FN Thomson Reuters Web of Science™ VR 1.0 PT J AU Fowler, LD Wielicki, BA Randall, DA Branson, MD Gibson, GG Denn, FM AF Fowler, LD Wielicki, BA Randall, DA Branson, MD Gibson, GG Denn, FM TI Use of a GCM to explore sampling issues in connection with satellite remote sensing of the Earth radiation budget SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; ICE-CLOUD MICROPHYSICS; ENERGY SYSTEM CERES; PARAMETERIZATION; PARAMETRIZATION; PRECIPITATION; ATMOSPHERE; PROJECT; CLIMATE; LIQUID AB Collocated in time and space, top-of-the-atmosphere measurements of the Earth radiation budget (ERB) and cloudiness from passive scanning radiometers, and lidar- and radar-in-space measurements of multilayered cloud systems, are the required combination to improve our understanding of the role of clouds and radiation in climate. Experiments to fly multiple satellites "in formation" to measure simultaneously the radiative and optical properties of overlapping cloud systems are being designed. Because satellites carrying ERB experiments and satellites carrying lidars- or radars-in space have different orbital characteristics, the number of simultaneous measurements of radiation and clouds is reduced relative to the number of measurements made by each satellite independently. Monthly averaged coincident observations of radiation and cloudiness are biased when compared against more frequently sampled observations due, in particular, to the undersampling of their diurnal cycle. Using the Colorado State University General Circulation Model (CSU GCM), the goal of this study is to measure the impact of using simultaneous observations from the Earth Observing System (EOS) platform and companion satellites flying lidars or radars on monthly averaged diagnostics of longwave radiation, cloudiness, and its cloud optical properties. To do so, the hourly varying geographical distributions of coincident locations between the afternoon EOS (EOS-PM) orbit and the orbit of the ICESAT satellite set to fly at the altitude of 600 km, and between the EOS PM orbit and the orbits of the PICASSO satellite proposed to fly at the altitudes of 485 km (PICA485) or 705 km (PICA705), are simulated in the CSU GCM for a 60-month time period starting at the idealistic July 1, 2001, launch date. Monthly averaged diagnostics of the top-of-the-atmosphere, atmospheric, and surface longwave radiation budgets and clouds accumulated over grid boxes corresponding to satellite overpasses are compared against monthly averaged diagnostics obtained from hourly samplings over the entire globe. Results show that differences between irregularly (satellite) and regularly (true) sampled diagnostics of the longwave net radiative budgets are the greatest at the surface and the smallest in the atmosphere and at the top-of-the-atmosphere, under both cloud-free and cloudy conditions. In contrast, differences between the satellite and the true diagnostics of the longwave cloud radiative forcings are the largest in the atmosphere and at the top-of-the atmosphere, and the smallest at the surface. A poorer diurnal sampling of the surface temperature in the satellite simulations relative to the true simulation contributes a major part to sampling biases in the longwave net radiative budgets, while a poorer diurnal sampling of cloudiness and its optical properties directly affects diagnostics of the longwave cloud radiative forcings. A factor of 8 difference in the number of satellite overpasses between PICA705 and PICA485 and ICESAT leads to a systematic factor of 3 difference in the spatial standard deviations of all radiative and cloudiness diagnostics. C1 Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. Analyt Serv & Mat Inc, Hampton, VA 23666 USA. RP Fowler, LD (reprint author), Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. EM laura@slikrock.atmos.colostate.edu RI Randall, David/E-6113-2011 OI Randall, David/0000-0001-6935-4112 NR 40 TC 5 Z9 5 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 27 PY 2000 VL 105 IS D16 BP 20757 EP 20772 DI 10.1029/2000JD900239 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 350NH UT WOS:000089107600022 ER PT J AU Krasnopolsky, VA Bjoraker, GL AF Krasnopolsky, VA Bjoraker, GL TI Mapping of Mars O-2((1)Delta) dayglow SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID INFRARED MEASUREMENTS; WATER-VAPOR; O-2 DAYGLOW; OZONE; ATMOSPHERE; ABUNDANCE; APHELION; BEHAVIOR; CLIMATE AB We observed the O-2((1)Delta) dayglow at 1.27 mu m near northern midsummer (L-S = 112 degrees) with a long-slit cryogenic echelle spectrograph (CSHELL at the NASA Infrared Telescope Facility) having a resolving power of 4x10(4). The observations resulted in a map of the O-2 dayglow which extends from 1000 to 1645 in local time and from 45 degrees S to 75 degrees N. The O-2 dayglow is formed by photolysis of high-altitude ozone, and this dayglow is the best tracer of seasonal variations in photochemistry at low and middle latitudes. Our observations show that O-2 dayglow can be mapped with existing ground-based instruments. The measured dayglow intensities display a gradual increase from 1.5 MR at 75 degrees N to 2.5 MR at 20 degrees N, a weak minimum of 2.3 MR at the equator, and a steep increase to 5 MR at 35 degrees-40 degrees S. The dayglow in a low-latitude belt from 5 degrees S to 25 degrees N (which is centered between the equator and the subsolar latitude) is maximum at 2.5 MR near 1300 and decreases to 1.5 MR at 1000 and 1645 LT. The observed dayglow intensities are smaller than those calculated using the model of Clancy and Nair [1996] by a factor of approximate to 3. The observation confirms the anticorrelation between ozone and water vapor observed from the Viking orbiters at midsummer. Coupled with the Thermal Emission Spectrometer (TES) observations of temperature, dust, and water vapor, the O-2 dayglow measurements comprise a good database to study Mars' photochemistry and dynamics. C1 Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Krasnopolsky, VA (reprint author), Catholic Univ Amer, Dept Phys, 620 Michigan Ave NE, Washington, DC 20064 USA. RI Bjoraker, Gordon/D-5032-2012; Krasnopolsky, Vladimir/L-5085-2013 NR 30 TC 25 Z9 26 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 AUG 25 PY 2000 VL 105 IS E8 BP 20179 EP 20188 DI 10.1029/2000JE001239 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 348TY UT WOS:000089003600001 ER PT J AU McConnell, JR Arthern, RJ Mosley-Thompson, E Davis, CH Bales, RC Thomas, R Burkhart, JF Kyne, JD AF McConnell, JR Arthern, RJ Mosley-Thompson, E Davis, CH Bales, RC Thomas, R Burkhart, JF Kyne, JD TI Changes in Greenland ice sheet elevation attributed primarily to snow accumulation variability SO NATURE LA English DT Article ID FIRN DENSIFICATION AB The response of grounded ice sheets to a changing climate critically influences possible future changes in sea level. Recent satellite surveys over southern Greenland show little overall elevation change at higher elevations, but large spatial variability(1-3). Using satellite studies alone, it is not possible to determine the geophysical processes responsible for the observed elevation changes and to decide if recent rates of change exceed the natural variability. Here we derive changes in ice-sheet elevation in southern Greenland, for the years 1978-88, using a physically based model of firn densification(4) and records of annual snow accumulation reconstructed from 12 ice cores at high elevation. Our patterns of accumulation-driven elevation change agree closely with contemporaneous satellite measurements of ice-sheet elevation change, and we therefore attribute the changes observed in 1978-88 to variability in snow accumulation. Similar analyses of longer ice-core records show that in this decade the Greenland ice sheet exhibited typical variability at high elevations, well within the long-term natural variability. Our results indicate that a better understanding of ice-sheet mass changes will require long-term measurements of both surface elevation and snow accumulation. C1 Univ & Community Coll Syst Nevada, Desert Res Inst, Reno, NV 89512 USA. Univ Washington, Appl Phys Lab, Seattle, WA 98105 USA. Ohio State Univ, Byrd Polar Res Ctr, Columbus, OH 43210 USA. Ohio State Univ, Dept Geog, Columbus, OH 43210 USA. Univ Missouri, Dept Elect Engn, Columbia, MO 65211 USA. Univ Arizona, Dept Hydrol & Water Resources, Tucson, AZ 85721 USA. NASA, Wallops Flight Facil, EG&G Serv, Wallops Island, VA 23337 USA. Univ Nebraska, Snow & Ice Res Grp, Lincoln, NE 68583 USA. RP McConnell, JR (reprint author), Univ & Community Coll Syst Nevada, Desert Res Inst, Reno, NV 89512 USA. RI Burkhart, John/B-7095-2008 OI Burkhart, John/0000-0002-5587-1693 NR 17 TC 57 Z9 58 U1 1 U2 13 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD AUG 24 PY 2000 VL 406 IS 6798 BP 877 EP 879 DI 10.1038/35022555 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 347AG UT WOS:000088903600040 ER PT J AU Manderson, JP Phelan, BA Stoner, AW Hilbert, J AF Manderson, JP Phelan, BA Stoner, AW Hilbert, J TI Predator-prey relations between age-1 + summer flounder (Paralichthys dentatus, Linnaeus) and age-0 winter flounder (Pseudopleuronectes americanus, Walbaum): predator diets, prey selection, and effects of sediments and macrophytes SO JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY LA English DT Article DE flatfish predator; prey choice; prey size selection; burial; sea grass; sea lettuce ID WINTER FLOUNDER; HABITAT COMPLEXITY; PSEUDOPLEURONECTES-AMERICANUS; PLEURONECTES-PLATESSA; SEDIMENT PREFERENCE; 0-GROUP FLATFISHES; FIELD OBSERVATIONS; JUVENILE PLAICE; LARGEMOUTH BASS; SUMMER FLOUNDER AB Laboratory experiments and weekly trammel net surveys in the Navesink River, New Jersey (USA) were used to examine the predator-prey interaction between age-1 + summer flounder (Paralichthys dentatus) and age-0 winter flounder (Pseudopleuronectes americanus). Winter flounder (24-67 mm TL) were the dominant piscine prey of summer flounder (n = 95, 252-648 mm TL) collected in trammel nets. We observed a temporal shift in summer flounder diets from sand shrimp (Crangon septemspinosa) and winter flounder, dominant during June and early July, to blue crabs (Callinectes sapidus) and other fishes (primarily Atlantic silversides, Menidia menidia and Atlantic menhaden, Brevortia tyrannus) later in the summer. Variations in prey selection appeared to be related to changes in the spatial distribution of predators and spatiotemporal variation in prey availability. In laboratory experiments, summer flounder (271-345 mm total length, TL) preferred demersal winter flounder to a pelagic fish (Atlantic silversides) and a benthic invertebrate (sand shrimp) prey, and the vulnerability of winter flounder increased with increasing prey body size from 20 to 90 mm TL. Experiments testing habitat effects showed that mortality of winter flounder in three different size classes (20-29, 40-49, 60-69 mm TL) was not influenced by sediment grain sizes permitting differential burial of the prey. However, vegetation enhanced survival, with fish suffering lower mortality in eelgrass (Zostera marina, 15+/-0.04%) than in sea lettuce (Ulva lactuca, 38+/-0.04%) or bare sand (70+/-0.07%) when the macrophytes were planted to produce similar leaf surface areas (5000 cm(2) m(-2)). Prey vulnerability appeared to be related to the role of vision in the predator's attack strategy and prey activity levels. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NOAA, Natl Marine Fisheries Serv, James J Howard Marine Sci Lab, Behav Ecol Branch, Highlands, NJ 07732 USA. RP Manderson, JP (reprint author), NOAA, Natl Marine Fisheries Serv, James J Howard Marine Sci Lab, Behav Ecol Branch, Highlands, NJ 07732 USA. NR 76 TC 71 Z9 74 U1 0 U2 10 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0981 J9 J EXP MAR BIOL ECOL JI J. Exp. Mar. Biol. Ecol. PD AUG 23 PY 2000 VL 251 IS 1 BP 17 EP 39 DI 10.1016/S0022-0981(00)00191-X PG 23 WC Ecology; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 353PN UT WOS:000089284800002 ER PT J AU Zhao, J Buldum, A Han, J Lu, JP AF Zhao, J Buldum, A Han, J Lu, JP TI First-principles study of Li-intercalated carbon nanotube ropes SO PHYSICAL REVIEW LETTERS LA English DT Article ID AB-INITIO; PSEUDOPOTENTIALS; LITHIUM; ATOMS AB We studied Li-intercalated carbon nanotube ropes by first-principles methods. Results show charge transfer between Li and C and small structural deformation due to intercalation. Both the interior of the nanotube and the interstitial space are susceptible for intercalation. The Li intercalation potential of a single-walled nanotube rope is comparable to that of graphite and almost independent of the Li density up to around LiC2. as observed in recent experiments. This density is significantly higher than that of Li-intercalated graphite, making the nanorope a premising. candidate for the anode material in battery applications. C1 Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA. EM zhaoj@physics.unc.edu; jpl@physics.unc.edu RI Zhao, Jijun/I-6030-2015 NR 24 TC 224 Z9 234 U1 8 U2 63 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 EI 1079-7114 J9 PHYS REV LETT JI Phys. Rev. Lett. PD AUG 21 PY 2000 VL 85 IS 8 BP 1706 EP 1709 DI 10.1103/PhysRevLett.85.1706 PG 4 WC Physics, Multidisciplinary SC Physics GA 345ZT UT WOS:000088846100031 ER PT J AU Cerf, NJ Ipe, A Rottenberg, X AF Cerf, NJ Ipe, A Rottenberg, X TI Cloning of continuous quantum variables SO PHYSICAL REVIEW LETTERS LA English DT Article ID ERROR-CORRECTION AB The cloning of quantum variables with continuous spectra is analyzed. A Gaussian quantum cloning machine is exhibited that copies equally well the states of two conjugate variables such as position and momentum. It also duplicates all coherent states with a fidelity of 2/3. More generally, the copies are shown to obey a no-cloning Heisenberg-like uncertainty relation. C1 Free Univ Brussels, Ecole Polytech, B-1050 Brussels, Belgium. CALTECH, Jet Prop Lab, Informat & Comp Technol Res Sect, Pasadena, CA 91109 USA. RP Cerf, NJ (reprint author), Free Univ Brussels, Ecole Polytech, CP 165, B-1050 Brussels, Belgium. NR 16 TC 166 Z9 171 U1 0 U2 9 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD AUG 21 PY 2000 VL 85 IS 8 BP 1754 EP 1757 DI 10.1103/PhysRevLett.85.1754 PG 4 WC Physics, Multidisciplinary SC Physics GA 345ZT UT WOS:000088846100043 ER PT J AU Nesbitt, JA AF Nesbitt, JA TI Thermal modeling of various thermal barrier coatings in a high heat flux rocket engine SO SURFACE & COATINGS TECHNOLOGY LA English DT Article DE thermal barrier coatings; thermal modeling; cermet coatings ID RESIDUAL-STRESSES AB One- and two-dimensional thermal models were developed to predict the thermal response of tubes with and without thermal barrier coatings (TBCs) tested for short durations in a H-2/O-2 rocket engine. Temperatures were predicted using median thermophysical property data for traditional air plasma sprayed ZrO2-Y2O3 TBCs, as well as air plasma sprayed and low pressure plasma sprayed ZrO2-Y2O3/NiCrAlY cermet coatings. Good agreement was observed between predicted and measured metal temperatures. It was also shown that the variation in the reported values of the thermal conductivity of plasma sprayed ZrO2-Y2O3 coatings can result in temperature differences of up to 180 degrees C at the ceramic/metal interface. In contrast, accounting for the presence of the bond coat or radiation from the ceramic layer had only a small effect on substrate temperatures (< 20 degrees C). The thermal models were also used to show that for the short duration test conditions of this study, a 100 mu m thick ZrO2-Y2O3 coating would provide a metal temperature benefit of approximately 300 degrees C over an uncoated tube while a 200 mu m thick coating would provide a benefit greater than 500 degrees C. The difference in the thermal response between tubes and rods was also predicted and used to explain the previously-observed increased life of TBCs on rods over that on tubes. (C) 2000 Elsevier Science S.A. All rights reserved. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Nesbitt, JA (reprint author), NASA, Glenn Res Ctr, MS 106-1,21000 Brooklyn Rd, Cleveland, OH 44135 USA. NR 29 TC 15 Z9 17 U1 0 U2 13 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0257-8972 J9 SURF COAT TECH JI Surf. Coat. Technol. PD AUG 21 PY 2000 VL 130 IS 2-3 BP 141 EP 151 DI 10.1016/S0257-8972(00)00723-4 PG 11 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA 340UJ UT WOS:000088553100001 ER PT J AU Allamandola, LJ AF Allamandola, LJ TI From interstellar polycyclic aromatic hydrocarbons and ice to early solar system chemistry and perhaps the origin of life. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Ames Res Lab, 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 AUG 20 PY 2000 VL 220 MA 17-GEOC BP U406 EP U406 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 386XU UT WOS:000166091202158 ER PT J AU Desch, S Kress, M Dateo, C Huo, W AF Desch, S Kress, M Dateo, C Huo, W TI Signatures of disequilibrium chemistry in the solar nebula. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Ames Res Lab, 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 AUG 20 PY 2000 VL 220 MA 8-GEOC BP U405 EP U405 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 386XU UT WOS:000166091202149 ER PT J AU Duraj, SA Browne, R Al-Fawaz, A Ye, L Wolf, J Hepp, AF Harris, JD Fanwick, PE AF Duraj, SA Browne, R Al-Fawaz, A Ye, L Wolf, J Hepp, AF Harris, JD Fanwick, PE TI Recent synthetic studies of Ga and In compounds from our laboratories. 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, Greenbelt, MD 20771 USA. Purdue Univ, W Lafayette, IN 47907 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 AUG 20 PY 2000 VL 220 MA 439-INOR BP U518 EP U518 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 386XU UT WOS:000166091202802 ER PT J AU Ferrante, RF Moore, MH Nuth, JA Smith, T AF Ferrante, RF Moore, MH Nuth, JA Smith, T TI Laboratory studies of catalysis of CO to organics on cosmic grain analogs. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 USN Acad, Dept Chem, Annapolis, MD 21402 USA. NASA, Goddard Space Flight Ctr, Astrochem Branch, Greenbelt, MD USA. Univ Maryland, College Pk, MD 20742 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 AUG 20 PY 2000 VL 220 MA 3-GEOC BP U404 EP U404 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 386XU UT WOS:000166091202144 ER PT J AU Gerakines, PA Moore, MH Hudson, RL AF Gerakines, PA Moore, MH Hudson, RL TI Energetic processing of HCN-bearing ices in the laboratory. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Goddard Space Flight Ctr, Astrochem Branch, Greenbelt, MD 20771 USA. Eckerd Coll, Dept Chem, St Petersburg, FL USA. RI Gerakines, Perry/B-9705-2009; Hudson, Reggie/E-2335-2012 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 AUG 20 PY 2000 VL 220 MA 2-GEOC BP U404 EP U404 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 386XU UT WOS:000166091202143 ER PT J AU Jaffe, RL AF Jaffe, RL TI Chemical modification of carbon nanotube sidewalls: Quantum chemistry calculations and molecular simulations. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Computat Chem Branch, Moffett Field, CA 94035 USA. 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 AUG 20 PY 2000 VL 220 MA 148-IEC BP U434 EP U434 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 386XU UT WOS:000166091202324 ER PT J AU Klein, DJ Bryant, RG AF Klein, DJ Bryant, RG TI Synthesis and characterization of polyimides prepared from sulfone, carbonyl, and phosphine oxide-containing diamines. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Langley Res Ctr, Adv Mat & Proc Branch, Hampton, VA 23681 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 AUG 20 PY 2000 VL 220 MA 137-POLY BP U275 EP U275 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 386XV UT WOS:000166091301536 ER PT J AU Kounaves, SP Buehler, MG Hecht, MH West, SJ AF Kounaves, SP Buehler, MG Hecht, MH West, SJ TI Electrochemical sensor array for determination of trace metal geochemistry on Mars. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Tufts Univ, Dept Chem, Pearson Chem Lab, Medford, MA 02155 USA. Jet Prop Lab, Pasadena, CA USA. Orion Res Inc, Beverly, MA 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 AUG 20 PY 2000 VL 220 MA 10-ENVR BP U317 EP U317 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 386XU UT WOS:000166091201632 ER PT J AU Thompson, KG Benicewicz, BC AF Thompson, KG Benicewicz, BC TI Corrosion-protective coatings from electroactive polymers. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, John F Kennedy Space Ctr, Kennedy Space Ctr, FL 32899 USA. Rensselaer Polytech Inst, Ctr Polymer Synthesis, Troy, NY USA. Rensselaer Polytech Inst, Dept Chem, Troy, NY 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 AUG 20 PY 2000 VL 220 MA 19-POLY BP U248 EP U248 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 386XV UT WOS:000166091301418 ER PT J AU Williams, MK Nelson, GL Weiser, ES St Clair, TL AF Williams, MK Nelson, GL Weiser, ES St Clair, TL TI Comparative characterization study of the properties, including degradation, of high temperature polyimide foams. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Div Mat Sci, Kennedy Space Ctr, FL 32899 USA. Florida Inst Technol, Coll Liberal Arts & Sci, Melbourne, FL USA. NR 0 TC 0 Z9 0 U1 1 U2 3 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 AUG 20 PY 2000 VL 220 MA 9-PMSE BP U329 EP U329 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 386XV UT WOS:000166091301874 ER PT J AU Storzer, H Hollenbach, D AF Storzer, H Hollenbach, D TI Optical line emission from photodissociation regions SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; galaxies : ISM; ISM : clouds; ISM : individual (Orion Nebula); line : formation; stars : formation ID PHOTOEVAPORATING CIRCUMSTELLAR DISKS; PHOTON-DOMINATED REGIONS; ORION NEBULA; PLANETARY-NEBULAE; PHYSICAL CONDITIONS; INFRARED-EMISSION; IONIZATION FRONTS; MOLECULAR CLOUDS; HYDROGEN; MODELS AB We present a parameter study for the optical, low-ionization [O I] lambda 6300, lambda 6363, and lambda 5577 and the [S II] lambda 6731 and lambda 6716 lines emitted by photodissociation regions (PDRs). We assume in these models that the PDR has a plane-parallel, semi-infinite geometry and is illuminated from one side. The PDR models are characterized by the total hydrogen density 10(4) cm(-3) less than or equal to n less than or equal to 10(7) cm(-3) and the strength of the FUV held G(0) in terms of the Habing held 10(3) < G(0) < 10(7). Oxygen and singly ionized sulfur are excited thermally in the outer hot PDR layers due to collisions with electrons and atomic hydrogen. [O I] photons are also produced in the photodissociation of OH. We apply the results of the parameter study to the protoplanetary disks in Orion, layers between H n regions and molecular clouds, low-ionization nuclear emission-line regions, T Tauri stars, and planetary nebulae. We discuss the extent to which PDRs dominate or contribute to the observed [O I] and [S II] emission in these different objects. C1 Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Storzer, H (reprint author), NASA, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. NR 42 TC 19 Z9 19 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP 751 EP 759 DI 10.1086/309251 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AY UT WOS:000089252600023 ER PT J AU Latter, WB Dayal, A Bieging, JH Meakin, C Hora, JL Kelly, DM Tielens, AGGM AF Latter, WB Dayal, A Bieging, JH Meakin, C Hora, JL Kelly, DM Tielens, AGGM TI Revealing the photodissociation region: HST/NICMOS imaging of NGC 7027 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : molecules; ISM : structure; molecular processes; planetary nebulae : general; planetary nebulae : individual (NGC 7027) ID PLANETARY-NEBULA NGC-7027; NEAR-INFRARED PROPERTIES; MOLECULAR-HYDROGEN; BIPOLAR NEBULAE; STARS; H-2; MORPHOLOGY; EVOLUTION; ENVELOPES; AFGL-2688 AB We report results from a Hubble Space Telescope (HST) and Near-Infrared Camera and Multiobject Spectrometer (NICMOS) program to study the distribution of hot neutral (molecular hydrogen) and ionized circumstellar material in the young planetary nebulae NGC 7027. HST/NICMOS provided very high spatial resolution imaging in line and continuum emission, and the stability and large dynamic range needed for investigating detailed structures in the circumstellar material. We present dramatic new images of NGC 7027 that have led to a new understanding of the structure in this important planetary nebula. The central star is clearly revealed, providing near-infrared fluxes that are used to directly determine the stellar temperature very accurately (T* = 198,000 K). It is found that the photodissociation layer as revealed by near-infrared molecular hydrogen emission is very thin (Delta R similar to 6 x 10(15) cm) and is biconical in shape. The interface region is structured and filamentary, suggesting the existence of hydrodynamic instabilities. We discuss evidence for the presence of one or more highly collimated, off-axis jets that might be present in NGC 7027. The NICMOS data are combined with earlier Hubble Space Telescope data to provide a complete picture of NGC 7027 using the highest spatial resolution data to date. The evolutionary future of NGC 7027 is discussed. C1 CALTECH, SIRTF Sci Ctr, IPAC, Pasadena, CA 91125 USA. Ctr Infrared Proc & Anal, Pasadena, CA USA. Jet Prop Lab, Pasadena, CA 91109 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Wyoming, Laramie, WY 82071 USA. Univ Groningen, Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands. RP Latter, WB (reprint author), CALTECH, SIRTF Sci Ctr, IPAC, MS 314-6, Pasadena, CA 91125 USA. EM latter@ipac.caltech.edu; adayal@ipac.caltech.edu; jbieging@as.arizona.edu; cmeakin@as.arizona.edu; jhora@cfa.harvard.edu; dkelly@as.arizona.edu; tielens@astro.rug.nl OI Hora, Joseph/0000-0002-5599-4650 NR 54 TC 63 Z9 63 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP 783 EP 797 DI 10.1086/309252 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AY UT WOS:000089252600027 ER PT J AU Wahlgren, GM Dolk, L Kalus, G Johansson, S Litzen, U Leckrone, DS AF Wahlgren, GM Dolk, L Kalus, G Johansson, S Litzen, U Leckrone, DS TI An optical region elemental abundance analysis of the HgMn type star HR 7775 SO ASTROPHYSICAL JOURNAL LA English DT Review DE stars : abundances; stars : chemically peculiar; stars : individual (HR 7775); stars : peculiar ID MERCURY-MANGANESE STARS; ADDED IUE SPECTRA; NORMAL LATE-B; ABSOLUTE TRANSITION-PROBABILITIES; CHEMICALLY PECULIAR STARS; O-I TRIPLET; CHI-LUPI; OSCILLATOR-STRENGTHS; HYPERFINE-STRUCTURE; AP STARS AB Optical region spectra of the chemically peculiar HgMn type star HR 7775 have been analyzed for the determination of elemental abundances and spectral line identification as a complementary study to the analysis of Hubble Space Telescope Goddard High Resolution Spectrograph spectra. The spectra were obtained with the SOFIN echelle spectrograph on the Nordic Optical Telescope at nominal resolving powers of R = 25,000, 80,000, and 170,000 and signal-to-noise ratios typically in excess of 100:1. The overall nature of the elemental abundance distribution is similar to other cool, HgMn stars; somewhat enhanced abundances for the iron-group elements, with progressively stronger enhancements for heavier elements. Of particular note are the presence of lines from the rare-earth spectra Nd III and Pr III, and the heavy elements Pt, Au, Hg, Tl, and Bi. The isotopic mixture for several lines of mercury and platinum has been investigated. For mercury a possible difference is found between the mixtures as derived from lines of Hg I and Hg II. Three lines of Pt II display the same mixture, which is different from that found from lower excitation lines at ultraviolet wavelengths. We present new laboratory Fourier Transform spectrometer measurements for isotopic and hyperfine structure components of Hg I lambda 4046 and 4358 and Hg II lambda 3984 Angstrom. C1 Lund Univ, Dept Phys, S-22100 Lund, Sweden. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Wahlgren, GM (reprint author), Lund Univ, Dept Phys, Box 118, S-22100 Lund, Sweden. EM Glenn.Wahlgren@fysik.lu.se; Linus.Dolk@fysik.lu.se; Gabriele.Kalus@fysik.lu.se; Sveneric.Johansson@fysik.lu.se; Ulf.Litzen@fysik.lu.se; dleckrone@hst.nasa.gov NR 105 TC 22 Z9 22 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP 908 EP 927 DI 10.1086/309239 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AY UT WOS:000089252600038 ER PT J AU Ashby, MLN Bergin, EA Plume, R Carpenter, JM Melnick, GJ Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Neufeld, DA Patten, BM Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF AF Ashby, MLN Bergin, EA Plume, R Carpenter, JM Melnick, GJ Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Neufeld, DA Patten, BM Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF TI Water abundance and velocity structure in S140, rho Oph A, and B335 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : molecules; radio lines : ISM; stars : formation ID OPHIUCHI DARK CLOUD; STAR-FORMATION; VLA OBSERVATIONS; EMISSION; RATIO; H2O; PROTOSTAR; CLUSTER; REGIONS; CORE AB We present Monte Carlo radiative transfer models for B335, S140, and rho Ophiuchi A that simulate the emission line arising from the 557 GHz 1(10)-->1(01) ground-state transition of ortho-(H2O)-O-16. These models reproduce the line profiles with a combination of turbulent and macroscopic motions, and are consistent with gravitational infall in rho Oph A. We cannot, however, discriminate infall from outflow for S140. Our models are consistent with ortho-H2O abundances relative to H-2 of 2 x 10(-8) and 4.5 x 10(-9) in S140 and rho Oph A, respectively, and an upper limit of 4 x 10(-6) (3 sigma) in B335, assuming the ratio ortho-H-2/para-H-2 = 0.1. We quantify the impact of dust continuum emission on the derived abundances. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. CALTECH, Dept Astron, Pasadena, CA 91125 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Ashby, MLN (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 30 TC 25 Z9 25 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L119 EP L122 DI 10.1086/312845 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700009 ER PT J AU Ashby, MLN Bergin, EA Plume, R Carpenter, JM Neufeld, DA Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Patten, BM Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ AF Ashby, MLN Bergin, EA Plume, R Carpenter, JM Neufeld, DA Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Patten, BM Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ TI An analysis of water line profiles in star formation regions observed by the Submillimeter Wave Astronomy Satellite SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : clouds; ISM : molecules; radio lines : ISM; stars : formation ID MOLECULAR CLOUD CORES; RADIATIVE-TRANSFER; EMISSION; H2O; CO; ABSORPTION; TEMPERATURE; EXCITATION; ORION; MODEL AB We present spectral line profiles for the 557 GHz 1(10)-->1(01) ground-state rotational transition of ortho-(H2O)-O-16 for 18 Galactic star formation regions observed by the Submillimeter Wave Astronomy Satellite. Water is unambiguously detected in every source. The line profiles exhibit a wide variety of shapes, including single-peaked spectra and self-reversed profiles. We interpret these profiles using a Monte Carlo code to model the radiative transport. The observed variations in the line profiles can be explained by variations in the relative strengths of the bulk flow and small-scale turbulent motions within the clouds. Bulk flow (infall, outflow) must be present in some cloud cores, and in certain cases this bulk flow dominates the turbulent motions. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. CALTECH, Dept Astron, Pasadena, CA 91125 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Ashby, MLN (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 33 TC 26 Z9 26 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L115 EP L118 DI 10.1086/312842 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700008 ER PT J AU Bergin, EA Lellouch, E Harwit, M Gurwell, MA Melnick, GJ Ashby, MLN Chin, G Erickson, NR Goldsmith, PF Howe, JE Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF AF Bergin, EA Lellouch, E Harwit, M Gurwell, MA Melnick, GJ Ashby, MLN Chin, G Erickson, NR Goldsmith, PF Howe, JE Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF TI Submillimeter Wave Astronomy Satellite observations of Jupiter and Saturn: Detection of 557 GHz water emission from the upper atmosphere SO ASTROPHYSICAL JOURNAL LA English DT Article DE planets and satellites : individual (Jupiter, Saturn); radio continuum : solar system; radio lines : solar system; submillimeter ID GIANT PLANETS; TEMPERATURES; MILLIMETER; HYDROGEN; OXYGEN; VAPOR AB We have used the Submillimeter Wave Astronomy Satellite to carry out observations on Jupiter and Saturn in two bands centered at 489 and 553 GHz. We detect spectrally resolved 557 GHz H2O emission on both planets, constraining for the first time the residence levels of external water vapor in Jupiter's and Saturn's stratosphere. For both planets, the line appears to be formed at maximum pressures of about 5 mbar. For Jupiter, the data further show that water is not uniformly mixed but increases with altitude above the condensation level. In each planet, the amount of water implied by the data is 1.5-2.5 times larger than inferred from Infrared Space Observatory data. In addition, our observations provide new whole-disk brightness measurements of Jupiter and Saturn near 489 and 553 GHz. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Observ Paris, Dept Rech Spatiale, F-92195 Meudon, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. Univ Massachusetts, Dept Astron, Amherst, MA 02133 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Bergin, EA (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 23 TC 30 Z9 30 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L147 EP L150 DI 10.1086/312846 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700015 ER PT J AU Bergin, EA Melnick, GJ Stauffer, JR Ashby, MLN Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Snell, RL Tolls, V Wang, Z Winnewisser, G Zhang, YF AF Bergin, EA Melnick, GJ Stauffer, JR Ashby, MLN Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Snell, RL Tolls, V Wang, Z Winnewisser, G Zhang, YF TI Implications of Submillimeter Wave Astronomy Satellite observations for interstellar chemistry and star formation SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : evolution; ISM : molecules; molecular processes; stars : formation ID DENSE MOLECULAR CLOUDS; CHEMICAL-MODELS; THERMAL BALANCE; GAS; EVOLUTION; DEPLETION; OXYGEN; ABUNDANCES; MECHANISM; CORES AB A long-standing prediction of steady state gas-phase chemical theory is that H2O and O-2 are important reservoirs of elemental oxygen and major coolants of the interstellar medium. Analysis of Submillimeter Wave Astronomy Satellite (SWAS) observations has set sensitive upper limits on the abundance of O-2 and has provided H2O abundances toward a variety of star-forming regions. Based on these results, we show that gaseous H2O and O-2 are not dominant carriers of elemental oxygen in molecular clouds. Instead, the available oxygen is presumably frozen on dust grains in the form of molecular ices, with a significant portion potentially remaining in atomic form, along with CO, in the gas phase. H2O and O-2 are also not significant coolants for quiescent molecular gas. In the case of H2O, a number of known chemical processes can locally elevate its abundance in regions with enhanced temperatures, such as warm regions surrounding young stars or in hot shocked gas. Thus, water can be a locally important coolant. The new information provided by SWAS, when combined with recent results from the Infrared Space Observatory, also provides several hard observational constraints for theoretical models of the chemistry in molecular clouds, and we discuss various models that satisfy these conditions. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 48 TC 122 Z9 123 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L129 EP L132 DI 10.1086/312843 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700011 ER PT J AU Goldsmith, PF Melnick, GJ Bergin, EA Howe, JE Snell, RL Neufeld, DA Harwit, M Ashby, MLN Patten, BM Kleiner, SC Plume, R Stauffer, JR Tolls, V Wang, Z Zhang, YF Erickson, NR Koch, DG Schieder, R Winnewisser, G Chin, G AF Goldsmith, PF Melnick, GJ Bergin, EA Howe, JE Snell, RL Neufeld, DA Harwit, M Ashby, MLN Patten, BM Kleiner, SC Plume, R Stauffer, JR Tolls, V Wang, Z Zhang, YF Erickson, NR Koch, DG Schieder, R Winnewisser, G Chin, G TI O-2 in interstellar molecular clouds SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : clouds; ISM : molecules ID INTER-STELLAR CLOUDS; GAS-PHASE CHEMISTRY; ROTATIONAL-EXCITATION; CARBON-MONOXIDE; UPPER LIMITS; ABUNDANCE; OXYGEN; SEARCH; RATIO; (OO)-O-16-O-18 AB We have used the Submillimeter Wave Astronomy Satellite (SWAS) to carry out deep integrations on the N-j = 3(3) --> 1(2) transition of O-2 in a variety of Galactic molecular clouds. We here report no convincing detection in an initial set of observations of 20 sources. We compare O-2 integrated intensities with those of (CO)-O-18 in a similarly sized beam and obtain 3 sigma upper limits for the O-2/(CO)-O-18 abundance ratio less than or equal to 2.3 in four clouds and less than or equal to 3.6 in five additional clouds. Our lowest individual limit corresponds to N(O-2)/N(H-2) < 2.6 x 10(-7) (3 sigma). A combination of data from nine sources yields < N(O-2)/N(H-2)> = [0.33 +/- 1.6 (3 sigma)] x 10(-7). These low limits, characterizing a variety of clouds in different environments at different Galactocentric radii, indicate that O-2 is not a major constituent of molecular clouds and is not an important coolant. The abundance of O-2 is significantly lower than predicted by steady state single-component chemical models. The present results are best understood in the context of cloud chemical and dynamical models that include the interaction of gas-phase molecules and grain surfaces and/or circulation of material between well-shielded and essentially unshielded regions. This circulation may be powered by turbulence or other driving forces that effectively keep molecular clouds chemically unevolved. C1 Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Goldsmith, PF (reprint author), Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Space Sci Bldg, Ithaca, NY 14853 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 39 TC 89 Z9 90 U1 1 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L123 EP L127 DI 10.1086/312854 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700010 ER PT J AU Gurwell, MA Bergin, EA Melnick, GJ Ashby, MLN Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF AF Gurwell, MA Bergin, EA Melnick, GJ Ashby, MLN Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF TI Submillimeter Wave Astronomy Satellite observations of the Martian atmosphere: Temperature and vertical distribution of water vapor SO ASTROPHYSICAL JOURNAL LA English DT Article DE planets and satellites : individual (Mars); radio lines : solar system; submillimeter ID MARS ATMOSPHERE; WAVELENGTHS; APHELION AB We report the first detections of absorption features in the submillimeter spectrum of Mars that are due to the H2O (1(10)-1(01)) and (CO)-C-13 (5-4) rotational transitions. Observations were obtained over several days near the planet's closest approach to Earth in 1999 April. These observations simultaneously provide us with an opportunity to derive the atmospheric temperature structure and to measure directly the distribution of water vapor with altitude. The Martian atmosphere is found to be relatively cool, consistent with results found from ground-based millimeter observations of CO. The distribution of water in the Martian atmosphere matches a profile of constant, 100% saturation from 10 to 45 km altitude. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Gurwell, MA (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 20 TC 31 Z9 31 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L143 EP L146 DI 10.1086/312857 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700014 ER PT J AU Howe, JE Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Hollenbach, DJ Kaufman, MJ Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ AF Howe, JE Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Hollenbach, DJ Kaufman, MJ Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ TI Extended [C I] and (CO)-C-13 (5 -> 4) emission in M17SW SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (M17SW); ISM : molecules; ISM : structure; radio lines : ISM submillimeter ID MOLECULAR CLOUDS; PHOTODISSOCIATION REGIONS; ATOMIC CARBON; CLUMPY STRUCTURE; LINE EMISSION; EXCITATION; MULTITRANSITION; SUBMILLIMETER; M17-SW; CORES AB We mapped a 13 x 22 pc region in emission from 492 GHz [C I] and, for the first time, 551 GHz (CO)-C-13 (5 --> 4) in the giant molecular cloud M17SW, The morphologies of the [C I] and (CO)-C-13 emission are strikingly similar The extent and intensity of the [C I] and (CO)-C-13 (5 --> 4) emission is explained as arising from photodissociation regions on the surfaces of embedded molecular clumps. Modeling of the (CO)-C-13 (5 --> 4) emission in comparison to (CO)-C-13 (1 --> 0) indicates a temperature gradient across the cloud, peaking to at least 63 K near the M17 ionization front and decreasing to at least 20 EC:at the western edge of the cloud. We see no correlation between gas density and column density, The beam-averaged column density of C I in the core is 1 x 10(18) cm(-2), and the mean column density ratio N(C I)/N(CO) is about 0.4; The variations of N(C I)/N(CO) with position in M17SW indicate a similar clump size distribution throughout the cloud. C1 Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. San Jose State Univ, Dept Phys, San Jose, CA 95192 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Howe, JE (reprint author), Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 32 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L137 EP L141 DI 10.1086/312850 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700013 ER PT J AU Melnick, GJ Ashby, MLN Plume, R Bergin, EA Neufeld, DA Chin, G Erickson, NR Goldsmith, PE Harwit, M Howe, JE Kleiner, SC Koch, DG Patten, BM Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, C Zhang, YF AF Melnick, GJ Ashby, MLN Plume, R Bergin, EA Neufeld, DA Chin, G Erickson, NR Goldsmith, PE Harwit, M Howe, JE Kleiner, SC Koch, DG Patten, BM Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, C Zhang, YF TI Observations of water vapor toward Orion BN/KL SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : individual (Orion); ISM : molecules ID MOLECULAR CLOUD CORES; COLLISIONAL EXCITATION; SHOCKED REGIONS; THERMAL BALANCE; STAR FORMATION; ABUNDANCES; H2O; EMISSION; OUTFLOW; OMC-1 AB We have obtained spectra of the rotational ground-state 1(10)-1(01) 556.936 GHz ortho-(H2O)-O-16 and 1(10)-1(01) 547.676 GHz ortho-(H2O)-O-18 transitions toward Orion BN/KL using the Submillimeter Wave Astronomy Satellite (SWAS). The ortho-(H2O)-O-16 spectrum shows strong evidence for both a broad (Delta v similar or equal to 48 km s(-1)) and a narrow (Delta v similar or equal to 7.5 km s(-1)) component, while the ortho-(H2O)-O-18 shows evidence for only a broad (Delta v similar or equal to 24 km s(-1)) component. The broad component emission in both ortho-(H2O)-O-16 and ortho-(H2O)-O-18 arises primarily from gas heated within the low- and high-velocity outflows and shocked gas surrounding IRc2 in which the ortho-(H2O)-O-16 and ortho-(H2O)-O-18 fractional abundances are estimated to be 3.5 x 10(-4) and 7 x 10(-7), respectively. This finding provides further confirmation that water is efficiently and abundantly produced within warm shock-heated gas. We estimate that the hot core plus the compact ridge contribute less than or similar to 10% to the ortho-(H2O)-O-16 integrated intensity within the SWAS beam. The narrow component seen in the ortho-(H2O)-O-16 spectrum is best fitted by ortho-water emission from the extended ridge (ER) and the higher temperature core of the extended ridge (CER) with a common fractional abundance of 3.3 x 10(-8). The absence of any discernible narrow component in the ortho-(H2O)-O-18 spectrum is used to set 3 sigma upper limits on the ortho-water fractional abundance within the ER of 7 x 10(-8) and within the CER of 5.2 x 10(-7). This implies that within the dense extended quiescent region, gas-phase water is neither a major repository of oxygen nor a major coolant in Orion BN/KL. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Cornell Univ, Dept Astron, Natl Astron & Ionosphere Ctr, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Melnick, GJ (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Chin, Gordon/E-1520-2012 NR 27 TC 43 Z9 43 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L87 EP L91 DI 10.1086/312849 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700002 ER PT J AU Melnick, GJ Stauffer, JR Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Snell, RL Tolls, V Wang, Z Winnewisser, G Zhang, YF AF Melnick, GJ Stauffer, JR Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Snell, RL Tolls, V Wang, Z Winnewisser, G Zhang, YF TI The Submillimeter Wave Astronomy Satellite: Science objectives and instrument description SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : clouds; stars : formation; submillimeter ID C-I EMISSION; MOLECULAR CLOUDS; THERMAL BALANCE; ATOMIC OXYGEN; LINE; ABUNDANCE; ABSORPTION; CARBON AB The Submillimeter Wave Astronomy Satellite (SWAS), launched in 1998 December, is a NASA mission dedicated to the study of star formation through direct measurements of (1) molecular cloud composition and chemistry, (2) the cooling mechanisms that facilitate cloud collapse, and (3) the large-scale structure of the UV-illuminated cloud surfaces. To achieve these goals, SWAS is conducting pointed observations of dense [n(H-2) > 10(3) cm(-3)] molecular clouds throughout our Galaxy in either the ground state or a low-lying transition of five astrophysically important species: H2O, (H2O)-O-18, O-2, C I, and (CO)-C-13. By observing these lines SWAS is (1) testing long-standing theories that predict that these species are the dominant coolants of molecular clouds during the early stages of their collapse to form stars and planets and (2) supplying previously missing information about the abundance of key species central to the chemical models of dense interstellar gas. SI TIAS carries two independent Schottky barrier diode mixers - passively cooled to similar to 175 K - coupled to a 54 x 68 cm off-axis Cassegrain antenna with an aggregate surface error similar to 11 mu m rms. During its baseline 3 yr mission, SWAS is observing giant and dark cloud cores with the goal of detecting or setting an upper limit on the water and molecular oxygen abundance of 3 x 10(-6) (relative to H-2). In addition, advantage is being taken of SWAS's relatively large beam size of 3'.3 x 4'.5 at 553 GHz and 3'.5 x 5'.0 at 490 GHz to obtain large-area (similar to 1 degrees x 1 degrees) maps of giant and dark clouds in the (CO)-C-13 and C I lines. With the use of a 1.4 GHz bandwidth acousto-optical spectrometer, SWAS has the ability to simultaneously observe either the H2O, O-2, C I, and (CO)-C-13 lines or the (H2O)-O-18, O-2, and C I lines. All measurements are being conducted with a velocity resolution less than 1 km s(-1). C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Massachusetts, Five Coll Radio Astron Observ, Amherst, MA 01003 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Melnick, GJ (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 21 TC 130 Z9 132 U1 1 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L77 EP L85 DI 10.1086/312856 PN 2 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700001 ER PT J AU Neufeld, DA Snell, RL Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Patten, BM Plume, R Schieder, R Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ AF Neufeld, DA Snell, RL Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Patten, BM Plume, R Schieder, R Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ TI Observations of interstellar water vapor in outflow regions SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : molecules ID L1157 DARK CLOUD; MOLECULAR CLOUDS; BIPOLAR OUTFLOW; HIGH-RESOLUTION; CO EMISSION; NGC-2071; FLOW; H2O; LINE; HYDROGEN AB We have observed the 1(10)-->1(01) transition of interstellar water vapor near 557 GHz toward the three outflow sources NGC 2071, L1157, and NGC 1333 IRAS 4 using the Submillimeter Wave Astronomy Satellite. In each case, the observations reveal broad emission from water in the outflow accompanied by a narrow absorption feature at the velocity of the quiescent gas. Our estimates of the average ortho-water abundance within the outflowing gas lie in the range (0.5-1.6) x 10(-6) relative to H-2. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Neufeld, DA (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 33 TC 31 Z9 31 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L107 EP L110 DI 10.1086/312852 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700006 ER PT J AU Neufeld, DA Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Patten, BM Plume, R Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ AF Neufeld, DA Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Kleiner, SC Koch, DG Patten, BM Plume, R Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ TI Observations of absorption by water vapor toward Sagittarius B2 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : individual (Sagittarius B2); ISM : molecules; radio lines : ISM ID MOLECULAR LINE SURVEY; STAR-FORMING REGIONS; GALACTIC-CENTER; SGR B2; CLOUDS; MULTILEVEL; AMMONIA; GALAXY AB We have observed the 1(10)-->1(01) pure rotational transitions of both (H2O)-O-16 and (H2O)-O-18 toward Sagittarius B2 using the Submillimeter Wave Astronomy Satellite. The spectra thereby obtained show a complex pattern of absorption and - in the case of (H2O)-O-16 - emission, with numerous features covering a wide range of LSR velocities (-130 to 130 km s(-1)) and representing absorption both in gas associated with Sgr B2 as well as by several components of foreground gas along the line of sight. The ortho-water abundance derived for the absorbing foreground gas is similar to 6 x 10(-7) relative to H-2. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Neufeld, DA (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 23 TC 31 Z9 31 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L111 EP L113 DI 10.1086/312853 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700007 ER PT J AU Neufeld, DA Stauffer, JR Bergin, EA Kleiner, SC Patten, BM Wang, Z Ashby, MLN Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Koch, DG Plume, R Schieder, R Snell, RL Tolls, V Winnewisser, G Zhang, YF Melnick, GJ AF Neufeld, DA Stauffer, JR Bergin, EA Kleiner, SC Patten, BM Wang, Z Ashby, MLN Chin, G Erickson, NR Goldsmith, PF Harwit, M Howe, JE Koch, DG Plume, R Schieder, R Snell, RL Tolls, V Winnewisser, G Zhang, YF Melnick, GJ TI Submillimeter Wave Astronomy Satellite observations of water vapor toward comet C/1999 H1 (Lee) SO ASTROPHYSICAL JOURNAL LA English DT Article DE comets : general; comets : individual (Lee (C/1999 HI)) AB We have detected the 1(10)-1(01) pure rotational transition of water vapor toward comet C/1999 H1 using the Submillimeter Wave Astronomy Satellite. Over the period 1999 May 19.01-23.69 UT, the average integrated antenna temperature was 1.79 +/- 0.03 K km s(-1) within a 3.'3 x 4.'5 (FWHM) elliptical beam. For an assumed ortho-to-para ratio of 3, we estimate the total water production rate as 8 x 10(28) s(-1). This value lies approximately 50% above the value estimated by Biver et al. from contemporaneous radio observations of hydroxyl molecules. The observed line width of 1.8 km s(-1) (FWHM) is broader than the instrumental profile and suggests an intrinsic line width of about 1.4 km s(-1) (FWHM). The data, taken during a portion of every 97 minute spacecraft orbit over a 4.68 day period, provide no evidence for variability. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Neufeld, DA (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 16 TC 34 Z9 34 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L151 EP L154 DI 10.1086/312851 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700016 ER PT J AU Plume, R Bensch, F Howe, JE Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Kleiner, S Koch, DG Neufeld, DA Patten, BM Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Reynolds, K Joyce, R Tavoletti, C Jack, G Rodkey, CJ Melnick, GJ AF Plume, R Bensch, F Howe, JE Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Kleiner, S Koch, DG Neufeld, DA Patten, BM Schieder, R Snell, RL Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Reynolds, K Joyce, R Tavoletti, C Jack, G Rodkey, CJ Melnick, GJ TI Large-scale (CO)-C-13 J=5 -> 4 and [C I] mapping Of Orion A SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : individual (Orion); ISM : molecules; stars : formation ID MOLECULAR CLOUD CORES; WARM GAS; EMISSION; SUBMILLIMETER; CARBON AB We present maps of the (CO)-C-13 J = 5 --> 4 (551 GHz) and [C I] P-3(1) --> P-3(0) (492 GHz) emission in the Orion A molecular cloud, covering a 0 degrees.5 x 2 degrees area. A large velocity gradient (LVG) analysis of (CO)-C-13 J = 5 --> 4 and J = 1 --> 0 suggests that the gas temperatures in the northern part of OMC-1. (north of Delta delta = -20') are similar to 45 K and are, on average, at least 20 K higher than those to the south. The average (CO)-C-13 column density is log (N/cm(-2)) = 16.4 +/- 0.3 and is fairly constant throughout the cloud, even in the low-temperature region south of BN/KL. LVG modeling of the [C I] emission shows a typical C-0 column density of 2 x 10(17) cm(-2), which yields a C/CO abundance ratio in the cloud of similar to 0.1 (rising to levels in excess of 0.5 at the cloud edges). Comparison of the Delta-variance (which measures spatial structure in a manner similar to a power spectrum) of the Submillimeter Wave Astronomy Satellite [C I], Five College Radio Astronomy Observatory (CO)-C-13 J = 1 --> 0, and CS J = 1 --> 0 velocity-integrated maps suggests that the [C I] and (CO)-C-13 emission arise from the same gas. In contrast, the CS emission likely originates in gas that is considerably more clumpy. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cornell Univ, Dept Astron, Natl Astron & Ionosphere Ctr, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Keystone Oaks Planetarium, Pittsburgh, PA 15216 USA. RP Plume, R (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 24 TC 33 Z9 33 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L133 EP L136 DI 10.1086/312847 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700012 ER PT J AU Snell, RL Howe, JE Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ AF Snell, RL Howe, JE Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ TI Water abundance in molecular cloud cores SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : molecules; radio lines : ISM ID HOT CORES; GL-2591; DENSITY; MODELS; H2O; CS AB We present Submillimeter Wave Astronomy Satellite (SWAS) observations of the 1(10)-->1(01) transition of ortho-H2O at 557 GHz toward 12 molecular cloud cores. The water emission was detected in NGC 7538, rho Oph A, NGC 2024, CRL 2591, W3, W3OH, Mon R2, and W33 and was not detected in TMC-1, L134N, and B335. We also present a small map of the H2O emission in S140. Observations of the (H2O)-O-18 line were obtained toward S140 and NGC 7538, but no emission was detected. The abundance of ortho-H2O relative to H-2 in the giant molecular cloud cores was found to vary between 6 x 10(-10) and 1 x 10(-8). Five of the cloud cores in our sample have previous H2O detections; however, in all cases the emission is thought to arise from hot cores with small angular extents. The H2O abundance estimated for the hot core gas is at least 100 times larger than in the gas probed by SI VAS. The most stringent upper limit on the ortho-H2O abundance in dark clouds is provided in TMC-I, where the 3 sigma upper limit on the ortho-H2O fractional abundance is 7 x 10(-8). C1 Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Snell, RL (reprint author), Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 28 TC 112 Z9 112 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L101 EP L105 DI 10.1086/312848 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700005 ER PT J AU Snell, RL Howe, JE Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ AF Snell, RL Howe, JE Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ TI Submillimeter Wave Astronomy Satellite observations of extended water emission in Orion SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : individual (Orion); ISM : molecules; radio lines : ISM ID MOLECULAR CLOUDS; SHOCKED REGIONS; VAPOR EMISSION; H2O; OMC-1; CORES AB We have used the Submillimeter Wave Astronomy Satellite to map the ground-state 1(10)-->1(01) transition of ortho-H2O at 557 GHz in the Orion molecular cloud. H2O emission was detected in Orion over an angular extent of about 20', or nearly 3 pc. The water emission is relatively weak, with line widths (3-6 km s(-1)) and V-LSR velocities (9-11 km s(-1)) consistent with an origin in the cold gas of the molecular ridge. We find that the ortho-H2O abundance relative to H-2 in the extended gas in Orion varies between 1 and 8 x 10(-8), with an average of 3 x 10(-8). The absence of detectable narrow-line ortho-(H2O)-O-18 emission is used to set a 3 sigma upper limit on the relative ortho-H2O abundance of 7 x 10(-8). C1 Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Snell, RL (reprint author), Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 25 TC 50 Z9 50 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L93 EP L96 DI 10.1086/312855 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700003 ER PT J AU Snell, RL Howe, JE Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ AF Snell, RL Howe, JE Ashby, MLN Bergin, EA Chin, G Erickson, NR Goldsmith, PF Harwit, M Kleiner, SC Koch, DG Neufeld, DA Patten, BM Plume, R Schieder, R Stauffer, JR Tolls, V Wang, Z Winnewisser, G Zhang, YF Melnick, GJ TI The distribution of water emission in M17SW SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : molecules; radio lines : ISM ID MOLECULAR CLOUDS; CLUMPY STRUCTURE; ATOMIC CARBON; CS; MULTITRANSITION; SUBMILLIMETER; CORES; H2O; SW; CO AB We present a 17-point map of the M17SW cloud core in the 1(10)-->1(01) transition of ortho-H2O at 557 GHz obtained with Submillimeter Wave Astronomy Satellite. Water emission was detected in 11 of the 17 observed positions. The line widths of the H2O emission vary between 4 and 9 km s(-1) and are similar to other emission lines that arise in the M17SW core. A direct comparison is made between the spatial extent of the H2O emission and the (CO)-C-13 J = 5-->4 emission; the good agreement suggests that the H2O emission arises in the same warm, dense gas as the (CO)-C-13 emission. A spectrum of the (H2O)-O-18 line was also obtained at the center position of the cloud core, but no emission was detected. We estimate that the average abundance of ortho-H2O relative to H-2 within the M17 dense core is approximately 1 x 10(-9), 30 times smaller than the average for the Orion core. Toward the I-I Il region/molecular cloud interface in M17SW the ortho-H2O abundance may be about 5 times larger than in the dense core. C1 Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Dept Astron, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Snell, RL (reprint author), Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. RI Chin, Gordon/E-1520-2012; Goldsmith, Paul/H-3159-2016 NR 21 TC 24 Z9 24 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 2000 VL 539 IS 2 BP L97 EP L100 DI 10.1086/312844 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 353AZ UT WOS:000089252700004 ER PT J AU Bauschlicher, CW Ricca, A AF Bauschlicher, CW Ricca, A TI Mechanisms for polycyclic aromatic hydrocarbon (PAH) growth SO CHEMICAL PHYSICS LETTERS LA English DT Article ID ACETYLENE; FLAMES AB We compute the barriers and heats of reaction for the conversion of benzene to naphthalene by acetylene additions using the B3LYP/4-31G approach. The Frenklach mechanism for adding a ring to a PAH molecule is compared with the Bittner-Howard acetylene addition mechanism. Both have low barriers, and the similarities and differences of the two mechanisms are discussed. A ring addition mechanism for cations is also studied, and it is found to have no barriers. (C) 2000 Published by Elsevier Science B.V. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 22 TC 54 Z9 55 U1 3 U2 18 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 AUG 18 PY 2000 VL 326 IS 3-4 BP 283 EP 287 DI 10.1016/S0009-2614(00)00798-3 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 346HU UT WOS:000088865600013 ER PT J AU Burgmann, R Schmidt, D Nadeau, RM d'Alessio, M Fielding, E Manaker, D McEvilly, TV Murray, MH AF Burgmann, R Schmidt, D Nadeau, RM d'Alessio, M Fielding, E Manaker, D McEvilly, TV Murray, MH TI Earthquake potential along the northern Hayward fault, California SO SCIENCE LA English DT Article ID SAN-ANDREAS FAULT; SURFACE DEFORMATION; SLIP; DEPTH; CREEP; INTERFEROMETRY; PARKFIELD; SPACE; RATES AB The Hayward fault slips in large earthquakes and by aseismic creep observed along its surface trace. Dislocation models of the surface deformation adjacent to the Hayward fault measured with the global positioning system and interferometric synthetic aperture radar favor creep at similar to 7 millimeters per year to the bottom of the seismogenic zone along a similar to 20-kilometer-long northern fault segment, Microearthquakes with the same waveform repeatedly occur at 4- to 10-kilometer depths and indicate deep creep at 5 to 7 millimeters per year. The difference between current creep rates and the long-term slip rate of similar to 10 millimeters per year can be reconciled in a mechanical model of a freely slipping northern Hayward fault adjacent to the locked 1868 earthquake rupture, which brake the southern 40 to 50 kilometers of the fault. The potential for a major independent earthquake of the northern Hayward fault might be Less than previously thought. C1 Univ Calif Berkeley, Dept Earth & Planetary Sci, Berkeley, CA 94720 USA. Univ Calif Berkeley, Berkeley Seismol Lab, Berkeley, CA 94720 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Davis, Dept Geol, Davis, CA 95616 USA. RP Burgmann, R (reprint author), Univ Calif Berkeley, Dept Earth & Planetary Sci, 307 McCone Hall, Berkeley, CA 94720 USA. RI Fielding, Eric/A-1288-2007 OI Fielding, Eric/0000-0002-6648-8067 NR 19 TC 122 Z9 126 U1 1 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 AUG 18 PY 2000 VL 289 IS 5482 BP 1178 EP 1182 DI 10.1126/science.289.5482.1178 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 346JE UT WOS:000088866600038 ER PT J AU Halasinski, TM Hudgins, DM Salama, F Allamandola, LJ Bally, T AF Halasinski, TM Hudgins, DM Salama, F Allamandola, LJ Bally, T TI Electronic absorption spectra of neutral pentacene (C22H14) and its positive and negative ions in Ne, Ar, and Kr matrices SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID AROMATIC HYDROCARBON CATIONS; INFRARED-SPECTROSCOPY; OPTICAL-ABSORPTION; LARGE MOLECULES; SPIN-RESONANCE; SMALL GRAINS; SOLID AR; ATOMS; ENERGIES; GAS AB The absorption spectra of neutral pentacene (C22H14) and its radical cation (C22H14+) and anion (C22H14-) isolated in solid Ne, Ar, and Kr have been measured from the ultraviolet to the near-infrared. The associated vibronic band systems and their spectroscopic assignments are discussed together with the physical and chemical conditions governing molecular anion production in matrices doped with alkali metal (Na or K). TD-DFT calculations were carried out to assist in the assignments for the measured spectral features of the pentacene ions. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Fribourg, Inst Phys Chem, CH-1700 Fribourg, Switzerland. RP Salama, F (reprint author), NASA, Ames Res Ctr, Mail Stop 245-6, Moffett Field, CA 94035 USA. RI Salama, Farid/A-8787-2009 OI Salama, Farid/0000-0002-6064-4401 NR 37 TC 81 Z9 82 U1 2 U2 19 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5639 J9 J PHYS CHEM A JI J. Phys. Chem. A PD AUG 17 PY 2000 VL 104 IS 32 BP 7484 EP 7491 DI 10.1021/jp0011544 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 345RK UT WOS:000088828800009 ER PT J AU Lei, SL Palazzolo, A Na, U Kascak, A AF Lei, SL Palazzolo, A Na, U Kascak, A TI Non-linear fuzzy logic control for forced large motions of spinning shafts SO JOURNAL OF SOUND AND VIBRATION LA English DT Article ID MAGNETIC BEARING AB A unique control approach is developed for prescribed large motion control using magnetic bearings in a proposed active stall control test rig. A finite element based, flexible shaft is modeled in a closed loop system with PD controllers that generate the control signals to support and to shake the rotor shaft. A linearized force model of the stall rig with 16 magnetic poles (4 opposing C-cores) yields stability and frequency responses. The non-linear model retains the non-linearities in Ampere's law, Faraday's law and the Maxwell stress tensor. A fuzzy logic control system is then designed to show the advantages over the conventional controllers with the fully non-linear model. (C) 2000 Academic Press. C1 Texas A&M Univ, Dept Mech Engn, College Stn, TX 77843 USA. NASA, Lewis Res Ctr, USA, Cleveland, OH 44135 USA. RP Lei, SL (reprint author), Texas A&M Univ, Dept Mech Engn, College Stn, TX 77843 USA. NR 14 TC 8 Z9 8 U1 0 U2 4 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD AUG 17 PY 2000 VL 235 IS 3 BP 435 EP 449 DI 10.1006/jsvi.2000.2937 PG 15 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 346PX UT WOS:000088881200005 ER PT J AU Wallace, K Hardy, G Serabyn, E AF Wallace, K Hardy, G Serabyn, E TI Deep and stable interferometric nulling of broadband light with implications for observing planets around nearby stars SO NATURE LA English DT Article ID SOLAR AB The number of indirectly detected planetary systems around nearby stars has grown tremendously since their initial discovery five years ago(1). But the direct observation of light reflected from these systems remains a formidable task, because of the high contrast ratios between them and their parent stars, and because of the tiny angular separations. Theoretically(2), these difficulties can be overcome by using a dual-aperture stellar interferometer in which the starlight is cancelled, or 'nulled', by broadband destructive interference, leaving the planet's light visible. Although the basic requirement of equal and oppositely directed electric fields is easy to state, an experimental demonstration of deep broadband nulling has been lacking, owing to difficulties engendered by the needs for extreme symmetry and stability, and low dispersion in the optical system. Here we report the deep (10(-4)) and stable nulling of broadband (18% bandwidth) thermal light. These results validate the physical principles underlying future planet-searching interferometers, and our laboratory instrument will serve as a prototype for the nulling instrument to be implemented on the Keck interferometer in 2001. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wallace, K (reprint author), CALTECH, Jet Prop Lab, MS 171-113,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 20 TC 54 Z9 55 U1 2 U2 4 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD AUG 17 PY 2000 VL 406 IS 6797 BP 700 EP 702 DI 10.1038/35021007 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 344PH UT WOS:000088767700035 ER PT J AU Crawford, J Davis, D Olson, J Chen, G Liu, S Fuelberg, H Hannan, J Kondo, Y Anderson, B Gregory, G Sachse, G Talbot, R Viggiano, A Heikes, B Snow, J Singh, H Blake, D AF Crawford, J Davis, D Olson, J Chen, G Liu, S Fuelberg, H Hannan, J Kondo, Y Anderson, B Gregory, G Sachse, G Talbot, R Viggiano, A Heikes, B Snow, J Singh, H Blake, D TI Evolution and chemical consequences of lightning-produced NOx observed in the North Atlantic upper troposphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID EASTERN NEW-YORK; NITRIC-ACID; PERFORMANCE EVALUATION; CONVECTIVE INJECTION; TROPOPAUSE REGION; DETECTION NETWORK; TROPICAL PACIFIC; HNO3/NOX RATIO; ICE PARTICLES; NITROGEN AB Airborne observations of NO during the Subsonics Assessment Ozone and Nitrogen Oxides Experiment (SONEX) reveal episodes of high NOx in the upper troposphere believed to be associated with lightning. Linkage to specific periods of lightning activity is possible through back trajectories and data from the National Lightning Detection Network. Lagrangian model calculations are used to explore the evolution of these high NOx plumes over the 1-2 days between their introduction and subsequent sampling by NASA's DC-8 aircraft. Simulations include expected changes in HNO3, H2O2, CH3OOH, HO2, and OH. Depending on the time of injection and dilution rate, initial NOx concentrations are estimated to range from 1 to 7 ppbv. Similar to many previous studies, simulated HNO3 concentrations tend to be greater than observations. Several possible explanations for this difference are explored. H2O2 observations are shown to be consistent with removal in convective activity. While it is possible that upper tropospheric CH3OOH is enhanced by convection, simulations show such increases in CH3OOH can be short-lived (e.g., < 12 hours) with no perceptible trace remaining at the time of sampling. High NO levels further prevent elevated levels of CH3OOH from propagating into increases in H2O2. HO2 is suppressed through reaction with NO in all cases. Simulated increases in OH exceeded a factor of 2 for some cases, but for the highest NOx levels, loss of OH via OH+NO2 offset production from HO2+NO. Additional increases in OH of 30-60% could result from convection of CH3OOH. A final point of discussion concerns how the chemistry within these plumes, their long-range transport, and their potential importance in sustaining background NOx far from source regions present a challenge to global and regional model simulations. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. Nagoya Univ, Solar Terr Environm Lab, Aichi, Japan. Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03820 USA. USAF, Res Lab, Hanscom AFB, MA 01731 USA. Univ Rhode Isl, Ctr Atmospher Chem Studies, Narragansett, RI 02882 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Irvine, Dept Chem, Irvine, CA 92717 USA. RP Crawford, J (reprint author), NASA, Langley Res Ctr, 21 Langley Blvd, Hampton, VA 23681 USA. EM j.h.crawford@larc.nasa.gov RI Kondo, Yutaka/D-1459-2012; Crawford, James/L-6632-2013 OI Crawford, James/0000-0002-6982-0934 NR 65 TC 18 Z9 18 U1 1 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 16 PY 2000 VL 105 IS D15 BP 19795 EP 19809 DI 10.1029/2000JD900183 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 347LG UT WOS:000088930600005 ER PT J AU Hurst, DF Dutton, GS Romashkin, PA Elkins, JW Herman, RL Moyer, EJ Scott, DC May, RD Webster, CR Grecu, J Loewenstein, M Podolske, JR AF Hurst, DF Dutton, GS Romashkin, PA Elkins, JW Herman, RL Moyer, EJ Scott, DC May, RD Webster, CR Grecu, J Loewenstein, M Podolske, JR TI Comparison of in situ N2O and CH4 measurements in the upper troposphere and lower stratosphere during STRAT and POLARIS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TOTAL HYDROGEN BUDGET; NITROUS-OXIDE; SPECTROMETER AB Nitrous oxide (N2O) and methane (CH4) were measured in the upper troposphere and lower stratosphere by multiple instruments aboard the NASA ER-2 aircraft during the 1995-1996 Stratospheric Tracers of Atmospheric Transport (STRAT) and 1997 Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) campaigns. Differences between coincidental, in situ measurements are examined to evaluate the agreement and variability in the agreement between these instruments during each flight. Mean N2O measurement differences for each flight were much smaller than limits calculated from quoted values of N2O measurement accuracy and for all but two flights were less than or equal to 8.7 ppb (3.5%). Mean CH4 measurement differences for flights were similarly much smaller than calculated limits and for all but three flights were less than or equal to 65 ppb (4.4%). Typical agreement between instruments during flights averaged 6.2 ppb (2.5%) for N2O and 43 ppb (2.9%) for CH4. In contrast, for about half of the flights, the variability of N2O and CH4 measurement differences exceeded limits calculated from quoted values of measurement precision. The typical measurement difference variability (lo) during a flight averaged +/-8.0 ppb for N2O and +/-43 ppb (2.9%) for CH4. For some flights, large differences or variations in differences are attributable to the poor measurement accuracy or precision of one instrument. It is demonstrated that small offsets between the computer clocks of these instruments can result in significant differences between their "coincidental" N2O and CH4 data, especially when there is high spatial variability in tracer abundance along a flight track. C1 Natl Ocean & Atmospher Adm, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. Univ Colorado, NOAA, Cooperat Inst Res Environm Sci, Boulder, CO 80309 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Pasadena, CA 91125 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Hurst, DF (reprint author), Natl Ocean & Atmospher Adm, Climate Monitoring & Diagnost Lab, MS R-CMDL1,325 Broadway, Boulder, CO 80303 USA. EM dhurst@cmdl.noaa.gov RI Herman, Robert/H-9389-2012; Hurst, Dale/D-1554-2016 OI Herman, Robert/0000-0001-7063-6424; Hurst, Dale/0000-0002-6315-2322 NR 16 TC 5 Z9 5 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 16 PY 2000 VL 105 IS D15 BP 19811 EP 19822 DI 10.1029/2000JD900218 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 347LG UT WOS:000088930600006 ER PT J AU Rind, D Lonergan, P Shah, K AF Rind, D Lonergan, P Shah, K TI Modeled impact of cirrus cloud increases along aircraft flight paths SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GLOBAL DISTRIBUTION; MIDDLE ATMOSPHERE; CLIMATE-CHANGE; CONTRAILS AB The potential climate impact of contrails and alterations in the lifetime of background cirrus due to subsonic aircraft water and aerosol emissions has been investigated in a set of experiments using the GISS GCM connected to a q-flux ocean. Cirrus clouds at a height of 12-15 km, with an optical thickness of 0.33, were input to the model "x" percentage of clear-sky occasions along subsonic aircraft flight paths. The percentage x is varied from 0.05 to 6%. Two types of experiments were performed: one with the percentage of cirrus cloud increase independent of flight density along the flight paths, the other with the percentage related to the density of fuel expenditure. The overall climate impact was similar with the two approaches. due to the feedbacks of the climate system. Fifty years were run for each of the eight experiments, with the following conclusions based on the stable results from years 31-50. The equilibrium global mean response shows that altering high-level clouds by 1% changes the global mean temperature by 0.43 degrees C. The global temperature response is highly linear (linear correlation coefficient of 0.996) for high cloud cover changes between 0.1 and 5%. The warming is amplified in the Northern Hemisphere, more so with greater cloud cover change. The temperature effect maximizes around 10 km, more so as the overall warming increases (warming greater than 4 degrees C occurs there with a 4.8% increase in upper level clouds). The surface temperature response is dominated by the feedbacks and shows little geographic relationship to the high cloud input outside of the hemispheric difference. Considering whether these effects would be observable, changing upper level cloud cover by as little as 0.4% produces warming greater than 2 standard deviations in the microwave sounding unit (MSU) channels 4, 2, and 2r (although the effect would be most noticeable in the upper troposphere channel 3 were standard deviations available). Given estimates of current aircraft impacts, this would require some increase relative to present-day effects, but a signal should be clear given the projections for 2050 aircraft. In comparison to increased CO2 experiments, in these runs the Northern Hemisphere clearly warms more relative to the Southern Hemisphere, and warming due to cloud height changes exceeds that due to the water vapor feedback. Despite the simplified nature of these experiments, the results emphasize the sensitivity of the modeled climate to high-level cloud cover changes and thus the potential ability of aircraft to influence climate by altering clouds in the upper troposphere. C1 NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. RP Rind, D (reprint author), NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. EM drind@giss.nasa.gov NR 28 TC 14 Z9 14 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 16 PY 2000 VL 105 IS D15 BP 19927 EP 19940 DI 10.1029/1999JD901160 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 347LG UT WOS:000088930600016 ER PT J AU Shah, KP Rind, D Druyan, L Lonergan, P Chandler, M AF Shah, KP Rind, D Druyan, L Lonergan, P Chandler, M TI AGCM hindcasts with SST and other forcings: Responses front global to agricultural scales SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; SEA-SURFACE TEMPERATURE; MICROWAVE SOUNDING UNIT; CLIMATE-CHANGE; EL-NINO; TRENDS; ENSO; PRECIPITATION; PREDICTION; SIMULATION AB Multiple realizations of the 1969-1998 time period have been simulated by the GISS AGCM to explore its responsiveness to accumulated forcings, particularly over sensitive agricultural regions. A microwave radiative transfer postprocessor has produced the AGCM lower tropospheric, tropospheric, and lower stratospheric brightness temperature (T-b) time series for correlations with microwave sounding unit (MSU) time series. AGCM regional surface air temperature and precipitation were also correlated with GISTEMP temperature data and with rain gage data. Seven realizations by the AGCM were forced solely by observed sea surface temperatures. Subsequent runs hindcast January 1969 through April 1998 with an accumulation of forcings: observed sea surface temperatures (SSTs), greenhouse gases, stratospheric volcanic aerosols, stratospheric and tropospheric ozone, and tropospheric sulfate and black carbon aerosols. Lower stratospheric T-b correlations between the AGCM? and the MSU for 1979-1998 reached as high as 0.93 globally given SST, greenhouse gases, volcanic aerosol, and stratospheric ozone forcings, Midtropospheric T-b correlations reached as high as 0.66 globally and 0.84 across the equatorial, 20 degrees S-20 degrees N band. Oceanic lower tropospheric T-b correlations were less high at 0.59 globally and 0.79 across the equatorial band. Of the sensitive agricultural areas considered, Nordeste in northeastern Brazil was simulated best with midtropospheric T-b correlations up to 0.80. The two other agricultural regions, in Africa and in the northern midlatitudes, suffered from higher levels of non-SST-induced variability. Zimbabwe had a maximum midtropospheric correlation of 0.54, while the U.S. Corn Belt reached only 0.25. Hindcast surface temperatures and precipitation were also correlated with observations, up to 0.46 and 0.63, respectively, for Nordeste. Correlations between AGCM and observed time series improved with addition of certain atmospheric forcings in zonal bands but not in agricultural regions encompassing only six AGCM grid cells. C1 Columbia Univ, NASA, Goddard Inst Space Studies,Columbia Earth Inst, Ctr Climate Syst Res,Goddard Space Flight Ctr, New York, NY 10025 USA. Sci Syst & Applicat, New York, NY 10025 USA. RP Shah, KP (reprint author), Columbia Univ, NASA, Goddard Inst Space Studies,Columbia Earth Inst, Ctr Climate Syst Res,Goddard Space Flight Ctr, 2880 Broadway, New York, NY 10025 USA. NR 53 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 16 PY 2000 VL 105 IS D15 BP 20025 EP 20053 DI 10.1029/2000JD900019 PG 29 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 347LG UT WOS:000088930600022 ER PT J AU Dessler, AE Sherwood, SC AF Dessler, AE Sherwood, SC TI Simulations of tropical upper tropospheric humidity SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MICROWAVE LIMB SOUNDER; WATER-VAPOR DISTRIBUTION; LARGE-SCALE ADVECTION; RELATIVE-HUMIDITY; TRAJECTORY ANALYSIS; UARS MLS; CIRRUS; CONVECTION; SENSITIVITY; CLIMATOLOGY AB We present simulations of humidity in the tropical upper troposphere at 215 and 146 hPa made by a model that includes only advection and, whenever relative humidity exceeds 100%, condensation. Despite the simplicity of the model, the simulations agree well with measurements in both convective and nonconvective regions. We see no evidence to suggest that accurate predictions of the humidity in this region are dependent on accurate simulations of microphysical processes or on transport of ice or liquid water. Our results instead suggest that accurate predictions of the humidity primarily require realistic three-dimensional large-scale (greater than a few hundred kilometers) wind fields. C1 Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Dessler, AE (reprint author), Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, 2207 Comp & Space Sci Bldg, College Pk, MD 20742 USA. EM dessler@ntmos.umd.edu; sherwood@zephyr.gsfc.nasa.gov RI Sherwood, Steven/B-5673-2008; Dessler, Andrew/G-8852-2012 OI Sherwood, Steven/0000-0001-7420-8216; Dessler, Andrew/0000-0003-3939-4820 NR 34 TC 51 Z9 51 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 16 PY 2000 VL 105 IS D15 BP 20155 EP 20163 DI 10.1029/2000JD900231 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 347LG UT WOS:000088930600032 ER PT J AU Mihalov, JD Fischer, HM Pehlke, E Lanzerotti, LJ AF Mihalov, JD Fischer, HM Pehlke, E Lanzerotti, LJ TI Energetic trapped electron measurements from the Galileo Jupiter Probe SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PARTICLES AB Energetic trapped electrons were measured with the Energetic Particle Instrument (EPI) on the Galileo Jupiter Probe. Samples were taken from inside Io's orbit to just above Jupiter's atmosphere. Under the assumption of simple power law spectra the energetic electron fluxes and spectra agree well with earlier results from the Pioneer spacecraft, at those locations where comparisons can be made. New features from this Galileo data include measurements of the inner boundary of the trappped particles, inside 1.6 R-J, direct observations of the electron pitch angle distributions, and energy spectral softening, both as the atmosphere is approached, and at smaller pitch angles at each measurement location. C1 NASA, Ames Res Ctr, Planetary Syst Branch, Moffett Field, CA 94035 USA. Inst Expt & Angew Phys, Kiel, Germany. Bell Labs, Lucent Technol, Murray Hill, NJ 07974 USA. RP Mihalov, JD (reprint author), NASA, Ames Res Ctr, Planetary Syst Branch, 245-3, Moffett Field, CA 94035 USA. NR 11 TC 3 Z9 3 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 2000 VL 27 IS 16 BP 2445 EP 2448 DI 10.1029/2000GL003812 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 344QZ UT WOS:000088771500024 ER PT J AU Purucker, M Ravat, D Frey, H Voorhies, C Sabaka, T Acuna, M AF Purucker, M Ravat, D Frey, H Voorhies, C Sabaka, T Acuna, M TI An altitude-normalized magnetic map of Mars and its interpretation SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Techniques developed for the reduction and analysis of terrestrial satellite magnetic field data are used to better understand the magnetic field observations made by Mars Global Surveyor. A global distribution of radial (B-r) magnetic field observations and associated uncertainties is inverted for an equivalent source magnetization distribution and then used to generate an altitude- normalized map of B-r at 200 km. The observations are well-represented by a potential function of crustal origin, consistent with a remanent origin for the Martian magnetic features. The correlation between the 40546 B-r observations and B-r calculated from the magnetization solution at observation locations is 0.978. For a magnetization distribution confined to a 50 km layer, calculated magnetizations range from -22 to +17 A/m. We see correlations with tectonics that were only hinted at in earlier maps. Magnetic features appear to be truncated against Valles Marineris and Ganges Chasma, suggestive of a major change in crustal properties associated with faulting. C1 NASA, Goddard Space Flight Ctr, Raytheon ITSS, Geodynam Branch, Greenbelt, MD 20771 USA. So Illinois Univ, Dept Geol, Carbondale, IL 62940 USA. NASA, Goddard Space Flight Ctr, Planetary Magnetospheres Branch, Greenbelt, MD 20771 USA. RP Purucker, M (reprint author), NASA, Goddard Space Flight Ctr, Raytheon ITSS, Geodynam Branch, Code 921, Greenbelt, MD 20771 USA. RI Voorhies, Coerte/D-4672-2012; Sabaka, Terence/D-5618-2012; OI Ravat, Dhananjay/0000-0003-1962-4422 NR 6 TC 118 Z9 120 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 AUG 15 PY 2000 VL 27 IS 16 BP 2449 EP 2452 DI 10.1029/2000GL000072 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 344QZ UT WOS:000088771500025 ER PT J AU Griffith, DWT Toon, GC Sen, B Blavier, JF Toth, RA AF Griffith, DWT Toon, GC Sen, B Blavier, JF Toth, RA TI Vertical profiles of nitrous oxide isotopomer fractionation measured in the stratosphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ATMOSPHERIC N2O; OZONE; SINKS; RATIO AB We have measured the vertical profiles of several isotopomers of nitrous oxide, N2O, in the stratosphere by balloon-borne infrared remote sensing between 15 and 35 km. In particular we distinguish the individual profiles and relative enrichments of the positional isotopomers (NNO)-N-15-N-14-O-16 and (NNO)-N-14-N-15-O-16 for the first time. We find a distinct and reproducible relative enrichment of the isotopomers which is in general agreement with measured photolysis rates in the laboratory and theoretical predictions. The results confirm photolysis as the dominant stratospheric Loss process for N2O and argue against suggestions that additional chemical sources of N2O in the stratosphere are required to explain the observed heavy isotopic enrichments there. C1 Univ Wollongong, Dept Chem, Wollongong, NSW 2522, Australia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Griffith, DWT (reprint author), Univ Wollongong, Dept Chem, Wollongong, NSW 2522, Australia. NR 30 TC 43 Z9 45 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 AUG 15 PY 2000 VL 27 IS 16 BP 2485 EP 2488 DI 10.1029/2000GL011797 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 344QZ UT WOS:000088771500034 ER PT J AU Sherwood, SC Dessler, AE AF Sherwood, SC Dessler, AE TI On the control of stratospheric humidity SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LOWER TROPICAL STRATOSPHERE; WATER-VAPOR; DEHYDRATION MECHANISM; TROPOSPHERIC AIR; CIRRUS CLOUDS; TROPOPAUSE; TRANSPORT; AIRCRAFT; MONSOON AB We present a hypothesis on the dehydration and transfer of air from the tropical troposphere into the stratosphere. The hypothesis is based on the existence of a thick "tropopause layer," in which vertical and horizontal mixing are both significant. Air is rapidly dehydrated upon entering this layer in vigorous convective overshoots, then slowly ascends through the layer before fully entering the stratosphere. Dehydration and genuine entry into the stratosphere are separate processes that happen on much different time scales. C1 Univ Space Res Assoc, Seabrook, MD USA. Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA. RP Sherwood, SC (reprint author), NASA, Goddard Space Flight Ctr, Mail Code 916, Greenbelt, MD 20771 USA. RI Sherwood, Steven/B-5673-2008; Dessler, Andrew/G-8852-2012 OI Sherwood, Steven/0000-0001-7420-8216; Dessler, Andrew/0000-0003-3939-4820 NR 22 TC 136 Z9 142 U1 2 U2 9 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 AUG 15 PY 2000 VL 27 IS 16 BP 2513 EP 2516 DI 10.1029/2000GL011438 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 344QZ UT WOS:000088771500041 ER PT J AU Liu, WT Xie, XS Polito, PS Xie, SP Hashizume, H AF Liu, WT Xie, XS Polito, PS Xie, SP Hashizume, H TI Atmospheric manifestation of tropical instability wave observed by QuikSCAT and tropical rain measuring mission SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SEA-SURFACE TEMPERATURE; EASTERN EQUATORIAL PACIFIC; UPPER OCEAN; WIND; VARIABILITY AB Observations from two new spaceborne microwave instruments in 1999 clearly reveal the atmospheric manifestation of tropical instability waves north of the Pacific equatorial cold tongue. A unique zonal-temporal bandpass filter enables the isolation of the propagating signals and the determination of their phase differences. The phase differences between the propagation of wind and sea surface temperature (SST) signals observed from space and the vertical wind profiles measured from a research ship are consistent with the hypothesis that the coupling between wind and SST is caused by buoyancy instability and mixing, which reduces the wind shear in the atmospheric boundary layer. The coupling causes higher evaporative cooling over the warm phase and infers a negative thermal feedback. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Hawaii, Int Pacific Res Ctr, Honolulu, HI 96822 USA. Hokkaido Univ, Grad Sch Environm & Earth Sci, Sapporo, Hokkaido, Japan. RP Liu, WT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 300-323, Pasadena, CA 91109 USA. RI Xie, Shang-Ping/C-1254-2009; Polito, Paulo/F-3040-2013 OI Xie, Shang-Ping/0000-0002-3676-1325; Polito, Paulo/0000-0003-2217-3853 NR 21 TC 125 Z9 134 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 2000 VL 27 IS 16 BP 2545 EP 2548 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 344QZ UT WOS:000088771500049 ER PT J AU Folkins, I Oltmans, SJ Thompson, AM AF Folkins, I Oltmans, SJ Thompson, AM TI Tropical convective outflow and near surface equivalent potential temperatures SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERIC WATER-VAPOR; TROPOPAUSE; FOUNTAIN AB We use clear sky heating rates to show that convective outflow in the tropics decreases rapidly with height between the 350 K and 360 K potential temperature surfaces (or between roughly 13 and 15 km). There is also a rapid fall-off in the pseudoequivalent potential temperature probability distribution of near surface air parcels between 350 K and 360 K. This suggests that the vertical variation of convective outflow in the upper tropical troposphere is to a large degree determined by the distribution of sub cloud layer entropy. C1 Dalhousie Univ, Dept Oceanog, Atmospher Sci Program, Halifax, NS B3H 4J1, Canada. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Folkins, I (reprint author), Dalhousie Univ, Dept Oceanog, Atmospher Sci Program, Halifax, NS B3H 4J1, Canada. RI Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 14 TC 35 Z9 35 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 AUG 15 PY 2000 VL 27 IS 16 BP 2549 EP 2552 DI 10.1029/2000GL011524 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 344QZ UT WOS:000088771500050 ER PT J AU King'uyu, SM Ogallo, LA Anyamba, EK AF King'uyu, SM Ogallo, LA Anyamba, EK TI Recent trends of minimum and maximum surface temperatures over eastern Africa SO JOURNAL OF CLIMATE LA English DT Article ID GLOBAL TEMPERATURE; CLIMATE VARIATIONS; NORTH-ATLANTIC; RANGE; 20TH-CENTURY; SERIES; PRECIPITATION; PERSPECTIVE; OCEAN; LAND AB This study investigated recent trends in the mean surface minimum and maximum air temperatures over eastern Africa by use of both graphical and statistical techniques. Daily records for 71 stations for the period 1939-92 were used. Attempts were also made to associate the temperature characteristics with the anomalies in the major systems that control the climate of the region including the El Nino-Southern Oscillation (ENSO), the quasi-biennial oscillation, and the prevailing convective processes represented by the outgoing longwave radiation. The northern part of the study region generally indicated nighttime warming and daytime cooling in recent years. The trend patterns were, however, reversed at coastal and lake areas. The Mozambique channel region showed cooling during both nighttime and daytime. There were thus large geographical and temporal variations in the observed trends, with some neighboring locations at times indicating opposite trends. A significant feature in the temperature variability patterns was the recurrence of extreme values. Such recurrences were significantly correlated with the patterns of convective activities, especially ENSO, cloudiness, and above/below normal rainfall. Although some of the variations in the trend patterns could be attributed to urbanization and land use patterns, such effects were not delineated in the current study. C1 Inst Meteorol Training & Res, Nairobi, Kenya. Univ Nairobi, Dept Meteorol, Nairobi, Kenya. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP King'uyu, SM (reprint author), Meteorol Serv, POB 101000, Gaborone, Botswana. NR 55 TC 37 Z9 39 U1 0 U2 4 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 AUG 15 PY 2000 VL 13 IS 16 BP 2876 EP 2886 DI 10.1175/1520-0442(2000)013<2876:RTOMAM>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 350YR UT WOS:000089129700003 ER PT J AU Chen, T Zhang, YC Rossow, WB AF Chen, T Zhang, YC Rossow, WB TI Sensitivity of atmospheric radiative heating rate profiles to variations of cloud layer overlap SO JOURNAL OF CLIMATE LA English DT Article ID GENERAL-CIRCULATION MODEL; UPPER-AIR OBSERVATIONS; HIGH-LEVEL CLOUDS; VERTICAL STRUCTURE; CLIMATE SIMULATIONS; SEASONAL-VARIATION; BUDGET EXPERIMENT; CIRRUS CLOUDS; ISCCP; SURFACE AB Three different cloud overlap schemes are applied to the International Satellite Cloud Climatology Project (ISCCP) vertical distribution of clouds in the radiative transfer model from the National Aeronautics and Space Administration Goddard Institute for Space Studies climate GCM to study the sensitivity of radiative fluxes and atmospheric radiative heating rate profiles to variations in cloud vertical structure. This study differs from previous ones because the ISCCP dataset constrains the total column optical thickness of the clouds at each location, a fact that is used to constrain cloud overlap occurrence. Moreover, this study considers the effects of cloud vertical structure on both shortwave (SW) and longwave (LW) fluxes at the top of the atmosphere, at the surface, and in the atmosphere. The in-atmosphere net fluxes are decomposed further into vertical profiles of radiative heating and cooling rates. The results show that the changes in the top-of-atmosphere (TOA) and surface (SRF) radiative fluxes vary among the different schemes, depending on the part of the atmosphere-surface system and spectral band (SW and LW) considered, but that the magnitudes of the changes generally are small. The scheme without a total optical thickness constraint produces opposite-signed changes in fluxes (except for the SRF LW flux) and the profile of atmospheric radiative heating rate in comparison with the schemes with the constraint. The constraint on total optical thickness eliminates nearly all of the effects on the total TOA and SRF radiation budget, significantly reducing the frequency of layer overlap occurrence and thereby reducing the effect of overlap on the radiative heating rate profiles. Even when the assumptions are changed to produce a frequency of occurrence of multilayer clouds that is similar to other estimates, the resulting changes in the radiative heating rate profile are quantitatively small. The magnitude of these changes is similar to the magnitude of the total overall cloud effect, however, making the layer overlap critical to accurate determinations of the shape of the radiative heating rate profiles. C1 Columbia Univ, Dept Appl Phys & Appl Math, New York, NY 10025 USA. Columbia Univ, Dept Earth & Environm Sci, New York, NY 10025 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Chen, T (reprint author), Columbia Univ, Dept Appl Phys & Appl Math, 2880 Broadway, New York, NY 10025 USA. RI Rossow, William/F-3138-2015 NR 45 TC 24 Z9 27 U1 0 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 AUG 15 PY 2000 VL 13 IS 16 BP 2941 EP 2959 DI 10.1175/1520-0442(2000)013<2941:SOARHR>2.0.CO;2 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 350YR UT WOS:000089129700007 ER PT J AU Rignot, E Padman, L MacAyeal, DR Schmeltz, M AF Rignot, E Padman, L MacAyeal, DR Schmeltz, M TI Observation of ocean tides below the Filchner and Ronne Ice Shelves, Antarctica, using synthetic aperture radar interferometry: Comparison with tide model predictions SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SOUTHERN WEDDELL SEA; SAR INTERFEROMETRY; CARLSON INLET; SATELLITE; STREAM; DYNAMICS; MOTION; FRONT AB Tides near and under floating glacial ice, such as ice shelves and glacier termini in fjords, can influence heat transport into the subice cavity, mixing of the under-ice water column, and the calving and subsequent drift of icebergs. Free-surface displacement patterns associated with ocean variability below glacial ice can be observed by differencing two synthetic aperture radar (SAR) interferograms, each of which represents the combination of the displacement patterns associated with the time-varying vertical motion and the time-independent lateral ice flow. We present the pattern of net free-surface displacement for the iceberg calving regions of the Ronne and Filchner Ice Shelves in the southern Weddell Sea. By comparing SAR-based displacement fields with ocean tidal models, the free-surface displacement variability for these regions is found to be dominated by ocean tides. The inverse barometer effect, i.e., the ocean's isostatic response to changing atmospheric pressure, also contributes to the observed vertical displacement. The principal value of using SAR interferometry in this manner lies in the very high lateral resolution (tens of meters) obtained over the large region covered by each SAR image. Small features that are not well resolved by the typical grid spacing of ocean tidal models may contribute to such processes as iceberg calving and cross-frontal ventilation of the ocean cavity under the ice shelf. