FN Thomson Reuters Web of Science™ VR 1.0 PT J AU O'Neill, NT Eck, TF Holben, BN Smirnov, A Royer, A Li, Z AF O'Neill, NT Eck, TF Holben, BN Smirnov, A Royer, A Li, Z TI Optical properties of boreal forest fire smoke derived from Sun photometry SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article DE aerosols; forest fire smoke; Sun photometry; optics ID SKY RADIANCE MEASUREMENTS; AEROSOL-SIZE DISTRIBUTION; BIOMASS BURNING AEROSOLS; UNITED-STATES; PRECIPITABLE WATER; AIR-POLLUTION; AMAZON BASIN; AERONET; CANADA; DEPTH AB [1] Aerosol optical properties derived from Sun photometry were investigated in terms of climatological trends at two Sun photometer sites significantly affected by western Canadian boreal forest fire smoke and in terms of a 2-week series of smoke events observed at stations near and distant from boreal forest fires. Aerosol optical depth (tau(a)) statistics for Waskesiu, Saskatchewan, and Thompson, Manitoba, were analyzed for summer data acquired between 1994 and 1999. A significant correlation between the geometric mean and the forest fire frequency indices (hot spots) was found; on the average, 80% of summertime optical depth variation in western Canada can be linked to forest fire sources. The average geometric mean and geometric standard deviation at 500 nm was observed to be 0.074 and 1.7 for the clearest, relatively smoke-free summer and 0.23 and 3.0 for the summer most influenced by smoke. A systematic decrease of fine mode Angstrom exponent (alpha(f)) was noted (dalpha(f)/d log tau(a) similar to -0.6). This decrease roughly corresponds to an increase in the fine mode effective radius (r(eff)) from 0.09 to 0.15 mum and an abundance (A) to size rate increase near 2.0 (d log A/d log r(eff)). A 1998 series of forest fire events was tracked using TOMS, AVHRR, and GOES imagery, back trajectories, and data from six Sun photometer sites in Canada and eastern United States. The results showed rates of decrease of alpha(f) with increasing tau(a) which were similar to the climatological data. An analysis in terms of source to station distance showed a decrease in alpha(f) and an increase in r(eff) with increasing distance. This observation was coherent with previous observations on the particle growth effects of aging. C1 Univ Sherbrooke, CARTEL, Sherbrooke, PQ J1K 2R1, Canada. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Goddard Earth Sci & Technol Ctr, Baltimore, MD 21228 USA. Canada Ctr Remote Sensing, Ottawa, ON K1A OY7, Canada. RP Univ Sherbrooke, CARTEL, 2500 Bd, Sherbrooke, PQ J1K 2R1, Canada. EM noneill@courrier.usherb.ca RI Smirnov, Alexander/C-2121-2009; ECK, THOMAS/D-7407-2012; Li, Zhanqing/F-4424-2010 OI Smirnov, Alexander/0000-0002-8208-1304; Li, Zhanqing/0000-0001-6737-382X NR 72 TC 38 Z9 39 U1 3 U2 18 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 JUN PY 2002 VL 107 IS D11 AR 4125 DI 10.1029/2001JD000877 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 609HN UT WOS:000178897700008 ER PT J AU Pope, SK Valero, FPJ Collins, WD Minnis, P AF Pope, SK Valero, FPJ Collins, WD Minnis, P TI Comparison of ScaRaB, GOES 8, aircraft, and surface observations of the absorption of solar radiation by clouds SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article DE radiation; absorption; clouds; observations ID ENHANCED SHORTWAVE EXPERIMENT; EXPERIMENT ARESE; TRANSMITTANCE; ATMOSPHERE AB [1] Data obtained by the Scanner for Radiation Budget (ScaRaB) instrument on the Meteor 3 satellite have been analyzed and compared to satellite (GOES 8), aircraft (Radiation Measurement System, RAMS), and surface (Baseline Solar Radiation Network (BRSN), Solar and Infrared Observations System (SIROS), and RAMS) measurements of irradiance obtained during the Atmospheric Radiation Measurements Enhanced Shortwave Experiment (ARESE). It is found that the ScaRaB data covering the period from March 1994 to February 1995 (the instrument's operational lifetime) indicate excess absorption of solar radiation by the cloudy atmosphere in agreement with previous aircraft, surface, and GOES 8 results. The full ScaRaB data set combined with BSRN and SIROS surface observations gives an average all-sky absorptance of 0.28. The GOES 8 data set combined with RAMS surface observations gives an average all-sky absorptance of 0.26. The aircraft data set (RAMS) gives a mean all-sky absorptance of 0.24 (for the column between 0.5 and 13 km). C1 Univ Calif San Diego, Scripps Inst Oceanog, Ctr Atmospher & Sci, Atmospher Res Lab, La Jolla, CA 92093 USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Pope, SK (reprint author), Univ Calif San Diego, Scripps Inst Oceanog, Ctr Atmospher & Sci, Atmospher Res Lab, 9500 Gilman Dr, La Jolla, CA 92093 USA. RI Collins, William/J-3147-2014; Minnis, Patrick/G-1902-2010 OI Collins, William/0000-0002-4463-9848; Minnis, Patrick/0000-0002-4733-6148 NR 15 TC 3 Z9 3 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN PY 2002 VL 107 IS D11 AR 4114 DI 10.1029/2001JD001139 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 609HN UT WOS:000178897700019 ER PT J AU Shindell, DT Grewe, V AF Shindell, DT Grewe, V TI Separating the influence of halogen and climate changes on ozone recovery in the upper stratosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article DE ozone; stratosphere; climate change; chlorofluorocarbons; ozone recovery ID MIDDLE ATMOSPHERE MODEL; WATER-VAPOR; DOUBLED CO2; SENSITIVITY; LATITUDE; INCREASE; TRENDS; LAYER AB [1] While halogens from chlorofluorocarbons (CFCs) dominated past ozone changes, our simulations show climate change playing an increasingly important role over coming decades. Including potential climate- induced stratospheric water vapor increases, the ozone change relative to 1980 attributable to climate change surpasses that due to halogens in the 2030s for both the upper stratosphere and the total column. Its overall impact may delay recovery of total ozone to 1980 values. These results emphasize that ozone recovery is not only a detection issue but also a detection and attribution issue, as trends must be ascribed to climate and halogens. Exploiting their different spatial patterns, we demonstrate a technique to isolate the halogen signature in the upper stratosphere by contrasting equatorial and midlatitude ozone trends at 40-km altitude. This may allow early detection of the effectiveness of halogen emission reductions, which would show that a delayed recovery does not represent a CFC treaty failure but rather highlights the growing influence of greenhouse gases on the Earth's atmosphere. C1 NASA, Goddard Inst Space Studies, Ctr Climate Res, New York, NY 10025 USA. Columbia Univ, Ctr Climate Syst Res, New York, NY USA. DLR, Inst Phys Atmosphare, D-82234 Wessling, Germany. RP Shindell, DT (reprint author), NASA, Goddard Inst Space Studies, Ctr Climate Res, 2880 Broadway, New York, NY 10025 USA. RI Shindell, Drew/D-4636-2012; Grewe, Volker/A-6147-2011 OI Grewe, Volker/0000-0002-8012-6783 NR 34 TC 12 Z9 14 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN PY 2002 VL 107 IS D12 AR 4144 DI 10.1029/2001JC0004\20 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 610TL UT WOS:000178976900016 ER PT J AU Singh, HB Anderson, BE Avery, MA Viezee, W Chen, Y Tabazadeh, A Hamill, P Pueschel, R Fuelberg, HE Hannan, JR AF Singh, HB Anderson, BE Avery, MA Viezee, W Chen, Y Tabazadeh, A Hamill, P Pueschel, R Fuelberg, HE Hannan, JR TI Global distribution and sources of volatile and nonvolatile aerosol in the remote troposphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article DE aerosol; particles; upper troposphere; pollution; condensation nuclei; PAN ID PEM-TROPICS-A; MIDLATITUDE UPPER TROPOSPHERE; PACIFIC EXPLORATORY MISSION; MARINE BOUNDARY-LAYER; CONDENSATION NUCLEI; STRATOSPHERIC AEROSOL; AIRCRAFT; PARTICLES; POLINAT-2; MODEL AB [1] Airborne measurements of aerosol (condensation nuclei, CN) and selected trace gases made over areas of the North Atlantic Ocean during Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) (October/November 1997), the south tropical Pacific Ocean during Pacific Exploratory Mission (PEM)-Tropics A (September/October 1996), and PEM-Tropics B (March/April 1999) have been analyzed. The emphasis is on interpreting variations in the number densities of fine (> 17 nm) and ultrafine (> 8 nm) aerosol in the upper troposphere (8-12 km). These data suggest that large number densities of highly volatile CN (10(4) - 10(5) cm(-3)) are present in the upper troposphere and particularly over the tropical/subtropical region. CN number densities in all regions are largest when the atmosphere is devoid of nonvolatile particles. Through marine convection and long-distance horizontal transport, volatile CN originating from the tropical/subtropical regions can frequently impact the abundance of aerosol in the middle and upper troposphere at mid to high latitudes. Nonvolatile aerosols behave in a manner similar to tracers of combustion (CO) and photochemical pollution (peroxyacetylnitrate (PAN)), implying a continental pollution source from industrial emissions or biomass burning. In the upper troposphere we find that volatile and nonvolatile aerosol number densities are inversely correlated. Results from an aerosol microphysical model suggest that the coagulation of fine volatile particles with fewer but larger nonvolatile particles, of principally anthropogenic origin, is one possible explanation for this relationship. In some instances the larger nonvolatile particles may also directly remove precursors (e. g., H2SO4) and effectively stop nucleation. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. San Jose State Univ, Dept Phys, San Jose, CA 95192 USA. Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. RP Singh, HB (reprint author), NASA, Ames Res Ctr, MS 245-5, Moffett Field, CA 94035 USA. NR 33 TC 10 Z9 10 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN PY 2002 VL 107 IS D11 AR 4121 DI 10.1029/2001JD000486 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 609HN UT WOS:000178897700012 ER PT J AU Tangborn, A Menard, R Ortland, D AF Tangborn, A Menard, R Ortland, D TI Bias correction and random error characterization for the assimilation of high-resolution Doppler imager line-of-sight velocity measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article DE stratospheric winds; observation error; forecast error; data assimilation; satellite wind measurement; wind retrieval ID ATMOSPHERE RESEARCH SATELLITE; KALMAN FILTER; PART I; STRATOSPHERE; EXCHANGE; FORECAST; PROFILES; TROPICS; SYSTEM AB [1] The statistical characteristics of the systematic and random observation errors of the line-of-sight (LOS) velocity measurements made by the high-resolution Doppler imager (HRDI) are obtained using collocated and coincident differences between HRDI observations and model-assimilated data (H-A). Although these differences have contributions from both observation and model errors, we show how they can be individually characterized. HRDI, a limb sounder on board the Upper Atmosphere Research Satellite (UARS), is the only instrument making global wind measurements in the stratosphere. Doppler shifts in O-2 absorption spectra measured by HRDI within two different bands (g and B) basically provide the line-of-sight velocity. The analysis presented here is carried out using the Doppler shifts themselves, rather than the HRDI retrieved (u,v) wind components. The absolute position of the line for zero-wind conditions in LOS velocity measurement is unknown, and one goal of this paper is to develop a systematic method of determining this position through mean differences (biases) between observed HRDI and LOS model analyses approximately projected onto the line of sight. Biases are separated based on 16 different measurement configurations. The bias dependence on these configurations (plus an altitude dependence) is used to create a bias correction for each instrument configuration. The random error component in H-A differences is analyzed by separating the g and B band observations and locating observation pairs where both bands are very nearly looking at the same location at the same time. It is shown that the two observation error streams are uncorrelated. Observation errors are also uncorrelated with the analyses error, and observational and model wind variance (in the stratosphere) are estimated. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. NW Res Associates Inc, Bellevue, WA 98009 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. RP Tangborn, A (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 910-3, Greenbelt, MD 20771 USA. EM tangborn@dao.gsfc.nasa.gov NR 26 TC 0 Z9 0 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 JUN PY 2002 VL 107 IS D12 AR 4147 DI 10.1029/2001JD000397 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 610TL UT WOS:000178976900013 ER PT J AU Renfrew, IA King, JC Markus, T AF Renfrew, IA King, JC Markus, T TI Coastal polynyas in the southern Weddell Sea: Variability of the surface energy budget SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article DE polynyas; sea ice; Weddell Sea; surface energy budget; surface fluxes; high-salinity shelf water ID INTERNAL BOUNDARY-LAYER; NCEP-NCAR REANALYSIS; COLD-AIR OUTBREAK; ICE SHELF; ARCTIC-OCEAN; HEAT-FLUX; WATER; ANTARCTICA; FROST; BENEATH AB [1] The surface energy budget of coastal polynyas in the southern Weddell Sea has been evaluated for the period 1992-1998 using a combination of satellite observations, meteorological data, and simple physical models. The study focuses on polynyas that habitually form off the Ronne Ice Shelf. The coastal polynya areal data are derived from an advanced multichannel polynya detection algorithm applied to passive microwave brightness temperatures. The surface sensible and latent heat fluxes are calculated via a fetch-dependent model of the convective-thermal internal boundary layer. The radiative fluxes are calculated using well-established empirical formulae and an innovative cloud model. Standard meteorological variables that are required for the flux calculations are taken from automatic weather stations and from the National Centers for Environmental Production/National Center for Atmospheric Research reanalyses. The 7 year surface energy budget shows an overall oceanic warming due to the presence of coastal polynyas. For most of the period the summertime oceanic warming, due to the absorption of shortwave radiation, is approximately in balance with the wintertime oceanic cooling. However, the anomalously large summertime polynya of 1997-1998 allowed a large oceanic warming of the region. Wintertime freezing seasons are characterized by episodes of high heat fluxes interspersed with more quiescent periods and controlled by coastal polynya dynamics. The high heat fluxes are primarily due to the sensible heat flux component, with smaller complementary latent and radiative flux components. The average freezing season area-integrated energy exchange is 3.48 x 10(19) J, with contributions of 63, 22, and 15% from the sensible, latent, and radiative components, respectively. The average melting season area-integrated energy exchange is -5.31 x 10(19) J, almost entirely due to the radiative component. There is considerable interannual variability in the surface energy budget. The standard deviation of the energy exchange during the freezing (melting) season is 28% (95%) of the mean. During the freezing season, positive surface heat fluxes are equated with ice production rates. The average annual coastal polynya ice production is 1.11 x 10(11) m(3) (or 24 m per unit area), with a range from 0.71 x 10(11) (in 1994) to 1.55 x 10(11) m(3) (in 1995). This can be compared to the estimated total ice production for the entire Weddell Sea: on average the coastal polynya ice production makes up 6.08% of the total, with a range from 3.65 (in 1994) to 9.11% (in 1995). C1 British Antarctic Survey, Cambridge CB3 0ET, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Renfrew, IA (reprint author), British Antarctic Survey, High Cross,Madingley Rd, Cambridge CB3 0ET, England. RI Renfrew, Ian/E-4057-2010; Markus, Thorsten/D-5365-2012 OI Renfrew, Ian/0000-0001-9379-8215; NR 58 TC 57 Z9 58 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-OCEANS JI J. Geophys. Res.-Oceans PD JUN PY 2002 VL 107 IS C6 AR 3063 DI 10.1029/2000JC000720 PG 22 WC Oceanography SC Oceanography GA 611AD UT WOS:000178993500001 ER PT J AU Bandfield, JL AF Bandfield, JL TI Global mineral distributions on Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article DE Mars; infrared spectroscopy; surface mineralogy; remote sensing ID THERMAL EMISSION SPECTROMETER; MARTIAN SURFACE; INFRARED-SPECTROSCOPY; PHYSICAL-PROPERTIES; ORBITER CAMERA; SURVEYOR; DUST; SPECTRA; MARINER-9; ROCKS AB [1] Determining the mineralogy of Mars is an essential part of revealing the conditions of the surface and subsurface. A deconvolution method was used to remove atmospheric components and determine surface mineralogy from Thermal Emission Spectrometer data at 1 pixel per degree (ppd). Minerals are grouped into categories on the basis of compositional and spectral similarity, and global concentration maps are produced. All binned pixels are fit well with RMS errors of less than or equal to0.005 in emissivity. Higher RMS errors are attributed to short wavelength particle size effects on dust-covered surfaces. Significant concentrations (>0.10) of plagioclase, high-Ca pyroxene, sheet silicates/high-Si glass, and hematite are detected and display distributions consistent with previous studies. Elevated concentrations of plagioclase and high-Ca pyroxene are consistent with basaltic surfaces and are located in low-albedo highlands regions north of similar to45degreesS. Significant concentrations of plagioclase and sheet silicates/high-Si glass and low concentrations of high-Ca pyroxenes are consistent with andesitic surfaces and are concentrated in both southern and northern high-latitude, low-albedo regions. Andesitic surfaces in the southern hemisphere have a lower spectral contrast than northern surfaces. An isolated surface located in Solis Planum is spectrally distinct but compositionally similar to other surfaces interpreted to be andesitic in composition. Concentrations of olivine below the detection limit correctly identify its presence in two of three locations. Potassium feldspar, low-Ca pyroxene, basaltic glass, olivine, sulfate, carbonate, quartz, and amphibole are not detected with confidence at 1 ppd. The results presented here indicate a predominance of volcanic compositions within Martian dust-free surfaces. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Bandfield, JL (reprint author), NASA, Goddard Space Flight Ctr, Code 693-0, Greenbelt, MD 20771 USA. EM jbandfield@lepvax.gsfc.nasa.gov NR 72 TC 111 Z9 115 U1 3 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 JUN PY 2002 VL 107 IS E6 AR 5042 DI 10.1029/2001JE001510 PG 21 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 610TW UT WOS:000178977900005 ER PT J AU Potter, AE Anderson, CM Killen, RM Morgan, TH AF Potter, AE Anderson, CM Killen, RM Morgan, TH TI Ratio of sodium to potassium in the Mercury exosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article DE Mercury; sodium; potassium; exosphere ID BRIGHT SPOTS; ATMOSPHERE; DIFFUSION; SURFACE; MOON; MAGNETOSPHERE; LUNAR AB [1] The ratio of sodium to potassium in the exosphere of Mercury is highly variable and averages about 100, considerably larger than for the Moon. We considered the possibility that this high value results from potassium loss rates that are larger than sodium loss rates. The principal loss processes are the sweeping of hot atoms off the planet by solar radiation acceleration and the capture of metal photoions by the solar wind. We found that radiation acceleration losses are not sufficiently different for sodium and potassium to explain the high ratio. Capture of sodium and potassium photoions by the solar wind is thought to be the major loss process. However, there is a competing process for the ions, which is collision with the surface, followed by neutralization. These atoms can return to the exosphere. The net steady state density of sodium and potassium in the exosphere depends on the relative efficiencies of solar wind capture and surface recycling. We propose that the photoion loss and recycling rates are sufficiently different for sodium and potassium to account for the high ratio. The higher mass of the potassium atom relative to sodium results in a smaller scale height and a larger gyroradius for potassium relative to sodium, which may result in more rapid net loss of potassium. C1 Natl Opt Astron Observ, Natl Solar Observ, Tucson, AZ 85726 USA. New Mexico State Univ, Dept Astron, Las Cruces, NM 88003 USA. SW Res Inst, San Antonio, TX 78228 USA. NASA Headquarters, Washington, DC 20546 USA. RP Potter, AE (reprint author), Natl Opt Astron Observ, Natl Solar Observ, POB 26732,950 N Cherry Ave, Tucson, AZ 85726 USA. RI Anderson, Carrie/C-8097-2012; Morgan, Thomas/I-5943-2013 NR 25 TC 14 Z9 14 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JUN PY 2002 VL 107 IS E6 AR 5040 DI 10.1029/2000JE001493 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 610TW UT WOS:000178977900007 ER PT J AU Voorhies, CV Sabaka, TJ Purucker, M AF Voorhies, CV Sabaka, TJ Purucker, M TI On magnetic spectra of Earth and Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article DE planetary magnetism; geomagnetism; Earth; Mars; magnetic spectrum; crustal magnetic fields ID GEOMAGNETIC-FIELD; CRUSTAL MAGNETIZATION; CORE; MODEL AB [1] The spectral method for distinguishing crustal from core-source magnetic fields is reexamined, modified, and applied to both a comprehensive geomagnetic field model and an altitude normalized magnetic map of Mars. The observational spectra are fairly fitted by theoretical forms expected from certain elementary classes of magnetic sources. For Earth we find fields from a core of radius 3512 +/- 64 km, in accord with the seismologic core radius of 3480 km, and a crust represented by a shell of random dipolar sources at radius 6367 +/- 14 km, near the planetary mean radius of 6371.2 km. For Mars we find no sign of a core-source field, only a field from a crust represented in the same way, but at radius 3344 +/- 10 km, about 46 km below the planetary mean radius of 3389.5 km, and with sources about 9.6 +/- 3.2 times stronger. C1 NASA, Raytheon ITSS, Geodynam Branch, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Voorhies, CV (reprint author), NASA, Raytheon ITSS, Geodynam Branch, Goddard Space Flight Ctr, Code 921, Greenbelt, MD 20771 USA. RI Voorhies, Coerte/D-4672-2012; Sabaka, Terence/D-5618-2012 NR 18 TC 48 Z9 48 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JUN PY 2002 VL 107 IS E6 AR 5034 DI 10.1029/2001JE001534 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 610TW UT WOS:000178977900013 ER PT J AU Leuliette, EW Nerem, RS Russell, GL AF Leuliette, EW Nerem, RS Russell, GL TI Detecting time variations in gravity associated with climate change SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID SEA-LEVEL CHANGE; MODELS; TEMPERATURE; SCALE; EARTH; FIELD AB [1] General circulation models offer a way to estimate the impact of mass redistributions on the Earth's time-varying gravity field. In this way, the prospects for detecting climate signals in the gravity field by dedicated satellite gravity missions, such as Gravity Recovery and Climate Experiment (GRACE), can be assessed. Using monthly averaged fluid mass diagnostics from a coupled atmosphere-ocean model developed at the Goddard Institute for Space Studies (GISS), we have estimated geoid variations from the fundamental model mass components. From these estimates the seasonal geoid signals from sea level, snow, soil moisture, water vapor, and atmospheric mass can be compared to the estimated errors for GRACE. All of these seasonal mass flows from the GISS model are well above the preliminary GRACE measurement errors. In addition, mass flows with significant secular trends attributable to the model's simulated increase of greenhouse gases would, in principle, be detectable by GRACE. However, the interannual variability of mass flows may require longer time series of gravity data, pattern analysis, or modeling improvements in order to detect trends. C1 Univ Texas, Ctr Space Res, Austin, TX 78712 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Leuliette, EW (reprint author), Univ Colorado, Colorado Ctr Astrodynam Res, UCB 431, Boulder, CO 80309 USA. EM eric.leuliette@colorado.edu; nerem@colorado.edu; russell@giss.nasa.gov RI Leuliette, Eric/D-1527-2010 OI Leuliette, Eric/0000-0002-3425-4039 NR 21 TC 7 Z9 7 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD JUN PY 2002 VL 107 IS B6 AR 2112 DI 10.1029/2001JB000404 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 610YZ UT WOS:000178990800016 ER PT J AU Brain, DA Bagenal, F Acuna, MH Connerney, JEP Crider, DH Mazelle, C Mitchell, DL Ness, NF AF Brain, DA Bagenal, F Acuna, MH Connerney, JEP Crider, DH Mazelle, C Mitchell, DL Ness, NF TI Observations of low-frequency electromagnetic plasma waves upstream from the Martian shock SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article DE Mars; MGS; upstream; waves; electromagnetic ID QUASI-PERPENDICULAR SHOCK; MARS GLOBAL SURVEYOR; WHISTLER INSTABILITY; PHOBOS OBSERVATIONS; EARTHS FORESHOCK; MAGNETIC-FIELD; SOLAR-WIND; BOW SHOCK; PROTONS; PACKETS AB [1] We have analyzed magnetic field data returned from Mars Global Surveyor (MGS) for signatures of electromagnetic plasma waves upstream from the Martian bow shock. We discuss two recurring wave features in the data. Left-hand polarized waves (0.04-0.10 Hz) observed near the local proton gyrofrequency (PCWs) propagate at small to moderate angles to the magnetic field and have amplitudes that decrease with distance from Mars. They are concentrated in two locations upstream of the Martian shock. PCWs were reported from Phobos 2 observations and can be attributed to solar wind pickup of Mars' hydrogen exosphere. Higher-frequency waves (0.4-2.3 Hz) are observed when MGS is magnetically connected to the Martian shock. These waves have not been reported at Mars before, but have been reported at many solar system bodies, and are attributed to whistler waves generated at the shock and propagating upstream. The sense of polarization (left-handed or right-handed) of the whistler waves observed in the spacecraft frame depends upon the angle between the magnetic field and the solar wind flow direction. The whistler waves at Mars follow the trends in frequency, amplitude, propagation angle, and eccentricity observed at other solar system bodies. C1 Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20701 USA. CESR, F-31028 Toulouse, France. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. RP Brain, DA (reprint author), Univ Colorado, Atmospher & Space Phys Lab, Campus Box 392, Boulder, CO 80309 USA. RI connerney, john/I-5127-2013; Hurley, Dana/F-4488-2015 OI Hurley, Dana/0000-0003-1052-1494 NR 39 TC 46 Z9 45 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 JUN PY 2002 VL 107 IS A6 AR 1076 DI 10.1029/2000JA000416 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 610UK UT WOS:000178979400013 ER PT J AU Khazanov, GV Gamayunov, KV Jordanova, VK Krivorutsky, EN AF Khazanov, GV Gamayunov, KV Jordanova, VK Krivorutsky, EN TI A self-consistent model of the interacting ring current ions and electromagnetic ion cyclotron waves, initial results: Waves and precipitating fluxes SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article DE ring current; inner magnetosphere; plasmasphere; numerical modeling ID 1-2 MAGNETIC PULSATIONS; EQUATORIAL MAGNETOSPHERE; PARTICLE INTERACTIONS; CURRENT EVOLUTION; CURRENT REGION; ALFVEN WAVES; STORM; PROTON; OSCILLATIONS; SIMULATION AB [1] Initial results from a newly developed model of the interacting ring current ions and ion cyclotron waves are presented. The model is based on the system of two kinetic equations: one equation describes the ring current ion dynamics, and another equation describes wave evolution. The system gives a self-consistent description of the ring current ions and ion cyclotron waves in a quasilinear approach. These equations for the ion phase space distribution function and for the wave power spectral density were solved on aglobal magnetospheric scale under nonsteady state conditions during the 2-5 May 1998 storm. The structure and dynamics of the ring current proton precipitating flux regions and the ion cyclotron wave-active zones during extreme geomagnetic disturbances on 4 May 1998 are presented and discussed in detail. C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Natl Space Sci & Technol Ctr, Huntsville, AL 35805 USA. Univ Alaska, Inst Geol, Fairbanks, AK 99775 USA. Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA. RP Khazanov, GV (reprint author), NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Natl Space Sci & Technol Ctr, 320 Sparkman Dr, Huntsville, AL 35805 USA. RI Gamayunov, Konstantin/A-8505-2009 OI Gamayunov, Konstantin/0000-0002-8768-8527 NR 43 TC 30 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 JUN PY 2002 VL 107 IS A6 AR 1085 DI 10.1029/2001JA000180 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 610UK UT WOS:000178979400004 ER PT J AU Moretto, T Hesse, M Yahnin, A Ieda, A Murr, D Watermann, JF AF Moretto, T Hesse, M Yahnin, A Ieda, A Murr, D Watermann, JF TI Magnetospheric signature of an ionospheric traveling convection vortex event SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article DE magnetosphere; ionosphere; solar wind; waves; plasma ID WIND DYNAMIC PRESSURE; SOLAR-WIND; IMPULSIVE EVENTS; HIGH-LATITUDES; VORTICES; GENERATION; PLASMA AB [1] We analyze Geotail observations of magnetic field and flow oscillations in the dayside magnetosphere that occurred in direct association with an event of traveling convection vortices observed in the northern high-latitude ionosphere. Geotail was positioned on a magnetic flux tube that mapped very close to the centers of the driving field-aligned currents in the ionosphere. These are the first in situ observations from the source region of such events. The flow signature is seen clearly in the cold, dense plasma population, which the satellite encounters during the event, in addition to a hot magnetospheric (plasma sheet-like) population. This report will present the observations and briefly discuss their implications for our understanding of the traveling convection vortex (TCV) signature. We interpret the event in terms of a boundary wave at the magnetopause. Our analysis suggests that strong gradients in the magnetic field strength or plasma density in the inner magnetosphere should play an important role in this process. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Boston Univ, Ctr Space Phys, Boston, MA 02215 USA. Polar Geophys Inst, Apatity 184200, Russia. Danish Metrol Inst, DK-2100 Copenhagen, Denmark. RP Moretto, T (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RI Hesse, Michael/D-2031-2012; Moretto, Therese/B-6846-2013; Yahnin, Alexander/B-5254-2014 OI Moretto, Therese/0000-0002-2403-5561; Yahnin, Alexander/0000-0003-1650-5436 NR 24 TC 11 Z9 11 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD JUN PY 2002 VL 107 IS A6 AR 1072 DI 10.1029/2001JA000049 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 610UK UT WOS:000178979400017 ER PT J AU Tanskanen, E Pulkkinen, TI Koskinen, HEJ Slavin, JA AF Tanskanen, E Pulkkinen, TI Koskinen, HEJ Slavin, JA TI Substorm energy budget during low and high solar activity: 1997 and 1999 compared SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article DE substorms; energetics; Joule heating ID INTERPLANETARY MAGNETIC-FIELD; GEOMAGNETIC-ACTIVITY; MAGNETOSPHERIC SUBSTORMS; WIND; IONOSPHERE; INSTRUMENT; CONVECTION; STORMS; TAIL AB [1] Substorms during the years 1997 and 1999 are analyzed to examine substorm energy budget just after solar minimum and prior to solar maximum. The energy input from the solar wind into the magnetosphere is estimated in terms of the time integral of Akasofu's epsilon parameter computed from Wind and ACE observations. The ionospheric Joule heating dissipation is estimated using the local electrojet index IL derived from the IMAGE magnetometer array of the MIRACLE ground-based network in the Scandinavian sector. In total, 839 substorms from the midnight sector have been investigated to show that on average the Northern Hemisphere Joule heating accounts for similar to30% of solar wind energy input during 1997 and 1999 substorms. We found that during the active year 1999, there were 26% more substorm events, they were 15% more intense, and they were located at lower latitudes than during 1997. Isolated and stormtime substorms were also examined separately. Mean intensity of isolated substorms was about -350 nT, whereas it was about -670 nT for stormtime events. This study confirms our previous results (for 1997 only) that the amount of Joule dissipation depends on the energy input during the substorm expansion phase. Furthermore, the correlation is best for substorms recorded in the postmidnight sector, indicating that the energy budget and substorms size are largely controlled by processes driven directly by the solar wind. C1 Finnish Meteorol Inst, FIN-00101 Helsinki, Finland. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Helsinki, Dept Phys, Helsinki, Finland. RP Tanskanen, E (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 40 TC 65 Z9 67 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD JUN PY 2002 VL 107 IS A6 AR 1086 DI 10.1029/2001JA900153 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 610UK UT WOS:000178979400003 ER PT J AU Koster, RD Dirmeyer, PA Hahmann, AN Ijpelaar, R Tyahla, L Cox, P Suarez, MJ AF Koster, RD Dirmeyer, PA Hahmann, AN Ijpelaar, R Tyahla, L Cox, P Suarez, MJ TI Comparing the degree of land-atmosphere interaction in four atmospheric general circulation models SO JOURNAL OF HYDROMETEOROLOGY LA English DT Article ID COMMUNITY-CLIMATE-MODEL; SOIL-MOISTURE; REGIONAL CLIMATE; SURFACE BOUNDARY; BIOSPHERE MODEL; GLOBAL CLIMATE; PARAMETERIZATION; CONVECTION; PRECIPITATION; SENSITIVITY AB The strength of the coupling between the land and the atmosphere, which controls, for example, the degree to which precipitation-induced soil moisture anomalies affect the overlying atmosphere and thereby the subsequent generation of precipitation, has been examined and quantified with many atmospheric general circulation models (AGCMs). Generally missing from such studies, however, is an indication of the extent to which the simulated coupling strength is model dependent. Four modeling groups have recently performed a highly controlled numerical experiment that allows an objective intermodel comparison of land-atmosphere coupling strength, focusing on short (weekly down to subhourly) timescales. The experiment essentially consists of an ensemble of 1-month simulations in which each member simulation artificially maintains the same (model specific) time series of surface prognostic variables. Differences in atmospheric behavior between the ensemble members then indicate the degree to which the state of the land surface controls atmospheric processes in that model. A comparison of the four sets of experimental results shows that coupling strength does indeed vary significantly among the AGCMs. C1 NASA, Hydrol Sci Branch, Lab Hydrospher Proc, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Ctr Ocean Land Atmosphere Studies, Calverton, MD USA. Univ Arizona, Inst Atmospher Phys, Tucson, AZ 85721 USA. Univ Wageningen & Res Ctr, Wageningen, Netherlands. Global Sci & Technol Inc, Lanham, MD USA. Met Off, Hadley Ctr Climate Predict & Res, Bracknell, Berks, England. NASA, Climate & Radiat Branch, Atmospheres Lab, Goddard Space Flight Ctr, Greenbelt, MD USA. RP Koster, RD (reprint author), NASA, Hydrol Sci Branch, Lab Hydrospher Proc, Goddard Space Flight Ctr, Code 974, Greenbelt, MD 20771 USA. RI Koster, Randal/F-5881-2012; Dirmeyer, Paul/B-6553-2016; Hahmann, Andrea/B-7541-2015; Cox, Peter/B-3299-2012 OI Koster, Randal/0000-0001-6418-6383; Dirmeyer, Paul/0000-0003-3158-1752; Hahmann, Andrea/0000-0001-8785-3492; NR 47 TC 83 Z9 83 U1 1 U2 19 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 2002 VL 3 IS 3 BP 363 EP 375 DI 10.1175/1525-7541(2002)003<0363:CTDOLA>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 554ME UT WOS:000175738900010 ER PT J AU Patterson, RL Hammoud, A Fialla, P AF Patterson, RL Hammoud, A Fialla, P TI Preliminary evaluation of polyarylate dielectric films for cryogenic applications SO JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS LA English DT Article AB Polymeric materials are used extensively on spacecraft and satellites in electrical power and distribution systems, as thermal blankets and optical surface coatings, as well as mechanical support structures. The reliability of these systems when exposed to the harsh environment of space is very critical to the success of the mission and the safety of the crew in manned-flight ventures. In this work, polyarylate films were evaluated for potential use as capacitor dielectrics and wiring insulation for cryogenic applications. Two grades of the film were characterized in terms of their electrical and mechanical properties before and after exposure to liquid nitrogen (-196 degreesC). The electrical characterization consisted of capacitance and dielectric loss measurements in the frequency range of 50 Hz to 100 kHz, and volume and surface resistivities. The mechanical measurements performed included changes in tensile (Young's modulus, elongation-at-break, and tensile strength) and structural properties (dimensional change, weight, and surface morphology). The preliminary results, which indicate good stability of the polymer after exposure to liquid nitrogen, are presented and discussed. (C) 2002 Kluwer Academic Publishers. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. OSS Grp Inc, NASA, Glenn Res Grp, Cleveland, OH 44135 USA. Tech Innovat GmbH, ISONOVA, A-2355 Wiener Neudorf, Austria. RP Patterson, RL (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 9 TC 1 Z9 1 U1 1 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0957-4522 J9 J MATER SCI-MATER EL JI J. Mater. Sci.-Mater. Electron. PD JUN PY 2002 VL 13 IS 6 BP 363 EP 365 DI 10.1023/A:1015656700768 PG 3 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Engineering; Materials Science; Physics GA 555GB UT WOS:000175785200009 ER PT J AU Troyer, TW Krukowski, AE Miller, KD AF Troyer, TW Krukowski, AE Miller, KD TI LGN input to simple cells and contrast-invariant orientation tuning: An analysis SO JOURNAL OF NEUROPHYSIOLOGY LA English DT Article ID PRIMARY VISUAL-CORTEX; CATS STRIATE CORTEX; LATERAL GENICULATE-NUCLEUS; SIMPLE RECEPTIVE-FIELDS; CORTICAL SIMPLE CELLS; SPATIAL-FREQUENCY; SHUNTING INHIBITION; NETWORK MODEL; AREA 17; SELECTIVITY AB We develop a new analysis of the lateral geniculate nucleus (LGN) input to a cortical simple cell, demonstrating that this input is the sum of two terms, a linear term and a nonlinear term. In response to a drifting grating, the linear term represents the temporal modulation of input, and the nonlinear term represents the mean input. The nonlinear term, which grows with stimulus contrast, has been neglected in many previous models of simple cell response. We then analyze two scenarios by which contrast-invariance of orientation tuning may arise. In the first scenario, at larger contrasts, the nonlinear part of the LGN input, in combination with strong push-pull inhibition, counteracts the nonlinear effects of cortical spike threshold, giving the result that orientation tuning scales with contrast. In the second scenario, at low contrasts, the nonlinear component of LGN input is negligible, and noise smooths the nonlinearity of spike threshold so that the input-output function approximates a power-law function. These scenarios can be combined to yield contrast-invariant tuning over the full range of stimulus contrast. The model clarifies the contribution of LGN nonlinearities to the orientation tuning of simple cells and demonstrates how these nonlinearities may impact different models of contrast-invariant tuning. C1 Univ Maryland, Dept Psychol, Neurosci & Cognit Sci Program, College Pk, MD 20742 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif San Francisco, Dept Physiol, WM Keck Ctr Integrat Neurosci, Sloan Swartz Ctr Theoret Neurobiol, San Francisco, CA 94143 USA. Univ Calif San Francisco, Dept Otolaryngol, WM Keck Ctr Integrat Neurosci, Sloan Swartz Ctr Theoret Neurobiol, San Francisco, CA 94143 USA. RP Troyer, TW (reprint author), Univ Maryland, Dept Psychol, Neurosci & Cognit Sci Program, College Pk, MD 20742 USA. RI Troyer, Todd/C-2817-2011 OI Troyer, Todd/0000-0002-2037-219X FU NEI NIH HHS [EY-11001] NR 45 TC 35 Z9 35 U1 0 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 0022-3077 J9 J NEUROPHYSIOL JI J. Neurophysiol. PD JUN PY 2002 VL 87 IS 6 BP 2741 EP 2752 DI 10.1152/jn.00474.2001 PG 12 WC Neurosciences; Physiology SC Neurosciences & Neurology; Physiology GA 556ZA UT WOS:000175878900011 PM 12037176 ER PT J AU Das, SK Harvey, DJ Biswas, R AF Das, SK Harvey, DJ Biswas, R TI Adaptive load-balancing algorithms using symmetric broadcast networks SO JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING LA English DT Article DE dynamic load balancing; network topology; job migration; performance study ID COMPUTERS AB In a distributed computing environment, it is important to ensure that the processor workloads are adequately balanced. Among numerous load-balancing algorithms. a unique approach given by Das and Prasad defines a symmetric broadcast network (SBN) that provides a robust communication pattern among the processors in a topology-independent manner. In this paper. we propose and analyze three efficient SBN-based dynamic load-balancing algorithms. and implement them on an SGI Origin2000. A thorough experimental study with Poisson-distributed synthetic loads demonstrates that our algorithms are effective in balancing system load. By optimizing completion time and idle time, the proposed algorithms are shown to compare favorably with several existing approaches. (C) 2002 Elsevier Science (USA). C1 NASA, Ames Res Ctr, Adv Supercomp NAS Div, Moffett Field, CA 94035 USA. So Oregon Univ, Dept Comp Sci, Ashland, OR 97520 USA. Univ Texas, Ctr Res Wireless Mobil & Networking, Dept Comp Sci & Engn, Arlington, TX 76019 USA. RP Das, SK (reprint author), NASA, Ames Res Ctr, Adv Supercomp NAS Div, Mail Stop T27A-1, Moffett Field, CA 94035 USA. EM das@cse.uta.edu; harveyd@sou.edu; rbiswas@nas.nasa.gov NR 24 TC 8 Z9 9 U1 2 U2 2 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0743-7315 J9 J PARALLEL DISTR COM JI J. Parallel Distrib. Comput. PD JUN PY 2002 VL 62 IS 6 BP 1042 EP 1068 DI 10.1006/jpdc.2001.1819 PG 27 WC Computer Science, Theory & Methods SC Computer Science GA 569PP UT WOS:000176611300003 ER PT J AU Nakamura, M Chao, Y AF Nakamura, M Chao, Y TI Diagnoses of an eddy-resolving Atlantic Ocean model simulation in the vicinity of the Gulf Stream. Part II: Eddy potential enstrophy and eddy potential vorticity fluxes SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID MEAN FLOW INTERACTION; NORTH-ATLANTIC; BLOCKING; 68-DEGREES-W; FREQUENCY; CIRCULATION; PROPAGATION; SYSTEM; FIELD AB Output of an eddy-resolving model of the North Atlantic is diagnosed in the vicinity of the Gulf Stream (GS), using quasigeostrophic potential vorticity (QGPV), quasigeostrophic potential enstrophy (QGPE), and modified divergent eddy potential vorticity flux, ((V'(h)q') over bar*)(d). A tongue or an elongated island of large mean QGPV along the model GS in the top 1000 m is associated with predominantly downgradient ((V'(h)q') over bar*)(d), suggesting that the horizontal eddy fluxes are balancing a sink of eddy QGPE in most of the tongue or island by converting the mean QGPE into eddy QGPE. Some large upgradient ((V'(h)q') over bar*)(d) is observed to the north of the center of the tongue or island, however, suggesting that some of the eddy fluxes in the northern half of the tongue or island of high QGPV are balancing a source of eddy QGPE there by converting eddy QGPE into the mean QGPE. At the intermediate levels of the model, under the GS, eddy QGPE is small, and the role of eddies appears to be mixed; they are forcing the mean to some extent and dissipating the mean to some extent. At the deep levels, the eddies show predominantly a dissipative role, tending to convert the mean QGPE into eddy QGPE. In the region of large time-mean meanders in the model GS, eddies are found to be reinforcing the meanders in a way very similar to that found in diagnoses of atmospheric blocking, which is essentially a large quasi-stationary meander in the subtropical jet. It suggests that the problem of the excessive meander amplitude in the model may be due to an imbalance between eddy forcing in the vicinity of the separation point and zonal acceleration of the GS simulated by the model or due to an unrealistically strong topographic stationary wave forcing in the model. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chao, Y (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 300-323, Pasadena, CA 91109 USA. NR 27 TC 2 Z9 2 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 JUN PY 2002 VL 32 IS 6 BP 1599 EP 1620 DI 10.1175/1520-0485(2002)032<1599:DOAERA>2.0.CO;2 PG 22 WC Oceanography SC Oceanography GA 555WN UT WOS:000175816400001 ER PT J AU Walsh, EJ Wright, CW Vandemark, D Krabill, WB Garcia, AW Houston, SH Murillo, ST Powell, MD Black, PG Marks, FD AF Walsh, EJ Wright, CW Vandemark, D Krabill, WB Garcia, AW Houston, SH Murillo, ST Powell, MD Black, PG Marks, FD TI Hurricane directional wave spectrum spatial variation at landfall SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID BOTTOM FRICTION; EVOLUTION; SURFACE; OCEAN AB The NASA Scanning Radar Altimeter (SRA) flew aboard one of the NOAA WP-3D hurricane research aircraft to document the sea surface directional wave spectrum in the region between Charleston, South Carolina, and Cape Hatteras, North Carolina, as Hurricane Bonnie was making landfall near Wilmington, North Carolina, on 26 August 1998. Two days earlier, the SRA had documented the hurricane wave field spatial variation in open water when Bonnie was 400 km east of Abaco Island, Bahamas. Bonnie was similar in size during the two flights. The maximum wind speed was lower during the landfall flight (39 m(-1)) than it had been during the first flight (46 m s(-1)). Also, Bonnie was moving faster prior to landfall (9.5 m s(-1)) than when it was encountered in the open ocean (5 m s(-1)). The open ocean wave height spatial variation indicated that Hurricane Bonnie would have produced waves of 10 m height on the shore northeast of Wilmington had it not been for the continental shelf. The gradual shoaling distributed the wave energy dissipation process across the shelf so that the wavelength and wave height were reduced gradually as the shore was approached. The wave height 5 km from shore was about 4 m. Despite the dramatic differences in wave height caused by shoaling and the differences in the wind field and forward speed of the hurricane, there was a remarkable agreement in the wave propagation directions for the various wave components on the two days. This suggests that, in spite of its complexity, the directional wave field in the vicinity of a hurricane may be well behaved and lend itself to be modeled by a few parameters, such as the maximum wind speed, the radii of the maximum and gale force winds, and the recent movement of the storm. C1 NASA, Goddard Space Flight Ctr, Wallops Flight Facil, Wallops Isl, VA USA. USA, Engineer Res & Dev Ctr, Vicksburg, MS USA. NOAA, Atlantic Oceanog & Meteorol Lab, Hurricane Res Div, Miami, FL 33149 USA. RP Walsh, EJ (reprint author), NOAA, Environm Technol Lab, R-ETL1,325 Broadway, Boulder, CO 80305 USA. RI Marks, Frank/A-5733-2011; Powell, Mark/I-4963-2013; Murillo, Shirley/C-3259-2014 OI Marks, Frank/0000-0003-0371-5514; Powell, Mark/0000-0002-4890-8945; Murillo, Shirley/0000-0002-2075-8682 NR 24 TC 29 Z9 30 U1 1 U2 5 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 JUN PY 2002 VL 32 IS 6 BP 1667 EP 1684 DI 10.1175/1520-0485(2002)032<1667:HDWSSV>2.0.CO;2 PG 18 WC Oceanography SC Oceanography GA 555WN UT WOS:000175816400004 ER PT J AU Haine, TWN Hall, TM AF Haine, TWN Hall, TM TI A generalized transport theory: Water-mass composition and age SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID OPTIMUM MULTIPARAMETER ANALYSIS; OCEAN CIRCULATION MODELS; WESTERN BOUNDARY CURRENT; EASTERN NORTH-ATLANTIC; INDIAN-OCEAN; MIXED-LAYER; TRACER; THERMOCLINE; VENTILATION; SECTION AB A general theory to describe and understand advective and diffusive ocean transport is reported. It allows any passive tracer field with an atmospheric source to be constructed by superposing sea surface contributions with a generalized Green's function called the boundary propagator of the passive tracer equation. The boundary propagator has the interpretation of the joint water-mass and transit-time distribution from the sea surface. The theory thus includes the classical oceanographic idea of water-mass analysis and extends it to allow for a distribution of transit times from the sea surface. The joint water-mass and transit-time distribution contains complete information about the transport processes in the flow. It captures this information in a more accessible way than using velocity and diffusivity fields, however, at least for the case of sequestration and transport of dissolved material by the ocean circulation. The boundary propagator is thus the natural quantity to consider when discussing both steady-state and transient ocean tracers, including the inverse problem of interpreting tracer data in terms of ocean circulation. Two constraints on the shape of the transit-time distributions are derived. First, the asymptotic behavior for a steady, or time-averaged, circulation is exponential decay. Second, integrated over the whole ocean, the transit-time distribution from the sea surface cannot increase. The theory is illustrated using a one-dimensional advection-diffusion model, a box model, and a North Atlantic general circulation model. C1 Johns Hopkins Univ, Dept Earth & Planetary Sci, Baltimore, MD 21218 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Haine, TWN (reprint author), Johns Hopkins Univ, Dept Earth & Planetary Sci, 329 Olin Hall, Baltimore, MD 21218 USA. NR 52 TC 82 Z9 84 U1 1 U2 10 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 JUN PY 2002 VL 32 IS 6 BP 1932 EP 1946 DI 10.1175/1520-0485(2002)032<1932:AGTTWM>2.0.CO;2 PG 15 WC Oceanography SC Oceanography GA 555WN UT WOS:000175816400019 ER PT J AU Hall, TM Haine, TWN AF Hall, TM Haine, TWN TI On ocean transport diagnostics: The idealized age tracer and the age spectrum SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID MODEL; GCM AB The idealized age tracer is commonly used to diagnose transport in ocean models and to help interpret ocean measurements. In most studies only the steady-state distribution, the result of many centuries of model integration, has been presented and analyzed. However, in principle the transient solution provides more information about the transport. Here it is shown that this information can be readily interpreted in terms of the ventilation histories of water masses. A simple relationship is derived, valid for stationary transport, between the transient evolution, tau(id) (r, t), of the idealized age tracer and the "age spectrum,'' G (r, t), the distribution of times t since a water mass was last ventilated. Namely, G (r, t) = -partial derivative(tt) tau(id) (r, t). Implications of the relationship are discussed, and the relationship is illustrated with an idealized model. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Johns Hopkins Univ, Dept Earth & Planetary Sci, Baltimore, MD 21218 USA. RP Hall, TM (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 14 TC 29 Z9 29 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD JUN PY 2002 VL 32 IS 6 BP 1987 EP 1991 DI 10.1175/1520-0485(2002)032<1987:OOTDTI>2.0.CO;2 PG 5 WC Oceanography SC Oceanography GA 555WN UT WOS:000175816400023 ER PT J AU Schwuchow, JM Kern, VD White, NJ Sack, FD AF Schwuchow, JM Kern, VD White, NJ Sack, FD TI Conservation of the plastid sedimentation zone in all moss genera with known gravitropic protonemata SO JOURNAL OF PLANT GROWTH REGULATION LA English DT Article DE barbula; fissidens; gravitropism; moss; Physcomitrium; plastid; protonema; sedimentation ID CERATODON-PURPUREUS; PHYSCOMITRELLA-PATENS; FUNARIA-HYGROMETRICA; PHOTOTROPISM; MICROTUBULES; PHYTOCHROME; LIGHT AB Moss protonemata from several species are known to be gravitropic. The characterization of additional gravitropic species would be valuable to identify conserved traits that may relate to the mechanism of gravitropism. In this study, four new species were found to have gravitropic protonemata, Fissidens adianthoides, Fissidens cristatus, Physcomitrium pyriforme, and Barbula unguiculata. Comparison of upright and inverted apical cells of P. pyriforme and Fissidens species showed clear axial sedimentation. This sedimentation is highly regulated and not solely dependent on amyloplast size. Additionally, the protonemal tip cells of these species contained broad subapical zones that displayed lateral amyloplast sedimentation. The conservation of a zone of lateral sedimentation in a total of nine gravitropic moss species from five different orders supports the idea that this sedimentation serves a specialized and conserved function in gravitropism, probably in gravity sensing. C1 Ohio State Univ, Dept Plant Biol, Columbus, OH 43210 USA. NASA, Ames Res Ctr, Lockheed Martin Space Operat, Moffett Field, CA 94035 USA. RP Sack, FD (reprint author), Ohio State Univ, Dept Plant Biol, 1735 Neil Ave, Columbus, OH 43210 USA. EM sack.1@osu.edu NR 25 TC 4 Z9 5 U1 2 U2 6 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0721-7595 EI 1435-8107 J9 J PLANT GROWTH REGUL JI J. Plant Growth Regul. PD JUN PY 2002 VL 21 IS 2 BP 146 EP 155 DI 10.1007/s003440010048 PG 10 WC Plant Sciences SC Plant Sciences GA 568TU UT WOS:000176560700008 PM 12024224 ER PT J AU Li, H Lee, J Libera, MR Lee, WY Kebbede, A Lance, MJ Wang, HY Morscher, GN AF Li, H Lee, J Libera, MR Lee, WY Kebbede, A Lance, MJ Wang, HY Morscher, GN TI Morphological evolution and weak interface development within chemical-vapor-deposited zirconia coating deposited on Hi-Nicalon (TM) fiber SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID TRANSFORMATION; GROWTH; MATRIX; FILMS AB The phase contents and morphology of a ZrO2 fiber coating deposited at 1050degreesC on Hi-Nicalon(TM) by chemical vapor deposition (CVD) were examined as a function of deposition time from 5-120 min. The morphological evolution in the ZrO2 coating was correlated to the development of delamination within the ZrO2 coating. The delamination appears to occur as a result of: (i) continuous formation of tetragonal ZrO2 nuclei on the deposition surface; (ii) martensitic transformation of the tetragonal phase to a monoclinic phase on reaching a critical grain size; and (iii) development of significant compressive hoop stresses because of the volume dilation associated with the transformation. Our observations suggest that it will be of critical importance to further understand and eventually control the nucleation and grain growth behavior of CVD ZrO2 and its phase transformation behavior for its potential applications for composites. C1 Stevens Inst Technol, Dept Chem Biochem & Mat Engn, Hoboken, NJ 07030 USA. Gen Elect Corp Res & Dev, Niskayuna, NY 12309 USA. Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA. Gen Elect Power Syst, Schenectady, NY 12345 USA. NASA, Glenn Res Ctr, Ohio Aerosp Inst, Cleveland, OH 44135 USA. RP Lee, WY (reprint author), Stevens Inst Technol, Dept Chem Biochem & Mat Engn, Hoboken, NJ 07030 USA. RI Lance, Michael/I-8417-2016 OI Lance, Michael/0000-0001-5167-5452 NR 19 TC 21 Z9 21 U1 0 U2 6 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43086-6136 USA SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD JUN PY 2002 VL 85 IS 6 BP 1561 EP 1568 PG 8 WC Materials Science, Ceramics SC Materials Science GA 570PV UT WOS:000176667400034 ER PT J AU Campbell, MR AF Campbell, MR TI A review of surgical care in space SO JOURNAL OF THE AMERICAN COLLEGE OF SURGEONS LA English DT Review ID ENDOSCOPIC SURGERY; TRAUMA SURGERY; IN-SPACE; MICROGRAVITY; WEIGHTLESSNESS; SPACEFLIGHT; PNEUMOTHORAX; MEDICINE; SYSTEM C1 NASA, Med Operat & Wyle Labs, Houston, TX USA. RP Campbell, MR (reprint author), 575 DeShong, Paris, TX 75460 USA. NR 60 TC 20 Z9 20 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 1072-7515 J9 J AM COLL SURGEONS JI J. Am. Coll. Surg. PD JUN PY 2002 VL 194 IS 6 BP 802 EP 812 AR PII S1072-7515(02)01145-6 DI 10.1016/S1072-7515(02)01145-6 PG 11 WC Surgery SC Surgery GA 562NM UT WOS:000176204800020 PM 12081072 ER PT J AU Ao, CO Kong, JA AF Ao, CO Kong, JA TI Analytical approximations in multiple scattering of electromagnetic waves by aligned dielectric spheroids SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID MONTE-CARLO SIMULATIONS; CORRELATED RANDOM DISTRIBUTIONS; DYADIC GREENS-FUNCTIONS; SIZE DISTRIBUTIONS; DENSE MEDIA; PARTICLES; PROPAGATION; SPHERES; SNOW AB In a dense medium, the failure to properly take into account multiple-scattering effects could lead to significant errors, This has been demonstrated in the past from extensive theoretical, numerical, and experimental studies of electromagnetic wave scattering by densely packed dielectric spheres. Here, electromagnetic wave scattering by densely packed dielectric spheroids with aligned orientation is studied analytically through quasi-crystalline approximation (QCA) and QCA with coherent potential (QCA-CP). We assume that the spheroids are electrically small so that single-particle scattering is simple. Low-frequency QCA and QCA-CP solutions are obtained for the average Green's function and the effective permittivity tensor. For QCA-CP, the low-frequency expansion of the uniaxial dyadic Green's function is required. The real parts of the effective permittivities from QCA and QCA-CP are compared with the Maxwell-Garnett mixing formula. QCA gives results identical to those with the mixing formula, while QCA-CP gives slightly higher values. The extinction coefficients from QCA and QCA-CP are compared with results from Monte Carlo simulations. Both QCA and QCA-CP agree well with simulations, although qualitative disagreement is evident at higher fractional volumes. (C) 2002 Optical Society of America. C1 MIT, Elect Res Lab, Cambridge, MA 02139 USA. RP Ao, CO (reprint author), Jet Prop Lab, Mail Stop 283-600,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 39 TC 5 Z9 5 U1 0 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 JUN PY 2002 VL 19 IS 6 BP 1145 EP 1156 DI 10.1364/JOSAA.19.001145 PG 12 WC Optics SC Optics GA 556RJ UT WOS:000175862500011 PM 12049352 ER PT J AU Launius, RD AF Launius, RD TI Brigham Young: Images of a Mormon prophet SO JOURNAL OF THE WEST LA English DT Book Review C1 NASA, Washington, DC USA. RP Launius, RD (reprint author), NASA, Washington, DC USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU J WEST INC PI MANHATTAN PA P O BOX 1009, MANHATTAN, KS 66505-1009 USA SN 0022-5169 J9 J WEST JI J. West PD SUM PY 2002 VL 41 IS 3 BP 98 EP 98 PG 1 WC History SC History GA 572GY UT WOS:000176766900056 ER PT J AU Schwemmer, G Miller, D Wilkerson, T Guerra, D Rallison, R AF Schwemmer, G Miller, D Wilkerson, T Guerra, D Rallison, R TI NASA lidar uses HOEs for lightweight scanning SO LASER FOCUS WORLD LA English DT Article AB To reduce the cost and weight of spaceborne scanning lidar systems, NASA has developed conical scanning telescopes using holographic optical elements. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Utah State Univ, Logan, UT 84322 USA. St Anselm Coll, Dept Phys & Cooperat Engn, Manchester, NH 03102 USA. Ralcon Dev Lab, Paradise, UT 84328 USA. RP Schwemmer, G (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt Rd, Greenbelt, MD 20771 USA. NR 0 TC 3 Z9 3 U1 1 U2 1 PU PENNWELL PUBL CO PI NASHUA PA 98 SPIT BROOK RD, NASHUA, NH 03062-2801 USA SN 0740-2511 J9 LASER FOCUS WORLD JI Laser Focus World PD JUN PY 2002 VL 38 IS 6 BP 141 EP + PG 5 WC Optics SC Optics GA 563FG UT WOS:000176245200039 ER PT J AU DellaCorte, C AF DellaCorte, C TI Beware - Time vampires abound! SO LUBRICATION ENGINEERING LA English DT Editorial Material C1 NASA, Glenn Res Ctr, Washington, DC 20546 USA. RP DellaCorte, C (reprint author), NASA, Glenn Res Ctr, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD JUN PY 2002 VL 58 IS 6 BP 3 EP 3 PG 1 WC Engineering, Mechanical SC Engineering GA 555RC UT WOS:000175806200001 ER PT J AU Parrish, FA Pyle, RL AF Parrish, FA Pyle, RL TI Field comparison of open-circuit scuba to closed-circuit rebreathers for deep mixed-gas diving operations SO MARINE TECHNOLOGY SOCIETY JOURNAL LA English DT Article AB A comparison of open-circuit scuba diving to closed-circuit ("rebreather') diving was conducted while collecting fishery data on black coral beds in Hawaii. Both methodologies used mixed gas from the same ship-based support system. The comparison was based on a series of eight dives, four open-circuit and four closed-circuit. These were used to make a direct-comparison of the gear in a square dive profile, a multilevel profile and two dives of varying profiles. Four general criteria were considered: time requirements for topside equipment preparation and maintenance, consumption of expendables, decompression efficiency, and potential dive durations and bailout capabilities for each of the two technologies. The open-circuit divers required 4 times as much topside equipment preparation as the rebreather, divers, consumed 17 times as much gas, and cost 7 times more in expendables. The open-circuit divers incurred 42% more decompression time for the square profile dives and 70016 more decompression time for the multilevel profile dives than the closed-circuit dive team. Most of the decompression advantage for the closed-circuit team is from the benefit of real-time decompression calculations, but some benefit comes from the breathing gas optimization inherent to rebreathers. For a given mass of equipment, the rebreathers allow for as much as 7.7 times more bottom time, or emergency bailout capability (depending on the chosen depth of the dive), compared with the open-circuit system. C1 Natl Marine Fisheries Serv, Honolulu Lab, Honolulu, HI USA. Bernice P Bishop Museum, Honolulu, HI USA. RP Parrish, FA (reprint author), Natl Marine Fisheries Serv, Honolulu Lab, Honolulu, HI USA. NR 11 TC 7 Z9 7 U1 0 U2 4 PU MARINE TECHNOLOGY SOC INC PI WASHINGTON PA C/O I CLAYION MATTHEWS, 1828 L ST, NW, 9TH FL, WASHINGTON, DC 20036 USA SN 0025-3324 J9 MAR TECHNOL SOC J JI Mar. Technol. Soc. J. PD SUM PY 2002 VL 36 IS 2 BP 13 EP 22 PG 10 WC Engineering, Ocean; Oceanography SC Engineering; Oceanography GA 590BT UT WOS:000177797900002 ER PT J AU Shepard, A Fryer, P Bellingham, J Moore, B Kelly, M Zande, J McCurdy, A Carless, J Ward, M Lemmerman, L AF Shepard, A Fryer, P Bellingham, J Moore, B Kelly, M Zande, J McCurdy, A Carless, J Ward, M Lemmerman, L TI Link 2002 Symposium "Sea and Space Experts Join to Develop Undersea Technologies" held 20-22 May 2002 at NASA Kennedy Space Center, Cape Canaveral, Florida SO MARINE TECHNOLOGY SOCIETY JOURNAL LA English DT Article; Proceedings Paper CT 2nd Link Project Workshop CY MAY 20-22, 2002 CL KENNEDY, FLORIDA C1 Univ N Carolina, Natl Undersea Res Ctr, Wilmington, NC 28401 USA. Univ Hawaii, Honolulu, HI 96822 USA. Monterey Bay Aquarium & Res Inst, Monterey, CA USA. Natl Undersea Res Program, Silver Spring, MD USA. NOAA, Off Ocean Explorat, Silver Spring, MD USA. Marine Adv Technol & Educ Ctr, Monterey, CA USA. NASA, Oceanog Outreach, Washington, DC 20546 USA. Sci Tek Commun, Orlando, FL USA. NASA, Jet Prop Lab, Pasadena, CA USA. RP Shepard, A (reprint author), Univ N Carolina, Natl Undersea Res Ctr, Wilmington, NC 28401 USA. NR 1 TC 3 Z9 3 U1 1 U2 1 PU MARINE TECHNOLOGY SOC INC PI WASHINGTON PA C/O I CLAYION MATTHEWS, 1828 L ST, NW, 9TH FL, WASHINGTON, DC 20036 USA SN 0025-3324 J9 MAR TECHNOL SOC J JI Mar. Technol. Soc. J. PD SUM PY 2002 VL 36 IS 2 BP 70 EP 77 PG 8 WC Engineering, Ocean; Oceanography SC Engineering; Oceanography GA 590BT UT WOS:000177797900012 ER PT J AU Benner, LAM Ostro, SJ Nolan, MC Margot, JL Giorgini, JD Hudson, RS Jurgens, RF Slade, MA Howell, ES Campbell, DB Yeomans, DK AF Benner, LAM Ostro, SJ Nolan, MC Margot, JL Giorgini, JD Hudson, RS Jurgens, RF Slade, MA Howell, ES Campbell, DB Yeomans, DK TI Radar observations of asteroid 1999 JM8 SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID SPIN-STATE; ARECIBO; GOLDSTONE; OBJECTS AB We report results of delay-Doppler observations of 1999 JM8 with the Goldstone 8560 MHz (3.5 cm) and Arecibo 2380 MHz (13 cm) radars over 18 days in July-August 1999. The images place thousands of pixels on the asteroid and achieve range resolutions as fine as 15 m/pixel. The images reveal an asymmetric, irregularly shaped object with a typical overall dimension within 20% of 7 km. If we assume that 1999 JM8's effective diameter is 7 km, then the absolute magnitude, 15.15, and the average Goldstone radar cross section, 2.49 km(2), correspond to optical and radar albedos of 0.02 and 0.06, establishing that 1999 JM8 is a dark object at optical and radar wavelengths. The asteroid is in a non-principal axis spin state that, although not yet well determined, has a dominant periodicity of similar to7 days. However, images obtained between July 31 and August 9 show apparent regular rotation of features from day to day, suggesting that the rotation state is not far from principal axis rotation. 1999 JM8 has regions of pronounced topographic relief, prominent facets several kilometers in extent, numerous crater-like features between similar to100 m and 1.5 km in diameter, and features whose structural nature is peculiar. Arecibo images provide the strongest evidence to date for a circular polarization ratio feature on any asteroid. Combined optical and radar observations from April 1990 to December 2000 permit computation of planetary close approach times to within +/- 10 days over the interval from 293 to at least 2907, one of the longest spans for any potentially hazardous asteroid. Integration of the orbit into the past and future shows close approaches to Earth, Mars, Ceres, and Vesta, but the probability of the object impacting Earth is zero for at least the next nine centuries. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Astron & Ionosphere Ctr, Arecibo Observ, Arecibo, PR 00612 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. Washington State Univ, Sch Elect Engn & Comp Sci, Pullman, WA 99164 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Ithaca, NY 14853 USA. RP Benner, LAM (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 23 TC 14 Z9 15 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD JUN PY 2002 VL 37 IS 6 BP 779 EP 792 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 566HC UT WOS:000176420100001 ER PT J AU Westphal, AJ Snead, C Borg, J Quirico, E Raynal, PI Zolensky, ME Ferrini, G Colangeli, L Palumbo, P AF Westphal, AJ Snead, C Borg, J Quirico, E Raynal, PI Zolensky, ME Ferrini, G Colangeli, L Palumbo, P TI Small hypervelocity particles captured in aerogel collectors: Location, extraction, handling and storage SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID CROSS-SECTIONS; IONS AB It has now been about a decade since the first demonstrations that hypervelocity particles could be captured, partially intact, in aerogel collectors. But the initial promise of a bonanza of partially-intact extraterrestrial particles, collected in space, has yet to materialize. One of the difficulties that investigators have encountered is that the location, extraction, handling and analysis of very small (10 mum and less) grains, which constitute the vast majority of the captured particles, is challenging and burdensome. Furthermore, current extraction techniques tend to be destructive over large areas of the collectors. Here we describe our efforts to alleviate some of these difficulties. We have learned how to rapidly and efficiently locate captured particles in aerogel collectors, using an automated microscopic scanning system originally developed for experimental nuclear astrophysics. We have learned how to precisely excavate small access tunnels and trenches using an automated micromanipulator and glass microneedles as tools. These excavations are only destructive to the collector in a very small area-this feature may be particularly important for excavations in the precious Stardust collectors. Using actuatable silicon microtweezers, we have learned how to extract and store "naked" particles-essentially free of aerogel-as small as 3 mum in size. We have also developed a technique for extracting particles, along with their terminal tracks, still embedded in small cubical aerogel blocks. We have developed a novel method for storing very small particles in etched nuclear tracks. We have applied these techniques to the extraction and storage of grains captured in aerogel collectors (Particle Impact Experiment, Orbital Debris Collector Experiment, Comet-99) in low Earth orbit. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Paris 11, Inst Astrophys Spatiale, F-91405 Orsay, France. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Osserv Astron Capodimonte, INAF, I-80131 Naples, Italy. Univ Parthenope, I-80133 Naples, Italy. RP Westphal, AJ (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RI quirico, eric/K-9650-2013 OI quirico, eric/0000-0003-2768-0694 NR 21 TC 18 Z9 18 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD JUN PY 2002 VL 37 IS 6 BP 855 EP 865 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 566HC UT WOS:000176420100006 ER PT J AU Arias, JI Morrell, NI Barba, RH Bosch, GL Grosso, M Corcoran, M AF Arias, JI Morrell, NI Barba, RH Bosch, GL Grosso, M Corcoran, M TI The massive double-lined O-type binary HD 165052 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE binaries : general; stars : early-type; stars : individual : HD 165052; X-rays : stars ID COLLIDING-WIND BINARIES; SPECTRAL CLASSIFICATION; SPACE DISTRIBUTION; MAIN-SEQUENCE; STARS; EMISSION; SEARCH; ORBITS AB We present a new optical spectroscopic study of the O-type binary HD 165052 based on high- and intermediate-resolution CCD observations. We re-investigated the spectral classification of the binary components, obtaining spectral types of O6.5 V and O7.5 V for the primary and secondary, respectively, finding that both stars display weak C iiilambda 5696 emission in their spectra. We also determined a radial-velocity orbit for HD 165052 with a period of 2.95510+/-0.00001 d, and semi-amplitudes of 94.8 and 104.7+/-0.5 km s(-1), resulting in a mass ratio Q =0.9 From a comparison with previous radial-velocity determinations, we found evidence of apsidal motion in the system. Several signatures of wind-wind collision, such as phase-locked variability of the X-ray flux and the Struve-Sahade effect, are also considered. It was also found that the reddening in the region should be normal, in contrast with previous determinations. C1 Univ Nacl La Plata, Fac Ciencias Astron & Geofis, La Plata, Buenos Aires, Argentina. Complejo Astron El Leoncito, RA-5400 San Juan, Argentina. Univ Space Res Assoc, Seabrook, MD 20706 USA. NASA, Goddard Space Flight Ctr, Lab High Energy Astrophys, Greenbelt, MD 20771 USA. RP Arias, JI (reprint author), Univ Nacl La Plata, Fac Ciencias Astron & Geofis, Paseo Bosque S-N,B1900FWA, La Plata, Buenos Aires, Argentina. RI Barba, Rodolfo/P-4649-2014 OI Barba, Rodolfo/0000-0003-1086-1579 NR 35 TC 8 Z9 8 U1 0 U2 0 PU BLACKWELL PUBLISHING LTD PI OXFORD PA 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUN PY 2002 VL 333 IS 1 BP 202 EP 210 DI 10.1046/j.1365-8711.2002.05404.x PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 560AK UT WOS:000176058900017 ER PT J AU Halverson, JB Rickenbach, T Roy, B Pierce, H Williams, E AF Halverson, JB Rickenbach, T Roy, B Pierce, H Williams, E TI Environmental characteristics of convective systems during TRMM-LBA SO MONTHLY WEATHER REVIEW LA English DT Article ID TOGA COARE; SQUALL LINES; RADAR; MORPHOLOGY; MIDLATITUDE; SHEAR AB In this paper, data collected from 51 days of continual upper-atmospheric soundings and the Tropical Ocean Global Atmosphere (TOGA) radar at Anglo-Brazilian Amazonian Climate Observation Study (ABRACOS) Hill during the Tropical Rainfall Measuring Mission component of the Brazilian Large Scale Biosphere-Atmosphere (TRMM-LBA) experiment are used to describe the mean thermodynamic and kinematic airmass properties of wet season convection over Rondonia, Brazil. Distinct multiday easterly and westerly lower-tropospheric wind regimes occurred during the campaign with contrasting airmass characteristics. Westerly wind periods featured modest CAPE (1000 J kg(-1)), moist conditions (>90% RH) extending through 700 mb, and shallow (900 mb) speed shear on the order of 10(-4) s(-1). This combination of characteristics promoted convective systems that featured a relatively large fraction of stratiform rainfall and weak convection nearly devoid of lightning. In contrast, easterly regime convective systems were more strongly electrified and featured larger convective rain rates and reduced stratiform rainfall fraction. These systems formed in an environment with larger CAPE (1500 J kg(-1)), drier lower- and midlevel humidities (<80% RH), and a wind shear layer that was both stronger (10(-3) s(-1)) and deeper (700 mb). The time series of low- and midlevel averaged humidity exhibited marked variability between westerly and easterly regimes and was characterized by low- frequency (i.e., multiday to weekly) variations. In addition to its importance in stratiform rain formation, the humidity content directly influenced cloud cover and, thus, the degree of thermal instability present during regimes. The synoptic-scale origins of these moisture fluctuations are examined. The results reported herein provide an environmental context for ongoing dual-Doppler analyses and numerical modeling case studies of individual TRMM-LBA convective systems. C1 NASA, Goddard Space Flight Ctr, JCET,UMBC, Mesoscale Proc Branch, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. Sci Syst & Applicat Inc, Lanham, MD USA. MIT, Ralph M Parsons Lab, Cambridge, MA 02139 USA. RP Halverson, JB (reprint author), NASA, Goddard Space Flight Ctr, JCET,UMBC, Mesoscale Proc Branch, Code 912, Greenbelt, MD 20771 USA. NR 33 TC 48 Z9 53 U1 2 U2 3 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 2002 VL 130 IS 6 BP 1493 EP 1509 DI 10.1175/1520-0493(2002)130<1493:ECOCSD>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 546HF UT WOS:000175268100004 ER PT J AU Braun, SA AF Braun, SA TI A cloud-resolving simulation of Hurricane Bob (1991): Storm structure and eyewall buoyancy SO MONTHLY WEATHER REVIEW LA English DT Article ID TROPICAL-CYCLONE MOTION; CONVECTIVE-SCALE CHARACTERISTICS; SEA INTERACTION THEORY; WESTERN NORTH PACIFIC; VORTEX ROSSBY-WAVES; INNER-CORE; ANDREW 1992; EXTRATROPICAL TRANSITION; MATURE HURRICANES; VERTICAL MOTIONS AB A numerical simulation of Hurricane Bob (1991) is conducted using the Pennsylvania State University-National Center for Atmospheric Research fifth-generation Mesoscale Model (MM5) with a horizontal grid spacing of 1.3 km on the finest nested mesh. The model produces a realistic hurricane that intensifies slowly during the period of finescale simulation. The time-averaged structure is characterized by a wavenumber-1 asymmetry with maximum low-level vertical motions and near-surface inflow in the left-front quadrant relative to the nearly aligned storm motion and mean wind shear vectors and strong outflow just above the boundary layer collocated with the updrafts. Instantaneous distributions of radial flow, vertical motion, and precipitation are strongly modified by a wavenumber-2 asymmetry that rotates cyclonically around the center at about half the speed of the mean tangential winds, consistent with the theory for vortex Rossby waves. The time-mean asymmetric vertical motion is comprised of small-scale convective updrafts that at any given time cover only a small portion of the eyewall area, but account for a majority of the updraft mass flux, consistent with the concept of hot towers. Calculations of buoyancy indicate that eyewall updrafts are positively buoyant with respect to an environment that includes the vortex-scale warm core structure. Air parcels entering the eyewall in the boundary layer are initially accelerated upward by vertical pressure gradient forces, but once above the boundary layer, they accelerate upward because of buoyancy forces. The buoyancy is typically achieved along outward-sloping paths in a layer characterized by conditional symmetric instability. However, the strong low-level outflow above the boundary layer in the eyewall displaces rising parcels out from under the warm core so that they become unstable to vertical displacements. Consequently, the eyewall updrafts are generally the result of convective rather than symmetric instability. A key source for the buoyancy is the energy gained from surface fluxes of moisture and heat by select parcels that originate from outside of the eyewall in the lowest part of the boundary layer, penetrate furthest into the eye, and then accelerate outward sharply while rising out of the boundary layer. Occasionally, air within the eye is drawn into the eyewall updrafts, suggesting episodic rather than continuous venting of the eye air into the eyewall. C1 NASA, Goddard Space Flight Ctr, Mesoscale Atmospher Proc Branch, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Braun, SA (reprint author), NASA, Goddard Space Flight Ctr, Mesoscale Atmospher Proc Branch, Atmospheres Lab, Code 912, Greenbelt, MD 20771 USA. NR 63 TC 107 Z9 115 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 2002 VL 130 IS 6 BP 1573 EP 1592 DI 10.1175/1520-0493(2002)130<1573:ACRSOH>2.0.CO;2 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 546HF UT WOS:000175268100008 ER PT J AU Eklund, PC Pradhan, BK Kim, UJ Xiong, Q Fischer, JE Friedman, AD Holloway, BC Jordan, K Smith, MW AF Eklund, PC Pradhan, BK Kim, UJ Xiong, Q Fischer, JE Friedman, AD Holloway, BC Jordan, K Smith, MW TI Large-scale production of single-walled carbon nanotubes using ultrafast pulses from a free electron laser SO NANO LETTERS LA English DT Article ID RAMAN-SCATTERING; DIAMETER; GROWTH; FIBERS; GAS AB We report the first use of ultrafast (subpicosecond) laser pulses for large-scale production of single wall carbon nanotubes (SWNT's) by the pulsed laser vaporization (PLV) technique. Very high production rates were achieved; using only 20% of the nominal average power of the 1 kW Jefferson Lab free electron laser (Jlab FEL), carbon soots rich in high quality bundles of SWNT's were produced at similar to1.5 g/h. Accordingly, a novel PLV geometry employing a spinning target and a sonic shearing jet of 1000 degreesC argon was developed to accommodate the highly energetic Jlab FEL ablation plume. Samples were characterized by scanning electron microscope, atomic force microscopy, transmission electron microscopy, temperature programmed oxidation, and Raman spectroscopy. C1 Penn State Univ, Dept Phys, University Pk, PA 16802 USA. Univ Penn, Dept Mat Sci & Engn, Philadelphia, PA 19104 USA. Univ Penn, LRSM, Philadelphia, PA 19104 USA. Coll William & Mary, Dept Appl Sci, Williamsburg, VA 23187 USA. Thomas Jefferson Natl Accelerator Facil, Newport News, VA 23606 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Penn State Univ, Dept Phys, Univ Pk, University Pk, PA 16802 USA. EM pce3@psu.edu RI Xiong, Qihua/A-4979-2011 OI Xiong, Qihua/0000-0002-2555-4363 NR 21 TC 55 Z9 56 U1 2 U2 20 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1530-6984 EI 1530-6992 J9 NANO LETT JI Nano Lett. PD JUN PY 2002 VL 2 IS 6 BP 561 EP 566 DI 10.1021/nl025515y PG 6 WC Chemistry, Multidisciplinary; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Chemistry; Science & Technology - Other Topics; Materials Science; Physics GA 562KC UT WOS:000176195100002 ER PT J AU Halicioglu, T Jaffe, RL AF Halicioglu, T Jaffe, RL TI Solvent effect on functional groups attached to edges of carbon nanotubes SO NANO LETTERS LA English DT Article ID CHEMICAL FORCE MICROSCOPY; SELF-ASSEMBLED MONOLAYERS AB Molecular dynamics calculations are carried out to investigate the effect exerted by aqueous solutions on the equilibrium structure and configuration of functional groups attached to carbon nanotubes. In this study, structures of polar and nonpolar functional groups in water are analyzed. Energy changes associated with configurational transformations of functional groups (from folded to extended forms) in water are calculated. Results indicate that polar functional groups are energetically more stable in extended configurations. Nonpolar functional groups, on the other hand, prefer to remain folded. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Jaffe, RL (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 8 TC 11 Z9 11 U1 0 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1530-6984 J9 NANO LETT JI Nano Lett. PD JUN PY 2002 VL 2 IS 6 BP 573 EP 575 DI 10.1021/nl0255449 PG 3 WC Chemistry, Multidisciplinary; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Chemistry; Science & Technology - Other Topics; Materials Science; Physics GA 562KC UT WOS:000176195100004 ER PT J AU Wei, CY Srivastava, D Cho, KJ AF Wei, CY Srivastava, D Cho, KJ TI Thermal expansion and diffusion coefficients of carbon nanotube-polymer composites SO NANO LETTERS LA English DT Article ID MOLECULAR-DYNAMICS; SIMULATION; FIBERS AB Classical molecular dynamics (MD) simulations employing Brenner potential for intra-nanotube interactions and van der Waals forces for polymer-nanotube interface are used to investigate the thermal expansion and diffusion characteristics of carbon nanotube-polyethylene composites. Additions of carbon nanotubes to a polymer matrix are found to increase the glass transition temperature T-g, and thermal expansion and diffusion coefficients in the composite above T-g. These findings could have implications in CNT composite processing, coating and painting applications. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Stanford Univ, Dept Mech Engn, Stanford, CA 94305 USA. RP Wei, CY (reprint author), NASA, Ames Res Ctr, MS 229-1, Moffett Field, CA 94035 USA. NR 23 TC 240 Z9 248 U1 7 U2 73 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1530-6984 J9 NANO LETT JI Nano Lett. PD JUN PY 2002 VL 2 IS 6 BP 647 EP 650 DI 10.1021/nl025554+ PG 4 WC Chemistry, Multidisciplinary; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Chemistry; Science & Technology - Other Topics; Materials Science; Physics GA 562KC UT WOS:000176195100018 ER PT J AU Delzeit, L Nguyen, CV Stevens, RM Han, J Meyyappan, M AF Delzeit, L Nguyen, CV Stevens, RM Han, J Meyyappan, M TI Growth of carbon nanotubes by thermal and plasma chemical vapour deposition processes and applications in microscopy SO NANOTECHNOLOGY LA English DT Article; Proceedings Paper CT 2nd International Conference on Trends in Nanotechnology (TNT2001) CY SEP 03-07, 2001 CL SEGOVIA, SPAIN SP Univ Autonoma Madrid, Consejo Superior Investigac Cient, CMP Cient, Univ Carlos III Madrid, Univ SEK, Natl Sci Fdn, NASA, World Sci, Motorola, Inst Phys Publishing ID CATALYTIC GROWTH; PATTERNED GROWTH; METAL PARTICLES; NANOFIBERS; ARRAYS; CVD AB Single-walled carbon nanotubes (SWNTs) are grown from a methane feedstock by thermal chemical vapour deposition (CVD). An ethylene-hydrogen plasma generated in an inductively coupled plasma reactor primarily yields multi-walled carbon nanotubes and thicker fibres. In both cases, an iron catalyst layer and an aluminium underlayer are deposited by ion beam sputtering onto silicon wafers for the growth of carbon nanotubes (CNTs). The plasma process provides well-aligned multi-walled nanofibres useful for fabrication of electrodes and sensors and further tip functionalization whereas thermal CVD produces a mat of SWNT ropes. In addition, CNTs grown at the tips of silicon cantilevers are demonstrated to be ideal for high-resolution imaging of biological samples and simulated Mars dust grains using atomic force microscopy. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. ELORET Corp, Sunnyvale, CA 94087 USA. RP NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 29 TC 40 Z9 40 U1 4 U2 24 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0957-4484 EI 1361-6528 J9 NANOTECHNOLOGY JI Nanotechnology PD JUN PY 2002 VL 13 IS 3 BP 280 EP 284 AR PII S0957-4484(02)30996-6 DI 10.1088/0957-4484/13/3/308 PG 5 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied SC Science & Technology - Other Topics; Materials Science; Physics GA 568NU UT WOS:000176549200009 ER PT J AU Assad, C Hartmann, MJ Paulin, MG AF Assad, C Hartmann, MJ Paulin, MG TI Control of a simulated arm using a novel combination of cerebellar learning mechanisms SO NEUROCOMPUTING LA English DT Article; Proceedings Paper CT 10th Computational Neuroscience Meeting (CSN 01) CY JUL, 2001 CL MONTEREY, CALIFORNIA DE cerebellum; cerebellar learning; dynamic state estimation; sensorimotor control ID GRANULE CELL; CORTEX; SYSTEM AB We present a model of cerebellar cortex that combines two types of learning: feedforward predictive association based on local Hebbian-type learning between granule cell ascending branch and parallel fiber inputs, and reinforcement learning with feedback error correction based on climbing fiber activity. The model is motivated by recent physiological and anatomical evidence and has more computational capacity than previous functional models of cerebellum. To demonstrate the model's utility, we simulated the control of a simple virtual arm. The model successfully learned to control the timing of release for the arm during a target-throwing task. (C) 2002 Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Otago, Dept Zool, Dunedin, New Zealand. Univ Otago, Ctr Neurosci, Dunedin, New Zealand. RP Assad, C (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 303-300, Pasadena, CA 91109 USA. RI Hartmann, Mitra/A-8150-2008; Hartmann, Mitra/B-6766-2009 NR 17 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0925-2312 J9 NEUROCOMPUTING JI Neurocomputing PD JUN PY 2002 VL 44 BP 275 EP 283 AR PII S0925-2312(02)00351-X DI 10.1016/S0925-2312(02)00351-X PG 9 WC Computer Science, Artificial Intelligence SC Computer Science GA 573PC UT WOS:000176839200043 ER PT J AU Ning, CZ AF Ning, CZ TI Self-sustained ultrafast pulsation in coupled vertical-cavity surface-emitting lasers SO OPTICS LETTERS LA English DT Article ID SEMICONDUCTOR-LASERS; PHASED-ARRAY; FREQUENCY; LOCKING AB We demonstrate that high-frequency, narrow-band, self-pulsating intensity oscillation can be generated with two coupled vertical-cavity surface-emitting lasers (VCSELs) and that such oscillation is greatly enhanced by collecting one of the two field lobes, The coupled VCSELs provide an ideal source for high-repetition-rate (over 40 GHz). sinusoidallike modulated laser light with Gaussian-like near- and far-field profiles. We also show that the modulation frequency can be tuned by inter-VCSEL separation or by a de bias level. (C) 2002 Optical Society of America. C1 NASA, Ames Res Ctr, Computat Quantum Optoelect, Moffett Field, CA 94035 USA. RP Ning, CZ (reprint author), NASA, Ames Res Ctr, Computat Quantum Optoelect, Mail Stop 229-1, Moffett Field, CA 94035 USA. RI Ning, C. Z./D-4699-2009 OI Ning, C. Z./0000-0003-4583-8889 NR 19 TC 4 Z9 4 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 2002 VL 27 IS 11 BP 912 EP 914 DI 10.1364/OL.27.000912 PG 3 WC Optics SC Optics GA 556VU UT WOS:000175870300010 PM 18026321 ER PT J AU Smialek, JL Auping, JV AF Smialek, JL Auping, JV TI COSP for windows-strategies for rapid analyses of cyclic-oxidation behavior SO OXIDATION OF METALS LA English DT Article DE cyclic oxidation; weight-change curves; growth kinetics; spalling; computer models ID MODEL AB COSP is a publicly available computer Program that models the Cyclic Oxidation weight gain and Spallation process. Inputs to the model include the selection of an oxidation-growth law and a spalling geometry, plus oxide phase, growth rate, spall constant, and cycle-duration parameters. Output includes weight change, the amounts of retained and spalled oxide, the total oxygen and metal consumed, and the terminal rates of weight loss and metal consumption. The present version is an updated Windows-based program, allowing greater compatibility with current PC operating systems. Viewing of multiple models and model fits to experimental data are enabled by an instant plotting feature and iterative modifications. Families of model curves are presented, which readily show the sensitivity to all the input parameters as well as the behavior of different growth laws and spalling modes. The cyclic behavior of NiAl and a complex superalloy are shown to be properly fitted by model curves. However, caution is always advised regarding the uniqueness claimed for any specific set of input parameters. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Smialek, JL (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. EM James.L.Smialek@grc.nasa.gov NR 25 TC 36 Z9 38 U1 1 U2 3 PU SPRINGER/PLENUM PUBLISHERS PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0030-770X J9 OXID MET JI Oxid. Met. PD JUN PY 2002 VL 57 IS 5-6 BP 559 EP 581 DI 10.1023/A:1015308606869 PG 23 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA 549NN UT WOS:000175450600010 ER PT J AU Tumer, K Ghosh, J AF Tumer, K Ghosh, J TI Robust combining of disparate classifiers through order statistics SO PATTERN ANALYSIS AND APPLICATIONS LA English DT Article DE classification error; ensembles; order statistics; robust statistics; trimmed means ID NEURAL NETWORKS; CLASSIFICATION; VARIANCE; BIAS AB Integrating the outputs of multiple classifiers via combiners or meta-learners has led to substantial improvements in several difficult pattern recognition problems. In this article, we investigate a family of combiners based on order statistics, for robust handling of situations where there are large discrepancies in performance of individual classifiers. Based on a mathematical modelling of how the decision boundaries are affected by order statistic combiners, we derive expressions for the reductions in error expected when simple output combination methods based on the median, the maximum and in general, the ith order statistic, are used. Furthermore, we analyse the trim and spread combiners, both based on linear combinations of the ordered classifier outputs, and show that in the presence of uneven classifier performance, they often provide substantial gains over both linear and simple order statistics combiners. Experimental results on both real world data and standard public domain data sets corroborate these findings. C1 NASA, Ames Res Ctr, Computat Sci Div, Moffett Field, CA 94035 USA. Univ Texas, Dept Elect & Comp Engn, Austin, TX 78712 USA. RP Tumer, K (reprint author), NASA, Ames Res Ctr, Computat Sci Div, MS 269-4, Moffett Field, CA 94035 USA. NR 33 TC 9 Z9 10 U1 0 U2 0 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 1433-7541 J9 PATTERN ANAL APPL JI Pattern Anal. Appl. PD JUN PY 2002 VL 5 IS 2 BP 189 EP 200 DI 10.1007/s100440200017 PG 12 WC Computer Science, Artificial Intelligence SC Computer Science GA 576EL UT WOS:000176989800010 ER PT J AU Eriksson, M Litzen, U Wahlgren, GM Leckrone, DS AF Eriksson, M Litzen, U Wahlgren, GM Leckrone, DS TI Spectral data for TaII with application to the tantalum abundance in chi Lupi SO PHYSICA SCRIPTA LA English DT Article ID HYPERFINE-STRUCTURE; STAR; ELEMENTS AB Tantalum spectra, emitted from a hollow cathode, have been recorded with a Fourier transform spectrometer in the region 2000-5000 Angstrom. The observed hyperfine patterns of Ta II have been analyzed, yielding center-of-gravity wavelengths for 199 lines and hyperfine constants for 38 even and 97 odd levels of Ta II. Improved energy level values have been derived. The laboratory data have been used for a study of the tantalum abundance of the CP star chi Lupi. C1 Lund Univ, Lund Observ, SE-22100 Lund, Sweden. Univ Coll Kalmar, SE-39182 Kalmar, Sweden. NASA, Goddard Space Flight Ctr, Lab Astron & Solar Phys, Greenbelt, MD 20771 USA. RP Eriksson, M (reprint author), Lund Univ, Lund Observ, Box 43, SE-22100 Lund, Sweden. NR 22 TC 14 Z9 14 U1 0 U2 2 PU ROYAL SWEDISH ACAD SCIENCES PI STOCKHOLM PA PUBL DEPT BOX 50005, S-104 05 STOCKHOLM, SWEDEN SN 0031-8949 J9 PHYS SCRIPTA JI Phys. Scr. PD JUN PY 2002 VL 65 IS 6 BP 480 EP 489 DI 10.1238/Physica.Regular.065a00480 PG 10 WC Physics, Multidisciplinary SC Physics GA 570WA UT WOS:000176681300004 ER PT J AU Khakoo, MA Wrkich, J Larsen, M Kleiban, G Kanik, I Trajmar, S Brunger, MJ Teubner, PJO Crowe, A Fontes, CJ Clark, REH Zeman, V Bartschat, K Madison, DH Srivastava, R Stauffer, AD AF Khakoo, MA Wrkich, J Larsen, M Kleiban, G Kanik, I Trajmar, S Brunger, MJ Teubner, PJO Crowe, A Fontes, CJ Clark, REH Zeman, V Bartschat, K Madison, DH Srivastava, R Stauffer, AD TI Differential cross sections and cross-section ratios for the electron-impact excitation of the neon 2p(5)3s configuration SO PHYSICAL REVIEW A LA English DT Article ID OPTICAL OSCILLATOR-STRENGTHS; DISTORTED-WAVE CALCULATION; RARE-GASES; POLARIZATION CORRELATION; INCIDENT ENERGIES; NOBLE-GASES; SCATTERING; ARGON; KRYPTON; STATES AB Electron-impact differential cross-section measurements for the excitation of the 2p(5)3s configuration of Ne are reported. The Ne cross sections are obtained using experimental differential cross sections for the electron-impact excitation of the n=2 levels of atomic hydrogen [Khakoo , Phys. Rev. A 61, 012701-1 (1999)], and existing experimental helium differential cross-section measurements, as calibration standards. These calibration measurements were made using the method of gas mixtures (Ne and H followed by Ne and He), in which the gas beam profiles of the mixed gases are found to be the same within our experimental errors. We also present results from calculations of these differential cross sections using the R-matrix and unitarized first-order many-body theory, the distorted-wave Born approximation, and relativistic distorted-wave methods. Comparison with available experimental differential cross sections and differential cross-section ratios is also presented. C1 Calif State Univ Fullerton, Dept Phys, Fullerton, CA 92834 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Flinders Univ S Australia, Adelaide, SA 5001, Australia. Univ Newcastle Upon Tyne, Dept Phys, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England. Los Alamos Natl Lab, Appl Theoret & Computat Phys Div, Los Alamos, NM 87544 USA. Int Atom Agcy, Atom & Mol Data Unit, A-1400 Vienna, Austria. Univ Toronto, Chem Phys Theory Grp, Toronto, ON M5S 3H6, Canada. Drake Univ, Dept Phys & Astron, Des Moines, IA 50311 USA. Univ Missouri, Dept Phys, Rolla, MO 65401 USA. Indian Inst Technol Roorkee, Dept Phys, Roorkee 247667, Uttar Pradesh, India. York Univ, Dept Phys & Astron, N York, ON M3J 1P3, Canada. RP Khakoo, MA (reprint author), Calif State Univ Fullerton, Dept Phys, Fullerton, CA 92834 USA. RI Bartschat, Klaus/I-2527-2012; OI Brunger, Michael/0000-0002-7743-2990 NR 53 TC 26 Z9 29 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 JUN PY 2002 VL 65 IS 6 AR 062711 DI 10.1103/PhysRevA.65.062711 PG 24 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 572FT UT WOS:000176763600064 ER PT J AU Strekalov, VN Strekalov, DV AF Strekalov, VN Strekalov, DV TI Thermodesorption of impurities from a transparent crystal surface SO PHYSICAL REVIEW A LA English DT Article ID DESORPTION AB Thermodesorption of impurities from a dielectric crystal surface can be stimulated by absorption of high-frequency phonons, e.g., Debye phonons. We study this process in the framework of a truncated-harmonic-oscillator model and find the desorption rate by methods of quantum statistics. In this paper, we present the estimates for the mean desorption rates that are simple, realistic, and at the same time allow us to predict a series of physical effects in thermodesorption processes. C1 Moscow State Univ Technol STANKIN, Dept Phys, Moscow 101472, Russia. JPL, Pasadena, CA 91109 USA. RP Strekalov, VN (reprint author), Moscow State Univ Technol STANKIN, Dept Phys, 3A Vadkovsky Per, Moscow 101472, Russia. NR 17 TC 2 Z9 2 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD JUN PY 2002 VL 65 IS 6 AR 062901 DI 10.1103/PhysRevA.65.062901 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 572FT UT WOS:000176763600072 ER PT J AU Ahmed, M Amann, JF Barlow, D Black, K Bolton, RD Brooks, ML Carius, S Chen, YK Chernyshev, A Concannon, HM Cooper, MD Cooper, PS Crocker, J Dittmann, JR Dzemidzic, M Empl, A Fisk, RJ Fleet, E Foreman, W Gagliardi, CA Haim, D Hallin, A Hoffman, CM Hogan, GE Hughes, EB Hungerford, EV Jui, CCH Kim, GJ Knott, JE Koetke, DD Kozlowski, T Kroupa, MA Kunselman, AR Lan, KA Laptev, V Lee, D Liu, F Manweiler, RW Marshall, R Mayes, BW Mischke, RE Nefkens, BMK Nickerson, LM Nord, PM Oothoudt, MA Otis, JN Phelps, R Piilonen, LE Pillai, C Pinsky, L Ritter, MW Smith, C Stanislaus, TDS Stantz, KM Szymanski, JJ Tang, L Tippens, WB Tribble, RE Tu, XL Van Ausdeln, LA von Witch, WH Whitehouse, D Wilkinson, C Wright, B Wright, SC Zhang, Y Ziock, KOH AF Ahmed, M Amann, JF Barlow, D Black, K Bolton, RD Brooks, ML Carius, S Chen, YK Chernyshev, A Concannon, HM Cooper, MD Cooper, PS Crocker, J Dittmann, JR Dzemidzic, M Empl, A Fisk, RJ Fleet, E Foreman, W Gagliardi, CA Haim, D Hallin, A Hoffman, CM Hogan, GE Hughes, EB Hungerford, EV Jui, CCH Kim, GJ Knott, JE Koetke, DD Kozlowski, T Kroupa, MA Kunselman, AR Lan, KA Laptev, V Lee, D Liu, F Manweiler, RW Marshall, R Mayes, BW Mischke, RE Nefkens, BMK Nickerson, LM Nord, PM Oothoudt, MA Otis, JN Phelps, R Piilonen, LE Pillai, C Pinsky, L Ritter, MW Smith, C Stanislaus, TDS Stantz, KM Szymanski, JJ Tang, L Tippens, WB Tribble, RE Tu, XL Van Ausdeln, LA von Witch, WH Whitehouse, D Wilkinson, C Wright, B Wright, SC Zhang, Y Ziock, KOH CA MEGA Collaboration TI Search for the lepton-family-number nonconserving decay mu(+)-> e(+)gamma SO PHYSICAL REVIEW D LA English DT Article ID MUON DECAY; DETECTOR; CONSTRUCTION; PERFORMANCE; PHYSICS; FLAVOR AB The MEGA experiment, which searched for the muon- and electron-number violating decay mu(+)-->e(+)gamma, is described. The spectrometer system, the calibrations, the data taking procedures, the data analysis, and the sensitivity of the experiment are discussed. The most stringent upper limit on the branching ratio, B(mu(+)-->e(+)gamma)<1.2x10(-11) with 90% confidence, is derived from a likelihood analysis. C1 Univ Houston, Houston, TX 77204 USA. Univ Chicago, Chicago, IL 60637 USA. Fermilab Natl Accelerator Lab, Batavia, IL 60510 USA. Indiana Univ, Bloomington, IN 46383 USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Stanford Univ, Stanford, CA 94305 USA. Texas A&M Univ, College Stn, TX 77843 USA. Univ Calif Los Angeles, Los Angeles, CA 90095 USA. Valparaiso Univ, Valparaiso, IN 46383 USA. Univ Virginia, Charlottesville, VA 22901 USA. Virginia Polytech Inst & State Univ, Blacksburg, VA 24061 USA. Univ Wyoming, Laramie, WY 82071 USA. Duke Univ, Durham, NC 27708 USA. Washington State Univ, Pullman, WA 99164 USA. Goddard Space Flight Ctr, Greenbelt, MD 20740 USA. Uppsala Univ, S-75105 Uppsala, Sweden. Zhejiang Silk & Text Univ, Hangzhou 310012, Peoples R China. CALTECH, Pasadena, CA 91125 USA. Fermilab Natl Accelerator Lab, Batavia, IL 60510 USA. Indiana Univ, Sch Med, Indianapolis, IN 46202 USA. Univ Maryland, Baltimore, MD 21201 USA. InSyst Technol, Roanoke, VA 24010 USA. Queens Univ, Kingston, ON K7L 3N6, Canada. Univ Utah, Salt Lake City, UT 84112 USA. Monmouth Coll, Monmouth, IL 61462 USA. Vina Technol, Newark, CA 94560 USA. Illinois Math & Sci Acad, Aurora, IL 60506 USA. IBM Corp, Austin, TX 78758 USA. IBM Corp, Microelect Div, Essex Jct, VT 05452 USA. Johns Hopkins Univ, Baltimore, MD 21218 USA. Optoson Inc, Indianapolis, IN 46260 USA. Hampton Univ, Hampton, VA 23668 USA. US DOE, Germantown, MD 20874 USA. Cisco Syst Inc, Richardson, TX 75082 USA. Idaho Natl Lab, Idaho Falls, ID 83401 USA. Univ Bonn, D-5300 Bonn, Germany. Allied Grp, Glastonbury, CT 06033 USA. AT&T Labs Res, Middletown, NJ 07932 USA. RP Ahmed, M (reprint author), Univ Houston, Houston, TX 77204 USA. RI Crocker, John/D-4991-2012 OI Crocker, John/0000-0001-6239-6010 NR 28 TC 74 Z9 74 U1 1 U2 2 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1550-7998 J9 PHYS REV D JI Phys. Rev. D PD JUN 1 PY 2002 VL 65 IS 11 AR 112002 DI 10.1103/PhysRevD.65.112002 PG 31 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 572JN UT WOS:000176770900005 ER PT J AU Qu, D Rame, E Garoff, S AF Qu, D Rame, E Garoff, S TI Dip-coated films of volatile liquids (vol 14, pg 1154, 2002) SO PHYSICS OF FLUIDS LA English DT Correction C1 Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. Carnegie Mellon Univ, Ctr Complex Fluids Engn, Pittsburgh, PA 15213 USA. NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, Cleveland, OH 44135 USA. RP Qu, D (reprint author), Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. RI Garoff, Stephen/P-7629-2014 OI Garoff, Stephen/0000-0001-8148-8535 NR 1 TC 0 Z9 0 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD JUN PY 2002 VL 14 IS 6 BP 2026 EP 2026 DI 10.1063/1.1476916 PG 1 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 550KN UT WOS:000175502400028 ER PT J AU de Carvalho, CAA Nussenzveig, HM AF de Carvalho, CAA Nussenzveig, HM TI Time delay SO PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS LA English DT Review ID CLASSICALLY CHAOTIC REPELLOR; SEMICLASSICAL TRACE FORMULAS; NEAR-INTEGRABLE SYSTEMS; NUCLEAR CROSS SECTIONS; 2ND VIRIAL-COEFFICIENT; TRAVERSAL-TIME; S-MATRIX; QUANTUM SCATTERING; DIELECTRIC MICROSPHERES; IRREGULAR SCATTERING AB The concepts of time delay and dwell time in quantum mechanics, and their applications to regular and chaotic scattering, to statistical mechanics, and to the tunneling time problem, among others, are reviewed. The emphasis is on physical concepts and on a pedagogical presentation. (C) 2002 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Fed Rio de Janeiro, Inst Fis, BR-21945970 Rio De Janeiro, RJ, Brazil. RP NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. EM nussenzv@climate.gsfe.nasa.gov NR 204 TC 124 Z9 124 U1 0 U2 13 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0370-1573 EI 1873-6270 J9 PHYS REP JI Phys. Rep.-Rev. Sec. Phys. Lett. PD JUN PY 2002 VL 364 IS 2 BP 83 EP 174 AR PII S0370-1573(01)00092-8 DI 10.1016/S0370-1573(01)00092-8 PG 92 WC Physics, Multidisciplinary SC Physics GA 554YC UT WOS:000175763900001 ER PT J AU Raulin, F McKay, CP AF Raulin, F McKay, CP TI Special issue on Exobiology: the search for extraterrestrial life and prebiotic chemistry - Preface SO PLANETARY AND SPACE SCIENCE LA English DT Editorial Material C1 Univ Paris 12, CNRS, UMR 7583, LISA, F-94010 Creteil, France. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Raulin, F (reprint author), Univ Paris 12, CNRS, UMR 7583, LISA, 61 Ave Gen Gaulle, F-94010 Creteil, France. NR 0 TC 9 Z9 9 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD JUN-JUL PY 2002 VL 50 IS 7-8 BP 655 EP 655 AR PII S0032-0633(02)00109-5 DI 10.1016/S0032-0633(02)00109-5 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 608LC UT WOS:000178846900001 ER PT J AU Gowayed, Y Abel-Hady, F Flowers, GT Trudell, JJ AF Gowayed, Y Abel-Hady, F Flowers, GT Trudell, JJ TI Optimal design of multi-direction composite flywheel rotors SO POLYMER COMPOSITES LA English DT Article ID PLATES; OPTIMIZATION; STIFFNESS AB Design of composite flywheels made with reinforcement in the hoop and radial directions (Multiple Direction Composites MDC) involves a large multitude of parameters such as those related to the flywheel operation, flywheel geometry, material characteristics, material layup, and stress spatial distribution and values. The problem is further complicated because most design parameters are interactive and because one parameter cannot be optimized independent of the other parameters. Optimum structural design of MDC flywheels using nonlinear optimization via a sequential quadratic programming approach and parametric finite element analysis are used to address this problem. Numerical examples are solved to compare the efficacy of the two approaches. C1 Auburn Univ, Dept Text Engn, Auburn, AL 36849 USA. Auburn Univ, Dept Mech Engn, Auburn, AL 36849 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Gowayed, Y (reprint author), Auburn Univ, Dept Text Engn, Auburn, AL 36849 USA. NR 35 TC 12 Z9 14 U1 0 U2 3 PU SOC PLASTICS ENG INC PI BROOKFIELD PA 14 FAIRFIELD DR, BROOKFIELD, CT 06804-0403 USA SN 0272-8397 J9 POLYM COMPOSITE JI Polym. Compos. PD JUN PY 2002 VL 23 IS 3 BP 433 EP 441 DI 10.1002/pc.10445 PG 9 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA 568HH UT WOS:000176536000014 ER PT J AU Neudeck, PG Okojie, RS Chen, LY AF Neudeck, PG Okojie, RS Chen, LY TI High-temperature electronics - A role for wide bandgap semiconductors? SO PROCEEDINGS OF THE IEEE LA English DT Article DE contacts; electronics; high temperature; metal-oxide-semiconductorfield-effect transistor (MOSFET); packaging; power; semiconductors; sensors; SiC; silicon carbide; silicon-on-insulator (SOI); wide bandgap ID N-JUNCTION DIODES; SILICON-CARBIDE; PERFORMANCE; TECHNOLOGY; BREAKDOWN; DEVICES; DEFECTS; GAN; RELIABILITY; CAPACITORS AB It is increasingly recognized that semiconductor based electronics that can function at ambient temperatures higher than 150 degreesC without external cooling could greatly benefit a variety of important applications, especially in the automotive, aerospace, and energy production industries. The fact that wide bandgap semiconductors are capable of electronic functionality at much higher temperatures than silicon has partially fueled their development, particularly in the case of SiC. It appears unlikely that wide bandgap semiconductor devices will find much use in low-power transistor applications until the ambient temperature exceeds approximately 300 degreesC, as commercially available silicon and silicon-on-insulator technologies are already satisfying requirements for digital and analog very large scale integrated circuits in this temperature range. However practical operation of silicon power devices at ambient temperatures above 200 degreesC appears problematic, as self-heating at higher power levels results in high internal junction temperatures and leakages. Thus, most electronic subsystems that simultaneously require high-temperature and high-power operation will necessarily be realized using wide bandgap devices, once the technology for realizing these devices become sufficiently developed that they become widely available. Technological challenges impeding the realization of beneficial wide bandgap high ambient temperature electronics, including material growth, contacts, and packaging, are briefly discussed. C1 NASA, Ohio Aerosp Inst, Glenn Res Ctr, Cleveland, OH 44135 USA. RP NASA, Ohio Aerosp Inst, Glenn Res Ctr, Cleveland, OH 44135 USA. EM neudeck@grc.naga.gov; okojie@grc.nasa.gov; Liangyu.Chen@grc.nasa.gov NR 65 TC 301 Z9 307 U1 9 U2 67 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9219 EI 1558-2256 J9 P IEEE JI Proc. IEEE PD JUN PY 2002 VL 90 IS 6 BP 1065 EP 1076 AR PII S0018-9219(02)05578-0 DI 10.1109/JPROC.2002.1021571 PG 12 WC Engineering, Electrical & Electronic SC Engineering GA 581CF UT WOS:000177273000013 ER PT J AU Lien, MC Proctor, RW AF Lien, MC Proctor, RW TI Stimulus-response compatibility and psychological refractory period effects: Implications for response selection SO PSYCHONOMIC BULLETIN & REVIEW LA English DT Review ID DUAL-TASK INTERFERENCE; S-R COMPATIBILITY; CHOICE-REACTION TASKS; IRRELEVANT LOCATION INFORMATION; EXECUTIVE COGNITIVE-PROCESSES; DIVIDED ATTENTION; REACTION-TIME; IDEOMOTOR COMPATIBILITY; OVERLAPPING TASKS; STROOP-LIKE AB The purpose of this paper was to provide insight into the nature of response selection by reviewing the literature on stimulus-response compatibility (SRC) effects and the psychological refractory period (PRP) effect individually and jointly The empirical findings and theoretical explanations of SRC effects that have been studied within a single-task context suggest that there are two response-selection routes-automatic activation and intentional translation. In contrast, all major PRP models reviewed in this paper have treated response selection as a single processing stage. In particular, the response-selection bottleneck (RSB) model assumes that the processing of Task I and Task 2 comprises two separate streams and that the PRP effect is due to a bottleneck located at response selection. Yet, considerable evidence from studies of SRC in the PRP paradigm shows that the processing of the two tasks is more interactive than is suggested by the RSB model and by most other models of the PRP effect. The major implication drawn from the studies of SRC effects in the PRP context is that response activation is a distinct process from final response selection. Response activation is based on both long-term and short-term task-defined S-R associations and occurs automatically and in parallel for the two tasks. The final response selection is an intentional act required even for highly compatible and practiced tasks and is restricted to processing one task at a time. Investigations of SRC effects and response-selection variables in dual-task contexts should be conducted more systematically because they provide significant insight into the nature of response-selection mechanisms. C1 Purdue Univ, Dept Psychol Sci, W Lafayette, IN 47907 USA. RP Lien, MC (reprint author), NASA, Ames Res Ctr, Mail Stop 262-4, Moffett Field, CA 94035 USA. EM mclien@mail.arc.nasa.gov; proctor@psych.purdue.edu NR 126 TC 122 Z9 122 U1 5 U2 19 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 1069-9384 J9 PSYCHON B REV JI Psychon. Bull. Rev. PD JUN PY 2002 VL 9 IS 2 BP 212 EP 238 DI 10.3758/BF03196277 PG 27 WC Psychology, Mathematical; Psychology, Experimental SC Psychology GA 571NP UT WOS:000176723700002 PM 12120784 ER PT J AU Everett, ME Howell, SB van Belle, GT Ciardi, DR AF Everett, ME Howell, SB van Belle, GT Ciardi, DR TI Stellar variability in a survey of field stars SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID PHOTOMETRIC VARIABILITY; VARIABLE-STARS; SPACE MISSION; BINARY STARS; HR-DIAGRAM; CEPHEIDS; PROJECT; CATALOG; SEARCH; DETECT AB We present results from a 5 night wide-field time-series photometric survey that detects variable field stars. We find that the fraction of stars whose light curves show variations depends on color and magnitude, reaching 17% for the brightest stars in this survey (Vsimilar to14) for which the photometric precision is best. The fraction of stars found to be variable is relatively high at colors bluer than the Sun and relatively low at colors similar to the Sun and increases again for stars redder than the Sun. We present light curves for a sample of the pulsating and eclipsing variables. Most of the stars identified as pulsating variables have low amplitudes (DeltaV = 0.01-0.05), relatively blue colors, and multiple periods. There are 13 stars we identify as either SX Phoenicis or delta Scuti stars. These classes represent a significant contribution to the total number of blue variables found in this survey. Another 17 stars are identified as eclipsing variables, which have a wide range in color, magnitude, and amplitude. Two variable giants are observed, and both show night-to-night similar to1% variations. We present data for 222 variables in total, most of which are not classified. Implications of surveys for stellar variability and interferometry are briefly discussed. C1 Planetary Sci Inst, Astronphys Grp, Tucson, AZ 85705 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Florida, Dept Astron, Gainesville, FL 32611 USA. RP Everett, ME (reprint author), Planetary Sci Inst, Astronphys Grp, 620 N 6th Ave, Tucson, AZ 85705 USA. EM everett@psi.edu; howell@psi.edu; gerard@huey.jpl.nasa.gov; ciardi@astro.ufl.edu OI Ciardi, David/0000-0002-5741-3047 NR 39 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD JUN PY 2002 VL 114 IS 796 BP 656 EP 670 DI 10.1086/341682 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 551ZJ UT WOS:000175593600010 ER PT J AU Wan, ZM Zhang, YL Li, ZL Wang, RB Salomonson, VV Yves, A Bosseno, R Hanocq, JF AF Wan, ZM Zhang, YL Li, ZL Wang, RB Salomonson, VV Yves, A Bosseno, R Hanocq, JF TI Preliminary estimate of calibration of the moderate resolution imaging spectroradiometer thermal infrared data using Lake Titicaca SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID LAND-SURFACE TEMPERATURE; RADIATIVE-TRANSFER; WATER-VAPOR; SEA-SURFACE; MODIS; SATELLITE; ALGORITHM; CLOUD; MODEL; SPECTROMETER AB The absolute radiometric accuracy of Moderate Resolution Imaging Spectroradiometer (MODIS) thermal infrared (TIR) data was evaluated with in situ data collected in a vicarious calibration field campaign conducted in Lake Titicaca, Bolivia during May 26 and June 17, 2000. The comparison between MODIS TIR data produced by the version 2.5.4 Level-1B code and the band radiances calculated with atmospheric radiative transfer code MODTRAN4.0 based on fake surface kinetic temperatures measured by five IR radiometers deployed in the high-elevation Lake Titicaca and the atmospheric temperature and water vapor profiles measured by radiosondes launched on the lake shore on June, 15 2000, a calin clear-sky day, shows good agreements in bands 31 and 32 (within an accuracy of 0.4%) in the daytime overpass case. Sensitivity analysis indicates that the changes on the measured atmospheric temperature and water vapor profiles result in negligible or small effects on the calculated radiances in the atmospheric window bands (bands 20-23, 29, and 31-32). Therefore, comparisons for these bands were made for cases when lake surface temperature measurements were available but no radiosonde data were available and in subareas of 10 x 16 pixels where there was no in situ measurement but MODIS brightness temperatures in band 3 1 vary within +/- 0.15 K by using the validated band 31 to determine lake surface temperatures through the MODTRAN4.0 code. Comparisons and error analysis show that the specified absolute radiometric accuracies are reached or nearly reached in MODIS bands 21, 29, and 31-33 and that there is a calibration bias of 2-3% in bands 20, 22, and 23. The error analysis also shows that the radiosondes cannot provide accurate atmospheric temperature and water vapor profiles to estimate the calibration accuracies in the atmspheric sounding bands (bands 24-25, 27-28, and 34-36) at the specified 1% level and that the calibration accuracy in the ozone band 30 cannot be estimated without in situ measurements of ozone. (C) 2002 Elsevier Science Inc. All rights rescrved. C1 Univ Calif Santa Barbara, Inst Computat Earth Syst Sci, Santa Barbara, CA 93106 USA. Goddard Space Flight Ctr, Earth Sci Directorate, Greenbelt, MD 20771 USA. French Inst Res & Dev, La Paz, Bolivia. INRA, Avignon, France. RP Wan, ZM (reprint author), Univ Calif Santa Barbara, Inst Computat Earth Syst Sci, Santa Barbara, CA 93106 USA. NR 31 TC 27 Z9 34 U1 1 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD JUN PY 2002 VL 80 IS 3 BP 497 EP 515 AR PII S0034-4257(01)00327-3 DI 10.1016/S0034-4257(01)00327-3 PG 19 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 554VK UT WOS:000175757700012 ER PT J AU Desch, SJ Borucki, WJ Russell, CT Bar-Nun, A AF Desch, SJ Borucki, WJ Russell, CT Bar-Nun, A TI Progress in planetary lightning SO REPORTS ON PROGRESS IN PHYSICS LA English DT Review ID ICE CRYSTAL INTERACTIONS; MARTIAN DUST STORMS; TITANS ATMOSPHERE; LOWER IONOSPHERE; MOIST CONVECTION; CHARGE-TRANSFER; ELECTROSTATIC DISCHARGES; JUPITERS ATMOSPHERE; JOVIAN THUNDERCLOUD; ORGANIC-MOLECULES AB We review the progress in the last decade in the field of planetary lightning. We provide background covering terrestrial lightning and newly discovered associated phenomena such as sprites. We concentrate on the theory and observations regarding lightning at Jupiter, especially the discoveries made by the Galileo orbiter and entry probe. Recent observations of Titan's atmosphere and a theory of possible lightning at Titan are reviewed. We discuss the potential for lightning detection by the Huygens probe that will enter Titan's atmosphere in 2005. Directions for future progress in planetary lightning are outlined. C1 Carnegie Inst Sci, Dept Terr Magnetism, Washington, DC 20015 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. Tel Aviv Univ, Dept Geophys & Plantetary Sci, IL-69978 Tel Aviv, Israel. RP Carnegie Inst Sci, Dept Terr Magnetism, 5241 Broad Branch Rd NW, Washington, DC 20015 USA. EM desch@dtm.ciw.edu OI Russell, Christopher/0000-0003-1639-8298 NR 235 TC 48 Z9 49 U1 0 U2 9 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0034-4885 EI 1361-6633 J9 REP PROG PHYS JI Rep. Prog. Phys. PD JUN PY 2002 VL 65 IS 6 BP 955 EP 997 AR PII S0034-4885(02)69401-1 DI 10.1088/0034-4885/65/6/202 PG 43 WC Physics, Multidisciplinary SC Physics GA 570HK UT WOS:000176652700002 ER PT J AU Saylor, JR Jones, BK Bliven, LF AF Saylor, JR Jones, BK Bliven, LF TI A method for increasing depth of field during droplet imaging SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID FRAGMENT SIZE DISTRIBUTIONS; RAINDROP OSCILLATIONS; DEFORMED DROPLETS; LIGHT-SCATTERING; AXIS RATIOS; COALESCENCE; BREAKUP; INCLUSIONS; COLLISION AB The measurement of water drops using direct optical imaging involves a tradeoff between the camera depth of field and the accuracy of the measured droplet size. A large depth of field increases the length of that portion of the optical axis that is in focus. However, since drops closer to the camera appear larger than those farther away, increasing the depth of field also increases errors in the measured drop size unless a priori knowledge exists concerning the location of the drop along the optical axis. Herein a method is presented for ascertaining drop location using a single camera. The method uses a characteristic of the droplet image which is observed when droplets are illuminated from behind. Once the location of the droplet is obtained, the appropriate magnification ratio is applied, permitting an accurate droplet size measurement. This method has been tested on glass spheres of various size. The relevance of this work to precipitation science is discussed. (C) 2002 American Institute of Physics. C1 Clemson Univ, Clemson, SC 29634 USA. NASA, Goddard Space Flight Ctr, Wallops Isl, VA 23337 USA. RP Saylor, JR (reprint author), Clemson Univ, Clemson, SC 29634 USA. RI bliven, francis/E-1450-2012 NR 25 TC 13 Z9 14 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD JUN PY 2002 VL 73 IS 6 BP 2422 EP 2427 DI 10.1063/1.1475353 PG 6 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 554PP UT WOS:000175744900031 ER PT J AU Luke, DR Burke, JV Lyon, RG AF Luke, DR Burke, JV Lyon, RG TI Optical wavefront reconstruction: Theory and numerical methods SO SIAM REVIEW LA English DT Review DE geometric optics; phase retrieval; nonconvex programming; least squares ID HUBBLE-SPACE-TELESCOPE; SIGNAL FEASIBILITY PROBLEMS; PHASE-RETRIEVAL ALGORITHMS; FOURIER-TRANSFORM PAIRS; IMAGE-RECONSTRUCTION; LEAST-SQUARES; APPROXIMATE SUBDIFFERENTIALS; DIVERSITY TECHNIQUE; ITERATIVE METHOD; NOISY DATA AB Optical wavefront reconstruction algorithms played a central role in the effort to identify gross manufacturing errors in NASA's Hubble Space Telescope (HST). NASA's success with reconstruction algorithms on the HST has led to an effort to develop software that can aid and in some cases replace complicated, expensive, and error-prone hardware. Among the many applications is HST's replacement, the Next Generation Space Telescope (NGST). This work details the theory of optical wavefront reconstruction, reviews some numerical methods for this problem, and presents a novel numerical technique that we call extended least squares. We compare the performance of these numerical methods for potential inclusion in prototype NGST optical wavefront reconstruction software. We begin with a tutorial on Rayleigh-Sommerfeld diffraction theory. C1 Univ Gottingen, Inst Numer & Appl Math, D-37083 Gottingen, Germany. Univ Washington, Dept Math, Seattle, WA 98195 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Luke, DR (reprint author), Univ Gottingen, Inst Numer & Appl Math, Lotzestr 16-18, D-37083 Gottingen, Germany. NR 133 TC 72 Z9 74 U1 2 U2 6 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 0036-1445 J9 SIAM REV JI SIAM Rev. PD JUN PY 2002 VL 44 IS 2 BP 169 EP 224 AR PII S0036144501390754 DI 10.1137/S003614450139075 PG 56 WC Mathematics, Applied SC Mathematics GA 557NF UT WOS:000175914100002 ER PT J AU Scharton, TD AF Scharton, TD TI Vibration and acoustic testing of spacecraft SO SOUND AND VIBRATION LA English DT Article AB Spacecraft are subjected to a variety of dynamics environments, which may include: quasi-static, vibration and acoustic loads at launch; pyrotechnic shocks generated by separation mechanisms; on-orbit jitter; and sometimes, planetary landing loads. There is a trend in the aerospace industry to rely more on structural analyses and less on testing to simulate these environments, because dynamics testing of spacecraft is time consuming, risky and expensive. However, as Dr. Edward Stone, the previous director of the Jet Propulsion Laboratory (JPL) told some students in the wake of the failures of two Mars spacecraft in 1999, "The key thing is to test. Build it, test it and test it some more. Because once it's gone, it's too late." Recognizing the essential role of testing, NASA is devoting considerable resources to the development of innovative and more efficient approaches to dynamics testing. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Scharton, TD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 1 Z9 3 U1 0 U2 2 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 JUN PY 2002 VL 36 IS 6 BP 14 EP 18 PG 5 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 566PC UT WOS:000176436500003 ER PT J AU Hughes, WO McNelis, ME AF Hughes, WO McNelis, ME TI Recent advances in vibroacoustics SO SOUND AND VIBRATION LA English DT Article AB Numerous vibroacoustics advances and problems in the aerospace industry have occurred over the last 15 years. This article addresses some of these that developed from engineering programmatic task-work at the NASA Glenn Research Center at Lewis Field. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Hughes, WO (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NR 15 TC 0 Z9 1 U1 2 U2 2 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 JUN PY 2002 VL 36 IS 6 BP 20 EP 27 PG 8 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 566PC UT WOS:000176436500004 ER PT J AU Bozzolo, G Garces, JE Abel, P AF Bozzolo, G Garces, JE Abel, P TI Modeling of 3C-SiC(100) using the BFS method for alloys SO SURFACE SCIENCE LA English DT Article; Proceedings Paper CT 20th European Conference on Surface Science CY SEP 04-07, 2001 CL KRAKOW, POLAND SP Jagiellonian Univ, Fulbright Int Ctr Cent & Eastern Europe, Elsevier Sci, AVC Sp DE semiconducting surfaces; semi-empirical models and model calculations; computer simulations; surface defects; alloys ID DIMER RECONSTRUCTION; SURFACE; LEED; SYSTEMS; SI(001); SI(100); C2H4 AB The Bozzolo-Ferrante-Smith (BFS) method for alloys is extended to elemental semiconductors. and in this introductory work, to 3C-SiC(1 0 0) surfaces. In spite of the differences between metallic systems and semiconductors, the formulation of the BFS method for metallic alloys remains unaltered, thus providing a computationally simple and physically sound tool to deal with semiconductors. First-principles methods are used for the determination of the parameters of Si, C and SiC. These are fully transferable and applicable to any surface problem dealing with the 3C-SiC structure. Basic features regarding the surface energy and structure of Si, C and 3C-SiC are determined and compared to experiment. