granat and Eureca spacecraft, and the SIGMA and PHEBUS experiments aboard the Granat spacecraft was obtained for numerous gamma-ray bursts. Fifteen of them were detected by three or more instruments on spacecraft separated by distances of several AU and could therefore be accurately localized by triangulation. In some cases, independent, accurate locations were obtained by SIGMA and/or WATCH. We present these localizations, which range in area from 0.9 to 530 arcmin(2). C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85715 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Ctr Etud Spatiale Rayonnements, F-31029 Toulouse, France. Moscow Space Res Inst, Moscow 117810, Russia. Danish Space Res Inst, DK-2100 Copenhagen, Denmark. Ctr Etud Saclay, F-91191 Gif Sur Yvette, France. Inst Nacl Invest Agr, LAEFF, E-28080 Madrid, Spain. RP Hurley, K (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. OI Castro-Tirado, A. J./0000-0003-2999-3563; Boer, Michel/0000-0001-9157-4349 NR 21 TC 20 Z9 20 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 2000 VL 533 IS 2 BP 884 EP 889 DI 10.1086/308675 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 313GA UT WOS:000086990900023 ER PT J AU Bohm-Vitense, E Carpenter, K Robinson, R Ake, T Brown, J AF Bohm-Vitense, E Carpenter, K Robinson, R Ake, T Brown, J TI Do all BaII stars have white dwarf companions? SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : general; stars : peculiar; ultraviolet : stars; white dwarfs ID BARIUM STARS; BINARY NATURE; MODEL-ATMOSPHERE; RED GIANTS; ABUNDANCES; ELEMENTS AB With the Hubble Space Telescope (HST) and the Goddard High Resolution Spectrograph (GHRS) we have observed four barium stars, three mild barium stars, and one weak G-band star in the ultraviolet spectral region. One barium star was observed with HST and the Space Telescope Imaging Spectrograph (STIS). The aim was to check the hypothesis that all these peculiar stars have white dwarf (WD) companions, which at their asymptotic giant branch phase transferred mass with peculiar element abundances to the present barium and CH peculiar stars. Assuming that the ultraviolet continua of the cool giants, including the barium stars, are generated in their chromospheres and that the relations between the continua and the emission lines created in the chromospheres and transition layers are similar in field giants and barium stars, we found that, indeed, most of our target barium and weak barium stars appear to have excess flux in the UV when compared to standard giant stars. For most of the stars the excess flux can be attributed to WD companions with temperatures between 10,000 and 12,000 K, if the WD mass is about 0.6 M.. Cooling times for the WDs were derived from their effective temperatures and model calculations by M. Wood. The calculated cooling times are longer than the lifetimes of the barium stars on the giant branch. For our target stars the mass transfer therefore happened while they were still on the main sequence. For two of the mild barium stars and one or perhaps two barium stars the derived cooling times for the WD companions come out to be longer than the total evolutionary times of the barium stars as calculated by Schaller et al. If our derivations are correct (the error bars are rather large) then either evolutionary models with larger convective overshoot have to be used for the barium stars or the cooling times of the white dwarfs have to be revised downward. Possibly an additional (as yet unknown) cooling mechanism has to be considered? The weak G-band star HD 165634, which has a carbon underabundance of about a factor of 10, also appears to have a WD companion. We discuss the implications of this very low carbon abundance. C1 Univ Washington, Dept Astron, Seattle, WA 98195 USA. NASA, Goddard Space Flight Ctr, LASP, Greenbelt, MD 20771 USA. Catholic Univ Amer, Dept Phys, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. Washington State Univ, Pullman, WA 99164 USA. RP Bohm-Vitense, E (reprint author), Univ Washington, Dept Astron, Seattle, WA 98195 USA. NR 41 TC 30 Z9 30 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 2000 VL 533 IS 2 BP 969 EP 983 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 313GA UT WOS:000086990900033 ER PT J AU Moran, T Deming, D Jennings, DE McCabe, G AF Moran, T Deming, D Jennings, DE McCabe, G TI Solar magnetic field studies using the 12 micron emission lines. III. Simultaneous measurements at 12 and 1.6 microns SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : infrared; Sun : magnetic fields; sunspots ID STOKES PROFILE ANALYSIS; I 12-MU-M DIAGNOSTICS; INFRARED LINES; MG-I; LIMB OBSERVATIONS; EVERSHED FLOW; QUIET SUN; SUNSPOT; FEATURES; PROBES AB We report total magnetic field strength measurements made simultaneously at two heights in the solar atmosphere using two infrared lines: the upper photospheric 12.32 mu m line of Mg I and the lower photospheric 1.56 mu m line of Fe I. We used the dual outputs of the McMath-Pierce Fourier transform spectrometer to obtain high spectral resolution data for both lines using a single input aperture, eliminating spatial registration errors. The results show a decrease of field strength with height in sunspots and plages, demonstrating field divergence between the lower and upper photosphere. Sunspot penumbral field strengths decrease by 12% between the two heights, while plages show decreases as large as a factor of 3. The plage results are consistent with thin-flux-tube models, provided that merging of flux tubes occurs. However, the sunspot results imply height gradients in total field strength that are large (2 G km(-1)) at the inner edge of the penumbra and decrease to smaller values (0.5 G km(-1)) at the outer penumbral edge. The magnitude of these gradients and their radial variation imply that sunspots do not conform to the "similarity assumption" commonly invoked in classic analytic models of sunspot magnetostatic structure. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP SM&A Corp, E 2600 Pk Tower Dr, Vienna, VA 22180 USA. RI Jennings, Donald/D-7978-2012 NR 40 TC 11 Z9 11 U1 1 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 20 PY 2000 VL 533 IS 2 BP 1035 EP 1042 DI 10.1086/308711 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 313GA UT WOS:000086990900038 ER PT J AU Kahler, SW McAllister, AH Cane, HV AF Kahler, SW McAllister, AH Cane, HV TI A search for interplanetary energetic particle events from solar posteruptive arcades SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; Sun : corona; Sun : particle emission ID CORONAL MASS EJECTIONS; WIND SPACECRAFT DATA; POST-FLARE LOOPS; GAMMA-RAY FLARE; MAGNETIC RECONNECTION; PROTON EVENTS; JUNE 15; ACCELERATION; ULYSSES; SHOCKS AB While the E >10 MeV ions observed in gradual solar energetic particle (SEP) events in space are attributed to acceleration at shocks driven by coronal mass ejections (CMEs), it has been suggested that such SEPs may also be produced in the magnetic reconnection of coronal arcades following CMEs. The arcade SEPs could escape the corona along open field lines and provide additional contributions to observed gradual SEP events. We searched for SEP events associated with large, bright solar soft X-ray arcades and intense metric noise storms in the western hemisphere, which should be favorable for the production of arcade SEP events observed at 1 AU. Five arcades/storms were possibly or definitely associated with IMP-8 24-28 MeV proton increases, but the latter appear to be shock accelerated. We also found 30 arcades (14 in active regions and 16 outside active regions) with no detectable SEP increases, suggesting that those arcades were not sources of escaping SEPs. This result provides evidence against the possibility of coronal arcade contributions to gradual SEP events. C1 USAF, Res Lab, Hanscom AFB, MA 01731 USA. Helio Res, La Crescenta, CA 91214 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Tasmania, Sch Math & Phys, Hobart, Tas, Australia. RP Kahler, SW (reprint author), USAF, Res Lab, Hanscom AFB, MA 01731 USA. NR 56 TC 17 Z9 17 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 2000 VL 533 IS 2 BP 1063 EP 1070 DI 10.1086/308680 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 313GA UT WOS:000086990900041 ER PT J AU Ofman, L Nakariakov, VM Sehgal, N AF Ofman, L Nakariakov, VM Sehgal, N TI Dissipation of slow magnetosonic waves in coronal plumes SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; Sun : corona; Sun : magnetic fields; waves ID HEATING MECHANISMS; POLAR PLUMES; SOLAR CORONA; ALFVEN WAVES; SOHO; WIND AB Recently, slow magnetosonic waves were identified in polar plumes, at heights up to about 1.2 R. using the Extreme Ultraviolet Imaging Telescope (EIT) observations of quasi-periodic EUV intensity fluctuations, and higher in the corona using the Ultraviolet Coronagraph Spectrometer (UVCS) white-light channel. First, we derive the linear dispersion relation for the slow waves in the viscous plasma. Next, we derive and solve an evolutionary equation of the Burgers type for the slow waves, incorporating the effects of radial stratification, quadratic nonlinearity, and viscosity. Finally, we model the propagation and dissipation of slow magnetosonic waves in polar plumes using one-dimensional and two-dimensional MHD codes in spherical geometry. The waves are launched at the base of the corona with a monochromatic source. We find that the slow waves nonlinearly steepen as they propagate away from the Sun into the solar wind. The nonlinear steepening of the waves leads to enhanced dissipation owing to compressive viscosity at the wave fronts. The efficient dissipation of the slow wave by compressive viscosity leads to damping of the waves within the first solar radii above the surface. We investigate the parametric dependence of the wave properties. C1 Raytheon ITSS, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ St Andrews, Sch Math & Computat Sci, St Andrews KY16 9SS, Fife, Scotland. RP Ofman, L (reprint author), Raytheon ITSS, Greenbelt, MD 20771 USA. RI Nakariakov, Valery/E-2375-2013; Lee, SungHwan/O-2563-2013 OI Nakariakov, Valery/0000-0001-6423-8286; NR 26 TC 86 Z9 86 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 2000 VL 533 IS 2 BP 1071 EP 1083 DI 10.1086/308691 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 313GA UT WOS:000086990900042 ER EF