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Earth & Space Res, Seattle, WA 98102 USA. Univ Chicago, Dept Geophys Sci, Chicago, IL 60637 USA. RP Rignot, E (reprint author), CALTECH, Jet Prop Lab, MS 300-235,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Rignot, Eric/A-4560-2014; OI Rignot, Eric/0000-0002-3366-0481; MacAyeal, Douglas/0000-0003-0647-6176 NR 34 TC 31 Z9 34 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD AUG 15 PY 2000 VL 105 IS C8 BP 19615 EP 19630 DI 10.1029/1999JC000011 PG 16 WC Oceanography SC Oceanography GA 344FJ UT WOS:000088748300010 ER PT J AU Durkee, PA Chartier, RE Brown, A Trehubenko, EJ Rogerson, SD Skupniewicz, C Nielsen, KE Platnick, S King, MD AF Durkee, PA Chartier, RE Brown, A Trehubenko, EJ Rogerson, SD Skupniewicz, C Nielsen, KE Platnick, S King, MD TI Composite ship track characteristics SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID AEROSOLS; CLIMATE AB The physical and radiative properties of a composite ship track are described from the analysis of 131 ship-ship track correlation pairs collected during the Monterey Area Ship Track experiment. The significant variability uf ship tracks around their average characteristics is also described. The nominal environmental conditions for the ship track set are also described. The composite ship track is 296 +/- 233 km long, 7.3 +/- 6 h old, and averages 9 +/- 5 km wide. The ship is, on the average, 16 +/- 8 km from of the head of the ship track along the relative wind vector and corresponds to a time of 2.5 +/- 15 min. The set of ship tracks examined in this study formed in marine boundary layers that were between 300 and 750 m deep, and no tracks formed in boundary layers above 800 m. The tracks form in regions of high relative humidity: small air-sea temperature differences, and moderate winds (average of 7.7 +/- 3.1 m s(-1)). The ambient cloud reflectance in advanced very high resolution radiometer channel 3 (3.7-mu m wavelength) is 11 +/- 4%, while the composite ship track Value is 14 +/- 5%. The relative track brightness is 7 +/- 26% and 37 +/- 34% for 0.63- and 3.7-mu m wavelengths, respectively. C1 USN, Postgrad Sch, Dept Meteorol, Monterey, CA 93943 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Durkee, PA (reprint author), USN, Postgrad Sch, Dept Meteorol, 589 Dyer Rd, Monterey, CA 93943 USA. RI King, Michael/C-7153-2011; Platnick, Steven/J-9982-2014 OI King, Michael/0000-0003-2645-7298; Platnick, Steven/0000-0003-3964-3567 NR 20 TC 46 Z9 47 U1 0 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD AUG 15 PY 2000 VL 57 IS 16 BP 2542 EP 2553 DI 10.1175/1520-0469(2000)057<2542:CSTC>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 347DH UT WOS:000088911800003 ER PT J AU Platnick, S Durkee, PA Nielsen, K Taylor, JP Tsay, SC King, MD Ferek, RJ Hobbs, PV Rottman, JW AF Platnick, S Durkee, PA Nielsen, K Taylor, JP Tsay, SC King, MD Ferek, RJ Hobbs, PV Rottman, JW TI The role of background cloud microphysics in the radiative formation of ship tracks SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID EFFECTIVE PARTICLE RADIUS; RADIOMETRIC CALIBRATION; STRATOCUMULUS CLOUDS; OPTICAL-THICKNESS; SATELLITE; FIRE; ALBEDO; SUSCEPTIBILITY; VALIDATION; ABSORPTION AB The authors investigate the extent to which the contrast brightness of ship tracks, that is, the relative change in observed solar reflectance, in visible and near-infrared imagery can be explained by the microphysics of the background cloud in which they form. The sensitivity of visible and near-infrared wavelengths for detecting reflectance changes in ship tracks is discussed, including the use of a modified cloud susceptibility parameter, termed the "contrast susceptibility," for assessing the sensitivity of background cloud microphysics on potential track development. It is shown that the relative change in cloud reflectance for ship tracks is expected to be larger in the near-infrared than in the visible and that 3.7-mu m channels, widely known to be useful for detecting tracks, have the greatest sensitivity. The usefulness of contrast susceptibility as a predictor of ship track contrast is tested with airborne and satellite remote sensing retrievals of background cloud parameters and track contrast. Retrievals are made with the high spatial resolution Moderate Resolution Imaging Spectroradiometer Airborne Simulator flown on the National Aeronautics and Space Administration's high-altitude ER-2 aircraft, and with the larger-scale perspective of the advanced very high resolution radiometer. Observed modifications in cloud droplet effective radius, optical thickness, liquid water path, contrast susceptibility, and reflectance contrast are presented for several ship tracks formed in background clouds with both small and large droplet sizes. The remote sensing results are augmented with in situ measurements of cloud microphysics that provide data at the smaller spatial scales. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Baltimore, MD 21228 USA. USN, Postgrad Sch, Dept Meteorol, Monterey, CA 93943 USA. Met Off, Meteorol Res Flight, Farnborough, Hants, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. Sci Applicat Int Corp, San Diego, CA 92121 USA. RP Platnick, S (reprint author), NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. RI King, Michael/C-7153-2011; Taylor, Jonathan/B-3786-2013; Tsay, Si-Chee/J-1147-2014; Platnick, Steven/J-9982-2014 OI King, Michael/0000-0003-2645-7298; Platnick, Steven/0000-0003-3964-3567 NR 45 TC 51 Z9 53 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 AUG 15 PY 2000 VL 57 IS 16 BP 2607 EP 2624 DI 10.1175/1520-0469(2000)057<2607:TROBCM>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 347DH UT WOS:000088911800007 ER PT J AU Taylor, JP Glew, MD Coakley, JA Tahnk, WR Platnick, S Hobbs, PV Ferek, RJ AF Taylor, JP Glew, MD Coakley, JA Tahnk, WR Platnick, S Hobbs, PV Ferek, RJ TI Effects of aerosols on the radiative properties of clouds SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID VAPOR CONTINUUM ABSORPTION; LIQUID-WATER PATH; EFFECTIVE RADIUS; BOUNDARY-LAYER; AIRCRAFT MEASUREMENTS; AIRBORNE MEASUREMENTS; ALBEDO; MODEL; SUSCEPTIBILITY; RETRIEVAL AB The influence of anthropogenic aerosols, in the form of ship exhaust effluent, on the microphysics and radiative properties of marine stratocumulus is studied using data gathered from the U.K. Mel. Office C-130 and the University of Washington C-131A aircraft during the Monterey Area Ship Track (MAST) experiment in 1994. During the period of MAST stratocumulus clouds were studied during 11 flights and a wide range of levels of background pollution was observed. The impact of the aerosol emitted from the ships was found to be very dependent on the background cloud microphysical conditions. In clouds of continental influence, the susceptibility of the cloud to further aerosol emissions was low, with a correspondingly weak microphysics and radiation signature in the ship tracks. In clean clouds, changes in droplet concentration of a factor of 2, and reductions in droplet size of up to 50%, were measured. These changes in the microphysics had significant impacts on the cloud radiative forcing. Furthermore, as a result of the cloud droplet size being reduced, in some cases the drizzle was suppressed in the clean clouds, resulting in an increase in Liquid water path in the polluted ship track environment. The impact of this combined change in liquid water path and droplet radius was to increase the cloud radiative forcing by up to a factor of 4. C1 Meteorol Off, Remote Sensing Branch, Meteorol Res Flight, Farnborough GU14 0LX, Hants, England. Oregon State Univ, Coll Ocean & Atmospher Sci, Corvallis, OR 97331 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Taylor, JP (reprint author), Meteorol Off, Remote Sensing Branch, Meteorol Res Flight, Farnborough GU14 0LX, Hants, England. RI Taylor, Jonathan/B-3786-2013; Platnick, Steven/J-9982-2014 OI Platnick, Steven/0000-0003-3964-3567 NR 48 TC 23 Z9 23 U1 0 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD AUG 15 PY 2000 VL 57 IS 16 BP 2656 EP 2670 DI 10.1175/1520-0469(2000)057<2656:EOAOTR>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 347DH UT WOS:000088911800010 ER PT J AU Ackerman, AS Toon, OB Taylor, JP Johnson, DW Hobbs, PV Ferek, RJ AF Ackerman, AS Toon, OB Taylor, JP Johnson, DW Hobbs, PV Ferek, RJ TI Effects of aerosols on cloud albedo: Evaluation of Twomey's parameterization of cloud susceptibility using measurements of ship tracks SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID MARINE STRATIFORM CLOUDS; BOUNDARY-LAYER; AIRBORNE MEASUREMENTS; STRATOCUMULUS CLOUDS; CONDENSATION NUCLEI; MICROPHYSICS; EMISSIONS AB Airborne measurements from the Meteorological Research Flight's Hercules C-130 and the University of Washington's Convair C-131A during the Monterey Area Ship Track field project are used to evaluate Twomey's analytic expression for cloud susceptibility, which describes the sensitivity of cloud albedo to changes in droplet concentrations, This expression incorporates assumptions about cloud physics, such as the independence of the cloud liquid water content and the width of the droplet size distribution on droplet concentrations. Averaged over all 69 ship track penetrations, cloud liquid water content decreased slightly and the droplet size distributions broadened from the ambient values. For the 17 cases for which albedos were measured during overflights, Twomey's parameterization represents the trend of albedo changes with droplet concentrations remarkably well, passing through the midpoints of the considerable spread in the data. The fortuitous agreement results from compensating changes in cloud properties. To ether with the albedo changes, the changes in cloud liquid water content and droplet size distributions imply that cloud thickness usually increased in the ship tracks. Such an increase was observed on the occasions that changes in cloud thickness were recorded (in the Sanko Pence ship track during very clean ambient condilions). Unfortunately systematic measurements of cloud thickness were not made for most of the ship tracks observed. The greatest outlier in the data corresponds to measurements made under horizontally inhomogeneous ambient conditions; possible explanations for its divergence include an increase in cloud thickness or an error in matching above-cloud. albedo measurements with in-cloud microphysics measurements. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. Univ Colorado, Program Atmospher & Ocean Sci, Boulder, CO 80309 USA. Meteorol Off, Meteorol Res Flight, Farnborough, Hants, England. Univ Washington, Seattle, WA 98195 USA. RP Ackerman, AS (reprint author), NASA, Ames Res Ctr, MS 245-4, Moffett Field, CA 94035 USA. RI Ackerman, Andrew/D-4433-2012; Taylor, Jonathan/B-3786-2013 OI Ackerman, Andrew/0000-0003-0254-6253; NR 32 TC 83 Z9 91 U1 1 U2 6 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD AUG 15 PY 2000 VL 57 IS 16 BP 2684 EP 2695 DI 10.1175/1520-0469(2000)057<2684:EOAOCA>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 347DH UT WOS:000088911800012 ER PT J AU Ferek, RJ Garrett, T Hobbs, PV Strader, S Johnson, D Taylor, JP Nielsen, K Ackerman, AS Kogan, Y Liu, QF Albrecht, BA Babb, D AF Ferek, RJ Garrett, T Hobbs, PV Strader, S Johnson, D Taylor, JP Nielsen, K Ackerman, AS Kogan, Y Liu, QF Albrecht, BA Babb, D TI Drizzle suppression in ship tracks SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID CLOUD CONDENSATION NUCLEI; MARINE STRATOCUMULUS CLOUDS; EDDY SIMULATION-MODEL; LIQUID-WATER PATH; BOUNDARY-LAYER; EXPLICIT MICROPHYSICS; RADIOMETRIC OBSERVATIONS; STRATIFORM CLOUDS; EFFECTIVE RADIUS; AIRCRAFT AB Although drizzle was a relatively infrequent occurrence during the Monterey Area Ship Track study, diverse measurements from several sources produced data signals consistent with a reduction in drizzle drops in stratus clouds affected by ship effluents. Concurrent increases in liquid water in the cloud droplet size range, due to redistribution from the drizzle mode, were not always observed, possibly because of the relatively small and often negligible amounts of water in the drizzle mode. Significant changes in cloud droplet size distribution, as well as reductions in drizzle flux and concentrations of drops >50-mu m radius, were observed in ship tracks when drizzle was more uniformly present in the ambient cloud. Radiometric measurements showed that increased droplet concentrations in ship tracks, which resulted in reduced droplet sizes, can significantly alter the liquid water path. Radar observations indicated that the reduced reflectivities of ship tracks compared with ambient clouds may be due to reductions in the concentrations of larger drops and/or reductions in the sizes of these drops. Two independent modeling studies showed decreases in drizzle in ship tracks due to the presence of smaller cloud droplets that reduced the efficiency of drop growth by collisions. C1 Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. Meteorol Off, Farnborough, Hants, England. Naval Postgrad Sch, Dept Meteorol, Monterey, CA USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Oklahoma, Cooperat Inst Mesoscale Meteorol Studies, Norman, OK 73019 USA. Penn State Univ, Dept Meteorol, University Pk, PA 16802 USA. RP Hobbs, PV (reprint author), Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. RI Ackerman, Andrew/D-4433-2012; Taylor, Jonathan/B-3786-2013 OI Ackerman, Andrew/0000-0003-0254-6253; NR 48 TC 69 Z9 70 U1 0 U2 2 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 AUG 15 PY 2000 VL 57 IS 16 BP 2707 EP 2728 DI 10.1175/1520-0469(2000)057<2707:DSIST>2.0.CO;2 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 347DH UT WOS:000088911800014 ER PT J AU Coakley, JA Durkee, PA Nielsen, K Taylor, JP Platnick, S Albrecht, BA Babb, D Chang, FL Tahnk, WR Bretherton, CS Hobbs, PV AF Coakley, JA Durkee, PA Nielsen, K Taylor, JP Platnick, S Albrecht, BA Babb, D Chang, FL Tahnk, WR Bretherton, CS Hobbs, PV TI The appearance and disappearance of ship tracks on large spatial scales SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID HIGH-RESOLUTION RADIOMETER; MARINE BOUNDARY-LAYER; SEA-SURFACE TEMPERATURE; TO-CUMULUS TRANSITION; NUMERICAL-SIMULATION; STRATOCUMULUS; CALIBRATION; SATELLITE; CHANNELS; MODEL AB The 1-km advanced very high resolution radiometer observations from the morning, NOAA-12, and afternoon, NOAA-11, satellite passes over the coast of California during June 1994 are used to determine the altitudes, visible optical depths, and cloud droplet effective radii for low-level clouds. Comparisons are made between the properties of clouds within 50 km of ship tracks and those farther than 200 km from the tracks in order to deduce the conditions that are conducive to the appearance of ship tracks in satellite images. The results indicate that the low-level clouds must be sufficiently close to the surface for ship tracks to form. Ship tracks rarely appear in low-level clouds having altitudes greater than 1 km. The distributions of visible optical depths and cloud droplet effective radii for ambient clouds in which ship tracks are embedded are the same as those for clouds without ship tracks. Cloud droplet sizes and liquid water paths for low-level clouds do not constrain the appearance of ship tracks in the imagery. The sensitivity of ship tracks to cloud altitude appears to explain why the majority of ship tracks observed from satellites off the coast of California are found south of 35 degrees N. A small rise in the height of low-level clouds appears to explain why numerous ship tracks appeared on one day in a particular region but disappeared on the next, even though the altitudes of the low level clouds were generally less than 1 km and the cloud cover was the same for both days. In addition, ship tracks are frequent when low-level clouds at altitudes below 1 km are extensive and completely cover large areas. The frequency of imagery pixels overcast by clouds with altitudes below 1 km is greater in the morning than in the afternoon and explains why more ship tracks are observed in the morning than in the afternoon. If the occurrence of ship tracks in satellite imagery data depends on the coupling of the clouds to the underlying boundary layer, then cloud-top altitude and the area of complete cloud cover by low-level clouds may be useful indices for this coupling. C1 Oregon State Univ, Coll Ocean & Atmospher Sci, Corvallis, OR 97331 USA. Naval Postgrad Sch, Dept Meteorol, Monterey, CA USA. Meteorol Off, Farnborough, Hants, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Miami, RSMAS, MPO, Coral Gables, FL 33124 USA. Penn State Univ, Dept Meteorol, University Pk, PA 16802 USA. Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. RP Coakley, JA (reprint author), Oregon State Univ, Coll Ocean & Atmospher Sci, Oceanog Adm 104, Corvallis, OR 97331 USA. RI Taylor, Jonathan/B-3786-2013; Platnick, Steven/J-9982-2014 OI Platnick, Steven/0000-0003-3964-3567 NR 29 TC 30 Z9 30 U1 0 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD AUG 15 PY 2000 VL 57 IS 16 BP 2765 EP 2778 DI 10.1175/1520-0469(2000)057<2765:TAADOS>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 347DH UT WOS:000088911800017 ER PT J AU Berkoff, TA Whiteman, DN Rallison, RD Schwemmer, GK Ramos-Izquierdo, L Plotkin, H AF Berkoff, TA Whiteman, DN Rallison, RD Schwemmer, GK Ramos-Izquierdo, L Plotkin, H TI Remote detection of Raman scattering by use of a holographic optical element as a dispersive telescope SO OPTICS LETTERS LA English DT Article ID LIDAR; AEROSOLS AB We describe the retrieval of nighttime lidar profiles by use of a large holographic optical element to simultaneously celled and spectrally disperse Raman-shifted return signals. Results obtained with a 20-Hz, 6-mJ/pulse, frequency-tripled Nd:YAG source demonstrate profiles for atmospheric nitrogen with a range greater than 1 km for a time average of 26 s. (C) 2000 Optical Society of America. OCIS codes: 280.3640, 290.5860, 090.2890. C1 NASA, Goddard Space Flight Ctr, Earth Sci Directorate, Greenbelt, MD 20771 USA. RP Berkoff, TA (reprint author), NASA, Goddard Space Flight Ctr, Earth Sci Directorate, Code 924 & Code 912, Greenbelt, MD 20771 USA. NR 8 TC 2 Z9 2 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 AUG 15 PY 2000 VL 25 IS 16 BP 1201 EP 1203 DI 10.1364/OL.25.001201 PG 3 WC Optics SC Optics GA 343XH UT WOS:000088727400023 PM 18066167 ER PT J AU Anantram, MP AF Anantram, MP TI Current-carrying capacity of carbon nanotubes SO PHYSICAL REVIEW B LA English DT Article AB The current carrying capacity of ballistic electrons in carbon nanotubes that are coupled to ideal contacts is analyzed. At small applied voltages, electrons are injected only into crossing subbands, the differential conductance is 4e(2)/h. At applied voltages larger than Delta E-NC/2e (Delta E-NC is the energy level spacing of first noncrossing subbands), electrons are injected into noncrossing subbands. The contribution of these electrons to current is determined by the competing processes of Bragg reflection and Zener-type intersubband tunneling. In small diameter nanotubes, Bragg reflection dominates, and the maximum differential conductance is comparable to 4e(2)/h. Intersubband Zener tunneling can be non-negligible as the nanotube diameter increases, because Delta E-NC is inversely proportional to the diameter. As a result, with increasing nanotube diameter, the differential conductance becomes larger than 4e(2)/h, though not comparable to the large number of subbands into which electrons are injected from the contacts. These results may be relevant to recent experiments in large diameter multiwall nanotubes that observed conductances larger than 4e(2)/h. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Anantram, MP (reprint author), NASA, Ames Res Ctr, Mail Stop T27A-1, Moffett Field, CA 94035 USA. NR 11 TC 38 Z9 38 U1 0 U2 9 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 EI 1550-235X J9 PHYS REV B JI Phys. Rev. B PD AUG 15 PY 2000 VL 62 IS 8 BP R4837 EP R4840 DI 10.1103/PhysRevB.62.R4837 PG 4 WC Physics, Condensed Matter SC Physics GA 348TU UT WOS:000089003200018 ER PT J AU Chung, DJH Kolb, EW Riotto, A Tkachev, II AF Chung, DJH Kolb, EW Riotto, A Tkachev, II TI Probing Planckian physics: Resonant production of particles during inflation and features in the primordial power spectrum SO PHYSICAL REVIEW D LA English DT Article ID MICROWAVE BACKGROUND ANISOTROPIES; SUPERDUSTER-VOID NETWORK; LARGE-SCALE STRUCTURE; COLD DARK-MATTER; COSMOLOGICAL PERTURBATIONS; BARYONIC FEATURES; REDSHIFT SURVEYS; EARLY UNIVERSE; FLUCTUATIONS; PARAMETERS AB The phenomenon of the resonant production of particles after inflation has received much attention in the past few years. In a new application of the resonant production of particles, we consider the effect of a resonance hiring inflation. We show that if the inflaton is coupled to a massive particle, resonant production of the particle during inflation modifies the evolution of the inflaton, and may leave an imprint in the form of sharp features in the primordial power spectrum. Precision measurements of microwave background anisotropies and large-scale structure surveys could be sensitive to the features, and probe the spectrum of particles as massive as the Planck scale. C1 Univ Michigan, Randall Lab Phys, Ann Arbor, MI 48109 USA. Fermi Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Chicago, Enrico Fermi Inst, Dept Astron & Astrophys, Chicago, IL 60637 USA. CERN, Div Theory, CH-1211 Geneva 23, Switzerland. Russian Acad Sci, Inst Nucl Res, Moscow 117312, Russia. RP Chung, DJH (reprint author), Univ Michigan, Randall Lab Phys, Ann Arbor, MI 48109 USA. NR 54 TC 133 Z9 135 U1 1 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 AUG 15 PY 2000 VL 62 IS 4 BP art. no. EP 043508 DI 10.1103/PhysRevD.62.043508 PG 13 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 345AK UT WOS:000088793100023 ER PT J AU Estabrook, FB Tinto, M Armstrong, JW AF Estabrook, FB Tinto, M Armstrong, JW TI Time-delay analysis of LISA gravitational wave data: Elimination of spacecraft motion effects SO PHYSICAL REVIEW D LA English DT Article AB LISA (Laser Interferometer Space Antenna) is a proposed mission which will use coherent laser beams exchanged between three remote spacecraft to detect and study low-frequency cosmic gravitational radiation. Modeling each spacecraft as moving almost inertially, rigidly carrying a laser, beam splitters and photodetectors, we previously showed how the measured time series of Doppler shifts of the six one-way laser beams between spacecraft pairs could be combined, with suitable time delays, to cancel exactly the otherwise overwhelming phase noise of the lasers. Three of the combinations synthesized data that could in principle be obtained if the spacecraft separations were very precisely equal, as in Michelson interferometry; seven other combinations offered possible design advantages and useful redundancy. Hen we extend those results by presenting time-delay equations for Doppler data from the actual drag-free configuration envisaged for the LISA mission. Each spacecraft will carry two proof-masses, shielded within two non-inertial optical benches carrying lasers and photodetectors. In this full drag-free configuration there are now twelve Doppler data streams, six measured with beams between the three vertex spacecraft and two with beams between each of the optical bench pairs on the three spacecraft. We show that generalizations of our previous linear data combinations, now using these twelve one-way Doppler measurements, can cancel the noises of all six lasers and also remove Doppler shifts due to the non-inertial motions of the six optical benches. It is noteworthy that adjacent optical benches need not be rigidly connected and that no phase locking of their lasers is required. From the latest LISA estimates for power spectra of remaining Doppler noises (very-low-level proof-mass "acceleration" noise, photodetector shot noise, and beam pointing noise) we compute the sensitivities of the generalized data combinations X and P. In the Appendix we give defining equations and sensitivity results for two additional data combinations, denoted E and U. Like X and P, these combinations only require data from four one-way laser links between the LISA spacecraft. LISA can achieve the desired gravitational wave strain performance of similar to 10(-23) with any of these combinations. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Estabrook, FB (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 70 Z9 72 U1 0 U2 3 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 AUG 15 PY 2000 VL 62 IS 4 BP art. no. EP 042002 DI 10.1103/PhysRevD.62.042002 PG 8 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 345AK UT WOS:000088793100007 ER PT J AU Waga, I Frieman, JA AF Waga, I Frieman, JA TI New constraints from high redshift supernovae and lensing statistics upon scalar field cosmologies SO PHYSICAL REVIEW D LA English DT Article ID STRING-DOMINATED UNIVERSE; GRAVITATIONAL LENSES; SCALING SOLUTIONS; COSMIC EQUATION; DARK ENERGY; CONSTANT; MODELS; LAMBDA; QUINTESSENCE; EVOLUTION AB We explore the implications of gravitationally lensed quasistellar objects and high-redshift SNe Ia observations for spatially hat cosmological models in which a classically evolving scalar field currently dominates the energy density of the Universe. We consider two representative scalar field potentials that give rise to effective decaying Lambda ("quintessence") models: pseudo Nambu-Goldstone bosons [V(phi) = M-4(1 + cos(phi/f))] and an inverse power-law potential [V(phi) = M(4+alpha)phi(-alpha)]. We show that a large region of parameter space is consistent with current data if Omega(m0)>0.15. On the other hand, a higher lower bound for the matter density parameter suggested by large-scale galaxy hows, Omega(m0)>0.3, considerably reduces the allowed parameter space, forcing the scalar field behavior to approach that of a cosmological constant. C1 Univ Fed Rio de Janeiro, Inst Fis, BR-21945970 Rio De Janeiro, Brazil. Fermi Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Waga, I (reprint author), Univ Fed Rio de Janeiro, Inst Fis, BR-21945970 Rio De Janeiro, Brazil. RI Waga, Ioav/B-6288-2014 NR 88 TC 47 Z9 47 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 AUG 15 PY 2000 VL 62 IS 4 AR 043521 DI 10.1103/PhysRevD.62.043521 PG 5 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 345AK UT WOS:000088793100036 ER PT J AU Barth, E Watson, AB AF Barth, E Watson, AB TI A geometric framework for nonlinear visual coding SO OPTICS EXPRESS LA English DT Article ID AREA MT; MOTION; MODEL; DIRECTION; MACAQUE; MECHANISMS; CURVATURE; RESPONSES; NEURONS; FILTERS AB It is argued that important aspects of early and middle level visual coding may be understood as resulting from basic geometric processing of the visual input. The input is treated as a hypersurface defined by image intensity as a function of two spatial coordinates and time. Analytical results show how the Riemann curvature tensor R of this hypersurface represents speed and direction of motion. Moreover, the results can predict the selectivity of MT neurons for multiple motions and for motion in a direction along the optimal spatial orientation. Finally, a model based on integrated R components predicts global-motion percepts related to the barber-pole illusion. (C) 2000 Optical Society of America. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Barth, E (reprint author), Med Univ Lubeck, Inst Signal Proc, Ratzeburger Allee 160, D-23538 Lubeck, Germany. NR 41 TC 17 Z9 17 U1 0 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1094-4087 J9 OPT EXPRESS JI Opt. Express PD AUG 14 PY 2000 VL 7 IS 4 BP 155 EP 165 PG 11 WC Optics SC Optics GA 344MW UT WOS:000088764300001 PM 19407860 ER PT J AU Wingard, CD AF Wingard, CD TI Characterization of prepreg and cured epoxy/fiberglass composite material for use in advanced composite piping systems SO THERMOCHIMICA ACTA LA English DT Article; Proceedings Paper CT 26th North-American-Thermal-Analysis-Society Conference CY SEP 13-15, 1998 CL CLEVELAND, OHIO DE epoxy/fiberglass prepreg; glass transition temperature (T-g); activation energy; DSC AB A company that uses epoxy/fiberglass prepreg material in advanced composite piping systems requested that the NASA/Marshall Space Flight Center (MSFC) use several thermal analysis techniques to characterize the material. Dynamic and isothermal tests by use of the TA Instruments 2920 Differential Scanning Calorimeter (DSC) yielded cure kinetics on the prepreg. The dynamic data showed two exothermic cure reactions for the prepreg, but isothermal data showed that the first cure exotherm was a low temperature event and began to disappear near 105 degrees C. For the second cure exotherm, activation energies (E-2) of 79.0 and 87.1 kJ/mol were obtained from the dynamic and isothermal data, respectively. Partial cure of the prepreg for several isothermal cure temperatures and times yielded a glass transition temperature (T-g) versus conversion plot with an approximate gelation point of the prepeg at 63% conversion. At a cure temperature of 135 degrees C and a T-g of 103 degrees C, most of the ultimate cure of the prepreg was achieved. The TA Instruments 983 Dynamic Mechanical Analyzer (DMA) yielded activation energies of cure of 140 (E-1) and 50.5 (E-2) kT/mol for the first and second cure reactions, respectively, based on times to gelation at several cure temperatures. A DMA temperature sweep at several fixed frequencies yielded an average activation energy of 357 kJ/mol for the T-g of the epoxy/fiberglass composite in cured sheet form. The fiber filler is a fiberglass mat, and DMA data as well as thermomechanical analysis (TMA) data on the cured sheet material showed a slight dependence on mat direction for the measured properties. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Wingard, CD (reprint author), NASA, George C Marshall Space Flight Ctr, Mail Code ED34, Huntsville, AL 35812 USA. NR 5 TC 22 Z9 26 U1 1 U2 14 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-6031 J9 THERMOCHIM ACTA JI Thermochim. Acta PD AUG 14 PY 2000 VL 357 BP 293 EP 301 DI 10.1016/S0040-6031(00)00400-7 PG 9 WC Thermodynamics; Chemistry, Analytical; Chemistry, Physical SC Thermodynamics; Chemistry GA 334RW UT WOS:000088200300038 ER PT J AU Wingard, CD AF Wingard, CD TI Aging study of neoprene FB uncured rubber in support of an obsolescence issue for EPDM rubber insulation used in the Reusable Solid Rocket Motor of the Space Shuttle SO THERMOCHIMICA ACTA LA English DT Article; Proceedings Paper CT 26th North-American-Thermal-Analysis-Society Conference CY SEP 13-15, 1998 CL CLEVELAND, OHIO DE neoprene FB; EPDM rubber insulation; Nordel polymers AB Thioliol/Wasatch (TC/W) in Utah is the manufacturer of the Reusable Solid Rocket Motor (RSRM) for the Space Shuttle, and filled EPDM and NBR rubber insulators are used on RSRM for erosion resistance. Since DuPont/Dow is closing production lines for Neoprene FB and two Nordel EPDM polymers used in three EPDM insulators for RSRM, TC/W will stockpile 6-7 years of Neoprene FB and Nordel to support RSRM production until reformulated EPDMs can be developed and recertified. NASA/MSFC used several thermal analysis techniques to study the effect of aging on a lot of uncured Neoprene FB kept in cold storage at 40 degrees F (4.4 degrees C) for more than 11 years ('old'). A lot of uncured Neoprene FB kept in cold storage for 8 months ('new') was used for comparison in the study. In processing of uncured calendered sheets by the Shuttle vendor that are later cured near 150 degrees C as RSRM insulation by TC/W, Neoprene FB is mixed into the EPDM formulation at 105"C. Uncured Neoprene FB is a solid at room temperature with a texture similar to that of cheese, but was shown by DSC to have a peak melting endotherm at 50 degrees C, becoming a low viscosity liquid until it begins to cross-link at higher temperatures. From a DMA study on the uncured 'old' and 'new' lots of Neoprene FB at cure temperatures of 95, 105 and 115 degrees C, a linear Arrhenius relationship of the logarithm of the time to gelation versus reciprocal absolute temperature yielded activation energies for the two lots of rubber When this: linear relationship was extrapolated down to the cold storage temperature of 4.4 degrees C, gel times of the 'old' and 'new' rubber lots were predicted to be 12.7 and 72.6 years, respectively. This data shows that the 'old' lot of Neoprene FB still has a considerably useful shelf life in cold storage. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Wingard, CD (reprint author), NASA, George C Marshall Space Flight Ctr, Mail Code ED34, Huntsville, AL 35812 USA. NR 6 TC 2 Z9 3 U1 0 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-6031 J9 THERMOCHIM ACTA JI Thermochim. Acta PD AUG 14 PY 2000 VL 357 BP 303 EP 312 DI 10.1016/S0040-6031(00)00401-9 PG 10 WC Thermodynamics; Chemistry, Analytical; Chemistry, Physical SC Thermodynamics; Chemistry GA 334RW UT WOS:000088200300039 ER PT J AU Boldt, E Loewenstein, M AF Boldt, E Loewenstein, M TI Cosmic ray generation by quasar remnants: constraints and implications SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE acceleration of particles; accretion, accretion discs; black hole physics; cosmic rays; galaxies : nuclei ID ACTIVE GALACTIC NUCLEI; HOST GALAXIES; BLACK-HOLES; ENERGY AB The quasar remnant cores of nearby giant elliptical galaxies NGC 4486 (M87), 1399, 4649 and 4472 are the sites of supermassive (>10(9)M.) black holes. These objects are investigated as to the viability of the conjecture that they could harbour compact dynamos capable of generating the highest energy cosmic rays. For an accretion process involving an equipartition magnetic field near the event horizons of the underlying putative spun-up black holes, the energy achievable in accelerating protons could well be greater than or equal to 10(20)eV for all these galaxies when only considering the drag induced by curvature radiation. Estimates of the spectral energy distribution (SED) of ambient core photons lead to the conclusion that the energy losses arising from photo-pion production in proton collisions with these target photons are relatively small for all but M87. For M87, the ambient photon field is likely to be a limiting factor. Accretion rates of similar to 1 M. yr(-1), comparable to the Bondi rates and to the stellar mass-loss rates, are associated with (>10(20)eV) cosmic ray generation in the other (electromagnetically dark) galactic core sites. If these sites are found to be sources of such cosmic rays, it would suggest the presence of a global inflow of interstellar gas all the way into the centre of the host galaxy. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. EM boldt@lheavx.gsfc.nasa.gov; loew@larmes.gsfc.nasa.gov NR 38 TC 25 Z9 25 U1 0 U2 0 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0035-8711 EI 1365-2966 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD AUG 11 PY 2000 VL 316 IS 3 BP L29 EP L33 DI 10.1046/j.1365-8711.2000.03768.x PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347BE UT WOS:000088905700001 ER PT J AU Laitinen, T Klein, KL Kocharov, L Torsti, J Trottet, G Bothmer, V Kaiser, ML Rank, G Reiner, MJ AF Laitinen, T Klein, KL Kocharov, L Torsti, J Trottet, G Bothmer, V Kaiser, ML Rank, G Reiner, MJ TI Solar energetic particle event and radio bursts associated with the 1996 July 9 flare and coronal mass ejection SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE Sun : corona; Sun : flares; Sun : particle emission ID COSMIC-RAY EVENT; MEV PROTONS; GAMMA-RAYS; ACCELERATION; SHOCK; INJECTION; ERNE; PROPAGATION; ANISOTROPY; INSTRUMENT AB Using spaceborne particle and gamma-ray detection and radio diagnostics we study solar energetic particle (SEP) production in the 1996 July 9 event. This event is associated with an impulsive soft X-ray flare (9:10 UT) and a coronal mass ejection (CME). In a global classification the event is considered as mixed-impulsive. A sequence of acceleration processes is identified, starting early in the flare impulsive phase and continuing throughout the period when the CME propagated up to several Ro above the photosphere: (1) Gamma-ray, hard X-ray and cm-wave emitting particles seen during the flare impulsive phase in the low corona had no counterpart at the Solar and Heliospheric Observatory (SoHO) spacecraft. (2) Electrons accelerated at a coronal shock wave were revealed by decimetric-to-metric type II radio emission and by simultaneous radio signatures of beams traveling to 1 AU. (3) Mildly relativistic (greater than or equal to 250 keV) electrons detected by SoHO did not correspond to these shock-accelerated populations, but to later mainly impulsive injection which was associated with radio brightenings over a large range of coronal altitudes. (4) Energetic protons detected by SoHO were accelerated during about 100 min after the flare impulsive phase with a gradually evolving production profile that bore some similarity with the time profile of broadband metric (type IV) emission. (5) While all other particle signatures decayed, a second period of interplanetary proton production took place greater than or equal to 2 hours after flare onset. The first, 100 min period of SEP acceleration, post-impulsive phase coronal acceleration, is definitely dominant in mildly relativistic electrons. Two acceleration periods nearly equally contribute to the production of similar to 20 MeV protons. However, the second period is more productive in low energy, similar to 1 MeV, protons. The timing of the SEP injections indicates that neither the impulsive hare acceleration in the low corona nor the interplanetary CME at greater than or equal to 10 R-circle dot are the main sources of the high-energy particles observed onboard SoHO. We suggest that various acceleration processes related to the reconfiguration of the corona in the course of the flare and CME lift-off contribute to the interacting and escaping particle populations, with different signatures at different energies and in different species. C1 Univ Turku, Dept Phys, Space Res Lab, Turku 20014, Finland. Observ Paris, DASOP, Meudon Sect, F-92195 Meudon, France. CNRS, UMR 8645, F-92195 Meudon, France. Univ Kiel, Inst Expt & Angew Phys, D-24118 Kiel, Germany. Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. Raytheon ITSS, Lanham, MD 20706 USA. RP Kocharov, L (reprint author), Univ Turku, Dept Phys, Space Res Lab, Turku 20014, Finland. EM leon.kocharov@srl.utu.fi RI Laitinen, Timo/B-2188-2009 OI Laitinen, Timo/0000-0002-7719-7783 NR 48 TC 34 Z9 34 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD AUG 10 PY 2000 VL 360 IS 2 BP 729 EP 741 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 354LF UT WOS:000089331400039 ER PT J AU Sahai, R Bujarrabal, V Castro-Carrizo, A Zijlstra, A AF Sahai, R Bujarrabal, V Castro-Carrizo, A Zijlstra, A TI The structure and momentum of multiple collimated outflows in the protoplanetary nebula Frosty Leo SO ASTRONOMY & ASTROPHYSICS LA English DT Letter DE stars : AGB and post-AGB; stars : mass-loss; ISM : reflection nebulae; ISM : individual objects ID CIRCUMSTELLAR ENVELOPE; IRAS 09371 AB We have discovered multiple jet-like features in the inner regions of the protoplanetary nebula (PPN) Frosty Lee, in optical images obtained with the Hubble Space Telescope. Frosty Leo is only the second PPN (after CRL2688) and the first oxygen-rich one, to show well-focussed jets close to the equatorial plane. The nebula consists of two bright compact structures embedded inside two large tenuous bubbles, separated by a flaring, roughly edge-on disk. The relatively high surface brightnesses of two ansae and substructures in the jets imply that the latter have carved out holes in the optically thick central region of the nebula, allowing starlight to escape with very little attenuation. Millimeter-wave CO line observations with the IRAM 30m radiotelescope show the presence of slow (similar to 10km s(-1)) and fast (>50km s(-1)) components in a molecular outflow associated with the bright inner(< 10 ") regions of the nebula. The mechanical momentum in the fast outflow is about a factor 500 larger than that available from the stellar radiation (L/c) during the post-AGE life of the source, and most likely derives from the gravitational energy of a close binary central star. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Observ Astron Nacl, Alcala De Henares 28800, Spain. UMIST, Dept Phys, Manchester M60 1QD, Lancs, England. RP Sahai, R (reprint author), CALTECH, Jet Prop Lab, MS 183-900, Pasadena, CA 91109 USA. NR 17 TC 24 Z9 24 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 AUG 10 PY 2000 VL 360 IS 2 BP L9 EP L12 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 354LF UT WOS:000089331400001 ER PT J AU Grego, L Carlstrom, JE Joy, MK Reese, ED Holder, GP Patel, S Cooray, AR Holzapfel, WL AF Grego, L Carlstrom, JE Joy, MK Reese, ED Holder, GP Patel, S Cooray, AR Holzapfel, WL TI The Sunyaev-Zeldovich effect in Abell 370 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations; galaxies : clusters : individual (Abell 370); techniques : interferometric ID X-RAY; INTRACLUSTER GAS; GALAXY CLUSTERS; DEUTERIUM; EMISSION; STATE AB We present interferometric measurements of the Sunyaev-Zeldovich (SZ) effect toward the galaxy cluster Abell 370. These measurements, which directly probe the pressure of the cluster's gas, show the gas distribution to be strongly aspherical, as do the X-ray and gravitational lensing observations. We calculate the cluster's gas mass fraction in two ways. We first compare the gas mass derived from the SZ measurements to the lensing-derived gravitational mass near the critical lensing radius. We also calculate the gas mass fraction from the SZ data by deprojecting the three-dimensional gas density distribution and deriving the total mass under the assumption that the gas is in hydrostatic equilibrium (HSE). We test the assumptions in the HSE method by comparing the total cluster mass implied by the two methods and find that they agree within the errors of the measurement. We discuss the possible systematic errors in the gas mass fraction measurement and the constraints it places on the matter density parameter, Omega(M). C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. Univ Alabama, Dept Astron, Huntsville, AL 35899 USA. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. RP Grego, L (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Holzapfel, William/I-4836-2015 NR 45 TC 37 Z9 37 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2000 VL 539 IS 1 BP 39 EP 51 DI 10.1086/309190 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347RQ UT WOS:000088943300005 ER PT J AU Staren, J Meinhold, P Childers, J Lim, M Levy, A Lubin, P Seiffert, M Gaier, T Figueiredo, N Villela, T Wuensche, CA Tegmark, M De Oliveira-Costa, A AF Staren, J Meinhold, P Childers, J Lim, M Levy, A Lubin, P Seiffert, M Gaier, T Figueiredo, N Villela, T Wuensche, CA Tegmark, M De Oliveira-Costa, A TI Spin-modulated telescope to make two-dimensional cosmic microwave background maps SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations instrumentation : detectors ID INTERMEDIATE ANGULAR SCALES; ANISOTROPY; RADIATION AB We describe the HEMT Advanced Cosmic Microwave Explorer (HACME), a balloon-borne experiment designed to measure subdegree-scale cosmic microwave background anisotropy over hundreds of deg(2), using a unique two-dimensional scanning strategy. A spinning flat mirror that is canted relative to its spin axis modulates the direction of beam response in a nearly elliptical path on the sky. The experiment was successfully flown in 1996 February, achieving near laboratory performance for several hours at float altitude. A map free of instrumental systematic effects is produced for a 3.5 hr observation of 630 deg(2), resulting in a flat-band power upper limit of [l(l + 1)C-I/(2 pi)](0.5) < 77 mu K at l = 38(-20)(+25) (95% confidence). The experiment design, flight operations, and data, including atmospheric effects and noise performance, are discussed. C1 Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Escola Fed Engn Itajuba, BR-37500000 Itajuba, MG, Brazil. Inst Natl Pesquisas Espacials, Div Astrofis, BR-12225010 Sao Jose Dos Campos, SP, Brazil. Univ Penn, Dept Phys, Philadelphia, PA 19104 USA. RP Staren, J (reprint author), Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. RI Figueiredo, Newton/F-9976-2011 NR 22 TC 7 Z9 7 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2000 VL 539 IS 1 BP 52 EP 56 DI 10.1086/309236 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347RQ UT WOS:000088943300006 ER PT J AU Holzapfel, WL Carlstrom, JE Grego, L Holder, G Joy, M Reese, ED AF Holzapfel, WL Carlstrom, JE Grego, L Holder, G Joy, M Reese, ED TI Limits on arcminute-scale cosmic microwave background anisotropy at 28.5 GHz SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations ID GALACTIC EMISSION; POWER SPECTRUM; RADIO-SOURCES; RADIATION; FLUCTUATIONS; REIONIZATION; SEARCH; CMB; CLUSTERS; GALAXIES AB We have used the Berkeley-Illinois-Maryland Association (BIMA) millimeter array outfitted with sensitive centimeter-wave receivers to search for cosmic microwave background (CMB) anisotropies on arcminute scales. The interferometer was placed in a compact configuration that produces high brightness sensitivity, while providing discrimination against point sources. Operating at a frequency of 28.5 GHz, the FWHM primary beam of the instrument is similar to 6'.6. We have made sensitive images of seven fields, four of which where chosen specifically to have low IR dust contrast and to be free of bright radio sources. Additional observations with the Owens Valley Radio Observatory (OVRO) millimeter array were used to assist in the location and removal of radio point sources. Applying a Bayesian analysis to the raw visibility data, we place limits on CMB anisotropy flat-band power of Q(flat) = 5.6(-5.6)(+3.0) mu K and Q(flat) < 14.1 mu K at 68% and 95% confidence, respectively. The sensitivity of this experiment to flat-band power peaks at a multipole of l = 5470, which corresponds to an angular scale of similar to 2'. The most likely value of Q(flat) is similar to the level of the expected secondary anisotropies. C1 Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Holzapfel, WL (reprint author), Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. RI Holzapfel, William/I-4836-2015 NR 45 TC 18 Z9 18 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2000 VL 539 IS 1 BP 57 EP 66 DI 10.1086/309211 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347RQ UT WOS:000088943300007 ER PT J AU Holzapfel, WL Carlstrom, JE Grego, L Joy, M Reese, ED AF Holzapfel, WL Carlstrom, JE Grego, L Joy, M Reese, ED TI Investigation of two reported arcminute-scale microwave decrements at 28.5 GHz SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations; galaxies : clusters : general; techniques : interferometric AB The Ryle telescope has been used at a frequency of 15 GHz, to detect a flux decrement in the direction of the quasar pair PC 1643 +4631A, B. This signal was interpreted as the Sunyaev-Zeldovich effect (SZE) produced by a distant cluster of galaxies. In the course of an effort to measure cosmic microwave background (CMB) anisotropies with a deep pointing of the VLA at 8.4 GHz, a second group detected a similar, but smaller, decrement. They also proposed that this signal might be explained as the SZE signal produced by a distant galaxy cluster. We report observations with the Berkeley-Illinois-Maryland Association (BIMA) interferometer operating at 28.5 GHz, in which we find no evidence for a SZE signal in the direction of either of the proposed clusters. In the case of the Ryle detection, the BIMA data are inconsistent with the SZE model proposed to explain the observed decrement at greater than 99.99% confidence. Together with published X-ray and optical searches, these results make a compelling case against the interpretation of the Ryle decrement as being due to the SZE in a massive cluster of galaxies. For the smaller VLA source, the BIR IA observations are not as constraining. The BIMA data are inconsistent with the proposed SZE model at greater than 90% confidence. C1 Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. Univ Chicago, Dept Astron, Chicago, IL 60637 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Holzapfel, WL (reprint author), Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. RI Holzapfel, William/I-4836-2015 NR 18 TC 5 Z9 5 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2000 VL 539 IS 1 BP 67 EP 72 DI 10.1086/309210 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347RQ UT WOS:000088943300008 ER PT J AU Dolan, JF Michalitsianos, AG Nguyen, QT Hill, RJ AF Dolan, JF Michalitsianos, AG Nguyen, QT Hill, RJ TI Ultraviolet spectral variability and the Ly alpha forest in the lensed quasar Q0957+561 SO ASTROPHYSICAL JOURNAL LA English DT Article DE gravitational lensing; quasars : absorption lines; quasars : emission lines; quasars : individual (Q0957+561); ultraviolet : galaxies ID GRAVITATIONAL LENS; TIME-DELAY; CLOUDS; ABSORPTION; SIZE; REDSHIFT; SYSTEMS; MODEL; SPECTROSCOPY; ABSORBERS AB Far-ultraviolet spectra of the gravitational lens components Q0957+561A, B were obtained with the Hubble Space Telescope Faint Object Spectrograph (FOS) at five equally spaced epochs, one every 2 weeks. We confirm the flux variability of the quasar's Ly alpha and O VI lambda 1037 emission lines in IUE spectra reported in earlier work of Dolan et al. The fluxes in these lines vary on a timescale of weeks in the observer's rest frame, independently of each other and of the surrounding continuum. The individual spectra of each image were co-added to investigate the properties of the Ly alpha forest along the two lines of sight to the quasar. Absorption lines having equivalent width W-lambda greater than or equal to 0.3 Angstrom in the observer's frame not previously identified by Michalitsianos et al. as interstellar lines, metal lines, or higher order Lyman lines were taken to be Ly alpha forest lines. The existence of each line in this consistently selected set was then verified by its presence in two archival FOS spectra with similar to 1.5 times higher signal to noise than our co-added spectra. Ly alpha forest lines with W-lambda greater than or equal to 0.3 A appear at 41 distinct wavelengths in the spectra of the two images. One absorption line in the spectrum of image A has no counterpart in the spectrum of image B, and one line in image B has no counterpart in image A. Based on the separation of the lines of sight over the redshift range searched for Ly alpha forest lines, the density of the absorbing clouds in the direction of Q0957 + 561 must change significantly over a distance R = 160(-70)(+120) h(50)(-1) kpc in the simplified model where the absorbers are treated as spherical clouds and the characteristic dimension, R, is the radius. (We adopt H-0 = 50 h(50) km s(-1) Mpc(-1), q(0) = 1/2, and Lambda = 0 throughout this paper.) The 95% confidence interval on R extends from 50 to 950 h(50)(-1) kpc. We show in the Appendix that the fraction of Lya forest lines that appear in only one spectrum can be expressed as a rapidly converging power series in 1/r, where r the ratio of the radius of the cloud to the separation of the two lines of sight at the redshift of the cloud. This power series can be rewritten to give r in terms of the fraction of Ly alpha forest wavelengths that appear in the spectrum of only one image. A simple linear approximation to the solution that everywhere agrees with the power series solution to better than 0.8% for r greater than or equal to 2 is derived in the Appendix. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. San Diego State Univ, Dept Astron, San Diego, CA 92182 USA. RP Dolan, JF (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. NR 34 TC 6 Z9 6 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2000 VL 539 IS 1 BP 111 EP 123 DI 10.1086/309206 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347RQ UT WOS:000088943300013 ER PT J AU Terashima, Y Ho, LC Ptak, AF AF Terashima, Y Ho, LC Ptak, AF TI Hard X-ray emission and the ionizing source in liners SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : nuclei; galaxies : Seyfert; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; DWARF SEYFERT NUCLEI; EARLY-TYPE GALAXIES; ASCA OBSERVATION; SPIRAL GALAXIES; NGC-1097; OBSCURATION; NGC-4736; SPECTRA; SEARCH AB We report X-ray fluxes in the 2-10 keV band from LINERs (low-ionization nuclear emission-line regions) and low-luminosity Seyfert galaxies obtained with the ASCA satellite. Observed X-ray luminosities are in the range between 4 x 10(39) and 5 x 10(41) ergs s(-1), which are significantly smaller than that of the "classical" low-luminosity Seyfert 1 galaxy NGC 4051. We found that X-ray luminosities in 2-10 keV of LINERs with broad H alpha emission in their optical spectra (LINER Is) are proportional to their H alpha luminosities. This correlation strongly supports the hypothesis that the dominant ionizing source in LINER Is is photoionization by hard photons from low-luminosity active galactic nuclei (AGNs). On the other hand, the X-ray luminosities of most LINERs without broad H alpha emission (LINER 2s) in our sample are lower than LINER is at a given H alpha luminosity. The observed X-ray luminosities in these objects are insufficient to power their H alpha luminosities, suggesting that their primary ionizing source is other than an AGN, or that an AGN, if present, is obscured even at energies above 2 keV. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Carnegie Inst Washington Observ, Pasadena, CA 91101 USA. Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. RP Terashima, Y (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 56 TC 68 Z9 68 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2000 VL 539 IS 1 BP 161 EP 165 DI 10.1086/309234 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347RQ UT WOS:000088943300018 ER PT J AU Yokogawa, J Paul, B Ozaki, M Nagase, F Chakrabarty, D Takeshima, T AF Yokogawa, J Paul, B Ozaki, M Nagase, F Chakrabarty, D Takeshima, T TI ASCA observation of the new transient X-ray pulsar XTE J0111.2-7317 in the small magellanic cloud SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : general; Magellanic Clouds; pulsars : individual (XTE J0111.2-; 7317); X-rays : stars ID IMAGING SPECTROMETER; ROSAT OBSERVATIONS; CENTAURUS X-3; BOARD ASCA; SPIN-DOWN; VELA X-1; SMC X-1; PHASE; GINGA; SPECTROSCOPY AB The new transient X-ray pulsar XTE J0111.2-7317 was observed with Advanced Satellite for Cosmology and Astrophysics (ASCA) on 1998 November 18, a few days after its discovery with the proportional counter array on board the Rossi X-ray Timing Explorer. The source was detected at a flux level of 3.6 x 10(-10) ergs cm(-2) s(-1) in the 0.7-10.0 keV band, which corresponds to the X-ray luminosity of 1.8 x 10(38) ergs s(-1), if a distance of 65 kpc for this pulsar in the Small Magellanic Cloud is assumed. Nearly sinusoidal pulsations with a period of 30.9497 +/- 0.0004 s were unambiguously detected during the ASCA observation. The pulsed fraction is low and slightly energy dependent with an average value of similar to 27%. The energy spectrum shows a large soft excess below similar to 2 keV when fitted to a simple power-law-type model. The soft excess is eliminated if the spectrum is fitted to an "inversely broken power-law" model, in which photon indices below and above a break energy of 1.5 keV are 2.3 and 0.8, respectively. The soft excess can also be described by a blackbody or a thermal bremsstrahlung when the spectrum above similar to 2 keV is modeled by a power law. In these models, however, the thermal soft component requires a very large emission zone, and hence it is difficult to explain the observed pulsations at energies below 2 keV. A bright state of the source enables us to identify a weak iron line feature at 6.4 keV with an equivalent width of 50 +/- 14 eV. Pulse phase-resolved spectroscopy revealed a slight hardening of the spectrum and marginal indication of an increase in the iron line strength during the pulse maximum. C1 Kyoto Univ, Grad Sch Sci, Dept Phys, Sakyo Ku, Kyoto 6068502, Japan. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. MIT, Dept Phys, Cambridge, MA 02139 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Seabrook, MD 20706 USA. RP Yokogawa, J (reprint author), Kyoto Univ, Grad Sch Sci, Dept Phys, Sakyo Ku, Kyoto 6068502, Japan. RI Astronomy & Astrophysics Group, Raman Res Institute/D-4046-2012; Ozaki, Masanobu/K-1165-2013; Paul, Biswajit/D-4807-2012 NR 37 TC 23 Z9 23 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2000 VL 539 IS 1 BP 191 EP 196 DI 10.1086/309202 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347RQ UT WOS:000088943300022 ER PT J AU LeBohec, S Bond, IH Bradbury, SM Buckley, JH Burdett, AM Carter-Lewis, DA Catanese, M Cawley, MF Dunlea, S D'Vali, M Fegan, DJ Fegan, SJ Finley, JP Gaidos, JA Hall, TA Hillas, AM Horan, D Knapp, J Krennrich, F Lessard, RW Macomb, D Masterson, C Quinn, J Rose, HJ Samuelson, FW Sembroski, GH Vassiliev, VV Weekes, TC AF LeBohec, S Bond, IH Bradbury, SM Buckley, JH Burdett, AM Carter-Lewis, DA Catanese, M Cawley, MF Dunlea, S D'Vali, M Fegan, DJ Fegan, SJ Finley, JP Gaidos, JA Hall, TA Hillas, AM Horan, D Knapp, J Krennrich, F Lessard, RW Macomb, D Masterson, C Quinn, J Rose, HJ Samuelson, FW Sembroski, GH Vassiliev, VV Weekes, TC TI Gamma-ray observations of the galactic plane at energies E > 500 GeV SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic rays; diffuse radiation; gamma rays : observations ID SATELLITE; TELESCOPE; TEV AB In 1998 and 1999 the Whipple Observatory 10 m telescope was used to search for diffuse gamma-ray emission from the Galactic plane. At this time, the telescope was equipped with a large (4"8) held of view camera, well suited to detect diffuse gamma-ray emission. No significant evidence of emission was found. Assuming the TeV emission profile matches EGRET observations above 1 GeV with a differential spectral index of 2.4, we derive an upper limit of 3.0 x 10(-8) cm(-2) s(-1) sr(-1) for the average diffuse emission above 500 GeV in the Galactic latitude range from -2 degrees to +2 degrees at Galactic longitude 40 degrees. Comparisons with EGRET observations provide a lower limit of 2.31 for the differential spectral index of the diffuse emission, assuming there is no break in the spectrum between 30 and 500 GeV. This constrains models for diffuse emission with a significant inverse Compton contribution. C1 Iowa State Univ, Dept Phys & Astron, Ames, IA 50011 USA. Univ Leeds, Dept Phys, Leeds LS2 9JT, W Yorkshire, England. Washington Univ, Dept Phys, St Louis, MO 63130 USA. Harvard Smithsonian Ctr Astrophys, Fred Lawrence Whipple Observ, Amado, AZ 85645 USA. St Patricks Coll, Dept Phys, Maynooth, Kildare, Ireland. Univ Coll Dublin, Dept Phys, Dublin 4, Ireland. Purdue Univ, Dept Phys, W Lafayette, IN 47907 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Lanham, MD USA. RP LeBohec, S (reprint author), Iowa State Univ, Dept Phys & Astron, Ames, IA 50011 USA. OI Knapp, Johannes/0000-0003-1519-1383 NR 25 TC 41 Z9 42 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2000 VL 539 IS 1 BP 209 EP 215 DI 10.1086/309227 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347RQ UT WOS:000088943300024 ER PT J AU Richling, S Yorke, HW AF Richling, S Yorke, HW TI Photoevaporation of protostellar disks. V. Circumstellar disks under the influence of both extreme-ultraviolet and far-ultraviolet radiation SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; hydrodynamics; HII regions; line : formation; radiative transfer; stars : formation ID ORION NEBULA; PHOTODISSOCIATION REGIONS; GRAINS; STARS; FLUX; APPEARANCE; DIFFUSION; TRAPEZIUM; ENVELOPES; PROPLYDS AB The evolution and appearance of protostellar disks can be significantly altered by their UV environment. We investigate numerically the photoevaporation of protostellar disks under the influence of an external radiation held with both EUV (hv > 13.6 eV) and FUV (6 eV < hv < 13.6 eV) components. Our two-dimensional axisymmetric radiation hydrodynamics calculations begin with star-disk configurations resulting from previously published collapse simulations. We follow the evolution after the external UV radiation source has been turned on. We consider the transfer of both direct (from the UV point source) as well as diffuse radiation fields simultaneously with the ionization of hydrogen and carbon. A simplified cooling function is employed which assumes that the carbon ionization front separates the molecular region from the region in atomic or ionized form. For some simulations an isotropic stellar wind has been included at the position of the disk's central star. At selected evolutionary times a frequency-dependent ray-tracing diagnostic code is used to calculate emission line spectra and emission line maps over the volume of interest. The interaction of the FUV-induced neutral how at the disk surface with the direct and diffuse EUV radiation fields leads to the typical head-tail objects with bright emission line crescents and tails pointing away from the external radiation source. The properties of the head-tail objects are in agreement with the properties of the proplyds in the Orion Nebula, M8, NGC 2024, and-in a more extreme UV environment-of the newly discovered proplyds in NGC 3603. After losing material via photoevaporation over a time,greater than or similar to 10(5) yr, our initially rather massive disks are reduced to typical observed disk masses. At this time the radius of the disk, the radius of the hydrogen ionization front, and the length of the tail are compatible to observed proplyds. Our model disks can be either silhouetted or nonsilhouetted in the emission line maps, depending on orientation. The [O III] 5007 Angstrom emission appears more diffuse than [O II] 3726 Angstrom, because the abundance of O III is low near the hydrogen ionization front and in the shadow regions along the tail. Monopolar and bipolar microjets emerging from the proplyds can be explained by spherically symmetric stellar winds hydrodynamically focused by the neutral evaporating flow from the disk surface. C1 Inst Theoret Astrophys, D-69121 Heidelberg, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Richling, S (reprint author), Inst Theoret Astrophys, Tiergartenstr 15, D-69121 Heidelberg, Germany. NR 47 TC 77 Z9 77 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2000 VL 539 IS 1 BP 258 EP 272 DI 10.1086/309198 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347RQ UT WOS:000088943300029 ER PT J AU Scott, DM Leahy, DA Wilson, RB AF Scott, DM Leahy, DA Wilson, RB TI The 35 day evolution of the Hercules X-1 pulse profile: Evidence for a resolved inner disk occultation of the neutron star SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : individual (Hercules X-1); X-rays : stars ID X-RAY PULSARS; HZ HERCULIS/HERCULES X-1; LONG-TERM VARIABILITY; ACCRETION DISK; PHASE SPECTROSCOPY; OPTICAL PULSATIONS; 35-DAY CYCLE; BEHAVIOR; SHAPE; UHURU AB Ginga and Rossi X-Ray Timing Explorer observations have allowed an unprecedented view of the recurrent systematic pulse shape changes associated with the 35 day cycle of Hercules X-l, a phenomenon currently unique among the known accretion-powered pulsars. We present observations of the pulse shape evolution. An explanation for the pulse evolution in terms of a freely precessing neutron star is reviewed and shown to have several major difficulties in explaining the observed pulse evolution pattern. Instead, we propose a phenomenological model for the pulse evolution based on an occultation of the pulse-emitting region by the tilted, inner edge of a precessing accretion disk. The systematic and repeating pulse shape changes require a resolved occultation of the pulse emission region. The observed pulse profile motivates the need for a pulsar beam consisting of a composite coaxial pencil and fan beam, but the observed evolution pattern requires the fan beam to be focused around the neutron star and beamed in the antipodal direction. The spectral hardness of the pencil beam component suggests an origin at the magnetic polar cap, with the relatively softer fan beam emission produced by backscattering from within the accretion column, qualitatively consistent with several theoretical models for X-ray emission from the accretion column of an accreting neutron star. C1 Univ Space Res Assoc, Columbia, MD 21044 USA. NASA, Marshall Space Flight Ctr, Space Sci Directorate, Huntsville, AL 35812 USA. Univ Calgary, Dept Phys, Calgary, AB T2N 1N4, Canada. RP Scott, DM (reprint author), Univ Space Res Assoc, Columbia, MD 21044 USA. NR 69 TC 58 Z9 59 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2000 VL 539 IS 1 BP 392 EP 412 DI 10.1086/309203 PN 1 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347RQ UT WOS:000088943300042 ER PT J AU Kotani, T Ebisawa, K Dotani, T Inoue, H Nagase, F Tanaka, Y Ueda, Y AF Kotani, T Ebisawa, K Dotani, T Inoue, H Nagase, F Tanaka, Y Ueda, Y TI ASCA observations of the absorption line features from the superluminal jet source GRS 1915+105 SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : dose; stars : individual (GRS 1915+105); X-rays : stars ID GAS IMAGING SPECTROMETER; HELIUM-LIKE IONS; BOARD ASCA AB We have carried out a precise energy spectral analysis of the superluminal jet source GRS 1915+/-105 observed with ASCA six times from 1994 to 1999. The source was SO bright that most SIS data suffered from event pileup. We have developed a new technique to circumvent the pileup effect, which enabled us to study the spectrum in detail and at high resolution (Delta E/E approximate to 2%). In the energy spectra of 1994 and 1995, resonant absorption lines of Ca XX K alpha, Fe XXV K alpha, Fe XXVI K alpha, as well as blends of the absorption lines of Ni XXVII K alpha + Fe XXV K beta and Ni XXVIII K alpha + Fe XXVI K beta, were observed. Such absorption lines have not been found in other objects, except for iron absorption lines from GRO J1655-40, another superluminal jet source. We carried out a "curve of growth" analysis for the absorption lines and estimated column densities of the absorbing ions. We found that a plasma of moderate temperature (0.1-10 keV) and cosmic abundance cannot account for the observed large equivalent widths. The hydrogen column density of such plasma would be so high that the optical depth of Thomson scattering would be too thick (N(H) greater than or similar to 10(24) cm(-2)). We require either a very high kinetic temperature of the ions (greater than or similar to 100 keV) or extreme overabundances (greater than or similar to 100 Z.). In the former case, the ion column densities have reasonable values of 10(17)-10(18) cm(-2). We modeled the absorber as a photoionized disk which envelops the central X-ray source. Using a photoionization calculation code, we constrain physical parameters of the plasma disk, such as the ionization parameter, radius, and density. Estimated parameters were found to be consistent with those of a radiation-driven disk wind. These absorption line features may be peculiar to superluminal jet sources and related to the jet formation mechanism. Alternatively, they may be common characteristics of supercritical edge-on systems. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. ISAS, Kanagawa 2298510, Japan. Max Planck Inst Extraterr Phys, Garching, Germany. RP Kotani, T (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NR 28 TC 103 Z9 103 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 AUG 10 PY 2000 VL 539 IS 1 BP 413 EP 423 DI 10.1086/309200 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347RQ UT WOS:000088943300043 ER PT J AU Heap, SR Lindler, DJ Lanz, TM Cornett, RH Hubeny, I Maran, SP Woodgate, B AF Heap, SR Lindler, DJ Lanz, TM Cornett, RH Hubeny, I Maran, SP Woodgate, B TI Space telescope imaging spectrograph coronagraphic observations of beta Pictoris SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; circumstellar matter; planetary systems; stars : imaging; stars : individual (beta Pictoris) ID CIRCUMSTELLAR DISK; DUST DISK; SYSTEM; IMAGES AB We present new coronagraphic images of beta Pictoris obtained with the Space Telescope Imaging Spectrograph (STIS) in 1997 September. The high-resolution images (0 ".1) clearly detect the circumstellar disk as close to the star as 0 ".75, corresponding to a projected radius of 15 AU. The images define the warp in the disk with greater precision and at closer radii to beta Pic than do previous observations. They show that the warp can be modeled by the projection of two components: the main disk and a fainter component, which is inclined to the main component by 4 degrees-5 degrees and extends only as far as approximate to 4 " from the star. We interpret the main component as arising primarily in the outer disk and the tilted component as defining the inner region of the disk. The observed properties of the warped inner disk are inconsistent with a driving force from stellar radiation. However, warping induced by the gravitational potential of one or more planets is consistent with the data. Using models of planet-warped disks constructed by Larwood & Papaloizou, we derive possible masses of the perturbing object. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Space Sci Directorate, Greenbelt, MD 20771 USA. RP Heap, SR (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. NR 20 TC 166 Z9 166 U1 2 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2000 VL 539 IS 1 BP 435 EP 444 DI 10.1086/309188 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347RQ UT WOS:000088943300045 ER PT J AU Hynes, RI Mauche, CW Haswell, CA Shrader, CR Cui, W Chaty, S AF Hynes, RI Mauche, CW Haswell, CA Shrader, CR Cui, W Chaty, S TI The X-ray transient XTE J1118+480: Multiwavelength observations of a low-state minioutburst SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : close; stars : individual (XTE J1118+480); ultraviolet : stars; X-rays : stars ID EXTREME-ULTRAVIOLET; ABSORPTION AB We present multiwavelength observations of the newly discovered X-ray transient XTE J1118+480 obtained in the rising phase of the 2000 April outburst. This source is located at unusually high Galactic latitude and in a very low absorption line of sight. This made the first Extreme Ultraviolet Explorer (EUVE) spectroscopy of an X-ray transient outburst possible, Together with our Hubble Space Telescope, Rossi X-Ray Timing Explorer, and United Kingdom Infrared Telescope data, this gives unprecedented spectral coverage. We find the source in the low hard state. The flat IR-UV continuum appears to be a combination of optically thick disk emission and possibly synchrotron, while at higher energies (including; EUV), a typical low hard state power law is seen. EUVE observations reveal no periodic modulation, suggesting an inclination low enough that no obscuration by the disk rim occurs. We discuss the nature of the source and this outburst and conclude that it may be more akin to minioutbursts seen in GRO J0422+32 than to a normal X-ray transient outburst. C1 Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. Open Univ, Dept Phys & Astron, Milton Keynes MK7 6AA, Bucks, England. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. MIT, Space Res Ctr, Cambridge, MA 02139 USA. RP Hynes, RI (reprint author), Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. NR 31 TC 99 Z9 99 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2000 VL 539 IS 1 BP L37 EP L40 DI 10.1086/312836 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 347RU UT WOS:000088943600010 ER PT J AU Devi, VM Benner, DC Smith, MAH Rinsland, CP Brown, LR AF Devi, VM Benner, DC Smith, MAH Rinsland, CP Brown, LR TI Measurements of air broadening, pressure shifting and off diagonal relaxation matrix coefficients in the nu(3) band of (CH3D)-C-12 (vol 517, pg 455, 2000) SO JOURNAL OF MOLECULAR STRUCTURE LA English DT Correction C1 Coll William & Mary, Dept Phys, Williamsburg, VA 23187 USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Devi, VM (reprint author), Coll William & Mary, Dept Phys, Box 8795, Williamsburg, VA 23187 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-2860 J9 J MOL STRUCT JI J. Mol. Struct. PD AUG 10 PY 2000 VL 526 BP 401 EP 401 DI 10.1016/S0022-2860(00)00692-X PG 1 WC Chemistry, Physical SC Chemistry GA 343BV UT WOS:000088682600041 ER PT J AU Vander Wal, RL Ticich, TM Curtis, VE AF Vander Wal, RL Ticich, TM Curtis, VE TI Flame synthesis of metal-catalyzed single-wall carbon nanotubes SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID ETHYLENE FLAMES; LARGE-SCALE; GROWTH; SOOT; HYDROCARBONS; PARTICLES; HYDROGEN; COMBUSTION; PYROLYSIS; MIXTURES AB In the work presented here, flame conditions are tailored to create a synergy between various metallic additives (cobaltocene, nickelocene, cobalt acetylacetonate, and ferrocene) and the flame environment to synthesize the desirable product of single-wall carbon nanotubes. The flame conditions for synthesis of the nanotubes is explored by using C2H2, C2H4 and CO in combination with H-2, CH4 or air along with an inert carrier (He, Nz or Ar) over a range of concentrations. Possible mechanisms for the encapsulation of the particles within a carbonaceous matrix are considered. C1 NASA Glenn, NCMR, Cleveland, OH 44135 USA. Centenary Coll Louisiana, Dept Chem, Shreveport, LA 71134 USA. RP Vander Wal, RL (reprint author), NASA Glenn, NCMR, MS 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 38 TC 29 Z9 30 U1 2 U2 13 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 AUG 10 PY 2000 VL 104 IS 31 BP 7209 EP 7217 DI 10.1021/jp994304n PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 343CF UT WOS:000088683600008 ER PT J AU Li, X Mintz, EA Bu, XR Zehnder, O Bosshard, C Gunter, P AF Li, X Mintz, EA Bu, XR Zehnder, O Bosshard, C Gunter, P TI Phase transfer catalysis for tandem alkylation of azo dyes for the synthesis of novel multifunctional molecules SO TETRAHEDRON LA English DT Article DE phase transfer; alkylation; azo compounds; polycyclic heterocyclic compounds ID PHOTOREFRACTIVE POLYMERS; SIDE-CHAIN AB Potentially photorefractive molecules, which possess both a charge transfer component and a nonlinear optical chromophore, were prepared by the direct N-monoalkylation of Disperse Orange 3 (1) with a carbazole alkyl bromide (2) utilizing phase transfer catalysis. Further N-alkylation of the remaining active N-H with alkyl halides with various chain lengths allowed the thermal properties of the Disperse Orange 3 derivatives to be fine-tuned. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Clark Atlanta Univ, Dept Chem, Atlanta, GA 30314 USA. Clark Atlanta Univ, NASA, Ctr High Performance Polymers & Composites, Atlanta, GA 30314 USA. ETH Zurich, Inst Quantum Elect, Nonlinear Opt Lab, CH-8093 Zurich, Switzerland. RP Bu, XR (reprint author), Clark Atlanta Univ, Dept Chem, Atlanta, GA 30314 USA. NR 20 TC 18 Z9 18 U1 2 U2 13 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 AUG 4 PY 2000 VL 56 IS 32 BP 5785 EP 5791 DI 10.1016/S0040-4020(00)00536-6 PG 7 WC Chemistry, Organic SC Chemistry GA 341DD UT WOS:000088575000004 ER PT J AU Goldstein, ME Leib, SJ AF Goldstein, ME Leib, SJ TI Emission of sound from turbulence convected by a parallel mean flow in the presence of a confining duct SO JOURNAL OF SOUND AND VIBRATION LA English DT Article ID NOISE AB An approximate method for calculating the noise generated by a turbulent flow within a semi-infinite duct of arbitrary cross-section is developed. It is based on a previously derived high-frequency solution to Lilley's equation, which describes the sound propagation in a transversely sheared mean flow. The source term is simplified by assuming the turbulence to be axisymmetric about the mean flow direction. Numerical results are presented for the special case of a ring source in a circular duct with an axisymmetric mean how. They show that the internally generated noise is suppressed at sufficiently large upstream angles in a hard-walled duct, and that acoustic liners can significantly reduce the sound radiated in both the upstream and downstream regions, depending upon the source location and Mach number of the flow. (C) 2000 Academic Press. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Brook Pk, OH 44142 USA. RP Goldstein, ME (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 19 TC 5 Z9 5 U1 0 U2 0 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD AUG 3 PY 2000 VL 235 IS 1 BP 25 EP 42 DI 10.1006/jsvi.1999.2912 PG 18 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 343NY UT WOS:000088709500002 ER PT J AU Bellamy, HD Snell, EH Lovelace, J Pokross, M Borgstahl, GEO AF Bellamy, HD Snell, EH Lovelace, J Pokross, M Borgstahl, GEO TI The high-mosaicity illusion: revealing the true physical characteristics of macromolecular crystals SO ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY LA English DT Article ID PROTEIN CRYSTALS; DIFFRACTION DATA; MICROGRAVITY; PERFECTION; ALGORITHM AB Typical measurements of macromolecular crystal mosaicity are dominated by the characteristics of the X-ray beam and as a result the mosaicity value given during data processing can be an artifact of the instrumentation rather than the sample. For physical characterization of crystals, an experimental system and software have been developed to simultaneously measure the diffraction resolution and mosaic spread of macromolecular crystals. The contributions of the X-ray beam to the reflection angular widths were minimized by using a highly parallel, highly monochromatic synchrotron source. Hundreds of reflection profiles over a wide resolution range were rapidly measured using a charge-coupled device (CCD) area detector in combination with superfine phi-slicing data collection. The Lorentz effect and beam contributions were evaluated and deconvoluted from the recorded data. Data collection and processing is described. From 1 degrees of superfine phi-slice data collected on a crystal of manganese superoxide dismutase, the mosaicities of 260 reflections were measured. The average mosaicity was 0.0101 degrees (s.d. 0.0035 degrees) measured as the full-width at half-maximum (FWHM) and ranged from 0.0011 to 0.0188 degrees. Each reflection profile was individually fitted with two Gaussian profiles, with the first Gaussian contributing 55% (s.d. 9%) and the second contributing 35% (s.d. 9%) of the reflection. On average, the deconvoluted width of the first Gaussian was 0.0054 degrees (s.d. 0.0015 degrees) and the second was 0.0061 degrees (s.d. 0.0023 degrees). The mosaicity of the crystal was anisotropic, with FWHM values of 0.0068, 0.0140 and 0.0046 degrees along the a, b and c axes, respectively. The anisotropic mosaicity analysis indicates that the crystal is most perfect in the direction that corresponds to the favored growth direction of the crystal. C1 Univ Toledo, Dept Chem, Toledo, OH 43606 USA. Stanford Synchrotron Radiat Lab, Stanford, CA 94309 USA. NASA, Struct Biol Lab, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Borgstahl, GEO (reprint author), Univ Toledo, Dept Chem, 2801 W Bancroft St, Toledo, OH 43606 USA. NR 25 TC 34 Z9 35 U1 2 U2 6 PU MUNKSGAARD INT PUBL LTD 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 AUG PY 2000 VL 56 BP 986 EP 995 DI 10.1107/S0907444900007356 PN 8 PG 10 WC Biochemical Research Methods; Biochemistry & Molecular Biology; Biophysics; Crystallography SC Biochemistry & Molecular Biology; Biophysics; Crystallography GA 337WD UT WOS:000088384200007 PM 10944335 ER PT J AU Storaasli, OO AF Storaasli, OO TI Special issue on large-scale analysis, design and intelligent synthesis environments - Preface SO ADVANCES IN ENGINEERING SOFTWARE LA English DT Editorial Material C1 NASA, Langley Res Ctr, Analyt & Computat Methods Branch, Hampton, VA 23681 USA. RP Storaasli, OO (reprint author), NASA, Langley Res Ctr, Analyt & Computat Methods Branch, Mail Stop 240, Hampton, VA 23681 USA. NR 0 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 0965-9978 J9 ADV ENG SOFTW JI Adv. Eng. Softw. PD AUG-SEP PY 2000 VL 31 IS 8-9 BP 499 EP 499 DI 10.1016/S0965-9978(00)00074-0 PG 1 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Engineering, Multidisciplinary SC Computer Science; Engineering GA 346MR UT WOS:000088876100001 ER PT J AU Watson, WR Storaasli, OO AF Watson, WR Storaasli, OO TI Application of NASA general-purpose solver to large-scale computations in aeroacoustics SO ADVANCES IN ENGINEERING SOFTWARE LA English DT Article; Proceedings Paper CT 5th NASA National Symposium on Large-Scale Analysis, Design and Intelligent Synthesis Environments CY OCT 12-15, 1999 CL WILLIAMSBURG, VIRGINIA SP NASA DE finite element; vector-sparse solver; general-purpose solver; impedance eduction; symmetric matrices; solver statistics; large-scale computations; aeroacoustics; SGI ORIGIN 2000 AB Of several iterative and direct equation solvers evaluated previously for computations in aeroacoustics, the most promising was the NASA-developed general-purpose solver (winner of NASA's 1999 software of the year award). This paper presents detailed, single-processor statistics of the performance of this solver, which has been tailored and optimized for large-scale aeroacoustic computations. The statistics compiled using an SGI ORIGIN 2000 computer with 12 Gb available memory (RAM) and eight available processors, are the central processing unit time, RAM requirements, and solution error. The equation solver is capable of solving 10 thousand complex unknowns in as little as 0.01 s using 0.02 Gb RAM, and 8.4 million complex unknowns in slightly less than 3 h using all 12 Gb. This latter solution Is the largest aeroacoustics problem solved to date with this technique. The study was unable to detect any noticeable error in the solution, since noise levels predicted from these solution vectors are in excellent agreement with the noise levels computed from the exact solution. The equation solver provides a means for obtaining numerical solutions to aeroacoustics problems in three dimensions. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 10 TC 0 Z9 1 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0965-9978 J9 ADV ENG SOFTW JI Adv. Eng. Softw. PD AUG-SEP PY 2000 VL 31 IS 8-9 BP 555 EP 561 DI 10.1016/S0965-9978(00)00015-6 PG 7 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Engineering, Multidisciplinary SC Computer Science; Engineering GA 346MR UT WOS:000088876100008 ER PT J AU Nguyen, DT Bunting, CF Moeller, KJ Runesha, H Qin, J AF Nguyen, DT Bunting, CF Moeller, KJ Runesha, H Qin, J TI Subspace and Lanczos sparse eigen-solvers for finite element structural and electromagnetic applications SO ADVANCES IN ENGINEERING SOFTWARE LA English DT Article; Proceedings Paper CT 5th NASA National Symposium on Large-Scale Analysis, Design and Intelligent Synthesis Environments CY OCT 12-15, 1999 CL WILLIAMSBURG, VIRGINIA SP NASA DE subspace and Lanczos sparse eigen-solvers; exxon-off-shore structure; high speed civil transport aircraft AB Recent developments in vectorized sparse technologies are incorporated into the Subspace and Lanczos iteration algorithms for computational enhancements. Numerical evaluations of the proposed sparse strategies for Subspace and Lanczos iteration algorithms are conducted by solving the generalized eigen-value problem associated with the Exxon-off-shore structure, HSCT aircraft and a two-dimensional reverberation chamber for electromagnetic applications. Both real and complex numbers eigen-problems can be treated. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Old Dominion Univ, CEE Dept, Norfolk, VA 23508 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Nguyen, DT (reprint author), Old Dominion Univ, CEE Dept, 135 Kauf, Norfolk, VA 23508 USA. RI Bunting, Charles/B-9762-2013 OI Bunting, Charles/0000-0001-9167-4235 NR 11 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 0965-9978 J9 ADV ENG SOFTW JI Adv. Eng. Softw. PD AUG-SEP PY 2000 VL 31 IS 8-9 BP 599 EP 606 DI 10.1016/S0965-9978(00)00021-1 PG 8 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Engineering, Multidisciplinary SC Computer Science; Engineering GA 346MR UT WOS:000088876100014 ER PT J AU Guruswamy, GP AF Guruswamy, GP TI HiMAP: a portable super modular multilevel parallel multidisciplinary process for large scale analysis SO ADVANCES IN ENGINEERING SOFTWARE LA English DT Article; Proceedings Paper CT 5th NASA National Symposium on Large-Scale Analysis, Design and Intelligent Synthesis Environments CY OCT 12-15, 1999 CL WILLIAMSBURG, VIRGINIA SP NASA DE massively parallel processors; super modular process; Navier-Stokes equations; NASTRAN AB An efficient super modular process to simulate aeroelasticity of aerospace vehicles using high fidelity flow equations such as the Euler/Navier-Stokes equations is presented. The process is suitable for both tightly coupled and uncoupled analysis. The process is designed to execute on massively parallel processors (MPP) and work-station clusters based on a multiple-instruction, multiple-data (MIMD) architecture. The fluids discipline is parallelized using a zonal approach whereas the structures discipline is parallelized using the substructures concept. provision is also made to include controls domain. Computations of each discipline are spread across processors using IEEE standard message passing interface (MPI) for inter processor communications. Disciplines can run in parallel using a macro utility MPIRUN developed based on MPI. In addition to discipline parallelization and coarse-grain parallelization of the disciplines, embarrassingly parallel capability to run multiple parameter cases is implemented using a script system. The combined effect of three levels of parallelization is an almost linear scalability for multiple concurrent analyses that pet-form efficiently on MPP. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Guruswamy, GP (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 16 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 0965-9978 J9 ADV ENG SOFTW JI Adv. Eng. Softw. PD AUG-SEP PY 2000 VL 31 IS 8-9 BP 617 EP 620 DI 10.1016/S0965-9978(00)00030-2 PG 4 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Engineering, Multidisciplinary SC Computer Science; Engineering GA 346MR UT WOS:000088876100016 ER PT J AU Vatsa, VN AF Vatsa, VN TI Computation of sensitivity derivatives of Navier-Stokes equations using complex variables SO ADVANCES IN ENGINEERING SOFTWARE LA English DT Article; Proceedings Paper CT 5th NASA National Symposium on Large-Scale Analysis, Design and Intelligent Synthesis Environments CY OCT 12-15, 1999 CL WILLIAMSBURG, VIRGINIA SP NASA DE sensitivity derivatives; complex variables; Navier-Stokes; computational fluid dynamics ID UNSTRUCTURED GRIDS; DESIGN AB A method based on complex variables for obtaining sensitivity derivatives in conjuction with a Navier-Stokes flow code is described. The complex variable approach is found to be efficient and accurate and does not suffer from step-size related truncation errors. The resulting sensitivity derivatives are calibrated by comparisons with finite-difference solutions and experimental data for several aerodynamic configurations of practical interest. The methodology is straightforward and can be applied to an existing code with moderate effort. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Vatsa, VN (reprint author), NASA, Langley Res Ctr, Mail Stop 128, Hampton, VA 23681 USA. NR 12 TC 9 Z9 12 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0965-9978 J9 ADV ENG SOFTW JI Adv. Eng. Softw. PD AUG-SEP PY 2000 VL 31 IS 8-9 BP 655 EP 659 DI 10.1016/S0965-9978(00)00025-9 PG 5 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Engineering, Multidisciplinary SC Computer Science; Engineering GA 346MR UT WOS:000088876100020 ER PT J AU Bergman, R Baker, JD AF Bergman, R Baker, JD TI Enabling collaborative engineering and science at JPL SO ADVANCES IN ENGINEERING SOFTWARE LA English DT Article; Proceedings Paper CT 5th NASA National Symposium on Large-Scale Analysis, Design and Intelligent Synthesis Environments CY OCT 12-15, 1999 CL WILLIAMSBURG, VIRGINIA SP NASA DE collaboration; computer supported cooperative work; groupware; collaborative engineering; interoperability; virtual shared workspace; virtual conference AB We examine the issue of distributed collaboration at the Jet Propulsion Laboratory (JPL). With the goals of "faster, better, cheaper" missions, an efficient, seamless collaboration capability is critical to future JPL space exploration missions. We assert that the current capabilities for distributed collaboration internal to JPL, as well as external, are unsatisfactory. This paper provides a vision of greatly enhanced distributed collaboration capabilities in the near future and into the far future. Our vision focuses primarily on distributed collaborative engineering and science. We believe enhanced capabilities are necessary in two collaborative paradigms: the virtual conference and the shared virtual workspace. We describe these collaborative paradigms, and discuss the tools that exist and the additional capability necessary to achieve the collaborative vision with respect to the types of data we typically work with at JPL. We identify the following types of data frequently exchanged in collaborative activities: project planning data, design data, notes/documentation, communication data, analysis/performance data, verification data and scientific data. Our analysis shows that at present there is good GroupWare support for project planning data and notes/documentation data. Support is improving for design data. Other data types have no or sporadic support at best. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bergman, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 2 Z9 2 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0965-9978 J9 ADV ENG SOFTW JI Adv. Eng. Softw. PD AUG-SEP PY 2000 VL 31 IS 8-9 BP 661 EP 668 DI 10.1016/S0965-9978(00)00009-0 PG 8 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Engineering, Multidisciplinary SC Computer Science; Engineering GA 346MR UT WOS:000088876100021 ER PT J AU Gage, PJ Wright, MJ Prabhu, DK Papadopoulos, PE Olejniczak, J Olynick, D AF Gage, PJ Wright, MJ Prabhu, DK Papadopoulos, PE Olejniczak, J Olynick, D TI Preliminary design interfaces for high-fidelity engineering software: Web-based analyses for vehicle engineering SO ADVANCES IN ENGINEERING SOFTWARE LA English DT Article; Proceedings Paper CT 5th NASA National Symposium on Large-Scale Analysis, Design and Intelligent Synthesis Environments CY OCT 12-15, 1999 CL WILLIAMSBURG, VIRGINIA SP NASA DE automated integrated design; synthesis; computer-aided design; grid; computational fluid dynamics; atmospheric entry; spacecraft AB Web browser interfaces have been developed for geometry generation, volume grid generation, Computational fluid dynamics (CFD) solver execution and solution inspection. These interfaces access only a subset of the software's capability because they are tailored so that only the relevant choices are available for change. Scripts have been written to efficiently link the steps in CFD analysis and to facilitate repeated analysis. This environment is used successfully for CFD analysis of ballistic range models for atmospheric entry experiments. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, Themosci Inst, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Gage, PJ (reprint author), NASA, Ames Res Ctr, Themosci Inst, Moffett Field, CA 94035 USA. NR 14 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 0965-9978 J9 ADV ENG SOFTW JI Adv. Eng. Softw. PD AUG-SEP PY 2000 VL 31 IS 8-9 BP 697 EP 705 DI 10.1016/S0965-9978(00)00028-4 PG 9 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Engineering, Multidisciplinary SC Computer Science; Engineering GA 346MR UT WOS:000088876100025 ER PT J AU Filman, RE Korsmeyer, DJ Lee, DD AF Filman, RE Korsmeyer, DJ Lee, DD TI A CORBA extension for intelligent software environments SO ADVANCES IN ENGINEERING SOFTWARE LA English DT Article; Proceedings Paper CT 5th NASA National Symposium on Large-Scale Analysis, Design and Intelligent Synthesis Environments CY OCT 12-15, 1999 CL WILLIAMSBURG, VIRGINIA SP NASA DE object infrastructure framework; distributed computing; middleware; frameworks; CORBA; injectors; intelligent synthesis environment; ility; security; reliability; manageability; quality of service AB We describe the implementation of a technology that achieves system-wide properties in large software systems by controlling and modifying inter-component communications. Traditional component-based applications intermix the code for component functionality with support for systematic properties. This produces non-reusable components and inflexible systems. The Object Infrastructure Framework (OIF) separates systematic properties from functional code and provides a mechanism for weaving them together with functional components. This allows a much richer variety of component reuse and system evolution. Key elements of this technology include intercepting inter-component communications with discrete, dynamically configurable "injectors", annotating communications and processes with additional meta-information. and a high-level, declarative specification language for describing the mapping between desired system properties and services that achieve these properties. We have implemented these ideas in a CORBA/Java framework for distributed computing, and are currently applying them to a distributed system for the analysis of aerospace design (wind-tunnel and CFD) data. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, Caelum Res Corp, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Stanford, CA 94305 USA. RP Filman, RE (reprint author), NASA, Ames Res Ctr, Caelum Res Corp, MS 269-1, Stanford, CA 94305 USA. NR 15 TC 12 Z9 13 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0965-9978 J9 ADV ENG SOFTW JI Adv. Eng. Softw. PD AUG-SEP PY 2000 VL 31 IS 8-9 BP 727 EP 732 DI 10.1016/S0965-9978(00)00031-4 PG 6 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Engineering, Multidisciplinary SC Computer Science; Engineering GA 346MR UT WOS:000088876100029 ER PT J AU Szewczyk, ZP Sleight, DW AF Szewczyk, ZP Sleight, DW TI Object-oriented approach to interactive analysis of structures SO ADVANCES IN ENGINEERING SOFTWARE LA English DT Article; Proceedings Paper CT 5th NASA National Symposium on Large-Scale Analysis, Design and Intelligent Synthesis Environments CY OCT 12-15, 1999 CL WILLIAMSBURG, VIRGINIA SP NASA DE object-oriented modeling and analysis; virtual phototyping; neural networks ID NETWORKS AB The paper presents a novel, object-oriented (O-O) approach to structural modeling and analysis to enable interactive, virtual prototyping in the next generation of the design environment. The interactivity of analysis of build-up structures can only be achieved by re-using results of component analyses, therefore, the applicability of data based analysis to the O-O approach is investigated in this paper. An object in the O-O approach is a neurocomputing model of a structural component developed for a given set of parameterized design variables, loading, and "smart" connectors. Such connectors define how the given component is connected to the assembly, and what is the validity of such a connection. Since component models can be subject to affine transformations, a family of similar structural components is available for modeling. Neurocomputing models are used to enable data based analysis, because they can relate any design variables and load conditions to the selected system response. The applicability of feed-forward and feature-sensitive neural nets is examined in this context. Object-oriented modeling is illustrated with a design of an assembly of beams using a single-point (SP) connector and an assembly of plates subject to a thermal load using a multi-point (MP) connector. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Szewczyk, ZP (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 11 TC 3 Z9 3 U1 0 U2 3 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0965-9978 J9 ADV ENG SOFTW JI Adv. Eng. Softw. PD AUG-SEP PY 2000 VL 31 IS 8-9 BP 733 EP 742 DI 10.1016/S0965-9978(00)00076-4 PG 10 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Engineering, Multidisciplinary SC Computer Science; Engineering GA 346MR UT WOS:000088876100030 ER PT J AU Powell, CA Preisser, JS AF Powell, CA Preisser, JS TI NASA subsonic jet transport noise reduction research SO AERONAUTICAL JOURNAL LA English DT Article; Proceedings Paper CT Biennial Congress of the International-Council-of-the-Aeronautical-Sciences CY AUG 28-SEP 01, 2000 CL HARROGATE, ENGLAND SP Int Council Aeronaut Sci AB Although new jet transport aircraft in today's fleet are considerably quieter than the first jet transports introduced about 40 years ago, airport community noise continues to be an important environmental issue. NASA's Advanced Subsonic Transport (AST) Noise Reduction programme was begun in 1994 as a seven-year effort to develop technology to reduce jet transport noise 10dB relative to -1992 technology. This programme provides for reductions in engine source noise, improvements in nacelle acoustic treatments, reductions in the noise generated by the airframe, and improvements in the way aircraft are operated in the airport environs. These noise reduction efforts will terminate at the end of 2001 and it appears that the objective will be met. However, because of an anticipated 3-8% growth in passenger and cargo operations well into the 21st century and the slow introduction of the new noise reduction technology into the fleet, world aircraft noise impact will remain essentially constant until about 2020 to 2030 and thereafter begin to rise. Therefore, NASA has begun planning with the FAA, industry, universities and environmental interest groups in the USA for a new noise reduction initiative to provide technology for significant further reductions. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Powell, CA (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 5 TC 2 Z9 2 U1 1 U2 1 PU ROYAL AERONAUTICAL SOC PI LONDON PA 4 HAMILTON PL, LONDON W1V OBQ, ENGLAND SN 0001-9240 J9 AERONAUT J JI Aeronaut. J. PD AUG PY 2000 VL 104 IS 1038 BP 353 EP 358 PG 6 WC Engineering, Aerospace SC Engineering GA 375AH UT WOS:000165377000004 ER PT J AU Kumar, A Hefner, JN AF Kumar, A Hefner, JN TI Future challenges and opportunities in aerodynamics SO AERONAUTICAL JOURNAL LA English DT Article; Proceedings Paper CT Biennial Congress of the International-Council-of-the-Aeronautical-Sciences CY AUG 28-SEP 01, 2000 CL HARROGATE, ENGLAND SP Int Council Aeronaut Sci ID FLOW-CONTROL AB Investments in aeronautics research and technology have declined substantially over the last decade, in part due to the perception that technologies required in aircraft design are fairly mature and readily available. This perception is being driven by the fact that aircraft configurations, particularly the transport aircraft, have evolved only incrementally over the last several decades. Lf,however, one considers that the growth in air travel is expected to triple in the next 20 years, it becomes quickly obvious that the evolutionary development of technologies is not going to meet the increased demands for safety, environmental compatibility, capacity, and economic viability. Instead, breakthrough technologies will be required both in traditional disciplines of aerodynamics, propulsion. structures, materials, controls and avionics as well as in the multidisciplinary integration of these technologies into the design of future aerospace vehicles concepts. The paper discusses challenges and opportunities in the field of aerodynamics over the next decade. Future technology advancements in aerodynamics will hinge on our ability to understand, model and control complex, three-dimensional, unsteady Viscous flow across the speed range. This understanding is critical for developing innovative flow and noise control technologies and advanced design tools that will revolutionise future aerospace vehicle systems and concepts. Specifically, the paper focuses on advanced vehicle concepts, flow and noise control technologies, and advanced design and analysis tools. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Kumar, A (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 54 TC 3 Z9 3 U1 0 U2 2 PU ROYAL AERONAUTICAL SOC PI LONDON PA 4 HAMILTON PL, LONDON W1V OBQ, ENGLAND SN 0001-9240 J9 AERONAUT J JI Aeronaut. J. PD AUG PY 2000 VL 104 IS 1038 BP 365 EP 373 PG 9 WC Engineering, Aerospace SC Engineering GA 375AH UT WOS:000165377000006 ER PT J AU Paynter, GC Clark, LT Cole, GL AF Paynter, GC Clark, LT Cole, GL TI Modeling the response from a cascade to an upstream acoustic disturbance SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA 36th Aerospace Sciences Meeting CY JAN 12-15, 1998 CL RENO, NEVADA SP Amer Inst Aeronaut & Astronaut AB Time-accurate Euler simulations for the Row through a two-dimensional cascade subjected to an upstream acoustic disturbance were used as the basis for a small-disturbance model to predict the reflected response upstream of the cascade. The small-disturbance model results in a linear system of algebraic equations fur the properties of the reflected and transmitted disturbances. The model predicts the reflected and transmitted responses as a function of the cascade blade geometry, the disturbance amplitude, and the initial Row properties. A new characteristic outflow boundary condition based on the small-disturbance response model was formulated and demonstrated independently in two one-dimensional Euler codes. The new boundary condition was found to provide a significant improvement in accuracy for the reflection response of an acoustic disturbance from a compressor relative to existing outflow boundary-condition models. C1 NASA, John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. NR 16 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 0001-1452 J9 AIAA J JI AIAA J. PD AUG PY 2000 VL 38 IS 8 BP 1322 EP 1330 DI 10.2514/2.1131 PG 9 WC Engineering, Aerospace SC Engineering GA 339WU UT WOS:000088501500003 ER PT J AU Rumsey, CL Gatski, TB Morrison, JH AF Rumsey, CL Gatski, TB Morrison, JH TI Turbulence model predictions of strongly curved flow in a U-duct SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA 37th Aerospace Sciences Meeting and Exhibit CY JAN 11-14, 1999 CL RENO, NEVADA SP Amer Inst Aeronaut & Astronaut ID REYNOLDS STRESS MODEL; HIGH-LIFT FLOWS; BOUNDARY-LAYERS; HOMOGENEOUS TURBULENCE; STREAMLINE CURVATURE; CLOSURE MODELS; EXPLICIT; ROTATION; WALL AB The ability of three types of turbulence models to accurately predict the effects of curvature on the flow in a U-duct is studied. An explicit algebraic stress model performs slightly better than one- or two-equation linear eddy viscosity models, although it is necessary to fully account for the variation of the production-to-dissipation-rate ratio in the algebraic stress model formulation. In their original formulations, none of these turbulence models fully captures the suppressed turbulence near the convex wall, whereas a full Reynolds stress model does. Some of the underlying assumptions used in the development of algebraic stress models an! investigated and compared with the computed flowfield from the full Reynolds stress model. Through this analysis, the assumption of Reynolds stress anisotropy equilibrium used in the algebraic stress model formulation is Found to he incorrect in regions of strong curvature. By the accounting for the local variation of the principal axes of the strain rate tensor, the explicit algebraic stress model correctly predicts the suppressed turbulence in the outer part of the boundary layer near the convex wall. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Rumsey, CL (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 40 TC 49 Z9 51 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD AUG PY 2000 VL 38 IS 8 BP 1394 EP 1402 DI 10.2514/2.1115 PG 9 WC Engineering, Aerospace SC Engineering GA 339WU UT WOS:000088501500011 ER PT J AU Kodiyalam, S Sobieszczanski-Sobieski, J AF Kodiyalam, S Sobieszczanski-Sobieski, J TI Bilevel integrated system synthesis with response surfaces SO AIAA JOURNAL LA English DT Article ID OPTIMIZATION AB Two variants of the BLISS method are proposed for multidisciplinary design optimization (MDO). These variants utilize experimental design methods and response surfaces to reduce the number of expensive system analysis required for solution of the MDO problem. BLISS is an MDO method for decomposition-based optimization of engineering systems that involves system optimization with a relatively small number of design variables and a number of subsystem optimizations that could each have a large number of local variables. In BLISS, the optimum sensitivity analysis data are used to relate the subsystem optimization solutions with the system optimizations. Instead, with the proposed variants, polynomial response surface approximations using either the system analysis or the subsystem optimization results are used. Additionally, the response surface construction process is well suited for computing in a concurrent processing environment. The proposed variants are implemented and evaluated on a conceptual-level aircraft and ship design problem. C1 Lockheed Martin Space Syst Co, Ctr Adv Technol, Sunnyvale, CA 94089 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Kodiyalam, S (reprint author), Lockheed Martin Space Syst Co, Ctr Adv Technol, 1111 Lockheed Martin Way, Sunnyvale, CA 94089 USA. NR 16 TC 29 Z9 32 U1 1 U2 10 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 AUG PY 2000 VL 38 IS 8 BP 1479 EP 1485 DI 10.2514/2.1126 PG 7 WC Engineering, Aerospace SC Engineering GA 339WU UT WOS:000088501500021 ER PT J AU Rivkina, EM Friedmann, EI McKay, CP Gilichinsky, DA AF Rivkina, EM Friedmann, EI McKay, CP Gilichinsky, DA TI Metabolic activity of permafrost bacteria below the freezing point SO APPLIED AND ENVIRONMENTAL MICROBIOLOGY LA English DT Article ID CRYPTOENDOLITHIC MICROBIAL COMMUNITY; ROSS DESERT; MICROORGANISMS; TEMPERATURES; ADAPTATION; ANTARCTICA; CARBON; LIFE AB Metabolic activity was measured in the laboratory at temperatures between 5 and -20 degrees C on the basis of incorporation of C-14-labeled acetate into lipids by samples of a natural population of bacteria from Siberian permafrost (permanently frozen soil). Incorporation followed a sigmoidal pattern similar to growth curves. At all temperatures, the log phase was followed, within 200 to 350 days, by a stationary phase, which was monitored until the 550th day of activity. The minimum doubling times ranged from 1 day (5 degrees C) to 20 days (-10 degrees C) to ca, 160 days (-20 degrees C). The curves reached the stationary phase at different levels, depending on the incubation temperature, We suggest that the stationary phase, which is generally considered to be reached when the availability of nutrients becomes limiting, was brought on under our conditions by the formation of diffusion barriers in the thin layers of unfrozen water known to be present in permafrost soils, the thickness of which depends on temperature. C1 Florida State Univ, Dept Biol Sci, Tallahassee, FL 32306 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Russian Acad Sci, Inst Basic Biol Problems, Pushchino 142292, Moscow Region, Russia. RP Friedmann, EI (reprint author), Florida State Univ, Dept Biol Sci, B-157, Tallahassee, FL 32306 USA. EM friedm@bio.fsu.edu RI Rivkina, Elizaveta/O-5344-2014 OI Rivkina, Elizaveta/0000-0001-7949-8056 NR 32 TC 286 Z9 310 U1 5 U2 63 PU AMER SOC MICROBIOLOGY PI WASHINGTON PA 1752 N ST NW, WASHINGTON, DC 20036-2904 USA SN 0099-2240 EI 1098-5336 J9 APPL ENVIRON MICROB JI Appl. Environ. Microbiol. PD AUG PY 2000 VL 66 IS 8 BP 3230 EP 3233 DI 10.1128/AEM.66.8.3230-3233.2000 PG 4 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA 340QP UT WOS:000088546300015 PM 10919774 ER PT J AU Yan, L McCarthy, PJ Weymann, RJ Malkan, MA Teplitz, HI Storrie-Lombardi, LJ Smith, M Dressler, A AF Yan, L McCarthy, PJ Weymann, RJ Malkan, MA Teplitz, HI Storrie-Lombardi, LJ Smith, M Dressler, A TI Extremely red objects from the Hubble Space Telescope NICMOS parallel imaging survey SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : elliptical and lenticular, cD; galaxies : starburst ID GALAXY; POPULATION; REDSHIFT AB We present a catalog of extremely red objects (EROs) discovered using the Hubble Space Telescope Near Infrared Camera and Multi-Object Spectrometer (NICMOS) parallel imaging database and ground-based optical follow-up observations. Within an area of 16 arcmin(2), we detect 15 objects with R-F160W > 5 and F160W < 21.5. We have also obtained K-band photometry for a subset of the 15 EROs. All of the R-F160W selected EROs imaged at K-band have R-K > 6. Our objects have F110W-F160W colors in the range 1.3-2.1, redder than the cluster elliptical galaxies at z similar to 0.8 and nearly 1 mag redder than the average population selected from the F160W images at the same depth. In addition, among only 22 NICMOS pointings, we detected two groups or clusters in two fields; each contains three or more EROs, suggesting that extremely red galaxies may be strongly clustered. At bright magnitudes with F160W < 19.5, the ERO surface density is similar to what has been measured by other surveys. At the limit of our sample, F160W = 21.5, our measured surface density is 0.94 +/- 0.24 arcmin(-2). Excluding the two possible groups or clusters and the one apparently stellar object reduces the surface density to 0.38 +/- 0.15 arcmin(-2). C1 Observ Carnegie Inst Washington, Pasadena, CA 91101 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. CALTECH, SIRTF Sci Ctr, Pasadena, CA 91125 USA. Cerro Tololo Interamer Observ, La Serena, Chile. RP Yan, L (reprint author), Observ Carnegie Inst Washington, 813 Santa Barbara St, Pasadena, CA 91101 USA. EM lyan@ociw.edu NR 25 TC 29 Z9 29 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 2000 VL 120 IS 2 BP 575 EP 582 DI 10.1086/301454 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349HZ UT WOS:000089040800007 ER PT J AU Dale, DA Silbermann, NA Helou, G Valjavec, E Malhotra, S Beichman, CA Brauher, J Contursi, A Dinerstein, HL Hollenbach, DJ Hunter, DA Kolhatkar, S Lo, KY Lord, SD Lu, NYY Rubin, RH Stacey, GJ Thronson, HA Werner, MW Corwin, HG AF Dale, DA Silbermann, NA Helou, G Valjavec, E Malhotra, S Beichman, CA Brauher, J Contursi, A Dinerstein, HL Hollenbach, DJ Hunter, DA Kolhatkar, S Lo, KY Lord, SD Lu, NYY Rubin, RH Stacey, GJ Thronson, HA Werner, MW Corwin, HG TI ISO mid-infrared observations of normal star-forming galaxies: The key project sample SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : general; galaxies : ISM ID VIRGO CLUSTER; EMISSION; NGC-6946; MAPS; IC-10; DUST AB We present mid-infrared maps and preliminary analysis for 61 galaxies observed with the ISOCAM instrument aboard the Infrared Space Observatory. Many of the general features of galaxies observed at optical wavelengths-spiral arms, disks, rings, and bright knots of emission-are also seen in the midinfrared, except the prominent optical bulges are absent at 6.75 and 15 mu m In addition, the maps are quite similar at 6.75 and 15 mu m, except for a few cases where a central starburst leads to lower I-nu(6.75 mu m)/I-nu(15 mu m) ratios in the inner region. We also present infrared flux densities and mid-infrared sizes for these galaxies. The mid-infrared color I-nu(6.75 mu m)/I-nu(15 mu m) shows a distinct trend with the far-infrared color I-nu(60 mu m)/I-nu(100 mu m). The quiescent galaxies in our sample [I-nu(60 mu m)/I-nu(100 mu m) less than or similar to 0.6] show I-nu(6.75 mu m)/I-nu(15 mu m) near unity, whereas this ratio drops significantly for galaxies with higher global heating intensity levels. Azimuthally averaged surface brightness profiles indicate the extent to which the mid-infrared flux is centrally concentrated, and provide information on the radial dependence of midinfrared colors. The galaxies are mostly well resolved in these maps: almost half of them have < 10% of their flux in the central resolution element. A comparison of optical and mid-infrared isophotal profiles indicates that the flux at 4400 Angstrom near the optical outskirts of the galaxies is approximately 8 (7) times that at 6.75 mu m (15 mu m), comparable to observations of the diffuse quiescent regions of the Milky Way. C1 CALTECH, IPAC, Pasadena, CA 91125 USA. Univ Texas, Dept Astron, Austin, TX 78712 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Lowell Observ, Flagstaff, AZ 86001 USA. Univ Illinois, Dept Astron, Urbana, IL 61801 USA. Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. NASA HQ, Washington, DC 20024 USA. Jet Prop Lab, Pasadena, CA 91109 USA. RP Dale, DA (reprint author), CALTECH, IPAC, MS 100-22, Pasadena, CA 91125 USA. RI Thronson, Harley/E-3382-2012 NR 36 TC 80 Z9 80 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 2000 VL 120 IS 2 BP 583 EP 603 DI 10.1086/301478 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349HZ UT WOS:000089040800008 ER PT J AU Surace, JA Sanders, DB AF Surace, JA Sanders, DB TI Imaging of ultraluminous infrared galaxies in the near-ultraviolet SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : interactions; galaxies : starburst; galaxies : star clusters; infrared radiation ID HUBBLE DEEP FIELD; PHOTOMETRIC STANDARD STARS; ENERGY-DISTRIBUTIONS; HIGH-REDSHIFT; STARBURST GALAXIES; CELESTIAL EQUATOR; ACTIVE GALAXIES; UBVRI; EVOLUTION; TELESCOPE AB We present the first ground-based U' (lambda(central) = 3410 Angstrom, Delta(lambda) = 320 Angstrom) images of ultraluminous infrared galaxies (ULIGs). Two samples were observed: (1) "warm" ULIGs with mid-infrared colors characteristic of active galactic nuclei (f(25 mu m)/f(60 mu m) > 0.2), which are believed to represent a critical transition phase between cooler ULIGs and optically selected QSOs according to a previously proposed evolutionary model, and (2) the complementary "cool" ULIGs (f(25 mu m)/f(60 mu m) < 0.2), which in the evolutionary model are the progenitors of warm ULIGs and which have many characteristics associated with active star formation. Although in some cases there is also emission identified with an active galactic nucleus, the U' emission originates primarily in massive young stars and as such allows a direct examination of the sites of recent high-mass star formation. Strong U' emission (median total M-U = -20.8) is seen in all systems, and in some cases the extended tidal features (both the smooth stellar distribution and compact star-forming features) contribute up to 60%-80% of the total flux. The star-forming regions in both samples are found to have ages based on spectral synthesis models in the range 10-100 Myr, and most differences in color between them can be attributed to the effects of dust reddening. Additionally, it is found that star formation in compact knots in the tidal tails is most prominent in those ULIGs that have double nuclei, suggesting that the star formation rate in the tails peaks prior to the actual coalescence of the galaxy nuclei and diminishes quickly thereafter. Similar to results at other wavelengths, the observed star formation at U' can account for only a small fraction of the known bolometric luminosity of the ULIGs. Azimuthally averaged radial light profiles at U' are characterized by a SBrsic law with index n = 2, which is intermediate between an exponential disk and an r(-1/4) law and closely resembles the latter at large radii. The implications of this near-ultraviolet imaging for optical/near-infrared observations of high-redshift counterparts of ULIGs are discussed. C1 CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. RP Surace, JA (reprint author), CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, MS 100-22, Pasadena, CA 91125 USA. NR 59 TC 53 Z9 53 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 2000 VL 120 IS 2 BP 604 EP 620 DI 10.1086/301491 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349HZ UT WOS:000089040800009 ER PT J AU Neff, SG Ulvestad, JS AF Neff, SG Ulvestad, JS TI VLA observations of the nearby merger NGC 4038/4039: HII regions and supernova remnants in the "antennae" SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 4038, NGC 4039); galaxies : interactions; galaxies : starburst; galaxies : star clusters; galaxies : stellar content ID SPACE-TELESCOPE OBSERVATIONS; STAR-FORMATION HISTORY; LUMINOUS IRAS SOURCES; HUBBLE DEEP FIELD; H-II REGIONS; RADIO-EMISSION; INTERACTING GALAXIES; FORMING GALAXIES; SEYFERT-GALAXIES; HIGH-REDSHIFT AB We present 6 and 4 cm radio images of the inner disks of the nearby merger pair NGC 4038 and NGC 4039 at resolutions between similar to 1 " and 2."6, or similar to 100 and 260 pc. We detect numerous compact radio sources embedded in more diffuse radio emission; the compact radio sources produce similar to 12% and similar to 25% of the 6 and 4 cm radio emission in the system, respectively. The strongest radio continuum emission occurs between the galaxies, at an optically unremarkable location near but not coincident with an extremely red cluster detected by Whitmore & Schweizer. The radio peak is at a location of intense star formation (as detected in the mid-IR) and of dense molecular gas. We identify 115 individual compact 6 cm radio sources and 63 individual 4 cm sources in the system, to a limiting luminosity of similar to 2 x 10(18) W Hz(-1), or,4 times the luminosity of Cas A; 90% of the 6 cm sources and 67% of the 4 cm sources are unresolved in these observations. Of the strongest sources, for which the flux densities are large enough to measure spectral indices with reasonable errors, one-third have nominally flat radio spectra, indicating that they are dominated by thermal radio emission from H II regions, and two-thirds have nominally steep spectra dominated by nonthermal emission from supernova remnants. For the compact sources dominated by thermal emission, we derive typical masses of 10(4) to 10(5) M. in massive young stars. Using reasonable assumptions about source sizes, we estimate associated ionized gas masses of 10(3) to 10(4) M.. A comparison with the similar to(2-5) x 10(3) M. typical optical clusters detected recently by Whitmore et al. suggests that the thermal radio sources detected here may be composed of tens of these typical young star clusters or else that they are more like the individual massive 10(5)-10(6) M. Whitmore et al. clusters. The strongest thermal radio source is associated with none of the Whitmore et al. clusters but is coincident with strong CO and 15 mu m emission, implying that massive star clusters are still enshrouded by dust in this region. The second strongest thermal source is near several optical clusters, suggesting that these clusters are just now emerging from their birth cloud and are clearing away the surrounding material. Estimates of stellar ages and sound speeds indicate that we do not see star formation propagating in this system; rather, the star formation sequence is probably related to more global properties of the interaction. From the steep-spectrum sources, we derive a total system supernova rate of 0.2-0.3 yr(-1), about an order of magnitude larger than that expected from the currently observed O star population. This suggests that a large number of O stars may have formed in the system in a short-lived burst, less than 10(6) yr in duration and about 3-4 Myr ago. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Radio Astron Observ, Socorro, NM 87801 USA. RP Neff, SG (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. EM neff@stars.gsfc.nasa.gov; julvesta@aoc.nrao.edu NR 63 TC 78 Z9 78 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 2000 VL 120 IS 2 BP 670 EP 696 DI 10.1086/301503 PG 27 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349HZ UT WOS:000089040800013 ER PT J AU Gaidos, EJ Henry, GW Henry, SM AF Gaidos, EJ Henry, GW Henry, SM TI Spectroscopy and photometry of nearby young solar analogs SO ASTRONOMICAL JOURNAL LA English DT Article DE planetary systems; solar system : formation; stars : evolution; Sun ID MAIN-SEQUENCE STARS; URSA-MAJOR GROUP; SUN-LIKE STARS; LITHIUM ABUNDANCES; GIANT STARS; X-RAY; EVOLUTION; ROTATION; PLEIADES; CLUSTERS AB We present new photometry and spectroscopy of 34 stars from a catalog of 38 nearby (d < 25 pc) G and K dwarfs selected as analogs to the early Sun. We report that the least active star in our sample is also slowly rotating and probably of solar age. Two other stars appear to be evolved objects that have recently acquired angular momentum. A fourth star may be a spectroscopic binary. Many of the other stars belong to previously identified common proper-motion groups. Space motions, lithium abundances, and Ca II emission of these stars suggest ages between 70 and 800 Myr. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Tennessee State Univ, Ctr Excellence Informat Syst, Nashville, TN 37203 USA. RP Gaidos, EJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 39 TC 85 Z9 86 U1 1 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 2000 VL 120 IS 2 BP 1006 EP 1013 DI 10.1086/301488 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349HZ UT WOS:000089040800042 ER PT J AU Brown, TM Kimble, RA Ferguson, HC Gardner, JP Collins, NR Hill, RS AF Brown, TM Kimble, RA Ferguson, HC Gardner, JP Collins, NR Hill, RS TI Measurements of the diffuse ultraviolet background and the terrestrial airglow with the space telescope imaging spectrograph SO ASTRONOMICAL JOURNAL LA English DT Article DE ultraviolet emission ID HUBBLE DEEP FIELD; GALAXY PHOTOMETRY; DATA REDUCTION; RADIATION; DUST AB Far-UV observations in and near the Hubble Deep Fields demonstrate that the Space Telescope Imaging Spectrograph (STIS) may obtain unique and precise measurements of the diffuse far-ultraviolet background. Although STIS is not the ideal instrument for such measurements, high-resolution images allow Galactic and extragalactic objects to be masked to very faint magnitudes, thus ensuring a measurement of the truly diffuse UV signal. The programs we have analyzed were not designed for this scientific purpose, but they would be sufficient to obtain a very sensitive measurement if it were not for a weak but larger than expected signal from airglow in the STIS 1450-1900 Angstrom bandpass. Our analysis shows that STIS far-UV crystal quartz observations taken near the limb during orbital day can detect a faint airglow signal, most likely from N I lambda 1493, that is comparable to the dark rate and inseparable from the far-UV background. Discarding all but the night data from these data sets yields the diffuse far-ultraviolet background measurement 501 +/- 103 photons cm(-2) s(-1) sr(-1) Angstrom(-1), along a line of sight with very low Galactic neutral hydrogen column (N-HI = 1.5 x 10(20) cm(-2)) and extinction [E(B- V) = 0.01 mag]. This result is in good agreement with earlier measurements of the far-UV background and should not include any significant contribution from airglow. We present our findings as a warning to other groups who may use the STIS far-UV camera to observe faint extended targets and to demonstrate how this measurement may be properly obtained with STIS. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. RP Brown, TM (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. NR 24 TC 30 Z9 30 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 2000 VL 120 IS 2 BP 1153 EP 1159 DI 10.1086/301468 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349HZ UT WOS:000089040800054 ER PT J AU Moehler, S Sweigart, AV Landsman, WB Heber, U AF Moehler, S Sweigart, AV Landsman, WB Heber, U TI Hot HB stars in globular clusters - Physical parameters and consequences for theory V. Radiative levitation versus helium mixing SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : early-type; stars : fundamental parameters; stars : horizontal-branch; Galaxy : globular clusters : individual : NGC 6752 ID HORIZONTAL-BRANCH STARS; RED GIANT STARS; B-STARS; NGC-6752; HIPPARCOS; CIRCULATION; PHOTOMETRY; PARALLAXES; ANOMALIES; ALUMINUM AB Atmospheric parameters (T-eff, log g), masses and helium abundances are derived for 42 hot horizontal branch (HB) stars in the globular cluster NGC 6752. For 19 stars we derive magnesium and iron abundances as well and find that iron is enriched by a factor of 50 on average with respect to the cluster abundance whereas the magnesium abundances are consistent with the cluster abundance. Radiation pressure may levitate heavy elements like iron to the surface of the star in a diffusive process. Taking into account the enrichment of heavy elements in our spectroscopic analyses we find that high iron abundances can explain part, but not all, of the problem of anomalously low gravities along the blue HE. The blue HE stars cooler than about 15,100 K and the sdB stars (T-eff greater than or equal to 20,000 K) agree well with canonical theory when analysed with metal-rich ([M/H] = +0.5) model atmospheres, but the stars in between these two groups remain offset towards lower gravities and masses. Deep Mixing in the red giant progenitor phase is discussed as another mechanism that may influence the position of the blue HE stars in the (T-eff, log g)-plane but not their masses. C1 Univ Erlangen Nurnberg, Astron Inst, Dr Remeis Sternwarte, D-96049 Bamberg, Germany. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. RP Moehler, S (reprint author), Univ Erlangen Nurnberg, Astron Inst, Dr Remeis Sternwarte, Sternwartstr 7, D-96049 Bamberg, Germany. EM moehler@sternwarte.uni-erlangen.de; sweigart@bach.gsfc.nasa.gov; landsman@mpb.gsfc.nasa.gov; heber@sternwarte.uni-erlangen.de RI Heber, Ulrich/G-3306-2013 OI Heber, Ulrich/0000-0001-7798-6769 NR 49 TC 69 Z9 69 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 AUG PY 2000 VL 360 IS 1 BP 120 EP 132 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 345PN UT WOS:000088824500016 ER PT J AU Justtanont, K Barlow, MJ Tielens, AGGM Hollenbach, D Latter, WB Liu, XW Sylvester, RJ Cox, P Rieu, NQ Skinner, CJ AF Justtanont, K Barlow, MJ Tielens, AGGM Hollenbach, D Latter, WB Liu, XW Sylvester, RJ Cox, P Rieu, NQ Skinner, CJ TI ISO-LWS observations of rotational CO lines from C-rich objects: AFGL 2688, AFGL 618 and NGC 7027 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : circumstellar matter; stars : evolution; stars : individual : NGC 7027, AFGL 618, AFGL 2688; stars : late-type; stars : mass-loss; infrared : stars ID LONG-WAVELENGTH SPECTROMETER; PLANETARY-NEBULA NGC-7027; PHOTODISSOCIATION REGIONS; INTERSTELLAR SHOCKS; CARBON-MONOXIDE; EGG NEBULA; EMISSION; AFGL-2688; SPECTRUM; IRC+10216 AB We present ISO-LWS full scan observations of CO rotational emission lines (J=14-13 up to J=37-36) from two C-rich post-AGE objects, AFGL 2688; AFGL 618, and one C-rich PN, NGC 7027. The presence of high rotational lines cannot be explained by a spherical, constant velocity wind during the previous AGE phase, but indicates a layer of warm, dense gas with a substantial beam filling factor(Ohm > 10(-10) sr). By simple optically thin calculations, we estimate the total mass of gas cooled through CO rotational lines to be typically similar to 0.1 M.. We also consider the physical processes responsible for heating and cooling the warm gas in these objects. Energy sources for the gas could include FUV photons, resulting in a PhotoDissociation Region (PDR), as well as shocks driven by the interacting winds during this evolutionary phase. We have calculated detailed models for the heating and cooling in C-rich PDRs and shocks in order to explain the CO spectra observed. In both models, the gas is cooled radiatively by molecular rotational lines as well as by atomic fine structure lines. Both models can produce warm gas of >500 K at a density of 10(6) - 10(7) cm(-3). We conclude that the source of heating for the young PN, NGC 7027, is FUV photons from the central star For the least evolved post-AGE star, AFGL 2688, the effective temperature is too cool to produce many FUV photons to heat the gas. However, there is evidence of a fast wind developing and hence the most likely heating mechanism for the envelope is shocks. For AFGL 618, the central star is hot enough to provide copious amounts of FUV photons but fast outflows have also been observed and both processes may be operational. However, in view of [O I] 63 mu m high resolution observations, the heating mechanism is more likely to be a PDR. C1 Stockholm Observ, S-13336 Saltsjobaden, Sweden. UCL, Dept Phys & Astron, London WC1E 6BT, England. Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands. SRON Groningen, NL-9700 AV Groningen, Netherlands. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. CALTECH, IPAC, SIRTF Sci Ctr, Pasadena, CA 91125 USA. Univ Paris 11, IAS, F-91405 Orsay, France. Observ Paris, F-75014 Paris, France. RP Stockholm Observ, S-13336 Saltsjobaden, Sweden. EM kay@astro.su.se RI Barlow, Michael/A-5638-2009; OI Barlow, Michael/0000-0002-3875-1171; /0000-0003-1689-9201 NR 45 TC 27 Z9 27 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 AUG PY 2000 VL 360 IS 3 BP 1117 EP 1125 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357JJ UT WOS:000089494500032 ER PT J AU Dahlem, M Parmar, A Oosterbroek, T Orr, A Weaver, KA Heckman, TM AF Dahlem, M Parmar, A Oosterbroek, T Orr, A Weaver, KA Heckman, TM TI Ambiguities in fits to the complex X-ray spectra of starburst galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : halos; galaxies : individual (M82, NGC 253; NGC 3034); galaxies : ISM; galaxies : starburst; X-rays : galaxies ID M82 AB Spectral fits to X-ray data from both NGC 253 and M82 provide ambiguous results. The so-called best-fit results depend on the instrument with which the data were obtained and, obviously, on the choice of spectral model composition. We show that different spectral models can be fit equally well to BeppoSAX data of both galaxies. Metallicities are unreliable in general, with a strong dependence on the choice of model. Preference to one particular spectral model can be given only by combining spectroscopic and imaging X-ray data from all available satellites (ROSAT, ASCA, and BeppoSAX). Based on spectra of NGC 253, we demonstrate that a model consisting of two or more thermal plasma components plus a hard power-law continuum and Fe Ka line emission can explain all observations. These model components represent the integral spectrum of thermal gas and compact sources in starburst galaxies that are most likely supernova remnants and X-ray binaries. The same model can fit the X-ray data of M82, but there the evidence, from ROSAT imaging, of the existence of compact sources which might represent high-mass X-ray binaries is weaker. This implies that its hard X-ray emission, which is extended in ROSAT images, might-if truly diffuse-be dominated by a very hot (several keV energy) thermal gas component. C1 European Space Technol Ctr, Div Astrophys, Dept Space Sci, NL-2200 AG Noordwijk, Netherlands. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RP Dahlem, M (reprint author), European Space Technol Ctr, Div Astrophys, Dept Space Sci, Postbus 299, NL-2200 AG Noordwijk, Netherlands. NR 16 TC 22 Z9 22 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2000 VL 538 IS 2 BP 555 EP 558 DI 10.1086/309186 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 345PR UT WOS:000088824800009 ER PT J AU Smith, DA Allen, RJ Bohlin, RC Nicholson, N Stecher, TP AF Smith, DA Allen, RJ Bohlin, RC Nicholson, N Stecher, TP TI A new probe of the molecular gas in galaxies: Application to M101 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (M101); galaxies : ISM; ISM : clouds; ISM : molecules; radio lines : galaxies; ultraviolet : galaxies ID H-II REGIONS; ULTRAVIOLET IMAGING TELESCOPE; LARGE-SCALE DISSOCIATION; SPIRAL STRUCTURE; STAR FORMATION; PHOTODISSOCIATION REGION; INTERSTELLAR-MEDIUM; IONIZED HYDROGEN; NEARBY GALAXIES; EMISSION AB Recent studies of nearby spiral galaxies suggest that photodissociation regions (PDRs) are capable of producing much of the observed H I in galaxy disks. In that case, measurements of the observed H I column density and the far-ultraviolet (FUV) photon flux responsible for the photodissociation process provide a new probe of the volume density of the local underlying molecular hydrogen. We develop the method and apply it to the giant Scd spiral galaxy M101 (NGC 5457). The H I column density and amount of FUV emission have been measured for a sample of 35 candidate PDRs located throughout the disk of M101 using the Very Large Array and the Ultraviolet Imaging Telescope. We find that, after correction for the best-estimate gradient of metallicity in the interstellar medium (ISM) of M101 and for the extinction of the ultraviolet emission, molecular gas with a narrow range of density from 30-1000 cm(-3) is found near star-forming regions at all radii in the disk of M101 out to a distance of 12' approximate to 26 cm kpc, close to the photometric limit of R(25) approximate to 13.'5. In this picture, the ISM is virtually all molecular in the inner parts of M101. The strong decrease of the H I column density in the inner disk of the galaxy at R(G) < 10 kpc is a consequence of a strong increase in the dust-to-gas ratio there, resulting in an increase of the H(2) formation rate on grains and a corresponding disappearance of hydrogen in its atomic form. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. McGill Univ, Montreal, PQ, Canada. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Smith, DA (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. NR 61 TC 37 Z9 37 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2000 VL 538 IS 2 BP 608 EP 622 DI 10.1086/309172 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 345PR UT WOS:000088824800014 ER PT J AU Brainerd, JJ AF Brainerd, JJ TI A plasma instability theory of gamma-ray burst emission SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; plasmas; radiation mechanisms : nonthermal ID ELECTROMAGNETIC INSTABILITIES; BATSE OBSERVATIONS; MODEL; REDSHIFT AB A plasma instability theory is presented for the prompt radiation from gamma-ray bursts. In the theory, a highly relativistic shell interacts with the external medium through the filamentation and the two-stream instabilities to convert bulk kinetic energy into electron thermal energy and magnetic field energy. The processes are not efficient enough to satisfy the Rankine-Hugoniot conditions, so a shock cannot form through this mechanism. Instead, the external medium passes through the shell, with the electrons radiating during this passage. Gamma rays are produced by synchrotron self-Compton emission. Prompt optical emission is also produced through this mechanism, while prompt radio emission is produced through synchrotron emission. The model timescales are consistent with the shortest burst timescales. To emit gamma rays, the shell's bulk Lorentz factor must be greater than or similar to 10(3). For the radiative processes to be efficient, the external medium density must satisfy a lower limit that is a function of the bulk Lorentz factor. Because the limits operate as selection effects, bursts that violate them constitute new classes. In particular, a class of optical and ultraviolet bursts with no gamma-ray emission should exist. Efficient gamma-ray emission requires an external medium of relatively high density. Several tests of the theory are discussed, as are the next theoretical investigations that should be conducted. C1 Univ Alabama, Huntsville, AL 35899 USA. RP Brainerd, JJ (reprint author), NASA, George C Marshall Space Flight Ctr, Space Sci Lab, SD50, Huntsville, AL 35812 USA. NR 31 TC 38 Z9 38 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2000 VL 538 IS 2 BP 628 EP 637 DI 10.1086/309136 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 345PR UT WOS:000088824800016 ER PT J AU Proga, D AF Proga, D TI Winds from accretion disks driven by radiation and magnetocentrifugal force SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; hydrodynamics; MHD; methods : numerical ID ACTIVE GALACTIC NUCLEI; YOUNG STELLAR OBJECTS; ASTROPHYSICAL JETS; BIPOLAR FLOWS; MODELS; STARS; SIMULATIONS; ROTATION; CORONAE AB We study the two-dimensional, time-dependent hydrodynamics of radiation-driven winds from luminous accretion disks threaded by a strong, large-scale, ordered magnetic field. The radiation force is mediated primarily by spectral lines and is calculated using a generalized multidimensional formulation of the Sobolev approximation. The effects of the magnetic field are approximated by adding into the equation of motion a force that emulates a magnetocentrifugal force. Our approach allows us to calculate disk winds when the magnetic field controls the geometry of the how, forces the flow to corotate with the disk, or both. In particular, we calculate models in which the lines of the poloidal component of the field are straight and inclined to the disk at a fixed angle. Our numerical calculations show that hows that conserve specific angular velocity have larger mass-loss rates than their counterparts that conserve specific angular momentum. The difference in the mass-loss rates between these two types of winds can be several orders of magnitude for low disk luminosities but vanishes for high disk luminosities. Winds that conserve angular velocity have much higher velocities than angular momentum-conserving winds. Fixing the wind geometry stabilizes winds that are unsteady when the geometry is derived self-consistently. The inclination angle between the poloidal velocity and the normal to the disk midplane is important. Nonzero inclination angles allow the magnetocentrifugal force to increase the mass-loss rate for low luminosities and increase the wind velocity for all luminosities. The presence of the azimuthal force does not change the mass-loss rate when the geometry of the flow is fixed. Our calculations also show that the radiation force can launch winds from magnetized disks. The line force can be essential in producing magnetohydrodynamical (MHD) winds from disks where the thermal energy is too low to launch winds or where the field lines make an angle of less than 30 degrees with respect to the normal to the disk midplane. In the latter case the wind will be less decollimated by the centrifugal force near its base, and its collimation far away from the disk can be larger than the collimation of its centrifugally driven MHD counterpart. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Proga, D (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 34 TC 49 Z9 49 U1 0 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2000 VL 538 IS 2 BP 684 EP 690 DI 10.1086/309154 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 345PR UT WOS:000088824800023 ER PT J AU Sandford, SA Bernstein, MP Allamandola, LJ Gillette, JS Zare, RN AF Sandford, SA Bernstein, MP Allamandola, LJ Gillette, JS Zare, RN TI Deuterium enrichment of polycyclic aromatic hydrocarbons by photochemically induced exchange with deuterium-rich cosmic ices SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : molecules; meteors : meteorites; methods : laboratory; molecular processes; ultraviolet : ISM ID INTERPLANETARY DUST PARTICLES; MURCHISON METEORITE; ISOTOPIC ANALYSES; SOLAR-SYSTEM; INTERSTELLAR; MOLECULES; EMISSION; FEATURES; KEROGEN; CLOUDS AB The polycyclic aromatic hydrocarbon (PAH) coronene (C(24)H(12),) frozen in D(2)O ice in a ratio of less than 1 part in 500 rapidly exchanges its hydrogen atoms with the deuterium in the ice at interstellar temperatures and pressures when exposed to ultraviolet radiation. Exchange occurs via three different chemical processes: D atom addition, D atom exchange at oxidized edge sites, and D atom exchange at aromatic edge sites. Observed exchange rates for coronene (C(24)H(12))-D(2)O and d(12)-coronene (C(24)D(12))-H(2)O isotopic substitution experiments show that PAHs in interstellar ices could easily attain the D/H levels observed in meteorites. These results may have important consequences for the abundance of deuterium observed in aromatic materials in the interstellar medium and in meteorites. These exchange mechanisms produce deuteration in characteristic molecular locations on the PAHs that may distinguish them from previously postulated processes for D enrichment of PAHs. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Stanford Univ, Dept Chem, Stanford, CA 94305 USA. Search Extra Terr Intelligence Inst, Mountain View, CA 94043 USA. RP Sandford, SA (reprint author), NASA, Ames Res Ctr, Mail Stop 245-6, Moffett Field, CA 94035 USA. RI Zare, Richard/A-8410-2009 NR 36 TC 39 Z9 40 U1 0 U2 7 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 AUG 1 PY 2000 VL 538 IS 2 BP 691 EP 697 DI 10.1086/309147 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 345PR UT WOS:000088824800024 PM 11543580 ER PT J AU Krist, JE Stapelfeldt, KR Menard, F Padgett, DL Burrows, CJ AF Krist, JE Stapelfeldt, KR Menard, F Padgett, DL Burrows, CJ TI WFPC2 images of a face-on disk surrounding TW Hydrae SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; stars : individual (TW Hydrae); stars : pre-main-sequence ID TAURI STARS; ACCRETION; EMISSION; PLANET; GAS AB Hubble Space Telescope observations of the isolated T Tauri star TW Hydrae reveal the presence of a compact circumstellar nebula. After subtraction of a reference point-spread function (PSF), a smooth, symmetrical, circular halo can be seen in both R- and I-band WFPC2 images. Its intensity declines with radius until reaching an outer sensitivity limit at 3 ".5 (approximate to 200 AU). Numerical experiments show that PSF subtraction artifacts cannot account for the halo's brightness distribution. Instead, the most likely explanation is that the halo is a face-on circumstellar disk. The radial brightness profile of the halo is complex and can be described with multiple, contiguous zones with individual power-law intensity relations. The halo appears slightly blue relative to the star, especially in the outer zones. We compare the TW Hya halo to single-scattering models of face-on disks with multiple radial zones. While optically thin disk models with vertical optical depth tau(upsilon) approximate to 10(-2) can reproduce the relative brightness of the nebula and star, we find that such models have large midplane optical depths and are therefore not self-consistent. We present an optically thick disk model that matches the radial brightness profile self-consistently and has a dust mass close to that implied by submillimeter continuum measurements. The zonal structure found in the disk could arise from radial variations in the dust properties that determine the local equilibrium temperature or perhaps via dynamical effects of unseen companions. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. Jet Prop Lab, Pasadena, CA 91109 USA. Canada France Hawaii Telescope Corp, Kamuela, HI 96743 USA. CALTECH, IPAC, Pasadena, CA 91125 USA. European Space Agcy, Dept Space Sci, Div Astrophys, Paris, France. 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 117 Z9 117 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2000 VL 538 IS 2 BP 793 EP 800 DI 10.1086/309170 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 345PR UT WOS:000088824800034 ER PT J AU Fajardo-Acosta, SB Beichman, CA Cutri, RM AF Fajardo-Acosta, SB Beichman, CA Cutri, RM TI Discovery of new candidate vega-type systems from IRAS and the 2 micron all-sky survey SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; dust, extinction; infrared : stars ID MAIN-SEQUENCE STARS; BETA-PICTORIS DISK; INFRARED OBSERVATIONS; INTRINSIC COLORS; PHOTOMETRY; SILICATES; SEARCH; DEBRIS AB We obtained J (1.25 mu m), H (1.65 mu m), and K, (2.17 mu m) photometry from the 2 Micron All-Sky Survey and 12, 25, 60, and 100 mu m photometry from the IRAS Faint Source Catalog of 2834 field stars. We identified in this sample 296 main-sequence (luminosity class IV TV-V, or V) stars. We searched the sample of main-sequence stars for excess 12 mu m emission with respect to J, H, and K, photospheric emission. We discovered eight systems with 12 mu m excess emission newly reported here. These excesses are likely to be from Vega-type circumstellar dust, but small-aperture photometry is needed to confirm their nature. Preliminary models that assume the excesses are circumstellar show the dust to be located similar to 1-10 AU from the stars, where it is heated to "terrestrial" temperatures, similar to 200-500 K. Colder dust might also exist in the systems but below the IRAS sensitivity limit. The exception is HD 93331 (B9.5 V), previously known for its IRAS far-infrared excess. C1 CALTECH, Jet Prop Lab, IPAC, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Fajardo-Acosta, SB (reprint author), CALTECH, Jet Prop Lab, IPAC, MS 100-22, Pasadena, CA 91125 USA. EM fajardo@ipac.caltech.edu; chas@pop.jpl.nasa.gov; roc@jpac.caltech.edu NR 33 TC 16 Z9 16 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2000 VL 538 IS 2 BP L155 EP L158 DI 10.1086/312815 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 345PU UT WOS:000088825000014 ER PT J AU Sahai, R Nyman, LA AF Sahai, R Nyman, LA TI Discovery of a symmetrical highly collimated bipolar jet in Hen 2-90 SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; planetary nebulae : general; stars : AGB and post-AGB; stars : mass loss ID EXCITATION PLANETARY-NEBULAE; SYMBIOTIC STARS; MASS-LOSS; EMISSION; OBJECTS; DISK AB Using the Hubble Space Telescope, we have obtained Ha! imaging of the object Hen 2-90, which has long been classified as a planetary nebula (PN). We find that the morphology of Hen 2-90 does not look like that of any known PN, but resembles that of a classical young stellar object (YSO)-a bipolar nebula bisected by a flaring disklike structure and a highly collimated bipolar jet perpendicular to the disk. The linear jet shows at least six pairs of emission knots located symmetrically on either side of the nebular center. Taking a kinematic distance of 2.5 kpc, we find that the gas density in the knots decreases steadily from about 10(4) cm(-3) in the knots closest to the center to 1.1 x 10(3) cm(-3) in the more distant knots, and their masses lie in the range of (0.7-3.6) x 10(-6) M-circle dot. The jet opening angle is about 4 degrees, from which we estimate its speed to be similar to 150 km s(-1) Hen 2-90's near- and mid-infrared fluxes imply the presence of a massive dusty nebula containing "warm" (183 K) and "hot" (513 K) dust in components with masses 5 x 10(-3) and 2.4 x 10(-5) M., respectively (assuming a gas-to-dust ratio of 100); the source luminosity is 5280 L-circle dot. Millimeter-wave line observations show no molecular gas directly associated with the source and the absence of star-forming activity, indicating that Hen 2-90 is probably not a YSO. The most likely hypothesis for explaining Hen 2-90 requires a binary with a cool giant and a compact companion with an accretion disk. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Onsala Space Observ, S-43992 Onsala, Sweden. European So Observ, Santiago 19, Chile. RP Sahai, R (reprint author), CALTECH, Jet Prop Lab, MS 183-900, Pasadena, CA 91109 USA. NR 29 TC 42 Z9 42 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2000 VL 538 IS 2 BP L145 EP L149 DI 10.1086/312809 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 345PU UT WOS:000088825000012 ER PT J AU Woo, R Armstrong, JW Habbal, SR AF Woo, R Armstrong, JW Habbal, SR TI Observed associations between the solar interior, corona, and solar wind SO ASTROPHYSICAL JOURNAL LA English DT Article DE solar wind; Sun : corona; Sun : interior ID DENSITY STRUCTURE; ULYSSES; ROTATION; SURFACE; CYCLE; FLOWS; GONG; SUN AB Using polarized brightness (pB) measurements made by the High Altitude Observatory (HAO) Mauna Loa Mk III K-coronameter, we investigate the daily changes of path-integrated density at 1.15 R-circle dot. During 1996, when simultaneous pB and helioseismology data were available, we find that the correlation of pB (at zero time lag and 20 degrees latitude lag) varies with latitude in the same way that the subsurface differential rotation inferred from helioseismology does. The association is such that bands of higher pB correlation are associated with retrograde subsurface rotation and that lower pB correlation bands are associated with prograde subsurface rotation. We also show that polar coronal holes are distinguished by a nonrecurring longitudinal structure as opposed to a recurring structure in the quiet Sun. In addition, the levels of pB and standard deviation sigma(pB) of pB are about half of those of the neighboring quiet Sun. These statistical characteristics of coronal density in polar holes and the quiet Sun were also present in 1993-1994 and are replicated in the statistics of the distant solar wind observed by Ulysses. The association of the density (pB) correlation with subsurface flow (when simultaneous data were available in 1996), together with the association of the latitudinal dependence of the statistical characteristics (average, standard deviation, and autocorrelation function) of the coronal (pB) and solar wind (Ulysses) density (when simultaneous data were available in 1993-1994), suggest a correlated variability of subsurface flow, coronal density, and solar wind density organized by solar latitude. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Woo, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 23 TC 9 Z9 9 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2000 VL 538 IS 2 BP L171 EP L174 DI 10.1086/312803 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 345PU UT WOS:000088825000018 ER PT J AU D'haeseleer, P Liang, SD Somogyi, R AF D'haeseleer, P Liang, SD Somogyi, R TI Genetic network inference: from co-expression clustering to reverse engineering SO BIOINFORMATICS LA English DT Review ID RECURRENT NEURAL NETWORKS; SACCHAROMYCES-CEREVISIAE; COMPUTATIONAL ANALYSIS; GENOMIC SCALE; PATTERNS; YEAST; IDENTIFICATION; DISCOVERY; SYSTEMS; CONSTRUCTION AB Motivation: Advances in molecular biological, analytical and computational technologies are enabling us to systematically investigate the complex molecular processes underlying biological systems. In particular; using high-throughput gene expression assays, we are able to measure the output of the gene regulatory network. We aim here to review dntamining and modeling approaches for conceptualizing and unraveling the functional relationships implicit in these datasets. Clustering of co-expression profiles allows us to infer shared regulatory inputs and functional pathways. We discuss various aspects of clustering, ranging from distance measures to clustering algorithms and multiple-cluster memberships. More advanced analysis aims to infer causal connections between genes directly, i.e. who is regulating whom and how. We discuss several approaches to the problem of reverse engineering of genetic networks, from discrete Boolean networks, to continuous linear and non-linear models. We conclude that the combination of predictive modeling with systematic experimental verification will be required to gain a deeper insight into living organisms, therapeutic targeting and bioengineering. C1 Univ New Mexico, Dept Comp Sci, Albuquerque, NM 87131 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Incyte Pharmaceut, Palo Alto, CA 94304 USA. RP D'haeseleer, P (reprint author), Univ New Mexico, Dept Comp Sci, Albuquerque, NM 87131 USA. OI D'haeseleer, Patrik/0000-0003-0007-8150 NR 103 TC 509 Z9 527 U1 6 U2 45 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 1367-4803 J9 BIOINFORMATICS JI Bioinformatics PD AUG PY 2000 VL 16 IS 8 BP 707 EP 726 DI 10.1093/bioinformatics/16.8.707 PG 20 WC Biochemical Research Methods; Biotechnology & Applied Microbiology; Computer Science, Interdisciplinary Applications; Mathematical & Computational Biology; Statistics & Probability SC Biochemistry & Molecular Biology; Biotechnology & Applied Microbiology; Computer Science; Mathematical & Computational Biology; Mathematics GA 375AL UT WOS:000165377300006 PM 11099257 ER PT J AU Fokin, AV Afonin, PV Mikhailova, IY Tsygannik, IN Mareeva, TY Nesmeyanov, VA Pangborn, W Lee, N Duax, W Ciszak, E Pletnev, VZ AF Fokin, AV Afonin, PV Mikhailova, IY Tsygannik, IN Mareeva, TY Nesmeyanov, VA Pangborn, W Lee, N Duax, W Ciszak, E Pletnev, VZ TI The three-dimensional structure of the antigen-binding fragment of a monoclonal antibody to human interleukin-2 in two crystal forms at 2.2 and 2.9 angstrom resolution SO BIOORGANICHESKAYA KHIMIYA LA Russian DT Article DE monoclonal antibody; antigen-binding fragment, interleukin-2; X-ray analysis ID X-RAY; COMPLEX; PEPTIDE; FAB AB The three-dimensional structure of the antigen-binding fragment of a monoclonal antibody to human interleukin-2 was determined in two crystal forms by the X-ray method of molecular replacement at 2.2 and 2.9 Angstrom resolutions. The spatial structure of the protein and the stereochemistry of its antigen-binding site were analyzed. C1 Russian Acad Sci, Shemyakin Ovchinnikov Inst Bioorgan Chem, Moscow 117871, Russia. Hauptman Woodward Med Res Ctr, Buffalo, NY 14203 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL USA. RP Pletnev, VZ (reprint author), Russian Acad Sci, Shemyakin Ovchinnikov Inst Bioorgan Chem, Ul Miklukho Maklaya 16-10,GSP-7, Moscow 117871, Russia. RI Fokin, Andrey/A-1330-2013; Pletnev, Vladimir/Q-6151-2016 NR 23 TC 4 Z9 4 U1 0 U2 0 PU MEZHDUNARODNAYA KNIGA PI MOSCOW PA 39 DIMITROVA UL., 113095 MOSCOW, RUSSIA SN 0132-3423 J9 BIOORG KHIM+ JI Bioorg. Khim. PD AUG PY 2000 VL 26 IS 8 BP 571 EP 578 PG 8 WC Biochemistry & Molecular Biology; Chemistry, Organic SC Biochemistry & Molecular Biology; Chemistry GA 370CB UT WOS:000165104100002 PM 11040993 ER PT J AU Mack, WJ Xiang, M Shircore, AM Selzer, RH Hodis, HN Azen, SP AF Mack, WJ Xiang, M Shircore, AM Selzer, RH Hodis, HN Azen, SP TI Efficacy of two lipid-lowering treatments on quantitative coronary angiographic endpoints SO CARDIOVASCULAR DRUGS AND THERAPY LA English DT Article DE coronary angiography; clinical trial; quantitative coronary angiography ID COLESTIPOL-NIACIN THERAPY; END-POINT MEASURES; ARTERY DISEASE; ATHEROSCLEROSIS-REGRESSION; PROGRESSION; PATHOGENESIS; LOVASTATIN; REDUCTION; TRIALS AB This study contrasts the sensitivity of four quantitative coronary angiography (QCA) measures (percent diameter stenosis [%S], minimum lumen diameter, average segment diameter, and percent involvement) in detecting S-year treatment effects of two lipid-lowering therapies and reports on the longitudinal pattern after 4 years of treatment on the primary QCA trial endpoint (%S) for all, mild/moderate (<50%S), and severe lesions (greater than or equal to 50%S). Patient cohorts were followed up from two randomized, placebo-controlled clinical trials of lipid-lowering therapies-colestipol/niaein in the Cholesterol Lowering Atherosclerosis Study (CLAS) and lovastatin in the Monitored Atherosclerosis Regression Study (MARS). Identical QCA methodology was used. In CLAS, the largest 2-year treatment effect size (=0.60) was noted for %S. In MARS, equivalent S-year effect sizes (=0.15) were noted for three QCA measures. The largest 2-year effect size in %S was found in CLAS for mild/moderate lesions (=0.55) and in MARS for severe lesions (=0.31). Treatment in CLAS led to regression of disease in the first 2 years; treatment in MARS slowed progression of disease in the first 2 years and led to regression of disease after 4,years. Colestipol/niacin reduced progression of mild/moderate and severe lesions over the first 2 years of therapy; lovastatin reduced the progression of severe lesions over the last 2 years of therapy. We conclude that reducing the progression of atherosclerosis is not a simple proposition; maximal therapy for reducing and stabilizing atherosclerosis most likely will result from the selection of agents targeted at specific lesions. C1 Univ So Calif, Dept Prevent Med, Stat Consultat & Res Ctr, Keck Sch Med, Los Angeles, CA 90089 USA. Univ So Calif, Dept Med, Atherosclerosis Res Unit, Keck Sch Med, Los Angeles, CA 90089 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Azen, SP (reprint author), Univ So Calif, Dept Prevent Med, Stat Consultat & Res Ctr, Keck Sch Med, 1540 Alcazar St,CHP 218, Los Angeles, CA 90089 USA. FU NHLBI NIH HHS [R03-HL-54532, R01-HL-49885] NR 26 TC 1 Z9 1 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0920-3206 J9 CARDIOVASC DRUG THER JI Cardiovasc. Drugs Ther. PD AUG PY 2000 VL 14 IS 4 BP 411 EP 418 DI 10.1023/A:1007816300468 PG 8 WC Cardiac & Cardiovascular Systems; Pharmacology & Pharmacy SC Cardiovascular System & Cardiology; Pharmacology & Pharmacy GA 352YC UT WOS:000089246100009 PM 10999648 ER PT J AU Zheng, Y Chang, SW Yuan, ZP AF Zheng, Y Chang, SW Yuan, ZP TI Path-independent integral for heterogeneous media with respect to field discontinuities SO COMPUTATIONAL MATERIALS SCIENCE LA English DT Article DE fracture; fracture criterion; heterogeneous medium; finite element method ID TIP STRESS-FIELD; CRACK-TIP; DYNAMIC FIELDS; INHOMOGENEOUS MATERIALS; MESH GENERATION AB By means of counter-evidence. it is proved that the original J integral does not satisfy the conservation law for general heterogeneous media. In the present paper, a modified version J* is re-proposed, which is a path-independent integral. The modifier term is related to stress and strain discontinuities occurring in material interfaces, and possibly occurring in interfaces between elastic and plastic zones. The integral J* can be interpreted as an expression of energy release rate. therefore, there exists an integral fracture criterion correspondingly. With regard to computational aspects related to finite element analysis, interface elements have been proposed to deal with stress and strain discontinuities in the material interfaces. For a generic case, adaptive analysis is recommended to take into account the discontinuities in the material interfaces, and possible discontinuities in the interfaces between elastic and plastic zones around a crack tip, in an optimal manner. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Glenn Res Ctr, Taitech, Cleveland, OH 44135 USA. Natl Kaohsiung Inst Marine Technol, Dept Marine Engn, Kaohsiung 811, Taiwan. Harbin Inst Technol, Dept Engn Mech, Harbin 150001, Peoples R China. RP Zheng, Y (reprint author), NASA, Glenn Res Ctr, Taitech, MS 5-11,21000 Brookpk Rd, Cleveland, OH 44135 USA. RI Zheng, Yao/A-3913-2016 NR 29 TC 0 Z9 0 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-0256 J9 COMP MATER SCI JI Comput. Mater. Sci. PD AUG PY 2000 VL 18 IS 2 BP 212 EP 224 DI 10.1016/S0927-0256(00)00102-6 PG 13 WC Materials Science, Multidisciplinary SC Materials Science GA 332MV UT WOS:000088078800011 ER PT J AU Barut, A Madenci, E Tessler, A Starnes, JH AF Barut, A Madenci, E Tessler, A Starnes, JH TI A new stiffened shell element for geometrically nonlinear analysis of composite laminates SO COMPUTERS & STRUCTURES LA English DT Article DE stiffened shell; finite element; composite; nonlinear ID CYLINDRICAL-SHELLS; FINITE-ELEMENTS; PLATES; PANELS; COMPRESSION; SHEAR AB A new stiffened shell element combining shallow beam and shallow shell elements is developed for geometrically nonlinear analysis of stiffened composite laminates under mechanical loading. The formulation of this element is based on the principle of Virtual displacements in conjunction with the co-rotational form of the total Lagrangian description of motion. In the finite element formulation, both the shell and the beam (stiffener) elements account for transverse shear deformations and material anisotropy. The cross section of the stiffener (beam) can be arbitrary in geometry and lamination. In order to combine the stiffener with the shell element, constraint conditions are applied to the displacement and rotation fields of the stiffener. These constraint conditions ensure that the cross section of the stiffener remains co-planar with the shell section after deformation. The resulting expressions for the displacement and rotation fields of the stiffener involve only the nodal unknowns of the shell element, thus reducing the total number of degrees-of-freedom. Also, the discretization of the entire stiffened shell structure becomes more flexible. The robustness of the stiffened shell element has been proven by comparison against other shell elements considered previously. (C) 2000 Published by Elsevier Science Ltd. All rights reserved. C1 Univ Arizona, Dept Aerosp & Mech Engn, Tucson, AZ 85721 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Madenci, E (reprint author), Univ Arizona, Dept Aerosp & Mech Engn, Aero Bldg 16, Tucson, AZ 85721 USA. EM madenci@ame.arizona.edu RI Tessler, Alexander/A-4729-2009 NR 34 TC 8 Z9 8 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-7949 EI 1879-2243 J9 COMPUT STRUCT JI Comput. Struct. PD AUG PY 2000 VL 77 IS 1 BP 11 EP 40 DI 10.1016/S0045-7949(99)00201-1 PG 30 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA 323WD UT WOS:000087587200002 ER PT J AU Chassignet, EP Arango, H Dietrich, D Ezer, T Ghil, M Haidvogel, DB Ma, CC Mehra, A Paiva, AM Sirkes, Z AF Chassignet, EP Arango, H Dietrich, D Ezer, T Ghil, M Haidvogel, DB Ma, CC Mehra, A Paiva, AM Sirkes, Z TI DAMEE-NAB: the base experiments SO DYNAMICS OF ATMOSPHERES AND OCEANS LA English DT Article DE DAMEE,-NAB; base experiments; north Atlantic circulation ID COORDINATE OCEAN MODELS; GULF-OF-MEXICO; NORTH-ATLANTIC; MEDITERRANEAN OUTFLOW; EQUATORIAL ATLANTIC; FLORIDA CURRENT; HEAT-TRANSPORT; WIND-DRIVEN; CIRCULATION; VARIABILITY AB The results of an intercomparison experiment performed with five numerical ocean models of different architecture are presented, While all models are able to simulate the large-scale characteristics of the North Atlantic circulation with a fair degree of realism, they also exhibit differences that can be attributed to the choices made in vertical coordinates, domain size, and boundary conditions. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Div Meteorol & Phys Oceanog, Miami, FL 33149 USA. Rutgers State Univ, Inst Marine & Coastal Sci, New Brunswick, NJ 08901 USA. Mississippi State Univ, Ctr Air Sea Technol, Stennis Space Ctr, MS 39529 USA. Princeton Univ, Program Atmospher & Ocean Sci, Princeton, NJ 08544 USA. Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ So Mississippi, Ctr Ocean & Atmospher Modeling, Stennis Space Ctr, MS 39529 USA. RP Chassignet, EP (reprint author), Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Div Meteorol & Phys Oceanog, 4600 Rickenbacker Causeway, Miami, FL 33149 USA. OI Ezer, Tal/0000-0002-2018-6071 NR 64 TC 71 Z9 73 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0377-0265 J9 DYNAM ATMOS OCEANS JI Dyn. Atmos. Oceans PD AUG PY 2000 VL 32 IS 3-4 BP 155 EP 183 DI 10.1016/S0377-0265(00)00046-4 PG 29 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Oceanography SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Oceanography GA 338UE UT WOS:000088441000001 ER PT J AU Naguib, S Alban-Rojas, I Rojas, G Raffoul, G Siadaty, S Casscells, SW Naghavi, M AF Naguib, S Alban-Rojas, I Rojas, G Raffoul, G Siadaty, S Casscells, SW Naghavi, M TI Stent diathermy using focused ultrasound & microwave SO EUROPEAN HEART JOURNAL LA English DT Meeting Abstract C1 Univ Texas, Houston Med Sch, Dept Cardiol, Houston, TX USA. NASA, Radio Frequency Commun, Houston, TX USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU W B SAUNDERS CO LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0195-668X J9 EUR HEART J JI Eur. Heart J. PD AUG-SEP PY 2000 VL 21 SU S MA P1585 BP 281 EP 281 PG 1 WC Cardiac & Cardiovascular Systems SC Cardiovascular System & Cardiology GA 351BR UT WOS:000089136601092 ER PT J AU Tubiello, FN Donatelli, M Rosenzweig, C Stockle, CO AF Tubiello, FN Donatelli, M Rosenzweig, C Stockle, CO TI Effects of climate change and elevated CO2 on cropping systems: model predictions at two Italian locations SO EUROPEAN JOURNAL OF AGRONOMY LA English DT Article; Proceedings Paper CT 5th Congress of the European-Society-for-Agronomy CY JUN 28-JUL 02, 1998 CL NITRA, SLOVAKIA SP European Soc Agron DE cropping systems; climate change; elevated CO2; adaptation ID ATMOSPHERIC CARBON-DIOXIDE; WINTER-WHEAT; GROWTH; YIELD; CROPSYST; TEMPERATURE; ENRICHMENT; PRODUCTIVITY; SIMULATION; MANAGEMENT AB The potential effects of future climate change were investigated, corresponding to a doubling of atmospheric CO2 from 350 to 700 ppm, on agricultural production of four different cropping systems at two Italian locations, Modena and Foggia. Climate change scenarios, derived from two general circulation models (GCMs), were used as weather input to a soil-plant growth simulator, CropSyst. This model was recently modified to include the effects of elevated CO2 on crop photosynthesis and transpiration. Six different crops in total were simulated at the two Italian sites. At Modena, a 3-year maize-maize-wheat rotation and a 2-year soybean-barley-summer sorghum rotation were studied. At Foggia, a 2-year sunflower-wheat-fallow rotation, and a 2-year wheat-fallow-spring sorghum rotation were simulated. Results suggested that the combined effects of elevated atmospheric CO2 and climate change at both sites would depress crop yields if current management practices were not modified. Specifically, predicted warmer air temperatures accelerated plant phenology, reducing dry matter accumulation and crop yields by 10-40%. By investigating adaptation strategies, it was found that a combination of early planting for spring-summer crops and the use of slower-maturing winter cereal cultivars succeeds in maintaining crop yields at current levels at both sites. For irrigated maize and soybean production at Modena, 60-90% more irrigation water was required under climate change to keep grain yields at current levels. This implies that adaptation to climate change may be limited for irrigated crops, depending on site-specific water availability. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, GISS, New York, NY 10025 USA. Columbia Univ, New York, NY 10025 USA. ISCI Bologna, I-40128 Bologna, Italy. Washington State Univ, Dept Biol Syst Engn, Pullman, WA 99164 USA. RP Tubiello, FN (reprint author), NASA, GISS, 2880 Broadway, New York, NY 10025 USA. NR 34 TC 156 Z9 167 U1 4 U2 38 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 1161-0301 J9 EUR J AGRON JI Eur. J. Agron. PD AUG PY 2000 VL 13 IS 2-3 BP 179 EP 189 DI 10.1016/S1161-0301(00)00073-3 PG 11 WC Agronomy SC Agriculture GA 346BZ UT WOS:000088851800008 ER PT J AU Ortiz, RM Wade, CE Ortiz, CL AF Ortiz, RM Wade, CE Ortiz, CL TI Prolonged fasting increases the response of the renin-angiotensin-aldosterone system, but not vasopressin levels, in postweaned northern elephant seal pups SO GENERAL AND COMPARATIVE ENDOCRINOLOGY LA English DT Article DE homeostasis; marine mammals; osmoregulation; water balance ID WATER CONSERVATION; PLASMA VASOPRESSIN; METABOLISM; MECHANISM; BEHAVIOR AB The 8- to 12-week postweaning fast exhibited by northern elephant seal pups (Mirounga angustirostris) occurs without any apparent deleterious effects on fluid and electrolyte homeostasis. However, during the fast the role of vasopressin (AVP) has been shown to be inconclusive and the involvement of the renin-angio-tensin-aldosterone system (RAAS) has yet to he examined. To examine the effects of prolonged fasting on these osmoregulatory hormones, 15 postweaned pups were serially blood-sampled during the first 49 days of their fast. Fasting did not induce significant changes in ionic or osmotic concentrations, suggesting electrolyte homeostasis. Total proteins were reduced by day 21 of fasting and remained depressed, suggesting a lack of dehydration. Aldosterone and plasma renin activity exhibited a correlated, linear increase over the first 49 days of the fast, suggesting an active RAAS. Aldosterone exhibited a parabolic trend over the fast with a peak at day 35, suggesting a shift in the sensitivity of the kidney to aldosterone later in the fast. AVP was elevated at day 49 only, but concentrations were relatively low. RAAS was modified during the postweaning fast in pups and appears to play a significant role in the regulation of electrolyte and, most likely, water homeostasis during this period. (C) 2000 Academic Press. C1 Univ Calif Santa Cruz, Dept Biol, Santa Cruz, CA 95064 USA. NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. RP Ortiz, RM (reprint author), Univ Calif Santa Cruz, Dept Biol, Santa Cruz, CA 95064 USA. FU NIGMS NIH HHS [GM 58903-01] NR 26 TC 28 Z9 29 U1 0 U2 6 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0016-6480 EI 1095-6840 J9 GEN COMP ENDOCR JI Gen. Comp. Endocrinol. PD AUG PY 2000 VL 119 IS 2 BP 217 EP 223 DI 10.1006/gcen.2000.7514 PG 7 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA 345UF UT WOS:000088833000011 PM 10936042 ER PT J AU O'Connor, WP Chao, BF Zheng, DW Au, AY AF O'Connor, WP Chao, BF Zheng, DW Au, AY TI Wind stress forcing of the North Sea 'pole tide' SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE Chandler wobble; North Sea; pole tide; sea level; tides; winds ID EUROPEAN CONTINENTAL-SHELF; STORM-SURGE MODEL; NUMERICAL-MODEL; GLOBAL OCEANS; DYNAMICS; CIRCULATION; LEVEL AB We conduct numerical simulations of the wind forcing of sea level variations in the North Sea using a barotropic ocean model with realistic geography and bathymetry to examine the forcing of the 14 month 'pole tide', which is known to be anomalously large along the Denmark-Netherlands coast. The simulation input is the monthly mean surface wind stress field from the National Centers for Environmental Prediction (NCEP) reanalysis for the 40 year period 1958-1997. The ocean model output sea level response is then compared with 10 coastal tide gauge records from the Permanent Service for Mean Sea Level (PSMSL) over the same period of time. Besides the strong seasonal variations, several prominent quasi-periodicities exist near 7 years, 3 years, 14 months, 9 months and 6.5 months. Correlations and spectral analyses show remarkable agreement between the model output and the observations, particularly in the 14 month, or Chandler, period band. The latter indicates that the enhanced pole tide found in the North Sea along the Denmark-Netherlands coast is actually the coastal set-up response to wind stress forcing with a periodicity of around 14 months. We find no need to invoke a geophysical explanation involving resonance enhancement of the pole tide in the North Sea to explain the observations. C1 NASA, Goddard Space Flight Ctr, Space Geodesy Branch, Greenbelt, MD 20771 USA. NOAA, NOS, Coast Survey Dev Lab, Silver Spring, MD 20910 USA. Chinese Acad Sci, Shanghai Astron Observ, Shanghai 200030, Peoples R China. Raytheon ITSS, Lanham, MD 20706 USA. RP Chao, BF (reprint author), NASA, Goddard Space Flight Ctr, Space Geodesy Branch, Code 926, Greenbelt, MD 20771 USA. RI Chao, Benjamin Fong/N-6156-2013 NR 51 TC 10 Z9 10 U1 0 U2 2 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0956-540X J9 GEOPHYS J INT JI Geophys. J. Int. PD AUG PY 2000 VL 142 IS 2 BP 620 EP 630 DI 10.1046/j.1365-246x.2000.00184.x PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 339NG UT WOS:000088482700025 ER PT J AU Buechler, DE Driscoll, KT Goodman, SJ Christian, HJ AF Buechler, DE Driscoll, KT Goodman, SJ Christian, HJ TI Lightning activity within a tornadic thunderstorm observed by the optical transient detector (OTD) SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STORM AB The first storm-scale, total lightning observations from space during tornadogenesis are presented. During the overpass of an Oklahoma supercell, just minutes prior to tornado touchdown on 17 April 1995, the NASA (National Aeronautics and Space Administration) OTD (Optical Transient Detector) detected a total of 143 flashes during approximately 3 minutes of observation time. The estimated total hash rate ranges from 45 (raw counts) to 78 (corrected for detection efficiency) flashes min(-1). This total flash rate was at least 17 times greater than the cloud-to-ground lightning rate detected by the National Lightning Detection Network (NLDN), indicating most of the lightning was intracloud. Cloud-to-ground lightning at this time was also dominated by positive polarity flashes. In addition, total lightning rates were decreasing rapidly prior to touchdown. These OTD observations are consistent with the limited results from recent ground based measurements of total lightning activity in tornadic storms and corroborate that such storms have unusually high total flash rates, are dominated by intracloud lightning, and that the total flash rates are observed to decrease rapidly in the minutes prior to touchdown. C1 Univ Alabama, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Buechler, DE (reprint author), Global Hydrol & Climate Ctr, 977 Explorer Blvd, Huntsville, AL 35806 USA. NR 17 TC 18 Z9 21 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 1 PY 2000 VL 27 IS 15 BP 2253 EP 2256 DI 10.1029/2000GL011579 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 341JL UT WOS:000088587200021 ER PT J AU Chao, Y Ghil, M McWilliams, JC AF Chao, Y Ghil, M McWilliams, JC TI Pacific interdecadal variability in this century's sea surface temperatures SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID UPPER-OCEAN TEMPERATURE; NORTH PACIFIC; EL-NINO; DECADAL VARIABILITY; CLIMATE; ENSO; OSCILLATIONS; ANOMALIES; DYNAMICS; TRENDS AB Analysis of this century's sea surface temperatures over the Pacific Ocean reveals an interdecadal oscillation with a period of 15-20 years. Our results show that the well-known 1976-77 climate regime shift is not unique, but represents one of several phase transitions associated with this interdecadal oscillation, also found around 1924-25, 1941-42, and 1957-58. The oscillation's striking north-south symmetry the equator implies strong interactions between tropics ana extratropics. A mode with a period of approximately 70 years and an apparently different spatial pattern is also identified tentatively but has to be evaluated further using longer time series. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Los Angeles, CA 90095 USA. RP Chao, Y (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 32 TC 83 Z9 91 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 1 PY 2000 VL 27 IS 15 BP 2261 EP 2264 DI 10.1029/1999GL011324 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 341JL UT WOS:000088587200023 ER PT J AU Gross, RS AF Gross, RS TI The excitation of the Chandler wobble SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID POLAR MOTION; EARTHS WOBBLE; WATER STORAGE; ROTATION; ATMOSPHERE; OCEANS; WIND; CORE AB The Chandler wobble is an excited resonance of the Earth's rotation having a period of about 14 months. Although it has been under investigation for more than a century, its excitation mechanism has remained elusive. Here, the angular momentum of the atmosphere computed from the products of a numerical weather prediction analysis system and the angular momentum of the oceans computed from a global oceanic general circulation model driven by observed surface winds and fluxes are used to show that during 1985.0-1996.0 the Chandler wobble was excited by a combination of atmospheric and oceanic processes, with the dominant excitation mechanism being ocean-bottom pressure fluctuations. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gross, RS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 238-332, Pasadena, CA 91109 USA. NR 27 TC 89 Z9 94 U1 1 U2 15 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 AUG 1 PY 2000 VL 27 IS 15 BP 2329 EP 2332 DI 10.1029/2000GL011450 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 341JL UT WOS:000088587200040 ER PT J AU Cockell, CS Catling, DC Davis, WL Snook, K Kepner, RL Lee, P McKay, CP AF Cockell, CS Catling, DC Davis, WL Snook, K Kepner, RL Lee, P McKay, CP TI The ultraviolet environment of Mars: Biological implications past, present, and future SO ICARUS LA English DT Review DE atmospheres; evolution; exobiology; Mars; photochemistry; radiative transfer ID BACILLUS-SUBTILIS SPORES; EARTHS EARLY ATMOSPHERE; MARTIAN ATMOSPHERE; ACTION SPECTRA; UV-RADIATION; SPACE ENVIRONMENT; EVOLUTION; NM; OZONE; LIFE AB A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment, past and present, Biological action spectra for DNA inactivation and chloroplast (photosystem) inhibition are used to estimate biologically effective irradiances for the martian surface under cloudless skies, Over time Mars has probably experienced an increasingly inhospitable photobiological environment, with present instantaneous DNA weighted irradiances 3.5-fold higher than they may have been on early Mars, This is in contrast to the surface of Earth, which experienced an ozone amelioration of the photobiological environment during the Proterozoic and now has DNA weighted irradiances almost three orders of magnitude lower than early Earth, Although the present-day martian UV flux is similar to that of early Earth and thus may not be a critical limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer, Microbial strategies for protection against UV radiation are considered in the light of martian photobiological calculations, past and present, Data are also presented for the effects of hypothetical planetary atmospheric manipulations on the martian UV radiation environment with estimates of the biological consequences of such manipulations. (C) 2000 Academic Press. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. Desert Res Inst, Reno, NV 89512 USA. RP Cockell, CS (reprint author), NASA, Ames Res Ctr, M-S 239-20, Moffett Field, CA 94035 USA. RI Catling, David/D-2082-2009; OI Catling, David/0000-0001-5646-120X NR 105 TC 123 Z9 126 U1 4 U2 32 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 2000 VL 146 IS 2 BP 343 EP 359 DI 10.1006/icar.2000.6393 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 341NN UT WOS:000088596600003 PM 11543504 ER PT J AU Lopez-Valverde, MA Haberle, RM Lopez-Puertas, M AF Lopez-Valverde, MA Haberle, RM Lopez-Puertas, M TI Non-LTE radiative mesospheric study for Mars Pathfinder entry SO ICARUS LA English DT Article DE non-LTE CO2 atmospheric emissions; radiative transfer; Mars atmosphere; infrared energy balance; radiative relaxation rate ID NONLOCAL THERMODYNAMIC-EQUILIBRIUM; TERRESTRIAL PLANET THERMOSPHERES; INFRARED EMISSIONS; MARTIAN ATMOSPHERE; VIBRATIONAL LEVELS; TRANSFER MODEL; POPULATIONS AB Detailed calculations of thermal cooling and solar heating rates under nonlocal thermodynamic equilibrium (non-LTE) situations have been conducted in order to analyze the atmospheric structure measured by the ASI/MET instrument during the Mars Pathfinder entry into the martian atmosphere. A time-marching version of the non-LTE model of Lopez-Valverde and Lopez-Puertas (1994, J. Geophys. Res. 99, 13,093-13,115) has been developed and used to evaluate the diurnal forcing by the CO2 near-IR bands. Allowance is made for uncertainties in the abundance of atomic oxygen and the rate coefficient of collisional deactivation of CO2(nu(2)) by O(P-3). The results indicate that a mesosphere (60-120 km) in radiative equilibrium should experience a large daily temperature variation, with a maximum change over 30 K between 90 and 110 km, Radiative lifetimes and instantaneous damping rates of simulated disturbances produced by atmospheric waves are also computed throughout that region. These depend on the thermal structure and, therefore, follow a similar daily cycle in response to the solar heating of the martian mesosphere. Values of a couple of hours and less than an hour are typical between 80 and 105 km during nighttime and daytime, respectively, increasing downward as the optical thickness at 15 mu m increases. Above 90 km, radiative relaxation times do not decrease with height, in clear contrast to the LTE approximation. On the basis of these calculations we conclude that the different temperatures between Viking and Pathfinder could be explained by a radiatively driven martian mesosphere, especially in the upper part of this region (90-120 km). (C) 2000 Academic Press. C1 CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Lopez-Valverde, MA (reprint author), CSIC, Inst Astrofis Andalucia, Apdo 3004, E-18080 Granada, Spain. RI Lopez Puertas, Manuel/M-8219-2013; OI Lopez Puertas, Manuel/0000-0003-2941-7734; Lopez-Valverde, M. A./0000-0002-7989-4267 NR 13 TC 5 Z9 5 U1 0 U2 2 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 2000 VL 146 IS 2 BP 360 EP 365 DI 10.1006/icar.2000.6388 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 341NN UT WOS:000088596600004 ER PT J AU Korycansky, DG Zahnle, KJ Law, MMM AF Korycansky, DG Zahnle, KJ Law, MMM TI High-resolution calculations of asteroid impacts into the venusian atmosphere SO ICARUS LA English DT Article DE impact processes; cratering ID RAYLEIGH-TAYLOR INSTABILITY; 1908 TUNGUSKA EXPLOSION; COMET SHOEMAKER-LEVY-9; SHEAR-LAYER; JUPITER; FRAGMENTS; BREAKUP; CRATERS; MODELS; SIZE AB We present results from a number of 2D high-resolution hydrodynamical simulations of asteroids striking the atmosphere of Venus. These cover a wide range of impact parameters (velocity, size, and incidence angle), but the focus is on 2-3 km diameter asteroids, as these are responsible for most of the impact craters on Venus. Asteroids in this size range are disintegrated, ablated, and significantly decelerated by the atmosphere, yet they retain enough impetus to make large craters when they meet the surface. We find that smaller impacters (diameter <1-2 km) are better described by a "pancaking" model in which the impactor is compressed and distorted, while for larger impacters (>2-3 km) fragmentation by mechanical ablation is preferred. The pancaking model has been modified to take into account effects of hydrodynamical instabilities. The general observation that most larger impacters disintegrate by shedding fragments generated from hydrodynamic instabilities spurs us to develop a simple heuristic model of the mechanical ablation of fragments based on the growth rates of Rayleigh-Taylor instabilities. Although in principle the model has many free parameters, most of these have little effect provided that they are chosen reasonably. In practice the range of model behavior can be described with one free parameter. The resulting model reproduces the mass and momentum fluxes rather well, doing so with reasonable values of all physical parameters. (C) 2000 Academic Press. C1 Univ Calif Santa Cruz, Univ Calif Observ, Lick Observ, 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, Univ Calif Observ, Lick Observ, Santa Cruz, CA 95064 USA. NR 40 TC 22 Z9 22 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 2000 VL 146 IS 2 BP 387 EP 403 DI 10.1006/icar.2000.6426 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 341NN UT WOS:000088596600006 PM 11543505 ER PT J AU Supulver, KD Lin, DNC AF Supulver, KD Lin, DNC TI Formation of icy planetesimals in a turbulent solar nebula SO ICARUS LA English DT Article DE planetesimals; planetary formation; ices; solar nebula ID T-TAURI STARS; PROTOPLANETARY ACCRETION DISKS; GIANT PLANETS; DUST; GAS; CONDENSATION; EVOLUTION; GRAINS; CONSEQUENCES; AGGREGATION AB We have constructed a numerical simulation of the formation of water-ice planetesimals in the outer solar nebula which incorporates global turbulence, condensation and sublimation of H2O, and collisional accumulation. Global turbulence based on the Kolmogorov turbulence spectrum is imposed on a two-dimensional azimuthally symmetric laminar solar nebula model, In a single simulation, an individual particle of a given size and density is placed in the nebula on a Keplerian orbit; its orbit evolves due to gas drag forces while simultaneously its size changes due to both H2O condensation and sublimation and the accumulation of background H2O-ice particles as it sweeps through the nebula. With the inclusion of the gas-grain exchange and the grains' long-term orbital evolution over large radial and vertical ranges, our approach extends beyond previous investigations. Major results include: (1) Turbulence can concentrate small particles into preferred regions in the nebula and can prevent the rapid loss of such particles into the Sun. (2) The suspension of mm and sub-mm particles and the sedimentation of large particles in the direction normal to the disk plane may modify their reprocessing properties, opacity, and the spectral energy distribution, (3) Particles experience wide ranges of ambient conditions (e.g., temperature and density) as they are buffeted about the nebula by turbulence. They may undergo significant chemical and/or structural changes as a result. (4) For planetesimals to grow from smaller particles, collisional accumulation must be efficient and rapid. A high midplane concentration of icy particles strongly favors planetesimal growth from small grains in the giant planet region of the Solar System. (C) 2000 Academic Press. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Santa Cruz, Board Studies Astron & Astrophys, Santa Cruz, CA 95064 USA. RP Supulver, KD (reprint author), Malin Space Sci Syst, POB 910148, San Diego, CA 92191 USA. NR 63 TC 67 Z9 67 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 2000 VL 146 IS 2 BP 525 EP 540 DI 10.1006/icar.2000.6418 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 341NN UT WOS:000088596600016 ER PT J AU Wilson, K Enoch, M AF Wilson, K Enoch, M TI Optical communications for deep space missions SO IEEE COMMUNICATIONS MAGAZINE LA English DT Article AB The Jet Propulsion Laboratory has had a long interest in optical communications for use in deep space exploration missions. Lasercomm technology offers the promise of significant advantages over RF in terms of communication system performance, and spacecraft mass and power savings. This paper describes the activities at JPL to evaluate optical communication systems for use on deep space exploration spacecraft. C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Wilson, K (reprint author), Jet Prop Lab, Pasadena, CA 91109 USA. NR 18 TC 16 Z9 16 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 0163-6804 J9 IEEE COMMUN MAG JI IEEE Commun. Mag. PD AUG PY 2000 VL 38 IS 8 BP 134 EP 139 DI 10.1109/35.860864 PG 6 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 342HU UT WOS:000088639800013 ER PT J AU Ji, Y Yao, XS Maleki, L AF Ji, Y Yao, XS Maleki, L TI High-Q whispering gallery mode dielectric resonator bandpass filter with microstrip line coupling and photonic bandgap mode-suppression SO IEEE MICROWAVE AND GUIDED WAVE LETTERS LA English DT Article DE bandpass filter; dielectric resonator; mode suppression; photonic bandgap AB We describe a novel bandpass filter based on using Whispering Gallery (WG) modes in high-density dielectric resonators (DR), Microstrip line mode-coupling and photonic bandgap (PBG) suppression techniques are also features of this design. Based on this approach, we demonstrate a filter with center frequency of 13.7 GHz, Q of 2000, insertion loss of 7 dB, and attenuation of 30 dB. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ji, Y (reprint author), Santec USA, Hackensack, NJ 07601 USA. NR 9 TC 12 Z9 12 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1051-8207 J9 IEEE MICROW GUIDED W JI IEEE Microw. Guided Wave Lett. PD AUG PY 2000 VL 10 IS 8 BP 310 EP 312 DI 10.1109/75.862224 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA 346AB UT WOS:000088847000004 ER PT J AU Christodoulou, CG Wahid, PF Mahbub, MR Bailey, MC AF Christodoulou, CG Wahid, PF Mahbub, MR Bailey, MC TI Design of a minimum-loss series-fed foldable microstrip SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Letter DE microstrip arrays; spacecraft antennas AB The design and analysis of a series-fed, low-loss, inverted microstrip array antenna, operating at 1.413 GHz is presented, Thr array antenna is composed of two subarrays consisting of an equal number of microstrip patches connected together through a series microstrip line. The subarrays are coaxially fed 180 degrees out of phase, This approach ensures a symmetric radiation pattern. The design approach for obtaining: a low sidelobe ratio and a low loss microstrip array Is accomplished using the IE3D code. Experimental and simulated data are presented and discussed. C1 Univ New Mexico, Dept Elect & Comp Engn, Albuquerque, NM 87131 USA. Univ Cent Florida, Dept Elect & Comp Engn, Orlando, FL 32816 USA. Harris Corp, Quincy, IL 62305 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Christodoulou, CG (reprint author), Univ New Mexico, Dept Elect & Comp Engn, Albuquerque, NM 87131 USA. NR 6 TC 2 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD AUG PY 2000 VL 48 IS 8 BP 1264 EP 1267 PG 4 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 374FY UT WOS:000165336200019 ER PT J AU Pogorzelski, RJ Scaramastra, RP Huang, J Beckon, RJ Petree, SM Chavez, CM AF Pogorzelski, RJ Scaramastra, RP Huang, J Beckon, RJ Petree, SM Chavez, CM TI A seven-element S-band coupled-oscillator controlled agile-beam phased array SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article DE coupled oscillators; injection locking; phased arrays AB This paper describes the design, fabrication, and testing of a seven-element S-band phased array, in which the beam is steered by means of a coupled-oscillator technique. Seven monolithic-microwave integrated-circuit-based voltage-controlled oscillators were coupled via microstrip transmission lines in such a manner that they mutually injection locked and, thus, oscillated as an ensemble. The output of each oscillator was connected to a microstrip patch array element and the seven elements were disposed in a line on a Duroid substrate. The resulting antenna was characterized in benchtop tests, revealing the relative phase behavior of the oscillators, and in range tests, producing far-field pattern cuts. Patterns showing beams steered to several angles were obtained by applying appropriate tuning voltages to the end oscillators of the array. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Pogorzelski, RJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 21 Z9 23 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 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD AUG PY 2000 VL 48 IS 8 BP 1375 EP 1384 DI 10.1109/22.859483 PG 10 WC Engineering, Electrical & Electronic SC Engineering GA 343TM UT WOS:000088717800012 ER PT J AU Pogorzelski, RJ Maccarini, PF York, RA AF Pogorzelski, RJ Maccarini, PF York, RA TI A continuum model of the dynamics of coupled oscillator arrays for phase-shifterless beam scanning (vol 47, pg 463, 1999) SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Correction C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Santa Barbara, Dept Elect & Comp Engn, Santa Barbara, CA 93106 USA. RP Pogorzelski, RJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD AUG PY 2000 VL 48 IS 8 BP 1422 EP 1422 PG 1 WC Engineering, Electrical & Electronic SC Engineering GA 343TM UT WOS:000088717800021 ER PT J AU Pogorzelski, RJ Maccarini, PF York, RA AF Pogorzelski, RJ Maccarini, PF York, RA TI Continuum modeling of the dynamics of externally injection-locked coupled oscillator arrays (vol 47, pg 471, 1999) SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Correction C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Santa Barbara, Dept Elect & Comp Engn, Santa Barbara, CA 93106 USA. RP Pogorzelski, RJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD AUG PY 2000 VL 48 IS 8 BP 1422 EP 1422 PG 1 WC Engineering, Electrical & Electronic SC Engineering GA 343TM UT WOS:000088717800022 ER PT J AU Cook, WR Boggs, SE Bolotnikov, AE Burnham, JA Fitzsimmons, MJ Harrison, FA Kecman, B Matthews, B Schindler, SM AF Cook, WR Boggs, SE Bolotnikov, AE Burnham, JA Fitzsimmons, MJ Harrison, FA Kecman, B Matthews, B Schindler, SM TI High resolution CdZnTe pixel detectors with VLSI readout SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT Nuclear Science Symposium (NSS) CY OCT 26-28, 1999 CL SEATTLE, WASHINGTON AB CdZnTe pixel detectors with a custom VLSI readout, are being developed at Caltech/JPL for use in focusing hard X-ray telescopes. We have recently tested several prototype detector assemblies, each consisting of a 2 mm thick CdZnTe pixel detector indium bump bonded to our VLSI readout chip. A complete pulse height analysis chain is located directly below each 680 by 650 mu m pixel and includes a preamplifier, shaping amplifiers, and a peak stretcher/discriminator. Here we report on the first fully functional operation of these detector/VLSI hybrids. Using an Am-241 source, collimated to illuminate a single pixel, excellent energy resolution of 670 eV FWHM was measured for the 59.5 keV line at -10C, with electronic noise of only 340 eV FWHM. Illumination with an uncollimated Am-241 source was performed to assess the uniformity of pixel response and to exercise the readout chip's ability to process multiple pixel events arising from X-rays interacting above pixel boundaries. The imaging capability of the detector was demonstrated using a tungsten slit mask. C1 CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Cook, WR (reprint author), CALTECH, Pasadena, CA 91125 USA. RI Boggs, Steven/E-4170-2015 OI Boggs, Steven/0000-0001-9567-4224 NR 4 TC 8 Z9 8 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD AUG PY 2000 VL 47 IS 4 BP 1454 EP 1457 DI 10.1109/23.872995 PN 1 PG 4 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 358UU UT WOS:000089576200030 ER PT J AU Latorella, KA Prabhu, PV AF Latorella, KA Prabhu, PV TI A review of human error in aviation maintenance and inspection SO INTERNATIONAL JOURNAL OF INDUSTRIAL ERGONOMICS LA English DT Article DE aviation; maintenance; inspection; human factors; human error ID HUMAN RELIABILITY ASSESSMENT; IDENTIFICATION; DESIGN AB Aviation safety depends on minimizing error in all facets of the system. While the role of flightdeck human error has received much emphasis, recently more attention has been directed toward reducing human error in maintenance and inspection. Aviation maintenance and inspection tasks are part of a complex organization, where individuals perform varied tasks in an environment with time pressures, sparse feedback, and sometimes difficult ambient conditions. These situational characteristics, in combination with generic human erring tendencies, result in varied forms of error. The most severe result in accidents and loss of life. For example, failure to replace horizontal stabilizer screws on a Continental Express aircraft resulted in in-flight leading-edge separation and 14 fatalities. While errors resulting in accidents are most salient, maintenance and inspection errors have other important consequences (e.g., air turn-backs, delays in aircraft availability, gate returns, diversions to alternate airports) which impede productivity and efficiency of airline operations, and inconvenience the flying public. This paper reviews current approaches to identifying, reporting, and managing human error in aviation maintenance and inspection. As foundation for this discussion, we provide an overview of approaches to investigating human error, and a description of aviation maintenance and inspection tasks and environmental characteristics. Relevance to industry Following an introductory description of its tasks and environmental characteristics, this paper reviews methods and tools for identifying, reporting, and managing human error in aviation maintenance and inspection. (C) 2000 Elsevier Science B.V. All rights reserved. C1 SUNY Buffalo, Dept Ind Engn, Buffalo, NY 14260 USA. Galaxy Sci Corp, Atlanta, GA 30345 USA. RP Latorella, KA (reprint author), NASA, Langley Res Ctr, Vehicle Integrat Branch, MS 152, Hampton, VA 23681 USA. EM k.a.latorella@larc.nasa.gov NR 95 TC 40 Z9 42 U1 5 U2 31 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-8141 J9 INT J IND ERGONOM JI Int. J. Ind. Ergon. PD AUG PY 2000 VL 26 IS 2 BP 133 EP 161 DI 10.1016/S0169-8141(99)00063-3 PG 29 WC Engineering, Industrial; Ergonomics SC Engineering GA 337DX UT WOS:000088343100002 ER PT J AU Hofton, MA Blair, JB Minster, JB Ridgway, JR Williams, NP Bufton, JL Rabine, DL AF Hofton, MA Blair, JB Minster, JB Ridgway, JR Williams, NP Bufton, JL Rabine, DL TI An airborne scanning laser altimetry survey of Long Valley, California SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID EASTERN CALIFORNIA; CALDERA; INFLATION AB Between 28 September and 7 October 1995, we conducted an airborne laser altimetry experiment over the Long Valley caldera, California, in which each of two scanning laser altimeters (dubbed SLICER and RASCAL) were ? own in a NASA T-39 jet aircraft. Operating concurrently were a Global Positioning System( GPS) guidance system and dual frequency receivers for precise navigation and post-flight calculation of the airplane trajectory relative to a ground station, and an inertial navigation system (INS) for attitude determination. Reduction of raw laser ranges requires merging the differential kinematic GPS aircraft trajectory and the INS data with the laser data, and determination of the atmospheric delay. Data geolocation consists of obtaining the centre location and the mean elevation within each footprint in a geodetic coordinate system. The elevation of Crowley Lake is recovered to an accuracy of similar to 3 cm or better from 3 km above ground level and crossover analysis indicates that the elevation estimates are consistent from pass to pass. We test our geolocation procedures by comparing laser-derived elevations with those determined in situ for recognizable ground features. A comparison of laser and GPS-derived positions shows that the horizontal accuracy is better than the diameter of the footprint and vertical accuracy is within the error inherent in the range measurement. A comparison of SLICER elevation data with digital elevation models (DEMs) of the region shows that the DEM data provides surface topography to within stated accuracy limits. Although research continues to utilize the full potential of laser altimetry data, our results constitute a successful demonstration that the technique may be used to perform geodetic monitoring of surface topographic changes. C1 Scripps Inst Oceanog, Cecil H & Ida M Green Inst Geophys & Planetary Ph, La Jolla, CA 92093 USA. NASA, Goddard Space Flight Ctr, Laser Remote Sensing Branch 924, Terr Phys Lab, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Lab Terr Phys 920, Greenbelt, MD 20771 USA. RP Hofton, MA (reprint author), Scripps Inst Oceanog, Cecil H & Ida M Green Inst Geophys & Planetary Ph, La Jolla, CA 92093 USA. RI Namikawa, Laercio/C-5559-2013; Rabine, David/C-9626-2013; Blair, James/D-3881-2013; Beckley, Matthew/D-4547-2013; OI Namikawa, Laercio/0000-0001-7847-1804; Minster, Jean Bernard/0000-0003-1268-5177 NR 26 TC 32 Z9 35 U1 1 U2 4 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD AUG PY 2000 VL 21 IS 12 BP 2413 EP 2437 DI 10.1080/01431160050030547 PG 25 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 341AR UT WOS:000088569300006 ER PT J AU Menzies, T Althoff, KD Kalfoglou, Y Motta, E AF Menzies, T Althoff, KD Kalfoglou, Y Motta, E TI Issues with meta-knowledge SO INTERNATIONAL JOURNAL OF SOFTWARE ENGINEERING AND KNOWLEDGE ENGINEERING LA English DT Article; Proceedings Paper CT 11th International Conference on Software Engineering and Knowledge Engineering (SEKE 99) CY JUN 16-19, 1999 CL KAISERSLAUTERN, GERMANY DE problem solving methods; ontologies; reuse; knowledge engineering; evaluation ID ACQUISITION; SYSTEMS AB At the SEKE'99 conference, knowledge engineering researchers held a panel on the merits of meta-knowledge (i.e. problem solving methods and ontologies) for the development of knowledge-based systems. The original panel was framed as a debate on the merits of meta-knowledge for knowledge maintenance [21]. However, the debate quickly expanded. In the end, we were really discussing the merits of different technologies for the specification of reusable components for KBS. In this brief article we record some of the lively debate from that panel and the email exchanges it generated. Keywords: Problem solving methods, ontologies, reuse, knowledge engineering, evaluation. C1 W Virginia Univ, NASA, Software Res Lab, Fairmont, WV 26554 USA. Fraunhofer Inst Expt Software Engn, Kaiserslautern, Germany. Univ Edinburgh, Inst Representat & Reasoning, Edinburgh EH8 9YL, Midlothian, Scotland. Open Univ, Knowledge Media Inst, Milton Keynes MK7 6AA, Bucks, England. OI Motta, Enrico/0000-0003-0015-1952 NR 34 TC 1 Z9 1 U1 0 U2 1 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA JOURNAL DEPT PO BOX 128 FARRER ROAD, SINGAPORE 912805, SINGAPORE SN 0218-1940 J9 INT J SOFTW ENG KNOW JI Int. J. Softw. Eng. Knowl. Eng. PD AUG PY 2000 VL 10 IS 4 BP 549 EP 555 DI 10.1142/S0218194000000262 PG 7 WC Computer Science, Artificial Intelligence; Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 370CU UT WOS:000165106000011 ER PT J AU Zak, M AF Zak, M TI Dynamics of intelligent systems SO INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS LA English DT Article AB Recent advances in nonlinear dynamics demonstrate a remarkable complexity of patterns outside of equilibrium, which are derived from simple basic laws of physics. A class of mathematical models has been identified providing a variety of such patterns in the form of static, periodic, or chaotic attractors. These models appear to be so general that they predict not only physical, but also biological, economic, and social patterns of behavior. Such a phenomenological reductionism may suggest that, on the dynamical level of description, there is no difference between a solar system, a swarm of insects, and a stock market. However, this conclusion is wrong for a very simple reason: Even primitive living species possess additional non-Newtonian properties which are not included in the laws of Newtonian or statistical mechanics. These properties follow from a privileged ability of living species to possess a self-image (a concept introduced in mathematical psychology). In this paper we consider the existence of a self-image as a postulate to be added to classical physics for modeling behavior of living systems. We show that self-image can be incorporated into the mathematical formalism of a nonlinear dynamics which evolves in probability space. We demonstrate that one of the basic invariants of living systems is their ability to predict the future, which is associated with intelligence. C1 CALTECH, Jet Prop Lab, Ultracomp Grp, Pasadena, CA 91109 USA. RP Zak, M (reprint author), CALTECH, Jet Prop Lab, Ultracomp Grp, M-S 126-347, Pasadena, CA 91109 USA. NR 13 TC 9 Z9 9 U1 0 U2 0 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0020-7748 J9 INT J THEOR PHYS JI Int. J. Theor. Phys. PD AUG PY 2000 VL 39 IS 8 BP 2107 EP 2140 DI 10.1023/A:1003622107129 PG 34 WC Physics, Multidisciplinary SC Physics GA 373FW UT WOS:000165278600015 ER PT J AU Banks, HT Joyner, ML Wincheski, B Winfree, WP AF Banks, HT Joyner, ML Wincheski, B Winfree, WP TI Nondestructive evaluation using a reduced-order computational methodology SO INVERSE PROBLEMS LA English DT Article ID PROPER ORTHOGONAL DECOMPOSITION; FLAW DETECTION; PROBE AB This paper uses eddy current based techniques and reduced-order modelling to explore the feasibility of detecting subsurface damage in structures such as air foils and pipelines. To identify the Geometry of the damage, an optimization algorithm is employed which requires solving the forward problem numerous times. To implement these methods in a practical setting, the forward algorithm must be solved with extremely fast and accurate solution methods. Therefore, our computational methods art: based on the reduced-order Karhunen-Loeve or proper orthogonal decomposition techniques. For proof of concept, we implement the methodology on a 2D problem and find the methods to be efficient and robust even with data containing 10% relative noise. Furthermore, the methods are fast: our findings suggest we can reduce the computational time on average by a factor of 3000. C1 N Carolina State Univ, Ctr Res Sci Computat, Raleigh, NC 27695 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Banks, HT (reprint author), N Carolina State Univ, Ctr Res Sci Computat, Raleigh, NC 27695 USA. NR 35 TC 22 Z9 22 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0266-5611 J9 INVERSE PROBL JI Inverse Probl. PD AUG PY 2000 VL 16 IS 4 BP 929 EP 945 DI 10.1088/0266-5611/16/4/304 PG 17 WC Mathematics, Applied; Physics, Mathematical SC Mathematics; Physics GA 349UM UT WOS:000089064000006 ER PT J AU Lovelac, J Snell, EH Pokross, M Arvai, AS Nielsen, C Xuong, NH Bellamy, HD Borgstahl, GEO AF Lovelac, J Snell, EH Pokross, M Arvai, AS Nielsen, C Xuong, NH Bellamy, HD Borgstahl, GEO TI BEAM-ish: a graphical user interface for the physical characterization of macro-molecular crystals SO JOURNAL OF APPLIED CRYSTALLOGRAPHY LA English DT Software Review DE graphical user interface; macromolecules; protein crystals; mosaicity; crystal quality; fine phi slicing; X-ray diffraction ID PROTEIN CRYSTAL C1 Univ Toledo, Dept Chem, Toledo, OH 43606 USA. NASA, George C Marshall Space Flight Ctr, Lab Struct Biol, Huntsville, AL 35812 USA. Area Detector Syst Corp, Poway, CA 92064 USA. Univ Calif San Diego, Dept Chem, San Diego, CA 92093 USA. Stanford Synchrotron Radiat Lab, Stanford, CA 94309 USA. RP Borgstahl, GEO (reprint author), Univ Toledo, Dept Chem, 2801 W Bancroft St, Toledo, OH 43606 USA. EM gborgst@uoft02.utoledo.edu FU NASA [NAG8-1380] FX This work was funded by NASA grant NAG8-1380. NR 5 TC 12 Z9 12 U1 0 U2 0 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 0021-8898 J9 J APPL CRYSTALLOGR JI J. Appl. Crystallogr. PD AUG 1 PY 2000 VL 33 BP 1187 EP 1188 DI 10.1107/S0021889800005732 PN 4 PG 2 WC Chemistry, Multidisciplinary; Crystallography SC Chemistry; Crystallography GA 337LR UT WOS:000088363000030 ER PT J AU Boda, WL Watenpaugh, DE Ballard, RE Hargens, AR AF Boda, WL Watenpaugh, DE Ballard, RE Hargens, AR TI Supine lower body negative pressure exercise simulates metabolic and kinetic features of upright exercise SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE gait; ground reaction force; oxygen consumption; spaceflight; microgravity ID LOCOMOTION; MICROGRAVITY; GRAVITY; SPACE AB Exercise within an artificial gravity environment may help prevent microgravity-induced deconditioning. We hypothesized that supine lower body negative pressure (LBNP) exercise simulates physiological and biomechanical features of upright exercise. Walking (4.5 +/- 0.3 km/h) and running (8.0 +/- 1.0 km/h) while supine within a LBNP exerciser were compared with walking and running while upright. Eight healthy subjects exercised for 5 min at each of the four posture/gait conditions. LBNP of 52 +/- 4 mmHg generated one body weight of supine ground reaction force (GRF). Gait parameters and GRFs were measured during the third minute of exercise, and heart rate and oxygen consumption were measured during the fifth minute. Oxygen consumption during supine LBNP treadmill exercise [walking: 14.6 +/- 0.9; running: 32.2 +/- 1.6 (SE) ml.min(-1).kg(-1)] was similar to that during upright treadmill exercise (walking: 15.1 +/- 0.9; running: 34.0 +/- 1.9 ml.min(-1).kg(-1)). Heart rate for supine LBNP exercise (grand mean: 133 +/- 11 beats/min) was also similar to that for upright exercise (136 +/- 11 beats/min). Footward forces integrated over each stride (330.5 +/- 34.4 vs. 319.1 +/- 29.6 N . s) and rate of force generation (26,483 +/- 4,310 vs. 25,634 +/- 4,434 N/s) were similar for upright and LBNP exercise, respectively. Our collective results indicate that supine exercise within LBNP can simulate the physiological stress and GRFs that are generated during upright gait. C1 Sonoma State Univ, Dept Kinesiol, Rohnert Park, CA 94928 USA. NASA, Ames Res Ctr, Gravitat Res Branch, Moffett Field, CA 94035 USA. RP Boda, WL (reprint author), Sonoma State Univ, Dept Kinesiol, 1801 E Cotati, Rohnert Park, CA 94928 USA. NR 31 TC 22 Z9 22 U1 0 U2 2 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 AUG PY 2000 VL 89 IS 2 BP 649 EP 654 PG 6 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 347LD UT WOS:000088930200035 PM 10926650 ER PT J AU Clarke, MSF Vanderburg, CR Bamman, MM Caldwell, RW Feeback, DL AF Clarke, MSF Vanderburg, CR Bamman, MM Caldwell, RW Feeback, DL TI In situ localization of cholesterol in skeletal muscle by use of a monoclonal antibody SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE immunolocalization; sarcoplasmic reticulum ID SARCOPLASMIC-RETICULUM; INTRACELLULAR CALCIUM; BIOLOGICAL-MEMBRANES; INSULIN-RESISTANCE; CARDIAC-MUSCLE; CELL-MEMBRANE; GROWTH-FACTOR; BINDING; CHANNEL; SARCOLEMMA AB A common perception is that cholesterol, the major structural lipid found in mammalian membranes, is localized nearly exclusively to the plasma membrane of living cells and that it is found in much smaller quantities in internal membranes. This perception is based almost exclusively on cell fractionation studies, in which density gradient centrifugation is used for purification of discrete subcellular membrane fractions. Here we describe a monoclonal antibody, MAb 2C5-6, previously reported to detect purified cholesterol in synthetic membranes (Swartz GM Jr, Gentry MK, Amende LM, Blanchette-Mackie EJ, and Alving CR. Proc Natl Acad Sci USA 85: 1902-1906, 1988), that is capable of detecting cholesterol in situ in the membranes of skeletal muscle sections. Localization of cholesterol, the dihydropyridine receptor of the T tubule, and the Ca2+-ATPase of the sarcoplasmic reticulum (SERCA2) by means of double and triple immunostaining protocols clearly demonstrates that cholesterol is primarily localized to the sarcoplasmic reticulum membranes of skeletal muscle rather than the sarcolemmal or T tubule membranes. The availability of this reagent and its ability to spatially localize cholesterol in situ may provide a greater understanding of the relationship between membrane cholesterol content and transmembrane signaling in skeletal muscle. C1 Univ Space Res Assoc, Div Space Life Sci, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. Massachusetts Gen Hosp, Res Space Management Grp, Boston, MA 02114 USA. Univ Alabama, Div Exercise Physiol, Birmingham, AL 35294 USA. Med Coll Georgia, Dept Pharmacol & Toxicol, Augusta, GA 30912 USA. RP Clarke, MSF (reprint author), Univ Space Res Assoc, Div Space Life Sci, 3600 Bay Area Blvd, Houston, TX 77058 USA. NR 46 TC 5 Z9 5 U1 0 U2 2 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 AUG PY 2000 VL 89 IS 2 BP 731 EP 741 PG 11 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 347LD UT WOS:000088930200045 PM 10926660 ER PT J AU Ronca, AE Alberts, JR AF Ronca, AE Alberts, JR TI Effects of spaceflight during pregnancy on labor and birth at 1 G SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE parturition; microgravity; uterus; abdominal muscle; fetus; newborn; rat ID MUSCLES AB The events of parturition (labor, delivery, maternal care, placentophagia, and onset of nursing) were analyzed in female Norway rats (Rattus norvegicus) flown on either 11- or 9-day-long spaceflights beginning at the approximate midpoint of their pregnancies. Each space shuttle flight landed on the 20th day of the rats' pregnancies, just 48-72 h before parturition. After spaceflight, dams were continuously monitored and recorded by time-lapse videography throughout the completion of parturition and onset of nursing (days 22 and 23). Analyses of parturition revealed that, compared with ground controls, flight darns displayed twice the number of lordosis contractions, the predominant labor contraction type in rats. The number of vertical contractions (those that immediately precede expulsion of a pup from the womb), the duration of labor, fetal wastage, number of neonates born, neonatal birth weights, placentophagia, and maternal care during parturition, including the onset of nursing, were comparable in flight and ground control dams. Our findings indicate that, with the exception of labor contractions, mammalian pregnancy and parturition remain qualitatively and quantitatively intact after spaceflight during pregnancy. C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. Indiana Univ, Dept Psychol, Bloomington, IN 47405 USA. RP Ronca, AE (reprint author), NASA, Ames Res Ctr, Div Life Sci, Bldg 261,Rm 111, Moffett Field, CA 94035 USA. FU NIMH NIH HHS [MH-28355, MH-46485] NR 16 TC 17 Z9 17 U1 0 U2 1 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 AUG PY 2000 VL 89 IS 2 BP 849 EP 854 PG 6 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 347LD UT WOS:000088930200058 PM 10926673 ER PT J AU Ritter, JM Voss, KJ AF Ritter, JM Voss, KJ TI A new instrument for measurement of the solar aureole radiance distribution from unstable platforms SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID SKY RADIANCE; CALIBRATION; SIMULATIONS; RETRIEVAL; AEROSOLS; ALBEDO AB A novel imaging solar aureole radiometer, which can obtain absolute radiometric measurements of the solar aureole when operated on an unstable platform, is described. A CCD array is used to image the aureole, while a neutral density occulter on a long pole blocks the direct solar radiation. This ensures accurate direction registration as the sun appears in acquired images, and the total circumsolar region is measured simultaneously. The imaging nature of this instrument along with a special triggering device permit acquisition of the circumsolar sky radiance within 7.5 degrees of the center of the solar disk. and within 1 degrees of the edge of the solar disk. This innovation makes possible. for the first time, reliable and accurate radiometric measurements of the solar aureole from unstable mobile platforms such as ships. This allows determination of the small angle atmospheric light scattering. The instrument has been used in held studies of atmospheric aerosols and will he used in satellite validation and calibration campaigns. C1 Univ Miami, Dept Phys, Coral Gables, FL 33124 USA. RP Ritter, JM (reprint author), NASA, George C Marshall Space Flight Ctr, Space Opt Mfg Technol Ctr, SD 71, Huntsville, AL 35812 USA. RI Voss, Kenneth /A-5328-2013 OI Voss, Kenneth /0000-0002-7860-5080 NR 15 TC 2 Z9 2 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 AUG PY 2000 VL 17 IS 8 BP 1040 EP 1047 DI 10.1175/1520-0426(2000)017<1040:ANIFMO>2.0.CO;2 PG 8 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 353GN UT WOS:000089266600003 ER PT J AU Early, EA Barnes, PY Johnson, BC Butler, JJ Bruegge, CJ Biggar, SF Spyak, PR Pavlov, MM AF Early, EA Barnes, PY Johnson, BC Butler, JJ Bruegge, CJ Biggar, SF Spyak, PR Pavlov, MM TI Bidirectional reflectance round-robin in support of the Earth Observing System program SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID CALIBRATION; EOS AB Laboratory measurements of the bidirectional reflectance distribution function (BRDF) of diffuse reflectors are required to support calibration in the Earth Observing System (EOS) program of the National Aeronautics and Space Administration. To assess the ability of the instrument calibration laboratories to perform accurate BRDF measurements, a round-robin with the National Institute of Standards and Technology (NIST) as the central laboratory was initiated by the EOS Project Science Office. The round-robin parameters include sample type, wavelength, and incident and viewing angles. The results show that the participating calibration laboratories are, with a few exceptions due to experimental techniques or sample properties, generally able to measure BRDF for the round-robin parameters to within 2% of the values measured by NIST. C1 Natl Inst Stand & Technol, Opt Technol Div, Gaithersburg, MD 20899 USA. NASA, Goddard Space Flight Ctr, Space Geodesy Networks, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Sensor Calibrat Off, Greenbelt, MD 20771 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. Univ Arizona, Ctr Opt Sci, Remote Sensing Grp, Tucson, AZ 85721 USA. Raytheon Santa Barbara Remote Sensing, Goleta, CA USA. Calif State Polytech Univ Pomona, Dept Chem, Pomona, CA 91768 USA. Swales Aerosp, Beltsville, MD USA. RP Early, EA (reprint author), Natl Inst Stand & Technol, Opt Technol Div, 100 Bur Dr,Stop 8442, Gaithersburg, MD 20899 USA. RI Butler, James/D-4188-2013 NR 22 TC 40 Z9 41 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 AUG PY 2000 VL 17 IS 8 BP 1077 EP 1091 DI 10.1175/1520-0426(2000)017<1077:BRRRIS>2.0.CO;2 PG 15 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 353GN UT WOS:000089266600007 ER PT J AU Liu, YG Su, MY Yan, XH Liu, WT AF Liu, YG Su, MY Yan, XH Liu, WT TI The mean-square slope of ocean surface waves and its effects on radar backscatter SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID WIND-GENERATED WAVES; GRAVITY-CAPILLARY WAVES; MICROWAVE BACKSCATTER; NUMBER SPECTRA; BOUNDARY-LAYER; ALTIMETER WIND; WATER-WAVES; SPEED; GROWTH; SCATTEROMETER AB The mean-square slope (MSS) of the sea surface for upwind and crosswind is derived, based on Phillips' equilibrium spectrum and the model herein on gravity-capillary wave spectrum. The MSS integrated from the above two spectra over high-frequency dissipation length (1 mm) firs the optical observations very well. The radar backscatter cross section (RBCS), calculated from specular reflection theory using the Ku-band filtered MSS, is in keeping with the empirically based Ku-band models by Brown for the GEOS-3 13.9-GHz altimeter, and by Witter and Chelton for the Geosat 13.5-GHz altimeter. Also, the RBCS, calculated using the C-band filtered MSS, is in keeping with the ERS-1/-2 scatterometer empirically based algorithms CMOD3 and CMOD4. The physics included in this model on gravity-capillary wave spectrum is also illustrated. The short-wave dissipation due to wave-drift interactions has the effect of suppressing the spectral density at high wind condition, which further influences the directional spreading rate. This effect can be denoted by c(2)/U(10)(2) or c(2)/c(p)(2) dependence of short-wave spectrum. It is suggested that the k(rho)/k dependence observed in the range of gravity waves should nor be extended to the region of short waves. The parasitic capillary wave dissipation due to molecular viscosity can he balanced by the energy supply from the underlying waves, hence it is removed from the model. The eddy viscosity is due to turbulence at the wind-drift layer, which suppresses the spectrum of high-frequency waves with wavelengths on the order of millimeters. C1 USN, Div Oceanog, Res Lab, Stennis Space Ctr, MS 39529 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. Univ Delaware, Coll Marine Studies, Newark, DE 19716 USA. RP Liu, YG (reprint author), Univ Delaware, Coll Marine Studies, Newark, DE 19716 USA. EM yuguang@newark.cms.udel.edu NR 57 TC 25 Z9 31 U1 1 U2 6 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 AUG PY 2000 VL 17 IS 8 BP 1092 EP 1105 DI 10.1175/1520-0426(2000)017<1092:TMSSOO>2.0.CO;2 PG 14 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 353GN UT WOS:000089266600008 ER PT J AU Polito, PS Liu, WT Tang, WQ AF Polito, PS Liu, WT Tang, WQ TI Correlation-based interpolation of NSCAT wind data SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID SCATTEROMETER AB Daily NASA Scatterometer (NSCAT) wind estimates cover about 75% of the globe. The remaining data gaps, which require interpolation, are regularly distributed in space and time. The development of this interpolation algorithm was guided by a balance between the smoothness of the end product and its fidelity to the original data. Three-dimensional matrices of autocorrelation coefficients Incorporate information about the dominant propagation pattern into the interpolation program. These coefficients are continuously updated in space and time and are used as weights to interpolate each point in a regular space-time grid. For the first step, European Centre for Medium-Range Weather Forecasts (ECMWF) wind data are used to simulate the NSCAT data distribution and interpolated using two different methods: one uses a single set of coefficients from a prescribed function based on the average decorrelation stales, and the other uses the Locally estimated autocorrelation coefficients. The comparison of these results with the original ECMWF maps favors those based on the auto-correlation. For the second step, daily maps of bin-averaged NSCAT wind data are compared to those interpolated by the correlation-based method and to those interpolated by successive corrections. Average differences between the original and Interpolated fields are presented for the areas covered by the swath and for the gaps. The two-dimensional wavenumber spectra are also compared. The correlation-based interpolation method retains relatively more small-scale signal while significantly reducing the swath signature. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Polito, PS (reprint author), CALTECH, Jet Prop Lab, MS 300-323,4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM polito@pacific.jpl.nasa.gov RI Polito, Paulo/F-3040-2013 OI Polito, Paulo/0000-0003-2217-3853 NR 5 TC 4 Z9 4 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0739-0572 EI 1520-0426 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD AUG PY 2000 VL 17 IS 8 BP 1128 EP 1138 DI 10.1175/1520-0426(2000)017<1128:CBIONW>2.0.CO;2 PG 11 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 353GN UT WOS:000089266600011 ER PT J AU Banerjee, RK Back, LH Back, MR Cho, YI AF Banerjee, RK Back, LH Back, MR Cho, YI TI Physiological flow simulation in residual human stenoses after coronary angioplasty SO JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID RATE-PRESSURE-DROP; ARTERIAL STENOSES; PULSATILE FLOW; SHEAR-STRESS; STEADY FLOW; BLOOD-FLOW; GUIDE-WIRE; CATHETER; VELOCITY; MODELS AB To evaluate the local hemodynamic implications of coronary artery balloon angioplasty computational fluid dynamics (CFD) was applied in a group Of patients previously reported by [Wilson et al. (1988), 77, pp. 873-885] with representative stenosis geometry post-angioplasty and with measured values of coronary flow reserve returning to a normal range (3.6+/-0.3). During undisturbed flow in the absence of diagnostic catheter sensors within the lesions the computed mean pressure drop Delta(p) over tilde was only about 1 mmHg at basal flow and increased moderately to about 8 mmHg for hyperemic flow. Corresponding elevated levels of mean wall shear stress in the midthroat region of the residual stenoses, which are common after angioplasty procedures, increased from about 60 to 290 dynes/cm(2) during hyperemia. The computations ((R) over bare(e) similar or equal to 100-400; alpha (e) = 2.25) indicated that the pulsatile flow field was principally quasi-steady during the cardiac cycle but there was phase lag in the pressure drop-mean velocity (Deltap - (u) over bar) relation. Time-averaged pressure drop values, Delta(p) over tilde, were about 20 percent higher than calculated pressure drop values, Deltap(s), for steady flow, similar to previous in vitro measurements by Cho et al. (1983). In the throat region, viscous effects were confined to the near-wall region and entrance effects were evident during the cardiac cycle. Proximal to the lesion, velocity profiles deviated from parabolic shape at lower velocities during the cardiac cycle. The flow field was very complex in the oscillatory separated flow reattachment region in the distal vessel where pressure recovery occurred These results may also serve as a useful reference against catheter-measured pressure drops and velocity ratios (hemodynamic endpoints) and arteriographic (anatomic) endpoints post-angioplasty. Some comparisons to previous studies of flow through stenoses models are also shown for perspective purposes. [S0148-0731(00)00304-6]. C1 NIH, Bioengn & Phys Sci Program, Bethesda, MD 20892 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ S Florida, Coll Med, Div Vasc Surg, Tampa, FL 33606 USA. Drexel Univ, Dept Mech Engn & Mech, Philadelphia, PA 19104 USA. RP Banerjee, RK (reprint author), NIH, Bioengn & Phys Sci Program, Bldg 3,Rm 3N17, Bethesda, MD 20892 USA. NR 35 TC 24 Z9 27 U1 0 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0148-0731 J9 J BIOMECH ENG-T ASME JI J. Biomech. Eng.-Trans. ASME PD AUG PY 2000 VL 122 IS 4 BP 310 EP 320 DI 10.1115/1.1287157 PG 11 WC Biophysics; Engineering, Biomedical SC Biophysics; Engineering GA 404QC UT WOS:000167111100003 PM 11036553 ER PT J AU Curtis, S Adler, R AF Curtis, S Adler, R TI ENSO indices based on patterns of satellite-derived precipitation SO JOURNAL OF CLIMATE LA English DT Article ID VERTICAL STRUCTURE INFORMATION; PASSIVE MICROWAVE TECHNIQUE; SEA-SURFACE TEMPERATURE; ESTIMATING RAINFALL; CLIMATOLOGY; SPACE AB study, gridded observed precipitation datasets are used to construct rainfall-based ENSO indices. The monthly Ei Nino and La Nina indices (EI and LI) measure the steepest zonal gradient of precipitation anomalies between the equatorial Pacific and the Maritime Continent. This is accomplished by spatially averaging precipitation anomalies using a spatial boxcar Filter, finding the maximum and minimum averages within a pacific and Maritime Continent domain for each month, and taking differences. The Fl and LI can be examined separately or combined to produce one El Nino-Southern Oscillation (ENSO) precipitation index (ESPI). ESPI is well correlated with traditional sea surface temperature (e.g., Nino-3.4) and pressure indices [e.g.. Southern Oscillation index (SOI)], leading Nino-3.3 by a month. ESPI has a tendency to produce stronger La Ninas than does Nino3.4 and SOI. One advantage satellite-derived precipitation indices have over more conventional indices is describing the strength and position of the Waller circulation. Examples are given of tracking the impact of recent ENSO events on the tropical precipitation fields. The 1982/83 and 1997/98 events were unique in that, during the transition from the warm to the cold phase, precipitation patterns associated with El Nino and La Nina were simultaneously strong. According to EI and ESPI, the 1997/98 El Nino was the strongest event over the past 20 years. C1 NASA, Goddard Space Flight Ctr, JCET, UMBC,Lab Atmposheres, Greenbelt, MD 20771 USA. Univ Maryland, Joint Ctr Earth Syst Technol, Baltimore, MD 21201 USA. RP Curtis, S (reprint author), NASA, Goddard Space Flight Ctr, JCET, UMBC,Lab Atmposheres, Code 912, Greenbelt, MD 20771 USA. RI Curtis, Scott/C-1115-2013; OI Curtis, Scott/0000-0001-9065-8639 NR 12 TC 56 Z9 58 U1 0 U2 6 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 AUG 1 PY 2000 VL 13 IS 15 BP 2786 EP 2793 DI 10.1175/1520-0442(2000)013<2786:EIBOPO>2.0.CO;2 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 345JB UT WOS:000088811900009 ER PT J AU Stolz, JA McCann, RS AF Stolz, JA McCann, RS TI Visual word recognition: Reattending to the role of spatial attention SO JOURNAL OF EXPERIMENTAL PSYCHOLOGY-HUMAN PERCEPTION AND PERFORMANCE LA English DT Article ID LEXICAL ACCESS; SEMANTIC CONTEXT; ACTIVATION MODEL; READING ALOUD; FREQUENCY; DEGRADATION; INTEGRATION; ALLOCATION; DECISIONS; SELECTION AB Three experiments examine whether spatial attention and visual word recognition processes operate independently or interactively in a spatially cued lexical-decision task. Participants responded to target strings that had been preceded first by a prime word at fixation and then by an abrupt onset cue either above or below fixation. Targets appeared either in the cued (i.e., valid) or uncued (i.e., invalid) location. The proportion of validly cued trials and the proportion of semantically related prime-target pairs were manipulated independently. It is concluded that spatial attention and visual word recognition processes are best, seen as interactive. Spatial attention affects word recognition in 2 distinct ways: (a) it affects the uptake of orthographic information, possibly acting as "glue" to hold Letters in their proper places in words, and (b) it (partly) determines whether or nor activation from the semantic level feeds down to the lexical level during word recognition. C1 Univ Waterloo, Dept Psychol, Waterloo, ON N2L 3G1, Canada. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Stolz, JA (reprint author), Univ Waterloo, Dept Psychol, Waterloo, ON N2L 3G1, Canada. NR 67 TC 31 Z9 33 U1 1 U2 1 PU AMER PSYCHOLOGICAL ASSOC PI WASHINGTON PA 750 FIRST ST NE, WASHINGTON, DC 20002-4242 USA SN 0096-1523 J9 J EXP PSYCHOL HUMAN JI J. Exp. Psychol.-Hum. Percept. Perform. PD AUG PY 2000 VL 26 IS 4 BP 1320 EP 1331 DI 10.1037/0096-1523.26.4.1320 PG 12 WC Psychology; Psychology, Experimental SC Psychology GA 337PQ UT WOS:000088371200005 PM 10946717 ER PT J AU McCann, RS Remington, RW Van Selst, M AF McCann, RS Remington, RW Van Selst, M TI A dual-task investigation of automaticity in visual word processing SO JOURNAL OF EXPERIMENTAL PSYCHOLOGY-HUMAN PERCEPTION AND PERFORMANCE LA English DT Review ID PSYCHOLOGICAL REFRACTORY-PERIOD; LEXICAL ACCESS; SPREADING ACTIVATION; RECOGNITION TASKS; CHRONOMETRIC EVIDENCE; VERIFICATION MODEL; OVERLAPPING TASKS; DIVIDED ATTENTION; PRINTED WORDS; READING ALOUD AB An analysis of activation models of visual word processing suggests that frequency-sensitive forms of lexical processing should proceed normally while unattended. This hypothesis was tested by having participants perform a speeded pitch discrimination task followed by lexical decisions or word naming. As the stimulus onset asynchrony between the tasks was reduced, lexical-decision and naming latencies increased dramatically. Word-frequency effects were additive with the increase, indicating that frequency-sensitive processing was subject to postponement while attention was devoted to the other task. Either (a) the same neural hardware shares responsibility for lexical processing and central stages of choice reaction time task processing and cannot perform both computations simultaneously, or (b) lexical processing is blocked in order to optimize performance on the pitch discrimination task. Either way, word processing is not as automatic: as activation models suggest. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. San Jose State Univ, Dept Psychol, San Jose, CA 95192 USA. RP McCann, RS (reprint author), NASA, Ames Res Ctr, Mail Stop 262-4, Moffett Field, CA 94035 USA. NR 114 TC 62 Z9 63 U1 7 U2 12 PU AMER PSYCHOLOGICAL ASSOC PI WASHINGTON PA 750 FIRST ST NE, WASHINGTON, DC 20002-4242 USA SN 0096-1523 J9 J EXP PSYCHOL HUMAN JI J. Exp. Psychol.-Hum. Percept. Perform. PD AUG PY 2000 VL 26 IS 4 BP 1352 EP 1370 DI 10.1037//0096-1523.26.4.1352 PG 19 WC Psychology; Psychology, Experimental SC Psychology GA 337PQ UT WOS:000088371200007 PM 10946719 ER PT J AU St Cyr, OC Howard, RA Sheeley, NR Plunkett, SP Michels, DJ Paswaters, SE Koomen, MJ Simnett, GM Thompson, BJ Gurman, JB Schwenn, R Webb, DF Hildner, E Lamy, PL AF St Cyr, OC Howard, RA Sheeley, NR Plunkett, SP Michels, DJ Paswaters, SE Koomen, MJ Simnett, GM Thompson, BJ Gurman, JB Schwenn, R Webb, DF Hildner, E Lamy, PL TI Properties of coronal mass ejections: SOHO LASCO observations from January 1996 to June 1998 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID DISCONNECTED MAGNETIC-STRUCTURE; SOLAR-WIND; SMM OBSERVATIONS; WHITE-LIGHT; FLOW SPEEDS; FLUX ROPE; APRIL 7; EIT; TRANSIENT; EARTH AB We report the properties of all the 841 coronal mass ejections (CMEs) observed by the Solar and Heliospheric Observatory (SOHO) Large Angle Spectroscopic Coronagraph (LASCO) C2 and C3 white-light coronagraphs from January 1996 through June 1998, and we compare those properties to previous observations by other similar instruments. Both the CME rate and the distribution of apparent locations of CMEs varied during this period as expected based on previous solar cycles. The distribution of apparent speeds and the fraction of CMEs showing acceleration were also in agreement with earlier reports. The pointing stability provided by an L-l orbit and the use of CCD detectors have resulted in superior brightness sensitivity for LASCO over earlier coronagraphs; however, we have not detected a significant population of fainter (i.e., low mass) CMEs. The general shape of the distribution of apparent sizes for LASCO CMEs is similar to those of earlier reports, but the average (median) apparent size of 72 degrees (50 degrees) is significantly larger. The larger average apparent size is predominantly the result of the detection of a population of partial and complete halo CMEs at least some of which appear to be events with a significant longitudinal component directed along the Sun-Earth line, either toward or away from the Earth. Using full disk solar images obtained by the Extreme ultraviolet Imaging Telescope (EIT) on SOHO, we found that 40 out of 92 of these events might have been directed toward the Earth, and we compared the timing of those with the I(I) geomagnetic storm index in the days following the CME, Although the "false alarm" rate was high, we found that 15 out of 21 (71%) of the K-p greater than or equal to 6 storms could be accounted for as SOHO LASCO/EIT frontside halo CMEs. If we eliminate three Kp, storms that occurred following LASCO/EIT data gaps. then the possible association rate was 15 out of 18 (83%). C1 Computat Phys Inc, Fairfax, VA USA. USN, Res Lab, Washington, DC 20375 USA. Univ Space Res Assoc, Washington, DC USA. Ball Aerosp Corp, Boulder, CO 80301 USA. Sachs Freeman Associates Inc, Naval Res Lab, Washington, DC 20375 USA. Univ Birmingham, Sch Phys & Space Res, Birmingham B15 2TT, W Midlands, England. NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. Max Planck Inst Aeron, D-37189 Lindau, Germany. Boston Coll, Inst Sci Res, Chestnut Hill, MA 02167 USA. Space Vehicles Directorate, Air Force Res Lab, Hanscom AFB, MA USA. NOAA, Space Environm Ctr, Boulder, CO 80303 USA. Astron Spatiale Lab, F-13248 Marseille, France. RP Computat Phys Inc, Fairfax, VA USA. RI Thompson, Barbara/C-9429-2012 NR 73 TC 347 Z9 347 U1 0 U2 12 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9380 EI 2169-9402 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD AUG 1 PY 2000 VL 105 IS A8 BP 18169 EP 18185 DI 10.1029/1999JA000381 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 342RU UT WOS:000088659600001 ER PT J AU Richardson, IG Cliver, EW Cane, HV AF Richardson, IG Cliver, EW Cane, HV TI Sources of geomagnetic activity over the solar cycle: Relative importance of coronal mass ejections, high-speed streams, and slow solar wind SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID COSMIC-RAY MODULATION; LONG-TERM AVERAGES; MAGNETIC-FIELD; ION ENHANCEMENTS; 1 AU; TEMPERATURE; DECREASES; REGIONS; IMP-8; DISTURBANCES AB We assess the contribution of various types of solar wind structures (coronal mass ejections (CMEs), high-speed streams, and slow solar wind) to averages of thf an geomagnetic activity index ((aa)over-bar) during the solar cycle. We used solar wind plasma, magnetic field, and energetic particle data to identify the flow types present in the near-Earth solar wind during 1972-1986 (encompassing the decline of solar cycle 20 and all of cycle 21). Corotating high-speed streams contribute similar to 70% of (aa)over-bar of solar maximum and similar to 30% at solar maximum (1978-1982). CME-related structures (shocks/postshock flows/ejecta) account for similar to 50% of (aa)over-bar at solar maximum and <10% outside of maximum. Slow solar wind contributes similar to 20% throughout the solar cycle. Our analysis provides insight into the Cause of the so-called "Gnevyshev Gap" in geomagnetic activity, characterized by a decrease in (aa)over-bar near the peak of the sunspot cycle. An example of this phenomenon occurred in 1980 at the maximum of cycle 21 when (aa)over-bar registered a value lower than that observed at the preceding solar minimum. We attribute the 1980 depression in an to a temporary reduction in average solar wind speed, evident in both CME and corotating stream related components, and a reduction in mean magnetic fields in all types of solar wind structure. This involvement of all solar wind structures is indicative of a global solar phenomenon, apparently related to an observed depression in tho solar open magnetic flux at the time of solar magnetic field polarity reversal, Both CMEs and streams contribute to geomagnctic activity on either side of this minimum. Thus, at least for cycle 21, the Gnevyshev Gap does not reflect a transition between a period of enhanced geomagnetic activity levels due to CMEs just prior to solar maximum and a second enhancement, due to corotating streams, during the descending phase. Beyond the post Gnevyshev Gap peak, high-speed streams will eventually dominate geomagnetic activity on the decline of the cycle and may, on occasion (as in solar cycle 20), produce a late peak in average geomagnetic activity with relatively little contribution from CMEs. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. USAF, Res Lab, Bedford, MA 01731 USA. RP Richardson, IG (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. OI Richardson, Ian/0000-0002-3855-3634 NR 59 TC 110 Z9 112 U1 2 U2 7 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 AUG 1 PY 2000 VL 105 IS A8 BP 18203 EP 18213 DI 10.1029/1999JA000400 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 342RU UT WOS:000088659600003 ER PT J AU Sanderson, TR Erdos, G Balogh, A Forsyth, RJ Marsden, RG Gosling, JT Phillips, JL Tranquille, C AF Sanderson, TR Erdos, G Balogh, A Forsyth, RJ Marsden, RG Gosling, JT Phillips, JL Tranquille, C TI Effect of magnetic discontinuities on the propagation of energetic particles: Ulysses observations of the onset of the March 1991 solar particle event SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID WAVES; HELIOSPHERE AB We present observations of energetic ions from the Cosmic Ray and Solar particle Investigation (COSPIN) and Heliosphere Instrument for Spectra Composition and Anisotropy at Law Energy (HISCALE) instruments on board the Ulysses spacecraft. We examine ill detail the onset of energetic ions observed during the March 1991 series of solar events. Active region 6555, at E28 at 2247 UT on March 22, 1991 (day 81), was most likely responsible for the high-energy protons subsequently seen at Ulysses. A slow increase in the high-energy (similar to 50 MeV) proton intensity, made up of many small but rapid intensity increases, began around 9 hours after the onset of the event, taking 1.5 days to reach maximum intensity. On the flank, and in front of a coronal mass ejection (CME), coming From a previous event, we observed a region with a drop in the magnetic field strength. This region was populated with hot shocked plasma and, owing to the low magnetic field pressure, had an ion plasma beta >1. Mirror mode waves, with discontinuities appearing at the edges of the waves, produced a larger-than-average number of magnetic field discontinuities, a large fraction of the discontinuities being aligned with their normals oriented along the radial direction, suggesting that they were being convected outward by the CME. These discontinuities acted as a series of barriers to the propagation of the energetic solar particles coming from the solar event, delaying substantially the onset of the particle event at Ulysses. C1 Estec, Dept Space Sci, NL-2220 AG Noordwijk, Netherlands. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2BZ, England. KFKI, Res Inst Particle & Nucl Phys, H-1525 Budapest, Hungary. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. RP Sanderson, TR (reprint author), Estec, Dept Space Sci, Keplerlaan 1,Postbus 299, NL-2220 AG Noordwijk, Netherlands. NR 15 TC 7 Z9 6 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 AUG 1 PY 2000 VL 105 IS A8 BP 18275 EP 18283 DI 10.1029/1999JA000115 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 342RU UT WOS:000088659600008 ER PT J AU Wibberenz, G Canc, HV AF Wibberenz, G Canc, HV TI Simple analytical solutions for propagating diffusive barriers and application to the 1974 minicycle SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID COSMIC-RAY MODULATION; MERGED INTERACTION REGIONS; SOLAR MAGNETIC-FIELD; DRIFT MODEL; HELIOSPHERE; DECREASES; ANISOTROPIES; SIMULATION; INTENSITY; 11-YEAR AB The cosmic ray minicycle of 1974 is a medium-term modulation event where a clear anticorrelation is observed between the cosmic ray intensity and the heliospheric magnetic field magnitude B. It occurs during a period of minimum solar activity in an A > 0 magnetic polarity epoch. Cosmic ray modulation during the event is studied with an analytical, spherically symmetric approximation for a propagating diffusive barrier. Under the assumption that the cosmic ray radial diffusion coefficient It scales inversely with B, the temporal development of the disturbance can be obtained from the observed variation of B. A recovery process is described by a simple exponential, with a. constant recovery time throughout the event. The profile of the intensity decrease as predicted by the model varies with the temporal development of the disturbance and with the duration of the disturbance in relation to the recovery timescale. The model predicts a maximum depression which is about a factor of 2.5 too small compared with neutron monitor observations. A replacement of the inverse relation K proportional to 1/B by the more general case K oc B-n and a value of n similar to 2.5 leads to a good agreement between model and observations. It is remarkable how closely the high-energy cosmic ray intensity follows the temporal structure of the magnetic field magnitude, suggesting that the magnetic field enhancement plays an important role for modulation during the minicycle. For the period under study, radial diffusion is essentially determined by diffusion parallel to the average field. Based on quasilinear theory a variation K-parallel to proportional to B-2 is suggested, consistent with the value of n = 2.5 +/- 1.0 derived in the paper. C1 Univ Kiel, Inst Expt & Angew Phys, D-24118 Kiel, Germany. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Tasmania, Sch Math & Phys, Hobart, Tas, Australia. RP Wibberenz, G (reprint author), Univ Kiel, Inst Expt & Angew Phys, D-24118 Kiel, Germany. NR 33 TC 24 Z9 24 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 AUG 1 PY 2000 VL 105 IS A8 BP 18315 EP 18325 DI 10.1029/1999JA000457 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 342RU UT WOS:000088659600012 ER PT J AU Garcia, FJ Kelley, MC Makela, JJ Sultan, PJ Pi, X Musman, S AF Garcia, FJ Kelley, MC Makela, JJ Sultan, PJ Pi, X Musman, S TI Mesoscale structure of the midlatitude ionosphere during high geomagnetic activity: Airglow and GPS observations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID F-REGION; ELECTRIC-FIELD; ARECIBO; NETWORK AB On the night of November 22, 1997, the Cornell All-Sky Imager recorded a spectacular display of structure in the 630.0 nm emission over Arecibo, Puerto nice. This event is an example of a phenomenon we have termed "intense midlatitude spread F." In this paper we describe the stormtime geophysical conditions for the period and detail the evolution of the event. The daytime midlatitude ionosphere was disturbed for four consecutive days. The initial daytime doubling of the total electron content (TEC) was associated with equatorward propagation of a high-TEC patch that seemed to have associated composition changes. The following days had distinct diurnal double maxima (DDM). The TEC in the Caribbean was very high during the first night of the storm and was extremely structured. Airglow depletions and enhancements surged poleward, bifurcating numerous times in the process. The airglow depletions were collocated wit;ll TEC minima along similar lines of sight to Global Positioning System satellites. Eventually, four parallel and very similar airglow wave packets were visible and oriented at an angle similar to the less violent structures reported in the companion paper [Garcia et al., this issue] and moving slowly toward the southwest. We explore a number of possible explanations for these features. We are most confident that secondary instabilities of the generalized ExB process can explain the evolution of the structures once they are formed. The initial process itself remains controversial. C1 Cornell Univ, Sch Elect Engn, Ithaca, NY 14853 USA. USAF, Res Lab, Hanscom AFB, MA 01731 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NOAA, Geosci Res Div, Silver Spring, MD 20910 USA. RP Garcia, FJ (reprint author), Cornell Univ, Sch Elect Engn, 318 Rhodes Hall, Ithaca, NY 14853 USA. NR 17 TC 20 Z9 20 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 AUG 1 PY 2000 VL 105 IS A8 BP 18417 EP 18427 DI 10.1029/1999JA000306 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 342RU UT WOS:000088659600020 ER PT J AU Palmroth, M Laakso, H Fejer, BG Pfaff, RF AF Palmroth, M Laakso, H Fejer, BG Pfaff, RF TI DE 2 observations of morningside and eveningside plasma density depletions in the equatorial ionosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SPREAD-F; ELECTRIC-FIELD; RADAR OBSERVATIONS; BUBBLES; IRREGULARITIES; EVOLUTION AB The occurrence of equatorial density depletions in the nightside F region ionosphere has been investigated by using observations gathered by the polar-orbiting Dynamics Explorer 2 satellite from August 1981 to February 1983. A variety of electric field/plasma drift patterns were observed within these depletions. including updrafting, downdrafting, bifurcating, converging, subsonic, and supersonic flows. The depletions, 116 events in total, are distributed over two groups: group I (eveningside depletions) consists of the events in the 1900-2300 MLT sector, and group II (morningside depletions) are the events in the 2300-0600 MLT sector. A statistical analysis reveals clear differences in the density depletion occurrence rates between the two groups. Magnetic activity appears to suppress the generation of eveningside depletions with a delay of 2-3 hours. In the morningside the probability of observing depletions increases instantly with increasing magnetic activity; yet the best correlation is found with a 2-hour delay. This indicates that in the premidnight sector the substorm-induced dynamo and prompt penetration electric fields induce westward electric fields in the equatorial ionosphere 2 hours after the onset in the auroral reg;ion. In the postmidnight sector, high-latitude ionospheric disturbances induce instantly equatorial eastward electric fields that move the F layer to higher altitudes, where it can become unstable to the Rayleigh-Taylor instability. Eveningside depletions were observed at all longitudes except those over the Pacific Ocean, while the morningside depletions occurred mostly over the Pacific and Atlantic-African sectors. C1 Finnish Meteorol Inst, FIN-00101 Helsinki, Finland. Utah State Univ, Ctr Atmospher & Space Sci, Logan, UT 84322 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Palmroth, M (reprint author), Finnish Meteorol Inst, POB 503, FIN-00101 Helsinki, Finland. RI Pfaff, Robert/F-5703-2012 OI Pfaff, Robert/0000-0002-4881-9715 NR 36 TC 15 Z9 15 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD AUG 1 PY 2000 VL 105 IS A8 BP 18429 EP 18442 DI 10.1029/1999JA005090 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 342RU UT WOS:000088659600021 ER PT J AU Mariani, F Orsini, S Candidi, M Marcucci, MF Acuna, M Musmann, G Ness, NF AF Mariani, F Orsini, S Candidi, M Marcucci, MF Acuna, M Musmann, G Ness, NF TI Characterization of the active current system around the TSS-1R satellite through magnetic field measurements taken by the Tethered Magnetometer instrument SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CURRENT COLLECTION; PLASMA AB In this paper we present the measurements and interpretations of the Tethered Magnetometer (TEMAG) experiment flown on the Tethered Satellite Mission Reflight TSS-1R. Data were taken during the active operating phase when current steps of variable amplitude were injected along the electrically conducting tether. The magnetic field shows clear signatures in the components and amplitude, dependent upon the orientation of the magnetometer boom with respect to the spacecraft ram velocity vector. In the eight events studied, current effects could be observed in the magnetic field data only when the boom was pointing toward the ram side hemisphere of the satellite, The picture emerging from the observed results suggests the formation of a current sheet on the ram side, possibly associated with the aerodynamic shock and compression of the geomagnetic field ahead of the satellite. Although the limited data do not allow full description of the phenomenology, they place important observational constraints on any theoretical model. C1 Univ Roma Tor Vergata, Dipartimento Fis Univ, I-00133 Rome, Italy. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. CNRS, IFSI, I-00133 Rome, Italy. Tech Univ Braunschweig, D-3300 Braunschweig, Germany. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. RP Mariani, F (reprint author), Univ Roma Tor Vergata, Dipartimento Fis Univ, Via Ric Sci 1, I-00133 Rome, Italy. NR 13 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 AUG 1 PY 2000 VL 105 IS A8 BP 18537 EP 18547 DI 10.1029/2000JA900019 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 342RU UT WOS:000088659600029 ER PT J AU Harris, AW AF Harris, AW TI "Atmospheric holes" are not small comets SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID EARTHS UPPER-ATMOSPHERE; UVI; DAYGLOW; INFLUX; RADAR AB Frank and Sigwarth [1993, 1999] have promoted the hypothesis of a population of small "house-sized" comets in near-parabolic orbits that are nearly tangent with the Earth's and rain down on the Earth at a rate of similar to 20/min. The hypothesis is based on "holes" in the dayglow of the Earth's atmosphere, which they first claimed to see in images from the Dynamics Explorer 1 satellite, and more recently in images from the Polar satellite. One of the key aspects of the claimed observations is that the atmospheric holes appear to be more numerous on the morning hemisphere of the Earth, to which Frank and Sigwarth draw analogy to radar meteors, which show a similar asymmetry. In this paper, I show that the distribution of orbits posited by Frank and Sigwarth yield a maximum flux in the afternoon, the opposite asymmetry from the claimed observations. The only orbits which yield the correct diurnal asymmetry, and preserve acceptably low entry speeds, are orbits interior to the Earth's having perihelia near the orbit of Mercury. Thus any relationship of "atmospheric holes" to "small comets," or icy bodies from the outer solar system, can be ruled out. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Harris, AW (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 183-501, Pasadena, CA 91109 USA. NR 16 TC 1 Z9 1 U1 1 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 AUG 1 PY 2000 VL 105 IS A8 BP 18575 EP 18579 DI 10.1029/1999JA000216 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 342RU UT WOS:000088659600032 ER PT J AU Harris, AW AF Harris, AW TI Comment on "'Atmospheric holes' are not small comets" by A. W. Harris - Reply SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Editorial Material ID UVI; SEARCH; EARTH C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Harris, AW (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 183-501, Pasadena, CA 91109 USA. NR 13 TC 0 Z9 0 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD AUG 1 PY 2000 VL 105 IS A8 BP 18585 EP 18587 DI 10.1029/2000JA000089 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 342RU UT WOS:000088659600034 ER PT J AU Wygant, JR Keiling, A Cattell, CA Johnson, M Lysak, RL Temerin, M Mozer, FS Kletzing, CA Scudder, JD Peterson, W Russell, CT Parks, G Brittnacher, M Germany, G Spann, J AF Wygant, JR Keiling, A Cattell, CA Johnson, M Lysak, RL Temerin, M Mozer, FS Kletzing, CA Scudder, JD Peterson, W Russell, CT Parks, G Brittnacher, M Germany, G Spann, J TI Polar spacecraft based comparisons of intense electric fields and Poynting flux near and within the plasma sheet-tail lobe boundary to UVI images: An energy source for the aurora SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID KINETIC ALFVEN WAVES; ELECTROSTATIC SHOCKS; ION-BEAMS; SATELLITE-OBSERVATIONS; PARTICLE-ACCELERATION; HIGH-ALTITUDE; MAGNETOSPHERE; REGION; ZONE; ISEE-1 AB In this paper, we present measurements from two passes of the Polar spacecraft of intense electric and magnetic field structures associated with Alfven waves at and within the outer boundary of the plasma sheet at geocentric distances of 4-6 R-E near local midnight. The electric field variations have maximum values exceeding 100 mV/m and are typically polarized approximately normal to the plasma sheet boundary. The electric field structures investigated vary over timescales (in the spacecraft Frame) ranging from 1 to 30 s. They are associated with strong magnetic field fluctuations with amplitudes of 10-40 nT which lie predominantly in the plane of the plasma sheet and are perpendicular to the local magnetic field. The Poynting flux associated with the perturbation fields measured at these altitudes is about 1-2 ergs cm(-2) s(-1) and is directed along the average magnetic field direction toward the ionosphere. If the measured Poynting flux is mapped to ionospheric altitudes along converging magnetic field lines, the resulting energy flux ranges up to 100 ergs cm(-2) s(-1). These strongly enhanced Poynting fluxes appear to occur in layers which are observed when the spacecraft is magnetically conjugate (to within a 1 degrees mapping accuracy) to intense auroral structures as detected by the Polar UV Imager (UVI). The electron energy flux (averaged over a spatial resolution of 0.5 degrees) deposited in the ionosphere due to auroral electron beams as estimated from the intensity in the UVI Lyman-Birge-Hopfield-long filters is 15-30 ergs cm(-2)s(-1). Thus there is evidence that these electric field structures provide sufficient Poynting flux to power the acceleration of auroral electrons (as well as the energization of upflowing ions and Joule heating of the ionosphere). During some events the phasing and ratio of the transverse electric and magnetic field variations are consistent with earthward propagation of Alfven surface waves with phase velocities of 4000-10000 km/s. During other events the phase shifts between electric and magnetic fields suggest interference between upward and downward propagating Alfven waves. The E/B ratios an about an order of magnitude larger than typical values of c/Sigma(p), where Sigma(p) is the height integrated Pedersen conductivity. The contribution to the total energy flux at these altitudes from Poynting flux associated with Alfven waves is comparable to or larger than the contribution from the particle energy flux and 1-2 orders of magnitude larger than that estimated from the large-scale steady stale convection electric field and field-aligned current system. C1 Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA. Univ Washington, Geophys Program, Seattle, WA 98195 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Lockheed Martin Palo Alto Labs, Palo Alto, CA 94304 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA. RP Wygant, JR (reprint author), Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA. RI Peterson, WK/A-8706-2009; Scudder, Jack/D-8417-2013; OI Peterson, WK/0000-0002-1513-6096; Scudder, Jack/0000-0001-7975-5630; Cattell, Cynthia/0000-0002-3805-320X; Kletzing, Craig/0000-0002-4136-3348 NR 45 TC 186 Z9 186 U1 1 U2 13 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 AUG 1 PY 2000 VL 105 IS A8 BP 18675 EP 18692 DI 10.1029/1999JA900500 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 342RU UT WOS:000088659600041 ER PT J AU Klimas, AJ Valdivia, JA Vassiliadis, D Baker, DN Hesse, M Takalo, J AF Klimas, AJ Valdivia, JA Vassiliadis, D Baker, DN Hesse, M Takalo, J TI Self-organized criticality in the substorm phenomenon and its relation to localized reconnection in the magnetospheric plasma sheet SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID DATA-DERIVED ANALOGS; DRIVEN DISSIPATIVE SYSTEMS; FIELD CURRENT INSTABILITY; ION WEIBEL INSTABILITY; EARTHS MAGNETOTAIL; ENERGY-STORAGE; SOLAR-FLARES; INTERMITTENT TURBULENCE; MAGNETIC FLUCTUATIONS; GEOTAIL OBSERVATIONS AB Evidence is presented that suggests that there is a significant self-organized criticality (SOC) component in the dynamics of substorms in the magnetosphere. We assume that observations of bursty bulk flows, fast flows, localized dipolarizations, plasma turbulence, etc, show that multiple localized reconnection sites provide the basic avalanche phenomenon in the establishment of SOC in the plasma sheet. First results are presented from a study of this avalanche process based on this working assumption. A magnetic field reversal model is discussed. Resistivity, in this model, is self-consistently generated in response to the excitation of an idealized current-driven instability. When forced by convection of magnetic flux into the field reversal region, the model yields rapid magnetic field annihilation through a dynamic behavior that is shown to exhibit many of the characteristics of SOC. Over a large range of forcing strengths, the annihilation rate is shown to self-adjust to balance the rate at which flux is convected into the reversal region. Several analogies to magnetotail dynamics are discussed: (1) It is shown that the presence of a localized criticality in the model produces a remarkable stability in the global configuration of the field reversal while simultaneously exciting extraordinarily dynamic internal evolution. (2) Under steady forcing it is shown that a loading-unloading cycle may arise that, as a consequence of the global stability, is quasi-periodic and, therefore, predictable despite the presence of internal turbulence in the field distribution. indeed, it is shown that the global loading-unloading cycle is a consequence of the internal turbulence. (3) It is shown that under steady, strong forcing the loading-unloading cycle vanishes. Instead, a recovery from a single unloading persists indefinitely. The field reversal is globally very steady while internally it is very dynamic as field annihilation goes on at the rate necessary to match the strong forcing. From this result we speculate that steady magnetospheric convection events result when the plasma sheet has been driven close to criticality over an extended spatial domain. During these events we would expect to find localized reconnection sites distributed over the spatial domain of near criticality, and we would expect to find plasma sheet transport in that domain to be closely related to that of BBF and fast flow events. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. Univ Oulu, Dept Phys Sci, Oulu, Finland. Univ Chile, Fac Ciencias, Dept Fis, Santiago, Chile. NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. RP Klimas, AJ (reprint author), NASA, Goddard Space Flight Ctr, Mail Code 692, Greenbelt, MD 20771 USA. EM alex.klimas@gsfc.nasa.gov; alejo@fisica.ciencias.uchile.cl; vassi@lepgst.gsfc.nasa.gov; baker@lynx.colorado.edu; michael.hesse@gsfc.nasa.gov; jouni.takalo@oulo.fi RI Valdivia, Juan/A-3631-2008; Hesse, Michael/D-2031-2012 OI Valdivia, Juan/0000-0003-3381-9904; NR 72 TC 103 Z9 104 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 AUG 1 PY 2000 VL 105 IS A8 BP 18765 EP 18780 DI 10.1029/1999JA000319 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 342RU UT WOS:000088659600047 ER PT J AU Gallagher, DL Craven, PD Comfort, RH AF Gallagher, DL Craven, PD Comfort, RH TI Global core plasma model SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ELECTRON-DENSITY; DUSKSIDE BULGE; REGION; MAGNETOSPHERE; IONOSPHERE; BEHAVIOR; DYNAMICS; TROUGH; PROBE; HE+ AB The global core plasma model (GCPM) provides empirically derived core plasma density as a function of geomagnetic and solar conditions throughout the inner magnetosphere. It is continuous in value and gradient and is composed of separate models for the ionosphere, plasmasphere, plasmapause, trough, and polar cap. The relative composition of plasmaspheric H+, He+, and O+ is included in the GCPM. A blunt plasmaspheric bulge and rotation of the bulge with changing geomagnetic conditions is included. The GCPM is an amalgam of density models intended to serve as a framework for continued improvement as new measurements become available and are used to characterize core plasma density, composition, and temperature. C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. Univ Alabama, Ctr Space Plasma & Aeronom Res, Huntsville, AL 35807 USA. RP Gallagher, DL (reprint author), NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. NR 52 TC 173 Z9 174 U1 1 U2 10 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 AUG 1 PY 2000 VL 105 IS A8 BP 18819 EP 18833 DI 10.1029/1999JA000241 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 342RU UT WOS:000088659600051 ER PT J AU Casadei, C Martelli, S Fiorini, P AF Casadei, C Martelli, S Fiorini, P TI A workcell for the development of robot-assisted surgical procedures SO JOURNAL OF INTELLIGENT & ROBOTIC SYSTEMS LA English DT Article DE discectomy; graphical interface; hybrid compliance control; knee osteoctomy; PC-based control; PUMA; robot-assisted surgery; robot-X-ray calibration AB This paper describes a robotic workstation for the development of new robot-assisted surgical procedures. This work is motivated by the difficulties and cost associated to the development of surgical robots, often requiring large investments and several re-designs which limit wider use of this technology. The approach presented here consists of using a general purpose robotic workcell to develop the hardware and the surgical aspects of new robot-based surgical systems, before committing to a completely new system design. The workcell is based on a clean room PUMA 260 manipulator, suitably enhanced to expand and improve its capabilities, and on a vision-based operator interface. Two new robot-assisted surgical procedures have been developed and tested using this set-up: percutaneous discectomy and knee osteoctomy. By using the robotic workcell, engineers and surgeons are able to define many aspects of the two procedures, such as surgical gestures, workspace of the robot, and calibration procedures, without incurring a large, up-front investment. First, the article describes the configuration of the workcell, the enhancements to the PUMA manipulator and the surgical procedures developed with this setup. Then the results of the tests and the lessons learned using the workcell are discussed in some detail. C1 Ist Ortoped Rizzoli, Lab Biocmeccan, I-40139 Bologna, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Casadei, C (reprint author), Ist Ortoped Rizzoli, Lab Biocmeccan, I-40139 Bologna, Italy. EM s.martelli@biomec.ior.it RI Fiorini, Paolo/A-2603-2012 NR 37 TC 2 Z9 2 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0921-0296 J9 J INTELL ROBOT SYST JI J. Intell. Robot. Syst. PD AUG PY 2000 VL 28 IS 4 BP 301 EP 324 DI 10.1023/A:1008104822926 PG 24 WC Computer Science, Artificial Intelligence; Robotics SC Computer Science; Robotics GA 332KW UT WOS:000088074200001 ER PT J AU Tumer, IY Longoria, RG Wood, KL AF Tumer, IY Longoria, RG Wood, KL TI Signal analysis using Karhunen-Loeve transformation: Application to hydrodynamic forces SO JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID FLOW AB This paper describes a signal analysis method using the Karhunen-Loeve (KL) transform, and applies the method to the analysis of hydrodynamic force data collected from controlled laboratory experiments. To demonstrate feasibility the study focuses on inline forces induced on fixed cylinders exposed to oscillatory flows, with increasing Keulegan- Carpenter numbers. This preliminary example illustrates how this force makes a transition from the inertia-dominated region at low Keulegan-Carpenter numbers up into higher Keulegan-Carpenter numbers where the nonlinear effects of the flow-structure interaction can be observed through the increased influence of clearly defined modes. [S0892-7219(00)00603-8]. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Texas, Austin, TX 78712 USA. RP Tumer, IY (reprint author), NASA, Ames Res Ctr, Mail Stop 269-3, Moffett Field, CA 94035 USA. NR 12 TC 0 Z9 0 U1 1 U2 2 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0892-7219 J9 J OFFSHORE MECH ARCT JI J. Offshore Mech. Arct. Eng. Trans. ASME PD AUG PY 2000 VL 122 IS 3 BP 208 EP 213 DI 10.1115/1.1286923 PG 6 WC Engineering, Ocean; Engineering, Mechanical SC Engineering GA 404NT UT WOS:000167107300009 ER PT J AU Huang, NE Shih, HH Shen, Z Long, SR Fan, KL AF Huang, NE Shih, HH Shen, Z Long, SR Fan, KL TI The ages of large amplitude coastal seiches on the Caribbean Coast of Puerto Rico SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID INTERNAL WAVES; HILBERT SPECTRUM; GENERATION; EXCITATION; SEA AB Using a process denoted here as the empirical mode decomposition and the Hilbert spectral analysis, the ages of the seiches on the Caribbean coast of Puerto Rico are determined from their dispersion characteristics with respect to time. The ages deduced from this method are less than a day; therefore, the seiches could be locally generated. C1 NASA, Goddard Space Flight Ctr, Oceans & Ice Branch, Lab Hydrospher Proc, Wallops Island, VA 23337 USA. CALTECH, Pasadena, CA 91125 USA. NOAA, Natl Ocean Serv, Silver Spring, MD USA. Univ Calif Irvine, Dept Civil & Environm Engn, Irvine, CA 92717 USA. NASA, Goddard Space Flight Ctr, Wallops Flight Facil, Observat Sci Branch,Lab Hydrospher Proc, Wallops Island, VA 23337 USA. Natl Taiwan Univ, Inst Oceanog, Taipei 10764, Taiwan. RP Long, SR (reprint author), NASA, Goddard Space Flight Ctr, Oceans & Ice Branch, Lab Hydrospher Proc, WFF Code 972,Bldg N-159,Room W-134, Wallops Island, VA 23337 USA. RI Long, Steven/D-7248-2012 NR 25 TC 31 Z9 44 U1 1 U2 3 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 AUG PY 2000 VL 30 IS 8 BP 2001 EP 2012 DI 10.1175/1520-0485(2000)030<2001:TAOLAC>2.0.CO;2 PG 12 WC Oceanography SC Oceanography GA 347DG UT WOS:000088911700012 ER PT J AU Ortiz, W Wignarajah, K Smith, JD AF Ortiz, W Wignarajah, K Smith, JD TI Inhibitory effect of hypergravity on photosynthetic carbon dioxide fixation in Euglena gracilis SO JOURNAL OF PLANT PHYSIOLOGY LA English DT Article DE Euglena gracilis; carbon dioxide fixation; hypergravity; photosynthesis; stress response ID WHEAT PLANTS; CLINOSTAT; SPACE; MICROGRAVITY; RESPONSES AB Photosynthesis, the conversion of light energy into chemical energy, is a critical biological process, whereby plants synthesize carbohydrates from light, carbon dioxide (CO2) and water. The influence of gravity on this biological process, however, is not weil understood. Thus, centrifugation was used to alter the gravity environment of Euglena gracilis grown on nutritive agar plates illuminated with red and blue light emitting diodes. The results showed that hypergravity (up to 10xg) had an inhibitory effect on photosynthetic CO2 fixation. Chlorophyll accumulation per cell was essentially unaffected by treatment; however, Chl a/Chl b ratios decreased in hypergravity when compared to 1xg controls. Photosynthesis in Euglena appears to have limited tolerance for even moderate changes in gravitational acceleration. C1 Univ Oklahoma, Dept Bot & Microbiol, Norman, OK 73019 USA. NASA, Ames Res Ctr, Lockheed Martin Engn & Sci, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Ctr Bioinformat, Moffett Field, CA 94035 USA. RP Smith, JD (reprint author), Univ Oklahoma, Dept Bot & Microbiol, 770 Van Vieet Oval, Norman, OK 73019 USA. NR 20 TC 3 Z9 3 U1 1 U2 1 PU URBAN & FISCHER VERLAG PI JENA PA BRANCH OFFICE JENA, P O BOX 100537, D-07705 JENA, GERMANY SN 0176-1617 J9 J PLANT PHYSIOL JI J. Plant Physiol. PD AUG PY 2000 VL 157 IS 2 BP 231 EP 234 PG 4 WC Plant Sciences SC Plant Sciences GA 348QU UT WOS:000088998100013 PM 11543574 ER PT J AU Wang, Y Sakamoto, J Kostov, S Mansour, AN denBoer, ML Greenbaum, SG Huang, CK Surampudi, S AF Wang, Y Sakamoto, J Kostov, S Mansour, AN denBoer, ML Greenbaum, SG Huang, CK Surampudi, S TI Structural aspects of electrochemically lithiated SnO: nuclear magnetic resonance and X-ray absorption studies SO JOURNAL OF POWER SOURCES LA English DT Article; Proceedings Paper CT Solid State Lithium Battery Workshop CY JUL, 1999 CL TOWSON, MARYLAND DE SnO; nuclear magnetic resonance; x-ray absorption ID LITHIUM; OXIDE; CARBON AB We have compared the local structure of electrochemically lithiated SnO with Sn/Li alloys using Li-7 to study the environment of the Li ion and extended X-ray absorption fine structure to study the environment of the Sn ion. Although a widely accepted simple model suggested that the electrochemically Lithiated SnO should be similar to Sn/Li alloys of corresponding composition, we find this is true only at low Li concentrations. The addition of more Li to the structure produces, for both the Li and the Sn, features which are difficult to reconcile with the simple model, and suggest the presence of direct Sn-O interactions. (C) 2000 Elsevier Science S.A. All rights reserved. C1 CUNY Hunter Coll, Dept Phys, New York, NY 10021 USA. CALTECH, Jet Prop Lab, Electrochem Technol Grp, Pasadena, CA 91109 USA. USN, Ctr Surface Warfare, Bethesda, MD 20817 USA. RP denBoer, ML (reprint author), CUNY Hunter Coll, Dept Phys, New York, NY 10021 USA. NR 11 TC 14 Z9 14 U1 2 U2 6 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0378-7753 J9 J POWER SOURCES JI J. Power Sources PD AUG PY 2000 VL 89 IS 2 BP 232 EP 236 DI 10.1016/S0378-7753(00)00434-1 PG 5 WC Chemistry, Physical; Electrochemistry; Energy & Fuels; Materials Science, Multidisciplinary SC Chemistry; Electrochemistry; Energy & Fuels; Materials Science GA 329ZJ UT WOS:000087938100017 ER PT J AU Toth, RA AF Toth, RA TI N-2- and air-broadened linewidths and frequency-shifts of N2O SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID LINE POSITIONS; STRENGTHS; CM(-1); BANDS AB N-2- and air-broadened linewidths and pressure-induced frequency-shifts of N2O were measured from spectra of room temperature gas samples. The data were obtained with a high-resolution Fourier Transform spectrometer in the region between 1800 and 4800 cm(-1). Over 500 vibration-rotation lines were measured from which linewidth coefficients were accurately determined (< 2% on the average) for 1 less than or equal to \m\ less than or equal to 73. The shift coefficients were found to have a weak J dependence in which the magnitude of the coefficients increases in proportion to J for a given vibrational band. Further, the results show that the shift coefficients exhibit a line frequency dependence which follows from theory. In general, N-2- or air-broadened shift coefficients (which were found to be comparable in value for a given line) range from about -0.001 to almost -0.005 cm(-1)/atm for the lines covered in this study. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Toth, RA (reprint author), CALTECH, Jet Prop Lab, Mail Stop 183-301, Pasadena, CA 91109 USA. NR 7 TC 26 Z9 26 U1 0 U2 12 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 AUG 1 PY 2000 VL 66 IS 3 BP 285 EP 304 DI 10.1016/S0022-4073(99)00167-3 PG 20 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 310LX UT WOS:000086830600007 ER PT J AU Main, ML Foltz, D Firstenberg, MS Bobinsky, E Bailey, D Frantz, B Pleva, D Baldizzi, M Meyers, DP Jones, K Spence, MC Freeman, K Morehead, A Thomas, JD AF Main, ML Foltz, D Firstenberg, MS Bobinsky, E Bailey, D Frantz, B Pleva, D Baldizzi, M Meyers, DP Jones, K Spence, MC Freeman, K Morehead, A Thomas, JD TI Real-time transmission of full-motion echocardiography over a high-speed data network: Impact of data rate and network quality of service SO JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY LA English DT Article ID VIDEO AB With high-resolution network transmission required for telemedicine, education, and guided-image acquisition, the impact of errors and transmission rates on image quality needs evaluation. Methods: We transmitted clinical echocardiograms from 2 National Aeronautics and Space Administration (NASA) research centers with the use of Motion Picture Expert Group-2 (MPEG-2) encoding and asynchronous transmission mode (ATM) network protocol over the NASA Research and Education Network. Data rates and network quality (cell losses [CLR], errors [CER], and delay variability [CVD]) were altered and image quality was judged. Results: At speeds of 3 to 5 megabits per second (Mbps), digital images were superior to those on videotape; at 2 Mbps, images were equivalent. Increasing CLR caused occasional brief pauses. Extreme CER and CDV increases still yielded high-quality images. Conclusions: Real-time echocardiographic acquisition, guidance, and transmission Is feasible with the use of MPEG-2 and ATM with broadcast quality seen above 3 Mbps, even with severe network quality degradation. These techniques can be applied to telemedicine and used for planned echocardiography aboard the International Space Station. C1 Cleveland Clin Fdn, Dept Cardiol, Cardiovasc Imaging Ctr, Cleveland, OH 44195 USA. NASA, Glenn Res Ctr, Cleveland, OH USA. NASA, Ames Res Ctr, Cleveland, OH USA. RP Thomas, JD (reprint author), Cleveland Clin Fdn, Dept Cardiol, Cardiovasc Imaging Ctr, Desk F-15,9500 Euclid Ave, Cleveland, OH 44195 USA. NR 14 TC 23 Z9 23 U1 0 U2 2 PU MOSBY, INC PI ST LOUIS PA 11830 WESTLINE INDUSTRIAL DR, ST LOUIS, MO 63146-3318 USA SN 0894-7317 J9 J AM SOC ECHOCARDIOG JI J. Am. Soc. Echocardiogr. PD AUG PY 2000 VL 13 IS 8 BP 764 EP 770 DI 10.1067/mje.2000.106075 PG 7 WC Cardiac & Cardiovascular Systems SC Cardiovascular System & Cardiology GA 345NM UT WOS:000088822100008 PM 10936820 ER PT J AU Lucas, C Zipser, EJ Ferrier, BS AF Lucas, C Zipser, EJ Ferrier, BS TI Sensitivity of tropical west pacific oceanic squall lines to tropospheric wind and moisture profiles SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID MACROSCOPIC ENTRAINMENT PROCESSES; SIMULATED CUMULUS ENSEMBLE; BULK ICE SCHEME; TOGA COARE; CONVECTIVE STORMS; NUMERICAL SIMULATIONS; MICROSCALE STRUCTURE; VERTICAL VELOCITY; FRONTAL RAINBANDS; CLOUD SYSTEMS AB Two-dimensional experiments using the Goddard Cumulus Ensemble model ore performed in order to examine the influence of environmental profiles of wind and humidity on the dynamical and microphysical structure of mesoscale convective systems (MCSs) over the tropical oceans. The initial environments used in this study are derived from the results of a cluster analysis of the TOGA COARE sounding data. The model data are analyzed with methods and measurements similar to those used in observational studies. Experiments to test the sensitivity of MCSs to the thermodynamic profile focus on the role of humidity in the free troposphere. In the experiments, a constant amount of relative humidity is added to every level above the boundary layer. As humidity is increased, model storms transition from weak, unsteady systems with little precipitation to strong, upshear-tilted systems with copious rainfall. This behavior is hypothesized to be the result of the entrainment of environmental air into the updraft cores. Experiments to test the sensitivity of MCSs to the kinematic profile focus on the amount of vertical wind shear in the midlevels, between approximately 2 and 10 km. Five kinematic profiles are used. The dynamical and microphysical characteristics of the runs changed dramatically in different shear environments. Shear in the midlevels affects the convective systems by altering the perturbation pressure field. Stronger sheer results in a broader and deeper mesolow below the updraft and a more intense dynamic high above the lending edge. C1 Texas A&M Univ, Dept Meteorol, College Stn, TX 77843 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Lucas, C (reprint author), Univ Adelaide, Dept Phys & Math Phys, Adelaide, SA 5005, Australia. NR 49 TC 44 Z9 45 U1 1 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD AUG 1 PY 2000 VL 57 IS 15 BP 2351 EP 2373 DI 10.1175/1520-0469(2000)057<2351:SOTWPO>2.0.CO;2 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 342QD UT WOS:000088655900002 ER PT J AU Huang, CK Sakamoto, JS Wolfenstine, J Surampudi, S AF Huang, CK Sakamoto, JS Wolfenstine, J Surampudi, S TI The limits of low-temperature performance of Li-ion cells SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID CARBONATES; BATTERIES AB The results of electrode and electrolyte studies reveal that the poor low-temperature (<- 30 degrees C) performance of Li-ion cells is mainly caused by the carbon electrodes and not the organic electrolytes and solid electrolyte interphase, as previously suggested. It is suggested that the main causes for the poor performance in the carbon electrodes are (i) the low value and concentration dependence of the Li diffusivity and (ii) limited Li capacity. (C) 2000 The Electrochemical Society. S0013-4651(00)01-034-X. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Dept Mat Sci, Los Angeles, CA 90095 USA. USA, Res Lab, Adelphi, MD 20783 USA. RP Huang, CK (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 94 Z9 116 U1 7 U2 62 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 AUG PY 2000 VL 147 IS 8 BP 2893 EP 2896 DI 10.1149/1.1393622 PG 4 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA 344FH UT WOS:000088748200008 ER PT J AU Tao, WK Lang, S Simpson, J Olson, WS Johnson, D Ferrier, B Kummerow, C Adler, R AF Tao, WK Lang, S Simpson, J Olson, WS Johnson, D Ferrier, B Kummerow, C Adler, R TI Vertical profiles of latent heat release and their retrieval for TOGA COARE convective systems using a cloud resolving model, SSM/I, and ship-borne radar data SO JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN LA English DT Article ID MIDLATITUDE SQUALL LINE; TROPICAL CUMULUS CLOUDS; MEASURING MISSION TRMM; BULK ICE SCHEME; MOISTURE BUDGETS; NUMERICAL-SIMULATION; MESOSCALE PROCESSES; MICROWAVE; RAINFALL; PRECIPITATION AB Latent heating profiles associated with three TOGA COARE active convective episodes (December 10-17 1992; December 19-27 1992; and February 9-13 1993) are examined using the two-dimensional version of the Goddard Cumulus Ensemble (GCE) Model, and retrieved by using the Goddard Convective and Stratiform Heating (CSH) algorithm. The following sources of rainfall information are input into the CSH algorithm: Special Sensor Microwave Imager (SSM/I), shipborne radars and the GCE model. Diagnostically determined latent heating profiles are calculated using 6 hourly soundings used for validation. The GCE model simulated rainfall and latent heating profiles are in excellent agreement with those estimated by soundings. In addition, the typical convective and stratiform heating structures (or shapes) are well captured by the GCE model. Radar measured rainfall is smaller than that estimated by the GCE model and SSM/I in both December convective episodes. SSM/I derived rainfall is more than the GCE model simulated for the December 19-27 and February 9-13 periods, but it is in excellent agreement with the GCE model for the December 10-17 period. The GCE model estimated stratiform amount is about 50 % for December 19-27, 42 % for December 11-17 and 56 % for the February 9-13 case. These results are consistent with large-scale analyses. Accurate estimates of stratiform amount are needed for good latent heating retrieval. A higher (lower) percentage of stratiform rain can imply a maximum heating rate at a higher (lower) altitude. The GCE model always simulates more stratiform rain (10 to 20 %) than the radar for all three convective episodes. The SSM/I derived stratiform amount is about 37 % for December 19-27, 48 % for December 11-17 and 41 % for the February 9-13 case. Temporal variability of CSH algorithm retrieved latent heating profiles using either the GCE model simulated or radar estimated rainfall and stratiform amount is in good agreement with that diagnostically determined for all three periods. However, less rainfall and a smaller stratiform percentage estimated by radar resulted in a weaker (underestimated) latent heating profile, and a lower maximum latent heating level compared to those determined diagnostically. Rainfall information from SSM/I can not retrieve individual convective events due to poor temporal sampling. Nevertheless, this study suggests that a good rainfall retrieval from SSM/I for a convective event can lead to a good latent heating retrieval. Sensitivity testing has been performed and the results indicate that the SSM/I derived time averaged stratiform amount may be underestimated for December 19-27. Time averaged heating profiles derived from SSM/I, however, agree well with those derived by soundings for the December 10-17 convective period. The heating retrievals may be more accurate for longer time scales, provided there is no bias in the sampling. An appropriate selection of latent heating profiles from the CSH look-up table is important. Sensitivity tests addressing this issue have been performed. C1 NASA, Goddard Space Flight Ctr, Mesoscale Atmospher Proc Branch, Greenbelt, MD 20771 USA. RP Tao, WK (reprint author), NASA, Goddard Space Flight Ctr, Mesoscale Atmospher Proc Branch, Code 912, Greenbelt, MD 20771 USA. EM tao@agnes.gsfc.nasa.gov NR 54 TC 53 Z9 56 U1 0 U2 4 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 AUG PY 2000 VL 78 IS 4 BP 333 EP 355 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 362CT UT WOS:000089761600002 ER PT J AU Librescu, L Nemeth, MP Starnes, JH Lin, W AF Librescu, L Nemeth, MP Starnes, JH Lin, W TI Nonlinear response of flat and curved panels subjected to thermomechanical loads SO JOURNAL OF THERMAL STRESSES LA English DT Article AB The results of an analytical study of the nonlinear response of flat and curved panels subjected to pre-existing, nondestabilizing lateral pressure and thermal loads and to mechanical edge loads are presented. The mechanical loads include uniaxial compression loads and combinations of uniaxial compression and transverse tension or compression loads that are increased monotonically into the postbuckling response range of the panels. The structural model used to analyze the panels is based on a higher order shell theory that includes transverse-shear flexibility, initial geometric imperfections, and von Karman-type geometric nonlinearities. The edges of a panel are modeled as simply supported edges with the displacement normal to the edge face either unrestrained or fully restrained Results are presented for transversely isotropic single-layer panels and three-layer sandwich panels that illustrate how the temperature field, initial imperfections, lateral pressure loads, and mechanical edge loads interact to change the character of the nonlinear panel response. Some response curves are presented that have classic unstable, asymmetric bifurcation behavior and intense snap-through instabilities. Other results show that, for some cases, these interactions can reduce the intensity of snap-through instabilities and even eliminate this form of instability altogether for certain ranges of loaning and structural parameter's. In addition, results are presented that show how transverse-shear flexibility affects the interactions of the temperature field, the initial imperfections, the lateral pressure loans, and, thus, the character of the nonlinear panel response. One important finding of the present study is that linear bifurcation buckling analyses may not indicate adequately the onset of significant nonlinear deformations of a geometrically perfect, shallow curved panel for certain combined mechanical loaning conditions. This finding may affect current preliminary design practice. C1 Virginia Polytech Inst & State Univ, Dept Engn Sci & Mech, Blacksburg, VA 24061 USA. NASA, Langley Res Ctr, Dept Struct Mech, Hampton, VA 23665 USA. RP Librescu, L (reprint author), Virginia Polytech Inst & State Univ, Dept Engn Sci & Mech, Blacksburg, VA 24061 USA. NR 10 TC 29 Z9 29 U1 2 U2 5 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0149-5739 J9 J THERM STRESSES JI J. Therm. Stresses PD AUG PY 2000 VL 23 IS 6 BP 549 EP 582 DI 10.1080/01495730050143134 PG 34 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA 330LR UT WOS:000087964000002 ER PT J AU Okai, K Ono, Y Moriue, O Kato, H Tsue, M Kono, M Sato, J Dietrich, DL Williams, FA AF Okai, K Ono, Y Moriue, O Kato, H Tsue, M Kono, M Sato, J Dietrich, DL Williams, FA TI Effects of the initial heat-up period on a two-droplet array burning at high pressure in microgravity SO JSME INTERNATIONAL JOURNAL SERIES B-FLUIDS AND THERMAL ENGINEERING LA English DT Article DE combustion; liquid fuel; diffusion flame; interaction effects; high pressure combustion ID FUEL DROPLETS; COMBUSTION AB The interactive combustion of two closely-spaced droplets at elevated pressures was investigated experimentally in a 2.2 second drop tower. Heptane, hexadecane and mixtures of the two were the fuel. A nitrogen-oxygen ambient with a relatively low oxygen concentration facilitated observation of droplets during combustion at elevated pressures. Results show that staged combustion of binary fuel droplets still exists for interacting droplets at elevated pressures. For pure fuels, the interaction effects are principally observed during the initial heating period. For fuel mixtures, interaction effects are estimated by comparing the transition time of a single droplet to that of the droplet pair. C1 Univ Tokyo, Dept Aeronaut & Astronaut, Bunkyo Ku, Tokyo 1138656, Japan. Ishikawajima Harima Heavy Ind Co Ltd, Koto Ku, Tokyo 1350061, Japan. NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. Univ Calif San Diego, Ctr Energy & Combust Res, La Jolla, CA 92093 USA. RP Okai, K (reprint author), Univ Tokyo, Dept Aeronaut & Astronaut, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan. EM okai@flame.t.u-tokyo.ac.jp NR 16 TC 1 Z9 1 U1 1 U2 4 PU JAPAN SOC MECHANICAL ENGINEERS PI TOKYO PA SHINANOMACHI-RENGAKAN BLDG, SHINANOMACHI 35, SHINJUKU-KU, TOKYO, 160-0016, JAPAN SN 1340-8054 J9 JSME INT J B-FLUID T JI JSME Int. J. Ser. B-Fluids Therm. Eng. PD AUG PY 2000 VL 43 IS 3 BP 485 EP 490 PG 6 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA 359HH UT WOS:000089605100019 ER PT J AU Casey, S AF Casey, S TI SOFIA detectors take on development challenges SO LASER FOCUS WORLD LA English DT Article C1 NASA, Ames Res Ctr, SOFIA Project, Moffett Field, CA 94035 USA. RP Casey, S (reprint author), NASA, Ames Res Ctr, SOFIA Project, Mail Stop T3B, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PENNWELL PUBL CO PI NASHUA PA 98 SPIT BROOK RD, NASHUA, NH 03062-2801 USA SN 0740-2511 J9 LASER FOCUS WORLD JI Laser Focus World PD AUG PY 2000 VL 36 IS 8 BP S17 EP + PG 4 WC Optics SC Optics GA 345VW UT WOS:000088836700032 ER PT J AU Hui, SC Jackson, AS Wier, LT AF Hui, SC Jackson, AS Wier, LT TI Development of normative values for resting and exercise rate pressure product SO MEDICINE AND SCIENCE IN SPORTS AND EXERCISE LA English DT Article DE myocardial oxygen consumption; heart rate; blood pressure; exercise stress test; norm development; physical fitness ID MYOCARDIAL OXYGEN-CONSUMPTION; UPRIGHT EXERCISE; DISEASE AB Purpose: The purpose of this study was to develop multivariate models to quantify resting, submaximal, and maximal rate pressure products (RPP). Methods: A validation sample (N = 1623) was randomly selected from a clinically healthy population, and four cross-validation samples were randomly selected from a clinical cohort. The cross-validation samples were patients who had a negative exercise ECG with (Neg-Med, N = 179) and without cardiovascular drug (Neg-NoMed, N = 350), and patients who had a positive exercise ECG with (Pos-Med, N = 60) and without cardiovascular drug (Pos-NoMed, N = 75). Men made up 83% of the validation sample (mean age = 44.2 +/- 8.7) and women 17% (mean age = 39.7 +/- 10.1). The validation sample was used to develop multiple regression equations to quantify resting, submaximal, and maximal RPP. Results: Results indicated that gender, body mass index (BMI), and physical activity level (Ex-code) were significantly related with resting RPP. Gender, age, BMI, and Ex-code were significantly related with maximal RPP. Gender, age, BMI, Ex-code, and percent of maximal heart rate at submaximal exercise (%HRmax) were significantly related with submaximal RPP. The multiple correlations for the resting, submaximal, and maximal models were 0.29 (SE = 16.75 beats.min(-1).mm Hg), 0.87 (SE = 29.04 beats.min(-1).mm Hg), and 0.31 (SE = 42.41 beats.min(-1).mm Hg), respectively. The accuracy of the models was confirmed when applied to the Neg-NoMed and Pos-Noh led samples but not the Neg-Med and Pos-Med samples. This result suggest that the regression models developed from this study can be generalized to other populations where patients were not taking cardiovascular medication. Microcomputer programs were suggested to evaluate RPP at rest, maximal exercise, and submaximal exercise. Conclusion: Nonnative RPP for resting and exercise relies on multiple fitness parameters. Practical regression models are developed and can be applied to patients without cardiovascular medication. C1 Chinese Univ Hong Kong, Dept Sports Sci & Phys Educ, Shatin, Hong Kong, Peoples R China. Univ Houston, Dept Hlth & Human Performance, Houston, TX USA. NASA, Lyndon B Johnson Space Ctr, Adult Fitness Ctr, Houston, TX 77058 USA. RP Hui, SC (reprint author), Chinese Univ Hong Kong, Dept Sports Sci & Phys Educ, Shatin, Hong Kong, Peoples R China. NR 32 TC 11 Z9 12 U1 0 U2 1 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0195-9131 J9 MED SCI SPORT EXER JI Med. Sci. Sports Exerc. PD AUG PY 2000 VL 32 IS 8 BP 1520 EP 1527 DI 10.1097/00005768-200008000-00023 PG 8 WC Sport Sciences SC Sport Sciences GA 342LJ UT WOS:000088645800023 PM 10949021 ER PT J AU Hartmann, MJ Assad, C Rasnow, B Bower, JM AF Hartmann, MJ Assad, C Rasnow, B Bower, JM TI Applications of video mixing and digital overlay to neuroethology SO METHODS-A COMPANION TO METHODS IN ENZYMOLOGY LA English DT Article DE animal tracking; data synchronization; video mixer; behavioral monitoring; whisking ID RAT AB Neuroethological experiments often require video images of animal behavior and recordings of physiological data to be acquired simultaneously, synchronized with each other, stored, and analyzed together. The use of inexpensive multimedia computers offers new possibilities for mixing video images, analog voltages, and computer data, storing these combined signals to videotape, and extracting quantitative data for analysis. In this paper, we summarize methods for mixing images from multiple video cameras and a Macintosh computer display to facilitate manipulation of data generated during our neurophysiological and behavioral research. These technologies enhance accuracy, speed, and flexibility during experiments, and facilitate selecting and extracting quantitative data from the videotape for further analysis. Three applications are presented: (A) we used an analog video mixer to synchronize neurophysiological recordings with ongoing behaviors of freely moving rats; (B) we used a chroma keyed digital overlay to generate positional data for the rat's face during drinking behavior; and (C) we combined a computer model of a rat's head and whiskers with videos of exploratory behaviors to better track and quantify movements in three dimensions. Although the applications described here are specific to our neuroethological work, these methods will be useful to anyone wishing to combine the signals from multiple video sources into a single image or to extract series of positional or movement data from video frames without frame grabbing. (C) 2000 Academic Press. C1 CALTECH, Dept Biol, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Amgen Inc, Thousand Oaks, CA 91320 USA. RP Hartmann, MJ (reprint author), CALTECH, Dept Biol, 216-76, Pasadena, CA 91125 USA. RI Hartmann, Mitra/A-8150-2008; Hartmann, Mitra/B-6766-2009; Bower, James/F-8343-2010 NR 9 TC 5 Z9 6 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 1046-2023 J9 METHODS JI Methods PD AUG PY 2000 VL 21 IS 4 BP 385 EP 391 DI 10.1006/meth.2000.1025 PG 7 WC Biochemical Research Methods; Biochemistry & Molecular Biology SC Biochemistry & Molecular Biology GA 343WH UT WOS:000088725100007 PM 10964581 ER PT J AU Ikebe, Y Leighly, K Tanaka, Y Nakagawa, T Terashima, Y Komossa, S AF Ikebe, Y Leighly, K Tanaka, Y Nakagawa, T Terashima, Y Komossa, S TI RXTE observation of NGC 6240: a search for the obscured active nucleus SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE galaxies : active; galaxies : individual : NGC 6240; galaxies : nuclei; galaxies : starburst; infrared : galaxies; X-rays : galaxies ID X-RAY-SPECTRA; INFRARED GALAXY NGC-6240; GALACTIC NUCLEI; ASCA OBSERVATIONS; MERGING GALAXIES; SEYFERT-GALAXIES; STARBURST; EMISSION; ABSORPTION; PLASMAS AB The wide-band energy spectrum of NGC 6240 over the range 0.5-200 keV is investigated using the RXTE and ASCA data. The RXTE data provide the spectrum beyond the ASCA range (0.5-10 keV) with significant detection of signals up to 30 keV and upper limits above 20 keV. The spectrum above 10 keV is found to be very flat. A strong iron K emission line discovered in the previous ASCA observation is also confirmed with the RXTE Proportional Counter Array (PCA), These results provide further evidence for the dominance of a reflection component, i.e, emission from cool material illuminated by an active galactic nucleus (AGN). By fitting the spectra obtained with RXTE and ASCA simultaneously, we satisfactorily modelled the AGN spectrum with a Compton reflection component and probably a transmitted AGN component penetrating through a thick absorber. The X-ray luminosity of the AGN is estimated to be in the range 4 x 10(43) to 6 x 10(44) erg s(-1) in the range 2-10 keV, which categorizes NGC 6240 among the most luminous Seyfert nuclei. The ratio of the 2-10 keV X-ray luminosity to the infrared luminosity, L-x(2-10 keV)/L-IR, is 0.01-0.1, which implies a quite substantial, if not dominant, contribution of AGN to the infrared luminosity. C1 Max Planck Inst Extraterr Phys, D-85741 Garching, Germany. Columbia Univ, Columbia Astrophys Lab, New York, NY 10027 USA. Inst Space & Astronaut Sci, Kanagawa 2298510, Japan. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ikebe, Y (reprint author), Max Planck Inst Extraterr Phys, Postfach 1312, D-85741 Garching, Germany. NR 53 TC 29 Z9 29 U1 0 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD AUG 1 PY 2000 VL 316 IS 2 BP 433 EP 441 DI 10.1046/j.1365-8711.2000.03514.x PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343HY UT WOS:000088698000019 ER PT J AU Menard, R Cohn, SE Chang, LP Lyster, PM AF Menard, R Cohn, SE Chang, LP Lyster, PM TI Assimilation of stratospheric chemical tracer observations using a Kalman filter. Part I: Formulation SO MONTHLY WEATHER REVIEW LA English DT Article ID ATMOSPHERIC DATA ASSIMILATION; ERROR COVARIANCE PARAMETERS; MAXIMUM-LIKELIHOOD-ESTIMATION; SIGNAL/ERROR CORRELATION; DISCRETIZATION ERROR; RESEARCH SATELLITE; SCHEMES; IMPLEMENTATION; FORECAST; PERFORMANCE AB The first part of this two-part article describes the formulation of a Kalman filter system for assimilating limb-sounding observations of stratospheric chemical constituents into a tracer transport model. The system is based on a two-dimensional isentropic approximation, permitting a full Kalman filter implementation and a thorough study of its behavior in a real-data environment. Datasets from two instruments on the Upper Atmosphere Research Satellite with very different viewing geometries are used in the assimilation experiments. A robust chi-squared diagnostic, which compares statistics of the observed-minus-forecast residuals with those calculated by the filter algorithm, is used to help formulate the statistical inputs to the filter, as well as to tune covariance parameters and to validate the assimilation results. Two significant departures from the standard (discrete) Kalman filter formulation were found to be important in this study. First, it was discovered that the standard Kalman filter covariance propagation is highly inaccurate for this problem. Spurious and rapid loss of variance and increase of correlation length scales occur as a result of diffusion of the small-scale structures inherent in tracer error covariance fields. A new formulation based on well-understood properties of the continuum error covariance propagation was therefore introduced. Second, validation diagnostics suggested that the initial error, model error, and representativeness error are all more appropriately assumed to be relative than absolute in this problem. A filter formulation for relative errors was therefore devised. With these two modifications, this Kalman filter assimilation system has only three tunable variance parameters and one tunable correlation length-scale parameter. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Catonsville, MD USA. RP Menard, R (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 910-3, Greenbelt, MD 20771 USA. EM menard@dao.gsfc.nasa.gov RI Cohn, Stephen/K-1954-2012 OI Cohn, Stephen/0000-0001-8506-9354 NR 52 TC 93 Z9 95 U1 0 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 EI 1520-0493 J9 MON WEATHER REV JI Mon. Weather Rev. PD AUG PY 2000 VL 128 IS 8 BP 2654 EP 2671 DI 10.1175/1520-0493(2000)128<2654:AOSCTO>2.0.CO;2 PN 1 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 346BD UT WOS:000088849600003 ER PT J AU Menard, R Changs, LP AF Menard, R Changs, LP TI Assimilation of stratospheric chemical tracer observations using a Kalman filter. Part II: chi(2)-validated results and analysis of variance and correlation dynamics SO MONTHLY WEATHER REVIEW LA English DT Article ID FORECAST; N2O AB A Kalman filter system designed for the assimilation of limb-sounding observations of stratospheric chemical tracers, which has four tunable covariance parameters, was developed in Part I of this two-part paper. The assimilation results of CH, observations from the Cryogenic Limb Array Etalon Sounder instrument (CLAES) and the Halogen Observation Experiment instrument (HALOE) on board the Upper Atmosphere Research Satellite are described in this paper. A robust chi(2) criterion, which provides a statistical validation of the forecast and observational error covariances, was used to estimate the tunable variance parameters of the system. In particular an estimate of the model error variance was obtained. The effect of model error on the forecast error variance became critical after only 3 days of assimilation of CLAES observations, although it took 14 days of forecast to double the initial error variance. Further, it was found that the model error due to numerical discretization, as arising in the standard Kalman filter algorithm, is comparable in size to the physical model error due to wind and transport modeling errors together. Separate assimilations of CLAES and HALOE observations were compared to validate the state estimate away from the observed locations. A wave breaking event that took place several thousands of kilometers away from the HALOE observation locations was well captured by the Kalman filter due to highly anisotropic forecast error correlations. The forecast error correlation in the assimilation of the CLAES observations was found to have a structure similar to that in pure forecast mode except for smaller length scales. Finally, an analysis of the variance and correlation dynamics was conducted to determine their relative importance in chemical tracer assimilation problems. Results show that the optimality of a tracer assimilation system depends, for the most part, on having flow-dependent error correlation rather than on evolving the error variance. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. RP Menard, R (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 910-3, Greenbelt, MD 20771 USA. NR 15 TC 62 Z9 64 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 AUG PY 2000 VL 128 IS 8 BP 2672 EP 2686 DI 10.1175/1520-0493(2000)128<2672:AOSCTO>2.0.CO;2 PN 1 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 346BD UT WOS:000088849600004 ER PT J AU Middleditch, J Kristian, JA Kunkel, WE Hill, KM Watson, RD Lucinio, R Imamura, JN Steiman-Cameron, TY Shearer, A Butler, R Redfern, M Danks, AC AF Middleditch, J Kristian, JA Kunkel, WE Hill, KM Watson, RD Lucinio, R Imamura, JN Steiman-Cameron, TY Shearer, A Butler, R Redfern, M Danks, AC TI Rapid photometry of supernova 1987A: a 2.14 ms pulsar? SO NEW ASTRONOMY LA English DT Review DE stars : neutron; pulsars : general; pulsars : individual : PSR1987A; supernovae : individual : SN1987A ID LARGE-MAGELLANIC-CLOUD; NEUTRON-STAR SYSTEMS; X-RAY PULSAR; MILLISECOND PULSAR; SN 1987A; OPTICAL PULSATIONS; GLOBULAR-CLUSTERS; GRAVITATIONAL-RADIATION; TELESCOPE OBSERVATIONS; FREE PRECESSION AB We have monitored Supernova 1987A in optical/near-infrared bands using various high-speed photometers from a few weeks following its birth until early 1996 in order to search for a pulsar remnant. While we have found no clear evidence of any pulsar of constant intensity and stable timing, we have found emission with a complex period modulation near the frequency of 467.5 Hz - a 2.14 ms pulsar candidate. We first detected this signal in data taken on the remnant at the Las Campanas Observatory (LCO) 2.5-m Dupont telescope during 14-16 Feb. 1992 UT. We detected further signals near the 2.14 ms period on numerous occasions over the next four years in data taken with a variety of telescopes, data systems and detectors, at a number of ground- and space-based observatories. In particular, an effort during mid-1993 to monitor this signal with the U. of Tasmania 1-m telescope, when SN1987A was inaccessible to nearly all other observing sites due to high airmass, clearly detected the 2.14 ms signal in the first three nights' observations. The sequence of detections of this signal from Feb. '92 through August '93, prior to its apparent subsequent fading, is highly improbable (<10(-10) for any noise source). In addition, the frequency of the signals followed a consistent and predictable spin-down (similar to 2-3 x 10(-10) Hz/s) over the several year timespan ('92-'96). We also find evidence in data, again taken by more than one telescope and recording system, for modulation of the 2.14 ms period with a similar to 1,000 s period which complicates its detection. The 1,000 s modulation was clearly detected in the first two observations with the U. Tas. 1-m during mid-1993. The characteristics of the 2.14 ms signature and its similar to 1,000 s modulation are consistent with precession and spindown via gravitational radiation of a neutron star with an effective non-axisymmetric oblateness of similar to 10(-6). The implied luminosity of the gravitational radiation exceeds the spindown luminosity of the Crab Nebula pulsar by an order of magnitude. Due to the nature of the 2.14 ms signature and its modulation, and the analysis techniques necessary for detection, it is difficult to determine the overall probability that all aspects of the signal are real, though it has remained consistent with an astrophysical origin throughout the several year timespan of our study. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Carnegie Inst Washington Observ, Pasadena, CA 91101 USA. Univ Tasmania, Sch Math & Phys, Hobart, Tas, Australia. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. Univ Oregon, Inst Theoret Sci, Eugene, OR 97403 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Natl Univ Ireland, Dept Informat Technol, Galway, Ireland. Natl Univ Ireland, Dept Phys, Galway, Ireland. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Middleditch, J (reprint author), Univ Calif Los Alamos Natl Lab, CIC-3,MS B256, Los Alamos, NM 87545 USA. RI Butler, Ray/A-6705-2012; Shearer, Andy/N-7609-2014 OI Butler, Ray/0000-0002-8441-7596; Shearer, Andy/0000-0001-7903-0074 NR 117 TC 41 Z9 41 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 1384-1092 J9 NEW ASTRON JI New Astron. PD AUG 1 PY 2000 VL 5 IS 5 BP 243 EP 283 DI 10.1016/S1384-1076(00)00024-5 PG 41 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349GA UT WOS:000089034200001 ER PT J AU Ahmed, S Sileno, AP deMeireles, JC Dua, R Pimplaskar, HK Xia, WJ Marinaro, J Langenback, E Matos, FJ Putcha, L Romeo, VD Behl, CR AF Ahmed, S Sileno, AP deMeireles, JC Dua, R Pimplaskar, HK Xia, WJ Marinaro, J Langenback, E Matos, FJ Putcha, L Romeo, VD Behl, CR TI Effects of pH and dose an nasal absorption of scopolamine hydrobromide in human subjects SO PHARMACEUTICAL RESEARCH LA English DT Article DE scopolamine; motion sickness; nasal absorption; pH effect; dose effect ID RATS AB Purpose. The present study was conducted to evaluate the effects of formulation pH and dose on nasal absorption of scopolamine hydrobromide, the single most effective drug available for the prevention of nausea and vomiting induced by motion sickness. Methods. Human subjects received scopolamine nasally at a dose of 0.2 mg/0.05 mL or 0.4 mg/0.10 mL, blood samples were collected at different time points, and plasma scopolamine concentrations were determined by LC-MS/MS. Results. Following administration of a 0.2 mg dose, the average C-max values were found to be 262 +/- 118, 419 +/- 161, and 488 +/- 331 pg/mL for pH 4.0, 7.0, and 9.0 formulations, respectively. At the 0.4 mg dose the average C-max values were found to be 503 +/- 199, 933 +/- 449, and 1,308 +/- 473 pg/mL for pH 4.0, 7.0, and 9.0 formulations, respectively. At a 0.2 mg dose, the AUC values were found to be 23,208 +/- 6,824, 29,145 +/- 9,225, and 25,721 +/- 5,294 pg.min/mL for formulation pH 4.0, 7.0, and 9.0, respectively. At a 0.4 mg dose, the average AUC value was found to be high for pH 9.0 formulation (70,740 +/- 29,381 pg.min/mL) as compared to those of pH 4.0 (59,573 +/- 13,700 pg.min/mL) and pH 7.0 (55,298 +/- 17,305 pg.min/mL) formulations. Both the C-max and AUC values were almost doubled with doubling the dose. On the other hand, the average T-max values decreased linearly with a decrease in formulation pH at both doses. For example, at a 0.4 mg dose, the average T-max values were 26.7 +/- 5.8, 15.0 +/- 10.0, and 8.8 +/- 2.5 minutes at formulation pH 4.0, 7.0, and 9.0, respectively. Conclusions. Nasal absorption of scopolamine hydrobromide in human subjects increased substantially with increases in formulation pH and dose. C1 Nastech Pharmaceut Co Inc, Hauppauge, NY 11788 USA. SUNY Stony Brook, Dept Pediat, Stony Brook, NY 11794 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Behl, CR (reprint author), Nastech Pharmaceut Co Inc, 45 Davids Dr, Hauppauge, NY 11788 USA. NR 17 TC 20 Z9 21 U1 0 U2 3 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0724-8741 J9 PHARMACEUT RES JI Pharm. Res. PD AUG PY 2000 VL 17 IS 8 BP 974 EP 977 DI 10.1023/A:1007551927177 PG 4 WC Chemistry, Multidisciplinary; Pharmacology & Pharmacy SC Chemistry; Pharmacology & Pharmacy GA 356ZM UT WOS:000089474100013 PM 11028944 ER PT J AU Boezio, M Carlson, P Francke, T Weber, N Suffert, M Hof, M Menn, W Simon, M Stephens, SA Bellotti, R Cafagna, F Circella, M De Marzo, C Finetti, N Papini, P Piccardi, S Spillantini, P Ricci, M Casolino, M De Pascale, MP Morselli, A Picozza, P Sparvoli, R Barbiellini, G Schiavon, P Vacchi, A Zampa, N Grimani, C Mitchell, JW Ormes, JF Streitmatter, RE Bravar, U Golden, RL Stochaj, SJ AF Boezio, M Carlson, P Francke, T Weber, N Suffert, M Hof, M Menn, W Simon, M Stephens, SA Bellotti, R Cafagna, F Circella, M De Marzo, C Finetti, N Papini, P Piccardi, S Spillantini, P Ricci, M Casolino, M De Pascale, MP Morselli, A Picozza, P Sparvoli, R Barbiellini, G Schiavon, P Vacchi, A Zampa, N Grimani, C Mitchell, JW Ormes, JF Streitmatter, RE Bravar, U Golden, RL Stochaj, SJ TI Measurement of the flux of atmospheric muons with the CAPRICE94 apparatus SO PHYSICAL REVIEW D LA English DT Article ID COSMIC-RAY PROTON; HELIUM SPECTRA; NEUTRINO FLUXES; RICH DETECTOR; GROUND-LEVEL; SEA-LEVEL; SPECTROMETER; PERFORMANCE; RATIO AB A new measurement of the momentum spectra of both positive and negative muons as a function of atmospheric depth was made by the balloon-borne experiment CAPRICE93. The data were collected during ground runs in Lynn Lake on 19 and 20 July 1994 and during the balloon flight on 8 and 9 August 1994. We present results that cover the momentum intervals 0.3-40 GeV/c for mu(-) and 0.3-2 GeV/c for mu(+), for atmospheric depths from 3.3 to 1000 g/cm(2), respectively. Good agreement is found with previous measurements for high momenta, while at momenta below 1 GeV/c we find latitude dependent geomagnetic effects. These measurements are important cross-checks for the simulations carried out to calculate the atmospheric neutrino fluxes and to understand the observed atmospheric neutrino anomaly. C1 Royal Inst Technol, KTH, S-10405 Stockholm, Sweden. Ctr Rech Nucl, F-67037 Strasbourg, France. Univ Siegen, D-57068 Siegen, Germany. Tata Inst Fundamental Res, Bombay 400005, Maharashtra, India. Univ Bari, Dipartimento Fis, I-70126 Bari, Italy. Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy. Univ Florence, Dipartimento Fis, I-50125 Florence, Italy. Ist Nazl Fis Nucl, Sez Firenze, I-50125 Florence, Italy. Ist Nazl Fis Nucl, Nazl Frascati Lab, I-00044 Frascati, Italy. Univ Roma Tor Vergata, Dipartimento Fis, I-00133 Rome, Italy. Ist Nazl Fis Nucl, Sez Roma, I-00133 Rome, Italy. Univ Trieste, Dipartimento Fis, I-34147 Trieste, Italy. Ist Nazl Fis Nucl, Sez Trieste, I-34147 Trieste, Italy. Univ Urbino, Ist Fis, I-61029 Urbino, Italy. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. New Mexico State Univ, Las Cruces, NM 88003 USA. RP Boezio, M (reprint author), Royal Inst Technol, KTH, S-10405 Stockholm, Sweden. EM mirko.boezio@trieste.infn.it RI Morselli, Aldo/G-6769-2011; Cafagna, Francesco/A-9299-2010; Vacchi, Andrea/C-1291-2010; OI Morselli, Aldo/0000-0002-7704-9553; Cafagna, Francesco/0000-0002-7450-4784; Vacchi, Andrea/0000-0003-3855-5856; Boezio, Mirko/0000-0002-8015-2981 NR 41 TC 42 Z9 43 U1 1 U2 7 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 AUG 1 PY 2000 VL 62 IS 3 AR 032007 DI 10.1103/PhysRevD.62.032007 PG 15 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 340CV UT WOS:000088516300010 ER PT J AU Frieman, JA Szalay, AS AF Frieman, JA Szalay, AS TI Large-scale structure: entering the precision era SO PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS LA English DT Review ID COLD DARK-MATTER; COSMOLOGICAL DENSITY PERTURBATIONS; INFLATIONARY UNIVERSE SCENARIO; 3-POINT CORRELATION-FUNCTION; GALAXY CORRELATION-FUNCTIONS; CAMPANAS REDSHIFT SURVEY; LYMAN-BREAK GALAXIES; POWER SPECTRUM; FLUCTUATIONS; STATISTICS AB In recent years, the framework for a plausible theory of large-scale structure formation has emerged: primordial, quasi-scale-invariant perturbations from inflation, which subsequently grow by gravitational instability in a universe with a substantial component of cold dark matter. At the same time, with the development of large galaxy surveys, the precision of statistical measurements of large-scale structure has begun to improve rapidly. In the near future, a new generation of surveys, along with cosmic microwave background missions and other cosmological probes, will probe this structure formation paradigm and ultimately provide clues to the dynamics of inflation itself. This chapter highlights recent progress and expected future developments in our understanding of large-scale structure and in testing the inflationary scenario for its formation. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Fermilab Astrophys Ctr, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RP NASA, Fermilab Astrophys Ctr, Fermi Natl Accelerator Lab, POB 500, Batavia, IL 60510 USA. EM frieman@fnal.gov NR 85 TC 3 Z9 3 U1 0 U2 0 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 AUG PY 2000 VL 333 IS 1-6 BP 215 EP 232 DI 10.1016/S0370-1573(00)00045-4 PG 18 WC Physics, Multidisciplinary SC Physics GA 336AW UT WOS:000088280600015 ER PT J AU Turner, MS AF Turner, MS TI The dark side of the universe: from Zwicky to accelerated expansion SO PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS LA English DT Review ID BIG-BANG NUCLEOSYNTHESIS; STRING-DOMINATED UNIVERSE; COSMOLOGICAL CONSTANT; SUPERNOVAE; ENERGY; DEUTERIUM; COMPONENT; MATTER; LAMBDA; OMEGA AB More than 60 years ago Zwicky made the case that the great clusters of galaxies are held together by the gravitational force of unseen (dark) matter. Today, the case is stronger and more precise: dark, nonbaryonic matter accounts for 30 +/- 7% of the critical mass density, with baryons (most of which are dark) contributing only 4.5 +/- 1% of the critical density. The large-scale structure that exists in the universe indicates that the bulk of the nonbaryonic dark matter must be cold (slowly moving particles). The SuperKamiokande detection of neutrino oscillations shows that particle dark matter, in the form of massive neutrinos, actually exists and accounts for as much mass as bright stars. An important threshold has been crossed; particle dark matter is no longer hypothetical. Over the past few years a case has developed for dark energy. This dark, relativistic component contributes about 80 +/- 20% of the critical density and is characterized by very negative pressure (p(X) < - 0.6 rho(X)). Consistent with this picture of dark energy and dark matter are measurements of CMB anisotropy that indicate that, matter and energy together account for the critical density (within 10%). Fundamental physics beyond the standard model is implicated in both the dark matter and dark energy puzzles: new fundamental particles (e.g., axion or neutralino) and new forms of relativistic energy (e.g., vacuum energy or a light scalar field). Dark matter and dark energy are central issues in both cosmology and particle physics. Over the next two decades a flood of precision cosmological observations and laboratory experiments will shed light on the dark side of the universe. As they do they will advance our understanding of both the universe and the laws of physics that govern it. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Chicago, Dept Astron & Astrophys, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Chicago, Dept Phys, Enrico Fermi Inst, Chicago, IL 60637 USA. NASA, Fermilab Astrophys Ctr, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. RP Turner, MS (reprint author), Univ Chicago, Dept Astron & Astrophys, Enrico Fermi Inst, 5640 S Ellis Ave, Chicago, IL 60637 USA. NR 51 TC 60 Z9 60 U1 2 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0370-1573 J9 PHYS REP JI Phys. Rep.-Rev. Sec. Phys. Lett. PD AUG PY 2000 VL 333 IS 1-6 BP 619 EP 635 DI 10.1016/S0370-1573(00)00040-5 PG 17 WC Physics, Multidisciplinary SC Physics GA 336AW UT WOS:000088280600033 ER PT J AU Morrison, D AF Morrison, D TI Moon yields info on near-earth asteroids SO PHYSICS TODAY LA English DT Letter C1 NASA, Ames Res Ctr, Mt View, CA USA. RP Morrison, D (reprint author), NASA, Ames Res Ctr, Mt View, CA USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0031-9228 J9 PHYS TODAY JI Phys. Today PD AUG PY 2000 VL 53 IS 8 BP 14 EP 14 DI 10.1063/1.1310113 PN 1 PG 1 WC Physics, Multidisciplinary SC Physics GA 339XE UT WOS:000088502500013 ER PT J AU Greeley, R Klemaszewski, JE Wagner, R AF Greeley, R Klemaszewski, JE Wagner, R CA Galileo Imaging Team TI Galileo views of the geology of Callisto SO PLANETARY AND SPACE SCIENCE LA English DT Article DE Callisto; outer planet satellites; icy moons; multi-ring impacts ID DOME CRATERS; SATELLITES; GANYMEDE; JUPITER; SURFACES; MISSION; FIELDS; EUROPA; SYSTEM; ORBIT AB Callisto was imaged by the Galileo spacecraft on 10 orbits, half of which involved close flybys, producing images with resolutions as high as 15 m/pixel. The Valhalla, Asgard, and Adlinda multi-ring structures were imaged, along with two features which might also be large impacts, Utgard and Heimdall (both provisionally named). The high albedo interior zones of these structures are relatively rugged and include small knobs. The interior ring zone of Valhalla includes outward facing scarps, as discovered on Voyager images, while the inner zones of the other, smaller multi-ring structures include grabens and inward facing scarps. The outer ring zones consist of grabens which are sinuous and include multiple parallel faults and fractures. High albedo areas associated with the fractures had been suggested previously as resurfacing zones; they are now seen to consist of numerous, closely spaced fractures. Crater size frequency distributions for the units associated with multi-ring structures suggest that all were formed essentially contemporaneously with their respective impact events. Galileo images show that surface degradation occurs on a variety of scales, including large landslides from the rims of craters and apparent sub-decameter surface modifications, leading to the removal of small carters in some areas. Similar styles of degradation ale not observed on Ganymede, suggesting fundamental differences in the properties of the surface materials. Catenae (crater chains) were also observed; some appear to be secondaries in which their primary source crater can be identified, while others are probably the result of the breakup of primary objects, as previously proposed. Although most of Callisto's surface consists of ancient cratered plains, some small 'smooth' areas had been suggested to result from cryovolcanic resurfacing. Representative bright and dark areas were viewed in high resolution; bright areas were found to be rugged at the 10s of meters scale, show no indications of how features, and are not considered to be cryovolcanic. Some smooth dark areas appear to mantle and embay the surrounding cratered plains. Although this is consistent with possible cryovolcanic processes, it is not definitive evidence of endogenic processes. The extension of imaging data, both in coverage and resolution, enable about 90% of the surface to be mapped photogeologically and gives new insight into the nature of surface features and the timing of their development. Cratered plains form the oldest recognizable unit on Callisto, but subtle differences in color and crater frequencies suggest regional differences in its development. The formation of Adlinda, Asgard, Valhalla, Heimdall, and Lofn crater appear to follow in that order. The morphology of associated features is consistent with a differentiated interior for Callisto and the presence of a thin icy lithosphere at the time of the impacts. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. Deutsch Zentrum Luft & Raumfahrt, Standort Berlin Adlershof, D-12489 Berlin, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Greeley, R (reprint author), Arizona State Univ, Dept Geol, Box 871404, Tempe, AZ 85287 USA. NR 70 TC 29 Z9 32 U1 0 U2 7 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 AUG PY 2000 VL 48 IS 9 BP 829 EP 853 DI 10.1016/S0032-0633(00)00050-7 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 346UV UT WOS:000088890200007 ER PT J AU Scheeres, DJ Khushalani, B Werner, RA AF Scheeres, DJ Khushalani, B Werner, RA TI Estimating asteroid density distributions from shape and gravity information SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 7th International Asteroids, Comets, Meteors Conference (ACM 99) CY JUL 26-30, 1999 CL CORNELL UNIV, ITHACA, NEW YORK HO CORNELL UNIV DE eros; NEAR; polyhedral gravity field; density distribution AB A least-squares approach for estimating the internal density distribution of an asteroid is presented and applied to a simple polyhedron asteroid shape. The method assumes that the asteroid gravity field is measured to a specified degree and order and that a polyhedral model of the asteroid is available and has been discretized into a finite number of constant density polyhedra. The approach is derived using several basic properties of spherical harmonic gravitational expansions and can explicitly accommodate a fully correlated covariance matrix for the estimated gravity field. For an asteroid shape discretized into M constant density polyhedra and a gravity field measured to degree and order N, the least-squares problem is under-determined if M > (N+1)(2) and is over-determined if M < (N+1)(2). For both cases a singular-value decomposition (SVD) approach will yield solutions. We apply our approach to a number of ideal test situations using an asteroid shape consisting of 508 tetrahedra. We show that the under-determined case is sensitive to non-uniform density distributions. The over-determined case shows very good performance independent of the initial density distribution guess. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Michigan, Dept Aerosp Engn, Ann Arbor, MI 48109 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Scheeres, DJ (reprint author), Univ Michigan, Dept Aerosp Engn, Ann Arbor, MI 48109 USA. NR 10 TC 16 Z9 16 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD AUG PY 2000 VL 48 IS 10 BP 965 EP 971 DI 10.1016/S0032-0633(00)00064-7 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 370HQ UT WOS:000165117800012 ER PT J AU Ozernoy, LM Gorkavyi, NN Taidakova, T AF Ozernoy, LM Gorkavyi, NN Taidakova, T TI Four cometary belts associated with the orbits of giant planets: a new view of the outer solar system's structure emerges from numerical simulations SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 7th International Asteroids, Comets, Meteors Conference (ACM 99) CY JUL 26-30, 1999 CL CORNELL UNIV, ITHACA, NEW YORK HO CORNELL UNIV ID KUIPER-BELT AB Using numerical simulations, we examine the structure of a cometary population near a massive planet, such as a giant planet of the Solar system, starting with one-planet approximation (the Sun plus one planet). By studying the distributions of comets in semimajor axis, eccentricity, pericenter, and apocenter distances, we have revealed several interesting features in these distributions. The most remarkable ones include (i) spatial accumulation of comets near the planetary orbit (which we call the 'cometary, belt') and (ii) avoidance of resonant orbits by comets. Then we abandon one-planet approximation and examine as to how a cometary belt is modified when the influence of all the four giant planets is taken into consideration. To this end, we simulate a stationary distribution of comets, which results from the gravitational scattering of the Kuiper belt objects on the four giant planets and accounts for the effects of mean-motion resonances. In our simulations, we deal with the stationary distributions computed, at different initial conditions, as 36 runs for the dynamical evolution of comets, which start from the Kuiper belt and are typically traced until the comets are ejected from the Solar system. Accounting for the influence of four giant planets makes the cometary belts overlapping, but nevertheless keeping almost all their basic features found in one-planet approximation. In particular, the belts maintain the gaps in the (a,e)- and (a, i)-space similar to the Kirkwood gaps in the main asteroid belt. We conclude that the large-scale structure of the Solar system is featured by the four cometary belts expected to contain 20-30 millions of scattered comets, and only a tiny fraction of them is currently visible as Jupiter, Saturn, etc. family comets. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Crimean Astrophys Observ, Simeiz Dept, UA-334242 Simeiz, Ukraine. Computat Consulting Serv, College Pk, MD 20740 USA. George Mason Univ, Computat Sci Inst, Dept Phys & Astron, Fairfax, VA 22030 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Ozernoy, LM (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. NR 10 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 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD AUG PY 2000 VL 48 IS 10 BP 993 EP 1003 DI 10.1016/S0032-0633(00)00068-4 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 370HQ UT WOS:000165117800016 ER PT J AU Hay, SI Myers, MF Burke, DS Vaughn, DW Endy, T Ananda, N Shanks, GD Snow, RW Rogers, DJ AF Hay, SI Myers, MF Burke, DS Vaughn, DW Endy, T Ananda, N Shanks, GD Snow, RW Rogers, DJ TI Etiology of interepidemic periods of mosquito-borne disease SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID NINO SOUTHERN OSCILLATION; DENGUE HEMORRHAGIC-FEVER; EL-NINO; TRANSMISSION DYNAMICS; EPIDEMIC MALARIA; CLIMATE; EVOLUTION; KENYA; PERSISTENCE; MORBIDITY AB Dengue viruses and malaria protozoa are of increasing global concern in public health. The diseases caused by these pathogens often show regular seasonal patterns in incidence because of the sensitivity of their mosquito vectors to climate. Between years in endemic areas, however, there can be further significant variation in case numbers for which public health systems are generally unprepared. There is an acute need for reliable predictions of within-year and between-year epidemic events. The prerequisite for developing any system of early warning is a detailed understanding of the factors involved in epidemic genesis. In this report we discuss the potential causes of the interepidemic periods in dengue hemorrhagic fever in Bangkok and of Plasmodium falciparum malaria in a highland area of western Kenya. The alternative causes are distinguished by a retrospective analysis of two unique and contemporaneous 33-year time series of epidemiological and associated meteorological data recorded at these two sites. We conclude that intrinsic population dynamics offer the most parsimonious explanation for the observed interepidemic periods of disease in these locations. C1 Univ Oxford, Dept Zool, Trypanosomiasis & Land Use Africa Res Grp, Oxford OX1 3PS, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Sch Hyg & Publ Hlth, Dept Int Hlth, Baltimore, MD 21205 USA. Walter Reed Army Inst Res, Dept Virus Dis, Silver Spring, MD 20910 USA. Armed Forces Res Inst Med Sci, Dept Virol, Bangkok 10400, Thailand. USA, Med Res Unit Kenya, Nairobi, Kenya. Kenya Med Res Inst, Wellcome Trust Collaborat Program, Nairobi, Kenya. Univ Oxford, John Radcliffe Hosp, Ctr Trop Med, Oxford OX3 9DU, England. RP Hay, SI (reprint author), Univ Oxford, Dept Zool, Trypanosomiasis & Land Use Africa Res Grp, S Parks Rd, Oxford OX1 3PS, England. RI Hay, Simon/F-8967-2015; Shanks, George Dennis/F-4056-2014; OI Hay, Simon/0000-0002-0611-7272; Shanks, George Dennis/0000-0001-5763-8660; /0000-0002-5704-8094 FU Wellcome Trust [056642] NR 56 TC 144 Z9 147 U1 3 U2 13 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA SN 0027-8424 J9 P NATL ACAD SCI USA JI Proc. Natl. Acad. Sci. U. S. A. PD AUG 1 PY 2000 VL 97 IS 16 BP 9335 EP 9339 DI 10.1073/pnas.97.16.9335 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 341UL UT WOS:000088608000102 PM 10922081 ER PT J AU Jarrett, TH AF Jarrett, TH TI Near-infrared galaxy morphology atlas SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID VIRGO CLUSTER; HUBBLE SEQUENCE; DWARF GALAXIES; H-I; PARAMETERS; COMPACT AB We present a representative sample of near-infrared (1-2 mu m) images spanning the Hubble galaxy morphology classification sequence. The images come from the Two Micron All-Sky Survey, with a range in brightness of 7 mag < K(s) < 13.5 mag, and the morphological classifications from the NASA/IPAC Extragalactic Database. We differentiate between elliptical, normal, and barred spirals, compact, dwarf, peculiar, and active galactic nucleus/Seyfert-type galaxies. This image atlas serves as a qualitative guide to the appearance of galaxies at wavelengths that penetrate the obscuring veil of dust, as well as provides a window to the older population of stars that dominate the observed light at 2 mu m, including large-scale bar features. We show that central surface brightness and integrated flux may be used to discriminate spheroid and early-type spirals from late-type spirals. The optical and near-infrared properties are compared. C1 CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. RP Jarrett, TH (reprint author), CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, MS 100-22, Pasadena, CA 91125 USA. EM jarrett@ipac.caltech.edu NR 38 TC 50 Z9 53 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 AUG PY 2000 VL 112 IS 774 BP 1008 EP 1080 DI 10.1086/316603 PG 73 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 344TK UT WOS:000088774800003 ER PT J AU Yasuda, H Fujitaka, K AF Yasuda, H Fujitaka, K TI Non-linearity of the high temperature peak area ratio of (LiF)-Li-6 : Mg, Ti (TLD-600) SO RADIATION MEASUREMENTS LA English DT Article ID FLIGHT; SPACE; TLDS AB Thermoluminescent dosemeters of (LiF)-Li-6:Mg,Ti (TLD-600) were exposed to high-energy heavy ion beams (He, C, Ne, and Ar) and Cs-137 gamma-rays and the glow curves were analyzed. The height of the main peak (peak 5) at about 200 degrees C slightly increased for He from gamma-rays and decreased for heavier ions with increasing Linear Energy Transfer (LET). Whereas the high temperature peak (peak 7) area around 260 degrees C simply increased. Non-linearity was seen between the LET and the high temperature peak (peak 7) area ratio (HTR) which was calculated as the TL integrated over 225-275 degrees C from the peak 5 normalized glow curve. Based on these results, average LET and quality factor were estimated for an assumed LET spectra of space radiation by using the HTR method. Considerable differences were found between these estimations and true values. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Natl Inst Radiol Sci, Inage Ku, Chiba 2638555, Japan. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Natl Inst Radiol Sci, Inage Ku, Chiba 2638555, Japan. EM h_yasuda@nirs.go.jp NR 11 TC 12 Z9 12 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1350-4487 J9 RADIAT MEAS JI Radiat. Meas. PD AUG PY 2000 VL 32 IS 4 BP 355 EP 360 DI 10.1016/S1350-4487(00)00069-X PG 6 WC Nuclear Science & Technology SC Nuclear Science & Technology GA 346HC UT WOS:000088864100012 ER PT J AU Komjathy, A Zavorotny, VU Axelrad, P Born, GH Garrison, JL AF Komjathy, A Zavorotny, VU Axelrad, P Born, GH Garrison, JL TI GPS signal scattering from sea surface: Wind speed retrieval using experimental data and theoretical model SO REMOTE SENSING OF ENVIRONMENT LA English DT Article; Proceedings Paper CT 50th International Conference on Remote Sensing for Marine and Coastal Environments CY OCT 05-07, 1998 CL SAN DIEGO, CALIFORNIA SP ERIM Int Inc ID SPECTRUM; SYSTEM AB Global Positioning System (GPS) signals reflected from the ocean surface have potential use for various remote sensing purposes. Some possibilities are measurements of surface roughness characteristics from which wave height, wind speed, and direction could be determined. For this paper; GPS-reflected signal measurements collected at aircraft altitudes of 2 km to 5 km with delay-Doppler mapping GPS receiver are used to explore the possibility of determining wind speed. To interpret the GPS data, a theoretical model has been developed that describes the power. of the reflected CPS signals for different time delays and Doppler frequencies as a function of geometrical and environmental parameters. The results indicate a good agreement between the measured and the modeled normalized signal power waveforms during changing surface wind conditions. The estimated rr,ind spc en using surface-reflected GPS data, obtained by comparing actual and modeled waveforms, shows good ;agreement (within 2 m/s) with delta obtained from a nearby buoy and independent wind speed measurements derived from the TOPEX/Poseidon altimetric satellite. (C)Elsevier Science Inc., 2000. C1 Univ Colorado, CCAR, Boulder, CO 80309 USA. Univ Colorado, CIRES, NOAA, ETL, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Komjathy, A (reprint author), Univ Colorado, CCAR, Campus Box 431, Boulder, CO 80309 USA. NR 20 TC 53 Z9 59 U1 0 U2 5 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD AUG PY 2000 VL 73 IS 2 BP 162 EP 174 DI 10.1016/S0034-4257(00)00091-2 PG 13 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 335ZM UT WOS:000088277200006 ER PT J AU Garrison, JL Katzberg, SJ AF Garrison, JL Katzberg, SJ TI The application of reflected GPS signals to ocean remote sensing SO REMOTE SENSING OF ENVIRONMENT LA English DT Article; Proceedings Paper CT 50th International Conference on Remote Sensing for Marine and Coastal Environments CY OCT 05-07, 1998 CL SAN DIEGO, CALIFORNIA SP ERIM Int Inc ID SEA AB The L-band broadcast signal from the Global Positioning System (GPS) reflected off of the sea surface is under study for use as a ocean, coastal, and wetlands remote sensing tool. The reflected signal from a given GPS satellite is cross-correlated with the pseudorandom noise code uniquely identifying that satellite. The shape of this cross-correlation, ordinarily, a very sharp triangle when tracking a direct line of sight signal, becomes wider and smoother as the mean square slope of the reflecting surface increases. It is proposed that the surface wind speed can be determined by matching the recorded shape of this cross-correlation to that predicted by theoretical models as a function od wind speed and direction. The significance of these effects increases with altitude of the receiver. Experimental data have been collected using a specially modified GPS receiver on aircraft and on a balloon at altitudes of up to 25 km. these data compare favorably with predictions of analytical models and demonstrate the dependence of the waveform shape on surface wind speed and receiver altitude. The advantages that this measurement technique has over conventional scatterometers is the small size, low cost and simplicity of the receiver hardware, no requirement for a transmitter, and the ability to simultaneously collect data from usually 10 or more points (from a low earth-orbiting satellite). This number could be larger if the Russian Global Navigation Satellite System satellites are also considered as additional sources of radiation. Furthermore, the bistatic scattering geometry is complementary to the backscatter used by conventional scatterometers. Published by Elsevier Science Inc. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Garrison, JL (reprint author), NASA, Goddard Space Flight Ctr, Code 572, Greenbelt, MD 20771 USA. NR 13 TC 31 Z9 34 U1 2 U2 9 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD AUG PY 2000 VL 73 IS 2 BP 175 EP 187 DI 10.1016/S0034-4257(00)00092-4 PG 13 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 335ZM UT WOS:000088277200007 ER PT J AU Hwang, PA Krabill, WB Wright, W Swift, RN Walsh, EJ AF Hwang, PA Krabill, WB Wright, W Swift, RN Walsh, EJ TI Airborne scanning lidar measurement of ocean waves SO REMOTE SENSING OF ENVIRONMENT LA English DT Article; Proceedings Paper CT 50th International Conference on Remote Sensing for Marine and Coastal Environments CY OCT 05-07, 1998 CL SAN DIEGO, CALIFORNIA SP ERIM Int Inc ID GREENLAND ICE-SHEET; WHITECAP COVERAGE; LASER ALTIMETRY; SPECTRA AB A scanning lidar system provides high-resolution three-dimensional measurements of ocean wave displacement. The airborne operation further enhances the speed of data acquisition. These properties allow rapid characterization of the ocean wave environment. In addition to active ranging, the scanning optics can obtain passive measurements of surface emissivity, yielding a digital image of surface brightness in real time. Processed into a binary image, these measurements can provide information on the average statistics and the spatial distribution of breaking waves. Technical specifications of the system and examples of application are presented. Published by Elsevier Science Inc. C1 USN, Res Lab, Div Oceanog, Stennis Space Ctr, MS USA. NASA, Goddard Space Flight Ctr, Lab Hydrospheric Proc, Wallops Island, VA 23337 USA. EG&G Serv Inc, Wallops Flight Facil, Wallops Island, VA USA. RP Hwang, PA (reprint author), USN, Res Lab, Div Oceanog, Stennis Space Ctr, MS USA. NR 17 TC 14 Z9 14 U1 0 U2 4 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD AUG PY 2000 VL 73 IS 2 BP 236 EP 246 DI 10.1016/S0034-4257(00)00098-5 PG 11 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 335ZM UT WOS:000088277200013 ER PT J AU Sparling, LC AF Sparling, LC TI Statistical perspectives on stratospheric transport SO REVIEWS OF GEOPHYSICS LA English DT Review ID ATMOSPHERE RESEARCH SATELLITE; POLAR VORTEX; DATA ASSIMILATION; TRACER TRANSPORT; AEROSOL; MODELS; CLIMATOLOGY; AIRCRAFT; HALOE; AREA AB Many long-lived stratospheric chemical constituents enter the stratosphere through the tropical tropopause, are transported throughout the stratosphere by the Brewer-Dobson circulation, and are photochemically destroyed in the upper stratosphere. These chemical constituents, or "tracers," can be used to track mixing and transport by the stratospheric winds. Much of our understanding about the stratospheric circulation is based on large-scale gradients and other spatial features in tracer fields constructed from satellite measurements. The point of view presented in this paper is different, but complementary, in that transport is described ill terms of tracer probability distribution functions. The probability distribution function is computed from the measurements and is proportional to the area occupied by tracer values in a given range. The flavor of this paper is tutorial, and the ideas are illustrated with several examples of transport-related phenomena, annotated with remarks that summarize the main point or suggest new directions. The examples illustrate how physically based statistical analysis can shed some light on aspects of stratospheric transport and dynamics that may not be obvious or quantifiable with other types of analyses. The dependence of the statistics on location and time is also shown to be important for practical problems related to statistical robustness and satellite sampling. An important motivation for the work presented here is the need for synthesis of the large and growing database of observations of the atmosphere and output generated by atmospheric models. C1 Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. NASA, Goddard Space Flight Ctr, Atmospher Chem & Dynam Branch, Greenbelt, MD 20771 USA. RP Sparling, LC (reprint author), Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. NR 47 TC 66 Z9 66 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 8755-1209 J9 REV GEOPHYS JI Rev. Geophys. PD AUG PY 2000 VL 38 IS 3 BP 417 EP 436 DI 10.1029/1999RG000070 PG 20 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 344GM UT WOS:000088750900004 ER PT J AU Tabib-Azar, M Sutapun, B Srikhirin, T Lando, J Adamovsky, G AF Tabib-Azar, M Sutapun, B Srikhirin, T Lando, J Adamovsky, G TI Fiber optic electric field sensors using polymer-dispersed liquid crystal coatings and evanescent field interactions SO SENSORS AND ACTUATORS A-PHYSICAL LA English DT Article DE fiber optic; polymer-dispersed liquid crystal; refractive index AB We report a simple evanescent field fiber optic electric field sensor constructed by coating the exposed fiber optic core with a polymer-dispersed liquid crystal (PDLC). It is well known that the effective refractive index of the liquid-crystal polymers has a large dependence on the direction and the magnitude of an applied electric field. This dependence was large enough in our devices to enable simple transmission measurements to detect the presence of an applied electric field across the fiber optic. The sensors showed good sensitivity and reproducibility with its response dominated by the RC time constant of the structure rather than the response of the PDLC. Its response time was approximately 3 min with 15-20 min relaxation time. Using an electric circuit model of the device, we also discuss how the sensor's response time can be improved by many orders of magnitude. (C) 2000 Elsevier Science S.A. All rights reserved. C1 Case Western Reserve Univ, Dept Phys, Cleveland, OH 44106 USA. Case Western Reserve Univ, Dept Syst & Comp Engn, Cleveland, OH 44106 USA. Case Western Reserve Univ, Dept Macromol Sci, Cleveland, OH 44106 USA. NASA, Lewis Res Ctr, Cleveland, OH 44118 USA. RP Tabib-Azar, M (reprint author), Case Western Reserve Univ, Dept Phys, Room 517,Glennan Bldg, Cleveland, OH 44106 USA. NR 12 TC 16 Z9 16 U1 0 U2 8 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0924-4247 J9 SENSOR ACTUAT A-PHYS JI Sens. Actuator A-Phys. PD AUG 1 PY 2000 VL 84 IS 1-2 BP 134 EP 139 DI 10.1016/S0924-4247(99)00352-0 PG 6 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 339HJ UT WOS:000088471400018 ER PT J AU Morford, RV Kellam, EC Hofmann, MA Baldwin, R Allcock, HR AF Morford, RV Kellam, EC Hofmann, MA Baldwin, R Allcock, HR TI A fire-resistant organophosphorus gel polymer electrolyte additive for use in rechargeable lithium batteries SO SOLID STATE IONICS LA English DT Article DE lithium batteries; gel polymer electrolytes; additive; propylene carbonate; conductivity AB The development of a small-molecule organophosphorus gel polymer electrolyte additive for use in rechargeable lithium batteries is described. This organophosphorus additive is less volatile and more resistant to ignition than propylene carbonate, a well known component of gel polymer electrolytes. Moreover, the ionic conductivities of gels containing the organophosphorus additive at low molar concentrations (11-21%) exceed the ionic conductivities of gels containing equimolar amounts of propylene carbonate (5.3 x 10(-5) versus 4.8 x 10(-5) S/cm). At higher molar concentrations (31-52%) there is evidence of phase separation, but conductivities remain comparable to propylene carbonate systems. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Penn State Univ, Dept Chem, University Pk, PA 16802 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Allcock, HR (reprint author), Penn State Univ, Dept Chem, 152 Davey Lab, University Pk, PA 16802 USA. NR 14 TC 27 Z9 27 U1 1 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-2738 J9 SOLID STATE IONICS JI Solid State Ion. PD AUG PY 2000 VL 133 IS 3-4 BP 171 EP 177 DI 10.1016/S0167-2738(00)00741-4 PG 7 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA 365UD UT WOS:000089968100004 ER PT J AU Landis, GA AF Landis, GA TI An all-woman crew to Mars: a radical proposal SO SPACE POLICY LA English DT Editorial Material AB It is logical to propose that if a human mission is flown to Mars, it should be composed of an entirely female crew. On the average, women have lower mass and take less volume than males, and use proportionately less consumables. In addition, sociological research indicates that a female crew may have a preferable interpersonal dynamic, and be likely to choose non-confrontational approaches to solve interpersonal problems. (C) 2000 Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Ohio Aerosp Inst, Cleveland, OH 44135 USA. RP Landis, GA (reprint author), NASA, Ohio Aerosp Inst, Glenn Mailstop 302-1,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 8 TC 1 Z9 1 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0265-9646 J9 SPACE POLICY JI Space Policy PD AUG PY 2000 VL 16 IS 3 BP 167 EP 169 DI 10.1016/S0265-9646(00)00020-5 PG 3 WC International Relations; Social Sciences, Interdisciplinary SC International Relations; Social Sciences - Other Topics GA 343VQ UT WOS:000088723500002 PM 11543564 ER PT J AU Garshnek, V Morrison, D Burkle, FM AF Garshnek, V Morrison, D Burkle, FM TI The mitigation, management, and survivability of asteroid/comet impact with Earth SO SPACE POLICY LA English DT Article DE near Earth object; impact; disaster management; global catastrophe ID ATMOSPHERE; FRAGMENTATION; COMETS AB The chances that Earth will collide with a significant near earth object (NEO) within the next century are very small, but such a collision is possible, would be catastrophic, and could happen at any time. Much discussion has been devoted to methods of diverting these objects away from Earth through the use of space technology. However, if these efforts are unsuccessful, we would need to implement effective strategies to survive the event, no matter how cataclysmic. To date, disaster management for various impact scenarios has not been addressed (except in novels and Hollywood films). An impact disaster may be many orders of magnitude greater than any disaster the human species has ever experienced. Initially, technology and experience gained in other large-scale disasters will most likely form the foundation of how these impact events will be managed and classified. Given the size and energy of the projectile, the estimated area of damage, and whether impact effects might be localized or global in nature, we can begin to build basic disaster response scenarios, anticipate public health concerns, and formulate questions in need of answers. Questions we must deal with include: what will be required technologically, sociologically, and medically to survive? What types of evacuation plans and warning systems might be required? Capabilities in need of further investigation include: technological protection strategies related to 'impact winter', expanded chemical hazard control methodologies, food storage and production, roles of national governments, and international cooperation. Whatever the magnitude and severity of the event, we must reflect on what we know, what capabilities we can apply, develop or adapt, and seriously investigate what might be done to manage it and survive. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Global Human Futures Res Associates, Ewa Beach, HI 96706 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Hawaii, John A Burns Sch Med, Dept Surg, Div Emergency Med, Honolulu, HI 96822 USA. RP Garshnek, V (reprint author), Global Human Futures Res Associates, 91-1201 Kamoawa St, Ewa Beach, HI 96706 USA. NR 32 TC 9 Z9 9 U1 1 U2 3 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0265-9646 J9 SPACE POLICY JI Space Policy PD AUG PY 2000 VL 16 IS 3 BP 213 EP 222 DI 10.1016/S0265-9646(00)00025-4 PG 10 WC International Relations; Social Sciences, Interdisciplinary SC International Relations; Social Sciences - Other Topics GA 343VQ UT WOS:000088723500008 ER PT J AU Rasch, PJ Feichter, J Law, K Mahowald, N Penner, J Benkovitz, C Genthon, C Giannakopoulos, C Kasibhatla, P Koch, D Levy, H Maki, T Prather, M Roberts, DL Roelofs, GJ Stevenson, D Stockwell, Z Taguchi, S Kritz, M Chipperfield, M Baldocchi, D McMurry, P Barrie, L Balkansi, Y Chatfield, R Kjellstrom, E Lawrence, M Lee, HN Lelieveld, J Noone, KJ Seinfeld, J Stenchikov, G Schwartz, S Walcek, C Williamson, D AF Rasch, PJ Feichter, J Law, K Mahowald, N Penner, J Benkovitz, C Genthon, C Giannakopoulos, C Kasibhatla, P Koch, D Levy, H Maki, T Prather, M Roberts, DL Roelofs, GJ Stevenson, D Stockwell, Z Taguchi, S Kritz, M Chipperfield, M Baldocchi, D McMurry, P Barrie, L Balkansi, Y Chatfield, R Kjellstrom, E Lawrence, M Lee, HN Lelieveld, J Noone, KJ Seinfeld, J Stenchikov, G Schwartz, S Walcek, C Williamson, D TI A comparison of scavenging and deposition processes in global models: results from the WCRP Cambridge Workshop of 1995 SO TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY LA English DT Article ID GENERAL-CIRCULATION MODELS; TROPOSPHERIC AEROSOLS; VERTICAL TRANSPORT; RESIDENCE TIMES; CLIMATE MODEL; TRACER MODEL; PB-210; RN-222; SIMULATION; ATMOSPHERE AB We report on results from a World Climate Research Program workshop on representations of scavenging and deposition processes in global transport models of the atmosphere. 15 models were evaluated by comparing simulations of radon, lead, sulfur dioxide, and sulfate against each other, and against observations of these constituents. This paper provides a survey on the simulation differences between models. It identifies circumstances where models are consistent with observations or with each other, and where they differ from observations or with each other. The comparison shows that most models are able to simulate seasonal species concentrations near the surface over continental sites to within a factor of 2 over many regions of the globe. Models tend to agree more closely over source (continental) regions than for remote (polar and oceanic) regions. Model simulations differ most strongly in the upper troposphere for species undergoing wet scavenging processes. There are not a sufficient number of observations to characterize the climatology (long-term average) of species undergoing wet scavenging in the upper troposphere. This highlights the need for either a different strategy for model evaluation (e.g., comparisons on an event by event basis) or many more observations of a few carefully chosen constituents. C1 Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Max Planck Inst Meteorol, D-20146 Hamburg, Germany. Univ Cambridge, Dept Chem, Ctr Atmospher Sci, Cambridge CB2 1EW, England. Univ Calif Santa Barbara, Bren Sch Environm Sci & Management, Santa Barbara, CA 93106 USA. Univ Michigan, Ann Arbor, MI 48109 USA. Brookhaven Natl Lab, Environm Chem Div, Upton, NY 11973 USA. CNRS, LGGE, F-38402 St Martin Dheres, France. Duke Univ, Levine Sci Res Ctr, Sch Environm, Durham, NC 27708 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. GFDL, Princeton, NJ 08542 USA. JMA, Chiyoda Ku, Tokyo 100, Japan. Univ Calif Irvine, Dept Earth Syst Sci, Irvine, CA 92717 USA. Meteorol Off, Bracknell RG12 2SY, Berks, England. Univ Utrecht, IMAU, NL-3584 CC Utrecht, Netherlands. NIRE, Tsukuba, Ibaraki 305, Japan. SUNY Albany, MSRC, New York, NY USA. NOAA, ATDD, Oak Ridge, TN 37831 USA. Univ Minnesota, Minneapolis, MN 55455 USA. AES Downsview, Downsview, ON M3H 5T4, Canada. CEA, DSM, LMCE, F-91191 Gif Sur Yvette, France. MISU, S-10691 Stockholm, Sweden. MPI Chem, D-55122 Mainz, Germany. US DOE, Environm Measurements Lab, New York, NY 10014 USA. Univ Maryland, College Pk, MD 20742 USA. SUNY Albany, Atmospher Sci Res Ctr, Albany, NY 12205 USA. RP Rasch, PJ (reprint author), Natl Ctr Atmospher Res, POB 3000, Boulder, CO 80307 USA. EM pjr@ucar.edu RI Penner, Joyce/J-1719-2012; McMurry, Peter/A-8245-2008; Georgiy, Stenchikov/J-8569-2013; Giannakopoulos, Christos/H-6827-2014; Lelieveld, Johannes/A-1986-2013; Baldocchi, Dennis/A-1625-2009; Kasibhatla, Prasad/A-2574-2010; Stevenson, David/C-8089-2012; Schwartz, Stephen/C-2729-2008; Mahowald, Natalie/D-8388-2013; Chipperfield, Martyn/H-6359-2013 OI Kasibhatla, Prasad/0000-0003-3562-3737; Balkanski, Yves/0000-0001-8241-2858; Kjellstrom, Erik/0000-0002-6495-1038; McMurry, Peter/0000-0003-1609-5131; Baldocchi, Dennis/0000-0003-3496-4919; Stevenson, David/0000-0002-4745-5673; Schwartz, Stephen/0000-0001-6288-310X; Mahowald, Natalie/0000-0002-2873-997X; Chipperfield, Martyn/0000-0002-6803-4149 NR 47 TC 122 Z9 123 U1 0 U2 12 PU CO-ACTION PUBLISHING PI JARFALLA PA RIPVAGEN 7, JARFALLA, SE-175 64, SWEDEN SN 0280-6509 J9 TELLUS B JI Tellus Ser. B-Chem. Phys. Meteorol. PD AUG PY 2000 VL 52 IS 4 BP 1025 EP 1056 DI 10.1034/j.1600-0889.2000.00980.x PG 32 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 361KA UT WOS:000089721200001 ER PT J AU Cole, RE Green, SM Jardin, MR AF Cole, RE Green, SM Jardin, MR TI Improving RUC-1 wind estimates by incorporating near-real-time aircraft reports SO WEATHER AND FORECASTING LA English DT Article AB A verification study of wind accuracy is presented for wind nowcasts generated by augmenting Rapid Update Cycle (RUC) wind forecasts with near-real-time aircraft reports using the Integrated Terminal Weather System (ITWS) gridded winds algorithm. Aircraft wind reports collected between the end of the RUC data collection interval and the time each RUC forecasts is valid are available for use in augmenting the RUC wind forecast to form a wind nowcast. The 60-km resolution, hourly RUG-I wind forecasts are used. ITWS-based nowcast wind errors and RUC forecast wind errors are examined statistically over a 1-yr dataset. The addition of the recent aircraft reports significantly reduces therms vector error and the 90th percentile vector error. Also reduced is the number of hours of sustained large errors and the correlation among errors. The errors increase with increasing wind speed, in part due to an underestimation of wind speed that increases with increasing wind speed. The errors in the augmented wind fields decrease with increasing numbers of Aircraft Communications Addressing and Reporting System reports. Different types of weather are also seen to influence wind field accuracy. C1 MIT, Lincoln Lab, Lexington, MA 02420 USA. NASA AMES, Moffett Field, CA USA. RP Cole, RE (reprint author), MIT, Lincoln Lab, 244 Wood St, Lexington, MA 02420 USA. NR 10 TC 4 Z9 4 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0882-8156 J9 WEATHER FORECAST JI Weather Forecast. PD AUG PY 2000 VL 15 IS 4 BP 447 EP 460 DI 10.1175/1520-0434(2000)015<0447:IRWEBI>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 346EX UT WOS:000088858800005 ER PT J AU Piva, PG Goldberg, RD Mitchell, IV Labrie, D Leon, R Charbonneau, S Wasilewski, ZR Fafard, S AF Piva, PG Goldberg, RD Mitchell, IV Labrie, D Leon, R Charbonneau, S Wasilewski, ZR Fafard, S TI Enhanced degradation resistance of quantum dot lasers to radiation damage SO APPLIED PHYSICS LETTERS LA English DT Article ID ENSEMBLES AB We compare the degradation of InAs/GaAs quantum well (QW) and quantum dot (QD) laser diodes following irradiation by high energy (8.56 MeV) phosphorous ions. Over a fluence range of 10(8)-10(11) ions/cm(2), the degradation of the low temperature QD photoluminescence and electroluminescence emission is greatly suppressed relative to that of QW based devices (X100 and x 1000, respectively at the highest dose studied). Irradiated QD laser diodes demonstrated lasing action over the entire range of fluences, and 2 orders of magnitude beyond the maximum dose sustainable by QW devices. The improved damage response of QD based structures results from efficient collection and localization of electrons and holes by QDs in the active region, which limit carrier transfer to nonradiative centers. This work suggests the suitability of QD device architectures for use in radiation environments, and in high power applications, wherever nonradiative processes promote the degradation or failure of traditional QW devices. (C) 2000 American Institute of Physics. [S0003-6951(00)03231-9]. C1 Univ Western Ontario, Dept Phys, London, ON N6A 3K7, Canada. Dalhousie Univ, Dept Phys, Halifax, NS B3H 3J5, Canada. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Res Council Canada, Inst Microstruct Sci, Ottawa, ON K1A 0R6, Canada. RP Piva, PG (reprint author), Natl Res Council Canada, Inst Microstruct Sci, Ottawa, ON K1A 0R6, Canada. NR 13 TC 46 Z9 46 U1 0 U2 4 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUL 31 PY 2000 VL 77 IS 5 BP 624 EP 626 DI 10.1063/1.127065 PG 3 WC Physics, Applied SC Physics GA 341FL UT WOS:000088580300006 ER PT J AU Temkin, A Drachman, RJ AF Temkin, A Drachman, RJ TI Partial wave dispersion relations: application to electron-atom scattering SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Letter AB In this letter we propose the use of partial wave dispersion relations (DRs) as the way to solve the longstanding problem of correctly incorporating exchange in a valid DR for electron-atom scattering. In particular, a method is given for effectively calculating the contribution of the discontinuity and/or Doles of the partial wave amplitude which occur in the negative E plane. The method is successfully tested in three cases: (i) the analytically solvable exponential potential, (ii) the Hartree potential and (iii) the S-wave exchange approximation for electron-hydrogen scattering. The latter is the first successful DR which includes exchange. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Temkin, A (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. NR 8 TC 4 Z9 4 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD JUL 28 PY 2000 VL 33 IS 14 BP L505 EP L511 DI 10.1088/0953-4075/33/14/101 PG 7 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 344HJ UT WOS:000088752900001 ER PT J AU Rood, RB Douglass, AR Cerniglia, MC Sparling, LC Nielsen, JE AF Rood, RB Douglass, AR Cerniglia, MC Sparling, LC Nielsen, JE TI Seasonal variability of middle-latitude ozone in the lowermost stratosphere derived from probability distribution functions SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID HALOGEN OCCULTATION EXPERIMENT; GENERAL-CIRCULATION MODEL; TROPOSPHERE EXCHANGE; 3-DIMENSIONAL SIMULATION; MASS-EXCHANGE; CUTOFF LOW; TROPOPAUSE FOLDS; TRANSPORT; IMPACT; CLIMATOLOGY AB We present a study of the distribution of ozone in the lowermost stratosphere with the goal of characterizing the observed variability. The air in the lowermost stratosphere is divided into two population groups based on Ertel's potential vorticity at 300 hPa. High (low) potential vorticity at 300 hPa indicates that the tropopause is low (high), and the identification of these two groups is made to account for the dynamic variability. Conditional probability distribution functions are used to define the statistics of the ozone distribution from both observations and a three-dimensional model simulation using winds from the Goddard Earth Observing System Data Assimilation System for transport. Ozone data sets include ozonesonde observations from northern midlatitude stations (1991-1996) and midlatitude observations made by the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS) (1994-1998). The conditional probability distribution functions are calculated at a series of potential temperature surfaces spanning the domain from the midlatitude tropopause to surfaces higher than the mean tropical tropopause (similar to 380 K). The probability distribution functions are similar for the two data sources, despite differences in horizontal and vertical resolution and spatial and temporal sampling. Comparisons with the model demonstrate that the model maintains a mix of air in the lowermost stratosphere similar to the observations. The model also simulates a realistic annual cycle. Results show that during summer, much of the observed variability is explained by the height of the tropopause, During the winter and spring, when the tropopause fluctuations are larger, less of the variability is explained by tropopause height. This suggests that more mixing occurs during these seasons. During all seasons, there is a transition zone near the tropopause that contains air characteristic of both the troposphere and the stratosphere. The relevance of the results to the assessment of the environmental impact of aircraft effluence is also discussed. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. Atmospher & Environm Res Inc, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Atmospher Chem & Dynam Branch, Greenbelt, MD 20771 USA. SM&A Corp, Greenbelt, MD USA. RP Rood, RB (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 910-3, Greenbelt, MD 20771 USA. EM rrood@dao.gsfc.nasa.gov RI Douglass, Anne/D-4655-2012; Rood, Richard/C-5611-2008 OI Rood, Richard/0000-0002-2310-4262 NR 52 TC 14 Z9 14 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 JUL 27 PY 2000 VL 105 IS D14 BP 17793 EP 17805 DI 10.1029/2000JD900142 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 337NT UT WOS:000088368700007 ER PT J AU Morris, GA Gleason, JF Ziemke, J Schoeberl, MR AF Morris, GA Gleason, JF Ziemke, J Schoeberl, MR TI Trajectory mapping: A tool for validation of trace gas observations SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ARRAY ETALON SPECTROMETER; HALOGEN OCCULTATION EXPERIMENT; ATMOSPHERE RESEARCH SATELLITE; MESOSPHERIC SOUNDER; OZONE DEPLETION; UARS PLATFORM; LIMB; CLAES; STRATOSPHERE; CALIBRATION AB We investigate the effectiveness of trajectory mapping (TM) as a data validation tool. TM combines a dynamical model of the atmosphere with trace gas observations to provide more statistically robust estimates of instrument performance over much broader geographic areas than traditional techniques are able to provide. We present four detailed case studies selected so that the traditional techniques are expected to work well. In each case the TM results are equivalent to or improve upon the measurement comparisons performed with traditional approaches. The TM results are statistically more robust than those achieved using traditional approaches since the TM comparisons occur over a much larger range of geophysical variability. In the first case study we compare ozone data from the Halogen Occultation Experiment (HALOE) with Microwave Limb Sounder (MLS). TM comparisons appear to introduce little to no error as compared to the traditional approach. In the second case study we compare ozone data from HALOE with that from the Stratospheric Aerosol and Gas Experiment II (SAGE II). TM results in differences of less than 5% as compared to the traditional approach at altitudes between 18 and 25 km and less than 10% at altitudes between 25 and 40 km. In the third case study we show that ozone profiles generated from HALOE data using TM compare well with profiles from five European ozonesondes. In the fourth case study we evaluate the precision of MLS H2O using TM and find typical precision uncertainties of 3-7% at most latitudes and altitudes. The TM results agree well with previous estimates but are the result of a global analysis of the data rather than an analysis in the limited latitude bands in which traditional approaches work. Finally, sensitivity studies using the MLS H2O data show the following: (1) a combination of forward and backward trajectory calculations minimize uncertainties in isentropic TM; (2) although the uncertainty of the technique increases with trajectory duration, TM calculations of up to 14 days can provide reliable information for use in data validation studies; (3) a correlation coincidence criterion of 400 km produces the best TM results under most circumstances; (4) TM performs well compared to (and sometimes better than) traditional approaches at all latitudes and in most seasons; and (5) TM introduces no statistically significant biases at altitudes between 22 and 40 km. C1 Valparaiso Univ, Dept Phys & Astron, Valparaiso, IN 46383 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Software Corp Amer, Greenbelt, MD USA. RP Morris, GA (reprint author), Valparaiso Univ, Dept Phys & Astron, Valparaiso, IN 46383 USA. EM Gary.Morris@valpo.edu RI Gleason, James/E-1421-2012 NR 40 TC 27 Z9 27 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUL 27 PY 2000 VL 105 IS D14 BP 17875 EP 17894 DI 10.1029/1999JD901118 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 337NT UT WOS:000088368700014 ER PT J AU Shay-El, Y Alpert, P da Silva, A AF Shay-El, Y Alpert, P da Silva, A TI Preliminary estimation of horizontal fluxes of cloud liquid water in relation to subtropical moisture budget studies employing ISCCP, SSMI, and GEOS-1/DAS data sets SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERIC MOISTURE; REANALYSIS; PRODUCTS; CLIMATE; DESERT AB Special Sensor Microwave/Imager (SSM/I) retrievals of cloud liquid water, International Satellite Cloud Climatology Project (ISCCP) cloud estimates, and winds from the Goddard EOS (GEOS-1/DAS) assimilation are employed to evaluate vertically integrated cloud liquid water (CLW) transport for 1992. First, GEOS-1/DAS multiyear data are used to confirm an earlier finding of a paradoxical net moisture sink over the Arabian-Iraqi desert [Alpert and Shay-El, 1993]. The negative vertically integrated moisture flux divergence over this region is balanced mainly by the negative incremental analysis updates (IAU) of moisture. Moisture fluxes reveal strong convection but without precipitation in a shallow Hadley-type cell. Vertical profiles indicate that the moisture removal process is associated with middle and high clouds and probably with CLW flux divergence. The CLW fluxes are estimated explicitly and globally from ISCCP and SSM/I by using linear regression methods. Areas of significant CLW divergence are found over the eastern coasts of both the United States and Asia, in the vicinity of the Gulf Stream and Kuroshio currents, as earlier conjectured by Peixoto [1973]. In both the Arabian-Iraqi desert and over the Sahara, divergence of a vertically integrated CLW flux opposes the convergence of a vertically integrated horizontal moisture flux, thus explaining at least partially the paradoxical net sink and source in these regions. However, the magnitude of the annual CLW flux estimates as calculated here is, in general, too small to play any significant role in the vertically integrated water budget, except perhaps along coastal regions and over dry subtropical deserts where precipitation minus evaporation is relatively small. C1 Tel Aviv Univ, Dept Geophys & Planetary Sci, IL-69978 Tel Aviv, Israel. NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20071 USA. RP Shay-El, Y (reprint author), Tel Aviv Univ, Dept Geophys & Planetary Sci, IL-69978 Tel Aviv, Israel. EM yuval@cyclone.tau.ac.il; pinhas@cyclone.tau.ac.il; dasilva@niteroi.gsfc.nasa.gov RI da Silva, Arlindo/D-6301-2012 OI da Silva, Arlindo/0000-0002-3381-4030 NR 28 TC 3 Z9 3 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUL 27 PY 2000 VL 105 IS D14 BP 18067 EP 18089 DI 10.1029/1999JD901200 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 337NT UT WOS:000088368700026 ER PT J AU Pinty, B Roveda, F Verstraete, MM Gobron, N Govaerts, Y Martonchik, JV Diner, DJ Kahn, RA AF Pinty, B Roveda, F Verstraete, MM Gobron, N Govaerts, Y Martonchik, JV Diner, DJ Kahn, RA TI Surface albedo retrieval from Meteosat - 1. Theory SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SEMI-ARID REGIONS; SPECTRAL ALBEDO; REFLECTANCE; DROUGHT; LAND; MODELS; SAHEL AB Land surface albedo constitutes a critical climatic variable, since it largely controls the actual amount of solar energy available to the Earth system. The purpose of this paper is to establish a theory for the exploitation of space observations to solve the atmosphere/surface radiation transfer problem on an operational basis and to generate surface albedo, aerosol load, and possibly land cover change products. Surface albedo is rather variable in space and time and depends both on the structure and on the radiative characteristics of the surface, as well as on the angular and spectral distribution of radiation at the bottom of the atmosphere. Weather and climate models often use preset distributions or simple parameterizations of this environment variable, even though such approaches do not accurately account for the actual effect of the underlying surface. From a mathematical point of view, the determination of the surface albedo corresponds to the estimation of a boundary condition fur the radiation transfer problem in the coupled surface-atmosphere system. A relatively large database of 10 years or more of Meteosat data has been accumulated by EUMETSAT. These data, collected at half-hour intervals over the entire Earth disk visible from longitude 0 degrees, constitute a unique resource to describe the anisotropy of the coupled surface-atmosphere system and provide the opportunity to document changes in surface albedo which may have occurred in these regions over that period, In addition, since the coupled surface-atmosphere radiation transfer problem must be solved, the proposed procedure also yields an estimate of the spatial and temporal distribution of aerosols. The proposed inversion procedure yields a characterization of surface radiative properties that may also be used to document and monitor land surface dynamics over the portion of the globe observed by Meteosat. Results from preliminary applications and an error budget analysis are discussed in a companion paper [Pinty et al., this issue]. C1 Commiss European Communities, Joint Res Ctr, Space Applicat Inst, I-21020 Ispra, VA, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. EUMETSAT, D-64295 Darmstadt, Germany. RP Pinty, B (reprint author), Commiss European Communities, Joint Res Ctr, Space Applicat Inst, TP 440, I-21020 Ispra, VA, Italy. EM bernard.pinty@jrc.it RI Kahn, Ralph/D-5371-2012; OI Kahn, Ralph/0000-0002-5234-6359; Verstraete, Michel/0000-0003-0968-8721 NR 31 TC 85 Z9 89 U1 3 U2 13 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 JUL 27 PY 2000 VL 105 IS D14 BP 18099 EP 18112 DI 10.1029/2000JD900113 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 337NT UT WOS:000088368700028 ER PT J AU Pinty, B Roveda, F Verstraete, MM Gobron, N Govaerts, Y Martonchik, JV Diner, DJ Kahn, RA AF Pinty, B Roveda, F Verstraete, MM Gobron, N Govaerts, Y Martonchik, JV Diner, DJ Kahn, RA TI Surface albedo retrieval from Meteosat - 2. Applications SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DROUGHT; AFRICA; SAHEL; VEGETATION; CHEMISTRY; FIRES; MODEL AB An advanced algorithm to retrieve the radiative properties of terrestrial surfaces sampled by the Meteosat visible instrument was derived in a companion paper [Pinty et al., this issue]. Preliminary applications of this algorithm against a limited set of Meteosat data is performed and the required procedures to screen "clear-sky" conditions only and to retrieve the "likely" solution of the inverse problem are presented and evaluated. The accumulation of results over two periods of 20 days each during the Northern Hemisphere summer and winter permits establishing sample geophysical maps of the algorithm products, including the surface albedo (i.e., directional hemispherical reflectance factors) over the entire African continent. The seasonal albedo changes occurring at a continental scale are interpreted on the basis of the most prominent environmental factors, namely the atmospheric circulation controlling the seasonal monsoon events and the biomass burning activities. The results of this study, supported by additional radiation transfer simulations, suggest that anthropogenic fire activities induce significant perturbations of the surface albedo values in the intertropical zones at the continental scale. C1 Commiss European Communities, Joint Res Ctr, Space Applicat Inst, I-21020 Ispra, VA, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. EUMETSAT, D-64295 Darmstadt, Germany. RP Pinty, B (reprint author), Commiss European Communities, Joint Res Ctr, Space Applicat Inst, TP 261, I-21020 Ispra, VA, Italy. EM bernard.pinty@jrc.it RI Kahn, Ralph/D-5371-2012; OI Kahn, Ralph/0000-0002-5234-6359; Verstraete, Michel/0000-0003-0968-8721 NR 21 TC 54 Z9 57 U1 1 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUL 27 PY 2000 VL 105 IS D14 BP 18113 EP 18134 DI 10.1029/2000JD900114 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 337NT UT WOS:000088368700029 ER PT J AU Joshi, M Haberle, R Hollingsworth, J Hinson, D AF Joshi, M Haberle, R Hollingsworth, J Hinson, D TI A comparison of MGS Phase 1 aerobraking radio occultation data and the NASA Ames Mars GCM SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID GENERAL-CIRCULATION MODEL; GLOBAL DUST STORMS; SURFACE PRESSURE; SIMULATIONS; PATHFINDER; TOPOGRAPHY; SURVEYOR; VIKING; CYCLE AB The NASA Ames Mars general circulation model (MGCM) is used to investigate how different phenomena in the Martian climate system combine to produce temperature profiles measured by the Radioscience Instrument (RS) aboard Mars Global Surveyor (MGS) in early 1998. When integrated with dust amounts consistent with Thermal Emission Spectrometer (TES) observations, and with a topography data set determined from the Mars Orbiting Laser Altimeter (MOLA), modeled temperature profiles are within 5-10 EC of observations. Modeled and measured pro-files in the winter subtropics are warmer than pure radiative-convective considerations suggest, providing further evidence of strong dynamical warming associated with descent in the Hadley cell. South of 40 degrees S, the best fit to the data is obtained by confining airborne dust to below 2 scale heights in this region. The differences in the strength of low-level inversions found in the MGCM and in the RS data indicate the presence of either a low-level radiative cooling mechanism such as isolated dust clouds or water-ice clouds, or a dynamical mechanism such as low-level gravity wave drag. When initialized with a mean surface pressure that gives the best fit to Viking lander measurements, the model matches RS surface pressure data to within 0.1 mbar. This consistency is a further validation of the MGCM and shows how GCMs can be used to interpret measurements of surface pressure taken at different locations using different methods. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Stanford Univ, Dept Elect Engn, Palo Alto, CA 94035 USA. San Jose State Univ Fdn, San Jose, CA USA. SETI Inst, Mt View, CA USA. RP Joshi, M (reprint author), Univ Reading, Dept Meteorol, POB 243, Reading RG6 6BB, Berks, England. RI Joshi, Manoj/C-1795-2008 OI Joshi, Manoj/0000-0002-2948-2811 NR 23 TC 10 Z9 10 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 JUL 25 PY 2000 VL 105 IS E7 BP 17601 EP 17615 DI 10.1029/1999JE001217 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 338LK UT WOS:000088421100005 ER PT J AU Lane, MD Christensen, PR AF Lane, MD Christensen, PR TI Convection in a catastrophic flood deposit as the mechanism for the giant polygons on Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID NORTHERN PLAINS; GROUND ICE; WATER; MODEL; PERMAFROST; STABILITY; FEATURES; RELEASE; ORIGIN; CO2 AB A formational mechanism for the large-scale polygons that are defined by intersecting fractures in the northern plains of Mars is proposed in this work. The presented model is based on Rayleigh convection of interstitial water driven by an unstable density/temperature gradient within a saturated, porous medium. Catastrophic emplacement of water-rich sediments into the Martian northern plain basins could have provided a thick sedimentary layer in which Rayleigh convection could have occurred. Convection within this active layer is proposed to have differentially thawed an underlying ice-rich permafrost layer that had been at the planet's surface before being rapidly buried. The resulting morphology of the permafrost subsurface is thought to have resembled the scalloped solid-liquid interface morphology produced in terrestrial convective flow visualization studies. The exact size and shape of the scallops on the frozen subsurface would have been controlled by the dimensions of the convection cells, which are estimated to have had width-to-depth ratios of between 3.4 and 4.5. Subsequent stresses (e.g., gravity and bending stresses) would have produced maximum tensile stresses in the overlying sediments preferentially above the subsurface topographic highs as described previously by McGill and Hills [1992]. Additional desiccation of the sediments would ha;Ie required contraction of the sediment cover and would have produced large-scale polygonal fractures along the preexisting weaknesses located above the raised subsurface topography. Thus the underlying subsurface geometric morphology would have been translated to the surface and would be represented by the large-scale polygonal fractures visible in the Viking Orbiter and Mars Global Surveyor images of the Martian northern plains. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. RP Lane, MD (reprint author), NASA, Lyndon B Johnson Space Ctr, Code SN3, Houston, TX 77058 USA. NR 68 TC 22 Z9 22 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 JUL 25 PY 2000 VL 105 IS E7 BP 17617 EP 17627 DI 10.1029/1999JE001197 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 338LK UT WOS:000088421100006 ER PT J AU Nagai, D Sulkanen, ME Evrard, AE AF Nagai, D Sulkanen, ME Evrard, AE TI A multiphase model for the intracluster medium SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE galaxies : clusters : general; intergalactic medium; X-rays : galaxies ID X-RAY-PROPERTIES; HUBBLE-CONSTANT; COOLING FLOWS; GALAXY CLUSTERS; SUPERNOVAE; PROFILES; SHAPES; ROSAT AB Constraints on the clustered mass density Omega(m) of the Universe derived from the observed population mean intracluster gas fraction [f(ICM)] of X-ray clusters may be biased by reliance on a single-phase assumption for the thermodynamic structure of the intracluster medium (ICM). We propose a descriptive model for multiphase structure in which a spherically symmetric ICM contains isobaric density perturbations with a radially dependent variance sigma(2)(r) = sigma(c)(2)(1 + r(2)/r(c)(2))(-epsilon). The model extends the work of Gunn & Thomas, which assumed radially independent density fluctuations. The main limitation of the model is its lack of connection to ICM dynamics. Fixing the X-ray emission profile and emission-weighted temperature, we explore two independently observable signatures of the model in the {sigma(c), epsilon} space. For bremsstrahlung-dominated emission, the central Sunyaev-Zeldovich (SZ) decrement in the multiphase case is increased over the single-phase case, and multiphase X-ray spectra in the range 0.1-20 keV are flatter in the continuum and exhibit stronger low-energy emission lines than their single-phase counterpart. We quantify these effects for a fiducial 10(8) K cluster and demonstrate how the combination of SZ and X-ray spectroscopy can be used to identify a preferred location {<(sigma)over cap>(c), <(epsilon)over cap>} in the model plane. From these parameters, the correct value of [f(ICM)] in the multiphase model results, allowing an unbiased estimate of Omega(m) to be recovered. The degree of consistency of current determinations of the Hubble constant via SZ and X-ray observations with values determined by other methods implies that biases in ICM gas fractions are not large. C1 Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA. Univ Chicago, Chicago, IL 60637 USA. NASA, Xray Astron Grp, Space Sci Lab, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Nagai, D (reprint author), Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA. OI Evrard, August/0000-0002-4876-956X NR 39 TC 10 Z9 10 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUL 21 PY 2000 VL 316 IS 1 BP 120 EP 128 DI 10.1046/j.1365-8711.2000.03484.x PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 345GL UT WOS:000088808200015 ER PT J AU Rauw, G Stevens, IR Pittard, JM Corcoran, MF AF Rauw, G Stevens, IR Pittard, JM Corcoran, MF TI ASCA spectroscopy of the hard X-ray emission from the colliding wind interaction in gamma(2) Velorum SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE binaries : general; stars : individual : gamma(2)Vel; stars : mass-loss; stars : Wolf-Rayet; X-rays : stars ID EARLY-TYPE STARS; SYSTEM; ABUNDANCES; HD-193793; BINARIES; SPECTRUM; MASS AB We discuss an ASCA observation of the eccentric WC8 + 07.5 III binary gamma(2)Velorum near apastron. The X-ray spectrum is compared with two previous observations obtained when the system was near periastron, All three spectra display a hard-emission component that undergoes strong variability over the orbital cycle. The properties of the hard X-ray emission of gamma(2)Vel are constrained by taking into account the contribution from contaminating soft X-ray sources in the vicinity of gamma(2)Vel, We find that the observed variations are in qualitative agreement with the predictions of colliding wind models. We investigate for the first time the effect of uncertainties in the chemical composition of the X-ray emitting plasma on our understanding of the high-energy properties of the wind interaction region. Our results indicate that these uncertainties significantly affect the derived shock temperature and absorption column, but play a smaller role in determining the intrinsic X-ray luminosity of the colliding wind zone. We further find that the intrinsic luminosity from the hard X-ray component in gamma(2)Vel does not follow the 1/D distance relation expected from simple models of adiabatic shocks. C1 Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium. Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. Univ Leeds, Dept Phys & Astron, Leeds LS2 9JT, W Yorkshire, England. NASA, Goddard Space Flight Ctr, USRA, LHEA, Greenbelt, MD 20771 USA. RP Rauw, G (reprint author), Univ Liege, Inst Astrophys & Geophys, 5 Ave Cointe, B-4000 Liege, Belgium. NR 35 TC 15 Z9 15 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUL 21 PY 2000 VL 316 IS 1 BP 129 EP 136 DI 10.1046/j.1365-8711.2000.03491.x PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 345GL UT WOS:000088808200016 ER PT J AU McCutcheon, WH Sandell, G Matthews, HE Kuiper, TBH Sutton, EC Danchi, WC Sato, T AF McCutcheon, WH Sandell, G Matthews, HE Kuiper, TBH Sutton, EC Danchi, WC Sato, T TI Star formation in NGC 6334 I and I(N) SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE stars : formation; ISM : individual : NGC 6334; ISM : jets and outflows; ISM : molecules; radio continuum : ISM; radio lines : ISM ID YOUNG STELLAR OBJECTS; MOLECULAR CLOUD CORES; METHANOL MASERS; INFRARED OBSERVATIONS; NGC-6334 COMPLEX; RADIO-SOURCES; SUBMILLIMETER; EMISSION; REGIONS; GHZ AB The northern section of the molecular cloud complex NGC 6334 has been mapped in the CO and CS spectral line emission and in continuum emission at a wavelength of 1300 mu m. Our observations highlight the two dominant sources, I and I(N), and a host of weaker sources. NGC 6334 I is associated with a cometary ultracompact H II region and a hot, compact core less than or equal to 10 arcsec in size, Mid-infrared and CH3OH observations indicate that it is also associated with at least two protostellar sources, each of which may drive a molecular outflow. For region I we confirm the extreme high-velocity outflow first discovered by Bachiller & Cernicharo and find that it is very energetic with a mechanical luminosity of 390 L.. A dynamical age for the outflow is similar to 3000 yr, We also find a weaker outflow originating from the vicinity of NGC 6334 I, In CO and CS this outflow is quite prominent to the north-west, but much less so on the eastern side of I, where there is very little molecular gas, Spectral survey data show a molecular environment at position I which is rich in methanol, methyl formate and dimethyl ether, with lines ranging in energy up to 900 K above the ground state, NGC 6334 I(N) is more dense than I, but cooler, and has none of the high-excitation lines observed toward I. I(N) also has an associated outflow but it is less energetic than the outflow from I. The fully sampled continuum map shows a network of filaments, voids and cores, many of which are likely to be sites of star formation. A striking feature is a narrow, linear ridge which defines the western boundary. It is unclear if there is a connection between this filament and the many potential sites of star formation, or if the filament existed prior to the star formation activity. C1 Univ British Columbia, Dept Phys & Astron, Vancouver, BC V6T 1Z1, Canada. Natl Radio Astron Observ, Green Bank, WV 24944 USA. Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V8X 4M6, Canada. Joint Astron Ctr, Hilo, HI 96720 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Illinois, Dept Astron, Urbana, IL 61801 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Kwantlen Univ Coll, Surrey, BC V3W 2M8, Canada. RP McCutcheon, WH (reprint author), Univ British Columbia, Dept Phys & Astron, Vancouver, BC V6T 1Z1, Canada. RI Sutton, Edmund/H-5113-2011 NR 57 TC 35 Z9 36 U1 0 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUL 21 PY 2000 VL 316 IS 1 BP 152 EP 164 DI 10.1046/j.1365-8711.2000.03487.x PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 345GL UT WOS:000088808200019 ER PT J AU Thomas, R Akins, T Csatho, B Fahnestock, M Gogineni, P Kim, C Sonntag, J AF Thomas, R Akins, T Csatho, B Fahnestock, M Gogineni, P Kim, C Sonntag, J TI Mass balance of the Greenland ice sheet at high elevations SO SCIENCE LA English DT Article AB Comparison of ice discharge from higher elevation areas of the entire Greenland Ice Sheet with total snow accumulation gives estimates of ice thickening rates over the past few decades. On average, the region has been in balance, but with thickening of 21 centimeters per year in the southwest and thinning of 30 centimeters per year in the southeast. The north of the ice sheet shows Less variability, with average thickening of 2 centimeters per year in the northeast and thinning of about 5 centimeters per year in the northwest. These results agree well with those from repeated altimeter surveys, except in the extreme south, where we find substantially higher rates of both thickening and thinning. C1 EG&G Serv, Wallops Flight Facil, Wallops Island, VA 23337 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Ohio State Univ, Byrd Polar Res Ctr, Columbus, OH 43210 USA. Univ Maryland, ESSIC, College Pk, MD 20742 USA. Univ Kansas, Radar Syst & Remote Sensing Lab, Lawrence, KS 66045 USA. RP Thomas, R (reprint author), EG&G Serv, Wallops Flight Facil, Bldg N-159, Wallops Island, VA 23337 USA. RI Kim, Changjoo/B-9362-2008; Fahnestock, Mark/N-2678-2013 NR 11 TC 59 Z9 62 U1 1 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD JUL 21 PY 2000 VL 289 IS 5478 BP 426 EP 428 DI 10.1126/science.289.5478.426 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 336ME UT WOS:000088305500039 ER PT J AU Krabill, W Abdalati, W Frederick, E Manizade, S Martin, C Sonntag, J Swift, R Thomas, R Wright, W Yungel, J AF Krabill, W Abdalati, W Frederick, E Manizade, S Martin, C Sonntag, J Swift, R Thomas, R Wright, W Yungel, J TI Greenland ice sheet: High-elevation balance and peripheral thinning SO SCIENCE LA English DT Article AB Aircraft Laser-altimeter surveys over northern Greenland in 1994 and 1999 have been coupled with previously reported data from southern Greenland to analyze the recent mass-balance of the Greenland Ice Sheet. Above 2000 meters elevation, the ice sheet is in balance on average but has some regions of local thickening or thinning. Thinning predominates at Lower elevations, with rates exceeding 1 meter per year close to the coast. Interpolation of our results between flight lines indicates a net loss of about 51 cubic kilometers of ice per year from the entire ice sheet, sufficient to raise sea Level by 0.13 millimeter per year-approximately 7% of the observed rise. C1 NASA, Lab Hydrospher Proc, Goddard Space Flight Ctr, Wallops Island, VA 23337 USA. EG&G Serv, Wallops Flight Facil, Wallops Island, VA 23337 USA. NASA, Lab Hydrospher Proc, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Krabill, W (reprint author), NASA, Lab Hydrospher Proc, Goddard Space Flight Ctr, Bldg N-159, Wallops Island, VA 23337 USA. NR 13 TC 250 Z9 255 U1 4 U2 25 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD JUL 21 PY 2000 VL 289 IS 5478 BP 428 EP 430 DI 10.1126/science.289.5478.428 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 336ME UT WOS:000088305500040 ER PT J AU Siegel, DA Wang, MH Maritorena, S Robinson, W AF Siegel, DA Wang, MH Maritorena, S Robinson, W TI Atmospheric correction of satellite ocean color imagery: the black pixel assumption SO APPLIED OPTICS LA English DT Article ID WATER-LEAVING RADIANCE; DIFFUSE TRANSMITTANCE; CASE-1 WATERS; SCATTERING; SEAWIFS; COASTAL; SENSORS; LIGHT; ABSORPTION; DEPENDENCE AB The assumption that values of water-leaving radiance in the near-infrared (NIR) are negligible enable aerosol radiative properties to be easily determined in the correction of satellite ocean color imagery. This is referred to as the black pixel assumption. We examine the implications of the black pixel assumption using a simple bio-optical model for the NIR water-leaving reflectance [rho(omega)(lambda(NIR))](N). In productive waters [chlorophyll (Chl) concentration >2 mg m(-3)], estimates of [rho(omega)(lambda(NIR))](N) are several orders of magnitude larger than those expected for pure seawater. These large values of [rho(omega)(lambda(NIR))](N) result in an overcorrection of atmospheric effects for retrievals of water-leaving reflectance that are most pronounced in the violet and blue spectral region. The overcorrection increases dramatically with Chl, reducing the true water-leaving radiance by roughly 75% when Chi is equal to 5 mg m(-3). Relaxing the black pixel assumption in the correction of Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) satellite ocean color imagery provides significant improvements in Chl and water-leaving reflectance retrievals when Chi values are greater than 2 mg m(-3). Improvements in the present modeling of [rho(omega)(lambda(NIR))](N) are considered, particularly for turbid coastal waters. However, this research shows that the effects of nonzero NIR reflectance must be included in the correction of satellite ocean color imagery. (C) 2000 Optical Society of America OCIS codes: 010.0010, 280.0280, 010.4450. C1 Univ Calif Santa Barbara, Inst Computat Earth Syst Sci, Santa Barbara, CA 93106 USA. Univ Calif Santa Barbara, Dept Geog, Santa Barbara, CA 93106 USA. Univ Calif Santa Barbara, Donald Bren Sch Environm Sci & Management, Santa Barbara, CA 93106 USA. Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, SAIC Gen Sci Corp, Greenbelt, MD 20771 USA. RP Univ Calif Santa Barbara, Inst Computat Earth Syst Sci, Santa Barbara, CA 93106 USA. EM davey@icess.ucsb.edu RI Wang, Menghua/F-5631-2010; Siegel, David/C-5587-2008 OI Wang, Menghua/0000-0001-7019-3125; NR 34 TC 275 Z9 286 U1 6 U2 17 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 JUL 20 PY 2000 VL 39 IS 21 BP 3582 EP 3591 DI 10.1364/AO.39.003582 PG 10 WC Optics SC Optics GA 337FC UT WOS:000088345900004 PM 18349929 ER PT J AU Koch, GJ Dharamsi, AN Fitzgerald, CM McCarthy, JC AF Koch, GJ Dharamsi, AN Fitzgerald, CM McCarthy, JC TI Frequency stabilization of a Ho : Tm : YLF laser to absorption lines of carbon dioxide SO APPLIED OPTICS LA English DT Article ID MODULATION SPECTROSCOPY; YAG LASER; PUMPED TM AB A single-frequency Ho:Tm:YLF laser, operating at an eye-safe wavelength of 2 mu m, has been developed with tuning characteristics optimized for spectroscopy of absorption features. The laser frequency was stabilized to three different absorption lines of carbon dioxide by a wavelength modulation technique. Long-term frequency drift has been eliminated from the laser, and shorter-term jitter has been reduced to within 13.5 MHz of the absorption line center. This stabilized laser is an ideal injection seed source for a differential absorption lidar system for measurement of atmospheric gases. (C) 2000 Optical Society of America OCIS codes: 140.3580, 300.6380, 280.3640, 280.1910. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Old Dominion Univ, Dept Elect & Comp Engn, Norfolk, VA 23529 USA. Sanders, Lockheed Martin Co, Nashua, NH 03060 USA. RP NASA, Langley Res Ctr, MS 468, Hampton, VA 23681 USA. EM g.j.koch@larc.nasa.gov NR 18 TC 46 Z9 48 U1 2 U2 11 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 JUL 20 PY 2000 VL 39 IS 21 BP 3664 EP 3669 DI 10.1364/AO.39.003664 PG 6 WC Optics SC Optics GA 337FC UT WOS:000088345900015 PM 18349940 ER PT J AU Yang, P Liou, KN Mishchenko, MI Gao, BC AF Yang, P Liou, KN Mishchenko, MI Gao, BC TI Efficient finite-difference time-domain scheme for light scattering by dielectric particles: application to aerosols SO APPLIED OPTICS LA English DT Article ID PERFECTLY MATCHED LAYER; ABSORBING BOUNDARY-CONDITION; TROPOSPHERIC AEROSOLS; ELECTROMAGNETIC-WAVES; ICE CRYSTALS; ABSORPTION; MODELS AB We have examined the Maxwell-Garnett, inverted Maxwell-Garnett, and Bruggeman rules for evaluation of the mean permittivity involving partially empty cells at particle surface in conjunction with the finite-difference time-domain (FDTD) computation Sensitivity studies show that the inverted Maxwell-Garnett rule is the most effective in reducing the staircasing effect. The discontinuity of permittivity at the interface of free space and the particle medium can be minimized by use of an effective permittivity at the cell edges determined by the average of the permittivity values associated with adjacent cells. The efficiency of the FDTD computational program is further improved by use of a perfectly matched layer absorbing boundary condition and the appropriate coding technique. The accuracy of the FDTD method is assessed on the basis of a comparison of the FDTD and the Mie calculations for ice spheres. This program is then applied to light scattering by convex and concave aerosol particles. Comparisons of the scattering phase function for these types of aerosol with those for spheres and spheroids show substantial differences in backscattering directions. Finally, we illustrate that the FDTD method is robust and flexible in computing the scattering properties of particles with complex morphological configurations. (C) 2000 Optical Society of America. C1 Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. USN, Res Lab, Remote Sensing Div, Washington, DC 20375 USA. RP Sci Syst & Applicat Inc, Lanham, MD 20706 USA. EM pyang@climate.gsfc.nasa.gov RI Yang, Ping/B-4590-2011; Mishchenko, Michael/D-4426-2012 NR 21 TC 101 Z9 105 U1 3 U2 16 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD JUL 20 PY 2000 VL 39 IS 21 BP 3727 EP 3737 DI 10.1364/AO.39.003727 PG 11 WC Optics SC Optics GA 337FC UT WOS:000088345900023 PM 18349948 ER PT J AU Bowman, KW Worden, HM Beer, R AF Bowman, KW Worden, HM Beer, R TI Instrument line-shape modeling and correction for off-axis detectors in Fourier-transform spectrometry SO APPLIED OPTICS LA English DT Article AB Spectra measured by off-axis detectors in a high-resolution Fourier-transform spectrometer are characterized by frequency scaling, asymmetry and broadening of their line shape, and self-apodization in the corresponding interferogram. For a narrow-band input spectrum and a specified detector geometry, a formalism is presented that accounts for these effects with separate terms. Some of the terms are used to correct the larger off-axis effects as part of the calibration. The remaining terms are used to model the residual effects with the on-axis instrument line shape. We extend this approach to the broadband case using filter banks. The technique is applied to simulated spectra for the Tropospheric Emissions Spectrometer. This approach is shown to maintain a radiometric accuracy to less than 0.1%. (C) 2000 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 kevin.bowman@jpl.nasa.gov NR 13 TC 15 Z9 15 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD JUL 20 PY 2000 VL 39 IS 21 BP 3765 EP 3773 DI 10.1364/AO.39.003765 PG 9 WC Optics SC Optics GA 337FC UT WOS:000088345900027 PM 18349952 ER PT J AU Hakkila, J Haglin, DJ Pendleton, GN Mallozzi, RS Meegan, CA Roiger, RJ AF Hakkila, J Haglin, DJ Pendleton, GN Mallozzi, RS Meegan, CA Roiger, RJ TI Gamma-ray burst class properties SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; methods : analytical; methods : data analysis ID BATSE AB Guided by the supervised pattern recognition algorithm C4.5 developed by Quinlan in 1986, we examine the three gamma-ray burst classes identified by Mukherjee et al. in 1998. C4.5 provides strong statistical support for this classification. However, with C4.5 and our knowledge of the BATSE instrument? we demonstrate that class 3 (intermediate fluence, intermediate duration, soft) does not have to be a distinct source population: statistical/systematic errors in measuring burst attributes combined with the well-known hardness/intensity correlation can cause low peak flux class 1 thigh fluence, long, intermediate hardness) bursts to take on class 3 characteristics naturally. Based on our hypothesis that the third class is not a distinct one, we provide rules so that future events can be placed in either class 1 or class 2 (low fluence, short, hard). We find that the two classes are relatively distinct on the basis of Band's work in 1993 on spectral parameters alpha, beta, and E-peak alone. Although this does not indicate a better basis for classification, it does suggest that different physical conditions exist for class 1 and class 2 bursts. In the process of studying burst class characteristics, we identify a new bias affecting burst fluence and duration measurements. Using a simple model of how burst duration can be underestimated, we show how this fluence duration bias can affect BATSE measurements and demonstrate the type of effect it can have on the BATSE fluence versus peak flux diagram. C1 Univ Alabama, Dept Phys & Astron, Huntsville, AL 35812 USA. Coll Charleston, Dept Phys & Astron, Charleston, SC 29424 USA. Minnesota State Univ, Dept Phys & Astron, Mankato, MN 56001 USA. Minnesota State Univ, Dept Comp & Informat Sci, Mankato, MN 56001 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Hakkila, J (reprint author), Univ Alabama, Dept Phys & Astron, Huntsville, AL 35812 USA. NR 27 TC 70 Z9 72 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP 165 EP 180 DI 10.1086/309107 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343MK UT WOS:000088706000018 ER PT J AU Jenkins, EB Wozniak, PR Sofia, UJ Sonneborn, G Tripp, TM AF Jenkins, EB Wozniak, PR Sofia, UJ Sonneborn, G Tripp, TM TI The properties of molecular hydrogen toward the Orion belt stars from observations by the interstellar medium absorption profile spectrograph SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : molecules; stars : individual (delta Orionis A, epsilon Orionis, xi Orionis A); ultraviolet : ISM ID H-II REGIONS; DELTA-ORIONIS; COPERNICUS OBSERVATIONS; ROTATIONAL-EXCITATION; HIPPARCOS CATALOG; OB1 ASSOCIATION; EXPANDING SHELL; BINARY STARS; DENSE CORES; NGC-2024 AB Absorption features from the Lyman and Werner bands of interstellar molecular hydrogen were recorded by the Interstellar Medium Absorption Profile Spectrograph (IMAPS) at lambda/Delta lambda = 80,000 in the spectra of delta Ori A and epsilon Ori. The objective was to find and study more examples of an unusual phenomenon found for one of the velocity components of H(2) in the spectrum of zeta Ori by Jenkins & Peimbert (1997). Specifically, they detected a gradual shift in velocity and broadening for features arising from progressively higher rotational excitations J. This effect appears to be absent in the spectra of both delta and epsilon Ori, which are only a few degrees away in the sky from zeta Ori. The absence of atomic material at a large negative velocity in the spectra of delta and epsilon Ori (and its presence in zeta Ori) supports a proposal by Jenkins & Peimbert that the line of sight to zeta intercepts a bow shock facing away from us, perhaps created by the collision of windlike material with some foreground obstruction. One edge of the molecular cloud complex Lynds 1630 is situated close to I Ori in the sky, but we present some evidence that seems to indicate that the cloud is more distant, in which case it could not serve as the obstruction. However, it is possible that the outermost extension of a high-speed jet from a star forming within the cloud can explain the high-velocity material and the shock front created by it. For both stars, the H(2) absorption features are separated into two velocity components. Total H(2) column densities toward delta and epsilon Ori are 5.5 x 10(14) and 1.9 x 10(16) cm(-2), respectively. When these values are compared to the column densities of H I, the fractions of H atoms bound in molecular form 2N(H(2))/[2N(H(2)) + N(H I)] = 7 x 10(-6) for delta and 1.3 x 10(-4) for epsilon. The rotation temperatures of the molecules with J > 2 toward epsilon Ori indicate that the gas is in the general vicinity of the stars that emit UV fluxes capable of rotationally pumping the molecules. For the strongest component of H(2) toward delta Ori, the pumping rate is lower and consistent with a general UV flux level in the plane of the Galaxy. C1 Princeton Univ Observ, Princeton, NJ 08544 USA. Villanova Univ, Dept Astron & Astrophys, Villanova, PA 19085 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Jenkins, EB (reprint author), Princeton Univ Observ, Princeton, NJ 08544 USA. RI Jenkins, Edward/P-5684-2014 OI Jenkins, Edward/0000-0003-1892-4423 NR 85 TC 14 Z9 14 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP 275 EP 288 DI 10.1086/309130 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343MK UT WOS:000088706000029 ER PT J AU Dieters, SW Belloni, T Kuulkers, E Woods, P Cui, M Zhang, SN Chen, W van der Klis, M van Paradijs, J Swank, J Lewin, WHG Kouveliotou, C AF Dieters, SW Belloni, T Kuulkers, E Woods, P Cui, M Zhang, SN Chen, W van der Klis, M van Paradijs, J Swank, J Lewin, WHG Kouveliotou, C TI The timing evolution of 4U 1630-47 during its 1998 outburst SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : close; stars : individual (4U 1630-47); X-rays : stars ID RAY TRANSIENT 4U-1630-47; QUASI-PERIODIC OSCILLATIONS; BLACK-HOLE CANDIDATES; GRO J1655-40; CYGNUS X-1; HIGH STATE; VARIABILITY; EXPLORER; NOISE AB We report on the evolution of the timing of 4U 1630-47 during its 1998 outburst using data obtained with the Rossi X-ray Timing Explorer (RXTE). The count rate and position in hardness intensity, color-color diagrams, and simple spectral fits are used to track the concurrent spectral changes. The source showed seven distinct types of timing behavior, most of which show differences with the canonical black hole spectral/timing states. In marked contrast to previous outbursts, we find quasi-periodic oscillation (QPO) signals during nearly all stages of the outburst with frequencies between 0.06 and 14 Hz and a remarkable variety of other characteristics. In particular, we find large (up to 23% rms) amplitude QPOs on the early rise. Later, slow 0.1 Hz semiregular short (similar to 5 s), 9%-16% deep dips dominate the light curve. At this time there are two QPOs, one stable near 13.5 Hz and the other whose frequency drops from the 6-8 Hz range to similar to 4.5 Hz during the dips. BeppoSAX observations during the very late declining phase show 4U 1630-47 in a low state. C1 Univ Alabama, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Osservatorio Astron Brera, I-23807 Merate, LC, Italy. Space Res Org Netherlands, NL-3584 CA Utrecht, Netherlands. Univ Utrecht, Inst Astron, Utrecht, Netherlands. MIT, Ctr Space Res, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. RP Dieters, SW (reprint author), Univ Alabama, 301 Sparkman Dr, Huntsville, AL 35899 USA. RI Swank, Jean/F-2693-2012; OI Cui, Wei/0000-0002-6324-5772 NR 39 TC 29 Z9 29 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP 307 EP 314 DI 10.1086/309108 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343MK UT WOS:000088706000032 ER PT J AU Kucera, TA Feldman, U Widing, KG Curdt, W AF Kucera, TA Feldman, U Widing, KG Curdt, W TI Wavelengths of forbidden transitions arising from levels within the Fe+19 2s(2)2p(3) ground configuration SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : corona; Sun : UV radiation; techniques : spectroscopic ID TOKAMAK DISCHARGES; LINES; IRON; SPECTRA; ELEMENTS; CHROMIUM; NICKEL; SUMER; CR; NI AB In this paper we report the identification of all remaining unidentified forbidden lines arising from transitions within levels of the Fe+19 ground configuration. These lines were identified using data from the SOHO/SUMER spectrograph and Skylab. Adjusted wavelength values are also given for some previously observed lines. Forbidden lines that are the result of transitions within levels of the ground configuration of a highly ionized astrophysically abundant element generally have longer wavelengths than resonance lines emitted by the same ion. Many of these forbidden lines are fairly prominent in low-density plasmas and traditionally have been used in determining properties of high-temperature astrophysical plasmas. The identified Fe+19 forbidden lines span the 300-2665 Angstrom wavelength range. Since spontaneous decay rates of forbidden transitions arising from the same upper level are known quite accurately, these Lines can be used for calibrating spectrometers over wide wavelength ranges. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. USN, Res Lab, Washington, DC 20375 USA. Max Planck Inst Aeron, D-37191 Katlenburg Duhm, Lindau, Germany. RI Kucera, Therese/C-9558-2012; OI Kucera, Therese/0000-0001-9632-447X NR 23 TC 9 Z9 9 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP 424 EP 427 DI 10.1086/309109 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343MK UT WOS:000088706000042 ER PT J AU Hayward, TL Hanner, MS Sekanina, Z AF Hayward, TL Hanner, MS Sekanina, Z TI Thermal infrared imaging and spectroscopy of comet Hale-Bopp (C/1995 O1) SO ASTROPHYSICAL JOURNAL LA English DT Article DE comets : general; comets : individual (Hale-Bopp 1995 O1); interplanetary medium ID INTERPLANETARY DUST PARTICLES; INTERSTELLAR DUST; INNER COMA; SILICATE MINERALOGY; EMISSION PATTERN; SPIN VECTOR; GRAINS; NUCLEUS; MORPHOLOGY; SPECTRUM AB We present lambda = 3-5 and 8-13 mu m images and long-slit spectra of comet Hale-Bopp (C/1995 O1) taken in 1997 February-April, near the time of perihelion passage. In agreement with other infrared observations, we find that the 3-13 mu m spectral energy distribution was dominated by a 10 mu m silicate feature with a strong underlying continuum. In the nuclear region, the feature's peak flux-to-continuum ratio varied from 2.8 on February 17 to 3.3 on April 19, and the color temperature of the 3-5 mu m continuum was similar to 1.8 times the equilibrium blackbody temperature at the relevant heliocentric distance. Both quantities are larger than in any previous comet and indicate a high abundance of submicron dust particles. Spectral structure within the silicate feature reveals the presence of crystalline olivine and pyroxene grains. The physical properties of the grains, as evidenced by their infrared emission, correlated with the morphology. Within the visible jets and halos the silicate feature was up to 15% stronger, and the 8-13 mu m color temperature similar to 1.1 times higher, than in the regions between the halos. Therefore, the halos were enriched in submicron particles relative to the background, as expected from the higher outflow velocities of these small grains. Within the halos, there was no measurable variation in the strength of the silicate feature or the color temperature with distance from the nucleus; that is, we detect no time-dependent evolution of dust particle properties (such as fragmentation) on a timescale of one rotational cycle (between similar to 2 and 13 hr after ejection). The spectral shape of the silicate feature was essentially the same everywhere in the inner coma in all of our 1997 spectra. Monte Carlo simulation of dust particle motions in the coma indicates that the observed patterns of jets and halos were dominated by submicron-sized grains. Modeling of the thermal emission from small grains demonstrates that the principal features of the 3-13 mu m continuum and the 8-13 mu m silicate feature can be synthesized from a mixture of amorphous carbon and amorphous and crystalline silicates. The overall shape of the silicate feature resembled that in other bright comets, indicating a similar mineral mix. However, the 10.0 mu m peak was sharper in Hale-Bopp near perihelion than in any previously observed comet except comet Mueller (C/1993 A1) at 2 AU. C1 Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hayward, TL (reprint author), Gemini Observ, 670 N Aohoku Pl, Hilo, HI 96720 USA. NR 70 TC 53 Z9 54 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP 428 EP 455 DI 10.1086/309117 PN 1 PG 28 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343MK UT WOS:000088706000043 ER PT J AU Ake, TB Dupree, AK Young, PR Linsky, JL Malina, RF Griffiths, NW Siegmund, OHW Woodgate, BE AF Ake, TB Dupree, AK Young, PR Linsky, JL Malina, RF Griffiths, NW Siegmund, OHW Woodgate, BE TI Far Ultraviolet Spectroscopic Explorer observations of the active cool star AB Doradus SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : chromospheres; stars : flare; stars : individual (AB Doradus); stars : pre-main-sequence; ultraviolet : stars ID X-RAY OBSERVATIONS AB Far-ultraviolet spectra were obtained of the active cool star AB Doradus (HD 36705) during the calibration and checkout period of the Fur Ultraviolet Spectroscopic Explorer (FUSE) satellite. Observations in this early phase of the mission were taken at a resolving power of 12,000-15,000 (similar to 20-25 km s(-1)) and covered the spectral range 905-1187 Angstrom. The integrated spectrum exhibits strong, rotationally broadened stellar emission from C III (lambda lambda 977, 1175) and O VI (lambda lambda 1032, 1037) and many weaker lines. Strong emission lines of C III and O VI exhibit broad wings. The C III lambda 977 profile shows blueshifted absorption at similar to 30 km s(-1), and C II lambda 1036 absorption appears superposed on emission in the wing of O vr lambda 1037. Rotational modulation of C III and O VI is present, in harmony with its photometric variability. Flares were detected in the brightest lines, and subexposures were analyzed to examine flux and profile variations. Downflows that extend to 600 km s(-1) during a flare are found in the O VI profiles. These early observations demonstrate that FUSE will be an exceptional instrument for studying chromospheres in cool stars. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Comp Sci Corp, Lanham Seabrook, MD USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Gaithersburg, MD USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Ake, TB (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. RI Woodgate, Bruce/D-2970-2012 NR 14 TC 24 Z9 24 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP L87 EP L90 DI 10.1086/312796 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100020 ER PT J AU Bianchi, L Hutchings, JB Fullerton, AW Morton, DC Ohl, RG Sonneborn, G Massa, D Brownsberger, KR Willis, AJ AF Bianchi, L Hutchings, JB Fullerton, AW Morton, DC Ohl, RG Sonneborn, G Massa, D Brownsberger, KR Willis, AJ TI Measuring the ionization of O star winds SO ASTROPHYSICAL JOURNAL LA English DT Article DE Magellanic Clouds; stars : early-type; stars : winds, outflows; ultraviolet : stars ID LARGE MAGELLANIC CLOUD; STELLAR WINDS; HOT STARS; SPECTROSCOPY; ULTRAVIOLET; SUPERGIANTS; TELESCOPE; GALAXIES; M31 AB We present an analysis of wind line profiles from Far Ultraviolet Spectroscopic Explorer (FUSE) spectra of two O7 supergiants in the Large and Small Magellanic Clouds (Sk -67 degrees 111 and AV 232, respectively). Model fits yield the column densities of S IV, S VI, P IV, P V, N III, and N IV, providing the first direct measurement of the ionization balance in stellar winds. The ratios of S IV/S VI and P IV/P V are consistently lower in the LMC star. IUE and Hubble Space Telescope archival spectra are also used to measure N IV and N V, but the much higher optical depth makes the N V measurements inconclusive. The velocity and optical depth distributions in the wind are qualitatively similar between the two stars, when scaled to their terminal velocities. The terminal velocities are different, with AV 232 being lower (as found previously in SMC stars and linked to lower metallicity). These are the first results from a program to investigate wind ionization and velocity structure among hot stars in local galaxies, and they demonstrate the higher accuracy in measuring column densities of less abundant ions, such as phosphorus and sulfur, observable in the FUSE range. C1 Johns Hopkins Univ, Dept Phys & Astron, Ctr Astrophys Sci, Baltimore, MD 21218 USA. Osserv Astron Torino, Pino Torinese, TO, Italy. Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V8X 4M6, Canada. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Raytheon Informat Technol Serv, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Sci Serv, Greenbelt, MD 20771 USA. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. UCL, Dept Phys & Astron, London WC1E 6BT, England. RP Bianchi, L (reprint author), Johns Hopkins Univ, Dept Phys & Astron, Ctr Astrophys Sci, 3400 Charles St, Baltimore, MD 21218 USA. RI Sonneborn, George/D-5255-2012 NR 24 TC 12 Z9 12 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP L57 EP L60 DI 10.1086/312789 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100013 ER PT J AU Chayer, P Kruk, JW Ake, TB Dupree, AK Malina, RF Siegmund, OHW Sonneborn, G Ohl, RG AF Chayer, P Kruk, JW Ake, TB Dupree, AK Malina, RF Siegmund, OHW Sonneborn, G Ohl, RG TI The discovery of photospheric phosphorus and iron in the Far Ultraviolet Spectroscopic Explorer spectrum of the hot DA white dwarf GD 394 SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : abundances; stars : individual (GD 394); white dwarfs ID RADIATIVE LEVITATION; ATMOSPHERES; EXOSAT; FEATURES; ROSAT; EUV AB We report the discovery of the photospheric P V 3s((2)S)-3p((2)P(o)) transitions and Fe III 3d(6)((5)D)-3d(5)((6)S)4p((5)p(o)) transitions detected in the far-UV spectrum of the hot hydrogen-rich white dwarf GD 394. The spectrum was obtained with the Far Ultraviolet Spectroscopic Explorer using the large aperture. The spectrum covers a wavelength range of 910-1180 Angstrom at a resolution of lambda/Delta lambda similar to 15,000. The presence of photospheric phosphorus and iron is the first hi-ill detection of heavy elements other than silicon in the photosphere of GD 394, This detection confirms Extreme Ultraviolet Explorer observations, which show evidence of heavy elements in the photosphere of GD 394 with relatively low individual abundances. The spectrum reveals also a host of photospheric Si III and Si IV features. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. Ctr Astrophys, Cambridge, MA 02138 USA. Lab Astron Spatiale Mareille, F-13120 Marseille, France. Univ Calif Berkeley, Ctr Euv Astrophys, Berkeley, CA 94720 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Chayer, P (reprint author), Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RI Sonneborn, George/D-5255-2012; Kruk, Jeffrey/G-4047-2012 NR 21 TC 13 Z9 13 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP L91 EP L94 DI 10.1086/312790 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100021 ER PT J AU Crowther, PA Fullerton, AW Hillier, DJ Brownsberger, K Dessart, L Willis, AJ De Marco, O Barlow, MJ Hutchings, JB Massa, DL Morton, DC Sonneborn, G AF Crowther, PA Fullerton, AW Hillier, DJ Brownsberger, K Dessart, L Willis, AJ De Marco, O Barlow, MJ Hutchings, JB Massa, DL Morton, DC Sonneborn, G TI Far Ultraviolet Spectroscopic Explorer spectroscopy of the O vi resonance doublet in Sand 2 (WO) SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : evolution; stars : individual (Sand 2); stars : Wolf-Rayet ID LARGE-MAGELLANIC-CLOUD; RAYET STARS; WC STARS; SPECTRAL ANALYSES; MASSIVE STARS; EXTINCTION; LMC AB We present Fnr Ultraviolet Spectroscopic Explorer spectroscopy of Sand 2, an LMC WO-type Wolf-Rayet star, revealing the O VI resonance P Cygni doublet at 1032-1038 Angstrom. These data are combined with Hubble Space Telescopic Faint Object Spectrograph ultraviolet and Mount Stromlo 2.3 m optical spectroscopy and analyzed using a spherical, non-LTE, line-blanketed code. Our study reveals exceptional stellar parameters: T* similar to 150,000 K, v(infinity) = 4100 km s(-1), log (L/L(.)) = 5.3, and (M)over dot = 1 x 10(-5) M. yr(-1), if we adopt a volume filling factor of 10%. Elemental abundances of C/He similar to 0.7 + 0.2 and O/He similar to 0.15(-0.05)(+0.10) by number qualitatively support previous recombination line studies. We confirm that Sand 2 is more chemically enriched in carbon than LMC WC stars and that it is expected to undergo a supernova explosion within the next 5 x 10(4) yr. C1 UCL, Dept Phys & Astron, London WC1E 6BT, England. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Pittsburgh, Dept Phys & Astron, Pittsburgh, PA 15260 USA. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Natl Res Council Canada, Herzberg Inst Astrophys, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. NASA, Goddard Space Flight Ctr, Raytheon Informat Technol Serv, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Sci Serv, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Crowther, PA (reprint author), UCL, Dept Phys & Astron, Gower St, London WC1E 6BT, England. RI Barlow, Michael/A-5638-2009; Sonneborn, George/D-5255-2012 OI Barlow, Michael/0000-0002-3875-1171; NR 27 TC 25 Z9 25 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP L51 EP L55 DI 10.1086/312783 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100012 ER PT J AU Friedman, SD Howk, JC Andersson, BG Sembach, KR Ake, TB Roth, K Sahnow, DJ Savage, BD York, DG Sonneborn, G Vidal-Madjar, A Wilkinson, E AF Friedman, SD Howk, JC Andersson, BG Sembach, KR Ake, TB Roth, K Sahnow, DJ Savage, BD York, DG Sonneborn, G Vidal-Madjar, A Wilkinson, E TI Far Ultraviolet Spectroscopic Explorer observations of interstellar gas toward the large magellanic cloud star Sk-67 degrees 05 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (Large Magellanic Cloud); ISM : atoms; ultraviolet : ISM ID ABSORPTION-LINES; ABUNDANCES AB We report on measurements of interstellar O VI, H-2, P II, Si II, Ar I, and Fe II absorption along the line of sight to Sk -67 degrees 05, a B0 Ia star in a diffuse H II region in the western edge of the Large Magellanic Cloud (LMC). We find log N(O VI) = 14.40 +/- 0.04 in the Milky Way component and, using the C Iv column density from previous IUE observations, N(C IV)/N(O VI) = 1.00 +/- 0.16, a value similar to other halo measurements made with the Far Ultraviolet Spectroscopic Explorer. In the LMC component, log N(O VI) = 13.89 +/- 0.05 and N(C IV)/N(O VI) < 0.4 (3 a), since only an upper limit on N(C Iv) is available. Along this sight line, the LMC is rich in molecular hydrogen [log N(H-2) = 19.50 +/- 0.08]; in the Milky Way, log N(H-2) = 14.95 +/- 0.08. A two-component fit for the excitation temperature of the molecular gas in the LMC gives T-01 = 59 +/- 5 K for J = 0, 1 and T-ex = 800 +/- 330 K for J = 3, 4, 5. For the Milky Way, T-01 = 99(-20)(+30) K; no excitation temperature could be determined for the higher rotational states. The Milky Way and LMC gas-phase [Fe/P] abundances are similar to 0.6 and similar to 0.7 dex lower, respectively, than solar system abundances. These values are similar to [Fe/Zn] measurements for the Milky Way and LMC toward SN 1987 A. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Inst Astrophys, CNRS, F-75014 Paris, France. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. RP Friedman, SD (reprint author), Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RI Sonneborn, George/D-5255-2012; Howk, Jay/D-2577-2013 NR 22 TC 21 Z9 21 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP L39 EP L42 DI 10.1086/312800 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100009 ER PT J AU Fullerton, AW Crowther, PA De Marco, O Hutchings, JB Bianchi, L Brownsberger, KR Massa, DL Morton, DC Rachford, BL Snow, TP Sonneborn, G Tumlinson, J Willis, AJ AF Fullerton, AW Crowther, PA De Marco, O Hutchings, JB Bianchi, L Brownsberger, KR Massa, DL Morton, DC Rachford, BL Snow, TP Sonneborn, G Tumlinson, J Willis, AJ TI Far Ultraviolet Spectroscopic Explorer observations of the stellar winds of two O7 supergiants in the magellanic clouds SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : early-type; stars : individual (Sk-67 degrees 111, Sk 80); stars : winds, outflows ID INFRARED EXTINCTION LAW; RADIATION-DRIVEN WINDS; DUST RATIO; MASS-LOSS; STARS; UV; ABSORPTION; EVOLUTION; ANGSTROM; SPECTRA AB We compare the stellar wind features in far-UV spectra of Sk -67 degrees 111, an O7 Ib(f) star in the LMC, with Sk 80, an O7 Iaf+ star in the SMC. The most striking differences are that Sk 80 has a substantially lower terminal velocity, much weaker O VI absorption, and stronger S IV emission. We have used line-blanketed, hydrodynamic, non-LTE atmospheric models to explore the origin of these differences. The Tar-UV spectra require systematically lower stellar temperatures than previous determinations for O7 supergiants derived from plane-parallel, hydrostatic models of photospheric line profiles. At these temperatures, the O VI in Sk -67 degrees 111 must be due primarily to shocks in the wind. C1 Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21286 USA. UCL, Dept Phys & Astron, London WC1E 6BT, England. Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V8X 4M6, Canada. Osserv Astron Torino, I-10025 Pino Torinese, TO, Italy. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Raytheon Infomat Technol Serv, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Sci Serv, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Fullerton, AW (reprint author), Univ Victoria, Dept Phys & Astron, POB 3055, Victoria, BC V8W 3P6, Canada. EM awf@pha.jhu.edu RI Sonneborn, George/D-5255-2012 NR 29 TC 25 Z9 25 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP L43 EP L46 DI 10.1086/312787 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100010 ER PT J AU Kriss, GA Green, RF Brotherton, M Oegerle, W Sembach, KR Davidsen, AF Friedman, SD Kaiser, ME Zheng, W Woodgate, B Hutchings, J Shull, JM York, DG AF Kriss, GA Green, RF Brotherton, M Oegerle, W Sembach, KR Davidsen, AF Friedman, SD Kaiser, ME Zheng, W Woodgate, B Hutchings, J Shull, JM York, DG TI Far Ultraviolet Spectroscopic Explorer observations of intrinsic absorption in the Seyfert 1 galaxy Markarian 509 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (Markarian 509); galaxies : Seyfert; quasars : absorption lines; ultraviolet : galaxies; X-rays : galaxies ID C-IV ABSORPTION; X-RAY; LINES; EMISSION; NGC-5548; MRK-509; OUTFLOW; GAS AB We present far-ultraviolet spectra of the Seyfert 1 galaxy Mrk 509 obtained in 1999 November with the Fnr Ultraviolet Spectroscopic Explorer. Our data span the observed wavelength range 915-1185 Pi at a resolution of similar to 20 km s(-1). The spectrum shows a blue continuum, broad O VI lambda lambda 1032, 1038 emission, and a broad C III lambda 977 line. We resolve associated absorption lines of O VI lambda lambda 1032, 1038, C III lambda 977, and Lyman lines through Ly zeta, superposed on these emission components. Seven distinct kinematic components are present, spanning a velocity range from -440 to 170 km s(-1) relative to the systemic velocity. The absorption is clustered in two groups, one centered at -370 km s(-1) and another at the systemic velocity. The blueshifted cluster may be associated with the extended line emission visible in deep images of Mrk 509 obtained by Phillips et al. Although several components appear to be saturated, they are not black at their centers. Partial coveting or scattering permits similar to 7% of the broad-line or continuum flux to be unaffected by absorption. Of the multiple components, only one has the same ionization state and column density as highly ionized gas that produces the O VII and O VIII ionization edges in X-ray spectra of Mrk 509. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. Johns Hopkins Univ, Dept Phys & Astron, Ctr Astrophys Sci, Baltimore, MD 21218 USA. Kitt Peak Natl Observ, Natl Opt Astron Observ, Tucson, AZ 85726 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Res Council Canada, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Univ Colorado, Joint Inst Lab Astrophys, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Kriss, GA (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. RI Oegerle, William/C-9070-2012 NR 24 TC 53 Z9 53 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP L17 EP L21 DI 10.1086/312784 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100004 ER PT J AU Massa, D Fullerton, AW Hutchings, JB Morton, DC Sonneborn, G Willis, AJ Bianchi, L Brownsberger, KR Crowther, PA Snow, TP York, DG AF Massa, D Fullerton, AW Hutchings, JB Morton, DC Sonneborn, G Willis, AJ Bianchi, L Brownsberger, KR Crowther, PA Snow, TP York, DG TI The detection of wind variability in Magellanic Cloud O stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE Magellanic Clouds; stars : winds, outflows; ultraviolet : stars ID SUPERGIANTS; ULTRAVIOLET; HD-64760 AB We present Far Ultraviolet Spectroscopic Explorer (FUSE) spectra for three Magellanic Cloud O stars (Sk 80, Sk -67 degrees 05, and Sk -67 degrees 111) with repeated observations. The data demonstrate the capabilities of FUSE to perform time-resolved spectroscopy on extragalactic stars. The wavelength coverage of FUSE provides access to resonance lines due to less abundant species, such as sulfur, which are unsaturated in O supergiants. This allows us to examine wind variability at all velocities in resonance lines for stars with higher mass-loss rates than can be studied at longer (lambda greater than or equal to 1150 Angstrom) wavelengths. The FUSE wavelength range also includes resonance lines from ions that bracket the expected dominant ionization stage of the wind. Our observations span 1-4 months with several densely sampled intervals of 10 hr or more. These observations reveal wind variability in all of the program stars and distinctive differences in the ionization structure and timescales of the variability. Sk -67 degrees 111 demonstrates significant wind variability on a timescale less than 10 hr, and the coolest O star (Sk -67 degrees 05) exhibits the largest variations in O VI. C1 NASA, Goddard Space Flight Ctr, Raytheon Informat Technol Serv, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Sci Serv, Greenbelt, MD 20771 USA. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Natl Res Council Canada, Herzberg Inst Astrophys, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. UCL, Dept Phys & Astron, London WC1E 6BT, England. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Massa, D (reprint author), NASA, Goddard Space Flight Ctr, Raytheon Informat Technol Serv, Code 681-0, Greenbelt, MD 20771 USA. EM derck.massa@gsfc.nasa.gov RI Sonneborn, George/D-5255-2012 NR 20 TC 8 Z9 8 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP L47 EP L50 DI 10.1086/312788 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100011 ER PT J AU Moos, HW Cash, WC Cowie, LL Davidsen, AF Dupree, AK Feldman, PD Friedman, SD Green, JC Green, RF Gry, C Hutchings, JB Jenkins, EB Linsky, JL Malina, RF Michalitsianos, AG Savage, BD Shull, JM Siegmund, OHW Snow, TP Sonneborn, G Vidal-Madjar, A Willis, AJ Woodgate, BE York, DG Ake, TB Andersson, BG Andrews, JP Barkhouser, RH Bianchi, L Blair, WP Brownsberger, KR Cha, AN Chayer, P Conard, SJ Fullerton, AW Gaines, GA Grange, R Gummin, MA Hebrard, G Kriss, GA Kruk, JW Mark, D McCarthy, DK Morbey, CL Murowinski, R Murphy, EM Oegerle, WR Ohl, RG Oliveira, C Osterman, SN Sahnow, DJ Saisse, M Sembach, KR Weaver, HA Welsh, BY Wilkinson, E Zheng, W AF Moos, HW Cash, WC Cowie, LL Davidsen, AF Dupree, AK Feldman, PD Friedman, SD Green, JC Green, RF Gry, C Hutchings, JB Jenkins, EB Linsky, JL Malina, RF Michalitsianos, AG Savage, BD Shull, JM Siegmund, OHW Snow, TP Sonneborn, G Vidal-Madjar, A Willis, AJ Woodgate, BE York, DG Ake, TB Andersson, BG Andrews, JP Barkhouser, RH Bianchi, L Blair, WP Brownsberger, KR Cha, AN Chayer, P Conard, SJ Fullerton, AW Gaines, GA Grange, R Gummin, MA Hebrard, G Kriss, GA Kruk, JW Mark, D McCarthy, DK Morbey, CL Murowinski, R Murphy, EM Oegerle, WR Ohl, RG Oliveira, C Osterman, SN Sahnow, DJ Saisse, M Sembach, KR Weaver, HA Welsh, BY Wilkinson, E Zheng, W CA FUSE Sci Team FUSE Instrument Team FUSE Sci Operations Team TI Overview of the Far Ultraviolet Spectroscopic Explorer Mission SO ASTROPHYSICAL JOURNAL LA English DT Article DE instrumentation : spectrographs; space vehicles; telescopes; ultraviolet : general ID PERFORMANCE; FUSE; TELESCOPE; DESIGN; SPECTROGRAPH; CALIBRATION; VOYAGER; GAS AB The Far Ultraviolet Spectroscopic Explorer satellite observes light in the far-ultraviolet spectral region, 905-1187 Angstrom, with a high spectral resolution. The instrument consists of four co-aligned prime-focus telescopes and Rowland spectrographs with microchannel plate detectors. Two of the telescope channels use Al :LiF coatings for optimum reflectivity between approximately 1000 and 1187 Angstrom, and the other two channels use SiC coatings for optimized throughput between 905 and 1105 Angstrom. The gratings are holographically ruled to correct largely for astigmatism and to minimize scattered light. The microchannel plate detectors have KBr photocathodes and use photon counting to achieve good quantum efficiency with low background signal. The sensitivity is sufficient to examine reddened lines of sight within the Milky Way and also sufficient to use as active galactic nuclei and QSOs for absorption-line studies of both Milky Way and extragalactic gas clouds. This spectral region contains a number of key scientific diagnostics, including O VI, H I, D I, and the strong electronic transitions of H(2) and HD. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Colorado, Dept Astrophys & Planetary Sci, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Ctr Astrophys, Cambridge, MA 02138 USA. Natl Opt Astron Observ, Tucson, AZ 85726 USA. Astron Spatiale Lab, F-13376 Marseille 12, France. ISO Data Ctr, ESA Astrophys Div, Madrid 28080, Spain. Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V8X 4M6, Canada. Princeton Univ Observ, Princeton, NJ 08544 USA. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Boulder, CO 80309 USA. Univ Calif Berkeley, Ctr EUV Astrophys, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Inst Astrophys, CNRS, F-75014 Paris, France. UCL, Dept Phys & Astron, London WC1E 6BT, England. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Comp Sci Corp, Lanham, MD 20706 USA. Osserv Astron Torino, I-10025 Pino Torinese, TO, Italy. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Swales Associates, Beltsville, MD 20705 USA. RP Moos, HW (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, 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; Jenkins, Edward/P-5684-2014; Weaver, Harold/D-9188-2016 OI Jenkins, Edward/0000-0003-1892-4423; NR 46 TC 383 Z9 384 U1 5 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 JUL 20 PY 2000 VL 538 IS 1 BP L1 EP L6 DI 10.1086/312795 PN 2 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100001 ER PT J AU Sahnow, DJ Moos, HW Ake, TB Andersen, J Andersson, BG Andre, M Artis, D Berman, AF Blair, WP Brownsberger, KR Calvani, HM Chayer, P Conard, SJ Feldman, PD Friedman, SD Fullerton, AW Gaines, GA Gawne, WC Green, JC Gummin, MA Jennings, TB Joyce, JB Kaiser, ME Kruk, JW Lindler, DJ Massa, D Murphy, EM Oegerle, WR Ohl, RG Roberts, BA Romelfanger, ML Roth, KC Sankrit, R Sembach, KR Shelton, RL Siegmund, OHW Silva, CJ Sonneborn, G Vaclavik, SR Weaver, HA Wilkinson, E AF Sahnow, DJ Moos, HW Ake, TB Andersen, J Andersson, BG Andre, M Artis, D Berman, AF Blair, WP Brownsberger, KR Calvani, HM Chayer, P Conard, SJ Feldman, PD Friedman, SD Fullerton, AW Gaines, GA Gawne, WC Green, JC Gummin, MA Jennings, TB Joyce, JB Kaiser, ME Kruk, JW Lindler, DJ Massa, D Murphy, EM Oegerle, WR Ohl, RG Roberts, BA Romelfanger, ML Roth, KC Sankrit, R Sembach, KR Shelton, RL Siegmund, OHW Silva, CJ Sonneborn, G Vaclavik, SR Weaver, HA Wilkinson, E TI On-orbit performance of the Far Ultraviolet Spectroscopic Explorer satellite SO ASTROPHYSICAL JOURNAL LA English DT Article DE instrumentation : spectrographs; space vehicles; ultraviolet : general ID MICROCHANNEL PLATES; FUSE; CALIBRATION; TELESCOPE; SPECTROGRAPH; MISSION; DESIGN AB The launch of the Far Ultraviolet Spectroscopic Explorer (FUSE) has been followed by an extensive period of calibration and characterization as part of the preparation for normal satellite operations. Major tasks carried out during this period include the initial coalignment, focusing, and characterization of the four instrument channels and a preliminary measurement of the resolution and throughput performance of the instrument. We describe the results from this test program and present preliminary estimates of the on-orbit performance of the FUSE satellite based on a combination of these data and prelaunch laboratory measurements. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Comp Sci Corp, Laurel, MD 20707 USA. Honeywell Technol Solut Inc, Columbia, MD 21045 USA. Inst Astrophys, INSU, CNRS, F-75014 Paris, France. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Adv Comp Concepts Inc, Greenbelt, MD 20771 USA. Raytheon Co, Informat Technol Serv, Greenbelt, MD 20771 USA. Raytheon Co, Sci Serv, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Sahnow, DJ (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. RI Oegerle, William/C-9070-2012; Sonneborn, George/D-5255-2012; Kruk, Jeffrey/G-4047-2012; Weaver, Harold/D-9188-2016 NR 19 TC 320 Z9 320 U1 5 U2 7 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP L7 EP L11 DI 10.1086/312794 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100002 ER PT J AU Savage, BD Sembach, KR Jenkins, EB Shull, JM York, DG Sonneborn, G Moos, HW Friedman, SD Green, JC Oegerle, WR Blair, WP Kruk, JW Murphy, EM AF Savage, BD Sembach, KR Jenkins, EB Shull, JM York, DG Sonneborn, G Moos, HW Friedman, SD Green, JC Oegerle, WR Blair, WP Kruk, JW Murphy, EM TI Far Ultraviolet Spectroscopic Explorer observations of O vi absorption in the galactic halo SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : halos; galaxies : structure; ISM : atoms; ISM : structure; ultraviolet : ISM ID IONIZED INTERSTELLAR GAS; CORONAL GAS; GALAXY; LINES AB Far-ultraviolet spectra of 11 active galactic nuclei observed by Far Ultraviolet Spectroscopic Explorer (FUSE) are analyzed to obtain measures of O VI lambda 1031.93 absorption occurring over very long paths through Milky Way halo gas. Strong O VI absorption is detected along 10 of 11 sight lines. Values of log [N(O VI) sin \b\] range from 13.80 to 14.64, with a median value of 14.21. The observations reveal the existence of a widespread but irregular distribution of O VI in the Milky Way halo. Combined with estimates of the O VI midplane density, n(0) = 2 x 10(-8) cm(-3), from the Copernicus satellite, the FUSE observations imply an O VI exponential scale height of 2.7 +/- 0.4 kpc. We find that N(C IV)/N(O VI) ranges from similar to 0.15 in the disk to similar to 0.6 along four extragalactic sight lines. The changing ionization state of the gas from the disk to the halo is consistent with a systematic decrease in the scale heights of Si IV, C IV, N V, to O VI from similar to 5.1 to similar to 2.7 kpc. While conductive heating models can account for the highly ionized atoms at low \z\,a combination of models land processes) appears to be required to explain the highly ionized atoms found in the halo. The greater scale heights of Si IV and C IV compared to O VI suggests that some of the Si IV and C IV in the halo is produced in turbulent mixing layers or by photoionization by hut halo stars or the extragalactic background. C1 Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Princeton Univ Observ, Princeton, NJ 08544 USA. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Univ Colorado, Joint Inst Lab Astrophys, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Savage, BD (reprint author), Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. 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 34 TC 68 Z9 68 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 JUL 20 PY 2000 VL 538 IS 1 BP L27 EP L30 DI 10.1086/312792 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100006 ER PT J AU Sembach, KR Savage, BD Shull, JM Jenkins, EB Murphy, EM York, DG Ake, T Blair, WP Davidsen, AF Friedman, SD Gibson, BK Kruk, JW Moos, HW Oegerle, WR Sahnow, D Sonneborn, G AF Sembach, KR Savage, BD Shull, JM Jenkins, EB Murphy, EM York, DG Ake, T Blair, WP Davidsen, AF Friedman, SD Gibson, BK Kruk, JW Moos, HW Oegerle, WR Sahnow, D Sonneborn, G TI Far Ultraviolet Spectroscopic Explorer observations of O vi in high-velocity clouds SO ASTROPHYSICAL JOURNAL LA English DT Article DE Galaxy : halo; intergalactic medium; ISM : clouds; ISM : evolution; ISM : kinematics and dynamics; ultraviolet : ISM ID GALACTIC HALO; GAS AB We have used moderate-resolution (FWHM approximate to 25 km s(-1)) spectra of active galactic nuclei and QSOs observed by the Far Ultraviolet Spectroscopic Explorer to make the first definitive measurements of absorption by hot gas in high-velocity clouds (HVCs) at large distances from the Galactic plane. Seven of the Il sight lines studied exhibit high-velocity (/V-LSR/ > 100 km s(-1)) O VI lambda 1031.93 absorption with log N(O vr) approximate to 13.79-14.62. High-velocity O VI absorption is detected in the distant gas of H I HVC complex C, the Magellanic Stream, several HVCs believed to be in the Local Group, and the outer Galaxy. The fraction of O VI in HVCs along the seven sight lines containing high-velocity O VI averages similar to 30%, with a full range of similar to 10%-70%. The O vr detections imply that hut (T similar to 3 x 10(5) K), collisionally ionized gas is an important constituent of the HVCs since O VI is difficult to produce by photoionization unless the path lengths over which the absorption occurs are very large (>100 kpc), The association of O VI with H I HVCs in many cases suggests that the O VI may be produced at interfaces or mixing layers between the H I clouds and hot, low-density gas in the Galactic corona or Local Group Alternatively, the O vr may originate within cooling regions of hot gas clouds as they are accreted onto the Galaxy. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Univ Colorado, Ctr Astrophys & Space Astron, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA. Princeton Univ Observ, Princeton, NJ 08544 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Sembach, KR (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; Jenkins, Edward/P-5684-2014; Gibson, Brad/M-3592-2015 OI Jenkins, Edward/0000-0003-1892-4423; Gibson, Brad/0000-0003-4446-3130 NR 32 TC 71 Z9 71 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP L31 EP L34 DI 10.1086/312785 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100007 ER PT J AU Shull, JM Tumlinson, J Jenkins, EB Moos, HW Rachford, BL Savage, BD Sembach, KR Snow, TP Sonneborn, G York, DG Blair, WP Green, JC Friedman, SD Sahnow, DJ AF Shull, JM Tumlinson, J Jenkins, EB Moos, HW Rachford, BL Savage, BD Sembach, KR Snow, TP Sonneborn, G York, DG Blair, WP Green, JC Friedman, SD Sahnow, DJ TI Far Ultraviolet Spectroscopic Explorer observations of diffuse interstellar molecular hydrogen SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (Large Magellanic Cloud, Small Magellanic Cloud); ISM : clouds; ISM : molecules; ultraviolet : ISM ID GAS AB We describe a moderate-resolution Far Ultraviolet Spectroscopic Explorer (FUSE) minisurvey of H-2 in the Milky Way and Magellanic Clouds using four hot stars and four active galactic nuclei as background sources. FUSE spectra of nearly every stellar and extragalactic source exhibit numerous absorption lines from the H-2 Lyman and Werner bands between 912 and 1120 Angstrom. One extragalactic sight line (PKS 2155-304) with low N(H I) shows no detectable H-2 and could be the "Lockman Hole of molecular gas," of importance for QSO absorption-line studies. We measure H-2 column densities in low rotational states (J = O and 1) to derive rotational and/or kinetic temperatures of diffuse interstellar gas. The higher J abundances can constrain models of the UV radiation fields and gas densities. In three optically thick clouds toward extragalactic sources, we find n(H) approximate to 30-50 cm(-3) and cloud thicknesses similar to 2-3 pc. The rotational temperatures for H-2 at high Galactic latitude, (T-01) = 107 +/- 17 K (seven sight lines) and 120 +/- 13 K (three optically thick clouds), are higher than those in the Copernicus sample composed primarily of targets in the disk. We find no evidence for great differences in the abundance or state of excitation of H-2 between sight lines in the Galaxy and those in the SMC and LMC. In the future, we will probe the distribution and physical parameters of diffuse molecular gas in the disk and halo and in the lower metallicity environs of the LMC and SMC. C1 Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Gaithersburg, MD USA. Princeton Univ, Dept Astrophys Sci, Princeton, NJ 08544 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Shull, JM (reprint author), Univ Colorado, Ctr Astrophys & Space Astron, Campus Box 391, Boulder, CO 80309 USA. RI Jenkins, Edward/P-5684-2014 OI Jenkins, Edward/0000-0003-1892-4423 NR 21 TC 82 Z9 82 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP L73 EP L76 DI 10.1086/312782 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100017 ER PT J AU Shull, JM Giroux, ML Penton, SV Tumlinson, J Stocke, JT Jenkins, EB Moos, HW Oegerle, WR Savage, BD Sembach, KR York, DG Green, JC Woodgate, BE AF Shull, JM Giroux, ML Penton, SV Tumlinson, J Stocke, JT Jenkins, EB Moos, HW Oegerle, WR Savage, BD Sembach, KR York, DG Green, JC Woodgate, BE TI Far Ultraviolet Spectroscopic Explorer observations of the low-redshift Ly beta forest SO ASTROPHYSICAL JOURNAL LA English DT Article DE intergalactic medium; quasars : absorption lines; ultraviolet : galaxies ID ABSORPTION-LINE SYSTEMS; INTERGALACTIC MEDIUM; ALPHA FOREST; CLOUDS; VOIDS; HALO AB We describe a moderate-resolution (20-25 km s(-1)) Far Ultraviolet Spectroscopic Explorer (FUSE) study of the low-redshift intergalactic medium. We report on studies of seven extragalactic sight lines and 12 Ly beta absorbers that correspond to Ly alpha lines detected by Hubble Space Telescope (HST)/Goddard High Resolution Spectrograph and Space Telescope imaging Spectrograph. These absorbers appear to contain a significant fraction of the low-z baryons and were a major discovery of the HST spectrographs. Using FUSE data, with 40 m Angstrom (4 sigma) Ly beta detection limits, we have employed the equivalent width ratio of Ly beta/Ly alpha, and occasionally higher Lyman lines, to determine the Doppler parameter b and accurate column densities N-H, for moderately saturated lines. We detect Ly beta absorption corresponding to all Ly alpha lines with W-lambda greater than or equal to 200 m Angstrom. The Ly beta/Ly alpha ratios yield a preliminary distribution function of Doppler parameters, with mean (b) = 31.4 +/- 7.4 km s(-1) and median 28 km s(-1), comparable to values at redshifts z = 2.0-2.5. If thermal, these b-values correspond to T-H1 approximate to 50,000 K, although the inferred Doppler parameters are considerably less than the widths derived from Ly alpha profile fitting, (b/b(width)) = 0.52. The typical increase in column density over that derived from profile fitting is Delta log N-H1 = 0.3, but ranges up to 1.0 dex. Our data suggest that the low-z Lya, absorbers contain sizable nonthermal motions or velocity components in the line profile, perhaps arising from cosmological expansion and infall. C1 Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Gaithersburg, MD USA. Princeton Univ, Dept Astrophys Sci, Princeton, NJ 08544 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Shull, JM (reprint author), Univ Colorado, Ctr Astrophys & Space Astron, Campus Box 391, Boulder, CO 80309 USA. RI Oegerle, William/C-9070-2012; Woodgate, Bruce/D-2970-2012; Jenkins, Edward/P-5684-2014 OI Jenkins, Edward/0000-0003-1892-4423 NR 32 TC 38 Z9 38 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP L13 EP L16 DI 10.1086/312781 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100003 ER PT J AU Vidal-Madjar, A Kunth, D des Etangs, AL Lequeux, J Andre, M BenJaffel, L Ferlet, R Hebrard, G Howk, JC Kruk, JW Lemoine, M Moos, HW Roth, KC Sonneborn, G York, DG AF Vidal-Madjar, A Kunth, D des Etangs, AL Lequeux, J Andre, M BenJaffel, L Ferlet, R Hebrard, G Howk, JC Kruk, JW Lemoine, M Moos, HW Roth, KC Sonneborn, G York, DG TI No diffuse H-2 in the metal-deficient galaxy I Zw 18 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : abundances; galaxies : dwarf; galaxies : individual (I Zw 18) galaxies : ISM; ISM : molecules; ultraviolet : galaxies ID BLUE COMPACT GALAXIES; STAR-FORMATION; MOLECULAR-HYDROGEN; CO; CONSTRAINTS; EVOLUTION; I-ZW-18; IZW-18; GAS AB The metal-deficient starburst galaxy I Zw 18 has been observed with the Fnr Ultraviolet Spectroscopic Explorer (FUSE) in a search for H-2 molecules. The spectrum obtained with an aperture covering the full galaxy shows no absorption lines of diffuse H-2 at the radial velocity of the galaxy. The upper limit for the diffuse H-2 column density is found to be very low, N(H-2) less than or equal to 10(15) cm(-2) (10 sigma), unlike our Galaxy where H-2 is generally present for even low H I column densities. Although the H I column density here is as high as N(H I) approximate to 2 x 10(21) cm(-2) we observe 2N(H-2)/N(H I) << 10(-6). We cannot exclude the possibility that some H-2 could be in very dense, small, and discrete clumps that cannot be detected with the present observation. However, the remarkable absence of diffuse H, in this metal-poor galaxy can be explained by the low abundance of dust grains (needed to form this molecule from H atoms), the high ultraviolet flux, and the low density of the H I cloud surrounding the star-forming regions. Thus, having eliminated diffuse H-2 as a significant contributor to the total mass, it appears that the gas of the galaxy is dominated by H I and that the high dynamical mass is not composed of cold and diffuse baryonic dark matter. C1 Inst Astrophys, CNRS, F-75014 Paris, France. Observ Paris, Dept Mat Interstellaire & Radioastron Millimetr, F-75014 Paris, France. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Observ Paris Meudon, CNRS, UMR 8629, Dept Astrophys Relativiste & Cosmol, F-92195 Meudon, France. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Vidal-Madjar, A (reprint author), Inst Astrophys, CNRS, 98 Bis Blvd Arago, F-75014 Paris, France. RI Sonneborn, George/D-5255-2012; Kruk, Jeffrey/G-4047-2012; Howk, Jay/D-2577-2013 NR 24 TC 42 Z9 42 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 2000 VL 538 IS 1 BP L77 EP L80 DI 10.1086/312797 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 343ML UT WOS:000088706100018 ER PT J AU Nelson, R Jimenez, J Schnell, CE Hartshorn, GS Gregoire, TG Oderwald, R AF Nelson, R Jimenez, J Schnell, CE Hartshorn, GS Gregoire, TG Oderwald, R TI Canopy height models and airborne lasers to estimate forest biomass: two problems SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID AREA AB Three ground datasets were used to simulate the canopy height characteristics of tropical forests in Costa Rica for the purposes of forest biomass estimation. The canopy height models (CHMs) were used in conjunction with airborne laser data. Gross biomass estimation errors on the order of 50-90% arose in two of the three analyses. The characteristics of the datasets and the biomass estimation procedure are reviewed to identify sources of error. In one dataset, the width of the fixed-area ground plots were small enough (5m) that significant portions of the overstory canopy above the plots were not accounted for in the ground samples. The use of mapped stand data from thin ground plots resulted in inaccurate CHMs, which in turn lead to gross overestimates of forest biomass (about 90% larger than the ground reference value). CHMs generated using mensuration data collected on thin, fixed-area plots may significantly underestimate the average canopy height and crown closure actually found on that plot. This underestimation problem is directly related to plot width. Below a critical threshold, the thinner the plot, the greater the underestimation bias. In the second dataset, it is believed that lower-than-normal rainfalls at the beginning and end of the wet season may have produced a forest canopy with reduced leaf area. The airborne laser pulses penetrated further into the canopy, resulting in airborne laser estimates of forest biomass which grossly underestimated reference values by about 50%. Changing canopy conditions (e.g. leaf loss due to drought, insect defoliation, storm damage) can affect the accuracy of a CHM. Sources of error are reported in order to forewarn those researchers who produce and utilize canopy height models. C1 NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. Org Trop Studies, Montes de Oca, Costa Rica. Org Trop Studies, Durham, NC 27708 USA. Yale Univ, Sch Forestry & Environm Studies, New Haven, CT 06511 USA. Virginia Tech, Dept Forestry, Coll Forestry & Wildlife Resources, Blacksburg, VA 24061 USA. RP Nelson, R (reprint author), NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Code 923, Greenbelt, MD 20771 USA. RI Nelson, Ross/H-8266-2014 NR 6 TC 19 Z9 20 U1 0 U2 9 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 20 PY 2000 VL 21 IS 11 BP 2153 EP 2162 DI 10.1080/01431160050029486 PG 10 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 332JH UT WOS:000088070200003 ER PT J AU D'Arrigo, RD Malmstrom, CM Jacoby, GC Los, SO Bunker, DE AF D'Arrigo, RD Malmstrom, CM Jacoby, GC Los, SO Bunker, DE TI Correlation between maximum latewood density of annual tree rings and NDVI based estimates of forest productivity SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID NET PRIMARY PRODUCTION; SATELLITE DATA; TEMPERATURE; GROWTH; NORTH; PARAMETERS; LATITUDES; CLIMATE; AMERICA; RECORD AB In boreal conifers, maximum latewood density (MXD) of annual rings varies in response to warm-season temperatures. Vegetation productivity can be estimated using the Normalized-Difference Vegetation Index: (NDVI) calculated from satellite sensor data. Ground measurements related to productivity are required in order to evaluate these estimates. MXD from three boreal sites was compared with estimates of net primary productivity (NPP) for 1982-1990 produced by the CASA (Carnegie-Ames-Stanford-Approach) model from FASIR (Fourier adjustments, solar zenith angle correction, interpolation at high latitudes, and reconstruction of tropical values) NDVI. All three density series correlated significantly with the CASA estimates, suggesting that in boreal conifers MXD may be an appropriate index for productivity or canopy growth in regions where productivity is strongly temperature-related. C1 Lamont Doherty Earth Observ, Tree Ring Lab, Palisades, NY 10964 USA. Michigan State Univ, Dept Bot & Plant Pathol, E Lansing, MI 48824 USA. NASA, Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. RP D'Arrigo, RD (reprint author), Lamont Doherty Earth Observ, Tree Ring Lab, Palisades, NY 10964 USA. RI Los, Sietse/G-8985-2012; OI Los, Sietse/0000-0002-1325-3555 NR 23 TC 25 Z9 34 U1 4 U2 35 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 20 PY 2000 VL 21 IS 11 BP 2329 EP 2336 DI 10.1080/01431160050029611 PG 8 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 332JH UT WOS:000088070200016 ER PT J AU Yee, HC Vinokur, M Djomehri, MJ AF Yee, HC Vinokur, M Djomehri, MJ TI Entropy splitting and numerical dissipation SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE entropy variables; symmetrizable nonlinear conservation laws; thermally perfect gas; low dissipation; high order methods; compact schemes; high order central differencings; shock-capturing methods; nonlinear filters; conservative differencing; TVD schemes; positive schemes; ENO schemes ID HYPERBOLIC CONSERVATION-LAWS; FINITE-DIFFERENCE; TVD SCHEMES; RESOLUTION; EQUATIONS; SUMMATION; SYSTEMS; FLOWS; EULER; PARTS AB A rigorous stability estimate for arbitrary order of accuracy of spatial central difference schemes for initial boundary value problems of nonlinear symmetrizable systems of hyperbolic conservation laws was established recently by Olsson and Oliger (1994, "Energy and Maximum Norm Estimates for Nonlinear Conservation Laws," RIACS Report, NASA Ames Research Center) and Olsson (1995, Math. Comput. 64, 212) and was applied to the two-dimensional compressible Euler equations fur a perfect gas by Gerritsen and Olsson (1996, J. Comput. Phys. 129, 245) and Gerritsen (1996, "Designing an Efficient Solution Strategy for Fluid Flows, Ph. D. Thesis, Stanford). The basic building block in developing the stability estimate is a generalized energy approach based on a special splitting of the flux derivative via a convex entropy function and certain homogeneous properties. Due to some of the unique properties of the compressible Euler equations for a perfect gas, the splitting resulted in the sum of a conservative portion and a non-conservative portion of the flux derivative, hereafter referred to as the "entropy splitting." There art: several potentially desirable attributes and side benefits of the entropy splitting for the compressible Euler equations that were not fully explored in Gerritsen and Olsson. This paper has several objectives, The first is to investigate the choice of the arbitrary parameter that determines the amount of splitting and its dependence on the type of physics of current interest to computational fluid dynamics. The second is to investigate in what manner the splitting affects the nonlinear stability of the central schemes fur long time integrations of unsteady Rows such as in nonlinear aeroacoustics and turbulence dynamics. If numerical dissipation indeed is needed to stabilize the central scheme, can the splitting help minimize the numerical dissipation compared to its un-split cousin? Extensive numerical study on the vortex preservation capability of the splitting in conjunction with central schemes furlong time integrations will be presented. The third is to study the effect of the non-conservative proportion of splitting in obtaining the correct shock location for high speed complex shock-turbulence interactions. The fourth is to determine if this method can be extended to other physical equations of state and other evolutionary equation sets. Tf numerical dissipation is needed, the Yee, Sandham, and Djomehri (1999, J. Comput. Phys. 150, 199) numerical dissipation is employed. The Yee er al. schemes fit in the Olsson and Oliger framework. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Yee, HC (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 49 TC 65 Z9 67 U1 0 U2 3 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD JUL 20 PY 2000 VL 162 IS 1 BP 33 EP 81 DI 10.1006/jeph.2000.6517 PG 49 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 334GD UT WOS:000088177900002 ER PT J AU Cottet, GH Koumoutsakos, P Salihi, MLO AF Cottet, GH Koumoutsakos, P Salihi, MLO TI Vortex methods with spatially varying cores SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE vortex methods; variable filters; domain decomposition ID SIMULATIONS; EQUATIONS AB The accuracy of vortex methods employing smooth vortex particles/blobs is determined by the blob size, which can be viewed as a mollifier of the vorticity field. For computational efficiency, this core size needs to be spatially variable as particles are used to discretize different parts of the flow field, such as the boundary layer and the wake in bluff body flows. We derive here a consistent approximation for the viscous Navier-Stokes equations using variable size vortex particles. This derivation is based on the implementation of mappings that allow the consistent formulation of the diffusion and convection operators of the Navier-Stokes equations in the context of vortex methods. Several local mappings can be combined giving the capability of "mesh-embedding" to vortex methods. It is shown that the proposed variable method offers a significant improvement on the computational efficiency of constant core size methods while maintaining the adaptive character of the method. The method is ideally suited to flows such as wakes and shear layers and the validity of the approach is illustrated by showing results from cylinder flows and wall-vortex interactions. Using this scheme, previously unattainable simulations of cylinders undergoing rotary oscillations at high Reynolds numbers reveal an interesting mechanism for drastic drag reduction. (C) 2000 Academic Press. C1 Univ Grenoble 1, IMAG, LMC, Grenoble, France. ETH Zurich, Inst Computat Sci, CH-8092 Zurich, Switzerland. NASA, Ames Res Ctr, CTR, Moffett Field, CA 94035 USA. RP Cottet, GH (reprint author), Univ Grenoble 1, IMAG, LMC, Grenoble, France. RI Koumoutsakos, Petros/A-2846-2008 OI Koumoutsakos, Petros/0000-0001-8337-2122 NR 15 TC 43 Z9 43 U1 0 U2 5 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD JUL 20 PY 2000 VL 162 IS 1 BP 164 EP 185 DI 10.1006/jeph.2000.6531 PG 22 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 334GD UT WOS:000088177900007 ER PT J AU Aloisio, S Francisco, JS Friedl, RR AF Aloisio, S Francisco, JS Friedl, RR TI Experimental evidence for the existence of the HO2-H2O complex SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID GAS-PHASE; SELF-REACTION; WATER-VAPOR; KINETICS; HO2; DEPENDENCE; MECHANISM AB Complex formation in the interaction of HO2 with H2O was studied using Fourier transform infrared absorption spectroscopy. Studies were carried out between 230 and 298 K in the presence of excess H2O. On the basis of measurements of HO2 disappearance, equilibrium constants (K-c) for the formation of the complex were determined to be 1.7 x 10(-16), 4.1 x 10(-17), and less than or equal to 4 x 10(-18) cm(3) molecule(-1) at 230, 250, and 298 K, respectively. The enthalpy for the reaction forming the complex was determined to be -36 +/- 16 kJ mol(-1). This is in good agreement with previous estimates made from kinetic measurements and theoretical calculations. C1 Purdue Univ, Dept Chem, W Lafayette, IN 47906 USA. Purdue Univ, Dept Earth & Atmospher Sci, W Lafayette, IN 47906 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Francisco, JS (reprint author), Purdue Univ, Dept Chem, W Lafayette, IN 47906 USA. NR 17 TC 88 Z9 89 U1 4 U2 16 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 JUL 20 PY 2000 VL 104 IS 28 BP 6597 EP 6601 DI 10.1021/jp0006330 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 337NM UT WOS:000088368200011 ER PT J AU Nuth, JA Hill, HGM Kletetschka, G AF Nuth, JA Hill, HGM Kletetschka, G TI Determining the ages of comets from the fraction of crystalline dust SO NATURE LA English DT Article ID SOLAR NEBULA; SILICATE GRAINS; BETA-PICTORIS; DISK AB The timescale for the accretion of bodies in the disk surrounding a young star depends upon a number of assumptions, but there are few observational constraints. In our own Solar System, measurements of meteoritic components can provide information about the inner regions of the nebula, but not the outer parts. Observations of the evolution of more massive protostellar systems (Herbig A(e)/B(e) stars) imply that significant changes occur in the physical properties of their dust with time(1). The simplest explanation is that thermal annealing of the original, amorphous grains in the hot inner nebula slowly increases the fractional abundance of crystalline material over time. Crystalline dust is then transported outward, where it is incorporated into comets that serve as a longterm reservoir for dust disks, such as that surrounding Beta Pictoris. Here we show that when applied to our own Solar System, this process can explain observed variations in both the volatile and dusty components of comets, while also providing a natural indicator of a comet's mean formation age. Studies of comets with different dust contents can therefore be used to investigate the timescales of the early Solar System. C1 NASA, Goddard Space Flight Ctr, Astrochem Branch, Greenbelt, MD 20771 USA. RP Nuth, JA (reprint author), NASA, Goddard Space Flight Ctr, Astrochem Branch, Code 691, Greenbelt, MD 20771 USA. EM uljan@lepvax.gsfc.nasa.gov RI Kletetschka, Gunther/C-9996-2011; Nuth, Joseph/E-7085-2012 OI Kletetschka, Gunther/0000-0002-0645-9037; NR 21 TC 65 Z9 65 U1 0 U2 7 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JUL 20 PY 2000 VL 406 IS 6793 BP 275 EP 276 DI 10.1038/35018516 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 335PM UT WOS:000088251900040 PM 10917522 ER PT J AU Brinksma, EJ Bergwerff, JB Bodeker, GE Boersma, KF Boyd, IS Connor, BJ de Haan, JF Hogervorst, T Hovenier, JW Parrish, A Tsou, JJ Zawodny, JM Swart, DPJ AF Brinksma, EJ Bergwerff, JB Bodeker, GE Boersma, KF Boyd, IS Connor, BJ de Haan, JF Hogervorst, T Hovenier, JW Parrish, A Tsou, JJ Zawodny, JM Swart, DPJ TI Validation of 3 years of ozone measurements over network for the detection of stratospheric change station Lauder, New Zealand SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DIFFERENTIAL ABSORPTION LIDAR; RAYLEIGH-SCATTERING; PROFILER ASSESSMENT; ATMOSPHERE; OPAL AB A large number of ozone profiles measured by using various methods (lidar, ozonesondes, microwave radiometer, and Stratospheric Aerosol and Gas Experiment II) over Lauder, New Zealand, between late 1994 and early 1998 are intercompared. These profiles are also used to validate a collocated Dobson spectrophotometer. Between March 1996 (August 1996 for sonde measurements) and January 1998, all instruments were operational and no instrument changes took place. The ozone number densities averaged over this period agreed within 5% in the 20- to 35-km range. Between 12 and 20 km, lidar and sonde results deviated by less than 8%, and lidar and SAGE II results deviated by less than 15%, The ozone column densities measured by the Dobson spectrophotometer agreed within 3% with the integrated ozone profiles. The various methods are discussed, and modifications are proposed. They comprise a decrease of the reported sonde altitudes of about 125 m (+/-50 m) to correct for the response time of the sonde's chemical solution, the use of more accurate molecular parameter values in the lidar algorithm, and a 2.5% decrease in SAGE II ozone densities. Improved agreement between the average ozone profiles to within 1.5% for lidar and sondes (20-35 km) and within 2.5% for lidar and SAGE II (20-35 km) is achieved. The Dobson results are found to be influenced by the annual cycle of the temperature profile through the altitude-averaged ozone absorption cross section, which has been assumed to be constant in the presented data but actually varies with an amplitude of 2% over Lauder. C1 Natl Inst Publ Hlth & Environm, Air Res Lab, NL-3720 BA Bilthoven, Netherlands. Natl Inst Water & Atmospher Res Ltd, Lauder, New Zealand. Free Univ Amsterdam, Div Phys & Astron, Fac Sci, NL-1081 HV Amsterdam, Netherlands. Univ Massachusetts, Dept Phys & Astron, Amherst, MA 01003 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Sci Applicat Int Corp, Hampton, VA USA. Univ Amsterdam, Astron Inst Anton Pannekoek, Amsterdam, Netherlands. RP Brinksma, EJ (reprint author), KNMI, Climate Res & Seismol Dept, Atmospher Compos Res Div, POB 201, NL-3730 AE De Bilt, Netherlands. EM brinksma@knmi.nl; hans.bergwerff@rivm.nl; g.bodeker@niwa.cri.nz; folkert.boersma@knmi.nl; i.boyd@uiwa.cri.nz; b.connor@niwa.cri.nz; johan@nat.vu.nl; wh@nat.vu.nl; hovenier@nat.vu.nl; parrish@fcrao1.phast.umass.edu; j.j.tsou@larc.nasa.gov; j.m.zawodny@larc.nasa.gov; daan.swart@rivm.nl RI Bodeker, Greg/A-8870-2008 OI Bodeker, Greg/0000-0003-1094-5852 NR 26 TC 16 Z9 16 U1 2 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUL 16 PY 2000 VL 105 IS D13 BP 17291 EP 17306 DI 10.1029/2000JD900143 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 335GU UT WOS:000088236400006 ER PT J AU Aires, F Chedin, A Nadal, JP AF Aires, F Chedin, A Nadal, JP TI Independent component analysis of multivariate time series: Application to the tropical SST variability SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SEA-SURFACE TEMPERATURE; LOW-FREQUENCY OSCILLATIONS; SINGULAR-SPECTRUM ANALYSIS; NORTHERN-HEMISPHERE; PRINCIPAL COMPONENTS; BLIND SEPARATION; EL-NINO; INTERANNUAL VARIABILITY; SOUTHERN OSCILLATION; ENSO AB With the aim of identifying the physical causes of variability of a given dynamical system, the geophysical community has made an extensive use of classical component extraction techniques such as principal component analysis (PCA) or rotational techniques (RT). We introduce a recently developed algorithm based on information theory: independent component analysis (ICA). This new technique presents two major advantages over classical methods. First, it aims at extracting statistically independent components where classical techniques search for decorrelated components (i.e., a weaker constraint). Second, the linear hypothesis for the mixture of components is not required. In this paper, after having briefly summarized the essentials of classical techniques, we present the new method in the context of geophysical time series analysis. We then illustrate the ICA algorithm by applying it to the study of the variability of the tropical sea surface temperature (SST), with a particular emphasis on the analysis of the links between El Nino Southern Oscillation (ENSO) and Atlantic SST variability. The new algorithm appears to be particularly efficient in describing the complexity of the phenomena and their various sources of variability in space and time. C1 Ecole Polytech, CNRS, Meteorol Dynam Lab, F-91128 Palaiseau, France. Ecole Normale Super, CNRS, Lab Phys Stat, F-75231 Paris 05, France. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Aires, F (reprint author), Columbia Univ, NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM filipe@sharki.giss.nasa.gov NR 58 TC 31 Z9 33 U1 0 U2 4 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 JUL 16 PY 2000 VL 105 IS D13 BP 17437 EP 17455 DI 10.1029/2000JD900152 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 335GU UT WOS:000088236400015 ER PT J AU Mlynczak, MG Garcia, RR Roble, RG Hagan, M AF Mlynczak, MG Garcia, RR Roble, RG Hagan, M TI Solar energy deposition rates in the mesosphere derived from airglow measurements: Implications for the ozone model deficit problem SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID THERMOSPHERE MODEL; MOLECULAR-OXYGEN; MIDDLE; TIDES; RADIATION; EMISSIONS; EXPLORER; SME AB We derive rates of energy deposition in the mesosphere due to the absorption of solar ultraviolet radiation by ozone. The rates are derived directly from measurements of the 1.27-mu m oxygen dayglow emission, independent of knowledge of the ozone abundance, the ozone absorption cross sections, and the ultraviolet solar irradiance in the ozone Hartley band. Fifty-six months of airglow data taken between 1982 and 1986 by the near-infrared spectrometer on the Solar-Mesosphere Explorer satellite are analyzed. The energy deposition rates exhibit altitude-dependent annual and semi-annual variations. We also find a positive correlation between temperatures and energy deposition rates near 90 km at low latitudes. This correlation is largely due to the semiannual oscillation in temperature and ozone and is consistent with model calculations. There is also a suggestion of possible tidal enhancement of this correlation based on recent theoretical and observational analyses. The airglow-derived rates of energy deposition are then compared with those computed by multidimensional numerical models. The observed and modeled deposition rates typically agree to within 20%. This agreement in energy deposition rates implies the same agreement exists between measured and modeled ozone volume mixing ratios in the mesosphere. Only in the upper mesosphere at midlatitudes during winter do we derive energy deposition rates (and hence ozone mixing ratios) consistently and significantly larger than the model calculations. This result is contrary to previous studies that have shown a large model deficit in the ozone abundance throughout the mesosphere. The climatology of solar energy deposition and heating presented in this paper is available to the community at the Middle Atmosphere Energy Budget Project web site at http://heat-budget.gats-inc.com. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Natl Ctr Atmospher Res, Div Atmospher Chem, Boulder, CO 80303 USA. Natl Ctr Atmospher Res, High Altitude Observ, Boulder, CO 80303 USA. RP Mlynczak, MG (reprint author), NASA, Langley Res Ctr, Mail Stop 420,21 Langley Blvd, Hampton, VA 23681 USA. EM m.g.mlynczak@larc.nasa.gov RI Hagan, Maura/C-7200-2008; Mlynczak, Martin/K-3396-2012 OI Hagan, Maura/0000-0002-8866-7429; NR 27 TC 10 Z9 10 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUL 16 PY 2000 VL 105 IS D13 BP 17527 EP 17538 DI 10.1029/2000JD900222 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 335GU UT WOS:000088236400020 ER PT J AU Gobron, N Pinty, B Verstraete, MM Martonchik, JV Knyazikhin, Y Diner, DJ AF Gobron, N Pinty, B Verstraete, MM Martonchik, JV Knyazikhin, Y Diner, DJ TI Potential of multiangular spectral measurements to characterize land surfaces: Conceptual approach and exploratory application SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LEAF-AREA INDEX; CANOPY REFLECTANCE; VEGETATION CANOPIES; GLOBAL-VEGETATION; PLANT CANOPIES; SOLAR SPECTRUM; SATELLITE DATA; MODEL; SCATTERING; SOIL AB New sensors exhibiting advanced technical specifications motivate the development of improved algorithms to take advantage of the enhanced performances of these sensors. In the particular case of the Multiangle Imaging Spectroradiometer (MISR) instrument, the angular sampling of the scattered radiance field, coupled with high spatial resolution and accurate radiometric calibration, justifies the implementation of physically based algorithms to optimally interpret the data and extract high-level information. This paper proposes a new approach to the reliable and accurate characterization of vegetated areas on the basis of data gathered in space and to the delivery of improved products to meet increasingly demanding user requests. An exploratory study based on advanced very high-resolution radiometer (AVHRR) data shows the potential of approaches based on advanced models but also points out the limitations associated with the use of data from monodirectional instruments. By contrast, a preliminary investigation conducted with synthetic MISR-like multiangular data illustrates the potential of analyzing data of high radiometric quality with advanced models to move toward a more complete characterization of terrestrial surfaces. C1 Commiss European Communities, Joint Res Ctr, Space Applicat Inst, I-21020 Ispra, VA, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Boston Univ, Dept Geog, Boston, MA 02215 USA. RP Gobron, N (reprint author), Commiss European Communities, Joint Res Ctr, Space Applicat Inst, TP 440, I-21020 Ispra, VA, Italy. EM nadine.gobron@jrc.it OI Verstraete, Michel/0000-0003-0968-8721 NR 48 TC 31 Z9 31 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUL 16 PY 2000 VL 105 IS D13 BP 17539 EP 17549 DI 10.1029/2000JD900154 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 335GU UT WOS:000088236400021 ER PT J AU Fujiwara, S Nishimura, T Murakami, M Nakagawa, H Tobita, M Rosen, PA AF Fujiwara, S Nishimura, T Murakami, M Nakagawa, H Tobita, M Rosen, PA TI 2.5-D surface deformation of M6.1 earthquake near Mt Iwate detected by SAR interferometry SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SYNTHETIC-APERTURE RADAR; NORTHRIDGE; CALIFORNIA AB The two-dimensional displacement vector field on the Earth's surface associated with a large earthquake near Iwate volcano in Japan, was mapped by combining satellite radar interferometry images from two different track directions. The displacement reveals not only large main ruptures, but details of many small faults movement of aftershocks and volcanic earthquakes. The displacements of the aftershock faults coincide with a stress held reorganized by the main earthquake that accelerated the aftershock fault movements. The displacements mimic the topography, suggesting that repeated movements of the same faults in the Quaternary have led to the presently existing topography. C1 Geog Survey Inst, Tsukuba, Ibaraki 3050811, Japan. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Fujiwara, S (reprint author), Geog Survey Inst, 1 Kitasato, Tsukuba, Ibaraki 3050811, Japan. RI Nishimura, Takuya/G-2789-2013 NR 11 TC 27 Z9 27 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 15 PY 2000 VL 27 IS 14 BP 2049 EP 2052 DI 10.1029/1999GL011291 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 337AQ UT WOS:000088335500009 ER PT J AU McKay, CP AF McKay, CP TI Thickness of tropical ice and photosynthesis on a snowball Earth SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID GLACIATION; ANTARCTICA; LAKES; LIFE AB On a completely ice-covered "snowball" Earth the thickness of ice in the tropical regions would be limited by the sunlight penetrating into the ice cover and by the latent heat flux generated by freezing at the ice bottom - the freezing rate would balance the sublimation rate from the top of the ice cover. Heat transfer models of the perennially ice-covered Antarctic dry valley lakes applied to the snowball Earth indicate that the tropical ice cover would have a thickness of 10 m or less with a corresponding transmissivity of > 0.1%. This light level is adequate for photosynthesis and could explain the survival of the eukaryotic algae. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP McKay, CP (reprint author), NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. NR 21 TC 59 Z9 60 U1 1 U2 21 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 JUL 15 PY 2000 VL 27 IS 14 BP 2153 EP 2156 DI 10.1029/2000GL008525 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 337AQ UT WOS:000088335500035 PM 11543492 ER PT J AU Le, G Chi, PJ Goedecke, W Russell, CT Szabo, A Petrinec, SM Angelopoulos, V Reeves, GD Chun, FK AF Le, G Chi, PJ Goedecke, W Russell, CT Szabo, A Petrinec, SM Angelopoulos, V Reeves, GD Chun, FK TI Magnetosphere on May 11, 1999, the day the solar wind almost disappeared: II. Magnetic pulsations in space and on the ground SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EARTHS FORESHOCK; ORIENTATION; WAVES AB Simultaneous observation's by Wind and IMP-8 in the upstream region on May 11, 1999, when the solar wind density was well below its usual values and the IMF was generally weakly northward, indicate there were upstream waves present in the foreshock, but wave power was an order of magnitude weaker than usual due to an extremely weak bow shock and tenuous solar wind plasma. Magnetic pulsations in the magnetosphere have been observed in the magnetic field data from Polar and at mid-latitude ground stations. By comparing May 11 with a control day under normal solar wind conditions and with a similar foreshock geometry, we find that the magnetosphere was much quieter than usual. The Pc 3-4 waves were nearly absent in the dayside magnetosphere both at Polar and as seen at midlatitude ground stations even through the foreshock geometry was favorable for the generation of these waves. Since the solar wind speed was not unusual on this day, these observations suggest that it is the Mach number of the solar wind flow relative to the magnetosphere that controls the amplitude of Pc 3-4 waves in the magnetosphere. C1 Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. USAF Acad, Dept Phys, Colorado Springs, CO 80840 USA. Lockheed Martin Adv Ctr, Space Phys Lab, Palo Alto, CA 94304 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Le, G (reprint author), Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. RI Le, Guan/C-9524-2012; Reeves, Geoffrey/E-8101-2011; OI Le, Guan/0000-0002-9504-5214; Reeves, Geoffrey/0000-0002-7985-8098; Russell, Christopher/0000-0003-1639-8298 NR 17 TC 12 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 JUL 15 PY 2000 VL 27 IS 14 BP 2165 EP 2168 DI 10.1029/1999GL000012 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 337AQ UT WOS:000088335500038 ER PT J AU Damayanthi, P Joshi, RP McAdoo, JA AF Damayanthi, P Joshi, RP McAdoo, JA TI Calculations of hole transport characteristics in bulk GaSb with comparisons to GaAs SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID SEMICONDUCTOR-METAL PHOTODETECTORS; NEGATIVE DIFFERENTIAL RESISTANCE; TEMPERATURE-GROWN GAAS; BEAM EPITAXIAL-GROWTH; LIQUID-PHASE EPITAXY; SB-RICH SOLUTIONS; GALLIUM ANTIMONIDE; ELECTRON-MOBILITY; INAS/GASB SUPERLATTICES; III-V AB Field dependent drift velocity results are presented for hole transport in bulk gallium antimonide material based on a Monte Carlo model which includes energy band warping. Transient drift velocities are demonstrated to be higher than for gallium arsenide. The steady-state characteristics are also shown to be superior. The material appears to have potential for high-speed photodetection. (C) 2000 American Institute of Physics. [S0021-8979(00)03914-1]. C1 Old Dominion Univ, Dept Elect & Comp Engn, Norfolk, VA 23529 USA. NASA, Langley Res Ctr, Aerosp Elect Syst Div, Electroopt Branch, Hampton, VA 23681 USA. RP Damayanthi, P (reprint author), Old Dominion Univ, Dept Elect & Comp Engn, Norfolk, VA 23529 USA. NR 56 TC 1 Z9 1 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUL 15 PY 2000 VL 88 IS 2 BP 817 EP 821 DI 10.1063/1.373742 PG 5 WC Physics, Applied SC Physics GA 329DA UT WOS:000087889800037 ER PT J AU Keller, G Rude, U Stals, L Mandl, S Rauschenbach, B AF Keller, G Rude, U Stals, L Mandl, S Rauschenbach, B TI Simulation of trench homogeneity in plasma immersion ion implantation SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID SHEATH; MODEL AB The time-dependent evolution of the potential, the electrical field, and the particle movement surrounding two-dimensional trenches during a high voltage pulse in the context of plasma immersion ion implantation is studied by a particle-in-cell simulation. The numerical procedure is based on the solution of Poisson's equation on a grid and the determination of the movement of the particles on the grid. This simulation is combined with simulation codes for the calculation of depth profiles and sputtering yields. The retained ion dose and the depth resolved concentration distribution were determined in dependence on the rise time of the pulse between 0.1 and 2 mu s, pulse durations between 1 and 10 mu s and the ion mass (m=20-131, i.e., Ne,...,Xe) for trenches with two different aspect ratios (eta=3:1 and 3:2). The results are discussed on the basis of the temporal evolution of the energy of the ions and the impact angle of the ions during the pulse. (C) 2000 American Institute of Physics. [S0021-8979(00)05314-7]. C1 Univ Augsburg, Inst Phys, D-86135 Augsburg, Germany. Univ Erlangen Nurnberg, Inst Informat, D-91058 Erlangen, Germany. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Rauschenbach, B (reprint author), Inst Oberflachemodifizierung Leipzig, D-04318 Leipzig, Germany. OI Ruede, Ulrich/0000-0001-8796-8599 NR 23 TC 22 Z9 23 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUL 15 PY 2000 VL 88 IS 2 BP 1111 EP 1117 DI 10.1063/1.373784 PG 7 WC Physics, Applied SC Physics GA 329DA UT WOS:000087889800079 ER PT J AU Lau, KM Kim, KM Yang, S AF Lau, KM Kim, KM Yang, S TI Dynamical and boundary forcing characteristics of regional components of the Asian summer monsoon SO JOURNAL OF CLIMATE LA English DT Article ID SEA-SURFACE-TEMPERATURE; INTERANNUAL VARIABILITY; BIENNIAL OSCILLATION; GLOBAL PRECIPITATION; SOUTHERN-OSCILLATION; WESTERN PACIFIC; RAINFALL; CIRCULATION; CLIMATE; CHINA AB In this paper, the authors present a description of the internal dynamics and boundary forcing characteristics of two major subcomponents of the Asian summer monsoon (ASM), that is, the South Asian monsoon (SAM) and the East-Southeast Asian monsoon (EAM). The description is based on a new monsoon-climate paradigm in which the variability of ASM is considered as the outcome of the interplay of a "fast" and an "intermediate" monsoon subsystem, under the influence of "slow" external forcings. Two sets of regional monsoon indices derived from dynamically consistent rainfall and wind data are used in this study. Results show that the internal dynamics of SAM are representative of a "classical" monsoon system in which the anomalous circulation is governed by Rossby wave dynamics, where anomalous vorticity induced by an off-equatorial heat source is balanced by the advection of planetary vorticity. On the other hand, the internal dynamics of EAM are characterized by a "bybrid" monsoon system featuring multicellular meridional circulation over the East Asian sector, extending from the deep Tropics to the midlatitudes. These meridional cells link; tropical heating to extratropical circulation systems via the East Asian jet stream and are responsible for the observed zonally oriented anomalous rainfall patterns over East and Southeast Asia and the subtropical western Pacific. In the extratropic al regions, the major upper-level vorticity balance is between the advection and generation by anomalous divergent circulation and basic-stale circulation. A consequence of the different dynamical underpinnings is that EAM is associated with stronger extratropical teleconnection patterns to regions outside ASM compared to SAM. The interannual variability of SAM is linked to basin-scale SST fluctuation with pronounced signals in the equatorial eastern Pacific. During the boreal spring, warming of the Arabian Sea and the subtropical western Pacific may lead to a strong SAM. For EAM, interannual variability is tied to SST anomalies over the East China Sea, the Sea of Japan (East Sea), and the South China Sea regions, while the linkage to equatorial basin-scale SST anomaly is weak at best. A strong EAM is foreshadowed by a large-scale SST anomaly dipole with warming (cooling) in the subtropical central (eastern) Pacific. Comparison with the P. J. Webster and S. Yang (WY) monsoon index shows that WY is not significantly correlated with either the SAM or EAM regional-scale rainfall separately. It is demonstrated that WY can be considered as a measure of the large-scale atmospheric circulation state over the Indian/Pacific Ocean basin, including the integrated heat source over the ASM region. As such, the regional monsoon indices developed in this paper and WY provide a complementary description of the broadscale and regional aspects of the ASM. C1 NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. Gen Sci Corp, SAIC, Beltsville, MD USA. RP Lau, KM (reprint author), NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Code 913, Greenbelt, MD 20771 USA. RI Yang, Song/B-4952-2009; Kim, Kyu-Myong/G-5398-2014; Lau, William /E-1510-2012 OI Lau, William /0000-0002-3587-3691 NR 39 TC 214 Z9 255 U1 0 U2 40 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 JUL 15 PY 2000 VL 13 IS 14 BP 2461 EP 2482 DI 10.1175/1520-0442(2000)013<2461:DABFCO>2.0.CO;2 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 340EW UT WOS:000088521000003 ER PT J AU Neelin, JD Jin, FF Syu, HH AF Neelin, JD Jin, FF Syu, HH TI Variations in ENSO phase locking SO JOURNAL OF CLIMATE LA English DT Article ID NINO-SOUTHERN-OSCILLATION; OCEAN-ATMOSPHERE INTERACTION; SEA-SURFACE TEMPERATURE; SELF-EXCITED OSCILLATIONS; HYBRID COUPLED MODEL; EL-NINO; TROPICAL OCEAN; SEASONAL CYCLE; UNIFIED VIEW; INTERANNUAL VARIABILITY AB A hybrid coupled model (HCM) and a simple coupled model (two variables) for the tropical Pacific ocean-atmosphere system are employed to examine the variations of ENSO phase-locking behavior. The HCM consists of an ocean general circulation model coupled to an empirical atmospheric model. While it is often stated that the warm peak phase of El Nino in observations tends to occur in a preferred season, both model simulations and analysis of observations suggest that the phase-locking behavior is more complicated. A scattered phase-locking behavior in ENSO onset and termination phases is seen in results of both models, even when model climatology is not changing during the integration and weather noise is not included. The mechanisms for this scatter appear to be robust when atmospheric stochastic forcing is included. A similar variation in phase-locking behavior is found in observations, suggesting that the observed scatter of onset and termination phases is a fundamental ENSO property. The scattered phase-locking behavior is explained as a result of a competition between the inherent ENSO frequency (giving a cycle in which warm peaks would not necessarily occur in a preferred season) and the tendency to phase-lock to a preferred season due to the nonlinear interaction between the ENSO cycle and the annual cycle. The phase-locking behavior is associated with the frequency-locking behavior but has additional aspects. For instance, the season of maximum warming can change with parameters. even when the locked ENSO frequency is unchanged. Analysis of observations motivated by the model variation in onset phases suggests defining a category for "early-onset" El Ninos. Such events appear to be more irregular than other El Ninos. C1 Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. Univ Hawaii, Sch Ocean & Earth Sci & Technol, Honolulu, HI 96822 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Univ Calif Los Angeles, Dept Atmospher Sci, 405 Hilgard Ave, Los Angeles, CA 90095 USA. EM neelin@atmos.ucla.edu RI Neelin, J. David/H-4337-2011 NR 59 TC 59 Z9 62 U1 1 U2 13 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 EI 1520-0442 J9 J CLIMATE JI J. Clim. PD JUL 15 PY 2000 VL 13 IS 14 BP 2570 EP 2590 DI 10.1175/1520-0442(2000)013<2570:VIEPL>2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 340EW UT WOS:000088521000009 ER PT J AU Polito, PS Sato, OT Liu, WT AF Polito, PS Sato, OT Liu, WT TI Characterization and validation of the heat storage variability from TOPEX/Poseidon at four oceanographic sites SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SEASONAL VARIABILITY; NORTH-ATLANTIC; ROSSBY WAVES; TOPEX ALTIMETRY; PACIFIC-OCEAN AB Oceanic heat storage and heat storage rate are correlated to the sea surface height anomaly signals from the TOPEX/Poseidon altimeter data from 1992 to 1998. The height anomaly data are decomposed through two-dimensional finite impulse response filtering. The signal components are the basin-scale (seasonal), westward propagating (Rossby waves), eastward propagating (Kelvin waves), and mesoscale eddies and a small-scale residual. The sum of these filtered components does not depart significantly from the original signal. Correlations and rms differences are calculated to compare heat storage estimates on the basis of altimeter and in situ data at four sites: Tropical Atmosphere-Ocean Array, Hawaii Ocean Time-series Program, California Cooperative Oceanic Fisheries Investigations, and hydrostation "S." The heat storage anomaly differences range from 52 to 64 x 10(7) J m(-2), and the correlations range from 0.67 to 0.88. The heat storage rate rms differences range from 97 to 228 W m(-2), and the correlations range from 0.66 to 0.82, The fraction of the variance associated with Rossby waves varies from 13% in the equatorial Pacific to 62% in the tropical North Pacific. Conversely, in the same regions the nonpropagating signal goes from 74 to 13%. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Polito, PS (reprint author), CALTECH, Jet Prop Lab, MS 300-323,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Polito, Paulo/F-3040-2013; Sato, Olga/G-3656-2013 OI Polito, Paulo/0000-0003-2217-3853; Sato, Olga/0000-0003-0751-4373 NR 35 TC 29 Z9 30 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JUL 15 PY 2000 VL 105 IS C7 BP 16911 EP 16921 DI 10.1029/1999JC000048 PG 11 WC Oceanography SC Oceanography GA 335TJ UT WOS:000088260600008 ER PT J AU Yu, LS Rienecker, MM AF Yu, LS Rienecker, MM TI Indian Ocean warming of 1997-1998 SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SEA-SURFACE TEMPERATURE; NINO SOUTHERN OSCILLATION; 1997-98 EL-NINO; GLOBAL STRUCTURE; SATELLITE DATA; ENSO SIGNAL; DYNAMICS; AUSTRALIA; EVOLUTION; RAINFALL AB The Indian Ocean underwent substantial changes in 1997-1998. The observations show not only the appearance of a dipole mode in the tropical region but also a persistent basin-scale warming. We present in this study an analysis of the basin-scale sea surface temperature (SST) variations during 1997-1998 using satellite observations, in situ temperature measurements, and National Centers for Environmental Prediction reanalyses. We find that the Indian SST anomaly peaks occurred at two periods, i.e., November-December-January coinciding with the Nino3 peak and the following April-May-June, and were phase locked to the Indian Ocean seasonal cycle. The changes of SST in the equatorial ocean were related to a coupled interaction between the atmosphere and the ocean. Oceanic upwelling in the east and downwelling in the west played a major role in giving rise to the SST anomalies associated with the dipole mode structure. The upwelling off the coast of Sumatra elevated the regional thermocline by more than 80 m in December 1997. On the other hand, the changes of SST in the southern Indian Ocean were largely induced by the changes of local latent flux. During boreal fall-winter of 1997 the southeasterly trades were displaced and abnormally prolonged in their northernmost equatorial position. This shifted the center of the trades toward the equator, weakened the winds in the central Southern Ocean, reduced the latent heat flux in the region, and subsequently induced a surface warming. The total change of the SST anomalies integrated over the two periods, July-December 1997 and January-May 1998, were explained well by the same period latent flux integral in both intensity and pattern. The cross-basin upper ocean temperature sections show that the extratropical warming was rather uniformly distributed in the upper 60 m, further supporting the role of mixed-layer processes in the warming. C1 Woods Hole Oceanog Inst, Dept Phys Oceanog, Woods Hole, MA 02543 USA. NASA, Goddard Space Flight Ctr, Oceans & Ice Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. RP Yu, LS (reprint author), Woods Hole Oceanog Inst, Dept Phys Oceanog, Woods Hole, MA 02543 USA. NR 40 TC 54 Z9 61 U1 2 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JUL 15 PY 2000 VL 105 IS C7 BP 16923 EP 16939 DI 10.1029/2000JC900068 PG 17 WC Oceanography SC Oceanography GA 335TJ UT WOS:000088260600009 ER PT J AU Chapron, B Kerbaol, V Vandemark, D Elfouhaily, T AF Chapron, B Kerbaol, V Vandemark, D Elfouhaily, T TI Importance of peakedness in sea surface slope measurements and applications SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID OCEAN; BACKSCATTERING; DISTRIBUTIONS AB We recall the simple statistical concept that non-Gaussian distribution peakedness results from the compounding of random processes. This idea is applied to observations and analysis of sea surface slopes as inferred using optical and microwave-scattering measurements. Our study emphasizes the importance of identifying and quantifying the distribution variance and kurtosis from observations. Data are shown to indicate consistently non-Gaussian peakedness, to indicate the need to report at least two parameters in an even order analysis, and to indicate near equivalence between radar and optical data. Physical interpretation for observed infrequent steep slopes is given via compounding statistical processes where normally distributed short-scale waves are modulated because of random fluctuations mainly associated with the underlying long wave field. Implications of non-Gaussian peakedness are provided for altimeter backscatter theory and for modeling wave-breaking probability. C1 IFREMER, Ctr Brest, Dept Oceanog Spatiale, Inst Francais Petr, F-29280 Plouzane, France. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Wallops Island, VA 23337 USA. RP Chapron, B (reprint author), IFREMER, Ctr Brest, Dept Oceanog Spatiale, Inst Francais Petr, BP 70, F-29280 Plouzane, France. RI Chapron, Bertrand/O-6527-2015 NR 21 TC 40 Z9 40 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JUL 15 PY 2000 VL 105 IS C7 BP 17195 EP 17202 DI 10.1029/2000JC900079 PG 8 WC Oceanography SC Oceanography GA 335TJ UT WOS:000088260600026 ER PT J AU Sprintall, J Gordon, AL Murtugudde, R Susanto, RD AF Sprintall, J Gordon, AL Murtugudde, R Susanto, RD TI A semiannual Indian Ocean forced Kelvin wave observed in the Indonesian seas in May 1997 SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID INDO-PACIFIC THROUGHFLOW; DYNAMICS; BOUNDARY; STRAIT; BASIN AB Recent observations within the Indonesian exit passages and internal seas highly resolve the arrival and passage of a semiannual Kelvin wave. In mid-May 1997, surface and subsurface currents were to the southeast at a mooring located south of Java in the South Java Current, while local wind forcing was northwestward. Subsequent northward fluctuations in the geostrophic current through Lombok Strait and in observed currents from two moorings located in Makassar Strait are commensurate with the speed and passage of a Kelvin wave through the region. The Kelvin wave was due to westerly wind forcing in the remote equatorial Indian Ocean during the semiannual April/May monsoon transition period. This was confirmed through a simple remote wind-forced analytical Kelvin wave model of velocity at the South Java Current mooring location and sea level in Lombok Strait and also in the numerical general circulation model of Murtugudde et al. [1998]. Warm temperature anomalies measured at the south Java mooring and within Makassar Strait an associated with the passage of the Kelvin wave. Salinity anomalies measured at the south Java mooring are consistent with an Indian Ocean source. The observed passage of the Kelvin wave during May 1997 unambiguously demonstrates for the first time that equatorial Indian Ocean remote wind forcing may on occasions influence the internal Indonesian seas. C1 Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA. Lamont Doherty Earth Observ, Palisades, NY 10964 USA. Univ Maryland, ESSIC, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. BPPT, Agcy Assessment & Applicat Technol, Jakarta, Indonesia. RP Sprintall, J (reprint author), Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA. RI Gordon, Arnold/H-1049-2011; OI Gordon, Arnold/0000-0001-6480-6095; SUSANTO, Raden Dwi/0000-0003-1495-5951 NR 22 TC 79 Z9 86 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JUL 15 PY 2000 VL 105 IS C7 BP 17217 EP 17230 DI 10.1029/2000JC900065 PG 14 WC Oceanography SC Oceanography GA 335TJ UT WOS:000088260600028 ER PT J AU Lobo, C Perret, N Morris, D Zou, J Cockayne, DJH Johnston, MB Gal, M Leon, R AF Lobo, C Perret, N Morris, D Zou, J Cockayne, DJH Johnston, MB Gal, M Leon, R TI Carrier capture and relaxation in Stranski-Krastanow InxGa1-xAs/GaAs(311)B quantum dots SO PHYSICAL REVIEW B LA English DT Article ID MOLECULAR-BEAM EPITAXY; SURFACE SEGREGATION; ENRICHMENT; DENSITY; GROWTH AB We have investigated the structure and optical properties of In0.6Ga0.4As/GaAs(311)B quantum dots (QD's) formed by the Stranski-Krastanow growth mode during metal-organic chemical-vapor deposition. We find that (311)B QD structures display a higher energy QD luminescence emission and a stronger wetting-layer emission than (100) QD's of similar diameter and density. Temperature-dependent photoluminescence (PL) measurements reveal shallow QD confinement energies and strong interaction between neighboring quantum dots. Longer PL rise times of the ground-state emission of (311)B QD's compared to (100) QD's are ascribed to the effect of differing numbers, energies, and level spacings of QD confined states on intersublevel relaxation mechanisms at low-carrier excitation densities. C1 Australian Natl Univ, Res Sch Phys Sci & Engn, Dept Elect Mat Engn, Canberra, ACT 0200, Australia. Univ Sherbrooke, Dept Phys, Sherbrooke, PQ J1K 2R1, Canada. Univ Sydney, Australian Key Ctr Microscopy & Microanal, Sydney, NSW 2006, Australia. Univ New S Wales, Sch Phys, Sydney, NSW 2052, Australia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lobo, C (reprint author), Australian Natl Univ, Res Sch Phys Sci & Engn, Dept Elect Mat Engn, Canberra, ACT 0200, Australia. RI Johnston, Michael/B-9813-2008; Zou, Jin/B-3183-2009; Lobo, Charlene/G-5003-2011 OI Johnston, Michael/0000-0002-0301-8033; Zou, Jin/0000-0001-9435-8043; Lobo, Charlene/0000-0002-2746-1363 NR 22 TC 17 Z9 17 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 EI 1550-235X J9 PHYS REV B JI Phys. Rev. B PD JUL 15 PY 2000 VL 62 IS 4 BP 2737 EP 2742 DI 10.1103/PhysRevB.62.2737 PG 6 WC Physics, Condensed Matter SC Physics GA 341VT UT WOS:000088612200065 ER PT J AU Kashlinsky, A Odenwald, S AF Kashlinsky, A Odenwald, S TI Looking behind the stars SO SCIENCE LA English DT Letter C1 NASA, Goddard Space Flight Ctr, Raytheon ITSS, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Kashlinsky, A (reprint author), NASA, Goddard Space Flight Ctr, Raytheon ITSS, Astron & Solar Phys Lab, Code 685, Greenbelt, MD 20771 USA. NR 8 TC 4 Z9 4 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 JUL 14 PY 2000 VL 289 IS 5477 BP 246 EP 247 DI 10.1126/science.289.5477.246 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 334DB UT WOS:000088169400021 PM 17750402 ER PT J AU Parusel, ABJ Wondimagegn, T Ghosh, A AF Parusel, ABJ Wondimagegn, T Ghosh, A TI Do nonplanar porphyrins have red-shifted electronic spectra? A DFT/SCI study and reinvestigation of a recent proposal SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID SPECTROSCOPIC PROPERTIES AB It is commonly believed that nonplanar distortions of the porphyrin skeleton bring about significant red shifts in the electronic absorption spectra. However, based on absorption spectroscopy and semiempirical AM1 studies of meso-tetrakis(perfluoroalkyl)porphyrin DiMagno and co-workers have challenged this notion. Here we present density functional theory based configuration interaction singles calculations which uphold the traditional view. Both ruffling and saddling deformations do bring about significant red shifts in the electronic spectra. Nonplanality-induced destabilization of the porphyrin HOMOs appears to be the principal cause of these red shifts. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Tromso, Fac Sci, Dept Chem, N-9037 Tromso, Norway. RP Parusel, ABJ (reprint author), NASA, Ames Res Ctr, MS 239-4, Moffett Field, CA 94035 USA. RI Ghosh, Abhik/G-8164-2016 OI Ghosh, Abhik/0000-0003-1161-6364 NR 26 TC 124 Z9 125 U1 2 U2 10 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD JUL 12 PY 2000 VL 122 IS 27 BP 6371 EP 6374 DI 10.1021/ja000757q PG 4 WC Chemistry, Multidisciplinary SC Chemistry GA 337MM UT WOS:000088365400005 ER PT J AU Fairley, BW Jones, LR Scharf, C Ebeling, H Perlman, E Horner, D Wegner, G Malkan, M AF Fairley, BW Jones, LR Scharf, C Ebeling, H Perlman, E Horner, D Wegner, G Malkan, M TI The WARPS survey - IV. The X-ray luminosity-temperature relation of high-redshift galaxy clusters SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE methods : data analysis; surveys; galaxies : clusters : general cosmology : observations; X-rays : galaxies ID FLUX-LIMITED SAMPLE; LOG-S RELATION; COOLING FLOWS; RICH CLUSTERS; ROSAT SURVEY; EVOLUTION; UNIVERSE; SPECTRUM; CATALOG AB We present a measurement of the cluster X-ray luminosity-temperature (L-T) relation out to high redshift (z similar to 0.8). Combined ROSAT PSPC spectra of 91 galaxy clusters detected in the Wide Angle ROSAT Pointed Survey (WARPS) are simultaneously fitted in redshift and luminosity bins. The resulting temperature and luminosity measurements of these bins, which occupy a region of the high-redshift L-T relation not previously sampled, are compared with existing measurements at low redshift in order to constrain the evolution of the L-T relation. We find the best fit to low-redshift (z < 0.2) cluster data, at T > 1 keV, to be L proportional to T3.15 +/- 0.06. Our data are consistent with no evolution in the normalization of the L-T relation up to z similar to 0.8. Combining our results with ASCA measurements taken from the literature, we find eta = 0.19 +/- 0.38 (for Omega(0) = 1, with 1 sigma errors) where L-Bol proportional to (1 + z)T-eta(3.15), or eta = 0.60 +/- 0.38 for Omega(0) = 0.3. This lack of evolution is considered in terms of the entropy-driven evolution of clusters. Further implications for cosmological constraints are also discussed. C1 Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, College Pk, MD 20742 USA. Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA. Univ Calif Los Angeles, Dept Astron, Los Angeles, CA 90024 USA. RP Fairley, BW (reprint author), Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. NR 53 TC 49 Z9 49 U1 1 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUL 11 PY 2000 VL 315 IS 4 BP 669 EP 678 DI 10.1046/j.1365-8711.2000.03512.x PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 331JX UT WOS:000088016600005 ER PT J AU Molnar, SM Birkinshaw, M AF Molnar, SM Birkinshaw, M TI Contributions to the power spectrum of cosmic microwave background from fluctuations caused by clusters of galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; galaxies : clusters : general; methods : numerical ID X-RAY-CLUSTERS; COSMOLOGICAL PARAMETERS; STATISTICAL PROPERTIES; PECULIAR VELOCITIES; SOURCE COUNTS; EVOLUTION; ANISOTROPIES; UNIVERSE; RADIATION; MODELS AB We estimate the contributions to the cosmic microwave background radiation (CMBR) power spectrum from the static and kinematic Sunyaev-Zeldovich (SZ) effects, and from the moving cluster of galaxies (MCG) effect. We conclude, in agreement with other studies, that at sufficiently small scales secondary fluctuations caused by clusters provide important contributions to the CMBR. At l greater than or similar to 3000, these secondary fluctuations become important relative to lensed primordial fluctuations. Gravitational lensing at small angular scales has been proposed as a way to break the "geometric degeneracy" in determining fundamental cosmological parameters. We show that this method requires the separation of the static SZ effect, but the kinematic SZ effect and the MCG effect are less important. The power spectrum of secondary fluctuations caused by clusters of galaxies, if separated from the spectrum of lensed primordial fluctuations, might provide an independent constraint on several important cosmological parameters. C1 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), Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 91 TC 47 Z9 47 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 2000 VL 537 IS 2 BP 542 EP 554 DI 10.1086/309042 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 338YP UT WOS:000088451100004 ER PT J AU Ghosh, KK Ramsey, BD Sadun, AC Soundararajaperumal, S Wang, J AF Ghosh, KK Ramsey, BD Sadun, AC Soundararajaperumal, S Wang, J TI Optical variability of BL Lacertae during the major outburst of 1997 SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL Lacertae objects : individual (BL Lacertae); galaxies : active; galaxies : nuclei ID GAMMA-RAY; INFRARED POLARIMETRY; STELLAR PHOTOMETRY; OBJECTS; BLAZARS; MICROVARIABILITY; POLARIZATION; EMISSION; QUASARS; FLARE AB We have undertaken an investigation of recent flux variability in BL Lac. We present optical observations taken over 22 nights documenting major as well. as minor outbursts. This has been combined, for purposes of multifrequency analysis, with published X-ray and gamma-ray data taken for an additional single night. On two nights in particular, including the night of the X-ray observations, a major outburst of about a full magnitude of variation was recorded All the data have been analyzed with theoretical models. Attempts were made to use synchrotron self-Compton and external Comptonization models to explain the data; however, both classes of models were found lacking. More satisfactory results were obtained using an analytical model proposed by Wang et al. that involves the evolution of synchrotron spectra in a homogeneous jet due to the injection of relativistic electrons, taking into account radiation losses during the outbursts. It is hoped that the results of this study of BL Lac, an archetype for the class of blazars in general, represent a more generic phenomenon applicable to the entire class. C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. Indian Inst Astrophys, Bangalore 560034, Karnataka, India. Univ Colorado, Dept Phys, Denver, CO 80217 USA. Chinese Acad Sci, Yunnan Observ, Beijing 100864, Peoples R China. RP Ghosh, KK (reprint author), NASA, George C Marshall Space Flight Ctr, Dept Space Sci, SD50, Huntsville, AL 35812 USA. NR 42 TC 12 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 2000 VL 537 IS 2 BP 638 EP 643 DI 10.1086/309071 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 338YP UT WOS:000088451100010 ER PT J AU Chiar, JE Tielens, AGGM Whittet, DCB Schutte, WA Boogert, ACA Lutz, D van Dishoeck, EF Bernstein, MP AF Chiar, JE Tielens, AGGM Whittet, DCB Schutte, WA Boogert, ACA Lutz, D van Dishoeck, EF Bernstein, MP TI The composition and distribution of dust along 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 HYDROGENATED AMORPHOUS-CARBON; POLYCYCLIC AROMATIC-HYDROCARBONS; DIFFUSE INTERSTELLAR-MEDIUM; DEEPLY EMBEDDED PROTOSTARS; H-II REGIONS; INFRARED-SPECTROSCOPY; MU-M; ABSORPTION FEATURES; MOLECULAR CLOUDS; SWS OBSERVATIONS AB We discuss the composition of dust and ice along the line of sight to the Galactic center (GC) based on analysis of mid-infrared spectra (2.4-13 mu m) from the Short Wavelength Spectrometer on the Infrared Space Observatory (ISO). We have analyzed dust absorption features arising in the molecular cloud material and the diffuse interstellar medium along the lines of sight toward Sgr A* and the Quintuplet sources, GCS 3 and GCS 4. It is evident from the depth of the 3.0 mu m H(2)O and the 4.27 mu m CO(2) ice features that there is more molecular cloud material along the line of sight toward Sgr AM than toward GCS 3 and GCS 4. In fact, Sgr A* has a rich infrared ice spectrum with evidence for the presence of solid CH(4), NH(3), and possibly HCOOH. Hydrocarbon dust in the diffuse interstellar medium along the line of sight to the GC is characterized by absorption features centered at 3.4, 6.85, and 7.25 mu m. Ground-based studies have identified the 3.4 mu m feature with aliphatic hydrocarbons, and ISO has given us the first meaningful observations of the corresponding modes at longer wavelengths. The integrated strengths of these three features suggest that hydrogenated amorphous carbon is their carrier. We attribute an absorption feature centered at 3.28 mu m in the GCS 3 spectrum to the C-H stretch in aromatic hydrocarbons. This feature is not detected, and its C-C stretch counterpart appears to be weaker, in the Sgr A* spectrum. A key question now is whether or not aromatics are a widespread component of the diffuse interstellar medium, analogous to aliphatic hydrocarbons. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SETI Inst, Mountain View, CA 94043 USA. Univ Groningen, Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands. Rensselaer Polytech Inst, Dept Phys Appl Phys & Astron, Troy, NY 12180 USA. Leiden Observ, NL-2300 RA Leiden, Netherlands. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. RP Chiar, JE (reprint author), NASA, Ames Res Ctr, Mail Stop 245-3, Moffett Field, CA 94035 USA. EM chiar@misty.arc.nasa.gov NR 92 TC 199 Z9 200 U1 2 U2 10 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 JUL 10 PY 2000 VL 537 IS 2 BP 749 EP 762 DI 10.1086/309047 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 338YP UT WOS:000088451100018 ER PT J AU Nayakshin, S Kazanas, D Kallman, TR AF Nayakshin, S Kazanas, D Kallman, TR TI Thermal instability and photoionized X-ray reflection in accretion disks SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; line : formation; radiation mechanisms : nonthermal radiative transfer; X-rays : general ID ACTIVE GALACTIC NUCLEI; VERTICAL STRUCTURE; SEYFERT-GALAXIES; COLD MATTER; COMPTON REFLECTION; BINARY-SYSTEM; MASS-TRANSFER; BLACK-HOLES; EMISSION; CORONAE AB We study the illumination of accretion disks in the vicinity of compact objects by an overlying X-ray source. Our approach differs from previous works of the subject in that we relax the simplifying assumption of constant gas density used in these studies; instead we determine the density from hydrostatic balance which is solved simultaneously with the ionization balance and the radiative transfer in a plane-parallel geometry. We calculate the temperature profile of the illuminated layer and the reprocessed X-ray spectra for a range of physical conditions, values of photon index Gamma for the illuminating radiation, and the incident and viewing angles. In accordance with some earlier studies, we find that the self-consistent density determination makes evident the presence of a thermal ionization instability well known in the context of quasar emission line studies. The main effect of this instability is to prevent the illuminated gas from attaining temperatures at which the gas is unstable to thermal perturbations. Thus, in sharp contrast to the constant density calculations that predict a continuous and rather smooth variation of the gas temperature in the illuminated material, we find that the temperature profile consists of several well defined thermally stable layers. Transitions between these stable layers are very sharp and can be treated as discontinuities as far as the reprocessed spectra are concerned. In particular, the uppermost layers of the X-ray illuminated gas are found to be almost completely ionized and at the local Compton temperature (similar to 10(7)-10(8) K); at larger depths, the gas temperature drops abruptly to form a thin layer with T similar to 10(6) K, while at yet larger depths it decreases sharply to the disk effective temperature. For a given X-ray spectral index, this discontinuous temperature structure is governed by just one parameter, A, which characterizes the strength of the gravitational force relative to the incident X-ray flux. We find that most of the Fe K alpha line emission and absorption edge are produced in the coolest, deepest layers, while the Fe atoms in the hottest, uppermost layers are generally almost fully ionized, hence making a negligible contribution to reprocessing features in the similar to 6.4-10 keV energy range. We also find that the Thomson depth of the top hot layers is pivotal in determining the fraction of the X-ray flux which penetrates to the deeper cooler layers, thereby affecting directly the strength of the Fe line, edge and reflection features. Due to the interplay of these effects, for Gamma less than or similar to 2, the equivalent width (EW) of the Fe features decreases monotonically with the magnitude of the illuminating flux, while the line centroid energy remains at 6.4 keV. We provide a summary of the dependence of the reprocessing features in the X-ray reflected spectra on the gravity parameter A, the spectral index Gamma, and other parameters of the problem. We emphasis that the results of our self-consistent calculations are both quantitatively and qualitatively different from those obtained using the constant density assumption. Therefore, we propose that future X-ray reflection calculations should always utilize hydrostatic balance in order to provide a reliable interpretation of X-ray spectra of active galactic nuclei and galactic black hole candidates. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Nayakshin, S (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. NR 66 TC 196 Z9 196 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 2000 VL 537 IS 2 BP 833 EP 852 DI 10.1086/309054 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 338YP UT WOS:000088451100025 ER PT J AU Sollerman, J Lundqvist, P Lindler, D Chevalier, RA Fransson, C Gull, TR Pun, CSJ Sonneborn, G AF Sollerman, J Lundqvist, P Lindler, D Chevalier, RA Fransson, C Gull, TR Pun, CSJ Sonneborn, G TI Observations of the Crab Nebula and its pulsar in the far-ultraviolet and in the optical SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; instrumentation : spectrographs pulsars : individual (Crab Pulsar); supernova remnants; ultraviolet : ISM; ultraviolet : stars ID LARGE-MAGELLANIC-CLOUD; TIME RESOLUTION; S-II; EMISSION; ABUNDANCES; TELESCOPE; FILAMENTS; SPECTRUM; GEMINGA; REMNANT AB We present far-UV observations of the Crab Nebula and its pulsar made with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. Broad, blueshifted absorption arising in the nebula is seen in C IV lambda 1550, reaching a blueward velocity of similar to 2500 km s(-1). This can be interpreted as evidence for a fast outer shell surrounding the Crab Nebula, and we adopt a spherically symmetric model to constrain the properties of such a shell. From the line profile we find that the density appears to decrease outward in the shell. A likely lower limit to the shell mass is similar to 0.3 M-circle dot with an accompanying kinetic energy of similar to 1.5 x 10(49) ergs. A fast massive shell with 10(51) ergs cannot be excluded but is less likely if the density profile is much steeper than rho(R) proportional to R-4 and the maximum velocity is less than or similar to 6000 km (-1). The observations cover the region 1140-1720 Angstrom, which is further into the ultraviolet than has previously been obtained for the pulsar. With the time-tag mode of the spectrograph we obtain the pulse profile in this spectral regime. The profile is similar to that previously obtained by us in the near-UV, although the primary peak is marginally narrower. Together with the near-UV data, and new optical data from the Nordic Optical Telescope, our spectrum of the Crab pulsar covers the entire region from 1140 to 9250 Angstrom. Dereddening the spectrum with a standard extinction curve we achieve a flat spectrum for the reddening parameters E(B - V) = 0.52, R = 3.1. This dereddened spectrum of the Crab pulsar can be fitted by a power law with spectral index alpha(nu) = 0.11 +/- 0.04. The main uncertainty in determining the spectral index is the amount and characteristics of the interstellar reddening, and we have investigated the dependence of ct, on E(B-V) and R. In the extended emission covered by our 25 " x 0 ".5 slit in the far-UV, we detect C Iv lambda 1550 and He II lambda 1640 emission lines from the Crab Nebula Several interstellar absorption lines are detected along the line of sight to the pulsar. The Ly alpha absorption indicates a column density of (3.0 +/- 0.5) x 10(21) cm(-2) of neutral hydrogen, which agrees well with our estimate of E(B - V) = 0.52 mag. Other lines show no evidence of severe depletion of metals in atomic gas. C1 Stockholm Observ, SE-13336 Saltsjobaden, Sweden. European So Observ, D-85748 Garching, Germany. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. RP Sollerman, J (reprint author), Stockholm Observ, SE-13336 Saltsjobaden, Sweden. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 49 TC 72 Z9 72 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 2000 VL 537 IS 2 BP 861 EP 874 DI 10.1086/309062 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 338YP UT WOS:000088451100027 ER PT J AU Hurley, K Kouveliotou, C Cline, T Cole, D Miller, MC Harmon, A Fishman, G Briggs, M van Paradijs, J Kommers, J Lewin, W AF Hurley, K Kouveliotou, C Cline, T Cole, D Miller, MC Harmon, A Fishman, G Briggs, M van Paradijs, J Kommers, J Lewin, W TI Precise interplanetary network localization of the bursting pulsar GRO J1744-28 SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : individual (GRO J1744-28); stars : neutron; X-rays : stars ID RAY-BURSTS; ULYSSES; BATSE AB We analyze 426 observations of the bursting pulsar GRO J1744-28 by Ulysses and BATSE. Triangulating each burst and statistically combining the triangulation annuli, we obtain a 3 sigma error ellipse whose area is 532 arcsec(2). The accuracy of this statistical method has been independently verified with observations of the soft gamma repeater SGR 1900+14. The ellipse is fully contained within the 1' radius ASCA error circle of the soft X-ray counterpart and partially overlaps the 10 " radius ROSAT error circle of a source which may also be the soft X-ray counterpart. A variable source which has been proposed as a possible IR counterpart lies at the edge of the 3 sigma error ellipse, making it unlikely from a purely statistical point of view to be associated with the bursting pulsar. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Alabama, Huntsville, AL 35899 USA. MIT, Ctr Space Res 37 627, Cambridge, MA 02139 USA. RP Hurley, K (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NR 26 TC 9 Z9 9 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 2000 VL 537 IS 2 BP 953 EP 957 DI 10.1086/309083 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 338YP UT WOS:000088451100037 ER PT J AU Hwang, U Holt, SS Petre, R AF Hwang, U Holt, SS Petre, R TI Mapping the X-ray-emitting ejecta in Cassiopeia A with Chandra SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (Cassiopeia A); supernova remnants; X-rays : general ID A SUPERNOVA REMNANT; EXPLOSIONS; SPECTROSCOPY; EMISSION; SHELL; JET AB We present X-ray emission-line equivalent width images of the bright Galactic supernova remnant Cassiopeia A for the elements Si, S, Ar, Ca, and Fe using a 50,000 s observation with the Advanced CCD Imaging Spectrometer on the Chandra X-Ray Observatory. The images essentially map the bulk of detectable ejecta of these elements over a wide range of surface brightnesses and show morphologies distinctly different from that of the broadband X-ray emission and the 4-6 keV continuum emission. The Si, S, Ar, and Ca maps, while different in turn from those of Fe, are similar to the distribution of fast optical ejecta knots in that they clearly delineate the X-ray counterpart of the northeast optical jet. Low surface brightness regions just outside the bright shell in the north and west are also shown to have strong line emission. The strong Fe emission is exterior to that of other elements in the east, as previously noted, but is generally coincident elsewhere. The projected interior has relatively little emission traced by high line equivalent widths. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Hwang, U (reprint author), Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NR 18 TC 92 Z9 92 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 2000 VL 537 IS 2 BP L119 EP L122 DI 10.1086/312776 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 338YQ UT WOS:000088451200012 ER PT J AU Ozernoy, LM Gorkavyi, NN Mather, JC Taidakova, TA AF Ozernoy, LM Gorkavyi, NN Mather, JC Taidakova, TA TI Signatures of exosolar planets in dust debris disks SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; dust, extinction; planetary systems; stars : individual (Vega, epsilon Eridani) ID RING; EARTH AB We apply our recently elaborated, powerful numerical approach to the high-resolution modeling of the structure and emission of circumstellar dust disks, incorporating all relevant physical processes. Specifically, we examine the resonant structure of a dusty disk induced by the presence of one planet. It is shown that the planet, via resonances and gravitational scattering, produces (1) an asymmetric resonant dust belt with one or more clumps, intermittent with one or a few off-center cavities, and (2) a central cavity void of dust. These features can serve as indicators of a planet embedded in the circumstellar dust disk and, moreover, can be used to determine its major orbital parameters and even the mass of the planet. The results of our study reveal a remarkable similarity with various types of highly asymmetric circumstellar disks observed with the James Clerk Maxwell Telescope around epsilon Eridani and Vega. The proposed interpretation of the clumps in those disks as being resonant patterns is testable-it predicts the asymmetric design around the star to revolve, viz., by 1.degrees 2-1.degrees 6 yr(-1) about Vega and 0.degrees 6-0.degrees 8 yr(-1) about epsilon Eri. C1 George Mason Univ, Inst Computat Sci & Informat, Fairfax, VA 22030 USA. George Mason Univ, Dept Phys & Astron, Fairfax, VA 22030 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, NRC,NAS, Greenbelt, MD 20771 USA. Computat Consulting Serv, College Pk, MD 20740 USA. RP Ozernoy, LM (reprint author), George Mason Univ, Inst Computat Sci & Informat, 5C3,4400 Univ Dr, Fairfax, VA 22030 USA. NR 14 TC 100 Z9 100 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 2000 VL 537 IS 2 BP L147 EP L151 DI 10.1086/312779 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 338YQ UT WOS:000088451200019 ER PT J AU Strohmayer, TE Ibrahim, AI AF Strohmayer, TE Ibrahim, AI TI Discovery of a 6.4 keV emission line in a burst from SGR 1900+14 SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : individual (SGR 1900+14); stars : neutron; X-rays : bursts ID MAGNETIZED NEUTRON-STARS; SOFT GAMMA-REPEATERS; X-RAY PULSARS; SPIN-DOWN; AFTERGLOWS; ACCRETION AB We present evidence of a 6.3 keV emission line during a burst from the soft gamma repeater SGR 1900+14. The Rossi X-Ray Timing Explorer (RXTE) monitored this source extensively during its outburst in the summer of 1998. A strong burst observed on 1998 August 29 revealed a number of unique properties. The burst exhibits a precursor and is followed by a long (similar to 10(3) a) tail modulated at the 5.16 s stellar rotation period. The precursor has a duration of approximate to 0.85 s and shows both significant spectral evolution as well as an emission feature centered near 6.4 keV during the first 0.3 a of the event, when the X-ray spectrum was hardest. The continuum during the burst is well fit with an optically thin thermal bremsstrahlung spectrum with the temperature ranging from approximate to 40 to 10 keV. The line is strong, with an equivalent width of similar to 400 eV, and is consistent with Fe K alpha fluorescence from relatively cool material. If the rest-frame energy is indeed 6.4 keV, then the lack of an observed redshift indicates that the source is at least similar to 80 km above the neutron star surface. We discuss the implications of the line detection in the context of models for SGRs. 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. RI Ibrahim, Alaa/A-6250-2008 OI Ibrahim, Alaa/0000-0002-8791-7270 NR 36 TC 29 Z9 29 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 2000 VL 537 IS 2 BP L111 EP L114 DI 10.1086/312769 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 338YQ UT WOS:000088451200010 ER PT J AU Dodelson, S Parker, S Thaler, J AF Dodelson, S Parker, S Thaler, J TI Cosmic microwave background: Past, future and present SO INTERNATIONAL JOURNAL OF MODERN PHYSICS A LA English DT Article; Proceedings Paper CT 19th International Symposium on Lepton and Photon Interactions CY AUG 09-14, 1999 CL STANFORD UNIV, STANFORD, CALIFORNIA SP Stanford Univ HO STANFORD UNIV ID COLD DARK-MATTER; X-RAY-CLUSTERS; COSMOLOGICAL PARAMETERS; GALAXY CLUSTERS; INFLATIONARY PERTURBATIONS; ANISOTROPY EXPERIMENTS; EIGENMODE ANALYSIS; UNIVERSE; POLARIZATION; RADIATION C1 NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Hawaii, Honolulu, HI 96822 USA. Univ Illinois, Chicago, IL 60680 USA. RP Dodelson, S (reprint author), NASA, Fermilab Astrophys Ctr, POB 500, Batavia, IL 60510 USA. NR 85 TC 4 Z9 4 U1 0 U2 0 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA JOURNAL DEPT PO BOX 128 FARRER ROAD, SINGAPORE 912805, SINGAPORE SN 0217-751X J9 INT J MOD PHYS A JI Int. J. Mod. Phys. A PD JUL 10 PY 2000 VL 15 IS 17 BP 2629 EP 2644 DI 10.1142/S0217751X00001152 PG 16 WC Physics, Nuclear; Physics, Particles & Fields SC Physics GA 342WG UT WOS:000088667900001 ER PT J AU Lulla, KP Evans, C AF Lulla, KP Evans, C TI Cover - Indonesian (Sumatra) biomass burning as seen from the Space Shuttle Atlantis SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article C1 NASA, Lyndon B Johnson Space Ctr, Off Earth Sci, Houston, TX 77058 USA. RP Lulla, KP (reprint author), NASA, Lyndon B Johnson Space Ctr, Off Earth Sci, Houston, TX 77058 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 10 PY 2000 VL 21 IS 10 BP 1969 EP 1969 DI 10.1080/01431160050021231 PG 1 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 321TJ UT WOS:000087470500001 ER PT J AU Glasser, ME Lulla, KP AF Glasser, ME Lulla, KP TI NASA astronaut photography depiction of the spatial and temporal characteristics of biomass burning SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID VEGETATION; FOREST; AMAZON AB NASA astronaut photographs of the Earth's surface, in the Space Shuttle Earth Observation Photographic database, have been examined for their ability to provide information on remote sensing of temporal and spatial distributions of biomass burning. Over 4554 photos of biomass burning are identified in a dataset containing 347 678 photos accumulated since 1961. Distributions of the entire database, and of the biomass burning photos it contains, are displayed by mission, month, year, season, latitude and hemisphere. The relative frequency of biomass burning photos was determined by removing the effects of the number of days in space and the number of photos taken. Distributions of the photos of burning are shown in relation to characteristics of global climatic and vegetation characteristics which favor biomass burning. The strengths and weaknesses of the photographic database as a tool for remote sensing of biomass burning are also discussed briefly. C1 Univ Nebraska, Dept Phys & Phys Sci, Kearney, NE 68849 USA. NASA, Lyndon B Johnson Space Ctr, Off Earth Sci, Houston, TX 77058 USA. RP Glasser, ME (reprint author), Univ Nebraska, Dept Phys & Phys Sci, Kearney, NE 68849 USA. NR 34 TC 1 Z9 1 U1 0 U2 1 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 10 PY 2000 VL 21 IS 10 BP 1971 EP 1986 DI 10.1080/01431160050021240 PG 16 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 321TJ UT WOS:000087470500002 ER PT J AU Gu, D Gillespie, AR AF Gu, D Gillespie, AR TI A new approach for temperature and emissivity separation SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article AB A Taylor expansion can be used to linearize the Planck function that governs the emission from a material at a given temperature. Such a linearization is more accurate than using Wien's approximation. This approach can be used to improve the accuracy of those logarithms that currently utilize Wien's approximation, such as the alpha residual and alpha emissivity techniques. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Washington, Dept Geol Sci, Seattle, WA 98195 USA. RP Gu, D (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 183-501, Pasadena, CA 91109 USA. NR 4 TC 9 Z9 11 U1 1 U2 3 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 10 PY 2000 VL 21 IS 10 BP 2127 EP 2132 PG 6 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 321TJ UT WOS:000087470500013 ER PT J AU Guarini, SE Moser, RD Shariff, K Wray, A AF Guarini, SE Moser, RD Shariff, K Wray, A TI Direct numerical simulation of a supersonic turbulent boundary layer at Mach 2.5 SO JOURNAL OF FLUID MECHANICS LA English DT Article ID REYNOLDS-NUMBER; CHANNEL FLOW; COMPRESSIBILITY; VELOCITY AB A direct numerical simulation of a supersonic turbulent boundary layer has been performed. We take advantage of a technique developed by Spalart for incompressible flow. In this technique, it is assumed that the boundary layer grows so slowly in the streamwise direction that the turbulence can be treated as approximately homogeneous in this direction. The slow growth is accounted for by a coordinate transformation and a multiple-scale analysis. The result is a modified system of equations, in which the flow is homogeneous in both the streamwise and spanwise directions, and which represents the state of the boundary layer at a given streamwise location. The equations are solved using a mixed Fourier and B-spline Galerkin method. Results are presented for a case having an adiabatic wall, a Mach number of M = 2.5, and a Reynolds number, based on momentum integral thickness and wall viscosity, of Re-theta = 849. The Reynolds number based on momentum integral thickness and free-stream viscosity is Re-theta = 1577. The results indicate that the Van Driest transformed velocity satisfies the incompressible scalings and a small logarithmic region is obtained. Both turbulence intensities and the Reynolds shear stress compare well with the incompressible simulations of Spalart when scaled by mean density. Pressure fluctuations are higher than in incompressible flow. Morkovin's prediction that streamwise velocity and temperature fluctuations should be anti-correlated, which happens to be supported by compressible experiments, does not hold in the simulation. Instead, a relationship is found between the rates of turbulent heat and momentum transfer. The turbulent kinetic energy budget is computed and compared with the budgets from Spalart's incompressible simulations. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Illinois, Dept Theoret & Appl Mech, Urbana, IL 61801 USA. RP Guarini, SE (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. OI Shariff, Karim/0000-0002-7256-2497 NR 49 TC 97 Z9 106 U1 0 U2 13 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JUL 10 PY 2000 VL 414 BP 1 EP 33 DI 10.1017/S0022112000008466 PG 33 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 343ZL UT WOS:000088733100001 ER PT J AU Fischer, DG AF Fischer, DG TI The information content of weakly scattered fields: implications for near-field imaging of three-dimensional structures SO JOURNAL OF MODERN OPTICS LA English DT Article ID OPTICAL MICROSCOPY; DIFFRACTION; LIMIT AB The structural information carried by the homogeneous and evanescent components of the scattered field is investigated for the case of a single plane wave, either homogeneous or evanescent, incident on a weakly scattering three-dimensional medium. For homogeneous plane wave incidence, it is shown that, unlike the one-to-one mapping that exists in the case of scattering from thin (i.e. two-dimensional) structures, the evanescent components of the scattered field are related to the three-dimensional Fourier transform of the dielectric susceptibility through a generalized Radon transform. For evanescent plane wave incidence, a reciprocal relationship exists between the homogenous components of the scattered field and the three-dimensional Fourier transform of the susceptibility. Inversion techniques are outlined for these two cases, as well as other experimental modalities, which explicitly require, except for separable media, complete (i.e, multiple view) measurement data. These results have direct bearing on total internal reflection microscopy (TIRM), and they yield insight into the limitations of more general near-field imaging techniques. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Fischer, DG (reprint author), NASA, Glenn Res Ctr, MS 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 24 TC 12 Z9 12 U1 0 U2 2 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0950-0340 J9 J MOD OPTIC JI J. Mod. Opt. PD JUL 10 PY 2000 VL 47 IS 8 BP 1359 EP 1374 DI 10.1080/095003400402968 PG 16 WC Optics SC Optics GA 326UE UT WOS:000087754600005 ER PT J AU Yau, ST Thomas, BR Vekilov, PG AF Yau, ST Thomas, BR Vekilov, PG TI Molecular mechanisms of crystallization and defect formation SO PHYSICAL REVIEW LETTERS LA English DT Article ID EQUILIBRIUM STEP DYNAMICS; ATOMIC-FORCE MICROSCOPY; SURFACE-MORPHOLOGY; VICINAL SURFACES; HUMAN-H; RESOLUTION; AU(110) AB Using the atomic force microscope (AFM) in situ during the crystallization of the protein apoferritin, we show that for this system the kink density along the steps is an equilibrium property that, multiplied by the frequency of molecular attachment, fully determines the propagation of growth steps. The intermolecular bond energy is 3.2 k(B)T. Point defects are nonequilibrial and are caused by incorporation of impurity molecules, and replicate in subsequent layers due to the strain they cause. Using single-molecule manipulation with the AFM tip, the defects can be healed to restore the regular lattice. C1 Univ Alabama, Ctr Micrograv & Mat Res, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, AMMSA, Huntsville, AL 35812 USA. Univ Alabama, Dept Chem, Huntsville, AL 35899 USA. RP Vekilov, PG (reprint author), Univ Alabama, Ctr Micrograv & Mat Res, Huntsville, AL 35899 USA. NR 35 TC 74 Z9 76 U1 1 U2 14 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD JUL 10 PY 2000 VL 85 IS 2 BP 353 EP 356 DI 10.1103/PhysRevLett.85.353 PG 4 WC Physics, Multidisciplinary SC Physics GA 331ZN UT WOS:000088048700032 ER PT J AU Garces, JE Mosca, HO Bozzolo, GH AF Garces, JE Mosca, HO Bozzolo, GH TI Atomistic modeling of Pd/Cu(100) surface alloy formation SO SURFACE SCIENCE LA English DT Article DE adatoms; alloys; compound formation; computer simulations; copper; low index single crystal surfaces; palladium; semi-empirical models and model calculations; single crystal surfaces; surface defects; surface structure, morphology, roughness, and topography ID ULTRATHIN PD FILMS; CU(100)-C(2X2)-PD SURFACE; DEFECT STRUCTURE; CU(100); GROWTH; CU(001); CU(001)C(2X2)-PD; CHEMISORPTION; AU AB A straightforward modeling approach, using the Bozzolo-Ferrante-Smith (BFS) method for alloys, is introduced and applied to the formation process of Pd/Cu(100) surface alloys. Ranging from the deposition of one single Pd atom to the formation of a c(2 x 2) structure, the proposed methodology helps explain all the experimentally observed features for coverages of up to 0.5 ML. In excellent agreement with all the known experimental facts, the approach sheds light onto the exchange mechanism between adatoms and substrate atoms, interdiffusion to subsurface layers, the formation of ordered structures and Cu islands and the c(2 x 2) structure at 0.5 ML Pd coverage. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Ohio Aerosp Inst, Cleveland, OH 44142 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Comis Nacl Energia Atom, Ctr Atom Bariloche, RA-8400 Bariloche, Rio Negro, Argentina. Comis Nacl Energia Atom, RA-1429 Buenos Aires, DF, Argentina. Univ Buenos Aires, Fac Ciencias Exactas & Nat, Dept Fis, RA-1428 Buenos Aires, DF, Argentina. RP Bozzolo, GH (reprint author), Ohio Aerosp Inst, 22800 Cedar Point Rd, Cleveland, OH 44142 USA. NR 29 TC 15 Z9 16 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 JUL 10 PY 2000 VL 459 IS 3 BP 365 EP 389 DI 10.1016/S0039-6028(00)00473-8 PG 25 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA 334JU UT WOS:000088184000016 ER PT J AU Yang, L Han, J AF Yang, L Han, J TI Electronic structure of deformed carbon nanotubes SO PHYSICAL REVIEW LETTERS LA English DT Article ID DENSITY-OF-STATES; SINGLE-WALL; CONTACT RESISTANCE; DIAMETER AB Electronic structure of deformed carbon nanotubes varies widely depending on their chirality and deformation mode. We present a framework to analyze these variations by quantifying the dispersion relation and density of states. The theory is based on the Huckel tight-binding model and confirmed by tour orbital tight-binding simulations of nanotubes under stretching, compression, torsion, and bending. it unriddles and unifies previous band gap studies and predicts the shifting, merging, and splitting of Van Hove singularities in the density of state, and the zigzag pattern of band gap change with strains. Possible applications to nanotube devices and spectroscopy research are also presented. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Yang, L (reprint author), NASA, Ames Res Ctr, MS 230-3, Moffett Field, CA 94035 USA. NR 23 TC 455 Z9 460 U1 11 U2 61 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD JUL 3 PY 2000 VL 85 IS 1 BP 154 EP 157 DI 10.1103/PhysRevLett.85.154 PG 4 WC Physics, Multidisciplinary SC Physics GA 330JR UT WOS:000087959400039 ER PT J AU Edgerton, VR Roy, RR Hodgson, JA Day, MK Weiss, J Harkema, SJ Dobkin, B Garfinkel, A Konigsberg, E Koslovskaya, I AF Edgerton, VR Roy, RR Hodgson, JA Day, MK Weiss, J Harkema, SJ Dobkin, B Garfinkel, A Konigsberg, E Koslovskaya, I TI How the science and engineering of spaceflight contribute to understanding the plasticity of spinal cord injury SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 48th International Astronautical Congress CY OCT 06-10, 1997 CL TURIN, ITALY ID NON-WEIGHT-BEARING; BIOASSAYABLE GROWTH-HORMONE; MEDIAL GASTROCNEMIUS FIBERS; SINGLE MUSCLE-FIBERS; SUCCINATE-DEHYDROGENASE ACTIVITY; HEAVY-CHAIN ISOFORMS; SKELETAL-MUSCLE; RAT SOLEUS; MYONUCLEAR NUMBER; CAT SOLEUS AB Space programs support experimental investigations related to the unique environment of space and to the technological developments from many disciplines of both science and engineering that contribute to space studies. Furthermore, interactions between scientists, engineers and administrators, that are necessary for the success of any science mission in space, promote interdiscipline communication, understanding and interests which extend well beyond a specific mission. NASA-catalyzed collaborations have benefited the spinal cord rehabilitation program at UCLA in fundamental science and in the application of expertise and technologies originally developed for the space program. Examples of these benefits include: (1) better understanding of the role of load in maintaining healthy muscle and motor function, resulting in a spinal cord injury (SCI) rehabilitation program based on muscle/limb loading; (2) investigation of a potentially novel growth factor affected by spaceflight which may help regulate muscle mass; (3) development of implantable sensors, electronics and software to monitor and analyze long-term muscle activity in unrestrained subjects; (4) development of hardware to assist therapies applied to SCI patients; and (5) development of computer models to simulate stepping which will be used to investigate the effects of neurological deficits (muscle weakness or inappropriate activation) and to evaluate therapies to correct these deficiencies. (C) 1997 International Astronautical Federation. Published by Elsevier Science Ltd. All rights reserved. C1 Univ Calif Los Angeles, Brain Res Inst, Los Angeles, CA 90024 USA. Univ Calif Los Angeles, Dept Physiol Sci, Los Angeles, CA 90024 USA. Univ Calif Los Angeles, Dept Neurol, Los Angeles, CA 90024 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Konigsberg Instruments Inc, Pasadena, CA USA. Inst Biomed Problems, Moscow, Russia. RP Edgerton, VR (reprint author), Univ Calif Los Angeles, Brain Res Inst, Los Angeles, CA 90024 USA. FU NINDS NIH HHS [NS16333] NR 99 TC 4 Z9 6 U1 0 U2 4 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 JUL PY 2000 VL 47 IS 1 BP 51 EP 62 DI 10.1016/S0094-5765(00)00009-6 PG 12 WC Engineering, Aerospace SC Engineering GA 341KN UT WOS:000088589700006 PM 11543389 ER PT J AU Monell, DW Piland, WM AF Monell, DW Piland, WM TI Aerospace systems design in NASA's collaborative engineering environment SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 50th International-Astronautical-Federation Congress CY OCT 04-08, 1999 CL AMSTERDAM, NETHERLANDS SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law, Boeing, Minist Econ Affairs, NISO, Fokker Space, Alcatel, Snecma, Space News AB Past designs of complex aerospace systems involved an environment consisting of collocated design teams with project managers, technical discipline experts, and other experts (e.g., manufacturing and systems operations). These experts were generally qualified only on the basis of past design experience and typically had access to a limited set of integrated analysis tools. These environments provided less than desirable design fidelity, often led to the inability of assessing critical programmatic and technical issues (e.g., cost, risk, technical impacts), and generally derived a design that was not necessarily optimized across the entire system. The continually changing, modern aerospace industry demands systems design processes that involve the best talent available (no matter where it resides) and access to the best design and analysis tools. A solution to these demands involves a design environment referred to as collaborative engineering. The collaborative engineering environment evolving within the National Aeronautics and Space Administration (NASA) is a capability that enables the Agency's engineering infrastructure to interact and use the best state-of-the-art tools and data across organizational boundaries. Using collaborative engineering, the collocated team is replaced with an interactive team structure where the team members are geographically distributed and the best engineering talent can be applied to the design effort regardless of physical location. In addition? a more efficient, higher quality design product is delivered by bringing together the best engineering talent with more up-to-date design and analysis tools. These tools are focused on interactive, multidisciplinary design and analysis with emphasis on the complete life cycle of the system. and they include nontraditional, integrated tools for life cycle cost estimation and risk assessment. NASA has made substantial progress during the last two years in developing a collaborative engineering environment. NASA is planning to use this collaborative engineering infrastructure to provide better aerospace systems life cycle design and analysis, which includes analytical assessment of the technical and programmatic aspects of a system from "cradle to grave." This paper describes the recent NASA developments in the area of collaborative engineering, the benefits (realized and anticipated) of using the developed capability, and the long-term plans for implementing this capability across the Agency. Published by Elsevier Science Ltd. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Monell, DW (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 0 TC 6 Z9 8 U1 2 U2 8 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 JUL-NOV PY 2000 VL 47 IS 2-9 SI SI BP 255 EP 264 DI 10.1016/S0094-5765(00)00065-5 PG 10 WC Engineering, Aerospace SC Engineering GA 351NR UT WOS:000089165500021 ER PT J AU Penley, NJ Uri, J Sivils, T Bartoe, JDF AF Penley, NJ Uri, J Sivils, T Bartoe, JDF TI Integration of multiple research disciplines on the International Space Station SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 50th International-Astronautical-Federation Congress CY OCT 04-08, 1999 CL AMSTERDAM, NETHERLANDS SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law, Boeing, Minist Econ Affairs, NISO, Fokker Space, Alcatel, Snecma, Space News AB The International Space Station will provide an extremely high-quality, long-duration microgravity environment for the conduct of research. In addition, the ISS offers a platform for performing observations of Earth and Space from a high-inclination orbit, outside of the Earth's atmosphere. This unique environment and observational capability offers the opportunity for advancement in a diverse set of research fields. Many of these disciplines to not relate to one another, and present widely differing approaches to study, as well as different resource and operational requirements. Significant challenges exist to ensure the highest quality research return for each investigation. Requirements from different investigations must be identified, clarified, integrated and communicated to ISS personnel in a consistent manner. Resources such as power, crew time, etc. must be apportioned to allow the conduct of each investigation. Decisions affecting research must be made at the strategic level as well as at a very detailed execution level. The timing of the decisions can range from years before an investigation to real-time operations. The international nature of the Space Station program adds to the complexity. Each participating country must be assured that their interests are represented during the entire planning and operations process. A process for making decisions regarding research planning, operations, and real-time replanning is discussed. This process ensures adequate representation of all research investigators. It provides a means for timely decisions, and it includes a means to ensure that all ISS International Partners have their programmatic interests represented. (C) 2000 Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Penley, NJ (reprint author), NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 0 TC 1 Z9 1 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 JUL-NOV PY 2000 VL 47 IS 2-9 SI SI BP 309 EP 315 DI 10.1016/S0094-5765(00)00072-2 PG 7 WC Engineering, Aerospace SC Engineering GA 351NR UT WOS:000089165500028 PM 11708366 ER PT J AU Rush, J AF Rush, J TI Current issues in the use of the global positioning system aboard satellites SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 50th International-Astronautical-Federation Congress CY OCT 04-08, 1999 CL AMSTERDAM, NETHERLANDS SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law, Boeing, Minist Econ Affairs, NISO, Fokker Space, Alcatel, Snecma, Space News AB The Global Positioning System (GPS) was originally intended to provide precise navigation service for Earth-based users, however, the ability to use GPS aboard satellites has also been demonstrated. There is great promise in this application but before its full benefits can be fully realized there must be confidence that GPS can provide the same level of performance and reliability that current satellite tracking systems provide. This paper will overview the demonstrated utility of satellite-based GPS applications and identify the key issues that must be addressed before its use for satellite tracking can become common practice. Some of the ongoing work to address the issues will be described. In addition, how planned improvements to the GPS constellations and it augmentations could help remedy some of the issue areas will be overviewed. (C) 2000 American Institute of Aeronautics and Astronautics, Inc. published by Elsevier Science Ltd. C1 NASA, Washington, DC 20546 USA. RP Rush, J (reprint author), NASA, Washington, DC 20546 USA. NR 11 TC 4 Z9 6 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 JUL-NOV PY 2000 VL 47 IS 2-9 SI SI BP 377 EP 387 DI 10.1016/S0094-5765(00)00079-5 PG 11 WC Engineering, Aerospace SC Engineering GA 351NR UT WOS:000089165500035 ER PT J AU Erickson, JK Cox, ZN Paczkowski, BG Sible, RW Theilig, EE AF Erickson, JK Cox, ZN Paczkowski, BG Sible, RW Theilig, EE TI Project Galileo: Completing Europa, preparing for IO SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 50th International-Astronautical-Federation Congress CY OCT 04-08, 1999 CL AMSTERDAM, NETHERLANDS SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law, Boeing, Minist Econ Affairs, NISO, Fokker Space, Alcatel, Snecma, Space News AB Galileo has completed the Europa leg of the Galileo Europa Mission, and is now pumping down the apojove in each succeeding orbit in preparation for the: Io phase. Including three encounters earlier in the primary mission, the total of ten close passes by Europa have provided a wealth of interesting and provocative information about this intriguing body. The results presented include new and exciting information about Europa's interactions with Jupiter's magnetosphere, its interior structure, and its tantalizing surface features, which strongly hint at a watery subsurface layer. Additional data concerning Callisto, and its own outlook for a subsurface ocean are also presented. In addition the engineering aspects of operating the spacecraft during the past year are explored, as well as a brief examination of what will be the challenges to prepare for the Io encounters. The steadily increasing radiation dosage that the spacecraft is experiencing is well beyond the original design parameters, and is contributing to a number of spacecraft problems and concerns. The ability of the flight team to analyze and solve these problems, even at the reduced staffing levels of an extended mission, is a testament to their tenacity and loyalty to the mission. The engineering data being generated by these continuing radiation-induced anomalies will prove invaluable to designers of future spacecraft to Jupiter and its satellites. The lessons learned during this arduous process are presented. (C) 2000 International Astronautical Federation. Published by Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Erickson, JK (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 1 TC 1 Z9 1 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 JUL-NOV PY 2000 VL 47 IS 2-9 SI SI BP 419 EP 441 DI 10.1016/S0094-5765(00)00083-7 PG 23 WC Engineering, Aerospace SC Engineering GA 351NR UT WOS:000089165500039 PM 11708367 ER PT J AU O'Neil, WJ Cazaux, C AF O'Neil, WJ Cazaux, C TI The Mars Sample Return Project SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 50th International-Astronautical-Federation Congress CY OCT 04-08, 1999 CL AMSTERDAM, NETHERLANDS SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law, Boeing, Minist Econ Affairs, NISO, Fokker Space, Alcatel, Snecma, Space News AB The Mars Sample Return (MSR) Project is underway. A 2003 mission to be launched on a Delta In Class vehicle and a 2005 mission launched on an Ariane 5 will culminate in carefully selected Mars samples arriving on Earth in 2008. NASA is the lead agency and will provide the Mars landed elements, namely, landers, revers, and Mars ascent vehicles (MAVs). The French Space Agency CNES is the largest international partner and will provide for the joint NASA/CNES 2005 Mission the Ariane 5 launch and the Earth Return Mars Orbiter that will capture the sample canisters from the Mars parking orbits the MAVs place them in. The sample canisters will be returned to Earth aboard the CNES Orbiter in the Earth Entry Vehicles provided by NASA. Other national space agencies are also expected to participate in substantial roles. Italy is planning to provide a drill that will operate from the Landers to provide subsurface samples. Other experiments in addition to the MSR payload will also be carried on the Landers. This Papepwill present the current status of the design of the MSR missions and flight articles. (C) 2000 American Institute of Aeronautics and Astronautics, Inc. Published by Elsevier Science Ltd. C1 CALTECH, Jet Prop Lab, Mars Sample Return Project, Pasadena, CA 91125 USA. RP O'Neil, WJ (reprint author), CALTECH, Jet Prop Lab, Mars Sample Return Project, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 0 TC 17 Z9 17 U1 0 U2 1 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 JUL-NOV PY 2000 VL 47 IS 2-9 SI SI BP 453 EP 465 DI 10.1016/S0094-5765(00)00085-0 PG 13 WC Engineering, Aerospace SC Engineering GA 351NR UT WOS:000089165500041 PM 11708368 ER PT J AU Rayman, MD Varghese, P Lehman, DH Livesay, LL AF Rayman, MD Varghese, P Lehman, DH Livesay, LL TI Results from the Deep Space 1 technology validation mission SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 50th International-Astronautical-Federation Congress CY OCT 04-08, 1999 CL AMSTERDAM, NETHERLANDS SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law, Boeing, Minist Econ Affairs, NISO, Fokker Space, Alcatel, Snecma, Space News AB Launched on October 24, 1998, Deep Space 1 (DS1) is the first mission of NASA's New Millennium program, chartered to validate in space high-risk, new technologies important for future space and Earth science programs. The advanced technology payload that was tested on DS1 comprises solar electric propulsion, solar concentrator arrays, autonomous on-board navigation and other autonomous systems, several telecommunications and microelectronics devices, and two low-mass integrated science instrument packages. The technologies were rigorously exercised so that subsequent flight projects would not have to incur the cost and risk of being the first users of these new capabilities. The performances of the technologies are described as are the general execution of the mission and plans for future operations, including a possible extended mission that would be devoted to science. (C) 2000 Elsevier Science Ltd. AII rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Rayman, MD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 16 TC 96 Z9 102 U1 2 U2 11 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 JUL-NOV PY 2000 VL 47 IS 2-9 SI SI BP 475 EP 487 DI 10.1016/S0094-5765(00)00087-4 PG 13 WC Engineering, Aerospace SC Engineering GA 351NR UT WOS:000089165500043 ER PT J AU Huckins, EK Elachi, C Woods, DV AF Huckins, EK Elachi, C Woods, DV TI Exploring the solar system - A current overview SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 50th International-Astronautical-Federation Congress CY OCT 04-08, 1999 CL AMSTERDAM, NETHERLANDS SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law, Boeing, Minist Econ Affairs, NISO, Fokker Space, Alcatel, Snecma, Space News AB This paper examines the history of robotic exploration of the solar system from the initial flights to present day. Analysis demonstrates how flight rate and spacecraft mass have varied in the programs of the major space faring countries. The paper also demonstrates how the faster, better, cheaper approach has significantly increased scientific productivity and program resiliency to failures. (C) 2000 Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Washington, DC 20546 USA. RP Huckins, EK (reprint author), NASA, Washington, DC 20546 USA. NR 0 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 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL-NOV PY 2000 VL 47 IS 2-9 SI SI BP 523 EP 533 PG 11 WC Engineering, Aerospace SC Engineering GA 351NR UT WOS:000089165500047 ER PT J AU Ahlf, P Cantwell, E Ostrach, L Pline, A AF Ahlf, P Cantwell, E Ostrach, L Pline, A TI Mars scientific investigations as a precursor for human exploration SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 50th International-Astronautical-Federation Congress CY OCT 04-08, 1999 CL AMSTERDAM, NETHERLANDS SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law, Boeing, Minist Econ Affairs, NISO, Fokker Space, Alcatel, Snecma, Space News AB In the past two years, NASA has begun to develop and implement plans for investigations on robotic Mars missions which are focused toward returning data critical for planning human missions to Mars. The Mars Surveyor Program 2001 Orbiter and Lander missions will mark the first time that experiments dedicated to preparation for human exploration will be carried out. Investigations on these missions and future missions range from characterization of the physical and chemical environment of Mars, to predicting the response of biology to the Mars environment. Planning for such missions must take into account existing data from previous Mars missions which were not necessarily focused on human exploration preparation. At the same time, plans for near term missions by the international community must be considered to avoid duplication of effort. This paper reviews data requirements for human exploration and applicability of existing data. It will also describe current plans for investigations and place them within the context of related international activities. (C) 2000 International Astronautical Federation. Published by Elsevier Science Ltd. All rights reserved. C1 NASA Headquarters, Div Life Sci, Washington, DC 20546 USA. RP Ahlf, P (reprint author), NASA Headquarters, Div Life Sci, Washington, DC 20546 USA. RI huang, hongqi/N-1473-2014 NR 32 TC 2 Z9 2 U1 0 U2 4 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 JUL-NOV PY 2000 VL 47 IS 2-9 SI SI BP 535 EP 545 DI 10.1016/S0094-5765(00)00092-8 PG 11 WC Engineering, Aerospace SC Engineering GA 351NR UT WOS:000089165500048 PM 11708369 ER PT J AU Bartoe, JDF Fortenberry, L AF Bartoe, JDF Fortenberry, L TI One year old and growing: A status report of the international space station and its partners SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 50th International-Astronautical-Federation Congress CY OCT 04-08, 1999 CL AMSTERDAM, NETHERLANDS SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law, Boeing, Minist Econ Affairs, NISO, Fokker Space, Alcatel, Snecma, Space News AB The International Space Station (ISS), as the largest international science and engineering program in history, features unprecedented technical, cost, scheduling, managerial, and international complexity. A number of major milestones have been accomplished to date, including the construction of major elements of flight hardware, the development of operations and sustaining engineering centers, astronaut training, and eight Space Shuttle/Mir docking missions. International partner contributions and levels of participation have been baselined, and negotiations and discussions are nearing completion regarding bartering arrangements for services and new hardware. As ISS is successfully executed, it can pave the way for more inspiring cooperative achievements in the future. Published by Elsevier Science Ltd. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Bartoe, JDF (reprint author), NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 0 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 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL-NOV PY 2000 VL 47 IS 2-9 SI SI BP 589 EP 597 DI 10.1016/S0094-5765(00)00097-7 PG 9 WC Engineering, Aerospace SC Engineering GA 351NR UT WOS:000089165500053 PM 11708370 ER PT J AU Robey, JL AF Robey, JL TI NASA's international microgravity strategic planning for the space station era SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 50th International-Astronautical-Federation Congress CY OCT 04-08, 1999 CL AMSTERDAM, NETHERLANDS SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law, Boeing, Minist Econ Affairs, NISO, Fokker Space, Alcatel, Snecma, Space News AB NASA's Microgravity Research Program has joined with other International Space Station Partners to form an International Microgravity Strategic Planning Group (IMSPG). The purpose of this international planning group is to develop and update an International Strategic Plan for Microgravity Science and Applications Research. The objective of the IMSPG is to coordinate hardware construction and utilization amongst all the planning group members for the science disciplines areas of Biotechnology, Combustion Science, Fluid Physics, Fundamental Physics and Materials Science. As Space Station schedules are changed and budgets tightened, international cooperation becomes a necessity to assure the complete accommodation of the breadth of the science disciplines requiring a microgravity environment to perform their research. The IMSPG is NASA's primary forum for discussions regarding international cooperation in microgravity science. This paper will relate the developments of this group since it's inception in 1995 and describe the plans currently defined and under development. (C) 2000 American Institute of Aeronautics and Astronautics, Inc. Published by Elsevier Science Ltd. C1 NASA, Micrograv Res Div, Program Dev & Coordinat, Washington, DC 20546 USA. RP Robey, JL (reprint author), NASA, Micrograv Res Div, Program Dev & Coordinat, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 1 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 JUL-NOV PY 2000 VL 47 IS 2-9 SI SI BP 599 EP 606 DI 10.1016/S0094-5765(00)00098-9 PG 8 WC Engineering, Aerospace SC Engineering GA 351NR UT WOS:000089165500054 ER PT J AU Dumas, LN Walton, AL AF Dumas, LN Walton, AL TI Faster, better, cheaper: An institutional view SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 50th International-Astronautical-Federation Congress CY OCT 04-08, 1999 CL AMSTERDAM, NETHERLANDS SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law, Boeing, Minist Econ Affairs, NISO, Fokker Space, Alcatel, Snecma, Space News AB The focus in solar system exploration has shifted to a "faster, better, cheaper" approach featuring focused, technically sophisticated, fast track missions. To implement this approach, the Jet Propulsion Laboratory (JPL) has modified its management practices and its developmental process and tools. This paper examines the challenges, responses, and early results of this new way of doing business. The focus of this evaluation is at the institutional rather than the project level; that is, how is JPL managing a suite of many small missions rather than a few big ones? Current JPL missions are designed to fixed cost targets that are an order of magnitude lower than their predecessors. They have focused scientific objectives, are usually part of an ongoing program of related missions, and are being developed in about half the time previously allowed. They utilize new technology to reduce mass and improve performance. The Laboratory has responded to the challenges of the new approach with modern design and development practices and information technologies, which result in an interdependence and need for resource sharing at many levels project to project, organization to organization, and nation to nation. The early results are encouraging. Eight missions developed under the new paradigm have been launched from 1997 to 1999, with a wide range of destinations and objectives. The program architecture concept has proven to be a robust one. While many implementation issues still need to be resolved, progress is being made and the resilience of the underlying architecture has been validated. (C) 2000 American Institute of Aeronautics and Astronautics, Inc. Published by Elsevier Science Ltd. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Dumas, LN (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 4 TC 3 Z9 3 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL-NOV PY 2000 VL 47 IS 2-9 SI SI BP 607 EP 621 DI 10.1016/S0094-5765(00)00099-0 PG 15 WC Engineering, Aerospace SC Engineering GA 351NR UT WOS:000089165500055 ER PT J AU Boggon, TJ Helliwell, JR Judge, RA Olczak, A Siddons, DP Snell, EH Stojanoff, V AF Boggon, TJ Helliwell, JR Judge, RA Olczak, A Siddons, DP Snell, EH Stojanoff, V TI Synchrotron X-ray reciprocal-space mapping, topography and diffraction resolution studies of macromolecular crystal quality SO ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY LA English DT Article ID EGG-WHITE LYSOZYME; BRAGG REFLECTION PROFILES; CCD VIDEO OBSERVATION; TETRAGONAL LYSOZYME; PROTEIN CRYSTALLIZATION; GROWTH-KINETICS; MICROGRAVITY CRYSTALLIZATION; PERFECTION; IMPURITIES; CONVECTION AB A comprehensive study of microgravity and ground-grown chicken egg-white lysozyme crystals is presented using synchrotron X-ray reciprocal-space mapping, topography techniques and diffraction resolution. Microgravity crystals displayed reduced intrinsic mosaicities on average, but no differences in terms of strain over their ground-grown counterparts. Topographic analysis revealed that in the microgravity case the majority of the crystal was contributing to the peak of the reflection at the appropriate Bragg angle. In the ground-control case only a small volume of the crystal contributed to the intensity at the diffraction peak. The techniques prove to be highly complementary, with the reciprocal-space mapping providing a quantitative measure of the crystal mosaicity and strain (or variation in lattice spacing) and the topography providing a qualitative overall assessment of the crystal in terms of its X-ray diffraction properties. Structural data collection was also carried out at the synchrotron. C1 Brookhaven Natl Lab, NSLS, Upton, NY 11973 USA. ESRF, Grenoble, France. NASA, Struct Biol Lab, Huntsville, AL 35812 USA. Univ Manchester, Dept Chem, Manchester M13 9PL, Lancs, England. RP Siddons, DP (reprint author), Brookhaven Natl Lab, NSLS, Upton, NY 11973 USA. EM siddons@bnl.gov RI stojanoff, vivian /I-7290-2012; Helliwell, John /C-4587-2014; OI stojanoff, vivian /0000-0002-6650-512X; Helliwell, John /0000-0002-0520-7540; Olczak, Andrzej/0000-0002-5433-1767 NR 67 TC 47 Z9 47 U1 0 U2 11 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0907-4449 J9 ACTA CRYSTALLOGR D JI Acta Crystallogr. Sect. D-Biol. Crystallogr. PD JUL PY 2000 VL 56 BP 868 EP 880 DI 10.1107/S0907444900005837 PN 7 PG 13 WC Biochemical Research Methods; Biochemistry & Molecular Biology; Biophysics; Crystallography SC Biochemistry & Molecular Biology; Biophysics; Crystallography GA 327FY UT WOS:000087784500010 PM 10930833 ER PT J AU Noor, AK Doyle, RJ Venneri, SL AF Noor, AK Doyle, RJ Venneri, SL TI Autonomous, biologically inspired systems for future space missions SO ADVANCES IN ENGINEERING SOFTWARE LA English DT Article DE autonomy; biologically inspired systems; Bio-Watch; evolvable systems; robotic outposts; space platforms AB Future space missions will go beyond reconnaissance, enabling sustained in-situ scientific studies. Such missions require space platforms that operate in a closed-loop fashion in its environment. The platforms must be autonomous, evolvable, resilient and highly distributed. The present article describes these characteristics, along with the mission concepts considered by NASA that require these characteristics. Autonomy is a practical application of Al. Evolvability and highly distributed characteristics are biologically inspired. Published by Elsevier Science Ltd. C1 Univ Virginia, NASA, Langley Res Ctr, Ctr Adv Computat Technol, Hampton, VA 23681 USA. CALTECH, Jet Prop Lab, Ctr Space Miss Informat & Software Syst, Pasadena, CA 91109 USA. NASA Headquarters, Washington, DC 20546 USA. RP Noor, AK (reprint author), Univ Virginia, NASA, Langley Res Ctr, Ctr Adv Computat Technol, Mail Stop 201, Hampton, VA 23681 USA. NR 7 TC 6 Z9 6 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0965-9978 J9 ADV ENG SOFTW JI Adv. Eng. Softw. PD JUL PY 2000 VL 31 IS 7 BP 473 EP 480 DI 10.1016/S0965-9978(00)00041-7 PG 8 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Engineering, Multidisciplinary SC Computer Science; Engineering GA 324NK UT WOS:000087628100005 ER PT J AU Grugel, RN AF Grugel, RN TI A solid case for processing in microgravity SO AEROSPACE AMERICA LA English DT Article C1 NASA Marshall, Huntsville, AL 35812 USA. RP Grugel, RN (reprint author), NASA Marshall, Huntsville, AL 35812 USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD JUL PY 2000 VL 38 IS 7 BP 30 EP 32 PG 3 WC Engineering, Aerospace SC Engineering GA 331GR UT WOS:000088010400009 ER PT J AU Roth, JR Sherman, DM Wilkinson, SP AF Roth, JR Sherman, DM Wilkinson, SP TI Electrohydrodynamic flow control with a glow-discharge surface plasma SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA 36th Aerospace Sciences Meeting CY JAN 12-15, 1998 CL RENO, NEVADA SP Amer Inst Aeronaut & Astronaut AB Multiple flow diagnostics have been applied to planar panels revered by strips of glow-discharge surface plasma in atmospheric pressure air generated by the one atmosphere uniform glow discharge plasma. Direct drag measurements, smoke wire and titanium tetrachloride Row visualization, and boundary-layer velocity profiles were obtained. The plasma generated along streamwise-oriented, symmetric strip electrodes is shown to cause a large increase in drag, whereas the plasma along spanwise-oriented, asymmetric strip electrodes can generate a significant thrust. Flow visualization and mean velocity measurements show the primary cause of the phenomena to be a combination of mass transport and vortical structures induced by strong electrohydrodynamic body forces on the Row, known as paraelectric forcing. C1 Univ Tennessee, Dept Elect & Comp Engn, Knoxville, TN 37996 USA. Univ Tennessee, Plasma Sci Lab, Knoxville, TN 37996 USA. NASA, Langley Res Ctr, Fluid Phys & Control Branch, Hampton, VA 23681 USA. RP Roth, JR (reprint author), Univ Tennessee, Dept Elect & Comp Engn, Knoxville, TN 37996 USA. NR 11 TC 168 Z9 185 U1 5 U2 21 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 JUL PY 2000 VL 38 IS 7 BP 1166 EP 1172 DI 10.2514/2.1110 PG 7 WC Engineering, Aerospace SC Engineering GA 330HT UT WOS:000087957300007 ER PT J AU Hegde, U Bahadori, MY Stocker, DP AF Hegde, U Bahadori, MY Stocker, DP TI Oscillatory temperature measurements in a pulsed microgravity diffusion flame SO AIAA JOURNAL LA English DT Article ID JET; TRANSITION; BUOYANCY AB Results from an experimental study of a pulsed, laminar, propane gas-jet diffusion flame in microgravity are presented. The primary objective of the study was to investigate the interaction of the imposed vortex with the jet and flame flowfield under momentum-dominated conditions. A novel technique, which used a sinusoidally driven iris placed concentrically around the flame base, was used to provide axisymmetric, controlled, and repeatable disturbances to interact with the flame, Measurements of the oscillatory temperature were used to elucidate the evolution of the imposed vortex as it convects downstream. Regions of the flame where energy transfer between the oscillations and the mean thermal field occur and the direction of the energy transfer were identified. Differences with normal gravity behavior were noted. Finally, correlations between the temperature and dame radiation oscillations were provided. C1 Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. Sci & Technol Dev Corp, Los Angeles, CA 90049 USA. NASA, John H Glenn Res Ctr Lewis Field, Micrograv Sci Div, Cleveland, OH 44135 USA. RP Hegde, U (reprint author), Natl Ctr Micrograv Res, Mail Stop 1 10-3,2100 Brookpk Rd, Cleveland, OH 44135 USA. NR 26 TC 1 Z9 1 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 2000 VL 38 IS 7 BP 1219 EP 1229 DI 10.2514/2.1091 PG 11 WC Engineering, Aerospace SC Engineering GA 330HT UT WOS:000087957300014 ER PT J AU Borisov, A Walker, RJ AF Borisov, A Walker, RJ TI Os solubility in silicate melts: New efforts and results SO AMERICAN MINERALOGIST LA English DT Article ID PLATINUM-GROUP ELEMENTS; SIDEROPHILE ELEMENTS; CORE FORMATION; UPPER MANTLE; EARTH; PALLADIUM; ALLOYS; IRIDIUM; ORIGIN; GOLD AB New experimental results are reported on the partitioning of Os between Ni94Os6 (at) alloys and silicate melt at 1400 degrees C at one atmosphere total pressure and oxygen fugacities ranging from 10(-6) to 10(-8) atm. Specially designed experiments allowed us to avoid nugget formation, which was responsible for the anomalously high Os solubilities reported by Borisov and Palme (1998). Experimental glasses were analyzed by instrumental neutron activation analysis and by isotope dilution analysis. Results reveal a strong dependence of Os solubility only with Os contents decreasing from about 100 ppb to about 5 ppb as f(o2) decreases. The slope of log (Os solubility) vs. log f(o2) implies that Os3+ is the dominant Os valence state in silicate melts. The relative geochemical behavior of Os and Pt is also compared. Results suggest that Pt is more siderophile, and may also be more chalcophile than Os under the conditions considered. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Maryland, Dept Geol, Isotope Geochem Lab, College Pk, MD 20742 USA. RP Borisov, A (reprint author), Russian Acad Sci, Inst Geol Ore Deposits Petrog Mineral & Geochem, Staromonetnyj 35, Moscow 109017, Russia. RI Walker, Richard/K-6869-2016 OI Walker, Richard/0000-0003-0348-2407 NR 43 TC 35 Z9 35 U1 1 U2 8 PU MINERALOGICAL SOC AMER PI WASHINGTON PA 1015 EIGHTEENTH ST, NW SUITE 601, WASHINGTON, DC 20036 USA SN 0003-004X J9 AM MINERAL JI Am. Miner. PD JUL-AUG PY 2000 VL 85 IS 7-8 BP 912 EP 917 PG 6 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA 330MH UT WOS:000087965500004 ER PT J AU Ivanov, AV Zolensky, ME Saito, A Ohsumi, K Yang, SV Kononkova, NN Mikouchi, T AF Ivanov, AV Zolensky, ME Saito, A Ohsumi, K Yang, SV Kononkova, NN Mikouchi, T TI Florenskyite, FeTiP, a new phosphide from the Kaidun meteorite SO AMERICAN MINERALOGIST LA English DT Article ID DISCOVERY AB Florenskyite is a new phosphide species from the Kaidun chondritic meteorite, which fell in South Yemen in 1980. Kaidun is a unique chondritic breccia containing a huge variety of fragments of different chondritic types. Florenskyite was found as four dispersed grains with a maximum dimension of 14 mu m within a single mass of Fe-rich serpentine within one Kaidun clast. Florenskyite is associated with submicrometer-sized grains of pentlandite and small (up to 1.5 mu m in width) laths of a still uncharacterized Fe-Cr phosphide. Florenskyite is creamy white in reflected light, and its luster is metallic. The average of three electron microprobe analyses gave (wt%) Fe 40.52, Ti 30.08, Ni 5.47, Cr 0.93, V 0.91, Co 0.60, P 21.69, Si 0.59, sum 100.79, corresponding to Fe-1.01(Ti0.87Ni0.13Cr0.03V0.02Co0.01)(1.06)(P0.97Si0.03). Single-crystal structure analysis was performed on florenskyite using a Laue pattern collected from a multiple crystal by in-situ synchrotron X-ray diffraction. Florenskyite crystallizes in the space group Pnma, and has the anti-PbCl2 structure. Previously determined cell constants of synthetic material [a = 6.007(1), b = 3.607(1), c = 6.897(1) Angstrom] were used in the single-crystal data reduction. We used the POWD12 program to calculate a powder XRD pattern; the 5 most intense reflections are d = 2.301 (l = 100), 2.188 (88), 2.307 (47), 1.938 (45), and 1.801 Angstrom (45). Florenskyite is only the fourth phosphide to be described from nature. Its paragenesis may be unique, and may be due to melting of a mineral assemblage including Fe-Ni metal, schreibersite, daubreelite, osbornite, or heideite and subsequent crystallization of phosphides from the melt. C1 Russian Acad Sci, Vernadsky Inst Geochem & Analyt Chem, Moscow 117975, Russia. NASA, Earth Sci & Solar Syst Explorat Div, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Inst Mat Struct Sci, Tsukuba, Ibaraki 305, Japan. Lockheed Engn & Sci Co, Houston, TX 77258 USA. Univ Tokyo, Fac Sci, Inst Mineral, Bunkyo Ku, Tokyo 113, Japan. RP Ivanov, AV (reprint author), Russian Acad Sci, Vernadsky Inst Geochem & Analyt Chem, Moscow 117975, Russia. NR 16 TC 26 Z9 28 U1 0 U2 2 PU MINERALOGICAL SOC AMER PI WASHINGTON PA 1015 EIGHTEENTH ST, NW SUITE 601, WASHINGTON, DC 20036 USA SN 0003-004X J9 AM MINERAL JI Am. Miner. PD JUL-AUG PY 2000 VL 85 IS 7-8 BP 1082 EP 1086 PG 5 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA 330MH UT WOS:000087965500025 ER PT J AU McCormick, SM Whitson, PA Wu, KK McIntire, LV AF McCormick, SM Whitson, PA Wu, KK McIntire, LV TI Sheer stress differentially regulates PGHS-1 and PGHS-2 protein levels in human endothelial cells SO ANNALS OF BIOMEDICAL ENGINEERING LA English DT Article DE prostaglandin H synthase; gene regulation; endothelium; cyclooxygenase ID PROSTAGLANDIN-H SYNTHASE-1; NITRIC-OXIDE SYNTHASE; FLUID SHEAR-STRESS; GENE-EXPRESSION; MESSENGER-RNA; DOWN-REGULATION; SMOOTH-MUSCLE; GROWTH-FACTOR; SERUM; PROMOTER AB The secretion of prostacyclin (PGI(2)) by endothelial cells is regulated by shear stress. Prostaglandin H synthase (PGHS) is considered to be a key Limiting enzyme in the synthesis of PGI, from arachidonic acid. Endothelial cells were cultured in the presence of 4, 15, or 25 dyn/cm(2) shear stress using a parallel plate flow chamber to assess the effect of shear stress on both PGHS isoforms, PGHS-1 and PGHS-2. In cells exposed to 4, 15, or 25 dyn/cm(2) shear stress PGHS-1 and PGHS-2 protein levels initially decreased. The decrease was followed by a sustained increase for PGHS-1 but only a transient increase for PGHS-2. The duration of the PGHS-2 increase depended on the magnitude of the shear stress. The effect of altering shear stress levels on PGHS protein levels in cells preconditioned to either 4, 15, or 25 dyn/cm(2) shear stress for 48 h was also studied. Changing shear stress levels effected PGHS-2 but not PGHS-1. Increases in shear stress levels from 4 to 15 or 25 dyn/cm(2) caused a decrease in PGHS-1. In contrast, decreases in shear stress levels from 15 or 25 to 4 dyn/cm2 caused PGHS-2 to increase. There was a continual decrease in PGHS-2 when the shear stress was changed from 15 to 25 or 25 to 15 dyn/cm(2). In summary, the regulation of PGHS-2 by sheer stress is dependent upon the magnitude of the shear stress, whereas the regulation of PGHS-1 protein levels seems to be independent of the shear stress magnitude. The regulation of PGHS-1 and PGHS-2 protein levels by shear stress indicates that these proteins play an important role in the maintenance of cardiovascular homeostasis as regulators of PGI(2) production. (C) 2000 Biomedical Engineering Society. [S0090-6964(00)00707-4]. C1 Rice Univ, Dept Bioengn, Houston, TX 77251 USA. NASA, Lyndon B Johnson Space Ctr, Astronaut Off, Houston, TX 77058 USA. Univ Texas, Dept Internal Med, Div Hematol, Houston, TX USA. Univ Texas, Vasc Biol Res Ctr, Houston, TX USA. RP McIntire, LV (reprint author), Rice Univ, Dept Bioengn, POB 1892, Houston, TX 77251 USA. RI Wu, Kenneth Kun-Yu/B-1070-2010 FU NHLBI NIH HHS [R01 HL 18670, R01 HL 50675]; PHS HHS [P50 N523327] NR 29 TC 12 Z9 13 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0090-6964 J9 ANN BIOMED ENG JI Ann. Biomed. Eng. PD JUL PY 2000 VL 28 IS 7 BP 824 EP 833 DI 10.1114/1.1289472 PG 10 WC Engineering, Biomedical SC Engineering GA 357GM UT WOS:000089490200011 PM 11016419 ER PT J AU Ashen, JB Goff, LJ AF Ashen, JB Goff, LJ TI Molecular and ecological evidence for species specificity and coevolution in a group of marine algal-bacterial symbioses SO APPLIED AND ENVIRONMENTAL MICROBIOLOGY LA English DT Article ID PRIONITIS-LANCEOLATA RHODOPHYTA; ACCESSORY NIDAMENTAL GLAND; MICROBIAL DIVERSITY; AXENIC CULTURE; GALLS; IDENTIFICATION; HYBRIDIZATION; MORPHOGENESIS; CHLOROPHYCEAE; TRANSMISSION AB The phylogenetic relationships of bacterial symbionts from three gall-bearing species in the marine red algal genus Prionitis (Rhodophyta) were inferred from 16S rDNA sequence analysis and compared to host phylogeny also inferred from sequence comparisons (nuclear ribosomal internal-transcribed-spacer region). Gall formation has been described previously on two species of Prionitis, P. lanceolata (from central California) and P. decipiens (from Peru). This investigation reports gall formation on a third related host, Prionitis filiformis. Phylogenetic analyses based on sequence comparisons place the bacteria as a single lineage within the Roseobacter grouping of the or subclass of the division Proteobacteria (99.4 to 98.25% sequence identity among phylotypes). Comparison of symbiont and host molecular phylogenies confirms the presence of three gall-bearing algal lineages and is consistent with the hypothesis that these red seaweeds and their bacterial symbionts are coevolving. The species specificity of these associations was investigated in nature by whole-cell hybridization of gall bacteria and in the laboratory by using cross-inoculation trials. Whole-cell in situ hybridization confirmed that a single bacterial symbiont phylotype is present in galls on each host. In laboratory trials, bacterial symbionts were incapable of inducing galls on alternate hosts (including two non-gall-bearing species). Symbiont-host specificity in Prionitis gall formation indicates an effective ecological separation between these closely related symbiont phylotypes and provides an example of a biological context in which to consider the organismic significance of 16S rDNA sequence variation. C1 Univ Calif Santa Cruz, Dept Biol, Santa Cruz, CA 95064 USA. RP Ashen, JB (reprint author), NASA, Ames Res Ctr, Mailstop 239-11, Moffett Field, CA 94035 USA. NR 48 TC 72 Z9 76 U1 3 U2 24 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 JUL PY 2000 VL 66 IS 7 BP 3024 EP 3030 DI 10.1128/AEM.66.7.3024-3030.2000 PG 7 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA 332DE UT WOS:000088057600045 PM 10877801 ER PT J AU Fang, A Pierson, DL Mishra, SK Demain, AL AF Fang, A Pierson, DL Mishra, SK Demain, AL TI Growth of Streptomyces hygroscopicus in rotating-wall bioreactor under simulated microgravity inhibits rapamycin production SO APPLIED MICROBIOLOGY AND BIOTECHNOLOGY LA English DT Article ID ESCHERICHIA-COLI; PROLYLRAPAMYCIN; AY-22,989; ACID AB Growth of Streptomyces hygroscopicus under conditions of simulated microgravity in a rotating-wall bioreactor resulted in a pellet form of growth, lowered dry cell weight, and inhibition of rapamycin production. With the addition of Teflon beads to the bioreactor; growth became much less pelleted, dry cell weight increased but rapamycin production was still markedly inhibited. Growth under simulated microgravity favored extracellular production of rapamycin, in contrast to a greater percentage of cell-bound rapamycin observed under normal gravity conditions. C1 MIT, Dept Biol, Fermentat Microbiol Lab, Cambridge, MA 02139 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Space Res Assoc, Johnson Space Ctr, Houston, TX 77058 USA. RP Demain, AL (reprint author), MIT, Dept Biol, Fermentat Microbiol Lab, Cambridge, MA 02139 USA. NR 26 TC 24 Z9 29 U1 0 U2 4 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0175-7598 J9 APPL MICROBIOL BIOT JI Appl. Microbiol. Biotechnol. PD JUL PY 2000 VL 54 IS 1 BP 33 EP 36 PG 4 WC Biotechnology & Applied Microbiology SC Biotechnology & Applied Microbiology GA 337FB UT WOS:000088345800006 PM 10952002 ER PT J AU Howard, JM Stone, BD AF Howard, JM Stone, BD TI Imaging with three spherical mirrors SO APPLIED OPTICS LA English DT Article ID 2ND-ORDER DESIGN METHODS; ASYMMETRIC SYSTEMS; 1ST-ORDER LAYOUT; COMPUTER ALGEBRA; EIKONAL THEORY; FOUNDATIONS AB Unobstructed, plane-symmetric systems of three spherical mirrors are investigated. Twelve parameters are necessary to specify the configuration of such a system. Constraints are determined to eliminate four of these parameters as independent degrees of freedom. These constraints ensure appropriate first-order behavior and are used to aid in two example design studies-one for a class of systems with the object at infinity and another for a class of finite conjugate projection systems. For the first study, a portion of the associated merit-function space is systematically evaluated and plotted, and the results are compared with those obtained when a global optimizer is used. For the second study, a global optimizer is employed as the primary search tool. Example systems from both studies are presented. (C) 2000 Optical Society of America. OCIS codes: 080.2740, 220.2740, 080.3620, 220.3620, 230.4040. C1 Univ Rochester, Inst Opt, Rochester, NY 14627 USA. Tropel Corp, Fairport, NY 14450 USA. RP Howard, JM (reprint author), NASA, Goddard Space Flight Ctr, Opt Branch, Code 551, Greenbelt, MD 20771 USA. NR 31 TC 13 Z9 14 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD JUL 1 PY 2000 VL 39 IS 19 BP 3216 EP 3231 DI 10.1364/AO.39.003216 PG 16 WC Optics SC Optics GA 331YE UT WOS:000088045600006 PM 18349887 ER PT J AU Howard, JM Stone, BD AF Howard, JM Stone, BD TI Imaging with four spherical mirrors SO APPLIED OPTICS LA English DT Article ID POINT AB We investigate unobstructed, plane-symmetric imaging systems of four spherical mirrors. Fifteen parameters are necessary to specify the configuration of such a system. Constraints are determined that ensure that any resultant system possesses a given set of first-order properties. These constraints remove four parameters as available degrees of freedom. To illustrate the efficacy of this design approach, we present two example studies: one for a class of systems with the object at infinity and another for finite-conjugate projection systems. For each study a global optimizer is used as the primary search tool. Example systems from these studies are presented. (C) 2000 Optical Society of America. OCIS codes: 080.2740, 220.2740, 080.3620, 220.3620, 230.4040. C1 Univ Rochester, Inst Opt, Rochester, NY 14627 USA. Tropel Corp, Fairport, NY 14450 USA. RP Howard, JM (reprint author), NASA, Goddard Space Flight Ctr, Opt Branch, Code 551, Greenbelt, MD 20771 USA. NR 10 TC 19 Z9 19 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 JUL 1 PY 2000 VL 39 IS 19 BP 3232 EP 3242 DI 10.1364/AO.39.003232 PG 11 WC Optics SC Optics GA 331YE UT WOS:000088045600007 PM 18349888 ER PT J AU Webb, JR Howard, E Benitez, E Balonek, T McGrath, E Shrader, C Robson, I Jenkins, P AF Webb, JR Howard, E Benitez, E Balonek, T McGrath, E Shrader, C Robson, I Jenkins, P TI The 1997 outburst of AO 0235+164: Evidence for a microlensing event? SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : active; gravitational lensing; quasars : individual (AO 0235+164) ID BL; AO-0235+164; OBJECT; RADIO AB We present: multiwavelength observations of AO 0235+164 made during a 5 mag outburst in 1997. Detection of the outburst at the observatory of the South Eastern Association for Research in Astronomy prompted a concerted effort by several observatories to monitor the source in the R band. We present V-, R-, and I-band photometry, as well as contemporaneous 850 mu m and X-ray measurements. We also use radio measurements from the University of Michigan's World Wide Web site in our analysis. We find that the source varies nearly simultaneously over 6 decades in frequency during this outburst and examine the possibility that the outburst was a result of a microlensing event. The duration of the outburst was on the order of 800 days, and the maximum luminosity was approximately 9.86 x 10(47) ergs s(-1) (assuming no relativistic beaming). We also analyze the long-term optical light curve and find that, although there is still no evidence for periodicity, the variations are interesting: the timescales between pairs of outbursts are remarkably similar. We suggest that the multifrequency behavior of the 1997 outburst is consistent with microlensing scenarios, while observations of previous outbursts suggest they were not consistent with gravitational microlensing. C1 Florida Int Univ, Dept Phys, Miami, FL 33199 USA. Natl Autonomous Univ Mexico, Inst Astron, Mexico City 04510, DF, Mexico. Florida Int Univ, Dept Phys, Miami, FL 33199 USA. Colgate Univ, Dept Phys & Astron, Hamilton, NY 13346 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. Joint Astron Ctr, Hilo, HI 96720 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Webb, JR (reprint author), Florida Int Univ, Dept Phys, Univ Pk, Miami, FL 33199 USA. NR 22 TC 27 Z9 28 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 2000 VL 120 IS 1 BP 41 EP 46 DI 10.1086/301432 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 341HX UT WOS:000088585900003 ER PT J AU Jarrett, TH Chester, T Cutri, R Schneider, S Rosenberg, J Huchra, JP Mader, J AF Jarrett, TH Chester, T Cutri, R Schneider, S Rosenberg, J Huchra, JP Mader, J TI 2MASS extended sources in the zone of avoidance SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : general; HII regions; infrared radiation; ISM : individual (W51); surveys ID LARGE-SCALE STRUCTURES; REDSHIFT-SURVEY; MILKY-WAY; VELOCITY-FIELD; IRAS GALAXIES; H-I; UNIVERSE; COMPLEX; LINE AB A new high-resolution near-infrared mapping effort, the Two Micron All Sky Survey (2MASS), is now underway and will provide a complete census of galaxies as faint as 13.5 mag (3 mJy) at 2.2 mu m for most of the sky, and similar to 12.1 mag (10 mJy) for regions veiled by the Milky Way. This census has already discovered nearby galaxies previously hidden behind our Galaxy and will allow delineation of large-scale structures in the distribution of galaxies across the whole sky. Here we report the detection and discovery of new extended sources from this survey for fields incorporating the Galactic plane at longitudes between 40 degrees and 70 degrees. Follow-up H I 21 cm and optical spectroscopy observations provide positive confirmation for 14 of the new 2MASS galaxies. We perform an internal completeness and reliability analysis for the sample, consisting of 7000 sources in similar to 1000 deg(2) of area, including galaxies and Galactic nebulae from the W51 giant molecular cloud. The area-normalized detection rate is about one to two galaxies per deg2 brighter than 12.1 mag (10 mJy), roughly constant with Galactic latitude throughout the "Zone of Avoidance," of which 85%-95% are newly discovered sources. In conjunction with the deep H I surveys, 2MASS will greatly increase the current census of galaxies hidden behind the Milky Way. Moreover, owing to its sensitivity to elliptical and other gas-poor galaxies, 2MASS will provide a key complementary data set to that of the gas-rich-sensitive H I surveys of the Milky Way galaxy, potentially uncovering nearby galaxies critical to the local gravity and mass density fields. C1 CALTECH, Ctr Infrared Proc & Anal, Jet Prop Lab, Pasadena, CA 91125 USA. Univ Massachusetts, Astron Program, Amherst, MA 01003 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Jarrett, TH (reprint author), CALTECH, Ctr Infrared Proc & Anal, Jet Prop Lab, MS 100-22, Pasadena, CA 91125 USA. EM jarrett@ipac.caltech.edu; tchester@ipac.caltech.edu; roc@ipac.caltech.edu; schneider@phast.umass.edu; jessica@phast.umass.edu; huchra@cfa.harvard.edu; jmader@cfa.harvard.edu NR 53 TC 73 Z9 73 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 2000 VL 120 IS 1 BP 298 EP 313 DI 10.1086/301426 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 341HX UT WOS:000088585900019 ER PT J AU Ciardi, DR Woodward, CE Clemens, DP Harker, DE Rudy, RJ AF Ciardi, DR Woodward, CE Clemens, DP Harker, DE Rudy, RJ TI Morphology and energetics of the molecular gas within a core and a diffuse region in the filamentary dark cloud GF 9 SO ASTRONOMICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : individual (LDN 1082, GF 9); ISM : kinematics and dynamics; stars : formation ID DENSE CORES; STAR-FORMATION; NH3 OBSERVATIONS; CARBON-MONOXIDE; BOK GLOBULE; EXTINCTION AB We have performed a CO, (CO)-C-13, and CS survey of a dense core region (GF 9-Core) and a diffuse filamentary region (CF 9-Fila) within the dark cloud GF 9 (LDN 1082). Spectra in each line were obtained toward 120 positions within each region covering areas of 8' x 10'. GF 9-Core is associated with the Class 0 protostar IRAS PSC 20503+6006, while GF 9-Fila has no associated IRAS point sources. The median CO excitation temperature of the core region is 7.2 +/- 0.5 K; for the filament region, the median temperature is 7.8 +/- 0.5 K. The mass derived from the LTE isothermal analysis of (CO)-C-13 is 53 +/- 8 and 40 +/- 6 M. for GF 9-Core and GF 9-Fila, respectively. Using near-infrared extinction data to trace the H-2 column density, the isothermal LTE assumptions for (CO)-C-13 appear to break down at A(V) greater than or similar to 3 mag. The near-infrared extinction data are used to correct the derived (CO)-C-13 column densities, yielding mass estimates that are similar to 20% larger than the LTE-derived masses, The average H-2 volume densities for GF 9-Core and CF 9-Fila are similar to 5000 +/- 700 and similar to 1700 +/- 200 cm(-3). Each region contains a 15 +/- 3 M, centrally condensed CS core, which is approximately 3 times more dense than the ambient (CO)-C-13 regions, In CF 9-Core, the high-density gas core appears to be physically associated with the IRAS point source. Both high-density cores appear to be in virial equilibrium; however, the CS line widths in GF 9-Core are almost twice as large as those measured in GF 9-Fila. Because GF 9-Core is associated with the Class 0 protostar PSC 20503 + 6006, the CS line widths may be enhanced by outflow or infall motion. The additional nonturbulent line-broadening component caused by outflow/infall motion required to explain the line width implies a supersonic velocity of at least 0.3 km s(-1) (Mach 1.5). C1 Univ Florida, Dept Agron, Gainesville, FL 32611 USA. Univ Wyoming, Dept Geol & Geophys, Laramie, WY 82071 USA. Boston Univ, Inst Astrophys Res, Boston, MA 02215 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Aerospace Corp, Los Angeles, CA 90009 USA. RP Ciardi, DR (reprint author), Univ Florida, Dept Agron, 211 Space Sci Bldg, Gainesville, FL 32611 USA. OI Harker, David/0000-0001-6397-9082 NR 35 TC 9 Z9 9 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 2000 VL 120 IS 1 BP 393 EP 406 DI 10.1086/301436 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 341HX UT WOS:000088585900026 ER PT J AU Greene, TP Lada, CJ AF Greene, TP Lada, CJ TI High-resolution near-infrared spectra of protostars SO ASTRONOMICAL JOURNAL LA English DT Article DE infrared radiation; stars : atmospheres; stars : formation; stars : rotation; techniques : spectroscopic ID YOUNG STELLAR OBJECTS; RHO-OPHIUCHI CLOUD; MAIN-SEQUENCE STARS; SPECTROSCOPY AB We present new high-resolution (R similar or equal to 21,000) near-infrared (lambda = 2 mu m) spectroscopic observations of a sample of Class I and flat-spectrum protostellar objects in the rho Ophiuchi dark cloud. None of the five Class I spectra show CO upsilon = 0-2 absorption features, consistent with high K-band continuum veilings, 4 less than or similar to r(k) less than or similar to 20, and fast stellar rotation, assuming that the underlying protostellar photospheres are of late spectral type, as is suggested by the low luminosities of most of these objects. Two of the flat-spectrum protostellar objects also show no absorption features and are likely to be highly veiled. The remaining two flat-spectrum sources show weak, broad absorptions, which are consistent with an origin in quickly rotating (upsilon sin i approximate to 50 km s(-1)) late-type stellar photospheres, which are also strongly veiled (r(k) similar or equal to 3-4). These observations provide further evidence that: (1) Class I sources are highly veiled at near-infrared wavelengths, confirming previous findings of lower resolution spectroscopic studies, and (2) flat-spectrum protostars rotate more rapidly than classical T Tauri stars (Class II sources), supporting findings from a recent high-resolution spectroscopic study of other flat-spectrum sources in this cloud. In addition our observations are consistent with the high rotation rates derived for two of the Class I protostellar objects in our sample from observations of variable hard X-ray emission obtained with the ASCA satellite. These observations suggest that certain Class I sources can rotate even more rapidly than flat-spectrum protostars, near breakup velocity. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. RP Greene, TP (reprint author), NASA, Ames Res Ctr, MS 245-6, Moffett Field, CA 94035 USA. EM tgreene@mail.arc.nasa.gov; clada@cfa.harvard.edu NR 24 TC 24 Z9 24 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 2000 VL 120 IS 1 BP 430 EP 436 DI 10.1086/301452 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 341HX UT WOS:000088585900029 ER PT J AU Kuiper, L Hermsen, W Verbunt, F Thompson, DJ Stairs, IH Lyne, AG Strickman, MS Cusumano, G AF Kuiper, L Hermsen, W Verbunt, F Thompson, DJ Stairs, IH Lyne, AG Strickman, MS Cusumano, G TI The likely detection of pulsed high-energy gamma-ray emission from millisecond pulsar PSR J0218+4232 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : pulsars : individual : PSR J0218+4232; stars : neutron; galaxies : BL Lacertae objects : individual : 3C 66A; gamma rays : observations; X-rays : stars ID RAPIDLY SPINNING PULSARS; EGRET OBSERVATIONS; RADIATION; CRAB AB We report circumstantial evidence for the first detection of pulsed high-energy gamma-ray emission from a millisecond pulsar, PSR J0218+4232, using data collected with the Energetic Gamma Ray Experiment (EGRET) on board the Compton Gamma Ray Observatory (CGRO). The EGRET source 3EG J0222+4253 is shown to be spatially consistent with PSR J0218+3232 for the energy range 100-300 MeV. Above 1 GeV the nearby BL Lac 3C 66A is the evident counterpart, and between 300 MeV and 1 GeV both sources contribute to the gamma-ray excess. Folding the 100-1000 MeV photons with an accurate radio ephemeris of PSR J0218+4232 yields a double peaked pulse profile with a similar to 3.5 sigma modulation significance and with a peak separation of similar to 0.45 similar to the 0.1-10 keV pulse profile, A comparison in absolute phase with the 610 MHz radio profile shows alignment of the gamma-ray pulses with two of three radio pulses. The luminosity of the pulsed emission (0.1-1 GeV) amounts L-gamma = 1.64 . 