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Ohio Aerosp Inst, Cleveland, OH 44142 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Ctr Atom Bariloche, RA-8400 San Carlos De Bariloche, Rio Negro, Argentina. RP Bozzolo, G (reprint author), Ohio Aerosp Inst, 22800 Cedar Point Rd, Cleveland, OH 44142 USA. NR 32 TC 4 Z9 4 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 JUN 1 PY 2002 VL 507 BP 394 EP 400 AR PII S0039-6028(02)01276-1 DI 10.1016/S0039-6028(02)01276-1 PG 7 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA 569CV UT WOS:000176583700071 ER PT J AU Lin, PH Chou, MD Ji, Q Tsay, SC AF Lin, PH Chou, MD Ji, Q Tsay, SC TI Clear-sky surface solar radiation during the South China Sea Monsoon Experiment SO TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES LA English DT Article DE SCSMEX; surface solar radiation ID WATER-VAPOR; ATMOSPHERIC ABSORPTION; CLOUDS; DISCREPANCY; IRRADIANCE; MODELS AB Downward total solar fluxes measured at Dungsha coral island (20degrees42'N, 116degrees43'E) during the South China Sea Monsoon Experiment (May-June 1998) have been calibrated and compared with radiative transfer calculations for three clear-sky days. Model calculations use water vapor and temperature profiles from radiosonde measurements, and the aerosol optical thickness is derived from sunphotometric radiance measurements. Results show that the difference between observed and model-calculated downward surface fluxes is <3% of the daily mean. Averaged over the three clear days, the difference reduces to 1%. The averaged downward surface fluxes from observations and calculations for the three selected dates are 314 and 317 W/m(2), respectively. This result is consistent with a previous study using TOGA COARE measurements, which found good agreement between observations and model calculations. This study provides an extra piece of useful information for the modeling of radiative transfer, which helps to fill in the puzzle of the absorption of solar radiation in the atmosphere. C1 Natl Taiwan Univ, Dept Atmospher Sci, Taipei 106, Taiwan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. RP Lin, PH (reprint author), Natl Taiwan Univ, Dept Atmospher Sci, 1 Sect,4 Roosevelt Rd, Taipei 106, Taiwan. RI Tsay, Si-Chee/J-1147-2014; OI LIN, PO-HSIUNG/0000-0002-6410-6221 NR 19 TC 3 Z9 4 U1 0 U2 1 PU CHINESE GEOSCIENCE UNION PI TAIPEI PA PO BOX 23-59, TAIPEI 10764, TAIWAN SN 1017-0839 J9 TERR ATMOS OCEAN SCI JI Terr. Atmos. Ocean. Sci. PD JUN PY 2002 VL 13 IS 2 BP 185 EP 195 PG 11 WC Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences; Oceanography SC Geology; Meteorology & Atmospheric Sciences; Oceanography GA 572UU UT WOS:000176794000006 ER PT J AU Karlin, S Brocchieri, L Trent, J Blaisdell, BE Mrazek, J AF Karlin, S Brocchieri, L Trent, J Blaisdell, BE Mrazek, J TI Heterogeneity of genome and proteome content in bacteria, archaea, and eukaryotes SO THEORETICAL POPULATION BIOLOGY LA English DT Article ID ASYMMETRIC SUBSTITUTION PATTERNS; HIGHLY EXPRESSED GENES; EVOLUTIONARY RELATIONSHIPS; DNA-REPLICATION; TRIGGER FACTOR; PROTEINS; SEQUENCES; PROKARYOTES; MECHANISMS; ORIGIN AB Our analysis compares bacteria, archaea, and eukaryota with respect to a wide assortment of genome and proteome properties. These properties include ribosomal protein gene distributions, chaperone protein contrasts, major variation of transcription/translation factors, gene encoding pathways of energy metabolism, and predicted protein expression levels. Significant differences within and between the three domains of life include protein lengths, information processing procedures, many metabolic and lipid biosynthesis pathways, cellular controls, and regulatory proteins. Differences among genomes are influenced by lifestyle, habitat, physiology, energy sources, and other factors. (C) 2002 Elsevier Science (USA). C1 Stanford Univ, Dept Math, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Karlin, S (reprint author), Stanford Univ, Dept Math, Stanford, CA 94305 USA. FU NHGRI NIH HHS [5R01HG00335-15]; NIGMS NIH HHS [5R01GM10452-40] NR 82 TC 28 Z9 29 U1 0 U2 1 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0040-5809 J9 THEOR POPUL BIOL JI Theor. Popul. Biol. PD JUN PY 2002 VL 61 IS 4 BP 367 EP 390 DI 10.1006/tpbi.2002.1606 PG 24 WC Ecology; Evolutionary Biology; Genetics & Heredity SC Environmental Sciences & Ecology; Evolutionary Biology; Genetics & Heredity GA 589CB UT WOS:000177739500002 PM 12167359 ER PT J AU Gaucher, EA Gu, X Miyamoto, MM Benner, SA AF Gaucher, EA Gu, X Miyamoto, MM Benner, SA TI Predicting functional divergence in protein evolution by site-specific rate shifts SO TRENDS IN BIOCHEMICAL SCIENCES LA English DT Review ID MOLECULAR EVOLUTION; COVARION HYPOTHESIS; STATISTICAL-METHODS; ELONGATION-FACTORS; CRYSTAL-STRUCTURE; STRUCTURAL BASIS; GENE FAMILY; SEQUENCES; MODEL; SUBSTITUTION AB Most modern tools that analyze protein evolution allow individual sites to mutate at constant rates over the history of the protein family. However, Walter Fitch observed in the 1970s that, if a protein changes its function, the mutability of individual sites might also change. This observation is captured in the 'non-homogeneous gamma model', which extracts functional information from gene families by examining the different rates at which individual sites evolve. This model has recently been coupled with structural and molecular biology to identify sites that are likely to be involved in changing function within the gene family. Applying this to multiple gene families highlights the widespread divergence of functional behavior among proteins to generate paralogs and orthologs. C1 Univ Florida, NASA, Astrobiol Inst, Gainesville, FL 32611 USA. Univ Florida, Dept Chem, Gainesville, FL 32611 USA. Iowa State Univ, Dept Zool & Genet, Ctr Bioinformat & Biol Stat, Ames, IA 50011 USA. Univ Florida, Dept Zool, Gainesville, FL 32611 USA. RP Benner, SA (reprint author), Univ Florida, NASA, Astrobiol Inst, Gainesville, FL 32611 USA. EM benner@chem.ufl.edu RI Gaucher, Eric/I-7313-2013 FU NIGMS NIH HHS [R01 GM 62118] NR 61 TC 97 Z9 99 U1 0 U2 9 PU ELSEVIER SCIENCE LONDON PI LONDON PA 84 THEOBALDS RD, LONDON WC1X 8RR, ENGLAND SN 0968-0004 J9 TRENDS BIOCHEM SCI JI Trends Biochem.Sci. PD JUN PY 2002 VL 27 IS 6 BP 315 EP 321 AR PII S0968-0004(02)02094-7 DI 10.1016/S0968-0004(02)02094-7 PG 7 WC Biochemistry & Molecular Biology SC Biochemistry & Molecular Biology GA 562XR UT WOS:000176224700011 PM 12069792 ER PT J AU Harm, DL Schlegel, TT AF Harm, DL Schlegel, TT TI Predicting motion sickness during parabolic flight SO AUTONOMIC NEUROSCIENCE-BASIC & CLINICAL LA English DT Article DE parabolic flight; amylase; R-R intervals; sympathovagal index; gender ID HEART-RATE; SEASICKNESS SUSCEPTIBILITY; TONE AB Background: There are large individual differences in susceptibility to motion sickness. Attempts to predict who will become motion sick have had limited success. In the present study, we examined gender differences in resting levels of salivary amylase and total protein, cardiac interbeat intervals (R-R intervals), and a sympathovagal index and evaluated their potential to correctly classify individuals into two motion sickness severity groups. Methods: Sixteen subjects (10 men and 6 women) flew four sets of 10 parabolas aboard NASA's KC-135 aircraft. Saliva samples for amylase and total protein were collected preflight on the day of the flight and motion sickness symptoms were recorded during each parabola. Cardiovascular parameters were collected in the supine position 1-5 days before the flight. Results: There were no significant gender differences in sickness severity or any of the other variables mentioned above. Discriminant analysis using salivary amylase, R-R intervals and the sympathovagal index produced a significant Wilks' lambda coefficient of 0.36, p=0.006. The analysis correctly classified 87% of the subjects into the none-mild sickness or the moderate-severe sickness group. Conclusions: The linear combination of resting levels of salivary amylase, high-frequency R-R interval levels, and a sympathovagal index may be useful in predicting motion sickness severity. Published by Elsevier Science B.V. C1 NASA, Johnson Space Ctr, Neurosci Lab, Houston, TX 77058 USA. RP Harm, DL (reprint author), SK3 Human Adaptat & Countermeasures Off, 2101 Nasa Rd 1, Houston, TX 77058 USA. EM dharm@ems.jsc.nasa.gov NR 30 TC 10 Z9 11 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 1566-0702 J9 AUTON NEUROSCI-BASIC JI Auton. Neurosci-Basic Clin. PD MAY 31 PY 2002 VL 97 IS 2 BP 116 EP 121 AR PII S1566-0702(02)00043-7 DI 10.1016/S1566-0702(02)00043-7 PG 6 WC Neurosciences SC Neurosciences & Neurology GA 576KG UT WOS:000177002900007 PM 12132644 ER PT J AU Huo, WM Tarnovsky, V Becker, KH AF Huo, WM Tarnovsky, V Becker, KH TI Total electron-impact ionization cross-sections of CFx and NFx (x=1-3) SO CHEMICAL PHYSICS LETTERS LA English DT Article ID ENCOUNTER-DIPOLE MODEL; FREE-RADICALS; WAVE-FUNCTIONS; BASIS-SETS; MOLECULES; THRESHOLD AB The discrepancy between experimental and theoretical total electron-impact ionization cross-sections of the fluorides CFx and NFx (x = 1-3) is attributed to inadequacies in previous theoretical models. Cross-sections calculated using a recently developed siBED model that takes into account the shielding of the long-range dipole potential in the collision are in agreement with experiment. The present study also re-analyzed the previously reported experimental data to account for incomplete collection of fragment ions and the presence of ion-pair formation channels. For NF3, Our experimental and theoretical cross-sections compare well with the recent data of Haaland et al. in the region below dication formation. (C) 2002 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Stevens Inst Technol, Dept Phys, Hoboken, NJ 07030 USA. RP Huo, WM (reprint author), NASA, Ames Res Ctr, Mail Stop T27 B-1, Moffett Field, CA 94035 USA. NR 31 TC 25 Z9 25 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD MAY 31 PY 2002 VL 358 IS 3-4 BP 328 EP 336 AR PII S0009-2614(02)00633-4 DI 10.1016/S0009-2614(02)00633-4 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 566GA UT WOS:000176417500023 ER PT J AU Chou, MD Lindzen, RS Hou, AY AF Chou, MD Lindzen, RS Hou, AY TI Reply to: "Tropical cirrus and water vapor: an effective Earth infrared iris feedback?" SO ATMOSPHERIC CHEMISTRY AND PHYSICS LA English DT Article ID VARIABILITY; CLOUDS AB In assessing the iris effect suggested by Lindzen et al. (2001), Fu et al. (2002) found that the response of high-level clouds to the sea surface temperature had an effect of reducing the climate sensitivity to external radiative forcing, but the effect was not as strong as LCH found. The approach of FBH to specifying longwave emission and cloud albedos appears to be inappropriate, and the derived cloud optical properties may not have real physical meaning. The cloud albedo calculated by FBH is too large for cirrus clouds and too small for boundary layer clouds, which underestimates the iris effect. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. RP Chou, MD (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RI Hou, Arthur/D-8578-2012 NR 9 TC 8 Z9 8 U1 0 U2 2 PU EUROPEAN GEOPHYSICAL SOC PI KATLENBURG-LINDAU PA MAX-PLANCK-STR 13, 37191 KATLENBURG-LINDAU, GERMANY SN 1680-7324 J9 ATMOS CHEM PHYS JI Atmos. Chem. Phys. PD MAY 30 PY 2002 VL 2 BP 99 EP 101 PG 3 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 591KB UT WOS:000177877900001 ER PT J AU Peters, W Krol, M Dentener, F Thompson, AM Lelieveld, J AF Peters, W Krol, M Dentener, F Thompson, AM Lelieveld, J TI Chemistry-transport modeling of the satellite observed distribution of tropical tropospheric ozone SO ATMOSPHERIC CHEMISTRY AND PHYSICS LA English DT Article ID MODIFIED-RESIDUAL METHOD; METHANE PHOTOOXIDATION; MAPPING SPECTROMETER; SOUTH ATLANTIC; DRY DEPOSITION; COLUMN OZONE; NIMBUS 7; TOMS; PARAMETERIZATION; GOME AB We have compared the 14-year record of satellite derived tropical tropospheric ozone columns (TTOC) from the NIMBUS-7 Total Ozone Mapping Spectrometer (TOMS) to TTOC calculated by a chemistry-transport model (CTM). An objective measure of error, based on the zonal distribution of TTOC in the tropics, is applied to perform this comparison systematically. In addition, the sensitivity of the model to several key processes in the tropics is quantified to select directions for future improvements. The comparisons indicate a widespread, systematic (20%) discrepancy over the tropical Atlantic Ocean, which maximizes during austral Spring. Although independent evidence from ozonesondes shows that some of the disagreement is due to satellite overestimate of TTOC, the Atlantic mismatch is largely due to a misrepresentation of seasonally recurring processes in the model. Only minor differences between the model and observations over the Pacific occur, mostly due to interannual variability not captured by the model. Although chemical processes determine the TTOC extent, dynamical processes dominate the TTOC distribution, as the use of actual meteorology pertaining to the year of observations always leads to a better agreement with TTOC observations than using a random year or a climatology. The modeled TTOC is remarkably insensitive to many model parameters due to efficient feedbacks in the ozone budget. Nevertheless, the simulations would profit from an improved biomass burning calendar, as well as from an increase in NOx abundances in free tropospheric biomass burning plumes. The model showed the largest response to lightning NOx emissions, but systematic improvements could not be found. The use of multi-year satellite derived tropospheric data to systematically test and improve a CTM is a promising new addition to existing methods of model validation, and is a first step to integrating tropospheric satellite observations into global ozone modeling studies. Conversely, the CTM may suggest improvements to evolving satellite retrievals for tropospheric ozone. C1 Inst Marine & Atmospher Res Utrecht, Utrecht, Netherlands. Commiss European Communities, Joint Res Ctr, I-21020 Ispra, Italy. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Max Planck Inst Chem, D-55128 Mainz, Germany. RP Peters, W (reprint author), Inst Marine & Atmospher Res Utrecht, Utrecht, Netherlands. EM W.Peters@phys.uu.nl RI Peters, Wouter/B-8305-2008; Krol, Maarten/B-3597-2010; Krol, Maarten/E-3414-2013; Lelieveld, Johannes/A-1986-2013; Thompson, Anne /C-3649-2014 OI Peters, Wouter/0000-0001-8166-2070; Thompson, Anne /0000-0002-7829-0920 NR 64 TC 24 Z9 24 U1 0 U2 5 PU COPERNICUS GESELLSCHAFT MBH PI GOTTINGEN PA BAHNHOFSALLEE 1E, GOTTINGEN, 37081, GERMANY SN 1680-7316 J9 ATMOS CHEM PHYS JI Atmos. Chem. Phys. PD MAY 30 PY 2002 VL 2 BP 103 EP 120 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 591KB UT WOS:000177877900002 ER PT J AU Yamada, T AF Yamada, T TI Modeling of kink-shaped carbon-nanotube Schottky diode with gate bias modulation SO APPLIED PHYSICS LETTERS LA English DT Article ID FIELD-EFFECT TRANSISTORS; HETEROJUNCTIONS; TRANSPORT AB A model is proposed for the recent gate voltage V-G modulation experiment of a kink-shaped carbon nanotube (NT) Schottky diode [Z. Yao, H. Postma, L. Balents, and C. Dekker, Nature (London) 402, 273 (1999)]. Since larger V-G increases both the forward and the reverse turn-on voltages of the diode, we show that: (1) the rectification must occur at the kink where the metallic and the semiconducting NTs meet, and not at the electrode contact, and (2) the semiconducting NT must be n type. The turn-on voltages are derived analytically as a function of V-G considering the electrode contact contribution and a good agreement is obtained with the experimental data. (C) 2002 American Institute of Physics. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Yamada, T (reprint author), NASA, Ames Res Ctr, M-S 229-1, Moffett Field, CA 94035 USA. RI Yamada, Toshishige/E-7834-2012 OI Yamada, Toshishige/0000-0001-7145-9212 NR 14 TC 14 Z9 14 U1 2 U2 8 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD MAY 27 PY 2002 VL 80 IS 21 BP 4027 EP 4029 DI 10.1063/1.1481213 PG 3 WC Physics, Applied SC Physics GA 553ZV UT WOS:000175709000049 ER PT J AU Margot, JL Nolan, MC Benner, LAM Ostro, SJ Jurgens, RF Giorgini, JD Slade, MA Campbell, DB AF Margot, JL Nolan, MC Benner, LAM Ostro, SJ Jurgens, RF Giorgini, JD Slade, MA Campbell, DB TI Binary asteroids in the near-Earth object population SO SCIENCE LA English DT Article ID TIDAL DISRUPTION; DOUBLET CRATERS; SATELLITES; DISCOVERY; DENSITY AB Radar images of near-Earth asteroid 2000 DP107 show that it is composed of an similar to800-meter-diameter primary and an similar to300-meter-diameter secondary revolving around their common center of mass. The orbital period of 1.755 +/- 0.007 days and semimajor axis of 2620 160 meters constrain the total mass of the system to 4.6 +/- 0.5 x 10(11) kilograms and the bulk density of the primary to 1.7 +/- 1.1 grams per cubic centimeter. This system and other binary near-Earth asteroids have spheroidal primaries spinning near the breakup point for strengthless bodies, suggesting that the binaries formed by spin-up and fission, probably as a result of tidal disruption during close planetary encounters. About 16% of near-Earth asteroids larger than 200 meters in diameter may be binary systems. C1 CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Astron & Ionosphere Ctr, Arecibo, PR 00612 USA. Cornell Univ, Ithaca, NY 14853 USA. RP Margot, JL (reprint author), CALTECH, MC 150-21, Pasadena, CA 91125 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 35 TC 144 Z9 144 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 24 PY 2002 VL 296 IS 5572 BP 1445 EP 1448 DI 10.1126/science.1072094 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 557LP UT WOS:000175910300042 PM 11951001 ER PT J AU Elsayed, KA Chen, SS Petway, LB Meadows, BL Marsh, WD Edwards, WC Barnes, JC DeYoung, RJ AF Elsayed, KA Chen, SS Petway, LB Meadows, BL Marsh, WD Edwards, WC Barnes, JC DeYoung, RJ TI High-energy, efficient, 30-Hz ultraviolet laser sources for airborne ozone-lidar systems SO APPLIED OPTICS LA English DT Article ID WATER-VAPOR AB Two compact, high-pulse-energy, injection-seeded, 30-Hz frequency-doubled Nd:YAG-laser-pumped Ti: sapphire lasers were developed and operated at infrared wavelengths of 867 and 900 run. Beams with laser pulse energy >30 mJ at ultraviolet wavelengths of 289 and 300 nm were generated through a tripling of the frequencies of these Ti:sapphire lasers. This work is directed at the replacement of dye lasers for use in an airborne ozone differential absorption lidar system. The ultraviolet pulse energy at 289 and 300 nm had 27% and 31% absolute optical energy conversion efficiencies from input pulse energies at 867 and 900 nm, respectively. (C) 2002 Optical Society of America. C1 Old Dominion Univ, Dept Elect & Comp Engn, Norfolk, VA 23529 USA. Sci & Technol Corp, Hampton, VA 23666 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Old Dominion Univ, Dept Elect & Comp Engn, 231 Kaufman Hall, Norfolk, VA 23529 USA. EM k.a.elsayed@larc.nasa.gov RI Elsayed, Khaled/A-4373-2015 NR 13 TC 8 Z9 9 U1 0 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAY 20 PY 2002 VL 41 IS 15 BP 2734 EP 2739 DI 10.1364/AO.41.002734 PG 6 WC Optics SC Optics GA 553VR UT WOS:000175697300004 PM 12027160 ER PT J AU Yang, P Gao, BC Wiscombe, WJ Mishchenko, MI Platnick, SE Huang, HL Baum, BA Hu, YX Winker, DM Tsay, SC Park, SK AF Yang, P Gao, BC Wiscombe, WJ Mishchenko, MI Platnick, SE Huang, HL Baum, BA Hu, YX Winker, DM Tsay, SC Park, SK TI Inherent and apparent scattering properties of coated or uncoated spheres embedded in an absorbing host medium SO APPLIED OPTICS LA English DT Article ID LIGHT-SCATTERING; MIE SCATTERING; ALGORITHMS; PARTICLES; ICE AB The conventional Lorenz-Mie formalism is extended to the case for a coated sphere embedded in an absorbing medium. The apparent and inherent scattering cross sections of a particle, derived from the far field and near field, respectively, are different if the host medium is absorptive. The effect of absorption within the host medium on the phase-matrix elements associated with polarization depends on the dielectric properties of the scattering particle. For the specific cases of a soot particle coated with a water layer and an ice sphere containing an air bubble, the phase-matrix elements -P-12/P-11 and P-33/p(11) are unique if the shell is thin. The radiative transfer equation for a multidisperse particle system embedded within an absorbing medium is discussed. Conventional multiple-scattering computational algorithms can be applied if scaled apparent single-scattering properties are applied. (C) 2002 Optical Society of America. C1 Texas A&M Univ, Dept Atmospher Sci, College Stn, TX 77843 USA. USN, Res Lab, Remote Sensing Div, Washington, DC 20375 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Univ Wisconsin, Cooperat Inst Meteorol Satellite Studies, Madison, WI 53706 USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. Ewha Womans Univ, Dept Environm Sci & Engn, Seoul 120750, South Korea. RP Texas A&M Univ, Dept Atmospher Sci, 3150 TAMU, College Stn, TX 77843 USA. EM pyang@ariel.met.tamu.edu RI Yang, Ping/B-4590-2011; Baum, Bryan/B-7670-2011; Wiscombe, Warren/D-4665-2012; Tsay, Si-Chee/J-1147-2014; Platnick, Steven/J-9982-2014; Hu, Yongxiang/K-4426-2012; Mishchenko, Michael/D-4426-2012 OI Baum, Bryan/0000-0002-7193-2767; Wiscombe, Warren/0000-0001-6844-9849; Platnick, Steven/0000-0003-3964-3567; NR 23 TC 43 Z9 49 U1 1 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 MAY 20 PY 2002 VL 41 IS 15 BP 2740 EP 2759 DI 10.1364/AO.41.002740 PG 20 WC Optics SC Optics GA 553VR UT WOS:000175697300005 PM 12027161 ER PT J AU Kahn, BH Eldering, A Irion, FW Mills, FP Sen, B Gunson, MR AF Kahn, BH Eldering, A Irion, FW Mills, FP Sen, B Gunson, MR TI Cloud identification in Atmospheric Trace Molecule Spectroscopy infrared occultation measurements SO APPLIED OPTICS LA English DT Article ID GAS EXPERIMENT-II; HIGH-LEVEL CLOUDS; CIRRUS CLOUDS; SAGE-II; STRATOSPHERIC AEROSOL; EXTINCTION EFFICIENCY; RADIATIVE PROPERTIES; SHUTTLE MISSIONS; SATELLITE; SPECTRA AB High-resolution infrared nongas absorption spectra derived from the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment are analyzed for evidence of the presence of cirrus clouds. Several nonspherical ice extinction models based on realistic size distributions and crystal habits along with a stratospheric sulfate aerosol model are fit to the spectra, and comparisons are made with different model combinations. Nonspherical ice models often fit observed transmission spectra better than a spherical Mie ice model, and some discrimination among nonspherical models is noted. The ATMOS lines of sight for eight occultations are superimposed on coincident geostationary satellite infrared imagery, and brightness temperatures along the lines of sight are compared with retrieved vertical temperature profiles. With these comparisons, studies of two cases of clear sky, three cases of opaque cirrus, and three cases of patchy cirrus are discussed. (C) 2002 Optical Society of America. C1 Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. EM kahn@atmos.ucla.edu NR 34 TC 12 Z9 12 U1 1 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAY 20 PY 2002 VL 41 IS 15 BP 2768 EP 2780 DI 10.1364/AO.41.002768 PG 13 WC Optics SC Optics GA 553VR UT WOS:000175697300007 PM 12027163 ER PT J AU Redding, D Regehr, M Sievers, L AF Redding, D Regehr, M Sievers, L TI Dynamic models of Fabry-Perot interferometers SO APPLIED OPTICS LA English DT Article AB Long-baseline, high-finesse Fabry-Perot interferometers can be used to make distance measurements that are precise enough to detect gravity waves. This level of sensitivity is achieved in part when the interferometer mirrors are isolated dynamically, with pendulum mounts and high-bandwidth cavity length control servos to reduce the effects of seismic noise. We present dynamical models of the cavity fields and signals of Fabry-Perot interferometers for use in the design and evaluation of length control systems for gravity-wave detectors. Models are described and compared with experimental data. (C) 2002 Optical Society of America. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM dave@huey.jpl.nasa.gov NR 9 TC 5 Z9 5 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAY 20 PY 2002 VL 41 IS 15 BP 2894 EP 2906 DI 10.1364/AO.41.002894 PG 13 WC Optics SC Optics GA 553VR UT WOS:000175697300021 PM 12027177 ER PT J AU Bernstein, RA Freedman, WL Madore, BF AF Bernstein, RA Freedman, WL Madore, BF TI The first detections of the extragalactic background light at 3000, 5500, and 8000 angstrom. I. Results SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; diffuse radiation; dust, extinction; galaxies : photometry; interplanetary medium; techniques : photometric ID HUBBLE-DEEP-FIELD; HIGH GALACTIC LATITUDE; HIGH-REDSHIFT GALAXIES; STAR-FORMATION HISTORY; 100 MICRON CIRRUS; SPACE-TELESCOPE; ZODIACAL LIGHT; RADIATION-FIELD; NUMBER COUNTS; EMISSION-LINE AB We present the first detection of the mean flux of the optical extragalactic background light (EBL) at 3000, 5500, and 8000 Angstrom. Diffuse foreground flux at these wavelengths comes from terrestrial airglow, dust-scattered sunlight (zodiacal light), and dust-scattered Galactic starlight (diffuse Galactic light). We have avoided the brightest of these, terrestrial airglow, by measuring the absolute surface brightness of the night sky from above the Earth's atmosphere using the Wide Field Planetary Camera 2 (WFPC2) and Faint Object Spectrograph, both on board the Hubble Space Telescope (HST). On the ground we have used the du Pont 2.5 m Telescope at the Las Campanas Observatory (LCO) to obtain contemporaneous spectrophotometry of blank sky in the HST field of view to measure and then subtract foreground zodiacal light from the HST observations. We have minimized the diffuse Galactic light in advance by selecting the HST target field along a line of sight with low Galactic dust column density and then estimated the low-level Galactic foreground using a simple scattering model and the observed correlation between thermal, 100 l m emission, and optical scattered flux from the same dust. In this paper, we describe the coordinated LCO/HST program and the HST observations and data reduction and present the resulting measurements of the EBL. Galaxies brighter than V = 23 AB mag are not well sampled in an image the size of the WFPC2 field of view. We have therefore measured the EBL from unresolved and resolved galaxies fainter than V = 23 AB mag by masking out brighter galaxies. We write this as EBL23 to emphasize this bright magnitude cutoff. From absolute surface photometry using WFPC2 and ground-based spectroscopy, we find mean values for the EBL23 of 4.0 (+/-2.5), 2.7 (+/-1.4), and 2.2 (+/-1.0) in units of 10(-9) ergs s(-1) cm(-2) sr(-1) Angstrom(-1) in the F300W, F555W, and F814W band-passes, respectively. The errors quoted are 1 combined statistical and systematic uncertainties. The total flux measured in resolved galaxies with V > 23 AB mag by standard photometric methods is roughly 15% of the EBL23 flux in each band. We have also developed a new method of source photometry, uniquely suited to these data, with which we can measure the ensemble flux from detectable sources much more accurately than is possible with standard methods for faint galaxy photometry. Using this method, we have quantified systematic biases affecting standard galaxy photometry, which prevent light from being recovered in isophotes within a few percent of the sky level. These biases have a significant effect on faint galaxy counts. The flux from resolved sources as measured by our ensemble photometry method is 3.2 (+/-0.22), 0.89 (+/-0.01), and 0.76 (+/-0.01) in units of 10(-9) ergs s(-1) cm(-2) sr(-1) Angstrom(-1) in the F300W, F555W, and F814W bandpasses, respectively, with 1sigma combined errors. These values, the total flux from resolved sources, represent absolute minima for the EBL23 in each band and are roughly 30% of the mean flux we measure for the total EBL23. C1 CALTECH, Div Phys Math & Astron, Pasadena, CA 91125 USA. Carnegie Observ, Pasadena, CA 91101 USA. CALTECH, NASA, Infrared Proc & Anal Ctr Extragalact Database, Pasadena, CA 91125 USA. RP Bernstein, RA (reprint author), CALTECH, Div Phys Math & Astron, MS 103-33, Pasadena, CA 91125 USA. NR 79 TC 102 Z9 102 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2002 VL 571 IS 1 BP 56 EP 84 DI 10.1086/339422 PN 1 PG 29 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550TJ UT WOS:000175519000005 ER PT J AU Bernstein, RA Freedman, WL Madore, BF AF Bernstein, RA Freedman, WL Madore, BF TI The first detections of the extragalactic background light at 3000, 5500, and 8000 angstrom. II. Measurement of foreground zodiacal light SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; diffuse radiation; interplanetary medium; techniques : spectroscopic ID SOUTHERN SPECTROPHOTOMETRIC STANDARDS; INTERPLANETARY DUST; LARGE TELESCOPES; SPECTRUM; PARTICLES; EMISSION; SURFACE AB We present a measurement of the absolute surface brightness of the zodiacal light (3900 5100 Angstrom) toward a fixed extragalactic target at high ecliptic latitude based on moderate-resolution (similar to1.3 Angstrom pixel(-1)) spectrophotometry obtained with the du Pont 2.5 m Telescope at the Las Campanas Observatory in Chile. This measurement and contemporaneous Hubble Space Telescope data from the Wide Field Planetary Camera 2 and Faint Object Spectrograph comprise a coordinated program to measure the mean flux of the diffuse extragalactic background light (EBL). The zodiacal light at optical wavelengths results from scattering by interplanetary dust so that the zodiacal light flux toward any extragalactic target varies seasonally with the position of the Earth. This measurement of zodiacal light is therefore relevant to the specific observations ( date and target field) under discussion. To obtain this result, we have developed a technique that uses the strength of the zodiacal Fraunhofer lines to identify the absolute flux of the zodiacal light in the multiple-component night-sky spectrum. Statistical uncertainties in the result are 0.6% (1sigma). However, the dominant source of uncertainty is systematic errors, which we estimate to be 1.1% (1sigma). We discuss the contributions included in this estimate explicitly. The systematic errors in this result contribute 25% in quadrature to the final error in our coordinated EBL measurement, which is presented in the first paper of this series. C1 CALTECH, Div Phys Math & Astron, Pasadena, CA 91125 USA. Carnegie Observ, Pasadena, CA 91101 USA. CALTECH, NASA, Infrared Proc & Anal Ctr Extragalact Database, Pasadena, CA 91125 USA. RP Bernstein, RA (reprint author), CALTECH, Div Phys Math & Astron, MS 103-33, Pasadena, CA 91125 USA. NR 66 TC 30 Z9 31 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2002 VL 571 IS 1 BP 85 EP 106 DI 10.1086/339423 PN 1 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550TJ UT WOS:000175519000006 ER PT J AU Bernstein, RA Freedman, WL Madore, BF AF Bernstein, RA Freedman, WL Madore, BF TI The first detections of the extragalactic background light at 3000, 5500, and 8000 angstrom. III. Cosmological implications SO ASTROPHYSICAL JOURNAL LA English DT Review DE cosmology : observations; diffuse radiation; galaxies : evolution; galaxies : photometry ID SURFACE BRIGHTNESS GALAXIES; DAMPED LYMAN-ALPHA; HIGH-REDSHIFT GALAXIES; STAR-FORMATION HISTORY; HUBBLE-DEEP-FIELD; ULTRAVIOLET LUMINOSITY DENSITY; DWARF SEYFERT NUCLEI; MASSIVE BLACK-HOLES; MULTIPHASE HOT GAS; X-RAY EVIDENCE AB We have used the Hubble Space Telescope Wide Field and Planetary Camera 2 in combination with ground-based spectroscopy to measure the integrated flux of galaxies at optical wavelengths the extragalactic background light (EBL). We have also computed the integrated light from individual galaxy counts in the images used to measure the EBL and in the Hubble Deep Field. We find that flux in galaxies as measured by standard galaxy photometry methods has generally been underestimated by about 50%, resulting from missed flux in the outer, lower surface brightness parts of galaxies and from associated errors in the estimated sky level. Comparing the corrected, integrated flux from individual galaxies with our total EBL measurement, we find that there is yet further light that contributes to the background that is not represented by galaxy counts and that the total flux in individually detected sources is a factor of 2 3 less than the EBL from 8000 to 3000 A. We show that a significant fraction of the EBL may come from normal galaxies at z < 4, which are simply undetectable as a result of K-corrections and cosmological surface brightness dimming. This result is consistent with results from recent redshift surveys at z < 4. In the context of some simple models,mu we discuss the constraints placed by the EBL on evolution in the luminosity density at z > 1; while significant flux comes from galaxies beyond the current detection limits, this evolution cannot be tightly constrained by our data. Based on our measurements of the optical EBL, combined with previously published measurements of the UV and IR EBL, we estimate that the total EBL from 0.1 to 1000 m is 100 +/- 20 nW m(-2) sr(-1). If the total EBL were produced entirely by stellar nucleosynthesis, then we estimate that the total baryonic mass processed through stars is Omega(*) = 0.0062 (+/- 0.0022) h(-2) in units of the critical density. For currently favored values of the baryon density Omega(B) this corresponds to 0.33 +/- 0.12 Omega(B). This estimate is smaller by roughly 7% if we allow for a contribution of 7 h(0.7) nW m(-2) sr(-1) to the total EBL from accretion onto central black holes. This estimate of suggests that the universe has been enriched to a total metal mass of 0.21 (+/-0.13) Z(.) Omega(B), which is consistent with other observational estimates of the cumulative metal mass fraction of stars, stellar remnants, and the intracluster medium of galaxy clusters in the local universe. C1 CALTECH, Div Phys Math & Astron, Pasadena, CA 91125 USA. Carnegie Observ, Pasadena, CA 91101 USA. CALTECH, NASA, Infrared Proc & Anal Ctr Extragalact Database, Pasadena, CA 91125 USA. RP Bernstein, RA (reprint author), CALTECH, Div Phys Math & Astron, MS 103-33, Pasadena, CA 91125 USA. NR 110 TC 48 Z9 48 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2002 VL 571 IS 1 BP 107 EP 128 DI 10.1086/339424 PN 1 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550TJ UT WOS:000175519000007 ER PT J AU Netzer, H Chelouche, D George, IM Turner, TJ Crenshaw, DM Kraemer, SB Nandra, K AF Netzer, H Chelouche, D George, IM Turner, TJ Crenshaw, DM Kraemer, SB Nandra, K TI The density and location of the X-ray absorbing gas in NGC 3516 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (NGC 3516); galaxies : nuclei; galaxies : Seyfert; techniques : spectroscopic; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; SEYFERT-1 GALAXY NGC-3516; WARM ABSORBERS; SWAN SONG; NGC-4051; SPECTROSCOPY; VARIABILITY; ABSORPTION; EMISSION; LINES AB A new Chandra observation and archival observations by ASCA are used to investigate spectral variations in the Seyfert 1 galaxy NGC 3516 over a period of 7 yr. A large change in flux (factor of similar to50 at 1 keV) is observed between an ASCA observation in 1994 and the Chandra observation in 2000, with the source close to the all-time maximum and minimum X-ray flux states, respectively. We find the variations in the observed flux and spectra at these epochs to be consistent with a constant column density of line-of-sight material reacting to changes in the ionizing continuum. The data from the two epochs are consistent with a simple decrease (by a factor of 8-10) in the luminosity of a constant 0.5-50 keV slope source and a line-of-sight absorber with an equivalent hydrogen column density of 10(21.9) cm(-2). Intermediate luminosities, sampled during other ASCA observations, are all fitted by the same model with a very small change in spectral index (well below DeltaT = 0.2). In addition, analysis of the long (360 ks) ASCA observation in 1998 shows clear color variations that are entirely consistent with this model and are interpreted as due to changes in the opacity of the absorbing gas. The data allow us to put a conservative upper limit of 60 ks on the recombination time, which translates to a lower limit of about 2.4 x 10(6) cm(-3) on the density of the recombining gas and an upper limit of about 6 x 10(17) h(75)(-2) cm on its distance from the central source. These are the best limits obtained so far on the density and location of the X-ray absorbing gas in a type 1 active galactic nucleus (AGN). They indicate that the absorbing gas is different in terms of its density and location from the ionized gas commonly observed in type II AGNs. The Chandra ACIS/LETGS data also reveals a strong (EW = 290 eV), unresolved 6.4 keV iron line, a strong O VII 0.561 keV line, and a marginally detected N VI 0.419 keV line. The former is interpreted as originating in a large column of gas of a lower state of ionization seen in reflection and is consistent with the spectrum at high energies at all epochs. The two other emission lines are probably emitted by the gas also responsible for the line-of-sight absorption. C1 Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA. Georgia State Univ, Dept Phys & Astron, Atlanta, GA 30303 USA. Catholic Univ Amer, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Netzer, H (reprint author), Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. NR 42 TC 53 Z9 53 U1 1 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2002 VL 571 IS 1 BP 256 EP 264 DI 10.1086/338967 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550TJ UT WOS:000175519000017 ER PT J AU George, IM Turner, TJ Netzer, H Kraemer, SB Ruiz, J Chelouche, D Crenshaw, DM Yaqoob, T Nandra, K Mushotzky, RF AF George, IM Turner, TJ Netzer, H Kraemer, SB Ruiz, J Chelouche, D Crenshaw, DM Yaqoob, T Nandra, K Mushotzky, RF TI The detection of circumnuclear X-ray emission from the Seyfert galaxy NGC 3516 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (NGC 3516); galaxies : nuclei; galaxies : Seyfert; X-rays : galaxies ID TRANSMISSION GRATING SPECTROMETER; LINE REGION; EXTENDED EMISSION; IONIZED-GAS; NGC-3516; AXAF; RESOLUTION; NEBULOSITY; OUTFLOWS; SAMPLE AB We present the first high-resolution, X-ray image of the circumnuclear regions of the Seyfert 1 galaxy NGC 3516, using the Chandra X-ray Observatory (CXO). All three of the CXO observations reported were performed with one of the two grating assemblies in place, and here we restrict our analysis to undispersed photons (i.e., those detected in the zeroth-order). A previously unknown X-ray source is detected similar to6" (1.1 h(75)(-1) kpc) NNE of the nucleus (position angle similar to29degrees) which we designate CXOU 110648.1+ 723412. Its spectrum can be characterized as a power law with a photon index Gamma similar to 1.8-2.6, or as thermal emission with a temperature kT similar to0.7-3 keV. Assuming a location within NGC 3516, isotropic emission implies a luminosity L similar to 2-8 x 10(39) h(75)(-2) ergs s(-1) in the 0.4-2 keV band. If due to a single point source, the object is super-Eddington for a 1.4 M-. neutron star. However, multiple sources or a small, extended source cannot be excluded using the current data. Large-scale extended X-ray emission is also detected out to similar to10" (similar to1.7 h(75)(-1) kpc) from the nucleus to the NE and SW and is approximately aligned with the morphologies of the radio emission and extended narrow emission line region (ENLR). The mean luminosity of this emission is 1-5 x 10(37) h(75)(-2) erg s(-1) arcsec(-2), in the 0.4-2 keV band. Unfortunately, the current data cannot usefully constrain its spectrum. These results are consistent with earlier suggestions of circumnuclear X-ray emission in NGC 3516. If the extended emission is due to scattering of the nuclear X-ray continuum, then the pressure in the X-ray-emitting gas is at least 2 orders of magnitude too small to provide the con ning medium for the ENLR clouds. C1 Univ Maryland Baltimore Cty, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Wise Observ, IL-69978 Tel Aviv, Israel. Tel Aviv Univ, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Catholic Univ Amer, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. Georgia State Univ, Dept Phys & Astron, Atlanta, GA 30303 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. RP George, IM (reprint author), Univ Maryland Baltimore Cty, Dept Phys, Joint Ctr Astrophys, 1000 Hilltop Circle, Baltimore, MD 21250 USA. NR 41 TC 8 Z9 8 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2002 VL 571 IS 1 BP 265 EP 271 DI 10.1086/338971 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550TJ UT WOS:000175519000018 ER PT J AU Athey, A Bregman, J Bregman, J Temi, P Sauvage, M AF Athey, A Bregman, J Bregman, J Temi, P Sauvage, M TI Mid-infrared observation of mass loss in elliptical galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : elliptical and lenticular, cD; infrared : stars; stars : AGB and post-AGB; stars : mass loss ID GIANT BRANCH STARS; INTERSTELLAR SILICATE MINERALOGY; LOSS RATES; CIRCUMSTELLAR ENVELOPES; INFRARED-EMISSION; EVOLVED STARS; SPECTRAL TYPE; AGB STARS; EVOLUTION; WINDS AB Early-type galaxies exhibit thermal and molecular resonance emission from dust that is shed and heated through stellar mass loss as a subset of the population moves through the asymptotic giant branch (AGB) phase of evolution. Because this emission can give direct insight into stellar evolution in addition to galactic stellar mass loss and interstellar medium injection rates, we conducted a program to search for this signature emission with CAM on the Infrared Space Observatory. We obtained 6-15 mum imaging observations in six narrow bands for nine elliptical galaxies; every galaxy is detected in every band. For wavelengths shorter than 9 mum, the spectra are well matched by a blackbody originating from the K and M stars that dominate the integrated light of elliptical galaxies. At wavelengths between 9 and 15 mum, however, the galaxies display excess emission relative to the stellar photospheric radiation. Additional data taken with the fine-resolution circular variable filter on one source clearly shows broad emission from 9 to 15 mum, peaking around 10 mum. This result is consistent with the known broad silicate feature at 9.7 mum originating in the circumstellar envelopes of AGB stars. This emission is compared with studies of Galactic and Large Magellanic Cloud AGB stars to derive cumulative mass-loss rates. In general, these mass-loss rates agree with the expected similar to0.8 M-. yr(-1) value predicted by stellar evolutionary models. Both the photospheric and circumstellar envelope emission follow a de Vaucouleurs R-1/4 law, supporting the conclusion that the mid-infrared excess emission originates in the stellar component of the galaxies and acts as a tracer of AGB mass loss and mass injection into the interstellar medium. C1 Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA. NASA, Ames Res Ctr, Astrophys Branch, Moffett Field, CA 94035 USA. Ctr Etud Saclay, Serv Astrophys, DAPNIA, DSM,CEA, F-91191 Gif Sur Yvette, France. RP Univ Michigan, Dept Astron, 500 Church St, Ann Arbor, MI 48109 USA. EM alex@astro.lsa.umich.edu; jbregman@astro.lsa.umich.edu NR 43 TC 83 Z9 83 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2002 VL 571 IS 1 BP 272 EP 281 DI 10.1086/339844 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550TJ UT WOS:000175519000019 ER PT J AU Mucke, A Koribalski, BS Moffat, AFJ Corcoran, MF Stevens, IR AF Mucke, A Koribalski, BS Moffat, AFJ Corcoran, MF Stevens, IR TI Australia telescope compact array radio imaging of the proplyd-like objects in the giant H II region NGC 3603 SO ASTROPHYSICAL JOURNAL LA English DT Article DE HII regions; ISM : individual (NGC 3603); radio continuum : ISM; stars : early-type; stars : formation; stars : pre-main-sequence ID WOLF-RAYET STARS; ORION-NEBULA; HIGH-RESOLUTION; HII-REGIONS; NGC-3603; SPECTROSCOPY; EMISSION; DISKS AB Three cometary-shaped objects in the giant H II region NGC 3603, originally found and identified as proto planetary disks (proplyds) by Brandner and coworkers using the Hubble Space Telescope and the Very Large Telescope in the optical and near-infrared, have been detected with the Australia Telescope Compact Array(5) in the radio continuum at 3 and 6 cm. All three proplyd-like objects are clearly resolved with an extent of a few arcseconds. The integrated 6 cm fluxes are up to 1.3 times higher than the 3 cm fluxes with spectral indices averaged over the whole clump between alpha = 0.1 and 0.5 (Sv proportional to nu(alpha)), indicating the likely presence of nonthermal emission in at least some of the sources. We present spectral-index maps and show that the sites of negative radio spectral indices are predominantly concentrated in the direction of the tails in at least two of the three proplyd-like nebulae, while positive spectral indices are found in the region facing the ionizing star cluster. We propose that thermal bremsstrahlung and nonthermal synchrotron radiation are at work in all three proplyd-like sources. In at least one of the three objects, optically thin nonthermal synchrotron emission appears to dominate when averaged over its whole spatial extent, while the spectrum of a second source shows a marginal indication of a nonthermal spectrum. The average spectrum of the third source is in agreement with thermal bremsstrahlung. All measured fluxes are at least one order of magnitude higher than those predicted by Brandner and coworkers. Upper limits for mass-loss rates due to photoevaporation are calculated to be similar to10(-5) M. yr(-1) and for electron densities to be similar to10(4) cm(-3). Due to the unexpectedly large radio luminosities of the proplyd-like features and because the radio emission is extended, a (proto-) stellar origin of the nonthermal emission from a dust enshrouded star appears unlikely. Instead, we propose that magnetized regions within the envelope of the proplyd-like nebulae exist. C1 Univ Montreal, Dept Phys, Montreal, PQ H3C 3J7, Canada. Observ Mont Megant, Montreal, PQ, Canada. CSIRO, Australia Telescope Natl Facil, Epping, NSW 1710, Australia. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. RP Mucke, A (reprint author), Ruhr Univ Bochum, Inst Theoret Phys, Lehrstuhl Weltraum & Astrophys 4, D-44780 Bochum, Germany. RI Koribalski, Baerbel/B-9987-2008 NR 26 TC 15 Z9 15 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2002 VL 571 IS 1 BP 366 EP 377 DI 10.1086/339843 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550TJ UT WOS:000175519000027 ER PT J AU Steinacker, A Papaloizou, JCB AF Steinacker, A Papaloizou, JCB TI Three-dimensional magnetohydrodynamic simulations of an accretion disk with star-disk boundary layer SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; instabilities; methods : numerical; MHD; turbulence ID DYNAMO-GENERATED TURBULENCE; ANGULAR-MOMENTUM TRANSPORT; 3-DIMENSIONAL SIMULATIONS; MAGNETIC-FIELD; INSTABILITY; OSCILLATIONS; VISCOSITY; STABILITY; GROWTH; FLOWS AB We present global three-dimensional MHD simulations of geometrically thin but unstratified accretion disks in which a near-Keplerian disk rotates between two bounding regions with initial rotation profiles that are stable to the magnetorotational instability (MRI). The inner region models the boundary layer between the disk and an assumed more slowly rotating central, nonmagnetic star. We investigate the dynamical evolution of this system in response to initial vertical and toroidal fields imposed in a variety of domains contained within the near-Keplerian disk. Cases with both nonzero and zero net magnetic flux are considered, and sustained dynamo activity is found in runs for up to 50 orbital periods at the outer boundary of the near-Keplerian disk. We find a progression of behavior regarding the turbulence resulting from the MRI and the evolving structure of the disk and boundary layer according to the initial field configuration. Simulations starting from fields with small radial scale and with zero net flux lead to the lowest levels of turbulence and smoothest variation of disk mean state variables. As found in local simulations, the final outcome is shown to be independent of the form of the imposed field. For our computational setup, average values of the Shakura Sunyaev alpha-parameter in the Keplerian disk are typically 0.004 +/- 0.002. The magnetic field eventually always diffuses into the boundary layer, resulting in the buildup of toroidal field, inward angular momentum transport, and the accretion of disk material. The mean radial velocity, while exhibiting large temporal fluctuations, is always subsonic. Simulations starting with net toroidal flux may yield an average alpha similar to 0.04. While being characterized by 1 order of magnitude larger average alpha, simulations starting from vertical fields with large radial scale and net flux may lead to the formation of persistent nonhomogeneous, nonaxisymmetric magnetically dominated regions of very low density. In these gaps, angular momentum transport occurs through magnetic torques acting between regions on either side of the gap. Local turbulent transport occurs where the magnetic field is not dominant. These simulations are indicative of the behavior of the disk when threaded by magnetic flux originating from an external source. However, the influence of such presumed sources in determining the boundary conditions that should be applied to the disk remains to be investigated. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ London Queen Mary & Westfield Coll, Sch Math Sci, Astron Unit, London E1 4NS, England. RP Steinacker, A (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 35 TC 56 Z9 56 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2002 VL 571 IS 1 BP 413 EP 428 DI 10.1086/339892 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550TJ UT WOS:000175519000030 ER PT J AU Ikeda, M Ohishi, M Nummelin, A Dickens, JE Bergman, P Hjalmarson, A Irvine, WM AF Ikeda, M Ohishi, M Nummelin, A Dickens, JE Bergman, P Hjalmarson, A Irvine, WM TI Survey observations of c-C2H4O and CH3CHO toward massive star-forming regions (vol 560, pg 792, 2001) SO ASTROPHYSICAL JOURNAL LA English DT Correction C1 Natl Astron Observ, Tokyo 181, Japan. Chalmers Lindholmen Univ Coll, Gothenburg, Sweden. CALTECH, Jet Prop Lab, Pasadena, CA USA. Chalmers Univ Technol, Onsala Space Observ, S-43900 Onsala, Sweden. Univ Massachusetts, Amherst, MA 01003 USA. RP Ikeda, M (reprint author), Natl Astron Observ, Tokyo 181, Japan. EM miho.ikeda@nao.ac.jp; masatoshi.ohishi@nao.ac.jp; albert.nummelin@chl.chalmers.se; jdickens@mail1.jpl.nasa.gov; bergman@oso.chalmers.se; hjalmar@oso.chalmers.se; irvine@fcrao1.astro.umass.edu NR 1 TC 5 Z9 5 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2002 VL 571 IS 1 BP 560 EP 561 DI 10.1086/339861 PN 1 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550TJ UT WOS:000175519000044 ER PT J AU Camilo, F Stairs, IH Lorimer, DR Backer, DC Ransom, SM Klein, B Wielebinski, R Kramer, M McLaughlin, MA Arzoumanian, Z Muller, P AF Camilo, F Stairs, IH Lorimer, DR Backer, DC Ransom, SM Klein, B Wielebinski, R Kramer, M McLaughlin, MA Arzoumanian, Z Muller, P TI Discovery of radio pulsations from the X-ray pulsar J0205+6449 in supernova remnant 3C 58 with the Green Bank Telescope SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (3C 58); pulsars : individual (PSR J0205+6449); supernova remnants ID YOUNG PULSARS; SEARCH AB We report the discovery with the 100 m Green Bank Telescope of 65 ms radio pulsations from the X-ray pulsar J0205+6449 at the center of supernova remnant 3C 58, making this possibly the youngest radio pulsar known. From our observations at frequencies of 820 and 1375 MHz, the free-electron column density to PSR J0205+6449 is found to be 140.7 +/- 0.3 cm(-3) pc. The barycentric pulsar period P and period derivative (P) over dot determined from a phase-coherent timing solution are consistent with the values previously measured from X-ray observations. The averaged radio profile of PSR J0205+6449 consists of one sharp pulse of width approximate to3 ms approximate to0.05P. The pulsar is an exceedingly weak radio source, with a pulse-averaged flux density in the 1400 MHz band of similar to45 muJy and a spectral index of similar to-2.1. Its radio luminosity of similar to0.5 mJy kpc(2) at 1400 MHz is lower than that of similar to99% of known pulsars and is the lowest among known young pulsars. C1 Columbia Univ, Columbia Astrophys Lab, New York, NY 10027 USA. Natl Radio Astron Observ, Green Bank, WV 24944 USA. Univ Manchester, Jodrell Bank Observ, Macclesfield SK11 9DL, Cheshire, England. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. McGill Univ, Dept Phys, Montreal, PQ H3A 2T8, Canada. MIT, Ctr Space Res, Cambridge, MA 02139 USA. Max Planck Inst Radioastron, D-53121 Bonn, Germany. NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. RP Camilo, F (reprint author), Columbia Univ, Columbia Astrophys Lab, 550 W 120th St, New York, NY 10027 USA. OI Ransom, Scott/0000-0001-5799-9714 NR 21 TC 66 Z9 66 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2002 VL 571 IS 1 BP L41 EP L44 DI 10.1086/341178 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550TQ UT WOS:000175519700009 ER PT J AU Hollis, JM Lovas, FJ Jewell, PR Coudert, LH AF Hollis, JM Lovas, FJ Jewell, PR Coudert, LH TI Interstellar antifreeze: Ethylene glycol SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : individual (Sagittarius B2(N-LMH)); ISM : molecules; radio lines : ISM ID TORSIONAL SPECTRUM; GLYCOLALDEHYDE; CONFORMER; SUGAR AB Interstellar ethylene glycol (HOCH2CH2OH) has been detected in emission toward the Galactic center source Sagittarius B2( N-LMH) by means of several millimeter-wave rotational torsional transitions of its lowest energy conformer. The types and kinds of molecules found to date in interstellar clouds suggest a chemistry that favors aldehydes and their corresponding reduced alcohols-e.g., formaldehyde (H2CO)/methanol (CH3OH), acetal-dehyde (CH3CHO) ethanol (CH3CH2OH). Similarly, ethylene glycol is the reduced alcohol of glycolaldehyde (CH2OHCHO), which has also been detected toward Sgr B2( N-LMH). While there is no consensus as to how any such large complex molecules are formed in the interstellar clouds, atomic hydrogen (H) and carbon monoxide (CO) could form formaldehyde on grain surfaces, but such surface chemistry beyond that point is uncertain. However, laboratory experiments have shown that the gas-phase reaction of atomic hydrogen (H) and solid-phase CO at 10-20 K can produce formaldehyde and methanol and that alcohols and other complex molecules can be synthesized from cometary ice analogs when subject to ionizing radiation at 15 K. Thus, the presence of aldehyde/reduced alcohol pairs in interstellar clouds implies that such molecules are a product of a low-temperature chemistry on grain surfaces or in grain ice mantles. This work suggests that aldehydes and their corresponding reduced alcohols provide unique observational constraints on the formation of complex interstellar molecules. C1 NASA, Goddard Space Flight Ctr, Earth & Space Data Comp Div, Greenbelt, MD 20771 USA. Univ Illinois, Dept Astron, Urbana, IL 61801 USA. Natl Radio Astron Observ, Green Bank, WV 24944 USA. Univ Paris 11, Photophys Mol Lab, F-91405 Orsay, France. RP Hollis, JM (reprint author), NASA, Goddard Space Flight Ctr, Earth & Space Data Comp Div, Code 930, Greenbelt, MD 20771 USA. NR 17 TC 90 Z9 90 U1 1 U2 16 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2002 VL 571 IS 1 BP L59 EP L62 DI 10.1086/341148 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550TQ UT WOS:000175519700013 ER PT J AU Reames, DV AF Reames, DV TI Magnetic topology of impulsive and gradual solar energetic particle events SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; shock waves; Sun : abundances; Sun : corona; Sun : particle emission ID CORONAL MASS EJECTIONS; INTERPLANETARY SHOCKS; HE-3-RICH EVENTS; PROTON EVENTS; ACCELERATION; FLARES; HE-3; WAVES; ABUNDANCES; INJECTION AB We examine the magnetic topology at the Sun that leads to the two classes of impulsive and gradual solar energetic particle (SEP) events so as to address new observations that seem to blur this classification, for example, that coronal mass ejections (CMEs) can accompany events of both classes. In our model, the unusual element abundances in impulsive SEP events result from resonant stochastic acceleration in magnetic reconnection regions that incorporate open magnetic field lines, allowing both accelerated ions and ejected plasma to escape. In the large gradual events that produce classic CMEs, reconnection occurs on closed field lines beneath the CME where the accelerated particles are trapped so they plunge into the solar atmosphere to produce a flare; they cannot escape. The SEPs seen at 1 AU in these large gradual events are accelerated by the shock wave driven outward by the CME. The shock-accelerated particles are derived from the local plasma and from reaccelerated suprathermal ions from previous impulsive or gradual SEP events. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Reames, DV (reprint author), NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. NR 46 TC 86 Z9 86 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 2002 VL 571 IS 1 BP L63 EP L66 DI 10.1086/341149 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550TQ UT WOS:000175519700014 ER PT J AU Jeevarajan, AS Vani, S Taylor, TD Anderson, MM AF Jeevarajan, AS Vani, S Taylor, TD Anderson, MM TI Continuous pH monitoring in a perfused bioreactor system using an optical pH sensor SO BIOTECHNOLOGY AND BIOENGINEERING LA English DT Article DE pH; optical sensor; non-invasive; phenol red; cell culture ID PHENOL RED AB Monitoring and regulating the pH of the solution in a bioprocess is one of the key steps in the success of bioreactor operation. An in-line optical pH sensor, based on the optical absorption properties of phenol red present in the medium, was developed and tested in this work for use in NASA space bioreactors based on a rotating wall-perfused vessel system supporting a baby hamster kidney (BHK-21) cell culture. The sensor was tested over three 30-day and one 124-day cell runs. The pH sensor initially was calibrated and then used during the entire cell culture interval. The pH reported by the sensor was compared to that measured by a fiber optically coupled Shimadzu spectrophotometer and a blood gas analyzer. The maximum standard error of prediction for all the four cell runs for development pH sensor against BGA was +/-0.06 pH unit and for the fiber optically coupled Shimadzu spectrophotometer against the blood gas analyzer was +/-0.05 pH unit. The pH sensor system performed well without need of recalibration for 124 days. (C) 2002 Wiley Periodicals, Inc.*. C1 Life Sci Syst & Serv, Wyle Labs, Houston, TX 77058 USA. Monsanto Co, Tulsa, OK USA. NASA, Biotechnol Program, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Jeevarajan, AS (reprint author), Life Sci Syst & Serv, Wyle Labs, 1290 Hercules Dr,Suite 120,Mail Stop BT-37, Houston, TX 77058 USA. NR 17 TC 38 Z9 39 U1 1 U2 13 PU JOHN WILEY & SONS INC PI HOBOKEN PA 111 RIVER ST, HOBOKEN, NJ 07030 USA SN 0006-3592 J9 BIOTECHNOL BIOENG JI Biotechnol. Bioeng. PD MAY 20 PY 2002 VL 78 IS 4 BP 467 EP 472 DI 10.1002/bit.10212 PG 6 WC Biotechnology & Applied Microbiology SC Biotechnology & Applied Microbiology GA 547VU UT WOS:000175353900013 PM 11948454 ER PT J AU Sandham, ND Li, Q Yee, HC AF Sandham, ND Li, Q Yee, HC TI Entropy splitting for high-order numerical simulation of compressible turbulence SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID CHANNEL FLOW AB A stable high-order numerical scheme for direct numerical simulation (DNS) of shock-free compressible turbulence is presented. The method is applicable to general geometries. It contains no upwinding, artificial dissipation. or filtering. Instead the method relies on the stabilizing mechanisms of an appropriate conditioning of the governing equations and the use of compatible spatial difference operators for the interior points (interior scheme) as well as the boundary points (boundary scheme). An entropy-splitting approach splits the inviscid flux derivatives into conservative and nonconservative portions. The spatial difference operators satisfy a summation-by-parts condition, leading to a stable scheme (combined interior and boundary schemes) for the initial boundary value problem using a generalized energy estimate. A Laplacian formulation of the viscous and heat conduction terms on the right hand side of the Navier-Stokes equations is used to ensure that any tendency to odd-even decoupling associated with central schemes can be countered by the fluid viscosity. The resulting methods are able to minimize the spurious high-frequency oscillations associated with pure central schemes. especially for long time integration applications such as DNS. For validation purposes, the methods are tested in a DNS of compressible turbulent plane channel flow at low values of friction Mach number, where reference turbulence data bases exist. It is demonstrated that the methods are robust in terms of grid resolution, and in good agreement with published channel data, Accurate turbulence statistics can be obtained with moderate grid sizes. Stability limits on the range of the splitting parameter are determined from numerical tests. (C) 2002 Elsevier Science (USA). C1 Univ Southampton, Sch Engn Sci, Southampton SO17 1BJ, Hants, England. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Sandham, ND (reprint author), Univ Southampton, Sch Engn Sci, Southampton SO17 1BJ, Hants, England. RI Sandham, Neil/G-4755-2010 NR 21 TC 87 Z9 88 U1 0 U2 7 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD MAY 20 PY 2002 VL 178 IS 2 BP 307 EP 322 DI 10.1006/jcph.2002.7022 PG 16 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 552AK UT WOS:000175596000003 ER PT J AU Claustre, H Morel, A Hooker, SB Babin, M Antoine, D Oubelkheir, K Bricaud, A Leblanc, K Queguiner, B Maritorena, S AF Claustre, H Morel, A Hooker, SB Babin, M Antoine, D Oubelkheir, K Bricaud, A Leblanc, K Queguiner, B Maritorena, S TI Is desert dust making oligotrophic waters greener? SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SAHARAN DUST; CASE-1 WATERS; CHLOROPHYLL-A; OCEAN; LIGHT; SCATTERING; INPUTS; IMPACT AB [1] In situ optical measurements provide evidence that oligotrophic waters of the Mediterranean Sea have a greener color than would result from their phytoplankton content alone. This anomaly, detectable in low chlorophyll waters, remains unnoticed in the chlorophyll-rich waters of the nearby waters of the Moroccan upwelling zone. It is due to enhanced absorption in the blue and enhanced backscattering in the green parts of the visible spectrum likely resulting from the presence of submicron Saharan dust in suspension within the upper layer. This result implies that regional estimations of carbon fixation from ocean color images might be significantly overestimated, not only in the Mediterranean Sea, but also in other oligotrophic areas of the Northern hemisphere, subjected to desert dust deposition. C1 CNRS, INSU, Lab Oceanog Villefranche, Observ Oceanol, F-06238 Villefranche Sur Mer, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Ctr Oceanol Marseille, Lab Oceanog & Biogeochim, F-13288 Marseille, France. Univ Calif Santa Barbara, Inst Computat Earth Syst Sci, Santa Barbara, CA 93106 USA. RP Claustre, H (reprint author), CNRS, INSU, Lab Oceanog Villefranche, Observ Oceanol, BP 08, F-06238 Villefranche Sur Mer, France. EM claustre@obs-vlfr.fr; Morel@obs-vlfr.fr; stan@ardbeg.gsfc.nasa.gov; babin@obs-vlfr.fr; antoine@obs-vlfr.fr; kadija@obs-vlfr.fr; bricaud@obs-vlfr.fr; karine.leblanc@com.univ-mrs.fr; bernard.queguiner@com.univ-mrs.fr; stephane@icess.ucsb.edu RI Queguiner, Bernard/B-4060-2008; Leblanc, Karine/C-6029-2009; oubelkheir, kadija/H-3843-2011; Hooker, Stanford/E-2162-2012; Antoine, David/C-3817-2013; CLAUSTRE, Herve/E-6877-2011 OI Queguiner, Bernard/0000-0001-5020-8297; Antoine, David/0000-0002-9082-2395; CLAUSTRE, Herve/0000-0001-6243-0258 NR 23 TC 75 Z9 75 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 2002 VL 29 IS 10 AR 1469 DI 10.1029/2001GL014056 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300037 ER PT J AU Curtis, S Huffman, GJ Adler, RF AF Curtis, S Huffman, GJ Adler, RF TI Precipitation anomalies in the tropical Indian Ocean and their relation to the initiation of El Nino SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MADDEN-JULIAN OSCILLATION; PACIFIC-OCEAN; ENSO; PREDICTABILITY; PREDICTION; CONVECTION; ONSET AB [1] A pattern of intraseasonal to interannual variability in precipitation and surface winds for the eastern equatorial Indian Ocean (EEIO) during 1979 to 1999 is described using combined Empirical Orthogonal Function (EOF) analyses. The main features of the positive phase of the EEIO mode are 1) enhanced precipitation to the south of the island of Sumatra, 2) suppressed precipitation in the central equatorial Indian Ocean, 3) surface westerly wind anomalies directed from the dry toward the wet region, and 4) southeasterly wind anomalies which meet the westerly anomalies in the vicinity of the enhanced precipitation. A relationship was found between the precipitation gradient of the EEIO mode and the five strongest El Nino events since 1979 (1982/ 83, 1986/ 87, 1991/ 92, 1994/ 95, and 1997/ 98). For the cases when the interannual component of the gradient reached a positive peak followed by significant power (94%) in the 30- 60 day component of the gradient roughly a season later, an El Nino was observed to develop. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. Sci Syst & Applicat Inc, Lanham, MD USA. RP Curtis, S (reprint author), NASA, Goddard Space Flight Ctr, Code 912, Greenbelt, MD 20771 USA. RI Curtis, Scott/C-1115-2013; Huffman, George/F-4494-2014; OI Huffman, George/0000-0003-3858-8308; Curtis, Scott/0000-0001-9065-8639 NR 20 TC 9 Z9 9 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 15 PY 2002 VL 29 IS 10 AR 1441 DI 10.1029/2001GL013399 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300065 ER PT J AU Dubovik, O Holben, BN Lapyonok, T Sinyuk, A Mishchenko, MI Yang, P Slutsker, I AF Dubovik, O Holben, BN Lapyonok, T Sinyuk, A Mishchenko, MI Yang, P Slutsker, I TI Non-spherical aerosol retrieval method employing light scattering by spheroids SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SKY BRIGHTNESS MEASUREMENTS; SIZE DISTRIBUTION; OPTICAL-PROPERTIES; TROPOSPHERIC AEROSOLS; RADIANCE MEASUREMENTS; REMOTE; PARTICLES; DUST; NETWORK; AERONET AB [1] Numerous studies indicate the need to account for particle non-sphericity in modeling the optical properties of dustlike aerosols. The methods for simulating the scattering of light by various non-spherical shapes have rapidly evolved over the last two decades. However, the majority of aerosol remote-sensing retrievals still rely on the Mie theory because retrievals accounting for particle non-sphericity are not as well defined methodologically and are demanding computationally. We propose a method for the retrieval of the optical properties of non-spherical aerosol based on the model of a shape mixture of randomly oriented polydisperse spheroids. This method is applied to angular and spectral radiation measurements from the Aerosol Robotic Network (AERONET) in locations influenced by desert dust. Comparisons with Mie-based retrievals show a significant improvement in dust-particle phase functions, size distributions, and refractive indices. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Texas A&M Univ, College Stn, TX 77843 USA. Univ Maryland Baltimore Cty, Baltimore, MD 21228 USA. Sci Syst & Appl Inc, Lanham, MD USA. RP Dubovik, O (reprint author), NASA, Goddard Space Flight Ctr, Code 923, Greenbelt, MD 20771 USA. RI Dubovik, Oleg/A-8235-2009; Yang, Ping/B-4590-2011; Mishchenko, Michael/D-4426-2012 OI Dubovik, Oleg/0000-0003-3482-6460; NR 24 TC 195 Z9 198 U1 4 U2 24 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 2002 VL 29 IS 10 AR 1415 DI 10.1029/2001GL014506 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300091 ER PT J AU Frey, HV Roark, JH Shockey, KM Frey, EL Sakimoto, SEH AF Frey, HV Roark, JH Shockey, KM Frey, EL Sakimoto, SEH TI Ancient lowlands on Mars SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CRUSTAL DICHOTOMY; IMPACT BASINS; EVOLUTION; ORIGIN; TOPOGRAPHY; CONVECTION; UTOPIA AB [1] Mars Orbiter Laser Altimeter (MOLA) data provide compelling evidence that the martian lowlands, below the smooth and sparsely cratered northern plains, are extremely old, far older than the plains which cover them. The evidence is in the form of a very large population of "Quasi-Circular Depressions'' (QCDs), many of which are very evident in the MOLA elevation data but generally not visible in available imagery. We interpret these "invisible'' QCDs to be buried impact basins. Cumulative number versus diameter curves for lowland QCDs suggests the buried lowland surface is older than the visible highland surface and that the lowland plains are a relatively thin (1-2 km) veneer overlying this much older surface. We conclude that the martian lowlands have been low and stable for nearly all of martian history. C1 NASA, Goddard Space Flight Ctr, Geodynam Branch, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, SSA Geodynam Branch, Greenbelt, MD 20771 USA. S River High Sch, Edgewater, MD 21037 USA. Univ Maryland Baltimore Cty, Goddard Space Flight Ctr, Geodynam Branch, GEST, Greenbelt, MD 20771 USA. RP Frey, HV (reprint author), NASA, Goddard Space Flight Ctr, Geodynam Branch, Sci Syst & Applicat Inc, Code 921, Greenbelt, MD 20771 USA. NR 23 TC 137 Z9 138 U1 1 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 2002 VL 29 IS 10 AR 1384 DI 10.1029/2001GL013832 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300122 ER PT J AU Halekas, JS Mitchell, DL Lin, RP Hood, LL Acuna, MH Binder, AB AF Halekas, JS Mitchell, DL Lin, RP Hood, LL Acuna, MH Binder, AB TI Evidence for negative charging of the lunar surface in shadow SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR-WIND; SPACECRAFT; PROSPECTOR AB [1] Observations of electron distributions above the shadowed surface of the Moon show energy-dependent loss cones which indicate reflection by both magnetic and electric fields. At the same time, low energy (less than or similar to100 eV) field aligned upward-going electron beams are observed. Together, these observations imply average night-side potential differences between the surface and the Lunar Prospector (LP) spacecraft of 35 V. The lunar surface may be at an even higher negative potential relative to the ambient plasma, since LP will likely also charge negative. The potential difference is consistent with simple current balance models which include secondary emission. No clear dependence is found on surface terrane type and age, or on ambient electron density and temperature. Instead, the potential difference is found to depend strongly on the angle from the subsolar point and the angle between the magnetic field and the normal to the lunar surface. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Lunar Res Inst, Tucson, AZ 85747 USA. RP Halekas, JS (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NR 12 TC 45 Z9 47 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 2002 VL 29 IS 10 AR 1435 DI 10.1029/2001GL014428 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300071 ER PT J AU Hicke, JA Asner, GP Randerson, JT Tucker, C Los, S Birdsey, R Jenkins, JC Field, C Holland, E AF Hicke, JA Asner, GP Randerson, JT Tucker, C Los, S Birdsey, R Jenkins, JC Field, C Holland, E TI Satellite-derived increases in net primary productivity across North America, 1982-1998 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TERRESTRIAL CARBON SINK; INTERANNUAL VARIABILITY; LAND; DECLINE; AGE AB [1] We used a new 17-year, high spatial resolution satellite record and a carbon cycle model to explore how changing net primary productivity (NPP) contributed to a proposed carbon (C) sink in North America. We found a small but significant increase in NPP, 0.03 Pg C yr(-2) or 8% over 17 years, that could explain a substantial fraction of the C sink. The largest increases occurred in the central and southeastern United States, eastern Canada, and northwestern North America, and were consistent with NPP trends derived from forest inventories and crop yields. Interannual NPP variability was small, implying that the large interannual variability in the C sink found in previous studies were driven by changes in heterotrophic respiration. C1 Univ Colorado, Dept Geol Sci, Boulder, CO 80309 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. NASA, Goddard Space Flight Ctr, Lab Atmospher Phys, Greenbelt, MD 20771 USA. USDA, Forest Serv, Newtown Sq, PA 19073 USA. Carnegie Inst Washington, Stanford, CA 94305 USA. Natl Ctr Atmospher Res, Boulder, CO 80305 USA. RP Hicke, JA (reprint author), Univ Colorado, Dept Geol Sci, Boulder, CO 80309 USA. RI Los, Sietse/G-8985-2012; Hicke, Jeff/M-9677-2013; Asner, Gregory/G-9268-2013 OI Asner, Gregory/0000-0001-7893-6421 NR 27 TC 60 Z9 68 U1 5 U2 20 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 2002 VL 29 IS 10 AR 1427 DI 10.1029/2001GL013578 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300079 ER PT J AU Hnat, B Chapman, SC Rowlands, G Watkins, NW Farrell, WM AF Hnat, B Chapman, SC Rowlands, G Watkins, NW Farrell, WM TI Finite size scaling in the solar wind magnetic field energy density as seen by WIND SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TURBULENCE; DISTRIBUTIONS; INTERMITTENCY; FLUCTUATIONS; PLASMA AB [1] Statistical properties of the interplanetary magnetic field fluctuations can provide an important insight into the solar wind turbulent cascade. Recently, analysis of the Probability Density Functions (PDF) of the velocity and magnetic field fluctuations has shown that these exhibit non- Gaussian properties on small time scales while large scale features appear to be uncorrelated. Here we apply the finite size scaling technique to explore the scaling of the magnetic field energy density fluctuations as seen by WIND. We find a single scaling sufficient to collapse the curves over the entire investigated range. The rescaled PDF follow a non Gaussian distribution with asymptotic behavior well described by the Gamma distribution arising from a finite range Levy walk. Such mono scaling suggests that a Fokker- Planck approach can be applied to study the PDF dynamics. These results strongly suggest the existence of a common, nonlinear process on the time scale up to 26 hours. C1 Univ Warwick, Space & Astrophys Grp, Coventry CV4 7AJ, W Midlands, England. British Antarctic Survey, Cambridge CB3 0ET, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Hnat, B (reprint author), Univ Warwick, Space & Astrophys Grp, Coventry CV4 7AJ, W Midlands, England. RI Chapman, Sandra/C-2216-2008; Watkins, Nicholas/C-5140-2008; Farrell, William/I-4865-2013 OI Chapman, Sandra/0000-0003-0053-1584; Watkins, Nicholas/0000-0003-4484-6588; NR 22 TC 44 Z9 44 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 2002 VL 29 IS 10 AR 1446 DI 10.1029/2001GL014587 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300060 ER PT J AU Jakowski, N Wehrenpfennig, A Heise, S Reigber, C Luhr, H Grunwaldt, L Meehan, TK AF Jakowski, N Wehrenpfennig, A Heise, S Reigber, C Luhr, H Grunwaldt, L Meehan, TK TI GPS radio occultation measurements of the ionosphere from CHAMP: Early results SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ATMOSPHERE; SYSTEM AB [1] The paper deals with initial analyzes of radio occultation measurements of the ionosphere carried out on board the CHAMP satellite since 11 April 2001. The accuracy of the operationally retrieved electron density profiles has been estimated by comparing with independent measurements. The derived ionospheric key parameters such as f0F2 and hmF2 agree with a standard deviation of 18 and 13%, respectively. It is shown that the CHAMP data products can essentially contribute to the establishment of operational data sets of the global electron density distribution for developing and improving global ionospheric models and to provide operational space weather information. C1 Deutsch Zentrum Luft & Raumfahrt DLR, Inst Kommunikat & Navigat, D-17235 Neustrelitz, Germany. Geoforschungszentrum Potsdam, D-14473 Potsdam, Germany. Jet Prop Lab, Pasadena, CA USA. RP Jakowski, N (reprint author), Deutsch Zentrum Luft & Raumfahrt DLR, Inst Kommunikat & Navigat, Kalkhorstweg 53, D-17235 Neustrelitz, Germany. RI Heise, Stefan/K-2190-2013 NR 10 TC 74 Z9 74 U1 2 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 2002 VL 29 IS 10 AR 1457 DI 10.1029/2001GL014364 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300049 ER PT J AU Kar, J Trepte, CR Thomason, LW Zawodny, JM AF Kar, J Trepte, CR Thomason, LW Zawodny, JM TI Observations of layers in ozone vertical profiles from SAGE II (v 6.0) measurements SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TRACER LAMINATION; STRATOSPHERE AB [1] Layered structures in the vertical profiles of ozone mixing ratio as retrieved by the Stratospheric Aerosol and Gas Experiment (SAGE II) version 6.0 have been studied in the altitude range 10-28 km in the middle and high latitudes (30-75 N and S). 12 years of data (1985-1990, 1994-1999) have been used to build a climatology of layers with thickness of a few kilometers. The occurrence peaks near 12-13 km, then decreases sharply up to about 20 km before increasing again in the 20-28 km range. The seasonal variation indicates that layering activity maximizes during winter-spring in both hemispheres. This is similar to earlier results on thinner structures or laminae. A significant number of layers were observed in summer at altitudes >20 km in both hemispheres primarily at high latitudes (>60 N and S). C1 Univ Arizona, Tucson, AZ 85721 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Kar, J (reprint author), Univ Arizona, Tucson, AZ 85721 USA. OI Thomason, Larry/0000-0002-1902-0840 NR 13 TC 5 Z9 5 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 2002 VL 29 IS 10 AR 1433 DI 10.1029/2001GL014230 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300073 ER PT J AU Lait, LR AF Lait, LR TI Systematic differences between radiosonde instruments SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB [1] Deviations of radiosonde geopotential heights from the zonal mean are examined. In the summer Northern Hemisphere stratosphere, systematic differences are found between radiosonde instrument types. Persistent meridional wind anomalies, approximately constant in magnitude and fixed in location, have previously been reported in the summer stratosphere, and one such anomaly over Europe is found to be co-located with boundaries between regions in which differing types of radiosonde instruments are used. The magnitude and orientation of the radiosonde geopotential height biases are consistent with the wind anomalies. Because the overall winds tend to be light in this region and season, these wind anomalies can represent significant perturbations of the flow and must be considered when interpreting the results of trajectory and diagnostic studies. C1 Sci Syst & Applicat Inc, Lanham, MD USA. RP Lait, LR (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20071 USA. NR 5 TC 4 Z9 4 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 2002 VL 29 IS 10 AR 1382 DI 10.1029/2001GL014337 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300124 ER PT J AU Leung, FYT Colussi, AJ Hoffmann, MR Toon, GC AF Leung, FYT Colussi, AJ Hoffmann, MR Toon, GC TI Isotopic fractionation of carbonyl sulfide in the atmosphere: Implications for the source of background stratospheric sulfate aerosol SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NITROUS-OXIDE; SULFURIC-ACID; MODEL; OCS; BALLOON; LAYER AB [1] In order to assess the contribution of carbonyl sulfide to stratospheric sulfate aerosol (SSA), we examined the stratospheric (OCS)-S-34 and (OCS)-S-32 concentration profiles in the infrared limb-transmittance spectra acquired by the JPL MkIV instrument. We found that (OCS)-S-34 is preferentially depleted by solar photolysis. The derived S-34 enrichment factor: epsilon = + 73.8 +/- 8.6parts per thousand, in conjunction with literature values of delta(34)S +11parts per thousand for tropospheric OCS, and a similar to 10% net processing of the OCS transported upwardly into the stratosphere, suggests that aerosol sulfate proceeding from OCS should be highly enriched in delta(34)S similar to80parts per thousand, comparing our prediction with previous reports of delta(34)S similar to+2.6parts per thousand for background SSA, we infer either that OCS is a minor contributor to SSA or that current views about its S-34-abundance and atmospheric circulation are seriously flawed. C1 CALTECH, WM Keck, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Leung, FYT (reprint author), CALTECH, WM Keck Labs 138 78, Pasadena, CA 91125 USA. RI Colussi, Agustin/C-6520-2008 NR 26 TC 18 Z9 18 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 2002 VL 29 IS 10 AR 1474 DI 10.1029/2001GL013955 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300032 ER PT J AU Lin, II Wen, LS Liu, KK Tsai, WT Liu, AK AF Lin, II Wen, LS Liu, KK Tsai, WT Liu, AK TI Evidence and quantification of the correlation between radar backscatter and ocean colour supported by simultaneously acquired in situ sea truth SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SYNTHETIC-APERTURE RADAR; SURFACE; TAIWAN; FILMS AB [1] Near simultaneously (within 2 hours) acquired ERS-2 Synthetic Aperture Radar (SAR) and Sea-viewing Wide Field-of-view Scanner (SeaWiFS) data over an upwelling region shows remarkable similarity in feature's location, scale, and boundary. Under uniform wind and sea states, reduction of Normalised Radar Cross Section (NRCS) from SAR is found highly correlated with the increase of SeaWiFS Chlorophyll-a (Chl-a) concentration. Typically, 1 mg/m3 of chlorophyll-a is correspondent with a 5 dB reduction of NRCS. This relationship is supported by simultaneously collected in situ sea truth measurements. This work provides a direct evidence and exceptional quantification of the relationship between radar backscatter and ocean colour that has long been speculated. C1 Natl Ctr Ocean Res, Taipei 10617, Taiwan. Natl Chiao Tung Univ, Hsinchu, Taiwan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Lin, II (reprint author), Natl Ctr Ocean Res, POB 23-13, Taipei 10617, Taiwan. RI Tsai, Wu-ting/D-1501-2011; Wen, Liang-Saw/B-6245-2012; Lin, I-I/J-4695-2013; Tsai, Wu-ting/A-3678-2017 OI Lin, I-I/0000-0002-8364-8106; Tsai, Wu-ting/0000-0002-5379-9421 NR 18 TC 9 Z9 9 U1 4 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 2002 VL 29 IS 10 AR 1464 DI 10.1029/2001GL014039 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300042 ER PT J AU Lin, JS Tabazadeh, A AF Lin, JS Tabazadeh, A TI The effect of nitric acid uptake on the deliquescence and efflorescence of binary ammoniated salts in the upper troposphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID METASTABILITY PHASE-DIAGRAMS; AEROSOLS; TEMPERATURES; EQUILIBRIUM; CHEMISTRY; PARTICLES; SULFATE; SYSTEM; MODEL; SIZE AB [1] Thermodynamic equilibrium model calculations are used to show that HNO3 can lower the relative humidity barrier to deliquesce binary ammoniated salts in the upper troposphere, particularly in aerosol solutions with an (NH4)(2)SO4 composition. Also in the case of (NH4)(2)SO4 or NH4HSO4 there is no abrupt change in the physical state of the thermodynamic system (instantaneous change of a dry salt particle into an aqueous solution) at the deliquescent point, which is typical for such a phase transition. Model results show that HNO3 dissolution in ammoniated aerosol solutions can prevent the efflorescence of (NH4)(2)SO4 and NH4HSO4 salts in favor of (NH4)(3)H(SO4)(2) (letovicite) crystallization. Future laboratory experiments, where binary ammoniated salts are studied at cold temperatures in the presence of both HNO3 and H2O, are needed to confirm the results of our model calculations. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Lin, JS (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 19 TC 6 Z9 6 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 2002 VL 29 IS 10 AR 1488 DI 10.1029/2002GL015251 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300018 ER PT J AU Lowe, ST Zuffada, C Chao, Y Kroger, P Young, LE LaBrecque, JL AF Lowe, ST Zuffada, C Chao, Y Kroger, P Young, LE LaBrecque, JL TI 5-cm-precision aircraft ocean altimetry using GPS reflections SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SIGNALS; PARIS AB [1] We present the first two aircraft Global Positioning System (GPS)-reflection altimetry measurements, the most precise GPS ocean-altimetry measurement, and demonstrate the altimetric precision and spatial resolution necessary to map mesoscale eddies. Our first experiment demonstrated a 14-cm precision single-satellite ocean altimetry measurement while our more recent experiment demonstrates 5 cm altimetric precision with 5-km spatial resolution. The new results show significant improvement over our previous effort, due to improved modeling, greater aircraft altitudes and velocities, improved receiver positioning, and better experimental control. Plans to further reduce speckle and refine models to obtain 5-cm altimetric accuracy are presented. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA Headquarters, Washington, DC USA. RP Lowe, ST (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 22 TC 59 Z9 64 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 2002 VL 29 IS 10 AR 1375 DI 10.1029/2002GL014759 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300131 ER PT J AU Mendes, VB Prates, G Pavlis, EC Pavlis, DE Langley, RB AF Mendes, VB Prates, G Pavlis, EC Pavlis, DE Langley, RB TI Improved mapping functions for atmospheric refraction correction in SLR SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INDEX; AIR AB [1] We present two new mapping functions (MFs) to model the elevation angle dependence of the atmospheric delay for satellite laser ranging (SLR) data analysis. The new MFs were derived from ray tracing through a set of data from 180 radiosonde stations globally distributed, for the year 1999, and are valid for elevation angles above 3degrees. When compared against ray tracing of two independent years of radiosonde data (1997-1998) for the same set of stations, our MFs reveal submillimetre accuracy for elevation angles above 10degrees, representing a significant improvement over other MFs, and is confirmed in improved solutions of LAGEOS and LAGEOS 2 data analysis. C1 Univ Lisbon, Fac Ciencias, Lab Tectonofis & Tecton Expt, P-1749016 Lisbon, Portugal. Univ Lisbon, Fac Ciencias, Dept Matemat, P-1749016 Lisbon, Portugal. Univ Algarve, Escola Super Tecnol, Faro, Portugal. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Greenbelt, MD 20771 USA. NASA, Greenbelt, MD 20771 USA. Raytheon Informat Technol & Sci Serv, Greenbelt, MD 20771 USA. Univ New Brunswick, Dept Geodesy & Geomat Engn, Geodet Res Lab, Fredericton, NB E3B 5A3, Canada. RP Mendes, VB (reprint author), Univ Lisbon, Fac Ciencias, Lab Tectonofis & Tecton Expt, P-1749016 Lisbon, Portugal. EM vmendes@fc.ul.pt; gprates@ualg.pt; epavlis@helmert.gsfc.nasa.gov; dpavlis@magus.stx.com; lang@unb.ca RI Mendes, Virgilio/K-6598-2012; Prates, Goncalo/K-4018-2014 OI Mendes, Virgilio/0000-0002-7362-8996; Prates, Goncalo/0000-0001-5797-9158 NR 12 TC 33 Z9 37 U1 0 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 2002 VL 29 IS 10 AR 1414 DI 10.1029/2001GL014394 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300092 ER PT J AU Morrill, J Bucsela, E Siefring, C Heavner, M Berg, S Moudry, D Slinker, S Fernsler, R Wescott, E Sentman, D Osborne, D AF Morrill, J Bucsela, E Siefring, C Heavner, M Berg, S Moudry, D Slinker, S Fernsler, R Wescott, E Sentman, D Osborne, D TI Electron energy and electric field estimates in sprites derived from ionized and neutral N-2 emissions SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STATE VIBRATIONAL POPULATIONS; PHOTOMETRIC MEASUREMENTS; IONIZATION; ELVES AB [1] During the EXL98 aircraft mission, sprites and blue jets were observed by narrow band cameras that measure the N-2(+) 1NG (0,1) band at 4278Angstrom and the N-2 2PG (0, 0) band at 3370Angstrom. We discuss the observations (similar to1 km resolution), instrumental and atmospheric corrections, and altitude profiles of ionized (1NG) and neutral (2PG) emission observed during a specific sprite. The ratio of ionized-to-neutral emission indicates a relative enhancement of ion emission below 55 km. Characteristic electron energies (E-Ch) and electric fields (E) are derived from these emission ratios using excitation rates computed from a model that solves the Boltzmann equation as a function of electric field. Up to 55km E follows the breakdown field (E-k) and E-Ch is similar to2.2eV. Above 55 km E drops below E-k and E-Ch drops to similar to1.75eV near 60km. C1 USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. NASA, Goddard Earth Sci & Technol Ctr, Greenbelt, MD USA. USN, Res Lab, Div Plasma Phys, Washington, DC 20375 USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Computat Phys Inc, Springfield, VA 22151 USA. Univ Alaska Fairbanks, Inst Geophys, Fairbanks, AK 99775 USA. RP Morrill, J (reprint author), USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. NR 16 TC 46 Z9 46 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 2002 VL 29 IS 10 AR 1462 DI 10.1029/2001GL014018 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300044 ER PT J AU Rathbun, JA Spencer, JR Davies, AG Howell, RR Wilson, L AF Rathbun, JA Spencer, JR Davies, AG Howell, RR Wilson, L TI Loki, Io: A periodic volcano SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID THERMAL EMISSION; LAVA FLOWS; EMPLACEMENT; ERUPTION; BASALT AB [1] Loki is the most powerful volcano in the Solar System. It has been observed to be in continuous though variable activity since 1979. Synthesis of more than a decade of groundbased data suggests that Loki eruptions are cyclic, with a 540 day period. Application of a simple lava cooling model to temperatures in Loki Patera, and eruption start and end times, implies that brightenings are due to a resurfacing wave propagating across the patera. The data are most consistent with lava lake overturn, but resurfacing by lava flows cannot be ruled out. A porosity gradient in the lake crust could cause lava lake overturn to occur periodically on the timescale observed. C1 Univ Redlands, Dept Phys, Redlands, CA 92373 USA. Lowell Observ, Flagstaff, AZ 86001 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Wyoming, Dept Phys & Astron, Laramie, WY 82071 USA. Univ Lancaster, Dept Environm Sci, Lancaster LA1 4YQ, England. RP Rathbun, JA (reprint author), Univ Redlands, Dept Phys, 1200 E Colton Ave, Redlands, CA 92373 USA. EM julie_rathbun@redlands.edu; spencer@lowell.edu NR 27 TC 21 Z9 21 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 2002 VL 29 IS 10 AR 1443 DI 10.1029/2002GL014747 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300064 ER PT J AU Shue, JH Newell, PT Liou, K Meng, CI Kamide, Y Lepping, RP AF Shue, JH Newell, PT Liou, K Meng, CI Kamide, Y Lepping, RP TI Two-component auroras SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SEMIANNUAL VARIATION; GEOMAGNETIC-ACTIVITY; SUBSTORMS; ELECTROJET; EVENTS AB [1] By examining Polar Ultraviolet Imager auroral images at the 160-180 nm N-2 Lyman-Birge-Hopfield emission band, we find that the auroral dynamics associated with substorms shows a two-component feature. An auroral feature, which is called the two-cell aurora, is associated with the increased magnetospheric convection in response to a southward interplanetary magnetic field. A substorm expansion may then occur, adding an additional aurora in the midnight sector. As the substorm continuously increases its strength, the substorm aurora connects with the two-cell aurora, forming a well-defined crescent-shape aurora. It is also found that the occurrence rate of the two-cell aurora depends on universal time. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Nagoya Univ, Solar Terr Environm Lab, Aichi 4428507, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Shue, JH (reprint author), Johns Hopkins Univ, Appl Phys Lab, 11100 Johns Hopkins Rd, Laurel, MD 20723 USA. RI Liou, Kan/C-2089-2016 OI Liou, Kan/0000-0001-5277-7688 NR 16 TC 9 Z9 9 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 2002 VL 29 IS 10 AR 1379 DI 10.1029/2002GL014657 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300127 ER PT J AU Wang, PH Minnis, P Wielicki, BA Wong, TM Vann, LB AF Wang, PH Minnis, P Wielicki, BA Wong, TM Vann, LB TI Satellite observations of long-term changes in tropical cloud and outgoing longwave radiation from 1985 to 1998 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID BUDGET EXPERIMENT; EARTH; CLIMATE; DATASET; ERBE AB [1] Cloud vertical distributions and radiation data from satellites taken between 1985 and 1998 were analyzed to determine the impact of clouds on outgoing longwave radiation (OLR) in the Tropics. Clouds with a 1-mum optical depth greater than 0.025 above 12 km decreased, while those below 12 km increased. The OLR mean and decadal trend were 254 Wm(-2) and 3.9 Wm(-2)/decade, respectively. The mean cloud and OLR results were used to derive a value of 0.36 for the tropical mean cloud longwave effective emissivity. Changes in cloud vertical distributions account for 40% of the OLR trend. A change in cloud effective emissivity of -0.026/decade could account for the remainder of the OLR changes. These changes suggest reduced mean cloud opacity, a drier troposphere, and a strengthened large-scale circulation in the Tropics during the period. C1 Sci & Technol Corp, Hampton, VA 23666 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Wang, PH (reprint author), Sci & Technol Corp, 10 Basil Sawyer Dr, Hampton, VA 23666 USA. RI Minnis, Patrick/G-1902-2010 OI Minnis, Patrick/0000-0002-4733-6148 NR 23 TC 13 Z9 13 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 2002 VL 29 IS 10 AR 1397 DI 10.1029/2001GL014264 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300109 ER PT J AU Yamauchi, Y Suess, ST Sakurai, T AF Yamauchi, Y Suess, ST Sakurai, T TI Relation between Pressure Balance Structures and polar plumes from Ulysses high latitude observations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR-WIND; MAGNETIC-FIELD; CORONAL PLUMES; DISCONTINUITIES; NETWORK; STREAMS AB [1] Ulysses observations have shown that pressure balance structures (PBSs) are a common feature in high-latitude, fast solar wind near solar minimum. Previous studies of Ulysses/SWOOPS plasma data suggest these PBSs may be remnants of coronal polar plumes. Here we find support for this suggestion in an analysis of PBS magnetic structure. We used Ulysses magnetometer data and applied a minimum variance analysis to magnetic discontinuities in PBSs. We found that PBSs preferentially contain tangential discontinuities, as opposed to rotational discontinuities and to non-PBS regions in the solar wind. This suggests that PBSs contain structures like current sheets or plasmoids that may be associated with network activity at the base of plumes. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Natl Astron Observ Japan, Tokyo 1818588, Japan. RP NASA, George C Marshall Space Flight Ctr, SD 50, Huntsville, AL 35812 USA. EM Yohei.Yamauchi@msfc.nasa.gov; Steve.Suess@nsstc.nasa.gov; sakurai@corona.mtk.nao.ac.jp NR 20 TC 15 Z9 15 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 15 PY 2002 VL 29 IS 10 AR 1383 DI 10.1029/2001GL013820 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DL UT WOS:000178888300123 ER PT J AU Beegle, LW Kanik, I Matz, L Hill, HH AF Beegle, LW Kanik, I Matz, L Hill, HH TI Effects of drift-gas polarizability on glycine peptides in ion mobility spectrometry SO INTERNATIONAL JOURNAL OF MASS SPECTROMETRY LA English DT Article DE ion mobility; drift tubes; polarization ID MASS-SPECTROMETRY; PHASE; CHROMATOGRAPHY; CONFORMATIONS AB This investigation is a continuation of our previous work on the feasibility of utilizing ultra-high resolution electrospray ionization/ion mobility spectrometry (ESI/IMS) for in situ analysis of biomolecular compounds. The compounds we studied, in this investigation, were glycine, the smallest amino acid and four of its oligomers, namely triglycine, tetraglycine, pentaglycine, and hexaglycine. Experimental effects of drift-gas polarizability on target ions in IMS were explored by utilizing four different drift-gases with differing polarizability values (He, Ar, N-2, and CO2). The gas-phase ion radii for all five compounds were calculated from the reduced ion mobilities, K-0(m), and the effective drift-gas radii employing a simple hard-sphere model. When ion radii were plotted against the polarizabilities of the drift-gases, linear plots with different slopes were produced. This empirical observation indicated that the polarizing of drift-gas can change the calculated ion radii in a linear fashion over a limited range of polarizability values and does not affect all ions equally. This effect can be exploited in order to alter the separation factors between different ions since all ions that yield different slopes can, theoretically, be separated with IMS using different drift-gases. We demonstrated that the separation factor (alpha) is highly dependent on the drift-gas. The maximum separability and, hence, unique identification of target ions was achieved when He and CO2 were used. (C) 2002 Published by Elsevier Science B.V. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91009 USA. Washington State Univ, Dept Chem, Pullman, WA 99164 USA. RP Kanik, I (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91009 USA. RI Beegle, Luther/A-6354-2010 NR 27 TC 41 Z9 41 U1 0 U2 11 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 1387-3806 J9 INT J MASS SPECTROM JI Int. J. Mass Spectrom. PD MAY 15 PY 2002 VL 216 IS 3 BP 257 EP 268 AR PII S1387-3806(02)00626-7 DI 10.1016/S1387-3806(02)00626-7 PG 12 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 565ZB UT WOS:000176399500004 ER PT J AU Okojie, RS Lukco, D Chen, YLL Spry, DJ AF Okojie, RS Lukco, D Chen, YLL Spry, DJ TI Reliability assessment of Ti/TaSi2/Pt ohmic contacts on SiC after 1000 h at 600 degrees C SO JOURNAL OF APPLIED PHYSICS LA English DT Article AB We report the result of the development and analysis of Ti/TaSi2/Pt high temperature ohmic contact metallizations on n-type 4H- and 6H-SiC that can successfully withstand 1000 h of 600 degreesC thermal treatment in air. Understanding the reaction kinetics and dominant failure mechanisms enabled metal thicknesses in the multilayer stack to be optimized, thereby providing stable specific contact resistivity in the range of 1-6x10(-5) Omega cm(2) on the n-type 4H-SiC and 6H-SiC epilayers throughout the duration of heat treatment in air. The deleterious effects of platinum in a platinum-rich silicide and the benefits in a platinum Si-rich silicide were identified within the multilayer system. A high temperature ohmic contact figure of merit is proposed as a reliability benchmark and calculated for the contacts to 4H- and 6H-SiC. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. QSS, Cleveland, OH 44135 USA. OAI, Cleveland, OH 44142 USA. RP Okojie, RS (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd,M-S 77-1, Cleveland, OH 44135 USA. NR 15 TC 34 Z9 34 U1 0 U2 6 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD MAY 15 PY 2002 VL 91 IS 10 BP 6553 EP 6559 DI 10.1063/1.14702551 PN 1 PG 7 WC Physics, Applied SC Physics GA 551QL UT WOS:000175572500046 ER PT J AU Good, N Dooley, J Fultz, B AF Good, N Dooley, J Fultz, B TI Magnetomechanical damping by polycrystalline TbDy SO JOURNAL OF APPLIED PHYSICS LA English DT Article; Proceedings Paper CT 46th Annual Conference on Magnetism and Magnetic Materials CY NOV 12-16, 2001 CL SEATTLE, WASHINGTON ID MAGNETOSTRICTION AB Vibration damping in polycrystalline TbDy alloys was studied at cryogenic temperatures. Mechanical hysteretic losses were measured at various strains, frequencies, and loading configurations at 77 K. Some textured TbDy materials demonstrated 22.6% energy dissipation in mechanical measurements at low frequency (0.01 Hz) and a mean logarithmic decrement of 0.23 at a higher frequency (25 kHz). Ultrasonic velocities of longitudinal and shear elastic waves were measured on single and polycrystalline TbDy; little variation in ultrasonic velocities was found even for samples with large variation in crystallographic texture and magnetomechanical properties. (C) 2002 American Institute of Physics. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. RP Good, N (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 4 Z9 4 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD MAY 15 PY 2002 VL 91 IS 10 BP 7824 EP 7826 DI 10.1063/1.1452217 PN 2 PG 3 WC Physics, Applied SC Physics GA 551RL UT WOS:000175575100331 ER PT J AU Smith, GL Wilber, AC Gupta, SK Stackhouse, PW AF Smith, GL Wilber, AC Gupta, SK Stackhouse, PW TI Surface radiation budget and climate classification SO JOURNAL OF CLIMATE LA English DT Article ID SATELLITE DATA; CLOUD AB The surface radiation budget of a region is strongly tied to its climate. An 8-yr climatology of surface radiation budget components for 2.5degrees regions over the earth is examined in order to learn how the regional climate and surface radiation are related. The yearly cycles of a few individual regions were studied by plotting monthly mean net longwave flux as a function of net shortwave flux at the surface. These plots show trajectories that are characteristic of the climate class. The behavior of the trajectories of surface radiation and their relation to the regional climate can be understood with simple conceptual models for many cases. From an examination of these trajectories, a set of parameters is developed, such as mean net longwave flux and range of net shortwave flux, which distinguish various climate classes on the basis of the surface radiation. These criteria are applied to produce a map of regional climate classes based on surface radiation, similar to those of Koeppen or Trewartha and Horn, which were based on vegetation, temperature, and precipitation. The current maps can be used to explore the relationships between surface radiation and regional climate. C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. Virginia Polytech Inst & State Univ, Blacksburg, VA 24061 USA. Analyt Serv & Mat Inc, Hampton, VA 23666 USA. RP Smith, GL (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, Mail Stop 420, Hampton, VA 23681 USA. NR 15 TC 16 Z9 16 U1 1 U2 8 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 2002 VL 15 IS 10 BP 1175 EP 1188 DI 10.1175/1520-0442(2002)015<1175:SRBACC>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 546AC UT WOS:000175248900005 ER PT J AU Li, XF Sui, CH Lau, KM AF Li, XF Sui, CH Lau, KM TI Interactions between tropical convection and its environment: An energetics analysis of a 2D cloud resolving simulation SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID MOIST AVAILABLE ENERGY; CONDITIONALLY UNSTABLE ATMOSPHERE; DIURNAL-VARIATIONS; TOGA COARE; CONVERGENCE; CIRCULATION; MAINTENANCE; ENSEMBLE; WAVE AB The phase relation between the perturbation kinetic energy (K') associated with the tropical convection and the horizontal-mean moist available potential energy ((P) over bar) associated with environmental conditions is investigated P by an energetics analysis of a numerical experiment. This experiment is performed using a 2D cloud resolving model forced by the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) derived vertical velocity. The imposed upward motion leads to a decrease of through the (P) over bar associated vertical advective cooling, and to an increase of K' through cloud-related processes, feeding the convection. The maximum K' and its maximum growth rate lags and leads, respectively, the maximum imposed large-scale upward motion by about 1-2 h, indicating that convection is phase locked with large-scale forcing. The dominant life cycle of the simulated convection is about 9 h, whereas the timescales of the imposed large-scale forcing are longer than the diurnal cycle. In the convective events, the maximum growth of K' leads the maximum decay of the perturbation moist available potential energy (P') by about 3 h through vertical heat transport by perturbation circulation, and perturbation cloud heating. The maximum decay of P' leads the maximum decay of (P) over bar by about 1 h through the perturbation radiative processes, the horizontal-mean cloud heating, and the large-scale vertical advective cooling. Therefore, maximum gain of K' occurs about 4-5 h before maximum decay of (P) over bar. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Li, XF (reprint author), NOAA, NESDIS, ORA, 5200 Auth Rd,Room 601, Camp Springs, MD 20746 USA. EM xiaofan.li@noaa.gov RI Li, Xiaofan/F-5605-2010; Li, Xiaofan/G-2094-2014; Lau, William /E-1510-2012; OI Lau, William /0000-0002-3587-3691; SUI, CHUNG-HSIUNG/0000-0003-2842-5660 NR 25 TC 41 Z9 45 U1 0 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD MAY 15 PY 2002 VL 59 IS 10 BP 1712 EP 1722 DI 10.1175/1520-0469(2002)059<1712:IBTCAI>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 542YU UT WOS:000175074000006 ER PT J AU Lay, OP Dubovitsky, S AF Lay, OP Dubovitsky, S TI Polarization compensation: a passive approach to a reducing heterodyne interferometer nonlinearity SO OPTICS LETTERS LA English DT Article AB Cyclic errors that are due to optical leakage limit the precision of displacement measurements made with optical interferometers. A method for real-time estimation of leakage components is introduced and is used to implement a novel passive technique for suppression of cyclic nonlinearities that uses only adjustments of existing polarizers and quarter-wave plates. This approach is used to reduce the cyclic error from 3 nm to 300 pm for an interferometer operating at a wavelength of 1320 nm. (C) 2002 Optical Society of America. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lay, OP (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 7 Z9 7 U1 0 U2 2 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 MAY 15 PY 2002 VL 27 IS 10 BP 797 EP 799 DI 10.1364/OL.27.000797 PG 3 WC Optics SC Optics GA 555GJ UT WOS:000175786100001 PM 18007931 ER PT J AU Ning, CZ Li, JZ AF Ning, CZ Li, JZ TI Many-body effects in a laterally inhomogeneous semiconductor quantum well SO PHYSICAL REVIEW B LA English DT Article ID DYNAMICS AB Many-body effects on conduction and diffusion of electrons and holes in a semiconductor quantum well are studied using a microscopic theory. The roles played by the screened Hartree-Fock (SHF) terms and the scattering terms are examined. It is found that the electron and hole conductivities depend only on the scattering terms, while the two-component electron-hole diffusion coefficients depend on both the SHF part and the scattering part. We show that, in the limit of the ambipolar diffusion approximation, however, the diffusion coefficients for carrier density and temperature are independent of electron-hole scattering. In particular, we found that the SHF terms lead to a reduction of density-diffusion coefficients and an increase in temperature-diffusion coefficients. Such a reduction or increase is explained in terms of a density- and temperature-dependent energy landscape created by the band-gap renormalization. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Ning, CZ (reprint author), NASA, Ames Res Ctr, M-S 229-1, Moffett Field, CA 94035 USA. RI Ning, C. Z./D-4699-2009 OI Ning, C. Z./0000-0003-4583-8889 NR 10 TC 1 Z9 1 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 J9 PHYS REV B JI Phys. Rev. B PD MAY 15 PY 2002 VL 65 IS 20 AR 201305 DI 10.1103/PhysRevB.65.201305 PG 4 WC Physics, Condensed Matter SC Physics GA 560DJ UT WOS:000176066600012 ER PT J AU Zhao, JJ Han, J Lu, JP AF Zhao, JJ Han, J Lu, JP TI Work functions of pristine and alkali-metal intercalated carbon nanotubes and bundles SO PHYSICAL REVIEW B LA English DT Article ID FIELD-EMISSION PROPERTIES; GAS CORRELATION-ENERGY; ELECTRONIC-STRUCTURE; PHOTOEMISSION SPECTROSCOPY; DENSITY; EMITTERS; ROPES; TIPS AB The work functions (WF's) of single-walled carbon nanotubes and bundles are studied using first-principles methods. For individual metallic tubes, the WF is independent of the chirality and increase slightly with tube diameter. For semiconducting tubes, the WF (as defined by the HOMO energy) decreases rapidly. The WF of nanotube bundles (similar to5 eV) shows no clear dependence on the tube size and chirality, slightly higher than individual tubes. For both metallic and semiconducting nanotubes, the WF decreases dramatically upon alkali-metal intercalation. The electronic states near the Fermi level are significantly modified and the metallic and semiconducting tube bundles become indistinguishable. C1 Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA. Eloret Corp, NASA, Ames Res Ctr, Santa Clara, CA 95051 USA. RP Zhao, JJ (reprint author), Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA. RI Zhao, Jijun/I-6030-2015 NR 44 TC 172 Z9 177 U1 2 U2 30 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 J9 PHYS REV B JI Phys. Rev. B PD MAY 15 PY 2002 VL 65 IS 19 AR 193401 DI 10.1103/PhysRevB.65.193401 PG 4 WC Physics, Condensed Matter SC Physics GA 556QR UT WOS:000175860900027 ER PT J AU Bandaru, J Beeman, JW Haller, EE AF Bandaru, J Beeman, JW Haller, EE TI Far-infrared absorption in Sb-doped Ge epilayers near the metal-insulator transition SO APPLIED PHYSICS LETTERS LA English DT Article ID PHOTOCONDUCTORS AB Epitaxial germanium layers doped near the metal-insulator transition were grown by liquid phase epitaxy from a Pb melt. Far-infrared absorption was measured between similar to20 cm(-1) and 150 cm(-1). Linear optical absorption coefficients were determined for Ge:Sb in the doping range of 9.0x10(14) cm(-3)200 mum) in blocked impurity band detectors is discussed. (C) 2002 American Institute of Physics. C1 Univ Calif Berkeley, Dept Mat Sci & Engn, Berkeley, CA 94720 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Div Sci Mat, Berkeley, CA 94720 USA. RP Bandaru, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 12 Z9 12 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD MAY 13 PY 2002 VL 80 IS 19 BP 3536 EP 3538 DI 10.1063/1.1479203 PG 3 WC Physics, Applied SC Physics GA 549UA UT WOS:000175464100024 ER PT J AU Milman, M Basinger, S AF Milman, M Basinger, S TI Error sources and algorithms for white-light fringe estimation at low light levels SO APPLIED OPTICS LA English DT Article ID PHASE-SHIFTING INTERFEROMETRY; VIBRATION AB We address the problem of highly accurate phase estimation at low light levels, as required by the Space Interferometry Mission (SIM). The most stringent SIM requirement in this regard is that the average phase error over a 30-s integration time correspond to a path-length error of approximately 30 pm. Most conventional phase-estimation algorithms exhibit significant enough bias at the signal levels at which the SIM will be operating so that some correction is necessary. Several algorithms are analyzed, and methods of compensating for their bias are developed. Another source of error in phase estimation occurs because the phase is not constant over the integration period. Errors that are due to spacecraft motion, the motion of compensating optical elements, and modulation errors are analyzed and simulated. A Kalman smoothing approach for compensating for these errors is introduced. (C) 2002 Optical Society of America. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Milman, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 198-138, Pasadena, CA 91109 USA. EM mark.h.milman@jpl.nasa.gov NR 20 TC 11 Z9 11 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAY 10 PY 2002 VL 41 IS 14 BP 2655 EP 2671 DI 10.1364/AO.41.002655 PG 17 WC Optics SC Optics GA 551NM UT WOS:000175567800007 PM 12022665 ER PT J AU Giblin, TW Connaughton, V van Paradijs, J Preece, RD Briggs, MS Kouveliotou, C Wijers, RAMJ Fishman, GJ AF Giblin, TW Connaughton, V van Paradijs, J Preece, RD Briggs, MS Kouveliotou, C Wijers, RAMJ Fishman, GJ TI Extended power-law decays in BATSE gamma-ray bursts: Signatures of external shocks? SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts ID ULTRA-RELATIVISTIC SHOCKS; HIGH-ENERGY AFTERGLOW; LIGHT CURVES; X-RAY; PARTICLE-ACCELERATION; INTERNAL SHOCKS; FIREBALL MODEL; SPECTRA; GRB-990123; EMISSION AB The connection between gamma-ray bursts (GRBs) and their afterglows is currently not well understood. Afterglow models of synchrotron emission generated by external shocks in the GRB fireball model predict emission detectable in the gamma-ray regime (greater than or similar to25 keV). In this paper, we present a temporal and spectral analysis of a subset of BATSE GRBs with smooth extended emission tails to search for signatures of the early high-energy afterglow, i.e., afterglow emission that initially begins in the gamma-ray phase and subsequently evolves into X-ray, UV, optical, and radio emission as the blast wave is decelerated by the ambient medium. From a sample of 40 GRBs we find that the temporal decays are best described with a power law similar tot(beta) rather than an exponential with a mean index approximate to -2. Spectral analysis shows that similar to20% of these events are consistent with fast-cooling synchrotron emission for an adiabatic blast wave, three of which are consistent with the blast-wave evolution of a jet with F-nu similar to t(-p). This behavior suggests that in some cases, the emission may originate from a narrow jet, possibly consisting of "nuggets" whose angular sizes are less than 1/Gamma, where Gamma is the bulk Lorentz factor. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. Ctr High Energy Astrophys, NL-1098 SJ Amsterdam, Netherlands. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Univ Space Res Assoc, Columbia, MD 21044 USA. SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA. RP Giblin, TW (reprint author), Coll Charleston, Dept Phys & Astron, 58 Coming St, Charleston, SC 29424 USA. OI Wijers, Ralph/0000-0002-3101-1808; Preece, Robert/0000-0003-1626-7335 NR 57 TC 39 Z9 39 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2002 VL 570 IS 2 BP 573 EP 587 DI 10.1086/339622 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550WJ UT WOS:000175527100010 ER PT J AU Maeda, Y Baganoff, FK Feigelson, ED Morris, M Bautz, MW Brandt, WN Burrows, DN Doty, JP Garmire, GP Pravido, SH Ricker, GR Townsley, LK AF Maeda, Y Baganoff, FK Feigelson, ED Morris, M Bautz, MW Brandt, WN Burrows, DN Doty, JP Garmire, GP Pravido, SH Ricker, GR Townsley, LK TI A Chandra study of Sagittarius A East: A supernova remnant regulating the activity of our Galactic center? SO ASTROPHYSICAL JOURNAL LA English DT Article DE Galaxy : center; ISM : individual (Sagittarius A East); supernova remnants; X-rays : ISM ID RAY REFLECTION-NEBULA; A-EAST; SGR-A; CENTER REGION; INTERSTELLAR-MEDIUM; ASCA OBSERVATIONS; MASER EMISSION; LINE EMISSION; W49B; COMPLEX AB We report on the X-ray emission from the shell-like, nonthermal radio source Sgr A East (SNR 000.0+00.0), located in the inner few parsecs of the Galaxy based on observations made with the ACIS detector on board the Chandra X-Ray Observatory. This is the first time Sgr A East has been clearly resolved from other complex structures in the region. The X-ray emitting region is concentrated within the central similar or equal to2 pc of the larger radio shell. The spectrum shows strong Kalpha lines from highly ionized ions of S, Ar, Ca, and Fe. A simple isothermal plasma model gives electron temperature similar to2 keV, absorption column similar to1x10(23) H cm(-2), luminosity similar to8x10(34) ergs s(-1) in the 2-10 keV band, and gas mass similar to2eta(1/2) M-circle dot with a filling factor eta. The plasma appears to be rich in heavy elements, overabundant by roughly a factor of 4 with respect to solar abundances, and shows a spatial gradient of elemental abundance; the spatial distribution of iron is more compact than that of the lighter elements. The gas mass and elemental abundance of the X-ray emission support the long-standing hypothesis that Sgr A East is a supernova remnant (SNR), perhaps produced by the Type II supernova explosion of a massive star with a main-sequence mass of 13-20 M-circle dot. The combination of the radio and X-ray morphologies classifies Sgr A East as a new metal-rich mixed morphology (MM) SNR. The size of the Sgr A East radio shell is the smallest of the known MM SNRs, which strongly suggests that the ejecta have expanded into a very dense interstellar medium. The ejecta-dominated chemical compositions of the plasma indicate that the ambient materials should be highly homogeneous. We thus evaluate a simplified dynamical evolution model where an SNR was formed about 10,000 yr ago and expanded into an ambient medium with a homogeneous density of 10(3) cm(-3). The model roughly reproduces most of the observed properties in the X-ray and radio wavelengths. A comparison with the radio observations requires the dense ambient medium to be ionized, but a luminous X-ray irradiator with an expected X-ray luminosity of similar to10(40) ergs s(-1) is not currently present. The presence of the ionized gas may be explained if the massive black hole (MBH) associated with the compact, nonthermal radio source Sgr A* was bright in X-rays about 300 yr ago but is presently dim. It is possible that the dust/molecular ridge compressed by the forward shock of Sgr A East hit Sgr A* in the past, and the passage of the ridge may have supplied material to accrete onto the black hole in the past and may have removed material from the black hole vicinity, leading to its present quiescent state. This may be a specific example of the intimate relationship between an SNR and MBH accretion activity in galactic nuclei. C1 Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA. MIT, Space Res Ctr, Cambridge, MA 02139 USA. Univ Calif Los Angeles, Div Astron, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Maeda, Y (reprint author), Inst Space & Astronaut Sci, 3-1-1 Yoshinodai, Kanagawa 2298510, Japan. RI Brandt, William/N-2844-2015 OI Brandt, William/0000-0002-0167-2453 NR 73 TC 136 Z9 136 U1 0 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2002 VL 570 IS 2 BP 671 EP 687 DI 10.1086/339773 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550WJ UT WOS:000175527100018 ER PT J AU Lisse, C Schultz, A Fernandez, Y Peschke, S Ressler, M Gorjian, V Djorgovski, SG Christian, DJ Golisch, B Kaminski, C AF Lisse, C Schultz, A Fernandez, Y Peschke, S Ressler, M Gorjian, V Djorgovski, SG Christian, DJ Golisch, B Kaminski, C TI Discovery of an extremely red object in the field of HD 155826 SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : stars; planetary systems : protoplanetary disks; stars : carbon; stars : imaging; stars : individual (HD 155826); stars : pre-main-sequence ID ULTRALUMINOUS INFRARED GALAXIES; NEARBY STARS; CARBON STARS; SPECTROSCOPY; PHOTOMETRY; SPECTRA; CATALOG; MATTER; CIRRUS; TAURI AB We have discovered an extremely red object, LSF 1, located 7" southwest (P. A. 217degrees) of the bright spectroscopic binary system HD 155826. Originally reported by IRAS as one source detected at 12-60 mum, and found as a single 6-25 mum source of similar flux in the Midcourse Space Experiment Galactic plane survey, two bright point sources were found in arcsecond resolution infrared images obtained with the MIRLIN camera at the Infrared Telescope Facility and confirmed by the Long Wavelength Spectrometer camera on Keck I. While HD 155826 itself was easily detected in all the broadband and narrowband filters from 0.9 to 12 mum that we used, the new counterpart, LSF 1, is only visible at 10 mum. In Gunn z, J, H, and K', the upper limit to the new object's magnitude is similar to14. The detection of the new bright IR source explains the confusing [K]-[N] IRAS colors that originally implied that HD 155826 was a possible Vega-like system. The anomalous long-wavelength emission is found to arise entirely from the new source. Without mid-IR extension or excess long-wavelength emission, HD 155826 should no longer be classified as a Vega-like system. We suspect LSF 1 to be either a highly reddened carbon star or a Class II YSO, with no association with the high proper motion HD 155826 system. C1 Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Comp Sci Corp, Sci Operat, Baltimore, MD 21218 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. ESA, VILSPA Tracking Stn, ISO Data Ctr, Villafranca Del Castillo, Spain. NASA, JPL, Pasadena, CA 91104 USA. CALTECH, Palomar Observ, Pasadena, CA 91125 USA. NASA, IRTF, Inst Astron, Hilo, HI 96720 USA. RP Lisse, C (reprint author), Univ Maryland, Dept Astron, College Pk, MD 20742 USA. EM lisse@astro.umd.edu; schultz@stsci.edu; yan@ifa.hawaii.edu; speschke@iso.vilspa.esa.es; ressler@jpl.nasa.gov; vg@coma.jpl.nasa.gov; george@oracle.caltech.edu; dchrist@stsci.edu; golisch@irtf.ifa.hawaii.edu RI Lisse, Carey/B-7772-2016; OI Lisse, Carey/0000-0002-9548-1526; Fernandez, Yanga/0000-0003-1156-9721; Christian, Damian/0000-0003-1746-3020 NR 34 TC 16 Z9 16 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2002 VL 570 IS 2 BP 779 EP 784 DI 10.1086/339722 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550WJ UT WOS:000175527100026 ER PT J AU Krist, JE Stapelfeldt, KR Watson, AM AF Krist, JE Stapelfeldt, KR Watson, AM TI Hubble Space Telescope/WFPC2 images of the GG Tauri circumbinary disk SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : general; circumstellar matter; stars : individual (GG Tauri); stars : pre-main-sequence ID RING; WFPC2; MODELS AB We present the first visible wavelength images of the GG Tau circumbinary ring obtained with the Hubble Space Telescope's (HST) Wide Field and Planetary Camera 2. Scattered light from the ring is detected in both V- and I-band images. The images show that the ring is smooth, except for a small gap that could be a shadow caused by material between the stars and the ring. The spokes seen extending from the stars to the ring in ground-based adaptive optics images are not seen in our data, which suggests that they may be image artifacts. The nearside/farside surface brightness ratio is 6.9 in the I band, consistent with forward scattering by small dust grains. The azimuth of the peak ring surface brightness appears offset by 13degrees from the azimuth closest to us, as seen in previous near-IR HST observations. This may indicate that the ring is warped or somehow shadowed by the circumstellar disks. The color of the ring is redder than the combined light from the stars as observed by HST, confirming previous measurements that indicate that circumstellar disks may introduce extinction of light illuminating the ring. We detect a bright, compact arc of material 0."3 from the secondary star at an azimuth opposite the primary. It appears to be too large to be a circumstellar disk and is not at the expected location for dust trapped at a Lagrange point. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Nacl Autonoma Mexico, Inst Astron, Morelia 58089, Michoacan, Mexico. RP Krist, JE (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. RI Stapelfeldt, Karl/D-2721-2012 NR 28 TC 33 Z9 33 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 2002 VL 570 IS 2 BP 785 EP 792 DI 10.1086/339777 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 550WJ UT WOS:000175527100027 ER PT J AU Lee, TJ Martin, JML AF Lee, TJ Martin, JML TI An accurate quartic force field, fundamental frequencies, and binding energy for the high energy density material TdN4 SO CHEMICAL PHYSICS LETTERS LA English DT Article ID CORRELATED MOLECULAR CALCULATIONS; GAUSSIAN-BASIS SETS; VIBRATIONAL FREQUENCIES; TETRAHEDRAL N-4; W2 THEORIES; THERMOCHEMISTRY; W1; TETRAAZATETRAHEDRANE; TETRAZETE; GEOMETRY AB The CCSD(T) method has been used to compute a highly accurate quartic force field and fundamental frequencies for all N-14 and N-15 isotopomers of the high energy density material TdN4. The computed fundamental frequencies show beyond doubt that the bands observed in a matrix isolation experiment by Radziszewski and coworkers [Chem. Phys. Lett. 328 (2000) 227] are not due to different isotopomers of TdN4. The most sophisticated thermochemical calculations to date yield a 2N(2) --> N-4 heat of reaction of 182.22 +/- 0.5 kcal/mol at 0 K (180.64 +/- 0.5 at 298 K). It is hoped that the data reported herein will aid in the ultimate detection of TdN4. (C) 2002 Published by Elsevier Science B.V. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Weizmann Inst Sci, Dept Organ Chem, IL-76100 Rehovot, Israel. RP Lee, TJ (reprint author), NASA, Ames Res Ctr, MST27B-1, Moffett Field, CA 94035 USA. RI Lee, Timothy/K-2838-2012; Martin, Jan/A-7457-2008 OI Martin, Jan/0000-0002-0005-5074 NR 33 TC 17 Z9 17 U1 0 U2 1 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 10 PY 2002 VL 357 IS 3-4 BP 319 EP 325 AR PII S0009-2614(02)00550-X DI 10.1016/S0009-2614(02)00550-X PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 558GV UT WOS:000175958700026 ER PT J AU Nayagam, V Williams, FA AF Nayagam, V Williams, FA TI Lewis-number effects on edge-flame propagation SO JOURNAL OF FLUID MECHANICS LA English DT Article ID MIXING LAYERS; COUNTERFLOW; STABILITY; DYNAMICS AB Activation-energy asymptotics is employed to explore effects of the Lewis number, the ratio of thermal to fuel diffusivity, in a one-dimensional model of steady motion of edges of reaction sheets. The propagation velocity of the edge is obtained as a function of the relevant Damkohler number, the ratio of the diffusion time to the chemical time. The results show how Lewis numbers different from unity can increase or decrease propagation velocities. Increasing the Lewis number increases the propagation velocity at large Damkohler numbers and decreases it at small Damkohler numbers. Advancing-edge and retreating-edge solutions are shown to exist simultaneously, at the same Damkohler number, if the Lewis number is sufficiently large. This multiplicity of solutions has a bearing on potential edge-flame configurations in non-uniform flows. C1 NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. Univ Calif San Diego, Energy Res Ctr, Dept Aerosp & Mech Engn, La Jolla, CA 92093 USA. RP Nayagam, V (reprint author), NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. NR 14 TC 20 Z9 20 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH ST, NEW YORK, NY 10011-4221 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD MAY 10 PY 2002 VL 458 BP 219 EP 228 DI 10.1017/S0022112002008017 PG 10 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 555GR UT WOS:000175786800009 ER PT J AU Anderson, JD Lau, EL Turyshev, SG Laing, PA Nieto, MM AF Anderson, JD Lau, EL Turyshev, SG Laing, PA Nieto, MM TI Search for a standard explanation of the pioneer anomaly SO MODERN PHYSICS LETTERS A LA English DT Article DE Pioneer 10 and 11; gravitational and systematic forces; spacecraft ID LONG-RANGE ACCELERATION; ULYSSES DATA; PROSAIC EXPLANATION; DISTANT SPACECRAFT; GALILEO; WEAK AB The data from Pioneer 10 and 11 shows an anomalous, constant, Doppler frequency drift that can be interpreted as an acceleration directed towards the Sun of a(P) = (8.74 +/- 1.33) X 10(-8) cm/s(2). Although one can consider a new physical origin for the anomaly, one must first investigate the contributions of the prime candidates, which are systematics generated on board. Here we expand upon previous analyses of thermal systematics. We demonstrate that thermal models put forth so far are not supported by the analyzed data. Possible ways to further investigate the nature of the anomaly axe proposed. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Aerosp Corp, El Segundo, CA 90245 USA. Los Alamos Natl Lab, Theoret Div MSB285, Los Alamos, NM 87545 USA. RP Anderson, JD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 19 TC 47 Z9 47 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 0217-7323 J9 MOD PHYS LETT A JI Mod. Phys. Lett. A PD MAY 10 PY 2002 VL 17 IS 14 BP 875 EP 885 DI 10.1142/S0217732302007107 PG 11 WC Physics, Nuclear; Physics, Particles & Fields; Physics, Mathematical SC Physics GA 566UZ UT WOS:000176447800005 ER PT J AU Soderblom, LA Becker, TL Bennett, G Boice, DC Britt, DT Brown, RH Buratti, BJ Isbell, C Giese, B Hare, T Hicks, MD Howington-Kraus, E Kirk, RL Lee, M Nelson, RM Oberst, J Owen, TC Rayman, MD Sandel, BR Stern, SA Thomas, N Yelle, RV AF Soderblom, LA Becker, TL Bennett, G Boice, DC Britt, DT Brown, RH Buratti, BJ Isbell, C Giese, B Hare, T Hicks, MD Howington-Kraus, E Kirk, RL Lee, M Nelson, RM Oberst, J Owen, TC Rayman, MD Sandel, BR Stern, SA Thomas, N Yelle, RV TI Observations of comet 19P/Borrelly by the Miniature Integrated Camera and Spectrometer Aboard Deep Space 1 SO SCIENCE LA English DT Article ID NUCLEUS; PHOTOMETRY; 253-MATHILDE; HALLEY; IMAGES AB The nucleus of the Jupiter-family comet 19P/Borrelly was closely observed by the Miniature Integrated Camera and Spectrometer aboard the Deep Space I spacecraft on 22 September 2001. The 8-kilometer-long body is highly variegated on a scale of 200 meters, exhibiting large albedo variations (0.01 to 0.03) and complex geologic relationships. Short-wavelength infrared spectra (1.3 to 2.6 micrometers) show a slope toward the red and a hot, dry surface (less than or equal to345 kelvin, with no trace of water ice or hydrated minerals), consistent with similar to10% or less of the surface actively sublimating. Borrelly's coma exhibits two types of dust features: fans and highly collimated jets. At encounter, the near-nucleus coma was dominated by a prominent dust jet that resolved into at least three smaller jets emanating from a broad basin in the middle of the nucleus. Because the major dust jet remained fixed in orientation, it is evidently aligned near the rotation axis of the nucleus. C1 US Geol Survey, Flagstaff, AZ 86001 USA. SW Res Inst, San Antonio, TX 78238 USA. Univ Tennessee, Dept Geol Sci, Knoxville, TN 37996 USA. Univ Arizona, Lunar & Planetary Lab, Dept Planetary Sci, Tucson, AZ 85721 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. DLR, Inst Space Sensor Technol & Planetary Explorat, D-12489 Berlin, Germany. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. SW Res Inst, Dept Space Studies, Boulder, CO 80302 USA. Max Planck Inst Aeron, D-37191 Katlenburg Lindau, Germany. RP Soderblom, LA (reprint author), US Geol Survey, 2255 N Gemini Dr, Flagstaff, AZ 86001 USA. OI Hare, Trent/0000-0001-8842-389X NR 26 TC 134 Z9 134 U1 1 U2 13 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 10 PY 2002 VL 296 IS 5570 BP 1087 EP 1091 DI 10.1126/science.1069527 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 551MG UT WOS:000175565000044 PM 11934989 ER PT J AU Keller, LP Hony, S Bradley, JP Molster, FJ Waters, LBFM Bouwman, J de Koter, A Brownlee, DE Flynn, GJ Henning, T Mutschke, H AF Keller, LP Hony, S Bradley, JP Molster, FJ Waters, LBFM Bouwman, J de Koter, A Brownlee, DE Flynn, GJ Henning, T Mutschke, H TI Identification of iron sulphide grains in protoplanetary disks SO NATURE LA English DT Article ID INTERPLANETARY DUST; CIRCUMSTELLAR DUST; INTERSTELLAR ABUNDANCES; OPTICAL-PROPERTIES; ISO SPECTROSCOPY; AB-AUR; HD-163296; SPECTRUM; SYSTEMS; STARS AB Sulphur is depleted in cold dense molecular clouds with embedded young stellar objects(1), indicating that most of it probably resides in solid grains. Iron sulphide grains are the main sulphur species in cometary dust particles(2,3), but there has been no direct evidence for FeS in astronomical sources(4), which poses a considerable problem, because sulphur is a cosmically abundant element. Here we report laboratory infrared spectra of FeS grains from primitive meteorites, as well as from pyrrhotite ([Fe,Ni](1-x)S) grains in interplanetary dust, which show a broad FeS feature centred at similar to23.5 micrometres. A similar broad feature is seen in the infrared spectra of young stellar objects, implying that FeS grains are an important but previously unrecognized component of circumstellar dust. The feature had previously been attributed to FeO5-7. The observed astronomical line strengths are generally consistent with the depletion of sulphur from the gas phase(1), and with the average Galactic sulphur/silicon abundance ratio(8). We conclude that the missing sulphur has been found. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA. ESA, ESTEC, RSSD ST, NL-2201 AZ Noordwijk, Netherlands. Univ Washington, Dept Astron, Seattle, WA 98195 USA. SUNY Coll Plattsburgh, Dept Phys, Plattsburgh, NY 12901 USA. Astrophys Inst & Univ Observ, Jena, Germany. Katholieke Univ Leuven, Inst Sterrenkunde, B-3001 Heverlee, Belgium. CENS, CEA, DSM, DAPNIA,Serv Astrophys, F-91191 Gif Sur Yvette, France. RP Keller, LP (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code SR, Houston, TX 77058 USA. NR 25 TC 76 Z9 76 U1 1 U2 10 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD MAY 9 PY 2002 VL 417 IS 6885 BP 148 EP 150 DI 10.1038/417148a PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 549RH UT WOS:000175460200035 PM 12000914 ER PT J AU Jordan, PM Puri, P AF Jordan, PM Puri, P TI Exact solutions for the unsteady plane Couette flow of a dipolar fluid SO PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Article DE back flow; dipolar fluid; instant steady state; jump discontinuity; Laplace transform; Rivlin-Ericksen fluid ID NONCLASSICAL HEAT-CONDUCTION; NON-NEWTONIAN SYSTEM; UNBOUNDED CHANNEL; VISCOUS FLUIDS; 2ND GRADE; REGULARIZATION; UNIQUENESS; MECHANICS; EXISTENCE; STABILITY AB The Laplace transform is used to determine two forms of the exact solution for the unsteady, isothermal, one-dimensional plane Couette flow of an incompressible dipolar fluid set in motion by the sudden acceleration from rest of the top plate. The solutions are found for arbitrary values of the dipolar constants d (greater than or equal to 0) and I (> 0). In considering special/limiting cases of the dipolar constants, exact solutions are also determined for Rivlin-Ericksen fluids, fluids with couple stresses, and viscous Newtonian fluids. Specifically, steady-state development time, mass flux and the skin-friction coefficient are determined for all fluid types. The results obtained are then compared with those of dipolar fluids. The influence of the dipolar constants and the other physical parameters on the velocity field is also examined, as well as the effects of start-stop plate motion. Most significantly, it is shown that when d > 0 the velocity field suffers a jump discontinuity on start-up, a transient back-flow condition is possible when I > d, and for special values of the physical parameters the flow instantly attains a steady state. Lastly, numerical results are presented graphically, conclusions are stated and closing remarks follow. C1 USN, Res Lab, Stennis Space Ctr, Stennis Space Ctr, MS 39529 USA. Univ New Orleans, Dept Math, New Orleans, LA 70148 USA. RP Jordan, PM (reprint author), USN, Res Lab, Stennis Space Ctr, Code 7181, Stennis Space Ctr, MS 39529 USA. EM pjordan@nrlssc.navy.mil NR 46 TC 20 Z9 20 U1 2 U2 4 PU ROYAL SOC PI LONDON PA 6-9 CARLTON HOUSE TERRACE, LONDON SW1Y 5AG, ENGLAND SN 1364-5021 EI 1471-2946 J9 P ROY SOC A-MATH PHY JI Proc. R. Soc. A-Math. Phys. Eng. Sci. PD MAY 8 PY 2002 VL 458 IS 2021 BP 1245 EP 1272 PG 28 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 548NV UT WOS:000175395300013 ER PT J AU Geser, A AF Geser, A TI Decidability of termination of grid string rewriting rules SO SIAM JOURNAL ON COMPUTING LA English DT Article DE semi-Thue system; string rewriting system; one-rule; termination; grid rule; total division order ID SEMI-THUE SYSTEMS AB Termination of string rewriting is known undecidable. Termination of string rewriting with only one rule is neither known decidable nor known undecidable. This paper presents a decision procedure for rules u --> v such that some letter b from u occurs as often or less often in v. We call such rules grid rules. By far most rules are grid rules. Grid rules cover all rules which terminate by a total division order. Thus total division orders are shown to be irrelevant for the termination problem of one-rule string rewriting. C1 NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. RP Geser, A (reprint author), NASA, Langley Res Ctr, ICASE, Mail Stop 132C, Hampton, VA 23681 USA. EM geser@icase.edu NR 20 TC 5 Z9 5 U1 0 U2 1 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 0097-5397 EI 1095-7111 J9 SIAM J COMPUT JI SIAM J. Comput. PD MAY 8 PY 2002 VL 31 IS 4 BP 1156 EP 1168 AR PII S009753979833297X DI 10.1137/S009753979833297X PG 13 WC Computer Science, Theory & Methods; Mathematics, Applied SC Computer Science; Mathematics GA 557FY UT WOS:000175899100007 ER PT J AU Li, X Wang, J Mason, R Bu, XR Harrison, J AF Li, X Wang, J Mason, R Bu, XR Harrison, J TI Combined phase transfer catalysis and ultrasound to enhance tandem alkylation of azo dyes SO TETRAHEDRON LA English DT Article DE phase transfer; alkylation; azo compounds; polycyclic heterocyclic compounds; amines ID NONLINEAR-OPTICAL-MATERIALS; SIDE-CHAIN; 2ND-ORDER; POLYMERS AB Ultrasound has been found to enhance N-substitution against elimination in the reaction of carbazole-containing bromides 3 with a Disperse Orange 3 derivative 2 under PTC condition. Upon using combined PTC and ultrasound conditions, a series of bifunctional molecules 1 have been prepared to possess charge-transporting agents and nonlinear optical chromophores in 2:1 ratio. (C) 2002 Published by Elsevier Science Ltd. C1 Clark Atlanta Univ, Dept Chem, Atlanta, GA 30314 USA. Clark Atlanta Univ, NASA, Ctr High Performance Polymers & Composites, Atlanta, GA 30314 USA. NASA, Langley Res Ctr, Polymer Branch, Hampton, VA 23681 USA. RP Bu, XR (reprint author), Clark Atlanta Univ, Dept Chem, Atlanta, GA 30314 USA. NR 25 TC 17 Z9 18 U1 0 U2 6 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0040-4020 J9 TETRAHEDRON JI Tetrahedron PD MAY 6 PY 2002 VL 58 IS 19 BP 3747 EP 3753 AR PII S0040-4020(02)00331-9 DI 10.1016/S0040-4020(02)00331-9 PG 7 WC Chemistry, Organic SC Chemistry GA 552GX UT WOS:000175612500013 ER PT J AU Benner, SA Caraco, MD Thomson, JM Gaucher, EA AF Benner, SA Caraco, MD Thomson, JM Gaucher, EA TI Evolution - Planetary biology - Paleontological, geological, and molecular histories of life SO SCIENCE LA English DT Review ID PROTEIN-PROTEIN INTERACTION; HOMOLOGOUS PROTEINS; FUNCTIONAL GENOMICS; DIVERGENCE; PREDICTION; DATABASE; DEHYDROGENASE; DROSOPHILA; INDICATORS; LIKELIHOOD AB The history of life on Earth is chronicled in the geological strata, the fossil record, and the genomes of contemporary organisms. When examined together, these records help identify metabolic and regulatory pathways, annotate protein sequences, and identify animal models to develop new drugs, among other features of scientific and biomedical interest. Together, planetary analysis of genome and proteome databases is providing an enhanced understanding of how life interacts with the biosphere and adapts to global change. C1 Univ Florida, Dept Chem, Gainesville, FL 32611 USA. Univ Florida, Dept Anat & Cell Biol, Gainesville, FL 32611 USA. Univ Florida, Dept Chem, NASA, Astrobiol Inst, Gainesville, FL 32611 USA. Fdn Appl Mol Evolut, Gainesville, FL 32604 USA. ETH Honggerberg, Dept Chem, CH-8093 Zurich, Switzerland. RP Benner, SA (reprint author), Univ Florida, Dept Chem, Gainesville, FL 32611 USA. RI Gaucher, Eric/I-7313-2013 FU NIGMS NIH HHS [GM 54075, R01 GM054075-02, R01 GM054075] NR 58 TC 57 Z9 61 U1 0 U2 16 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD MAY 3 PY 2002 VL 296 IS 5569 BP 864 EP 868 DI 10.1126/science.1069863 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 549KF UT WOS:000175442500031 PM 11988562 ER PT J AU Barnes, CL Snell, EH Kundrot, CE AF Barnes, CL Snell, EH Kundrot, CE TI Thaumatin crystallization aboard the International Space Station using liquid-liquid diffusion in the Enhanced Gaseous Nitrogen Dewar (EGN) SO ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY LA English DT Article ID FREE INTERFACE DIFFUSION; ATOMIC-FORCE MICROSCOPY; PROTEIN CRYSTAL; GROWTH-KINETICS; MACROMOLECULAR CRYSTALLIZATION; SURFACE-MORPHOLOGY; MICROGRAVITY; EARTH AB This paper reports results from the first biological crystal-growth experiment on the International Space Station (ISS). Crystals of thaumatin were grown using liquid-liquid diffusion in Tygon(R) tubing transported in the Enhanced Gaseous Nitrogen Dewar (EGN). Different volume ratios and concentrations of protein and precipitant were used to test different adaptations of the vapor-diffusion crystallization recipe to the liquid-liquid diffusion method. The EGN warmed up from 77 to 273 K in about 4 d, about the same time it took to warm from 273 to 293 K. The temperature within the EGN was 293-297 K for the majority of the experiment. Air gaps that blocked liquid-liquid diffusion formed in the tubes. Nonetheless, crystals were grown. Synchrotron diffraction data collected from the best space-grown crystal extended to 1.28 Angstrom, comparable to previous studies of space-grown thaumatin crystals. The resolution of the best ground-control crystal was only 1.47 Angstrom. It is not clear if the difference in diffraction limit arises from factors other than crystal size. Improvements in temperature control and the elimination of air gaps are needed, but the results show that the EGN on the ISS can be used to produce space-grown crystals that diffract to high resolution. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Kundrot, CE (reprint author), NASA, George C Marshall Space Flight Ctr, Mail Code SD41, Huntsville, AL 35812 USA. NR 27 TC 10 Z9 10 U1 0 U2 5 PU BLACKWELL MUNKSGAARD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0907-4449 J9 ACTA CRYSTALLOGR D JI Acta Crystallogr. Sect. D-Biol. Crystallogr. PD MAY PY 2002 VL 58 BP 751 EP 760 DI 10.1107/S0907444902002767 PN 5 PG 10 WC Biochemical Research Methods; Biochemistry & Molecular Biology; Biophysics; Crystallography SC Biochemistry & Molecular Biology; Biophysics; Crystallography GA 546WZ UT WOS:000175300500004 PM 11976485 ER PT J AU Marzocca, P Librescu, L Silva, WA AF Marzocca, P Librescu, L Silva, WA TI Aeroelastic response and flutter of swept aircraft wings SO AIAA JOURNAL LA English DT Article ID SONIC-BOOM; UNSTEADY AERODYNAMICS; SUBSONIC FLOW; LOADINGS; BLAST; LIFT AB A unified approach of stability and aeroelastic response of swept aircraft wings in an incompressible flow is developed. To this end, the indicial function concept in time and frequency domains is used, and on this basis the flutter instability and subcritical aeroelastic response to arbitrary time-dependent external excitation are analyzed. In addition, an original representation of the aeroelastic response in the phase space is, presented, and the implications of the related results toward determining the flutter instability in flight are emphasized. Validations of selected results against the theoretical and experimental predictions are supplied, and pertinent conclusions are outlined. C1 Virginia Polytech Inst & State Univ, Dept Engn Sci & Mech, Blacksburg, VA 24061 USA. NASA, Langley Res Ctr, Aeroelast Branch, Hampton, VA 23681 USA. RP Marzocca, P (reprint author), Virginia Polytech Inst & State Univ, Dept Engn Sci & Mech, 0219 Norris Hall, Blacksburg, VA 24061 USA. NR 40 TC 11 Z9 12 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 2002 VL 40 IS 5 BP 801 EP 812 DI 10.2514/2.1724 PG 12 WC Engineering, Aerospace SC Engineering GA 611YC UT WOS:000179044700001 ER PT J AU Marzocca, P Librescu, L Silva, WA AF Marzocca, P Librescu, L Silva, WA TI Aeroelastic response of nonlinear wing sections using a functional series technique SO AIAA JOURNAL LA English DT Article ID NON-LINEAR STRUCTURES; VOLTERRA SERIES; HOPF-BIFURCATION; SONIC-BOOM; SYSTEMS; LOADINGS; BLAST AB The determination of the subcritical aeroelastic response and flutter instability of nonlinear two-dimensional wing sections in an incompressible flowfield via indicial functions and Volterra series approach is considered. The aeroelastic governing equations are based on the inclusion of stiffness and damping nonlinearities in plunging and pitching and of the linear unsteady aerodynamics and consideration of an arbitrary time-dependent external pressure pulse. Nonlinear unsteady aeroelastic kernels are obtained, and based on these, time histories of the subcritical aeroelastic response are determined. Conclusions and results displaying the implications of the considered effects are supplied. C1 Virginia Polytech Inst & State Univ, Dept Engn Sci & Mech, Blacksburg, VA 24061 USA. NASA, Langley Res Ctr, Aeroelast Branch, Hampton, VA 23681 USA. RP Marzocca, P (reprint author), Virginia Polytech Inst & State Univ, Dept Engn Sci & Mech, 0219 Norris Hall, Blacksburg, VA 24061 USA. NR 42 TC 30 Z9 32 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 2002 VL 40 IS 5 BP 813 EP 824 DI 10.2514/2.1735 PG 12 WC Engineering, Aerospace SC Engineering GA 611YC UT WOS:000179044700002 ER PT J AU Alexeenko, AA Levin, DA Gimelshein, SF Collins, RJ Reed, BD AF Alexeenko, AA Levin, DA Gimelshein, SF Collins, RJ Reed, BD TI Numerical modeling of axisymmetric and three-dimensional flows in microelectromechanical systems nozzles SO AIAA JOURNAL LA English DT Article ID MONTE-CARLO SIMULATION AB A numerical study of three-dimensional effects on the performance of a micronozzle fabricated from flat silicon wafers is performed by use of both continuum and kinetic approaches: The nozzle operates in a low-Reynolds-number regime, and viscous effects dominate the gas expansion. Thrust losses occur because the shear on the wall is greater in a flat nozzle configuration than in an axisymmetric conical nozzle. Therefore, the prediction of the micronozzle performance based on axisymmetric or two-dimensional modeling can lead to significant design errors. Comparison of simulation with recent data shows good agreement in terms of thrust predictions for cold-gas thrusters at Reynolds numbers of approximately 2 x 10(2). C1 Penn State Univ, Dept Aerosp Engn, University Pk, PA 16802 USA. George Washington Univ, Dept Chem, Washington, DC 20052 USA. Univ Minnesota, Dept Elect Engn, Minneapolis, MN 55455 USA. NASA, John H Glenn Res Ctr, On Board Propuls Branch, Cleveland, OH 44125 USA. RP Alexeenko, AA (reprint author), Penn State Univ, Dept Aerosp Engn, University Pk, PA 16802 USA. RI Alexeenko, Alina/B-7168-2011 NR 20 TC 47 Z9 48 U1 1 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 2002 VL 40 IS 5 BP 897 EP 904 DI 10.2514/2.1726 PG 8 WC Engineering, Aerospace SC Engineering GA 611YC UT WOS:000179044700011 ER PT J AU Okong'o, N Harstad, K Bellan, J AF Okong'o, N Harstad, K Bellan, J TI Direct numerical simulations of O-2/H-2 temporal mixing layers under supercritical conditions SO AIAA JOURNAL LA English DT Article ID NITROGEN; HEPTANE; TURBULENCE; TRANSITION; PRESSURES; SCALES AB Direct numerical simulations of a supercritical oxygen/hydrogen temporal three-dimensional mixing layer are conducted to explore the features of high-pressure transitional mixing behavior. The conservation equations are formulated according to fluctuation-dissipation theory and are coupled to a modified Peng-Robinson equation of state. The boundary conditions are periodic in the streamwise and spanwise directions and of nonreflecting outflow type in the cross-stream direction. Simulations are conducted with initial Reynolds numbers of 6 x 10(2) and 7.5 x 10(2), initial pressure of 100 atm, and temperatures of 400 K in the O-2 and 600 K in the H-2 stream. Each simulation encompasses the rollup and pairing of four initial spanwise vortices into a single vortex. The layer eventually exhibits distorted regions of high density-gradient-magnitude similar to the experimentally observed wisps. of fluid at the boundary of supercritical jets. Analysis of the data reveals that the higher-Reynolds-number layer reaches transition, whereas the other one does not. The transitional layer is analyzed to elucidate its characteristics. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Okong'o, N (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 29 TC 38 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 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 2002 VL 40 IS 5 BP 914 EP 926 DI 10.2514/2.1728 PG 13 WC Engineering, Aerospace SC Engineering GA 611YC UT WOS:000179044700013 ER PT J AU Xirouchakis, D Smirnov, A Woody, K Lindsley, DH Andersen, FJ AF Xirouchakis, D Smirnov, A Woody, K Lindsley, DH Andersen, FJ TI Thermodynamics and stability of pseudobrookite-type MgTi2O5 (karrooite) SO AMERICAN MINERALOGIST LA English DT Article ID NEUTRON POWDER DIFFRACTION; SYSTEM NA2O-K2O-CAO-MGO-FEO-FE2O3-AL2O3-SIO2-TIO2-H2O-CO2; CHEMICAL REACTIONS; CRYSTAL-CHEMISTRY; ARMALCOLITE; EQUILIBRIA; PRESSURE; MINERALS; OLIVINE; MANTLE AB Pseudobrookite-type MgTi2O5 (karrooite) is a synthetic crystalline phase with the Bbmm structure and a component in orthorhombic oxide solid solutions, R2+Ti2O5-R23+TiO5, which are present as accessory minerals in lunar and terrestrial rocks. In this study, we present a model for the molar Gibbs free energy of MgTi2O5 as a function of T, P, and the order parameter s = X-Mg(Ml) - 2X(Mg)(M2), (-1 less than or equal to s less than or equal to 1). We describe the molar Gibbs free energy, ((G) over bar), with the equation: (G) over bar = (g) over bar (0) + (g) over bar (1).(1 - s) + 3/2 (g) over bar (2).(1 - s(2)) - T.(S) over bar (config), and take parameter g(0) to represent the molar Gibbs free energy of ordered MgTi2O5 (s = 1), whereas parameters g(1) and g(2) may represent cation-disorder contributions. We used powder and single-crystal X-ray diffraction, and high-temperature relative enthalpy data, to calibrate the disorder contribution to the volume (b(0)= 7.3822-10 (3) J/bar), and the model parameters g(1) (7370.8 J/mol) and g(2) (3576.1 J/mol), and heat capacity and volume equation coefficicnts. We also optimized standard state thermodynamic data from the elements for ordered MgTi2O5, (DeltaH(0) = -2 498 515.28 J/mol, S-0 = 149.55 J/(mol.K), DeltaG(0) = -2 362 181.72 J/mol, V-0 = 5.445 J/bar) consistent with the model parameters and equations, the thermodynamic data in QUILF, and phase-equilibrium experiments involving MgTi2O5, geikelite, rutile, orthoenstatite, and forsterite in the range 973 to 1673 K and 0.0001 to 2.0 GPa. Finally, we investigate theoretically the stability of MgTi2O5 (karrooite) with respect to geikelite, rutile, diopside, enstatite, and forsterite in the CaO-MgO-TiO2-SiO2 system. We Find that diopside- and titanite-bearing reactions require extremely high temperatures, and are thus not stable with respect to liquid. The inferred phase relations can be of help in understanding the stability of MgTi2O5 with respect to rutile, geikelite, forsterite, and orthoenstatite, and by extrapolation that of armalcolite relative to rutile, ilmenite, olivine, and orthopyroxene in terrestrial mantle rocks and high-Ti lunar basalts. C1 NASA, Lyndon B Johnson Space Ctr, Off Astromat Res & Explorat Sci, Houston, TX 77058 USA. Texas So Univ, Dept Chem, Houston, TX 77004 USA. SUNY Stony Brook, Dept Geosci, Stony Brook, NY 11794 USA. SUNY Stony Brook, Ctr High Pressure Res, Stony Brook, NY 11794 USA. MDProductivity, Austin, TX 78759 USA. RP Xirouchakis, D (reprint author), NASA, Lyndon B Johnson Space Ctr, Off Astromat Res & Explorat Sci, Mail Code SA13, Houston, TX 77058 USA. EM dxirouch@ems.jsc.nasa.gov RI Smirnov, Alexander/D-4672-2009 OI Smirnov, Alexander/0000-0001-8665-5187 NR 48 TC 10 Z9 10 U1 2 U2 8 PU MINERALOGICAL SOC AMER PI CHANTILLY PA 3635 CONCORDE PKWY STE 500, CHANTILLY, VA 20151-1125 USA SN 0003-004X J9 AM MINERAL JI Am. Miner. PD MAY-JUN PY 2002 VL 87 IS 5-6 BP 658 EP 667 PG 10 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA 553DN UT WOS:000175660500008 ER PT J AU Gelman, A Pasarica, C Dodhia, R AF Gelman, A Pasarica, C Dodhia, R TI Let's practice what we preach: Turning tables into graphs SO AMERICAN STATISTICIAN LA English DT Article DE data reduction; graph; table; visual display ID LOGISTIC-REGRESSION; PUBLICATIONS; PERFORMANCE; CANCER; MODELS AB Statisticians recommend graphical displays but often use tables to present their own research results. Could graphs do better? We study the question by going through the tables in a recent issue of the Journal of the American Statistical Association. We show how it is possible to improve the presentations using graphs that actually take up less space than the original tables. We find a particularly effective tool to be multiple repeated line plots, with comparisons of interest connected by lines and separate comparisons isolated on different plots. C1 Columbia Univ, Dept Stat, New York, NY 10027 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Gelman, A (reprint author), Columbia Univ, Dept Stat, New York, NY 10027 USA. NR 47 TC 76 Z9 78 U1 1 U2 21 PU AMER STATISTICAL ASSOC PI ALEXANDRIA PA 1429 DUKE ST, ALEXANDRIA, VA 22314 USA SN 0003-1305 J9 AM STAT JI Am. Stat. PD MAY PY 2002 VL 56 IS 2 BP 121 EP 130 DI 10.1198/000313002317572790 PG 10 WC Statistics & Probability SC Mathematics GA 545MC UT WOS:000175220400008 ER PT J AU Pumera, M Wang, J Opekar, F Jelinek, I Feldman, J Lowe, H Hardt, S AF Pumera, M Wang, J Opekar, F Jelinek, I Feldman, J Lowe, H Hardt, S TI Contactless conductivity detector for microchip capillary electrophoresis SO ANALYTICAL CHEMISTRY LA English DT Article ID CONDUCTOMETRIC DETECTOR; DEVICES; CHIP; ISOTACHOPHORESIS AB A microfabricated electrophoresis chip with an integrated contactless conductivity detection system is described. The new contactless conductivity microchip detector is based on placing two planar sensing aluminum film electrodes on the outer side of a poly(methyl methacrylate) (PMMA) microchip (without contacting the solution) and measuring the impedance of the solution in the separation channel. The contactless route obviates problems (e.g., fouling, unwanted reactions) associated with the electrode-solution contact, offers isolation of the detection system from high separation fields, does not compromise the separation efficiency, and greatly simplifies the detector fabrication. Relevant experimental variables, such as the frequency and amplitude of the applied ac voltage or the separation voltage, were examined and optimized. The detector performance was illustrated by the separation of potassium, sodium, barium, and lithium cations and the chloride, sulfate, fluoride, acetate, and phosphate. anions. The response was linear (over the 20 muM-7 mM range) and reproducible (RSD = 3.4-4.9%; n = 10), with detection limits of 2.8 and 6.4 muM (for potassium and chloride, respectively). The advantages associated with the contactless conductivity detection, along with the low cost of the integrated PMMA chip/detection system, should enhance the power and scope of microfluidic analytical devices. C1 New Mexico State Univ, Dept Chem & Biochem, Las Cruces, NM 88003 USA. Charles Univ, Dept Analyt Chem, Prague 12043 2, Czech Republic. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Inst Mikrotech Mainz GMBH, D-55129 Mainz, Germany. RP Wang, J (reprint author), New Mexico State Univ, Dept Chem & Biochem, Las Cruces, NM 88003 USA. RI Wang, Joseph/C-6175-2011; Pumera, Martin/F-2724-2010 OI Pumera, Martin/0000-0001-5846-2951 NR 17 TC 163 Z9 176 U1 2 U2 40 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0003-2700 J9 ANAL CHEM JI Anal. Chem. PD MAY 1 PY 2002 VL 74 IS 9 BP 1968 EP 1971 DI 10.1021/ac011219e PG 4 WC Chemistry, Analytical SC Chemistry GA 547XU UT WOS:000175358800030 PM 12033293 ER PT J AU Barrow, CH Lecacheux, A MacDowall, RJ AF Barrow, CH Lecacheux, A MacDowall, RJ TI Jovicentric latitude effect on the HOM radio emission observed by Ulysses/URAP at 5 AU from Jupiter SO ANNALES GEOPHYSICAE LA English DT Article DE magnetospheric physics; planetary magnetospheres; radio science; radio astronomy ID JOVIAN HECTOMETRIC RADIATION; VOYAGER; LOCATIONS; PLANETS AB During 1994 and into 1996, Ulysses was at distances of 5 AU or more from Jupiter and travelling from south to north of the ecliptic plane between jovicentric latitudes -36degrees to 20degrees. Observations by the Unified Radio and Plasma Experiment (URAP) on board the Ulysses spacecraft during this period have been searched for jovian hectometric (HOM) radio events. At these distances, the HOM was only received occasionally. The signals were generally weak and much care was needed to find and to identify the events. All of the HOM events were observed when Ulysses was at jovicentric latitudes between -12.2degrees less than or equal to D-Uly less than or equal to 14.70, relatively close to the plane of the jovicentric equator. Both senses of polarization were observed with left-hand (LH) predominant. The events occurred when the jovimagnetic latitude D-phi was between -8.5degrees and 14.2degrees and suggest that the HOM was only detectable within a beam some 23degrees wide, centred on about 3degrees jovimagnetic latitude. This is roughly consistent with previous work by Alexander et al. (1979) and by Ladreiter and Leblanc (1989, 199 1), based upon observations made by Voyager and other spacecraft when these were relatively close to Jupiter. The results are consistent with an emission process due to the Cyclotron-Maser instability, as suggested by a number of scientists in the past. C1 Max Planck Inst Aeron, D-37189 Katlenburg Lindau, Germany. Observ Paris, ARPEGES, F-92195 Meudon, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Barrow, CH (reprint author), Max Planck Inst Aeron, D-37189 Katlenburg Lindau, Germany. RI MacDowall, Robert/D-2773-2012 NR 29 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN GEOPHYSICAL SOC PI KATLENBURG-LINDAU PA MAX-PLANCK-STR 13, 37191 KATLENBURG-LINDAU, GERMANY SN 0992-7689 J9 ANN GEOPHYS-GERMANY JI Ann. Geophys. PD MAY PY 2002 VL 20 IS 5 BP 599 EP 607 PG 9 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA 560TX UT WOS:000176098400002 ER PT J AU Sakano, Y Pickering, KD Strom, PF Kerkhof, LJ AF Sakano, Y Pickering, KD Strom, PF Kerkhof, LJ TI Spatial distribution of total, ammonia-oxidizing, and denitrifying bacteria in biological wastewater treatment reactors for bioregenerative life support SO APPLIED AND ENVIRONMENTAL MICROBIOLOGY LA English DT Article ID 16S RIBOSOMAL-RNA; LENGTH-POLYMORPHISM ANALYSIS; MOLECULAR DIVERSITY; SEQUENCE-ANALYSIS; ACTIVATED-SLUDGE; COMMUNITIES; SEDIMENTS; GENES; DENITRIFICATION; IDENTIFICATION AB Bioregenerative life support systems may be necessary for long-term space missions due to the high cost of lifting supplies and equipment into orbit. In this study, we investigated two biological wastewater treatment reactors designed to recover potable water for a spacefaring crew being tested at Johnson Space Center. The experiment (Lunar-Mars Life Support Test Project-Phase III) consisted of four crew members confined in a test chamber for 91 days. In order to recycle all water during the experiment, an immobilized cell bioreactor (ICB) was employed for organic carbon removal and a trickling filter bioreactor (TFB) was utilized for ammonia removal, followed by physical-chemical treatment. In this study, the spatial distribution of various microorganisms within each bioreactor was analyzed by using biofilm samples taken from four locations in the ICB and three locations in the TFB. Three target genes were used for characterization of bacteria: the 16S rRNA gene for the total bacterial community, the ammonia monooxygenase (amoA) gene for ammonia-oxidizing bacteria, and the nitrous oxide reductase (nosZ) gene for denitrifying bacteria. A combination of terminal restriction fragment length polymorphism (T-RELP), sequence, and phylogenetic analyses indicated that the microbial community composition in the ICB and the TFB consisted mainly of Proteobacteria, low-G+C gram-positive bacteria, and a Cytophaga-Flexibacter-Bacteroides group. Fifty-seven novel 16S rRNA genes, 8 novel amoA genes, and 12 new nosZ genes were identified in this study. Temporal shifts in the species composition of total bacteria in both the ICB and the TFB and ammonia-oxidizing and denitrifying bacteria in the TFB were also detected when the biofilms were compared with the inocula after 91 days. This result suggests that specific microbial populations were either brought in by the crew or enriched in the reactors during the course of operation. C1 Rutgers State Univ, Inst Marine & Coastal Sci, New Brunswick, NJ 08901 USA. Rutgers State Univ, Dept Environm Sci, New Brunswick, NJ 08901 USA. NASA, Johnson Space Ctr, Houston, TX 77058 USA. RP Kerkhof, LJ (reprint author), Rutgers State Univ, Inst Marine & Coastal Sci, Cook Campus,71 Dudley Rd, New Brunswick, NJ 08901 USA. NR 32 TC 38 Z9 41 U1 0 U2 14 PU AMER SOC MICROBIOLOGY PI WASHINGTON PA 1752 N ST NW, WASHINGTON, DC 20036-2904 USA SN 0099-2240 J9 APPL ENVIRON MICROB JI Appl. Environ. Microbiol. PD MAY PY 2002 VL 68 IS 5 BP 2285 EP 2293 DI 10.1128/AEM.68.5.2285-2293.2002 PG 9 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA 548UB UT WOS:000175407300024 PM 11976099 ER PT J AU Brasunas, JC AF Brasunas, JC TI Phase anomalies in Fourier-transform spectrometers: an absorbing beam splitter is neither sufficient nor necessary SO APPLIED OPTICS LA English DT Article ID EMISSION; INTERFEROMETER; SOUNDER; SPECTRA AB Recently it has been a topic of some discussion that the phase associated with part of the self-emission of a Fourier-transform spectrometer may differ neither by 0 nor by pi rad from the phase of an external target if there is absorption in the beam splitter. The conventional interpretation of this has been to separate the self-emission into three terms: instrument emission from the input port, in phase with the external target; emission from the secondary input port, pi rad from the target; and emission from an absorbing beam splitter with an anomalous phase (neither 0 nor pi rad with respect to the target). There is another necessary condition that has not received much attention, that the instrument not be isothermal. For polarized radiation there is an additional condition that suppresses the anomalous phase, and for unpolarized radiation there is a way to produce an anomalous phase without beam-splitter absorption. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Brasunas, JC (reprint author), NASA, Goddard Space Flight Ctr, Code 693,Bldg 2,Room S112, Greenbelt, MD 20771 USA. EM john.c.brasunas.1@gsfe.nasa.gov RI brasunas, john/I-2798-2013 NR 13 TC 6 Z9 6 U1 1 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAY 1 PY 2002 VL 41 IS 13 BP 2481 EP 2487 DI 10.1364/AO.41.002481 PG 7 WC Optics SC Optics GA 547TF UT WOS:000175347500015 PM 12009159 ER PT J AU Bradford, CM Stacey, GJ Swain, MR Nikola, T Bolatto, AD Jackson, JM Savage, ML Davidson, JA Ade, PAR AF Bradford, CM Stacey, GJ Swain, MR Nikola, T Bolatto, AD Jackson, JM Savage, ML Davidson, JA Ade, PAR TI SPIFI: a direct-detection imaging spectrometer for submillimeter wavelengths SO APPLIED OPTICS LA English DT Article ID ATOMIC CARBON; ATMOSPHERIC TRANSMISSION; THERMAL DETECTORS; NOISE; CAMERA; CALORIMETERS; ASTRONOMY; ARRAY AB The South Pole Imaging Fabry-Perot Interferometer (SPIFI) is the first instrument of its kind-a direct-detection imaging spectrometer for astronomy in the submillimeter band. SPIFI's focal plane is a square array of 25 silicon bolometers cooled to 60 mK;, the spectrometer consists of two cryogenic scanning Fabry-Perot interferometers in series with a 60-mK bandpass filter. The instrument operates in the short submillimeter windows (350 and 450 mum) available from the ground, with spectral resolving power selectable between 500 and 10,000. At present, SPIFI's sensitivity is within a factor of 1.5-3 of the photon background limit, comparable with the best heterodyne spectrometers. The instrument's large bandwidth and mapping capability provide substantial advantages for specific astrophysical projects, including deep extragalactic observations, We present the motivation for and design of SPIFI and its operational characteristics on the telescope, (C) 2002 Optical Society of America. C1 Boston Univ, Inst Astrophys Res, Boston, MA 02215 USA. NASA, Ames Res Ctr, Univ Space Res Assoc, Stratospher Observ Infrared Astron, Moffett Field, CA 94035 USA. Cardiff Univ, Dept Phys & Astron, Cardiff CF24 3YB, S Glam, Wales. Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. RP Bradford, CM (reprint author), CALTECH, Dept Phys, Pasadena, CA 91125 USA. EM bradford@submm.caltech.edu NR 40 TC 27 Z9 27 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAY 1 PY 2002 VL 41 IS 13 BP 2561 EP 2574 DI 10.1364/AO.41.002561 PG 14 WC Optics SC Optics GA 547TF UT WOS:000175347500025 PM 12009168 ER PT J AU Stern, D Tozzi, P Stanford, SA Rosati, P Holden, B Eisenhardt, P Elston, R Wu, KL Connolly, A Spinrad, H Dawson, S Dey, A Chaffee, FH AF Stern, D Tozzi, P Stanford, SA Rosati, P Holden, B Eisenhardt, P Elston, R Wu, KL Connolly, A Spinrad, H Dawson, S Dey, A Chaffee, FH TI Spices II: Optical and near-infrared identifications of faint X-ray sources from deep Chandra observations of Lynx SO ASTRONOMICAL JOURNAL LA English DT Article DE cosmology : observations; diffuse radiation; galaxies : active; surveys; X-rays ID EARLY-TYPE GALAXIES; REDSHIFT RADIO GALAXIES; HUBBLE-SPACE-TELESCOPE; LARGE SKY SURVEY; N-LOG S; SPECTRAL PROPERTIES; BACKGROUND SPECTRUM; ALPHA EMISSION; STANDARD STARS; LOCKMAN FIELD AB We present our first results on field X-ray sources detected in a deep, 184.7 ks observation with the Advanced CCD Imaging Spectrometer (ACIS-I) on the Chandra X-Ray Observatory. The observations target the Lynx field (alpha = 08(h)48(m), delta = + 44degrees 54') of SPICES, the Spectroscopic Photometric Infrared-Chosen Extragalactic Survey, which contains three known X-ray emitting clusters at redshifts of z = 0.57, 1.26, and 1.27. Not including the known clusters, in the 17' x 17' ACIS-I field we detect 132 sources in the 0.5-2 keV ( soft) X-ray band down to a limiting flux of approximate to1.7 x 10(-16) ergs cm(-2) s(-1) and 111 sources in the 2-10 keV (hard) X-ray band down to a limiting flux of approximate to1.3 x 10(-15) ergs cm(-2) s(-1). The combined catalog contains a total of 153 sources, of which 42 are detected only in the soft band and 21 are detected only in the hard band. Confirming previous Chandra results, we find that the fainter sources have harder X-ray spectra, providing a consistent solution to the long-standing spectral paradox. From deep optical and near-infrared follow-up data, 77% of the X-ray sources have optical counterparts to I = 24, and 71% of the X-ray sources have near-infrared counterparts to K-s = 20. Four of the 24 sources in the near-IR field are associated with extremely red objects (EROs; I-K-s greater than or equal to 4). We have obtained spectroscopic redshifts with the Keck telescopes of 18 of the Lynx Chandra sources. These sources comprise a mix of broad-lined active galaxies, apparently normal galaxies, and two late-type Galactic dwarfs. Intriguingly, one Galactic source is identified with an M7 dwarf exhibiting nontransient, hard X-ray emission. Thirteen of the Chandra sources are located within regions for which we have Hubble Space Telescope imaging. Nine of the sources are detected, showing a range of morphologies: several show compact cores embedded within diffuse emission, while others are spatially extended showing typical galaxy morphologies. Two of the Chandra sources in this subsample appear to be associated with mergers. We briefly review non active galactic nucleus mechanisms to produce X-ray emission and discuss properties of the Lynx Chandra sample in relation to other samples of X-ray and non X-ray sources. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Osserv Astron Trieste, I-34131 Trieste, Italy. Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94550 USA. Univ Calif Davis, Dept Phys, Davis, CA 95616 USA. European So Observ, D-85748 Garching, Germany. Univ Florida, Dept Astron, Gainesville, FL 32611 USA. Univ Pittsburgh, Dept Phys & Astron, Pittsburgh, PA 15260 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Natl Opt Astron Observ, Tucson, AZ 85719 USA. WM Keck Observ, Kamuela, HI 96743 USA. RP Stern, D (reprint author), CALTECH, Jet Prop Lab, Mail Stop 169-327, Pasadena, CA 91109 USA. NR 79 TC 50 Z9 50 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 2002 VL 123 IS 5 BP 2223 EP 2245 DI 10.1086/339967 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 547AZ UT WOS:000175311200006 ER PT J AU Chen, CHR Chu, YH Gruendl, R Lai, SP Wang, QD AF Chen, CHR Chu, YH Gruendl, R Lai, SP Wang, QD TI A critical examination of hypernova remnant candidates in M101. II. NGC 5471B SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : individual (M101); HII regions; ISM : bubbles; ISM : kinematics and dynamics; supernova remnants; X-rays : ISM ID VIOLENT INTERSTELLAR-MEDIUM; GAMMA-RAY BURST; SUPERNOVA-REMNANTS; 30-DORADUS; EMISSION; REGIONS; ASSOCIATIONS; EVOLUTION; IMAGE AB NGC 5471B has been suggested to contain a hypernova because of its extraordinarily bright X-ray emission. To assess its true nature, we have obtained high-resolution images in continuum bands and nebular lines with the Hubble Space Telescope, and high-dispersion long-slit spectra with the Kitt Peak National Observatory 4 m echelle spectrograph. The images reveal three supernova remnant (SNR) candidates in the giant H II region NGC 5471, the brightest one being the 77 60 pc shell in NGC 5471B. The H velocity pro le of NGC 5471B can be decomposed into a narrow component (FWHM 41 km s(-1)) from the background H II region and a broad component (FWHM 148 km s(-1)) from the SNR shell. Using the brightness ratio of the broad to narrow components and the Halpha flux measured from the WFPC2 Halpha image, we derive a Halpha luminosity of (1.4 +/- 0.1) x 10(39) ergs s(-1) for the SNR shell. The [S II] lambda6716/ 6731 doublet ratio of the broad velocity component is used to derive an electron density of 700 cm 3 in the SNR shell. The mass of the SNR shell is thus 4600 +/- 500 M-.. With a similar to 330 km s(-1) expansion velocity implied by the extreme velocity extent of the broad component, the kinetic energy of the SNR shell is determined to be 5 10 51 ergs. This requires an explosion energy greater than 10 52 ergs, which can be provided by one hypernova or multiple supernovae. Comparing to SNRs in nearby active star formation regions, the SNR shell in NGC 5471B appears truly unique and energetic. We conclude that the optical observations support the existence of a hypernova remnant in NGC 5471B. C1 Univ Illinois, Dept Astron, Urbana, IL 61801 USA. Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. RP Chen, CHR (reprint author), CALTECH, Jet Prop Lab, MS 169-506,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 38 TC 21 Z9 21 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 2002 VL 123 IS 5 BP 2462 EP 2472 DI 10.1086/339964 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 547AZ UT WOS:000175311200021 ER PT J AU Cambresy, L Beichman, CA Jarrett, TH Cutri, RM AF Cambresy, L Beichman, CA Jarrett, TH Cutri, RM TI Extinction with 2MASS: Star counts and reddening toward the North America and Pelican Nebulae SO ASTRONOMICAL JOURNAL LA English DT Article DE dust, extinction; infrared : radiation; ISM : clouds; ISM : individual (North America Nebula, Pelican Nebula); stars : formation ID SOUTHERN DARK CLOUDS; MOLECULAR CLOUDS; IC 5146; INTERSTELLAR EXTINCTION; LUMINOSITY FUNCTION; VISUAL EXTINCTION; INTRINSIC COLORS; DUST EXTINCTION; MILKY-WAY; NGC-7000 AB We propose a general method for mapping the extinction in dense molecular clouds using Two Micron All Sky Survey near-infrared data. The technique is based on the simultaneous utilization of star counts and colors. These two techniques provide independent estimations of the extinction, and each method reacts differently to foreground star contamination and to star clustering. We take advantage of both methods to build a large-scale extinction map (2.degrees5 x 2.degrees5) of the North America and Pelican Nebulae complex. With K(s) star counts and H-K(s) color analysis the visual extinction is mapped up to 35 mag. Regions with visual extinction greater than 20 mag account for less than 3% of the total mass of the cloud. Color is generally a better estimator for the extinction than star counts. Nine star clusters are identified in the area, seven of which were previously unknown. C1 CALTECH, Ctr Infrared Proc & Anal, Jet Prop Lab, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Cambresy, L (reprint author), CALTECH, Ctr Infrared Proc & Anal, Jet Prop Lab, M-S 100-22, Pasadena, CA 91125 USA. EM laurent@ipac.caltech.edu; chas@pop.jpl.nasa.gov; jarrett@ipac.caltech.edu; roc@ipac.caltech.edu NR 57 TC 78 Z9 79 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 2002 VL 123 IS 5 BP 2559 EP 2573 DI 10.1086/339830 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 547AZ UT WOS:000175311200028 ER PT J AU Landgraf, M Liou, JC Zook, HA Grun, E AF Landgraf, M Liou, JC Zook, HA Grun, E TI Origins of solar system dust beyond Jupiter SO ASTRONOMICAL JOURNAL LA English DT Article DE comets : individual (1P/Halley, 29P/Schwassmann-Wachmann 1); Kuiper belt; solar system : general ID KUIPER-BELT; INTERSTELLAR DUST; COMET P/HALLEY; INTERPLANETARY; PARTICLES; OBJECTS; SIGNATURES; GRAINS; MODEL; EARTH AB The measurements of cosmic interplanetary dust by the instruments on board the Pioneer 10 and 11 spacecraft contain the dynamical signature of dust generated by Edgeworth-Kuiper belt objects, as well as short-period Oort cloud comets and short-period Jupiter-family comets. While the dust concentration detected between Jupiter and Saturn is mainly due to the cometary components, the dust outside Saturn's orbit is dominated by grains originating from the Edgeworth-Kuiper belt. In order to sustain a dust concentration that accounts for the Pioneer measurements, short-period external Jupiter-family comets, on orbits similar to that of comet 29P/Schwassmann-Wachmann 1, have to produce 8x10(4) g s(-1) of dust grains with sizes between 0.01 and 6 mm. A sustained production rate of 3x10(5) g s(-1) has to be provided by short-period Oort cloud comets on 1P/Halley-like orbits. The comets cannot, however, account for the dust flux measured outside Saturn's orbit. The measurements there can only be explained by generation of dust grains in the Edgeworth-Kuiper belt by mutual collisions of the source objects and by impacts of interstellar dust grains onto the objects surfaces. These processes have to release in total 5x10(7) g s(-1) of dust from the Edgeworth-Kuiper belt objects in order to account for the amount of dust found by Pioneer beyond Saturn, making the Edgeworth-Kuiper disk the brightest extended feature of the solar system when observed from afar. C1 European Space Technol Ctr, D-64293 Darmstadt, Germany. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin Space Operat, Houston, TX 77058 USA. Max Planck Inst Kernphys, D-69029 Heidelberg, Germany. RP Landgraf, M (reprint author), European Space Technol Ctr, Robert Bosch Str 5, D-64293 Darmstadt, Germany. NR 30 TC 77 Z9 78 U1 1 U2 5 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 2002 VL 123 IS 5 BP 2857 EP 2861 DI 10.1086/339704 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 547AZ UT WOS:000175311200052 ER PT J AU Chambers, JE Quintana, EV Duncan, MJ Lissauer, JJ AF Chambers, JE Quintana, EV Duncan, MJ Lissauer, JJ TI Symplectic integrator algorithms for modeling planetary accretion in binary star systems SO ASTRONOMICAL JOURNAL LA English DT Article DE celestial mechanics; methods : n-body simulations; methods : numerical ID TERRESTRIAL PLANETS; CLOSE ENCOUNTERS; 3 DIMENSIONS; STABILITY AB We derive and test two new symplectic integrator algorithms, suitable for studying planetary accretion in binary star systems. The algorithms incorporate the hierarchical nature of stable planetary orbits in binary star systems. In one case, planets orbit a single star, perturbed by a distant companion; in the second case, planets orbit both binary members. Each algorithm integrates close encounters between planets symplectically using a hybrid symplectic scheme. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA. Queens Univ, Dept Phys, Kingston, ON K7L 3N6, Canada. RP Chambers, JE (reprint author), NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. NR 22 TC 41 Z9 41 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 2002 VL 123 IS 5 BP 2884 EP 2894 DI 10.1086/340074 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 547AZ UT WOS:000175311200054 ER PT J AU Salas, JB Pottasch, SR Feibelman, WA Wesselius, PR AF Salas, JB Pottasch, SR Feibelman, WA Wesselius, PR TI An ISO and IUE study of planetary nebula NGC 2440 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE ISM : abundances; planetary nebulae : individual : NGC2440; infrared : ISM; ISM : lines and bands ID EFFECTIVE COLLISION STRENGTHS; STRUCTURE FORBIDDEN TRANSITIONS; IRON PROJECT; ATOMIC DATA; EMISSION-LINES; GROUND CONFIGURATION; INFRARED TRANSITIONS; ULTRAVIOLET-SPECTRA; OPTICAL-SPECTRA; NE-IV AB The infrared and ultraviolet spectra of planetary nebula NGC2440 are presented. The observations were made by the Infrared Space Observatory (ISO) and the International Ultraviolet Explorer (IUE). These data, in conjunction with published optical observations have been used to derive electron temperature and density. The electron temperature increases with increasing ionization potential, from 11 000 to 18 000 K. The electron density has a constant value of 4500 cm(-3) in agreement with previous determinations. The chemical abundance has been derived for the following elements; helium, carbon, nitrogen, oxygen, neon, sulfur and argon. The ionization correction factor turns out to be very small for all species except sulfur. C1 SRON, Space Res Lab, NL-9700 AV Groningen, Netherlands. Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Salas, JB (reprint author), SRON, Space Res Lab, POB 800, NL-9700 AV Groningen, Netherlands. NR 41 TC 9 Z9 9 U1 1 U2 1 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 2002 VL 387 IS 1 BP 301 EP 309 DI 10.1051/0004-6361:20020351 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 548XP UT WOS:000175415400034 ER PT J AU O'Shea, E Muglach, K Fleck, B AF O'Shea, E Muglach, K Fleck, B TI Oscillations above sunspots: Evidence for propagating waves? SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE Sun : sunspot; Sun : oscillations; waves ID TRANSITION REGION OSCILLATIONS; UMBRAL OSCILLATIONS; PHOTOELECTRIC OBSERVATIONS; SOLAR CHROMOSPHERE; PLUMES; MODEL; ATMOSPHERE; SPECTRUM; SOHO AB We present results of an analysis of time series data observed in sunspot umbral regions. The data were obtained in the context of the SOHO Joint Observing Program (JOP) 97 in September 2000. This JOP included the Coronal Diagnostic Spectrometer (CDS) and the Michelson Doppler Imaging (MDI) instrument, both part of SOHO, the TRACE satellite and various ground based observatories. The data was analysed by using both Fourier and wavelet time series analysis techniques. We find that oscillations are present in the umbra at all temperatures investigated, from the temperature minimum as measured by TRACE 1700 Angstrom up to the upper corona as measured by CDS Fe XVI 335 Angstrom (logT = 6:4 K). Oscillations are found to be present with frequencies in the range of 5.4 mHz (185 s) to 8.9 mHz (112 s). Using the techniques of cross-spectral analysis time delays were found between low and high temperature emission suggesting the possibility of both upward and downward wave propagation. It is found that there is typically a good correlation between the oscillations measured at the different emission temperatures, once the time delays are taken into account. We find umbral oscillations both inside and outside of sunspot plume locations which indicates that umbral oscillations can be present irrespective of the presence of these sunspot plumes. We find that a number of oscillation frequencies can exist co-spatially and simultaneously i.e. for one pixel location three different frequencies at 5.40, 7.65 and 8.85 mHz were measured. We investigate the variation of the relative amplitudes of oscillation with temperature and find that there is a tendency for the amplitudes to reach a maximum at the temperature of O III (and less typically OV and Mg IX) and then to decrease to reach a minimum at the temperature of Mg X (logT = 6.0 K), before increasing again at the temperature of Fe XVI. We discuss a number of possible theoretical scenarios that might explain these results. From a measurement of propagation speeds we suggest that the oscillations we observe are due to slow magnetoacoustic waves propagating up along the magnetic field lines. C1 ESA, ESTEC, Res & Sci Support Dept RSSD, NL-2201 AZ Noordwijk, Netherlands. Astrophys Inst Potsdam, D-14482 Potsdam, Germany. NASA, Goddard Space Flight Ctr, ESA Res & Sci Support Dept RSSD, Greenbelt, MD 20771 USA. RP Inst Astrofis Canarias, C Via Lactea S-N, San Cristobal la Laguna 38200, Tenerife, Spain. EM eoshea@rssd.esa.int; k.muglach@aip.de; bfleck@esa.nascom.nasa.gov RI Fleck, Bernhard/C-9520-2012 NR 37 TC 67 Z9 67 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 2002 VL 387 IS 2 BP 642 EP 664 DI 10.1051/0004-6361:20020375 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 556PM UT WOS:000175858200028 ER PT J AU De Moortel, I Ireland, J Hood, AW Walsh, RW AF De Moortel, I Ireland, J Hood, AW Walsh, RW TI The detection of 3 & 5 min period oscillations in coronal loops SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE MHD; Sun : oscillations; corona; sunspots ID SUNSPOT TRANSITION REGION; PLUMES; WAVES; EXPLORER; TRACE AB High cadence, 171 Angstrom, TRACE observations show that outward propagating intensity disturbances are a common feature in large, quiescent coronal loops. These oscillations are interpreted as propagating slow magneto-acoustic waves. Using a wavelet analysis, we found periods of the order of 282 +/- 93 s. However, a careful study of the location of the footpoints revealed a distinct separation between those loops that support oscillations with periods smaller than 200 s and periods larger than 200 s. It was found that loops that are situated above sunspot regions display intensity oscillations with a period of the order of 172 +/- 32 s, whereas oscillations in "non-sunspot" loops show periods of the order of 321 +/- 74 s. We conclude that the observed longitudinal oscillations are not are-driven but are most likely caused by an underlying driver exciting the loop footpoints. This result suggests that the underlying oscillations can propagate through the transition region and into the corona. C1 Univ St Andrews, Sch Math & Stat, St Andrews KY16 9SS, Fife, Scotland. NASA, L3Com Analyt Corp, GSFC, Greenbelt, MD 20771 USA. Univ Cent Lancashire, Dept Phys Astron & Maths, Preston PR1 2HE, Lancs, England. RP De Moortel, I (reprint author), Univ St Andrews, Sch Math & Stat, St Andrews KY16 9SS, Fife, Scotland. NR 17 TC 137 Z9 137 U1 0 U2 2 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 2002 VL 387 IS 1 BP L13 EP L16 DI 10.1051/0004-6361:20020436 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 548XP UT WOS:000175415400004 ER PT J AU Castro-Carrizo, A Bujarrabal, V Contreras, CS Alcolea, J Neri, R AF Castro-Carrizo, A Bujarrabal, V Contreras, CS Alcolea, J Neri, R TI The structure and dynamics of the molecular envelope of M2-56 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : individual : M2-56; circumstellar matter; stars : AGB and post-AGB; radio lines : stars; stars : mass-loss ID PROTOPLANETARY NEBULA M-1-92; PHOTODISSOCIATION; EMISSION; GL-618; MASS; CO AB M2-56 is a protoplanetary nebula (PPN) in which strong shocks are taking place, therefore, useful to study the post AGB wind interaction. It is well known that molecular observations allow studying the mass distribution of PPNe, even in those regions that have been recently shocked. We present high resolution maps of the emission of (CO)-C-12 J =2-1 and J = 1-0 in M2-56. Such maps show a bipolar, molecular nebula that extends similar to28" along the symmetry axis. The nebula is composed of two contiguous, incomplete shells located along the symmetry axis, which has an inclination of similar to17degrees with respect to the plane of the sky. Those empty lobes intersect in the center of the nebula, where there is a small and dense ring perpendicular to the axis. This central ring expands radially at about 8 km s(-1) and seems to be the remnant of the circumstellar envelope of the AGB star, that has not been accelerated by the interaction with the fast post AGB jets. The radius of the central ring is of similar to4 x 10(16) cm, for a distance of 2.1 kpc (deduced from an analysis of the main properties of the object). At similar to4 x 10(17) cm from the nebular center, the tips of the lobes reach axial expansion velocities of similar to200 km s(-1). We have developed a model for the spatio-kinematical distribution and the excitation conditions of the molecular gas in M2-56. From the best fitting of the observations with the predictions of the model for both lines, we have estimated the physical conditions of the molecular nebula. It is found that the density varies from 5 x 10(3) to 0.6 x 10(3) cm(-3) from the nebular center to the lobe tips, and that the part of the lobes that has not been detected is probably composed of photodissociated gas, due to the effect of interstellar photons on low density regions. The rotational temperature is estimated to be approximately constant, similar to 13 16 K. For the assumed geometry, a velocity field composed by a dominant radial component plus an axial contribution has been deduced. The emission of both lines is found to be optically thin, and therefore probes the whole molecular gas, which has a mass of similar to0.05 M-.. The "scalar" momentum and the kinetic energy of the different regions of the molecular nebula have been calculated, finding that the high momentum won by the gas in the post AGB phase cannot have been supplied by the radiation pressure mechanism. Although the central star of M2-56 is not very hot yet (similar to20 000 K), this PPN has a large kinematical age, between 1000 yr and 1700 yr, in comparison with other PPNe that have hotter central stars. M2-56 may not be a typical PPN, but an intermediate object between the known low mass post AGB nebulae and the standard PPNe. C1 Observ Astron Nacl, IGN, Alcala De Henares 28800, Spain. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Inst Radio Astron Millimetr, F-38406 St Martin Dheres, France. RP Castro-Carrizo, A (reprint author), Observ Astron Nacl, IGN, Apdo 1143, Alcala De Henares 28800, Spain. RI Sanchez-Contreras, Carmen/N-3718-2015 OI Sanchez-Contreras, Carmen/0000-0002-6341-592X NR 19 TC 32 Z9 32 U1 0 U2 0 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 2002 VL 386 IS 2 BP 633 EP 645 DI 10.1051/0004-6361:20020220 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 543YX UT WOS:000175132400023 ER PT J AU Zhang, S Collmar, W Bennett, K Bloemen, H Hermsen, W McConnell, M Reimer, O Schonfelder, V Wagner, SJ Williams, OR AF Zhang, S Collmar, W Bennett, K Bloemen, H Hermsen, W McConnell, M Reimer, O Schonfelder, V Wagner, SJ Williams, OR TI COMPTEL observations of the gamma-ray blazar PKS 1622-297 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE gamma rays : observations; galaxies : active; galaxies : quasars : individual : PKS 1622-297 ID EXTRAGALACTIC RADIO-SOURCES; POLARIZATION PROPERTIES; EGRET OBSERVATIONS; QUASARS 3C-273; EMISSION; MODEL; JET; RADIATION; SPECTRA; FLARE AB We report results of observations and analyses on the gamma-ray blazar PKS 1622-297, with emphasis on the COMPTEL data (0.75-30 MeV) collected between April 1991 and November 1997. PKS 1622-297 was detected as a source of gamma-rays by the EGRET experiment aboard CGRO in 1995 during a gamma-ray outburst at energies above 100 MeV lasting for five weeks. In this time period the blazar was significantly (similar to 5.9 sigma) detected by COMPTEL at 10{30 MeV. At lower COMPTEL energies the detection is marginal, resulting in a hard MeV spectrum. The combined COMPTEL/EGRET energy spectrum shows a break at MeV energies. The broad-band spectrum (radio {-gamma-rays) shows that the gamma-ray emission dominates the overall power output. On top of the 5-week gamma-ray outburst, EGRET detected a huge are lasting for >1 day. Enhanced MeV emission (10-30 MeV) is found near the time of this are, suggesting a possible time delay with respect to the emission above 100 MeV. Outside the 5-week flaring period in 1995, we do not detect MeV emission from PKS 1622-297. C1 Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. SRON, Natl Inst Space Res, NL-3584 CA Utrecht, Netherlands. Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA. European Space Agcy, Dept Space Sci, Div Astrophys, ESTEC, NL-2200 AG Noordwijk, Netherlands. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Inst High Energy Phys, Lab Cosm Ray & High Energy Astrophys, Beijing 100039, Peoples R China. Landessternwarte Heidelberg, D-69117 Heidelberg, Germany. RP Zhang, S (reprint author), Max Planck Inst Extraterr Phys, POB 1603, D-85740 Garching, Germany. EM shz@mpe.mpg.de RI Reimer, Olaf/A-3117-2013 OI Reimer, Olaf/0000-0001-6953-1385 NR 40 TC 6 Z9 6 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 2002 VL 386 IS 3 BP 843 EP 853 DI 10.1051/0004-6361:20020267 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 546HZ UT WOS:000175269800009 ER PT J AU Benoit, A Ade, P Amblard, A Ansari, R Aubourg, E Bartlett, J Bernard, JP Bhatia, RS Blanchard, A Bock, JJ Boscaleri, A Bouchet, FR Bourrachot, A Camus, P Couchot, F de Bernardis, P Delabrouille, J Desert, FX Dore, O Douspis, M Dumoulin, L Dupac, X Filliatre, P Ganga, K Gannaway, F Gautier, B Giard, M Giraud-Heraud, Y Gispert, R Guglielmi, L Hamilton, JC Hanany, S Henrot-Versille, S Hristov, VV Kaplan, J Lagache, G Lamarre, JM Lange, AE Madet, K Maffei, B Marrone, D Masi, S Murphy, JA Naraghi, F Nati, F Perrin, G Piat, M Puget, JL Santos, D Sudiwala, RV Vanel, JC Vibert, D Wakui, E Yvon, D AF Benoit, A Ade, P Amblard, A Ansari, R Aubourg, E Bartlett, J Bernard, JP Bhatia, RS Blanchard, A Bock, JJ Boscaleri, A Bouchet, FR Bourrachot, A Camus, P Couchot, F de Bernardis, P Delabrouille, J Desert, FX Dore, O Douspis, M Dumoulin, L Dupac, X Filliatre, P Ganga, K Gannaway, F Gautier, B Giard, M Giraud-Heraud, Y Gispert, R Guglielmi, L Hamilton, JC Hanany, S Henrot-Versille, S Hristov, VV Kaplan, J Lagache, G Lamarre, JM Lange, AE Madet, K Maffei, B Marrone, D Masi, S Murphy, JA Naraghi, F Nati, F Perrin, G Piat, M Puget, JL Santos, D Sudiwala, RV Vanel, JC Vibert, D Wakui, E Yvon, D TI Archeops: a high resolution, large sky coverage balloon experiment for mapping cosmic microwave background anisotropies SO ASTROPARTICLE PHYSICS LA English DT Article ID FOREGROUNDS; BOLOMETERS AB Archeops is a balloon-borne instrument dedicated to measuring cosmic microwave background (CMB) temperature anisotropies at high angular resolution (similar to8') over a large fraction (similar to25%) of the sky in the millimetre domain. Based on Planck high frequency instrument technology, cooled bolometers (0.1 K) scan the sky in total power mode with large circles at constant elevation. During the course of a 24-h Arctic-night balloon flight, Archeops will observe a complete annulus on the sky in four frequency bands centered at 143, 217 353 and 545 GHz with an expected sensitivity to CMB fluctuations of similar to100 muK for each of the 90 thousand 20' average pixels. We describe the instrument and its performance obtained during a test flight from Trapani (Sicily) to Spain in July 1999. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Ctr Rech Tres Basses Temp, F-38042 Grenoble 9, France. Univ London Queen Mary & Westfield Coll, Dept Phys, Astrophys Lab, London E1 4NS, England. Coll France, F-75231 Paris 5, France. Lab Accelerateur Lineaire, F-91898 Orsay, France. CEA Saclay, SPP DAPNIA DSM, F-91191 Gif Sur Yvette, France. Observ Midi Pyrenees, F-31400 Toulouse, France. Univ Paris 11, Inst Astrophys Spatiale, F-91405 Orsay, France. CALTECH, Pasadena, CA 91109 USA. Jet Prop Lab, Pasadena, CA 91109 USA. CNR, IROE, I-50127 Florence, Italy. Inst Astrophys, F-75014 Paris, France. IN2P3, CSNSM, F-91405 Orsay, France. Univ Roma La Sapienza, Dipartimento Fis, Grp Cosmol Sperimentale, I-00185 Rome, Italy. Ctr Etud Spatiale Rayonnements, F-38041 Grenoble 4, France. Inst Nucl Sci, F-38026 Grenoble, France. Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA. Natl Univ Ireland, St Patricks Coll, Dept Phys, Maynooth, Kildare, Ireland. RP Desert, FX (reprint author), Ctr Rech Tres Basses Temp, 25 Ave Martyrs BP166, F-38042 Grenoble 9, France. RI Bouchet, Francois/B-5202-2014; amblard, alexandre/L-7694-2014; Yvon, Dominique/D-2280-2015; Nati, Federico/I-4469-2016; OI amblard, alexandre/0000-0002-2212-5395; Nati, Federico/0000-0002-8307-5088; Masi, Silvia/0000-0001-5105-1439; de Bernardis, Paolo/0000-0001-6547-6446; Bouchet, Francois/0000-0002-8051-2924 NR 26 TC 63 Z9 63 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-6505 J9 ASTROPART PHYS JI Astropart Phys. PD MAY PY 2002 VL 17 IS 2 BP 101 EP 124 AR PII S0927-6505(01)00141-4 DI 10.1016/S0927-6505(01)00141-4 PG 24 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 559TL UT WOS:000176041400001 ER PT J AU Molnar, SM Birkinshaw, M Mushotzky, RF AF Molnar, SM Birkinshaw, M Mushotzky, RF TI Constraints in cosmological parameter space from the Sunyaev-Zeldovich effect and thermal bremsstrahlung SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmological parameters; cosmology : theory; galaxies : clusters : general; X-rays : galaxies : clusters ID X-RAY-PROPERTIES; MICROWAVE BACKGROUND ANISOTROPIES; HUBBLE-CONSTANT; COOLING-FLOW; GALAXY CLUSTERS; POWER SPECTRUM; INTRACLUSTER MEDIUM; SYSTEMATIC-ERRORS; HIGH-RESOLUTION; EMISSION AB We discuss how the space of possible cosmological parameters is constrained by the angular diameter distance function D-A(z) as measured using the SZ/X-ray method, which combines the Sunyaev-Zeldovich (SZ) effect and X-ray brightness data for clusters of galaxies. New X-ray satellites and ground-based interferometers dedicated to SZ observations should soon lead to D-A(z) measurements limited by systematic rather than random error. We analyze the systematic and random error budgets to make a realistic estimate of the accuracy achievable in the determination of (Omega(m), Omega(A), h), the density parameters of matter and cosmological constant, and the dimensionless Hubble constant, using D-A(z) derived from the SZ/X-ray method and the position of the first Doppler peak in the cosmic microwave background fluctuations. We briefly study the effect of systematic errors. We find that Omega(m), Omega(A), and w are affected, but h is not, by systematic errors that grow with redshift. With as few as 70 clusters, each providing a measurement of D-A(z) with a 7% random and 5% systematic error, Omega(m) can be constrained to +/-0.2, Omega(A) to +/-0.2, and h to +/-0.11 ( all at 3sigma). We also estimate constraints for the alternative three-parameter set ( Omega(m), w, h), where w is the equation-of-state parameter. The measurement of D-A(z) provides constraints complementary to those from the number density of clusters in redshift space. A sample of 70 clusters (D-A measured with the same accuracy as before) combined with cluster evolution results (or a known matter density) can constrain w within +/-0.45 (at 3sigma). Studies of X-ray and SZ properties of clusters of galaxies promise an independent and powerful test for cosmological parameters. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Bristol, Dept Phys, Bristol BS8 1TL, Avon, England. RP Molnar, SM (reprint author), Rutgers State Univ, Dept Phys & Astron, 136 Frelinghuysen Rd, Piscataway, NJ 08854 USA. NR 97 TC 20 Z9 20 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2002 VL 570 IS 1 BP 1 EP 16 DI 10.1086/339568 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 547AG UT WOS:000175309300001 ER PT J AU Dawson, S Spinrad, H Stern, D Dey, A van Breugel, W de Vries, W Reuland, M AF Dawson, S Spinrad, H Stern, D Dey, A van Breugel, W de Vries, W Reuland, M TI A galactic wind at z=5.190 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; early universe; galaxies : high-redshift; galaxies : individual (J1236.8+6215); galaxies : starburst ID HUBBLE-DEEP-FIELD; STAR-FORMING GALAXIES; HIGH-REDSHIFT; LY-ALPHA; RADIATIVE-TRANSFER; ELLIPTIC GALAXIES; KECK SPECTROSCOPY; CLUMPY UNIVERSE; REIONIZATION; EVOLUTION AB We report the serendipitous detection in high-resolution optical spectroscopy of a strong, asymmetric Lyalpha emission line at z = 5.190. The detection was made in a 2.25 hr exposure with the Echelle Spectrograph and Imager on the Keck II telescope through a spectroscopic slit of dimensions 1" x 20". The progenitor of the emission line, J123649.2 + 621539 ( hereafter ES1), lies in the Hubble Deep Field North northwest flanking field, where it appears faint and compact, subtending just 0."3 (FWHM) with I-AB = 25.4. The ES1 Lyalpha line flux of 3.0 x 10(-17) ergs cm(-2) s(-1) corresponds to a luminosity of 9.0 x 10(42) ergs s(-1), and the line pro le shows the sharp blue cutoff and broad red wing commonly observed in star-forming systems and expected for radiative transfer in an expanding envelope. We find that the Lyalpha profile is consistent with a galaxy-scale outflow with a velocity of v > 300 km s(-1). This value is consistent with wind speeds observed in powerful local star-bursts (typically 10(2)-10(3) km s(-1)) and compares favorably to simulations of the late-stage evolution of Lyalpha emission in star-forming systems. We discuss the implications of this high-redshift galactic wind for the early history of the evolution of galaxies and the intergalactic medium and for the origin of the UV background at z > 3. C1 Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Kitt Peak Natl Observ, Natl Opt Astron Observ, Tucson, AZ 85726 USA. Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94550 USA. RP Dawson, S (reprint author), Univ Calif Berkeley, Dept Astron, Mail Code 3411, Berkeley, CA 94720 USA. NR 54 TC 76 Z9 76 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2002 VL 570 IS 1 BP 92 EP 99 DI 10.1086/339579 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 547AG UT WOS:000175309300008 ER PT J AU Chiar, JE Adamson, AJ Pendleton, YJ Whittet, DCB Caldwell, DA Gibb, EL AF Chiar, JE Adamson, AJ Pendleton, YJ Whittet, DCB Caldwell, DA Gibb, EL TI Hydrocarbons, ices, and "XCN" in the line of sight toward the Galactic center SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; Galaxy : center; infrared : ISM : lines and bands; infrared : stars; ISM : molecules ID DIFFUSE INTERSTELLAR-MEDIUM; GIANT MOLECULAR CLOUDS; YOUNG STELLAR OBJECTS; INFRARED-SPECTROSCOPY; GRAIN MANTLES; ABSORPTION FEATURES; ISOTOPIC-SUBSTITUTION; MICRON ABSORPTION; 3-MICRON SPECTRA; SWS OBSERVATIONS AB We discuss 2.8-3.9 mum spectra from the United Kingdom Infrared Telescope of seven sight lines toward IR sources near Sagittarius A* in the Galactic center (GC). In all lines of sight, the 3.0 mum H2O ice feature is present with optical depths in the range 0.33-1.52. By constructing a simple ice model, we show that the ice pro le is not fully accounted for by pure H2O ice mantles. Residual absorption is present at 2.95 and 3.2-3.6 l m. Aliphatic hydrocarbon absorption at 3.4 mum is shown to vary by a factor of 1.7, indicating significant changes in the foreground extinction across the small field. By determining the true ice pro le for the GC line of sight, we reveal an additional broad absorption component around similar to3.3 mum, which partially underlies the similar to3.4 mum aliphatic hydrocarbon feature. Its carrier resides in the diffuse interstellar medium. The width of this absorption is deduced to be at least similar to100 cm(-1), much broader than individual polycyclic aromatic hydrocarbon molecules produced in the laboratory or unidentified infrared emission features observed in the interstellar medium. The 4.62 mum "XCN" feature is detected in the molecular clouds along the line of sight toward IRS 19. In the solar neighborhood, this feature is seen only toward some deeply embedded protostars. Toward the GC, it may indicate the serendipitous presence of such an object in the line of sight to IRS 19, or it might conceivably arise from the processing of ices in the circumnuclear ring of the GC itself. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SETI Inst, Mt View, CA 94043 USA. Joint Astron Ctr, Hilo, HI 96720 USA. Rensselaer Polytech Inst, Dept Phys Appl Phys & Astron, Troy, NY 12180 USA. RP Chiar, JE (reprint author), NASA, Ames Res Ctr, Mail Stop 245-3, Moffett Field, CA 94035 USA. RI Caldwell, Douglas/L-7911-2014; OI Caldwell, Douglas/0000-0003-1963-9616; Whittet, Douglas/0000-0001-8539-3891; adamson, andrew/0000-0003-1120-5178 NR 82 TC 50 Z9 50 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2002 VL 570 IS 1 BP 198 EP 209 DI 10.1086/339570 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 547AG UT WOS:000175309300018 ER PT J AU Wilson, CA Finger, MH Coe, MJ Laycock, S Fabregat, J AF Wilson, CA Finger, MH Coe, MJ Laycock, S Fabregat, J TI A decade in the life of EXO 2030+375: A multiwavelength study of an accreting X-ray pulsar SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; pulsars : individual (EXO 2030+375); stars : neutron; X-rays : binaries; X-rays : individual (EXO 2030+375) ID QUASI-PERIODIC OSCILLATIONS; LUMINOSITY DEPENDENCE; TIMING EXPLORER; WIND-ACCRETION; NEUTRON STARS; EXO-2030+375; BINARY; OUTBURST; DISCOVERY; EMISSION AB Using BATSE and RXTE observations from 1991 April to 2001 August, we have detected 71 outbursts from 82 periastron passages of EXO 2030+375, a 42 s transient X-ray pulsar with a Be star companion, including several outbursts from 1993 August to 1996 April, when the source was previously believed to be quiescent. Combining BATSE, RXTE, and EXOSAT data, we have derived an improved orbital solution. Applying this solution results in a smooth pro le for the spin-up rate during the giant outburst and results in evidence for a correlation between the spin-up rate and observed flux in the brighter BATSE outbursts. Infrared and H measurements show a decline in the density of the circumstellar disk around the Be star. This decline is followed by a sudden drop in the X-ray flux and a turnover from a spin-up trend to spin-down in the frequency history. This is the first Be/X-ray binary that shows an extended interval, about 2.5 yr, in which the global trend is spin-down, but the outbursts continue. In 1995 the orbital phase of EXO 2030+375's outbursts shifted from peaking about 6 days after periastron to peaking before periastron. The outburst phase slowly recovered to peaking at about 2.5 days after periastron. We interpret this shift in orbital phase followed by a slow recovery as evidence of a global one-armed oscillation propagating in the Be disk. This is further supported by changes in the shape of the H profile, which are commonly believed to be produced by a reconfiguration of the Be disk. The truncated viscous decretion disk model provides an explanation for the long series of normal outbursts and the evidence of an accretion disk in the brighter normal outbursts. Longterm multiwavelength observations such as these clearly add considerably to our knowledge of Be/X-ray binaries and the relationship among optical, infrared, and X-ray observations. C1 Natl Space Sci & Technol Ctr, Space Sci Res Ctr SD 50, Huntsville, AL 35805 USA. Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. Univ Valencia, Dept Astron & Astrofis, E-46100 Valencia, Spain. RP Wilson, CA (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RI Fabregat, Juan/F-9066-2016 OI Fabregat, Juan/0000-0002-5986-9347 NR 64 TC 52 Z9 52 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2002 VL 570 IS 1 BP 287 EP 302 DI 10.1086/339739 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 547AG UT WOS:000175309300026 ER PT J AU Thompson, RR Creech-Eakman, MJ Akeson, RL AF Thompson, RR Creech-Eakman, MJ Akeson, RL TI Time-dependent asymmetries in the atmosphere of the Mira variable R Trianguli through infrared interferometry SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : stars; stars : AGB and post-AGB; stars : atmospheres; stars : fundamental parameters; stars : individual (R Trianguli); techniques : interferometric ID PALOMAR TESTBED INTERFEROMETER; HUBBLE-SPACE-TELESCOPE; SOLAR NEIGHBORHOOD; ALPHA-ORIONIS; M-GIANTS; STARS; SPECTROSCOPY; KINEMATICS; DIAMETERS; EMISSION AB We report high-resolution ( < 0.05 mas) angular size measurements of the Mira variable star R Tri using the Palomar Testbed Interferometer. Observations were conducted in the K band (2.0-2.4 μm) between the visual phases of 0.77 and 0.88, and one period later at phase 0.91. The spatial coverage of the measurements spans 40&DEG; in position angle. Three simple geometries were modeled: a uniform ellipse model and a uniform sphere with a brighter "disk" model have lower χ(2)(μ) than the uniform spherical disk model by factors of 5-10. For the axially symmetric models, the axis of symmetry is clustered between 20degrees and 35degrees. The position angles are roughly perpendicular to visual polarization position angles, which supports an axially symmetric source of light scattering. For the elliptical geometry, averaging the semimajor and semiminor axes throughout the data set yields an ensemble average angular diameter of 5.22 +/- 0.30 mas; the ensemble average axial ratio of 2a/2b = 0.75 is similar to that previously determined for other Mira and semiregular variable stars. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Wyoming, Dept Phys & Astron, Laramie, WY 82071 USA. CALTECH, Infrared Proc & Anal Ctr, Pasadena, CA 91125 USA. RP Thompson, RR (reprint author), CALTECH, Jet Prop Lab, MS 171-113,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 43 TC 30 Z9 30 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2002 VL 570 IS 1 BP 373 EP 378 DI 10.1086/339736 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 547AG UT WOS:000175309300032 ER PT J AU Suchkov, AA Schultz, AB Lisse, CM AF Suchkov, AA Schultz, AB Lisse, CM TI Candidate pre-main-sequence F stars with circumstellar dust identified using combined 2MASS and uvby data SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; infrared : stars; planetary systems : protoplanetary disks; stars : pre-main-sequence ID PHOTOMETRY; POPULATION; BINARIES; MATTER; CLOUD AB We propose a method that uses near-infrared plus uvby photometry to identify potentially extensive circumstellar dusty environments around F and A stars. The method has been applied to a sample of similar to900 metal-rich reddened F stars with 2 Micron All Sky Survey and uvby data, suggesting the presence of circumstellar dust emitting in the near-infrared for similar to70 stars. The log T-e-M-V diagram suggests that most, if not all, are likely pre-main-sequence (PMS) stars. They seem to be a continuation of the class of Herbig Ae/Be PMS stars in the spectral type F. Their number drops sharply downward of log T-e similar to 3/84 (spectral types later than similar toF5), which may provide new clues to the PMS evolution of 1-2 M. stars. We present a list of 21 of the most conspicuous candidate stars with circumstellar dust. About half of them are associated with the extended star-forming region around rho Ophiuchi. The brightest of these 21 stars, with V less than or similar to 7.5, turn out to be IRAS sources, suggesting the presence of heated dust emitting in the far-infrared. Also in this list, HD 81270 is reported as a very unusual star moving away from the Galactic plane at a projected speed of 70 km s(-1). C1 NASA, Baltimore, MD 21218 USA. Comp Sci Corp, Sci Programs, Baltimore, MD 21218 USA. Univ Maryland, Dept Astron, College Pk, MD USA. RP Suchkov, AA (reprint author), NASA, 3700 San Martin Dr, Baltimore, MD 21218 USA. RI Lisse, Carey/B-7772-2016 OI Lisse, Carey/0000-0002-9548-1526 NR 23 TC 7 Z9 7 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 2002 VL 570 IS 1 BP L29 EP L32 DI 10.1086/340856 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 547AN UT WOS:000175309900008 ER PT J AU Moos, HW Sembach, KR Vidal-Madjar, A York, DG Friedman, SD Hebrard, G Kruk, JW Lehner, N Lemoine, M Sonneborn, G Wood, BE Ake, TB Andre, M Blair, WP Chayer, P Gry, C Dupree, AK Ferlet, R Feldman, PD Green, JC Howk, JC Hutchings, JB Jenkins, EB Linsky, JL Murphy, EM Oegerle, WR Oliveira, C Roth, K Sahnow, DJ Savage, BD Shull, JM Tripp, TM Weiler, EJ Welsh, BY Wilkinson, E Woodgate, BE AF Moos, HW Sembach, KR Vidal-Madjar, A York, DG Friedman, SD Hebrard, G Kruk, JW Lehner, N Lemoine, M Sonneborn, G Wood, BE Ake, TB Andre, M Blair, WP Chayer, P Gry, C Dupree, AK Ferlet, R Feldman, PD Green, JC Howk, JC Hutchings, JB Jenkins, EB Linsky, JL Murphy, EM Oegerle, WR Oliveira, C Roth, K Sahnow, DJ Savage, BD Shull, JM Tripp, TM Weiler, EJ Welsh, BY Wilkinson, E Woodgate, BE TI Abundances of deuterium, nitrogen, and oxygen in the local interstellar medium: Overview of first results from the FUSE mission SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE cosmology : observations; Galaxy : abundances; ISM : abundances; ISM : evolution; ultraviolet : ISM ID ON-ORBIT PERFORMANCE; D/H RATIO; WHITE-DWARF; SPATIAL VARIATIONS; SIGHT; LINE; ABSORPTION; HYDROGEN; STARS; SPECTROGRAPH AB Observations obtained with the Far Ultraviolet Spectroscopic Explorer ( FUSE) have been used to determine the column densities of D I, N I, and O I along seven sight lines that probe the local interstellar medium (LISM) at distances from 37 to 179 pc. Five of the sight lines are within the Local Bubble, and two penetrate the surrounding H I wall. Reliable values of N ( H I were determined for five of the sight lines from Hubble Space Telescope (HST) data, International Ultraviolet Explorer (IUE) data, and published Extreme Ultraviolet Explorer ( EUVE) measurements. The weighted mean of D I/H I for these five sight lines is (1.52 +/- 0.08) x 10(-5) (1 sigma uncertainty in the mean). It is likely that the D I/H I ratio in the Local Bubble has a single value. The D I/ O I ratio for the five sight lines within the Local Bubble is (3.76 +/- 0.20) x 10(-2). It is likely that O I column densities can serve as a proxy for H I in the Local Bubble. The weighted mean for O I H I for the seven FUSE sight lines is (3.03 +/- 0.21) x 10(-4), comparable to the weighted mean (3.43 +/- 0.15) x 10(-4) reported for 13 sight lines probing larger distances and higher column densities. The FUSE weighted mean of N I/H I for five sight lines is half that reported by Meyer and colleagues for seven sight lines with larger distances and higher column densities. This result combined with the variability of O I/N I ( six sight lines) indicates that at the low column densities found in the LISM, nitrogen ionization balance is important. Thus, unlike O I, N I cannot be used as a proxy for H I or as a metallicity indicator in the LISM. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Inst Astrophys, F-75014 Paris, France. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Boulder, CO 80309 USA. Comp Sci Corp, Lanham, MD 20706 USA. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. ESA, Div Astrophys, ISO Data Ctr, Madrid 28080, Spain. Astron Spatiale Lab, F-13376 Marseille 12, France. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Colorado, Dept Astrophys & Planetary Sci, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V8X 4M6, Canada. Princeton Univ Observ, Princeton, NJ 08544 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. Gemini Observ, No Operat Ctr, Hilo, HI 96720 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. NASA Headquarters, Washington, DC 20546 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RP Moos, HW (reprint author), Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RI Oegerle, William/C-9070-2012; Sonneborn, George/D-5255-2012; Woodgate, Bruce/D-2970-2012; Kruk, Jeffrey/G-4047-2012; Howk, Jay/D-2577-2013; Jenkins, Edward/P-5684-2014; OI Jenkins, Edward/0000-0003-1892-4423; Howk, J. Christopher/0000-0002-2591-3792; Murphy, Edward/0000-0003-2925-738X NR 89 TC 142 Z9 142 U1 0 U2 5 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD MAY PY 2002 VL 140 IS 1 BP 3 EP 17 DI 10.1086/339133 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541XU UT WOS:000175012500002 ER PT J AU Kruk, JW Howk, JC Andre, M Moos, HW Oegerle, WR Oliveira, C Sembach, KR Chayer, P Linsky, JL Wood, BE Ferlet, R Hebrard, G Lemoine, M Vidal-Madjar, A Sonneborn, G AF Kruk, JW Howk, JC Andre, M Moos, HW Oegerle, WR Oliveira, C Sembach, KR Chayer, P Linsky, JL Wood, BE Ferlet, R Hebrard, G Lemoine, M Vidal-Madjar, A Sonneborn, G TI Abundances of deuterium, nitrogen, and oxygen toward HZ 43A: Results from the FUSE mission SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE ISM : abundances; ISM : clouds; stars : individual (HZ 43A); white dwarfs ID LOCAL INTERSTELLAR-MEDIUM; HOPKINS-ULTRAVIOLET-TELESCOPE; STARK-BROADENING TABLES; RICH WHITE-DWARFS; EFFECTIVE TEMPERATURES; MASS-DISTRIBUTION; HYDROGEN; HOT; MODELS; LINES AB We present an analysis of interstellar absorption along the line of sight to the nearby white dwarf star HZ 43A. The distance to this star is 68 +/- 13 pc, and the line of sight extends toward the north Galactic pole. Column densities of O I, N I, and N II were derived from spectra obtained by the Far Ultraviolet Spectroscopic Explorer ( FUSE), the column density of D I was derived from a combination of our FUSE spectra and an archival Hubble Space Telescope (HST) GHRS spectrum, and the column density of H I was derived from a combination of the GHRS spectrum and values derived from Extreme Ultraviolet Explorer (EUVE) data obtained from the literature. We find the following abundance ratios (with 2 sigma uncertainties) : D I/H I = (1.66 +/- 0.28) x 10(-5), O I/H I = (3.63 +/- 0.84) x 10(-4), and N I/ H I = (3.80 +/- 0.74) x 10(-5). The N II column density was slightly greater than that of N I indicating that ionization corrections are important when deriving nitrogen abundances. Other interstellar species detected along the line of sight were C II C III O vi Si II Ar I Mg II and Fe II an upper limit was determined for N III No elements other than H I were detected in the stellar photosphere. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Boulder, CO 80309 USA. Inst Astrophys, F-75014 Paris, France. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kruk, JW (reprint author), Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RI Oegerle, William/C-9070-2012; Sonneborn, George/D-5255-2012; Kruk, Jeffrey/G-4047-2012; Howk, Jay/D-2577-2013; OI Howk, J. Christopher/0000-0002-2591-3792 NR 76 TC 51 Z9 51 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD MAY PY 2002 VL 140 IS 1 BP 19 EP 36 DI 10.1086/339131 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541XU UT WOS:000175012500003 ER PT J AU Friedman, SD Howk, JC Chayer, P Tripp, TM Hebrard, G Andre, M Oliveira, C Jenkins, EB Moos, HW Oegerle, WR Sonneborn, G Lamontagne, R Sembach, KR Vidal-Madjar, A AF Friedman, SD Howk, JC Chayer, P Tripp, TM Hebrard, G Andre, M Oliveira, C Jenkins, EB Moos, HW Oegerle, WR Sonneborn, G Lamontagne, R Sembach, KR Vidal-Madjar, A TI Deuterium and oxygen toward Feige 110: Results from the FUSE mission SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE cosmology : observations; ISM : abundances; ISM : clouds; stars : individual (Feige 110); ultraviolet : ISM ID ABSORPTION PROFILE SPECTROGRAPH; INTERSTELLAR ATOMIC DEUTERIUM; BIG-BANG NUCLEOSYNTHESIS; MOLECULAR-HYDROGEN; SPATIAL VARIABILITY; ABUNDANCE; STARS; RATIO; EVOLUTION; SYSTEM AB We present measurements of the column densities of interstellar D I and O I made with the Far Ultraviolet Spectroscopic Explorer (FUSE) and of H I made with the International Ultraviolet Explorer (IUE) toward the sdOB star Feige 110 [(l, b) = (74.degrees09, -59.degrees07); d = 179(-67)(+265) pc; z = 154(-227)(+57) pc]. Our determination of the D I column density made use of curve-of-growth fitting and pro letting analyses, while our O I column density determination used only curve-of-growth techniques. The H I column density was estimated by fitting the damping wings of the interstellar Lyalpha profile. We find log N( D I) = 15.47 +/- 0.06, log N (O I) = 16.73 +/- 0.10, and log N (H I) = 20.14(-0.20)(+0.13) (all errors 2sigma). This implies D/H = (2.14 +/- 0.82) x 10(-5), D/O = (5.50(-1.33)(+1.64)) x 10(-2), and O/H = (3.89 +/- 1.67) x 10(-4). Taken with the FUSE results reported in companion papers and previous measurements of the local interstellar medium ( LISM), this suggests the possibility of spatial variability in D/H for sight lines exceeding similar to100 pc. This result may constrain models which characterize the mixing timescales and length scales of material in the LISM. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. Princeton Univ Observ, Princeton, NJ 08544 USA. CNRS, Inst Astrophys Paris, F-75014 Paris, France. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Montreal, Dept Phys, Montreal, PQ H3C 3J7, Canada. RP Friedman, SD (reprint author), Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RI Oegerle, William/C-9070-2012; Sonneborn, George/D-5255-2012; Howk, Jay/D-2577-2013; Jenkins, Edward/P-5684-2014; OI Jenkins, Edward/0000-0003-1892-4423; Howk, J. Christopher/0000-0002-2591-3792 NR 47 TC 37 Z9 37 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD MAY PY 2002 VL 140 IS 1 BP 37 EP 49 DI 10.1086/339132 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541XU UT WOS:000175012500004 ER PT J AU Sonneborn, G Andre, M Oliveira, C Hebrard, G Howk, JC Tripp, TM Chayer, P Friedman, SD Kruk, JW Jenkins, EB Lemoine, M Moos, HW Oegerle, WR Sembach, KR Vidal-Madjar, A AF Sonneborn, G Andre, M Oliveira, C Hebrard, G Howk, JC Tripp, TM Chayer, P Friedman, SD Kruk, JW Jenkins, EB Lemoine, M Moos, HW Oegerle, WR Sembach, KR Vidal-Madjar, A TI Interstellar deuterium, nitrogen, and oxygen abundances toward BD+28 degrees 4211: Results from the FUSE mission SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE cosmology : observations; ISM : abundances; ISM : evolution; stars : individual (BD+28 degrees 4211); ultraviolet : ISM ID TELESCOPE IMAGING SPECTROGRAPH; HUBBLE-SPACE-TELESCOPE; ABSORPTION PROFILE SPECTROGRAPH; BIG-BANG NUCLEOSYNTHESIS; ON-ORBIT PERFORMANCE; BALMER LINE PROBLEM; DA WHITE-DWARFS; SPECTROPHOTOMETRIC STANDARDS; SPATIAL VARIABILITY; GALACTIC EVOLUTION AB High-resolution far-UV spectra of the O-type subdwarf BD + 28degrees4211 were obtained with the Far Ultraviolet Spectroscopic Explorer ( FUSE) to measure the interstellar deuterium, nitrogen, and oxygen abundances in this direction. The interstellar D I transitions are analyzed down to Lyiota at 920.7 Angstrom. The star was observed several times at different target offsets in the direction of spectral dispersion. The aligned and co-added spectra have high signal-to-noise ratios (S/N = 50-100). D I, N I, and O I transitions were analyzed with curve-of-growth and profile fitting techniques. A model of interstellar molecular hydrogen on the line of sight was derived from H(2) lines in the FUSE spectra and used to help analyze some features where blending with H(2) was significant. The H I column density was determined from high-resolution Hubble Space Telescope Space Telescope Imaging Spectrograph spectra of Lyalpha to be log N(H I) = 19.846 +/- 0.035 (2 sigma), which is higher than is typical for sight lines in the local interstellar medium (ISM) studied for D/H. We found that D/H = (1.39 +/- 0.21) x 10(-5) (2 sigma) and O/H = (2.37 +/- 0.55) x 10(-4) (2 sigma). O/H toward BD + 28 degrees4211 appears to be significantly below the mean O/H ratio for the ISM and the Local Bubble. C1 NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Inst Astrophys, F-75014 Paris, France. Princeton Univ Observ, Princeton, NJ 08544 USA. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. RP Sonneborn, G (reprint author), NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Code 681, Greenbelt, MD 20771 USA. EM george.sonneborn@gsfc.nasa.gov; mandre@pha.jhu.edu; oiveira@pha.jhu.edu; hebrard@iap.fr; howk@pha.jhu.edu; tripp@astro.princeton.edu; chayer@pha.jhu.edu; scott@pha.jhu.edu; kruk@pha.jhu.edu; ebj@astro.princeton.edu; lemoine@iap.fr; hwm@pha.jhu.edu; oegerle@s2.gsfc.nasa.gov; sembach@pha.jhu.edu; alfred@iap.fr RI Oegerle, William/C-9070-2012; Kruk, Jeffrey/G-4047-2012; Howk, Jay/D-2577-2013; Jenkins, Edward/P-5684-2014 OI Jenkins, Edward/0000-0003-1892-4423 NR 60 TC 40 Z9 40 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD MAY PY 2002 VL 140 IS 1 BP 51 EP 66 DI 10.1086/339134 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541XU UT WOS:000175012500005 ER PT J AU Lemoine, M Vidal-Madjar, A Hebrard, G Desert, JM Ferlet, R Des Etangs, AL Howk, JC Andre, M Blair, WP Friedman, SD Kruk, JW Lacour, S Moos, HW Sembach, K Chayer, P Jenkins, EB Koester, D Linsky, JL Wood, BE Oegerle, WR Sonneborn, G York, DG AF Lemoine, M Vidal-Madjar, A Hebrard, G Desert, JM Ferlet, R Des Etangs, AL Howk, JC Andre, M Blair, WP Friedman, SD Kruk, JW Lacour, S Moos, HW Sembach, K Chayer, P Jenkins, EB Koester, D Linsky, JL Wood, BE Oegerle, WR Sonneborn, G York, DG TI Deuterium abundance toward G191-B2B: Results from the FUSE mission SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE ISM : abundances; ISM : clouds; stars : individual (G191-B2B); ultraviolet : ISM ID TELESCOPE IMAGING SPECTROGRAPH; LOCAL INTERSTELLAR-MEDIUM; BIG-BANG NUCLEOSYNTHESIS; STARK-BROADENING TABLES; WHITE-DWARF HZ43; GALACTIC EVOLUTION; SPATIAL VARIATIONS; GHRS OBSERVATIONS; D/H RATIO; HST-GHRS AB High-resolution spectra of the hot white dwarf G191-B2B, covering the wavelength region 905 1187 A, were obtained with the Far Ultraviolet Spectroscopic Explorer ( FUSE). These data were used in conjunction with existing high-resolution Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) observations to evaluate the total H I, D I, O I and N I column densities along the line of sight. Previous determinations of N (D I) based upon GHRS and STIS observations were controversial as a result of the saturated strength of the D I Lyalpha line. In the present analysis the column density of D I has been measured using only the unsaturated Lybeta and Lygamma lines observed by FUSE. A careful inspection of possible systematic uncertainties tied to the modeling of the stellar continuum or to the uncertainties in the FUSE instrumental characteristics has been performed. The column densities derived are log N (D I) = 13.40 +/- 0.07, log N(O I) = 14.86 +/- 0.07, and log N(N I) = 13.87 +/- 0.07, quoted with 2 sigma uncertainties. The measurement of the H I column density by pro le fitting of the Lyalpha line has been found to be uncertain. If additional weak, hot interstellar components are added to the three detected clouds along the line of sight, the H I column density can be reduced quite significantly, even though the signal-to-noise ratio and spectral resolution at Lyalpha are excellent. The new estimate of N (H I) toward G191-B2B reads log N(H I) = 18.18 +/- 0.18 (2 sigma), so that the average D/H ratio on the line of sight is D/H = 1.66(-0.6)(+0.9))x 10(-5) (2 sigma). C1 CNRS, Inst Astrophys Paris, F-75014 Paris, France. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. Princeton Univ Observ, Princeton, NJ 08544 USA. Univ Kiel, Inst Theoret Phys & Astrophys, D-24098 Kiel, Germany. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Boulder, CO 80309 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Lemoine, M (reprint author), CNRS, Inst Astrophys Paris, 98 Bis Blvd Arago, F-75014 Paris, France. RI Oegerle, William/C-9070-2012; Sonneborn, George/D-5255-2012; Kruk, Jeffrey/G-4047-2012; Howk, Jay/D-2577-2013; Jenkins, Edward/P-5684-2014; OI Jenkins, Edward/0000-0003-1892-4423; Howk, J. Christopher/0000-0002-2591-3792 NR 62 TC 75 Z9 75 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD MAY PY 2002 VL 140 IS 1 BP 67 EP 80 DI 10.1086/339128 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541XU UT WOS:000175012500006 ER PT J AU Hebrard, G Lemoine, M Vidal-Madjar, A Desert, JM Des Etangs, AL Ferlet, R Wood, BE Linsky, JL Kruk, JW Chayer, P Lacour, S Blair, WP Friedman, SD Moos, HW Sembach, KR Sonneborn, G Oegerle, WR Jenkins, EB AF Hebrard, G Lemoine, M Vidal-Madjar, A Desert, JM Des Etangs, AL Ferlet, R Wood, BE Linsky, JL Kruk, JW Chayer, P Lacour, S Blair, WP Friedman, SD Moos, HW Sembach, KR Sonneborn, G Oegerle, WR Jenkins, EB TI Deuterium abundance toward WD 2211-495: Results from the FUSE mission SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE cosmology : observations; ISM : abundances; ISM : clouds; stars : individual (WD 2211-495); ultraviolet : ISM; white dwarfs ID DA WHITE-DWARFS; ALL-SKY SURVEY; ABSORPTION PROFILE SPECTROGRAPH; LOCAL INTERSTELLAR-MEDIUM; EUV-SELECTED SAMPLE; SEQUENCE-B-STARS; GALACTIC EVOLUTION; ELEMENT ABUNDANCES; CHEMICAL EVOLUTION; SOLAR NEIGHBORHOOD AB We present a deuterium abundance analysis of the line of sight toward the white dwarf WD 2211-495 observed with the Far Ultraviolet Spectroscopic Explorer (FUSE). Numerous interstellar lines are detected on the continuum of the stellar spectrum. A thorough analysis was performed through the simultaneous fit of interstellar absorption lines detected in the four FUSE channels of multiple observations with different slits. We excluded all saturated lines in order to reduce possible systematic errors on the column density measurements. We report the determination of the average interstellar D/O and D/N ratios along this line of sight at the 95% confidence level: D/O = (4.0 +/- 1.2) x 10(-2) and D/N = (4.4 +/- 1.3) x 10(-1). In conjunction with FUSE observations of other nearby sight lines, the results of this study will allow a deeper understanding of the present-day abundance of deuterium in the local interstellar medium and its evolution with time. C1 Inst Astrophys, F-75014 Paris, France. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Boulder, CO 80309 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Princeton Univ Observ, Princeton, NJ 08544 USA. RP Hebrard, G (reprint author), Inst Astrophys, 98 Bis Blvd Arago, F-75014 Paris, France. RI Oegerle, William/C-9070-2012; Sonneborn, George/D-5255-2012; Kruk, Jeffrey/G-4047-2012; Jenkins, Edward/P-5684-2014 OI Jenkins, Edward/0000-0003-1892-4423 NR 70 TC 83 Z9 83 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD MAY PY 2002 VL 140 IS 1 BP 103 EP 114 DI 10.1086/339130 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541XU UT WOS:000175012500009 ER PT J AU McGinnis, PJ AF McGinnis, PJ TI The scope and direction of health informatics SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Editorial Material DE electronic medical record; medical informatics; health informatics; telemedicine; eHealth ID MEDICAL INFORMATICS AB Health Informatics (HI) is a dynamic discipline based on the medical sciences, information sciences, and cognitive sciences. Its domain can broadly be defined as medical information management. The purpose of this paper is to provide an overview of this domain, discuss the current "state of the art," and indicate the likely growth areas for health informatics. The sources of information used in this paper are selected publications from the literature of Health Informatics, HI 5300: Introduction to Health Informatics, which is a course from the Department of Health Informatics at the University of Texas Houston Health Sciences Center, and the author's personal experience in practicing telemedicine and implementing an electronic medical record at the NASA-Johnson Space Center. The conclusion is that the direction of Health Informatics is in the direction of data management, transfer, and representation via electronic medical records and the Internet. C1 NASA, Lyndon B Johnson Space Ctr, Med Operat Branch, Houston, TX 77058 USA. Univ Texas, Hlth Sci Ctr, Sch Hlth Informat Sci, Dept Hlth Informat, Houston, TX USA. RP McGinnis, PJ (reprint author), NASA, Lyndon B Johnson Space Ctr, Med Operat Branch, Mail Code SD-26, Houston, TX 77058 USA. NR 15 TC 2 Z9 2 U1 2 U2 2 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD MAY PY 2002 VL 73 IS 5 BP 503 EP 507 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 545KR UT WOS:000175216800014 PM 12014613 ER PT J AU Proctor, RW Lien, MC Vu, KPL Schultz, EE Salvendy, G AF Proctor, RW Lien, MC Vu, KPL Schultz, EE Salvendy, G TI Improving computer security for authentication of users: Influence of proactive password restrictions SO BEHAVIOR RESEARCH METHODS INSTRUMENTS & COMPUTERS LA English DT Article; Proceedings Paper CT 31st Annual Meeting of the Society-for-Computers-in-psychology (SCiP) CY NOV 14, 2001 CL ORLANDO, FLORIDA SP Soc Comp Psychol ID MEMORY AB Entering a username-password combination is a widely used procedure for identification and authentication in computer systems. However, it is a notoriously weak method, in that the passwords adopted by many users are easy to crack. In an attempt to improve security, proactive password checking may be used, in which passwords must meet several criteria to be more resistant to cracking. In two experiments, we examined the influence of proactive password restrictions on the time that it took to generate an acceptable password and to use it subsequently to log in. The required length was a minimum of five characters in Experiment 1 and eight characters in Experiment 2. In both experiments, one condition had only the length restriction, and the other had additional restrictions. The additional restrictions greatly increased the time it took to generate the password but had only a small effect on the time it took to use it subsequently to log in. For the five-character passwords, 75% were cracked when no other restrictions were imposed, and this was reduced to 33% with the additional restrictions. For the eight-character passwords, 17% were cracked with no other restrictions, and 12.5% with restrictions. The results indicate that increasing the minimum character length reduces crackability and increases security, regardless of whether additional restrictions are imposed. C1 Purdue Univ, Dept Psychol Sci, W Lafayette, IN 47907 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Berkeley, Berkeley, CA 94720 USA. Tsing Hua Univ, Beijing 100084, Peoples R China. RP Proctor, RW (reprint author), Purdue Univ, Dept Psychol Sci, W Lafayette, IN 47907 USA. NR 13 TC 28 Z9 28 U1 2 U2 6 PU PSYCHONOMIC SOC INC PI AUSTIN PA 1710 FORTVIEW RD, AUSTIN, TX 78704 USA SN 0743-3808 J9 BEHAV RES METH INS C JI Behav. Res. Methods Instr. Comput. PD MAY PY 2002 VL 34 IS 2 BP 163 EP 169 DI 10.3758/BF03195438 PG 7 WC Psychology, Mathematical; Psychology, Experimental SC Psychology GA 568AL UT WOS:000176520200005 PM 12109007 ER PT J AU Owen, S Anderson, G Agnew, DC Johnson, H Hurst, K Reilinger, R Shen, ZK Svarc, J Baker, T AF Owen, S Anderson, G Agnew, DC Johnson, H Hurst, K Reilinger, R Shen, ZK Svarc, J Baker, T TI Early postseismic deformation from the 16 October 1999 M-w 7.1 Hector Mine, California, earthquake as measured by survey-mode GPS SO BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA LA English DT Article ID LANDERS EARTHQUAKE; HALF-SPACE; FAULTS; SHEAR; ZONE; SLIP AB The 16 October 1999 (M-w 7.1) Hector Mine earthquake was the largest earthquake in California since the 1992 (M-w 7.3) Landers event. The Hector Mine earthquake occurred in the eastern Mojave Desert, where the density of permanent Global Positioning System (GPS) stations is relatively low. Since the earthquake, groups from the United States Geological Survey, University of Southern California, University of California, Los Angeles, University of California, San Diego, and Massachusetts Institute of Technology have made postseismic survey-mode observations to increase the spatial coverage of deformation measurements. A total of 55 sites were surveyed, with markers from a few meters to 100 km from the surface rupture. We present velocity estimates for the 32 sites that had enough repeated observations between 17 October 1999 and 26 March 2000 to provide reliable results; these survey-mode data complement the temporal and spatial coverage provided by newly installed Southern California Integrated Geodetic Network permanent GPS stations and future Interferometric Synthetic Aperture Radar postseismic results. We then use the postseismic velocity estimates to compute a simple afterslip model. Results of inversions show that the observed velocities are consistent with deep afterslip occuring underneath the coseismic rupture area. C1 Univ So Calif, Dept Earth Sci, Los Angeles, CA USA. Univ Calif San Diego, Inst Geophys & Planetary Phys, La Jolla, CA 92093 USA. Jet Prop Lab, Pasadena, CA USA. MIT, Earth Resources Lab, Cambridge, MA 02139 USA. Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA. US Geol Survey, Menlo Pk, CA 94025 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. Predict Co, Santa Fe, NM USA. RP Owen, S (reprint author), Univ So Calif, Dept Earth Sci, Los Angeles, CA USA. NR 21 TC 31 Z9 33 U1 0 U2 6 PU SEISMOLOGICAL SOC AMER PI EL CERRITO PA PLAZA PROFESSIONAL BLDG, SUITE 201, EL CERRITO, CA 94530 USA SN 0037-1106 J9 B SEISMOL SOC AM JI Bull. Seismol. Soc. Amer. PD MAY PY 2002 VL 92 IS 4 BP 1423 EP 1432 DI 10.1785/0120000930 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 576QN UT WOS:000177016500021 ER PT J AU Hurst, TP Conover, DO AF Hurst, TP Conover, DO TI Effects of temperature and salinity on survival of young-of-the-year Hudson River striped bass (Morone saxatilis): implications for optimal overwintering habitats SO CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES LA English DT Article ID DIFFERENT LATITUDES; GROWTH-PERFORMANCE; ESTUARINE; RECRUITMENT; TOLERANCE; FISH AB We examined the role of salinity, body size, and energetic state in determining low temperature tolerance of young-of-the-year (YOY) striped bass (Morone saxatilis) and used this information to map optimal overwintering habitat in the Hudson River estuary. A long-term experiment compared survival at 15 ppt and 30 ppt. In additional experiments, winter-acclimated fish were exposed to temperature declines (2.3degreesC.day(-1) to 1degreesC.week(-1)) at salinities from 0 ppt to 35 ppt. Highest survival at low temperatures was consistently observed at intermediate salinities. These results suggest that the observed distribution of overwintering striped bass is related to physiological constraints on osmoregulatory ability at low temperatures. Low temperature tolerance appeared unrelated to body size and energetic state. Salinity profiles were used to describe the location and extent of optimal wintering habitats under various hydrographic regimes. The location of optimal habitats was displaced by over 27 km along the river axis because of variation in salinity regime. Changes in the availability of optimal habitat may be responsible for variation in recruitment to the Hudson River population. These results demonstrate the need to consider a holistic approach encompassing all seasons of the year in assessing habitat requirements of fishes. C1 SUNY Stony Brook, Marine Sci Res Ctr, Stony Brook, NY 11794 USA. RP Hurst, TP (reprint author), NOAA, Hatfield Marine Sci Ctr, Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Newport, OR 97365 USA. RI Hurst, Thomas/N-1401-2013 NR 38 TC 35 Z9 36 U1 3 U2 7 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 MAY PY 2002 VL 59 IS 5 BP 787 EP 795 DI 10.1139/F02-051 PG 9 WC Fisheries; Marine & Freshwater Biology SC Fisheries; Marine & Freshwater Biology GA 583FC UT WOS:000177395100005 ER PT J AU Amorim, MCP McCracken, ML Fine, ML AF Amorim, MCP McCracken, ML Fine, ML TI Metabolic costs of sound production in the oyster toadfish, Opsanus tau SO CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE LA English DT Article ID SONIC NEUROMUSCULAR SYSTEM; ACOUSTIC COMMUNICATION; OXYGEN-CONSUMPTION; ENERGETIC COSTS; TELEOST FISH; MUSCLE; BEHAVIOR; CONTRACTIONS; SWIMBLADDER; GENERATION AB The energetics of mate calling has been studied in insects, frogs, birds, and mammals, but not in fishes. The oyster toadfish, Opsanus tau, produces a boatwhistle advertisement call using one of the fastest muscles known in vertebrates. Because toadfish will not boatwhistle in a respirometer, we measured oxygen consumption after eliciting sound production by electrically stimulating the sonic swim bladder muscle nerve. Induced sounds were similar to a male calling at a rapid rate. Stimulation of the sonic nerve increased the respiration rate by 40-60% in males, but they became agitated. Repeating the experiment decreased agitation, and in most fish respiration rates approximated control levels by the second or third replication. Elicited sounds and therefore sonic-muscle performance were similar in all repetitions, hence it appears that the increased oxygen consumption in the first trial was caused by the fish's agitation. Controls indicated that electrode implantation and electrical stimulation of the body cavity did not affect the respiration rate. We suggest that allocation of a small amount of the total energy budget to sound production is reasonable in toadfish, and probably most other fish species, because of the small amount of time that the sonic muscles actually contract and their small size (about 1% of body mass). C1 Inst Super Psicol Aplicada, Unidade Invest Ecoetol, P-1149041 Lisbon, Portugal. Natl Marine Fisheries Serv, Honolulu Lab, Honolulu, HI 96822 USA. Virginia Commonwealth Univ, Dept Biol, Richmond, VA 23284 USA. RP Amorim, MCP (reprint author), Inst Super Psicol Aplicada, Unidade Invest Ecoetol, Rua Jardim Tabaco 34, P-1149041 Lisbon, Portugal. RI Amorim, Maria Clara/K-1889-2012 OI Amorim, Maria Clara/0000-0002-2453-6999 NR 43 TC 26 Z9 28 U1 0 U2 3 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA, ONTARIO K1A 0R6, CANADA SN 0008-4301 J9 CAN J ZOOL JI Can. J. Zool.-Rev. Can. Zool. PD MAY PY 2002 VL 80 IS 5 BP 830 EP 838 DI 10.1139/Z02-054 PG 9 WC Zoology SC Zoology GA 566GU UT WOS:000176419200005 ER PT J AU Kiris, C Kwak, D AF Kiris, C Kwak, D TI Aspects of unsteady incompressible flow simulations SO COMPUTERS & FLUIDS LA English DT Article ID NAVIER-STOKES EQUATIONS; SCHEMES AB Since unsteady incompressible flow simulations involving complex geometry require long computing times, it is crucial to select computationally efficient solvers. For this purpose, two numerical procedures, one based on artificial compressibility and the other pressure projection method, are investigated for obtaining time-accurate solutions of the incompressible Navier-Stokes equations. The performance of the two methods is compared by obtaining unsteady solutions for the evolution of twin vortices behind a flat plate. Calculated results are compared with experimental and other numerical results. For an unsteady flow, which requires small physical time step, the pressure projection method was found to be computationally efficient since it does not require a subiteration procedure. It was also observed that the artificial compressibility method requires a fast convergence scheme at each physical time step in order to satisfy the incompressibility condition. This was obtained by employing a GMRES-ILU(0) solver in the artificial compressibility solver. Published by Elsevier Science Ltd. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kiris, C (reprint author), NASA, Ames Res Ctr, Mail Stop T27B-1, Moffett Field, CA 94035 USA. NR 16 TC 15 Z9 16 U1 0 U2 0 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 MAY-SEP PY 2002 VL 31 IS 4-7 BP 627 EP 638 AR PII S0045-7930(01)00076-7 DI 10.1016/S0045-7930(01)00076-7 PG 12 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA 533JJ UT WOS:000174525900016 ER PT J AU Rubin, SG Celestina, ML Srinivasan, K AF Rubin, SG Celestina, ML Srinivasan, K TI Adaptive and fixed segmented domain decomposition multigrid procedures for internal viscous flows SO COMPUTERS & FLUIDS LA English DT Article AB A segmented domain decomposition multigrid procedure is reviewed. The methodology is outlined for both an adaptive formulation applied primarily to inlet, nozzle and duct flows, and for a fixed, predetermined, subdomain Formulation applied for turbomachinery geometries. The procedure has been considered for both low and high speed flows in two- and three-dimensions, and for laminar and turbulent-model applications. With these procedures., the grids remain uniform in each subdomain; although the global grid appears to be highly stretched. This formulation allows for computations with a high degree of accuracy and grid independence at reasonable computer cost. This is generally not possible to replicate with full domain multigrid procedures on stretched grids with large cell aspect ratio. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Univ Cincinnati, ASE EM, Cincinnati, OH 45221 USA. AP Solut Inc, NASA Glenn Res Ctr, Cleveland, OH 44135 USA. DaimlerChrysler Corp, Auburn Hills, MI 48326 USA. RP Rubin, SG (reprint author), Univ Cincinnati, ASE EM, POB 210070, Cincinnati, OH 45221 USA. NR 10 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 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD MAY-SEP PY 2002 VL 31 IS 4-7 BP 787 EP 813 AR PII S0045-7930(01)00080-9 DI 10.1016/S0045-7930(01)00080-9 PG 27 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA 533JJ UT WOS:000174525900025 ER PT J AU De Chant, LJ Seidel, JA AF De Chant, LJ Seidel, JA TI Multiple stream superposition of a two-stream combined analytical numerical initial value problem solver for aerodynamic mixing SO COMPUTERS & MATHEMATICS WITH APPLICATIONS LA English DT Article DE multiple stream superposition; combined analytical/numerical method; aerodynamic mixing; ejector nozzle AB In spite of the rapid advances in both scalar and parallel computational flow simulation tools, the large number and breadth of variables involved in both design and inverse problems make the use of complex fluid flow models impractical. With this restriction, it may be concluded that an important family of methods for mathematical/computational development are reduced or approximate models. An approximate model for two stream mix problems utilizing a combined perturbation/numerical modelling methodology has been developed [1]. The numerical portion of the model uses a compact finite difference scheme, while analytical solutions are used to resolve singular behavior that is inherent to this flow. Approximate representation of the flow in terms of Rux variables yields a linear transport operator, thus facilitating the additive decomposition of the solution into numerical and analytical portions. Additionally, linearity permits superposition of the basic two-stream initial value problem to construct multiple stream mixing problems. Multiple stream results are presented to illustrate the efficiency of this methodology. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Analyt Entrainment LLC, Albuquerque, NM 87112 USA. NASA, Glenn Res Ctr, Propuls Syst Anal Off, Cleveland, OH 44135 USA. RP De Chant, LJ (reprint author), Analyt Entrainment LLC, 1541 Summit Hills Dr, Albuquerque, NM 87112 USA. NR 26 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0898-1221 J9 COMPUT MATH APPL JI Comput. Math. Appl. PD MAY-JUN PY 2002 VL 43 IS 10-11 BP 1451 EP 1468 AR PII S0898-1221(02)00111-6 DI 10.1016/S0898-1221(02)00111-6 PG 18 WC Computer Science, Interdisciplinary Applications; Mathematics, Applied SC Computer Science; Mathematics GA 546TQ UT WOS:000175290800020 ER PT J AU Kincaid, RK Padula, SL AF Kincaid, RK Padula, SL TI D-optimal designs for sensor and actuator locations SO COMPUTERS & OPERATIONS RESEARCH LA English DT Article DE location; D-optimal; tabu search; heuristics ID ORBIT MODAL IDENTIFICATION; SPACE STRUCTURES; PLACEMENT; SEARCH; ALGORITHM AB Active control of noise and vibration is now possible in automobiles, aircraft, and many other devices. Where to place actuators, to control noise and vibration, and sensors, to measure the performance of the actuators, is a central question. Given a truss structure, we seek the k most effective locations to control and/or sense vibrations. A discrete D-optimal design has been proposed as a solution to this location problem. We develop a simple static tabu search and test its performance on an 80 node truss structure built at NASA-Langley Research Center. We show that our tabu search approach dominates the traditional approaches to finding D-optimal designs. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Coll William & Mary, Dept Math, Williamsburg, VA 23187 USA. NASA, Langley Res Ctr, Multidisplinary Optimizat Branch, Hampton, VA 23681 USA. RP Kincaid, RK (reprint author), Coll William & Mary, Dept Math, Williamsburg, VA 23187 USA. NR 24 TC 17 Z9 21 U1 0 U2 6 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0305-0548 J9 COMPUT OPER RES JI Comput. Oper. Res. PD MAY PY 2002 VL 29 IS 6 BP 701 EP 713 DI 10.1016/S0305-0548(01)00048-X PG 13 WC Computer Science, Interdisciplinary Applications; Engineering, Industrial; Operations Research & Management Science SC Computer Science; Engineering; Operations Research & Management Science GA 517BM UT WOS:000173591300012 ER PT J AU Ciszak, E Hammons, AS Hong, YS AF Ciszak, E Hammons, AS Hong, YS TI Use of capillaries for macromolecular crystallization in a cryogenic dewar SO CRYSTAL GROWTH & DESIGN LA English DT Article ID CRYSTALS AB The enhanced gaseous nitrogen (EGN) dewar is a cryogenic dry shipper with a sealed cylinder inserted inside along with a temperature-monitoring device, and is intended for macromolecular crystallization experiments on the International Space Station. Within the dewar, each crystallization experiment is contained as a solution within a plastic capillary tube. The standard procedure for loading samples in these tubes has involved rapid freezing of the precipitant and biomolecular solution, e.g., protein, directly in liquid nitrogen; this method, however, often resulted in uncontrolled formation of air voids. These air pockets, or bubbles, can lead to irreproducible crystallization results. A novel protocol has been developed to prevent formation of bubbles, and this has been tested in the laboratory as well as aboard the International Space Station during a 42-day long mission of July/August 2001. The gain or loss of mass from solutions within the plastic capillaries revealed that mass transport occurred among separated tubes, and that this mass transport was dependent upon the hygroscopic character of the solution contained in any given tube. The surface area of the plastic capillary tube also related to the observed mass transport. Furthermore, the decreased mass of solutions of protein correlated to observed formation of protein crystals. C1 NASA, George C Marshall Space Flight Ctr, Biophys & Space Res Lab, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35805 USA. RP Ciszak, E (reprint author), NASA, George C Marshall Space Flight Ctr, Biophys & Space Res Lab, Mail Code SD46, Huntsville, AL 35812 USA. NR 6 TC 7 Z9 7 U1 0 U2 5 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1528-7483 J9 CRYST GROWTH DES JI Cryst. Growth Des. PD MAY-JUN PY 2002 VL 2 IS 3 BP 235 EP 238 DI 10.1021/cg0155671 PG 4 WC Chemistry, Multidisciplinary; Crystallography; Materials Science, Multidisciplinary SC Chemistry; Crystallography; Materials Science GA 548GD UT WOS:000175379500011 ER PT J AU Rashed, H Cutts, T Abell, T Cowings, P Toscano, W El-Gammal, A Adl, D AF Rashed, H Cutts, T Abell, T Cowings, P Toscano, W El-Gammal, A Adl, D TI Predictors of response to a behavioral treatment in patients with chronic gastric motility disorders SO DIGESTIVE DISEASES AND SCIENCES LA English DT Article DE gastrointestinal dysmotility; biofeedback; behavioral; autonomic; outcome; autogenic ID IRRITABLE-BOWEL-SYNDROME; DIABETIC GASTROPARESIS; DOMPERIDONE; SYMPTOMS; BIOFEEDBACK; THERAPY; MANAGEMENT; CISAPRIDE; DYSPEPSIA; EFFICACY AB Chronic gastric motility disorders have proven intractable to most traditional therapies. Twenty-six patients with chronic nausea and vomiting were treated with a behavioral technique, autonomic training (AT) with directed imagery (verbal instructions), to help facilitate physiological control. After treatment, gastrointestinal symptoms decreased by >30% in 58% of the treated patients. We compared those improved patients to the 43% who did not improve significantly. No significant differences existed in baseline symptoms and autonomic measures between both groups. However, baseline measures of gastric emptying and autonomic function predicted treatment outcome. Patients who improved manifested mild to moderate delay in baseline gastric emptying measures. The percent of liquid gastric emptying at 60 mins and the sympathetic adrenergic measure of percent of change in the foot cutaneous blood flow in response to cold stress test predicted improvement in AT outcome, with clinical diagnostic values of 77% and 71%,, respectively. We conclude that AT treatment can be efficacious in some patients with impaired gastric emptying and adrenergic dysfunction. More work is warranted to compare biofeedback therapy with gastric motility patients and controls in population-based studies. C1 Univ Tennessee, Coll Med, Dept Neurol, Memphis, TN 38163 USA. Univ Tennessee, Coll Med, Dept Med, Memphis, TN 38163 USA. Univ Tennessee, Coll Med, Dept Psychiat, Memphis, TN 38163 USA. Univ Arkansas Med Sci, Little Rock, AR 72205 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. E Tennessee Univ, Dept Surg, Johnson City, TN 37614 USA. RP Rashed, H (reprint author), Univ Tennessee, Coll Med, Dept Neurol, 855 Monroe Ave,Room 412, Memphis, TN 38163 USA. NR 28 TC 17 Z9 17 U1 2 U2 3 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0163-2116 J9 DIGEST DIS SCI JI Dig. Dis. Sci. PD MAY PY 2002 VL 47 IS 5 BP 1020 EP 1026 AR UNSP 0163-2116/02/0500-1020/0 DI 10.1023/A:1015029805498 PG 7 WC Gastroenterology & Hepatology SC Gastroenterology & Hepatology GA 550KE UT WOS:000175501500012 PM 12018897 ER PT J AU Toporski, JKW Steele, A Westall, F Avci, R Martill, DM McKay, DS AF Toporski, JKW Steele, A Westall, F Avci, R Martill, DM McKay, DS TI Morphologic and spectral investigation of exceptionally well-preserved bacterial biofilms from the Oligocene Enspel formation, Germany SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Review ID IN-SITU SILICIFICATION; ION MASS-SPECTROMETRY; TOF-SIMS ANALYSIS; NEOPROTEROZOIC ACRITARCHS; FUNCTIONAL-GROUPS; FOSSIL BACTERIA; MICROBIAL MATS; SOFT-TISSUES; SEDIMENTS; MINERALIZATION AB The fossilised soft tissues of a tadpole and an associated coprolitic structure from the organic-rich volcanoclastic lacustrine Upper Oligocene Enspel sediments (Germany) were investigated using high-resolution imaging techniques and nondestructive in situ surface analysis. Total organic carbon analysis of the coprolite and the sediment revealed values of 28.9 and 8.9% respectively. The soft tissues from the tadpole and the coprolite were found to be composed of 0.5 to 1 mum-sized spheres and rod shapes. These features are interpreted as the fossil remains of bacterial biofilms consisting probably of heterotrophic bacteria and fossilised extracellular polymeric substances. They became fossilised while in the process of degrading the organic matter of the organism and the coprolite. Comparison with a modem marine biofilm revealed morphologic details identical to those observed in the fossil bacterial biofilms. Although the fossil biofilms on both macrofossils exhibited identical microtextures, their mode of preservation was inhomogeneous and varied between calcium phosphate and an as yet unidentified mineral phase consisting mainly of Si, Ca, Ti, P, and S, but also showing the presence of Mg, Al, and Fe. The coprolite consists purely of fossilised bacterial cells in a densely packed arrangement and associated fossilised extracellular polymeric substances. In addition to preliminary imaging and energy-dispersive X-ray analysis, both the fossil biofilms and the sediment were investigated by nondestructive in situ analysis using time of flight-secondary ion mass spectroscopy (ToF-SIMS). The mass spectra obtained on the coprolite in mass-resolved chemical mapping mode allowed the tentative identification of a number of organic secondary ion species. Some spectra appear to indicate the presence of bacterial hopanoids, but further work using standard techniques such as gas chromatography mass spectroscopy is needed to conclusively verify the presence of these substances. Nevertheless, ToF-SIMS chemical maps were successfully correlated with electron microscopy images, allowing the correlation of molecular spectra, the spatial distribution of individual organic species, and specific morphologic features to demonstrate the potential of this approach in the analysis of microfossils. Copyright (C) 2002 Elsevier Science Ltd. C1 Univ Portsmouth, Sch Earth & Environm Sci, Astrobiol Grp, Portsmouth PO1 3QL, Hants, England. Carnegie Inst Washington, Geophys Lab, Washington, DC 20015 USA. NASA, Lyndon B Johnson Space Ctr, Astrobiol Grp, Houston, TX 77058 USA. Lunar & Planetary Inst, Houston, TX 77058 USA. Montana State Univ, Dept Phys, ICAL, Bozeman, MT 59717 USA. RP Toporski, JKW (reprint author), Univ Portsmouth, Sch Earth & Environm Sci, Astrobiol Grp, Burnaby Bldg,Burnaby Rd, Portsmouth PO1 3QL, Hants, England. NR 117 TC 70 Z9 75 U1 4 U2 21 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 MAY PY 2002 VL 66 IS 10 BP 1773 EP 1791 AR PII S0016-7037(01)00870-5 DI 10.1016/S0016-7037(01)00870-5 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 551TF UT WOS:000175577200007 ER PT J AU Xirouchakis, D Draper, DS Schwandt, CS Lanzirotti, A AF Xirouchakis, D Draper, DS Schwandt, CS Lanzirotti, A TI Crystallization conditions of Los Angeles, a basaltic Martian meteorite SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID FE-TI OXIDES; OXYGEN FUGACITY; EQUILIBRIA; SHERGOTTITE; PYROXENES; OLIVINE; QUARTZ; PRESSURES; PETROLOGY; SYSTEMS AB The texture of Los Angeles (stone 1) is dominated by relatively large (0.5-2.0 mm) anhedral to subhedral grains of pyroxene, and generally subhedral to euhedral shocked plagioclase feldspar (maskelynite). Minor phases include subhedral titanomagnetite and ilmenite, Fe-rich olivine, olivine+augite-dominated symplectites [some of which include a Si-rich phase and some which do not], pyrrhotite, phosphate(s), and an impact shock-related alkali- and silica-rich glass closely associated with anhedral to euhedral silica grains. Observations and model calculations indicate that the initial crystallization of Mg-rich pigeonitic pyroxenes at less than or equal to1150 degreesC, probably concomitantly with plagioclase, was followed by pigeonitic and augitic compositions between 1100 and 1050 degreesC whereas between 1050 and 920 to 905 degreesC pyroxene of single composition crystallized. Below 920 to 905 degreesC, single composition Fe-rich clinopyroxene exsolved to augite and pigeonite. Initial appearance of titanomagnetite probably occurred near 990 degreesC and FMQ-1.5 whereas at and below 990 degreesC and greater than or equal toFMQ-1.5 titanomagnetite and single composition Fe-rich clinopyroxene may have started to react, producing ilmenite and olivine. However, judging from the most common titanomagnetite compositions, we infer that most of this reaction likely occurred between 950 and 900 degreesC at FMQ-1.0 +/- 0.2 and nearly simultaneously with pyroxene exsolution, thus producing assemblages of pigeonite, titanomagnetite, olivine, ilmenite, and augite. We deem this reaction as the most plausible explanation for the formation of the olivine+augite-dominated symplectites in Los Angeles. But we cannot preclude possible contributions to the symplectites from the shock-related alkali- and silica-rich glass or shocked plagioclase, and the breakdown of Fe-rich pigeonite compositions to olivine+augite+silica below 900 degreesC. Reactions between Fe-Ti oxides and silicate minerals in Los Angeles and other similar basaltic Martian meteorites can control the T-fO(2) equilibration path during cooling, which may better explain the relative differences in fO(2) among the basaltic Martian meteorites. Copyright (C) 2002 Elsevier Science Ltd. C1 NASA JSC, Off Astromat Res, Houston, TX 77058 USA. Texas So Univ, Dept Chem, Houston, TX 77004 USA. Lockheed Martin, Houston, TX 77058 USA. Univ Chicago, Brookhaven Natl Lab, Consortium Adv Radiat Sources, Upton, NY 11973 USA. RP Xirouchakis, D (reprint author), NASA JSC, Off Astromat Res, Mail Code SA13, Houston, TX 77058 USA. NR 47 TC 40 Z9 40 U1 1 U2 6 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 MAY PY 2002 VL 66 IS 10 BP 1867 EP 1880 AR PII S0016-7037(01)00892-4 DI 10.1016/S0016-7037(01)00892-4 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 551TF UT WOS:000175577200013 ER PT J AU Campbell, KA Farmer, JD Des Marais, D AF Campbell, KA Farmer, JD Des Marais, D TI Ancient hydrocarbon seeps from the Mesozoic convergent margin of California: carbonate geochemistry, fluids and palaeoenvironments SO GEOFLUIDS LA English DT Review DE ancient hydrocarbon seeps; California Mesozoic; carbonate geochemistry; carbonate paragenesis; stable isotopes ID METHANE-DERIVED CARBONATES; OREGON SUBDUCTION ZONE; GREAT VALLEY SEQUENCE; GULF-OF-MEXICO; FORE-ARC BASIN; AUTHIGENIC CARBONATES; CONTINENTAL-SLOPE; ACCRETIONARY PRISM; HYDROTHERMAL-VENT; PYRITE FORMATION AB More than a dozen hydrocarbon seep-carbonate occurrences in late Jurassic to late Cretaceous forearc and accretionary prism strata, western California, accumulated in turbidite/fault-hosted or serpentine diapir-related settings. Three sites, Paskenta, Cold Fork of Cottonwood Creek and Wilbur Springs, were analyzed for their petrographic, geochemical and palaeoecological attributes, and each showed a three-stage development that recorded the evolution of fluids. through reducing-oxidizing-reducing conditions. The first stage constituted diffusive, reduced fluid seepage (CH4, H2S) through seafloor sediments, as indicated by Fe-rich cletrital micrite, corroded surfaces encrusted with framboidal pyrite, anhedral yellow calcite and negative cement stable isotopic signatures (delta(13)C as low as -35.5parts per thousand PDB; delta(18)O as low as -10.8parts per thousand. PDB). Mega-invertebrates, adapted to reduced conditions and/or bacterial chemosymbiosis, colonized the sites during this earliest period of fluid seepage. A second, early stage of centralized venting at the seafloor followed, which was coincident with hydrocarbon migration, as evidenced by nonluminescent fibrous cements with delta(13)C values as low as -43.7%. PDB, elevated delta(18)O (up to +2.3%. PDB), petroleum inclusions, marine borings and lack of pyrite. Throughout these early phases of hydrocarbon seepage, microbial sediments were preserved as layered and clotted, nondetrital micrites. A final late-stage of development marked a return to reducing conditions during burial diagenesis, as implied by pore-associated Mn-rich cement phases with bright cathodoluminescent patterns, and negative delta(18)O signatures (as low as -14parts per thousand PDB). These recurring patterns among sites highlight similarities in the hydrogeological evolution of the Mesozoic convergent margin of California, which influenced local geochemical conditions and organism responses. A comparison of stable carbon and oxygen isotopic data for 33 globally distributed seep-carbonates, ranging in age from Devonian to Recent, delineated three groupings that reflect variable fluid input, different tectono-sedimentary regimes and time-temperature-dependent burial diagenesis. C1 Univ Auckland, Dept Geol, Auckland 1, New Zealand. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Campbell, KA (reprint author), Univ Auckland, Dept Geol, Private Bag 92019, Auckland 1, New Zealand. OI Campbell, Kathleen/0000-0002-4815-2519 NR 131 TC 172 Z9 199 U1 13 U2 65 PU BLACKWELL PUBL LTD PI OXFORD PA 108 COWLEY RD, OXFORD OX4 1JF, OXON, ENGLAND SN 1468-8115 J9 GEOFLUIDS JI Geofluids PD MAY PY 2002 VL 2 IS 2 BP 63 EP 94 DI 10.1046/j.1468-8123.2002.00022.x PG 32 WC Geochemistry & Geophysics; Geology SC Geochemistry & Geophysics; Geology GA 636GH UT WOS:000180445900002 ER PT J AU Boy, JP Gegout, P Hinderer, J AF Boy, JP Gegout, P Hinderer, J TI Reduction of surface gravity data from global atmospheric pressure loading SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE atmospheric loading; Green's function; pressure; superconducting gravimeter ID EARTH; DEFORMATION; DYNAMICS AB Besides solid Earth and ocean tides, atmospheric pressure variations are one of the major sources of surface gravity perturbations. As shown by previous studies (Merriam 1992; Mukai et al. 1995; Boy et al. 1998), the usual pressure correction with the help of local pressure measurements and the barometric admittance (a simple transfer function between pressure and gravity, both measured locally) does not allow an adequate estimation of global atmospheric loading. We express the response of the Earth to pressure forcing using a Green's function formalism (Farrell 1972). The atmosphere acts on surface gravity through two effects: first, a direct gravitational attraction by air masses which is sensitive to regional (about 1000 km around the gravimeter) pressure variations; second, an elastic process induced by the Earth's surface deformation and mass redistribution which is sensitive to large scale pressure variations (wavelengths greater than 4000 km). We estimate atmospheric loading using Green's functions and global pressure charts provided by meteorological centres. We introduce different hypotheses on the atmospheric thickness and atmospheric density variations with altitude for the modelling of the direct Newtonian attraction. All computations are compared to gravity data provided by superconducting gravimeters of the GGP (Global Geodynamics Project) network. We show the improvement by modelling global pressure versus the local estimates in terms of reduction of the variance of gravity residuals. We can also validate the inverted barometer (IB) hypothesis as the oceanic response to pressure forcing for periods exceeding one week. The non-inverted barometer (NIB) hypothesis is shown to be definitely an inadequate assumption for describing the oceanic response to atmospheric pressure at seasonal timescales. C1 EOST IPGS, UMR 7516,CNRS ULP, F-67084 Strasbourg, France. NASA, Goddard Space Flight Ctr, Space Geodesy Branch, Greenbelt, MD 20771 USA. RP EOST IPGS, UMR 7516,CNRS ULP, 5 Rue Rene Descartes, F-67084 Strasbourg, France. RI Boy, Jean-Paul/E-6677-2017 OI Boy, Jean-Paul/0000-0003-0259-209X NR 27 TC 58 Z9 63 U1 1 U2 8 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0956-540X EI 1365-246X J9 GEOPHYS J INT JI Geophys. J. Int. PD MAY PY 2002 VL 149 IS 2 BP 534 EP 545 DI 10.1046/j.1365-246X.2002.01667.x PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 549JT UT WOS:000175441300022 ER PT J AU Christensen, LE Okumura, M Sander, SP Salawitch, RJ Toon, GC Sen, B Blavier, JF Jucks, KW AF Christensen, LE Okumura, M Sander, SP Salawitch, RJ Toon, GC Sen, B Blavier, JF Jucks, KW TI Kinetics of HO2+HO2 -> H2O2+O-2: Implications for stratospheric H2O2 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TEMPERATURE-DEPENDENCE; SELF-REACTION; ATMOSPHERIC CHEMISTRY; HO2; RADICALS; O-3; PRESSURES; HO2+HO2; DO2 AB [1] The reaction HO2 + HO2 --> H2O2 + O-2 (1) has been studied at 100 Torr and 222 K to 295 K. Experiments employing photolysis of Cl-2/CH3OH/O-2/N-2 and F-2/H-2/O-2/N-2 gas mixtures to produce HO2 confirmed that methanol enhanced the observed reaction rate. At 100 Torr, zero methanol, k(1) = (8.8 +/- 0.9) 10(-13) x exp[(210 +/- 26)/T] cm(3) molecule(-1) s(-1) (2 uncertainties), which agrees with current recommendations at 295 K but is nearly 2 times slower at 231 K. The general expression for k(1), which includes the dependence on bath gas density, is k(1) = (1.5 +/- 0.2) x 10(-12) exp[(19 +/- 31)/T] + 1.7 x 10(-33) [M] x exp[1000/T], where the second term is taken from the JPL00-3 recommendation. The revised rate largely accounts for a discrepancy between modeled and measured [H2O2] in the lower to middle stratosphere. C1 CALTECH, Arthur Amos Noyes Lab Chem Phys, Div Chem & Chem Engn, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP CALTECH, Arthur Amos Noyes Lab Chem Phys, Div Chem & Chem Engn, Pasadena, CA 91125 USA. RI Salawitch, Ross/B-4605-2009; Okumura, Mitchio/I-3326-2013 OI Salawitch, Ross/0000-0001-8597-5832; Okumura, Mitchio/0000-0001-6874-1137 NR 16 TC 37 Z9 38 U1 1 U2 14 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 2002 VL 29 IS 9 AR 1299 DI 10.1029/2001GL014525 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DH UT WOS:000178888000063 ER PT J AU Farrell, WM Desch, MD AF Farrell, WM Desch, MD TI Solar proton events and the fair weather electric field at ground SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INTERPLANETARY MAGNETIC-FIELD; CIRCUIT AB [1] Previous works have demonstrated the ability of solar energetic particles to affect mesospheric electric fields. In this work, we suggest that such particles can also affect the fair-weather electric field at ground level. Our model applies previously derived changes in the high-altitude atmospheric conductivity profile to the global electric circuit. We find that the strongest flare-generated proton events are capable of creating a measurable change to the electric field at ground level (similar to5% change), but these changes are small in comparison to those associated with passing thunderstorms. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Farrell, WM (reprint author), NASA, Goddard Space Flight Ctr, Code 695, Greenbelt, MD 20771 USA. EM William.M.Farrell.1@gsfc.nasa.gov; Michael.D.Desch.1@gsfc.nasa.gov RI Farrell, William/I-4865-2013 NR 19 TC 5 Z9 6 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 2002 VL 29 IS 9 AR 1323 DI 10.1029/2001GL013908 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DH UT WOS:000178888000040 ER PT J AU Kwok, R AF Kwok, R TI Sea ice concentration estimates from satellite passive microwave radiometry and openings from SAR ice motion SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID IMAGER AB [1] Openings in the Arctic Ocean ice cover from small-scale sea ice motion fields are compared with open water fractions retrieved from satellite passive microwave observations. We find very little agreement between the results. Passive microwave retrieval algorithms seem to be insensitive to small areas of open-water in winter leads. Variability in the passive microwave retrievals is mostly due to anomalous and persistent regions of lower ice concentration where no openings are found. Between January and April of 1998, openings cover similar to0.3 +/- 0.1% of the total area within the perennial ice zone. This is smaller, in one instance ten times, than the open water fraction from the passive microwave retrievals. Previous bounds of open water coverage of the ice cover imposed on climate simulations based on uncertainties in passive microwave retrievals (+/- 4 - 7%) are too high and the overestimated open water fraction on model results should be reexamined. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kwok, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM ron.kwok@jpl.nasa.gov RI Kwok, Ron/A-9762-2008 OI Kwok, Ron/0000-0003-4051-5896 NR 12 TC 27 Z9 27 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 2002 VL 29 IS 9 AR 1311 DI 10.1029/2002G:014787 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DH UT WOS:000178888000052 ER PT J AU Masserot, D Lenoble, J Brogniez, C Houet, M Krotkov, N McPeters, R AF Masserot, D Lenoble, J Brogniez, C Houet, M Krotkov, N McPeters, R TI Retrieval of ozone column from global irradiance measurements and comparison with TOMS data. A year of data in the Alps SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID DERIVATION; BREWER; CLOUD AB [1] Spectral UV global irradiance has been measured regularly during the year 2000, in the French Alps, using two UV spectroradiometers. The total ozone column amount is retrieved from the ratio of irradiances around 305 and 340 nm, using look up tables based on modeling data. During cloudless days, ozone values from direct sun observations agree to within 5 DU. These ground based values compare reasonably well (to within about 4%, or 12 DU) with TOMS ozone data; this is consistent with the uncertainty of both methods which is estimated to 5 DU for TOMS, and 5-7 DU for clear sky ground based measurements. Generally the ground based ozone values seem to be slightly higher than the TOMS ozone values. For a few cases, the difference between TOMS and ground based values, can reach 10 to 15%. Different possible explanations of the discrepancies are considered. C1 Univ Sci & Technol, Opt Atmospher Lab, UMR 8518, Lille, France. Univ Grenoble 1, Equipe Interact Rayonnement Solaire Atmosphere, Grenoble, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Univ Sci & Technol, Opt Atmospher Lab, UMR 8518, Lille, France. RI McPeters, Richard/G-4955-2013; Krotkov, Nickolay/E-1541-2012 OI McPeters, Richard/0000-0002-8926-8462; Krotkov, Nickolay/0000-0001-6170-6750 NR 11 TC 15 Z9 16 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 2002 VL 29 IS 9 AR 1309 DI 10.1029/2002GL014823 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DH UT WOS:000178888000053 ER PT J AU McComas, DJ Elliott, HA Gosling, JT Reisenfeld, DB Skoug, RM Goldstein, BE Neugebauer, M Balogh, A AF McComas, DJ Elliott, HA Gosling, JT Reisenfeld, DB Skoug, RM Goldstein, BE Neugebauer, M Balogh, A TI Ulysses' second fast-latitude scan: Complexity near solar maximum and the reformation of polar coronal holes SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID WIND; STREAM; SPECTROMETER; SOUTHERN; FLUX AB [1] Ulysses' second fast latitude scan, near solar maximum, comprises a complicated mixture of solar wind flows from a variety of sources at high southern as well as low heliolatitudes. In contrast, observations northward of similar to40degrees N show the reformation of relatively steady fast solar wind flows, which are virtually indistinguishable from the polar coronal hole winds observed at high latitudes over Ulysses' first orbit. These high-speed flows predominantly display the opposite magnetic polarity from that observed in the northern hemisphere during the previous orbit, indicating that the Sun's dipole has reversed. The recent restructuring of the high-latitude solar wind, so soon after solar maximum, suggests that the heliospheric chaos around maximum occupies a unique and relatively shorter-lived portion of the solar cycle with the majority of the cycle maintaining the simple bimodal solar wind structure associated with large, persistent polar coronal holes. C1 SW Res Inst, San Antonio, TX 78284 USA. Los Alamos Natl Lab, Los Alamos, NM USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. Univ London Imperial Coll Sci Technol & Med, London, England. RP McComas, DJ (reprint author), SW Res Inst, 6220 Culebra Rd, San Antonio, TX 78284 USA. EM dmccomas@swri.edu; helliott@swri.edu; jgosling@lanl.gov; dreisen@lanl.gov; rskoug@lanl.gov; bgoldstein@jplsp.jpl.nasa.gov; mneugeb@jplsp.jpl.nasa.gov; a.balogh@ic.ac.uk RI Reisenfeld, Daniel/F-7614-2015 NR 19 TC 37 Z9 38 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 2002 VL 29 IS 9 AR 1290 DI 10.1029/2001GL014164 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DH UT WOS:000178888000072 ER PT J AU Mertens, CJ Mlynczak, MG Lopez-Puertas, M Remsberg, EE AF Mertens, CJ Mlynczak, MG Lopez-Puertas, M Remsberg, EE TI Impact of non-LTE processes on middle atmospheric water vapor retrievals from simulated measurements of 6.8 Mm Earth limb emission SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NONLOCAL THERMODYNAMIC-EQUILIBRIUM; MESOSPHERIC SOUNDER; INFRARED MONITOR; MU-M; STRATOSPHERE; VALIDATION; NIMBUS-7; BANDS AB [1] We present an efficient and accurate algorithm for the retrieval of water vapor (H2O) volume mixing ratio (vmr) in the middle atmosphere from satellite measurements of 6.8 mum Earth limb emission, which rigorously includes non-local thermodynamic equilibrium (non-LTE) processes. A number of retrieval studies have been conducted with this algorithm leading to three major conclusions about the retrieval of H2O in the middle atmosphere: (1) satellite measurements of 6.3 mum limb emission must be made to high altitudes (85-90 km), where the few optically thick H2O absorption lines become optically thin, in order to prevent large errors in retrieved stratospheric and mesospheric H2O vmr; (2) the impact of non-LTE on nighttime H2O retrievals is greater than previously thought; (3) the enhancements in the daytime H2O channel radiances of the NIMBUS 7 LIMS experiment may be entirely due to non-LTE emission from the H2O 6.3 mum bands. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. CSIC, Inst Astrofis Andalucia, Granada, Spain. RP Mertens, CJ (reprint author), NASA, Langley Res Ctr, 21 Langley Blvd,Mail Stop 401B, Hampton, VA 23681 USA. EM c.j.mertens@larc.nasa.gov RI Mlynczak, Martin/K-3396-2012; Lopez Puertas, Manuel/M-8219-2013 OI Lopez Puertas, Manuel/0000-0003-2941-7734 NR 12 TC 3 Z9 3 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 2002 VL 29 IS 9 AR 1288 DI 10.1029/2001GL014590 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DH UT WOS:000178888000074 ER PT J AU Purucker, M Langlais, B Olsen, N Hulot, G Mandea, M AF Purucker, M Langlais, B Olsen, N Hulot, G Mandea, M TI The southern edge of cratonic North America: Evidence from new satellite magnetometer observations - art. no. 1342 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETIC-ANOMALIES; REMANENT MAGNETIZATION; MODELS; MAGSAT; FIELD AB [1] A global model is developed for both induced and remanent magnetizations in the terrestrial lithosphere. The model is compared with, and well-described by, Orsted satellite observations. Interpretation of the observations over North America suggests that the large total field anomalies, associated with spherical harmonic degrees 15-26 and centered over Kentucky and the south-central United States, are the manifestations of the magnetic edges of the southern boundaries of cratonic North America. The techniques and models developed here may be of use in defining other cratonic boundaries. C1 NASA, Goddard Space Flight Ctr, Geodynam Branch, Raytheon ITSS, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Geodynam Branch, NAS NRC, Greenbelt, MD 20771 USA. Danish Space Res Inst, DK-2100 Copenhagen, Denmark. Inst Phys Globe, F-75252 Paris 05, France. RP NASA, Goddard Space Flight Ctr, Geodynam Branch, Raytheon ITSS, Greenbelt, MD 20771 USA. RI Hulot, Gauthier/A-5627-2011; Olsen, Nils/H-1822-2011; MANDEA, Mioara/E-4892-2012; Langlais, Benoit/K-5366-2012 OI Olsen, Nils/0000-0003-1132-6113; Langlais, Benoit/0000-0001-5207-304X NR 20 TC 33 Z9 33 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 2002 VL 29 IS 9 AR 013645. DI 10.1029/2001GL013645 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DH UT WOS:000178888000021 ER PT J AU Vignes, D Acuna, MH Connerney, JEP Crider, DH Reme, H Mazelle, C AF Vignes, D Acuna, MH Connerney, JEP Crider, DH Reme, H Mazelle, C TI Factors controlling the location of the Bow Shock at Mars SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR-WIND INTERACTION; VENUS-LIKE INTERACTION; MAG/ER EXPERIMENT; GLOBAL SURVEYOR; MAGNETIC-FIELDS; POSITION; SHAPE AB [1] During the first year of the Mars Global Surveyor (MGS) mission, 553 shock crossings have been identified from a total of 363 orbits. The shape of the shock has been determined by examining the MGS spacecraft Magnetometer/ Electron Reflectometer (MAG/ER) data. The location of the shock was found highly variable. The present study shows that the high crustal magnetic sources, found in the southern hemisphere, do not seem responsible for the Bow Shock (BS) variability. The present study shows that contrary to many expectations there is no obvious strong one to one correlation between the location of the highest crustal sources and the variability of the shock position. On the other hand, the shock appears farthest from Mars in the hemisphere of locally upward interplanetary electric field consistent with the idea that mass loading play a role in controlling the BS location, which confirms previous results. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Ctr Etud Spatiale Rayonnements, Toulouse, France. RP Vignes, D (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM vignes@lepmom.gsfc.nasa.gov; mha@lepmom.gsfc.nasa.gov; jec@lepjec.gsfc.nasa.gov; dcrider@lepvax.gsfc.nasa.gov; Henri.Reme@cesr.fr; Christian.Mazelle@cesr.fr RI connerney, john/I-5127-2013; Hurley, Dana/F-4488-2015 OI Hurley, Dana/0000-0003-1052-1494 NR 19 TC 25 Z9 26 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 2002 VL 29 IS 9 AR 1328 DI 10.1029/2001GL014513 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DH UT WOS:000178888000035 ER PT J AU Vinnikov, KY Robock, A Cavalieri, DJ Parkinson, CL AF Vinnikov, KY Robock, A Cavalieri, DJ Parkinson, CL TI Analysis of seasonal cycles in climatic trends with application to satellite observations of sea ice extent SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SURFACE AIR-TEMPERATURE AB We present a new technique to study the seasonal cycle of climatic trends in the expected value, variance, and other moments of the statistical distribution. The basis of the technique is multiple linear regression, but with periodic basis functions. The technique allows us to provide comprehensive information on statistical parameters of climate for every day of an observational period. Using daily data, the technique has no problems caused by different lengths of months or the leap-year cycle. Without needing to assume the stationarity of contemporary climate, the technique allows the study of statistical parameters of climatic records of arbitrary length. We illustrate the technique with applications to trends in the satellite observed variations of sea ice extent in the Northern and Southern Hemispheres. We show that a significant part of the variability in hemispheric sea ice extents for the period 1978-1999 is related to linear trends. C1 Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. Rutgers State Univ, Dept Environm Sci, New Brunswick, NJ 08901 USA. NASA, Goddard Space Flight Ctr, Oceans & Ice Branch, Greenbelt, MD 20771 USA. RP Vinnikov, KY (reprint author), Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. RI Vinnikov, Konstantin/F-9348-2010; Parkinson, Claire/E-1747-2012; Robock, Alan/B-6385-2016 OI Parkinson, Claire/0000-0001-6730-4197; NR 21 TC 12 Z9 12 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 2002 VL 29 IS 9 AR 1310 DI 10.1029/2001GL014481 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DH UT WOS:000178888000076 ER PT J AU Yang, ZH Toon, GC Margolis, JS Wennberg, PO AF Yang, ZH Toon, GC Margolis, JS Wennberg, PO TI Atmospheric CO2 retrieved from ground-based near IR solar spectra SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INTEGRATED ABSORPTION INTENSITIES; MOLECULAR-OXYGEN; O-2 AB [1] The column-averaged volume mixing ratio (VMR) of CO2 over Kitt Peak, Arizona, has been retrieved from high-resolution solar absorption spectra obtained with the Fourier transform spectrometer on the McMath telescope. Simultaneous column measurements of CO2 at similar to6300 cm(-1) and O-2 at similar to7900 cm(-1) were ratioed to minimize systematic errors. These column ratios were then scaled by the mean O-2 VMR (0.2095) to yield column-averaged vmrs of CO2. These display similar behavior to the Mauna Loa in situ surface measurements. During the period 1977-1995, the column-averaged mixing ratio of CO2 increased at an average rate of 1.49 +/- 0.04 ppmv/yr with seasonal variations of similar to7 ppmv peak-to-peak. Our retrievals demonstrate that this remote technique is capable of precisions better than 0.5%. C1 CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. RP Yang, ZH (reprint author), CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. RI Wennberg, Paul/A-5460-2012 NR 9 TC 48 Z9 48 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 1 PY 2002 VL 29 IS 9 AR 1339 DI 10.1029/2001GL014537 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DH UT WOS:000178888000024 ER PT J AU Hicke, JA Asner, GP Randerson, JT Tucker, C Los, S Birdsey, R Jenkins, JC Field, C AF Hicke, JA Asner, GP Randerson, JT Tucker, C Los, S Birdsey, R Jenkins, JC Field, C TI Trends in North American net primary productivity derived from satellite observations, 1982-1998 SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Article DE net primary productivity; North America; trends; carbon cycle; NPP; NDVI ID TERRESTRIAL CARBON SINK; ATMOSPHERIC CO2; INTERANNUAL VARIABILITY; SPATIAL-RESOLUTION; FOREST ECOSYSTEMS; US FORESTS; LAND; MODEL; FERTILIZATION; NITROGEN AB [1] Net primary productivity (NPP) in North America was computed for the years 1982-1998 using the Carnegie-Ames-Stanford approach (CASA) carbon cycle model. CASA was driven by a new, corrected satellite record of the normalized difference vegetation index at 8-km spatial resolution. Regional trends in the 17-year NPP record varied substantially across the continent. Croplands and grasslands of the Central Plains and eastern Canadian forests experienced summer increases in NPP. Peak NPP trends in Alaska and western Canada occurred in late spring or early summer, suggesting an earlier onset of the growing season in these regions. Forests and woodlands of the southeastern United States showed NPP increases in spring and fall, also suggesting an increase in the length of the growing season. An analysis of climate variables showed that summer precipitation increased in the Central Plains, indicating that climate changes probably play some role in increasing NPP in this region, though intensive management of agricultural ecosystems has also increased productivity. Similarly, increased summer precipitation possibly increased NPP in eastern Canada, but another possible explanation is forest recovery after insect damage. NPP in the southeastern United States increased in the absence of climate variation. Much of this region consists of aggressively managed forests, with young stand ages and intensive silviculture resulting in increased NPP. The high latitudes of western Canada and Alaska experienced spring warming that could have increased NPP in late spring or early summer. C1 Univ Colorado, Dept Geol Sci, Boulder, CO 80309 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. NASA, Goddard Space Flight Ctr, Lab Atmospher Phys, Greenbelt, MD 20771 USA. US Forest Serv, USDA, Newtown Sq, PA 19073 USA. US Forest Serv, USDA, Burlington, VT 05402 USA. Carnegie Inst Washington, Stanford, CA 94305 USA. RP Hicke, JA (reprint author), Carnegie Inst Washington, 290 Panama St, Stanford, CA 94305 USA. RI Los, Sietse/G-8985-2012; Hicke, Jeff/M-9677-2013; Asner, Gregory/G-9268-2013 OI Asner, Gregory/0000-0001-7893-6421 NR 56 TC 38 Z9 39 U1 3 U2 28 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0886-6236 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD MAY-JUN PY 2002 VL 16 IS 2 AR 1019 DI 10.1029/2001GB001550 PG 22 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA 609DG UT WOS:000178887900010 ER PT J AU DeFries, RS Bounoua, L Collatz, GJ AF DeFries, RS Bounoua, L Collatz, GJ TI Human modification of the landscape and surface climate in the next fifty years SO GLOBAL CHANGE BIOLOGY LA English DT Article DE human impacts; land cover; surface climate ID GENERAL-CIRCULATION MODEL; DOUBLED ATMOSPHERIC CO2; LAND-USE CHANGES; TERRESTRIAL CARBON METABOLISM; ICE-CLOUD MICROPHYSICS; SEMI-ARID REGIONS; PARAMETERIZATION SIB2; GLOBAL CLIMATE; STOMATAL CONDUCTANCE; CANOPY REFLECTANCE AB Human modification of the landscape potentially affects exchanges of energy and water between the terrestrial biosphere and the atmosphere. This study develops a possible scenario for land cover in the year 2050 based on results from the IMAGE 2 (Integrated Model to Assess the Greenhouse Effect) model, which projects land-cover changes in response to demographic and economic activity. We use the land-cover scenario as a surface boundary condition in a biophysically-based land-surface model coupled to a general circulation model for a 15-years simulation with prescribed sea surface temperature and compare with a control run using current land cover. To assess the sensitivity of climate to anthropogenic land-cover change relative to the sensitivity to decadal-scale interannual variations in vegetation density, we also carry out two additional simulations using observed normalized difference vegetation index (NDVI) from relatively low (1982-83) and high (1989-90) years to describe the seasonal phenology of the vegetation. In the past several centuries, large-scale land-cover change occurred primarily in temperate latitudes through conversion of forests and grassland to highly productive cropland and pasture. Several studies in the literature indicate that past changes in surface climate resulting from this conversion had a cooling effect owing to changes in vegetation morphology (increased albedo). In contrast, this study indicates that future land-cover change, likely to occur predominantly in the tropics and subtropics, has a warming effect governed by physiological rather than morphological mechanisms. The physiological mechanism is to reduce carbon assimilation and consequently latent relative to sensible heat flux resulting in surface temperature increases up to 2 degreesC and drier hydrologic conditions in locations where land cover was altered in the experiment. In addition, in contrast to an observed decrease in diurnal temperature range (DTR) over land expected with greenhouse warming, results here suggest that future land-cover conversion in tropics could increase the DTR resulting from decreased evaporative cooling during the daytime. For grid cells with altered land cover, the sensitivity of surface temperature to future anthropogenic land-cover change is generally within the range induced by decadal-scale interannual variability in vegetation density in temperate latitudes but up to 1.5 degreesC warmer in the tropics. C1 Univ Maryland, Dept Geog, College Pk, MD 20742 USA. Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP DeFries, RS (reprint author), Univ Maryland, Dept Geog, College Pk, MD 20742 USA. EM rd63@umail.umd.edu RI collatz, george/D-5381-2012 NR 74 TC 111 Z9 119 U1 5 U2 34 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 1354-1013 J9 GLOBAL CHANGE BIOL JI Glob. Change Biol. PD MAY PY 2002 VL 8 IS 5 BP 438 EP 458 DI 10.1046/j.1365-2486.2002.00483.x PG 21 WC Biodiversity Conservation; Ecology; Environmental Sciences SC Biodiversity & Conservation; Environmental Sciences & Ecology GA 549CE UT WOS:000175426300003 ER PT J AU Korycansky, DG Zahnle, KJ Mac Low, MM AF Korycansky, DG Zahnle, KJ Mac Low, MM TI High-resolution simulations of the impacts of asteroids into the Venusian atmosphere II: 3D models SO ICARUS LA English DT Article DE impact processes; cratering; near Earth asteroids; Venus ID RAYLEIGH-TAYLOR INSTABILITY; COMET SHOEMAKER-LEVY-9; GEOSTROPHIC TURBULENCE; JUPITER; CRATERS; METEOROIDS; DIMENSIONS; EXPLOSION; SHAPE; SIZE AB We compare high-resolution 2D and 3D numerical hydrocode simulations of asteroids striking the atmosphere of Venus. Our focus is on aerobraking and its effect on the size of impact craters. We consider impacts both by spheres and by the real asteroid 4769 Castalia, a severely nonspherical. body in a Venus-crossing orbit. We compute mass and momentum fluxes as functions of altitude as global measures of the asteroid's progress. We find that, on average, the 2D and 3D simulations are in broad agreement over how quickly an asteroid slows down, but that the scatter about the average is much larger for the 2D models than for the 3D models. The 2D models appear to be rather strongly susceptible to the "butterfly effect," in which tiny changes in initial conditions (e.g., 0.05% change in the impact velocity) produce quite different chaotic evolutions. By contrast, the global properties of the 3D models appear more reproducible despite seemingly large differences in initial conditions. We argue that this difference between 2D and 3D models has its root in the greater geometrical constraints present in any 2D model, and in particular in the global conservation of enstrophy in 2D that forces energy to pool in large-scale structures. It is the interaction of these artificial large-scale structures that causes slightly different 2D models to diverge so greatly. These constraints do not apply in 3D and large scale structures are not observed to form. A one-parameter modified pancake model reproduces the expected crater diameters of the 3D Castalias reasonably well. (C) 2002 Elsevier Science (USA). C1 Univ Calif Santa Cruz, Dept Earth Sci, CODEP, Santa Cruz, CA 95064 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Amer Museum Nat Hist, Dept Astrophys, New York, NY 10024 USA. RP Korycansky, DG (reprint author), Univ Calif Santa Cruz, Dept Earth Sci, CODEP, Santa Cruz, CA 95064 USA. NR 47 TC 14 Z9 14 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 2002 VL 157 IS 1 BP 1 EP 23 DI 10.1006/icar.2002.6795 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 557VL UT WOS:000175929000001 ER PT J AU Matese, JJ Lissauer, JJ AF Matese, JJ Lissauer, JJ TI Characteristics and frequency of weak stellar impulses of the Oort cloud SO ICARUS LA English DT Article DE comets; dynamics; celestial mechanics ID COMET CLOUD; SOLAR-SYSTEM; HIPPARCOS; EVOLUTION; ORBITS; MATTER AB We have developed a model of the response of the outer Oort cloud of comets to simultaneous tidal perturbations of the adiabatic galactic force and a stellar impulse. The six-dimensional phase space of near-parabolic comet orbital elements has been subdivided into cells. A mapping of the evolution of these elements from beyond the loss cylinder boundary into the inner planetary region over the course of a single orbit is possible. This is done by treating each perturbation separately, and in combination, during a time interval of 5 Myr. We then obtain the time dependence of a wide range of observable comet flux characteristics, which provides a fingerprint of the dynamics. These include the flux distributions of energy, perihelion distance, major axis orientation, and angular momentum orientation. Correlations between these variables are also determined. We show that substantive errors occur if one superposes the separately obtained flux results of the galactic tide and the stellar impulse rather than superposing the tidal and impulsive perturbations in a single analysis. Detailed illustrations are given for an example case where the stellar mass and relative velocity have the ratio M-*/V-rel = 0.043 M-circle plus/km s(-1) and the solar impact parameter is 45,000 AU. This case has features similar to the impending Gliese 710 impulse with the impact parameter selected to be close to the low end of the predicted range. We find that the peak in the observable comet flux exceeds that due to the galactic tide alone by approximate to41%. 'We also present results for the time dependence of the flux enhancements and for the mean encounter frequency of weak stellar impulse events as functions of M-*/V-rel and solar impact parameter. (C) 2002 Elsevier Science (USA). C1 Univ Louisiana, Dept Phys, Lafayette, LA 70504 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Matese, JJ (reprint author), Univ Louisiana, Dept Phys, Lafayette, LA 70504 USA. NR 23 TC 21 Z9 21 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 2002 VL 157 IS 1 BP 228 EP 240 DI 10.1006/icar.2001.6799 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 557VL UT WOS:000175929000018 ER PT J AU Livengood, TA Hewagama, T Kostiuk, T Fast, KE Goldstein, JJ AF Livengood, TA Hewagama, T Kostiuk, T Fast, KE Goldstein, JJ TI Improved determination of ethane (C2H6) abundance in Titan's stratosphere SO ICARUS LA English DT Article DE satellites of Saturn; Titan; atmospheres; composition; infrared observations ID VOYAGER INFRARED OBSERVATIONS; ATMOSPHERE; SPECTROSCOPY AB Ethane spectral lines were observed in emission from Titan in August 1993, October 1995, and September 1996, at a spectral resolution of lambda/Deltalambda approximate to 10(6), at wavelength 11.7-11.9 mum using the Goddard Infrared Heterodyne Spectrometer at the NASA Infrared Telescope Facility on Mauna Kea, Hawaii. The ethane mole fraction is determined to be (8.8 +/- 2.2) x 10(-6) (68.3% confidence limits, "1sigma"), averaging the retrievals from each observing run obtained using the "recommended" thermal profile of R. V. Yelle, D. Strobel, E. Lellouch, and D. Gautier (1997, in Huygens: Science, Payload, and Mission (J.-P. Lebreton, Ed.), pp. 243-256, European Space Agency SP-1177). (C) 2002 Elsevier Science (USA). C1 Challenger Ctr Space Sci Educ, Alexandria, VA 22314 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Livengood, TA (reprint author), Challenger Ctr Space Sci Educ, 1250 N Pitt St, Alexandria, VA 22314 USA. RI Hewagama, T/C-8488-2012; Livengood, Timothy/C-8512-2012; Kostiuk, Theodor/A-3077-2014 NR 19 TC 19 Z9 19 U1 0 U2 2 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 2002 VL 157 IS 1 BP 249 EP 253 DI 10.1006/icar.2002.6823 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 557VL UT WOS:000175929000020 ER PT J AU Roe, HG de Pater, I Macintosh, BA Gibbard, SG Max, CE McKay, CP AF Roe, HG de Pater, I Macintosh, BA Gibbard, SG Max, CE McKay, CP TI Titan's atmosphere in late southern spring observed with adaptive optics on the W.M. Keck II 10-meter telescope SO ICARUS LA English DT Article DE Titan; satellites; atmospheres; infrared observations ID IMAGES; SURFACE AB Using adaptive optics on the W M. Keck H telescope, we imaged Titan several times during 1999 to 2001 in narrowband near-infrared filters selected to probe Titan's stratosphere and upper troposphere. We observed a bright feature around the south pole, possibly a collar of haze or clouds. Further, we find that solar phase angle explains most of the observed east-west brightness asymmetry of Titan's atmosphere, although the data do not preclude the presence of a "morning fog" effect at small solar phase angle. (C) 2002 Elsevier Science (USA). C1 Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Roe, HG (reprint author), Univ Calif Berkeley, Dept Astron, 601 Campbell Hall, Berkeley, CA 94720 USA. OI Max, Claire/0000-0003-0682-5436 NR 17 TC 33 Z9 33 U1 0 U2 1 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 2002 VL 157 IS 1 BP 254 EP 258 DI 10.1006/icar.2002.6831 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 557VL UT WOS:000175929000021 ER PT J AU Smith, MD Conrath, RJ Pearl, JC Christensen, PR AF Smith, MD Conrath, RJ Pearl, JC Christensen, PR TI Thermal Emission Spectrometer observations of Martian planet-encircling dust storm 2001A SO ICARUS LA English DT Article ID ATMOSPHERIC TEMPERATURES; TES OBSERVATIONS; MARS; VIKING; AEROBRAKING; MARINER-9; OPACITY AB The initiation and evolution of a planet-encircling dust storm on Mars have been observed in unprecedented detail by the Thermal Emission Spectrometer (TES) on board the Mars Global Surveyor. A local dust storm began to expand quickly on 26 June 2001 (areo-centric longitude, L-s = 185degrees), becoming a planet-encircling dust storm by 11 July 2001. The dust storm had dust optical depth >2 over wide areas and caused atmospheric temperatures over a large vertical range to warm by >40 K from 20-N latitude to the south pole. (C) 2002 Elsevier Science (USA). C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cornell Univ, CRSR, Ithaca, NY 14853 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. RP Smith, MD (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Smith, Michael/C-8875-2012 NR 26 TC 87 Z9 88 U1 0 U2 2 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 2002 VL 157 IS 1 BP 259 EP 263 DI 10.1006/icar.2001.6797 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 557VL UT WOS:000175929000022 ER PT J AU Stadter, PA Chacos, AA Heins, RJ Moore, GT Olsen, EA Asher, MS Bristow, JO AF Stadter, PA Chacos, AA Heins, RJ Moore, GT Olsen, EA Asher, MS Bristow, JO TI Confluence of navigation, communication, and control in distributed spacecraft systems SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB This research details the development of technologies and methodologies that enable distributed spacecraft systems by supporting integrated navigation, communication, and control. Operating at the confluence of these critical functions produces capabilities needed to realize the promise of distributed spacecraft systems, including improved performance and robustness relative to monolithic space systems. Navigation supports science data association and data alignment for distributed aperture sensing, multipoint observation, and co-observation of target regions. Communication enables autonomous distributed science data processing and information exchange among space assets. Both navigation and communication provide essential input to control methods for coordinating distributed autonomous assets at the interspacecraft system level and the intraspacecraft affector subsystem level. A technology solution to implement these capabilities, the Crosslink Transceiver, is also described. The Crosslink Transceiver provides navigation and communication capability that can be integrated into a developing autonomous command and control methodology for distributed spacecraft systems. A small satellite implementation of the Crosslink Transceiver design is detailed and its ability to support broad distributed spacecraft mission classes is described. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Stadter, PA (reprint author), Johns Hopkins Univ, Appl Phys Lab, 11100 Johns Hopkins Rd, Laurel, MD 20723 USA. NR 16 TC 6 Z9 7 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 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD MAY PY 2002 VL 17 IS 5 BP 26 EP 32 DI 10.1109/62.1001989 PG 7 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA 553DY UT WOS:000175661500007 ER PT J AU Liebowitz, J AF Liebowitz, J TI A look at NASA Goddard Space Flight Center's knowledge management initiatives SO IEEE SOFTWARE LA English DT Article AB As we move from the information age to the knowledge era, knowledge is being treated as a key asset. NASA and others are realizing that to maximize their organizations' potential, they must fully leverage their knowledge or intellectual capital. To accomplish this task, an emerging trend is to develop knowledge management and knowledge sharing initiatives within organizations. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Liebowitz, J (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 8 TC 6 Z9 6 U1 0 U2 4 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 0740-7459 J9 IEEE SOFTWARE JI IEEE Softw. PD MAY-JUN PY 2002 VL 19 IS 3 BP 40 EP + DI 10.1109/MS.2002.1003451 PG 4 WC Computer Science, Software Engineering SC Computer Science GA 551HD UT WOS:000175553400018 ER PT J AU Geudtner, D Zink, M Gierull, C Shaffer, S AF Geudtner, D Zink, M Gierull, C Shaffer, S TI Interferometric alignment of the X-SAR antenna system on the space shuttle radar topography mission SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE SAR antenna beam alignment; SAR interferometry; shuttle radar topography mission/X-band synthetic aperture radar (SRTM/X-SAR) ID SYNTHETIC-APERTURE RADAR; SIR-C/X-SAR; STATISTICS; PHASE AB The on-orbit alignment of the antenna beams of both the X-band and C-band radar systems during operations of the shuttle radar topography mission/X-band synthetic aperture radar (SRTM/X-SAR) was a key requirement for achieving best interferometric performance. In this paper, we consider the X-SAR antenna beam alignment in azimuth. For a single-pass cross-track SAR interferometer, we establish the relation between yaw and pitch misalignment of the antenna beams and the resulting relative shift of the Doppler frequency bands. This relation is used to provide solutions for the mechanical adjustments of the outboard antenna and electronic beam steering to correct for azimuth misalignment. Furthermore, the effects of the X-SAR effective outboard antenna pattern on the azimuth beam alignment are analyzed. As a result, a so-called "relaxing" factor is derived, which increases the limit for the difference in antenna azimuth angle with respect to the requirement on spectral overlap, and hence spatial interferogram resolution. However, we also show that the alignment requirement is driven by the constraint on decreasing the azimuth ambiguity-to-signal ratio (AASR) for the effective outboard antenna pattern to reduce the resulting additional height error. The strategy for misalignment determination and correction is presented, and results of the analysis of the in-flight X-SAR antenna beam alignment are discussed. C1 DLR, German Aerosp Ctr, Inst Microwave & Radar Syst, D-82230 Wessling, Germany. European Space Agcy, Estec, NL-2200 AG Noordwijk, Netherlands. Def Res & Dev Canada Ottawa, Aerosp Radar & Navigat Sect, Ottawa, ON K1A 0Z4, Canada. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Geudtner, D (reprint author), DLR, German Aerosp Ctr, Inst Microwave & Radar Syst, D-82230 Wessling, Germany. NR 21 TC 10 Z9 13 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 2002 VL 40 IS 5 BP 995 EP 1006 AR PII S0196-2892(02)04811-8 DI 10.1109/TGRS.2002.1010887 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 566QB UT WOS:000176438800001 ER PT J AU Lowe, ST Kroger, P Franklin, G LaBrecque, JL Lerma, J Lough, M Marcin, MR Muellerschoen, RJ Spitzmesser, D Young, LE AF Lowe, ST Kroger, P Franklin, G LaBrecque, JL Lerma, J Lough, M Marcin, MR Muellerschoen, RJ Spitzmesser, D Young, LE TI A delay/Doppler-mapping receiver system for GPS-reflection remote sensing SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID ALTIMETRY AB A delay/Doppler-mapping receiver system, developed specifically for global positioning system (GPS)-reflection remote sensing, is described, and example delay/Doppler waveforms are presented. The high-quality data obtained with this system provide a more accurate and detailed examination of ground-based and aircraft GPS-reflection phenomenology than has been available to date. As an example, systematic effects in the reflected signal delay waveform, due to nonideal behavior of the C/A-code auto-correlation function, are presented for the first time. Both a single-channel open-loop recording system and a recently developed 16-channel recorder are presented. The open-loop data from either recorder are postprocessed with a software GPS receiver that performs the following functions: signal detection; phase and delay tracking; delay, Doppler, and delay/Doppler waveform mapping; dual-frequency (L1 and L2) processing; C/A-code and Y-code waveform extraction; coherent integrations as short as 125 mus; navigation message decoding; and precise observable time tagging. The software can perform these functions on all detectable satellite signals without dead time, and custom signal-processing features can easily be included into the system. Data collected with this system can, in principle, be processed to extract 1) over an ocean: mean sea height, wind speed and direction, and significant wave height; 2) over land: soil moisture, biomass, and bistatic imaging; and 3) over ice: ice age, thickness, and surface ice density. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA Headquarters, Washington, DC 20546 USA. Sony Precis Technol Amer Inc, Lake Forest, IL USA. Compaq Comp Corp, Galway, Ireland. RP Lowe, ST (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 24 Z9 29 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 2002 VL 40 IS 5 BP 1150 EP 1163 AR PII S0196-2892(02)04809-X DI 10.1109/TGRS.2002.1010901 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 566QB UT WOS:000176438800015 ER PT J AU Li, Q Rimoldi, B Simon, MK AF Li, Q Rimoldi, B Simon, MK TI Bandwidth-efficient constant-energy trellis-coded modulation schemes with prescribed decoding delay SO IEEE TRANSACTIONS ON INFORMATION THEORY LA English DT Article; Proceedings Paper CT 5th International Symposium on Signals, Systems, and Electronics (ISSSE 01) CY JUL, 2001 CL TOKYO, JAPAN SP URSI, Commun Soc, Electr Soc, IEICE, Sci Council Japan, IEEE Japan Council DE decoding delay; maximum-likelihood sequence estimation (MLSE); minimum shift keying (MSK); pulse amplitude modulation (PAM); spectral shaping; trellis-coded modulation (TCM); Viterbi decoder AB For a general class of constant-energy trellis-coded modulation (TCM) schemes with 2(v) states, necessary and sufficient conditions to guarantee that a maximum-likelihood sequence estimator (MSLE) can decode each symbol with a fixed delay of v symbols are derived. Additive white Gaussian noise (AWGN) is assumed. Minimum shift keying (MSK) is a special case that belongs to the family of modulation schemes with v = 1. It is shown that when these conditions are met, the minimum squared Euclidean distance is upper-bounded by 4E(s), where E-s. is the signal's energy per interval. Necessary and sufficient conditions to achieve the upper bound are given and it is shown that these conditions are met if and only if the TCM scheme can be implemented as pulse amplitude modulation (PAM) using a pulse that extends over v + 1 symbols. Signals that achieve this upper bound and maximize the power within a given bandwidth are found. The bandwidth efficiency of such schemes is significantly higher than that of MSK. C1 Broadcom Corp, Mt Lakes, NJ 07046 USA. Swiss Fed Inst Technol, Commun Syst Dept, CH-1015 Lausanne, Switzerland. Jet Prop Lab, Pasadena, CA 91109 USA. RP Broadcom Corp, Mt Lakes, NJ 07046 USA. EM quinnli@broadcom.com; bixio.rimoldi@epfl.ch; marvin.k.simon@jpl.nasa.gov NR 9 TC 0 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9448 EI 1557-9654 J9 IEEE T INFORM THEORY JI IEEE Trans. Inf. Theory PD MAY PY 2002 VL 48 IS 5 BP 1150 EP 1161 AR PII S0018-9448(02)03095-X DI 10.1109/18.995602 PG 12 WC Computer Science, Information Systems; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 541DX UT WOS:000174970900010 ER PT J AU Litman, D Patel-Schneider, PF Mishra, A Crawford, J Dvorak, D AF Litman, D Patel-Schneider, PF Mishra, A Crawford, J Dvorak, D TI R++: Adding path-based rules to C++ SO IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING LA English DT Article DE object-oriented models and systems; rule-based processing and systems; C plus; knowledge-based systems; expert systems AB Object-oriented languages and rule-based languages offer two distinct and useful programming abstractions. However, previous attempts to integrate data-driven rules into object-oriented languages have typically achieved an uneasy union at best. R++ is a new, closer integration of the rule-based and object-oriented paradigms that extends C++ with a single programming construct, the path-based rule, as a new kind of class member, Path-based rules-data-driven rules that are restricted to following pointers between objects-are like "automatic methods" that are triggered by changes to the objects they monitor. Path-based rules provide a useful level of abstraction that encourages a more declarative style of programming and are valuable in object-oriented designs as a means of modeling dynamic collections of interdependent objects. Unlike more traditional pattern-matching rules, path-based rules are not at odds with the object-oriented paradigm and offer performance advantages for many natural applications. C1 AT&T Labs Res, Florham Pk, NJ 07932 USA. Bell Labs Res, Murray Hill, NJ 07974 USA. Inautix Technol, E Brunswick, NJ 08816 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Litman, D (reprint author), AT&T Labs Res, Room A211,180 Pk Ave, Florham Pk, NJ 07932 USA. EM diane@research.att.com; pfps@research.bell-labs.com; anil_mishra@excite.com; jc@i2.com; dldvorak@mail1.jpl.nasa.gov NR 43 TC 5 Z9 6 U1 0 U2 3 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1041-4347 J9 IEEE T KNOWL DATA EN JI IEEE Trans. Knowl. Data Eng. PD MAY-JUN PY 2002 VL 14 IS 3 BP 638 EP 658 DI 10.1109/TKDE.2002.1000347 PG 21 WC Computer Science, Artificial Intelligence; Computer Science, Information Systems; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 547DG UT WOS:000175317300011 ER PT J AU Otterman, J Atlas, R Chou, SH Jusem, JC Pielke, RA Chase, TN Rogers, J Russell, GL Schubert, SD Sud, YC Terry, J AF Otterman, J Atlas, R Chou, SH Jusem, JC Pielke, RA Chase, TN Rogers, J Russell, GL Schubert, SD Sud, YC Terry, J TI Are stronger North-Atlantic southwesterlies the forcing to the late-winter warming in Europe? SO INTERNATIONAL JOURNAL OF CLIMATOLOGY LA English DT Article DE climate trends; advancement of spring in Europe; ocean-to-land advection; Atlantic southwesterlies ID CLIMATE VARIABILITY; TEMPERATURE; REANALYSIS; SATELLITE; INCREASE; TRENDS; SEA AB We examine a possible mechanism leading to late-winter warming, and thus to an early spring in Europe. From the National Centers for Environmental Prediction reanalysis, we extract for the years 1948-99 ocean-surface winds over the eastern North Atlantic, and air temperatures at the surface T-s, and at the 500 hPa level T-500 in late-winter and spring. T-s is extracted at six European locations, all at 50.5 degreesN, ranging in longitude from 1.9degreesE (northeastern France) to 26.2degreesE (Ukraine). To quantify the advection of maritime air into Europe, we evaluate for three-pentad groups the index I-na of the southwesterlies at 45degreesN, 20degreesW; I-na is the average wind speed at this point if the direction is from the quadrant 180-270degrees (when the direction is different, the contribution counts as zero). In late winter, correlations C-it between I-na and T-s are substantial, up to the 0.6 level in western Europe (but weaker correlations for Poland and Ukraine). C-it drops sharply by mid-March, occasionally taking negative values subsequently. This drop in C-it indicates that maritime air advection is no longer associated closely with the surface-air warming; the role of insolation becomes important, and thus the drop in C-it marks the arrival of spring. Correlations C-iDelta between I-na and our lapse-rate parameter Delta, the difference between T-s and T-500, indicate that the flow of warm maritime-air from the North Atlantic into this 'corridor' at 50.5degreesN is predominantly at lower tropospheric level. By computing the best linear fit to I-na and T-s, the trends for the period 1948-99 are evaluated. The trends are appreciable in the second half of February and the first half of March: for I-na, the trends are 0.41 m s(-1) and 0.15 m s(-1) per decade in pentad groups 10-12 and 13-15 respectively (I-na increased from 1948 to 1999 by 2.10 m s(-1) and 0.77 m s(-1)); for T-s, the trends for western Germany are 0.36degreesC and 0.43degreesC per decade in these two respective pentad groups (T-s in this location increased from 1948 to 1999 by 1.86degreesC and 2.19degreesC). Such higher near-surface temperatures would markedly influence snow-melt, and thus absorption of insolation by the surface. Our three-pentad analysis points to the interval from mid-February to mid-March as the end of-winter period in which the southwesterlies over the eastern North Atlantic become stronger and the surface-air temperatures in Europe rise markedly, the lapse rate becomes steeper, and concurrently the longitudinal temperature gradient between the Somme (France) and the Oder (Germany-Poland border) (about -4degreesC in 1948 for the 10degrees longitude distance) is reduced by 0.8degreesC, i.e. by 20% of its 1948 value. Our thesis, that the observed late-winter warming and the concomitant advancement of spring in Europe results, at least in part, from stronger southwesterlies over the North Atlantic, merits further investigations. Copyright (C) 2002 Royal Meteorological Society. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Gen Sci Corp, Beltsville, MD USA. Univ Colorado, Boulder, CO 80309 USA. Colorado State Univ, Ft Collins, CO 80523 USA. Ohio State Univ, Columbus, OH 43210 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Otterman, J (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 910-3, Greenbelt, MD 20771 USA. RI Pielke, Roger/A-5015-2009; Atlas, Robert/A-5963-2011 OI Atlas, Robert/0000-0002-0706-3560 NR 24 TC 6 Z9 6 U1 1 U2 3 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0899-8418 J9 INT J CLIMATOL JI Int. J. Climatol. PD MAY PY 2002 VL 22 IS 6 BP 743 EP 750 DI 10.1002/joc.681 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 562BK UT WOS:000176177400008 ER PT J AU Tunstel, E de Oliveira, MAA Berman, S AF Tunstel, E de Oliveira, MAA Berman, S TI Fuzzy behavior hierarchies for multi-robot control SO INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS LA English DT Article AB Hierarchical approaches and methodologies are commonly used for control system design and synthesis. Well-known model-based techniques are often applied to solve problems of complex and large-scale control systems. The general philosophy of decomposing control problems into modular and more manageable subsystem control problems applies equally to the growing domain of intelligent and autonomous systems. However, for this class of systems, new techniques for subsystem coordination and overall system control are often required. This article presents an approach to hierarchical control design and synthesis for the case where the collection of subsystems is comprised of fuzzy logic controllers and fuzzy knowledge-based decision systems. The approach is used to implement hierarchical behavior-based controllers for autonomous navigation of one or more mobile robots. Theoretical details of the approach are presented, followed by discussions of practical design and implementation issues. Example implementations realized on various physical mobile robots are described to demonstrate how the techniques may be applied in practical applications involving homogeneous and heterogeneous robot teams. (C) 2002 Wiley Periodicals, Inc. C1 CALTECH, Jet Prop Lab, NASA, Pasadena, CA 91109 USA. Univ New Mexico, NASA, Ctr Autonomous Control Engn, Albuquerque, NM 87131 USA. Ben Gurion Univ Negev, Dept Ind Engn & Management, IL-84105 Beer Sheva, Israel. RP Tunstel, E (reprint author), CALTECH, Jet Prop Lab, NASA, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI BERMAN, SIGAL/F-1467-2012 OI BERMAN, SIGAL/0000-0001-7717-7259 NR 30 TC 19 Z9 19 U1 0 U2 4 PU JOHN WILEY & SONS INC PI HOBOKEN PA 111 RIVER ST, HOBOKEN, NJ 07030 USA SN 0884-8173 J9 INT J INTELL SYST JI Int. J. Intell. Syst. PD MAY PY 2002 VL 17 IS 5 BP 449 EP 470 DI 10.1002/int.10032 PG 22 WC Computer Science, Artificial Intelligence SC Computer Science GA 542YN UT WOS:000175073500002 ER PT J AU Sorokin, DY Gorlenko, VM Tourova, TP Tsapin, A Nealson, KH Kuenen, GJ AF Sorokin, DY Gorlenko, VM Tourova, TP Tsapin, A Nealson, KH Kuenen, GJ TI Thioalkalimicrobium cyclicum sp nov and Thioalkalivibrio jannaschii sp nov., novel species of haloalkaliphilic, obligately chemolithoautotrophic sulfur-oxidizing bacteria from hypersaline alkaline Mono Lake (California) SO INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY LA English DT Article DE haloalkaliphilic sulfur-oxidizers; soda lakes; Mono Lake; Thioalkalimicrobium; Thioalkalivibrio ID SODA LAKES; AMMONIA; ENVIRONMENT; DIVERSITY; METHANE AB Two strains of haloalkaliphilic, obligately autotrophic, sulfur-oxidizing bacteria were isolated from the oxygen-sulfide interface water layer of stratified alkaline and saline Mono Lake, California, USA. Strain ALM1(T) was a dominant species in enrichment on moderate-saline, carbonate-buffered medium (0.6 M total Na(+), pH 10) with thiosulfate as an energy source and nitrate as a nitrogen source. Cells of ALM1(T) are open ring-shaped and are non-motile. It has a high growth rate and activity of thiosulfate and sulfide oxidation and very low sulfur-oxidizing activity. Genetic comparison and phylogenetic analysis suggested that ALM1(T) (= DSM 14477(T) = JCM 11371(T)) represents a new species of the genus Thioalkalimicrobium in the gamma-Proteobacteria, for which the name Thioalkalimicrobium cyclicum sp. nov. is proposed. Another Mono Lake isolate, strain ALM2(T), dominated in enrichment on a medium containing 2 M total Na+ (pH 10). It is a motile vibrio which tolerates up to 4 M Na+ and produces a membrane-bound yellow pigment. Phylogenetic analysis placed ALM2(T) as a member of genus Thioaikalivibrio in the gamma-Proteobacteria, although its DNA hybridization with the representative strains of this genus was only about 30%. On the basis of genetic and phenotypic properties, strain ALM2(T) (= DSM 14478(T) = JCM 11372(T)) is proposed as Thioalkalivibrio jannaschii sp. nov. C1 Russian Acad Sci, Inst Microbiol, Moscow 117811, Russia. CALTECH, Jet Prop Lab, Pasadena, CA USA. Delft Univ Technol, Kluyver Inst Technol, NL-2628 BC Delft, Netherlands. RP Sorokin, DY (reprint author), Russian Acad Sci, Inst Microbiol, Prospect 60-Let Octyabrya 7-2, Moscow 117811, Russia. EM soroc@inmi.da.ru NR 23 TC 35 Z9 37 U1 3 U2 11 PU SOC GENERAL MICROBIOLOGY PI READING PA MARLBOROUGH HOUSE, BASINGSTOKE RD, SPENCERS WOODS, READING RG7 1AG, BERKS, ENGLAND SN 1466-5026 J9 INT J SYST EVOL MICR JI Int. J. Syst. Evol. Microbiol. PD MAY PY 2002 VL 52 BP 913 EP 920 DI 10.1099/ijs.0.02034-0 PG 8 WC Microbiology SC Microbiology GA 555ZZ UT WOS:000175824100031 PM 12054257 ER PT J AU Ansari, RR Giblin, FJ King, JF Leverenz, VR Lin, LR AF Ansari, RR Giblin, FJ King, JF Leverenz, VR Lin, LR TI In vivo static and dynamic light scattering (DLS) measurements in lenses of hyperbaric oxygen (HBO)-treated guinea pigs indicate increased scattering and protein size SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract CT Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology CY MAY 05-10, 2002 CL FT LAUDERDALE, FLORIDA SP Assoc Res Vis & Ophthalmol C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Oakland Univ, Eye Res Inst, Rochester, MI 48063 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ASSOC RESEARCH VISION OPHTHALMOLOGY INC PI ROCKVILLE PA 12300 TWINBROOK PARKWAY, ROCKVILLE, MD 20852-1606 USA SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAY PY 2002 VL 43 SU 1 MA 2358 BP U561 EP U561 PG 1 WC Ophthalmology SC Ophthalmology GA 709CF UT WOS:000184606602288 ER PT J AU Fink, W Castano, R AF Fink, W Castano, R TI Automated objective characterization of visual field defects in 3D SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract CT Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology CY MAY 05-10, 2002 CL FT LAUDERDALE, FLORIDA SP Assoc Res Vis & Ophthalmol C1 Univ So Calif, Dept Ophthalmol, Doheny Eye Inst, Keck Sch Med, Los Angeles, CA USA. CALTECH, Jet Prop Lab, Machine Learning Syst Grp, Pasadena, CA USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ASSOC RESEARCH VISION OPHTHALMOLOGY INC PI ROCKVILLE PA 12300 TWINBROOK PARKWAY, ROCKVILLE, MD 20852-1606 USA SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAY PY 2002 VL 43 SU 1 MA 240 BP U45 EP U45 PG 1 WC Ophthalmology SC Ophthalmology GA 709CF UT WOS:000184606600218 ER PT J AU Xing, J AF Xing, J TI Center-surround contrast suppression is constrained by the boundaries of the stimulus SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract CT Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology CY MAY 05-10, 2002 CL FT LAUDERDALE, FLORIDA SP Assoc Res Vis & Ophthalmol C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ASSOC RESEARCH VISION OPHTHALMOLOGY INC PI ROCKVILLE PA 12300 TWINBROOK PARKWAY, ROCKVILLE, MD 20852-1606 USA SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAY PY 2002 VL 43 SU 2 MA 4722 BP U1333 EP U1333 PG 1 WC Ophthalmology SC Ophthalmology GA 709CG UT WOS:000184606701876 ER PT J AU Ward, RR Dawson, WJ Kirschman, RK Mueller, O Patterson, RL Dickman, JE Hammoud, A AF Ward, RR Dawson, WJ Kirschman, RK Mueller, O Patterson, RL Dickman, JE Hammoud, A TI Ge semiconductor devices for cryogenic power electronics - II SO JOURNAL DE PHYSIQUE IV LA English DT Article; Proceedings Paper CT 5th European Workshop on Low Temperature Electronics (WOLTE 5) CY JUN 19-21, 2002 CL GRENOBLE, FRANCE SP Int Natl Polytechn Grenoble, Ville Grenoble, Conseil Gen Isere, Univ Joseph Fourier ID BIPOLAR-TRANSISTORS; TEMPERATURE; PERFORMANCE AB We have begun investigation and development of cryogenic semiconductor power devices (diodes, bipolar transistors and field-effect transistors) based on germanium. The motivation is NASA's interest in electronics that can operate down to deep cryogenic temperatures (as low as approximate to30-40 K) for exploration of the outer planets and other Solar System bodies that present cold environments as well as for future space observatories. There are also potential applications related to cryogenic/superconducting motors and generators and power distribution and storage. We have characterized available Ge diodes and bipolar transistors at cryogenic temperatures and have begun examining NUS (metal-insulator-semiconductor) capacitors on Ge. Our investigations show that all these types of devices can operate from room temperature down to 20 K or lower. C1 GPD Optoelect Corp, Salem, NH 03079 USA. LTE, Ballston Lake, NY 12019 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. QSS Grp Inc, Cleveland, OH USA. RP GPD Optoelect Corp, 7 Manor Pkwy, Salem, NH 03079 USA. NR 12 TC 1 Z9 1 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 1155-4339 J9 J PHYS IV JI J. Phys. IV PD MAY PY 2002 VL 12 IS PR3 BP 67 EP 70 DI 10.1051/jp420020038 PG 4 WC Physics, Multidisciplinary SC Physics GA 575WM UT WOS:000176971500014 ER PT J AU Patterson, RL Hammoud, A Dickman, JE Gerber, S Elbuluk, M Overton, E AF Patterson, RL Hammoud, A Dickman, JE Gerber, S Elbuluk, M Overton, E TI Electronics for deep space cryogenic applications SO JOURNAL DE PHYSIQUE IV LA English DT Article; Proceedings Paper CT 5th European Workshop on Low Temperature Electronics (WOLTE 5) CY JUN 19-21, 2002 CL GRENOBLE, FRANCE SP Int Natl Polytechn Grenoble, Ville Grenoble, Conseil Gen Isere, Univ Joseph Fourier AB Deep space probes and planetary exploration missions require electrical power management and control systems that are capable of efficient and reliable operation in very cold temperature environments. Typically, in deep space probes, heating elements are used to keep the spacecraft electronics near room temperature. The utilization of power electronics designed for and operated at low temperature will contribute to increasing efficiency and improving reliability of space power systems. At NASA Glenn Research Center, commercial-off-the-shelf devices as well as developed components are being investigated for potential use at low temperatures. These devices include semiconductor switching devices, magnetics, and capacitors. Integrated circuits such as digital-to-analog and analog-to-digital converters, DC/DC converters, operational amplifiers, and oscillators are also being evaluated. In this paper, results will be presented for selected analog-to-digital converters, oscillators, DC/DC converters, and pulse width modulation (PWM) controllers. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NASA, QSS Grp Inc, Glenn Res Ctr, Cleveland, OH 44135 USA. NASA, Glenn Res Ctr, ZIN Technol Inc, Cleveland, OH 44135 USA. Univ Akron, Dept Elect Engn, Akron, OH 44325 USA. RP NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 11 TC 4 Z9 4 U1 0 U2 4 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 1155-4339 J9 J PHYS IV JI J. Phys. IV PD MAY PY 2002 VL 12 IS PR3 BP 207 EP 210 DI 10.1051/jp420020068 PG 4 WC Physics, Multidisciplinary SC Physics GA 575WM UT WOS:000176971500044 ER PT J AU Patnaik, SN Coroneos, RM Hopkins, DA Lavelle, TM AF Patnaik, SN Coroneos, RM Hopkins, DA Lavelle, TM TI Lessons learned during solutions of multidisciplinary design optimization problems SO JOURNAL OF AIRCRAFT LA English DT Article ID STRUCTURAL OPTIMIZATION AB Optimization research at NASA Glenn Research Center has addressed design of structures, aircraft, and aircraft engines. Four issues were encountered during the solution of the multidisciplinary problems. Strategy adapted for their resolution is discussed. Design optimization produced an inefficient design for an engine component. The deficiency was overcome through animation and weight was reduced by 20%. Infeasibility encountered in aircraft and engine design problems was alleviated by cascading multiple algorithms. The cascade strategy reduced aircraft weight and produced a feasible design. Profile optimization converged to an irregular shape for a beam. A regular shape was restored through engineering intuition, but the optimum freight was not changed. The subproblem optimization for a cylindrical shell converged to a design that might be difficult to manufacture. This issue remains a challenge. The issues are illustrated through design of an engine component, synthesis of a subsonic aircraft, operation optimization of a supersonic engine, design of a wave-rotor-topping device, profile optimization of a beam, and design of a cylindrical shell. A multidisciplinary problem might not Yield an optimum solution in the first attempt. However, the combined effort of designers and researchers can bring design optimization from academia to industry. C1 Ohio Aersp Inst, Brookpark, OH 44142 USA. NASA John H Glenn Res Ctr, Cleveland, OH 44135 USA. RP Patnaik, SN (reprint author), Ohio Aersp Inst, Brookpark, OH 44142 USA. NR 32 TC 1 Z9 1 U1 0 U2 5 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 2002 VL 39 IS 3 BP 386 EP 393 DI 10.2514/2.2959 PG 8 WC Engineering, Aerospace SC Engineering GA 558GQ UT WOS:000175958300002 ER PT J AU Greenman, RM Stepniewski, SW Jorgensen, CC Roth, KR AF Greenman, RM Stepniewski, SW Jorgensen, CC Roth, KR TI Designing compact feedforward neural models with small training data sets SO JOURNAL OF AIRCRAFT LA English DT Article ID UPWIND DIFFERENCING SCHEME; NAVIER-STOKES EQUATIONS; NETWORKS; LIFT AB A new hybrid method is presented for designing feedforward, backpropagation neural models with small training data sets. The method minimizes the generalization error, a fundamental quantity that characterizes the effectiveness of the regression models. It combines into one framework a bootstrap technique that estimates network generalization performance and a collection of stochastic and deterministic optimization techniques that adjust neural network interconnection geometry. The approach is derived as a form of multi-objective optimization strategy. This allows for more direct treatment of contradictory design criteria than traditionally employed single-objective techniques. A stochastic optimization method such as a genetic algorithm is used to select activation functions for hidden-layer nodes, whereas fast deterministic techniques, optimal brain surgeon and singular value decomposition, are used to perform connection and node pruning. The method is demonstrated by optimizing neural networks that model the high-lift aerodynamics of a multi-element airfoil. The neural model is constructed using a small computational data set consisting of 227 data points. In the numerical experiments presented, the solutions produced by, this hybrid approach exhibit an improvement in the generalization ability on the average of five to six times when compared to the pruned models with only one type of activation function. When traditional fully connected networks with hyperbolic tangent activation functions are considered, the improvement in the generalization performance of the new models is even greater. The neural models exhibit superior generalization qualities that are virtually impossible to find by manual trial-and-error approaches. C1 Lawrence Livermore Natl Lab, Livermore, CA 94551 USA. SONY Elect, San Jose, CA 95134 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Greenman, RM (reprint author), Lawrence Livermore Natl Lab, Livermore, CA 94551 USA. NR 23 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAY-JUN PY 2002 VL 39 IS 3 BP 452 EP 459 DI 10.2514/2.2950 PG 8 WC Engineering, Aerospace SC Engineering GA 558GQ UT WOS:000175958300011 ER PT J AU Leon, R Chaparro, S Johnson, SR Navarro, C Jin, X Zhang, YH Siegert, J Marcinkevicius, S Liao, XZ Zou, J AF Leon, R Chaparro, S Johnson, SR Navarro, C Jin, X Zhang, YH Siegert, J Marcinkevicius, S Liao, XZ Zou, J TI Dislocation-induced spatial ordering of InAs quantum dots: Effects on optical properties SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID MISFIT DISLOCATIONS; ISLANDS; SUPERLATTICES; TRANSITIONS; LASERS AB Misfit dislocations were used to modify the surface morphology and to attain spatial ordering of quantum dots (QDs) by molecular beam epitaxy. Effects of anneal time and temperature on strain-relaxed InxGa1-xAs/GaAs layers and subsequent spatial ordering of InAs QDs were investigated. Photoluminescence (PL) and time-resolved PL was used to study the effects of increased QD positional ordering, increased QD uniformity, and their proximity to dislocation arrays on their optical properties. Narrower inhomogeneous PL broadening from the QDs ordered on dislocation arrays were observed, and differences in PL dynamics were found. (C) 2002 American Institute of Physics. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Arizona State Univ, Ctr Solid State Elect Res, Tempe, AZ 85287 USA. Arizona State Univ, Dept Elect Engn, Tempe, AZ 85287 USA. Royal Inst Technol, Dept Microelect & Informat Technol, Opt Sect, S-10044 Stockholm, Sweden. Univ Sydney, Australian Key Ctr Microscopy & Microanal, Sydney, NSW 2006, Australia. RP Leon, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Liao, Xiaozhou/B-3168-2009; Zou, Jin/B-3183-2009 OI Liao, Xiaozhou/0000-0001-8565-1758; Zou, Jin/0000-0001-9435-8043 NR 19 TC 29 Z9 30 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD MAY 1 PY 2002 VL 91 IS 9 BP 5826 EP 5830 DI 10.1063/1.1467963 PG 5 WC Physics, Applied SC Physics GA 542WR UT WOS:000175069000044 ER PT J AU Delzeit, L McAninch, I Cruden, BA Hash, D Chen, B Han, J Meyyappan, M AF Delzeit, L McAninch, I Cruden, BA Hash, D Chen, B Han, J Meyyappan, M TI Growth of multiwall carbon nanotubes in an inductively coupled plasma reactor SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID CHEMICAL-VAPOR-DEPOSITION; SINGLE; NANOFIBERS; CVD AB A high density plasma from a methane-hydrogen mixture is generated in an inductively coupled plasma reactor, and multiwalled carbon nanotubes (MWNTs) are grown on silicon substrates with multilayered Al/Fe catalysts. The nanotubes are vertically aligned, and the alignment is better than the orientation commonly seen in thermally grown samples. A detailed parametric study varying inductive power, pressure, temperature, gas composition, catalyst thickness, and power to the substrate is undertaken. Transmission electron microscopy and Raman spectroscopy are used to characterize the nanotubes. Emission spectroscopy and a global model are used to characterize the plasma. The power in the lower electrode holding the substrate influences the morphology and results in a transition from MWNTs to nanofibers as the power is increased. (C) 2002 American Institute of Physics. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Delzeit, L (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. OI McAninch, Ian/0000-0002-9190-2936 NR 25 TC 169 Z9 173 U1 2 U2 39 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD MAY 1 PY 2002 VL 91 IS 9 BP 6027 EP 6033 DI 10.1063/1.1465101 PG 7 WC Physics, Applied SC Physics GA 542WR UT WOS:000175069000074 ER PT J AU Lee, SMC Williams, WJ Schneider, SM AF Lee, SMC Williams, WJ Schneider, SM TI Role of skin blood flow and sweating rate in exercise thermoregulation after bed rest SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE core temperature; intestinal temperature; microgravity; spaceflight ID HEAD-DOWN TILT; CUTANEOUS VASODILATION; RESISTANCE EXERCISE; SUBMAXIMAL EXERCISE; TEMPERATURE; PERFORMANCE; RESPONSES; HUMANS; SYSTEM; MEN AB Two potential mechanisms, reduced skin blood flow (SBF) and sweating rate (SR), may be responsible for elevated intestinal temperature (T-in) during exercise after bed rest and space-flight. Seven men underwent 13 days of 6degrees head-down bed rest. Pre- and post-bed rest, subjects completed supine sub-maximal cycle ergometry (20 min at 40% and 20 min at 65% of pre-bed rest supine peak exercise capacity) in a thermoneutral room. After bed rest, T-in was elevated at rest (+0.3 +/- 0.12degreesC) and at the end of exercise (+0.33 +/- 0.07degreesC). Percent increase in SBF during exercise was less after bed rest (211 +/- 53 vs. 96 +/- 31%; P less than or equal to 0.05), SBF/T-in threshold was greater (37.09 +/- 0.16 vs. 37.33 +/- 0.13degreesC; P less than or equal to 0.05), and slope of SEF/T-in. tended to be reduced (536 +/- 184 vs. 201 +/- 46%/degreesC; P = 0.08). SR/T-in threshold was delayed (37.06 +/- 0.11 vs. 37.34 +/- 0.06degreesC; P less than or equal to 0.05), but the slope of SR/T-in (3.45 +/- 1.22 vs. 2.58 +/- 0.71 mg.min(-1).cm(-2.)degreesC(-1)) and total sweat loss (0.42 +/- 0.06 vs. 0.44 +/- 0.08 kg) were not changed. The higher resting and exercise T-in and delayed onset of SBF and SR suggest a centrally mediated elevation in the thermoregulatory set point during bed rest exposure. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Wyle Labs, Life Sci Syst & Serv Div, Houston, TX 77058 USA. RP Schneider, SM (reprint author), Univ New Mexico, Dept Exercise Sci, Johnson Ctr 126, Albuquerque, NM 87131 USA. FU NCRR NIH HHS [M01 RR-00073] NR 44 TC 18 Z9 21 U1 0 U2 3 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD MAY PY 2002 VL 92 IS 5 BP 2026 EP 2034 DI 10.1152/japplphysiol.00105.2001 PG 9 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 544WP UT WOS:000175184900032 PM 11960954 ER PT J AU Li, L Im, E Durden, SL Haddad, ZS AF Li, L Im, E Durden, SL Haddad, ZS TI A surface wind model-based method to estimate rain-induced radar path attenuation over ocean SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID MEASURING MISSION TRMM; PRECIPITATION RADAR; CROSS-SECTION; PROFILING ALGORITHM; SCATTEROMETER WINDS; MICROWAVE IMAGER; KU-BAND; RETRIEVALS; SATELLITE; GHZ AB The rainfall retrieved using the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) depends on estimating the radar signal path-integrated attenuation using the surface reference technique (SRT). This technique assumes uniform ocean surface backscattering background at precipitation scale and attributes the difference in measured surface backscattering cross sections inside and outside of storms to path-integrated attenuation. Since surface wind is the major environmental variable that controls the strength of the ocean backscattering, it is very desirable to examine the impact of surface wind variation on the retrieved attenuation. To this end, we examined the feasibility of retrieving ocean surface winds from TRMM PR data for the benefit of the surface reference technique. A geophysical model function, a forward model, is developed based on ocean surface wind speed retrieved from TRMM Microwave Imager (TMI) data. A fieldwise wind-retrieval procedure, an inverse model, is formulated using maximum likelihood estimation. Comparison of the conventional SRT with the path-integrated radar attenuation derived using the wind field approach shows an rms difference of 12 dB, which is consistent with previous study based on data collected from the Jet Propulsion Laboratory Airborne Rain-Mapping Radar (ARMAR). In addition, there is excellent agreement between wind fields retrieved from TRMM PR and TMI data. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Im, E (reprint author), CALTECH, Jet Prop Lab, Mail Stop 300-227,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 31 TC 18 Z9 18 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD MAY PY 2002 VL 19 IS 5 BP 658 EP 672 DI 10.1175/1520-0426(2002)019<0658:ASWMBM>2.0.CO;2 PG 15 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 547BG UT WOS:000175312200009 ER PT J AU Zibordi, G Hooker, SB Berthon, JF D'Alimonte, D AF Zibordi, G Hooker, SB Berthon, JF D'Alimonte, D TI Autonomous above-water radiance measurements from an offshore platform: A field assessment experiment SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID REMOTE-SENSING REFLECTANCE; IN-WATER; ATMOSPHERIC CORRECTION; OPTICAL MEASUREMENTS; SEAWIFS DATA; OCEAN COLOR; VALIDATION AB An autonomous system for making above-water radiance measurements has been produced by adding a new measurement scenario to a CIMEL CE-318 sun photometer. The new system, called the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Photometer Revision for Incident Surface Measurement (SeaPRISM), combines the normal CE-318 capability for measuring direct sun irradiance and sky radiance, with a new capability for measuring above-water radiance for the retrieval of water-leaving radiance. The system has been extensively tested during several measurement periods over a 1-yr time frame from August 1999 to July 2000 under various sun elevations along with different atmospheric, seawater, and sea-state conditions. The field assessment of the new instrument was conducted at an oceanographic tower located in the northern Adriatic Sea within the framework of measurement campaigns aimed at supporting ocean color calibration and validation activities. Sample data at 440, 500, 670, 870, and 1020 nm were collected at azimuth and zenith angles satisfying the SeaWiFS Ocean Optics Protocols (and successive revisions) for above-water radiance measurements. Specifically, data were collected with azimuth angles of 908 with respect to the sun plane, and with nadir viewing angles of 308, 408, and 458 for above-water measurements and of 1508, 1408, and 1358 for sky radiance measurements, respectively (the latter are needed for glint correction of the data). The intercomparison between water-leaving radiances computed from SeaPRISM measurements and those obtained from in-water optical profiles taken with the Wire-Stabilized Profiling Environmental Radiometer (WiSPER) system were performed using 113 coincident sets of measurements collected during clear-sky conditions. The SeaPRISM measurements taken at 408 and corrected for glint effects using different methods show the best agreement with WiSPER data. The intercomparisons exhibit average absolute unbiased percent differences, generally lower than 10% at 440 and 500 nm, and lower than 26% at 670 nm. The intercomparison of the water-leaving radiance ratio L-W(440)/L-W(500) from SeaPRISM data taken at 408 and WiSPER data exhibits average absolute unbiased percent differences lower than 5.6%. C1 Joint Res Ctr European Union, Space Applicat Inst, I-21020 Ispra, Italy. NASA, Lab Hydrospher Proc, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Zibordi, G (reprint author), Joint Res Ctr European Union, Space Applicat Inst, I-21020 Ispra, Italy. RI Hooker, Stanford/E-2162-2012; D'Alimonte, Davide/I-6531-2013 OI D'Alimonte, Davide/0000-0001-7217-7057 NR 32 TC 36 Z9 36 U1 0 U2 4 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 MAY PY 2002 VL 19 IS 5 BP 808 EP 819 DI 10.1175/1520-0426(2002)019<0808:AAWRMF>2.0.CO;2 PG 12 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 547BG UT WOS:000175312200020 ER PT J AU de Gonzalez, ALC Gonzalez, WD Tsurutani, BT Silbergleit, VM AF de Gonzalez, ALC Gonzalez, WD Tsurutani, BT Silbergleit, VM TI Letter to the editor - Authors' response SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Letter ID GEOMAGNETIC-ACTIVITY C1 INPE, BR-12201970 Sao Jose Dos Campos, Brazil. CALTECH, Jet Prop Lab, Pasadena, CA USA. Univ Buenos Aires, Fac Ingn, Buenos Aires, DF, Argentina. RP de Gonzalez, ALC (reprint author), INPE, Caixa Postal 515, BR-12201970 Sao Jose Dos Campos, Brazil. NR 3 TC 0 Z9 0 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 2002 VL 64 IS 7 BP 871 EP 871 AR PII S1364-6826(02)00081-0 PG 1 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 569LX UT WOS:000176604800009 ER PT J AU Mlynczak, M AF Mlynczak, M TI A comparison of space-based observations of the energy budgets of the mesosphere and the troposphere SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT Workshop on Planetary Scale Mesopause Observing System (PSMOS 2000) CY MAY 23-26, 2000 CL UNIV TORONTO, SANDFOR FLEMING BLD, TORONTO, CANADA HO UNIV TORONTO, SANDFOR FLEMING BLD DE energy budget; mesosphere; troposhere; satellites ID STRATOSPHERIC HEAT-BUDGET; EARTHS RADIATION BUDGET; NON-LTE CONDITIONS; MU-M; SPECTROSCOPIC REQUIREMENTS; DETAILED EVALUATION; MIDDLE ATMOSPHERE; WATER-VAPOR; SATELLITE; AIRGLOW AB The flow of energy from the Sun, through the atmosphere, to the Earth's surface and oceans, and ultimately back to space, controls the weather and climate of the planet. Since the dawn of the Space Age, the energy balance of the planet has been measured by orbiting satellites. Over the past 40 years the technology and the scientific understanding have developed to the point where we can measure not only the energy balance of the entire Earth and its atmosphere but also of the various regions of the atmosphere including the troposphere, the stratosphere, and the mesosphere. With the planned space-based observations of the sources and sinks of energy in the mesosphere, the energy balance of this region of the atmosphere may soon be better understood from observations than the energy balance of the troposphere on seasonal to annual timescales. Fundamental to this assertion is the fact that the primary sources and sinks of radiative and chemical potential energy, the thermal structure, and the winds in the mesosphere are to be directly observed by space-based instrumentation at high vertical resolution, in contrast to the troposphere. In this paper we review some of the planned measurements of the energy budgets of the atmosphere from existing and future space-based platforms. We particularly show how the airglow can be used to determine many of the key sources of energy in the mesosphere. These ideas provide the basis for interpretation of new space-based measurements of the mesosphere planned in the near future. Published by Elsevier Science Ltd. C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Mlynczak, M (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, Mail Stop 420, Hampton, VA 23681 USA. RI Mlynczak, Martin/K-3396-2012 NR 36 TC 6 Z9 6 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-JUL PY 2002 VL 64 IS 8-11 BP 877 EP 887 AR PII S1364-6826(02)00043-3 DI 10.1016/S1364-6826(02)00043-3 PG 11 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 571ZJ UT WOS:000176748800002 ER PT J AU Evans, GL Morey-Holton, E Turner, RT AF Evans, GL Morey-Holton, E Turner, RT TI The effects of a subanabolic dose of parathyroid hormone (PTH) and Raloxifene on hindlimb unloaded male rats SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 Mayo Clin, Rochester, MN USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC BONE & MINERAL RES PI WASHINGTON PA 2025 M ST, N W, STE 800, WASHINGTON, DC 20036-3309 USA SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD MAY PY 2002 VL 17 IS 5 MA P34 BP 958 EP 958 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA 545QP UT WOS:000175229100104 ER PT J AU Risbey, JS Lamb, PJ Miller, RL Morgan, MC Roe, GH AF Risbey, JS Lamb, PJ Miller, RL Morgan, MC Roe, GH TI Exploring the structure of regional climate scenarios by combining synoptic and dynamic guidance and GCM output SO JOURNAL OF CLIMATE LA English DT Article ID SEA-SURFACE TEMPERATURE; NORTH-AMERICAN PRECIPITATION; UNITED-STATES; STATIONARY WAVES; STORM-TRACKS; SOUTHERN OSCILLATION; GEOPOTENTIAL HEIGHT; TROPICAL PACIFIC; INTERDECADAL VARIABILITY; ATMOSPHERIC CO2 AB A set of regional climate scenarios is constructed for two study regions in North America using a combination of GCM output and synoptic-dynamical reasoning. The approach begins by describing the structure and components of a climate scenario and identifying the dynamical determinants of large-scale and regional climate. Expert judgement techniques are used to categorize the tendencies of these elements in response to increased greenhouse forcing in climate model studies. For many of the basic dynamical elements, tendencies are ambiguous, and changes in sign (magnitude, position) can usually be argued in either direction. A set of climate scenarios is produced for winter and summer, emphasizing the interrelationships among dynamical features, and adjusting GCM results on the basis of known deficiences in GCM simulations of the dynamical features. The scenarios are qualitative only, consistent with the level of precision afforded by the uncertainty in understanding of the dynamics, and in order to provide an outline of the reasoning and chain of contingencies on which the scenarios are based. The three winter scenarios outlined correspond roughly to a north-south displacement of the stationary wave pattern, to an increase in amplitude of the pattern, and to a shift in phase of the pattern. These scenarios illustrate that small changes in the dynamics can lead to large changes in regional climate in some regions, while other regions are apparently insensitive to some of the large changes in dynamics that can be plausibly hypothesized. The dynamics of summer regional climate changes are even more difficult to project, though thermodynamic considerations allow some more general conclusions to be reached in this season. Given present uncertainties it is difficult to constrain regional climate projections. C1 Monash Univ, Sch Math Sci, Clayton, Vic 3800, Australia. Univ Oklahoma, Cooperat Inst Mesoscale Meteorol Studies, Norman, OK 73019 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Univ Wisconsin, Dept Atmospher & Ocean Sci, Madison, WI USA. Univ Washington, Quaternary Res Ctr, Seattle, WA 98195 USA. RP Risbey, JS (reprint author), Monash Univ, Sch Math Sci, POB 28M, Clayton, Vic 3800, Australia. RI Miller, Ron/E-1902-2012; Risbey, James/M-8419-2013 OI Risbey, James/0000-0003-3202-9142 NR 81 TC 15 Z9 15 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 MAY PY 2002 VL 15 IS 9 BP 1036 EP 1050 DI 10.1175/1520-0442(2002)015<1036:ETSORC>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 541XR UT WOS:000175012300008 ER PT J AU Ortiz, RM Wade, CE Costa, DP Ortiz, CL AF Ortiz, RM Wade, CE Costa, DP Ortiz, CL TI Renal effects of fresh water-induced hypo-osmolality in a marine adapted seal SO JOURNAL OF COMPARATIVE PHYSIOLOGY B-BIOCHEMICAL SYSTEMIC AND ENVIRONMENTAL PHYSIOLOGY LA English DT Article DE aldosterone; kidney; marine mammals; osmoregulation; vasopressin ID ANGIOTENSIN-ALDOSTERONE SYSTEM; ATRIAL-NATRIURETIC-PEPTIDE; VASOPRESSIN; INCREASES; HUMANS; PUPS; EXCRETION; RATS; LOAD AB With few exceptions, marine mammals are not exposed to fresh water; however quantifying the endocrine and renal responses of a marine-adapted mammal to the infusion of fresh water could provide insight on the evolutionary adaptation of kidney function and on the renal capabilities of these mammals. Therefore, renal function and hormonal changes associated with fresh water-induced diuresis were examined in four, fasting northern elephant seal (Mirounga angustirostris) (NES) pups. A series of plasma samples and 24-h urine voids were collected prior to (control) and after the infusion of water. Water infusion resulted in an osmotic diuresis associated with an increase in glomerular filtration rate (GFR), but not an increase in free water clearance. The increase in excreted urea accounted for 96% of the increase in osmotic excretion. Following infusion of fresh water, plasma osmolality and renin activity decreased, while plasma aldosterone increased. Although primary regulators of aldosterone release (Na+, K+ and angiotensin II) were not significantly altered in the appropriate directions to individually stimulate aldosterone secretion, increased aldosterone may have resulted from multiple, non-significant changes acting in concert. Aldosterone release may also be hypersensitive to slight reductions in plasma Na+, which may be an adaptive mechanism in a species not known to drink seawater. Excreted aldosterone and urea were correlated suggesting aldosterone may regulate urea excretion during hypo-osmotic conditions in NES pups. Urea excretion appears to be a significant mechanism by which NES pups sustain electrolyte resorption during conditions that can negatively affect ionic homeostasis such as prolonged fasting. C1 Univ Calif Santa Cruz, Dept Biol, Santa Cruz, CA 95064 USA. NASA, Ames Res Ctr, Neuroendocrinol Lab, Div Life Sci, Moffett Field, CA 94035 USA. RP Ortiz, RM (reprint author), Univ Calif Santa Cruz, Dept Biol, A316 Earth & Marine Sci, Santa Cruz, CA 95064 USA. FU NIGMS NIH HHS [GM 58903-01] NR 39 TC 6 Z9 6 U1 1 U2 7 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0174-1578 J9 J COMP PHYSIOL B JI J. Comp. Physiol. B-Biochem. Syst. Environ. Physiol. PD MAY PY 2002 VL 172 IS 4 BP 297 EP 307 DI 10.1007/s00360-002-0254-3 PG 11 WC Physiology; Zoology SC Physiology; Zoology GA 568DY UT WOS:000176528200003 PM 12037592 ER PT J AU Stone, RP O'Clair, CE AF Stone, RP O'Clair, CE TI Behavior of female Dungeness crabs, Cancer magister, in a glacial southeast Alaska estuary: Homing, brooding-site fidelity, seasonal movements, and habitat use SO JOURNAL OF CRUSTACEAN BIOLOGY LA English DT Article ID HOME-RANGE; NORTHERN CALIFORNIA; EGGS; CRUSTACEANS; MORTALITY AB Aspects of the behavior of ovigerous Dungeness crabs (Cancer magister) were studied in Fritz Cove, Alaska. To test fidelity and homing ability of crabs to their brooding site. we ultrasonically tagged eight ovigerous crabs and transplanted them 1.4 km from their brooding site. Eight ultrasonically tagged control crabs v ere returned to the brooding site. Crab movements were subsequently monitored weekly from late February to October to determine activity patterns and seasonal shifts in depth distribution and habitat use. Seven females transplanted away from the brooding site homed back to that site within 13 to 20 d. Ovigerous female crabs showed fidelity to the head of the cove and ranged a maximum of 3.4 km. Crabs had distinct seasonal patterns of depth distribution. habitat use, and activity which were related to reproductive status. The general pattern for female crabs was: (1) a relatively inactive period during winter and early spring at depths greater than -16 m; ovigerous crabs were typically buried during this period in a dense aggregation: (2) an abrupt movement into shallow water (less than -10 m) during mid-April and residence there until late June; this movement was coincident with the spring phytoplankton bloom and initiation of larval hatching and (3) increased activity beginning in July with movement back to deeper water presumably to forage. Females that molted prior to oviposition did so between late May and September. Females occupied depths between +1.6 and -107.3 m. Home ranges were small (<4% of the total cove habitat) and varied with crab sized smaller crabs had larger home ranges. Ovigerous females brooded embryos in a small, discrete area of unconsolidated, homogeneous, fine sand. These sediments were also highly permeable, Annual use of the main brooding area was documented for a 12-year period and emphasizes the importance of this essential habitat. C1 Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Auke Bay Lab, Juneau, AK 99801 USA. RP Stone, RP (reprint author), Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Auke Bay Lab, 11305 Glacier Highway, Juneau, AK 99801 USA. EM bob.stone@noaa.gov NR 36 TC 14 Z9 17 U1 1 U2 9 PU CRUSTACEAN SOC PI SAN ANTONIO PA 840 EAST MULBERRY, SAN ANTONIO, TX 78212 USA SN 0278-0372 J9 J CRUSTACEAN BIOL JI J. Crustac. Biol. PD MAY PY 2002 VL 22 IS 2 BP 481 EP 492 DI 10.1651/0278-0372(2002)022[0481:BOFDCC]2.0.CO;2 PG 12 WC Marine & Freshwater Biology SC Marine & Freshwater Biology GA 556TY UT WOS:000175866100028 ER PT J AU Lee, CP Chernov, AA AF Lee, CP Chernov, AA TI Solutal convection around growing protein crystals and diffusional purification in Space SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE biomaterials; convection; diffusion; impurities; roughening; lysozyme; proteins ID TETRAGONAL LYSOZYME CRYSTALS; GROWTH-KINETICS; IMPURITY; CRYSTALLIZATION; TRANSPORT; DEFECTS AB Convective and diffusional mass transport to an isolated crystal growing from solution., with slow linear interface kinetics, is considered analytically as a generic scaling model. We focus on the interface kinetics which is slow as compared to the diffusion mass transport which is typical of protein crystal growth, Independently, full-scale numerical solutions of transport equations around a cylindrical crystal, at the center of the bottom of a cylindrical cell filled with the solution, are found. The two approaches give results that agree over a wide range of parameters, providing dimensionless relationships that allow predictions of the contribution of convection and diffusion to mass transport. Requirements for microgravity level in Space experiments to achieve diffusional mass transport are estimated on the basis of these relationships. Coefficients of impurity distribution between a growing crystal and its solution, under the influences of convection and diffusion around the crystal, were numerically evaluated as functions of time. The results provide further support for the hypothesis concerning the role of the impurity depletion zone in the purification of a growing crystal. They also reveal that in general, the impurity distribution within the crystal is not homogeneous due to convection. The effects of various factors on growth kinetics and crystal purity are considered. (C) 2002 Published by Elsevier Science B.V. C1 NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35806 USA. RP Chernov, AA (reprint author), NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, 4950 Corp Dr,Suite 100, Huntsville, AL 35806 USA. NR 31 TC 19 Z9 20 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD MAY PY 2002 VL 240 IS 3-4 BP 531 EP 544 AR PII S0022-0248(02)00909-0 DI 10.1016/S0022-0248(02)00909-0 PG 14 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 557MH UT WOS:000175912000032 ER PT J AU Abrahamson, J Marshall, J AF Abrahamson, J Marshall, J TI Permanent electric dipoles on gas-suspended particles and the production of filamentary aggregates SO JOURNAL OF ELECTROSTATICS LA English DT Article DE particle chains; permanent electric dipoles; triboelectrification; metal oxidation; ball aggregation ID NANOPARTICLES; SIMULATIONS; OXIDATION; ADHESION; MOMENT; TONER; SIO2 AB The shapes of an aggregate of particles is the result of the force acting in its formation, and in turn strongly influences the properties of the aggregate. In this paper we investigate the forces acting on particles in the gas phase to form extended chains. Electrical charge on the particles is normally invoked to explain these chains, in the form of charges of opposite sign on different particles, and dipoles composed of separated persistent charges of opposite sign on the same particle. We discuss (a) contract charging for micron sized dielectric particles and (b) chemical charging during growth of oxide layers on metal nanoparticles, noting experimental evidence supporting the existence of dipoles. A mapping of different aggregate forms from dipolar particles has been attempted, including magnetic and electrical dipoles, taking account of concentration, dipole strength and time, all in dimensionless form. Turbulent diffusion is found important with flow situations. Aggregation of dipole particle chains into ball-like objects is mentioned with respect to ball lightning. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Univ Canterbury, Dept Chem & Proc Engn, Christchurch 1, New Zealand. NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. RP Abrahamson, J (reprint author), Univ Canterbury, Dept Chem & Proc Engn, Private Bag 4800, Christchurch 1, New Zealand. NR 48 TC 9 Z9 9 U1 2 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0304-3886 J9 J ELECTROSTAT JI J. Electrost. PD MAY PY 2002 VL 55 IS 1 BP 43 EP 63 DI 10.1016/S0304-3886(01)00183-8 PG 21 WC Engineering, Electrical & Electronic SC Engineering GA 536CE UT WOS:000174682500003 ER PT J AU Freund, F AF Freund, F TI Charge generation and propagation in igneous rocks SO JOURNAL OF GEODYNAMICS LA English DT Article; Proceedings Paper CT International Symposium on The Recent Aspects of Electromagnetic Variations Related with Earthquakes CY DEC 20-21, 1999 CL TOKYO, JAPAN ID MAGNETIC-FIELD MEASUREMENTS; LOMA-PRIETA EARTHQUAKE; ELECTRICAL-CONDUCTIVITY; MAGNESIUM-OXIDE; SIGNALS; FRACTURE; PRECURSORS; IONOSPHERE; PREDICTION; EMISSION AB Various electrical phenomena have been reported prior to or concurrent with earthquakes such as resistivity changes, ground potentials, electromagnetic (EM), and luminous signals. Doubts have been raised as to whether some of these phenomena are real and indeed precursory. One of the reasons for uncertainty is that, despite decades of intense work, there is still no physically coherent model. Using low- to medium-velocity impacts to measure electrical signals with microsecond time resolution, it has now been observed that when dry gabbro and diorite cores are impacted at relatively low velocities, similar to100 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 dry granite block is impacted at higher velocity, similar to1.5 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. Before activation, the positive holes lay dormant in the 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, O3X-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 by microfracturing. Depending on where in the stressed rock volume the charge carriers are activated, they will form rapidly moving or fluctuating charge clouds that may 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. (C) 2002 Published by Elsevier Science Ltd. C1 San Jose State Univ, Dept Phys, San Jose, CA 95192 USA. NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. RP Freund, F (reprint author), San Jose State Univ, Dept Phys, San Jose, CA 95192 USA. EM ffreund@mail.arc.nasa.gov NR 78 TC 60 Z9 65 U1 1 U2 8 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0264-3707 J9 J GEODYN JI J. Geodyn. PD MAY-JUL PY 2002 VL 33 IS 4-5 SI SI BP 543 EP 570 AR PII S0264-3707(02)00015-7 DI 10.1016/S0264-3707(02)00015-7 PG 28 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 573EY UT WOS:000176817400014 ER PT J AU Herber, A Thomason, LW Gernandt, H Leiterer, U Nagel, D Schulz, KH Kaptur, J Albrecht, T Notholt, J AF Herber, A Thomason, LW Gernandt, H Leiterer, U Nagel, D Schulz, KH Kaptur, J Albrecht, T Notholt, J TI Continuous day and night aerosol optical depth observations in the Arctic between 1991 and 1999 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article DE aerosols and particles; instruments and techniques ID POLAR-REGIONS; STRATOSPHERIC AEROSOL; ATMOSPHERIC AEROSOL; AIR-POLLUTION; HAZE; MODEL; APPROXIMATION; PERTURBATION; SPITSBERGEN; VALIDATION AB [1] Ground-based measurements of total aerosol optical depth (AOD), e. g., tropospheric and stratospheric aerosol, have been established at the Koldewey station in Ny-Alesund, Spitzbergen (Norway, 78.95degreesN, 11.93degreesE), since 1991. The basic instrumentation is a multichannel photometer using sunlight. New instruments have been developed to extend the measurement period to polar night. The new instruments are a Sun and Moon photometer (1995) and a star photometer (1996). The instruments and applied methods for aerosol optical depth retrieval for Sun, Moon, and star measurements are briefly discussed. The year-round measurements made it possible to study in detail the interannual and seasonal variations of total AOD in the Arctic. The seasonal variation and the long-term trend of tropospheric aerosol optical depth are discussed, taking into account the stratospheric AOD measured by the Stratospheric Aerosol and Gas Experiment (SAGE II). The lowest tropospheric aerosol optical depth values occur in late summer and fall. Each year, strong Arctic haze events were recorded not only during spring but also in late winter as the first star photometer measurements clearly show. Five-day backward trajectories were used to analyze possible sources for high tropospheric AOD. Elevated tropospheric aerosol optical depth appears for northeasterly, easterly, or westerly winds. Finally, the long-term changes of tropospheric AOD have been assessed. A small positive trend of the tropospheric aerosol optical depth is found for the vicinity of Spitzbergen during the measurement period. C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. Deutsch Wetterdienst, Meteorol Observ Lindenberg, D-15864 Lindenberg, Germany. GKSS Forschungszentrum Geesthacht GmbH, Inst Atmospharenphys, D-21502 Geesthacht, Germany. Dr Schulz & Partner GmbH Buckow, D-15848 Buckow, Germany. Fdn Polar & Marine Res, Alfred Wegener Inst, D-14473 Potsdam, Germany. Fdn Polar & Marine Res, Alfred Wegener Inst, D-27515 Bremerhaven, Germany. RP Herber, A (reprint author), Fdn Polar & Marine Res, Alfred Wegener Inst, Postfach 120161, D-27515 Bremerhaven, Germany. EM aherber@awi-bremerhaven.de; l.w.thomason@larc.nasa.gov; hgernandt@awi-bremerhaven.de; Leiterer@mol.dwd.d400.de; dagmar.nagel@gkss.de; drschulz@drschulz.com; jasmine.kaptur@zsw-bw.de; talbrecht@awi-potsdam.de; jnotholt@awi-potsdam.de RI Notholt, Justus/P-4520-2016 OI Notholt, Justus/0000-0002-3324-885X NR 56 TC 64 Z9 67 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 PY 2002 VL 107 IS D10 AR 4097 DI 10.1029/2001JD000536 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 609HA UT WOS:000178896500009 ER PT J AU Jacob, DJ Field, BD Jin, EM Bey, I Li, QB Logan, JA Yantosca, RM Singh, HB AF Jacob, DJ Field, BD Jin, EM Bey, I Li, QB Logan, JA Yantosca, RM Singh, HB TI Atmospheric budget of acetone SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article DE acetone; tropospheric chemistry; propane; inverse modeling; sea-air exchange; biosphere-atmosphere interactions ID VOLATILE ORGANIC-COMPOUNDS; SOUTHEASTERN UNITED-STATES; CHEMICAL-TRANSPORT MODEL; POLAR SUNRISE EXPERIMENT; AIR-SEA EXCHANGE; CARBONYL-COMPOUNDS; NONMETHANE HYDROCARBONS; UPPER TROPOSPHERE; LOWER STRATOSPHERE; MARINE TROPOSPHERE AB [1] The atmospheric budget and distribution of acetone are investigated by using a priori estimates of sources and sinks to constrain a global three-dimensional atmospheric model simulation and then using atmospheric observations from 14 surface sites and 5 aircraft missions to improve these estimates through an inversion analysis. Observations over the South Pacific imply a large photochemical marine source of acetone, either from the ocean or from marine organic aerosol. Low concentrations of acetone measured at European sites in winter-spring and in the Arctic in summer suggest a large microbial ocean sink. The summer-to-fall decrease of concentrations observed in Europe argues against a large source from plant decay. Continental observations in the tropics and at northern midlatitudes in summer imply a large source from terrestrial vegetation. Observations in the Northern Hemisphere outside summer imply a large source from atmospheric oxidation of anthropogenic isoalkanes (propane, isobutane, isopentane). Model simulation of isoalkanes and comparison to observations yields best global emission estimates of 12 Tg C yr(-1) for propane (including only 0.6 Tg C yr(-1) from biomass burning), 3.6 Tg C yr(-1) for isobutane, and 5.0 Tg C yr(-1) for isopentane. Our best estimate of the global acetone source is 95 Tg yr(-1). The mean tropospheric lifetime of acetone is estimated to be 15 days. Terrestrial vegetation and oceans are the principal sources of acetone in the tropopause region (0.1-0.7 ppbv) except in the extratropical Northern Hemisphere, where oxidation of isoalkanes is more important. C1 Harvard Univ, Dept Earth & Planetary Sci, Div Engn & Appl Sci, Cambridge, MA 02138 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Jacob, DJ (reprint author), Harvard Univ, Dept Earth & Planetary Sci, Div Engn & Appl Sci, Pierce Hall,20 Oxford St, Cambridge, MA 02138 USA. EM djj@io.harvard.edu; bey@io.harvard.edu; qli@io.harvard.edu; jal@io.harvard.edu; hsingh@mail.arc.nasa.gov NR 91 TC 143 Z9 145 U1 5 U2 39 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 PY 2002 VL 107 IS D10 AR 4100 DI 10.1029/2001JD000694 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 609HA UT WOS:000178896500006 ER PT J AU Santee, ML Tabazadeh, A Manney, GL Fromm, MD Bevilacqua, RM Waters, JW Jensen, EJ AF Santee, ML Tabazadeh, A Manney, GL Fromm, MD Bevilacqua, RM Waters, JW Jensen, EJ TI A Lagrangian approach to studying Arctic polar stratospheric clouds using UARS MLS HNO3 and POAM II aerosol extinction measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NITRIC-ACID TRIHYDRATE; TRAJECTORY CALCULATIONS; SATELLITE-OBSERVATIONS; WINTER STRATOSPHERE; LIDAR OBSERVATIONS; VORTEX CONDITIONS; SULFURIC-ACID; WATER-VAPOR; OZONE LOSS; DENITRIFICATION AB [1] We assess the viability of diagnosing polar stratospheric cloud (PSC) composition and denitrification using existing satellite measurements. A Lagrangian approach is used to track PSC evolution from formation through dissipation. Upper Atmosphere Research Satellite Microwave Limb Sounder observations of gas-phase HNO3 and Polar Ozone and Aerosol Measurement II observations of aerosol extinction from the Arctic late winter of 1995/1996 are correlated and compared to results from PSC composition models along air parcel trajectories. This approach is successful in capturing the broad patterns of PSC development. That is, a strong correlation is found between low-temperature, low-HNO3, and high-extinction points. In most cases the observed behavior along the Lagrangian paths falls within the range predicted by equilibrium liquid ternary aerosol and nitric acid trihydrate composition models. At no time along the trajectories (when there is data coverage) do the models display large changes in either HNO3 or aerosol extinction that are not reflected in the data. In general, however, there is a large degree of overlap in the comparisons between the models and the data. Unmeasured quantities and large uncertainties in both measurements and model calculations preclude conclusive determination of PSC composition or phase in most cases. In the majority of PSC events studied, gas-phase HNO3 fully recovers to pre-PSC abundances following cloud evaporation. We conclude that while severe denitrification (50% or greater) may have occurred in highly localized regions in the Arctic in 1996, it did not occur over spatial scales comparable to or larger than the MLS field of view (similar to400 km x 200 km x 6 km), even though it was a relatively cold winter. Improved measurements from upcoming satellite missions, such as Earth Observing System Aura, will ameliorate many of the difficulties in diagnosing PSC composition and denitrification encountered in this study. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. USN, Res Lab, Washington, DC 20375 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. New Mexico Highlands Univ, Dept Nat Resources Management, Las Vegas, NM 87701 USA. Computat Phys Inc, Fairfax, VA 22031 USA. RP Santee, ML (reprint author), CALTECH, Jet Prop Lab, Mail Stop 183-701,4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM mls@mls.jpl.nasa.gov RI Fromm, Michael/F-4639-2010 NR 73 TC 13 Z9 13 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 MAY PY 2002 VL 107 IS D10 AR 4098 DI 10.1029/2000JD000227 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 609HA UT WOS:000178896500008 ER PT J AU Zwally, HJ Comiso, JC Parkinson, CL Cavalieri, DJ Gloersen, P AF Zwally, HJ Comiso, JC Parkinson, CL Cavalieri, DJ Gloersen, P TI Variability of Antarctic sea ice 1979-1998 SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article DE sea ice; Antarctic; climate; passive microwave; Southern Ocean ID SOUTHERN-OCEAN; BOTTOM WATER; CIRCUMPOLAR WAVE; WEDDELL POLYNYA; CARBON-DIOXIDE; CLIMATE VARIABILITY; TIME-SERIES; TEMPERATURE; TRENDS; WINTER AB [1] The principal characteristics of the variability of Antarctic sea ice cover as previously described from satellite passive microwave observations are also evident in a systematically calibrated and analyzed data set for 20.2 years (1979-1998). The total Antarctic sea ice extent (concentration >15%) increased by 11,180 +/- 4190 km(2) yr(-1) (0.98 +/- 0.37% (decade)(-1)). The increase in the area of sea ice within the extent boundary is similar (10,860 +/- 3720 km(2) yr(-1) and 1.26 +/- 0.43% (decade)(-1)). Regionally, the trends in extent are positive in the Weddel Sea (1.4 +/- 0.9% (decade)(-1)), Pacific Ocean (2.0 +/- 1.4% (decade)(-1)), and Ross (6.7 +/- 1.1% (decade)(-1)) sectors, slightly negative in the Indian Ocean (-1.0 +/- 1.0% (decade)(-1)), and strongly negative in the Bellingshausen-Amundsen Seas sector (-9.7 +/- 1.5% (decade)(-1)). For the entire ice pack, ice increases occur in all seasons, with the largest increase during fall. On a regional basis the trends differ season to season. During summer and fall the trends are positive or near zero in all sectors except the Bellingshausen-Amundsen Seas sector. During winter and spring the trends are negative or near zero in all sectors except the Ross Sea, which has positive trends in all seasons. Components of interannual variability with periods of about 3-5 years are regionally large but tend to counterbalance each other in the total ice pack. The interannual variability of the annual mean sea ice extent is only 1.6% overall, compared to 6-9% in each of five regional sectors. Analysis of the relation between regional sea ice extents and spatially averaged surface temperatures over the ice pack gives an overall sensitivity between winter ice cover and temperature of -0.7% change in sea ice extent per degree Kelvin. For summer some regional ice extents vary positively with temperature, and others vary negatively. The observed increase in Antarctic sea ice cover is counter to the observed decreases in the Arctic. It is also qualitatively consistent with the counterintuitive prediction of a global atmospheric-ocean model of increasing sea ice around Antarctica with climate warming due to the stabilizing effects of increased snowfall on the Southern Ocean. C1 NASA, Goddard Space Flight Ctr, Oceans & Ice Branch, Greenbelt, MD 20771 USA. RP Zwally, HJ (reprint author), NASA, Goddard Space Flight Ctr, Oceans & Ice Branch, Code 971, Greenbelt, MD 20771 USA. RI Parkinson, Claire/E-1747-2012 OI Parkinson, Claire/0000-0001-6730-4197 NR 69 TC 174 Z9 182 U1 2 U2 32 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 PY 2002 VL 107 IS C5 AR 3041 DI 10.1029/2000JC000733 PG 21 WC Oceanography SC Oceanography GA 609VR UT WOS:000178926100007 ER PT J AU Braak, CJ de Haan, JF Hovenier, JW Travis, LD AF Braak, CJ de Haan, JF Hovenier, JW Travis, LD TI Spatial and temporal variations of Venus haze properties obtained from Pioneer Venus Orbiter polarimetry SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article DE Venus; polarization; haze; clouds; Pioneer Venus Orbiter ID POLARIZED-LIGHT; PLANETARY ATMOSPHERES; MULTIPLE-SCATTERING AB [1] The spatial and temporal variations of the polarization of light scattered by Venus, as observed by the Pioneer Venus Orbiter between 1978 and 1990, is analyzed in terms of spatial and temporal variations of Venus upper haze properties. Special attention is given to choosing maps with sufficiently accurate geometrical information. This selection involves multiple-scattering calculations for a number of reasonable models for the Venus atmosphere. For a set of observations in four wavelength bands of the Venus disk as a whole or a particular region thereof, observed values of Stokes parameters I and Q were used to obtain the average observed relative Stokes parameter q(obs). Subsequently, the haze particle column density and the cloud top pressure were iteratively adjusted until values of q(obs) at two wavelengths were reproduced. For the planet as a whole, it was found that the haze particle column density decreased gradually during the Pioneer Venus Orbiter mission, whereas little significant temporal variability was found for the cloud top pressure. Similar long-term behavior was derived for selected regions of Venus. Regions at higher latitudes exhibited higher values of both the haze particle column density and the cloud top pressure than regions at lower latitudes. Something similar holds for regions with low solar elevations as compared to regions in which the Sun was close to the zenith. C1 Free Univ Amsterdam, Dept Phys & Astron, NL-1081 HV Amsterdam, Netherlands. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Royal Netherlands Meteorol Inst, NL-3730 AE De Bilt, Netherlands. Univ Amsterdam, Astron Inst Anton Pannekoek, Amsterdam, Netherlands. RP Braak, CJ (reprint author), Free Univ Amsterdam, Dept Phys & Astron, De Boelelaan 1081, NL-1081 HV Amsterdam, Netherlands. NR 31 TC 6 Z9 6 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 PY 2002 VL 107 IS E5 AR 5029 DI 10.1029/2001JE001502 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 609MC UT WOS:000178906900005 ER PT J AU Dubinin, E Skalsky, A Song, P Savin, S Kozyra, J Moore, TE Russell, CT Chandler, MO Fedorov, A Avanov, L Sauvaud, JA Friedel, RHW AF Dubinin, E Skalsky, A Song, P Savin, S Kozyra, J Moore, TE Russell, CT Chandler, MO Fedorov, A Avanov, L Sauvaud, JA Friedel, RHW TI Polar-Interball coordinated observations of plasma and magnetic field characteristics in the regions of the northern and southern distant cusps SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FLUX-TRANSFER EVENTS; EARTHS MAGNETOPAUSE; BOUNDARY-LAYER; MAGNETOSPHERIC CUSPS; DAYSIDE MAGNETOPAUSE; PARTICLE SIGNATURES; INTERMEDIATE SHOCKS; RECONNECTION LAYER; KINETIC STRUCTURE; NORTHWARD IMF AB [1] The structure of the high-latitude magnetosphere near the polar cusps is studied by using coordinated observations from the Polar and Interball satellites. While Polar surveyed the northern polar cusp region, Interball sampled the high-altitude region in the vicinity of the southern cusp in similar local times. A "magnetic turbulent region'' that is distinct from the magnetosphere and magnetosheath and consists of recurrent small-scale events is observed in both hemispheres. The small-scale events often contain a steep ramp followed by a wave train. The events are characterized by a steep increase in the ion energy followed by dispersed velocity filter features. Kinetic and fluid characteristics of ions and a test of the Walen relation show that the events are associated with reconnection processes. S-shaped polarization of the magnetic field variations is a characteristic feature in many cases indicating the existence of intermediate shocks. The change in the low-energy cutoff of injected ions indicates that the reconnection site is about a few Earth radii from Polar. Reflected ions on the reconnected magnetospheric field lines, which are not predicted by simple reconnection scenarios, are also observed. Coexistence of transmitted and reflected ions gives rise to a "stagnant'' plasma on the magnetospheric field lines. Characteristics of ions and electrons strongly support the suggestion that the field lines threading the plasma in these regions, which extend from the magnetosheath to the magnetosphere, are connected, at least at one end, with the Earth. In other words, the boundary layer is located, at least partly, on reconnected field lines. In contrast, a turbulent region in the indentation of the cusps has been thought to be in the magnetosheath and not to be connected with the Earth. Although the events observed by both satellites have a certain similarity, the probability of conjugated events being recorded by both satellites is small. It is believed that the visible similarity between the observations from the two hemispheres is due to structures that are characteristic features of a single transient reconnection event. C1 Univ Michigan, Space Phys Res Lab, Ann Arbor, MI 48109 USA. Moscow Space Res Inst, Moscow 117810, Russia. NASA, Extraterr Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. NASA, Space Sci Lab, Space Flight Ctr, Huntsville, AL 35812 USA. CNRS, Ctr Etud Spatiale Rayonnements, F-31028 Toulouse 4, France. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. RP Dubinin, E (reprint author), Max Planck Inst Aeron, Max Planck Str 2, D-37191 Katlenburg Lindau, Germany. RI Friedel, Reiner/D-1410-2012; Moore, Thomas/D-4675-2012 OI Friedel, Reiner/0000-0002-5228-0281; Moore, Thomas/0000-0002-3150-1137 NR 63 TC 10 Z9 10 U1 2 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 PY 2002 VL 107 IS A5 AR 1053 DI 10.1029/2001JA900068 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 609ML UT WOS:000178909100013 ER PT J AU Jones, GH Lucek, EA Balogh, A MacDowall, RJ McComas, DJ Smith, EJ AF Jones, GH Lucek, EA Balogh, A MacDowall, RJ McComas, DJ Smith, EJ TI A high-latitude interplanetary magnetic field enhancement at Ulysses SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article DE solar wind; interplanetary magnetic field; comets; interplanetary dust ID COMET GIACOBINI-ZINNER; SOLAR-WIND; FRAGMENTS; FREQUENCY AB [1] An analysis is presented of data returned from the Ulysses spacecraft on 28 July 2000, when it encountered a highly unusual event in the high-latitude solar wind. The event is identified as a class of structure previously found only near Venus and Earth. The event's characteristics are described, in terms of similarities and differences to previously reported events of this type. Several possible origins for the event are discussed. It is noted that some, but not all, of the behavior of the magnetic field and plasma parameters is consistent with mass loading of the solar wind. Assuming such a cause, an attempt is made to derive constraints on a putative cometary source's orbital parameters using a new technique that could be applied to similar events. The origin of the event, however, remains unidentified. C1 Univ London Imperial Coll Sci Technol & Med, Blackett Lab, Space & Atmospher Phys Grp, London SW7 2BW, England. NASA, Extraterr Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. SW Res Inst, Space Sci & Engn Div, San Antonio, TX 78228 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jones, GH (reprint author), Univ London Imperial Coll Sci Technol & Med, Blackett Lab, Space & Atmospher Phys Grp, London SW7 2BW, England. RI MacDowall, Robert/D-2773-2012; Jones, Geraint/C-1682-2008; OI Jones, Geraint/0000-0002-5859-1136 NR 34 TC 2 Z9 2 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 PY 2002 VL 107 IS A5 AR 1054 DI 10.1029/2001JA000098 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 609ML UT WOS:000178909100012 ER PT J AU Khazanov, GV Liemohn, MW AF Khazanov, GV Liemohn, MW TI Transport of photoelectrons in the nightside magnetosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article DE superthermal electrons; inner magnetosphere; plasmasphere; numerical modeling; convection ID IONOSPHERE-PLASMASPHERE TRANSPORT; SUPERTHERMAL ELECTRONS; RING CURRENT; CROSS-SECTIONS; MODEL; PHOTOIONIZATION; DECAY AB [1] Kinetic modeling results are analyzed to examine the transport of photoelectrons through the nightside inner magnetosphere. Two sources are considered, those on the dayside from direct solar illumination and those across the nightside from light scattered by the upper atmosphere and geocorona. A natural filter exists on the nightside for the dayside photoelectrons. Coulomb collisions erode the distribution at low energies and low L shells, and magnetospheric convection compresses the electrons as they drift toward dawn. It is shown that for low-activity levels a band of photoelectrons forms between L = 4 and 6 that extends throughout the nightside local times and into the morning sector. For the scattered light photoelectrons the trapped zone throughout the nightside is populated with electrons of E < 30 eV. At high L shells near dawn, convective compression on the nightside yields an accelerated population with electrons at energies up to twice the ionospheric energy maximum (that is, roughly 1200 eV for dayside photoelectrons and 60 eV for scattered light electrons). Modeled energy and pitch angle distributions are presented to show the features of these populations. C1 NASA, Natl Space Sci & Technol Ctr, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Michigan, Space Phys Res Lab, Ann Arbor, MI 48109 USA. RP Khazanov, GV (reprint author), NASA, Natl Space Sci & Technol Ctr, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RI Liemohn, Michael/H-8703-2012 OI Liemohn, Michael/0000-0002-7039-2631 NR 32 TC 7 Z9 7 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 PY 2002 VL 107 IS A5 AR 1064 DI 10.1029/2001JA000163 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 609ML UT WOS:000178909100002 ER PT J AU Lew, JS Juang, JN AF Lew, JS Juang, JN TI Structural damage detection using virtual passive controllers SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID ACTIVE VIBRATION ABSORBER; 2ND-ORDER DYNAMIC-SYSTEMS; ROBUST CONTROLLER; DESIGNS AB Novel approaches are presented for structural damage detection that use virtual passive controllers attached to structures, where passive controllers are energy dissipative devices and, thus, guarantee closed-loop stability. The use of the identified parameters of various closed-loop systems can solve the problem that the reliable identified parameters, such as natural frequencies, of the open-loop system may not provide enough information for damage detection. Only a small number of sensors are required for the proposed approaches. The identified natural frequencies, which are generally much less sensitive to noise and more reliable than the identified mode shapes, are used for damage detection. Two damage detection techniques are presented. One technique is based on structures with direct output feedback controllers, whereas the other technique uses second-order dynamic feedback controllers. A least-squares technique, which is based on the sensitivity of natural frequencies to damage variables, is used for accurately identifying the damage variables. C1 Tennessee State Univ, Ctr Excellence Informat Syst, Nashville, TN 37203 USA. NASA, Langley Res Ctr, Struct Dynam Branch, Hampton, VA 23681 USA. RP Lew, JS (reprint author), Tennessee State Univ, Ctr Excellence Informat Syst, Nashville, TN 37203 USA. NR 19 TC 33 Z9 39 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 2002 VL 25 IS 3 BP 419 EP 424 DI 10.2514/2.4918 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 550NQ UT WOS:000175509500001 ER PT J AU Oldenburg, JA Tragesser, SG AF Oldenburg, JA Tragesser, SG TI Minimizing the effects of transverse torques during thrusting for spin-stabilized spacecraft SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID UP MANEUVERS; ANNIHILATION; BIAS AB During an orbital maneuver of a spin-stabilized spacecraft, undesired transverse torques are present due to thruster misalignment and offset from the center of mass. These body-fixed torques cause the thrust vector to precess about a direction that is offset from the nominal. This oscillation of the thrust vector over the course of the maneuver decreases the final magnitude of the DeltaV while the average offset causes a pointing error. Previous work shows that inserting a short-coast phase into the maneuver can eliminate the pointing error. The behavior of the thrust axis is considered to find solutions for the coast phase timing that minimize the average oscillation of the thrust axis to maximize DeltaV, while retaining the property of eliminating the secular pointing error. The new maneuver scheme realizes a significant increase in efficiency over the previous solution, particularly if the oscillation of the thrust axis is large. C1 USAF, Inst Technol, Dept Aeronaut & Astronaut, Wright Patterson AFB, OH 45433 USA. RP Oldenburg, JA (reprint author), US Space Command, Natl Missile Def Command & Control Integrat Sect, Peterson AFB, CO 80914 USA. NR 4 TC 7 Z9 7 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 2002 VL 25 IS 3 BP 591 EP 595 DI 10.2514/2.4921 PG 5 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 550NQ UT WOS:000175509500021 ER PT J AU Kim, Y Engel, BA Lim, KJ Larson, V Duncan, B AF Kim, Y Engel, BA Lim, KJ Larson, V Duncan, B TI Runoff impacts of land-use change in Indian river lagoon watershed SO JOURNAL OF HYDROLOGIC ENGINEERING LA English DT Article DE runoff; land usage; Florida; watersheds; lagoons; geographic information systems ID SCALE; MODEL; GIS AB Changes in land use can have significant impacts on hydrology and the environment. The Long-Term Hydrologic Impact Analysis model and a geographic information system-based Soil Conservation Service curve number method were used to estimate average annual runoff and runoff for rainfall events with varying return periods, respectively, for NASA's John F. Kennedy Space Center (KSC) within the Indian River Lagoon watershed (IRL), Florida, for 1920, 1943, and 1990 land uses. Changes in estimated runoff depths due to land-use alteration between 1920 and 1990-for design rainfall events ranging from a 24 h/1 year to a 24 h/100 year return period-ranged from 7-17% for KSC to 22-55% for the IRL watershed. The percentage changes in average annual runoff due to land-use changes were much greater. Between 1920 and 1990, estimated average annual runoff for the KSC increased about 49%, and the IRL runoff increased nearly 113%. For the KSC and IRL, most of the increase in runoff between 1920 and 1990, both for single events and annually, came from landscape urbanization, although increased agricultural land uses in the IRL also contributed to increased runoff. Large differences in estimated runoff between the KSC and IRL are due to differences in the amount of urban land use within the respective areas (1990 urban land uses for the IRL are 34.8 versus 20.5% for KSC). Land-use change can have a dramatic impact on annual runoff volume, as demonstrated in this study; thus the effects of land-use change on annual or long-term runoff should be considered in land-use planning. C1 Korea Inst Construct Technol, Koyang, Kyounggi Do, South Korea. Purdue Univ, Dept Agr & Biol Engn, W Lafayette, IN 47907 USA. NASA, John F Kennedy Space Ctr, Kennedy Space Ctr, FL 32899 USA. RP Kim, Y (reprint author), Korea Inst Construct Technol, Koyang, Kyounggi Do, South Korea. NR 24 TC 35 Z9 40 U1 0 U2 17 PU ASCE-AMER SOC CIVIL ENGINEERS PI RESTON PA 1801 ALEXANDER BELL DR, RESTON, VA 20191-4400 USA SN 1084-0699 J9 J HYDROL ENG JI J. Hydrol. Eng. PD MAY-JUN PY 2002 VL 7 IS 3 BP 245 EP 251 DI 10.1061/(ASCE)1084-0699(2002)7:3(245) PG 7 WC Engineering, Civil; Environmental Sciences; Water Resources SC Engineering; Environmental Sciences & Ecology; Water Resources GA 545NQ UT WOS:000175224200005 ER PT J AU Joshi, SM Kelkar, AG AF Joshi, SM Kelkar, AG TI Design of norm-bounded and sector-bounded LQG controllers for uncertain systems SO JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS LA English DT Article DE linear systems; robust control; LQG controllers AB The design of linear-quadratic-Gaussian (LQG) controllers is addressed for uncertain linear time-invariant systems that are either norm bounded or belong to a given sector. The system matrices are assumed to be affine functions of parameters confined to a convex polytopic region in the parameter space. Methods are developed for designing controllers which satisfy certain norm or sector conditions and are simultaneously optimal in the LQG sense. The resulting controllers provide robust stability as well as optimal performance. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. Iowa State Univ, Dept Mech Engn, Ames, IA USA. RP Joshi, SM (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 11 TC 11 Z9 11 U1 0 U2 2 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-3239 J9 J OPTIMIZ THEORY APP JI J. Optim. Theory Appl. PD MAY PY 2002 VL 113 IS 2 BP 269 EP 282 AR UNSP 0022-3239/02/0500-0269/0 DI 10.1023/A:1014878808394 PG 14 WC Operations Research & Management Science; Mathematics, Applied SC Operations Research & Management Science; Mathematics GA 553QC UT WOS:000175686100004 ER PT J AU Les, CM Whalen, RT Beaupre, GS Yan, CH Cleek, TM Wills, JS AF Les, CM Whalen, RT Beaupre, GS Yan, CH Cleek, TM Wills, JS TI The X-ray attenuation characteristics and density of human calcaneal marrow do not change significantly during adulthood SO JOURNAL OF ORTHOPAEDIC RESEARCH LA English DT Article DE bone marrow; quantitative computed tomography; cancellous bone; aging; calcaneus; bone density ID QUANTITATIVE COMPUTED-TOMOGRAPHY; BONE-MINERAL DENSITY; STRAIN-SPECIFIC DIFFERENCES; DUAL-ENERGY METHODS; TRABECULAR BONE; SKELETAL SYSTEM; FAILURE LOADS; SINGLE-ENERGY; FAT-CONTENT; CT AB Changes in the material characteristics of bone marrow with aging can be a significant source of error in measurements of bone density when using X-ray and ultrasound imaging modalities. In the context of computed tomography, dual-energy computed techniques have been used to correct for changes in marrow composition. However, dual-energy quantitative Computed tomography (DE-QCT) protocols, while increasing the accuracy of the measurement. reduce the precision and increase the radiation dose to the patient in comparison to single-energy quantitative computed tomography (SE-QCT) protocols. If the attenuation properties of the marrow for a particular bone can be shorn to be relatively constant with age, it should be possible to use single-energy techniques without experiencing errors caused by unknown marrow composition. Marrow was extracted by centrifugation from 10 mm thick frontal sections of 34 adult cadaver calcanei (28 males. 6 females, ages 17 65 years). The density and energy-dependent linear X-ray attenuation coefficient Of each marrow sample,here determined. For purposes of comparing Our results. we then computed an effective CT number at two GE CT/i scan voltages (80 and 120 kVp) for each specimen. The coefficients of variation for the density. CT number at 80 kVp and CT number at 120 kVp v ere each less than 1%, and the parameters did not change significantly with age (p > 0.2, r(2) < 0.02, power > 0.8 where the minimum acceptable r(2) = 0.216). We could demonstrate no significant gender-associated differences in these relationships. These data Suggest that calcaneal bone marrow X-ray attenuation properties and marrow density are essentially constant from the third through sixth decades of life. (C) 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Musculoskeletal Biomech Lab, Ames Res Ctr, Moffett Field, CA 94035 USA. Stanford Univ, Lucas MRS Imaging Ctr, Stanford, CA 94305 USA. VA Palo Alto Hlth Care Syst, Rehabil Res & Dev Ctr, Palo Alto, CA USA. RP Les, CM (reprint author), Henry Ford Hosp, Ctr Bone & Joint, ERB 2015, 2799 W Grand Blvd, Detroit, MI 48202 USA. OI Beaupre, Gary/0000-0002-6211-7621 NR 73 TC 3 Z9 3 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0736-0266 J9 J ORTHOPAED RES JI J. Orthop. Res. PD MAY PY 2002 VL 20 IS 3 BP 633 EP 641 AR PII S0736-0266(01)00143-7 DI 10.1016/S0736-0266(01)00143-7 PG 9 WC Orthopedics SC Orthopedics GA 552LF UT WOS:000175621300032 PM 12038641 ER PT J AU Lee, T Fukumori, I Menemenlis, D Xing, ZF Fu, LL AF Lee, T Fukumori, I Menemenlis, D Xing, ZF Fu, LL TI Effects of the Indonesian Throughflow on the Pacific and Indian oceans SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID GENERAL-CIRCULATION MODEL; NORTH PACIFIC; APPEARANCE REALITY; EL-NINO; THERMOCLINE; WATER; PARAMETERIZATION; CLIMATOLOGY; ORIGINATE; EXCHANGE AB Effects of the Indonesian Throughflow (ITF) on the circulation and thermal structure of the Pacific and Indian Oceans are studied by comparing solutions of a near-global ocean general circulation model with open and closed Indonesian passages from 1981 to 1997. The ITF contributes to the maintenance of the model circulation system around eastern Australia and the southern Indian Ocean. Blockage of the ITF weakens the Indian Ocean South Equatorial Current and Agulhas Current and strengthens the East Australian Current. The ITF does not affect the Mindanao Current, but drains waters carried by this current into the Indian Ocean and thus reduces tropical-subtropical exchange in the North Pacific. Meanwhile, it helps maintain a stronger New Guinea Coastal Undercurrent and thus enhances tropical-subtropical exchange in the south. Water parcels traveling along the western boundary of the South Pacific cross the equator in the presence of the ITF but are confined to the Southern Hemisphere without the ITF. The southern "exchange window'' in which subducted waters can reach the Tropics is wider with than without the ITF. Some parcels from the southern subtropics can reach the Tropics with open ITF, but recirculate back to the subtropical gyre when the ITF is closed. These "excess'' recirculated parcels reach several degrees farther south and outcrop north of Tasmania. The consequence on sea surface temperature (SST) there may have an important implication to the local climate. Blockage of the ITF depresses the mean thermocline of the tropical Pacific, increases SST in the central to eastern equatorial Pacific, and thus reduces the SST difference between the warm pool and cold tongue. It also raises the mean thermocline of the Indian Ocean (especially the southern Indian Ocean) and decreases SST in the southern Indian Ocean. Blockage of the ITF reduces seasonal-to-interannual thermocline fluctuations in the central to eastern equatorial Pacific because the resulting deeper thermocline attenuates fluctuations in response to local Ekman pumping. The opposite is true in the southern Indian Ocean for the interannual timescale. However, seasonal thermocline fluctuation in that area is weakened when the ITF is blocked (despite a shallower thermocline). It indicates that local Ekman pumping is not the dominant mechanism controlling seasonal thermocline variability there as previously suggested. Radiation of planetary waves from the ITF area and advection by the ITF-dependent South Equatorial Current could also be important. Blockage of the ITF also reduces interannual variability of SST in the eastern equatorial Pacific and enhances those in the tropical southern Indian Ocean and south of Tasmania. The results indicate that the ITF may affect El Nino-Southern Oscillation by modifying tropical-subtropical exchanges, mean tropical thermocline structure, mean SST difference between the warm pool and cold tongue, and seasonal-to-interannual variabilities of thermocline depth and SST. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lee, T (reprint author), CALTECH, Jet Prop Lab, MS 300-323,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 42 TC 100 Z9 109 U1 2 U2 18 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 2002 VL 32 IS 5 BP 1404 EP 1429 DI 10.1175/1520-0485(2002)032<1404:EOTITO>2.0.CO;2 PG 26 WC Oceanography SC Oceanography GA 547GW UT WOS:000175325500009 ER PT J AU Schmidt, GR Bonometti, JA Irvine, CA AF Schmidt, GR Bonometti, JA Irvine, CA TI Project Orion and future prospects for nuclear pulse propulsion SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/ASME/SAE/ASEE 36th Joint Propulsion Conference and Exhibit CY JUL 16-19, 2000 CL HUNTSVILLE, ALABAMA SP Amer Inst Aeronaut & Astronaut, ASME, SAE, ASEE ID ENERGY AB The race to the Moon dominated human space flight during the 1960s and culminated in Project Apollo, which placed 12 men on the lunar surface. Unbeknownst to the public at that time, several U.S. government agencies sponsored another project that could have conceivably placed large bases on the moon and eventually sent crewed expeditions to Mars and the outer planets within the same period of time as Apollo, and for approximately the same cost. The project, code-named Orion, featured an extraordinary propulsion method known as nuclear pulse propulsion. First conceived at the dawn of the space age, the concept was as radical then as it is now. However, its feasibility was never dismissed on purely technical grounds. In fact, many of the scientists and engineers who came into contact with the program over its seven-year lifetime became convinced of its viability. The political and nontechnical issues that finally sealed the program's fate would certainly make the original Orion unacceptable by today's standards. However, new technologies and ideas developed since then could mitigate some of the major issues, and make nuclear pulse propulsion less unreasonable to consider for future human exploration, at least beyond Mars orbit. These new approaches are presented, following a discussion of the technological rationale for nuclear pulse propulsion and a general history of the concept. C1 NASA, George C Marshall Space Flight Ctr, Prop Res Ctr, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Adv Concepts Dept, Huntsville, AL 35812 USA. RP Schmidt, GR (reprint author), NASA, George C Marshall Space Flight Ctr, Prop Res Ctr, Huntsville, AL 35812 USA. NR 26 TC 7 Z9 7 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 2002 VL 18 IS 3 BP 497 EP 504 DI 10.2514/2.5969 PG 8 WC Engineering, Aerospace SC Engineering GA 552AG UT WOS:000175595700001 ER PT J AU Papila, N Shyy, W Griffin, L Dorney, DJ AF Papila, N Shyy, W Griffin, L Dorney, DJ TI Shape optimization of supersonic turbines using global approximation methods SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA 39th Aerospace Sciences Meeting and Exhibits CY JAN 08-11, 2001 CL RENO, NEVADA SP Amer Inst Aeronaut & Astronaut ID DESIGN OPTIMIZATION; FLOW AB There is growing interest to adopt supersonic turbines for rocket propulsion, However, this technology has not been actively investigated in the United States for the last three decades. To aid design improvement, a global optimization framework combining the radial-basis neural network (NN) and the polynomial response surface (RS) method is constructed for shape optimization of a two-stage supersonic turbine, involving O(10) design variables. The design of the experiment approach is adopted to reduce the data size needed by the optimization task. The combined NN and RS techniques are employed. A major merit of the RS approach is that it enables one to revise the design space to perform multiple optimization cycles. This benefit is realized when an optimal design approaches the boundary of a predefined design space. Furthermore, by inspecting the influence of each design variable, one can also gain insight into the existence of multiple design choices and select the optimum design based on other factors such as stress and materials consideration. C1 Univ Florida, Dept Aerosp Engn Mech & Engn Sci, Gainesville, FL 32611 USA. NASA, George C Marshall Space Flight Ctr, Space Transportat Directorate, Huntsville, AL 35812 USA. RP Papila, N (reprint author), Univ Florida, Dept Aerosp Engn Mech & Engn Sci, Gainesville, FL 32611 USA. NR 41 TC 35 Z9 36 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 2002 VL 18 IS 3 BP 509 EP 518 DI 10.2514/2.5991 PG 10 WC Engineering, Aerospace SC Engineering GA 552AG UT WOS:000175595700003 ER PT J AU Oyama, A Liou, MS AF Oyama, A Liou, MS TI Multiobjective optimization of rocket engine pumps using evolutionary algorithm SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB A design optimization method for turbopumps of cryogenic rocket engines has been developed. Multiobjective evolutionary algorithm is used for multiobjective pump design optimizations. Performances of design candidates are evaluated by using the meanline pump flow-modeling method based on the Euler turbine equation coupled with empirical correlations for rotor efficiency. To demonstrate feasibility of the present approach, single-stage centrifugal pump and multistage pump design optimizations are performed. The number of pump performance evaluations necessary to obtain a reasonable pareto-optimal set for the conceptual rocket engine pump design will be investigated using the single-stage centrifugal pump design optimization. In both design optimizations the present method obtains hundreds of reasonable and uniformly distributed pareto-optimal solutions that include some designs outperforming the original design in total head while reducing input power by 1 %. Detailed observation of the design results also reveals some important design criteria for turbopumps in cryogenic rocket engines. These results demonstrate the feasibility of the evolutionary algorithm-based multiobjective design optimization method in this field. C1 NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. RP Oyama, A (reprint author), Ohio Aerosp Inst ICOMP, 22800 Cedar Point Rd, Cleveland, OH 44142 USA. NR 24 TC 18 Z9 18 U1 2 U2 9 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 2002 VL 18 IS 3 BP 528 EP 535 DI 10.2514/2.5993 PG 8 WC Engineering, Aerospace SC Engineering GA 552AG UT WOS:000175595700005 ER PT J AU Rivers, HK Sikora, JG Sankaran, SN AF Rivers, HK Sikora, JG Sankaran, SN TI Detection of hydrogen leakage in a composite sandwich structure at cryogenic temperature SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT AIAA/ASME/ASCE/AHS/ASC 42nd Structures, Structural Dynamics, and Materials Conference CY APR 16-19, 2001 CL SEATTLE, WASHINGTON SP Amer Inst Aeronatu & Astronaut, ASME, ASCE, AHS, ASC AB Hydrogen tanks made of polymer-matrix composite material have been proposed as an enabling technology for reducing the weight of reusable launch vehicles and increasing their payload. A key development issue for these lightweight structures is the leakage of hydrogen through the composite material, which is generally a function of the tank material, manufacturing method, mechanical load, any internal damage states in the material, and the temperatures at which the tank must operate. A method for measuring leakage through a geometrically complex structure at cryogenic temperatures and under mechanical load that has been developed, calibrated, and used to measure helium and hydrogen leakage through the X-33 liquid hydrogen tank structure is presented. In particular, results from the calibration tests are presented that indicate that the measurement errors are less than 10% for leak rates ranging from 0.3 to 200 cm(3)/min at standard atmospheric conditions. In addition, both hydrogen and helium leak tests that were performed on two specimens taken from a discarded segment of the X-33 tank structure and results are compared. For both the hydrogen and helium tests leak rates varied with the applied mechanical load. The level of hydrogen leakage is shown to be significantly higher than the helium leakage and to exceed the acceptable leak rate for a vehicle like the X-33 liquid hydrogen tank by an order of magnitude. C1 NASA, Langley Res Ctr, Met & Thermal Struct Branch, Struct & Mat Competency, Hampton, VA 23681 USA. Lockheed Martin Space Operat, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Instrumentat Syst Dev Branch, Aerodynam Aerothermodynam & Accoust Competency, Hampton, VA 23681 USA. RP Rivers, HK (reprint author), NASA, Langley Res Ctr, Met & Thermal Struct Branch, Struct & Mat Competency, 6 E Reid St, Hampton, VA 23681 USA. NR 8 TC 11 Z9 11 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 2002 VL 39 IS 3 BP 452 EP 459 DI 10.2514/2.3829 PG 8 WC Engineering, Aerospace SC Engineering GA 560HZ UT WOS:000176077800014 ER PT J AU Frumkin, MA Van Der Wijngaart, RF AF Frumkin, MA Van Der Wijngaart, RF TI Tight bounds on cache use for stencil operations on rectangular grids SO JOURNAL OF THE ACM LA English DT Article DE algorithms; performance; theory; cache memory; cache misses; fundamental parallelepiped; lattice; lower and upper bounds; reduced basis; scientific computing; structured grids AB We derive tight bounds on cache misses for evaluation of explicit stencil operators on rectangular grids. Our lower bound is based on the isoperimetric property of the discrete crosspolytope. Our upper bound is based on a good surface-to-volume ratio of a parallelepiped spanned by a reduced basis of the interference lattice of a grid. Measurements show that our algorithm typically reduces the number of cache misses by a factor of three, relative to a compiler optimized code. We show that stencil calculations on grids whose interference lattices have a short vector feature abnormally high numbers of cache misses. We call such grids unfavorable and suggest to avoid these in computations by appropriate padding. By direct measurements on a MIPS R10000 processor we show a good correlation between abnormally high numbers of cache misses and unfavorable three-dimensional grids. C1 NASA, Ames Res Ctr, Adv Supercomp Div, Moffett Field, CA 94035 USA. RP Frumkin, MA (reprint author), NASA, Ames Res Ctr, Adv Supercomp Div, Mail Stop T27A-2, Moffett Field, CA 94035 USA. EM frumkin@nas.nasa.gov; wijngaar@nas.nasa.gov NR 13 TC 0 Z9 0 U1 0 U2 0 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 2 PENN PLAZA, STE 701, NEW YORK, NY 10121-0701 USA SN 0004-5411 J9 J ACM JI J. ACM PD MAY PY 2002 VL 49 IS 3 BP 434 EP 453 DI 10.1145/567112.567115 PG 20 WC Computer Science, Hardware & Architecture; Computer Science, Information Systems; Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA 590CQ UT WOS:000177800500005 ER PT J AU Cheng, Y Canuto, VM Howard, AM AF Cheng, Y Canuto, VM Howard, AM TI An improved model for the turbulent PBL SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID LARGE-EDDY SIMULATION; ATMOSPHERIC BOUNDARY-LAYER; SURFACE-LAYER; DYNAMICAL MODEL; CLOSURE-MODEL; ENERGY-MODEL; MIXED-LAYER; 3RD-ORDER MOMENTS; GEOPHYSICAL FLOWS; SHEAR-DRIVEN AB Second-order turbulence models of the Mellor and Yamada type have been widely used to simulate the planetary boundary layer (PBL). It is, however, known that these models have several deficiencies. For example, assuming the production of the turbulent kinetic energy equals its dissipation, they all predict a critical Richardson number that is about four times smaller than the large eddy simulation (LES) data in stably stratified flows and are unable to distinguish the vertical and lateral components of the turbulent kinetic energy in neutral PBLs, and they predict a boundary layer height lower than expected. In the present model, three new ingredients are employed: 1) an updated expression for the pressure-velocity correlation, 2) an updated expression for the pressure-temperature correlation, and 3) recent renormalization group (RNG) expressions for the different turbulence timescales, which yield 1) a critical Richardson number of order unity in the stably stratified PBL (at level 2 of the model), 2) different vertical and lateral components of the turbulent kinetic energy in the neutral PBL obtained without the use of the wall functions, 3) a greater PBL height, 4) closer comparisons with the Kansas data in the context of the Monin-Obukhov PBL similarity theory, in both stable and unstable PBLs, and 5) more realistic comparisons with the LES and laboratory data. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Dept Appl Math & Phys, New York, NY USA. RP Canuto, VM (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM acvmc@giss.nasa.gov NR 64 TC 111 Z9 114 U1 2 U2 13 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD MAY PY 2002 VL 59 IS 9 BP 1550 EP 1565 DI 10.1175/1520-0469(2002)059<1550:AIMFTT>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 542YQ UT WOS:000175073700008 ER PT J AU Varnai, T Marshak, A AF Varnai, T Marshak, A TI Observations of three-dimensional radiative effects that influence MODIS cloud optical thickness retrievals SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID BOUNDARY-LAYER CLOUDS; ALBEDO; VARIABILITY; BIASES; STRATOCUMULUS AB When cloud properties are retrieved from satellite observations, current calculations apply one-dimensional (1D) theory to the three-dimensional (3D) world: they consider only vertical processes and ignore horizontal interactions. This paper proposes a novel approach that estimates 3D effects in cloud optical thickness retrievals. The proposed method combines visible and thermal infrared images to see whether 3D radiative effects make clouds appear asymmetric-that is, whether cloud surfaces tilted toward the sun are systematically brighter than surfaces tilted away from it. The observed asymmetries are then used to estimate 3D effects for 1-km-size pixels as well as 50-km-size areas. Initial results obtained for Moderate-Resolution Imaging Spectroradiometer (MODIS) images reveal that 3D effects cause abundant uncertainties in the 1-km-resolution 1D retrievals. Averaging over 50 km by 50 km areas greatly reduces the errors but does not remove them completely. Conservative estimates show that the mean optical thickness values are biased by more than 10% in 10% of the areas, and the errors in the areas' standard deviation values are more than 10% in about 20% of areas. C1 NASA, Goddard Space Flight Ctr, Joint Ctr Earth Syst Technol, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Baltimore, MD 21228 USA. RP Varnai, T (reprint author), NASA, Goddard Space Flight Ctr, Joint Ctr Earth Syst Technol, Code 913, Greenbelt, MD 20771 USA. RI Marshak, Alexander/D-5671-2012 NR 24 TC 55 Z9 57 U1 0 U2 7 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD MAY PY 2002 VL 59 IS 9 BP 1607 EP 1618 DI 10.1175/1520-0469(2002)059<1607:OOTDRE>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 542YQ UT WOS:000175073700012 ER PT J AU Gabriel, AK AF Gabriel, AK TI Fundamental radar properties: hidden variables in space-time SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article AB A derivation of the properties of pulsed radiative imaging systems is presented with examples drawn from conventional, synthetic aperture, and interferometric radar. A geometric construction of the space and time components of a radar observation yields a simple underlying structural equivalence among many of the properties of radar, including resolution, range ambiguity, azimuth aliasing, signal strength, speckle, layover, Doppler shifts, obliquity and slant range resolution, finite antenna size, atmospheric delays, and beam- and pulse-limited configurations. The same simple structure is shown to account for many interferometric proporties of radar: height resolution, image decorrelation, surface velocity detection, and surface deformation measurement. What emerges is a simple, unified description of the complex phenomena of radar observations. The formulation comes from fundamental physical concepts in relativistic field theory, of which the essential elements are presented. In the terminology of physics, radar properties are projections of hidden variables-curved worldlines from a broken symmetry in Minkowski space-time-onto a time-serial receiver. (C) 2002 Optical Society of America. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gabriel, AK (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 10 TC 2 Z9 2 U1 0 U2 0 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 2002 VL 19 IS 5 BP 946 EP 956 DI 10.1364/JOSAA.19.000946 PG 11 WC Optics SC Optics GA 548CY UT WOS:000175372100012 PM 11999969 ER PT J AU Milman, M AF Milman, M TI Optimization approach to the suppression of vibration errors in phase-shifting interferometry SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID SELF-CALIBRATING ALGORITHM AB An optimization-based strategy is introduced for suppressing errors due to vibration in phase-shifting-interferometry algorithms. A norm-square integral criterion of the error as a function of vibration frequency is used as the basis of the optimization procedure. Analytical results are obtained for certain classes of problems, and numerical algorithms are used when these are not available. It is also shown that the effect of vibration-induced errors in the computation of a time-averaged phase estimate diminishes as the measurements are averaged. Simulations are used to validate the analysis and demonstrate the overall efficacy of the approach. Generalizations to multiple objective optimization problems are briefly discussed. (C) 2002 Optical Society of America. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Milman, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 5 Z9 5 U1 0 U2 2 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 2002 VL 19 IS 5 BP 992 EP 1004 DI 10.1364/JOSAA.19.000992 PG 13 WC Optics SC Optics GA 548CY UT WOS:000175372100017 PM 11999974 ER PT J AU DellaCorte, C AF DellaCorte, C TI A changing of the guard SO LUBRICATION ENGINEERING LA English DT Editorial Material C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP DellaCorte, C (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD MAY PY 2002 VL 58 IS 5 BP 3 EP 3 PG 1 WC Engineering, Mechanical SC Engineering GA 552EK UT WOS:000175606100001 ER PT J AU Litvin, FL Fuentes, A Fan, Q Handschuh, RF AF Litvin, FL Fuentes, A Fan, Q Handschuh, RF TI Computerized design, simulation of meshing, and contact and stress analysis of face-milled formate generated spiral bevel gears SO MECHANISM AND MACHINE THEORY LA English DT Article AB A new approach for design, tooth contact analysis (TCA) and stress analysis of formate generated spiral bevel gears is proposed. The advantage of formate generation is the higher productivity. The purposes of the proposed approach are to overcome difficulties of surface conjugation caused by formate generation, develop a low noise and stabilized bearing contact, and perform stress analysis. The approach proposed is based on application of four procedures that enable in sequence to provide a predesigned parabolic function of transmission errors with limited magnitude of maximal transmission errors, a bearing contact with reduced shift of contact caused by misalignment, and perform stress analysis based on application of Finite Element Method. The advantage of the approach developed for finite element analysis (FEA) is the automatic generation of finite element models with multi-pairs of teeth. The stress analysis is accomplished by direct application of ABAQUS. Intermediate auxiliary CAD computer programs for development of solid models are not required. The theory developed is illustrated with an example of design and computation. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Univ Illinois, Dept Mech Engn, Gear Res Ctr, Chicago, IL 60607 USA. NASA, Glenn Res Ctr, USA Res Lab, Cleveland, OH 44135 USA. RP Litvin, FL (reprint author), Univ Illinois, Dept Mech Engn, Gear Res Ctr, POB 4348, Chicago, IL 60607 USA. RI Fuentes Aznar, Alfonso/A-4259-2015 OI Fuentes Aznar, Alfonso/0000-0001-7882-4999 NR 14 TC 44 Z9 67 U1 1 U2 19 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-114X J9 MECH MACH THEORY JI Mech. Mach. Theory PD MAY PY 2002 VL 37 IS 5 BP 441 EP 459 AR PII S0094-114X(01)00086-6 DI 10.1016/S0094-114X(01)00086-6 PG 19 WC Engineering, Mechanical SC Engineering GA 550BB UT WOS:000175482500002 ER PT J AU Whittenberger, JD Raj, SV Locci, IE Salem, JA AF Whittenberger, JD Raj, SV Locci, IE Salem, JA TI Elevated temperature strength and room-temperature toughness of directionally solidified Ni-33Al-33Cr-1Mo SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID ROD-PLATE TRANSITION; EUTECTIC NIAL-CR; MECHANICAL-PROPERTIES; CREEP-BEHAVIOR; SUBGRAIN SIZE; PLASTIC-FLOW; COMPOSITES; STRESS; ALLOY AB The eutectic composition Ni-33Al-33Cr-1Mo has been directionally solidified (DS) via a modified Bridgman technique at rates ranging from 7.6 to 508 mm/h to determine if the growth rate affects the mechanical properties. Microstructural examination revealed that all DS rods had grain/cellular microstructures containing alternating plates of NiAl and Cr alloyed with Mo. At slower growth rates (less than or equal to 12.7 mm/h), the grains had sharp boundaries, while faster growth rates (greater than or equal to 25.4 mm/h) led to cells bounded by intercellular regions. None of the growth conditions resulted in either dendrites or third phases. Compressive testing between 1200 and 1400 K indicated that alloys DS at rates between 25.4 and 254 mm/h possessed the best strengths, while room-temperature toughness exhibited a plateau of about 16 MParootm for growth rates between 12.7 and 127 mm/h. Thus, a growth rate of 127 mm/h represents the best combination of fast processing and mechanical properties for this system. C1 Case Western Reserve Univ, Mat Div, Cleveland, OH 44106 USA. NASA, Glenn Res Ctr, Struct & Acoust Div, Cleveland, OH 44135 USA. RP Whittenberger, JD (reprint author), Case Western Reserve Univ, Mat Div, Cleveland, OH 44106 USA. NR 29 TC 19 Z9 20 U1 0 U2 4 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 184 THORN HILL RD, WARRENDALE, PA 15086 USA SN 1073-5623 J9 METALL MATER TRANS A JI Metall. Mater. Trans. A-Phys. Metall. Mater. Sci. PD MAY PY 2002 VL 33 IS 5 BP 1385 EP 1397 DI 10.1007/s11661-002-0063-z PG 13 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA 548FA UT WOS:000175376900007 ER PT J AU Brown, PG Hildebrand, AR Zolensky, ME AF Brown, PG Hildebrand, AR Zolensky, ME TI Tagish Lake SO METEORITICS & PLANETARY SCIENCE LA English DT Editorial Material C1 Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada. Univ Calgary, Dept Geol & Geophys, Calgary, AB T2N 1N4, Canada. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Brown, PG (reprint author), Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada. NR 12 TC 2 Z9 2 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAY PY 2002 VL 37 IS 5 BP 619 EP 621 PG 3 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 558MR UT WOS:000175971600001 ER PT J AU Mittlefehldt, DW AF Mittlefehldt, DW TI Geochemistry of the ungrouped carbonaceous chondrite Tagish Lake, the anomalous CM chondrite Bells, and comparison with CI and CM chondrites SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID TRACE-ELEMENTS; COMPOSITIONAL CLASSIFICATION; METEORITES; MINERALOGY; SOLAR; ABUNDANCES; PETROLOGY; MATRIX AB I have determined the composition via instrumental neutron activation analysis of a bulk pristine sample of the Tagish Lake carbonaceous chondrite fall, along with bulk samples of the Cl chondrite Orgueil and of several CM chondrites. Tagish Lake has a mean of refractory lithophile element/Cr ratios like those of CM chondrites, and distinctly higher than the Cl chondrite mean. Tagish Lake exhibits abundances of the moderately volatile lithophile elements Na and K that are slightly higher than those of mean CM chondrites. Refractory through moderately volatile siderophile element abundances in Tagish Lake are like those of CM chondrites. Tagish Lake is distinct from CM chondrites in abundances of the most volatile elements. Mean Cl-normalized Se/Co, Zn/Co and Cs/Co for Tagish Lake are 0.68 +/- 0.01, 0.71 +/- 0.07 and 0.76 +/- 0.02, while for all available CM chondrite determinations, these ratios lie between 0.31 and 0.61, between 0.32 and 0.58, and between 0.39 and 0.74, respectively. Considering petrography, and oxygen isotopic and elemental compositions, Tagish Lake is an ungrouped member of the carbonaceous chondrite clan. The overall abundance pattern is similar to those of CM chondrites, indicating that Tagish Lake and CMs experienced very similar nebular fractionations. Bells is a CM chondrite with unusual petrologic characteristics. Bells has a mean CI-normalized refractory lithophile element/Cr ratio of 0.96, lower than for any other CM chondrite, but shows CI-normalized moderately volatile lithophile element/Cr ratios within the ranges of other CM chondrites, except for Na which is low. Iridium, Co, Ni and Fe abundances are like those of CM chondrites, but the moderately volatile siderophile elements, Au, As and Sb, have abundances below the ranges for CM chondrites. Abundances of the moderately volatile elements Se and Zn of Bells are within the CM ranges. Bells is best classified as an anomalous CM chondrite. C1 NASA, Lyndon B Johnson Space Ctr, SR, Houston, TX 77058 USA. RP Mittlefehldt, DW (reprint author), NASA, Lyndon B Johnson Space Ctr, SR, Houston, TX 77058 USA. NR 31 TC 30 Z9 30 U1 1 U2 5 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAY PY 2002 VL 37 IS 5 BP 703 EP 712 AR UNSP MS#4650 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 558MR UT WOS:000175971600008 ER PT J AU Zolensky, ME Nakamura, K Gounelle, M Mikouchi, T Kasama, T Tachikawa, O Tonui, E AF Zolensky, ME Nakamura, K Gounelle, M Mikouchi, T Kasama, T Tachikawa, O Tonui, E TI Mineralogy of Tagish Lake: An ungrouped type 2 carbonaceous chondrite SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID CM CHONDRITES; REFRACTORY INCLUSIONS; AQUEOUS ALTERATION; KAIDUN METEORITE; MATRIX; ORIGIN; PHYLLOSILICATES; POROSITY; RICH; RIMS AB In this paper we describe the recovery, handling and preliminary mineralogical investigation of the Tagish Lake meteorite. Tagish Lake is a type 2 carbonaceous chondrite which bears similarities to CI1 and CM chondrite groups, but is distinct from both. Abundant phyllosilicates as well as chondrules (however sparse) and common olivine grains in the matrix preclude any other classification. The bulk density of Tagish Lake (1.67 g/cc) is far lower than Cl or CM chondrites (2.2-2.3 and 2.6-2.9 g/cc, respectively), or any other meteorite for that matter. We have identified two lithologies: a dominant carbonate-poor lithology and a less-abundant carbonate-rich lithology. The meteorite is a breccia at all scales. We have noted similarities between Tagish Lake and some clasts within the enigmatic meteorite Kaidun; possibly there are genetic relationships here worth exploring. In the paper we describe a clast of CM1 material within Tagish Lake which is very similar to a major lithology in Kaidun. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Kobe Univ, Grad Sch Sci & Technol, Kobe, Hyogo 6578510, Japan. Nat Hist Museum, Dept Mineral, London SW7 5BD, England. Univ Tokyo, Grad Sch Sci, Dept Earth & Planetary Sci, Bunkyo Ku, Tokyo 1130033, Japan. RP Zolensky, ME (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code ST, Houston, TX 77058 USA. RI Kasama, Takeshi/K-5383-2012 NR 49 TC 118 Z9 118 U1 5 U2 12 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAY PY 2002 VL 37 IS 5 BP 737 EP 761 AR UNSP MS#4660 PG 25 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 558MR UT WOS:000175971600010 ER PT J AU Hartley, LE Drew, JE Long, KS Knigge, C Proga, D AF Hartley, LE Drew, JE Long, KS Knigge, C Proga, D TI Testing the line-driven disc wind model: time-resolved ultraviolet spectroscopy of IX Vel and V3885 Sgr SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE line : profiles; binaries : close; stars : mass-loss; novae, cataclysmic variables; ultraviolet : stars ID UV RESONANCE LINES; UX-URSAE-MAJORIS; CATACLYSMIC VARIABLES; ACCRETION DISKS; PHOTOMETRY; RADIATION; SPECTRA; DEPENDENCE; VELORUM; STARS AB To confront the predictions of the most recent line-driven disc wind models with observational evidence, we have obtained Hubble Space Telescope (HST ) STIS (1180-1700 Angstrom) echelle spectra of the nova-like variables IX Vel and V3885 Sgr at three epochs. The targets were observed in time-tag mode for similar to2000 s on each occasion, allowing us to study the spectral time evolution on time-scales down to similar to10 s. The mean ultraviolet (UV) spectra are characterized by the wind signature of broad blueshifted absorption in Lyalpha , N V lambda 1240, Si IV lambda 1398, C V lambda 1549 and He II lambda 1640. There is very little redshifted emission other than in C IV. Narrow blueshifted absorption dips, superposed on the broad absorption at around -900 km s(-1) , accompany periods of well-developed wind activity. The continuum level and mean line profiles vary markedly from observation to observation - with the wind signatures almost disappearing in one epoch of observation of IX Vel. The strong positive correlation between UV brightness and wind activity predicted by line-driven disc wind models is disobeyed by both binaries. The wind signatures in the UV spectrum of IX Vel are revealed to be remarkably steady on time-scales ranging from similar to10 to similar to1000 s. More variability is seen in V3885 Sgr, the binary with the lower opacity outflow. However, there is only one epoch in which the line profile changes significantly in similar to100 s or less. Narrow absorption dips, when present, show only smooth, small changes in velocity. We surmise that these may trace the orbital motion of the white dwarf. The near-absence of line profile variability on the shorter 10- to 100-s time-scales, and the lack of correlation between wind activity and luminosity, could both arise if a non-radiative factor such as the magnetic field geometry controls the mass loss rate in these binaries. C1 ICSTM, Blackett Lab, Dept Phys, London, England. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. Univ Colorado, JILA, Boulder, CO 80309 USA. RP Hartley, LE (reprint author), ICSTM, Blackett Lab, Dept Phys, Prince Consort Rd, London, England. OI Drew, Janet/0000-0003-1192-7082 NR 42 TC 31 Z9 31 U1 0 U2 1 PU BLACKWELL PUBLISHING LTD PI OXFORD PA 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD MAY 1 PY 2002 VL 332 IS 1 BP 127 EP 143 DI 10.1046/j.1365-8711.2002.05277.x PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 546AN UT WOS:000175249900018 ER PT J AU Scranton, R AF Scranton, R TI Modelling galaxy clustering by colour SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE methods : numerical; large-scale structure of Universe ID CONDENSATION; UNIVERSE; PROFILES; HALOES; BIAS AB We extend the mass-halo formalism for analytically generating power spectra to allow for the different clustering behaviour observed in galaxy subpopulations. Although applicable to other separations, we concentrate our methods on a simple separation by rest-frame colour into 'red' and 'blue' subpopulations through modifications to the (M) relations and halo distribution functions for each of the subpopulations. This sort of separation is within the capabilities of the current generations of simulations as well as galaxy surveys, suggesting a potentially powerful observational constraint for current and future simulations. In anticipation of this, we demonstrate the sensitivity of the resulting power spectra to the choice of model parameters. C1 Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. RP Scranton, R (reprint author), Univ Chicago, Dept Astron & Astrophys, 5640 S Ellis Ave, Chicago, IL 60637 USA. NR 23 TC 26 Z9 27 U1 0 U2 0 PU BLACKWELL PUBLISHING LTD PI OXFORD PA 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD MAY PY 2002 VL 332 IS 3 BP 697 EP 704 DI 10.1046/j.1365-8711.2002.05325.x PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 553FD UT WOS:000175664400016 ER PT J AU Akylas, A Georgantopoulos, I Griffiths, RG Papadakis, IE Mastichiadis, A Warwick, RS Nandra, K Smith, DA AF Akylas, A Georgantopoulos, I Griffiths, RG Papadakis, IE Mastichiadis, A Warwick, RS Nandra, K Smith, DA TI Monitoring RXTE observations of Markarian 348: the origin of the column density variations SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE galaxies : active; galaxies : individual; Mrk 348; quasars : general; galaxies : Seyfert; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; ABSORPTION; GALAXIES; NGC-7582 AB We analyse 37 RXTE observations of the type 2 Seyfert galaxy Mrk 348 obtained over a period of 14 months. We confirm the spectral variability previously reported by Smith, Georgantopoulos & Warwick, in the sense that the column density decreases by a factor of similar to3 as the count rate increases. Column density variations could possibly originate either from the random drift of clouds within the absorption screen, or from photoionization processes. Our modelling of the observed variations implies that the first scenario is more likely. These clouds should lie within a distance of >2 light-years from the source, having a diameter of a few light-days and a density of >10(7) cm(-3) , hence probably residing outside the broad-line region. C1 Natl Observ Athens, Inst Astron & Astrophys, Athens 15236, Greece. Univ Athens, Dept Phys, Athens 15783, Greece. Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England. Univ Crete, Dept Phys, Iraklion 73010, Greece. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, College Pk, MD 20742 USA. RP Georgantopoulos, I (reprint author), Natl Observ Athens, Inst Astron & Astrophys, 1 Metaxa B Pavlou, Athens 15236, Greece. RI Papadakis, Iossif/C-3235-2011; Georgantopoulos, Ioannis/L-3687-2013; Akylas, Athanassios/K-4629-2013 NR 17 TC 10 Z9 10 U1 0 U2 0 PU BLACKWELL PUBLISHING LTD PI OXFORD PA 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD MAY PY 2002 VL 332 IS 2 BP L23 EP L27 DI 10.1046/j.1365-8711.2002.05392.x PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 551AF UT WOS:000175536700024 ER PT J AU Sun, CJ Hao, Z Ghil, M Neelin, JD AF Sun, CJ Hao, Z Ghil, M Neelin, JD TI Data assimilation for a coupled ocean-atmosphere model. Part I: Sequential state estimation SO MONTHLY WEATHER REVIEW LA English DT Article ID NINO SOUTHERN OSCILLATION; TROPICAL PACIFIC-OCEAN; ENSEMBLE KALMAN FILTER; EL-NINO; SEA-LEVEL; GENERALIZED INVERSION; CIRCULATION MODEL; NUMERICAL-MODEL; ALTIMETER DATA; ENSO AB The assimilation problem for the coupled ocean-atmosphere system in the tropical Pacific is investigated using an advanced sequential estimator, the extended Kalman filter (EKF). The intermediate coupled model used in this study consists of an upper-ocean model and a steady-state atmospheric response to it. Model errors arise from the uncertainty in atmospheric wind stress. Data assimilation is applied in this idealized context to produce a time-continuous, dynamically consistent description of the model's El Nino-Southern Oscillation, based on incomplete and inaccurate observations. This study has two parts: Part I (the present paper) deals with state estimation for the coupled system, assuming that model parameters are correct, while Part II will deal with simultaneous state and parameter estimation. The dynamical structure of forecast errors is estimated sequentially using a linearized Kalman filter and compared with that of an uncoupled ocean model. The coupling produces large changes in the structure of the error-correlation field. For example, error correlations with opposite signs in the western and eastern part of the model basin are caused by wind stress feedbacks. The full EKF method is used to assimilate various model-generated synthetic oceanic datasets into the coupled model in an identical-twin framework. The assimilated datasets include the sea surface temperature and a combination of wave velocities and thermocline depth anomaly. With the EKF, the model's forecast-assimilation cycle is able to estimate correctly the phase and amplitude of the basic ENSO oscillation while using very few observations. This includes a set of observations that only cover a single meridional section of the ocean, preferably in the eastern basin. C1 Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90024 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA. RP Sun, CJ (reprint author), NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Mail code 974, Greenbelt, MD 20771 USA. RI Sun, Chaojiao/A-9569-2011; Neelin, J. David/H-4337-2011 OI Sun, Chaojiao/0000-0002-7030-0485; NR 68 TC 16 Z9 16 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD MAY PY 2002 VL 130 IS 5 BP 1073 EP 1099 DI 10.1175/1520-0493(2002)130<1073:DAFACO>2.0.CO;2 PG 27 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 537WH UT WOS:000174782300001 ER PT J AU Gelaro, R Rosmond, T Daley, R AF Gelaro, R Rosmond, T Daley, R TI Singular vector calculations with an analysis error variance metric SO MONTHLY WEATHER REVIEW LA English DT Article ID ENSEMBLE PREDICTION SYSTEM; ADAPTIVE OBSERVATIONS; OPTIMAL PERTURBATIONS; TARGETING OBSERVATIONS; BAROCLINIC WAVES; PREDICTABILITY; FASTEX; SENSITIVITY; MODEL; CIRCULATION AB Singular vectors of the navy's global forecast model are calculated using an initial norm consistent with an estimate of analysis error variance provided by the Naval Research Laboratory's (NRL) Atmospheric Variational Data Assimilation System (NAVDAS). The variance estimate is based on a decomposition of the block diagonal preconditioner for the conjugate-gradient descent algorithm used in NAVDAS. Because the inverse square root of the operator that defines the variance norm is readily computed, the leading singular vectors are obtained using a standard Lanczos algorithm, as with diagonal norms such as total energy. The resulting singular vectors are consistent with the expected distribution of analysis errors. Compared with singular vectors based on a total energy norm, the variance singular vectors at initial time have less amplitude over well-observed areas, as well as greater amplitude in the middle and upper troposphere. The variance singular vectors are in some ways similar to the full covariance (Hessian) singular vectors developed at the European Centre for Medium-Range Weather Forecasts (ECMWF). However, unlike the Hessian singular vectors, the variance singular vectors exhibit only minor difference in structure and growth rate compared with total energy singular vectors. This is because the variance singular vectors exclude covariance information used in NAVDAS that significantly penalizes smaller scales. The 20 leading analysis error variance singular vectors explain approximately the same fraction of forecast error variance as the total energy singular vectors in a linear context, but less in a nonlinear context. Deficiencies in the current experimental configuration are among the reasons suspected for this. Implications for targeted observing are also examined. The results show that the variance norm can have a significant impact on determining the locations for supplemental observations. C1 Naval Res Lab, Monterey, CA USA. RP Gelaro, R (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. NR 50 TC 34 Z9 35 U1 0 U2 1 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 MAY PY 2002 VL 130 IS 5 BP 1166 EP 1186 DI 10.1175/1520-0493(2002)130<1166:SVCWAA>2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 537WH UT WOS:000174782300005 ER PT J AU Fukumori, I AF Fukumori, I TI A partitioned Kalman filter and smoother SO MONTHLY WEATHER REVIEW LA English DT Article ID NINO-SOUTHERN OSCILLATION; OCEAN CIRCULATION MODEL; TROPICAL PACIFIC-OCEAN; DATA ASSIMILATION; SEA-LEVEL; EL-NINO; TOPEX/POSEIDON; OCEANOGRAPHY AB A new approach is advanced for approximating Kalman filtering and smoothing suitable for oceanic and atmospheric data assimilation. The method solves the larger estimation problem by partitioning it into a series of smaller calculations. Errors with small correlation distances are derived by regional approximations, and errors associated with independent processes are evaluated separately from one another. The overall uncertainty of the model state, as well as the Kalman filter and smoother, is approximated by the sum of the corresponding individual components. The resulting smaller dimensionality of each separate element renders application of Kalman filtering and smoothing to the larger problem much more practical than otherwise. In particular, the approximation makes high-resolution global eddy-resolving data assimilation computationally viable. The approach is described and its efficacy demonstrated using a simple one-dimensional shallow water model. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Fukumori, I (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 300-323, Pasadena, CA 91109 USA. NR 22 TC 102 Z9 104 U1 3 U2 10 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 MAY PY 2002 VL 130 IS 5 BP 1370 EP 1383 DI 10.1175/1520-0493(2002)130<1370:APKFAS>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 537WH UT WOS:000174782300017 ER PT J AU Li, JLF Kohler, M Farrara, JD Mechoso, CR AF Li, JLF Kohler, M Farrara, JD Mechoso, CR TI The impact of stratocumulus cloud radiative properties on surface heat fluxes simulated with a general circulation model SO MONTHLY WEATHER REVIEW LA English DT Article ID WATER-CONTENT; PARAMETERIZATION; LAYER AB When sea surface temperatures are prescribed at its lower boundary, the University of California, Los Angeles (UCLA) atmospheric general circulation model (AGCM) produces a realistic simulation of planetary boundary layer (PBL) stratocumulus cloud incidence. Despite this success, net surface solar fluxes are generally overpredicted in comparison to Earth Radiation Budget Experiment (ERBE) derived data in regions characterized by persistent stratocumulus cloud decks. It is suggested that this deficiency is due to the highly simplified formulation of the PBL cloud optical properties. A new formulation of PBL cloud optical properties is developed based on an estimate of the stratocumulus cloud liquid water path. The January and July mean net surface solar fluxes simulated by the revised AGCM are closer to ERBE-derived values in regions where stratocumulus clouds are frequently observed. The area-averaged estimated error reductions range from 24 (Peru region) to 53 W m(-2) (South Pacific storm track region). The results emphasize that surface heat fluxes are very sensitive to the radiative properties of stratocumulus clouds and that a realistic simulation of both the geographical distribution of stratocumulus clouds and their optical properties is crucial. C1 Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. NASA, Res Data Corp, Data Assimilat Off, Greenbelt, MD USA. European Ctr Medium Range Weather Forecasts, Reading RG2 9AX, Berks, England. RP Farrara, JD (reprint author), Univ Calif Los Angeles, Dept Atmospher Sci, 405 Hilgard Ave, Los Angeles, CA 90095 USA. NR 17 TC 22 Z9 22 U1 0 U2 2 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 MAY PY 2002 VL 130 IS 5 BP 1433 EP 1441 DI 10.1175/1520-0493(2002)130<1433:TIOSCR>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 537WH UT WOS:000174782300022 ER PT J AU Koekemoer, AM O'Dea, CP Sarazin, CL McNamara, BR Donahue, M Voit, M Baum, SA Gallimore, JF AF Koekemoer, AM O'Dea, CP Sarazin, CL McNamara, BR Donahue, M Voit, M Baum, SA Gallimore, JF TI Interactions between the Abell 2597 central radio source and dense gas in its host galaxy SO NEW ASTRONOMY REVIEWS LA English DT Article; Proceedings Paper CT International Workshop on Life Cycles of Radio Galaxies CY JUL 15-17, 1999 CL SPACE TELESCOPE SCI INST, BALTIMORE, MARYLAND HO SPACE TELESCOPE SCI INST DE cooling flows; galaxies : active; galaxies : clusters; individual (Abell 2597); radio continuum : galaxies ID COOLING FLOWS; CLUSTERS; EMISSION AB We present a detailed HST/WFPC2 study of the complex network of emission-line filaments and blue continuum emission associated with the lobes of the radio source at the center of the nearby strong cooling-flow cluster Abell 2597. This object is a prototypical "blue-lobed" cluster radio galaxy. We discuss ways in which the radio source is interacting with the cool dense gas around it, and derive detailed constraints on the physical properties of the gas. We also resolve the blue continuum emission, which is most likely due to young stars, and discuss possible relationships between the radio source, the supply of gas and the triggering mechanisms for the active nucleus and the star formation. (C) 2002 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Space Telecope Sci Inst, Baltimore, MD 21218 USA. Univ Virginia, Astron Dept, Charlottesville, VA 22903 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NRAO, Charlottesville, VA 22903 USA. RP Koekemoer, AM (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Donahue, Megan/B-5361-2012; OI Koekemoer, Anton/0000-0002-6610-2048 NR 15 TC 2 Z9 2 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 1387-6473 J9 NEW ASTRON REV JI New Astron. Rev. PD MAY PY 2002 VL 46 IS 2-7 BP 149 EP 153 AR PII S1387-6473(01)00170-1 DI 10.1016/S1387-6473(01)00170-1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 554CX UT WOS:000175717000016 ER PT J AU Koekemoer, AM Bicknell, GV AF Koekemoer, AM Bicknell, GV TI Shock ionization of line-emitting gas in the radio galaxy PKS 0349-27 SO NEW ASTRONOMY REVIEWS LA English DT Article; Proceedings Paper CT International Workshop on Life Cycles of Radio Galaxies CY JUL 15-17, 1999 CL SPACE TELESCOPE SCI INST, BALTIMORE, MARYLAND HO SPACE TELESCOPE SCI INST DE galaxies : active; galaxies : individual (PKS 0349-27); radio continuum : galaxies ID EXTENDED IONIZED-GAS; EMISSION AB The FRII radio galaxy PKS 0349-27 contains a luminous emission-line nebula, extending over several tens of kpc around its host galaxy. We investigate the spatial distribution of the kinematics, line ratios and total emission-tine flux of the gas by means of a detailed series of long-slit spectra that cover its entire extent. We show that the physical properties of the line-emitting gas, in particular its ionization properties, excitation state, dynamics and energetics, suggest a scenario involving auto-ionizing shocks as the dominant ionization mechanism. (C) 2002 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Mt Stromlo & Siding Spring Observ, Weston, ACT 2611, Australia. RP Koekemoer, AM (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. OI Koekemoer, Anton/0000-0002-6610-2048 NR 13 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 1387-6473 J9 NEW ASTRON REV JI New Astron. Rev. PD MAY PY 2002 VL 46 IS 2-7 BP 197 EP 201 AR PII S1387-6473(01)00179-8 DI 10.1016/S1387-6473(01)00179-8 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 554CX UT WOS:000175717000025 ER PT J AU Sambruna, RM Eracleous, M Mushotzky, RF AF Sambruna, RM Eracleous, M Mushotzky, RF TI Constraining the central engine of radio-loud AGNs SO NEW ASTRONOMY REVIEWS LA English DT Article; Proceedings Paper CT International Workshop on Life Cycles of Radio Galaxies CY JUL 15-17, 1999 CL SPACE TELESCOPE SCI INST, BALTIMORE, MARYLAND HO SPACE TELESCOPE SCI INST DE galaxies : active; quasars; radio continuum : galaxies; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; ADVECTION-DOMINATED ACCRETION; X-RAY-SPECTRA; BLACK-HOLES; LINE; GALAXIES; ASCA; QUASARS; REFLECTION; EMISSION AB We present an X-ray spectral survey of radio-loud (RL) AGNs using ASCA and RXTE. The goal was to study the structure of their central engines and compare it to that of their radio-quiet (RQ) counterparts. We find systematic differences in the X-ray properties of the two AGN classes. Specifically, RL AGNs exhibit weaker Fe lines and reflection components than RQ AGNs, indicating smaller solid angles subtended by the re-processing medium to the X-ray source. The circumnuclear environs of RL and RQ AGNs also differ: large amounts of cold gas are detected in Broad Line Radio Galaxies and Quasars, contrary to what is found in Seyfert galaxies of similar X-ray luminosity. We also discuss ASCA observations of Weak Line Radio Galaxies, a distinct subset of radio galaxies which may harbor a low-luminosity AGN powered by an advection-dominated accretion flow. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Penn State Univ, Dept Astron & Astrophys, State Coll, PA 16802 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Sambruna, RM (reprint author), Penn State Univ, Dept Astron & Astrophys, 525 Davey Lab, State Coll, PA 16802 USA. NR 29 TC 12 Z9 12 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 1387-6473 J9 NEW ASTRON REV JI New Astron. Rev. PD MAY PY 2002 VL 46 IS 2-7 BP 215 EP 220 AR PII S1387-6473(01)00183-X DI 10.1016/S1387-6473(01)00183-X PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 554CX UT WOS:000175717000029 ER PT J AU Wehrle, AE Jones, DL Meier, DL Piner, BG AF Wehrle, AE Jones, DL Meier, DL Piner, BG TI The radio jets and accretion disk in NGC 4261 SO NEW ASTRONOMY REVIEWS LA English DT Article; Proceedings Paper CT International Workshop on Life Cycles of Radio Galaxies CY JUL 15-17, 1999 CL SPACE TELESCOPE SCI INST, BALTIMORE, MARYLAND HO SPACE TELESCOPE SCI INST DE accretion disks; galaxies : active; galaxies : individual (NGC 4261); galaxies : jets ID NGC-4261 AB The nearby (41 Mpc) FR-I radio galaxy NGC 4261 contains a pair of symmetric kpc-scale jets, emerging from the vicinity of a 5 X 10(8) M-circle dot black hole. We present new VLBA observations of NGC 4261 at 22 and 43 GHz which we combine with previous observations at 1.6 and 8.4 GHz. We find that the orientation of the radio jet axis is the same on pc and kpc 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)) years. This suggests that a single merger event may be responsible for the supply of gas in the nucleus of NGC 4261. We also use our VLBA images to probe the structure of the accretion disk on sub-parsec scales through free-free absorption of synchrotron emission from the base of symmetric radio jets. (C) 2002 Published by Elsevier Science B.V. C1 CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wehrle, AE (reprint author), CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Mail Code 100-22, Pasadena, CA 91125 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 1387-6473 J9 NEW ASTRON REV JI New Astron. Rev. PD MAY PY 2002 VL 46 IS 2-7 BP 235 EP 238 AR PII S1387-6473(01)00187-7 DI 10.1016/S1387-6473(01)00187-7 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 554CX UT WOS:000175717000033 ER PT J AU Meier, DL AF Meier, DL TI Grand unification of AGN and the accretion and spin paradigms SO NEW ASTRONOMY REVIEWS LA English DT Article; Proceedings Paper CT International Workshop on Life Cycles of Radio Galaxies CY JUL 15-17, 1999 CL SPACE TELESCOPE SCI INST, BALTIMORE, MARYLAND HO SPACE TELESCOPE SCI INST DE accretion disks; black hole physics; galaxies : jets; radio continuum : galaxies; quasars : general ID ACTIVE GALACTIC NUCLEI; BLACK-HOLE; ASTROPHYSICAL JETS; RADIO-LOUD; DISKS; SIMULATIONS; FANAROFF; GALAXIES; ENERGY; DRIVEN AB While attempts to unify certain classes of AGN using orientation and environmental effects have been successful, it is widely recognized that intrinsic properties of the accreting black hole system also must play a role in determining the appearance of such an object. In addition to mass and accretion rate, the angular momentum (or spin) of the black hole can play a crucial role in determining the power of a relativistic jet that is generated by magneto-hydrodynamic acceleration near the hole. In this paper a scenario is presented, based on accretion theory and recent models of MHD jet production, in which the primary (although not only) parameter differentiating between radio loud and quiet objects is the black hole spin, and that determining quasar vs. radio galaxy is the accretion rate. A Surprising number of desirable features result from these simple concepts and the accompanying equations. In addition, there are several testable predictions that can determine whether this grand unification scheme has further merit. (C) 2002 Published by Elsevier Science B.V. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Meier, DL (reprint author), CALTECH, Jet Prop Lab, 238-332,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 30 TC 34 Z9 34 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 1387-6473 J9 NEW ASTRON REV JI New Astron. Rev. PD MAY PY 2002 VL 46 IS 2-7 BP 247 EP 255 AR PII S1387-6473(01)00189-0 DI 10.1016/S1387-6473(01)00189-0 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 554CX UT WOS:000175717000035 ER PT J AU Benjapiyaporn, C Davis, GD Leonardi, E Leong, SS Timchenko, V de Groh, HC AF Benjapiyaporn, C Davis, GD Leonardi, E Leong, SS Timchenko, V de Groh, HC TI Numerical study of G-jitter during directional solidification SO NUMERICAL HEAT TRANSFER PART A-APPLICATIONS LA English DT Article ID CRYSTAL-GROWTH; BRIDGMAN AB A study of directional solidification of a weak binary alloy (specifically, Bi-1%Sn) using a fixed grid single domain approach has been undertaken. The enthalpy method is used to solve for the temperature field over the computational domain, including both the solid and liquid phases. The vorticity-stream function formulation is used to describe thermosolutal convection in the liquid region. Results on the solute field and segregation are presented, showing the effects of the periodic disturbances for a range of amplitudes and frequencies (multicomponent) and for actual acceleration data obtained during a space flight. C1 Univ New S Wales, Sch Mech & Mfg Engn, Computat Fluid Dynam Res Lab, Sydney, NSW 2052, Australia. NASA, Glenn Res Ctr, Cleveland, OH USA. RP Benjapiyaporn, C (reprint author), Univ New S Wales, Sch Mech & Mfg Engn, Computat Fluid Dynam Lab, Sydney, NSW 2052, Australia. NR 8 TC 6 Z9 6 U1 0 U2 0 PU TAYLOR & FRANCIS INC PI PHILADELPHIA PA 325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA SN 1040-7782 J9 NUMER HEAT TR A-APPL JI Numer. Heat Tranf. A-Appl. PD MAY PY 2002 VL 41 IS 6-7 BP 597 EP 610 DI 10.1080/104077802317418232 PG 14 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA 555MT UT WOS:000175798400003 ER PT J AU Raju, MS AF Raju, MS TI On the importance of chemistry/turbulence interactions in spray computations SO NUMERICAL HEAT TRANSFER PART B-FUNDAMENTALS LA English DT Article ID FLAMES AB This article presents results from spray computations performed as a part of the National Combustion Code (NCC) development activity. The NCC is being developed with the aim of advancing the prediction tools used in the design of advanced technology combustors based oil multidimensional computational methods. The solution procedure combines the novelly of the application of the scalar Monte Carlo probability density function (PDF) method to the modeling of turbulent spray flames with the ability to perforin the computations on unstructured grids with parallel computing. A validation summary is provided for two different cases: one is a reacting spray without swirl, and the other is a similar spray but non-reacting. The comparisons involving both gas-phase and droplet velocities, droplet size distributions, and gas-phase temperatures show reasonable agreement with the available experimental data. The comparisons involve both the results obtained from the use of the Monte Carlo PDF method as well as those obtained from the conventional computational fluid dynamics (CFD) solution. The detailed comparisons clearly highlight the importance of chemistry/turbulence interactions in the modeling of reacting splays. The results from the PDF and non-PDF methods were found to be markedly different, and the PDF solution is closer to the reported experimental data. The PDF computations predict that most of the combustion occurs in a predominantly diffusion-flame environment and the rest in a predominantly premixed-flame environment. However, the non-PDF solution predicts incorrectly that the combustion occurs in a predominantly vaporization-controlled regime. The Monte Carlo temperature distribution shows that the functional form of the PDF for the temperature fluctuations varies substantially from point to point. The results bring to the fore some of the deficiencies associated with the rise of assumed-shape PDF methods ill spray computations. Finally, we end the article by demonstrating the computational viability of the present solution procedure for its use in 3-D combustor calculations by summarizing the results of parallel performance for a 3-D test case with periodic boundary conditions. For the 3-D case, the parallel performance of all the three solvers (CFD, PDF, and spray) has been found to be good when the computations were performed on a 24-processor SGI Origin workstation. C1 NASA, Glenn Res Ctr, QSS Inc, Cleveland, OH 44135 USA. RP Raju, MS (reprint author), NASA, Glenn Res Ctr, QSS Inc, 21000 Brookpk Rd,Mail Stop 500-QSS, Cleveland, OH 44135 USA. NR 9 TC 17 Z9 17 U1 0 U2 2 PU TAYLOR & FRANCIS INC PI PHILADELPHIA PA 325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA SN 1040-7790 J9 NUMER HEAT TR B-FUND JI Numer Heat Tranf. B-Fundam. PD MAY PY 2002 VL 41 IS 5 BP 409 EP 432 DI 10.1080/104077902753725885 PG 24 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA 556NW UT WOS:000175856700001 ER PT J AU Hart, RC Herring, GC Balla, RJ AF Hart, RC Herring, GC Balla, RJ TI Common-path heterodyne laser-induced thermal acoustics for seedless laser velocimetry SO OPTICS LETTERS LA English DT Article AB We demonstrate the use of a novel technique for the detection of heterodyne laser-induced thermal acoustic signals that allows the construction of a highly stable seedless laser velocimeter. A common-path configuration is combined with quadrature detection to provide flow direction, to greatly improve robustness to misalignment and vibration, and to give reliable velocity measurement at low-flow velocities. Comparison with Pitot tube measurements in the free stream of a wind tunnel shows root-mean-square errors of 0.67 m/s over the 0-55-m/s velocity range. (C) 2002 Optical Society of America. C1 NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Adv Measurement & Diagnost Branch, Hampton, VA 23681 USA. RP Hart, RC (reprint author), NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. NR 8 TC 10 Z9 10 U1 0 U2 1 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 MAY 1 PY 2002 VL 27 IS 9 BP 710 EP 712 DI 10.1364/OL.27.000710 PG 3 WC Optics SC Optics GA 546QC UT WOS:000175284000012 PM 18007907 ER PT J AU Eraso, FE Analoui, M Watson, AB Rebeschini, R AF Eraso, FE Analoui, M Watson, AB Rebeschini, R TI Impact of lossy compression on diagnostic accuracy of radiographs for periapical lesions SO ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS LA English DT Article ID CARIES DETECTION; IMAGES; NOISE; FILM AB Objectives. The purpose of this study was to evaluate the lossy Joint Photographic Experts Group compression for endodontic pretreatment digital radiographs. Study design. Fifty clinical charge-coupled device-based, digital radiographs depicting periapical areas were selected. Each image was compressed at 2, 4, 8, 16, 32, 48, and 64 compression ratios. One root per image was marked for examination. Images were randomized and viewed by four clinical observers under standardized viewing conditions. Each observer read the image set three times, with at least two weeks between each reading. Three pre-selected sites per image (mesial, distal, apical) were scored on a five-scale score confidence scale. A panel of three examiners scored the uncompressed images, with a consensus score for each site. The consensus score was used as the baseline for assessing the impact of lossy compression on the diagnostic values of images. The mean absolute error between consensus and observer scores was computed for each observer, site, and reading session. Results. Balanced one-way analysis of variance for all observers indicated that for compression ratios 48 and 64, there was significant difference between mean absolute error of uncompressed and compressed images (P < .05). After converting the five-scale score to two-level diagnostic values, the diagnostic accuracy was strongly correlated (R-2 = 0.91) with the compression ratio. Conclusion. The results of this study suggest that high compression ratios can have a severe impact on the diagnostic quality of the digital radiographs for detection of periapical lesions. C1 Nova SE Univ, Coll Dent Med, Dept Oral & Maxillofacial Radiol & Pathol, Ft Lauderdale, FL 33314 USA. Indiana Univ, Sch Dent, Indianapolis, IN USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Eraso, FE (reprint author), Nova SE Univ, Coll Dent Med, Dept Oral & Maxillofacial Radiol & Pathol, Ft Lauderdale, FL 33314 USA. NR 23 TC 14 Z9 14 U1 0 U2 0 PU MOSBY, INC PI ST LOUIS PA 11830 WESTLINE INDUSTRIAL DR, ST LOUIS, MO 63146-3318 USA SN 1079-2104 J9 ORAL SURG ORAL MED O JI Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod. PD MAY PY 2002 VL 93 IS 5 BP 621 EP 625 DI 10.1067/moe.2002.122640 PG 5 WC Dentistry, Oral Surgery & Medicine SC Dentistry, Oral Surgery & Medicine GA 568CA UT WOS:000176523800023 PM 12075215 ER PT J AU Hecht, H Kaiser, MK Savelsbergh, GJP van der Kamp, J AF Hecht, H Kaiser, MK Savelsbergh, GJP van der Kamp, J TI The impact of spatiotemporal sampling on time-to-contact judgments SO PERCEPTION & PSYCHOPHYSICS LA English DT Article ID SIMULATED SELF-MOTION; INFORMATION-SOURCES; PREDICTION-MOTION; ACTIVE CONTROL; ARRIVAL-TIME; VISUAL SPACE; JUDGING TIME; COLLISION; EXTRAPOLATION; PERCEPTION AB When motion in the frontoparallel plane is temporally sampled, it is often perceived to be slower than its continuous counterpart. This finding stands in contrast to humans' ability to extrapolate and anticipate constant-velocity motion. We investigated whether this sampling bias generalizes to motion in the sagittal plane (i.e., objects approaching the observer). We employed a paradigm in which observers judged the arrival time of an oncoming object. We found detrimental effects of time sampling on both perceived time to contact and time to passage. Observers systematically overestimated the time it would take a frontally approaching object to intersect their eye plane. To rule out artifacts inherent in computer simulation, we replicated the experiment, using real objects. The bias persisted and proved to be robust across a large range of temporal and spatial variations. Energy and pooling mechanisms are discussed in an attempt to understand the effect. C1 MIT, Man Vehicle Lab, Cambridge, MA 02139 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Vrije Univ Amsterdam, Amsterdam, Netherlands. RP Hecht, H (reprint author), MIT, Man Vehicle Lab, 77 Massachusetts Ave,Bldg 37-219, Cambridge, MA 02139 USA. RI Hecht, Heiko/H-3106-2011 NR 73 TC 7 Z9 7 U1 0 U2 5 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 2002 VL 64 IS 4 BP 650 EP 666 DI 10.3758/BF03194733 PG 17 WC Psychology; Psychology, Experimental SC Psychology GA 563NV UT WOS:000176263200012 PM 12132765 ER PT J AU Sergeev, A Karasik, BS Gershenson, M Mitin, V AF Sergeev, A Karasik, BS Gershenson, M Mitin, V TI Electron-phonon scattering in disordered metallic films SO PHYSICA B-CONDENSED MATTER LA English DT Article; Proceedings Paper CT 10th International Conference on Phonon Scattering in Condensed Matter CY AUG 12-17, 2001 CL DARTMOUTH COLL, HANOVER, NEW HAMPSHIRE HO DARTMOUTH COLL DE electron-phonon interaction; disorder AB The quantum interference between 'Pure' electron-phonon and electron-boundary/impurity scattering drastically changes the electron-phonon relaxation rate. If impurities and boundaries vibrate in the same way as the host lattice, the electron-phonon relaxation rate is significantly decreased. In the presence of the scattering potential that does not vibrate with phonons (e.g. rigid boundaries, interelectron scattering) the relaxation rate is substantially enhanced. Current work reviews recent progress in the theoretical investigations. gives quantitative explanations of available low-temperature data, and presents original experimental results for ultrathin Hf at ultralow temperatures. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Wayne State Univ, Dept ECE, Detroit, MI 48202 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Rutgers State Univ, Dept Phys, Piscataway, NJ 08854 USA. RP Sergeev, A (reprint author), Wayne State Univ, Dept ECE, Detroit, MI 48202 USA. RI Karasik, Boris/C-5918-2011 NR 7 TC 5 Z9 5 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 2002 VL 316 BP 328 EP 330 AR PII S0921-4526(02)00499-4 DI 10.1016/S0921-4526(02)00499-4 PG 3 WC Physics, Condensed Matter SC Physics GA 564CL UT WOS:000176297400079 ER PT J AU Kok, P Lee, H Dowling, JP AF Kok, P Lee, H Dowling, JP TI Creation of large-photon-number path entanglement conditioned on photodetection SO PHYSICAL REVIEW A LA English DT Article ID INTERFEROMETRIC OPTICAL LITHOGRAPHY; FREDKIN GATE; QUANTUM; DIFFRACTION AB Large-photon-number path entanglement is an important resource for enhanced precision measurements and quantum imaging. We present a general constructive protocol to create any large-photon-number path-entangled state based on the conditional detection of single photons. The influence of imperfect detectors is considered and an asymptotic scaling law is derived. C1 CALTECH, Jet Prop Lab, Quantum Comp Technol Grp, Sect 367, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, Quantum Comp Technol Grp, Sect 367, Mail Stop 126-347,4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM pieter.kok@jpl.nasa.gov RI Kok, Pieter/B-1658-2010; DOWLING, JONATHAN/L-2749-2013 NR 19 TC 149 Z9 150 U1 0 U2 7 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9926 EI 2469-9934 J9 PHYS REV A JI Phys. Rev. A PD MAY PY 2002 VL 65 IS 5 AR 052104 DI 10.1103/PhysRevA.65.052104 PN A PG 5 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 554PC UT WOS:000175743800020 ER PT J AU Ramirez-Serrano, J DeGraffenreid, W Weiner, J AF Ramirez-Serrano, J DeGraffenreid, W Weiner, J TI Polarization-dependent spectra in the photoassociative ionization of cold atoms in a bright sodium beam SO PHYSICAL REVIEW A LA English DT Article ID MOLECULES; SPECTROSCOPY; COLLISIONS; NA-2 AB We report measurements of cold photoassociative ionization (PAI) spectra obtained from collisions within a slow, bright Na atomic beam. A high-brightness atom flux, obtained by optical cooling and focusing of the atom beam, permits a high degree of alignment and orientation of binary collisions with respect to the laboratory atom-beam axis. The results reveal features of PAI spectra not accessible in conventional magneto-optical trap studies. We take advantage of this high degree of alignment to selectively excite autoionizing doubly excited states of specific symmetry. C1 Univ Maryland, Lab Atom Mol & Opt Sci & Engn, College Pk, MD 20742 USA. RP Ramirez-Serrano, J (reprint author), Jet Prop Lab, Quantum Sci Grp, 4800 Oak Grove Dr,MS 298-100, Pasadena, CA 91104 USA. RI Weiner, John/C-1065-2008 NR 14 TC 6 Z9 6 U1 2 U2 2 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 2002 VL 65 IS 5 AR 052719 DI 10.1103/PhysRevA.65.052719 PN A PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 554PC UT WOS:000175743800100 ER PT J AU Yurtsever, U Dowling, JP AF Yurtsever, U Dowling, JP TI Lorentz-invariant look at quantum clock-synchronization protocols based on distributed entanglement SO PHYSICAL REVIEW A LA English DT Article ID SHARED PRIOR ENTANGLEMENT; STATE; ATOMS AB Recent work has raised the possibility that quantum-information-theory techniques can be used to synchronize atomic clocks nonlocally. One of the proposed algorithms for quantum clock synchronization (QCS) requires distribution of entangled pure singlets to the synchronizing parties [R. Jozsa , Phys. Rev. Lett. 85 2010 (2000)]. Such remote entanglement distribution normally creates a relative phase error in the distributed singlet state, which then needs to be purified asynchronously. We present a relativistic analysis of the QCS protocol that shows that asynchronous entanglement purification is not possible, and, therefore, the proposed QCS scheme remains incomplete. We discuss possible directions of research in quantum-information theory, which may lead to a complete, working QCS protocol. C1 CALTECH, Jet Prop Lab, Quantum Comp Technol Grp, Pasadena, CA 91109 USA. RP Yurtsever, U (reprint author), CALTECH, Jet Prop Lab, Quantum Comp Technol Grp, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI DOWLING, JONATHAN/L-2749-2013 NR 16 TC 2 Z9 2 U1 1 U2 3 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 2002 VL 65 IS 5 AR 052317 DI 10.1103/PhysRevA.65.052317 PN A PG 6 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 554PC UT WOS:000175743800057 ER PT J AU Lin, JC AF Lin, JC TI Review of research on low-profile vortex generators to control boundary-layer separation SO PROGRESS IN AEROSPACE SCIENCES LA English DT Review ID WINGS AB An in-depth review of boundary-layer flow-separation control by a passive method using low-profile vortex generators is presented. The generators are defined as those with a device height between 10% and 50% of the boundary-layer thickness. Key results are presented for several research efforts, all of which were performed within the past decade and a half where the majority of these works emphasize experimentation with some recent efforts on numerical simulations. Topics of discussion consist of both basic fluid dynamics and applied aerodynamics research. The fluid dynamics research includes comparative studies on separation control effectiveness as well as device-induced vortex characterization and correlation. The comparative studies cover the controlling of low-speed separated flows in adverse pressure gradient and supersonic shock-induced separation. The aerodynamics research includes several applications for aircraft performance enhancement and covers a wide range of speeds. Significant performance improvements are achieved through increased lift and/or reduced drag for various airfoils-low-Reynolds number, high-lift, and transonic-as well as highly swept wings. Performance enhancements for non-airfoil applications include aircraft interior noise reduction, inlet flow distortion alleviation inside compact ducts, and a more efficient overwing fairing. The low-profile vortex generators are best for being applied to applications where flow-separation locations are relatively fixed and the generators can be placed reasonably close upstream of the separation. Using the approach of minimal near-wall protuberances through substantially reduced device height, these devices can produce streamwise vortices just strong enough to overcome the separation without unnecessarily persisting within the boundary layer once the flow-control objective is achieved. Practical advantages of low-profile vortex generators, such as their inherent simplicity and low device drag, are demonstrated to be critically important for many applications as well. Published by Elsevier Science Ltd. C1 NASA, Langley Res Ctr, Flow Phys & Control Branch, Hampton, VA 23681 USA. RP Lin, JC (reprint author), NASA, Langley Res Ctr, Flow Phys & Control Branch, Hampton, VA 23681 USA. NR 49 TC 222 Z9 242 U1 12 U2 96 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0376-0421 J9 PROG AEROSP SCI JI Prog. Aeosp. Sci. PD MAY-JUL PY 2002 VL 38 IS 4-5 BP 389 EP 420 AR PII S0376-0421(02)00010-6 DI 10.1016/S0376-0421(02)00010-6 PG 32 WC Engineering, Aerospace SC Engineering GA 616XZ UT WOS:000179329900004 ER PT J AU Tinto, M AF Tinto, M TI Spacecraft radio occultations using multiple Doppler readouts SO RADIO SCIENCE LA English DT Article DE radio science; spacecraft radio occultations ID GRAVITATIONAL-RADIATION; PHASE SCINTILLATION; TRACKING; VOYAGER; RINGS AB [1] We present an innovative technique that eliminates the phase noise of the onboard frequency reference as the main limiting factor on uplink radio occultations, while allowing full utilization of the expected improvement in SNR over downlink experiments. This technique relies on conducting simultaneous uplink and downlink occultation measurements to synthesize a phase reference of quality determined by the stability of the atomic clock at the ground station, eliminating the frequency fluctuations of the onboard clock as the limiting factor. Atomic frequency standards typically have frequency stability that is about 2-3 orders of magnitude better than space-qualified state-of-the-art clocks. The quantum leap improvement in reference phase stability and, simultaneously, in measurement SNR opens the door to fundamentally new science capabilities for radio occultation observations of planetary rings and atmospheres. In particular, the improvement is expected to enhance sensitivity to tenuous target regions, to increase the dynamic range within opaque regions, and to improve the spatial resolution of mapping large- and small-scale target structures. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Tinto, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 161-260, Pasadena, CA 91109 USA. EM massimo.tinto@jpl.nasa.gov NR 13 TC 1 Z9 1 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0048-6604 EI 1944-799X J9 RADIO SCI JI Radio Sci. PD MAY-JUN PY 2002 VL 37 IS 3 AR 1045 DI 10.1029/2001RS002473 PG 8 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA 610ER UT WOS:000178948200003 ER PT J AU Dokken, ST Winsor, P Markus, T Askne, J Bjork, G AF Dokken, ST Winsor, P Markus, T Askne, J Bjork, G TI ERS SAR characterization of coastal polynyas in the Arctic and comparison with SSM/I and numerical model investigations SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID WAVELET ANALYSIS; SEA; ICE; OCEAN; SHELF; WATER; CLASSIFICATION; TEXTURE; IMAGES; TIDES AB Coastal polynyas in the Arctic basin from the A inter period (January to April) are characterized using ESA European Remote Sensing satellite (ERS)-1/2 Synthetic Aperture Radar (SAR) Precision (Precise Image, PRI) and Browse images. A SAR polynya algorithm is used to delineate open water, new ice, and young ice, and to define the size and shape of polynyas. In order to extract radiometric and contextual information in the ERS SAR PRI images. three different image classification routines are developed and applied. No in situ data have been available for verification of the polynya shapes and sizes, but one of the ice classification routines have been verified earlier using ground truth data. The SAR polynya algorithm is demonstrated to be able to discriminate between the polynya and the surrounding ice area for 85 analyzed cases. The results from the SAR algorithm are compared to ERS Browse images. passive microwave data (a recent Polynya Signature Simulation Method (PSSM), and the Bootstrap and the NASA Team ice concentration algorithms), and a numerical polynya model (NPM) forced by National Center for Environmental Predictions (NCEP) wind fields and air temperatures. The ERS SAR Browse images show a relatively good correlation with the ERS SAR PRI images (.88) while the Special Sensor Microwave Imager (SSM/I) Bootstrap and the NASA Team ice concentration algorithms both have low correlation coefficients (below .3). The PSSM calculates the polynya shape and size, and delineates open water and thin ice. For polynyas of all sizes it has a correlation of .69 compared to the SAR PRI images. For polynyas with widths greater than 10 km the correlation increases to .83. The NPM computes offshore coastal polynya widths, heat exchange. and ice production. Compared to SAR data, it overestimates the maximum size of the polynya by about 15% and has a correlation of .71 compared to the analyzed SAR PRI images. The polynyas in our main investigation area, located at Franz Josef Land, are found to be primarily wind driven. The surrounding large-scale ice drift and tidal currents have little effect on the polynya behavior. One overall conclusion from this investigation is that SAR images processed through the SAR polynya algorithm in combination with the NPM is a powerful tool for investigating and characterizing polynyas at various scales in the Arctic. (C) 2002 Elsevier Science Inc. All rights reserved. C1 Chalmers Univ Technol, Dept Radio & Space Sci, S-41296 Gothenburg, Sweden. Univ Gothenburg, Dept Oceanog, Ctr Earth Sci, Gothenburg, Sweden. NASA, Goddard Space Flight Ctr, UMBC, JCET, Greenbelt, MD 20771 USA. RP Dokken, ST (reprint author), Chalmers Univ Technol, Dept Radio & Space Sci, S-41296 Gothenburg, Sweden. RI Markus, Thorsten/D-5365-2012; OI Askne, Jan/0000-0002-7860-5419 NR 40 TC 10 Z9 12 U1 1 U2 5 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD MAY PY 2002 VL 80 IS 2 BP 321 EP 335 AR PII S0034-4257(01)00313-3 DI 10.1016/S0034-4257(01)00313-3 PG 15 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 543MR UT WOS:000175106200012 ER PT J AU Foster, JE AF Foster, JE TI Compact plasma accelerator device SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB A compact plasma accelerator concept based on plasma production at a magnetic cusp was designed and fabricated. Plume and discharge characteristics of the device were documented using a Faraday probe and a retarding potential analyzer. The discharge current variations with increasing discharge voltage were nonlinear with the discharge current increasing rapidly with voltage. The device demonstrated the capability of generating ion beamlets (similar to80 eV) with downstream peak current densities comparable to that of higher power ion thruster devices (7 mA/cm(2)). In general, the device appeared to operate best at very low flow rates. High propellant utilization fractions (ionization fractions) were measured below 1 SCCM of Xe flow (88% at 0.48 SCCM). Floating potential measurements made downstream of the device were used to estimate the downstream electric field. These measurements, which were used to qualitatively assess beam neutralization, indicated beam neutralization does occur downstream of the device. Based on the measurements, the compact plasma accelerator concept could potentially be used as a low energy ion source for propulsion applications or for low energy plasma/materials processing applications. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Foster, JE (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 18 TC 3 Z9 3 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD MAY PY 2002 VL 73 IS 5 BP 2020 EP 2027 DI 10.1063/1.1464658 PG 8 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 545AN UT WOS:000175194200006 ER PT J AU Ohsaka, K Rednikov, A Sadhal, SS Trinh, EH AF Ohsaka, K Rednikov, A Sadhal, SS Trinh, EH TI Noncontact technique for determining viscosity from the shape relaxation of ultrasonically levitated and initially elongated drops SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID ROTATING LIQUID-DROPS; TENSION; SPACE AB We present a technique that can determine the viscosity of highly viscous liquids, particularly, undercooled liquids that exist at temperatures below their freezing points. The technique involves levitation of a liquid drop using an ultrasonic standing wave, and elongation of the drop by rotating it beyond the point of bifurcation. The elongated drop is then allowed to be restored to its original shape by surface tension driven relaxation. The time-dependent shape parameters of the relaxing drop are related to the viscosity through a relaxation model. In addition, this technique can also determine the surface tension that has a known relationship with the angular velocity at the bifurcation point. The feasibility of the technique is demonstrated by performing the measurement using sucrose solutions as a model liquid drop. The obtained viscosity values show a good correlation with those determined by a falling ball method. (C) 2002 American Institute of Physics. C1 Univ So Calif, Sch Engn, Los Angeles, CA 90089 USA. NASA Headqurters, Washington, DC 20546 USA. RP Ohsaka, K (reprint author), Univ So Calif, Sch Engn, Los Angeles, CA 90089 USA. NR 17 TC 16 Z9 16 U1 0 U2 4 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD MAY PY 2002 VL 73 IS 5 BP 2091 EP 2096 DI 10.1063/1.1470228 PG 6 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 545AN UT WOS:000175194200018 ER PT J AU Orient, OJ Chutjian, A AF Orient, OJ Chutjian, A TI A compact, high-resolution Paul ion trap mass spectrometer with electron-impact ionization SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB A Paul ion trap has been developed for use as a high-resolution mass spectrometer. It is of small size (r(0)=10 mm), having a resolution of m/Deltam=324, which is limited by the machining accuracy of the trap. It has a demonstrated mass range of 1-300 u, and a sensitivity of 2x10(14) counts/Torr s, or to 500 parts per trillion detection sensitivity in a typical vacuum of 10(-5) Torr. Ionization of the room-temperature gas within the trap is carried out with an electron beam traversing the trapping volume. The trap operates in a radio frequency only mode, and no dc is required. Trapping is accomplished within the well depth of the dynamic radio frequency potential, and no cooling gas is required, such as helium. This combination of factors makes the trap potentially of use for autonomous operation in harsh environments requiring low power, low weight, and low volume, such as undersea, on the surface of a planet or asteroid, or in a spacecraft. (C) 2002 American Institute of Physics. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chutjian, A (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 23 Z9 23 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD MAY PY 2002 VL 73 IS 5 BP 2157 EP 2160 DI 10.1063/1.1469675 PG 4 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 545AN UT WOS:000175194200028 ER PT J AU Johnson, AR Chen, T Mead, JL AF Johnson, AR Chen, T Mead, JL TI Modeling step-strain relaxation and cyclic deformations of elastomers SO RUBBER CHEMISTRY AND TECHNOLOGY LA English DT Article; Proceedings Paper CT Fall Meeting of the Rubber-Division of the American-Chemical-Society CY OCT 17-20, 2000 CL CINCINNATI, OHIO SP Amer Chem Soc, Rubber Div ID VISCOELASTIC CONSTITUTIVE MODELS; RUBBER VISCOELASTICITY AB Data for step-strain relaxation and cyclic compressive deformations of highly viscous short elastomer cylinders are modeled using a large strain rubber viscoelastic constitutive theory with a rate-independent friction stress term added. In the tests, both small and large amplitude cyclic compressive strains, in the range of 1% to 10%, were superimposed on steady state compressed strains, in the range of 5% to 200, for frequencies of 1 and 10 Hz. The elastomer cylinders were conditioned prior to each test to soften them. The constants in the viscoelastic-friction constitutive theory are determined by employing a nonlinear least-squares method to fit the analytical stresses for a Maxwell model. which includes friction, to measured relaxation stresses obtained from a 20% step-strain compression test. The simulation of the relaxation data with the nonlinear model is successful at compressive strains of 5%, 10%, 15%, and 20%, Simulations of hysteresis stresses for enforced cyclic compressive strains of 20%+/-5% are made with the model calibrated by the relaxation data. The predicted hysteresis stresses are lower than the measured stresses. C1 NASA, Langley Res Ctr, Army Res Lab, Analyt & Computat Methods Branch, Hampton, VA 23681 USA. Univ Lowell, Dept Plast Engn, Lowell, MA 01854 USA. RP Johnson, AR (reprint author), NASA, Langley Res Ctr, Army Res Lab, Analyt & Computat Methods Branch, MS 240, Hampton, VA 23681 USA. NR 16 TC 0 Z9 0 U1 0 U2 6 PU AMER CHEMICAL SOC INC PI AKRON PA RUBBER DIV UNIV AKRON PO BOX 499, AKRON, OH 44309-0499 USA SN 0035-9475 J9 RUBBER CHEM TECHNOL JI Rubber Chem. Technol. PD MAY-JUN PY 2002 VL 75 IS 2 BP 333 EP 345 DI 10.5254/1.3544982 PG 13 WC Polymer Science SC Polymer Science GA 598XR UT WOS:000178302400013 ER PT J AU Bennett, E AF Bennett, E TI NASA's Helios prototype - Soaring to a new record SO SAMPE JOURNAL LA English DT Article AB On August 13, 2001, off the island of Kauai, an extraordinary innovative aeronautical success was recorded and achieved. This accomplishment introduced the world to one of the capabilities an aircraft called Helios is expected to possess. The Helios prototype is a solar-electric UAV (uninhabited aerial vehicle) flying wing designed to operate comfortably at extreme altitudes. On this date, Helios sustained flight at an altitude of 96,863 feet for over 40 minutes setting a new world record! The new record flight was the consequence of concentrated hard work by NASA Dryden Research Center and AeroVironment, Inc., which have been developing this aircraft for several y,ears under NASA Environmental Research Aircraft and Sensor Technology (ERAST) Project sponsorship. AeroVironment, Inc., is located in Monrovia, California, and is known for product and technology innovation in clean energy and efficient vehicles. C1 NASA, Commercial Technol Off, Washington, DC 20546 USA. RP Bennett, E (reprint author), NASA, Commercial Technol Off, Washington, DC 20546 USA. NR 0 TC 2 Z9 2 U1 2 U2 6 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 2002 VL 38 IS 3 BP 41 EP 47 PG 7 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 543KX UT WOS:000175102100004 ER PT J AU Stern, SA AF Stern, SA TI Journey to the farthest planet SO SCIENTIFIC AMERICAN LA English DT Article C1 SW Res Inst, Dept Space Studies, Boulder, CO USA. NASA, New Horizons Mission Pluto & Kuiper Belt, Washington, DC 20546 USA. RP Stern, SA (reprint author), SW Res Inst, Dept Space Studies, Boulder, CO USA. NR 3 TC 8 Z9 8 U1 0 U2 0 PU SCI AMERICAN INC PI NEW YORK PA 415 MADISON AVE, NEW YORK, NY 10017 USA SN 0036-8733 J9 SCI AM JI Sci.Am. PD MAY PY 2002 VL 286 IS 5 BP 56 EP 63 PG 8 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 539WT UT WOS:000174895200034 PM 11951332 ER PT J AU Walker, JP Houser, PR AF Walker, JP Houser, PR TI Evaluation of the OhmMapper instrument for soil moisture measurement SO SOIL SCIENCE SOCIETY OF AMERICA JOURNAL LA English DT Article ID SENSORS AB An instrument for making rapid measurements of the soil moisture content in the root zone is an essential tool for many applications, including understanding of soil water dynamics, evaluation of agriculture water stress, and validation of soil moisture modeling. Studies have shown that electrical resistance measurements may be used to infer soil moisture content under special circumstances. In this paper, electrical resistivity (resistance multiplied by a geometric factor) measurements of the soil by the Geometrics Inc. OlmMapper instrument are compared with point measurements of soil moisture to a depth of 70 cm. It was found that the OhmMapper resistivity measurements could be used to infer soil moisture content with a coefficient of determination as high as 0.34 when a simple power law relationship was used. A more sophisticated analysis of the resistivity measurements could potentially lead to a greater coefficient of determination. C1 NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. Univ Melbourne, Dep Civil & Environm Engn, Parkville, Vic 3010, Australia. RP Walker, JP (reprint author), NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. RI Walker, Jeffrey/D-2624-2009; Houser, Paul/J-9515-2013 OI Houser, Paul/0000-0002-2991-0441 NR 17 TC 14 Z9 14 U1 0 U2 4 PU SOIL SCI SOC AMER PI MADISON PA 677 SOUTH SEGOE ROAD, MADISON, WI 53711 USA SN 0361-5995 J9 SOIL SCI SOC AM J JI Soil Sci. Soc. Am. J. PD MAY-JUN PY 2002 VL 66 IS 3 BP 728 EP 734 PG 7 WC Soil Science SC Agriculture GA 546RU UT WOS:000175288300007 ER PT J AU Cid, C Hidalgo, MA Nieves-Chinchilla, T Sequeiros, J Vinas, AF AF Cid, C Hidalgo, MA Nieves-Chinchilla, T Sequeiros, J Vinas, AF TI Plasma and magnetic field inside magnetic clouds: A global study SO SOLAR PHYSICS LA English DT Article ID NONLINEAR EVOLUTION; FLUX ROPES; WIND; SPACECRAFT AB Data observed during spacecraft encounters with magnetic clouds have been extensively analyzed in the literature. Moreover, several models have been proposed for the magnetic topology of these events, and fitted to the observations. Although these interplanetary events present well-defined plasma features, none of those models have included a simultaneous analysis of magnetic field and plasma data. Using as a starting point a non-force-free model that we have developed previously, we present a global study of MCs that include both the magnetic field topology and the plasma pressure. In this paper we obtain the governing equations for both magnitudes inside a MC. The expressions deduced are fitted simultaneously to the measurements of plasma pressure and magnetic field vector. We perform an analysis of magnetic field and plasma WIND observations within several MCs from 1995 to 1998. The analysis is confined to four of these events that have high-quality data. Only in one fitting procedure we obtain the orientation of the magnetic cloud relative to the ecliptic plane and the current density of the plasma inside the cloud. We find that the equations proposed reproduce the experimental data quite well. C1 Univ Alcala de Henares, Dept Fis, Madrid, Spain. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Cid, C (reprint author), Univ Alcala de Henares, Dept Fis, Madrid, Spain. RI Nieves-Chinchilla, Teresa/F-3482-2016; Hidalgo, Miguel/L-5826-2014; OI Nieves-Chinchilla, Teresa/0000-0003-0565-4890; Hidalgo, Miguel/0000-0003-1617-2037; CID, CONSUELO/0000-0002-2863-3745 NR 24 TC 38 Z9 38 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD MAY PY 2002 VL 207 IS 1 BP 187 EP 198 DI 10.1023/A:1015542108356 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 554XZ UT WOS:000175763600015 ER PT J AU So, RMC Vimala, P Jin, LH Zhao, CY Gatski, TB AF So, RMC Vimala, P Jin, LH Zhao, CY Gatski, TB TI Accounting for buoyancy effects in the explicit algebraic stress model: Homogeneous turbulent shear flows SO THEORETICAL AND COMPUTATIONAL FLUID DYNAMICS LA English DT Article ID DISSIPATION RATE; REYNOLDS-STRESS; ANISOTROPIES AB Most explicit algebraic stress models are formulated for turbulent shear flows without accounting for external body force effects, such as the buoyant force. These models yield fairly good predictions of the turbulence field generated by mean shear. As for thermal turbulence generated by the buoyant force, the models fail to give satisfactory results. The reason is that the models do not explicitly account for buoyancy effects, which interact with the mean shear to enhance or suppress turbulent mixing. Since applicable. coupled differential equations have been developed describing these thermal turbulent fields, it is possible to develop corresponding explicit algebraic stress models using tensor representation theory. While the procedure to be followed has been employed previously, unique challenges arise in extending the procedure for developing the algebraic representations to turbulent buoyant flows. In this paper the development of an explicit algebraic stress model (EASM) is confined to the homogeneous buoyant shear flow case to illustrate the methodology needed to develop the proper polynomial representations, The derivation is based on the implicit formulation of the Reynolds stress anisotropy at buoyant equilibrium, A five-term representation is found to be necessary to account properly for the effect of the thermal field. Thus derived, external buoyancy effects are represented in the scalar coefficients of the basis tensors, and structural buoyancy effects are accounted for in additional terms in the stress anisotropy tensor. These terms will not vanish even in the absence of mean shear. The performance of the new EASM, together with a two-equation (2-Eq) model, the non-buoyant EASM of Gatski and Speziale (1993) and a full second-order model, is assessed against direct numerical simulations of homogeneous, buoyant shear flows at two different Richardson numbers representing weak and strong buoyancy effects, The calculations show that this five-term representation yields better results than the 2-Eq model and the EASM of Gatski and Speziale where buoyancy effects are not explicitly accounted for. C1 Hong Kong Polytech Univ, Dept Mech Engn, Kowloon, Hong Kong, Peoples R China. NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Hampton, VA 23681 USA. RP So, RMC (reprint author), Hong Kong Polytech Univ, Dept Mech Engn, Kowloon, Hong Kong, Peoples R China. RI So, Ronald/B-6698-2008 NR 28 TC 10 Z9 11 U1 1 U2 1 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0935-4964 J9 THEOR COMP FLUID DYN JI Theor. Comput. Fluid Dyn. PD MAY PY 2002 VL 15 IS 5 BP 283 EP 302 DI 10.1007/s00162-002-0057-x PG 20 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 562WV UT WOS:000176222700002 ER PT J AU Bauschlicher, CW Gutsev, GL AF Bauschlicher, CW Gutsev, GL TI MnO+: a challenge for density functional theory methods SO THEORETICAL CHEMISTRY ACCOUNTS LA English DT Article DE density functional theory; complete-active-space self-consistent-field; multireference configuration interaction; MnO+ ID GAUSSIAN-BASIS SETS; MOLECULAR CALCULATIONS; EXACT EXCHANGE; ROW ATOMS; ENERGIES; APPROXIMATION; SPECTRA; CATIONS; IONS AB The (5)Sigma(+) and (5)Pi states of MnO+ are studied using density functional theory (DFT) and the complete-active-space self-consistent-field (CASSCF)/multireference configuration interaction (MRCI) and CASSCF/average coupled pair functional (ACPF) levels of theory. All the DFT methods give a reasonable description of the (5)Sigma(+) state, but only the hybrid functionals give (5)Pi spectroscopic constants that agree with those obtained using the MRCI and ACPF approaches. The origin of the difference between the pure and hybrid functionals is discussed. C1 NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. Univ Virginia, Dept Chem, Charlottesville, VA 22901 USA. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, Space Technol Div, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 29 TC 8 Z9 8 U1 0 U2 2 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 1432-881X J9 THEOR CHEM ACC JI Theor. Chem. Acc. PD MAY PY 2002 VL 107 IS 5 BP 309 EP 312 DI 10.1007/s00214-002-0334-1 PG 4 WC Chemistry, Physical SC Chemistry GA 564UJ UT WOS:000176331700007 ER PT J AU Marchetti, M Jones, WR Street, KW Wheeler, D Dixon, D Jansen, MJ Kimura, H AF Marchetti, M Jones, WR Street, KW Wheeler, D Dixon, D Jansen, MJ Kimura, H TI Tribological performance of some Pennzane (R)-based greases for vacuum applications SO TRIBOLOGY LETTERS LA English DT Article DE grease lubrication; space mechanisms; accelerated tests AB Commercial greases for space applications usually fulfill the requirements imposed by the severe conditions of use (load, ultrahigh vacuum, speed, etc.). The main requirement is their ability to create an elastohydrodynamic lubrication film, boundary film, or both, for the speed, load, and temperature conditions under which the mechanisms will operate. Three greases, all based on a multiply alkylated cyclopentane (Pennzane(R)) base oil, were studied. The thickeners were an n-octadecylterephthalamate soap, a lithium soap, and a urea derivative. A four-ball tribometer and a spiral-orbit tribometer were employed to evaluate the greases under ultrahigh vacuum. The results indicated that all three greases yielded very low wear rates and extended lifetimes. In addition, routine physical property data are reported for each grease. C1 NASA, Tribol & Surface Sci Branch, Glenn Res Ctr, Cleveland, OH 44135 USA. SEST Inc, Middleburg Hts, OH 44130 USA. Kyodo Yushi Co Ltd, Fujisawa, Kanagawa 2518588, Japan. RP Marchetti, M (reprint author), NASA, Tribol & Surface Sci Branch, Glenn Res Ctr, 21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 22 TC 15 Z9 15 U1 0 U2 3 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 1023-8883 J9 TRIBOL LETT JI Tribol. Lett. PD MAY PY 2002 VL 12 IS 4 BP 209 EP 216 DI 10.1023/A:1015486926801 PG 8 WC Engineering, Chemical; Engineering, Mechanical SC Engineering GA 551ZH UT WOS:000175593500003 ER PT J AU Hays, CC Glade, SC AF Hays, CC Glade, SC TI Thermophysical properties and glass forming ability in the alloy series (Ti100-xZrx)(45)(Ni14.5Cu85.5)(55) SO APPLIED PHYSICS LETTERS LA English DT Article AB Measurements of the structural and thermophysical properties of bulk metallic glass forming alloys in the series (Ti100-xZrx)(45)(Ni14.5Cu85.5)(55) (at. %) are presented for 25less than or equal toxless than or equal to75. The bulk glass forming ability was found to terminate abruptly for x>50 due to the nucleation of NiTiZr and Zr2Cu symmetry phases with increasing x. Calorimetric measurements reveal that crystallization is facilitated by a decomposition process in the under-cooled liquid. (C) 2002 American Institute of Physics. C1 CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. RP Hays, CC (reprint author), CALTECH, Jet Prop Lab, Low Temp Sci & Engn Grp 79 24, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 8 TC 6 Z9 7 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD APR 29 PY 2002 VL 80 IS 17 BP 3096 EP 3098 DI 10.1063/1.1475368 PG 3 WC Physics, Applied SC Physics GA 544EB UT WOS:000175144300022 ER PT J AU Tubiello, FN Rosenzweig, C Goldberg, RA Jagtap, S Jones, JW AF Tubiello, FN Rosenzweig, C Goldberg, RA Jagtap, S Jones, JW TI Effects of climate change on US crop production: simulation results using two different GCM scenarios. Part I: Wheat, potato, maize, and citrus SO CLIMATE RESEARCH LA English DT Article DE climate change; agriculture; elevated CO2; US National Assessment; adaptation ID CARBON-DIOXIDE; CO2 ENRICHMENT; RESPONSES; IMPACTS; GROWTH; MINK AB We projected US agricultural production in 2030 and 2090 at 45 representative sites, using 2 scenarios of climate change, developed with the Hadley Centre Model and the Canadian Centre Climate Model, and the DSSAT (Decision Support Systems for Agro-technology Transfer) dynamic crop-growth models. These simulation results have previously been aggregated nationally with the aid of economic models to show an increase in overall US agricultural output under climate change. In this work, we analyzed the regional distribution of the simulated yields, showing that positive results largely depend on the precipitation increases projected by the climate scenarios. In contrast, in some important rainfed production areas where precipitation was projected to decrease, such as the Kansas and Oklahoma Bread Basket regions under the Canadian Centre Climate Model scenario, climate change resulted in significant reductions of grain yield (-30 to -40%), accompanied by increased year-to-year variability. We also discussed the response to additional factors affecting the simulated US crop production under climate change, such as higher temperature and elevated CO2. C1 Columbia Univ, New York, NY 10025 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Univ Florida, Coll Agr & Life Sci, Gainesville, FL 32611 USA. RP Tubiello, FN (reprint author), Columbia Univ, Armstrong Hall,2880 Broadway, New York, NY 10025 USA. NR 19 TC 106 Z9 111 U1 1 U2 36 PU INTER-RESEARCH PI OLDENDORF LUHE PA NORDBUNTE 23, D-21385 OLDENDORF LUHE, GERMANY SN 0936-577X J9 CLIMATE RES JI Clim. Res. PD APR 26 PY 2002 VL 20 IS 3 BP 259 EP 270 DI 10.3354/cr020259 PG 12 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA 563CD UT WOS:000176235900008 ER PT J AU Del Genio, AD AF Del Genio, AD TI Atmospheric science - The dust settles on water vapor feedback SO SCIENCE LA English DT Editorial Material C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Del Genio, AD (reprint author), NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RI Del Genio, Anthony/D-4663-2012 OI Del Genio, Anthony/0000-0001-7450-1359 NR 9 TC 9 Z9 10 U1 0 U2 5 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD APR 26 PY 2002 VL 296 IS 5568 BP 665 EP 666 DI 10.1126/science.1071400 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 546PD UT WOS:000175281700031 PM 11976431 ER PT J AU Rind, D AF Rind, D TI Climatology - The sun's role in climate variations SO SCIENCE LA English DT Review ID NEOPROTEROZOIC SNOWBALL EARTH; GENERAL-CIRCULATION MODEL; 11-YEAR SOLAR-CYCLE; NORTHERN-HEMISPHERE; COSMIC-RAYS; GLOBAL CLIMATE; VARIABILITY; IRRADIANCE; TEMPERATURE; ATMOSPHERE AB Is the Sun the controller of climate changes, only the instigator of changes that are mostly forced by the system feedbacks, or simply a convenient scapegoat for climate variations lacking any other obvious cause? This question is addressed for suggested solar forcing mechanisms operating on time scales from billions of years to decades. Each mechanism fails to generate the expected climate response in important respects, although some relations are found. The magnitude of the system feedbacks or variability appears as large or larger than that of the solar forcing, making the Sun's true role ambiguous. As the Sun provides an explicit external forcing, a better understanding of its cause and effect in climate change could help us evaluate the importance of other climate forcings (such as past and future greenhouse gas changes). C1 Columbia Univ, NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Rind, D (reprint author), Columbia Univ, NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 64 TC 165 Z9 194 U1 6 U2 44 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD APR 26 PY 2002 VL 296 IS 5568 BP 673 EP 677 DI 10.1126/science.1069562 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 546PD UT WOS:000175281700036 PM 11976436 ER PT J AU Lewis, RM Torczon, V AF Lewis, RM Torczon, V TI A globally convergent augmented Lagrangian pattern search algorithm for optimization with general constraints and simple bounds SO SIAM JOURNAL ON OPTIMIZATION LA English DT Article DE augmented Lagrangian; constrained optimization; direct search; nonlinear programming; pattern search ID MINIMIZATION AB We give a pattern search method for nonlinearly constrained optimization that is an adaption of a bound constrained augmented Lagrangian method first proposed by Conn, Gould, and Toint [SIAM J. Numer. Anal., 28 ( 1991), pp. 545 572]. In the pattern search adaptation, we solve the bound constrained subproblem approximately using a pattern search method. The stopping criterion proposed by Conn, Gould, and Toint for the solution of the subproblem requires explicit knowledge of derivatives. Such information is presumed absent in pattern search methods; however, we show how we can replace this with a stopping criterion based on the pattern size in a way that preserves the convergence properties of the original algorithm. In this way we proceed by successive, inexact, bound constrained minimization without knowing exactly how inexact the minimization is. As far as we know, this is the first provably convergent direct search method for general nonlinear programming. C1 Coll William & Mary, Dept Math, Williamsburg, VA 23187 USA. Coll William & Mary, Dept Comp Sci, Williamsburg, VA 23187 USA. NASA, Inst Comp Applicat Sci & Engn, Langley Res Ctr, Hampton, VA 23681 USA. RP Lewis, RM (reprint author), Coll William & Mary, Dept Math, POB 8795, Williamsburg, VA 23187 USA. NR 29 TC 152 Z9 157 U1 3 U2 8 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 APR 26 PY 2002 VL 12 IS 4 BP 1075 EP 1089 AR PII S1052623498339727 DI 10.1137/S1052623498339727 PG 15 WC Mathematics, Applied SC Mathematics GA 555UA UT WOS:000175810600011 ER PT J AU Hwu, SU Loh, YC Johnson, LA Panneton, RJ AF Hwu, SU Loh, YC Johnson, LA Panneton, RJ TI Solar array electromagnetic scattering characteristics at S-band frequencies SO ELECTRONICS LETTERS LA English DT Article AB Solar panel blockage is a major concern to the space station S-band communication link assessment, Solar array electromagnetic scattering characteristics at S-band frequencies (2 2.3 GHz) are investigated. Both experimental and computational results indicate the solar array can he modelled as a conducting plate for S-band communication link signal strength predictions. C1 Lockheed Martin Space Operat, Adv Engn Div, Houston, TX 77258 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77258 USA. RP Hwu, SU (reprint author), Lockheed Martin Space Operat, Adv Engn Div, 2400 NASA Rd 1, Houston, TX 77258 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD SG1 2AY, ENGLAND SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD APR 25 PY 2002 VL 38 IS 9 BP 400 EP 402 DI 10.1049/el:20020299 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA 551AR UT WOS:000175537700005 ER PT J AU Tyler, D Barnes, JR Haberle, RM AF Tyler, D Barnes, JR Haberle, RM TI Simulation of surface meteorology at the Pathfinder and VL1 sites using a Mars mesoscale model SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article DE Mars; meteorology; boundary layer; modeling; climate ID ATMOSPHERIC BOUNDARY-LAYER; MARTIAN ATMOSPHERE; GENERAL-CIRCULATION; SLOPE WINDS; CLIMATE; LANDER AB [1] The Fifth-Generation Penn State/NCAR Mesoscale Model (MM5) has been adapted to study circulations in the Martian atmosphere. The NASA Ames Mars general circulation model (GCM) provides initial and boundary conditions. The meteorology of this Mars MM5 (the OSU MMM5) is compared with Pathfinder and Viking Lander 1 (VL1) data for late northern summer. The MMM5 uses an equator-crossing semiglobal polar stereographic mother domain, significantly reducing the boundary reflections inherent in Martian mesoscale simulations. Using two-way nests, simultaneous simulations of two regions are performed: (1) Chryse Planitia (Mars Pathfinder (MPF)/VL1) and (2) the central chasmas of Valles Marineris. Simulations are hydrostatic and dry. The MMM5 uses the same atmospheric radiation package as the GCM but a much enhanced near-surface vertical resolution and a different Planetary Boundary Layer (PBL) scheme. Model topography, thermal inertia, and surface albedo maps have all been developed using the most recent data from the Mars Global Surveyor (MGS) Mars Orbiter Laser Altimeter (MOLA) and Thermal Emission Spectrometer (TES) experiments. The diurnal cycles of surface air temperature, surface pressure, and surface wind all show improvement in comparison with the GCM. For certain regions the local surface pressure tidal amplitudes are strongly dependent on the resolution of the model and/or the topography; VL1 and MPF are in such a region. The diurnal cycles of wind are complex, and for many locations the near-surface winds are dominated by slope flows of multiple scales. Comparison with data indicates that resolving these slope flows is very important for simulating the diurnal wind cycle. At specific locations these slope flows dramatically influence the diurnal surface pressure cycle. C1 Oregon State Univ, Coll Ocean & Atmospher Sci, Corvallis, OR 97331 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Tyler, D (reprint author), Oregon State Univ, Coll Ocean & Atmospher Sci, Corvallis, OR 97331 USA. NR 27 TC 26 Z9 26 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 2002 VL 107 IS E4 AR 5018 DI 10.1029/2001JE001618 PG 21 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 609MB UT WOS:000178906500007 ER PT J AU Iraci, LT Essin, AM Golden, DM AF Iraci, LT Essin, AM Golden, DM TI Solubility of methanol in low-temperature aqueous sulfuric acid and implications for atmospheric particle composition SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID LOWER STRATOSPHERE; UPPER TROPOSPHERE; HETEROGENEOUS REACTIONS; AEROSOLS; FORMALDEHYDE; ACETONE; CHEMISTRY; SURFACES; FATE; HBR AB Using traditional Knudsen cell techniques, we find well-behaved Henry's law uptake of methanol in aqueous 45-70 wt % H2SO4 solutions at temperatures between 197 and 231 K. Solubility of methanol increases with decreasing temperature and increasing acidity, with an effective Henry's law coefficient ranging from 105 to 10(8) M atm(-1). Equilibrium uptake of methanol into sulfuric acid aerosol particles in the upper troposphere and lower stratosphere will not appreciably alter gas-phase concentrations of methanol. The observed room-temperature reaction between methanol and sulfuric acid is too slow to provide a sink for gaseous methanol at the temperatures of the upper troposphere and lower stratosphere. It is also too slow to produce sufficient quantities of soluble reaction products to explain the large amount of unidentified organic material seen in particles of the upper troposphere. C1 SRI Int, Mol Phys Lab, Menlo Pk, CA 94025 USA. Stanford Univ, Dept Mech Engn, Stanford, CA 94305 USA. RP Iraci, LT (reprint author), NASA, Ames Res Ctr, M-S 245-5, Moffett Field, CA 94035 USA. NR 43 TC 33 Z9 33 U1 2 U2 12 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 25 PY 2002 VL 106 IS 16 BP 4054 EP 4060 DI 10.1021/jp012332b PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 544PR UT WOS:000175169600010 ER PT J AU Salter, LM Chaban, GM AF Salter, LM Chaban, GM TI Theoretical study of gas phase tautomerization reactions for the ground and first excited electronic states of adenine SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID AB-INITIO; SPECTRA; 2-AMINOPURINE; ENERGY; SPECTROSCOPY; DYNAMICS AB Geometrical structures and energetic properties for different tautomers of adenine are calculated in this study, using multi-configurational wave functions. Both the ground and the lowest singlet excited-state potential energy surface are studied. Four tautomeric forms are considered, and their energetic order is found to be different on the ground and the excited state potential energy surfaces. Minimum energy reaction paths are obtained for hydrogen atom transfer (tautomerization) reactions in the ground and the lowest excited electronic state. It is found that the barrier heights and the shapes of the reaction paths are different for the ground and the excited electronic state, suggesting that the probability of such tautomerization reaction is higher on the excited state potential energy surface. This tautomerization process should become possible in the presence of water or other polar solvent molecules and may play an important role in the photochemistry of adenine. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Tougaloo Coll, Tougaloo, MS 39174 USA. Jackson State Univ, Dept Chem, Jackson, MS 39217 USA. Jackson State Univ, Computat Ctr Mol Struct & Interact, Jackson, MS 39217 USA. RP Chaban, GM (reprint author), NASA, Ames Res Ctr, Mail Stop T27B-1, Moffett Field, CA 94035 USA. NR 19 TC 42 Z9 43 U1 1 U2 7 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 25 PY 2002 VL 106 IS 16 BP 4251 EP 4256 DI 10.1021/jp014620d PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 544PR UT WOS:000175169600036 ER PT J AU Abel, P Bozzolo, G AF Abel, P Bozzolo, G TI Calculation of thermal expansion coefficients of pure elements and their alloys SO SCRIPTA MATERIALIA LA English DT Article DE thermal expansion; alloys; intermetallics; quantum approximate methods; nickel; aluminium; copper ID EQUATION; METALS; STATE AB A simple algorithm for computing the coefficient of thermal expansion of pure elements and their alloys, based on features of the binding energy curve, is introduced. The BFS method for alloys is used to determine the binding energy curves of intermetallic alloys and Ni-base superalloys. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Cleveland, OH 44142 USA. RP Bozzolo, G (reprint author), NASA, Glenn Res Ctr Lewis Field, Mail Stop 23-2, Cleveland, OH 44135 USA. NR 12 TC 16 Z9 16 U1 1 U2 10 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1359-6462 J9 SCRIPTA MATER JI Scr. Mater. PD APR 25 PY 2002 VL 46 IS 8 BP 557 EP 562 AR PII S1359-6462(01)01236-2 DI 10.1016/S1359-6462(01)01236-2 PG 6 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 560RN UT WOS:000176095200001 ER PT J AU Stevenson, TR Pellerano, FA Stahle, CM Aidala, K Schoelkopf, RJ AF Stevenson, TR Pellerano, FA Stahle, CM Aidala, K Schoelkopf, RJ TI Multiplexing of radio-frequency single-electron transistors SO APPLIED PHYSICS LETTERS LA English DT Article ID READOUT AB We present results on wavelength division multiplexing of radio-frequency single-electron transistors. We use a network of resonant impedance matching circuits to direct applied rf carrier waves to different transistors depending on carrier frequency. A two-channel demonstration of this concept using discrete components successfully reconstructed input signals with small levels of crosscoupling. A lithographic version of the rf circuits had measured parameters in agreement with electromagnetic modeling, with reduced crosscapacitance and inductance, and should allow 20-50 channels to be multiplexed. (C) 2002 American Institute of Physics. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. RP Stevenson, TR (reprint author), NASA, Goddard Space Flight Ctr, Codes 553 & 555, Greenbelt, MD 20771 USA. RI Schoelkopf, Robert/J-8178-2012 NR 12 TC 35 Z9 35 U1 1 U2 6 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD APR 22 PY 2002 VL 80 IS 16 BP 3012 EP 3014 DI 10.1063/1.1472472 PG 3 WC Physics, Applied SC Physics GA 542WQ UT WOS:000175068900065 ER PT J AU Banks, HT Beeler, SC Kepler, GM Tran, HT AF Banks, HT Beeler, SC Kepler, GM Tran, HT TI Reduced order modeling and control of thin film growth in an HPCVD reactor SO SIAM JOURNAL ON APPLIED MATHEMATICS LA English DT Article DE chemical vapor deposition; reduced order model; nonlinear feedback tracking control; nonlinear compensator; state-dependent Riccati equations ID CHEMICAL-VAPOR-DEPOSITION; P-POLARIZED REFLECTANCE; FEEDBACK-CONTROL; COMPENSATOR CONTROL; NONLINEAR-SYSTEMS; PENALTY; DESIGN; MOCVD AB This paper describes the development of a reduced order model-based feedback control methodology for regulation of the growth of thin films in a high-pressure chemical vapor deposition (HPCVD) reactor. Precise control of the film thickness and composition is highly desirable, making real-time control of the deposition process very important. The source vapor species transport is modeled by the standard gas dynamics partial differential equations, with species decomposition reactions, reduced down to a small number of ordinary differential equations through use of the proper orthogonal decomposition technique. This system is coupled with a reduced order model of the surface reactions involved in the source vapor decomposition and film growth on the substrate. Also modeled is the real-time observation technique used to obtain a partial measurement of the deposition process. The utilization of reduced order models greatly simplifies the mathematical formulation of the physical process so that it can be solved quickly enough to be used for real-time model-based feedback control. This control problem is fairly complicated, however, because the surface reactions render the model nonlinear. To deal with this we use a nonlinear feedback control method based on the state-dependent Riccati equation (SDRE). A second SDRE is contained in a state estimator which uses the nonlinear partial observations of the growth process to obtain an estimated state on which to base the feedback control. These nonlinear control techniques are implemented on the HPCVD model, and the results analyzed as to the effectiveness of the reduced order model and nonlinear control at tracking the desired film growth profile. C1 N Carolina State Univ, Dept Math, Ctr Res Sci Computat, Raleigh, NC 27695 USA. NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. Chinese Univ Hong Kong, Inst Math Sci, Sha Tin 100083, Hong Kong, Peoples R China. RP Banks, HT (reprint author), N Carolina State Univ, Dept Math, Ctr Res Sci Computat, Box 8205, Raleigh, NC 27695 USA. EM htbanks@eos.ncsu.edu; scbeeler@icase.edu; gmkepler@unity.ncsu.edu; tran@control.math.ncsu.edu NR 44 TC 27 Z9 27 U1 0 U2 3 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 0036-1399 EI 1095-712X J9 SIAM J APPL MATH JI SIAM J. Appl. Math. PD APR 22 PY 2002 VL 62 IS 4 BP 1251 EP 1280 AR PII S0036139901383280 PG 30 WC Mathematics, Applied SC Mathematics GA 548XR UT WOS:000175415600007 ER PT J AU Bautista, MA Gull, TR Ishibashi, K Hartman, H Davidson, K AF Bautista, MA Gull, TR Ishibashi, K Hartman, H Davidson, K TI Excitation of SrII lines in Eta Carinae SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE atomic data; atomic processes; line : formation; stars : abundances; stars : individual : Eta Carinae ID GASEOUS NEBULAE; II LINES; NI-II AB We study the nature of the peculiar [Sr II] and Sr II emission filament found in the ejecta of Eta Carinae. To this purpose we carry out ab initio calculations of radiative transition probabilities and electron impact excitation rate coefficients for Sr II. Then we build a multilevel model for the system which is used to investigate the physical condition of the filament and the nature of the observed allowed and forbidden Sr II optical emission. It is found that the observed spectrum is consistent with the lines being pumped by the continuum radiation field in a mostly neutral region with electron density near 10(7) cm(-3). Under these conditions, the observed emission can be explained without the need for a large Sr overabundance. C1 Inst Venezolano Invest Cient, Ctr Fis, Caracas 1020A, Venezuela. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Lund Univ, Dept Phys, Lund, Sweden. Univ Minnesota, Dept Astron, Minneapolis, MN 55455 USA. RP Bautista, MA (reprint author), Inst Venezolano Invest Cient, Ctr Fis, Apartado 21827, Caracas 1020A, Venezuela. RI Gull, Theodore/D-2753-2012; Hartman, Henrik/K-3113-2013 OI Gull, Theodore/0000-0002-6851-5380; NR 15 TC 19 Z9 19 U1 1 U2 1 PU BLACKWELL PUBLISHING LTD PI OXFORD PA 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD APR 21 PY 2002 VL 331 IS 4 BP 875 EP 879 DI 10.1046/j.1365-8711.2002.05250.x PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 546JJ UT WOS:000175270700009 ER PT J AU Lazendic, JS Whiteoak, JB Klamer, I Harbison, PD Kuiper, TBH AF Lazendic, JS Whiteoak, JB Klamer, I Harbison, PD Kuiper, TBH TI Accurate positions of H2O masers in the Large Magellanic Cloud SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE line : profiles; masers; HII regions; ISM : molecules; Magellanic Clouds ID STAR-FORMATION; 30 DORADUS; INFRARED OBSERVATIONS; METHANOL MASER; OH MASER; REGIONS; IMAGES AB Positions with subarcsecond accuracy have been measured for seven 22-GHz H2O masers associated with H II regions in the Large Magellanic Cloud (LMC); two of the masers are new detections. Initial position measurements were obtained with the 70-m antenna of the Canberra NASA Deep Space Network during a period of more than two years in which the antenna was used to monitor the maser emission. The positions were further improved using 22-GHz observations involving three antennas of the Australia Telescope Compact Array. The positions have been compared with those of 1.6-GHz continuum emission and other LMC masers (of OH and CH3OH). The H2O maser positions range from within 1 arcsec (270 mpc) of the centre of a compact H II component to beyond the boundary of significant continuum emission. Three of the four masers located near continuum peaks are close to OH masers. In two cases the positional agreement is better than 0.2 arcsec (53 mpc); in the third case the agreement is worse (0.9 arcsec) but the positions of the individual H2O features appear to be spread over more than 1 arcsec. The velocities of the OH masers are within the spread of the H2O velocities. The three H2O masers offset from continuum centres are located 3-7 arcsec from optical or infrared phenomena probably associated with very early stages of star formation; no other molecular masers are known in these directions. C1 Univ Sydney, Sch Phys A28, Sydney, NSW 2006, Australia. CSIRO, Australia Telescope Natl Facil, Epping, NSW 2121, Australia. BAE Syst Australia, Canberra Deep Space Commun Complex, Tidbinbilla, ACT, Australia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lazendic, JS (reprint author), Univ Sydney, Sch Phys A28, Sydney, NSW 2006, Australia. NR 22 TC 27 Z9 27 U1 0 U2 0 PU BLACKWELL PUBLISHING LTD PI OXFORD PA 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD APR 21 PY 2002 VL 331 IS 4 BP 969 EP 974 DI 10.1046/j.1365-8711.2002.05251.x PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 546JJ UT WOS:000175270700017 ER PT J AU Houde, M Bastien, P Dotson, JL Dowell, CD Hildebrand, RH Peng, RS Phillips, TG Vaillancourt, JE Yoshida, H AF Houde, M Bastien, P Dotson, JL Dowell, CD Hildebrand, RH Peng, RS Phillips, TG Vaillancourt, JE Yoshida, H TI On the measurement of the magnitude and orientation of the magnetic field in molecular clouds SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : clouds; ISM : individual (M17); ISM : magnetic fields; polarization; radio lines : ISM ID HELICAL FIELDS; ION SPECTRA; POLARIMETRY AB We demonstrate that the combination of Zeeman, polarimetry, and ion-to-neutral molecular line width ratio measurements permits the determination of the magnitude and orientation of the magnetic field in the weakly ionized parts of molecular clouds. Zeeman measurements provide the strength of the magnetic field along the line of sight, polarimetry measurements give the field orientation in the plane of the sky, and the ion-to-neutral molecular line width ratio determines the angle between the magnetic field and the line of sight. We apply the technique to the M17 star-forming region using a HERTZ 350 l m polarimetry map and HCO+-to-HCN molecular line width ratios to provide the first three-dimensional view of the magnetic field in M17. C1 Caltech Submillimeter Observ, Hilo, HI 96720 USA. Univ Montreal, Dept Phys, Montreal, PQ H3C 3J7, Canada. NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. CALTECH, Pasadena, CA 91125 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Chicago, Dept Phys, Chicago, IL 60637 USA. RP Houde, M (reprint author), Caltech Submillimeter Observ, 111 Nowelo St, Hilo, HI 96720 USA. NR 17 TC 35 Z9 36 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 2002 VL 569 IS 2 BP 803 EP 814 DI 10.1086/339356 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ND UT WOS:000174989900022 ER PT J AU Yorke, HW Sonnhalter, C AF Yorke, HW Sonnhalter, C TI On the formation of massive stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; hydrodynamics; radiative transfer; stars : formation; stars : mass loss ID RADIATIVE-TRANSFER THEORY; PROTOSTELLAR DISKS; MAIN-SEQUENCE; QUADRATURE PERTURBATIONS; MOLECULAR OUTFLOWS; INITIAL CONDITIONS; STELLAR EVOLUTION; DIFFUSION; GRAINS; CLOUD AB We calculate numerically the collapse of slowly rotating, nonmagnetic, massive molecular clumps of masses 30, 60, and 120 M, which conceivably could lead to the formation of massive stars. Because radiative acceleration on dust grains plays a critical role in the clumps dynamical evolution, we have improved the module for continuum radiation transfer in an existing two-dimensional ( axial symmetry assumed) radiation hydrodynamic code. In particular, rather than using gray dust opacities and gray radiation transfer, we calculate the dusts wavelength-dependent absorption and emission simultaneously with the radiation density at each wavelength and the equilibrium temperatures of three grain components: amorphous carbon particles, silicates, and dirty ice coated silicates. Because our simulations cannot spatially resolve the innermost regions of the molecular clump, however, we cannot distinguish between the formation of a dense central cluster or a single massive object. Furthermore, we cannot exclude significant mass loss from the central object(s) that may interact with the inflow into the central grid cell. Thus, with our basic assumption that all material in the innermost grid cell accretes onto a single object, we are able to provide only an upper limit to the mass of stars that could possibly be formed. We introduce a semianalytical scheme for augmenting existing evolutionary tracks of pre-main-sequence protostars by including the effects of accretion. By considering an open outermost boundary, an arbitrary amount of material could, in principal, be accreted onto this central star. However, for the three cases considered (30, 60, and 120 M-. originally within the computation grid), radiation acceleration limited the final masses to 31.6, 33.6, and 42.9 M-., respectively, for wavelength-dependent radiation transfer and to 19.1, 20.1, and 22.9 M-. for the corresponding simulations with gray radiation transfer. Our calculations demonstrate that massive stars can in principle be formed via accretion through a disk. The accretion rate onto the central source increases rapidly after one initial free-fall time and decreases monotonically afterward. By enhancing the nonisotropic character of the radiation field, the accretion disk reduces the effects of radiative acceleration in the radial direction a process we call the "flashlight effect. The flashlight effect is further amplified in our case by including the effects of frequency-dependent radiation transfer. We conclude with the warning that a careful treatment of radiation transfer is a mandatory requirement for realistic simulations of the formation of massive stars. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Inst Theoret Phys, Lehrstuhl Atsron, D-97074 Wurzburg, Germany. RP CALTECH, Jet Prop Lab, MS 169-506, Pasadena, CA 91109 USA. EM harold.yorke@jpl.nasa.gov NR 47 TC 297 Z9 298 U1 1 U2 4 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 2002 VL 569 IS 2 BP 846 EP 862 DI 10.1086/339264 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ND UT WOS:000174989900026 ER PT J AU Baykal, A Stark, MJ Swank, JH AF Baykal, A Stark, MJ Swank, JH TI X-ray spectra and pulse frequency changes in SAX J2103.5+4545 SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : individual (SAX J2103.5+4545); stars : neutron; X-rays : binaries; X-rays : stars ID MAGNETIC NEUTRON-STARS; LUMINOSITY DEPENDENCE; ACCRETION TORQUES; TIMING EXPLORER; BINARIES; EXO-2030+375; PERIOD; SPIN; ATMOSPHERES; PERFORMANCE AB The 1999 November outburst of the transient pulsar SAX J2103.5+4545 was monitored with the large area detectors of the Rossi X-Ray Timing Explorer until the pulsar faded after a year. The 358 s pulsar was spun up for 150 days, at which point the flux dropped quickly by a factor of 7, the frequency saturated, and, as the flux continued to decline, a weak spin-down began. The pulses remained strong during the decay and the spin-up/flux correlation can be fitted to the Ghosh and Lamb derivations for the spin-up caused by accretion from a thin, pressure-dominated disk, for a distance of approximate to3.2 kpc and a surface magnetic field of approximate to1.2 x 10(13) G. During the bright spin-up part of the outburst, the flux was subject to strong orbital modulation, peaking approximate to3 days after periastron of the eccentric 12.68 day orbit, while during the faint part, there was little orbital modulation. The X-ray spectra were typical of accreting pulsars, describable by a cutoff power law, with an emission line near the 6.4 keV of Kalpha fluorescence from cool iron. The equivalent width of this emission did not share the orbital modulation, but nearly doubled during the faint phase, despite little change in the column density. The outburst could have been caused by an episode of increased wind from a Be star, such that a small accretion disk was formed during each periastron passage. A change in the wind and disk structure apparently occurred after 5 months such that the accretion rate was no longer modulated or the diffusion time was longer. The distance estimate implies that the X-ray luminosity observed was between 1 x 10(36) and 6 x 10(34) ergs s(-1), with a small but definite correlation with the intrinsic power-law spectral index. C1 Middle E Tech Univ, Dept Phys, TR-06531 Ankara, Turkey. Lafayette Coll, Dept Phys, Easton, PA 18042 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Baykal, A (reprint author), Middle E Tech Univ, Dept Phys, Inonu Bulvar, TR-06531 Ankara, Turkey. RI Swank, Jean/F-2693-2012 NR 38 TC 40 Z9 41 U1 0 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 2002 VL 569 IS 2 BP 903 EP 910 DI 10.1086/339429 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ND UT WOS:000174989900031 ER PT J AU Bohm-Vitense, E Robinson, R Carpenter, K Mena-Werth, J AF Bohm-Vitense, E Robinson, R Carpenter, K Mena-Werth, J TI What is happening at spectral type F5 in Hyades F stars? SO ASTROPHYSICAL JOURNAL LA English DT Article DE open clusters and associations : individual (Hyades); stars : chromospheres; stars : coronae; stars : rotation ID YOUNG GALACTIC CLUSTERS; SOLAR-TYPE DWARFS; SPECTROGRAPH OBSERVATIONS; CHROMOSPHERIC ACTIVITY; MAGNETIC-STRUCTURE; COOL STARS; DYNAMO; CONVECTION; EVOLUTION; ROTATION AB Aiming at a better understanding of the mechanisms heating the chromospheres, transition regions, and coronae of cool stars, we study ultraviolet, low-resolution Hubble Space Telescope/Space Telescope Imaging Spectrograph spectra of Hyades main-sequence F stars. We study the B-V dependence(s) of the chromospheric and transition layer emission line fluxes and their dependences on rotational velocities. We find that the transition layer emission line fluxes and also those of strong chromospheric lines decrease steeply between B-V = 0.42 and 0.45, i.e., at spectral type F5, for which the rotational velocities also decrease steeply. The magnitude of the line-flux decrease increases for lines of ions with increasing degree of ionization. This shows that the line-flux decrease is not due to a change in the surface filling factor but rather due to a change of the relative importance of different heating mechanisms. For early F stars with B-V < 0.42 we find for the transition layer emission lines increasing fluxes for increasing v sin i, indicating magnetohydrodynamic heating. The v sin i dependence is strongest for the high-ionization lines. On the other hand, the low chromospheric lines show no dependence on v sin i, indicating acoustic shock heating for these layers. This also contributes to the heating of the transition layers. The Mg II and Ca II lines show decreasing fluxes for increasing v sin i, as long as v sin i is less than similar to 40 km s(-1). The coronal X-ray emission also decreases for increasing v sin i, except for v sin i larger than similar to 100 km s(-1). We have at present no explanation for this behavior. For late F stars the chromospheric lines show v sin i dependences similar to those observed for early F stars, again indicating acoustic heating for these layers. We were unable to determine the v sin i dependence of the transition layer lines because of too few single star targets. The decrease of emission line fluxes at the spectral type F5, with steeply decreasing v sin i, indicates, however, a decreasing contribution of magnetohydrodynamic heating for the late F stars. The X-ray emission for the late F stars increases for increasing v sin i, indicating magnetohydrodynamic heating for the coronae of the late F stars, different from the early F stars. C1 Univ Washington, Dept Astron, Seattle, WA 98195 USA. Catholic Univ Amer, Dept Phys, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, LASP, Greenbelt, MD 20771 USA. Univ Nebraska, Dept Phys, Kearney, NE 68849 USA. RP Univ Washington, Dept Astron, Seattle, WA 98195 USA. NR 42 TC 13 Z9 13 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 2002 VL 569 IS 2 BP 941 EP 963 PN 1 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ND UT WOS:000174989900033 ER PT J AU Biesecker, DA Myers, DC Thompson, BJ Hammer, DM Vourlidas, A AF Biesecker, DA Myers, DC Thompson, BJ Hammer, DM Vourlidas, A TI Solar phenomena associated with "EIT waves" SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : activity; Sun : coronal mass ejections (CMEs); Sun : flares; Sun : radio radiation; Sun : UV radiation; waves ID CORONAL MASS EJECTIONS; II RADIO-BURSTS; SOHO MISSION; TRANSIENT AB In an effort to understand what an "EIT wave" is and what its causes are, we have looked for correlations between the initiation of EIT waves and the occurrence of other solar phenomena. An EIT wave is a coronal disturbance, typically appearing as a diffuse brightening propagating across the Sun. A catalog of EIT waves, covering the period from 1997 March through 1998 June, was used in this study. For each EIT wave, the catalog gives the heliographic location and a rating for each wave, where the rating is determined by the reliability of the observations. Since EIT waves are transient, coronal phenomena, we have looked for correlations with other transient, coronal phenomena: X-ray flares, coronal mass ejections (CMEs), and metric type II radio bursts. An unambiguous correlation between EIT waves and CMEs has been found. The correlation of EIT waves with flares is significantly weaker, and EIT waves frequently are not accompanied by radio bursts. To search for trends in the data, proxies for each of these transient phenomena are examined. We also use the accumulated data to show the robustness of the catalog and to reveal biases that must be accounted for in this study. C1 NASA, Goddard Space Flight Ctr, Emergent Informat Technol Inc, Greenbelt, MD 20771 USA. George Mason Univ, EO Hulburt Ctr Space Res, Naval Res Lab, Washington, DC 20375 USA. RP Biesecker, DA (reprint author), NASA, Goddard Space Flight Ctr, Emergent Informat Technol Inc, Mail Code 682-3, Greenbelt, MD 20771 USA. RI Vourlidas, Angelos/C-8231-2009; Thompson, Barbara/C-9429-2012 OI Vourlidas, Angelos/0000-0002-8164-5948; NR 24 TC 175 Z9 184 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 2002 VL 569 IS 2 BP 1009 EP 1015 DI 10.1086/339402 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ND UT WOS:000174989900038 ER PT J AU Falconer, DA Moore, RL Gary, GA AF Falconer, DA Moore, RL Gary, GA TI Correlation of the coronal mass ejection productivity of solar active regions with measures of their global nonpotentiality from vector magnetograms: Baseline results SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : coronal mass ejections (CMEs); Sun : magnetic fields; Sun : X-rays, gamma rays ID MAGNETIC-FIELD; FLARES AB From conventional magnetograms and chromospheric and coronal images, it is known qualitatively that the fastest coronal mass ejections (CMEs) are magnetic explosions from sunspot active regions in which the magnetic field is globally strongly sheared and twisted from its minimum-energy potential configuration. In this paper, we present measurements from active region vector magnetograms that begin to quantify the dependence of the CME productivity of an active region on the global nonpotentiality of its magnetic field. From each of 17 magnetograms of 12 bipolar active regions, we obtain a measure of the size of the active region (the magnetic flux content, Phi) and three different measures of the global nonpotentiality (L-SS, the length of strong-shear, strong-field main neutral line; I-N, the net electric current arching from one polarity to the other; and alpha = muI(N)/Phi, a flux-normalized measure of the field twist). From these measurements and the observed CME productivity of the active regions, we find that: ( 1) All three measures of global nonpotentiality are statistically significantly correlated with each other and with the active region flux content. ( 2) All three measures of global nonpotentiality are significantly correlated with CME productivity. The flux content has some correlation with CME productivity, but at a less than statistically significant confidence level (less than 95%). (3) The net current is less strongly correlated with CME productivity than is, and the correlation of flux content with CME productivity is weaker still. If these differences in correlation strength, and a significant correlation of alpha with flux content, persist to larger samples of active regions, this would suggest that active region size does not affect CME productivity except through global nonpotentiality. ( 4) For each of the four global magnetic quantities, the correlation with CME productivity is stronger for a +/-2 day time window for the CME production than for windows half as wide or twice as wide. This plausibly results from most CME-productive active regions producing less than one CME per day, and from active region evolution often significantly changing the global nonpotentiality over the course of several days. These results establish that measures of active region global nonpotentiality from vector magnetograms ( such as L-SS, I-N, and alpha) should be useful for prediction of active region CMEs. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Falconer, DA (reprint author), Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. NR 29 TC 88 Z9 89 U1 1 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 2002 VL 569 IS 2 BP 1016 EP 1025 DI 10.1086/339161 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ND UT WOS:000174989900039 ER PT J AU Charnley, SB Rodgers, SD AF Charnley, SB Rodgers, SD TI The end of interstellar chemistry as the origin of nitrogen in comets and meteorites SO ASTROPHYSICAL JOURNAL LA English DT Article DE comets : general; ISM : abundances; ISM : molecules; meteors, meteoroids; molecular processes ID O1 HALE-BOPP; MOLECULAR CLOUDS; DEUTERIUM FRACTIONATION; ISOTOPE; AMMONIA; CORES; ABUNDANCE; DEPLETION; JUPITER; DISKS AB We describe a mechanism for enhanced nitrogen isotope fractionation in dense molecular gas where most of the molecules containing carbon and oxygen have condensed on grains but where N(2) remains in the gas. The lack of hydroxl molecules prevents the recycling of N atoms into N(2), and the nitrogen eventually becomes atomic. Ammonia is formed efficiently under these conditions and rapidly accretes as ice. We find that a significant fraction of the total nitrogen is ultimately present as solid NH(3). This interstellar ammonia is enhanced in (15)N with (15)NH(3)/(14)NH(3) almost 80% higher than the cosmic (15)N/(14)N ratio. It is possible that a large part of the nitrogen available to the early solar system was highly fractionated ammonia ice and hence that the (15)N enhancements of primitive solar system material and the depletion of N(2) in comets are concomitant. Other implications of this theory for observations of dense molecular material and the nitrogen inventory available to the protosolar nebula are briefly discussed. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Charnley, SB (reprint author), NASA, Ames Res Ctr, Div Space Sci, MS 245-3, Moffett Field, CA 94035 USA. RI Charnley, Steven/C-9538-2012 NR 48 TC 97 Z9 97 U1 2 U2 6 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 2002 VL 569 IS 2 BP L133 EP L137 DI 10.1086/340484 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541NU UT WOS:000174991300017 ER PT J AU Bosilovich, MG AF Bosilovich, MG TI On the use and validation of mosaic heterogeneity in atmospheric numerical models SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID 1987 FIFE DATA; LAND SURFACES; REANALYSIS; BOUNDARY AB [1] The mosaic land modeling approach allows for the representation of multiple surface types in a single atmospheric general circulation model grid box. Each surface type, collectively called "tiles'' correspond to different sets of surface characteristics (e.g. for grass, crop or forest). Typically, the tile space data is averaged to grid space by weighting the tiles with their fractional cover. While grid space data is routinely evaluated, little attention has been given to the tile space data. The present paper explores uses of the tile space surface data in validation with station observations. The results indicate the limitations that the mosaic heterogeneity parameterization has in reproducing variations observed between stations at the Atmospheric Radiation Measurement Southern Great Plains field site. C1 NASA, Data Assimilat Off, Greenbelt, MD 20771 USA. RP Bosilovich, MG (reprint author), NASA, Data Assimilat Off, GSFC Code 910-3, Greenbelt, MD 20771 USA. RI Bosilovich, Michael/F-8175-2012 NR 8 TC 2 Z9 3 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 15 PY 2002 VL 29 IS 8 AR 1174 DI 10.1029/2001GL013925 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DF UT WOS:000178886800113 ER PT J AU Doake, CSM Corr, HFJ Nicholls, KW Gaffikin, A Jenkins, A Bertiger, WI King, MA AF Doake, CSM Corr, HFJ Nicholls, KW Gaffikin, A Jenkins, A Bertiger, WI King, MA TI Tide-induced lateral movement of Brunt Ice Shelf, Antarctica SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MODEL; FILCHNER AB [1] Accurate position data show that Brunt Ice Shelf has an irregular three-dimensional motion driven by the ocean tide. A 30-day GPS record from Halley station shows not only the expected vertical tidal displacement, but also a significant variation in horizontal velocity. The maximum forward velocity occurs about four hours before the maximum tidal height, a phase relationship that suggests ocean currents may be responsible. However, values of ice/ water friction coefficients needed to make this explanation plausible appear to be too high to be physically reasonable. Alternative explanations invoke interactions between the ice shelf and a grounded area at the ice front. Our findings suggest that significant errors might result if these motions are ignored when interpreting 'double difference' satellite SAR interferograms, where the common assumption is that the horizontal velocity of an ice shelf has no tidal dependence. C1 British Antarctic Survey, NERC, Cambridge CB3 0ET, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Newcastle Upon Tyne, Dept Geomat, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England. Univ Tasmania, Ctr Spatial Informat Sci, Hobart, Tas, Australia. RP Doake, CSM (reprint author), British Antarctic Survey, NERC, Madingley Rd, Cambridge CB3 0ET, England. RI Corr, Hugh/C-5398-2011; King, Matt/B-4622-2008 OI King, Matt/0000-0001-5611-9498 NR 17 TC 23 Z9 23 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 15 PY 2002 VL 29 IS 8 AR 1226 DI 10.1029/2001GL014606 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DF UT WOS:000178886800061 ER PT J AU Garmier, R Barriot, JP Konopliv, AS Yeomans, DK AF Garmier, R Barriot, JP Konopliv, AS Yeomans, DK TI Modeling of the Eros gravity field as an ellipsoidal harmonic expansion from the NEAR Doppler tracking data SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB [1] The gravity field for asteroid 433 Eros has been determined in terms of ellipsoidal harmonic functions by processing the Doppler tracking data of the NEAR spacecraft while it was in orbit about the asteroid. Using the same set of NEAR spacecraft Doppler tracking data, comparative descriptions of the Eros gravity field are provided for both the ellipsoidal and the traditional spherical harmonic models. It is shown that for elongated bodies, like the asteroid Eros, the ellipsoidal harmonics model permits a better representation of the gravity signature than does the spherical harmonics model. Eros has a nearly uniform density but there are negative gravity anomalies near the ends of Eros and positive gravity anomalies near the Psyche crater and the Himeros depression. C1 Observ Midi Pyrenees, GRGS, CNES, UMR 5562, F-31400 Toulouse, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Garmier, R (reprint author), Observ Midi Pyrenees, GRGS, CNES, UMR 5562, 14 Ave E Belin, F-31400 Toulouse, France. OI garmier, romain/0000-0002-3577-8117 NR 6 TC 14 Z9 14 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 15 PY 2002 VL 29 IS 8 AR 1231 DI 10.1029/2001GL013768 PG 3 WC Geosciences, Multidisciplinary SC Geology GA 609DF UT WOS:000178886800056 ER PT J AU Gopalswamy, N Yashiro, S Kaiser, ML Howard, RA Bougeret, JL AF Gopalswamy, N Yashiro, S Kaiser, ML Howard, RA Bougeret, JL TI Interplanetary radio emission due to interaction between two coronal mass ejections SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID WIND SPACECRAFT; SOLAR; ORIGIN; SHOCKS; MHZ AB [1] We report on the detection of a new class of nonthermal radio emission due to the interaction between two coronal mass ejections (CMEs). The radio emission was detected by the Radio and Plasma Wave Experiment (WAVES) on board the Wind satellite, while the CMEs were observed by the white-light coronagraphs of the Solar and Heliospheric Observatory (SOHO) mission. There was no type II radio burst (metric or interplanetary) preceding the nonthermal emission. The radio emission occurred at a distance beyond 10 R-s from the Sun, where the two CMEs came in contact. Using H-alpha and EUV images, we found that the two CMEs were ejected roughly along the same path. We argue that the nonthermal electrons responsible for the new type of radio emission were accelerated due to reconnection between the two CMEs and/or due to the formation of a new shock at the time of the collision between the two CMEs. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. USN, Res Lab, Solar Phys Branch, Washington, DC 20375 USA. Univ Paris, Dept Rech Spatiale, Meudon, France. RP Gopalswamy, N (reprint author), NASA, Goddard Space Flight Ctr, Bldg 26 Room G1,Mailstop 682-3, Greenbelt, MD 20771 USA. EM gopals@fugee.gsfc.nasa.gov RI Gopalswamy, Nat/D-3659-2012; OI Gopalswamy, Nat/0000-0001-5894-9954 NR 11 TC 28 Z9 28 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 15 PY 2002 VL 29 IS 8 AR 1265 DI 10.1029/2001GL013606 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DF UT WOS:000178886800022 ER PT J AU Huang, XL Farrara, J Leroy, SS Yung, YL Goody, RM AF Huang, XL Farrara, J Leroy, SS Yung, YL Goody, RM TI Cloud variability as revealed in outgoing infrared spectra: Comparing model to observation with spectral EOF analysis SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID GENERAL-CIRCULATION MODEL; FLUCTUATION DISSIPATION; DIURNAL-VARIATIONS; CLIMATE MODELS; OSCILLATION AB [1] Spectrally resolved outgoing radiance is a potentially powerful tool for testing climate models. To show how it can be used to evaluate the simulation of cloud variability, which is the principal uncertainty in current climate models, we apply spectral empirical orthogonal function (EOF) analysis to satellite radiance spectra and synthetic spectra derived from a general circulation model (GCM). We show that proper averaging over a correct timescale is necessary before applying spectral EOF analysis. This study focuses on the Central Pacific and the western Pacific Warm Pool. For both observation and GCM output, cloud variability is the dominant contributor to the first principal component that accounts for more than 95% of the total variance. However, the amplitude of the first principal component derived from the observations (2 similar to 3.4 W m(-2)) is 2 similar to 6 times greater than that of the GCM simulation. This suggests that cloud variability in the GCM is significantly smaller than that in the real atmosphere. C1 CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. Harvard Univ, Dept Chem & Biol Chem, Cambridge, MA 02138 USA. RP Huang, XL (reprint author), CALTECH, Div Geol & Planetary Sci, MC 150-21, Pasadena, CA 91125 USA. RI Huang, Xianglei/G-6127-2011 OI Huang, Xianglei/0000-0002-7129-614X NR 20 TC 12 Z9 12 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 15 PY 2002 VL 29 IS 8 AR 1270 DI 10.1029/2001GL014176 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DF UT WOS:000178886800017 ER PT J AU Hutterli, MA Bales, RC McConnell, JR Stewart, RW AF Hutterli, MA Bales, RC McConnell, JR Stewart, RW TI HCHO in Antarctic snow: Preservation in ice cores and air-snow exchange SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TO-FIRN TRANSFER; SOUTH-POLE; HYDROGEN-PEROXIDE; FORMALDEHYDE; TROPOSPHERE; H2O2; GREENLAND AB [1] Formaldehyde (HCHO) measurements in snow and shallow firn at three Antarctic sites gave concentrations around 6 ppbw in surface snow and 1 ppbw and lower below 1-2 m depth. The variable concentration patterns in shallow snow and firn result from temperature-dependent uptake and release of HCHO in response to annual temperature cycles. Deeper concentrations are constant with depth, and apparently reflect average atmospheric concentrations. This implies that after accounting for differences in temperature and accumulation, changes in ice-core HCHO concentrations with depth should linearly reflect changes in atmospheric HCHO over time. Modeling of observed HCHO profiles in the snow implies that degassing of HCHO from surface snow likely contributes a significant fraction of the HCHO found in the boundary layer in spring and summer at all three sites. Based on modeling of air-snow exchange and atmospheric photochemistry, summer HCHO levels are estimated to be on the order of 100-200 pptv. C1 Univ Bern, Inst Phys, CH-3012 Bern, Switzerland. Univ Arizona, Dept Hydrol & Water Resources, Tucson, AZ 85721 USA. Desert Res Inst, Reno, NV 89512 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Hutterli, MA (reprint author), Univ Bern, Inst Phys, CH-3012 Bern, Switzerland. NR 14 TC 33 Z9 33 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 APR 15 PY 2002 VL 29 IS 8 AR 1235 DI 10.1029/2001GL014256 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DF UT WOS:000178886800050 ER PT J AU Otterman, J Angell, J Atlas, R Bungato, D Schubert, S Starr, D Susskind, J Wu, MLC AF Otterman, J Angell, J Atlas, R Bungato, D Schubert, S Starr, D Susskind, J Wu, MLC TI Advection from the North Atlantic as the forcing of winter greenhouse effect over Europe SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article DE greenhouse effect in Europe; maritime-air advection; climate fluctuations; climatic feedback ID TEMPERATURE; SURFACE; REANALYSIS AB [1] In winter, large interannual fluctuations in the surface temperature are observed over central Europe. Comparing warm February 1990 with cold February 1996, a satellite-retrieved surface (skin) temperature difference of 9.8 K is observed for the region 50 - 60degreesN; 5 - 35degreesE. Previous studies show that advection from the North Atlantic constitutes the forcing to such fluctuations. The advection is quantified by Index I-na, the average of the ocean-surface wind speed over the eastern North Atlantic when the direction is from the southwest (when the wind is from another direction, it counts as a zero speed to the average). Average Ina for February 1990 was 10.6 m s(-1), but for February 1996 I-na was only 2.4 m s(-1). A large value of I-na means a strong southwesterly flow which brings warm and moist air into central Europe at low level, producing a steeper tropospheric lapse rate. Strong ascending motions at 700 mb were observed in association with warm and moist advection from the ocean in February 1990, producing clouds and precipitation. Total precipitable water and cloud-cover fraction have larger values in February 1990 than in 1996. The difference in the greenhouse effect between these two scenarios, this reduction in the heat loss to space, can be translated into a virtual radiative heating of 2.6 W m(-2) above the February 1990 surface/atmosphere system, which contributes to a warming of the surface on the order of 2.6 K. Accepting this estimate as quantitatively meaningful, we evaluate the direct effect, the rise in the surface temperature in Europe as a result of the maritime-air inflow, as 7.2 K (9.8 K-2.6 K). Thus, fractional reinforcement by the greenhouse effect is 2.6/7.2, or 36%, a substantial positive feedback. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. NOAA, Silver Spring, MD USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Sci Applicat Int Corp, Beltsville, MD USA. RP Otterman, J (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 910-3, Greenbelt, MD 20771 USA. RI Atlas, Robert/A-5963-2011 OI Atlas, Robert/0000-0002-0706-3560 NR 17 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 15 PY 2002 VL 29 IS 8 AR 1241 DI 10.1029/2001GL014187 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DF UT WOS:000178886800036 ER PT J AU Thulasiraman, S O'Neill, NT Royer, A Holben, BN Westphal, DL McArthur, LJB AF Thulasiraman, S O'Neill, NT Royer, A Holben, BN Westphal, DL McArthur, LJB TI Sunphotometric observations of the 2001 Asian dust storm over Canada and the US SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID APRIL 1998; AEROSOL; AERONET AB [1] Sunphotometry, supported by TOMS imagery and the NRL-NAAPS global aerosol model, was used to monitor the 2001 springtime Asian dust plume across Canada and the U. S. Comparative analysis between these data sets indicated that the dust plume was remarkable in its extent and persistence and that its evolution could be inferred at western, mid-western and eastern sunphotometer stations for a period of about a week. The dust influence on sunphotmeter monthly statistics is shown to be weak, but systematic. C1 Univ Sherbrooke, CARTEL, Sherbrooke, PQ J1K 2R1, Canada. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USN, Res Lab, Monterey, CA USA. Meteorol Serv Canada, Downsview, ON, Canada. RP Thulasiraman, S (reprint author), Univ Sherbrooke, CARTEL, Sherbrooke, PQ J1K 2R1, Canada. NR 10 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 APR 15 PY 2002 VL 29 IS 8 AR 1255 DI 10.1029/2001GL014188 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DF UT WOS:000178886800031 ER PT J AU Wickert, J Beyerle, G Hajj, GA Schwieger, V Reigber, C AF Wickert, J Beyerle, G Hajj, GA Schwieger, V Reigber, C TI GPS radio occultation with CHAMP: Atmospheric profiling utilizing the space-based single difference technique SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INVERSION; SYSTEM AB [1] The GPS (Global Positioning System) radio occultation experiment onboard the German CHAMP (CHAllenging Minisatellite Payload) satellite was successfully started in February 2001. By the end of July 2001 more than 11,000 globally distributed vertical profiles of atmospheric temperature were derived. Operational data processing is based on the double difference method to correct for satellite clock errors. This technique requires a continuous data stream from a global network of GPS ground stations. Termination of the GPS Selective Availability mode on May 2, 2000 reduced the GPS clock errors by orders of magnitude, thereby rendering space-based single differencing feasible. First results using this single difference technique without direct use of GPS ground station data are presented. The comparison of two data sets consisting of 436 occultations, one processed with space-based single differencing, the other with classical double differencing, yields no discernible temperature bias below 30 km altitude, a standard deviation of <0.6 K below 20 km and <1.2 K below 30 km. The comparison of both data sets with corresponding meteorological analyses shows nearly identical results with differences in mean and standard deviation of <0.15 K up to 30 km. C1 Geoforschungszentrum Potsdam, Div 1, D-14473 Potsdam, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wickert, J (reprint author), Geoforschungszentrum Potsdam, Div 1, D-14473 Potsdam, Germany. RI Wickert, Jens/A-7257-2013 NR 23 TC 27 Z9 27 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 15 PY 2002 VL 29 IS 8 AR 1187 DI 10.1029/2001GL013982 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DF UT WOS:000178886800100 ER PT J AU Wilson, C Adamec, D AF Wilson, C Adamec, D TI A global view of bio-physical coupling from SeaWiFS and TOPEX satellite data, 1997-2001 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SEA-SURFACE HEIGHT; OCEAN COLOR; ATLANTIC-OCEAN; ROSSBY WAVES; PACIFIC; WIND; TRICHODESMIUM; CHLOROPHYLL; DISPERSAL; CYCLE AB [1] Vertical fluxes of nutrient-rich water from below the nutricline to the ocean surface can be a limiting factor affecting surface chlorophyll, and the depth of the nutricline plays an important role in the regulation of surface productivity. Because subsurface nutrient data is less available than physical oceanographic data, satellite chlorophyll (SC) data has been compared to satellite sea-level anomalies (SLA), because SLA largely reflects changes in the thermocline depth, and the thermocline and nutricline are often colocated. Here global correlations between 46 months of TOPEX SLA and SeaWiFS SC are examined. These two measurements are predominately negatively correlated as smaller SLA implies a shallower thermocline/nutricline, which will increase the surface nutrient flux and increase phytoplankton concentrations. However, there are large areas in all ocean basins where the correlations suggest that SC are affected by processes other than thermocline depth changes. C1 NASA, Goddard Space Flight Ctr, GEST Ctr, Greenbelt, MD 20711 USA. NASA, Goddard Space Flight Ctr, Oceans & Ice Branch, Greenbelt, MD 20711 USA. RP Wilson, C (reprint author), NASA, Goddard Space Flight Ctr, GEST Ctr, Code 971, Greenbelt, MD 20711 USA. EM cara_wilson@gsfc.nasa.gov RI Wilson, Cara/A-8816-2009 NR 28 TC 21 Z9 21 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 15 PY 2002 VL 29 IS 8 AR 1257 DI 10.1029/2001GL014063 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DF UT WOS:000178886800030 ER PT J AU Cosgrove, BA Barron, EJ Pollard, D AF Cosgrove, BA Barron, EJ Pollard, D TI A simple interactive vegetation model coupled to the GENESIS GCM SO GLOBAL AND PLANETARY CHANGE LA English DT Article DE simple interactive vegetation model; GENESIS GCM; climate-vegetation interaction ID GENERAL-CIRCULATION MODELS; GLOBAL CLIMATE MODELS; TERRESTRIAL BIOSPHERE MODEL; TRANSFER SCHEME LSX; ATMOSPHERIC CO2; CARBON-DIOXIDE; STOMATAL-RESISTANCE; NORTHERN AFRICA; FEEDBACKS; SIMULATIONS AB A growing number of research efforts have demonstrated the importance of climate-vegetation interaction in understanding climate sensitivity and climate change. In the study of Earth system history, vegetation is frequently specified or off-line vegetation calculations are produced using comprehensive biome models. However. these methods may fail to capture climate vegetation feedbacks, and specified vegetation in a climate model may introduce substantial error into the simulation. Simple interactive vegetation models designed for incorporation into climate model studies in Earth history have considerable potential to (a) capture climate feedbacks ignored in earlier studies, (b) improve our ability to validate model simulations, and (c) gain greater insights into the distribution and character of vegetation in Earth history. The Simple Interactive Vegetation Model (SIVM) is a highly simplified vegetation model designed for Earth system history study. This model is evaluated by (1) determining the extent to which the simplified vegetation alters the simulation of the present-day climate, (21) determining the extent to which SIVM produces a realistic present-day vegetation distribution given observed climate parameters, and (3) examining the performance of the coupled GENESIS-SIVM system when applied to the Miocene and Oxygen Isotope Stage 3 climates. The SIVM provides substantial improvement over specified vegetation assumptions in climate models and aids in the interpretation of past climates. (C) 2002 Elsevier Science B.V All rights reserved. C1 Penn State Univ, EMS Environm Inst, University Pk, PA 16802 USA. NASA, Goddard Space Flight Ctr, SAIC, GSC,Hydrol Sci Branch, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Data Assimilat Office, Greenbelt, MD 20771 USA. RP Barron, EJ (reprint author), Penn State Univ, EMS Environm Inst, 2217 Earth Engn Sci Bldg,Univ Pk, University Pk, PA 16802 USA. NR 76 TC 17 Z9 17 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD APR 15 PY 2002 VL 32 IS 2-3 BP 253 EP 278 AR PII S0921-8181(01)00153-9 DI 10.1016/S0921-8181(01)00153-9 PG 26 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA 558JB UT WOS:000175961600009 ER PT J AU Goorjian, PM Ning, CZ AF Goorjian, PM Ning, CZ TI Ultrafast beam self-switching by using coupled vertical-cavity surface-emitting lasers SO JOURNAL OF MODERN OPTICS LA English DT Article; Proceedings Paper CT 15th National Quanturn Electronics and Photonics Conference CY SEP 03-06, 2001 CL UNIV STRATHELYDE, GLASGOW, SCOTLAND HO UNIV STRATHELYDE ID TRANSVERSE-MODE DYNAMICS; SEMICONDUCTOR-LASERS; ARRAYS; SIMULATION AB Dynamic beam switching of vertical-cavity surface-emitting lasers (VCSELs) has important applications for switching and routeing in optical interconnect networks. VCSEL arrays of various kinds have been quite extensively researched for tailoring and engineering near- and far-field patterns. In this paper, a new method of directional beam switching is proposed that uses two coupled VCSELs. When two VCSELs are coupled by a small separation and biased at the same steady current near threshold, then the resulting light output is dynamic at an extremely high frequency. The model equations are based on an approximation to the semiconductor Maxwell-Bloch equations. The simulations are for coupled VCSELs operating at 980 nm with circular current apertures of 5.6 mum diameter. Figures of the results will show far-field beam intensity patterns during a cycle of oscillation. The simulation results show directional switching at a speed of about 40 GHz and between directions about 88 apart. Results of addition simulations are also presented. Simulations that use two square VCSELs show that the frequency of oscillation increases to 50 GHz and that the far-field pattern remains similar. Finally, for four round VCSELs in a square pattern, two far-field circularly shaped beams moved left and right at a frequency of 50 GHz. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Goorjian, PM (reprint author), NASA, Ames Res Ctr, MS 202A-1, Moffett Field, CA 94035 USA. RI Ning, C. Z./D-4699-2009 OI Ning, C. Z./0000-0003-4583-8889 NR 8 TC 1 Z9 1 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 0950-0340 J9 J MOD OPTIC JI J. Mod. Opt. PD APR 15 PY 2002 VL 49 IS 5-6 BP 707 EP 718 DI 10.1080/09500340110111725 PG 12 WC Optics SC Optics GA 546LW UT WOS:000175276400002 ER PT J AU Dubovitsky, S Lay, OP Seidel, DJ AF Dubovitsky, S Lay, OP Seidel, DJ TI Elimination of heterodyne interferometer nonlinearity by carrier phase modulation SO OPTICS LETTERS LA English DT Article AB Accuracy in measuring displacement in optical interferometers is limited by cyclic errors introduced by various leakage paths within the system. Existing techniques to reduce this nonlinearity do not work when there is large optical loss in the target path, such as for long-range measurements. We describe a new approach to reducing nonlinearity that overcomes these limitations. Based on phase modulation of the laser light, and requiring minimal additional components, experiments have demonstrated rejection of the effects of leakage in the presence of large optical loss. (C) 2002 Optical Society of America. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Dubovitsky, S (reprint author), CALTECH, Jet Prop Lab, M-S 301-451,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 7 Z9 7 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD APR 15 PY 2002 VL 27 IS 8 BP 619 EP 621 DI 10.1364/OL.27.000619 PG 3 WC Optics SC Optics GA 543RY UT WOS:000175116000019 PM 18007881 ER PT J AU Andriotis, AN Menon, M Srivastava, D Chernozatonskii, L AF Andriotis, AN Menon, M Srivastava, D Chernozatonskii, L TI Transport properties of single-wall carbon nanotube Y junctions SO PHYSICAL REVIEW B LA English DT Article ID BINDING MOLECULAR-DYNAMICS; BRANCH SWITCH; ELECTRICAL-CONDUCTION; ELECTRONIC-PROPERTIES; COHERENT TRANSPORT; FORMALISM; DEVICES; SYSTEMS; ATOMS; RECTIFICATION AB Quantum conductivity of a wide class of carbon nanotube Y junctions is calculated using an efficient Green's function embedding scheme. Our results indicate that rectification and switching properties of these junctions depend strongly on the symmetry and to a lesser degree on chirality. We find that a zig-zag tube forming the stem of a symmetric Y junction is sufficient to cause perfect rectification across the junction, otherwise the I-V characteristics remain asymmetric with some leakage current for positive bias voltages. For asymmetric Y junction, on the other hand, we find that no rectification at all is possible. We invoke a model calculation involving Y branching in molecules as well as in nanotubes to explain the dependence of rectification on the nature of the geometry at the branching. C1 Fdn Res & Technol Hellas, Inst Elect Struct & Laser, Iraklion 71110, Crete, Greece. Univ Kentucky, Dept Phys & Astron, Lexington, KY 40506 USA. Univ Kentucky, Ctr Computat Sci, Lexington, KY 40506 USA. NASA, Ames Res Ctr, CSC, Moffett Field, CA 94035 USA. Russian Acad Sci, Inst Biochem Phys, Moscow 117977, Russia. RP Andriotis, AN (reprint author), Fdn Res & Technol Hellas, Inst Elect Struct & Laser, POB 1527, Iraklion 71110, Crete, Greece. RI Andriotis, Antonios/A-2848-2014 NR 62 TC 88 Z9 88 U1 1 U2 14 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 J9 PHYS REV B JI Phys. Rev. B PD APR 15 PY 2002 VL 65 IS 16 AR 165416 DI 10.1103/PhysRevB.65.165416 PG 13 WC Physics, Condensed Matter SC Physics GA 547GQ UT WOS:000175325000119 ER PT J AU Anderson, JD Laing, PA Lau, EL Liu, AS Nieto, MM Turyshev, SG AF Anderson, JD Laing, PA Lau, EL Liu, AS Nieto, MM Turyshev, SG TI Study of the anomalous acceleration of Pioneer 10 and 11 SO PHYSICAL REVIEW D LA English DT Review ID GALACTIC ROTATION CURVES; LONG-RANGE ACCELERATION; NON-NEWTONIAN GRAVITY; SPACE-TIME FRAME; SOLAR-SYSTEM; KUIPER-BELT; ULYSSES DATA; GRAVITATIONAL-RADIATION; PROSAIC EXPLANATION; DISTANT SPACECRAFT AB Our previous analyses of radio Doppler and ranging data from distant spacecraft in the solar system indicated that an apparent anomalous acceleration is acting on Pioneer 10 and 11, with a magnitude a(P)similar to8x10(-8) cm/s(2), directed towards the Sun. Much effort has been expended looking for possible systematic origins of the residuals, but none has been found. A detailed investigation of effects both external to and internal to the spacecraft, as well as those due to modeling and computational techniques, is provided. We also discuss the methods, theoretical models, and experimental techniques used to detect and study small forces acting on interplanetary spacecraft. These include the methods of radio Doppler data collection, data editing, and data reduction. There is now further data for the Pioneer 10 orbit determination. The extended Pioneer 10 data set spans 3 January 1987 to 22 July 1998. (For Pioneer 11 the shorter span goes from 5 January 1987 to the time of loss of coherent data on 1 October 1990.) With these data sets and more detailed studies of all the systematics, we now give a result of a(P)=(8.74+/-1.33)x10(-8) cm/s(2). (Annual-diurnal variations on top of a(P), that leave a(P) unchanged, are also reported and discussed.) C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Aerosp Corp, El Segundo, CA 90245 USA. Astrodynam Sci, Los Angeles, CA 90039 USA. Los Alamos Natl Lab, Div Theoret, Los Alamos, NM 87545 USA. RP Anderson, JD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 149 TC 334 Z9 336 U1 4 U2 6 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD APR 15 PY 2002 VL 65 IS 8 AR 082004 DI 10.1103/PhysRevD.65.082004 PN A PG 50 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 544FE UT WOS:000175146900007 ER PT J AU Chung, DJH Kolb, EW Riotto, A AF Chung, DJH Kolb, EW Riotto, A TI Extra dimensions present a new flatness problem SO PHYSICAL REVIEW D LA English DT Article ID D-BRANES; MILLIMETER; COSMOLOGY AB There is no known fundamental reason to demand as a cosmological initial condition that the bulk possess an SO(3,1) isometry. On the contrary, one expects bulk curvature terms that violate the SO(3,1) isometry at early epochs, leading to a violation of Lorentz invariance on our brane. Demanding that the Lorentz noninvariant terms are small leads to a new "flatness" problem, not solved by the usual formulation of inflation for a class of braneworld solutions. Furthermore, unlike in four dimensions, the Lorentz violations induced from the bulk curvature cannot always be removed as the infrared cutoff is taken arbitrarily large. This means that the equivalence principle in higher dimensions does not guarantee the equivalence principle in dimensionally reduced theories. Near-future experiments are expected to severely constrain these Lorentz-violating "signatures" of extra dimensions. C1 Univ Michigan, Randall Lab Phys, Ann Arbor, MI 48109 USA. NASA, Fermilab Astrophys Ctr, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. Univ Chicago, Enrico Fermi Inst, Dept Astron & Astrophys, Chicago, IL 60637 USA. Scuola Normale Super Pisa, I-56126 Pisa, Italy. Ist Nazl Fis Nucl, I-56127 Pisa, Italy. RP Chung, DJH (reprint author), Univ Michigan, Randall Lab Phys, Ann Arbor, MI 48109 USA. NR 14 TC 24 Z9 24 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD APR 15 PY 2002 VL 65 IS 8 AR 083516 DI 10.1103/PhysRevD.65.083516 PN A PG 9 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 544FE UT WOS:000175146900030 ER PT J AU de Oliveira, HP de Almeida, AMO Soares, ID Tonini, EV AF de Oliveira, HP de Almeida, AMO Soares, ID Tonini, EV TI Homoclinic chaos in the dynamics of a general Bianchi type-IX model SO PHYSICAL REVIEW D LA English DT Article ID MIXMASTER UNIVERSE; EQUATIONS; BEHAVIOR AB The dynamics of a general Bianchi type-IX model with three scale factors is examined. The matter content of the model is assumed to be comoving dust plus a positive cosmological constant. The model presents a critical point of saddle-center-center type in the finite region of phase space. This critical point engenders in the phase space dynamics the topology of stable and unstable four dimensional tubes RxS(3), where R is a saddle direction and S-3 is the manifold of unstable periodic orbits in the center-center sector. A general characteristic of the dynamical flow is an oscillatory mode about orbits of an invariant plane of the dynamics which contains the critical point and a Friedmann-Robertson-Walker (FRW) singularity. We show that a pair of tubes (one stable, one unstable) emerging from the neighborhood of the critical point towards the FRW singularity have homoclinic transversal crossings. The homoclinic intersection manifold has topology RxS(2) and is constituted of homoclinic orbits which are biasymptotic to the S-3 center-center manifold. This is an invariant signature of chaos in the model, and produces chaotic sets in phase space. The model also presents an asymptotic de Sitter attractor at infinity and initial conditions sets are shown to have fractal basin boundaries connected to the escape into the de Sitter configuration (escape into inflation), characterizing the critical point as a chaotic scatterer. C1 Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Estado Rio de Janeiro, Inst Fis, Dept Fis Teor, BR-20550013 Rio De Janeiro, Brazil. Ctr Brasileiro Pesquisas Fis, BR-22290180 Rio De Janeiro, Brazil. Max Planck Inst Phys Complex Syst, D-01187 Dresden, Germany. Ctr Fed Educ Tecnol, BR-29040333 Vitoria, ES, Brazil. RP de Oliveira, HP (reprint author), Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, POB 500, Batavia, IL 60510 USA. NR 32 TC 26 Z9 26 U1 1 U2 5 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD APR 15 PY 2002 VL 65 IS 8 AR 083511 DI 10.1103/PhysRevD.65.083511 PN A PG 9 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 544FE UT WOS:000175146900025 ER PT J AU Tinto, M Estabrook, FB Armstrong, JW AF Tinto, M Estabrook, FB Armstrong, JW TI Time-delay interferometry for LISA SO PHYSICAL REVIEW D LA English DT Article ID GRAVITATIONAL-RADIATION; SPACECRAFT MOTION; ELIMINATION; TRACKING; DETECTOR; NOISE AB LISA (Laser Interferometer Space Antenna) is a mission to detect and study low-frequency cosmic gravitational radiation through its influence on the phases or frequencies of laser beams exchanged between three remote spacecraft. We previously showed how, with lasers of identical frequencies on stationary spacecraft, the measurement of twelve time series of Doppler shifts could be combined to cancel exactly the phase noise of the lasers and the Doppler fluctuations due to noninertial motions of the six optical benches, while preserving gravitational wave signals. Here we generalize those results on gravitational wave detection with time-delay interferometry to the expected LISA instrument. The six lasers have different center frequencies (in the nominal LISA configuration these center frequencies may well differ by several hundred megahertz) and the distances between spacecraft pairs will change with time (these slowly varying orbital Doppler shifts are expected to be up to tens of megahertz). We develop time-delay data combinations which, as previously, preserve gravitational waves and exactly cancel the leading noise source (phase fluctuations of the six lasers); these data combinations then imply transfer functions for the remaining system noises. Using these, we plot frequency and phase power spectra for modeled system noises in the unequal Michelson combination X and the symmetric Sagnac combination zeta. Although optical bench noise can no longer be cancelled exactly, with the current LISA specifications it is suppressed to negligible levels. It is known that the presently anticipated laser center frequency differences and the orbital Doppler drifts introduce another source of phase noise, arising from the onboard oscillators required to track the photodetector fringes. For the presently planned mission, our analysis indeed demonstrates that noise from current-generation ultrastable oscillators would, if uncorrected, dominate the LISA noise budget. To meet the LISA sensitivity goals either achievable improvements in oscillator stability must be combined with much stricter requirements on the allowed laser center frequency differences and on the allowed Doppler shifts from orbital drifts or, as has been previously suggested, additional calibrating interspacecraft data must be taken, by modulating the laser beams and considerably increasing system complexity. We generalize prior schemes for obtaining the required oscillator instability calibration data to the case of six proof masses, six lasers, and three onboard oscillators. For this realistic configuration we derive appropriate time-delayed combinations of the calibrating data to correct each of the laser-noise-free data combinations. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Tinto, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 57 Z9 57 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD APR 15 PY 2002 VL 65 IS 8 AR 082003 DI 10.1103/PhysRevD.65.082003 PN A PG 12 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 544FE UT WOS:000175146900006 ER PT J AU Mallis, MM Neri, DF Oyung, R Colletti, L Nguyen, T Dinges, DF AF Mallis, MM Neri, DF Oyung, R Colletti, L Nguyen, T Dinges, DF TI Stability of behavioral alertness in pilots repeating simulated night flights SO SLEEP LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. San Jose State Univ, San Jose, CA 95192 USA. Raytheon Co, Lexington, MA 02421 USA. Univ Penn, Philadelphia, PA 19104 USA. NR 1 TC 1 Z9 1 U1 0 U2 0 PU AMER ACAD SLEEP MEDICINE PI ROCHESTER PA 6301 BANDEL RD, STE 101, ROCHESTER, MN 55901 USA SN 0161-8105 J9 SLEEP JI Sleep PD APR 15 PY 2002 VL 25 SU S MA 626 BP A443 EP A443 PG 1 WC Clinical Neurology; Neurosciences SC Neurosciences & Neurology GA 540KB UT WOS:000174927200627 ER PT J AU Rodriguez, DM Oyung, RL Barger, LK Mallis, MM Jewett, ME AF Rodriguez, DM Oyung, RL Barger, LK Mallis, MM Jewett, ME TI Flight deck light exposure of pilots during long-haul trips between the United States and Japan SO SLEEP LA English DT Meeting Abstract C1 Brigham & Womens Hosp, Biomath Modeling Unit, Boston, MA 02115 USA. Harvard Univ, Sch Med, Cambridge, MA 02138 USA. San Jose State Univ, NASA, Ames Res Ctr, Fatigue Countermeasures Program, San Jose, CA 95192 USA. NR 1 TC 1 Z9 1 U1 0 U2 0 PU AMER ACAD SLEEP MEDICINE PI ROCHESTER PA 6301 BANDEL RD, STE 101, ROCHESTER, MN 55901 USA SN 0161-8105 J9 SLEEP JI Sleep PD APR 15 PY 2002 VL 25 SU S MA 594 BP A420 EP A421 PG 2 WC Clinical Neurology; Neurosciences SC Neurosciences & Neurology GA 540KB UT WOS:000174927200596 ER PT J AU Wal, RLV Berger, GM Hall, LJ AF Wal, RLV Berger, GM Hall, LJ TI Single-walled carbon nanotube synthesis via a multi-stage flame configuration SO JOURNAL OF PHYSICAL CHEMISTRY B LA English DT Article ID CATALYTIC GROWTH; LASER VAPORIZATION; DIFFUSION FLAMES; METAL PARTICLES; LARGE-SCALE; GAS-PHASE; PYROLYSIS; HYDROCARBONS; DECOMPOSITION; DIAGNOSTICS AB Filter paper, loaded with catalyst precursor, is burned to generate catalyst nanoparticles for single-wall nanotube (SWNT) synthesis in a two-stage flame. A First-stage diffusion flame creates the Fe nanoparticles as an aerosol in the post-flame gases for catalysis. A second-stage flame is formed by the first-stage diffusion flame gases plus added fuel exiting into the combustion gases of a fuel-rich, premixed flame. Both catalyst conditioning and SWNT synthesis occurs within the post-flame reacting flow of this second-stage flame system. C1 NASA Glenn, NCMR, Cleveland, OH 44135 USA. RP NASA Glenn, NCMR, MS 110-3,21000 Brookpark Rd, Cleveland, OH 44135 USA. EM randy.vanderwal@grc.nasa.gov NR 50 TC 24 Z9 24 U1 0 U2 5 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1520-6106 J9 J PHYS CHEM B JI J. Phys. Chem. B PD APR 11 PY 2002 VL 106 IS 14 BP 3564 EP 3567 DI 10.1021/jp012844q PG 4 WC Chemistry, Physical SC Chemistry GA 542AW UT WOS:000175022100010 ER PT J AU Turner, MS Riess, AG AF Turner, MS Riess, AG TI Do type Ia supernovae provide direct evidence for past deceleration of the universe? SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; supernovae : general ID HIGH-REDSHIFT SUPERNOVAE; COSMOLOGICAL CONSTANT; ACCELERATING UNIVERSE; MODELS; LAMBDA AB Observations of SN 1997ff at z similar to 1.7 favor the accelerating universe interpretation and provide some direct evidence that the universe was once decelerating. We show that the strength of this conclusion depends upon the nature of the dark energy causing the present acceleration. Only for a cosmological constant is the SNe evidence definitive. Using a new test which is independent of the contents of the universe, we show that the SN data favor recent acceleration ( z < 0.5) and past deceleration ( z > 0.5). C1 Univ Chicago, Enrico Fermi Inst, Dept Astron & Astrophys, Chicago, IL 60637 USA. Univ Chicago, Enrico Fermi Inst, Dept Phys, Chicago, IL 60637 USA. Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. RP Turner, MS (reprint author), Univ Chicago, Enrico Fermi Inst, Dept Astron & Astrophys, Chicago, IL 60637 USA. NR 32 TC 104 Z9 105 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 2002 VL 569 IS 1 BP 18 EP 22 DI 10.1086/338580 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 539NF UT WOS:000174876800003 ER PT J AU Wallace, PM Halpern, JP Magalhaes, AM Thompson, DJ AF Wallace, PM Halpern, JP Magalhaes, AM Thompson, DJ TI An active galactic nucleus identification for 3EG J2006-2321 SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : observations; quasars : individual (PMN J2005-2310) ID GAMMA-RAY SOURCES; EGRET SOURCES; SUPERNOVA-REMNANTS; RADIO-SOURCES; SKY SURVEY; EMISSION; VARIABILITY; GALAXIES; CATALOG; SEARCH AB We present a multiwavelength analysis of the high-energy gamma-ray source 3EG J2006-2321 (l = 18.degrees82, b = -26.degrees26). The flux of this source above 100 MeV is shown to be variable on timescales of days and months. Optical observations and careful examination of archived radio data indicate that its most probable identification is with PMN J2005-2310, a flat-spectrum radio quasar with a 5 GHz flux density of 260 mJy. Study of the V = 19.3 optical counterpart indicates a redshift of 0.833 and variable linear polarization. No X-ray source has been detected near the position of PMN J2005-2310, but an X-ray upper limit is derived from ROSAT data. This upper limit provides for a spectral energy distribution with global characteristics similar to those of known gamma-ray blazars. Taken together, these data indicate that 3EG J2006-2321, listed as unidentified in the Third EGRET Catalog, is a member of the blazar class of active galactic nuclei (AGNs). The 5 GHz radio flux density of this blazar is the lowest of the 68 EGRET-detected AGNs. The fact that EGRET has detected such a source has implications for unidentified EGRET sources, particularly those at high latitudes (\b\ > 30degrees), many of which may be blazars. C1 Berry Coll, Dept Phys Astron & Geol, Rome, GA 30149 USA. Columbia Univ, Columbia Astrophys Lab, New York, NY 10027 USA. Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-01060970 Sao Paulo, Brazil. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Wallace, PM (reprint author), Berry Coll, Dept Phys Astron & Geol, Campus Box 5004, Rome, GA 30149 USA. RI Thompson, David/D-2939-2012; Magalhaes, Antonio Mario/K-9532-2013 OI Thompson, David/0000-0001-5217-9135; NR 46 TC 17 Z9 17 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 2002 VL 569 IS 1 BP 36 EP 43 DI 10.1086/339286 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 539NF UT WOS:000174876800005 ER PT J AU Howk, JC Sembach, KR Savage, BD Massa, D Friedman, SD Fullerton, AW AF Howk, JC Sembach, KR Savage, BD Massa, D Friedman, SD Fullerton, AW TI The global content, distribution, and kinematics of interstellar OVI in the Large Magellanic Cloud SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : ISM; ISM : atoms; Magellanic Clouds; ultraviolet : ISM ID ULTRAVIOLET-SPECTROSCOPIC-EXPLORER; HIGH-VELOCITY CLOUDS; WIND VARIABILITY; ABSORPTION-LINES; HALO INTERACTION; GALACTIC HALO; IONIZED-GAS; WC STARS; OB STARS; X-RAYS AB We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of interstellar O VI absorption toward 12 early-type stars in the Large Magellanic Cloud (LMC). The observations have a velocity resolution of less than or similar to20 km s(-1) (FWHM) and clearly show O VI 1031.926 Angstrom absorption at LMC velocities toward all 12 stars. From these observations we derive column densities of interstellar O VI in this nearby galaxy; the observed columns are in the range log N(O VI) = 13.9-14.6, with a mean of 14.37 and a standard deviation of +/-38% ((+0.14)(-0.21)dex). The observations probe several sight lines projected onto known superbubbles in the LMC, but these show relatively little (if any) enhancement in O VI column density compared to sight lines toward relatively quiescent regions of the LMC. The observed LMC O VI absorption is broad, with Gaussian dispersions sigma approximate to 30-50 km s(-1). This implies temperatures T less than or similar to (2-5) x 10(6), indicating that much of the broadening is non-thermal because O VI has a very low abundance at such high temperatures. The O VI absorption is typically displaced similar to -30 km s(-1) from the corresponding low-ionization absorption associated with the bulk of the LMC gas. The general properties of the LMC O VI absorption are very similar to those of the Milky Way halo. The average column density of O VI and the dispersion of the individual measurements about the mean are identical to those measured for the halo of the Milky Way, even though the metallicity of the LMC is a factor of similar to2.5 lower than the Milky Way. The velocity dispersion measured for the LMC material is also consistent with recent measurements of the Galactic halo. The striking similarities in these quantities suggest that much of the LMC O VI may arise in a vertically extended distribution similar to the Galactic halo. We discuss the measurements in the context of a halo composed of radiatively cooling hot gas and/or turbulent mixing layers. If the observed O VI absorption is tracing a radiatively cooling galactic fountain flow, the mass flow rate from one side of the LMC disk is of the order (M) over dot similar to 1 M. yr(-1), with a mass flux per unit area of the disk (M) over dot /Omega similar to 2 x 10(-2) M. yr(-1) kpc(-2). C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Wisconsin, Dept Astron, Madison, WI 53711 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. RP Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. EM howk@pha.jhu.edu; sembach@stsci.edu; savage@astro.wisc.edu; derck.massa@gsfc.nasa.gov; scott@pha.jhu.edu; awf@pha.jhu.edu RI Howk, Jay/D-2577-2013; OI Howk, J. Christopher/0000-0002-2591-3792 NR 73 TC 47 Z9 47 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 2002 VL 569 IS 1 BP 214 EP 232 DI 10.1086/339322 PN 1 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 539NF UT WOS:000174876800019 ER PT J AU Smith, DM Heindl, WA Swank, JH AF Smith, DM Heindl, WA Swank, JH TI Two different long-term behaviors in black hole candidates: Evidence for two accretion flows? SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; black hole physics; stars : individual (1E 1740.7 2942, GRS 1758-258, GX 339-4, Cygnus X-1, Cygnus X-3); X-rays : stars ID MOLECULAR CLOUD; CYGNUS X-1; RAY; 1E-1740.7-2942; GRS-1758-258; COUNTERPART; GX339-4; MODEL; 1E1740.7-2942; GX-339-4 AB We discuss the results of long-term hard X-ray monitoring of Galactic black hole candidates 1E 1740.7-2942, GRS 1758-258, Cyg X-1, GX 339-4, and Cyg X-3 with the Rossi X-Ray Timing Explorer. The objects divide into two classes. In the first class, exemplified by Cyg X-1, luminosity and spectral hardness evolve simultaneously. In the second class, the relation is more complicated: the softest spectra occur while the count rate is dropping. Most models of accretion, tailored to Cyg X-1, do not predict the second sort of behavior. One interpretation is a simple model with two simultaneous, independent accretion flows: a thin disk and a hot halo. A drop in the accretion rate affecting both flows would propagate through the halo immediately but might take up to several weeks to propagate through the disk. While the inner halo is thus temporarily depleted compared to the disk, a temporary soft state is expected. This picture is supported by the observation that those sources that show delays (1E 1740.7-2942, GRS 1758-258, and GX 339-4) are expected to have low-mass companions, and those that do not (Cyg X-1, Cyg X-3) are known or thought to have high-mass companions. Low-mass companions imply accretion by Roche lobe overflow, with a high specific angular momentum in the accreting material, and therefore a large disk with a long viscous timescale. Wind accretion from massive companions is expected to result in a much smaller disk and thus little viscous delay. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Smith, DM (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RI Swank, Jean/F-2693-2012 NR 47 TC 117 Z9 120 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 2002 VL 569 IS 1 BP 362 EP 380 DI 10.1086/339167 PN 1 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 539NF UT WOS:000174876800031 ER PT J AU Yaqoob, T Padmanabhan, U Dotani, T Nandra, K AF Yaqoob, T Padmanabhan, U Dotani, T Nandra, K TI The effect of changes in the ASCA calibration on the Fe K lines in active galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (MCG 6-30-15); X-rays : galaxies ID EMISSION AB The ASCA calibration has evolved considerably since launch and, indeed, is still evolving. There have been concerns in the literature that changes in the ASCA calibration have resulted in the Fe K lines in active galactic nuclei (AGNs) now being systematically narrower than was originally thought. If this were true, a large body of ASCA results would be affected. In particular, it has been claimed that the broad red wing (when present) of the Fe Kline has been considerably weakened by changes in the ASCA calibration. We demonstrate explicitly that changes in the ASCA calibration over a period of about 8 years have a negligible effect on the width, strength, or shape of the Fe K lines. The reduction in both width and equivalent width is only similar to8% or less. We confirm this with simulations and individual sources, as well as sample average profiles. The average profile for type 1 AGNs is still very broad, with the red wing extending down to similar to4 keV. The reason for the claimed, apparently large, discrepancies is that in some sources the Fe K line is complex, and a single-Gaussian model, being an inadequate description of the line profile, picks up different portions of the pro le with different calibration. Single-Gaussian fits do not, therefore, model all of the line emission in some sources, in which case they do not compare old and current calibration, since the models do not then describe the data. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Inst Space & Astronaut Sci, Kanagawa 2298510, Japan. Univ Space Res Assoc, Columbia, MD 21044 USA. RP Yaqoob, T (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. NR 17 TC 23 Z9 23 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 2002 VL 569 IS 1 BP 487 EP 492 DI 10.1086/339166 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 539NF UT WOS:000174876800042 ER PT J AU Kaplinghat, M Turner, M AF Kaplinghat, M Turner, M TI How cold dark matter theory explains Milgrom's law SO ASTROPHYSICAL JOURNAL LA English DT Article DE dark matter; galaxies : fundamental parameters galaxies : halos; galaxies : kinematics and dynamics galaxies : spiral; gravitation ID NEWTONIAN DYNAMICS; ANGULAR-MOMENTUM; GALAXY FORMATION; SPIRAL GALAXIES; DISK GALAXIES; MASS; ORIGIN AB Milgrom noticed the remarkable fact that the gravitational effect of dark matter in galaxies only becomes important where accelerations are less than about 10(-8) cm s(-2) similar to cH(o) ("Milgrom's law"). This forms the basis for modified Newtonian dynamics, an alternative to particle dark matter. However, any successful theory of galactic dynamics must account for Milgrom's law. We show how Milgrom's law comes about in the cold dark matter theory of structure formation. C1 Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Chicago, Enrico Fermi Inst, Dept Phys, Chicago, IL 60637 USA. RP Kaplinghat, M (reprint author), Univ Chicago, Dept Astron & Astrophys, 5640 S Ellis Ave, Chicago, IL 60637 USA. NR 25 TC 30 Z9 30 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 2002 VL 569 IS 1 BP L19 EP L22 DI 10.1086/340578 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 539PE UT WOS:000174879000005 ER PT J AU Behn, MD Lin, J Zuber, MT AF Behn, MD Lin, J Zuber, MT TI Mechanisms of normal fault development at mid-ocean ridges SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article DE mid-ocean ridge processes; normal faults; oceanic lithosphere; lithosphere dynamics; stresses; elastic properties ID EAST PACIFIC RISE; SLOW-SPREADING RIDGE; ACCRETING PLATE BOUNDARIES; SINGLE NORMAL-FAULT; SCAN SONAR IMAGES; ATLANTIC RIDGE; CRUSTAL THICKNESS; SEISMIC STRUCTURE; MIDOCEAN RIDGES; LITHOSPHERIC DEFORMATION AB [1] Slow spreading ridge segments are characterized not only by small, closely spaced faults that develop near the segment center but also by large, widely spaced faults that develop near the segment ends, typically at the inside corner of a ridge-offset intersection. In this study we investigate the competing effects of stress accumulation in the lithosphere and the yield strength of the lithosphere in controlling the location of normal fault formation and direction of propagation. Seismic velocity models from the Mid-Atlantic Ridge in the Oceanographer-Hayes region and 29degreesN and the East Pacific Rise at 9degreesN were used to estimate the along-axis change in dynamic Young's modulus. Corresponding thermal and rheologic models were calculated to estimate the along-axis variation in yield strength. We then develop a thin-plate model to calculate the predicted location of fault initiation or reactivation and the subsequent propagation direction for different combinations of linear along-axis gradients in Young's modulus and yield strength. On the basis of this model we define two modes of normal fault development at slow spreading segments: mode C (center) faults, which develop at the segment center and propagate outward, and mode E (end) faults, which develop at the segment ends and propagate inward. Mode C faults are predicted to form at ridges where the along-axis variation in yield strength dominates the along-axis accumulation of stress. Conversely, mode E faults are predicted to develop at ridges where stress accumulation toward segment ends overcomes the high yield strength in these locations. In addition to the accumulation of stress caused by along-axis gradients in Young's modulus, we illustrate that shear stresses resisting relative plate motion along a transform fault will generate higher effective stress at inside corners, possibly concentrating mode E faulting in these locations. At fast spreading ridges, where along-axis gradients in stress and lithospheric strength are relatively small, more uniform patterns of faulting are predicted. The results of this study quantify how the interplay between the along-axis variations in stress state and the mechanical properties of the lithosphere controls the style of fault development at mid-ocean ridge segments. C1 Woods Hole Oceanog Inst, MIT WHOI Joint Program, Woods Hole, MA 02543 USA. Woods Hole Oceanog Inst, Dept Geol & Geophys, Woods Hole, MA 02543 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. RP Behn, MD (reprint author), Woods Hole Oceanog Inst, MIT WHOI Joint Program, Bldg 54-521, Woods Hole, MA 02543 USA. EM mbehn@mit.edu; jlin@whoi.edu; zuber@mit.edu RI Behn, Mark/F-5813-2012 OI Behn, Mark/0000-0002-2001-1335 NR 78 TC 14 Z9 15 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD APR 10 PY 2002 VL 107 IS B4 AR 2083 DI 10.1029/2001JB000503 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 609QX UT WOS:000178917000002 ER PT J AU Dong, D Fang, P Bock, Y Cheng, MK Miyazaki, S AF Dong, D Fang, P Bock, Y Cheng, MK Miyazaki, S TI Anatomy of apparent seasonal variations from GPS-derived site position time series SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article DE seasonal variation; GPS; time series ID ATMOSPHERIC-PRESSURE; CRUSTAL DEFORMATION; GEOCENTER VARIATIONS; EARTHS SURFACE; GEODETIC DATA; FAULT SLIP; SYSTEM; OCEAN; WATER; EARTHQUAKE AB [1] Apparent seasonal site position variations are derived from 4.5 years of global continuous GPS time series and are explored through the "peering'' approach. Peering is a way to depict the contributions of the comparatively well-known seasonal sources to garner insight into the relatively poorly known contributors. Contributions from pole tide effects, ocean tide loading, atmospheric loading, nontidal oceanic mass, and groundwater loading are evaluated. Our results show that similar to40% of the power of the observed annual vertical variations in site positions can be explained by the joint contribution of these seasonal surface mass redistributions. After removing these seasonal effects from the observations the potential contributions from unmodeled wet troposphere effects, bedrock thermal expansion, errors in phase center variation models, and errors in orbital modeling are also investigated. A scaled sensitivity matrix analysis is proposed to assess the contributions from highly correlated parameters. The effects of employing different analysis strategies are investigated by comparing the solutions from different GPS data analysis centers. Comparison results indicate that current solutions of several analysis centers are able to detect the seasonal signals but that the differences among these solutions are the main cause for residual seasonal effects. Potential implications for modeling seasonal variations in global site positions are explored, in particular, as a way to improve the stability of the terrestrial reference frame on seasonal timescales. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif San Diego, Scripps Inst Oceanog, Inst Geophys & Planetary Phys, La Jolla, CA 92093 USA. Univ Texas, Ctr Space Res, Austin, TX 78759 USA. Geodet Observ Ctr, Geog Survey Inst, Ibaraki, Japan. RP Dong, D (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM Danan.Dong@jpl.nasa.gov; pfang@pgga.ucsd.edu; ybock@ucsd.edu; cheng@csr.utexas.edu; miyazaki@eri.u-tokyo.ac.jp RI MIYAZAKI, Shin'ichi/M-1202-2015 NR 62 TC 186 Z9 210 U1 4 U2 24 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD APR 10 PY 2002 VL 107 IS B4 AR 2075 DI 10.1029/2001JB000573 PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 609QX UT WOS:000178917000010 ER PT J AU Zweck, C Freymueller, JT Cohen, SC AF Zweck, C Freymueller, JT Cohen, SC TI Three-dimensional elastic dislocation modeling of the postseismic response to the 1964 Alaska earthquake SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article DE Crustal movements; modeling; earthquake dynamics; earthquake mechanics ID WILLIAM-SOUND EARTHQUAKE; SOUTH CENTRAL ALASKA; SUBDUCTION ZONES; KENAI PENINSULA; STRAIN ACCUMULATION; DEFORMATION; SEGMENT; RELEASE; FAULT; CALIFORNIA AB [1] GPS velocity observations from the Kenai Peninsula and Kodiak Island, Alaska, display a pattern of spatial variability suggesting the presence of multiple active processes on the underlying Pacific-North American plate interface. Velocities of sites on the eastern Kenai Peninsula and Kodiak Island are consistent with elastic strain accumulation at the plate interface, whereas velocities of sites on the western Kenai Peninsula and Cook Inlet are oriented in the opposite direction and suggest an ongoing postseismic response to the 1964 Alaska earthquake. We can reproduce the observed velocities using a three-dimensional elastic dislocation model to estimate the variation in coupling between the Pacific and North American plates. Two different inversion schemes are examined to check the robustness of the results. We find that the GPS data can be satisfied by the presence of a locked area near southwest Prince William Sound, a locked area near southwest Kodiak Island, and an area of postseismic reverse slip beneath and north of the western Kenai Peninsula. The shallow plate interface trenchward of the western Kenai Peninsula does not appear to be locked. The locked areas correspond to the Prince William Sound and Kodiak Island asperities that ruptured in 1964, and the area of postseismic slip lies downdip of the 1964 rupture area. The correspondence between the present shallow coupling distribution and the 1964 slip distribution suggests that the locked regions repeat from one earthquake cycle to another. C1 Univ Alaska, Inst Geophys, Fairbanks, AK 99775 USA. NASA, Geodynam Branch, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Zweck, C (reprint author), Univ Alaska, Inst Geophys, POB 757320, Fairbanks, AK 99775 USA. EM chrisz@giseis.alaska.edu; jeff@giseis.alaska.edu; scohen@carnoustie.gsfc.nasa.gov NR 37 TC 46 Z9 47 U1 0 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD APR 10 PY 2002 VL 107 IS B4 AR 2064 DI 10.1029/2001JB000409 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 609QX UT WOS:000178917000021 ER PT J AU Makoshi, K Mingo, N AF Makoshi, K Mingo, N TI Theory of inelastic scanning tunneling spectroscopy SO SURFACE SCIENCE LA English DT Article; Proceedings Paper CT 10th International Conference on Vibrations at Surfaces CY JUN 17-21, 2001 CL ST MALO, FRANCE DE scanning tunneling spectroscopies; vibrations of adsorbed molecules; copper ID MOLECULE VIBRATIONAL SPECTROSCOPY; CO; CU(100); MICROSCOPY; EXCITATION; MODES AB A theory of inelastic scanning tunneling spectroscopy at T = 0 K and results of its application to C2H2/Cu and CO/Cu are presented. Results of differential conductance show interesting interference effects, which determines the possible observation of each mode. Also considered is the relation between inelastic fraction of conductance and relaxation rate of adsorbate vibrations due to electron-hole pair excitations. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Himeji Inst Technol, Fac Sci, Kamigori, Hyogo 6781297, Japan. Japan Synchrotron Radiat Res Inst, Mikazuki, Sayo 6795148, Japan. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Makoshi, K (reprint author), Himeji Inst Technol, Fac Sci, Kamigori, Hyogo 6781297, Japan. NR 15 TC 4 Z9 4 U1 1 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0039-6028 J9 SURF SCI JI Surf. Sci. PD APR 10 PY 2002 VL 502 BP 34 EP 40 AR PII S0039-6028(01)01895-7 DI 10.1016/S0039-6028(01)01895-7 PG 7 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA 548HZ UT WOS:000175383700007 ER PT J AU Okumura, M Garland, ER Morrell, C Christensen, LE Bean, BD Nizkorodov, S Choi, P Sander, SP AF Okumura, M Garland, ER Morrell, C Christensen, LE Bean, BD Nizkorodov, S Choi, P Sander, SP TI Free radical reactions studied by IR cavity ringdown and FM spectroscopies. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH, Dept Chem, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 454-PHYS BP C86 EP C86 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CE UT WOS:000176296801898 ER PT J AU Smirnov, SN Montforts, FP Vlassiouk, I Kutzki, O Wedel, M Sander, SP AF Smirnov, SN Montforts, FP Vlassiouk, I Kutzki, O Wedel, M Sander, SP TI Long-lived photoinduced charge transfer states in novel porphyrin-fullerene and chlorin-fullerene dyads. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 New Mexico State Univ, Dept Chem & Biochem, Las Cruces, NM 88003 USA. Univ Bremen, Inst Organ Chem, D-2800 Bremen 33, Germany. Yale Univ, Dept Chem, New Haven, CT USA. Duke Univ, Dept Chem, Durham, NC 27706 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. NR 0 TC 0 Z9 0 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 443-PHYS BP C85 EP C85 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CE UT WOS:000176296801887 ER PT J AU Chandrasekhar, P Zay, BJ Ross, D McQueeney, T Birur, GC Swanson, T Kauder, L Douglas, D AF Chandrasekhar, P Zay, BJ Ross, D McQueeney, T Birur, GC Swanson, T Kauder, L Douglas, D TI Conducting polymer based dynamic IR-electrochromics for spacecraft thermal control. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Ashwin Ushas Corp Inc, Lakewood, NJ 08701 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 287-POLY BP D25 EP D25 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CE UT WOS:000176296802251 ER PT J AU Hergenrother, PM Watson, KA Smith, JG Connell, JW Yokota, R AF Hergenrother, PM Watson, KA Smith, JG Connell, JW Yokota, R TI Polyimides from 2,3,3 ',4 '-biphenyltetracarboxylic dianhydride and aromatic diamines. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Inst Space & Astronaut Sci, Tokyo 153, Japan. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 283-POLY BP D25 EP D25 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CE UT WOS:000176296802247 ER PT J AU Melendez, O Williams, MK AF Melendez, O Williams, MK TI Surface characterization of the weathering degradation of polyimide foams. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Testbeds, Kennedy Space Ctr, Kennedy Space Ctr, FL 32899 USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 035-PMSE BP D62 EP D62 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CE UT WOS:000176296802462 ER PT J AU Borgstahl, GEO Lovelace, J Vahedi-Faridi, A Bellamy, HD Snell, EH AF Borgstahl, GEO Lovelace, J Vahedi-Faridi, A Bellamy, HD Snell, EH TI One of the finer things in life: Perfecting macromolecular crystal analysis. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Univ Toledo, Dept Chem, Toledo, OH 43606 USA. NASA, Ctr Adv Microstruct & Devices, Washington, DC 20546 USA. NASA, Struct Biol Lab, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 167-IEC BP U652 EP U652 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296703583 ER PT J AU Clausen, CA Cooper, CD Collins, M Pettey, L Geiger, CL AF Clausen, CA Cooper, CD Collins, M Pettey, L Geiger, CL TI A pilot-scale evaluation of ultraviolet light-enhanced H2O2 oxidation of NOx emissions SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Univ Cent Florida, Dept Chem, Orlando, FL 32816 USA. NASA, Kennedy Space Ctr, FL 32899 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 017-CATL BP U18 EP U18 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296700044 ER PT J AU Conrad, PG Luttge, A AF Conrad, PG Luttge, A TI Surface interactions between Shewanella oneidensis and calcite at neutral pH. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH, Jet Prop Lab, Ctr Life Detect, Pasadena, CA 91109 USA. Rice Univ, Dept Earth Sci, Houston, TX 77251 USA. RI Luttge, Andreas/A-2560-2011 OI Luttge, Andreas/0000-0002-5878-4026 NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 089-GEOC BP U605 EP U606 PN 1 PG 2 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296703329 ER PT J AU Flynn, GJ Keller, LP AF Flynn, GJ Keller, LP TI Synchrotron radiation analysis of interplanetary dust: Clues to the formation of organic matter in the solar system. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 SUNY Coll Plattsburgh, Dept Phys, Plattsburgh, NY 12901 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 109-GEOC BP U609 EP U609 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296703349 ER PT J AU Hehemann, DG Kundu, KP AF Hehemann, DG Kundu, KP TI Inerting of jet fuel contained in fuel tanks in commercial aircrafts. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Cleveland State Univ, Dept Chem, Cleveland, OH 44115 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 14-CHAS BP U147 EP U147 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296700717 ER PT J AU Judge, RA Kephart, R Snell, EH van der Woerd, M AF Judge, RA Kephart, R Snell, EH van der Woerd, M TI Decades of data: Extracting trends from microgravity crystallization history. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 168-IEC BP U652 EP U652 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296703584 ER PT J AU Kojiro, DR Sheverev, VA Khromov, NA AF Kojiro, DR Sheverev, VA Khromov, NA TI Chemical detection and identification techniques for exobiology flight experiments. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Exobiol Branch, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 045-ANYL BP U70 EP U70 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296700304 ER PT J AU Love, GD Summons, RE Snape, CE Jahnke, LL Logan, GA AF Love, GD Summons, RE Snape, CE Jahnke, LL Logan, GA TI Rapid screening of microorganisms using catalytic hydropyrolysis to identify chemotaxonomic lipid markers. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Univ Newcastle Upon Tyne, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. Univ Nottingham, Sch Chem Environm & Min Engn, Nottingham NG7 2RD, England. NASA, Ames Res Ctr, Exobiol Branch, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 053-GEOC BP U599 EP U600 PN 1 PG 2 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296703293 ER PT J AU Morales, AL Miranda, FA Cabrera, CR AF Morales, AL Miranda, FA Cabrera, CR TI Optimization of ferroelectric thin films based RF phase shifters via self-assembled monolayer modification methods. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Univ Puerto Rico, Dept Chem, San Juan, PR 00931 USA. NASA, Glenn Res Ctr, Appl RF Technol Branch, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 283-COLL BP U427 EP U427 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296702361 ER PT J AU Pusey, ML AF Pusey, ML TI Tetragonal lysozyme, from monomer to crystal. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 170-IEC BP U653 EP U653 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296703586 ER PT J AU Rossi, D Smith, CA Paley, M AF Rossi, D Smith, CA Paley, M TI Kinetics of polymerization of diacetylene methyl nitroaniline. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Our Lady Lake Univ, San Antonio, TX 78207 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 240-CHED BP U196 EP U196 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296700980 ER PT J AU Rouse, JH Ounales, Z T Lellehei, PT Siochi, EJ AF Rouse, JH Ounales, Z T Lellehei, PT Siochi, EJ TI Incorporation of carbon nanotubes within stepwise assembled polyelectrolyte films SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Adv Mat Proc Branch, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 169-COLL BP U398 EP U398 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296702248 ER PT J AU Sander, SP Christensen, LE Okumura, M Garland, ER Morrell, C Bean, BD Nizkorodov, S Choi, P AF Sander, SP Christensen, LE Okumura, M Garland, ER Morrell, C Bean, BD Nizkorodov, S Choi, P TI Rates and mechanisms of peroxy and alkoxy radicals using infrared laser spectroscopy. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. CALTECH, Dept Chem, Pasadena, CA 91125 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 083-ENVR BP U522 EP U522 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296702920 ER PT J AU Sherry, LJ Ticich, TM Wal, RLV Hall, L AF Sherry, LJ Ticich, TM Wal, RLV Hall, L TI Laser assisted methods of metal catalyst production for carbon nanostructure synthesis. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Centenary Coll Louisiana, Dept Chem, Shreveport, LA 71134 USA. NASA, Glenn Res Ctr, NCMR, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 902-CHED BP U301 EP U301 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296701641 ER PT J AU Villegas, Y Smith, CA Gostowski, R AF Villegas, Y Smith, CA Gostowski, R TI Compatibility of materials with hydrogen peroxide: Isothermal microcalorimetry. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, George C Marshall Space Flight Ctr, Mat Combust Res Facil, Huntsville, AL 35812 USA. Our Lady Lake Univ, San Antonio, TX 78207 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 7 PY 2002 VL 223 MA 207-CHED BP U192 EP U192 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 564CD UT WOS:000176296700948 ER PT J AU Boldt, E Levinson, A Loewenstein, M AF Boldt, E Levinson, A Loewenstein, M TI Black-hole galactic nuclei: a high-energy perspective SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article; Proceedings Paper CT 4th Edoardo Amaldi Conference on Gravitational Waves CY JUL 08-13, 2001 CL PERTH, AUSTRALIA ID COSMIC-RAYS; GALAXIES; EMISSION; REMNANTS AB The gravitational radiation signals to be anticipated from events involving black-hole galactic nuclei depend on the spin of the underlying object. To obtain evidence about the spin of Seyfert AGN black holes, we can rely on future ultra-high resolution spectral/spatial x-ray studies of iron K line fluorescence from the innermost regions of accreting matter. Normal galaxies present more of a challenge. To account for the highest energy cosmic rays, we propose that ultra-relativistic particle acceleration can occur near the event horizons of spun-up supermassive black-holes at the non-active nuclei of giant elliptical galaxies. This conjecture about the black hole spin associated with such nuclei is subject to verification via the characteristic TeV curvature radiation expected to be detected with upcoming gamma-ray observatories. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Tel Aviv Univ, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Boldt, E (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NR 22 TC 1 Z9 1 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD APR 7 PY 2002 VL 19 IS 7 BP 1317 EP 1319 AR PII S0264-9381(02)28456-7 DI 10.1088/0264-9381/19/7/312 PG 3 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 544TX UT WOS:000175178400013 ER PT J AU Strohmayer, TE AF Strohmayer, TE TI Gravitational waves from rotating neutron stars and evaluation of fast chirp transform techniques SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article; Proceedings Paper CT 4th Edoardo Amaldi Conference on Gravitational Wave CY JUL 08-13, 2001 CL PERTH, AUSTRALIA ID X-RAY-BURSTS; QUASI-PERIODIC OSCILLATIONS; ACCRETION-INDUCED COLLAPSE; COHERENT OSCILLATIONS; MILLISECOND PULSATIONS; TIMING-EXPLORER; BINARY; FREQUENCY; PULSAR; DISCOVERY AB X-ray observations suggest that neutron stars in low mass x-ray binaries (LMXB) are rotating with frequencies in the range 300-600 Hz. These spin rates are significantly less than the break-up rates for essentially all realistic neutron star equations of state, suggesting that some process may limit the spin frequencies of accreting neutron stars to this range. If the accretion-induced spin up torque is in equilibrium with gravitational radiation losses, these objects could be interesting sources of gravitational waves. I present a brief summary of current measurements of neutron star spins in LMXBs based on the observations of high-Q oscillations during thermonuclear bursts (so-called 'burst oscillations'). Further measurements of neutron star spins will be important in exploring the gravitational radiation hypothesis in more detail. To this end, I also present a study of fast chirp transform (FCT) techniques as described by Jenet and Prince (Prince T A and Jenet F A 2000 Phys. Rev. D 62 122001) in the context of searching for the chirping signals observed during x-ray bursts. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Strohmayer, TE (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NR 45 TC 0 Z9 0 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD APR 7 PY 2002 VL 19 IS 7 BP 1321 EP 1326 AR PII S0264-9381(02)29311-9 DI 10.1088/0264-9381/19/7/313 PG 6 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 544TX UT WOS:000175178400014 ER PT J AU Sengupta, AS Dhurandhar, SV Lazzarini, A Prince, T AF Sengupta, AS Dhurandhar, SV Lazzarini, A Prince, T TI Extended hierarchical search (EHS) algorithm for detection of gravitational waves from inspiralling compact binaries SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article; Proceedings Paper CT 4th Edoardo Amaldi Conference on Gravitational Wave CY JUL 08-13, 2001 CL PERTH, AUSTRALIA ID COALESCING BINARIES; STRATEGY; FILTERS; CHOICE AB Pattern matching techniques such as matched filtering will be used for online extraction of gravitational wave signals buried inside detector noise. This involves cross correlating the detector output with hundreds of thousands of templates spanning a multi-dimensional parameter space, which is very expensive computationally. A faster implementation algorithm was devised by Mohanty and Dhurandhar using a hierarchy of templates over the mass parameters, which speeded up the procedure by about 25-30 times. We show that a further reduction in computational cost is possible if we extend the hierarchy paradigm to an extra parameter, namely, the time of arrival of the signal. In the first stage, the chirp waveform is cut-off at a relatively low frequency allowing the data to be coarsely sampled leading to cost saving in pet-forming the FFTs. This is possible because most of the signal power is at low frequencies, and therefore the advantage due to hierarchy over masses is not compromised. Results are obtained for spinless templates up to the second post-Newtonian (2PN) order for a single detector with LIGO I noise power spectral density. We estimate that the gain in computational cost over a flat search is about 100, which is about a factor of four over the previous less sophisticated hierarchical scheme. C1 Inter Univ Ctr Astron & Astrophys, Pune 411007, Maharashtra, India. CALTECH, LIGO Lab, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sengupta, AS (reprint author), Inter Univ Ctr Astron & Astrophys, Post Bag 4, Pune 411007, Maharashtra, India. NR 6 TC 1 Z9 1 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD APR 7 PY 2002 VL 19 IS 7 BP 1507 EP 1512 AR PII S0264-9381(02)29296-5 DI 10.1088/0264-9381/19/7/337 PG 6 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 544TX UT WOS:000175178400038 ER PT J AU Merkowitz, SM Maghami, PG Sharma, A Willis, WD Zakrzwski, CM AF Merkowitz, SM Maghami, PG Sharma, A Willis, WD Zakrzwski, CM TI A mu Newton thrust-stand for LISA SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article; Proceedings Paper CT 4th Edoardo Amaldi Conference on Gravitational Wave CY JUL 08-13, 2001 CL PERTH, AUSTRALIA AB The success of the LISA project depends on the ability of the disturbance reduction system to shield the proof masses from all external forces and to maintain tight pointing requirements relative to the other two spacecrafts. muN-thrusters are required to compensate for the solar radiation pressure acting on the spacecraft. The force noise from these thrusters must be low enough not to disturb the freely floating proof masses. To date, these noise requirements have not been demonstrated, mostly because no thrust-stand exists with sufficient sensitivity. We present the status of our muNewton thrust-stand that will verify that the thrusters proposed for LISA will meet the noise requirements. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Merkowitz, SM (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Merkowitz, Stephen/D-6680-2012 OI Merkowitz, Stephen/0000-0002-0412-4209 NR 7 TC 19 Z9 26 U1 0 U2 3 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD APR 7 PY 2002 VL 19 IS 7 BP 1745 EP 1750 AR PII S0264-9381(02)29337-5 DI 10.1088/0264-9381/19/7/370 PG 6 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 544TX UT WOS:000175178400071 ER PT J AU Tinto, M AF Tinto, M TI The Cassini Ka-band gravitational wave experiments SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article; Proceedings Paper CT 4th Edoardo Amaldi Conference on Gravitational Wave CY JUL 08-13, 2001 CL PERTH, AUSTRALIA ID SPACECRAFT DOPPLER TRACKING; RADIATION; DETECTOR AB Cassini, a joint American/European interplanetary scientific mission to Saturn, will be continuously and coherently tracked for 40 days during its solar oppositions in the next three years, starting on 26 November 2001. Doppler tracking searches for gravitational waves in the millihertz frequency band will be performed by using newly implemented Ka-band (approximate to32 GHz) microwave capabilities on the ground and onboard the spacecraft, Use of the Ka-band coherent microwave link will suppress solar plasma scintillations to levels below those identified by remaining instrumental noise sources, making the Cassini Doppler tracking experiments the most sensitive searches for gravitational waves ever attempted in the millihertz frequency band. This paper provides a short review of the Doppler response to gravitational radiation, the noise sources and their transfer functions into the Doppler observable and estimates of the anticipated Cassini Doppler tracking sensitivities to gravitational radiation. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Tinto, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 4 TC 15 Z9 16 U1 1 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD APR 7 PY 2002 VL 19 IS 7 BP 1767 EP 1773 AR PII S0264-9381(02)29064-4 DI 10.1088/0264-9381/19/7/373 PG 7 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 544TX UT WOS:000175178400074 ER PT J AU Wang, J Escarpa, A Pumera, M Feldman, J AF Wang, J Escarpa, A Pumera, M Feldman, J TI Capillary electrophoresis-electrochemistry microfluidic system for the determination of organic peroxides SO JOURNAL OF CHROMATOGRAPHY A LA English DT Article DE chip technology; detection, electrophoresis; electrochemical detection; instrumentation; peroxides ID PERFORMANCE LIQUID-CHROMATOGRAPHY; FILM AMPEROMETRIC DETECTORS; PEROXYACETIC ACID; SEPARATION; MICROCHIP; CHIPS AB A microfluidic analytical system for the separation and detection of organic peroxides. based on a microchip capillary electrophoresis device with an integrated amperometric detector. was developed. The new microsystem relies on the reductive detection of both organic acid peroxides and hydroperoxides at -700 mV (vs. Ag wire/AgCl). Factors influencing the separation and detection processes were examined and optimized, The integrated microsystem offers rapid measurements (within 130 s) of these organic-peroxide compounds, down to micromolar levels. A highly stable response for repetitive injections (RSD 0.35-3.12% n = 12) reflects the negligible electrode passivation. Such a "lab-on-a-chip" device should be attractive for on-site analysis of organic peroxides, as desired for environmental screening and industrial monitoring, (C) 2002 Elsevier Science B.V. All rights reserved. C1 New Mexico State Univ, Dept Chem & Biochem, Las Cruces, NM 88003 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wang, J (reprint author), New Mexico State Univ, Dept Chem & Biochem, Las Cruces, NM 88003 USA. RI Wang, Joseph/C-6175-2011; Pumera, Martin/F-2724-2010; Escarpa, Alberto/N-2293-2016 OI Pumera, Martin/0000-0001-5846-2951; Escarpa, Alberto/0000-0002-7302-0948 NR 21 TC 57 Z9 59 U1 0 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0021-9673 J9 J CHROMATOGR A JI J. Chromatogr. A PD APR 5 PY 2002 VL 952 IS 1-2 BP 249 EP 254 AR PII S0021-9673(02)00075-4 PG 6 WC Biochemical Research Methods; Chemistry, Analytical SC Biochemistry & Molecular Biology; Chemistry GA 548QT UT WOS:000175400900024 PM 12064536 ER PT J AU Giorgini, JD Ostro, SJ Benner, LAM Chodas, PW Chesley, SR Hudson, RS Nolan, MC Klemola, AR Standish, EM Jurgens, RF Rose, R Chamberlain, AB Yeomans, DK Margot, JL AF Giorgini, JD Ostro, SJ Benner, LAM Chodas, PW Chesley, SR Hudson, RS Nolan, MC Klemola, AR Standish, EM Jurgens, RF Rose, R Chamberlain, AB Yeomans, DK Margot, JL TI Asteroid 1950 DA's encounter with Earth in 2880: Physical limits of collision probability prediction SO SCIENCE LA English DT Article ID CROSSING ASTEROIDS; DYNAMICS AB Integration of the orbit of asteroid (29075) 1950 DA, which is based on radar and optical measurements spanning 51 years, reveals a 20-minute interval in March 2880 when there could be a nonnegligible probability of the 1-kilometer object colliding with Earth. Trajectory knowledge remains accurate until then because of extensive astrometric data, an inclined orbit geometry that reduces in-plane perturbations, and an orbit uncertainty space modulated by gravitational resonance. The approach distance uncertainty in 2880 is determined primarily by uncertainty in the accelerations arising from thermal re-radiation of solar energy absorbed by the asteroid. Those accelerations depend on the spin axis, composition, and surface properties of the asteroid, so that refining the collision probability may require direct inspection by a spacecraft. 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 Calif Santa Cruz, Lick Observ, Santa Cruz, CA 95064 USA. CALTECH, Pasadena, CA 91125 USA. RP Giorgini, JD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM Jon.Giorgini@jpl.nasa.gov 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 26 TC 52 Z9 53 U1 0 U2 0 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD APR 5 PY 2002 VL 296 IS 5565 BP 132 EP 136 DI 10.1126/science.1068191 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 539FA UT WOS:000174858800045 PM 11935024 ER PT J AU Ricca, A Bauschlicher, CW AF Ricca, A Bauschlicher, CW TI Theoretical study of the interaction of water and imidazole with iron and nickel dications SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID GAUSSIAN-BASIS SETS; CRYSTAL-STRUCTURE; MOLECULAR CALCULATIONS; ROW ATOMS; BINDING; CHAPERONIN; LIGANDS; ENERGIES; COMPLEX AB The structures, the harmonic frequencies, and the energies of Fe(H2O)(n)(imid)(m)(2+) and Ni(H2O)n(imid)(m)(2+) complexes are computed using density functional theory with the B3LYP functional. A CSOV analysis shows that the bonding is mostly electrostatic in nature. Imidazole forms a stronger bond than water with both metal dications because of its larger dipole moment and polarizability. The reactions for the exchange of one water molecule by one imidazole are exothermic, and up to six water molecules can be replaced by imidazoles. The trends are very similar for both metals with the displacement reactions being slightly more favorable for Ni2+. C1 NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. RP Ricca, A (reprint author), ELORET Corp, Mail Stop 230-3, Sunnyvale, CA 94087 USA. NR 27 TC 15 Z9 15 U1 0 U2 0 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 4 PY 2002 VL 106 IS 13 BP 3219 EP 3223 DI 10.1021/jp014133y PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 538BA UT WOS:000174793100024 ER PT J AU Avdeev, S Bidoli, V Casolino, M De Grandis, E Furano, G Morselli, A Narici, L De Pascale, MP Picozza, P Reali, E Sparvoli, R Boezio, M Carlson, P Bonvicini, W Vacchi, A Zampa, N Castellini, G Fuglesang, C Galper, A Khodarovich, A Ozerov, Y Popov, A Vavilov, N Mazzenga, G Ricci, M Sannita, WG Spillantini, P AF Avdeev, S Bidoli, V Casolino, M De Grandis, E Furano, G Morselli, A Narici, L De Pascale, MP Picozza, P Reali, E Sparvoli, R Boezio, M Carlson, P Bonvicini, W Vacchi, A Zampa, N Castellini, G Fuglesang, C Galper, A Khodarovich, A Ozerov, Y Popov, A Vavilov, N Mazzenga, G Ricci, M Sannita, WG Spillantini, P TI Eye light flashes on the Mir space station SO ACTA ASTRONAUTICA LA English DT Article ID BEAM TEST; NINA AB The phenomenon of light flashes (LF) in eyes for people in space has been investigated onboard Mir. Data on particles hitting the eye have been collected with the SilEye detectors, and correlated with human observations, It is found that a nucleus in the radiation environment of Mir has roughly a 1% probability to cause an LF, whereas the proton probability is almost three orders of magnitude less, As a function of LET, the LF probability increases above 10 keV/mum, reaching about 5% at around 50 keV/mum. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Russian Space Corp Energia Korolev, Moscow, Russia. RP Fuglesang, C (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code OT, Houston, TX 77058 USA. RI Morselli, Aldo/G-6769-2011; Vacchi, Andrea/C-1291-2010; Galper, Arkady/M-9610-2015; OI Morselli, Aldo/0000-0002-7704-9553; Vacchi, Andrea/0000-0003-3855-5856; casolino, marco/0000-0001-6067-5104; Castellini, Guido/0000-0002-0177-0643; Sparvoli, Roberta/0000-0002-6314-6117; Picozza, Piergiorgio/0000-0002-7986-3321; Boezio, Mirko/0000-0002-8015-2981 NR 28 TC 28 Z9 30 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 APR PY 2002 VL 50 IS 8 BP 511 EP 525 DI 10.1016/S0094-5765(01)00190-4 PG 15 WC Engineering, Aerospace SC Engineering GA 554TK UT WOS:000175753100003 PM 11962526 ER PT J AU Gorchakova, N Kuznetsov, L Yarygin, V Chanetz, B Pot, T Bur, R Taran, JP Pigache, D Schulte, D Moss, J AF Gorchakova, N Kuznetsov, L Yarygin, V Chanetz, B Pot, T Bur, R Taran, JP Pigache, D Schulte, D Moss, J TI Progress in hypersonic studies using electron-beam-excited x-ray detection SO AIAA JOURNAL LA English DT Article AB Experimental and numerical studies of the laminar shock-wave/boundary-layer interaction occurring past a hollow cylinder flare model in a Mach 10 air flow at zero incidence were conducted. Flowfield density measurements were performed by detecting x-ray emissions from the gas produced by electron-beam impact. A solution was found to make these measurements possible near the model surface. Wall pressure and heat flux measurements have been performed. All of the experimental results are compared with numerical results obtained by using Navier-Stokes and direct simulation Monte Carlo solvers. C1 Inst Thermophys, Novosibirsk 630090, Russia. Off Natl Etud & Rech Aerosp, F-92300 Chatillon, France. DLR, German Aerosp Res Ctr, D-51147 Cologne, Germany. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Gorchakova, N (reprint author), Inst Thermophys, Novosibirsk 630090, Russia. NR 24 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD APR PY 2002 VL 40 IS 4 BP 593 EP 598 DI 10.2514/2.1698 PG 6 WC Engineering, Aerospace SC Engineering GA 536RZ UT WOS:000174716800001 ER PT J AU Kao, HC AF Kao, HC TI Body-vortex interaction, sound generation, and destructive interference SO AIAA JOURNAL LA English DT Article ID NOISE AB It is generally recognized that the interaction of vortices with downstream blades is a major source of noise production. To analyze this problem numerically, a two-dimensional model of inviscid flow, together with the method of matched asymptotic expansions. is proposed. The method of matched asymptotic expansions is used to match the inner region of incompressible How to the outer region of compressible flow. Because of incompressibility, relatively simple numerical methods are available to treat multiple vortices and multiple bodies of arbitrary shape. Disturbances from these vortices and bodies propagate outward as sound waves. Because of their interactions, either constructive or destructive interference may result. When it is destructive, the combined sound intensity can be reduced, sometimes substantially. C1 NASA, John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. RP Kao, HC (reprint author), POB 360872, Strongsville, OH 44136 USA. NR 21 TC 7 Z9 7 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD APR PY 2002 VL 40 IS 4 BP 652 EP 660 DI 10.2514/2.1722 PG 9 WC Engineering, Aerospace SC Engineering GA 536RZ UT WOS:000174716800008 ER PT J AU Watson, WR Nguyen, DT Reddy, CJ Vatsa, VN Tang, WH AF Watson, WR Nguyen, DT Reddy, CJ Vatsa, VN Tang, WH TI Algorithms and application of sparse matrix assembly and equation solvers for aeroacoustics SO AIAA JOURNAL LA English DT Article ID MINIMUM-DEGREE ALGORITHM; LINEAR-EQUATIONS; FACTORIZATION; ELIMINATION; SYSTEM AB An algorithm for symmetric sparse equation solutions on an unstructured grid is described. Efficient, sequential sparse algorithms for degree-of-freedom reordering, supernodes, symbolic/numerical factorization, and forward/backward solution phases are reviewed. Three sparse algorithms for the generation and assembly of symmetric systems of matrix equations are presented. The accuracy and numerical performance of the sequential version of the sparse algorithms are evaluated over the frequency range of interest in a three-dimensional aeroacoustics application. Results show that the solver solutions are accurate using a discretization of 12 points per wavelength. Results also show that the first assembly algorithm is impractical for high-frequency noise calculations. The second and third assembly algorithms have nearly equal performance at low values,of source frequencies, but at higher values of source frequencies the third algorithm saves CPU time and RAM., The, CPU time and the RAM required by the second and third assembly algorithms are two orders of magnitude smaller than that required by the sparse equation solver. A sequential version of these sparse algorithms can, therefore, be conveniently incorporated into a substructuring (or domain decomposition) formulation to achieve parallel, computation, where different substructures are handled by different parallel processors. C1 NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Hampton, VA 23681 USA. Old Dominion Univ, Multidisciplinary Parallel Vector Computat Ctr, Norfolk, VA 23529 USA. EM Inc, Hampton, VA 23666 USA. NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Hampton, VA 23681 USA. Hong Kong Univ Sci & Technol, Dept Civil & Struct Engn, Kowloon, Hong Kong, Peoples R China. RP Watson, WR (reprint author), NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Hampton, VA 23681 USA. NR 25 TC 0 Z9 0 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD APR PY 2002 VL 40 IS 4 BP 661 EP 670 DI 10.2514/2.1723 PG 10 WC Engineering, Aerospace SC Engineering GA 536RZ UT WOS:000174716800009 ER PT J AU Morris, PJ Farassat, F AF Morris, PJ Farassat, F TI Acoustic analogy and alternative theories for jet noise prediction SO AIAA JOURNAL LA English DT Article ID MIXING NOISE; COMPUTATION; FLOWS AB Several methods for the prediction of jet noise are described All but one of the noise prediction schemes are based on Lighthill's or Lilley's acoustic analogy, whereas the other is the jet noise generation model recently proposed by Tam and Auriault. In all of the approaches, some assumptions must be made concerning the statistical properties of the turbulent sources. In each case:the characteristic scales of the turbulence are obtained from a solution of the Reynolds-averaged Navier-Stokes equation using a k-epsilon turbulence model. It is shown that, for the same level of empiricism, Tam and Auriault's model yields better agreement with experimental noise measurements than the acoustic analogy. It is then shown that this result is not because of some fundamental flaw in the acoustic analogy approach, but instead is associated with the assumptions made in the approximation of the turbulent source statistics. If consistent assumptions are made, both the acoustic analogy and Tam and Auriault's model yield identical noise predictions. In conclusion, a proposal is presented for an acoustic analogy that provides a clearer identification of the equivalent source mechanisms, as is a discussion of noise prediction issues that remain to be resolved. C1 Penn State Univ, Dept Aerosp Engn, University Pk, PA 16802 USA. NASA, Langley Res Ctr, Aeroacoust Branch, Hampton, VA 23681 USA. RP Morris, PJ (reprint author), Penn State Univ, Dept Aerosp Engn, University Pk, PA 16802 USA. NR 19 TC 62 Z9 65 U1 3 U2 11 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD APR PY 2002 VL 40 IS 4 BP 671 EP 680 DI 10.2514/2.1699 PG 10 WC Engineering, Aerospace SC Engineering GA 536RZ UT WOS:000174716800010 ER PT J AU Taghavi, RR Raman, G Bencic, TJ AF Taghavi, RR Raman, G Bencic, TJ TI Mixer-ejector wall pressure and temperature measurements based on photoluminescence SO AIAA JOURNAL LA English DT Article ID SENSITIVE PAINT; NOZZLE AB Ejector side-wall pressure distribution is a key indicator of supersonic jet-mixer-ejector performance. When documenting pressure patterns on an ejector wall using pressure-sensitive paint (PSP), one has to consider temperature variations caused by the supersonic jet flow within the ejector because these can cause significant local errors in the PSP results. If the temperature sensitivity of PSP is not corrected for in complex internal supersonic flows, large localized errors could contaminate the results. In the present work, temperature-sensitive paint maps the temperature distribution on the ejector wall and corrects PSP results point-by-point for temperature sensitivity. The experiments were conducted on multijet supersonic mixer-ejector configurations with straight, convergent (6-deg), and divergent (6-deg) side walls. A comparison of corrected and uncorrected PSP readings shows that at M-j = 1.55, the error with respect to true data from static pressure ports can be reduced from 4.98 to 2.84% for the case of a simple ejector with parallel walls. For the complex 6-deg convergent ejector at M-j = 1.39, the error reduces by almost an order of magnitude (from 20.83 to 2.66%). Our results indicate that the use of this correction technique can significantly reduce PSP errors in complex internal supersonic flow situations. C1 Univ Kansas, Dept Aerosp Engn, Lawrence, KS 66045 USA. IIT, Dept Mech & Aerosp Engn, Chicago, IL 60616 USA. NASA, John H Glenn Res Ctr Lewis Field, Opt Instrumentat Technol Branch, Cleveland, OH 44135 USA. RP Taghavi, RR (reprint author), Univ Kansas, Dept Aerosp Engn, Lawrence, KS 66045 USA. NR 21 TC 5 Z9 5 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD APR PY 2002 VL 40 IS 4 BP 745 EP 750 DI 10.2514/2.1707 PG 6 WC Engineering, Aerospace SC Engineering GA 536RZ UT WOS:000174716800018 ER PT J AU Tsurutani, BT Zhang, LD Mason, GL Lakhina, GS Hada, T Arballo, JK Zwickl, RD AF Tsurutani, BT Zhang, LD Mason, GL Lakhina, GS Hada, T Arballo, JK Zwickl, RD TI Particle transport in He-3-rich events: wave-particle interactions and particle anisotropy measurements SO ANNALES GEOPHYSICAE LA English DT Article DE interplanetary physics; energetic particles; MHD waves and turbulence; space plasma physics; charged particle motion and acceleration; wave-particle interactions ID SOLAR ENERGETIC PARTICLES; COSMIC-RAY TRANSPORT; HIGH HELIOGRAPHIC LATITUDES; PITCH-ANGLE DIFFUSION; MEAN FREE PATHS; ALFVEN WAVES; MAGNETIC CLOUDS; INTERPLANETARY DISCONTINUITIES; TANGENTIAL DISCONTINUITIES; ULYSSES OBSERVATIONS AB Energetic particles and MHD waves are studied using simultaneous ISEE-3 data to investigate particle propagation and scattering between the source near the Sun and 1 AU. He-3-rich events arc of particular interest because they are typically low intensity "scatter-free" events. The largest solar proton events are of interest because they have been postulated to generate their own waves through beam instabilities, For 3He-rich events, simultaneous interplanetary magnetic spectra are measured. The intensity of the interplanetary "fossil" turbulence through which the particles have traversed is found to be at the "quiet" to "intermediate" level of IMF activity. Pitch angle scattering rates and the corresponding particle mean free paths; lambda(W-P) are calculated using the measured wave intensities, polarizations, and k directions. The values of lambda(W-P) are found to be similar to5 times less than the value of lambda(He), the latter derived from He intensity and anisotropy time profiles. It is demonstrate by computer simulation that scattering rates through a 90degrees pitch angle are lower than that of other pitch angles, and that this is a possible explanation for the discrepancy between the lambda(W-P) and lambda(He) values. At this time the scattering mechanism(s) is unknown. We suggest a means where a direct comparison between the two lambda values could be made. Computer simulations indicate that although scattering through 90degrees is lower, it still occurs. Possibilities are either large pitch angle scattering through resonant interactions, or particle mirroring off of field compression regions. The largest solar proton events are analyzed to investigate the possibilities of local wave generation at 1 AU. In accordance with the results of a previous calculation (Gary et al., 1985) of beam stability, proton beams at 1 AU are found to be marginally stable. No evidence for substantial wave amplitude was found. Locally generated waves, if present, were less than 10(-3) nT(2) Hz(-1) at the leading proton event edge, 4 where dispersion effects (beaming) are the greatest, and at the point of peak proton flux, where the particle energy flux is the greatest. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Univ Maryland, Dept Phys, College Pk, MD USA. Univ Maryland, Inst Phys Sci & Technol, College Pk, MD USA. Indian Inst Geomagnetism, Colaba, Mumbai Bombay, India. Kyushu Univ, Kasuga, Fukuoka 816, Japan. NOAA, Space Environm Lab, Boulder, CO 80303 USA. RP Tsurutani, BT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. RI Lakhina, Gurbax /C-9295-2012; OI Lakhina, Gurbax /0000-0002-8956-486X NR 85 TC 7 Z9 7 U1 0 U2 1 PU EUROPEAN GEOPHYSICAL SOC PI KATLENBURG-LINDAU PA MAX-PLANCK-STR 13, 37191 KATLENBURG-LINDAU, GERMANY SN 0992-7689 J9 ANN GEOPHYS-GERMANY JI Ann. Geophys. PD APR PY 2002 VL 20 IS 4 BP 427 EP 444 PG 18 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA 556QA UT WOS:000175859400002 ER PT J AU Moller, KD Sternberg, O Grebel, H Stewart, KP AF Moller, KD Sternberg, O Grebel, H Stewart, KP TI Near-field effects in multilayer inductive metal meshes SO APPLIED OPTICS LA English DT Article ID BANDPASS-FILTERS; DIELECTRIC BOUNDARY; GRIDS; THIN AB The transmittance of inductive single-layer and multilayer cross-shaped metal meshes has been calculated with the Micro-Stripes software program. The effect of symmetric and asymmetric alignment of the crosses of one mesh with respect to another was studied and compared with transmission line theory, which presents the nonaligned case. Significant differences are found for small spacing at approximately 1/5 the periodicity constant, whereas the differences disappear for large spacing. A pair of coupled surface waves is used to represent the mode of a single mesh. The resulting modes corresponding to the transmittance of multilayer metal meshes are interpreted by modes composed of resonance modes of a single mesh coupled by Fabry-Perot modes depending on the separation. (C) 2002 Optical Society of America. C1 New Jersey Inst Technol, Dept Phys, Newark, NJ 07102 USA. New Jersey Inst Technol, Elect Imaging Ctr, Newark, NJ 07102 USA. New Jersey Inst Technol, Dept Elect Engn, Newark, NJ 07102 USA. Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Moller, KD (reprint author), New Jersey Inst Technol, Dept Phys, Newark, NJ 07102 USA. NR 17 TC 10 Z9 10 U1 0 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD APR 1 PY 2002 VL 41 IS 10 BP 1942 EP 1948 DI 10.1364/AO.41.001942 PG 7 WC Optics SC Optics GA 538JK UT WOS:000174812200017 PM 11936794 ER PT J AU de Paz, AG Madore, BF AF de Paz, AG Madore, BF TI On the optimization of broadband photometry for galaxy evolution studies SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : evolution; galaxies : photometry; methods : numerical; methods : statistical ID EMISSION-LINE GALAXIES; STAR-FORMATION HISTORY; HUBBLE-DEEP-FIELD; ALPHA EMITTING GALAXIES; DIGITAL SKY SURVEY; UNIVERSIDAD-COMPLUTENSE; STELLAR POPULATIONS; SYNTHESIS MODELS; STARBURST GALAXIES; REDSHIFT GALAXIES AB We have derived the uncertainties to be expected in the derivation of galaxy physical properties (star formation history, age, metallicity, and reddening) when comparing broadband photometry to the predictions of evolutionary synthesis models. We have obtained synthetic colors for a large sample (similar to9000) of artificial galaxies by assuming different star formation histories, ages, metallicities, reddening values, and redshifts. The colors derived have been perturbed by adopting different observing errors and compared against the evolutionary synthesis models grouped in different sets. The comparison has been performed using a combination of Monte Carlo simulations, a maximum likelihood estimator, and principal component analysis. After comparing the input and derived output values we have been able to compute the uncertainties and covariant degeneracies between the galaxy physical properties as a function of (1) the set of observables available, (2) the observing errors, and (3) the galaxy properties themselves. In this work we have considered different sets of observables, some of them including the standard Johnson-Cousins (UBVR(C)I(C)) and Sloan Digital Sky Survey (SDSS) bands in the optical, the Two Micron All-Sky Survey ( 2MASS) bands in the near-infrared, and the Galaxy Evolution Explorer (GALEX) bands in the UV, at three different redshifts, z = 0.0, 0.7, and 1.4. This study is intended to represent a basic tool for the design of future projects on galaxy evolution, allowing an estimate of the optimal bandpass combinations and signal-to-noise ratios required for a given scientific objective. C1 CALTECH, NASA, IPAC Extragalact Database, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Carnegie Inst Astron Observ, Pasadena, CA 91101 USA. RP de Paz, AG (reprint author), CALTECH, NASA, IPAC Extragalact Database, MS 100-22, Pasadena, CA 91125 USA. EM agpaz@ipac.caltech.edu; barry@ipac.caltech.edu OI Gil de Paz, Armando/0000-0001-6150-2854 NR 58 TC 21 Z9 21 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD APR PY 2002 VL 123 IS 4 BP 1864 EP 1880 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 537JX UT WOS:000174756400005 ER PT J AU Laycock, S Corbet, RHD Perrodin, D Coe, MJ Marshall, FE Markwardt, C AF Laycock, S Corbet, RHD Perrodin, D Coe, MJ Marshall, FE Markwardt, C TI Discovery of a new transient X-ray pulsar in the Small Magellanic Cloud SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE galaxies : Magellanic Clouds; stars : binaries : general; stars : pulsars : general; stars : pulsars : individual : XTE-SMC95; X-rays : stars ID BINARY-SYSTEMS; POPULATIONS; SMC AB Systematic Rossi X-Ray Timing Explorer (RXTE) observations of the Small Magellanic Cloud (SMC) have revealed a previously unknown transient X-ray pulsar with a pulse period of 95s. The 95s pulsar, provisionally designated XTE SMC95, was detected in three Proportional Counter Array (PCA) observations during an outburst spanning 4 weeks in March/April 1999. The pulse profile is double peaked reaching a pulse fraction of approximate to0.8. The X-ray spectrum is well represented by an absorbed power-law with a photon index of 1.4 and mean unabsorbed flux of greater than or similar to8.95 x 10(-11) ergs cm(-2) s(-1) (3-25 keV). The source is proposed as a Be/neutron star system on the basis of its pulsations, transient nature and characteristically hard X-ray spectrum. The 2-10 keV X-ray luminosity implied by our observations is greater than or similar to2 x 10(37) ergs s(-1) which is consistent with that of normal outbursts seen in Galactic systems. This discovery adds to the emerging picture of the SMC as containing an extremely dense population of transient high mass X-ray binaries. C1 Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Laycock, S (reprint author), Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. RI Perrodin, Delphine/L-1916-2016 OI Perrodin, Delphine/0000-0002-1806-2483 NR 28 TC 12 Z9 12 U1 0 U2 1 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD APR PY 2002 VL 385 IS 2 BP 464 EP 470 DI 10.1051/0004-6361:20020150 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 538FM UT WOS:000174804600011 ER PT J AU Bearda, H Hartmann, W Ebisawa, K Heise, J Kaastra, J van der Meer, R Verbunt, F Motch, C AF Bearda, H Hartmann, W Ebisawa, K Heise, J Kaastra, J van der Meer, R Verbunt, F Motch, C TI The complex X-ray spectrum of the supersoft source MR Vel SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : atmospheres; binaries : close; line : identification; stars : individual : MR Vel; stars : winds, outflows; X-rays : binaries ID LARGE MAGELLANIC CLOUD; ROSAT; ATMOSPHERES AB We present the X-ray spectrum of MR Vel/RXJ 0925.7-4758, obtained with the Medium Energy Grating spectrometer of the Chandra X-ray Telescope. The simplest models used by earlier authors, stellar atmospheres in combination with a thermal plasma in collisional ionization equilibrium, cannot explain the spectrum. Neither does a photo-ionized plasma. We identify PCygni profiles of Fe XVII and OVIII, from which we conclude that these lines arise in a wind. We conclude that major uncertainty exists about the bolometric luminosity of MR Vel, and perhaps of supersoft sources in general, so that the theoretical prediction that this luminosity derives from steady nuclear burning cannot be verified. C1 Univ Utrecht, Astron Inst, NL-3508 TA Utrecht, Netherlands. SRON, Natl Inst Space Res, NL-3584 CA Utrecht, Netherlands. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Astron Observ, CNRS, UA 1280, F-67000 Strasbourg, France. RP Bearda, H (reprint author), Univ Utrecht, Astron Inst, POB 80000, NL-3508 TA Utrecht, Netherlands. NR 29 TC 18 Z9 18 U1 0 U2 0 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD APR PY 2002 VL 385 IS 2 BP 511 EP 516 DI 10.1051/0004-6361:20020104 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 538FM UT WOS:000174804600016 ER PT J AU Creech-Eakman, MJ Chiang, EI Joung, RMK Blake, GA van Dishoeck, EF AF Creech-Eakman, MJ Chiang, EI Joung, RMK Blake, GA van Dishoeck, EF TI ISO LWS spectra of T Tauri and Herbig AeBe stars SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : pre-main sequence; infrared : stars; line : identification; stars : formation ID YOUNG STELLAR OBJECTS; INTERSTELLAR SILICATE MINERALOGY; CIRCUMSTELLAR DISKS; PHOTODISSOCIATION REGIONS; ENERGY-DISTRIBUTIONS; PROTOPLANETARY DISKS; MOLECULAR CLOUDS; AE/BE STARS; HD 163296; INFRARED-EMISSION AB We present an analysis of ISO-LWS spectra of eight T Tauri and Herbig AeBe young stellar objects. Some of the objects are in the embedded phase of star-formation, whereas others have cleared their environs but are still surrounded by a circumstellar disk. Fine-structure lines of [OI] and [CII] are most likely excited by far-ultraviolet photons in the circumstellar environment rather than high-velocity out flows, based on comparisons of observed line strengths with predictions of photon-dominated and shock chemistry models. A subset of our stars and their ISO spectra are adequately explained by models constructed by Chiang & Goldreich (1997) and Chiang et al. (2001) of isolated, passively heated, flared circumstellar disks. For these sources, the bulk of the LWS flux at wavelengths longward of 55 mum arises from the disk interior which is heated diffusively by reprocessed radiation from the disk surface. At 45 mum, water ice emission bands appear in spectra of two of the coolest stars, and are thought to arise from icy grains irradiated by central starlight in optically thin disk surface layers. C1 CALTECH, Dept Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. Univ Calif Berkeley, Berkeley, CA 94720 USA. Columbia Univ, Dept Astron, New York, NY 10027 USA. Sterrewacht Leiden, NL-2300 RA Leiden, Netherlands. RP Creech-Eakman, MJ (reprint author), CALTECH, Dept Geol & Planetary Sci, MS 150-21, Pasadena, CA 91125 USA. EM mce@huey.jpl.nasa.gov NR 59 TC 25 Z9 25 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD APR PY 2002 VL 385 IS 2 BP 546 EP 562 DI 10.1051/0004-6361:20020157 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 538FM UT WOS:000174804600020 ER PT J AU Viotti, RF Antonelli, LA Corcoran, MF Damineli, A Grandi, P Muller, JM Rebecchi, S Rossi, C Villada, M AF Viotti, RF Antonelli, LA Corcoran, MF Damineli, A Grandi, P Muller, JM Rebecchi, S Rossi, C Villada, M TI BeppoSAX broad X-ray range observations of eta Carinae during high and low spectroscopic states SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : binaries : spectroscopic; stars : emission-line, Be; stars : individual : eta Car; stars : mass loss; X-rays : stars ID BINARY; VARIABILITY; ULTRAVIOLET; SPECTRUM; EMISSION; EVENT; STAR AB We present BeppoSAX spectra of the extremely luminous and massive object eta Car observed in a very broad X-ray range (0.1-200 keV) during high state (December 1996) and egress from the last low state (March 1998). Both spectra are composed of at least two components, a soft one with kT(s) < 0:7 keV,and a hard with kT(h) = 4:7 keV. We found in March 1998 a large flux defect in the 1.5-4 keV range, while the flux remained constant below 1.5 keV and above 5 keV. We attribute this defect to a x3.5 increase of the absorbing matter in front of the hard component, while its temperature and unabsorbed luminosity were nearly the same in the two epochs. In December 1996 the PDS X-ray flux in the 13-20 keV range is larger than the extrapolated hard spectrum, indicating the presence of an even harder additional component, which possibly declined during the March 1998 low state. Conversely, we find that at that time, the flux of the 6.7 keV iron line was 40% stronger. Coordinated optical and NIR spectroscopic observations indicate that in March 1998 eta Car was still in a state of low excitation of the emission line spectrum, with extended P Cygni absorptions. These results indicate that after the X-ray flux minimum, the hard component recovered its high state luminosity more rapidly than the high ionization spectral lines, but in the meantime it was partly occulted by a large amount of absorbing matter placed in front of the source. These results are discussed in the framework of the proposed binary model of eta Car. C1 CNR, Ist Astrofis Spaziale & Fis Cosm, Area Ric Tor Vergata, I-00133 Rome, Italy. Osserv Astron Roma, INAF, I-00040 Rome, Italy. Univ Space Res Assoc, Seabrook, MD 20706 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Sao Paulo, Inst Astron & Geofis, BR-04301904 Sao Paulo, Brazil. Univ Nijmegen Hosp, Dept Radiol, NL-6500 HB Nijmegen, Netherlands. ESA ESRIN, ASI Sci Data Ctr, I-00044 Frascati, Roma, Italy. Univ Roma La Sapienza, Dipartimento Fis, I-00185 Rome, Italy. Univ Nacl Cordoba, Astron Observ, Dept Astron Estelar, RA-5000 Cordoba, Argentina. RP CNR, Ist Astrofis Spaziale & Fis Cosm, Area Ric Tor Vergata, Via Fosso Cavaliere 100, I-00133 Rome, Italy. EM uvspace@ias.rm.cnr.it RI Damineli, Augusto/D-8210-2012; OI Damineli, Augusto/0000-0002-7978-2994; Grandi, Paola/0000-0003-1848-6013 NR 34 TC 16 Z9 16 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD APR PY 2002 VL 385 IS 3 BP 874 EP 883 DI 10.1051/0004-6361:20020048 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 539YT UT WOS:000174901700015 ER PT J AU Klassen, A Bothmer, V Mann, G Reiner, MJ Krucker, S Vourlidas, A Kunow, H AF Klassen, A Bothmer, V Mann, G Reiner, MJ Krucker, S Vourlidas, A Kunow, H TI Solar energetic electron events and coronal shocks SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE Sun : flares; Sun : particle emission; CMEs; Sun : radio radiation; shock waves ID MASS EJECTIONS; WIND SPACECRAFT; RADIO EVIDENCE; BURSTS; ACCELERATION; SIGNATURES; EMISSION; PLASMA; FLARES AB Mildly relativistic electrons appear during the solar energetic particle events. A detailed investigation on the origin of such electrons is presented for four particlular solar events. The mildly relativistic electrons have been detected at energies of 0.25-0.7 MeV by COSTEP/SOHO and below 0.392 MeV by Wind 3-DP experiments. Coronal shocks associated with these electron events are identified from the metric-to-decametric solar type II radio bursts. All selected events were associated with solar activity at western longitudes, so that the magnetic footpoints connecting the spacecraft with the Sun were close to the are/shock/CME site. The associated type II bursts were accompanied by so-called shock accelerated (SA) type III bursts appearing to be emerging from the type II emission site. We found: (1) that all of the 0.25-0.7 MeV electron events were released during or after, but never simultaneously with the onset of type II bursts and CMEs. The time delay between the type II burst onset and the release of the mildly relativistic electrons is in the range of 11.5-45 min; (2) that the mildly relativistic electrons were released rather at the end of SA type III bursts or somewhat later; (3) that the mildly relativistic electrons were released when the associated type II burst and the CME reached a certain height (h similar to 1-4 R-s) above the photosphere. For the four events studied, it is concluded that mildly relativistic electrons at 0.25-0.7 MeV energies measured in the interplanetary medium from solar energetic particle events are accelerated by coronal shock waves, commonly in association with white-light CMEs. C1 Astrophys Inst Potsdam, D-14482 Potsdam, Germany. Univ Kiel, Kiel, Germany. Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. USN, Res Lab, Washington, DC 20375 USA. RP Klassen, A (reprint author), Astrophys Inst Potsdam, Sternwarte 16, D-14482 Potsdam, Germany. RI Vourlidas, Angelos/C-8231-2009 OI Vourlidas, Angelos/0000-0002-8164-5948 NR 34 TC 46 Z9 46 U1 0 U2 1 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD APR PY 2002 VL 385 IS 3 BP 1078 EP 1088 DI 10.1051/0004-6361:20020205 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 539YT UT WOS:000174901700036 ER PT J AU Contreras, CS Desmurs, JF Bujarrabal, V Alcolea, J Colomer, F AF Contreras, CS Desmurs, JF Bujarrabal, V Alcolea, J Colomer, F TI Submilliarcsecond-resolution mapping of the 43 GHz SiO maser emission in the bipolar post-AGB nebula OH231.8+4.2 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE masers; stars : AGB and post-AGB; stars : mass-loss; circumstellar matter; stars : individual : OH231.8+4.2; stars : variables : general ID LATE-TYPE STARS; OH-231.8+4.2 AB We present similar to0.3 milliarcsec-resolution maps of the SiO (v = 2,J = 1-0) maser emission in the bipolar post-AGB nebula OH231.8+4.2 obtained with the Very Long Baseline Array. These observations have provided for the first time the structure and kinematics of the close stellar environment in a proto-Planetary Nebula. Our observations reveal the SiO maser emission arising in several bright spots of less than similar to10(13) cm in size forming a structure elongated in the direction perpendicular to the symmetry axis of the nebula. Such a distribution is consistent with an equatorial torus with a radius of similar to6 AU around the central star. A complex velocity gradient is found along the torus, which suggests rotation and infall of material towards the star. The rotation and infalling velocities deduced are of the same order and range between similar to7 and similar to10 km s(-1). From our data, we estimate the mass of the SiO torus and the central star, as well as a stringent upper limit to the present stellar mass-loss rate. C1 Observ Astron Nacl, Alcala De Henares 28800, Spain. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Contreras, CS (reprint author), Observ Astron Nacl, Apdo 1143, Alcala De Henares 28800, Spain. RI Sanchez-Contreras, Carmen/N-3718-2015 OI Sanchez-Contreras, Carmen/0000-0002-6341-592X NR 17 TC 25 Z9 25 U1 0 U2 0 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD APR PY 2002 VL 385 IS 1 BP L1 EP L4 DI 10.1051/0004-6361:20020233 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 535BW UT WOS:000174626200001 ER PT J AU Edelson, R Turner, TJ Pounds, K Vaughan, S Markowitz, A Marshall, H Dobbie, P Warwick, R AF Edelson, R Turner, TJ Pounds, K Vaughan, S Markowitz, A Marshall, H Dobbie, P Warwick, R TI X-ray spectral variability and rapid variability of the soft X-ray spectrum Seyfert 1 galaxies Arakelian 564 and Ton S180 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (Arakelian 564, Ton S180); galaxies : Seyfert; X-rays : galaxies ID POWER-DENSITY SPECTRUM; ACTIVE GALACTIC NUCLEI; IMAGING SPECTROMETER; ASCA OBSERVATIONS; TON S180; NGC 3516; SPECTROSCOPY; RXTE; REVERBERATION; CHANDRA AB The bright, soft X-ray spectrum Seyfert 1 galaxies Ark 564 and Ton S180 were monitored for 35 days and 12 days, respectively, with ASCA and RXTE (and EUVE for Ton S180). These represent the most intensive X-ray monitoring of any such soft-spectrum Seyfert 1 to date. Light curves were constructed for Ton S180 in six bands spanning 0.1-10 keV and for Ark 564 in five bands spanning 0.7-10 keV. The short-timescale ( hours days) variability patterns were very similar across energy bands, with no evidence of lags between any of the energy bands studied. The fractional variability amplitude was almost independent of energy band, unlike hard-spectrum Seyfert 1 galaxies, which show stronger variations in the softer bands. It is difficult to simultaneously explain soft Seyfert galaxies stronger variability, softer spectra, and weaker energy dependence of the variability relative to hard Seyfert galaxies. There was a trend for soft- and hard-band light curves of both objects to diverge on the longest timescales probed (similar toweeks), with the hardness ratio showing a secular change throughout the observations. This is consistent with the fluctuation power density spectra that showed relatively greater power on long timescales in the softest bands. The simplest explanation of all of these is that two continuum emission components are visible in the X-rays: a relatively hard, rapidly variable component that dominates the total spectrum and a slowly variable soft excess that only shows up in the lowest energy channels of ASCA. Although it would be natural to identify the latter component with an accretion disk and the former with a corona surrounding it, a standard thin disk could not get hot enough to radiate significantly in the ASCA band, and the observed variability timescales are much too short. It also appears that the hard component may have a more complex shape than a pure power law. The most rapid factor of 2 flares and dips occurred within similar to1000 s, in Ark 564 and a bit more slowly in Ton S180. The speed of the luminosity changes rules out viscous or thermal processes and limits the size of the individual emission regions to less than or similar to15 Schwarzschild radii (and probably much less), that is, to either the inner disk or small regions in a corona. C1 Univ Calif Los Angeles, Dept Astron, Los Angeles, CA 90095 USA. Univ Leicester, Xray Astron Grp, Leicester LE1 7RH, Leics, England. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA. Inst Astron, Cambridge CB3 0HA, England. MIT, Ctr Space Res, Cambridge, MA 02139 USA. RP Edelson, R (reprint author), Univ Calif Los Angeles, Dept Astron, Los Angeles, CA 90095 USA. EM rae@astro.ucla.edu NR 51 TC 182 Z9 184 U1 1 U2 4 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 1 PY 2002 VL 568 IS 2 BP 610 EP 626 DI 10.1086/323779 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 535BQ UT WOS:000174625700014 ER PT J AU Strickland, DK Heckman, TM Weaver, KA Hoopes, CG Dahlem, M AF Strickland, DK Heckman, TM Weaver, KA Hoopes, CG Dahlem, M TI Chandra observations of NGC 253. II. On the origin of diffuse X-ray emission in the halos of starburst galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : halos; galaxies : individual (NGC 253); galaxies : starburst; ISM : bubbles; ISM : jets and outflows; X-rays : galaxies ID SCULPTOR GROUP GALAXIES; H-ALPHA EMISSION; HUBBLE-SPACE-TELESCOPE; IONIZED-GAS; GALACTIC SUPERWINDS; SPIRAL GALAXIES; MAGNETIC-FIELD; DISK GALAXIES; HOT-GAS; NGC-253 AB We present a detailed case study of the diffuse X-ray and Halpha emission in the halo of NGC 253, a nearby edge-on starburst galaxy driving a galactic superwind. The arcsecond spatial resolution of the ACIS imaging spectroscope on the Chandra X-Ray Observatory allows us to study the spatial and spectral properties of the diffuse X-ray emitting plasma, at a height of between 3 and 9 kpc above the disk in the northern halo of NGC 253, with greatly superior spatial and spectral resolution compared to previous X-ray instruments. We find statistically significant structure within the diffuse emission on angular scales down to similar to10" (similar to130 pc) and place limits on the luminosity of any X-ray emitting "clouds" on smaller scales. There is no statistically significant evidence for any spatial variation in the spectral properties of the diffuse emission over scales from similar to400 pc to similar to3 kpc. The spectrum of the diffuse X-ray emission is clearly thermal, although with the higher spectral resolution and sensitivity of Chandra it is clear that current simple spectral models do not provide a physically meaningful description of the spectrum. In particular, the fitted metal abundances are unphysically low. There is no convincing evidence for diffuse X-ray emission at energies above 2 keV in the halo. We show that the X-shaped soft X-ray morphology of the superwind previously revealed by ROSAT is matched by very similar X-shaped Halpha emission, extending at least 8 kpc above the plane of the galaxy. In the northern halo the X-ray emission appears to lie slightly interior to the boundary marked by the Halpha emission. The total 0.3-2.0 keV energy band X-ray luminosity of the northern halo, L-X 5 x 10(38) ergs s(-1), is very similar to the halo Halpha luminosity of L-Halpha similar to4 x 10(38) ergs s(-1), both of which are a small fraction of the estimated wind energy injection rate of similar to10(42) ergs s(-1) from supernovae in the starburst. We show that there are a variety of models that can simultaneously explain spatially correlated X-ray and H emission in the halos of starburst galaxies, although the physical origin of the various emission components can be very different in different models. These findings indicate that the physical origin of the X-ray emitting million-degree plasma in super-winds is closely linked to the presence of much cooler and denser T similar to 10(4) K gas, not only within the central kiloparsec regions of starbursts but also on similar to10 kpc scales within the halos of these galaxies. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. European So Observ, Santiago 19, Chile. RP Strickland, DK (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. NR 95 TC 140 Z9 140 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 2002 VL 568 IS 2 BP 689 EP 716 DI 10.1086/338889 PN 1 PG 28 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 535BQ UT WOS:000174625700019 ER PT J AU Wheeler, JC Meier, DL Wilson, JR AF Wheeler, JC Meier, DL Wilson, JR TI Asymmetric supernovae from magnetocentrifugal jets SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; ISM : jets and outflows; pulsars : general; supernovae : general ID GAMMA-RAY BURSTS; 25 APRIL 1998; ACCRETION DISKS; CORE-COLLAPSE; STELLAR COLLAPSE; NEUTRON-STARS; BLACK-HOLES; GRB 970228; R-PROCESS; EXPLOSIONS AB Strong toroidal magnetic fields generated in stellar collapse can generate magnetocentrifugal jets in analogy to those found in simulations of black hole accretion. Magnetocentrifugal jets may explain why all core collapse supernovae are found to be substantially asymmetric and predominantly bipolar. We describe two phases: the initial LeBlanc-Wilson jet and a subsequent protopulsar or toroidal jet that propagates at about the core escape velocity. The prompt LeBlanc-Wilson jets will produce an excess of neutron-rich matter and hence cannot be the common origin of supernova explosions; similar but less severe problems arise with the protopulsar jet that may be alleviated by partial evacuation along the axis by rotation. The jets will produce bow shocks that tend to expel matter, including iron and silicon, into equatorial tori. This may help to account for observations of the element distribution in Cas A. A magnetic switch mechanism may apply in rare instances ( when there is low density and large magnetic field), with subsequent increase in the speed and collimation of the toroidal jet. The conditions that turn the magnetic switch on would yield a jet that propagates rapidly and with small opening angle through the star, depositing relatively little momentum. The result could be enough infall to form a black hole. A third, highly relativistic jet from the rotating black hole could catch up to the protopulsar jet after it has emerged from the star. The interaction of these two jets plausibly could be the origin of the internal shocks thought to produce gamma-ray bursts and could explain the presence of iron lines in the afterglow. Recent estimates that typical gamma-ray burst energy is similar to3 x 10(50) ergs imply either a very low efficiency for conversion of rotation into jets by the Blandford-Znajek mechanism or a rather rapid turnoff of the jet process even though the black hole still rotates rapidly. Magnetars and hypernovae might arise in an intermediate parameter regime of energetic jets that yield larger magnetic fields and provide more energy than the routine case, but that are not so tightly collimated that they yield failed supernova. C1 Univ Texas, Dept Astron, Austin, TX 78712 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Lawrence Livermore Natl Lab, Livermore, CA 94551 USA. RP Wheeler, JC (reprint author), Univ Texas, Dept Astron, RLM 15308, Austin, TX 78712 USA. EM wheel@astro.as.utexas.edu; dlm@sgra.jpl.nasa.gov; wilson@ricker.llnl.gov NR 81 TC 108 Z9 109 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 APR 1 PY 2002 VL 568 IS 2 BP 807 EP 819 DI 10.1086/338953 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 535BQ UT WOS:000174625700029 ER PT J AU Harding, AK Muslimov, AG AF Harding, AK Muslimov, AG TI Pulsar polar cap heating and surface thermal X-ray emission. II. Inverse Compton radiation pair fronts SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : general; radiation mechanisms : nonthermal; relativity; stars : neutron; X-rays : stars ID STRONG MAGNETIC-FIELDS; GAMMA-RAY; SCATTERING AB We investigate the production of electron-positron pairs by inverse Compton scattered (ICS) photons above a pulsar polar cap ( PC) and calculate surface heating by returning positrons. This paper is a continuation of our self-consistent treatment of acceleration, pair dynamics, and electric field screening above pulsar PCs. We calculate the altitude of the inverse Compton pair-formation fronts, the flux of returning positrons, and present the heating efficiencies and X-ray luminosities. We revise pulsar death lines implying cessation of pair formation, and present them in surface magnetic field period space. We find that virtually all known radio pulsars are capable of producing pairs by resonant and nonresonant ICS photons radiated by particles accelerated above the PC in a pure star-centered dipole field, so that our ICS pair death line coincides with empirical radio pulsar death. Our calculations show that ICS pairs are able to screen the accelerating electric field only for high PC surface temperatures and magnetic fields. We argue that such screening at ICS pair fronts occurs locally, slowing but not turning off acceleration of particles until screening can occur at a curvature radiation (CR) pair front at higher altitude. In the case where no screening occurs above the PC surface, we anticipate that the pulsar gamma-ray luminosity will be a substantial fraction of its spin-down luminosity. The X-ray luminosity resulting from PC heating by ICS pair fronts is significantly lower than the PC heating luminosity from CR pair fronts, which dominates for most pulsars. PC heating from ICS pair fronts is highest in millisecond pulsars, which cannot produce CR pairs, and may account for observed thermal X-ray components in the spectra of these old pulsars. C1 NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Emergent Informat Technol Inc, Space Sci Sector, Upper Marlboro, MD 20774 USA. RP Harding, AK (reprint author), NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Harding, Alice/D-3160-2012 NR 30 TC 134 Z9 135 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 2002 VL 568 IS 2 BP 862 EP 877 DI 10.1086/338985 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 535BQ UT WOS:000174625700033 ER PT J AU Jennings, DE Deming, D McCabe, G Sada, PV Moran, T AF Jennings, DE Deming, D McCabe, G Sada, PV Moran, T TI Solar magnetic field studies using the 12 micron emission lines. IV. Observations of a Delta region solar flare SO ASTROPHYSICAL JOURNAL LA English DT Article DE line : profiles; magnetic fields; Sun : activity; Sun : flares; Sun : infrared ID MG-I; FEATURES; SUNSPOTS AB We have recently developed the capability to make solar vector ( Stokes IQUV) magnetograms using the infrared line of Mg I at 12.32 mum. On 2001 April 24, we obtained a vector magnetic map of solar active region NOAA 9433, fortuitously just prior to the occurrence of an M2 flare. Examination of a sequence of SOHO / Michaelson Doppler Imager magnetograms and comparison with ground-based Halpha images shows that the are was produced by the cancellation of newly emergent magnetic flux outside of the main sunspot. The very high Zeeman sensitivity of the 12 mum data allowed us to measure field strengths on a spatial scale which was not directly resolvable. At the are trigger site, opposite polarity fields of 2700 and 1000 G occurred within a single 2 00 resolution element, as revealed by two resolved Zeeman splittings in a single spectrum. Our results imply an extremely high horizontal field strength gradient (5 G km(-1)) prior to the are, significantly greater than seen in previous studies. We also find that the magnetic energy of the cancelling fields was more than sufficient to account for the flare's X-ray luminosity. C1 NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Greenbelt, MD 20771 USA. Catholic Univ Amer, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. Univ Monterrey, Dept Fis & Matemat, San Pedro Garza Garcia 66259, NL, Mexico. Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. RP Jennings, DE (reprint author), NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Greenbelt, MD 20771 USA. RI Jennings, Donald/D-7978-2012 NR 17 TC 12 Z9 12 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 2002 VL 568 IS 2 BP 1043 EP 1048 DI 10.1086/339159 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 535BQ UT WOS:000174625700047 ER PT J AU van Noort, M Hubeny, I Lanz, T AF van Noort, M Hubeny, I Lanz, T TI Multidimensional non-LTE radiative transfer. I. A universal two-dimensional short-characteristics scheme for cartesian, spherical, and cylindrical coordinate systems SO ASTROPHYSICAL JOURNAL LA English DT Article DE line : formation; methods : numerical; radiative transfer ID LAMBDA ITERATION METHOD; 2 SPACE DIMENSIONS; MAGNETOHYDRODYNAMICS CODE; ASTROPHYSICAL FLOWS; ACCRETION DISKS; ALGORITHMS; CONTINUUM; ZEUS-2D; TESTS AB We have developed an efficient and robust two-dimensional non-LTE radiation transfer solver appropriate for line transfer in the equivalent two-level atom formalism. The numerical method applies the accelerated lambda iteration technique together with the short-characteristics scheme. The code presented in this paper incorporates all three standard geometries ( Cartesian, cylindrical, and spherical) in a transparent way while allowing for arbitrary ( three-dimensional) velocity fields. The geometry-specific parts of the radiative transfer solver are modularized so that the change of geometry is accomplished by simply setting the appropriate switch. We have also developed a parallel version of the code, in which we use a parallelization in spatial subdomains, and showed that such a scheme is sufficiently robust. We have performed a number of tests of the performance of the solver in all three geometries. Finally, we discuss the internal accuracy of the transfer solutions depending on the number of spatial, angular, and frequency grid points. C1 Univ Sydney, Sch Phys, Sydney, NSW 2006, Australia. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Univ Sydney, Sch Phys, A28, Sydney, NSW 2006, Australia. NR 35 TC 39 Z9 39 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 2002 VL 568 IS 2 BP 1066 EP 1094 DI 10.1086/338949 PN 1 PG 29 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 535BQ UT WOS:000174625700050 ER PT J AU Hudson, RL Moore, MH AF Hudson, RL Moore, MH TI The N-3 radical as a discriminator between ion-irradiated and UV-photolyzed astronomical ices SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : molecules; line : formation; line : identification; molecular processes ID INFRARED SPECTRUM; MATRIX-ISOLATION; ULTRAVIOLET PHOTOLYSIS; INTERSTELLAR; ANALOGS; SURFACE; PLUTO; HYDROCARBONS; SEGREGATION; MIXTURES AB Infrared spectroscopy has been used to show that irradiation of solid N-2 and N-2-rich ices with 0.8 MeV protons produces the N-3 (azide) radical. In contrast, no N-3 was observed after solid N-2 and N-2-rich ices were photolyzed by far-UV photons. Isotopic substitution experiments support the N-3 identification, as does an analysis of the reactions occurring in the ices. This is the first documented difference in reaction products between the radiation chemistry and photochemistry of a nonpolar astronomical ice analog. We suggest that this difference in reaction chemistries could be used to identify ion-irradiated ices on interstellar grains and in the outer solar system. Further, N-3 might be used as a tracer of solid-phase interstellar N-2, which is expected to exist in dark, molecular clouds but is difficult to observe directly. Although the absolute strength of the N-3 band in solid N-2 is unknown, we estimate that it is at least 100 times greater than that of the fundamental vibration of N-2. C1 Eckerd Coll, Dept Chem, St Petersburg, FL 33733 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Hudson, RL (reprint author), Eckerd Coll, Dept Chem, St Petersburg, FL 33733 USA. EM hudsonrl@eckerd.edu; ummhm@lepvax.gsfc.nasa.gov RI Hudson, Reggie/E-2335-2012 NR 37 TC 44 Z9 44 U1 2 U2 9 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 1 PY 2002 VL 568 IS 2 BP 1095 EP 1099 DI 10.1086/339039 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 535BQ UT WOS:000174625700051 ER PT J AU Ciardi, DR van Belle, GT Akeson, RL Thompson, RR Lada, EA Howell, SB AF Ciardi, DR van Belle, GT Akeson, RL Thompson, RR Lada, EA Howell, SB TI On the near-infrared size of Vega (vol 559, pg 1147, 2001) SO ASTROPHYSICAL JOURNAL LA English DT Correction C1 Univ Florida, Dept Astron, Gainesville, FL 32611 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Planetary Sci Inst, Astrophys Grp, Tucson, AZ 85705 USA. RP Ciardi, DR (reprint author), Univ Florida, Dept Astron, 211 Space Sci Bldg, Gainesville, FL 32611 USA. NR 1 TC 0 Z9 0 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 2002 VL 568 IS 2 BP 1101 EP 1101 DI 10.1086/338973 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 535BQ UT WOS:000174625700053 ER PT J AU Ofman, L AF Ofman, L TI Chromospheric leakage of Alfven waves in coronal loops SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; Sun : corona; Sun : magnetic fields; waves ID TRANSITION REGION; OSCILLATIONS; EXPLORER AB The recently observed rapid damping of coronal loop oscillations generated discussion regarding the physical mechanism responsible for the damping, with the leakage into the chromosphere suggested as one of the possible mechanisms. I study the leakage of Alfven waves into the chromospheric footpoints of a coronal loop using the nonlinear viscoresistive 1.5-dimensional MHD model. The waves were launched by an initial transverse velocity profile in the loop. I find that the leakage time of long-wavelength transverse oscillations, such as the ones observed recently by the Transition Region and Coronal Explorer (TRACE), is 5 times longer than the observed damping time of the oscillations. For the loop recently observed by TRACE, I conclude that the observed damping of the long-wavelength oscillations is not due to leakage into the chromosphere. However, depending on particular chromospheric and coronal properties, chromospheric leakage may be significant in some events of coronal loop oscillations. C1 Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Tel Aviv Univ, Dept Geophys, IL-69978 Tel Aviv, Israel. RP Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. EM leon.ofman@gsfc.nasa.gov NR 12 TC 50 Z9 50 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 2002 VL 568 IS 2 BP L135 EP L138 DI 10.1086/340329 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 535BR UT WOS:000174625800016 ER PT J AU Charpinet, S Fontaine, G Brassard, P Dorman, B AF Charpinet, S Fontaine, G Brassard, P Dorman, B TI Adiabatic survey of subdwarf B star oscillations. II. Effects of model parameters on pulsation modes SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE stars : interiors; stars : oscillations; subdwarfs ID EVOLVED STELLAR POPULATIONS; DA WHITE-DWARFS; EC-14026 STARS; ULTRAVIOLET-RADIATION; ELLIPTIC GALAXIES; HOT; OPACITIES; BINARY AB We present additional results obtained from a systematic adiabatic survey of the pulsation properties of extreme horizontal branch models identified with the subdwarf B stars. This survey is aimed at providing the most basic theoretical tools with which to analyze the asteroseismological characteristics of the recently discovered class of pulsating sdB stars ( the EC 14026 stars). In this paper, the second of a series of three, we use an adiabatic pulsation code to compute the low-order, radial and nonradial ( from l = 1 through l = 3) p, f, and g oscillation modes of a large grid of static envelope models of subdwarf B stars in order to explore thoroughly parameter space. We first demonstrate that such static models are sufficiently reliable for computations of the pulsation mode properties in these stars. This step is necessary if we are to understand the effects of various model parameters on the pulsation periods of sdB stars, effects that remain hopelessly tangled in evolutionary models. We show, in particular, that low-order radial and nonradial p-modes obtained from static structures do not experience significant period variations compared to modes computed with evolutionary models. This is not surprising because the acoustic modes probe mainly the envelope and are not sensitive to the details of the deep core, which are, of course, ignored in static models. In contrast, we find that the g-mode periods computed with static models are systematically overestimated, and we provide a detailed explanation of this phenomenon. We note, however, that the qualitative behaviors of the g-mode properties are still very well reproduced with static models. Moreover, because the pulsation periods observed in the vast majority of the known EC 14026 stars can be unambiguously identified with low-order acoustic modes, we conclude that static envelope models are valuable additions to the tools that we have at our disposal for carrying out asteroseismological analyses of these stars. On this basis, and in the light of the results presented in the first paper of this series, we next discuss and interpret the pulsation mode behaviors as functions of the main model parameters: the effective temperature T e, the logarithmic surface gravity log g, the mass of the H-rich envelope M-env, and the total mass of the star M-tot. To achieve this goal, a large grid of 11,200 static envelope models is built and some 1,256, 600 adiabatic modes ( including p-, f-, and g-modes) are computed. The grid covers the whole volume of parameter space where real subdwarf B stars are expected: 22,000 less than or equal to T-eff less than or equal to 41,000 K, 4.9 less than or equal to log g less than or equal to 6.4, 8 x 10(-6) less than or equal to M-env/M-. less than or equal to 8 x 10(-3), and 0.46 less than or equal to M-tot/ M-. less than or equal to 0.50. We find that both p- and g-mode periods are very sensitive to the log g parameter, while only g modes respond significantly to variations of the effective temperature. We stress, however, that mode bumping and avoided crossing phenomena blur somewhat the differences between nonradial acoustic and gravity modes (in effect, these become mixed modes) in the high-T-eff, low-gravity part of the explored log g-T-eff plane. We show that changing the mass of the H-rich envelope has a significant impact, through the trapping and microtrapping effects, on both the g-mode and, more importantly from a practical point of view, the p- mode period spectra. This raises the exciting possibility of using the signature of the M-env parameter on the acoustic mode periods to constrain the H-rich envelope mass of the EC 14026 stars from their observed period spectra. We also find that the M-tot parameter has a slight, although noticeable, impact on the p- and g-mode periods within the narrow mass range considered in this survey. C1 Observ Midi Pyrenees, Astrophys Lab, F-31400 Toulouse, France. Univ Montreal, Dept Phys, Montreal, PQ H3C 3J7, Canada. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Emergent Informat Technol Inc, Greenbelt, MD 20771 USA. RP Charpinet, S (reprint author), Observ Midi Pyrenees, Astrophys Lab, 14 Ave Edouard Belin, F-31400 Toulouse, France. OI Charpinet, Stephane/0000-0002-6018-6180 NR 45 TC 27 Z9 27 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD APR PY 2002 VL 139 IS 2 BP 487 EP 537 DI 10.1086/338822 PG 51 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 533KB UT WOS:000174527600006 ER PT J AU Richardson, GA Chung, TJ AF Richardson, GA Chung, TJ TI Computational relativistic astrophysics using the flow field-dependent variation theory SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE accretion, accretion disks; hydrodynamics; methods : numerical; relativity ID HYDRODYNAMICS; ACCRETION AB We present our method for solving general relativistic nonideal hydrodynamics. Relativistic effects become pronounced in such cases as jet formation from black hole magnetized accretion disks which may lead to the study of gamma-ray bursts. Nonideal flows are present where radiation, magnetic forces, viscosities, and turbulence play an important role. Our concern in this paper is to reexamine existing numerical simulation tools as to the accuracy and efficiency of computations and introduce a new approach known as the flow field dependent variation ( FDV) method. The main feature of the FDV method consists of accommodating discontinuities of shock waves and high gradients of flow variables such as occur in turbulence and unstable motions. In this paper, the physics involved in the solution of relativistic hydrodynamics and solution strategies of the FDV theory are elaborated. The general relativistic astrophysical flow and shock solver (GRAFSS) is introduced, and some simple example problems for computational relativistic astrophysics (CRA) are demonstrated. C1 NASA, George C Marshall Space Flight Ctr, Natl Space Sci & Technol Ctr, Huntsville, AL 35812 USA. Univ Alabama, Dept Mech & Aerosp Engn, Huntsville, AL 35899 USA. RP Richardson, GA (reprint author), Univ Alabama, Ctr Space Plasma & Aeron Res, Huntsville, AL 35899 USA. NR 22 TC 8 Z9 8 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD APR PY 2002 VL 139 IS 2 BP 539 EP 563 DI 10.1086/338508 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 533KB UT WOS:000174527600007 ER PT J AU Serban, R Koon, WS Lo, MW Marsden, JE Petzold, LR Ross, SD Wilson, RS AF Serban, R Koon, WS Lo, MW Marsden, JE Petzold, LR Ross, SD Wilson, RS TI Halo orbit mission correction maneuvers using optimal control SO AUTOMATICA LA English DT Article DE dynamical systems; optimal control; halo orbit transfer; invariant manifolds; three-body problem; space mission design ID DYNAMICAL-SYSTEMS; PERIODIC-ORBITS; SOFTWARE AB This paper addresses the comulation of file required trajectory correction maneuvers for a halo orbit space mission to compensate for the launch velocity errors introduced by inaccuracies of the launch vehicle. By combining dynamical systems theory with optimal control techniques. we are able to provide a compelling portrait of the complex landscape of the trajectory design space. This approach enables automation of the analysis to perform parametric Studies that simply ere not available to mission designers a few years ago, such as hock the magnitude of the errors and the timing of the first trajectory correction maneuver affects the correction DeltaV. The impetus for combining dynamical systems theory and optimal control in this problem arises from design issues for the Genesis Discovery Mission being developed for NASA by the Jet Propulsion Laboratory. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Control & Dynam Syst, Pasadena, CA 91125 USA. Univ Calif Santa Barbara, Dept Mech & Environm Engn, Santa Barbara, CA 93106 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ross, SD (reprint author), CALTECH, Control & Dynam Syst, MC 107-81, Pasadena, CA 91125 USA. EM shane@eds.caltech.edu RI Ross, Shane/B-7237-2009 OI Ross, Shane/0000-0001-5523-2376 NR 19 TC 27 Z9 35 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0005-1098 J9 AUTOMATICA JI Automatica PD APR PY 2002 VL 38 IS 4 BP 571 EP 583 AR PII S0005-1098(01)00279-5 DI 10.1016/S0005-1098(01)00279-5 PG 13 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA 525FK UT WOS:000174058100002 ER PT J AU Polk, JD Rugaber, C Kohn, G Arenstein, R Fallon, WF AF Polk, JD Rugaber, C Kohn, G Arenstein, R Fallon, WF TI Central retinal artery occlusion by proxy: A cause for sudden blindness in an airline passenger SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE surgical complications; aerospace; flight physiology; vision loss; retinal detachment ID INTRAOCULAR GAS; PNEUMATIC RETINOPEXY; AIR-TRAVEL; DETACHMENT; PRESSURE AB The use of gas media in ophthalmologic procedures is relatively commonplace. Scleral buckle and pneumatic retinopexy procedures using air-gas mediums are a widely accepted treatment for retinal detachment, We present a patient who had a scleral buckle with pneumatic retinopexy performed and subsequently flew in a commercial airliner 2 wk later. The patient experienced sudden blindness due to central retinal artery occlusion brought about by expansion of the air bubble when the aircraft reached cruise altitude and a cabin pressure of 8000 ft. The intraocular pressure exceeded the central artery pressure thereby collapsing the artery. The patient's symptoms were relieved when an onboard flight surgeon identified the problem and the cabin pressure was reset to 2000 ft. Flying after an ophthalmic procedure that incorporates intraocular gas may have complications due to the bubble expansion in accordance with Boyle's Law. The ophthalmologic surgeon must be diligent in forewarning patients of the potential complications of flying for weeks to months after a procedure that utilizes intraocular gas. C1 NASA, Lyndon B Johnson Space Ctr, Wyle Life Sci, Houston, TX 77058 USA. RP Polk, JD (reprint author), NASA, Lyndon B Johnson Space Ctr, Wyle Life Sci, 1290 Hercules Dr, Houston, TX 77058 USA. NR 20 TC 9 Z9 9 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 APR PY 2002 VL 73 IS 4 BP 385 EP 387 PG 3 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 536ZR UT WOS:000174732200011 PM 11952061 ER PT J AU Pardo, JR Ridal, M Murtagh, D Cernicharo, J AF Pardo, JR Ridal, M Murtagh, D Cernicharo, J TI Microwave temperature and pressure measurements with the Odin satellite: I. Observational method SO CANADIAN JOURNAL OF PHYSICS LA English DT Article ID LINE; SUBMILLIMETER; STRATOSPHERE; VALIDATION; MILLIMETER; PROFILES; SOUNDER; O-2 AB The Odin satellite is equipped with millimetre and sub-millimetre receivers for observations of several molecular lines in the middle and upper atmosphere of our planet (similar to25-100 km, the particular altitude range depending on the species) for studies in dynamics, chemistry, and energy transfer in these regions. The same receivers are also used to observe molecules in outer space, this being the astrophysical share of the project. Among the atmospheric lines that can be observed, we find two corresponding to molecular oxygen (118.75 GHz and 487.25 GHz). These lines can be used for retrievals of the atmospheric temperature vertical profile. In this paper, we describe the radiative-transfer modeling for O-2 in the middle and upper atmosphere that we will use as a basis for the retrieval algorithms. Two different observation modes have been planned for Odin, the three-channel operational mode and a high-resolution mode. The first one will determine the temperature and pressure on an operational basis using the oxygen line at 118.75 GRz, while the latter can be used for measurements of both O-2 lines, during a small fraction of the total available time for aeronomy, aimed at checking the particular details of the radiative transfer near O-2 lines at very high altitudes (>70 km). The Odin temperature measurements are expected to cover the altitude range similar to30-90 km. C1 CSIC, IEM, E-28006 Madrid, Spain. Observ Paris, LERMA, F-75014 Paris, France. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. CALTECH, George W Downs Lab Phys, Pasadena, CA 91125 USA. Stockholm Univ, Dept Meteorol, S-10691 Stockholm, Sweden. RP Pardo, JR (reprint author), CSIC, IEM, Serrano 121, E-28006 Madrid, Spain. RI Murtagh, Donal/F-8694-2011; OI Murtagh, Donal/0000-0003-1539-3559; Ridal, Martin/0000-0002-2716-1571 NR 28 TC 4 Z9 4 U1 0 U2 1 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA, ONTARIO K1A 0R6, CANADA SN 0008-4204 J9 CAN J PHYS JI Can. J. Phys. PD APR PY 2002 VL 80 IS 4 BP 443 EP 454 DI 10.1139/P01-158 PG 12 WC Physics, Multidisciplinary SC Physics GA 567TF UT WOS:000176500700010 ER PT J AU Ridal, M Murtagh, DP Merino, F Pardo, JR Pagani, L AF Ridal, M Murtagh, DP Merino, F Pardo, JR Pagani, L TI Microwave temperature and pressure measurements with the Odin satellite: II. Retrieval method SO CANADIAN JOURNAL OF PHYSICS LA English DT Article ID MILLIMETER-WAVE-PROPAGATION; SUBMILLIMETER; LINE; VALIDATION; MODEL; O-2; AIR AB The millimetre receiver on the Swedish satellite Odin, will be used for detection of the 118.750 GHz oxygen line. The temperature and pressure will be determined from the output of a three-channel filter bank measurement. One frequency bin is centred over the emission-line frequency while the other two cover parts of the line wing, where the opacity is less, providing a useful signal at lower altitudes. The bandwidth of each channel is 40 MHz. The signal in the frequency bin covering the line centre is modeled by a high-resolution model including the Zeeman effect, developed by the Observatoire de Paris-Meudon. The other two 40 MHz bins are modeled using the much faster standard Odin forward model, developed at the Department of Meteorology at Stockholm University together with Chalmers University of Technology. The operational retrievals employ an iterative method that uses simulated signals from a reference atmosphere as a lookup table for the pressure. The temperature is then calculated from the equation of hydrostatic equilibrium, and a new lookup table computed. This process is repeated until a convergence criterion is reached. Simulations, including known error sources, show that the temperature can be retrieved with a root mean square (rms) around 3 K, in the altitude range similar to25-90 km using the operational temperature retrieval method (the filter bank method). A sub-millimetre receiver on board Odin will also be used to observe the oxygen line at 487.249 GHz. Both this line and the 118.750 GHz line can be observed in high resolution (150 kHz) for detailed studies of the Zeeman splitting. Retrievals from the high-resolution measurements are expected to give a precision of +/-2 K rms at that resolution. However, this kind of observation will occupy an entire spectrometer and will not be made on a regular basis. C1 Stockholm Univ, Dept Meteorol, Svante Arrhenius, SE-10691 Stockholm, Sweden. Observ Paris, DEMIRM, UMR 8540, F-75014 Paris, France. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. CALTECH, George W Downs Lab Phys, Pasadena, CA 91125 USA. Observ Paris, CNRS, DEMIRM, URA 336, F-75014 Paris, France. RP Ridal, M (reprint author), SMHI, SE-60176 Norrkoping, Sweden. RI The Odin satellite, aeronomy mission/F-1671-2011; Murtagh, Donal/F-8694-2011; OI Murtagh, Donal/0000-0003-1539-3559; Ridal, Martin/0000-0002-2716-1571 NR 20 TC 5 Z9 6 U1 0 U2 0 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA, ONTARIO K1A 0R6, CANADA SN 0008-4204 J9 CAN J PHYS JI Can. J. Phys. PD APR PY 2002 VL 80 IS 4 BP 455 EP 467 DI 10.1139/P02-021 PG 13 WC Physics, Multidisciplinary SC Physics GA 567TF UT WOS:000176500700011 ER PT J AU Foschi, PG Pagan, KL AF Foschi, PG Pagan, KL TI Toward a polar stratospheric cloud climatology using advanced very high resolution radiometer thermal infrared data SO CANADIAN JOURNAL OF REMOTE SENSING LA English DT Article ID ANTARCTIC VORTEX; SPLIT-WINDOW; OZONE; AVHRR; RECOVERY; DEPLETION; WINTER; CLAES; HNO3 AB Polar stratospheric clouds (PSCs) play a critical role in ozone depletion over both polar regions. To date, the most complete PSC records consist of measurements from limb-viewing satellites that offer limited spatial and temporal coverage. To construct a more complete and long-term PSC climatology, we investigated the use of advanced very high resolution radiometer (AVHRR) satellite imagery for detecting PSCs. Two approaches were examined: (1) a correlative approach relating image-derived data to verification data, and (2) an interpretation of the image-derived data based on a radiative transfer model. The model determined that Type II or ice PSCs can be detected using the AVHRR thermal infrared channels. The image-derived data, namely density-sliced channel 5 temperature data, color composites, and density-sliced channel 4-5 brightness temperature difference images, provide quick views of potential PSC locations. The model-based approach provides the best method for constructing a long-term ice PSC climatology from the AVHRR archive. C1 San Francisco State Univ, Romberg Tiburon Ctr Environm Studies, Tiburon, CA 94920 USA. San Francisco State Univ, Dept Geosci, NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Foschi, PG (reprint author), San Francisco State Univ, Romberg Tiburon Ctr Environm Studies, 3152 Paradise Dr, Tiburon, CA 94920 USA. NR 35 TC 1 Z9 1 U1 0 U2 4 PU CANADIAN AERONAUTICS SPACE INST PI OTTAWA PA 1685 RUSSELL RD, UNIT 1-R, OTTAWA, ON K1G 0N1, CANADA SN 0703-8992 J9 CAN J REMOTE SENS JI Can. J. Remote Sens. PD APR PY 2002 VL 28 IS 2 BP 187 EP 195 PG 9 WC Remote Sensing SC Remote Sensing GA 550NZ UT WOS:000175510300012 ER PT J AU Chen, B Parker, G Han, J Meyyappan, M Cassell, AM AF Chen, B Parker, G Han, J Meyyappan, M Cassell, AM TI Heterogeneous single-walled carbon nanotube catalyst discovery and optimization SO CHEMISTRY OF MATERIALS LA English DT Article ID GROWTH; MICROARRAYS AB High-throughput methods are utilized in the discovery and optimization of heterogeneous catalyst formulations that promote single-walled carbon nanotube (SWNT) synthesis. Catalyst compositions, substrates, and reaction conditions are varied to efficiently investigate SWNT growth by chemical vapor deposition (CVD). A robotic microarray printer is employed to print libraries of the liquid-based catalyst precursors onto various substrates. After CVD, the catalyst arrays are qualitatively screened for yield via electron microscopy. More comprehensive characterization of candidate catalysts is further investigated with confocal Raman spectroscopy (CRS). Detailed CRS mapping reveals information concerning the printed catalyst and nanotube homogeneity in the microarrays. This powerful characterization approach allows for the high-throughput screening of nanotube type, diameter distribution, and purity within the microarrays. The methodology described has enabled the efficient exploration of synthesis parameters, which has led to the identification of SWNT catalysts with various activities. C1 NASA, Ames Res Ctr, Ctr Nanotechnol, Moffett Field, CA 94035 USA. RP Cassell, AM (reprint author), NASA, Ames Res Ctr, Ctr Nanotechnol, M-S 229-1,Moffet Field, Moffett Field, CA 94035 USA. NR 31 TC 40 Z9 41 U1 4 U2 74 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0897-4756 J9 CHEM MATER JI Chem. Mat. PD APR PY 2002 VL 14 IS 4 BP 1891 EP 1896 DI 10.1021/cm0116828 PG 6 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 542DR UT WOS:000175028700065 ER PT J AU Kabir, HRH AF Kabir, HRH TI Application of linear shallow shell theory of Reissner to frequency response of thin cylindrical panels with arbitrary lamination SO COMPOSITE STRUCTURES LA English DT Article DE analytical solutions; thin cylindrical shells; arbitrary lamination ID PLATE BENDING ELEMENT; MODERATELY-THICK; VIBRATION AB A free vibration response of arbitrarily laminated - crafted with advanced fiber reinforced composite materials - thin and shallow cylindrical panels on rectangular planform with simply supported boundary conditions is analytically investigated. The thin shallow shell formulation of Reissner that follows the classical Kirchhoff-Love hypothesis of small displacements is considered to include arbitrarily laminated behaviors. The simply supported boundary condition having normal, tangential, and transverse displacements restrained at the edges is implemented. The solution functions in a form of mixed boundary continuous and discontinuous double Fourier series are assumed into the analytical solution formulation. The efficiency and accuracy of the solution methodology are determined by studying numerically the convergence behavior of frequencies for various parametric effects. The analytically obtained numerical results and mode shapes are compared with available finite element solutions, and the analytical results can be capitalized as base-line solutions for future comparisons. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 NASA, United Space Alliance, USA Solid Rocket Booster Element, Kennedy Space Ctr, FL 32899 USA. RP Kabir, HRH (reprint author), NASA, United Space Alliance, USA Solid Rocket Booster Element, Kennedy Space Ctr, FL 32899 USA. NR 28 TC 4 Z9 4 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0263-8223 J9 COMPOS STRUCT JI Compos. Struct. PD APR PY 2002 VL 56 IS 1 BP 35 EP 52 AR PII S0263-8223(01)00184-2 DI 10.1016/S0263-8223(01)00184-2 PG 18 WC Materials Science, Composites SC Materials Science GA 534MR UT WOS:000174590600005 ER PT J AU Kang, KS Kwak, DY AF Kang, KS Kwak, DY TI Covolume method for new nonconforming rectangle element for the Stokes problem SO COMPUTERS & MATHEMATICS WITH APPLICATIONS LA English DT Article DE Stokes problems; covolume method; nonconforming mixed finite element method; hybrid domain decomposition method AB We analyze a covolume method based on the new nonconforming element introduced by Douglas et al. [1]. We show the H-1 optimal order convergence of the scheme for Stokes problem and study the hybrid domain decomposition procedure for this covolume scheme. The numerical experiment shows that the covolume scheme is somewhat better than finite element scheme in the computation of pressure. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Korea Adv Inst Sci & Technol, Taejon 305701, South Korea. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Korea Adv Inst Sci & Technol, Dept Math, Taejon 305701, South Korea. RP Kang, KS (reprint author), Korea Adv Inst Sci & Technol, Taejon 305701, South Korea. RI Kwak, Do young/C-1912-2011 NR 13 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 APR-MAY PY 2002 VL 43 IS 8-9 BP 1063 EP 1078 AR PII S0898-1221(01)00345-5 PG 16 WC Mathematics, Applied SC Mathematics GA 541FV UT WOS:000174975300012 ER PT J AU Barlow, RG Aiken, J Holligan, PM Cummings, DG Maritorena, S Hooker, S AF Barlow, RG Aiken, J Holligan, PM Cummings, DG Maritorena, S Hooker, S TI Phytoplankton pigment and absorption characteristics along meridional transects in the Atlantic Ocean SO DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS LA English DT Article DE phytoplankton; pigments; absorption; Atlantic Ocean; transects ID PHOTOSYNTHETICALLY ACTIVE PIGMENTS; BASIN-SCALE VARIABILITY; NORTH-ATLANTIC; BIOOPTICAL CHARACTERISTICS; COMMUNITY STRUCTURE; NATURAL PHYTOPLANKTON; SPECTRAL ABSORPTION; EQUATORIAL PACIFIC; CHLOROPHYLL-A; SARGASSO-SEA AB Pigment patterns and associated absorption properties of phytoplankton were investigated in the euphotic zone along two meridional transects in the Atlantic Ocean, between the UK and the Falkland Islands, and between South Africa and the UK. Total chlorophyll a (TChla = MVChla + DVChla + chlorophyllide a) concentrations and the biomarker pigments for diatoms (fucoxanthin), nanoflagellates and cyanobacteria (zeaxanthin) appeared to have similar distribution patterns in the spring and in the autumn in the temperate NE Atlantic and the northern oligotrophic gyre. Divinyl chlorophyll a levels (prochlorophytes) were greater in spring at the deep chlorophyll maximum in the oligotrophic gyre, however, Marked seasonal differences were observed in the NW African upwelling region. TChla concentrations were twice as high in the upper mixed layer in the spring, with the community dominated by diatoms and prymnesiophytes (19'-hexanoyloxyfucoxanthin). A layered structure was prevalent in the autumn where cyanobacteria, diatoms and prymnesiophytes were located in the upper water column and diatoms and mixed nanoflagellates at the sub-surface maximum. In the South Atlantic, the Benguela upwelling ecosystem and the Brazil-Falklands Current Confluence Zone (BFCCZ) were the most productive regions with the TChla levels being twice as high in the Benguela. Diatoms dominated the Benguela system, while nanoflagellates were the most ubiquitous group in the BFCCZ. Pigment concentrations were greater along the eastern boundary of the southern oligotrophic gyre and distributed at shallower depths. Deep chlorophyll maxima were a feature of the western boundary oligotrophic waters, and cyanobacteria tended to dominate the upper water column along both transects with a mixed group of nanoflagellates at the chlorophyll maximum. Absorption coefficients were estimated from spectra reconstructed from pigment data. Although absorption was greater in the productive areas, the TChla-specific coefficients were higher in oligotrophic regions. In communities that were dominated by diatoms or nanoflagellates, pigment absorption was generally uniform with depth and attenuating irradiance, with TChla being the major absorbing pigment at 440 nm and photosynthetic carotenoids (PSC) at 490 nm. Absorption by chlorophyll c and photoprotective carotenoids (PPC) was much lower. Populations where cyanobacteria were prevalent were characterized by high PPC absorption, particularly at 490 nm, throughout most of the euphotic zone. The data suggested that the effect of pigments on the variability of phytoplankton absorption was due primarily to the variations in absorption by PPC. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 Plymouth Marine Lab, Plymouth PL1 3DH, Devon, England. Southampton Oceanog Ctr, Southampton SO14 3ZH, Hants, England. Univ Calif Santa Barbara, ICESS, Santa Barbara, CA 93106 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Marine & Coastal Management, ZA-8012 Rogge Bay, Cape Town, South Africa. RP Barlow, RG (reprint author), Marine & Coastal Management, Private Bag X2, ZA-8012 Rogge Bay, Cape Town, South Africa. RI Hooker, Stanford/E-2162-2012 NR 41 TC 46 Z9 46 U1 4 U2 20 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0967-0637 J9 DEEP-SEA RES PT I JI Deep-Sea Res. Part I-Oceanogr. Res. Pap. PD APR PY 2002 VL 49 IS 4 BP 637 EP 660 AR PII S0967-0637(01)00081-4 DI 10.1016/S0967-0637(01)00081-4 PG 24 WC Oceanography SC Oceanography GA 539KA UT WOS:000174868000002 ER PT J AU Minello, TJ Rozas, LP AF Minello, TJ Rozas, LP TI Nekton in Gulf Coast wetlands: Fine-scale distributions, landscape patterns, and restoration implications SO ECOLOGICAL APPLICATIONS LA English DT Article DE blue crabs; density models; edge marsh; Gulf Coast wetlands; habitat fragmentation; landscape patterns; nekton populations; restoration; salt marsh; shrimp; Spartina alterniflora; tidal creeks ID SALT-MARSH; DECAPOD CRUSTACEANS; GALVESTON BAY; NATANT MACROFAUNA; SEAGRASS HABITAT; PENAEUS-AZTECUS; BROWN SHRIMP; TEXAS USA; LAND LOSS; FISH AB Many decapod crustaceans and fishes are common inhabitants of flooded salt marshes in the northwestern Gulf of Mexico, but spatial distributions are uneven, and population sizes are difficult to estimate. We measured fine-scale (1-10 m) distributions of nekton on the vegetated marsh surface using enclosure samplers in Galveston Bay, Texas, and used these patterns to estimate population size. Natant decapod crustaceans were abundant in the marsh; densities of juvenile brown shrimp Farfantepenaeus aztecus, white shrimp Litopenaeus setiferus, and blue crabs Callinectes sapidus were highest 1 m from the water's edge and declined rapidly to 10 m from the edge. We developed regression models to describe these fine-scale density patterns and validated the models with independent data on density distributions from two other marsh systems. We used a Geographic Information System to transfer the density models to a natural marsh landscape; the highly fragmented Elmgrove Point marsh was composed of shallow nonvegetated bottom (37.4% of the area) and Spartina alterniflora vegetation (62.6%) with similar to 15 % of the vegetated area within 1 m of the marsh-water interface. We estimated that this 437-ha salt marsh complex supported populations of 16.2 million brown shrimp, 15.5 million white shrimp, and 11.3 million blue crabs. We divided the marsh complex into 39 sectors and examined relationships between nekton populations and landscape-scale patterns of marsh fragmentation. The amount of edge and the population estimates in a sector increased consistently with the amount of water up to similar to20-25%. Nekton population declines were not apparent until the late stages of marsh disintegration (>70% open water). We also used our fine-scale density models to simulate the effects of adding creeks to a 1-ha created salt marsh of solid vegetation. For shrimp, 1-2 creeks/ha (or a comparable amount of edge) were required to reach populations equivalent to shallow nonvegetated bottom, and up to 6 creeks/ha were required to reach populations similar to those estimated for the natural marsh complex. Simulated populations of blue crabs reached levels in the natural marsh complex with the addition of fewer creeks (2-3 creeks/ha). C1 SE Fisheries Sci Ctr, Natl Marine Fisheries Serv, NOAA, Galveston Lab,Fishery Ecol Branch, Galveston, TX 77551 USA. RP Minello, TJ (reprint author), SE Fisheries Sci Ctr, Natl Marine Fisheries Serv, NOAA, Galveston Lab,Fishery Ecol Branch, Galveston, TX 77551 USA. EM tom.minello@noaa.gov NR 68 TC 54 Z9 57 U1 4 U2 26 PU ECOLOGICAL SOC AMER PI WASHINGTON PA 1990 M STREET NW, STE 700, WASHINGTON, DC 20036 USA SN 1051-0761 J9 ECOL APPL JI Ecol. Appl. PD APR PY 2002 VL 12 IS 2 BP 441 EP 455 PG 15 WC Ecology; Environmental Sciences SC Environmental Sciences & Ecology GA 532EC UT WOS:000174457800012 ER PT J AU Goldberg, R Phelan, B Pereira, J Hagan, S Clark, P Bejda, A Calabrese, A Studholme, A Able, KW AF Goldberg, R Phelan, B Pereira, J Hagan, S Clark, P Bejda, A Calabrese, A Studholme, A Able, KW TI Variability in habitat use by young-of-the-year winter flounder, Pseudopleuronectes americanus, in three northeastern US estuaries SO ESTUARIES LA English DT Article ID JUVENILE FISHES; WAQUOIT BAY; SPECIES COMPOSITION; SEAGRASS MEADOWS; SPATIAL SCALE; HUDSON RIVER; GROWTH-RATES; MARSH CREEKS; BARE SAND; MASSACHUSETTS AB We compared distribution and abundance by habitat for age-0, young-of-the-year (YOY) winter flounder, Pseudopleuronectes americanus, in three estuaries (Hammonasset River, Navesink River, and Great Bay-Little Egg Harbor) in the northeastern United States to better define essential fish habitat (EFH). Two replicates of five representative habitats were sampled in most estuaries: eelgrass (Zostera marina), unvegetated areas adjacent to eelgrass, macroalgae, (primarily Ulva lactuca), unvegetated areas adjacent to macroalgae, and tidal marsh creeks. Fish were sampled every two weeks, May through October 1995 and 1996, with a beam-trawl (1-m width, 3-mm mesh net). Abundance of YOY winter flounder was highest in the Navesink River estuary and similar between years, but was significantly lower and differed between years in the Great Bay-Little Egg Harbor and Hammonasset River estuaries. Annual temperature differences appear to influence estuary use by YOY. In the years and estuaries studied, where habitat-related differences in abundance were significant, YOY were found in higher densities in unvegetated areas adjacent to eelgrass. The exception was in the Hammonasset River in 1995 when densities were higher in eelgrass. We conclude that the type of habitat most important to YOY winter flounder varies among estuaries and as a result, care should be taken in defining EFH, based only on limited spatial and temporal sampling. C1 NOAA, Natl Marine Fisheries Serv, NE Fisheries Sci Ctr, Milford Lab, Milford, CT 06460 USA. NOAA, Natl Marine Fisheries Serv, NE Fisheries Sci Ctr, James J Howard Marine Sci Lab, Highlands, NJ 07732 USA. Rutgers State Univ, Inst Marine & Coastal Studies, Marine Field Stn, Tuckerton, NJ 08087 USA. RP Goldberg, R (reprint author), NOAA, Natl Marine Fisheries Serv, NE Fisheries Sci Ctr, Milford Lab, 212 Rogers Ave, Milford, CT 06460 USA. NR 58 TC 30 Z9 30 U1 0 U2 4 PU ESTUARINE RES FEDERATION PI LAWRENCE PA PO BOX 368, LAWRENCE, KS 66044 USA SN 0160-8347 J9 ESTUARIES JI Estuaries PD APR PY 2002 VL 25 IS 2 BP 215 EP 226 DI 10.1007/BF02691309 PG 12 WC Environmental Sciences; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 554UA UT WOS:000175754500006 ER PT J AU Else, P Haldorson, L Krieger, K AF Else, P Haldorson, L Krieger, K TI Shortspine thornyhead (Sebastolobus alascanus) abundance and habitat associations in the Gulf of Alaska SO FISHERY BULLETIN LA English DT Article ID ROCKFISH SEBASTES; DEEP-REEF; FISHES; OREGON AB Shortspine thornyhead (Sebastolobus alascanus) abundance was estimated from 107 video transects at 27 stations recorded from a research submersible in 1991 off southeast Alaska at depths ranging from 165 to 355 m. Numbers of invertebrates in seven major taxa were estimated, as was substrate type. Thornyhead abundance ranged from 0 to 7.5/100 m(2), with a mean of 1.22/100 m(2), and was positively correlated with depth and amount of hard substrate. Invertebrate abundances were not significantly correlated with numbers of thornyheads, Shortspine thornyhead abundance estimates from this study were several times higher than estimates produced by bottom trawl surveys off southeast Alaska in 1990 and 1993, the two years of survey that encompassed the submersible transects; however, the trend of increasing abundance with depth was similar in the trawl surveys and in the submersible transects, suggesting that trawl surveys systematically underestimate abundance of shortspine thornyheads. C1 Univ Alaska, Sch Fisheries & Ocean Sci, Juneau, AK 99801 USA. Natl Marine Fisheries Serv, Auke Bay Lab, Juneau, AK 99802 USA. RP Haldorson, L (reprint author), Univ Alaska, Sch Fisheries & Ocean Sci, 11120 Glacier Highway, Juneau, AK 99801 USA. NR 18 TC 9 Z9 9 U1 0 U2 1 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 USA SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD APR PY 2002 VL 100 IS 2 BP 193 EP 199 PG 7 WC Fisheries SC Fisheries GA 545PR UT WOS:000175226800004 ER PT J AU Garrett, ES AF Garrett, ES TI The "shrouded threat" of foodborne parasites SO FOOD TECHNOLOGY LA English DT Editorial Material C1 US Dept Commerce, Natl Ocean & Atmospher Adm, Natl Marine Fisheries Serv, Pascagoula, MS USA. RP Garrett, ES (reprint author), US Dept Commerce, Natl Ocean & Atmospher Adm, Natl Marine Fisheries Serv, Pascagoula, MS USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU INST FOOD TECHNOLOGISTS PI CHICAGO PA 525 WEST VAN BUREN, STE 1000, CHICAGO, IL 60607-3814 USA SN 0015-6639 J9 FOOD TECHNOL-CHICAGO JI Food Technol. PD APR PY 2002 VL 56 IS 4 BP 20 EP 20 PG 1 WC Food Science & Technology SC Food Science & Technology GA 541EC UT WOS:000174971400007 ER PT J AU Magilligan, FJ Gomez, B Mertes, LAK Smith, LC Smith, ND Finnegan, D Garvin, JB AF Magilligan, FJ Gomez, B Mertes, LAK Smith, LC Smith, ND Finnegan, D Garvin, JB TI Geomorphic effectiveness, sandur development, and the pattern of landscape response during jokulhlaups: Skeioararsandur, southeastern Iceland SO GEOMORPHOLOGY LA English DT Article DE floods; Jokulhlaups; facies models; outwash; sediment ID GJALP SUBGLACIAL ERUPTION; LAURENTIDE ICE-SHEET; SOUTHERN ICELAND; DEPOSITS; SEDIMENT; GLACIER; VATNAJOKULL; FLOOD; PALEOHYDROLOGY; GRIMSVOTN AB By contrast with other historical outburst floods on Skeioardrsandur, the 1996 jokulhlaup was unprecedented in its magnitude and duration, attaining a peak discharge of similar to 53,000 m(3),/s in <17 h. Using a combination of field sampling and remote sensing techniques (Landsat TM, SAR interferometry, airphotos, and laser altimetry), we document the sandur-wide geomorphic impacts of this event, These impacts varied widely across the Skeioararsandur and cannot be singularly attributed to jokulhlaup magnitude because pre-jokulhlaup glacial dynamics and the extant setting largely conditioned the spatial pattern, type, and magnitude of these impacts, Topographic lowering and asymmetric retreat of the ice front during the late twentieth century has decoupled the ice sheet from the moraine/sandur complex along the central and western sandur. This glacial control, in combination with the convex topography of the proximal sandur. promoted a shift from a primarily diffuse-source braided outwash system to a more point-sourced, channelized discharge of water and sediment. Deposition dominated within the proglacial depression, with approximately 3.8* 107 m(3) of sediment, and along channel systems that remained connected to subglacial sediment supplies. This shift to a laterally dissimilar, channelized routing system creates a more varied depositional pattem that is not explicitly controlled by the concave longitudinal profile down-sandur. Laterally contiguous units, therefore, may vary greatly in age and sediment character, suggesting that current facies models inadequately characterize sediment transfers when the ice front is decoupled from its sandur. Water was routed onto the sandur in a highly organized fashion; and this jokulhlaup generated major geomorphic changes, including sandur incision in normally aggradational distal settings and eradication of proximal glacial landforms dating to similar toA.D. 1892. (C) 2002 Elsevier Science B.V. All rights reserved. C1 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 Calif Los Angeles, Dept Geog, Los Angeles, CA 90095 USA. Univ Nebraska, Dept Geosci, Lincoln, NE 68508 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Magilligan, FJ (reprint author), Dartmouth Coll, Dept Geog, 6017 Fairchild, Hanover, NH 03755 USA. EM Magilligan@dartmouth.edu RI Smith, Laurence/E-7785-2012; Last, First/A-6350-2013 OI Smith, Laurence/0000-0001-6866-5904; NR 59 TC 47 Z9 47 U1 3 U2 16 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-555X J9 GEOMORPHOLOGY JI Geomorphology PD APR 1 PY 2002 VL 44 IS 1-2 BP 95 EP 113 AR PII S0169-555X(01)00147-7 DI 10.1016/S0169-555X(01)00147-7 PG 19 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA 544MV UT WOS:000175164900005 ER PT J AU Arrigo, KR van Dijken, GL Ainley, DG Fahnestock, MA Markus, T AF Arrigo, KR van Dijken, GL Ainley, DG Fahnestock, MA Markus, T TI Ecological impact of a large Antarctic iceberg SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ROSS-SEA; ICE-SHEET; PHAEOCYSTIS; PENINSULA; DYNAMICS; RETREAT; SHELVES; FUTURE AB [1] Satellite imagery has been used to document for the first time the potential for large icebergs to substantially alter the dynamics of a marine ecosystem. The B-15 iceberg (similar to 10,000 km(2)), which calved off the Ross Ice Shelf in the biologically productive southwestern Ross Sea, Antarctica, restricted the normal drift of pack ice, resulting in heavier spring/summer pack ice cover than previously recorded. Extensive ice cover reduced both the area suitable for phytoplankton growth and the length of the algal growing season. Consequently, primary productivity throughout the region was >40% below normal, which changed both the abundance and behavior of upper trophic level organisms. C1 Stanford Univ, Dept Geophys, Stanford, CA 94305 USA. HT Harvey & Associates, San Jose, CA 95118 USA. Univ Maryland, ESSIC, College Pk, MD 20742 USA. NASA GSFC UMBC JCET, Greenbelt, MD 20771 USA. RP Arrigo, KR (reprint author), Stanford Univ, Dept Geophys, Stanford, CA 94305 USA. RI Van Dijken, Gert/C-5276-2011; Markus, Thorsten/D-5365-2012; Fahnestock, Mark/N-2678-2013 NR 25 TC 65 Z9 65 U1 1 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 1 PY 2002 VL 29 IS 7 AR 1104 DI 10.1029/2001GL014160 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DE UT WOS:000178886700056 ER PT J AU de Viron, O Dickey, JO Marcus, SL AF de Viron, O Dickey, JO Marcus, SL TI Annual atmospheric torques: Processes and regional contributions SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ANGULAR-MOMENTUM BALANCE; EARTHS WOBBLE; LENGTH; OCEANS; BUDGET AB [1] All three components of annual atmospheric torque are analyzed with a focus on understanding the contributions from various sources and the physical interactions involved. The annual variations of the equatorial component are dominated by the torque on Earth's ellipticity, with the X component mainly due to an anomaly over the Himalayas, and the Y component associated with pressure anomalies over the North Pacific Ocean. The axial annual component is due to the combined effect of friction and mountain torque, whose amplitudes are at the same order of magnitude with the friction term being larger. Partial cancellation of the mountain torque over Asia and North America is effected by the out-of phase contribution of the Andes (South America having the opposite seasonal cycle to Asia and North America). C1 Observ Royal Belgique, B-1180 Brussels, Belgium. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP de Viron, O (reprint author), Observ Royal Belgique, 3 Ave Circulaire, B-1180 Brussels, Belgium. EM o.deviron@oma.be; jean.dickey@jpl.nasa.gov; steven.marcus@jpl.nasa.gov RI de Viron, Olivier/N-6647-2014 OI de Viron, Olivier/0000-0003-3112-9686 NR 18 TC 2 Z9 2 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 1 PY 2002 VL 29 IS 7 AR 1140 DI 10.1029/2001GL013859 PG 3 WC Geosciences, Multidisciplinary SC Geology GA 609DE UT WOS:000178886700020 ER PT J AU Lau, KM Kim, KM Shen, SSP AF Lau, KM Kim, KM Shen, SSP TI Potential predictability of seasonal precipitation over the United States from canonical ensemble correlation predictions SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SEA-SURFACE TEMPERATURES; US PRECIPITATION; FORECASTS; SKILL AB [1] Potential predictability of seasonal precipitation over the US is explored using a new canonical ensemble correlation (CEC) prediction model, which optimally utilizes intrinsic sea surface temperature (SST) variability in major ocean basins. Results show that CEC yields a remarkable (10-20%) increase in baseline prediction skills for seasonal precipitation over the US for all seasons, compared to traditional statistical predictions using global SST. While the tropical Pacific, i.e., El Nino, contributes to the largest share of potential predictability in the southern tier States during boreal winter, the North Pacific and the North Atlantic are responsible for enhanced predictability in the northern Great Plains, Midwest and the southwest US during boreal summer. Overall, CEC significantly reduces the spring-summer predictability barrier over the conterminous US, thereby raising the skill bar for seasonal precipitation predictions. C1 NASA, Climate & Radiat Branch, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD 20706 USA. Univ Alberta, Dept Math Sci, Edmonton, AB T6G 2G1, Canada. RP Lau, KM (reprint author), NASA, Climate & Radiat Branch, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM lau@climate.gsfc.nasa.gov; kmkim@climate.gsfc.nasa.gov; samshen@climate.gsfc.nasa.gov RI Kim, Kyu-Myong/G-5398-2014 NR 16 TC 14 Z9 15 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 1 PY 2002 VL 29 IS 7 AR 1097 DI 10.1029/2001GL014263 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DE UT WOS:000178886700063 ER PT J AU Natarajan, M Remsberg, EE Gordley, LL AF Natarajan, M Remsberg, EE Gordley, LL TI Ozone budget in the upper stratosphere: Model studies using the reprocessed LIMS and the HALOE datasets SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID VIBRATIONALLY EXCITED OXYGEN; PHOTOCHEMISTRY; DEFICIT; VALIDATION; MESOSPHERE; BALANCE; O-3 AB [1] Recently reprocessed LIMS dataset has been used with a contemporary photochemical model to study the balance between photochemical production and destruction of ozone in the upper stratosphere. Model results corresponding to January 1979 indicate that the ozone deficit is less than 15% in the pressure range of 5 to 0.5 mb between 50degreesS and 50degreesN latitude. The imbalance at 40 km is much smaller than reported by the earliest studies with the archived LIMS data. The same model, when initialized with HALOE (version 19) data for January, 1996, shows similar results with peak ozone deficits being less than 10%. For both cases, the model shows a near balance in the ozone budget above 1 mb, contrary to recent studies based on balloon-borne measurements. The magnitude of the ozone imbalance seen in this study is within the uncertainties of the data and model. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. GATS Inc, Newport News, VA 23606 USA. RP Natarajan, M (reprint author), NASA, Langley Res Ctr, 21 Langley Blvd, Hampton, VA 23681 USA. EM m.natarajan@larc.nasa.gov; e.e.remsberg@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 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 1 PY 2002 VL 29 IS 7 AR 1152 DI 10.1029/2001GL014262 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 609DE UT WOS:000178886700008 ER PT J AU Hale, AS Hapke, B AF Hale, AS Hapke, B TI A time-dependent model of radiative and conductive thermal energy transport in planetary regoliths with applications to the Moon and Mercury SO ICARUS LA English DT Article DE Mercury; Moon; surface; regoliths; radiative transfer ID EMISSION-SPECTRA; ICE; STABILITY; LUNAR; GRADIENTS; POLES AB Modeling thermal energy transfer in planetary regoliths involves treating four processes: visible radiative transfer, thermal radiative transfer, conductive transfer, and heat storage. We explicitly treat these processes while considering time-dependent problems, and we apply this model to the regoliths of the Moon and Mercury. Fitting the model to observational data allows us to constrain the radiative resistivity and thermal inertia parameters of these regoliths and hence constrain their conductivities, thermal extinction coefficients, and average grain sizes. It is also found that water ice would be stable in the polar subsurfaces of both bodies, even in areas which receive unlight during the day. (C) 2002 Elsevier Science (USA). C1 Univ Pittsburgh, Dept Geol & Planetary Sci, Pittsburgh, PA 15260 USA. RP Hale, AS (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 34 TC 15 Z9 19 U1 0 U2 5 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 2002 VL 156 IS 2 BP 318 EP 334 DI 10.1006/icar.2001.6768 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 553ED UT WOS:000175662000002 ER PT J AU McConnochie, TH Buratti, BJ Hillier, JK Tryka, KA AF McConnochie, TH Buratti, BJ Hillier, JK Tryka, KA TI A search for water ice at the lunar poles with clementine images SO ICARUS LA English DT Article DE Moon; Moon; surface; ices ID COHERENT BACKSCATTER; MULTIPLE-SCATTERING; POLAR ICE; MOON; MERCURY; STABILITY; SURFACES; DEPOSITS; PHOTOMETRY; MARS AB Optical and near-IR signatures of water ice on the Moon's surface were sought in the permanently shadowed regions near its poles. Significant amounts of multiply-scattered radiation partly illuminate primary shadows cast by craters and other features. If there is water ice in the permanently shadowed regions of the Moon's surface, its spectral signature should appear in this multiply-scattered light. This investigation can be done most effectively with observations obtained by spacecraft, because most selenocentric positions occupied by the Earth will also be occupied by the Sun at some point in time, and because the lunar poles are seen only obliquely to a terrestrial observer. Images obtained by Clementine are particularly well-suited to this task, because the spacecrafts polar orbit allowed images of the poles to be acquired on nearly every orbit, resulting in literally thousands of images taken within a few degrees of each pole, and because the filters on the ultraviolet-visual camera (UVVIS) and the near infrared camera (NIR) occur at major absorption bands or within important continuum features of water ice. Approximately 5800 images obtained by the UVVIS camera and 1800 images obtained by the NIR camera were calibrated and combined into coadded mosaics to create multispectral maps of the lunar poles with the highest possible signal-to-noise. Unfortunately, analysis of our UVVIS mosaics indicates that any possible signal from multiply-scattered light in primary shadows was overwhelmed by instrumental stray light. For the NIR camera, we were able to determine the normalized reflectance of several regions that were identified by Margot et al. (1999, Science 284, 1658-1660) as permanent shadows. We have identified one permanently shadowed crater with a 1.5-mum band spectral signature indicative of between 2.5 and 21% fractional coverage of H2O frost. However, the same region shows a 2.0 mum spectral signature that is inconsistent with the presence of any water. (C) 2002 Elsevier Science (USA). C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP McConnochie, TH (reprint author), Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. OI Tryka, Kimberly/0000-0002-5399-4235 NR 38 TC 5 Z9 5 U1 0 U2 3 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 2002 VL 156 IS 2 BP 335 EP 351 DI 10.1006/icar.2001.6765 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 553ED UT WOS:000175662000003 ER PT J AU Rao, MN Bogard, DD Nyquist, LE McKay, DS Masarik, J AF Rao, MN Bogard, DD Nyquist, LE McKay, DS Masarik, J TI Neutron capture isotopes in the martian regolith and implications for martian atmospheric noble gases SO ICARUS LA English DT Article ID SNC METEORITES; PARENT BODY; SOLAR-WIND; ORTHOPYROXENITE ALH84001; RAY PRODUCTION; MARS; ORIGIN; SHERGOTTITES; XENON; CARBONATES AB Impact-produced glasses in some martian meteorites have trapped significant amounts of the recent martian atmosphere. From literature data, we estimate that similar to9% of the trapped Kr-80 in these meteorites was produced from neutron capture on Br-79. Estimates of neutron fluences made from Kr-80 and Sm-149 for bulk samples of meteorite EET79001 indicate that Kr-80 excesses in the impact glass were not produced in situ. Theoretical calculations independently predict production of a large neutron-capture component of Kr-80 and Ar-36 in the martian regolith, and part of this component presumably escaped into the martian atmosphere. These calculations were made by using the Los Alamos High-Energy Transport Code to calculate the fluxes of galactic cosmic ray (GCR)-produced thermal neutrons as a function of depth in the uppermost 500 g cm(-2) of the martian surface, and by adopting average Cl, Br, and I concentrations of the upper martian surface of similar to0.3%, similar to20 ppm, and similar to0.5 ppm, respectively. Combining these data with the appropriate neutron-capture cross sections, we calculate Mars global production rates of Kr-80(n) = 2.4 x 10(16) atoms sec(-1), Ar-36(n) = 5.5 x 10(18) atoms sec(-1), and Xe-128(n) = 3 x 10(13) atoms sec(-1). Calculated global production rates of spallogenic Kr-80(sp), and Ar-36(sp), are smaller by factors of similar to770 and similar to29, respectively. It would require similar to330 Myr to produce an amount of 80Kr(n) equivalent to the amount inferred to be present today in the martian atmosphere (similar to2.5 x 1032 atoms). Production of these neutron-capture components probably has occurred over the past similar to4 Gyr, as only an atmospheric pressure substantially higher than today's would appreciably decrease the neutron flux in the regolith. Thus, most of the neutron-capture noble gases produced over time probably remain in the martian regolith and would make sensitive indicators of the time period a sample has resided near the martian surface. Assuming mixing of the martian surface to an average depth of 100 in, the predicted average regolith concentrations of (80)Kn, Ar-36(s), and Xe-128(n) are similar to4 x 10(-9) cm(3) g(-1), similar to1 X 10(-6) cm(3) g(-1), and -5 x 10(-12) cm(3) g(-1), respectively. If similar fractions of these neutron-capture isotopes have escaped into the atmosphere, they would comprise similar to3% and similar to0.2% of the present atmospheric inventories of Ar-36 and Xe-128, respectively. The fractional excess of (80)Km(n) in ancient martian meteorite ALH84001 appears similar to that in shock-glass phases of young shergottite meteorites. If ALH84001 acquired its atmospheric gases similar to4 Gyr ago, this implies that, prior to that time, halogens were greatly concentrated at the martian surface by crustal formational and weathering processes, impacts efficiently degassed the regolith, and Mars did not have a significant atmosphere to shield the surface. (C) 2002 Elsevier Science (USA). C1 NASA, Johnson Space Ctr, Houston, TX 77058 USA. NASA, Johnson Space Ctr, SR, Houston, TX 77058 USA. Comenius Univ, Dept Nucl Phys, Bratislava, Slovakia. RP Rao, MN (reprint author), NASA, Johnson Space Ctr, Houston, TX 77058 USA. NR 83 TC 18 Z9 18 U1 0 U2 8 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 2002 VL 156 IS 2 BP 352 EP 372 DI 10.1006/icar.2001.6809 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 553ED UT WOS:000175662000004 ER PT J AU Hecht, MH AF Hecht, MH TI Metastability of liquid water on Mars SO ICARUS LA English DT Article DE Mars; surface; ices; exobiology ID THERMAL EMISSION SPECTROMETER; GENERAL-CIRCULATION; SIMULATIONS; ICE AB A simple model of local heat transport on Mars demonstrates that transient melting of ice may occur in depressions and gullies nearly anywhere on the planet where thin ice is illuminated by normal-incidence insolation. An experiment has been performed to confirm the model of evaporation rate at low pressure. Reduction of radiative cooling due to gully geometry is shown to be important. Since appropriate meteorological, topographic, and optical conditions may occur on slopes nearly anywhere on the planet, hydrological features such as gullies would likely form only where such ice might accumulate, notably in sheltered locations at high latitudes. It is suggested that cold-trapping of winter condensation could concentrate a sufficient amount of ice to allow seasonal melting in gullies. (C) 2002 Elsevier Science (USA). C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Hecht, MH (reprint author), Jet Prop Lab, M-S 233-200,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 32 TC 176 Z9 178 U1 7 U2 21 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 2002 VL 156 IS 2 BP 373 EP 386 DI 10.1006/icar.2001.6794 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 553ED UT WOS:000175662000005 ER PT J AU Cruikshank, DP Geballe, TR Owen, TC Ore, CMD Roush, TL Brown, RH Lewis, JH AF Cruikshank, DP Geballe, TR Owen, TC Ore, CMD Roush, TL Brown, RH Lewis, JH TI Search for the 3.4-mu m C-H spectral bands on low-albedo asteroids SO ICARUS LA English DT Article DE asteroid composition; infrared observations; organic chemistry; spectroscopy; asteroid surfaces ID REFLECTANCE SPECTRA; ORGANIC-MATTER; OUTER-BELT; MU-M; WATER; INTERSTELLAR; MURCHISON; METEORITE; HYDRATION; BODIES AB A report of the detection of the C-H hydrocarbon band complex at 3.4 mum in an asteroid spectrum, by D. P. Cruikshank and R. H. Brown (1987, Science 238, 183-184) is not confirmed by recent data of higher quality. Spectra of the same asteroid and six other low-albedo asteroids do not show this feature, which if present would indicate the presence of hydrocarbons and might link these asteroids with certain classes of carbonaceous meteorites. (C) 2002 Elsevier Science (USA). C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Gemini Observ, Hilo, HI 96720 USA. Inst Astron, Honolulu, HI 96822 USA. SETI Inst, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. Cuesta Coll, San Luis Obispo, CA 93403 USA. RP Cruikshank, DP (reprint author), NASA, Ames Res Ctr, MS 245-6, Moffett Field, CA 94035 USA. EM dcruikshank@mail.arc.nasa.gov NR 35 TC 4 Z9 4 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 2002 VL 156 IS 2 BP 434 EP 441 DI 10.1006/icar.2001.6810 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 553ED UT WOS:000175662000008 ER PT J AU Fast, K Kostiuk, T Romani, P Espenak, F Hewagama, T Betz, A Boreiko, R Livengood, T AF Fast, K Kostiuk, T Romani, P Espenak, F Hewagama, T Betz, A Boreiko, R Livengood, T TI Temporal behavior of stratospheric ammonia abundance and temperature following the SL9 impacts SO ICARUS LA English DT Article DE Comets S-L9; Jupiter; Jupiter-atmosphere; infrared observations; photochemistry ID INFRARED IMAGING SPECTROSCOPY; COMET SHOEMAKER-LEVY-9; PULSE-RADIOLYSIS; NH2 RADICALS; JUPITER; COLLISION; SITES; KINETICS; MODELS; ETHANE AB Infrared emission lines of stratospheric ammonia (NH3) were observed following the collisions of the fragments of Comet Shoemaker-Levy 9 with Jupiter in July of 1994 at the impact sites of fragments G and K. Infrared heterodyne spectra near 10.7 mum were obtained by A. Betz et al. (in Abstracts for Special Sessions on Comet Shoemaker-Levy 9, The 26th Meeting of the Division for Planetary Sciences, Washington DC, 31 Oct.-4 Nov. 1994, p. 25) using one of the Infrared Spatial Interferometer telescope systems on Mount Wilson. Lineshapes of up to three different NH3 emission lines were measured at a resolving power of similar to10(7) at multiple times following the impacts. We present here our radiative transfer analysis of the fully resolved spectral lineshapes of the multiple rovibrational lines. This analysis provides information on temperature structure and NH3 abundance distributions and their temporal changes up to 18 days after impact. These results are compared to photochemical models to determine the role of photochemistry and other mechanisms in the destruction and dilution of NH3 in the jovian stratosphere after the SL9 impacts. One day following the G impact, the inferred temperature above 0.001 mbar altitude is 283+/-13 K, consistent with a recent plume splashback model. Cooling of the upper stratosphere to 204 K by the fourth day and to quiescence after a week is consistent with a simple gray atmosphere radiative flux calculation and mixing with cold jovian air. During the first 4 days after impact, NH3 was present primarily at altitudes above 1 mbar with a column density of (7.7+/-1.6) x 10(17) cm(-1) after 1 day and (3.7+/-0.8) x 10(17) cm(-2) after 4 days. (Errors represent precision.) We obtained >2.5 times more NH3 than can be supplied by nitrogen from a large cometary fragment, suggesting a primarily jovian source for the NH3. By 18 days postimpact, a return to quiescent upper stratospheric temperature is retrieved for the G region, with an NH3 column density of 7.3 x 10(17) cm(-2) or more in the lower stratosphere, possibly supplied by NH3 upwelling across an impact-heated and turbulent tropopause, which may have been masked by initial dust and haze. Above the 1-mbar level, the maximum retrieved column density decreased to 6.5 x 10(16) cm(-2). Comparison to photochemical models indicates that photolysis alone is not sufficient to account for the loss of NH3 above 1 mbar by that time, even when chemical reformation of NH3 is ignored. We speculate that the dispersion of plume material at high altitudes (above 1 mbar) is responsible for the change in the spectra observed a few days postimpact. Data on the K impact region provide qualitatively consistent results. (C) 2002 Elsevier Science (USA). C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Planetary Syst Branch, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Univ Colorado, CASA, Boulder, CO 80303 USA. Challenger Ctr Space Sci Educ, Alexandria, VA 22314 USA. RP Fast, K (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Planetary Syst Branch, Greenbelt, MD 20771 USA. RI Livengood, Timothy/C-8512-2012; Hewagama, T/C-8488-2012; Romani, Paul/D-2729-2012; Kostiuk, Theodor/A-3077-2014 NR 34 TC 12 Z9 12 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 2002 VL 156 IS 2 BP 485 EP 497 DI 10.1006/icar.2001.6804 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 553ED UT WOS:000175662000012 ER PT J AU Stallard, T Miller, S Millward, G Joseph, RD AF Stallard, T Miller, S Millward, G Joseph, RD TI On the dynamics of the jovian ionosphere and thermosphere II. The measurement of H(3)(+) vibrational temperature, column density, and total emission SO ICARUS LA English DT Article DE aurorae; infrared observations; ionospheres; Jupiter atmosphere; spectroscopy ID JUPITER; ATMOSPHERE; TRANSITIONS; AURORA; MODEL; H-3+ AB We present the first reported measurements of the intensity of a "hotband" transition for the H(3)(+) molecular ion in the northern auroral/polar region of Jupiter. This transition is identified as the R(3, 4(+)) line of the (2v(2) (l = 0) --> v(2)) hotband, with a wavelength of 3.94895 gm. This is the first time such a transition has been measured outside the laboratory, and the wavelength as measured on Jupiter is within the experimental accuracy of the lab measurement. This detection makes it possible to investigate H(3)(+) transitions that simultaneously originate from different vibrational levels. We use the intensity ratio between this line and the Q(1, 0(-)) fundamental transition to derive effective vibrational temperatures, column densities, and total emission parameters as a function of position across the auroral/polar region. Effective temperatures range from similar to900 to similar to1250 K; an increase in average temperature during our observing run of similar to100 K is noted. The derived temperatures are toward the high end or in excess of the auroral temperature range that has been reported in the literature to date. The relationship among emission intensity, temperature, and density is shown to be complex. This may reflect the nonthermalization of the vibrational levels at the gas densities prevailing in the jovian thermosphere. An alternative analysis allowing for this effect is presented. But this approach requires thermospheric temperatures to be similar to1500 K at the level that the majority of H(3)(+) is being produced, higher than has previously been proposed. (C) 2002 Elsevier Science (USA). C1 Inst Astron, Honolulu, HI 96822 USA. UCL, Dept Phys & Astron, London WC1 6BT, England. RP Stallard, T (reprint author), Univ Hawaii, Inst Astron, NASA, Infrared Telescope Facil, Honolulu, HI 96822 USA. EM tss@star.ucl.ac.uk OI Stallard, Tom/0000-0003-3990-670X NR 23 TC 45 Z9 45 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 2002 VL 156 IS 2 BP 498 EP 514 DI 10.1006/icar.2001.6793 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 553ED UT WOS:000175662000013 ER PT J AU Rampino, MR AF Rampino, MR TI Supereruptions as a threat to civilizations on earth-like planets SO ICARUS LA English DT Article DE climate; supereruptions; volcanic winter; volcanism ID GREENLAND ICE CORE; EXPLOSIVE VOLCANIC-ERUPTIONS; GREAT DRY FOG; TOBA ERUPTION; LAKI ERUPTION; VESUVIAN AREA; REAL-TIME; ICELAND; AEROSOLS; WINTER AB The largest explosive volcanic eruptions (supereruptions) produce > 1000 km(3) of ejected material and greater than or equal to 1000 Mt (10(15) g) of submicron atmospheric aerosols and dust. These eruptions may be capable of creating global climatic disturbances sufficient to cause severe problems for world agriculture and modern civilization. Supereruptions are estimated to occur on average about every 50,000 years, which is about twice the frequency of impacts by comets and asteroids > 1 km diameter predicted to cause similar climatic effects. Prediction, prevention, and mitigation of global volcanic climatic disasters may be potentially more difficult than planetary protection from the threat of large impacts, so that explosive volcanism might limit the longevity of technological civilizations. (C) 2002 Elsevier Science (USA). C1 NYU, Earth & Environm Sci Program, New York, NY 10003 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Rampino, MR (reprint author), NYU, Earth & Environm Sci Program, 100 Washington Sq E,Room 1009, New York, NY 10003 USA. NR 88 TC 35 Z9 36 U1 10 U2 31 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 2002 VL 156 IS 2 BP 562 EP 569 DI 10.1006/icar.2001.6808 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 553ED UT WOS:000175662000018 ER PT J AU Ostro, SJ Rosema, KD Campbell, DB Shapiro, II AF Ostro, SJ Rosema, KD Campbell, DB Shapiro, II TI Radar observations of asteroid 1862 Apollo SO ICARUS LA English DT Article DE asteroids; radar ID NEAR-EARTH ASTEROIDS AB Arecibo radar echo spectra show the Q-class asteroid 1862 Apollo to have an elongation within 10% of 1.27, a pole-on silhouette with an average dimension of about 1.7 km, and disc-integrated radar properties that are typical for radar-detected near-Earth asteroids. (C) 2002 Elsevier Science (USA). C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Cornell Univ, Dept Astron, Ithaca, NY USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Ostro, SJ (reprint author), CALTECH, Jet Prop Lab, 300-233, Pasadena, CA 91109 USA. NR 11 TC 6 Z9 6 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 2002 VL 156 IS 2 BP 580 EP 583 DI 10.1006/icar.2001.6805 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 553ED UT WOS:000175662000020 ER PT J AU Snyder, V AF Snyder, V TI Preserving IBM 1401 software SO IEEE ANNALS OF THE HISTORY OF COMPUTING LA English DT Article C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Snyder, V (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1058-6180 J9 IEEE ANN HIST COMPUT JI IEEE Ann. Hist. Comput. PD APR-JUN PY 2002 VL 24 IS 2 BP 101 EP 102 PG 2 WC Computer Science, Theory & Methods; History & Philosophy Of Science SC Computer Science; History & Philosophy of Science GA 560CQ UT WOS:000176064700020 ER PT J AU Gawronski, W Almassy, WT AF Gawronski, W Almassy, WT TI Command preprocessor for radio telescopes and microwave antennas SO IEEE ANTENNAS AND PROPAGATION MAGAZINE LA English DT Article DE antennas; antenna accessories; antenna mechanical factors; antenna transient analysis; control systems; acceleration control; control engineering; linear-quadratic-Gaussian control AB The LQG (linear-quadratic-Gaussian) controllers, designed for the NASA Deep Space Network antennas, have small tracking errors and are resistant to wind disturbances. However, they induce limit cycling during antenna-slewing operations and target acquisition. The cycling is caused by the violation of the antenna's rate and acceleration limits. This problem can be avoided by introduction of a command that does not exceed the limits. A command preprocessor, presented in this paper, generates a command that is equal to the original command if the latter does not exceed the limits, and that varies with the maximum (or minimum) allowable rate and acceleration if the limits are met or exceeded. The preprocessor is comparatively simple, since it requires the knowledge of the command at only the current and the previous instants of time, while the other known preprocessor [3] requires the knowledge of the terminal state and the acquisition time. Analysis and field tests of the preprocessor are presented in this article. The dynamics of the preprocessor itself, and of the antenna with the preprocessor, are illustrated with the antenna's measured responses to typical commands. C1 CALTECH, Jet Prop Lab, Commun Ground Syst Sect, Pasadena, CA 91109 USA. Honeywell, Pasadena, CA 91107 USA. RP Gawronski, W (reprint author), CALTECH, Jet Prop Lab, Commun Ground Syst Sect, MS 238-528,4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM wodek.k.gawronski@jpl.nasa.gov NR 3 TC 4 Z9 7 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1045-9243 EI 1558-4143 J9 IEEE ANTENN PROPAG M JI IEEE Antennas Propag. Mag. PD APR PY 2002 VL 44 IS 2 BP 30 EP 37 DI 10.1109/MAP.2002.1003632 PG 8 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 553WY UT WOS:000175701100005 ER PT J AU Howe, BM Kirkham, H Vorperian, V AF Howe, BM Kirkham, H Vorperian, V TI Power system considerations for undersea observatories SO IEEE JOURNAL OF OCEANIC ENGINEERING LA English DT Article DE DUDC converter; dc power systems; medium voltage dc converters; ocean observatories AB Power systems for undersea observatories combine ideas from terrestrial power systems and switching power supplies with experience from undersea cable systems. Basic system trade-offs for various design decisions are explored in this paper. First, design questions including whether the power delivery should be alternating or direct current and a parallel or series network are examined. This introduces the question of maximum power delivery capability, which is explored in depth. A separate issue, the negative incremental resistance presented to the delivery system by the use of constant-voltage converters, is examined, and the resulting dynamics explored by simulation. C1 Univ Washington, Appl Phys Lab, Seattle, WA 98195 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Howe, BM (reprint author), Univ Washington, Appl Phys Lab, Seattle, WA 98195 USA. OI Howe, Bruce/0000-0001-5711-5253; Kirkham, Harold/0000-0003-2893-7586 NR 16 TC 34 Z9 39 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 0364-9059 J9 IEEE J OCEANIC ENG JI IEEE J. Ocean. Eng. PD APR PY 2002 VL 27 IS 2 BP 267 EP 274 AR PII S0364-9059(02)04121-3 DI 10.1109/JOE.2002.1002481 PG 8 WC Engineering, Civil; Engineering, Ocean; Engineering, Electrical & Electronic; Oceanography SC Engineering; Oceanography GA 554UC UT WOS:000175754700014 ER PT J AU Chattopadhyay, G Schlecht, E Gill, J Martin, S Maestrini, A Pukala, D Maiwald, F Mehdi, I AF Chattopadhyay, G Schlecht, E Gill, J Martin, S Maestrini, A Pukala, D Maiwald, F Mehdi, I TI A broadband 800 GHz Schottky balanced doubler SO IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS LA English DT Article DE balanced doubler; broadband; millimeter waves; Schottky diode AB A broadband planar Schottky balanced doubler at 800 GHz has been designed and built. The design utilizes two Schottky diodes in a balanced configuration on a 12 mum thick Gallium Arsenide (GaAs) substrate as a supporting frame. This broadband doubler (designed for 735 GHz to 850 GHz) uses a split waveguide block and has a relatively simple, fast, and robust assembly procedure. The doubler achieved approximate to 10% efficiency at 765 GHz, giving 1.1 mW of peak output power when pumped with about 9 mW of input power at room temperature. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Chattopadhyay, G (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 7 TC 32 Z9 32 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1531-1309 J9 IEEE MICROW WIREL CO JI IEEE Microw. Wirel. Compon. Lett. PD APR PY 2002 VL 12 IS 4 BP 117 EP 118 AR PII S1531-1309(02)03962-4 DI 10.1109/7260.993286 PG 2 WC Engineering, Electrical & Electronic SC Engineering GA 537EA UT WOS:000174744300001 ER PT J AU Lee, AY Yu, JW Kahn, PB Stoller, RL AF Lee, AY Yu, JW Kahn, PB Stoller, RL TI Space interferometry mission spacecraft pointing error budgets SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article AB Preliminary error budgets for the pointing knowledge, control, and stability of the Space Interferometry Mission (SW) spacecraft are constructed using the specifications of commercial off-the-shelf attitude determination sensors, attitude control actuators, and other spacecraft capabilities that have been demonstrated in past missions. Results obtained indicate that we can meet all the presently known spacecraft pointing requirements. A large number of derived requirements are generated from this study. Examples are specifications on attitude determination sensors, attitude control actuators, minimum settling time after a rest-to-rest spacecraft slew. Preliminary error budgets constructed in this study must be updated to reflect the changing spacecraft design and requirements. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lee, AY (reprint author), CALTECH, Jet Prop Lab, MS 230-104,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 9 TC 10 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 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD APR PY 2002 VL 38 IS 2 BP 502 EP 514 DI 10.1109/TAES.2002.1008982 PG 13 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 560BU UT WOS:000176062300012 ER PT J AU Iannello, C Luo, S Batarseh, I AF Iannello, C Luo, S Batarseh, I TI Full bridge ZCS PWM converter for high-voltage high-power applications SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article AB This paper presents a comprehensive study of a full bridge (FB) zero-current switched (ZCS) PWM converter which is suitable for high-voltage and high-power de application that achieves ZCS for all active switches, and zero-voltage-switched (ZVS) operation for all diodes on the high voltage side. The given converter utilizes component parasitic parameters, particularly for the high-voltage transformer, and employs fixed-frequency phase-shift control to implement soft-switching commutations. Detailed steady state analysis of the converter power stage is presented for the first time and the major features of the converter's power stage are discussed. Small-signal characteristics are also presented and accompanied by a discussion of the controller design and implementation. A design example is also presented based on the steady state analysis and is validated by simulation. Theoretical and simulated results are in good agreement. C1 Univ Cent Florida, Sch Elect Engn & Comp Sci, Orlando, FL 32816 USA. RP NASA, PH J Ground Syst, Kennedy Space Ctr, FL 32899 USA. EM batarseh@mail.ucf.edu NR 13 TC 50 Z9 56 U1 0 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9251 EI 1557-9603 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD APR PY 2002 VL 38 IS 2 BP 515 EP 526 DI 10.1109/TAES.2002.1008983 PG 12 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 560BU UT WOS:000176062300013 ER PT J AU Liebe, CC AF Liebe, CC TI Accuracy performance of star trackers - A tutorial SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article ID IDENTIFICATION; ALGORITHMS; TRACKING; SENSOR AB An autonomous star tracker is an avionics instrument used to provide the absolute 3-axis attitude of a spacecraft utilizing star observations. It consists of an electronic camera and associated processing electronics. The processor has the capability to perform star identification utilizing an internal star catalog stored in firmware and to calculate the attitude quaternion autonomously. Relevant parameters and characteristics of an autonomous star tracker are discussed in detail. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Liebe, CC (reprint author), CALTECH, Jet Prop Lab, MS 198-138,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 33 TC 200 Z9 304 U1 6 U2 43 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD APR PY 2002 VL 38 IS 2 BP 587 EP 599 DI 10.1109/TAES.2002.1008988 PG 13 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 560BU UT WOS:000176062300018 ER PT J AU Feiveson, AH Metter, EJ Paloski, WH AF Feiveson, AH Metter, EJ Paloski, WH TI A statistical model for interpreting computerized dynamic posturography data SO IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING LA English DT Article DE balance control; beta distribution; equilibrium score; latent response; maximum-likelihood; mixed distribution; nonresponse; posture test ID PATENT FORAMEN OVALE; ECHOCARDIOGRAPHY; TRANSESOPHAGEAL; CONTRAST AB Computerized dynamic posturography (CDP) is widely used for assessment of altered balance control. CDP trials are quantified using the equilibrium score (ES), which ranges from zero to 100, as a decreasing function of peak sway angle. The problem of how best to model and analyze ESs from a controlled study is considered. The ES often exhibits a skewed distribution in repeated trials, which can lead to incorrect inference when applying standard regression or analysis of variance models. Furthermore, CDP trials are terminated when a patient loses balance. In these situations, the ES is not observable, but is assigned the lowest possible score-zero. As a result, the response variable has a mixed discrete-continuous distribution, further compromising inference obtained by standard statistical methods. Here, we develop alternative methodology for analyzing ESs under a stochastic model extending the ES to a continuous latent random variable that always exists, but is unobserved in the event of a fall. Loss of balance occurs conditionally, with probability depending on the realized latent ES. After fitting the model by a form of quasi-maximum-likelihood, one may perform statistical inference to assess the effects of explanatory variables. An example is provided, using data from the NIH/NIA Baltimore Longitudinal Study on Aging. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NIA, Clin Invest Lab, Gerontol Res Ctr, Baltimore, MD 21224 USA. RP Feiveson, AH (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code SD3, Houston, TX 77058 USA. FU NIA NIH HHS [1Z01AG00014-41]; PHS HHS [00205] NR 25 TC 12 Z9 12 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 0018-9294 J9 IEEE T BIO-MED ENG JI IEEE Trans. Biomed. Eng. PD APR PY 2002 VL 49 IS 4 BP 300 EP 309 AR PII S0018-9294(02)02900-7 DI 10.1109/10.991157 PG 10 WC Engineering, Biomedical SC Engineering GA 533HX UT WOS:000174524700003 PM 11942721 ER PT J AU Le Vine, DM Abraham, S AF Le Vine, DM Abraham, S TI The effect of the ionosphere on remote sensing of sea surface salinity from space: Absorption and emission at L band SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE ionospheric electromagnetic propagation; microwave radiometry; ocean salinity; remote sensing ID INTERNATIONAL REFERENCE IONOSPHERE; FARADAY-ROTATION; MICROWAVE; MODEL; DELAY AB The purpose of this work is to examine the effects of Faraday rotation and attenuation/emission in the ionosphere in the context of a future remote sensing system in space to measure salinity. Sea surface salinity is important for understanding ocean circulation and for modeling energy exchange with the atmosphere. A passive microwave sensor in space operating near 1.4 GHz (L-band) could provide global coverage and complement in situ arrays being planned to provide subsurface profiles. However, the salinity signal is relatively small and changes along the propagation path can be important sources of error. It is shown that errors due to the ionosphere can be as large as several psu. The dominant source of error is Faraday rotation but emission can be important. C1 Goddard Space Flight Ctr, Lab Hydrospher Proc, Microwave Sensors Branch, Greenbelt, MD 20771 USA. Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Microwave Sensors Branch, Greenbelt, MD 20771 USA. RP Le Vine, DM (reprint author), Goddard Space Flight Ctr, Lab Hydrospher Proc, Microwave Sensors Branch, Code 975, Greenbelt, MD 20771 USA. NR 32 TC 49 Z9 50 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 APR PY 2002 VL 40 IS 4 BP 771 EP 782 AR PII S0196-2892(02)04604-1 DI 10.1109/TGRS.2002.1006342 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 559DB UT WOS:000176008900004 ER PT J AU Yueh, SH Wilson, WJ Dinardo, S AF Yueh, SH Wilson, WJ Dinardo, S TI Polarimetric radar remote sensing of ocean surface wind SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE ocean wind; polarimetric; radar ID BRIGHTNESS TEMPERATURES; VECTOR; RADIOMETER AB Experimental data are presented to support the development of a new concept for ocean wind velocity measurement (speed and direction) with the polarimetric microwave radar technology. This new concept has strong potential for improving the wind direction accuracy and extending the useful swath width by up to 30% for follow-on NASA spaceborne scatterometer mission to SeaWinds series. The key issue is whether there is a relationship between the polarization state of ocean backscatter and surface wind velocity at NASA scatterometer frequencies (13 GHz). An airborne Ku-band polarimetric scatterometer (POLSCAT) was developed for proof-of-concept measurements. A set of aircraft flights indicated repeatable wind direction signals in the POLSCAT observations of sea surfaces at 9-11 m/s wind speed. The correlation coefficients between co- and cross-polarized radar response of ocean surfaces have a peak-to-peak amplitude of about 0.4 and are shown to have an odd-symmetry with respect to the wind direction, unlike the normalized radar cross sections. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Yueh, SH (reprint author), CALTECH, Jet Prop Lab, MS 300-235, Pasadena, CA 91109 USA. EM Simon.Yueh@jpl.nasa.gov NR 11 TC 26 Z9 28 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD APR PY 2002 VL 40 IS 4 BP 793 EP 800 AR PII S0196-2892(02)04589-8 DI 10.1109/TGRS.2002.1006350 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 559DB UT WOS:000176008900006 ER PT J AU Ao, CO Braunisch, H O'Neill, K Kong, JA AF Ao, CO Braunisch, H O'Neill, K Kong, JA TI Quasi-magneto static solution for a conducting and permeable spheroid with arbitrary excitation SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE electromagnetic induction; prolate spheroid; quasi-magnetostatics; spheroidal wavefunction; unexploded ordnance ID SCATTERING AB Broad-band electromagnetic induction (EMI) methods are promising in the detection and discrimination of subsurface metallic targets. In this paper, the quasi-magneto-static solution for a conducting and permeable prolate spheroid under arbitrary excitation by a time-harmonic primary field is obtained by using the separation of variables method with vector spheroidal wave functions. Numerical results for the induced dipole moments are presented for uniform axial and transverse excitations, where the primary field is oriented along the major and minor axis of the prolate spheroid, respectively. We show that the EMI frequency responses are sensitive to the orientation and permeability of the spheroid. An approximation is also developed that aims to extend the exact solution to higher frequencies by assuming slight penetration of the primary field into the spheroid. Under this approximation, a system of equations that refers only to the external field expansions is derived. It is shown that, for spheroids with high relative permeability, this approximation is in fact capable of yielding an accurate broad-band response even for highly elongated spheroids. C1 MIT, Elect Res Lab, Cambridge, MA 02139 USA. MIT, Dept Elect Engn & Comp Sci, Cambridge, MA 02139 USA. USA, Cold Reg Res & Engn Lab, Hanover, NH 03755 USA. RP Ao, CO (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 36 Z9 36 U1 0 U2 5 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 APR PY 2002 VL 40 IS 4 BP 887 EP 897 AR PII S0196-2892(02)04590-4 DI 10.1109/TGRS.2002.1006370 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 559DB UT WOS:000176008900015 ER PT J AU Ma, ZQ Mohammadi, S Bhattacharya, P Katehi, LPB Alterovitz, SA Ponchak, GE AF Ma, ZQ Mohammadi, S Bhattacharya, P Katehi, LPB Alterovitz, SA Ponchak, GE TI A high-power and high-gain X-band Si/SiGe/Si heterojunction bipolar transistor SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article DE class AB; Gummel-Poon model; HBT; large-signal modeling; PAE; SiGe ID MOBILE COMMUNICATION; HBTS; AMPLIFIERS AB A double mesa-type Si/SiGe/Si (n-p-n) heterojunction bipolar transistor (HBT) with record output power and power gain at X-band (8.4 GHz) is demonstrated. The device exhibits collector breakdown voltage BVCBO of more than 24 V and a maximum oscillation frequency of 37 GM. Under continuous-wave operation and class-AB biasing conditions, 24.2-dBm (263-mW) RF output power with concurrent gain of 6.9 dB is measured at the peak power-added efficiency (28.1%) from a single ten-emitter fingers (780-mum(2) emitter area) common-base HBT. The maximum RF output power achieved is as high as 26.3 dBm (430 mW in saturation) and the maximum collector efficiency is 36.9%. The low collector doping concentration together with the device layout result in negligible thermal effects across the transistor and greatly simplifies the large-signal modeling. The conventional Gummel-Poon model yields good agreement between the modeled and the measured dc characteristics and small-signal S-parameters. The accuracy of the model is further validated with the measured power performance of the SiGe power HBT at X-band. These results set a benchmark for power performance for SiGe-based HBTs and indicate promise for their implementation in efficient X-band power-amplifier circuits. C1 Univ Michigan, Dept Elect Engn & Comp Sci, Ann Arbor, MI 48109 USA. NASA Glenn Res Ctr, Cleveland, OH 44135 USA. RP Ma, ZQ (reprint author), Purdue Univ, Sch Engn, W Lafayette, IN 47907 USA. NR 19 TC 31 Z9 36 U1 0 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD APR PY 2002 VL 50 IS 4 BP 1101 EP 1108 AR PII S0018-9480(02)03015-6 DI 10.1109/22.993412 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA 541FJ UT WOS:000174974300004 ER PT J AU Bose, D Govindan, TR Meyyappan, M AF Bose, D Govindan, TR Meyyappan, M TI A coupled plasma and sheath model for high density reactors SO IEEE TRANSACTIONS ON PLASMA SCIENCE LA English DT Article DE plasma materials-processing applications; plasma sheaths; simulation ID RADIO-FREQUENCY SHEATHS; DYNAMICS AB We present a coupled plasma and collisionless sheath model for the simulation of high-density plasma processing reactors. Due to inefficiencies in numerical schemes and the resulting computational burden, a coupled multidimensional plasma and sheath simulation has not been possible for gas mixtures and high-density reactors of practical interest. In this work, we demonstrate that with a fully implicit algorithm and a refined computational mesh, a self-consistent simulation of a reactor including both the plasma and sheath is feasible. We discuss the details of the model equations, the importance of ion inertia, and the resulting sheath profiles for argon and chlorine plasmas. We find that at low operating pressures (10-30 mtorr), the charge separation occurs only within a 0.5-mm layer near the surface in a 300 mm inductively coupled plasma etch reactor. A unified simulation eliminates the use of offline or loosely coupled and oversimplified sheath models which generally leads to uncertainties in ion flux and sheath electrical properties. C1 NASA, Ames Res Ctr, Eloret Corp, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, NASA Adv Supercomp Div, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Ctr Nanotechnol, Moffett Field, CA 94035 USA. RP Bose, D (reprint author), NASA, Ames Res Ctr, Eloret Corp, Moffett Field, CA 94035 USA. NR 16 TC 4 Z9 4 U1 1 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0093-3813 J9 IEEE T PLASMA SCI JI IEEE Trans. Plasma Sci. PD APR PY 2002 VL 30 IS 2 BP 653 EP 659 AR PII S0093-3813(02)04660-X DI 10.1109/TPS.2002.1024264 PN 2 PG 7 WC Physics, Fluids & Plasmas SC Physics GA 585QU UT WOS:000177536700004 ER PT J AU Hales, NW Yamauchi, K Alicea, A Sundaresan, A Pellis, NR Kulkarni, AD AF Hales, NW Yamauchi, K Alicea, A Sundaresan, A Pellis, NR Kulkarni, AD TI A countermeasure to ameliorate immune dysfunction in in vitro simulated microgravity environment: Role of cellular nucleotide nutrition SO IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY-ANIMAL LA English DT Article DE in vitro cultures; simulated microgravity; cell nutrition; nucleotides; T cells ID HYPOGRAVITY; SPACEFLIGHT; ACTIVATION AB Considerable evidence suggests that space travelers are immunosuppressed, presumably by microgravity environmental stresses, putting them at risk for adverse effects, such as opportunistic infections, poor wound healing, and cancer. The purpose of this study was to examine the. role and mechanisms of nucleotide (NT) supplementation as a countermeasure to obviate immunosuppression during space travel. The in vitro rotary cell Culture system, a bioreactor (BIO), was used to simulate the effect of microgravity and to isolate the neuroendocrine effects inherent to in vitro models. The splenocytes from normal mice were cultured in BIO and control tissue culture (TC) flasks with and without phytohemagglutinin (PHA) for mitogen assays. The culture medium was then supplemented with various concentrations of a nucleosides-nucleotides mixture (NS + NT), inosine, and uridine. Cytokines interleukin (IL)-1beta, IL-2 IL-3, tumor necrosis factor-a, and interferon (IFN)-gamma were measured front the supernatant by enzyme-linked immunosorbent assay. In the PHA-stimulated cultures the cellular proliferation in the BIO was significantly decreased as compared with the TC flask cells. BIO-cultured cells in the presence of NS + NT maintained mitogen responses similar to the control TC flask cells. The maintenance of the mitogen response in BIO was observed by the supplementation of uridine and not of inosine. These results are in agreement with out, earlier results from unit gravity experiments that showed that pyrimidines are more effective in pleiogenic immunoprotection to hosts. Cytokines IL-1beta, IL-2, and IFN-gamma in the BIO supernatants of cells cultured in the presence of NS + NT had a significantly higher response than the control vessel. Thus, supplemental NT, especially pyrimidines, can confer immune protection and enhance cytokine responses during space travel. C1 Univ Texas, Hlth Sci Ctr, Houston Med Sch, Dept Surg, Houston, TX 77030 USA. Wyle Labs, Houston, TX 77058 USA. NASA, JSC, Houston, TX 77058 USA. RP Kulkarni, AD (reprint author), Univ Texas, Hlth Sci Ctr, Houston Med Sch, Dept Surg, 6431 Fannin,MSB Suite 4-164, Houston, TX 77030 USA. NR 21 TC 11 Z9 11 U1 1 U2 2 PU SOC IN VITRO BIOLOGY PI LARGO PA 9315 LARGO DR WEST, STE 25, LARGO, MD 20774 USA SN 1071-2690 J9 IN VITRO CELL DEV-AN JI In Vitro Cell. Dev. Biol.-Anim. PD APR PY 2002 VL 38 IS 4 BP 213 EP 217 PG 5 WC Cell Biology; Developmental Biology SC Cell Biology; Developmental Biology GA 588QG UT WOS:000177711700008 ER PT J AU Garg, VK AF Garg, VK TI Heat transfer research on gas turbine airfoils at NASA GRC SO INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW LA English DT Article; Proceedings Paper CT 3rd United Engineering Foundation Conference on Turbulent Heat Transfer CY MAR 18-23, 2001 CL GIRDWOOD, ALASKA DE gas turbine heat transfer; film cooling; internal cooling channel; blade tip; rough blade ID COOLED ROTATING BLADE; TURBULENCE MODELS; TRANSFER PREDICTIONS; REYNOLDS-NUMBER; LEADING-EDGE; ROTOR BLADE; FLOWS; TRANSITION; TIP; TEMPERATURE AB The turbine gas path is a very complex flow field due to a variety of flow and heat transfer phenomena encountered in turbine passages. This manuscript provides an overview of the current work in this field at the NASA Glenn Research Center (GRC). Based on the author's preference, however, more emphasis is on the computational work. There is much more experimental work in progress at GRC than that reported here. Specifically, the external flow and heat transfer characteristics are described over smooth and rough turbine blades for a range of parameter values. For smooth blades, the effect of film-cooling holes as well as internal cooling channels with ribs and bleed holes is considered. Studies on the blade tip region, susceptible to burnout and oxidation due to high thermal loading. are also described, Wherever possible, predictions of heat transfer coefficient on the real blade surface, obtained using in-house-developed codes, are compared with the available experimental data. Suggestions for further work are outlined. (C) 2002 Elsevier Science Inc. All rights reserved. C1 NASA, Glenn Res Ctr, AYT Res Corp, Cleveland, OH 44135 USA. RP Garg, VK (reprint author), NASA, Glenn Res Ctr, AYT Res Corp, Mail Stop 5-11,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 79 TC 36 Z9 38 U1 0 U2 8 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0142-727X J9 INT J HEAT FLUID FL JI Int. J. Heat Fluid Flow PD APR PY 2002 VL 23 IS 2 BP 109 EP 136 AR PII S0142-727X(01)00144-8 DI 10.1016/S0142-727X(01)00144-8 PG 28 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA 528LL UT WOS:000174245200002 ER PT J AU Woodcraft, AL Sudiwala, RV Griffin, MJ Wakui, E Maffei, B Tucker, CE Haynes, CV Gannaway, F Ade, PAR Bock, JJ Turner, AD Sethuraman, S Beeman, JW AF Woodcraft, AL Sudiwala, RV Griffin, MJ Wakui, E Maffei, B Tucker, CE Haynes, CV Gannaway, F Ade, PAR Bock, JJ Turner, AD Sethuraman, S Beeman, JW TI High precision characterisation of semiconductor bolometers SO INTERNATIONAL JOURNAL OF INFRARED AND MILLIMETER WAVES LA English DT Article DE cryogenic detectors; bolometers; characterisation; submillimeter; NTD ID INFRARED DETECTORS; NOISE; GE AB We describe techniques for testing and characterising semiconductor bolometers, using the bolometer model presented in Sudiwalia et. al. [1]. The procedures are illustrated with results from a prototype bolometer for the high frequency instrument (HFI) in the Planck Surveyor cosmic microwave background mission. This is a bolometer using spider-web geometry and a neutron transmutation doped (NTD) germanium thermistor, designed for operation at 100 mK. Details are given of the laboratory facility used to take data at temperatures from 70 mK to 350 mK. This employs an adiabatic demagnetisation refrigerator to cool the detector and optics. The spatial and spectral properties of the optical system are controlled using feedhorns and edge filters. To characterise the bolometer, blanked and optically loaded load curves were measured over a range of temperatures, and the response to modulated radiation was measured as a function of modulation frequency, temperature and bias current. Results for the prototype bolometer show that its behaviour is well represented by an ideal thermal detector down to a temperature of approximately 100 mK. Below this, non-thermal effects such as electron-phonon decoupling or electric field dependent resistance appear to lead to departure from ideal behaviour. The performance was in good agreement with the design goals for the bolometer. C1 Univ Wales Coll Cardiff, Dept Phys & Astron, Cardiff CF24 3YB, S Glam, Wales. Univ London Queen Mary & Westfield Coll, Dept Phys, London E1 4NS, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA. RP Woodcraft, AL (reprint author), Univ Wales Coll Cardiff, Dept Phys & Astron, 5 Parade, Cardiff CF24 3YB, S Glam, Wales. NR 21 TC 12 Z9 12 U1 0 U2 0 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0195-9271 J9 INT J INFRARED MILLI JI Int. J. Infrared Millimeter Waves PD APR PY 2002 VL 23 IS 4 BP 575 EP 595 AR UNSP 0195-9271/02/0400-0575/0 DI 10.1023/A:1015757810970 PG 21 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA 554JJ UT WOS:000175731800004 ER PT J AU Fuerstenau, S Soli, G Cunningham, T Hancock, B Pain, B Sinha, M AF Fuerstenau, S Soli, G Cunningham, T Hancock, B Pain, B Sinha, M TI Active pixel sensors for mass spectrometry SO INTERNATIONAL JOURNAL OF MASS SPECTROMETRY LA English DT Article DE array detector; charge; mass spectrometry; CMOS; Faraday cup AB Active pixel sensors (APS) are micro-fabricated CMOS amplifier arrays that are rapidly replacing CCD devices in many electronic imaging applications. Unlike the pixels of a CCD device, the sensing elements of the APS will respond to locally situated electrostatic charge, owing to the amplifier present in each pixel. We have built two small test arrays with microscopic aluminum electrodes integrated onto standard APS readout circuitry for the purpose of detecting low-energy gas-phase ions in mass spectrometers and other analytical instruments. The devices exhibit a near-linear dynamic range greater than four orders of magnitude, and a noise level of less than 100 electrons at room temperature. Data are presented for the response of the APS detectors to small ions in a miniature magnetic sector mass spectrometer and in an atmospheric pressure jet of helium. Data for individual highly-charged electrospray droplets are presented as well. Anticipated improvements suggest that in the near future APS ion detectors will posses noise levels approaching 10 electrons and will have a useful dynamic range over six orders of magnitude. (Int J Mass Spectrom 215 (2002) 101-111) (C) 2002 Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Fuerstenau, S (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 13 TC 9 Z9 10 U1 1 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 1387-3806 J9 INT J MASS SPECTROM JI Int. J. Mass Spectrom. PD APR 1 PY 2002 VL 215 IS 1-3 SI SI BP 101 EP 111 AR PII S1387-3806(01)00589-9 DI 10.1016/S1387-3806(01)00589-9 PG 11 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 542BE UT WOS:000175023000009 ER PT J AU Pavlis, EC Iorio, L AF Pavlis, EC Iorio, L TI The impact of tidal errors on the determination of the Lense-Thirring effect from satellite laser ranging SO INTERNATIONAL JOURNAL OF MODERN PHYSICS D LA English DT Article DE tides; LAGEOS; LAGEOS II; node; perigee; orbital perturbations ID EARTH TIDES AB The general relativistic Lense-Thirring effect can be detected by means of a suitable combination of orbital residuals of the laser-ranged LAGEOS and LAGEOS II satellites. While this observable is not affected by the orbital perturbation induced by the zonal Earth solid and ocean tides, it is sensitive to those generated by the tesseral and sectorial tides. The assessment of their influence on the measurement of the parameter mu(LT), with which the gravitomagnetic effect is accounted for, is the goal of this paper. After simulating the combined residual curve by calculating accurately the mismodeling of the more effective tidal perturbations, it has been found that, while the solid tides affect the recovery of mu(LT) at a level always well below 1%, for the ocean tides and the other long-period signals muDelta depends strongly on the observational period and the noise level: Deltamu(tides) similar or equal to 2% after seven years. The aliasing effect of K-1 l = 3 p = 1 tide and SRP(4241) solar radiation pressure harmonic, with periods longer than four years, on the perigee of LAGEOS II yield to a maximum systematic uncertainty on mu(LT) of less than 4% over different observational periods. The zonal 18.6-year tide does not affect the combined residuals. C1 NASA, Goddard Space Flight Ctr, Joint Ctr Earth Syst Technol, JCET UMBC,Space Geodesy Branch, Greenbelt, MD 20771 USA. Univ Bari, Dipartmento Fis, I-70126 Bari, Italy. RP Pavlis, EC (reprint author), NASA, Goddard Space Flight Ctr, Joint Ctr Earth Syst Technol, JCET UMBC,Space Geodesy Branch, Code 926,ESSB Bldg 33,Rm G213, Greenbelt, MD 20771 USA. RI Iorio, Lorenzo/G-5658-2011 OI Iorio, Lorenzo/0000-0003-4949-2694 NR 23 TC 20 Z9 20 U1 0 U2 2 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA JOURNAL DEPT PO BOX 128 FARRER ROAD, SINGAPORE 912805, SINGAPORE SN 0218-2718 J9 INT J MOD PHYS D JI Int. J. Mod. Phys. D PD APR PY 2002 VL 11 IS 4 BP 599 EP 618 DI 10.1142/S0218271802001883 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 549XC UT WOS:000175471400010 ER PT J AU Mayaux, P De Grandi, GF Rauste, Y Simard, M Saatchi, S AF Mayaux, P De Grandi, GF Rauste, Y Simard, M Saatchi, S TI Large-scale vegetation maps derived from the combined L-band GRFM and C-band CAMP wide area radar mosaics of Central Africa SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID FOREST MAPPING PROJECT; TROPICAL AFRICA; K-DISTRIBUTION; ERS-1; SAR AB A new dataset has been compiled by combining the wide area Synthetic Aperture Radar ( SAR) mosaics over Central Africa generated in the context of the NASDA Global Rain Forest Mapping (GRFM) and the ESA/EC Central Africa Mosaic Projects (CAMP). The CAMP mosaic consists of more than 700 SAR scenes acquired over the Central Africa region (6degrees S-8degrees N and 5degrees E-26degrees E) by the ESA ERS satellites; the acquisitions were performed in 1994 ( July, August) and in 1996 ( January, February) in two different seasonal conditions. The GRFM Africa mosaic consists of some 3900 JERS-1 images acquired over the region (10degrees S-10degrees N, 14degrees W and 42degrees E) at two dates (January-March 1996 and October-November 1996). In this paper the methods used for combining the two wide area radar mosaics are at first presented. The GRFM Africa mosaic was processed using a block adjustment algorithm with the inclusion of external observations derived from high precision maps along the coastline, which assures an absolute geolocation residual mean squared error of 240 m with respect to ground control points. On the other hand, the CAMP mosaic was compiled taking into account only the internal relative geometric accuracy. Therefore the GRFM dataset was taken as the reference system and the C-band ERS layer composed by rectifying each ERS frame, after down-sampling at 100 m pixel spacing, to the reference mosaic. The rectification procedure uses a set of tie-points measured automatically between each ERS frame and the homologous subset in the JERS mosaic. Due to the different characteristics of the two sensors (microwave centre frequency, viewing geometry, polarization) and the different acquisition dates, each mosaic presents a different window over the same ecosystem. This fact suggests that a new dimension in terms of thematic information content can be added by the fusion of the two datasets. In support of this statement, the complementary characteristics of the two sensors are first discussed with respect to observations related to the vegetation cover in the Congo River floodplain. The potential of the combined dataset for vegetation mapping at the regional scale is further demonstrated by a classification pursuit of the main vegetation types in the central part of the Congo Basin. The main land-cover classes are: lowland rain forest, permanently flooded forest, periodically flooded forest, swamp grassland, and savannah. The classification map is validated using a compilation of national vegetation maps derived from other high resolution remote sensing data or by ground surveys. This first thematic result already confirms that the combined contributions from the L-band and the C-band sensors improve the information extraction capability. Indeed, the radar-derived vegetation map contains better spatial detail than any existing map, especially with respect to the extent of flooded formations. C1 Commiss European Communities, Joint Res Ctr, Global Vegetat Monitoring Unit, Space Applicat Inst, I-21020 Ispra, Varese, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. VTT Otakaari 7B, Espoo 02044, Finland. RP Mayaux, P (reprint author), Commiss European Communities, Joint Res Ctr, Global Vegetat Monitoring Unit, Space Applicat Inst, TP440, I-21020 Ispra, Varese, Italy. RI Simard, Marc/H-3516-2013 OI Simard, Marc/0000-0002-9442-4562 NR 37 TC 21 Z9 21 U1 0 U2 10 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD APR PY 2002 VL 23 IS 7 BP 1261 EP 1282 DI 10.1080/01431160110092849 PG 22 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 535TF UT WOS:000174661900005 ER PT J AU Rosenqvist, A Birkett, CM AF Rosenqvist, A Birkett, CM TI Evaluation of JERS-1 SAR mosaics for hydrological applications in the Congo river basin SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID NASA RADAR ALTIMETER; AMAZON FLOODPLAIN; LEVEL VARIATIONS; LAKES; TOPEX/POSEIDON; PROJECT; FOREST AB Two JERS-1 Synthetic Aperture Radar (SAR) mosaics covering central Africa were investigated with respect to their potential usefulness for studies of seasonal flooding dynamics in the Congo river basin. The mosaic quality was initially evaluated with respect to geometric and radiometric accuracy, as well as to the temporal composition of the data used in the mosaic assembly. The investigation revealed no major defects that should prevent utilization of the data for hydrological applications. The state of flooding captured in each of the two mosaics-preferably portraying the Congo and its tributaries during their annual maximum and minimum water marks-was furthermore evaluated by examining river stage information. Stage data contemporary with the satellite acquisitions (1996) were derived from the TOPEX/POSEIDON Radar Altimeter and supplemented by historical in situ records. The results suggest that the SAR mosaics may serve well to appraise the maximum extents of flooding in the Congo river basin, but quite poorly to assess the dynamics and ranges of the variations. It was reckoned that a minimum of three acquisitions within 1 year would be required to better describe the complex hydrology in the region. The validation uncertainty in rivers where only historical in situ data were available was evident, thus stressing the utility and future potential of radar altimetry to provide substitute measurements of river stages. C1 Natl Space Dev Agcy Japan, Earth Observat Res Ctr, Chuo Ku, Tokyo 1046023, Japan. NASA, USRA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Rosenqvist, A (reprint author), Natl Space Dev Agcy Japan, Earth Observat Res Ctr, Chuo Ku, Triton Sq X-22F,1-8-10 Harumi, Tokyo 1046023, Japan. NR 25 TC 23 Z9 24 U1 2 U2 11 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD APR PY 2002 VL 23 IS 7 BP 1283 EP 1302 DI 10.1080/01431160110092902 PG 20 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 535TF UT WOS:000174661900006 ER PT J AU Salas, WA Ducey, MJ Rignot, E Skole, D AF Salas, WA Ducey, MJ Rignot, E Skole, D TI Assessment of JERS-1 SAR for monitoring secondary vegetation in Amazonia: I. Spatial and temporal variability in backscatter across a chrono-sequence of secondary vegetation stands in Rondonia SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID REGENERATING TROPICAL FOREST; SYNTHETIC APERTURE RADAR; THEMATIC MAPPER DATA; BRAZILIAN AMAZON; RAIN-FOREST; MAPPING DEFORESTATION; ATMOSPHERIC CO2; IMAGING RADARS; LAND-USE; BIOMASS AB Quantification of the direct impact of land use in the tropics on net biotic carbon flux relies on estimates of rates of deforestation, pre- and post-disturbance biomass, and fate of the cleared land. While existing remote sensing applications are providing estimates of the rates of deforestation and the fate of the cleared land (pasture, croplands, or secondary vegetation), techniques for estimating biomass of natural systems with remote sensing are needed. Synthetic Aperture Radar (SAR) presents a unique opportunity for imaging tropical forests under most cloud conditions and potentially provides information on vegetation biomass. Models for estimating above-ground biomass from SAR data have been developed. In this paper we examine the temporal and spatial variability of mean normalized radar cross-section across a chrono-sequence of secondary vegetation stands and clearings in Rondonia, Brazil. We also assess the impact of the observed temporal and spatial variability in normalized radar cross-section on estimating biomass of secondary vegetation stands. Results indicate that, while quantitative estimates of biomass are not stable due to intrinsic texture, system noise, and environmental effects, JERS-1 data are still useful for categorizing relative differences in development of secondary vegetation stands. Merging Japanese Earth Resources Satellite 1 (JERS-1) SAR data with Landsat Thematic Mapper (TM) derived age information data provide improved characterization of clearings and secondary vegetation in Rondonia. C1 Univ New Hampshire, Inst Study Earth Oceans & Space, Complex Syst Res Ctr, Durham, NH 03824 USA. Univ New Hampshire, Dept Nat Resources, Durham, NH 03824 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Michigan State Univ, Dept Geog, Basic Sci & Remote Sensing Initiat, E Lansing, MI 48824 USA. RP Salas, WA (reprint author), Appl Geosolut LLC, 10 Newmarket Rd, Durham, NH 03824 USA. RI Rignot, Eric/A-4560-2014; Ducey, Mark/K-1101-2016 OI Rignot, Eric/0000-0002-3366-0481; NR 62 TC 28 Z9 29 U1 0 U2 6 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD APR PY 2002 VL 23 IS 7 BP 1357 EP 1379 DI 10.1080/01431160110092939 PG 23 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 535TF UT WOS:000174661900009 ER PT J AU Salas, WA Ducey, MJ Rignot, E Skole, D AF Salas, WA Ducey, MJ Rignot, E Skole, D TI Assessment of JERS-1 SAR for monitoring secondary vegetation in Amazonia: II. Spatial, temporal, and radiometric considerations for operational monitoring SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID REGENERATING TROPICAL FOREST; THEMATIC MAPPER DATA; LANDSAT-TM DATA; RAIN-FOREST; MAPPING DEFORESTATION; RADAR BACKSCATTER; BIOMASS; IMAGERY; AGE; RONDONIA AB While the role of Synthetic Aperture Radar (SAR) in operational tropical forest monitoring has yet to be defined, it is nevertheless a critical technology for improving our understanding of deforestation and secondary vegetation in the tropics. In order to understand the role of this technology in operational monitoring a systematic evaluation, relative to other existing technologies of its performance is required. In this paper we evaluate the spatial, temporal, and noise constraints of JERS SAR data for mapping and monitoring biomass of secondary vegetation in Rondonia, Brazil. Our results indicate that the variability in stand estimates of biomass is high and that the source of the majority of the variability is not from speckle and the intrinsic texture of the secondary vegetation but likely due to differences in environmental conditions resulting in differential background scattering properties. Multitemporal analysis significantly improves biomass estimates to the point where it is possible to map changes in biomass. Slight reductions in the variability in estimates of normalized radar cross-section greatly improve biomass estimation. C1 Univ New Hampshire, Inst Study Earth Oceans & Space, Complex Syst Res Ctr, Durham, NH 03824 USA. Univ New Hampshire, Dept Nat Resources, Durham, NH 03824 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Michigan State Univ, Dept Geog, Basic Sci & Remote Sensing Initiat, E Lansing, MI 48824 USA. RP Salas, WA (reprint author), Appl Geosolut LLC, 10 Newmarket Rd, Durham, NH 03824 USA. EM bill.salas@unh.edu RI Rignot, Eric/A-4560-2014; Ducey, Mark/K-1101-2016 OI Rignot, Eric/0000-0002-3366-0481; NR 34 TC 8 Z9 8 U1 0 U2 3 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD APR PY 2002 VL 23 IS 7 BP 1381 EP 1399 DI 10.1080/01431160110092948 PG 19 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 535TF UT WOS:000174661900010 ER PT J AU Chapman, B Siqueira, P Freeman, A AF Chapman, B Siqueira, P Freeman, A TI The JERS Amazon Multi-season Mapping Study (JAMMS): observation strategies and data characteristics SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID TROPICAL FOREST; CALIBRATION; RADAR AB The Japanese Earth Resources Satellite (JERS-1) Amazon Multiseason Mapping Study (JAMMS), part of the Global Rain Forest Mapping (GRFM) project led by the National Space Development Agency of Japan (NASDA), had an ambitious agenda to map the entire Amazon river floodplain (and surrounding areas) twice at high resolution. The observation strategy carried out by NASDA for the JAMMS project and the other elements of the GRFM project (1995-1997) constituted the first time that a spaceborne Synthetic Aperture Radar (SAR) successfully implemented a continental scale, coordinated seasonal mapping campaign. This observation strategy, chosen around the flooding cycle of the major river systems, was designed to provide the first high-resolution measurement of inundation extent by the Amazon river and its tributaries. In order for the scientific community at large to be able to exploit this dataset, the characteristics of the data (resolution, radiometric and geometric calibration, coverage, and ability to be mosaicked) must be well understood. We find that the quantization of the Alaska SAR Facility (ASF) imagery impacts the range of backscatter values that may be observed, in contrast to the NASDA processed imagery. The noise equivalent sigma(0) is -15 dB at worst, but improves to about -20 dB at the centre of the swath. The resolution of the ASF imagery is slightly worse than that processed by NASDA. The initial geolocation accuracy of the ASF processed imagery is quite poor, but may be improved during the mosaicking process. The relative radiometric calibration of the data may be improved to about 0.2 dB by comparing the calibration of overlapping imagery, and through a careful analysis of cross-track trends in the data. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chapman, B (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Siqueira, Paul/D-9760-2016 OI Siqueira, Paul/0000-0001-5781-8282 NR 22 TC 18 Z9 18 U1 1 U2 2 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD APR PY 2002 VL 23 IS 7 BP 1427 EP 1446 DI 10.1080/014311601192966 PG 20 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 535TF UT WOS:000174661900012 ER PT J AU Freeman, A Chapman, B Siqueira, P AF Freeman, A Chapman, B Siqueira, P TI The JERS-1 Amazon Multi-season Mapping Study (JAMMS): Science objectives and implications for future missions SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article AB In late September 1995, the National Space Development Agency of Japan (NASDA) began a new phase of operations for the Japanese Earth Remote Sensing satellite (JERS-1) Synthetic Aperture Radar (SAR)-the Global Rain Forest Mapping (GRFM) project. The first rainforest area to be mapped was the Amazon basin, between September and November of that year (the low flood season for much of the region), in support of the JERS-1 Amazon Multi-season Study (JAMMS), sponsored by NASA. This data acquisition was repeated 6 months later to acquire a second map of the Amazon, during the high flood season in May/June of 1996. The main objective of the JAMMS project was to generate a map of inundation over the Amazon basin by comparing data from the high- and low-flood seasons. Most of the data collected during these two phases of the JAMMS project, a total of similar to5000 frames of data, was received and processed by the Alaska SAR Facility (ASF), then sent to the Jet Propulsion Laboratory (JPL) and NASDA for post-processing and analysis. The quality of the data processed by ASF for the JAMMS project has proved to be exceptional. This paper is a summary of the JAMMS project, which has resulted in a scientific dataset of very high value-a multi-season snapshot of one of the most difficult areas on Earth to monitor, even from space. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Freeman, A (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Siqueira, Paul/D-9760-2016 OI Siqueira, Paul/0000-0001-5781-8282 NR 17 TC 8 Z9 8 U1 0 U2 4 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD APR PY 2002 VL 23 IS 7 BP 1447 EP 1460 DI 10.1080/01431160110092975 PG 14 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 535TF UT WOS:000174661900013 ER PT J AU Simard, M De Grandi, G Saatchi, S Mayaux, P AF Simard, M De Grandi, G Saatchi, S Mayaux, P TI Mapping tropical coastal vegetation using JERS-1 and ERS-1 radar data with a decision tree classifier SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID SYNTHETIC-APERTURE RADAR; RAIN-FOREST; DEFORESTATION; BACKSCATTER; TEXTURE; AFRICA; AREA AB The objective of this paper is to investigate the complementarity of JERS-1 and ERS-1 data for mapping coastal tropical regions. We use a decision tree classifier to classify a coastal region of Gabon and describe the feature contribution using the decision tree diagram. The JERS-1 Global Rain Forest Mapping (GRFM) and ERS-1 Central Africa Mosaic Project (CAMP) datasets are used. The result is a land cover map of the west coast of Gabon. The analysis explicitly shows the complementary characteristics of the L- and C-band Synthetic Aperture Radar (SAR) instruments. We demonstrate the usefulness of combined use of L- and C-band data for large area mapping of coastal regions, especially in flooded areas for discrimination of high and low mangroves as well as grasses and tree swamps. The overall classification accuracy increases by 18% over single band classification. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Commiss European Communities, Joint Res Ctr, Space Applicat Inst, I-21020 Ispra, VA, Italy. RP Simard, M (reprint author), CALTECH, Jet Prop Lab, MS 300-227,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Simard, Marc/H-3516-2013 OI Simard, Marc/0000-0002-9442-4562 NR 28 TC 48 Z9 53 U1 1 U2 12 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD APR PY 2002 VL 23 IS 7 BP 1461 EP 1474 DI 10.1080/01434460110092984 PG 14 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 535TF UT WOS:000174661900014 ER PT J AU Podest, E Saatchi, S AF Podest, E Saatchi, S TI Application of multiscale texture in classifying JERS-1 radar data over tropical vegetation SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID MAPPING DEFORESTATION; SAR IMAGES; LAND-USE; FOREST; CLASSIFICATION; AMAZON; FEATURES; RONDONIA; BRAZIL AB In this paper, a multiscale texture-based classifier for mapping tropical forest land cover types is discussed. The classifier was implemented using the Japanese Earth Remote Sensing Satellite (JERS-1) 100 m resolution radar data acquired over the Amazon Rainforest as part of the Global Rainforest Mapping (GRFM) Project. Demonstrated here is the use of the information content present in different texture measurements at different scales to separate three categories of land cover types: forest from nonforest, terre firme from floodplain vegetation, and grassland from woodland savanna. Various combinations of first-order image statistics known as texture measures were used at different scales as feature dimensions to aid the class discrimination. Eight of the most common first-order texture measures found in the literature were used. The best combination of texture measures at each scale were determined by employing a class separability test using the Bhattachuryya distance. The results were then used as input images into a supervised multiscale maximum likelihood estimation classifier. The classified maps were validated against independent test sites, and by comparison with a Landsat Thematic Mapper (TM) classification. It was found that JERS-1 backscatter and texture measures can discriminate forest from nonforest types with very high accuracy (above 90%). Old secondary forest or regrowth areas were often mixed with forest. Radar backscatter alone was able to separate terre firme and floodplain vegetation. However, texture measures were important in separating open from dense floodplain vegetation. Similarly, the backscatter sensitivity to low biomass values was instrumental in separating woodland from grassland savanna. Texture had a lesser role in separating these two vegetation types but was important to separate the woodland savanna from dense evergreen forest and secondary forests. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Podest, E (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Mitchard, Edward/C-6346-2009 NR 21 TC 42 Z9 48 U1 0 U2 4 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD APR PY 2002 VL 23 IS 7 BP 1487 EP 1506 DI 10.1080/01431160110093000 PG 20 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 535TF UT WOS:000174661900016 ER PT J AU Hess, LL Novo, EMLM Slaymaker, DM Holt, J Steffen, C Valeriano, DM Mertes, LAK Krug, T Melack, JM Gastil, M Holmes, C Hayward, C AF Hess, LL Novo, EMLM Slaymaker, DM Holt, J Steffen, C Valeriano, DM Mertes, LAK Krug, T Melack, JM Gastil, M Holmes, C Hayward, C TI Geocoded digital videography for validation of land cover mapping in the Amazon basin SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID AIRBORNE VIDEO; ACCURACY ASSESSMENT; AERIAL VIDEOGRAPHY; FOREST; RIVER; CLASSIFICATION; VEGETATION; LANDSCAPE; SYSTEM; AREA AB Four Validation Overflights for Amazon Mosaics (VOAM) aerial video surveys have been carried out in the Brazilian Amazon to provide ground verification for mapping of wetland cover with the Global Rain Forest Mapping (GRFM) Project JERS-1 (Japanese Earth Remote Sensing Satellite) mosaics of the Amazon basin. Surveys in 1995 and 1996, acquired with handheld analog camcorders from small aircraft, were timed to imaging of the GRFM low- and high-water mosaics, and limited to within 600 km of Manaus. For the 1997 and 1999 flights, digital camcorder systems were installed in the Bandeirante survey plane operated by Brazil's National Institute for Space Research. The VOAM97 and VOAM99 surveys circumscribed the Brazilian Amazon, documenting ground conditions at resolutions on the order of 1 m (wide-angle format) and 10 cm (zoom format) for wetlands, forests, savannas, and human-impacted areas. Global Positioning System (GPS) information encoded on the video audio track was extracted by mosaicking software that automatically generates geocoded digital mosaics from video clips. On the 1999 survey, a laser altimeter recorded profiles of terrain and vegetation canopy heights. A validation dataset was compiled from the videography for a portion of the GRFM mosaics extending 6degrees by 4degrees in longitude and latitude, using randomly selected points along flight lines. Other applications of the VOAM videography include acquisition of ground control points for image geolocation, creation of a high-resolution geocoded mosaic of a forest study area, forest biomass estimation, and rapid assessment of fire damage. Geocoded digital videography provides a cost-effective means of compiling high-resolution validation datasets for land cover mapping in remote, cloud-covered regions. C1 Univ Calif Santa Barbara, Inst Computat Earth Syst Sci, Santa Barbara, CA 93106 USA. Natl Inst Space Res, BR-12201970 Sao Jose Dos Campos, SP, Brazil. Univ Massachusetts, Dept Nat Resource Conservat, Amherst, MA 01003 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Santa Barbara, Dept Geog, Santa Barbara, CA 93106 USA. RP Hess, LL (reprint author), Univ Calif Santa Barbara, Inst Computat Earth Syst Sci, Santa Barbara, CA 93106 USA. EM lola@icess.ucsb.edu RI Holt, John/C-4896-2009 NR 46 TC 28 Z9 29 U1 0 U2 4 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD APR PY 2002 VL 23 IS 7 BP 1527 EP 1555 DI 10.1080/01431160110092687 PG 29 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 535TF UT WOS:000174661900018 ER PT J AU Bednarcyk, BA Arnold, SM AF Bednarcyk, BA Arnold, SM TI Transverse tensile and creep modeling of continuously reinforced titanium composites with local debonding SO INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES LA English DT Article DE metal matrix composite; debonding; modeling; micromechanics; viscoplasticity; tension; creep; method of cells ID METAL-MATRIX COMPOSITES; MICROMECHANICAL ANALYSIS; INELASTIC DEFORMATION; DAMAGE; FAILURE AB A new widely applicable model for local interfacial debonding in composite materials is presented. Unlike its direct predecessors, the new model allows debonding to progress via unloading of interfacial stresses e en as global loading of the composite continues, The primary advantages of this ne model are its accuracy, simplicity. and efficiency. In order to apply the new debonding model to simulate the behavior of composite materials, it as implemented within the generalized method of cells (GMC) micromechanics model for general periodic M multi-phased materials. The time- and history-dependent (viscoplastic) transverse tensile and creep behavior of SiC/Ti composites, which are known to be subject to internal fiber-matrix debonding. was then simulated. Results indicate that GMC's ability to Simulate the transverse behavior Of titanium Matrix composites has been significantly improved by the new debonding model. Further, the present study has highlighted the need for a more accurate time, temperature, and rate dependent constitutive representation Of the titanium matrix behavior in order to enable predictions of the composite transverse response. without resorting to recalibration of the debonding model parameters. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Brookpark, OH 44142 USA. RP Bednarcyk, BA (reprint author), NASA, Glenn Res Ctr, MS 49-7,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 35 TC 23 Z9 23 U1 1 U2 3 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 APR PY 2002 VL 39 IS 7 BP 1987 EP 2017 AR PII S0020-7683(01)00216-5 DI 10.1016/S0020-7683(01)00216-5 PG 31 WC Mechanics SC Mechanics GA 553GT UT WOS:000175633700015 ER PT J AU Stubenrauch, CJ Briand, V Rossow, WB AF Stubenrauch, CJ Briand, V Rossow, WB TI The role of clear-sky identification in the study of cloud radiative effects: Combined analysis from ISCCP and the Scanner Of Radiation budget SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID GENERAL-CIRCULATION MODEL; SATELLITE DATA; ERBE; VALIDATION; RESOLUTION; ALGORITHMS; INVERSION; FIELD AB Two additional narrowband channels of the Scanner of Radiation Budget (ScaRaB) instrument should improve the Earth Radiation Budget Experiment (ERBE) cloud scene identification. Applying the original International Satellite Cloud Climatology Project (ISCCP) algorithms to the ScaRaB narrowband data gives a clear-sky frequency that is about 5% lower than that given by quasi-simultaneous ISCCP data, an indication that the ISCCP cloud detection is very stable. However, one would expect about 10%-20% smaller clear-sky occurrence for the larger ScaRaB pixels. Adapting the ISCCP algorithms to the ScaRaB spatial resolution and to the different time sampling of the ScaRaB data leads to a reduction of residual cloud contamination. A sensitivity study with time-space-collocated ScaRaB and ISCCP data shows that the clear-sky identification method has a greater effect on the clear-sky frequency and therefore on the statistics than on the zonal mean values of the clear-sky fluxes. The zonal outgoing longwave (LW) fluxes corresponding to ERBE clear sky are in general about 2-10 W m(-2) higher than those from the ScaRaB-adapted ISCCP clear-sky identifications. The latter are close to fluxes corresponding to clear-sky regions from ISCCP data, whereas ScaRaB clear-sky LW fluxes obtained with the original ISCCP identification lie about 1-2 W m(-2) below. Especially in the Tropics, where water vapor abundance is high, the ERBE clear-sky LW fluxes seem to be systematically overestimated by about 4 W m(-2), and shortwave (SW) fluxes are lower by about 5-10 W m(-2). However, another source of uncertainty in the monthly mean zonal cloud radiative effects comes from the low frequency of clear-sky occurrence, when averaging over regions that correspond to the spatial resolution of general circulation models. An additional systematic sampling bias in the clear-sky fluxes appears because the clear-sky regions selected by the different algorithms occur in different geographic regions with different cloud properties. C1 Ecole Polytech, Meteorol Dynam Lab, F-91128 Palaiseau, France. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Stubenrauch, CJ (reprint author), Ecole Polytech, Meteorol Dynam Lab, F-91128 Palaiseau, France. RI Rossow, William/F-3138-2015 NR 29 TC 8 Z9 9 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD APR PY 2002 VL 41 IS 4 BP 396 EP 412 DI 10.1175/1520-0450(2002)041<0396:TROCSI>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 528PE UT WOS:000174251500004 ER PT J AU Siddiqi, I Verevkin, A Prober, DE Skalare, A McGrath, WR Echternach, PM LeDuc, HG AF Siddiqi, I Verevkin, A Prober, DE Skalare, A McGrath, WR Echternach, PM LeDuc, HG TI Heterodyne mixing in diffusion-cooled superconducting aluminum hot-electron bolometers SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID INELASTIC-SCATTERING; TERAHERTZ MIXER; LOW-NOISE; FILMS; TRANSITION; ASTRONOMY; RECEIVER; WIRES; METAL; TIME AB We present microwave (30 GHz) measurements on aluminum superconducting hot-electron bolometer (HEB) mixers. Aluminum HEB mixers have a lower superconducting transition temperature than niobium and niobium nitride devices, and are predicted to have improved sensitivity and require less local oscillator power. The devices studied consist of a narrow superconducting aluminum microbridge with contacts comprised of thick aluminum, titanium, and gold. A perpendicular magnetic field is used to suppress superconductivity in the contacts. The device length is much shorter than the electron-phonon inelastic length [L<(Dtau(e-ph))(1/2)] and thus the intermediate frequency (IF) bandwidth is set by the diffusion time of hot electrons from the microbridge into the contacts. We discuss limitations on the IF bandwidth in very short HEB mixers with fully normal contacts. Overall, the microwave heterodyne mixing results show good performance with a mixer noise temperature inferred from the conversion efficiency and output noise of T(M)greater than or equal to4 K, double side band (DSB). Measurements at 618 GHz yield a conversion efficiency approximately 10 dB lower than observed at 30 GHz. Output saturation by background radiation is postulated to contribute significantly to this difference. A similar decrease in conversion efficiency in the microwave mixing measurements is observed when broadband noise is added to the rf input signal. We discuss the tradeoff between increased sensitivity and the occurrence of saturation effects in low transition temperature HEBs. (C) 2002 American Institute of Physics. C1 Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. RP Siddiqi, I (reprint author), Yale Univ, Dept Appl Phys, 15 Prospect St, New Haven, CT 06520 USA. RI Siddiqi, Irfan/E-5548-2015 NR 43 TC 14 Z9 14 U1 0 U2 4 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD APR 1 PY 2002 VL 91 IS 7 BP 4646 EP 4654 DI 10.1063/1.1448865 PG 9 WC Physics, Applied SC Physics GA 535UC UT WOS:000174663900108 ER PT J AU Morey-Holton, ER Globus, RK AF Morey-Holton, ER Globus, RK TI Hindlimb unloading rodent model: technical aspects SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Review DE simulated weightlessness; hindlimb suspension; altered gravity; mechanical load; animal model ID SIMULATED WEIGHTLESSNESS; GENETIC-REGULATION; SKELETAL RESPONSE; BONE RESPONSE; GROWING RATS; SPACE-FLIGHT; IN-SPACE; SUSPENSION; MUSCLE; MICE AB Since its inception at the National Aeronautics and Space Administration (NASA) Ames Research Center in the mid-1970s, many laboratories around the world have used the rat hindlimb unloading model to simulate weightlessness and to study various aspects of musculoskeletal loading. In this model, the hindlimbs of rodents are elevated to produce a 30degrees head-down tilt, which results in a cephalad fluid shift and avoids weightbearing by the hindquarters. Although several reviews have described scientific results obtained with this model, this is the first review to focus on the technical aspects of hindlimb unloading. This review includes a history of the technique, a brief comparison with spaceflight data, technical details, extension of the model to mice, and other important technical considerations (e.g., housing, room temperature, unloading angle, the potential need for multiple control groups, age, body weight, the use of the forelimb tissues as internal controls, and when to remove animals from experiments). This paper is intended as a reference for researchers, reviewers of manuscripts, and institutional animal care and use committees. Over 800 references, related to the hindlimb unloading model, can be accessed via the electronic version of this article. C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. RP Morey-Holton, ER (reprint author), NASA, Ames Res Ctr, Div Life Sci, M-S 239-11, Moffett Field, CA 94035 USA. NR 47 TC 397 Z9 472 U1 7 U2 30 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD APR PY 2002 VL 92 IS 4 BP 1367 EP 1377 DI 10.1152/japplphysiol.00969.2001 PG 11 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 534EX UT WOS:000174572600004 PM 11895999 ER PT J AU Campbell, JR Hlavka, DL Welton, EJ Flynn, CJ Turner, DD Spinhirne, JD Scott, VS Hwang, IH AF Campbell, JR Hlavka, DL Welton, EJ Flynn, CJ Turner, DD Spinhirne, JD Scott, VS Hwang, IH TI Full-time, eye-safe cloud and aerosol lidar observation at atmospheric radiation measurement program sites: Instruments and data processing SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID CLIMATE AB Atmospheric radiative forcing, surface radiation budget, and top-of-the-atmosphere radiance interpretation involve knowledge of the vertical height structure of overlying cloud and aerosol layers. During the last decade, the U. S. Department of Energy, through the Atmospheric Radiation Measurement (ARM) program, has constructed four long-term atmospheric observing sites in strategic climate regimes (north-central Oklahoma; Barrow, Alaska; and Nauru and Manus Islands in the tropical western Pacific). Micropulse lidar (MPL) systems provide continuous, autonomous observation of nearly all significant atmospheric clouds and aerosols at each of the central ARM facilities. These systems are compact, and transmitted pulses are eye safe. Eye safety is achieved by expanding relatively low-powered outgoing pulse energy through a shared, coaxial transmit/receive telescope. ARM MPL system specifications and specific unit optical designs are discussed. Data normalization and calibration techniques are presented. These techniques, in tandem, represent an operational value-added processing package used to produce normalized data products for ARM cloud and aerosol research. C1 Sci Syst & Applicat Inc, Lanham, MD USA. Univ Maryland Baltimore Cty, Baltimore, MD 21228 USA. Pacific NW Natl Lab, Richland, WA 99352 USA. NASA, Goddard Space Flight Ctr, Mesoscale Atmospher Proc Branch, Greenbelt, MD 20708 USA. Sci & Engn Serv Inc, Burtonsville, MD USA. RP Campbell, JR (reprint author), NASA, Goddard Space Flight Ctr, Mesoscale Atmospher Proc Branch, Code 912, Greenbelt, MD 20708 USA. RI Welton, Ellsworth/A-8362-2012; Campbell, James/C-4884-2012; Scott, Vibart/B-5086-2013; OI Campbell, James/0000-0003-0251-4550; Hlavka, Dennis/0000-0002-2976-7243 NR 14 TC 183 Z9 191 U1 5 U2 19 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 APR PY 2002 VL 19 IS 4 BP 431 EP 442 DI 10.1175/1520-0426(2002)019<0431:FTESCA>2.0.CO;2 PG 12 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 534UH UT WOS:000174605000002 ER PT J AU Hooker, SB Lazin, G Zibordi, G McLean, S AF Hooker, SB Lazin, G Zibordi, G McLean, S TI An evaluation of above- and in-water methods for determining water-leaving radiances SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID REMOTE-SENSING REFLECTANCE; QUALITY MONITOR SQM; OCEAN-COLOR; OPTICAL MEASUREMENTS; FIELD RADIOMETERS; SEAWIFS; CALIBRATION; MATTER AB A high-quality dataset collected at an oceanographic tower was used to compare water-leaving radiances derived from simultaneous above- and in-water optical measurements. The former involved two different above- water systems and four different surface glint correction methods, while the latter used three different in-water sampling systems and three different methods (one system made measurements a fixed distance from the tower, 7.5 m; another at variable distances up to 29 m away; and the third was a buoy sited 50 m away). Instruments with a common calibration history were used, and to separate differences in methods from changes in instrument performance, the stability (at the 1% level) and intercalibration of the instruments (at the 2%-3% level) was performed in the field with a second generation Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Quality Monitor (SQM-II). The water-leaving radiances estimated from the methods were compared to establish their performance during the field campaign, which included clear and overcast skies, Case-1 and Case-2 conditions, calm and roughened sea surface, etc. Three different analytical approaches, based on unbiased percent differences (UPDs) between the methods, were used to compare the various methods. The first used spectral averages across the 412-555-nm SeaWiFS bands (the part of the spectrum used for ocean color algorithms), the second used the ratio of the 490- and 555-nm bands, and the third used the individual (discrete) wavelengths. There were eight primary conclusions of the comparisons, which were considered within the context of the SeaWiFS 5% radiometric objectives. 1) The 5% radiometric objective was achieved for some in-water methods in Case-1 waters for all analytical approaches. 2) The 5% radiometric objective was achieved for some above- water methods in Case- 2 waters for all analytical approaches, and achieved in both water types for band ratios and some discrete wavelengths. 3) The largest uncertainties were in the blue domain (412 and 443 nm). 4) A best-to-worst ranking of the in-water methods based on minimal comparison differences did not depend on the analytical approach, but a similar ranking of the above-water methods did. 5) Above- and in-water methods not specifically designed for Case- 2 conditions were capable of results in keeping with those formulated for the Case- 2 environment or in keeping with results achieved in Case-1 waters. 6) There was a significant difference between two above- water instruments oriented perpendicular with respect to the sun, but pointed in the same direction (best agreement) versus the opposite direction (worst agreement). 7) The overall intercomparison of all methods across Case-1 and Case-2 conditions was at the 9.1% level for the spectral averages, and at the 3.1% level for the band ratios (uncertainties other than those associated with implementing the individual methods account for 2%-4% and 1%-3% of these values, respectively). 8) A comparison with traditional regression analyses confirms the UPD conclusions. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Satlantic Inc, Halifax, NS, Canada. Commiss European Communities, Joint Res Ctr, I-21020 Ispra, Italy. RP Hooker, SB (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Hooker, Stanford/E-2162-2012 NR 52 TC 84 Z9 88 U1 0 U2 8 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 APR PY 2002 VL 19 IS 4 BP 486 EP 515 DI 10.1175/1520-0426(2002)019<0486:AEOAAI>2.0.CO;2 PG 30 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 534UH UT WOS:000174605000007 ER PT J AU Cleek, TM Whalen, RT AF Cleek, TM Whalen, RT TI Cross-sectional structural parameters from densitometry SO JOURNAL OF BIOMECHANICS LA English DT Article DE X-ray absorptiometry; bone geometry; moment of inertia; tibia ID BONE; ABSORPTIOMETRY; FRACTURE; INERTIA; INVITRO; MOMENT; TIBIA; LOAD AB Bone densitometry has previously been used to obtain cross-sectional properties of bone from a single X-ray projection across the bone width. Using three unique projections, we have extended the method to obtain the principal area moments of inertia and orientations of the principal axes at each scan cross-section along the length of the scan. Various aluminum phantoms were used to examine scanner characteristics to develop the highest accuracy possible for in vitro non-invasive analysis of cross-sectional properties. Factors considered included X-ray photon energy, initial scan orientation, the angle spanned by the three scans (included angle), and I-min/I-max ratios. Principal moments of inertia were accurate to within +/-3.1% and principal angles were within +/-1degrees of the expected value for phantoms scanned with included angles of 60degrees and 90degrees at the higher X-ray photon energy (140 kVp). Low standard deviations in the error (0.68-1.84%) also indicate high precision of calculated measurements with these included angles. Accuracy and precision decreased slightly when the included angle was reduced to 30degrees. The method was then successfully applied to a pair of excised cadaveric tibiae. The accuracy and insensitivity of the algorithms to cross-sectional shape and changing isotropy (I-min/I-max) values when various included angles are used make this technique viable for future in vivo studies. C1 NASA, Ames Res Ctr, Musculoskeletal Biomech Lab, Moffett Field, CA 94035 USA. RP Cleek, TM (reprint author), NASA, Ames Res Ctr, Musculoskeletal Biomech Lab, MS 239-11, Moffett Field, CA 94035 USA. NR 13 TC 3 Z9 3 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0021-9290 J9 J BIOMECH JI J. Biomech. PD APR PY 2002 VL 35 IS 4 BP 511 EP 516 AR PII S0021-9290(01)00220-2 DI 10.1016/S0021-9290(01)00220-2 PG 6 WC Biophysics; Engineering, Biomedical SC Biophysics; Engineering GA 548TZ UT WOS:000175407100012 PM 11934420 ER PT J AU Bihary, Z Chaban, GM Gerber, RB AF Bihary, Z Chaban, GM Gerber, RB TI Vibrational spectroscopy and matrix-site geometries of HArF, HKrF, HXeCl, and HXeI in rare-gas solids SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID CHARGE-TRANSFER MOLECULES; SELF-CONSISTENT-FIELD; AB-INITIO; POLYATOMIC SYSTEMS; XENON; COMPOUND; XE; (H2O)(N); HALIDES; STATES AB The vibrational spectroscopy and the matrix-site geometries of several novel rare-gas compounds in the matrix environment were computed theoretically, and compared with experiment. Ab initio calculations are used in the fitting of analytical potential surfaces for the HRgY molecules and for the interactions between HRgY and the matrix atoms Rg. With these potentials, matrix-site geometries for the molecule in the solid are computed. Finally, the vibrational spectroscopy of HRgY in the Rg matrix is computed using the vibrational self-consistent field (VSCF) method. The VSCF includes anharmonic effects, that are essential in this case. The version of VSCF used here includes coupling between HRgY and the vibrations of the solid atoms. The vibrations of 72 matrix atoms are treated. The main results are: (1) The matrix shifts are considerably greater than typically found for neutral, strongly bond molecules, but are much smaller than discrepancies between theory and experiment. This can be attributed to the insufficient accuracy of the potentials used for the HRgY molecules. This calls for better future description of the electronic structure of HRgY. (2) The matrix shifts and splitting effects are interpreted by the calculations in terms of the site geometries involved. These effects are very different for HArF, HKrF than for HXeCl, HXeI. (3) The computed matrix-site splittings are in semiquantitative accord with experiment. This supports the interaction potentials used between HRgY and the matrix. The results provide insights on the effects of the matrix on the rare-gas molecules. (C) 2002 American Institute of Physics. C1 Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Hebrew Univ Jerusalem, Dept Phys Chem, IL-91904 Jerusalem, Israel. Hebrew Univ Jerusalem, Fritz Haber Res Ctr, IL-91904 Jerusalem, Israel. RP Bihary, Z (reprint author), Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA. NR 39 TC 65 Z9 66 U1 1 U2 13 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD APR 1 PY 2002 VL 116 IS 13 BP 5521 EP 5529 DI 10.1063/1.1455621 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 532JH UT WOS:000174470700024 ER PT J AU Chillier, XDF Stone, BM Joblin, C Salama, F Allamandola, LJ AF Chillier, XDF Stone, BM Joblin, C Salama, F Allamandola, LJ TI D-1(B-2(2g))-> D-0((2)A(u)) fluorescence from the matrix-isolated perylene cation following laser excitation into the D-5(B-2(3g)) and D-2(B-2(3g)) electronic states SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID POLYCYCLIC AROMATIC-HYDROCARBONS; DIFFUSE INTERSTELLAR BANDS; INFRARED-SPECTRA; RADICAL CATIONS; EMISSION; ABSORPTION; NE; AR AB Fluorescence spectra of the perylene cation, isolated in an argon matrix and pumped by direct laser excitation via the D-2(B-2(3g))<--D-0((2)A(u)) and D-5(B-2(3g))<--D-0((2)A(u)) transitions, are presented. Direct excitation into the D-5 or D-2 states is followed by rapid nonradiative relaxation to D-1 that, in turn, relaxes radiatively. Excitation spectroscopy across the D-2(B-2(3g))<--D-0((2)A(u)) transition near 730 nm shows that site splitting plays little or no role in determining the spectral substructure in the ion spectra. Tentative assignments for ground state vibrational frequencies are made by a comparison of spectral intervals with calculated normal mode frequencies, with the strongest IR bands leading to the most intense vibronic bands. (C) 2002 American Institute of Physics. C1 NASA, Ames Res Ctr, Astrochem Lab, Moffett Field, CA 94035 USA. RP Chillier, XDF (reprint author), Univ Geneva, Dept Chim Phys Sci 2, CH-1211 Geneva, Switzerland. RI Salama, Farid/A-8787-2009 OI Salama, Farid/0000-0002-6064-4401 NR 28 TC 8 Z9 8 U1 2 U2 4 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD APR 1 PY 2002 VL 116 IS 13 BP 5725 EP 5730 DI 10.1063/1.1456027 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 532JH UT WOS:000174470700047 ER PT J AU Hazeltine, E Ivry, R Diedrichsen, J AF Hazeltine, E Ivry, R Diedrichsen, J TI Callosotomy patients show normal patterns of temporal coupling on a discrete movement task but not on a continuous movement task SO JOURNAL OF COGNITIVE NEUROSCIENCE LA English DT Meeting Abstract C1 Univ Calif Berkeley, Berkeley, CA 94720 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RI Diedrichsen, Jorn/A-7789-2010 OI Diedrichsen, Jorn/0000-0003-0264-8532 NR 0 TC 0 Z9 0 U1 0 U2 0 PU M I T PRESS PI CAMBRIDGE PA FIVE CAMBRIDGE CENTER, CAMBRIDGE, MA 02142 USA SN 0898-929X J9 J COGNITIVE NEUROSCI JI J. Cogn. Neurosci. PD APR PY 2002 SU S MA B99 BP 65 EP 65 PG 1 WC Neurosciences; Psychology, Experimental SC Neurosciences & Neurology; Psychology GA 525LP UT WOS:000174072000228 ER PT J AU Schumacher, EH Brodsky, KL Elston, PA Landau, SM Ivry, R D'Esposito, M Hazeltine, E AF Schumacher, EH Brodsky, KL Elston, PA Landau, SM Ivry, R D'Esposito, M Hazeltine, E TI Dissociating response selection, response competition, and other processes involved in task switching SO JOURNAL OF COGNITIVE NEUROSCIENCE LA English DT Meeting Abstract C1 Univ Calif Berkeley, Berkeley, CA 94720 USA. NASA, Moffett Field, CA 94035 USA. RI Schumacher, Eric/B-5143-2008 NR 0 TC 0 Z9 0 U1 0 U2 0 PU M I T PRESS PI CAMBRIDGE PA FIVE CAMBRIDGE CENTER, CAMBRIDGE, MA 02142 USA SN 0898-929X J9 J COGNITIVE NEUROSCI JI J. Cogn. Neurosci. PD APR PY 2002 SU S MA D36 BP 103 EP 103 PG 1 WC Neurosciences; Psychology, Experimental SC Neurosciences & Neurology; Psychology GA 525LP UT WOS:000174072000403 ER PT J AU Krueger, R Paris, IL O'Brien, TK Minguet, PJ AF Krueger, R Paris, IL O'Brien, TK Minguet, PJ TI Fatigue life methodology for bonded composite skin/stringer configurations SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article DE composite materials; testing; finite element analysis; fatigue life prediction; fracture mechanics; skin/flange interface ID ENERGY RELEASE RATES; CRACK AB A methodology is presented for determining the fatigue life of composite structures based on fatigue characterization data and geometric nonlinear finite element analyses. To demonstrate the approach, predicted results were compared to fatigue tests performed on specimens which consisted of a tapered composite flange, representing a stringer or frame, bonded onto a composite skin. In a first step, quasi-static tension and fatigue tests were performed to evaluate the debonding mechanisms between the skin and the bonded stringer. Specimen edges were examined under the microscope to document the damage occurrence. In a second step, a two-dimensional finite element model was developed to analyze the tests. To predict matrix cracking onset, the relationship between the externally applied tension load and the maximum principal stresses transverse to the fiber direction was determined through geometrically nonlinear analysis. Transverse tension fatigue life data were used to generate an onset fatigue life P-N curve for matrix cracking. The resulting prediction was in good agreement with measured data from the fatigue tests. In a third step, a fracture mechanics approach based on geometrically nonlinear analysis was used to determine the relationship between the externally applied tension load and the critical energy release rate. Mixed mode energy release rate fatigue life data from DCB, 4ENF, and MMB tests were used to create a fatigue life onset G-N curve for delamination. The resulting prediction was in good agreement with data from the fatigue tests. Additionally, the prediction curve for cumulative life to failure was generated from the matrix onset and delamination onset fatigue life curves. The results were in good agreement with data from the fatigue tests, which demonstrated that the methodology offers a significant potential to predict cumulative fatigue life of composite structures. C1 NASA Langley Res Ctr, US Army Res Lab, Hampton, VA 23681 USA. Head Structures Technol Res & Dev Grp, Philadelphia, PA 19142 USA. RP Krueger, R (reprint author), NASA Langley Res Ctr, US Army Res Lab, Mail Stop 132C, Hampton, VA 23681 USA. RI Krueger, Ronald/G-5356-2015 NR 25 TC 10 Z9 10 U1 0 U2 4 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 USA SN 0884-6804 J9 J COMPOS TECH RES JI J. Compos. Technol. Res. PD APR PY 2002 VL 24 IS 2 BP 56 EP 79 PG 24 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA 558ZL UT WOS:000175998400003 ER PT J AU Dudley, M Vetter, WM Neudeck, PG AF Dudley, M Vetter, WM Neudeck, PG TI Polytype identification in heteroepitaxial 3C-SiC grown on 4H-SiC mesas using synchrotron white beam X-ray topography SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE defects; X-ray topography; growth from vapor; single crystal growth; semiconducting silicon carbide ID SIC DEVICE CONFIGURATIONS; 6H-SIC SINGLE-CRYSTALS; DEFECTS; CARBIDE AB Synchrotron white beam X-ray topography (SWBXT), post-oxidation color mapping, atomic force microscopy (AFM) and scanning electron microscopy (SEM) have been used to study the defect and polytype distribution in a thin film grown on mesas structures on part of a 4H-SiC crystal subjected to a non-optimal version of the previously reported [Appl. Phys. Lett. 77 (2000) 1449] procedure for achieving atomic flatness. This combination of techniques was used to provide confirmation that atomic flatness could only be achieved on mesas containing no screw dislocations. It was also found that the vast majority of the atomically flat mesas were of small size as expected since the probability of a screw dislocation threading a mesa is proportional to its area. For these small mesas, either no 3C-SiC nucleation or complete coverage by one or other of the 3C variants was observed. In mesas containing screw dislocations, mostly those of larger size, either no 3C nucleation or partial coverage by single or double phase 3C was observed. In contrast to our previous observations of on-axis mesa samples grown under different conditions in which polytypes such as 15R were observed [J. Phys. D 28 (1995) A56; in: L. Terminello, N. Shinn, G. Ice. K. D'Amico. D. Perry (Eds.), Applications of Synchrotron Radiation Techniques to Materials Science, Mater. Res. Soc. Symp. Proc. 375 (1995) 327] no polytypes other than 4H, 3C(I) and 3C(II) were detected anywhere on this wafer. In the absence of the stacking sequence template provided by the risers of steps (whether from screw dislocations or off cut angle), this data indicates that no other polytype forms but 3C under these growth conditions. This study indicates that combined use of SWBXT in back-reflection and forward-reflection geometry. post-oxidation color mapping, AFM and SEM, is ideally suited for detailed microstructural and structural mapping in SiC. (C) 2002 Elsevier Science B.V. All rights reserved. C1 SUNY Stony Brook, Dept Mat Sci & Engn, Stony Brook, NY 11794 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Dudley, M (reprint author), SUNY Stony Brook, Dept Mat Sci & Engn, Stony Brook, NY 11794 USA. NR 12 TC 17 Z9 19 U1 2 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD APR PY 2002 VL 240 IS 1-2 BP 22 EP 33 AR PII S0022-0248(02)00827-8 DI 10.1016/S0022-0248(02)00827-8 PG 12 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 551JU UT WOS:000175558100004 ER PT J AU Dold, P Schweizer, M Croll, A Benz, KW AF Dold, P Schweizer, M Croll, A Benz, KW TI Measurement of microscopic growth rates in float zone silicon crystals SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 13th International Conference on Crystal Growth held in conjunction with the 11th International Conference on Vapor Growth and Epitaxy CY JUL 30-AUG 04, 2001 CL KYOTO, JAPAN SP Sci Council Japan, Japan Soc Appl Phys, Japanese Assoc Crystal Growth, Fdn Promot Mat Sci & Technol Japan, Izumi Fdn Promot Sci & Engn, Kansai Res Fdn Technol Program, Murata Fdn Promot Sci & Engn, Doshisha Univ, Japan Soc Micrograv Applicat, Anritsu Corp, ASEC Inc, Canon Inc, Chichibu Fuji Co Ltd, Dai Ichi Kiden Co Ltd DE convection; growth velocity; interfaces; magnetic fields; segregation; floating zone technique; semiconducting silicon ID STATIC AXIAL FIELDS; MAGNETIC-FIELDS; TEMPERATURE-FLUCTUATIONS; NUMERICAL-SIMULATION; MARANGONI FLOW; LIQUID BRIDGE; MELT; OSCILLATIONS; MICROGRAVITY; INTERFACE AB The micro segregation of doped silicon crystals grown by the float zone technique was investigated by using a heat pulse technique. The heat pulses (3-10 Hz) generated finely spaced periodic time markers which overlay the dopant inhomogeneities caused by convective instabilities in the melt. The microscopic growth rate was determined by measuring the distance of the markers. For a flow regime governed by time-dependent thermocapillary convection, the average growth rate of 2 mm/min fluctuated from 1.27 to 2.63 mm/min with fluctuation frequencies between 0.01 and 0.15 Hz. The microscopic growth rate becomes constant when applying a static axial magnetic field of 500 mT. The impact of concentration fluctuations within the solute boundary layer ahead of the crystal-melt interface was observed qualitatively by comparing the interface profile given by the pulse markings with the contours of the convectively induced striations. (C) 2002 Elsevier Science B.V. All rights reserved. C1 Univ Freiburg, Inst Kristallog, D-79104 Freiburg, Germany. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. Univ Freiberg, Inst NE Met & Reinstoffe, D-09599 Freiberg, Germany. RP Dold, P (reprint author), Univ Freiburg, Inst Kristallog, Hebelstr 25, D-79104 Freiburg, Germany. RI Croell, Arne/A-2480-2013 OI Croell, Arne/0000-0002-8673-9994 NR 22 TC 8 Z9 8 U1 2 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD APR PY 2002 VL 237 BP 1671 EP 1677 AR PII S0022-0248(01)02318-1 DI 10.1016/S0022-0248(01)02318-1 PN 3 PG 7 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 569CA UT WOS:000176581400009 ER PT J AU Volz, MP Schweizer, M Kaiser, N Cobb, SD Vujisic, L Motakef, S Szofran, FR AF Volz, MP Schweizer, M Kaiser, N Cobb, SD Vujisic, L Motakef, S Szofran, FR TI Bridgman growth of detached GeSi crystals SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 13th International Conference on Crystal Growth held in conjunction with the 11th International Conference on Vapor Growth and Epitaxy CY JUL 30-AUG 04, 2001 CL KYOTO, JAPAN SP Sci Council Japan, Japan Soc Appl Phys, Japanese Assoc Crystal Growth, Fdn Promot Mat Sci & Technol Japan, Izumi Fdn Promot Sci & Engn, Kansai Res Fdn Technol Program, Murata Fdn Promot Sci & Engn, Doshisha Univ, Japan Soc Micrograv Applicat, Anritsu Corp, ASEC Inc, Canon Inc, Chichibu Fuji Co Ltd, Dai Ichi Kiden Co Ltd DE Bridgman technique; growth from melt; detached growth; germanium-silicon ID SOLIDIFICATION; MICROGRAVITY AB Ge1-xSix (02.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 530VU UT WOS:000174380300004 ER PT J AU Gyekenyesi, AL Kautz, HE Shannon, RE AF Gyekenyesi, AL Kautz, HE Shannon, RE TI Quantifying creep damage in a metallic alloy using acousto-ultrasonics SO JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE LA English DT Article DE acousto-ultrasonics; creep damage; health monitoring; metallic alloy; nondestructive evaluation; turbine AB Due to elevated temperatures and excessive stresses, turbine components may experience creep behavior. As a result, it is desirable to monitor and assess the current condition of such components. This study used the acousto-ultrasonics (AU) method in an effort to monitor the state of the material at various percentages of expended (i.e., used-up creep life) creep life in the nickel base alloy, Udimet 520. A stepped specimen (i.e., varying cross-sectional area) was used, which allowed for a post mortem nondestructive evaluation (NDE) analysis of the various levels of expended life. The overall objectives in this study were two-fold: First, a user-friendly, graphical interface AU system was developed, and second, the new AU system was applied as a NDE tool to assess distributed damage resulting from creep. The experimental results demonstrated that the AU method was able to detect material changes as a function of expended creep life. C1 OAI, Glenn Res Ctr, Cleveland, OH 44135 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Siemens Westinghouse Power Co, Ctr Sci & Technol, Pittsburgh, PA 15235 USA. RP Gyekenyesi, AL (reprint author), OAI, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 13 TC 7 Z9 8 U1 0 U2 2 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 USA SN 1059-9495 J9 J MATER ENG PERFORM JI J. Mater. Eng. Perform. PD APR PY 2002 VL 11 IS 2 BP 205 EP 210 DI 10.1361/105994902770344277 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA 552VL UT WOS:000175640700012 ER PT J AU Ustinov, EA AF Ustinov, EA TI Adjoint sensitivity analysis of radiative transfer equation: 2. Applications to retrievals of temperature in scattering atmospheres in thermal IR SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article DE adjoint sensitivity analysis; radiative transfer; remote sensing AB An approach to formulation of inversion algorithms for thermal sounding in the case of scattering atmosphere based on the adjoint equation of radiative transfer (Ustinov, JQSRT 68 (2001) 195, referred to as Paper I in the main text) is applied to temperature retrievals in the scattering atmosphere for the nadir viewing geometry. Analytical expressions for the weighting functions involving the integration of the source function are derived. Temperature weighting functions for a simple model of the atmosphere with scattering are evaluated and convergence to the case of pure atmospheric absorption is demonstrated. The numerical experiments on temperature retrievals are carried out to demonstrate the validity of the expressions obtained. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ustinov, EA (reprint author), CALTECH, Jet Prop Lab, Mail Stop 183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Ustinov, Eugene/D-1350-2015 OI Ustinov, Eugene/0000-0003-0227-4286 NR 11 TC 6 Z9 6 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD APR 1 PY 2002 VL 73 IS 1 BP 29 EP 40 AR PII S0022-4073(01)00167-4 DI 10.1016/S0022-4073(01)00167-4 PG 12 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 522LR UT WOS:000173899100004 ER PT J AU Qi, DW Luo, LS Aravamuthan, R Strieder, W AF Qi, DW Luo, LS Aravamuthan, R Strieder, W TI Lateral migration and orientation of elliptical particles in poiseuille flows SO JOURNAL OF STATISTICAL PHYSICS LA English DT Article; Proceedings Paper CT 9th Annual International Conference on Discrete Simulation of Fluid Dynamics CY AUG 21-24, 2000 CL SANTA FE, NEW MEXICO SP Ctr Nonlinear Studies, Los Alamos Natl Lab, Theoret Div, Sandia Natl Labs DE lattice Boltzmann simulation; elliptical particles; particle suspension; lateral migration; particle orientation; molecular dynamic simulation ID DISCRETIZED BOLTZMANN-EQUATION; INITIAL-VALUE PROBLEMS; REYNOLDS-NUMBER FLOWS; PARTICULATE SUSPENSIONS; DIRECT SIMULATION; NUMERICAL SIMULATIONS; NEWTONIAN FLUID; SOLID BODIES; SEDIMENTATION; MOTION AB The simulations of elliptical particles in a pressure driven flow are performed using a lattice Boltzmann (LB) method. Effects of multi-particle interaction on the lateral migration and orientation of both neutrally and non-neutrally buoyant particles are investigated, Low and itermediate solid concentrations in terms of area fraction f(a) = 13, 25, and 40% are included in these simulations. C1 Western Michigan Univ, Dept Paper & Printing Sci & Engn, Kalamazoo, MI 49008 USA. NASA, Langley Res Ctr, ICASE, Hampton, VA USA. Western Michigan Univ, Dept Paper & Printing Sci & Engn, Kalamazoo, MI 49008 USA. Univ Notre Dame, Dept Chem Engn, Notre Dame, IN 46556 USA. RP Qi, DW (reprint author), Western Michigan Univ, Dept Paper & Printing Sci & Engn, Kalamazoo, MI 49008 USA. RI Luo, Li-Shi/A-4561-2011 OI Luo, Li-Shi/0000-0003-1215-7892 NR 26 TC 20 Z9 20 U1 0 U2 4 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-4715 J9 J STAT PHYS JI J. Stat. Phys. PD APR PY 2002 VL 107 IS 1-2 BP 101 EP 120 DI 10.1023/A:1014502402884 PG 20 WC Physics, Mathematical SC Physics GA 542NW UT WOS:000175051500008 ER PT J AU Lockard, DP Luo, LS Milder, SD Singer, BA AF Lockard, DP Luo, LS Milder, SD Singer, BA TI Evaluation of PowerFLOW for aerodynamic applications SO JOURNAL OF STATISTICAL PHYSICS LA English DT Article; Proceedings Paper CT 9th Annual International Conference on Discrete Simulation of Fluid Dynamics CY AUG 21-24, 2000 CL SANTA FE, NM SP Ctr Nonlinear Studies, Los Alamos Natl Lab, Theoret Div, Sandia Natl Labs DE PowerFLOW; lattice Boltzmann method; lattice gas automata; 2D flow past NACA-0012 airfoil; aerodynamic simulations; turbulence modeling; wall function ID LATTICE-BOLTZMANN METHOD; NAVIER-STOKES COMPUTATIONS; FLUID-DYNAMICS; TIME EVOLUTION; GAS AUTOMATA; BGK MODELS; EQUATION; FLOWS; PROGRESS; SYSTEM AB A careful comparison of the performance of a commercially available Lattice-Boltzmann Equation solver (PowerFLOW) was made with a conventional, block-structured computational fluid-dynamics code (CFL3D) for the flow over a two-dimensional NACA-0012 airfoil. The results suggest that the version of PowerFLOW used in the investigation produced solutions with large errors in the computed flow field; these errors are attributed to inadequate resolution of the boundary layer for reasons related to grid resolution and primitive turbulence modeling. The requirement of square grid cells in the PowerFLOW calculations limited the number of points that could be used to span the boundary layer on the wing and still keep the computation size small enough to fit on the available computers. Although not discussed in detail, disappointing results were also obtained with PowerFLOW for a cavity flow and for the flow around a generic helicopter configuration. C1 NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Hampton, VA 23681 USA. NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. George Mason Univ, Sch Computat Sci, Fairfax, VA 22030 USA. RP Lockard, DP (reprint author), NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Mail Stop 128, Hampton, VA 23681 USA. EM d.p.lockard@larc.nasa.gov; luo@icase.edu; b.a.singer@larc.nasa.gov RI Luo, Li-Shi/A-4561-2011 OI Luo, Li-Shi/0000-0003-1215-7892 NR 63 TC 25 Z9 26 U1 0 U2 7 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-4715 J9 J STAT PHYS JI J. Stat. Phys. PD APR PY 2002 VL 107 IS 1-2 BP 423 EP 478 DI 10.1023/A:1014539411062 PG 56 WC Physics, Mathematical SC Physics GA 542NW UT WOS:000175051500026 ER PT J AU Morisio, M Seaman, CB Basili, VR Parra, AT Kraft, SE Condon, SE AF Morisio, M Seaman, CB Basili, VR Parra, AT Kraft, SE Condon, SE TI COTS-based software development: Processes and open issues SO JOURNAL OF SYSTEMS AND SOFTWARE LA English DT Article DE commercial off-the-shelf; COTS; component-based; empirical study; software development process AB The work described in this paper is an investigation of the COTS-based software development within a particular NASA environment, with an emphasis on the processes used. Fifteen projects using a COTS-based approach were studied and their actual process was documented. This process is evaluated to identify essential differences in comparison to traditional software development. The main differences. and the activities for which projects require more guidance, are requirements definition and COTS selection, high level design, integration and testing. Starting from these empirical observations, a new process and set of guidelines for COTS-based development are developed and briefly presented. (C) 2002 Elsevier Science Inc. All rights reserved. C1 Politecn Torino, Dipartimento Automat & Informat, I-10129 Turin, Italy. Univ Maryland, College Pk, MD 20742 USA. Univ Maryland Baltimore Cty, Baltimore, MD 21250 USA. Fraunhofer Ctr Maryland, College Pk, MD 20742 USA. Comp Sci Corp, Lanham, MD USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Morisio, M (reprint author), Politecn Torino, Dipartimento Automat & Informat, Corso Duca Abruzzi 24, I-10129 Turin, Italy. EM morisio@polito.it; cseaman@umbc.edu; basili@fc-md.umd.edu; aparra@csc.com; skraft@gsfc.nasa.gov NR 16 TC 35 Z9 40 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0164-1212 J9 J SYST SOFTWARE JI J. Syst. Softw. PD APR 1 PY 2002 VL 61 IS 3 BP 189 EP 199 AR PII S0164-1212(01)00147-9 DI 10.1016/S0164-1212(01)00147-9 PG 11 WC Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA 547KP UT WOS:000175331800003 ER PT J AU Quinn, GD Salem, JA AF Quinn, GD Salem, JA TI Effect of lateral cracks on fracture toughness determined by the surface-crack-in-flexure method SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID ALPHA-SILICON CARBIDE; HOT-PRESSED SI3N4; R-CURVES; CERAMICS; GLASS; FLAWS; GROWTH; PARAMETERS; SPECIMENS; ALUMINA AB The surface-crack-in-flexure (SCF) method uses a Knoop indenter to create small, semielliptical surface precracks in beam specimens. Lateral cracks may interfere with the primary median crack and cause errors of up to 10% in determination of fracture toughness, particularly for materials for which the fracture toughness is similar to3 MPa.m(1/2) or less. Although the residual-stress-damage zone is ground or polished away by hand by removing 4.5-5 times the indentation depth, this amount may not be sufficient to completely remove the lateral cracks in low-fracture-toughness materials. A series of tests were conducted on sintered alpha silicon carbide with different amounts of material removed after indentation. Once the lateral cracks were fully removed, the SCF results concurred with single-edged-precracked-beam and chevron-notched-beam data collected in accordance with ASTM Designation C1421. A simple remedy for the SCF method is to examine the outer ground surface for remnants of lateral cracks before fracture and to remove more material if necessary. C1 NIST, Div Ceram, Gaithersburg, MD 20899 USA. NASA, Struct Div, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Quinn, GD (reprint author), NIST, Div Ceram, Gaithersburg, MD 20899 USA. NR 48 TC 21 Z9 21 U1 3 U2 9 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43086-6136 USA SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD APR PY 2002 VL 85 IS 4 BP 873 EP 880 PG 8 WC Materials Science, Ceramics SC Materials Science GA 540XV UT WOS:000174956900022 ER PT J AU Whalley, M Howitt, J AF Whalley, M Howitt, J TI Optimization of Partial Authority Automatic Flight Control Systems for hover/low-speed maneuvering in degraded visual environments SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article; Proceedings Paper CT 55th Annual Forum of the American-Helicopter-Society CY MAY 25-27, 1999 CL MONTREAL, CANADA SP Amer Helicopter Soc AB A ground-based piloted simulation study of a Partial Authority Flight Control Augmentation concept for the UH-60 Black Hawk helicopter was performed. Two command model gain sets were synthesized for a model-following, attitude-command attitude-hold (ACAH) control law: 1) a gain set optimized for Level 1 handling qualities with respect to the ADS-33D handling qualities specification, and 2) a gain set optimized for minimum least-squares error between the open- and closed-loop stick-to-attitude frequency response. The resulting configurations were tested at both 10 and 15 percent stability augmentation system (SAS) authority levels. The standard UR-60A SAS was also evaluated for comparison purposes. Four hover/low-speed tasks were performed in a simulated degraded visual environment using night vision goggles. Series servo hardover recoveries at 10 and 15 percent authority levels were also assessed. The results indicate that the "frequency-matched" ACAH control law reduced series servo activity, reduced series servo saturation, and improved control predictability in the region of saturation. C1 USA, NASA, Rotorcraft Div, Ames Res Ctr, Moffett Field, CA 94035 USA. Powered Lift & Maritime Aviat, Bedford, England. RP Whalley, M (reprint author), USA, NASA, Rotorcraft Div, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 15 TC 2 Z9 2 U1 0 U2 2 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD APR PY 2002 VL 47 IS 2 BP 79 EP 89 PG 11 WC Engineering, Aerospace SC Engineering GA 546VF UT WOS:000175295100001 ER PT J AU Kottapalli, S Kitaplioglu, C AF Kottapalli, S Kitaplioglu, C TI Neural network representation of external tilt-rotor noise SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article; Proceedings Paper CT 6th AIAA/Confederation of European Aerospace Societies Aeroacoustics Conference CY JUN, 2000 CL MAUI, HAWAII SP Amer Inst Aeronaut & Astronaut AB Results from a neural network study of the noise data from a full-scale XV-15 tilt-rotor are presented. Specifically, this database was acquired during the 1998 NASA Ames 80- by 120-foot wind tunnel test to establish the blade-vortex-interaction noise signature. The present study has three objectives: 1) To conduct a neural-network-based quality assessment of the noise data; 2) To obtain neural network representations of the noise data and to demonstrate their sensitivity to test conditions; 3) To obtain neural-network-based noise predictions. Overall, neural networks are successfully used to assess the quality of the noise data and to represent the complete database as well as to predict tilt-rotor noise using the minimal amount of input data. As major findings, the data quality is found to be acceptable, and accurate neural network representations are obtained for the test-condition-sensitivity cases. C1 USA, NASA, Rotorcraft Div, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kottapalli, S (reprint author), USA, NASA, Rotorcraft Div, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 9 TC 2 Z9 2 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD APR PY 2002 VL 47 IS 2 BP 109 EP 114 PG 6 WC Engineering, Aerospace SC Engineering GA 546VF UT WOS:000175295100004 ER PT J AU Wilbur, ML Mirick, PH Yeager, WT Langston, CW Cesnik, CES Shin, S AF Wilbur, ML Mirick, PH Yeager, WT Langston, CW Cesnik, CES Shin, S TI Vibratory loads reduction testing of the NASA/Army/MIT active twist rotor SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article; Proceedings Paper CT 57th Annual Forum of the American-Helicopter-Society CY MAY 09-11, 2001 CL WASHINGTON, D.C. SP Amer Helicopter Soc AB Recent studies have indicated that controlled strain-induced blade twisting can be attained using piezoelectric Active Fiber Composite technology, and that such advancement may provide a mechanism for reduced rotorcraft vibrations and increased rotor performance. To validate these findings experimentally, a cooperative effort between the NASA Langley Research Center, the Army Research Laboratory, and the MIT Active Materials and Structures Laboratory has been developed. As a result of this collaboration a four-bladed, aeroelasticafly scaled, active-twist model rotor has been designed and fabricated for testing in the heavy gas test medium of the NASA Langley Transonic Dynamics Tunnel. Initial wind tunnel testing has been conducted to assess the impact of active blade twist on both fixed- and rotating-system vibratory loads in forward flight. The active twist control was found to have a pronounced effect on all system loads and was shown to offer generally reductions in fixed-system loads of 60% to 95%, depending upon flight condition, with 1.1degrees to 1.4degrees of dynamic blade twist observed. A summary of the systems developed and the vibratory loads reduction results obtained are presented in this paper. C1 USA, Res Lab, NASA, Langley Res Ctr, Hampton, VA 23665 USA. MIT, Act Mat & Struct Lab, Cambridge, MA 02139 USA. RP Wilbur, ML (reprint author), USA, Res Lab, NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 22 TC 29 Z9 29 U1 0 U2 3 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD APR PY 2002 VL 47 IS 2 BP 123 EP 133 PG 11 WC Engineering, Aerospace SC Engineering GA 546VF UT WOS:000175295100006 ER PT J AU Piatak, DJ Kvaternik, RG Nixon, MW Langston, CW Singleton, JD Bennett, RL Brown, RK AF Piatak, DJ Kvaternik, RG Nixon, MW Langston, CW Singleton, JD Bennett, RL Brown, RK TI A parametric investigation of whirl-flutter stability on the WRATS tiltrotor model SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article; Proceedings Paper CT 57th Annual Forum of the American-Helicopter-Society CY MAY 09-11, 2001 CL WASHINGTON, D.C. SP Amer Helicopter Soc AB A wind-tunnel investigation of whirl-flutter stability boundaries has been conducted on a 1/5-size semispan tiltrotor model known as the Wing and Rotor Aeroelastic Test System (WRATS) in the NASA-Langley Transonic Dynamics Tunnel as part of a joint NASA/Army/Bell Helicopter Textron, Inc (BHTI) research program. The model was developed by BHTI as part of the JVX (V-22) development program in the 1980s and was modified to incorporate a hydraulically actuated swasliplate control system for use in active controls research. The modifications have changed the model's pylon mass properties sufficiently to warrant testing to re-establish its baseline stability boundaries. A parametric investigation of the effect of rotor design variables on stability was also conducted. Experimental baseline stability boundaries in air are presented with comparisons to results from parametric variations of rotor pitch-flap coupling and control system stiffness. Increasing the rotor pitch-flap coupling (53 more negative) has a destabilizing effect on stability, while a reduction in control system stiffness has little effect on whirl-flutter stability. The results from tests conducted in R-134a heavy gas indicate that matching full-scale blade Mach number has a destabilizing effect on whirl-flutter. This finding demonstrates that stability boundaries obtained from tests at reduced Mach number in air are unconservative. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. USA, Res Lab, Vehicle Technol Directorate, NASA,Langley Res Ctr, Hampton, VA USA. Bell Helicopter Textron Inc, Ft Worth, TX USA. RP Piatak, DJ (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 23 TC 4 Z9 7 U1 1 U2 4 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD APR PY 2002 VL 47 IS 2 BP 134 EP 144 PG 11 WC Engineering, Aerospace SC Engineering GA 546VF UT WOS:000175295100007 ER PT J AU Matz, LM Hill, HH Beegle, LW Kanik, I AF Matz, LM Hill, HH Beegle, LW Kanik, I TI Investigation of drift gas selectivity in high resolution ion mobility spectrometry with mass spectrometry detection SO JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY LA English DT Article ID ELECTROSPRAY-IONIZATION; SEPARATION; RANGE AB Recent studies in electrospray ionization (ESI)/ion mobility spectrometry (IMS) have focussed on employing different drift gases to alter separation efficiency for some molecules. This study investigates four structurally similar classes of molecules (cocaine and metabolites, amphetamines, benzodiazepines, and small peptides) to determine the effect of structure on relative mobility changes in four drift gases (helium, nitrogen, argon, carbon dioxide). Collision cross sections were plotted against drift gas polarizability and a linear relationship was found for the nineteen compounds evaluated in the study. Based on the reduced mobility database, all nineteen compounds could be separated in one of the four drift gases, however, the drift gas that provided optimal separation was specific for the two compounds. (C) 2002 American Society for Mass Spectrometry. C1 Washington State Univ, Dept Chem, Pullman, WA 99164 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Hill, HH (reprint author), Washington State Univ, Dept Chem, POB 644630, Pullman, WA 99164 USA. RI Beegle, Luther/A-6354-2010 FU NIDA NIH HHS [8RO3DA1192302] NR 33 TC 56 Z9 57 U1 2 U2 18 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 1044-0305 J9 J AM SOC MASS SPECTR JI J. Am. Soc. Mass Spectrom. PD APR PY 2002 VL 13 IS 4 BP 300 EP 307 AR PII S1044-0305(01)00366-X DI 10.1016/S1044-0305(01)00366-X PG 8 WC Chemistry, Analytical; Chemistry, Physical; Spectroscopy SC Chemistry; Spectroscopy GA 539AY UT WOS:000174848300002 PM 11951967 ER PT J AU Stern, DP AF Stern, DP TI Systematic identification of preferred orbits for magnetospheric missions: 2. The "profile" constellation SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB Using orbital criteria developed in Part I of this study (Stern, [1]), a "Profile" constellation mission is developed for studying the Earth's magnetosphere. The basic "Profile" has six satellites in each of two close orbits with apogee 25R(E) or 20R(E), (Earth radii, 1 R-E = 6371 km), but it can be extended to a "Twin Profile" mission with two coplanar constellations (total of twenty-four spacecraft), covering the magnetosphere end-to-end and requiring only one launch. One constellation of twelve then has apogee at midnight (or at other times, dusk), the other at noon (or dawn), and the two exchange positions every six months. The small satellites (17 kg, 29 w) will measure magnetic fields, ion and electron energy spectra, and plasma bulk flows. They require a minimal Deltav and can therefore be flung off in pairs from a spinning mother ship, assuring a scientifically desirable spin axis and other benefits. Simulation codes derive the week-by-week coverage of ten magnetospheric regions by the twelve satellites, as well as the annual number of hours certain formations occur, e.g. ten+ satellites within 2R(E) of the tail's neutral sheet. Of particular interest is the tight clustering of six to twelve satellites at r > 23R(E) (for 25R(E) apogee), enhancing (at various times) local coverage of the substorm reconnection region, low latitude boundary layer and bow shock. The article concludes with a list of thirty targeted scientific investigations, each with its appropriate formation. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Stern, DP (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Code 695, Greenbelt, MD 20771 USA. NR 6 TC 0 Z9 0 U1 0 U2 2 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 USA SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD APR-JUN PY 2002 VL 50 IS 2 BP 149 EP 171 PG 23 WC Engineering, Aerospace SC Engineering GA 679TX UT WOS:000182939000002 ER PT J AU Hanna, JL Tolson, RH AF Hanna, JL Tolson, RH TI Approaches to autonomous aerobraking at Mars SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article; Proceedings Paper CT AAS/AIAA Astrodynamics Specialists Conference CY JUL 30-AUG 02, 2001 CL QUEBEC CITY, CANADA SP Amer Astronaut Soc, Amer Inst Aeronaut & Astronaut AB Planetary atmospheric aerobraking will most likely be incorporated in every future Mars orbiting mission. Aerobraking requires an intensive workload during operations. To provide safe and efficient aerobraking, both navigation and spacecraft system teams must be extremely diligent in updating spacecraft sequences and performing periapsis raise or lower maneuvers to maintain the required orbital energy reduction without exceeding the design limits of the spacecraft. Automating the process with onboard measurements could significantly reduce the operational burden and, in addition, could reduce the potential for human error. Two levels of automation are presented and validated using part of the Mars Global Surveyor aerobraking sequence and a simulated Mars Odyssey sequence. The simplest method only provides the capability to update the onboard sequence. This method uses onboard accelerometer measurements to estimate the change in orbital period during an aerobraking pass and thereby estimates the beginning of the next acrobraking sequence. Evaluation of the method utilizing MGS accelerometer data showed that the time of the next periapsis can be estimated to within 25% 3sigma of the change in the orbital period due to drag. The second approach provides complete onboard orbit propagation. A low-order gravity model is proposed that is sufficient to provide periapsis altitude predictions to within 100-200 meters over three orbits. Accelerometer measurements are used as part of the trajectory force model while the spacecraft is in the atmosphere. C1 NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. George Washington Univ, Joint Inst Adv Flight Sci, NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Hanna, JL (reprint author), NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, MS 365, Hampton, VA 23681 USA. NR 10 TC 1 Z9 2 U1 0 U2 0 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 USA SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD APR-JUN PY 2002 VL 50 IS 2 BP 173 EP 189 PG 17 WC Engineering, Aerospace SC Engineering GA 679TX UT WOS:000182939000003 ER PT J AU Dwyer, AM Tolson, RH Munk, MM Tartabini, PV AF Dwyer, AM Tolson, RH Munk, MM Tartabini, PV TI Development of a Monte Carlo Mars-gram model for 2001 Mars Odyssey aerobraking simulations SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article; Proceedings Paper CT AAS/AIAA Astrodynamics Specialists Conference CY JUL 30-AUG 02, 2001 CL QUEBEC CITY, CANADA SP Amer Astronaut Soc, Amer Inst Aeronaut & Astronaut ID GLOBAL SURVEYOR AEROBRAKING AB Atmospheric density data taken during the Mars Global Surveyor aerobraking mission (1997-1999) showed significant variability over the altitude ranges (100-140 km) of interest for aerobraking. This paper presents the method by which Mars Global Surveyor data were used to determine the statistical distribution of mean density and the amplitude and phase of stationary atmospheric waves as a function of latitude. The combination of mean density and waves produced a good fit to the observed data. Using this information, a model was developed to implement the variations into Monte Carlo simulations for future missions to Mars, specifically the Mars Odyssey aerobraking mission (October, 2001-January, 2002). An example of Monte Carlo results for the Mars Odyssey aerobraking mission is shown. C1 NASA, Langley Res Ctr, Vehicle Anal Branch, Hampton, VA 23665 USA. George Washington Univ, Sch Engn & Appl Sci, JIAFS, NASA,Langley Res Ctr, Hampton, VA 23605 USA. RP Dwyer, AM (reprint author), NASA, Langley Res Ctr, Vehicle Anal Branch, Hampton, VA 23665 USA. NR 9 TC 2 Z9 2 U1 0 U2 0 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 USA SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD APR-JUN PY 2002 VL 50 IS 2 BP 191 EP 211 PG 21 WC Engineering, Aerospace SC Engineering GA 679TX UT WOS:000182939000004 ER PT J AU Smart, MC Ratnakumar, BV Surampudi, S AF Smart, MC Ratnakumar, BV Surampudi, S TI Use of organic esters as cosolvents in electrolytes for lithium-ion batteries with improved low temperature performance SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID CELLS; INTERCALATION; GRAPHITE AB The electrolyte composition plays a strong role in determining the low temperature performance of lithium-ion cells, both in terms of ionic mobility in the electrolyte solution, as well as forming suitable surface films on the electrode surfaces. A series of ester solvents was chosen for incorporation into multicomponent electrolyte formulations due to their favorable physiochemical properties (i.e., low viscosity, low melting point, and high permittivity!, as well as good compatibility with carbonaceous anodes and mixed metal cathodes (i.e., LiCoO2 and LiNiCoO2). In addition to determining the relative facility of lithium intercalation and deintercalation in Li-carbon cells as a function of temperature, a number of conventional electrochemical methods were employed to further enhance the understanding of the nature of the electrode surface films in these ester-based electrolytes, including dc polarization and ac impedance measurements. A distinct trend was observed with respect to the stability of the surface films formed. In solutions containing low molecular weight cosolvents (i.e., methyl acetate and ethyl acetate! the surface films appear resistive and inadequately protective, whereas electrolytes containing higher molecular weight esters resulted in surface films with more desirable attributes. Promising electrolyte formulations were further evaluated in prototype lithium-ion cells (AA-size) and fully characterized in terms of their low temperature discharge performance. (C) 2002 The Electrochemical Society. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Smart, MC (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 22 TC 77 Z9 80 U1 3 U2 46 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 65 SOUTH MAIN STREET, PENNINGTON, NJ 08534 USA SN 0013-4651 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD APR PY 2002 VL 149 IS 4 BP A361 EP A370 DI 10.1149/1.1453407 PG 10 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA 532XE UT WOS:000174499700002 ER PT J AU Xu, YH Jeevarajan, AS Fay, JM Taylor, TD Anderson, MM AF Xu, YH Jeevarajan, AS Fay, JM Taylor, TD Anderson, MM TI On-line measurement of glucose in a rotating wall perfused vessel bioreactor using an amperometric glucose sensor SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID CHEMICAL SENSORS; BIOSENSOR; INJECTION; SYSTEM; LACTATE AB A high performance, long-term, stable glucose sensor was developed and evaluated for continuous measurement of glucose for use in National Aeronautics and Space Administration space bioreactors while using a rotating wall perfused vessel system to support a baby hamster kidney (BHK-21) cell culture. The sensor employs a glucose oxidase multilayered membrane with a hydrogen peroxide electrode system. The output of the sensor was converted to glucose concentration utilizing the two-point calibration method. The sensor, tested over four 30 day bioreactor cell runs, showed a steady-state response time of less than 15 min. The sensor was able to measure glucose continuously and accurately for 16 days while using a single calibration and 30 days using two sets of calibrations, resulting in a standard error of prediction of +/-0.5 mM as against a benchtop Beckman glucose analyzer. Evaluation conditions like cell culture pH, incubator temperature conditions, and operational flow rate, were found to have a very little effect on the sensor performance. (C) 2002 The Electrochemical Society. C1 Wyle Life Sci, Houston, TX 77058 USA. NASA, Cellular Biotechnol Program, Houston, TX 77058 USA. RP Xu, YH (reprint author), Wyle Life Sci, Houston, TX 77058 USA. NR 22 TC 7 Z9 7 U1 0 U2 6 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 65 SOUTH MAIN STREET, PENNINGTON, NJ 08534 USA SN 0013-4651 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD APR PY 2002 VL 149 IS 4 BP H103 EP H106 DI 10.1149/1457990 PG 4 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA 532XE UT WOS:000174499700060 ER PT J AU Li, XF Sui, CH Lau, KM AF Li, XF Sui, CH Lau, KM TI Precipitation efficiency in the tropical deep convective regime: A 2-D cloud resolving modeling study SO JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN LA English DT Article ID DIURNAL-VARIATIONS; WATER-BUDGET; SQUALL LINE; TOGA COARE; MESOSCALE AB Precipitation efficiency in the tropical deep convective regime is analyzed based on the hourly data from a 2-D cloud resolving simulation. The cloud resolving model is forced by the large-scale vertical velocity, zonal wind and large-scale horizontal advections derived from TOGA COARE for a 20-day period. Large-scale precipitation efficiency (LSPE) is defined as a ratio of surface rain rate to the sum of surface evaporation and moisture convergence, and cloud-microphysics precipitation efficiency (CMPE) is defined as a ratio of surface rain rate to the sum of condensation and deposition rates of supersaturated vapor. Moisture budget shows that the local atmospheric moisture gains (loses) when the LSPE is less (more) than 100%. The LSPE could be larger than 100% for strong convection. This suggests that in order to avoid moisture bias, the cumulus parameterization schemes used in general circulation models should allow the precipitation rate to be larger than the sum of surface evaporation and moisture convergence in strong convective region. Statistical analysis shows that the LSPE is about 80% of the CMPE when it is less than 60%, and the CMPE is a constant of about 70% when the LSPE is more than 60%. The CMPE increases with increasing mass-weighted mean temperature and increasing surface rain rate. This suggests that precipitation is more efficient for warm environment and strong convection. C1 NOAA, NESDIS, ORA, ARAD, Camp Springs, MD 20746 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Li, XF (reprint author), NOAA, NESDIS, ORA, ARAD, 5200 Auth Rd,Room 601, Camp Springs, MD 20746 USA. EM Xiaofan.Li@noaa.gov RI Li, Xiaofan/F-5605-2010; Li, Xiaofan/G-2094-2014; Lau, William /E-1510-2012; OI Lau, William /0000-0002-3587-3691; SUI, CHUNG-HSIUNG/0000-0003-2842-5660 NR 26 TC 48 Z9 50 U1 0 U2 5 PU METEOROLOGICAL SOC JAPAN PI TOKYO PA C/O JAPAN METEOROLOGICAL AGENCY 1-3-4 OTE-MACHI, CHIYODA-KU, TOKYO, 100-0004, JAPAN SN 0026-1165 EI 2186-9057 J9 J METEOROL SOC JPN JI J. Meteorol. Soc. Jpn. PD APR PY 2002 VL 80 IS 2 BP 205 EP 212 DI 10.2151/jmsj.80.205 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 563PB UT WOS:000176263800005 ER PT J AU Daryabeigi, K AF Daryabeigi, K TI Heat transfer in adhesively bonded honeycomb core panels SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB The influence of adhesive thickness and thermal properties on the overall heat transfer through an adhesively bonded honeycomb core panel over the temperature range of 250-500 K was investigated. The combined radiation and conduction heat transfer was modeled using a finite volume numerical formulation. The numerical model was validated by comparison with published experimental effective thermal conductivity measurements. It was found that the adhesive layer could cause significant augmentation of heat transfer through the honeycomb panel. A parametric study was conducted to investigate the influence of adhesive thickness, thermal conductivity and emissivity, on the overall heat transfer through the panel. C1 NASA, Langley Res Ctr, Met & Thermal Struct Branch, Hampton, VA 23681 USA. RP Daryabeigi, K (reprint author), NASA, Langley Res Ctr, Met & Thermal Struct Branch, Hampton, VA 23681 USA. NR 20 TC 10 Z9 12 U1 1 U2 9 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD APR-JUN PY 2002 VL 16 IS 2 BP 217 EP 221 DI 10.2514/2.6687 PG 5 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA 543NF UT WOS:000175107500008 ER PT J AU Van Zante, DE Adamczyk, JJ Strazisar, AJ Okiishi, TH AF Van Zante, DE Adamczyk, JJ Strazisar, AJ Okiishi, TH TI Wake recovery performance benefit in a high-speed axial compressor SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 46th International Congress and Exhibition on Gas Turbines and Aeroengines CY JUN 04-07, 2001 CL NEW ORLEANS, LOUISIANA AB Rotor wakes are an important source of loss in axial compressors. The decay rate of a rotor wake is largely due to both mixing (results in loss) and stretching (no loss accrual). Thus, the actual loss associated with rotor wake decay will vary in proportion to the amounts of mixing and stretching involved. This wake stretching process, referred to by Smith (1996) as recovery, is reversible and for a 2-D rotor wake leads to an inviscid reduction of the velocity deficit of the wake. It will be shown that for the rotor/stator spacing typical of core compressors, wake stretching is the dominant wake decay process within the stator with viscous mixing playing only a secondary role. A model for the rotor 1 wake decay process is developed and used to quantify the viscous dissipation effects relative to those of inviscid wake stretching. The model is verified using laser anemometer measurements acquired in the wake of a transonic rotor operated alone and in a stage configuration at near peak efficiency and near stall operating conditions. Results from the wake decay model exhibit good agreement with the experimental data. Data from the model and laser anemometer measurements indicate that rotor wake straining (stretching) is the primary decay process in the stator passage. Some implications of these results on compressor stage design are discussed. C1 Iowa State Univ, Ames, IA 50011 USA. NASA Glenn Res Ctr, Cleveland, OH 44135 USA. RP Van Zante, DE (reprint author), Iowa State Univ, Ames, IA 50011 USA. NR 26 TC 27 Z9 27 U1 2 U2 2 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD APR PY 2002 VL 124 IS 2 BP 275 EP 284 DI 10.1115/1.1445793 PG 10 WC Engineering, Mechanical SC Engineering GA 547PQ UT WOS:000175341300017 ER PT J AU Jow, KG Dingemans, TJ AF Jow, KG Dingemans, TJ TI Liquid crystals derived from 2-phenylisoindoles: synthesis and characterization SO LIQUID CRYSTALS LA English DT Article ID TAILS AB 2-Phenylisoindole was investigated as the rigid core unit in a series of asymmetric mesogenic molecules. When the 2-phenylisoindole core was terminated with a hexyl tail, no mesophase formation could be observed. When 4-n-(tridecafluorohexyl) was used, however, both monotropic and enantiotropic phase behaviour were observed. It was found that most functionalities at the anhydride 5-position results in the formation of smectic A (SmA) phases in the temperature range 70-180degreesC. Functionalities at the anhydride 4-position suppress mesophase formation. Large substituents (-Br, -NO2) and symmetric substitution patterns (5,6-dichloro,4,7-dichloro and 4,5,6,7-tetrachloro) on the anhydride moiety increase the melting point and destabilize the mesophase. Temperature dependent X-ray diffraction experiments suggest an interdigitated SmA packing for this family of compounds. C1 NASA, ICASE, Langley Res Ctr, Hampton, VA 23681 USA. MIT, Dept Mat Sci & Engn, Cambridge, MA 02139 USA. RP Dingemans, TJ (reprint author), NASA, ICASE, Langley Res Ctr, Mail Stop 132C,3 W Reid St, Hampton, VA 23681 USA. RI Dingemans, Theo/E-3532-2017 NR 11 TC 5 Z9 5 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 0267-8292 J9 LIQ CRYST JI Liq. Cryst. PD APR PY 2002 VL 29 IS 4 BP 573 EP 581 DI 10.1080/02678290110116213 PG 9 WC Chemistry, Multidisciplinary; Crystallography; Materials Science, Multidisciplinary SC Chemistry; Crystallography; Materials Science GA 531HT UT WOS:000174410500012 ER PT J AU Baker, JD Johanos, TC AF Baker, JD Johanos, TC TI Effects of research handling on the endangered Hawaiian monk seal SO MARINE MAMMAL SCIENCE LA English DT Article DE Hawaiian monk seal; Monachus scbauinslandi; handling effects; endangered species ID ANTARCTIC FUR SEALS; MONACHUS-SCHAUINSLANDI; BEHAVIOR AB We examined the effects of research handling on free-ranging endangered Hawaiian monk seals, Monachus schauinslandi. by analyzing differences in subsequent year survival, migration, and condition between handled seals and controls during 1983-1998. Each of 549 handled seals was matched to a control seal of the same age, sex, location, and year. Handling included instrumentation with telemetry devices (n = 93), blood sampling (n = 19), and tagging (n = 437). No significant differences were found between handled seals and their controls in one-year resighting rates, observed migration rates, or condition. Resighting rates of handled and control seals were high (80%-100%). Available sample sizes were sufficient to detect reasonably small (9%-20%) differences in resighting rates had they existed among instrumented or tagged seals and controls (alpha = 0.05, power = 0.90). Too few seals were captured for blood sampling to detect even large differences in their resighting rates. However, blood samples were drawn from most instrumented seals, and there was no indication that this larger group suffered harmful effects. Duration of restraint during flipper tagging had no effect on subsequent probability of resighting. Our analysis suggests that conservative selection procedures and careful handling techniques have no deleterious effects on Hawaiian monk seals. C1 Natl Marine Fisheries Serv, Honolulu Lab, Honolulu, HI 96822 USA. RP Baker, JD (reprint author), Natl Marine Fisheries Serv, Honolulu Lab, 2570 Dole St, Honolulu, HI 96822 USA. NR 25 TC 24 Z9 28 U1 0 U2 13 PU SOC MARINE MAMMALOGY PI LAWRENCE PA 1041 NEW HAMPSHIRE ST, LAWRENCE, KS 66044 USA SN 0824-0469 J9 MAR MAMMAL SCI JI Mar. Mamm. Sci. PD APR PY 2002 VL 18 IS 2 BP 500 EP 512 DI 10.1111/j.1748-7692.2002.tb01051.x PG 13 WC Marine & Freshwater Biology; Zoology SC Marine & Freshwater Biology; Zoology GA 544MK UT WOS:000175164000012 ER PT J AU Schmidt, GA Mulitza, S AF Schmidt, GA Mulitza, S TI Global calibration of ecological models for planktic foraminifera from coretop carbonate oxygen-18 SO MARINE MICROPALEONTOLOGY LA English DT Article DE planktic foraminifera; seawater delta O-18; carbonate delta O-18; marine sediments ID STABLE-ISOTOPE VARIABILITY; DEEP-WATER FLUXES; PALEOCEANOGRAPHIC SIGNIFICANCE; VERTICAL-DISTRIBUTION; SEASONAL SUCCESSION; SARGASSO SEA; TEMPERATURE; TRACERS; PACIFIC; OCEAN AB A global dataset of coretop planktic foraminiferal delta(18)O(c) is combined with a global database of seawater delta(18)O(w) observations and ocean climatologies to determine robust optimum parameters for an ecological model for six commonly measured species and varieties. These parameters consist of the temperature ranges. optimum temperatures, depth habitat. and the amount of secondary calcification for Globigerinoides ruber (white), G. ruber (pink), Neogloboquadrina pachyderma (1). N. pachyderma (r), Globigerinoides sacculifer. and Globigerina bulloides, This approach produces ecological models and temperature ranges consistent with previous work. and manages to reproduce the coretop oxygen-18 carbonate values remarkably well. The standard error of modelled values of coretop calcite globally and for all species is 0.53 parts per thousand, compared to an error of 1.2 parts per thousand when assuming annual average mixed layer equilibrium calcite. (C) 2002 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Ctr Climate Syst Res, New York, NY USA. Univ Bremen, Dept Geosci, Bremen, Germany. RP Mulitza, S (reprint author), NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RI Mulitza, Stefan/G-5357-2011; Schmidt, Gavin/D-4427-2012 OI Mulitza, Stefan/0000-0002-3842-1447; Schmidt, Gavin/0000-0002-2258-0486 NR 33 TC 47 Z9 49 U1 1 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0377-8398 J9 MAR MICROPALEONTOL JI Mar. Micropaleontol. PD APR PY 2002 VL 44 IS 3-4 BP 125 EP 140 AR PII S0377-8398(01)00041-X DI 10.1016/S0377-8398(01)00041-X PG 16 WC Paleontology SC Paleontology GA 566JC UT WOS:000176423100002 ER PT J AU Abdul-Aziz, A Baaklini, GY AF Abdul-Aziz, A Baaklini, GY TI Challenges in integrating nondestructive testing and finite element methods for realistic structural analysis SO MATERIALS EVALUATION LA English DT Article DE finite element analysis; computed tomography; image processing; stress analysis; nondestructive testing AB Capabilities and expertise related to the development of links between nondestructive testing (NDT) and finite element analysis at NASA Glenn Research Center are demonstrated, Current tools to analyze data produced by computed tomography scans are exercised to help assess the damage state in high temperature structural composite materials. A utility translator was written to convert a stereolithographic data file to a suitable computer aided design (CAD) finite element analysis type file. Finite element analyses are carried out with a commercial nonlinear finite element code and the analytical results are discussed. Modeling was established by building a preprocessing and postprocessing finite element package generated model and comparing it to a model generated by the image processing software in conjunction with the preprocessing and postprocessing finite element package. Modeling issues and results are discussed in this paper. The entire process that outlines the tie between the data extracted via NDT and the finite element modeling and analysis is idly described. Furthermore, the advantage of analyzing an NDT produced model versus CAD model is illustrated by showing that NDT offers more details concerning deformities and structural abnormalities that can assist greatly in the structural evaluation of tested components. In CAD modeling, on the other hand, all of the discontinuities have to be artificially modeled. C1 NASA, Glenn Res Ctr, Life Predict Branch, Cleveland, OH 44135 USA. RP Abdul-Aziz, A (reprint author), NASA, Glenn Res Ctr, Life Predict Branch, 21000 Brookpk Rd,MS 6-1, Cleveland, OH 44135 USA. NR 5 TC 0 Z9 0 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 APR PY 2002 VL 60 IS 4 BP 529 EP 534 PG 6 WC Materials Science, Characterization & Testing SC Materials Science GA 539JV UT WOS:000174867500007 ER EF