10(34). (Delta Omega/1 sr) . (d/5.7 kpc)(2) erg s(-1) which is similar to 7% of the pulsar's total spin-down luminosity. The similarity of the X-ray and gamma-ray pulse profile shapes of PSR J0218+4232, and the apparent alignment of the gamma-ray pulses with two radio pulses at 610 MHz, bears resemblance to the well-known picture for the Crab pulsar. This similarity, and the fact that PSR J0218+4232 is one of three millisecond pulsars (the others are PSR B1821-24 and PSR B1937+21) which exhibit very hard, highly non-thermal, high-luminosity X-ray emission in narrow pulses led us to discuss these millisecond pulsars as a class, noting that each of these has a magnetic field strength near the light cylinder comparable to that for the Crab. None of the current models for gamma-ray emission from radio pulsars can explain the gamma-ray spectrum and luminosity of PSR J0218+4232. C1 SRON, NL-3584 CA Utrecht, Netherlands. Univ Utrecht, Astron Inst, NL-3508 TA Utrecht, Netherlands. NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Greenbelt, MD 20771 USA. Univ Manchester, Jodrell Bank, Macclesfield SK11 9DL, Cheshire, England. USN, Res Lab, Washington, DC 20375 USA. CNR, Ist Fis Cosm & Applicaz Informat, I-90146 Palermo, Italy. RP Kuiper, L (reprint author), SRON, Sorbonnelaan 2, NL-3584 CA Utrecht, Netherlands. EM L.M.Kuiper@sron.nl RI Thompson, David/D-2939-2012; OI Thompson, David/0000-0001-5217-9135; Cusumano, Giancarlo/0000-0002-8151-1990 NR 53 TC 89 Z9 91 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUL PY 2000 VL 359 IS 2 BP 615 EP 626 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 341JJ UT WOS:000088587000025 ER PT J AU Stickel, M Lemke, D Klaas, U Beichman, CA Rowan-Robinson, M Efstathiou, A Bogun, S Kessler, MF Richter, G AF Stickel, M Lemke, D Klaas, U Beichman, CA Rowan-Robinson, M Efstathiou, A Bogun, S Kessler, MF Richter, G TI The ISOPHOT 170 mu m serendipity survey I. Compact sources with galaxy associations SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE methods : data analysis; catalogs; surveys; galaxies : ISM; infrared : galaxies ID SPIRAL GALAXIES; COLD DUST; IRAS OBSERVATIONS; SKY SURVEY; EMISSION; MASSES; SAMPLE; ISO AB The first set of compact sources observed in the ISOPHOT 170 mu m Serendipity Survey is presented. From the slew data with low (I(100 mu m) less than or equal to 15 MJy/sr) cirrus background, 115 well-observed sources with a high signal-to-noise ratio in all detector pixels having a galaxy association were extracted. Of the galaxies with known optical morphologies, the vast majority are classified as spirals, barred spirals, or irregulars. The 170 mu m fluxes measured from the Serendipity slews have been put on an absolute flux level by using calibration sources observed additionally with the photometric mapping mode of ISOPHOT. For all but a few galaxies, the 170 mu m fluxes are determined for the first time, which represents a significant increase in the number of galaxies with measured Far-Infrared (FIR) fluxes beyond the IRAS 100 mu m limit. The 170 mu m fluxes cover the range 2 less than or similar to F(170 mu m) less than or similar to 100 Jy. Formulae for the integrated FIR fluxes F(40-220 mu m) and the total infrared fluxes F(1-1000 mu m) incorporating the new 170 mu m fluxes are provided. The large fraction of sources with a high F(170 mu m)/F(100 mu m) flux ratio indicates that a cold (T(Dust) less than or similar to 20 K) dust component is present in many galaxies. The detection of such a cold dust component is crucial for the determination of the total dust mass in galaxies, and, in cases with a large F(170 mu m)/F(100 mu m) flux ratio, increases the dust mass by a significant factor. The typical mass of the coldest dust component is M(Dust) = 10(7.5) (+/- 0.5) M(circle dot), a factor 2-10 larger than that derived from IRAS fluxes alone. As a consequence, the majority of the derived gas-to-dust ratios are much closer to the canonical value of approximate to 160 for the Milky Way. By relaxing the selection criteria, it is expected that the Serendipity Survey will eventually lead to a catalog of 170 mu m fluxes for 1000 galaxies. C1 Max Planck Inst Astron, D-69117 Heidelberg, Germany. CALTECH, Ctr Infrared Proc & Anal, JPL, Pasadena, CA 91125 USA. Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2BZ, England. ESO, Data Management & Operat Div, D-85748 Garching, Germany. ESA, Div Space Sci, ISO Data Ctr, Div Astrophys, Madrid 28080, Spain. Astrophys Inst Potsdam, D-14482 Potsdam, Germany. RP Stickel, M (reprint author), Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany. EM stickel@mpia-hd.mpg.de NR 36 TC 75 Z9 75 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 JUL PY 2000 VL 359 IS 3 BP 865 EP 875 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 341JZ UT WOS:000088588400006 ER PT J AU Hanlon, L Laureijs, RJ Metcalfe, L McBreen, B Altieri, B Castro-Tirado, A Claret, A Costa, E Delaney, M Feroci, M Frontera, F Galama, T Gorosabel, J Groot, P Heise, J Kessler, M Kouveliotou, C Palazzi, E van Paradijs, J Piro, L Smith, N AF Hanlon, L Laureijs, RJ Metcalfe, L McBreen, B Altieri, B Castro-Tirado, A Claret, A Costa, E Delaney, M Feroci, M Frontera, F Galama, T Gorosabel, J Groot, P Heise, J Kessler, M Kouveliotou, C Palazzi, E van Paradijs, J Piro, L Smith, N TI ISO detection of a 60 mu m source near GRB 970508 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE gamma rays : bursts; gamma rays : observations; infrared : galaxies; infrared : general; ISM : dust, extinction ID GAMMA-RAY BURST; SPECTRAL ENERGY-DISTRIBUTIONS; OPTICAL COUNTERPART; INFRARED GALAXIES; STAR-FORMATION; GRB-970508; LUMINOSITY; STARBURST; BEPPOSAX; REDSHIFT AB The Infrared Space Observatory observed the field of the gamma-ray burst GRB 970508 with the CAM and PHT instruments, on May 21 and 24, 1997 and with PHT in three filters in November 1997. A source at 60 mu m (flux in May of 66 +/- 10 mJy) was detected near the position of the host galaxy of this gamma-ray burst. The source was detected again in November 1997, at a marginally lower flux (43 +/- 13 mJy). A Galactic cirrus origin and a stellar origin for the emission can be ruled out on the basis of the infrared colours. The marginal evidence for variability in the 60 mu m flux between May and November is not sufficient to warrant interpretation of the source as transient fireball emission. However, the infrared colours are physically reasonable if attributed to conventional dust emission from a single blackbody source. The probability of detecting a 60 mu m source by chance in a PHT beam down to a detection limit of 50 mJy is similar to 5 x 10(-3). If the source is at the redshift of the host galaxy of the gamma-ray burst the fluxes and upper limits at wavelengths from 12 mu m to 170 mu m indicate it is an ultraluminous infrared galaxy (L(ir) similar to 2 x 10(12) L(circle dot)). The star formation rate is estimated to be several hundred solar masses per year, depending significantly on model-dependent parameters. If this source is associated with the host galaxy of GRB 970508, progenitor models which associate GRBs with star-forming regions are favoured. C1 Univ Coll Dublin, Dept Expt Phys, Dublin 4, Ireland. ESA, ISO Data Ctr, Div Astrophys, Villafranca Dasti, Italy. ESA, Div Astrophys, XMM Data Ctr, Villafranca Dasti, Italy. Lab Astrofis Espacial & Fis Fundamental, Madrid 28080, Spain. CSIC, IAA, Inst Astrofis Andalucia, Granada 18080, Spain. CEA, Serv Astrophys, DSM, DAPNIA, F-91191 Gif Sur Yvette, France. CNR, Ist Astrofis Spaziale, I-00133 Rome, Italy. Stockholm Observ, S-13336 Saltsjobaden, Sweden. CNR, ITESRE, Bologna, Italy. Univ Amsterdam, Astron Inst Anton Pannekoek, Amsterdam, Netherlands. SRON, Utrecht, Netherlands. NASA, MSFC, USRA, Huntsville, AL USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. Cork Inst Technol, Dept Appl Phys & Instrumentat, Cork, Ireland. RP Hanlon, L (reprint author), Univ Coll Dublin, Dept Expt Phys, Belfield,Stillorgan Rd, Dublin 4, Ireland. EM lhanlon@bermuda.ucd.ie RI Galama, Titus/D-1429-2014; PIRO, LUIGI/E-4954-2013; Palazzi, Eliana/N-4746-2015; Groot, Paul/K-4391-2016; OI Galama, Titus/0000-0002-1036-396X; PIRO, LUIGI/0000-0003-4159-3984; Groot, Paul/0000-0002-4488-726X; Costa, Enrico/0000-0003-4925-8523; Feroci, Marco/0000-0002-7617-3421; Palazzi, Eliana/0000-0002-8691-7666; Castro-Tirado, A. J./0000-0003-2999-3563 NR 51 TC 17 Z9 17 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUL PY 2000 VL 359 IS 3 BP 941 EP 947 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 341JZ UT WOS:000088588400012 ER PT J AU Bouret, JC Catala, C AF Bouret, JC Catala, C TI NLTE calculations of neutral helium lines in the wind of the Herbig Ae star AB Aurigae SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE line : formation; line : profiles; stars : atmospheres; stars : chromospheres; stars : mass-loss; stars : pre-main sequence ID T-TAURI STARS; TERM SPECTRAL VARIABILITY; BETA-PICTORIS PHENOMENON; INTERMEDIATE-MASS STARS; MAIN-SEQUENCE STARS; X-RAY-EMISSION; AE/BE STARS; INFRARED-EMISSION; ACCRETION DISKS; FORBIDDEN LINES AB In order to improve our knowledge about the structure of the winds of the Herbig Ae/Be stars and the mechanisms that drive them, we performed a NLTE analysis of the formation of helium lines in the wind of AB Aur, the prototype of the whole class. These lines are indeed expected to form in the densest layers of the envelope, at the very base of the wind, and therefore to provide constraints on these regions where the wind originates. A large observational data set is now available which we have extensively used to deduce strong constraints on the physics that prevail in the inner part of the wind. Among these data, we particularly used those from the MUSICOS 1996 campaign, which show that the He I D3 (lambda 5876 Angstrom) line is made of two distincts components: a blue-shifted emission component, and a redshifted component alternatively seen as an absorption or an emission. The classical model for AB Aur's wind (Bouret & Catala 1998; Catala & Kunasz 1987) fails to reproduce the observed profile. We find that the observations can be explained by a two component model in which the base of the wind includes dense and hot clumps of outflowing material, while the bulk of the wind is still described by the model by Bouret & Catala (1998). This clumpy structure can result from the presence of co-rotating interaction regions which form where fast streams in the wind overtake slow streams. Our results show that a blue-shifted emission is formed in such conditions, and can be rotationally modulated as observed, due to fast and slow streams alternating on the line of sight as the star rotates. Our model can also explain the occasional presence of an absorption component near rest wavelength, as formed in the bulk of the extended chromosphere. Concerning the red emission component, which is occasionally observed instead of the absorption one, we argue that it may arise from polar downflows. C1 Observ Midi Pyrenees, Lab Astrophys Toulouse, CNRS UMR 5572, F-31400 Toulouse, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Bouret, JC (reprint author), Observ Midi Pyrenees, Lab Astrophys Toulouse, CNRS UMR 5572, 14 Ave Edouard Belin, F-31400 Toulouse, France. EM bouret@winds.gsfc.nasa.gov NR 71 TC 15 Z9 15 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUL PY 2000 VL 359 IS 3 BP 1011 EP 1024 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 341JZ UT WOS:000088588400021 ER PT J AU Hui, L Kofman, L Shandarin, SF AF Hui, L Kofman, L Shandarin, SF TI Multiple streaming and the probability distribution of density in redshift space SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : theory; galaxies : distances and redshifts; gravitation; large-scale structure of universe ID LARGE-SCALE STRUCTURE; GRAVITATIONAL-INSTABILITY; POWER SPECTRUM; COSMOLOGICAL CONSTANT; GALAXY REDSHIFTS; COLD MATTER; UNIVERSE; APPROXIMATIONS; DISTORTIONS; OMEGA AB We examine several aspects of redshift distortions by expressing the redshift-space density in terms of the eigenvalues and orientation of the local Lagrangian deformation tensor. We explore the importance of multiple streaming using the Zeldovich approximation (ZA), and compute the average number of streams in both real and redshift space. We find that multiple streaming can be significant in redshift space but negligible in real space, even at moderate values of the linear fluctuation amplitude (sigma(l) less than or similar to 1). Moreover, unlike their real-space counterparts, redshift-space multiple streams can how past each other with minimal interactions. Such nonlinear redshift-space effects, which are physically distinct from the fingers-of-God due to small-scale virialized motions, might in part explain the well-known departure of redshift distortions from the classic linear prediction by Kaiser, even at relatively large scales where the corresponding density held in real space is well described by linear perturbation theory. We also compute, using the ZA, the probability distribution function (PDF) of the density, as well as S-3, in real and redshift space, and compare it with the PDF measured from N-body simulations. The role of caustics in defining the character of the high-density tail is examined. We find that (non-Lagrangian) smoothing, due to both finite resolution or discreteness and small-scale velocity dispersions, is very effective in erasing caustic structures, unless the initial power spectrum is sufficiently truncated. C1 NASA, Fermilab Astrophys Ctr, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. CITA, Toronto, ON M5S 3H8, Canada. Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA. RP Hui, L (reprint author), NASA, Fermilab Astrophys Ctr, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. NR 43 TC 17 Z9 17 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 2000 VL 537 IS 1 BP 12 EP 20 DI 10.1086/308991 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 337PN UT WOS:000088371000002 ER PT J AU Stern, D Bunker, A Spinrad, H Dey, A AF Stern, D Bunker, A Spinrad, H Dey, A TI One-line redshifts and searches for high-redshift Ly alpha emission SO ASTROPHYSICAL JOURNAL LA English DT Article DE early universe; galaxies : distances and redshifts; galaxies : evolution; galaxies : formation ID HUBBLE DEEP FIELD; PRIMEVAL GALAXIES; RADIO GALAXIES; SPECTROPHOTOMETRIC STANDARDS; CATALOG; SPECTROSCOPY; EVOLUTION AB We report the serendipitous discovery of two objects close in projection with fairly strong emission lines at long wavelength (lambda similar to 9190 Angstrom). One (A) seems not to be hosted by any galaxy brighter than V-555 = 27.5, Or I-814 = 26.7 (Vega-based 3 sigma limits in 1." 0 diameter apertures), while the other line is associated with a faint (I-814 similar or equal to 24.4) red galaxy (B) offset by 2." 7 and 7 Angstrom spectrally. Both lines are broad (FWHM approximate to 700 km s(-1)), are extended spatially, and have high equivalent widths [W-lambda(obs)(A) > 1225 Angstrom, 95% confidence limit; W-lambda(obs)(B) approximate to 150 Angstrom] No secondary spectral features are detected for galaxy A. Blue continuum and the marginal detection of a second weak line in the spectrum of galaxy B is consistent with [O II] (the strong line) and Mg II (the weak line) at z = 1.466. By association, galaxy A is likely at z = 1.464, implying a rest-frame equivalent width of the [O II] emission line in excess of 600 Angstrom and a projected separation of 30 h(50)(-1) kpc for the galaxy pair. Conventional wisdom states that isolated emission lines with rest-frame equivalent widths larger than similar to 200 Angstrom are almost exclusively Ly alpha. This moderate-redshift discovery therefore compromises recent claims of high-redshift Ly alpha emitters for which other criteria (i.e., line profile, associated continuum decrements) are not reported. We discuss observational tests to distinguish Ly alpha emitters at high redshift from foreground systems. C1 Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Natl Opt Astron Observ, KPNO, Tucson, AZ 85726 USA. RP Stern, D (reprint author), CALTECH, Jet Prop Lab, Mail Stop 169-327, Pasadena, CA 91109 USA. NR 51 TC 54 Z9 54 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 2000 VL 537 IS 1 BP 73 EP 79 DI 10.1086/309001 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 337PN UT WOS:000088371000009 ER PT J AU Piner, BG Edwards, PG Wehrle, AE Hirabayashi, H Lovell, JEJ Unwin, SC AF Piner, BG Edwards, PG Wehrle, AE Hirabayashi, H Lovell, JEJ Unwin, SC TI Space VLBI observations of 3C 279 at 1.6 and 5 GHz SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : jets; quasars : individual (3C 279); radiation mechanisms : nonthermal; radio continuum : galaxies; techniques : interferometric ID EXTRAGALACTIC RADIO-SOURCES; BASE-LINE INTERFEROMETRY; QUASAR 3C-279; BRIGHTNESS TEMPERATURE; SUPERLUMINAL MOTION; BLAZAR 3C-279; TELESCOPE; CAMPAIGN; IMAGES; MERLIN AB We present VLBI Space Observatory Programme (VSOP) observations of the gamma-ray blazar 3C 279 at 1.6 and 5 GHz made on 1998 January 9-10 with the HALCA satellite and ground arrays including the Very Long Baseline Array (VLBA). The combination of the VSOP and VLBA-only images at these two frequencies maps the jet structure on scales from 1 to 100 mas. On small angular scales the structure is dominated by the quasar core and the bright secondary component "C4" located 3 milliarcseconds from the core (at this epoch) at a position angle of -115 degrees. On larger angular scales the structure is dominated by a jet extending to the southwest, which at the largest scale seen in these images connects with the smallest scale structure seen in VLA images. We have exploited two of the main strengths of VSOP: the ability to obtain matched-resolution images to ground-based images at higher frequencies and the ability to measure high brightness temperatures. A spectral index map was made by combining the VSOP 1.6 GHz image with a matched-resolution VLBA-only image at 5 GHz from our VSOP observation on the following day. The spectral index map shows the core to have a highly inverted spectrum, with some areas having a spectral index approaching the limiting value for synchrotron self-absorbed radiation of alpha = +2.5 (where S proportional to nu(+alpha)). Gaussian model fits to the VSOP visibilities revealed high brightness temperatures (>10(12) K) that are difficult to measure with ground-only arrays. An extensive error analysis was performed on the brightness temperature measurements. Most components did not have measurable brightness temperature upper limits, but lower limits were measured as high as 5 x 10(12) K. This lower limit is significantly above both the nominal inverse Compton and equipartition brightness temperature limits. The derived Doppler factor, Lorentz factor, and angle to the line of sight in the case of the equipartition limit are at extreme ends of the ranges of expected values for EGRET blazars. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. Australia Telescope Natl Facil, Epping, NSW 1710, Australia. RP Piner, BG (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 41 TC 18 Z9 19 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 2000 VL 537 IS 1 BP 91 EP 100 DI 10.1086/309031 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 337PN UT WOS:000088371000011 ER PT J AU Dupke, RA White, RE AF Dupke, RA White, RE TI Metallicity gradients in the intracluster gas of Abell 496 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : abundances; galaxies : clusters : individual (Abell 496); intergalactic medium; X-rays : galaxies ID ELLIPTIC GALAXY NGC-4636; INTRA-CLUSTER MEDIUM; X-RAY OBSERVATIONS; 4 RICH CLUSTERS; PERSEUS CLUSTER; ELEMENTAL ABUNDANCES; SURFACE PHOTOMETRY; MEDIUM ENRICHMENT; IRON ABUNDANCES; METAL ABUNDANCE AB Analysis of spatially resolved ASCA spectra of the intracluster gas in Abell 496 confirms there are mild metal abundance enhancements near the center, as previously found in a joint analysis of spectra from Ginga Large Area Counter and Einstein solid state spectrometer. Simultaneous analysis of spectra from all ASCA instruments (SIS + GIS) shows that the iron abundance is 0.36 +/- 0.03 solar 3'-12' from the center of the cluster and rises similar to 50% to 0.53 +/- 0.04 solar within the central 2'. The F-test shows that this abundance gradient is significant at the more than 99.99% level. Nickel and sulfur abundances are also centrally enhanced. We use a variety of elemental abundance ratios to assess the relative contribution of Type Ia supernovae (SNe Ia) and Type II supernovae (SNe II) to the metal enrichment of the intracluster gas. We find spatial gradients in several abundance ratios, indicating that the fraction of iron from SNe Ia increases toward the cluster center, with SNe Ia accounting for similar to 50% of the iron mass 3'-12' from the center and similar to 70% within 2'. The increased proportion of SN Ia ejecta at the center is such that the central iron abundance enhancement can be attributed wholly to SNe Ia; we find no significant gradient in SN II ejecta. These spatial gradients in the proportion of SN Ia/II ejecta imply that the dominant metal enrichment mechanism near the center is different than in the outer parts of the cluster. We show that the central abundance enhancement is unlikely to be due to ram pressure stripping of gas from cluster galaxies or to secularly accumulated stellar mass loss within the central cD. We suggest that the additional SN Ia ejecta near the center is the vestige of a secondary SN Ia-driven wind from the cD (following a more energetic protogalactic SN II-driven wind phase), which was partially smothered in the cD due to its location at the cluster center. C1 Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. NR 72 TC 38 Z9 38 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 2000 VL 537 IS 1 BP 123 EP 133 DI 10.1086/308993 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 337PN UT WOS:000088371000013 ER PT J AU Kinney, AL Schmitt, HR Clarke, CJ Pringle, JE Ulvestad, JS Antonucci, RRJ AF Kinney, AL Schmitt, HR Clarke, CJ Pringle, JE Ulvestad, JS Antonucci, RRJ TI Jet directions in Seyfert galaxies SO ASTROPHYSICAL JOURNAL LA English DT Review DE galaxies : active; galaxies : jets; galaxies : Seyfert; galaxies : structure ID ACTIVE GALACTIC NUCLEI; POINT-SOURCE CATALOG; WARM IRAS SOURCES; COUNTERROTATING DISK FORMATION; CENTRAL BLACK-HOLES; SPIRAL GALAXIES; RADIO STRUCTURES; ACCRETION DISKS; LIMITED SAMPLE; DECOUPLED NUCLEUS AB Here we present the study of the relative angle between the accretion disk (or radio jet) and the galaxy disk for a sample of Seyfert galaxies selected from a mostly isotropic property, the 60 mu m flux, and warm infrared colors. We used VLA A-array 3.6 cm continuum data and ground-based optical imaging, homogeneously observed and reduced to minimize selection effects. For parts of the analysis we enlarged the sample by including galaxies serendipitously selected from the literature. For each galaxy we have a pair of points (i, delta), which are the inclination of the galaxy relative to the line of sight and the angle between the jet projected into the plane of the sky and the host galaxy major axis, respectively. For some galaxies we also had information about which side of the minor axis is closer to Earth. This data is combined with a statistical technique, developed by us, to determine the distribution of beta angles in three dimensions,, the angle between the jet and the host galaxy plane axis. We found from an initial analysis of the data of the 60 mu m sample, where Seyfert 1 and 2 galaxies were not differentiated, that the observed distribution of i and delta values can be well represented either by a homogeneous sin beta distribution in the range 0 degrees less than or equal to beta less than or equal to 90 degrees or in 0 degrees less than or equal to beta less than or equal to 65 degrees, but not by an equatorial ring. A more general model, which tested beta-distributions in the range beta(1) less than or equal to beta less than or equal to beta(2), for different ranges of beta(1) and beta(2) values, required beta(2) to be larger than 65 degrees and gave preference for beta(1) smaller than 40 degrees-50 degrees. An important result from our analysis was obtained when we determined whether the jet was projected against the near or the far side of the galaxy and differentiated between Seyfert 1 and Seyfert 2 galaxies, which showed that the model could not represent Seyfert 1 galaxies adequately. We found that the inclusion of viewing angle restrictions for Seyfert 1 galaxies, namely, that a galaxy can be recognized as a Seyfert 1 only if the angle between the jet and the line of sight (\phi\) is smaller than a given angle phi(c) and that the galaxy inclination i is smaller than an angle i(c), gave rise to statistically acceptable models. This indication that there is a difference in viewing angle to the central engine between Seyfert 1 galaxies and Seyfert 2 galaxies is a direct and independent confirmation of the underlying concepts of the unified model. We discuss possible explanations for the misalignment between the accretion disk and the host galaxy disk: warping of the accretion disk by self-irradiation instability, by the Bardeen-Petterson effect, or by a misaligned gravitational potential of a nuclear star cluster surrounding the black hole, as well as feeding of the accretion disk by a misaligned inflow of gas from minor mergers, capture of individual stars or gas from the nuclear star cluster, and the capture of individual molecular clouds from the host galaxy. C1 Space Telescope Sci Inst, Baltimore, MD 21818 USA. Univ Cambridge, Inst Astron, Observ, Cambridge CB3 0HA, England. Natl Radio Astron Observ, Socorro, NM 87801 USA. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. RP Kinney, AL (reprint author), NASA Headquarters, 300 E St, Washington, DC 20546 USA. NR 106 TC 144 Z9 146 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 2000 VL 537 IS 1 BP 152 EP 177 DI 10.1086/309016 PN 1 PG 26 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 337PN UT WOS:000088371000015 ER PT J AU Cranmer, SR Smith, MA Robinson, RD AF Cranmer, SR Smith, MA Robinson, RD TI A multiwavelength campaign on gamma cassiopeiae. IV. The case for illuminated disk-enhanced wind streams SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; line : profiles; stars : early-type; stars : emission-line, Be; stars : individual (gamma Cassiopeiae); stars : winds, outflows ID COROTATING INTERACTION REGIONS; RADIATION-DRIVEN WINDS; ONE-ARMED OSCILLATIONS; LONG-TERM VARIABILITY; BE-STAR ATMOSPHERES; STELLAR WINDS; X-RAY; O-STARS; DYNAMIC PROCESSES; FAR-UV AB On 1996 March 14-15 we conducted a campaign with the Hubble Space Telescope GHRS to observe the Si lambda lambda 1394, 1403 lines of the B0.5e star gamma Cas at high temporal and spectral resolution. As a part of this similar to 22 hr campaign, the Rossi X-Ray Timing Explorer (RXTE) was also used to monitor this star's copious and variable X-ray emission. In this fourth paper of a series we present an analysis of the rapid variations of the discrete absorption components (DACs) of the Si Iv doublet. The DACs attain a maximum absorption at -1280 km s(-1), taper at higher velocities, and extend to -1800 km s(-1). The DACs in this star's resonance lines have been shown to be correlated with a greater than or similar to 6 yr cycle in the Balmer line emission VIR ratio, and in 1996 this DAC strength was near its maximum. We derive hydrogen densities of 10(9)-10(10) cm(-3) in the DAC material using a curve-of-growth method and find that the plasma becomes marginally optically thick near -1280 km s(-1). The "mean DAC" probably represents a broad "plateau" with a volume density intermediate between the star's midlatitude wind and equatorial disk. We also follow the blueward evolution of subfeatures in the DACs. These features appear to emanate primarily from one or two discrete azimuths on the star and accelerate much more slowly than expected for the background wind, thereby exhibiting an enhanced opacity spiral stream pattern embedded within the structure forming the DAC. In the first two papers in this series, we suggested that active X-ray centers are associated with at least two major cool clouds forced into corotation. Several correlations of flickering in the Si rv DACs are found in our data, which support the idea that changes in X-ray ionizing flux cause changes in the ionization of material at various sectors along the spiral pattern. We demonstrate that similar flickering is visible in archival IUE data from 1982 and may also be responsible for earlier reports from Copernicus of rapid changes in this star's UV and optical lines. Finally, we discovered that flickering of the DAC fluxes in the 1982 data is correlated with rotation phase and shows a modulation with a 7.5 hr cyclical cessation of X-ray flares that was observed recently by RXTE. This confirms our basic picture that lulls in X-ray activity close to the star's surface cause both a lower Si v ionization fraction and an increase in Si Iv variability within the DAC structures. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Space Telescope Sci Inst, CSC, STScI, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, LASP, Greenbelt, MD 20771 USA. Catholic Univ Amer, Washington, DC 20064 USA. RP Cranmer, SR (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. NR 88 TC 21 Z9 21 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 2000 VL 537 IS 1 BP 433 EP 447 DI 10.1086/309008 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 337PN UT WOS:000088371000042 ER PT J AU Sahai, R AF Sahai, R TI The starfish twins: Two young planetary nebulae with extreme multipolar morphology SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; ISM : jets and outflows; planetary nebulae : individual (He 2-47, M1-37); stars : AGB and post-AGB; stars : mass loss ID PROTOPLANETARY NEBULA; MASS-LOSS; STARS; JETS; EVOLUTION; EMISSION; DUST AB We present N alpha images of two objects, He 2-47 and M1-37, obtained during a Hubble Space Telescope imaging survey of young planetary nebulae (PNs) selected on the basis of their low-excitation characteristics. The two objects show a highly aspherical morphology, characterized by multiple lobes distributed around the central star. Such a morphology has never been seen before in any astrophysical setting. Bright structures near the minor axes indicate the presence of dense equatorial tori (seen edge-on in M1-37 and as partial elliptical rings in He 2-47). In both nebulae, the central star is found to be offset from the geometrical center of symmetry of the waist region. The multiple lobes of He 2-47 and M1-37 have been produced fairly recently (a few hundred years ago), based on rough estimates of their expansion ages. The extreme multipolar morphology of these PNs supports the recent hypothesis of Sahai & Trauger that the primary agents for shaping PNs are high-speed collimated outflows that operate during the late asymptotic giant branch (AGE) and/or early post-AGE evolutionary phase; these outflows change their direction episodically, and/or multiple collimated outflows with different axes operate (quasi)simultaneously. Drastic modifications of existing theories or completely new ideas are needed in order to obtain a full understanding of the salient morphological features of He 2-47 and M1-37. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sahai, R (reprint author), CALTECH, Jet Prop Lab, MS 183-900,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 31 TC 52 Z9 52 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 2000 VL 537 IS 1 BP L43 EP L47 DI 10.1086/312748 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 337PP UT WOS:000088371100011 ER PT J AU Titarchuk, L Osherovich, V AF Titarchuk, L Osherovich, V TI delta-invariant for quasi-periodic oscillations and physical parameters of the 4U 0614+09 binary SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; diffusion; stars : individual (4U 0614+09, 4U 1702-42, 4U 1728-34, Scorpius X-1); stars : neutron; waves; X-rays : stars ID NEUTRON-STAR BINARIES; KEPLERIAN OSCILLATIONS AB The recently formulated two-oscillator (TO) model interprets the lowest of the kilohertz frequencies of the twin-peak quasi-periodic oscillations in X-ray binaries as the Keplerian frequency v(K). The high twin frequency v(h) in this model holds the upper hybrid frequency relation to the rotational frequency of the neutron star's magnetosphere Omega: v(h)(2) = v(K)(2) + 43(Omega/2 pi)(2). The vector Omega is assumed to have an angle delta with the normal to the disk. The first oscillator in the TO model allows one to interpret the horizontal branch observed below 100 Hz as the lower mode of the Keplerian oscillator under the influence of the Coriolis force, with frequency v(L) being dependent on v(h), v(K), and delta. For some stars such as 4U 0614+09, Scorpius X-1, and 4U 1702-42, v(h), v(K), and v(L) have been observed simultaneously, thus providing the opportunity to check the central prediction of the TO model, i.e., the constancy of delta for a particular source. Given the considerable variation of each of these three frequencies, the existence of an observational invariant with a clear physical interpretation as a global parameter of the neutron star magnetosphere is an important test of the TO model. Using the results of recent observations of 4U 0614+09, we verify the existence of this invariant and determine the angle delta = 15 degrees.6 + 0 degrees.5 for this star. The second oscillator in the model deals with both a radial (presumably sound) oscillation and a diffuse process in the viscous layer surrounding the neutron star. Our analysis of the viscous oscillation frequency v(V) and the break frequency v(b) of the diffusion shows that the spin value of the inner boundary of the transition layer for 4U 0614+09 is at least 2 times more than the values for 4U 1728-34 and Sco X-1. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. George Mason Univ, Inst Computat Sci & Informat, Fairfax, VA 22030 USA. NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. RP Titarchuk, L (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 19 TC 12 Z9 12 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 2000 VL 537 IS 1 BP L39 EP L42 DI 10.1086/312759 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 337PP UT WOS:000088371100010 ER PT J AU Cotera, AS Simpson, JP Erickson, EF Colgan, SWJ Burton, MG Allen, DA AF Cotera, AS Simpson, JP Erickson, EF Colgan, SWJ Burton, MG Allen, DA TI Interstellar extinction in the vicinity of the Galactic center SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE dust, extinction; Galaxy : center; infrared : ISM : lines and bands ID RECOMBINATION-LINE-INTENSITIES; BAND LUMINOSITY FUNCTION; CONTINUUM OBSERVATIONS; INFRARED-SPECTRA; HYDROGENIC IONS; NUCLEAR BULGE; M-SUPERGIANTS; GAMMA-RATIO; HOT STARS; MILKY-WAY AB We present J (1.2 mum), H (1.6 mum), K' (2.11 mum), and Bry (2.166 mum) images from four large regions within the central 40 pc of the Galaxy. Localized variations in the extinction, as determined by observations of the stellar population, are examined using the median H-K' color as a function of position within each region. As the value of the derived extinction from the stars is dependent upon the intrinsic magnitude of the assumed stellar type, the J-H versus H-K' diagrams are first used to investigate the distribution of stellar types in the four regions, We find that there is a distinct OB population, contrary to earlier assumptions, with the ratio of K and M giants and supergiants to OB stars approximately twice that of the solar neighborhood. Although on the scale of similar to1' fluctuations in the extinction are on the order of A(V) similar to 2, throughout the entire region the extinction varies from A(V) greater than or similar to 25 to A(V) less than or similar to 40. We also examine whether there is any variation in the extinction and stellar number density relative to the unusual radio features in these regions and do not find a significant correlation. Spectral imaging in Bry 2.166 mum emission shows a strong morphological correspondence between the 6 cm radio images and the diffuse Bry emission. By comparing the theoretical Bry flux derived from the radio flux using recombination theory with our measured Bry flux, we obtain a second, independent, estimate of the extinction. We compare the two data sets and find that the extinction as derived from the stars is consistently greater, sometimes by a factor of 2, than the value of the extinction derived from the Bry images. The derived extinction in various regions, however, is insufficient for any of these regions to be located behind the molecular clouds as previously observed in the Galactic center, consistent with the theory that the observed radio emission is produced on the foreground surface of these clouds. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ New S Wales, Sydney, NSW 2057, Australia. Anglo Australian Observ, Epping, NSW, Australia. RP Cotera, AS (reprint author), Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. RI Colgan, Sean/M-4742-2014; OI Burton, Michael/0000-0001-7289-1998 NR 52 TC 27 Z9 28 U1 0 U2 0 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 JUL PY 2000 VL 129 IS 1 BP 123 EP 146 DI 10.1086/313401 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 365MC UT WOS:000089954200006 ER PT J AU Baldwin, JA Verner, EM Verner, DA Ferland, GJ Martin, PG Korista, KT Rubin, RH AF Baldwin, JA Verner, EM Verner, DA Ferland, GJ Martin, PG Korista, KT Rubin, RH TI High-resolution spectroscopy of faint emission lines in the Orion Nebula SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE HII regions; ISM : individual (Orion Nebula); ISM : kinematics and dynamics; line : identification ID PHYSICAL CONDITIONS; CHEMICAL-COMPOSITION; REGIONS; ABUNDANCES; SPECTRUM; IONS; FE; HE AB We present high-resolution spectrophotometric observations of the Orion Nebula, made with the Cassegrain echelle spectrograph on the Blanco 4 m telescope at Cerro Tololo Inter-American Observatory (CTIO). The resolution and signal-to-noise ratio make it possible to identify 444 emission lines in the 3498-7468 Angstrom range, down to 10(4) times fainter than H beta. We present a detailed atlas of these emission lines along with an analysis of the associated errors. This data set is used to study the velocity held in the Orion Nebula. The forbidden lines split into two distinct groups. The low-ionization group has ions with an ionization potential less than 20 eV. Lines of these ions, [O I], [N I], [Ni II], and [Fe II], have recession velocities, relative to the hydrogen lines, of +10 to +15 km s(-1). There is a sharp change to the second, high-ionization group, which includes lines of ions with ionization potentials larger than 20 eV, namely, [S II], [O II], [N II], and [Fe III]. These lines have velocities around +3 km s(-1), with a slight trend of decreasing velocity with the increasing ionization potential. This is consistent with previously proposed dynamical models in which lines of ions with different ionization potentials originate at different distances from the ionizing stars. Significant acceleration appears to take place across the narrow region where Fe(2+) exists. Across this region the gas receives an acceleration of similar to 2.5 x 10(-5) cm s(-2). This provides a constraint on hydrodynamical models. We set a limit He II 4686/H beta < 7 x 10(-5), which in turn sets a limit to the intensity of the ionizing continuum at energies higher than 54 eV. Modern stellar atmospheres predict a continuum that is far stronger than is present in the region near (1) Ori C. C1 Natl Opt Astron Observ, Cerro Tololo Inter Amer Observ, La Serena, Chile. Univ Kentucky, Dept Phys & Astron, Lexington, KY 40506 USA. Univ Toronto, Dept Astron, Toronto, ON M5S 3H8, Canada. Univ Toronto, Canadian Inst Theoret Astrophys, Toronto, ON M5S 3H8, Canada. Western Michigan Univ, Dept Phys, Kalamazoo, MI 49008 USA. NASA, Ames Res Ctr, Astrophys Branch MS 245 6, Moffett Field, CA 94035 USA. RP Baldwin, JA (reprint author), Natl Opt Astron Observ, Cerro Tololo Inter Amer Observ, Casilla 603, La Serena, Chile. EM katya@pa.uky.edu NR 31 TC 58 Z9 58 U1 0 U2 1 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 JUL PY 2000 VL 129 IS 1 BP 229 EP 246 DI 10.1086/313416 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 365MC UT WOS:000089954200009 ER PT J AU Jonin, C Liu, XM Ajello, JM James, GK Abgrall, H AF Jonin, C Liu, XM Ajello, JM James, GK Abgrall, H TI High-resolution electron-impact emission of H-2. I. Cross sections and emission yields 900-1200 angstrom SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE methods : laboratory; molecular processes; ultraviolet : ISM ID DIFFUSE INTERSTELLAR BANDS; HUBBLE-SPACE-TELESCOPE; PHOTOELECTRON ANGULAR-DISTRIBUTIONS; VIBRATIONAL BRANCHING RATIOS; XUV-LASER SPECTROSCOPY; V RYDBERG STATES; MOLECULAR-HYDROGEN; ULTRAVIOLET EMISSION; JUPITER AURORA; TRANSITION-PROBABILITIES AB High-resolution (Delta lambda = 115 m Angstrom) emission spectra of molecular hydrogen produced by electron-impact excitation at 100 eV have been obtained in the wavelength range 900-1200 A. The emission spectra can be assigned to transitions between the X (1)Sigma (+)(g) ground state and the 1s sigma (g)np sigma (1)(u)Sigma (u), and 1s sigma (g)np pi, (1)Pi (u) Rydberg states. Synthetic rotational line spectra based on the excitation function of Liu et al. and calculated 2p sigma B (1)Sigma (+)(u)-X (1)Sigma (+)(g), 2p pi C (1)Pi (u)-X 1 Sigma (+)(g), 3p sigma B' (1)Sigma (+)(u)-X (1)Sigma (+)(g) and 3p piD (1)Pi (u)-X (1)Sigma (+)(g) transition probabilities of Abgrall et al. are generally found to be in good agreement with the experimental spectra in the regions where emissions from 1s sigma (g) np sigma (u) (n greater than or equal to 4) and 1s sigma (g) np pi (u) (n greater than or equal to 4) states are negligible. Emission cross sections for D (1)Pi (+)(u), D' (1)Pi (u), and D " (1)Pi (-)(u), B' 1 Sigma (+)(u), and B " (1)Sigma (+)(u) states are obtained by measuring the emission intensities from these states relative to those from the B (1)Sigma (+)(u),C (1)Pi (u), and D (1)Pi (-)(u) states. A high- resolution EW calibration technique is established. At 100 eV the emission cross sections of the D (1)Pi (u), D' 1 Pi (u), D " (1)Pi (u), B' 1 Sigma (+)(u), and B " (1)Sigma (+)(u) states are measured to be (2.8+/-0.4) x 10(-18), (6.3 +/- 1.3) x 10(-19), (5.9 +/- 1.7) x 10(-20), (2.1 +/- 0.3) x 10(-18), and (1.6 +/- 0.4) x 10(-19) cm(2), respectively. In addition, the vibrational emission cross sections have been compared to the estimated excitation cross sections to obtain the predissociation yields for selected vibrational levels of the D (1)Pi (+)(u), D' (1)Pi (+)(u) and D " (1)Pi (+)(u) states. The B' (1)Sigma (+)(u) state is inferred to have very significant excitation into the H(1s)+H(2p, 2s) dissociative continuum. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ So Calif, Dept Aerosp & Mech Engn, Los Angeles, CA 90089 USA. Observ Paris, DAEC, Sect Meudon, F-92195 Meudon, France. CNRS, UMR 8631, F-92195 Meudon, France. RP Jonin, C (reprint author), CNRS 5516, Lab Traitement Signal & Instrument, 23 Rue Dr P Michelon, F-42023 St Etienne 2, France. NR 87 TC 40 Z9 40 U1 0 U2 5 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUL PY 2000 VL 129 IS 1 BP 247 EP 266 DI 10.1086/313414 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 365MC UT WOS:000089954200010 ER PT J AU Liu, XM Shemansky, DE Ajello, JM Hansen, DL Jonin, C James, GK AF Liu, XM Shemansky, DE Ajello, JM Hansen, DL Jonin, C James, GK TI High-resolution electron-impact emission spectrum of H-2. II. 760-900 angstrom SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE methods : laboratory; molecular processes; ultraviolet : ISM ID HUBBLE-SPACE-TELESCOPE; ROTATIONAL STATE DISTRIBUTIONS; VIBRATIONAL BRANCHING RATIOS; DIFFUSE INTERSTELLAR BANDS; MOLECULAR-HYDROGEN; RYDBERG STATES; LASER SPECTROSCOPY; ULTRAVIOLET EMISSION; JUPITER AURORA; INTENSITY MEASUREMENTS AB A high-resolution (Delta lambda similar to 95 and 240 m Angstrom FWHM) electron-impact-induced emission spectrum of molecular hydrogen has been obtained in the wavelength range 760-900 Angstrom. Analysis of the spectrum results in the assignment of some previously unobserved as well as observed but unassigned emission lines. Emissions observed in the 760-900 Angstrom range and a few selected regions above 900 Angstrom at room temperature (300 K) are tabulated, together with their spectral assignments. The tabulation can be considered as a supplement to the H-2 atlas of Roncin & Launay and can be used for the analysis of EW emission spectra observed in the interstellar medium and planetary atmospheres where H-2 is the major constituent. Emission, predissociation, and autoionization yields for some transitions below 800 Angstrom are discussed. A Delta nu not equal 0 perturbation between the J(j) = 2 levels for nu (j) = 5 of the D' (1)Pi (-)(u) state and nu (j) = 2 of the 10p pi (1)Pi (-)(u) state is inferred. C1 Univ So Calif, Dept Aerosp & Mech Engn, Los Angeles, CA 90089 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Liu, XM (reprint author), Univ So Calif, Dept Aerosp & Mech Engn, Los Angeles, CA 90089 USA. NR 78 TC 15 Z9 15 U1 0 U2 1 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 JUL PY 2000 VL 129 IS 1 BP 267 EP 280 DI 10.1086/313413 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 365MC UT WOS:000089954200011 ER PT J AU Cha, AN Sahu, MS Moos, HW Blaauw, A AF Cha, AN Sahu, MS Moos, HW Blaauw, A TI The local interstellar medium in Puppis-Vela SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE ISM : kinematics and dynamics; ISM : structure; solar neighborhood ID BETA-CANIS-MAJORIS; H-I; NA-I; ALPHA ABSORPTION; GAS; CLOUDS; IONIZATION; LINE; HEMISPHERE; ULYSSES AB The first study of the local interstellar medium (LISM) toward Puppis-Vela (1 = 245 degrees to 275 degrees, b = -15 degrees to +5 degrees, d < 200 pc) is presented in this paper. A study of the locations, sizes, and physical characteristics of local interstellar gas, i.e."astronephography, is included, and relies upon the improved distance measurements provided by Hipparcos parallax measurements. All spectra of more distant sight lines contain absorption features due to intervening local gas, and more distant structures can only be studied accurately if components due to the LISM have been isolated. Towards this end, high-resolution (R 95,000), high signal-to-noise (S/N similar to 110 to 250) Na I lambda lambda 5889.951, 5895.924 spectra of 11 nearby stars in the direction of Puppis-Vela have been obtained with the Coude Echelle Spectrograph on the 1.4 m Coude Auxiliary Telescope at the European Southern Observatory. Toward Puppis-Vela, absorption due to the Local Interstellar Cloud (LIC) was not observed, but components at three distinct velocities were found, and the extent of the local gas producing the features was estimated. The three components have the following locations and velocities: component A-(l approximate to 276 degrees to 298 degrees, b approximate to -5 degrees to +4 degrees), V-hello = +6 to +9 km s(-1) and d similar to 104 pc; component B-(l approximate to 264 degrees to 276 degrees, b approximate to -7 degrees to + 3 degrees), V-hello = + 12 to +15 km s(-1), and d similar to 115 pc; component C-(l approximate to 252 degrees to 271 degrees, b approximate to -8 degrees to -6 degrees), V-hello = +21 to +23 km s(-1) and d similar to 131 pc. The conclusions regarding the ultraviolet spectrum of gamma (2) Vel (l = 263 degrees, b = -8 degrees, d = 258 +/- 35 pc) presented by Fitzpatrick & Spitzer were reexamined in light of this new LISM data, and the ambiguity in their conclusions about several absorption components is resolved. The stars in Puppis-Vela flank the region of the apparent extension of the Local Bubble (or Cavity) known as the beta CMa tunnel, and measurements of the Na I column density towards the sample stars have been used to modify existing estimates of the extent of the tunnel. A compilation of all existing Na I observations of less than 200 pc sight lines around the tunnel reveal that low column densities have been exclusively detected within l approximate to 210 degrees to 250 degrees, and b approximate to -21 degrees to -9 degrees. Near the Galactic plane, at latitudes - 10 degrees < b < 0 degrees and d less than or similar to 150 pc, the tunnel is cofined to l < 270, a lower longitude than was previously reported. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Natl Opt Astron Observ, Tucson, AZ USA. Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands. RP Cha, AN (reprint author), Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NR 57 TC 11 Z9 11 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUL PY 2000 VL 129 IS 1 BP 281 EP 294 DI 10.1086/313411 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 365MC UT WOS:000089954200012 ER PT J AU Takahashi, F Schmoll, WJ Strader, EA Belovich, VM AF Takahashi, F Schmoll, WJ Strader, EA Belovich, VM TI Suppression of a nonpremixed flame stabilized by a backward-facing step SO COMBUSTION AND FLAME LA English DT Article ID EXTINCTION AB The stabilization and suppression behavior of a nonpremixed methane flame formed behind a backward-facing step in a combustion tunnel has been studied by impulsively injecting a gaseous fire-extinguishing agent (CF3Br) into the airflow. Optical observations, including a schlieren method, revealed that two distinct flame stabilization and suppression regimes, i.e., (I) rim-attached and (II) wake-stabilized, appeared as the mean air velocity was increased. The suppression in regime I occurred after immediate detachment of the flame at agent arrival, followed by blowout of the flame in the sheer layer downstream. The suppression in regime II took place as a result of consecutive extinction of the flames in the sheer layer and the recirculation zone, and the latter flame is controlling. The characteristic mixing (or residence) time in the recirculation zone, measured by the sodium D-line emission method, linearly depended on a simple similarity parameter, i.e., the step height divided by the effective mean air velocity. For long agent injection periods, the critical agent mole fraction at suppression approached a minimum value of similar to 0.025, which was identical to the value obtained using a counterflow diffusion flame. On the other hand, the critical agent mole fraction at suppression increased dramatically as the agent injection period was decreased below the characteristic mixing time. Under relatively high air velocities (regime II), the critical agent mole fraction at suppression normalized by the minimum value was a unique function of the agent injection period normalized by the characteristic mixing time and can be predicted using a theoretical expression. Furthermore, the total agent mass delivered can be minimized at the injection period near the characteristic mixing time. Published by Elsevier Science Inc. C1 Univ Dayton, Res Inst, Dayton, OH 45469 USA. USAF, Res Lab, Wright Patterson AFB, OH 45433 USA. RP Takahashi, F (reprint author), NASA, Natl Ctr Micrograv Res Fluids & Combust, Glenn Res Ctr, MS 500-115,21000 Brookpark Rd, Cleveland, OH 44135 USA. NR 23 TC 3 Z9 3 U1 0 U2 7 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0010-2180 J9 COMBUST FLAME JI Combust. Flame PD JUL PY 2000 VL 122 IS 1-2 BP 105 EP 116 DI 10.1016/S0010-2180(00)00106-1 PG 12 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA 322QM UT WOS:000087520300008 ER PT J AU Luo, LS AF Luo, LS TI Some recent results on discrete velocity models and ramifications for lattice Boltzmann equation SO COMPUTER PHYSICS COMMUNICATIONS LA English DT Article; Proceedings Paper CT 8th International Symposium on the Discrete Simulation of Fluid Dynamics (LGA99) CY JUL 28-30, 1999 CL UNIV TOKYO, TOKYO, JAPAN HO UNIV TOKYO DE discrete velocity model; Boltzmann equation; lattice Boltzmann equation; thermodynamic consistency; H-theorem ID NAVIER-STOKES EQUATION; KINETIC-EQUATIONS; GAS AUTOMATA; FLOW; ENTROPY; SIMULATIONS; SCHEME; FLUID AB Some rigorous results on discrete velocity models are briefly reviewed and their ramifications for the lattice Boltzmann equation (LBE) are discussed. In particular, issues related to thermodynamics and H-theorem of the lattice Boltzmann equation are addressed. It is argued that for the lattice Boltzmann equation satisfying the correct hydrodynamic equations, there cannot exist an H-theorem. Nevertheless, the equilibrium distribution function of the lattice Boltzmann equation can closely approximate the genuine equilibrium which minimizes the H-function of the corresponding continuous Boltzmann equation. It is also pointed out that the "equilibrium" in the LEE models is an attractor rather than a true equilibrium in the rigorous sense of H-theorem. Since there is no H-theorem to guarantee the stability of the LEE models at the attractor, the stability of the attractor can only be studied by means other than proving an H-function. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Langley Res Ctr, Inst Comp Appl Sci & Engn, Hampton, VA 23681 USA. RP Luo, LS (reprint author), NASA, Langley Res Ctr, Inst Comp Appl Sci & Engn, MS 132C,3 West Reid St,Bldg 1152, Hampton, VA 23681 USA. RI Luo, Li-Shi/A-4561-2011 OI Luo, Li-Shi/0000-0003-1215-7892 NR 41 TC 20 Z9 20 U1 0 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0010-4655 J9 COMPUT PHYS COMMUN JI Comput. Phys. Commun. PD JUL PY 2000 VL 129 IS 1-3 BP 63 EP 74 DI 10.1016/S0010-4655(00)00093-X PG 12 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 336XH UT WOS:000088327900008 ER PT J AU Burnett, T Chaput, C Arrighi, H Norris, J Suson, DJ AF Burnett, T Chaput, C Arrighi, H Norris, J Suson, DJ TI Simulating the Glast satellite with Gismo SO COMPUTING IN SCIENCE & ENGINEERING LA English DT Article AB A Monte Carlo simulation package plays a significant role in the design of the Gamma Ray Large Area Space Telescope, The successor to the Compton Gamma Ray Observatory. C1 Univ Washington, Seattle, WA 98195 USA. Stanford Linear Accelerator Ctr, Stanford, CA 94305 USA. NASA, Goddard Space Flight Ctr, Compton Observ Sci Support Ctr, Greenbelt, MD USA. Texas A&M Univ, Kingsville, TX USA. RP Burnett, T (reprint author), Univ Washington, Seattle, WA 98195 USA. NR 7 TC 8 Z9 9 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 1521-9615 J9 COMPUT SCI ENG JI Comput. Sci. Eng. PD JUL-AUG PY 2000 VL 2 IS 4 BP 9 EP 18 DI 10.1109/5992.852387 PG 10 WC Computer Science, Interdisciplinary Applications SC Computer Science GA 329UK UT WOS:000087926500004 ER PT J AU DeMartini, EE Uchiyama, JH Williams, HA AF DeMartini, EE Uchiyama, JH Williams, HA TI Sexual maturity, sex ratio, and size composition of swordfish, Xiphias gladius, caught by the Hawaii-based pelagic longline fishery SO FISHERY BULLETIN LA English DT Article ID REPRODUCTION; FLORIDA; WATERS AB Swordfish (Xiphias gladius) caught by the Hawaii-based pelagic longline fishery during March 1994-June 1997 were examined at sea by observers of the National Marine Fisheries Service, Southwest Region. Observers provided unbiased size and sex composition data for 4.8% of the swordfish catch and 4.9% of the effort in number of hooks of the fishery during the 40-mo. period. Observers measured body lengths for more than 8600 swordfish brought aboard participating vessels; sex, based on macroscopic appearance of gonads, was identified aboard ship for 77% of measured fish. Sex identifications were later verified (0.5% error rate) and gonadal developmental stage described for 1336 fish whose sex was identified in the field. Logistic regression was used to estimate sex-specific, median body size at sexual maturity (L-50) by using microscopic morphological evidence for gonadal development. L-50 was 102 cm +/-2.5 (95% CI) cm eye-to-fork length (EFL and 144 +/- 2.8 cm EFL for males (n=506) and females (n=822), respectively. Sex ratios were an increasing power function between 100 and 220 cm, and nearly all fish >220 cm EFL were females. Sex composition and body size varied temporally and spatially, especially the latter. Relatively more males were caught south of 27 degrees N: females dominated catches north of 27 degrees N. Small-bodied fish of both sexes prevailed year-round below 22 degrees N. A greater percentage of large-bodied (>156-cm [males], >172-cm [females] EFL fish were caught north of 35 degrees N during the late summer-early Minter. The latter observations are consistent with several nonmutually exclusive hypotheses of migration energetics and body muscle heat conservation, both of which ale discussed. C1 NOAA, Natl Marine Fisheries Serv, SW Fisheries Sci Ctr, Honolulu Lab, Honolulu, HI 96822 USA. RP DeMartini, EE (reprint author), NOAA, Natl Marine Fisheries Serv, SW Fisheries Sci Ctr, Honolulu Lab, 2570 Dole St, Honolulu, HI 96822 USA. NR 49 TC 42 Z9 46 U1 0 U2 2 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 JUL PY 2000 VL 98 IS 3 BP 489 EP 506 PG 18 WC Fisheries SC Fisheries GA 341LT UT WOS:000088592400004 ER PT J AU Drass, DM Bootes, KL Lyczkowski-Shultz, J Comyns, BH Holt, GJ Riley, CM Phelps, RP AF Drass, DM Bootes, KL Lyczkowski-Shultz, J Comyns, BH Holt, GJ Riley, CM Phelps, RP TI Larval development of red snapper, Lutjanus campechanus, and comparisons with co-occurring snapper species SO FISHERY BULLETIN LA English DT Article ID YELLOWTAIL SNAPPER; ATLANTIC; IDENTIFICATION; CHRYSURUS; PISCES; FISHES AB The larval development of red snapper, Lutjanus campechanus, is described from reared larvae and from specimens collected in the Gulf of Mexico (GOM). Snapper larvae are pelagic and are characterized by the following features: a deep and compressed, lightly pigmented body; moderately short gut; 24 myomeres; and elongated dorsal and pelvic fins that form early in development. Specimens of L. campechanus (1.9 to 26.1 mm) also showed the presence of weak serrations on pelvic-fin spines, absence of serrations on preopercular or dorsal spines, early forming pigment in dorsal and pelvic fins, and notochord flexion between 3.6 and 5.5 mm. Preflexion larvae of the snapper subfamily Lutjaninae in GOM collections cannot be reliably identified to species despite recent larval descriptions. Species-specific differences in number, spacing, and size of melanophores in the postanal ventral series are evident in the youngest larvae of species from the GOM whose development has been described (Ocyurus chrysurus, L. analis, L. synagris, L, griseus, L. campechanus, and Rhomboplites aurorubens) but further evaluation of the utility of these characters is needed. Characteristics that distinguish mid- to late-flexion larvae of these species are compiled in our study and discussed. Among known GOM lutjanine larvae, body depth, pelvic-ray length and serrations on the angle spine of the preopercle can be used in combination with pigmentation to identify larvae to species. Presence of melanistic pigment land size at first appearance) or absence of melanistic pigment in the following locations are useful characters for larval snapper identification: anterior surface of the visceral mass, ventral to notochord flexure; internal area over the notochord; dorsal midline of caudal peduncle; soft dorsal fin; analfin base ol membrane; and pelvic fin. C1 NOAA, Natl Marine Fisheries Serv, Pascagoula, MS 39567 USA. Univ Texas, Inst Marine Sci, Port Aransas, TX 78373 USA. Gulf Coast Res Lab, Ocean Springs, MS 39564 USA. Gulf Coast Bird Observ, Lake Jackson, TX 77566 USA. Auburn Univ, Dept Fisheries & Allied Aquacultures, Auburn, AL 36849 USA. RP Drass, DM (reprint author), NOAA, Natl Marine Fisheries Serv, 3209 Frederick St, Pascagoula, MS 39567 USA. NR 32 TC 16 Z9 16 U1 0 U2 6 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 JUL PY 2000 VL 98 IS 3 BP 507 EP 527 PG 21 WC Fisheries SC Fisheries GA 341LT UT WOS:000088592400005 ER PT J AU Karlstrom, KE Bowring, SA Dehler, CM Knoll, AH Porter, SM Des Marais, DJ Weil, AB Sharp, ZD Geissman, JW Elrick, MB Timmons, JM Crossey, LJ Davidek, KL AF Karlstrom, KE Bowring, SA Dehler, CM Knoll, AH Porter, SM Des Marais, DJ Weil, AB Sharp, ZD Geissman, JW Elrick, MB Timmons, JM Crossey, LJ Davidek, KL TI Chuar Group of the Grand Canyon: Record of breakup of Rodinia, associated change in the global carbon cycle, and ecosystem expansion by 740 Ma SO GEOLOGY LA English DT Article DE Rodinia; Chuar Group; Grand Canyon; Neoproterozoic; C isotopes ID SOUTH CHINA; PROTEROZOIC SUPERCONTINENT; ISOTOPIC COMPOSITION; SUCCESSIONS; EVOLUTION; LAURENTIA; SEAWATER; COMPLEX; ARIZONA; EARTH AB The Chuar Group (similar to 1.600 m thick) preserves a record of extensional tectonism, ocean-chemistry fluctuations, and biological diversification during the late Neoproterozoic Era. An ash layer from the top of the section has a U-Pb zircon age of 742 +/- 6 Ma. The Chuar Group was deposited at low latitudes during extension on the north-trending Butte fault system and is inferred to record rifting during the breakup of Rodinia. Shallow-marine deposition is documented by tide- and wave-generated sedimentary structures, facies associations, and fossils. C isotopes in organic carbon show large stratigraphic variations, apparently recording incipient stages of the marked C isotopic fluctuations that characterize later Neoproterozoic time. Upper Chuar rocks preserve a rich biota that includes not only cyanobacteria and algae, but also heterotrophic protists that document increased food web complexity in Neoproterozoic ecosystems, The Chuar Group thus provides a well-dated, high-resolution record of early events in the sequence of linked tectonic, biogeochemical, environmental and biological changes that collectively ushered in the Phanerozoic Eon. C1 Univ New Mexico, Dept Earth & Planetary Sci, Albuquerque, NM 87131 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. Harvard Univ, Dept Organism & Evolutionary Biol, Cambridge, MA 02138 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Michigan, Dept Geosci, Ann Arbor, MI 48109 USA. RP Karlstrom, KE (reprint author), Univ New Mexico, Dept Earth & Planetary Sci, Albuquerque, NM 87131 USA. RI Weil, Arlo/B-8522-2008; Crossey, Laura/C-2033-2008 OI Crossey, Laura/0000-0001-6237-8023 NR 38 TC 82 Z9 91 U1 1 U2 25 PU GEOLOGICAL SOC AMERICA, INC PI BOULDER PA PO BOX 9140, BOULDER, CO 80301-9140 USA SN 0091-7613 J9 GEOLOGY JI Geology PD JUL PY 2000 VL 28 IS 7 BP 619 EP 622 DI 10.1130/0091-7613(2000)28<619:CGOTGC>2.0.CO;2 PG 4 WC Geology SC Geology GA 327YN UT WOS:000087822200011 PM 11543503 ER PT J AU Rampino, MR Prokoph, A Adler, A AF Rampino, MR Prokoph, A Adler, A TI Tempo of the end-Permian event: High-resolution cyclostratigraphy at the Permian-Triassic boundary SO GEOLOGY LA English DT Article DE Permian-Triassic boundary; Milankovitch cycles; extinctions; cyclostratigraphy ID MASS EXTINCTION; TIME-SERIES; CLIMATE; EVOLUTION; CYCLE AB The Permian-Triassic (P-T) boundary is marked by the most severe mass extinction in the geologic record. High-resolution cyclo-stratigraphy on a 10(4) yr scale across the P-T boundary in a core from the Carnic Alps (Austria) revealed significant cycles in the ratio similar to 40:10:4.7:2.3 m, identified with Milankovitch cycles of similar to 412:100:40:20 k.y. (eccentricity 1 and 2, obliquity, and precession), Wavelet analysis indicates continuity of deposition across the boundary, with an average accumulation rate of similar to 10 cm/k.y. The dramatic faunal changes at the P-T boundary can be constrained within an interval of <60 k.y. (possibly <8 k.y.), with the accompanying sharp negative global carbon-isotope shift within <30 k.y., suggesting a catastrophic cause. C1 NYU, Earth & Environm Sci Program, New York, NY 10003 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Univ Ottawa, Dept Earth Sci, Ottawa, ON K1N 6N5, Canada. NYU, Dept Phys, New York, NY 10003 USA. RP Rampino, MR (reprint author), NYU, Earth & Environm Sci Program, 100 Washington Sq E, New York, NY 10003 USA. NR 33 TC 87 Z9 104 U1 1 U2 16 PU GEOLOGICAL SOC AMERICA, INC PI BOULDER PA PO BOX 9140, BOULDER, CO 80301-9140 USA SN 0091-7613 J9 GEOLOGY JI Geology PD JUL PY 2000 VL 28 IS 7 BP 643 EP 646 DI 10.1130/0091-7613(2000)28<643:TOTEEH>2.0.CO;2 PG 4 WC Geology SC Geology GA 327YN UT WOS:000087822200017 ER PT J AU Chu, XZ Pan, WL Papen, G Gardner, CS Swenson, G Jenniskens, P AF Chu, XZ Pan, WL Papen, G Gardner, CS Swenson, G Jenniskens, P TI Characteristics of Fe ablation trails observed during the 1998 Leonid meteor shower SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LIDAR OBSERVATIONS; IRON AB Eighteen Fe ablation trails were observed during the 17/18 Nov 1998 Leonid meteor shower with an airborne Fe lidar aboard the NSF/NCAR Electra aircraft over Okinawa. The average altitude of the 18 trails from the high velocity (72 km/s) Leonid meteors, 95.67+/-0.93 km, is approximately 6.7 km higher than previously observed for slower (similar to 30 km/s) sporadic meteors. This height difference is consistent with the assumption that meteors ablate when atmospheric drag reaches a critical threshold. The average age of the Fe trails, determined by a diffusion model, is 10.1 min. The youngest ages were observed below 92 km and above 98 km where chemistry and diffusion dominate, respectively. The average abundance of the trails is 10% of the abundance of the background Fe layer. Observations suggest that the 1998 Leonid shower did not have a significant impact on the abundance of the background Fe layer. C1 Univ Illinois, Dept Elect & Comp Engn, Urbana, IL 61801 USA. NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. RP Chu, XZ (reprint author), Univ Illinois, Dept Elect & Comp Engn, 1406 W Green St, Urbana, IL 61801 USA. RI Chu, Xinzhao/I-5670-2015 OI Chu, Xinzhao/0000-0001-6147-1963 NR 12 TC 22 Z9 24 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 JUL 1 PY 2000 VL 27 IS 13 BP 1807 EP 1810 DI 10.1029/1999GL010756 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 331LY UT WOS:000088021600001 ER PT J AU Lui, ATY Liou, K Newell, PT Meng, CI Ohtani, S McEntire, RW Fox, NJ Lepping, RP Paterson, WR Sigwarth, JB Frank, LA Kokubun, S Parks, GK Moretto, T Yumoto, K AF Lui, ATY Liou, K Newell, PT Meng, CI Ohtani, S McEntire, RW Fox, NJ Lepping, RP Paterson, WR Sigwarth, JB Frank, LA Kokubun, S Parks, GK Moretto, T Yumoto, K TI Conjunction of tail satellites for substorm study: ISTP event of 1997 January 2 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INSTABILITY; PLASMA; FIELD AB The interval of 1997 January 1-2 was identified as a favorable conjunction of Geotail and IMP-8 to examine substorm activity in the mid-tail region prior to data acquisition. On January 2, 1997, global auroral observations from Polar indicated a substorm onset at similar to 0120 UT followed by a substorm intensification at similar to 0154 UT sit a local time spatially separated from the initial substorm activity region. During this event, both Geotail and IMP-8 were in the mid-tail near the midnight meridian (Geotail (X, Y) approximate to (-30,-3)R-E and IMP-8 (X,Y) approximate to (-37,2)R-E). Observations indicated that the substorm onset activity was localized in the postmidnight region. After the onset, Geotail detected a transient dipolarization which was not accompanied by large plasma flows (i.e., \ V-x \less than or equal to 200 km/s). The subsequent substorm intensification produced enduring dipolarization at Geotail and highly fluctuating magnetic field (mostly northward B-z) at IMP-8. Observations for this substorm showed no indication of mid-tail activities occurring prior to auroral brightening for both onset and intensification even though the satellites observed activities subsequently. Close examination of data indicates that the delays were not due to a dawn-dusk expansion of mid-tail activity. These results are consistent with substorm activity beginning in the near-Earth region first, followed by activity in the mid-tail region later. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. Nagoya Univ, Solar Terr Environm Lab, Aichi 442, Japan. Univ Washington, Seattle, WA USA. Danish Space Res Inst, Copenhagen, Denmark. Kyushu Univ 33, Dept Earth & Planetary Sci, Fukuoka 8128581, Japan. RP Lui, ATY (reprint author), Johns Hopkins Univ, Appl Phys Lab, Johns Hopkins Rd, Laurel, MD 20723 USA. RI Paterson, William/F-5684-2012; Moretto, Therese/B-6846-2013; Ohtani, Shinichi/E-3914-2016; Fox, Nicola/P-6692-2016; Liou, Kan/C-2089-2016 OI Moretto, Therese/0000-0002-2403-5561; Ohtani, Shinichi/0000-0002-9565-6840; Fox, Nicola/0000-0003-3411-4228; Liou, Kan/0000-0001-5277-7688 NR 11 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 JUL 1 PY 2000 VL 27 IS 13 BP 1831 EP 1834 DI 10.1029/1999GL010772 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 331LY UT WOS:000088021600007 ER PT J AU Lara, A Gopalswamy, N DeForest, C AF Lara, A Gopalswamy, N DeForest, C TI Change in photospheric magnetic flux during coronal mass ejections (vol 27, pg 1435, 2000) SO GEOPHYSICAL RESEARCH LETTERS LA English DT Correction C1 Catholic Univ Amer, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Lara, A (reprint author), Catholic Univ Amer, Washington, DC 20064 USA. RI Gopalswamy, Nat/D-3659-2012 NR 1 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 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 1 PY 2000 VL 27 IS 13 BP 1863 EP 1863 DI 10.1029/2000GL900009 PG 1 WC Geosciences, Multidisciplinary SC Geology GA 331LY UT WOS:000088021600015 ER PT J AU Thompson, BJ Cliver, EW Nitta, N Delannee, C Delaboudiniere, JP AF Thompson, BJ Cliver, EW Nitta, N Delannee, C Delaboudiniere, JP TI Coronal dimmings and energetic CMEs in April-May 1998 (vol 27, pg 1431, 2000) SO GEOPHYSICAL RESEARCH LETTERS LA English DT Correction C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USAF, Res Lab, Hanscom AFB, MA USA. Lockheed Martin Solar & Astrophys Lab, Palo Alto, CA USA. Inst Astrophys Spatiale, Orsay, France. RP Thompson, BJ (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Thompson, Barbara/C-9429-2012 NR 1 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 JUL 1 PY 2000 VL 27 IS 13 BP 1865 EP 1865 DI 10.1029/2000GL900010 PG 1 WC Geosciences, Multidisciplinary SC Geology GA 331LY UT WOS:000088021600016 ER PT J AU Gurnett, DA Persoon, AM Kurth, WS Roux, A Bolton, SJ AF Gurnett, DA Persoon, AM Kurth, WS Roux, A Bolton, SJ TI Plasma densities in the vicinity of Callisto from Galileo plasma wave observations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETOSPHERE; RADIATION; JUPITER; EUROPA AB The Galileo spacecraft has made seven close flybys of Jupiter's moon Callisto. During the closest of these (C22), which approached to within 535 km of the surface, the plasma wave instrument detected a very clear upper hybrid emission as the spacecraft passed near the moon. The peak electron density indicated by the upper hybrid resonance emission was 400 cm(-3), almost one-thousand times the electron density cm in the magnetosphere of Jupiter at the orbit of Callisto. These observations indicate that Callisto is probably surrounded by a dense ionospheric-like plasma. C1 Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. UVSQ, CETP, Velizy, France. Jet Prop Lab, Pasadena, CA 91109 USA. RP Gurnett, DA (reprint author), Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. OI Kurth, William/0000-0002-5471-6202 NR 17 TC 18 Z9 18 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 JUL 1 PY 2000 VL 27 IS 13 BP 1867 EP 1870 DI 10.1029/2000GL003751 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 331LY UT WOS:000088021600017 ER PT J AU Mitchell, DL Lin, RP Reme, H Crider, DH Cloutier, PA Connerney, JEP Acuna, MH Ness, NF AF Mitchell, DL Lin, RP Reme, H Crider, DH Cloutier, PA Connerney, JEP Acuna, MH Ness, NF TI Oxygen Auger electrons observed in Mars' ionosphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID RADIO OCCULTATION METHODS; MAGNETIC-FIELD; IONIZATION; VENUS; CO AB Over the course of 290 orbits, the Electron Reflectometer onboard Mars Global Surveyor consistently observed a plasma boundary at a median altitude of 380 km, where electron fluxes at energies greater than similar to 100 eV change abruptly by about an order of magnitude. Above the boundary, electron energy spectra are consistent with solar wind electrons that have been shocked and then cooled by impact with exospheric neutrals. Below the boundary, electron energy spectra exhibit a broad feature from 20 to 50 eV, which likely results from a blend of unresolved. photoionization peaks that have been predicted by published models of ionospheric photoelectrons at Mars. We attribute a second feature at similar to 500 eV to oxygen Auger electrons. The 500-eV flux level measured below the boundary responds to variations in the solar soft x-ray flux and is consistent with a balance between photoionization and loss by impact with atmospheric neutral atoms. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Ctr Etud Spatiale Rayonnements, F-31028 Toulouse 4, France. Rice Univ, Dept Phys & Astron, Houston, TX 77005 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. RP Mitchell, DL (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RI connerney, john/I-5127-2013; Hurley, Dana/F-4488-2015 OI Hurley, Dana/0000-0003-1052-1494 NR 18 TC 53 Z9 53 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 JUL 1 PY 2000 VL 27 IS 13 BP 1871 EP 1874 DI 10.1029/1999GL010754 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 331LY UT WOS:000088021600018 ER PT J AU Demoz, B Starr, D Whiteman, D Evans, K Hlavka, D Peravali, R AF Demoz, B Starr, D Whiteman, D Evans, K Hlavka, D Peravali, R TI Raman LIDAR detection of cloud base SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ATMOSPHERE; SCATTERING; HEIGHT AB Advantages introduced by Raman lidar systems for cloud base determination during precipitating periods are explored using two case studies of light rain and virga conditions. A combination of the Raman lidar derived profiles of water vapor mixing ratio and aerosol scattering ratio, together with the Raman scattered signals from liquid drops, can minimize or even eliminate some of the problems associated with cloud boundary detection using elastic backscatter lidars. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Demoz, B (reprint author), NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. RI Demoz, Belay/N-4130-2014 NR 16 TC 7 Z9 7 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 JUL 1 PY 2000 VL 27 IS 13 BP 1899 EP 1902 DI 10.1029/1999GL010941 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 331LY UT WOS:000088021600025 ER PT J AU Nathan, TR Cordero, EC Li, L Wuebbles, DJ AF Nathan, TR Cordero, EC Li, L Wuebbles, DJ TI Effects of planetary wave-breaking on the seasonal variation of total column ozone SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERE AB The effects of planetary wave breaking on the seasonal variation of total column ozone are investigated using a zonally averaged chemical-radiative-transport model of the atmosphere. The planetary wave breaking effects of zonal wavenumbers k=1 and k=2 are significant in the middle latitude stratosphere during Northern Hemisphere (NH) winter, whereas only wave k=1 is important during Southern Hemisphere (SH) winter. The mixing and induced meridional circulation due to the planetary wave breaking increases the seasonal variation of total column ozone in NH (SH) middle latitudes by similar to 20% (similar to 10%). C1 Univ Calif Davis, Dept Land Air & Water Resources, Atmospher Sci Program, Davis, CA 95616 USA. Monash Univ, Cooperat Res Ctr So Hemisphere Meteorol, Clayton, Vic 3168, Australia. San Jose State Univ Fdn, NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Illinois, Dept Atmospher Sci, Urbana, IL 61801 USA. RP Nathan, TR (reprint author), Univ Calif Davis, Dept Land Air & Water Resources, Atmospher Sci Program, 1 Shields Ave, Davis, CA 95616 USA. RI Nathan, Terrence/F-5958-2011 NR 10 TC 6 Z9 6 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 1 PY 2000 VL 27 IS 13 BP 1907 EP 1910 DI 10.1029/1999GL010891 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 331LY UT WOS:000088021600027 ER PT J AU Yu, JY Liu, WT Mechoso, CR AF Yu, JY Liu, WT Mechoso, CR TI An SST anomaly dipole in the northern subtropical Pacific and its relationships with ENSO SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB This study examines the links between tropical and subtropical sea surface temperature (SST) anomalies in the Pacific Ocean during ENSO (El Nino-Southern Oscillation) events. A long-term simulation by the UCLA coupled atmosphere-ocean general circulation model is used. It is found that a zonally-oriented SST anomaly dipole in the subtropical Pacific develops almost simultaneously with and is closely related to tropical ENSO events. The dipole is located east of the dateline between 20 degrees N and 40 degrees N and consists of an anomaly center off the coast of the North America and another anomaly center with opposite sign further to the west. It is demonstrated that this dipole feature is primarily driven by anomalous surface heat fluxes associated with the altered atmospheric circulation during ENSO events. C1 Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab 300 323, Pasadena, CA 91109 USA. RP Yu, JY (reprint author), Univ Calif Los Angeles, Dept Atmospher Sci, 405 Hilgard Ave, Los Angeles, CA 90095 USA. RI Yu, Jin-Yi/G-3413-2011 OI Yu, Jin-Yi/0000-0001-6156-7623 NR 13 TC 7 Z9 7 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 JUL 1 PY 2000 VL 27 IS 13 BP 1931 EP 1934 DI 10.1029/1999GL011340 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 331LY UT WOS:000088021600033 ER PT J AU Hernandez-Pajares, M Juan, JM Sanz, J Colombo, OL AF Hernandez-Pajares, M Juan, JM Sanz, J Colombo, OL TI Application of ionospheric tomography to real-time GPS carrier-phase ambiguities resolution, at scales of 400-1000 km and with high geomagnetic activity SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The influence of the ionosphere can be one of the main obstacles to GPS carrier phase ambiguity resolution in real-time, particularly over long baselines. This is important to all users of GPS requiring sub-decimeter positioning, perhaps in real time, especially with high geomagnetic activity or close to the Solar Maximum. Therefore, it is desirable to have a precise estimation of the ionospheric delay in realtime, to correct the data. In this paper we asses a real-time tomographic model of the ionosphere created using dual-frequency phase data simultaneously collected with the receivers of a network of stations in the USA and Canada, with separations of 400-1000 km, during a period of high geomagnetic activity (Kp=6). When the tomographic ionospheric correction is included, the resolution on-the-fly (OTF) of the widelane double-differenced ambiguities at the reference stations is nearly 100% successful for satellite elevations above 20 degrees, while the resolution of the L-1, L-2 ambiguities at the rover is typically more than 80% successful. C1 Univ Politecn Catalunya, Grp Astron & Geomat, E-08034 Barcelona, Spain. NASA, Goddard Space Flight Ctr, USRA, Greenbelt, MD 20771 USA. RP Hernandez-Pajares, M (reprint author), Univ Politecn Catalunya, Grp Astron & Geomat, Campus Nord Mod C-3,Jordi Girona 1, E-08034 Barcelona, Spain. RI Sanz Subirana, Jaume/C-1265-2014; Juan Zornoza, Jose Miguel/S-6224-2016 OI Sanz Subirana, Jaume/0000-0001-8880-7084; Juan Zornoza, Jose Miguel/0000-0003-1126-2367 NR 8 TC 39 Z9 42 U1 0 U2 8 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 JUL 1 PY 2000 VL 27 IS 13 BP 2009 EP 2012 DI 10.1029/1999GL011239 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 331LY UT WOS:000088021600053 ER PT J AU Yarnal, B Lakhtakia, MN Yu, Z White, RA Pollard, D Miller, DA Lapenta, WM AF Yarnal, B Lakhtakia, MN Yu, Z White, RA Pollard, D Miller, DA Lapenta, WM TI A linked meteorological and hydrological model system: the Susquehanna River Basin Experiment (SRBEX) SO GLOBAL AND PLANETARY CHANGE LA English DT Article DE hydroclimatic modeling; mesoscale meteorological model; hydrological model; river basin hydrology; Susquehanna River Basin ID GLOBAL CLIMATE MODEL; TRANSFER SCHEME LSX; BOUNDARY-LAYER; GENESIS; SIMULATION; SENSITIVITY; RESOLUTION; REGCM2; TESTS; CO2 AB The goal of the Susquehanna River Basin Experiment (SRBEX) is to simulate the basin's hydrologic response to atmospheric forcing at various time scales. To reach this goal, SRBEX concentrates on developing climate downscaling methodologies. One downscaling approach links a high-resolution meteorological model and a suite of coupled hydrological models. This paper (1) provides an overview of this linked model system and its elements, (2) describes a series of simulations and sensitivity experiments, and (3) discusses ongoing model development. In a typical simulation, a nested version of the Penn State-NCAR mesoscale meteorological model (MM5) simulates the precipitation from a storm system passing over the river basin. The resulting high-resolution precipitation field, with grid increments as fine as 4 km, then drives the Hydrological Modeling System (HMS). HMS is composed of physically based, interactive surface routing, groundwater, soil water, and channel leakage components. An important aspect of the system is the application of a geographic information system (GIS) to control the high-resolution soils, land-use, and digital terrain data at the model interface. One significant output from the model system is a simple hydrograph, which represents the integration of basin hydrology over time and space. Experiments have been performed to determine the sensitivity of the linked model system results to the rainfall-runoff abstraction method and to the MM5 nesting scheme. Ongoing research aims at expanding the time scales of analysis, improving model efficiency and speed of computation, and changing the present meteorological-hydrological interaction from a linked system to a coupled system. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Penn State Univ, Ctr Earth Syst Sci, University Pk, PA 16802 USA. Univ Nevada, Dept Geosci, Las Vegas, NV 89154 USA. George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35806 USA. RP Yarnal, B (reprint author), Penn State Univ, Ctr Earth Syst Sci, 22217 Earth Engn Sci Bldg, University Pk, PA 16802 USA. NR 27 TC 14 Z9 17 U1 0 U2 2 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 JUL PY 2000 VL 25 IS 1-2 BP 149 EP 161 DI 10.1016/S0921-8181(00)00026-6 PG 13 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA 336ZU UT WOS:000088333500010 ER PT J AU McMuldroch, S Pilorz, SH Danielson, GE AF McMuldroch, S Pilorz, SH Danielson, GE CA NIMS Sci Team TI Galileo NIMS near-infrared observations of Jupiter's ring system SO ICARUS LA English DT Article DE Jupiter; planetary rings; planetary rings; Jupiter; infrared observations ID MAPPING SPECTROMETER EXPERIMENT; JOVIAN RING; LORENTZ RESONANCES; SATELLITES AB We present the first observations of the jovian ring system viewed at near-infrared wavelengths in forward-scattered light. The eclipse of the Sun by Jupiter during the "C3" orbit of the Galileo spacecraft afforded favorable conditions for the Near Infrared Mapping Spectrometer (NIMS) to observe the ring system between 0.7 and 5.2 mu m at a spectral resolution of approximate to 0.04 mu m. NIMS images show the nearly edge-on main ring from just inside the ansa at 1.80 R-J down to 1.05 R-J (where 1 R-J = 71398 km), at a spatial resolution of 450 km along the ring and 1130 km out of the ring plane. At these spatial resolutions, no fine structure is apparent in the ring. The large wavelength coverage of the NIMS observations permits an analysis of the scattering properties of the ring system even though the ring subtends only a small range of scattering angles. Our retrieved particle size distribution shows a decrease in the number of particles at larger radii although there is a reversal of this trend between 0.6 and 18 mu m. This distribution can be modeled as the combination of a power law with index p = 3.9 +/- 0.2 and a log-normal distribution of mean radius 4.5 mu m. Analysis shows that Voyager data lacked the required wavelength coverage and viewing geometry to determine the particle distribution uniquely. We conclude that the NIMS data set is a better determinant of the particle size distribution, especially for particles larger than a micrometer. We suggest that the power law distribution is the result of collisional processes that form grains less than 1 micrometer, in agreement with previous theory. We suggest that the log-normal distribution is characteristic of another, yet undetermined, process that dominates grain formation and evolution for particles several micrometers in size, (C) 2000 Academic Press. C1 CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP McMuldroch, S (reprint author), CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. NR 25 TC 9 Z9 9 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 2000 VL 146 IS 1 BP 1 EP 11 DI 10.1006/icar.2000.6343 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 329UU UT WOS:000087927500001 ER PT J AU Lissauer, JJ French, RG AF Lissauer, JJ French, RG TI HST high-resolution backscatter image of Saturn's G ring SO ICARUS LA English DT Article ID PLANE CROSSINGS; PARTICLES AB On 14 October 1996, we imaged Saturn's faint G ring with the Hubble Space Telescope's WFPC2 Planetary Camera. This is the highest resolution image of the G ring ever obtained in backscattered light, with an image scale of only 282 km per pixel. The 400-s exposure was taken using the F555W filter at a solar phase angle of alpha = 1.93 degrees and a ring tilt of B = -3.82 degrees as seen from Earth. The radial profile of the ring was derived from azimuthal averages of the ring brightness. It is highly asymmetric, with a sharp inner edge that is abrupt at the limit of our resolution, rising from 20 to 80% of maximum intensity over a distance of less than 700 km. Outward of its peak at r = 169,000 km, the G ring brightness gradually diminishes over several thousand kilometers. From a high SNR profile, averaged over ring longitudes within 25 degrees of the East (morning) ansa, the full-width at half-maximum intensity of the G ring is similar to 5200 km; higher resolution, lower SNR, profiles suggest a somewhat smaller ring width. The similarities between the radial structure seen from the HST in backscatter, and the highest resolution Voyager 1 and 2 profiles obtained in forward scattered light, imply that dust and macroscopic particles have similar distributions within the G ring. (C) 2000 Academic Press. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Wellesley Coll, Dept Astron, Wellesley, MA 02581 USA. RP Lissauer, JJ (reprint author), NASA, Ames Res Ctr, Div Space Sci, MS 245-3, Moffett Field, CA 94035 USA. NR 15 TC 8 Z9 8 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 2000 VL 146 IS 1 BP 12 EP 18 DI 10.1006/icar.2000.6386 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 329UU UT WOS:000087927500002 ER PT J AU Lynch, DK Mazuk, AL Russell, RW Hackwell, JA Hanner, MS AF Lynch, DK Mazuk, AL Russell, RW Hackwell, JA Hanner, MS TI 8- to 13-mu m spectra of Saturn's A and B rings SO ICARUS LA English DT Article DE Saturn; rings; infrared; spectra; particle properties ID PARTICLE-SIZE DISTRIBUTIONS; OCCULTATION; DUST AB Thermal IR spectroscopy of Saturn's A and B rings in the 8 to 13-mu m range reveals a smooth, Planck-like continuum with no spectral structure that could be attributed to optically thin water ice or silicate dust. The brightness temperatures of the A and B rings obtained by fitting a Planck function to the spectra were 90.3 +/- 0.9 and 90.5 +/- 0.6 K, respectively, in good agreement with and extending earlier photometric measurements. (C) 2000 Academic Press. C1 Aerospace Corp, Space Sci Applicat Lab, Los Angeles, CA 90009 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Lynch, DK (reprint author), Aerospace Corp, Space Sci Applicat Lab, POB 92957, Los Angeles, CA 90009 USA. NR 33 TC 7 Z9 7 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 2000 VL 146 IS 1 BP 43 EP 47 DI 10.1006/icar.2000.6372 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 329UU UT WOS:000087927500004 ER PT J AU Orton, GS Serabyn, E Lee, YT AF Orton, GS Serabyn, E Lee, YT TI Vertical distribution of PH3 in Saturn from observations of its 1-0 and 3-2 rotational lines SO ICARUS LA English DT Article DE atmospheres; composition; photochemistry; Saturn, atmosphere; spectroscopy ID VOYAGER INFRARED MEASUREMENTS; GIANT PLANETS; HIGH-RESOLUTION; ATMOSPHERE; PHOSPHINE; JUPITER; PHOTOCHEMISTRY; PARAMETERS; ABUNDANCE; HYDROGEN AB Far-infrared Fourier-transform spectrometer measurements of the 1-0 and 3-2 PH3 transitions in Saturn's disk near 267 and 800 GHz (8.9 and 26.7 cm(-1)), respectively, were analyzed simultaneously to derive a global mean profile for the PH3 vertical mixing ratio between 100 and 600 mbar total pressure, The far-infrared spectrum is relatively free from spectral interlopers, suffers minimal absorption or scattering by atmospheric particulates, and contains intrinsically weak PH3 lines that are sensitive to a range of atmospheric depths. The combined spectra are inconsistent with a uniform tropospheric mixing ratio, even with a stratospheric cutoff. They are consistent with a volume mixing ratio of PH3 that drops from 1.2 x 10(-5) at 645 mbar pressure to a value of 4.1 x 10(-7) at 150 mbar pressure, a decrease that is linear in log abundance vs log pressure, The mixing ratio could drop even more quickly at atmospheric pressures below 150 mbar and still be consistent with the data. The mixing ratio may well remain constant with depth for pressures above 630 mbar, The maximum PH3 mixing ratio in this model is consistent with a [P]/[H] ratio in the deep atmosphere that is about a factor of 10 higher than solar composition. Such a model is consistent with rapid mixing up to the radiative-convective boundary and transport by, for example, vertical waves just above this boundary, In the best fitting model, the eddy diffusion coefficient is similar to 10(4) cml near 630 mbar, and it must increase with altitude, The predominant PH3 loss mechanisms are direct photolysis by UV radiation and scavenging by H atoms produced by the photolysis. (C) 2000 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. RP Orton, GS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 169-237, Pasadena, CA 91109 USA. NR 61 TC 30 Z9 30 U1 0 U2 2 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 2000 VL 146 IS 1 BP 48 EP 59 DI 10.1006/icar.2000.6390 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 329UU UT WOS:000087927500005 ER PT J AU Buratti, BJ McConnochie, TH Calkins, SB Hillier, JK Herkenhoff, KE AF Buratti, BJ McConnochie, TH Calkins, SB Hillier, JK Herkenhoff, KE TI Lunar transient phenomena: What do the clementine images reveal? SO ICARUS LA English DT Article DE moon, surface; volcanism ID MOON AB Lunar Transient Phenomena (LTP) have been reported for at least 450 years. The events range from bright flashes, to reddish or bluish glows, to obscurations. Gaseous spectra and photometric measurements of the events have been obtained. Several theories have been offered as explanations for LTP, including residual volcanic activity or outgassing, bombardment by energetic particles, and piezoelectric effects. As the first set of digital multispectral images of the entire Moon, the Clementine data offer a unique opportunity to couple inferences of compositional relationships with lunar geomorphology in the regions of LTP. We have selected 11 regions from which numerous reliable historical reports of LTP exist. Our analysis of the Clementine multispectral images shows that many events occur in regions of bright, spectrally reddish deposits, which may be characteristic of volcanic ejecta. The events may be associated with outgassing of volatiles collected in or beneath mare basalt flows, We find that LTP tend to occur near the edges of maria, in agreement with a suggestion originally made by Cameron (1972, Icarus 16, 339-387), and in other regions of crustal weakness. We also find that some of the reported events tend to be in craters with rims of distinctly different (bluer) composition. This compositional difference may result from recent slumping of the rim, accompanied by the appearance of fresher underlying material. In some cases, slumping may be triggered by the release of pockets of volatiles; in turn the slumping events may cause additional pockets of trapped material to be released. There are four instances in which Clementine multispectral images were acquired both before and after an event that was reported by a terrestrial team of amateur astronomers mobilized to observe the Moon during the mapping phase of Clementine. None of these four sets of images shows clear changes that could be attributed to the reported LTP. (C) 2000 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. US Geol Survey, Flagstaff, AZ 86001 USA. RP Buratti, BJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 183-501, Pasadena, CA 91109 USA. NR 34 TC 8 Z9 8 U1 2 U2 3 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 2000 VL 146 IS 1 BP 98 EP 117 DI 10.1006/icar.2000.6373 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 329UU UT WOS:000087927500008 ER PT J AU Anicich, VG Milligan, DB Fairley, DA McEwan, MJ AF Anicich, VG Milligan, DB Fairley, DA McEwan, MJ TI Termolecular ion-molecule reactions in Titan's atmosphere, I - Principal ions with principal neutrals SO ICARUS LA English DT Article DE atmospheres; composition; ion-chemistry; ionospheres; Titan ID ASSOCIATION REACTIONS; LOW-PRESSURE; TEMPERATURE-DEPENDENCE; SYSTEM; VOYAGER-1; H3O+; RESONANCE; ABINITIO; NITROGEN; KINETICS AB The FA-SIFT experiment at Canterbury was used to determine some of the principal termolecular ion-molecule reactions that occur in the atmosphere of Titan, Saturn's satellite. The experiments were performed using both a pure nitrogen bath gas and a pure helium bath gas. The reactions of the ions N+, N-2(+), N-3(+), N-4(+), HCNH+, c-C3H3+ and H3O+ with molecular nitreogn were studied in a nitrogen bath gas at room temperature. Only two of these ions, N+ and N-2(+), were observed to react with N-2, forming N-3(+) and N-4(+), respectively. A second set of experiments was performed that measured the reactivity of ions in Titan's atmosphere that do not undergo rapid bimolecular reactions with other species. The reactions of these so-called "terminal" ions (HCNH+, c-C3H3+, and H3O+) with the trace neutral constituents of Titan (CH4, C2H2, and C2H4) were also examined using both helium and nitrogen as the bath gas. The only reactions observed to occur were the termolecular reactions of HCNH+ and H3O+ with C2H2 and C2H4. A third set of reactions was studied. These were the reactions of N+ and Ni with the 4 species CH4, C2H2, C2H4, HCN, and C4H8. All of the reactions in this third set have bimolecular ion-molecule kinetics, and they are compared in the text with the similar reactions of N+ and N-2(+) with these reagents. Finally, a projection is made using a model temperature and pressure profile of Titan's atmosphere to appraise the relative importance of N+ vs N-3(+) reactions and N-2(+) vs N-4(+) reactions. (C) 2000 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Canterbury, Dept Chem, Christchurch 4800, New Zealand. RP Anicich, VG (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 46 TC 20 Z9 20 U1 0 U2 3 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 2000 VL 146 IS 1 BP 118 EP 124 DI 10.1006/icar.2000.6353 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 329UU UT WOS:000087927500009 ER PT J AU Jarvis, KS Vilas, F Larson, SM Gaffey, MJ AF Jarvis, KS Vilas, F Larson, SM Gaffey, MJ TI Are Hyperion and Phoebe linked to Lapetus? SO ICARUS LA English DT Article DE satellites, irregular; Saturn, satellites; spectrophotometry; surfaces, satellites ID CCD REFLECTANCE SPECTRA; SOLAR-SYSTEM; TROJAN ASTEROIDS; ORGANIC-MATTER; DARK MATERIAL; WATER ICE; IAPETUS; SPECTROPHOTOMETRY; PHOTOMETRY; ORIGIN AB Narrowband reflectance spectra of the saturnian satellites S VII Hyperion and S LY Phoebe were obtained across the 0.4- to 0.8-mu m spectral region, The spectrum of Phoebe shows an absorption feature centered near 0.43 mu m superimposed on the UV/blue intervalence charge transfer transition present in the spectrum, similar to absorptions identified in the spectra of C-class asteroids (Vilas et al. 1993b. Icarus 105, 67-78), We use a linear mixing model to separate the reflectance spectrum of the dark material on Hyperion from the icy material. A distinct absorption feature centered at 0.67 mu m is present. A slight inflection suggesting an absorption feature near 0.4-0.6 mu m, and change in slope near 0.73 mu m suggesting the lower wavelength edge of an absorption, are also present. These absorptions are very similar to those identified in the spectrum of the dark material on the surface of Iapetus (Vilas et al, 1996. Icarus 124, 262-267), suggesting that the dark material on these two satellites is compositionally similar and has a similar origin. We attribute these absorption features to the (6)A(1) --> T-4(2)(G) and (6)A(1) --> T-4(1)(G) ferric charge transfer transitions in iron alteration minerals such as goethite and hematite that are products of the aqueous alteration of anhydrous silicates. (C) 2000 Academic Press. C1 Lockheed Martin Space Operat, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Rensselaer Polytech Inst, Dept Earth & Environm Sci, Ithaca, NY 14853 USA. RP Jarvis, KS (reprint author), Lockheed Martin Space Operat, 2400 NASA Rd 1,C-23, Houston, TX 77058 USA. NR 37 TC 31 Z9 31 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 2000 VL 146 IS 1 BP 125 EP 132 DI 10.1006/icar.2000.6371 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 329UU UT WOS:000087927500010 ER PT J AU Krasnopolsky, VA Mumma, MJ Abbott, MJ AF Krasnopolsky, VA Mumma, MJ Abbott, MJ TI EUVE search for X-rays from Comets Encke, Mueller (C/1993 A1), Borrelly, and Postperihelion Hale-Bopp SO ICARUS LA English DT Article ID EXTREME-ULTRAVIOLET EMISSION; DUST PARTICLES; O1; B2; HYAKUTAKE; RADIATION AB Our observation of postperihelion Hale-Bopp on November 17-23, 1997, revealed the comet soft X-ray luminosity of (3.7 +/- 1.2) x 10(24) photons s(-1) in an aperture of 6 x 10(5) km and in the EUVE range of 97-165 eV. We also analyzed observations of three comets from the EUVE archive. The X-ray luminosity of Comet Borrelly on November 20-22, 1994, was (7.5 +/- 0.6) x 10(24) photons s(-1) for the aperture of rho = 7 x 10(4) km. Upper limits of 2.7 x 10(23) and 1.4 x 10(24) photons s(-1) were obtained for Comets Encke and Mueller (C/1993 Al) on November 30, 1993, and June 9-11, 1994, for rho = 1.7 x 105 and 4.1 x 10(5) km, respectively. This work has doubled the number of comet observations in our EUVE database. Soft X-ray emissions have been detected in five of the eight observations. The measured X-ray luminocities are consistent with a r(3/2)Q(gas) dependence having the efficiency of (6.4 +/- 0.9) x 10(-5) AU(3/2) and therefore favors a gas-related mechanism. The only viable candidate is the charge transfer mechanism. Using our X-ray luminosities as functions of aperture and assuming the presentation of the charge transfer spectrum by thermal bremsstrahlung or the power law, it is possible to make careful comparison of X-ray observations made with different instruments. While both our pre- and postperihelion observations of Hale-Bopp demonstrate a regular behavior of X-rays from that comet, the outburst detected with the BeppoSAX and the nondetection with the ROSAT look puzzling. We suggest that the longterm EUVE observations reflect a mean X-ray emission while the comparatively short BeppoSAX and ROSAT observations of Comet Hale-Bopp could coincide with a maximum and a minimum in the heavy ion flux, respectively. (C) 2000 Aacademic Press. C1 Catholic Univ Amer, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Ctr Euv Astrophys, Berkeley, CA 94720 USA. RP Krasnopolsky, VA (reprint author), Catholic Univ Amer, Washington, DC 20064 USA. RI mumma, michael/I-2764-2013; Krasnopolsky, Vladimir/L-5085-2013 NR 33 TC 24 Z9 24 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 2000 VL 146 IS 1 BP 152 EP 160 DI 10.1006/icar.2000.6387 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 329UU UT WOS:000087927500012 ER PT J AU Pravec, P Sarounova, L Rabinowitz, DL Hicks, MD Wolf, M Krugly, YN Velichko, FP Shevchenko, VG Chiorny, VG Gaftonyuk, NM Genevier, G AF Pravec, P Sarounova, L Rabinowitz, DL Hicks, MD Wolf, M Krugly, YN Velichko, FP Shevchenko, VG Chiorny, VG Gaftonyuk, NM Genevier, G TI Two-period lightcurves of 1996 FG(3), 1998 PG, and (5407) 1992 AX: One probable and two possible binary asteroids SO ICARUS LA English DT Article DE binary asteroids; two-period lightcurves ID ROTATION; EVENTS AB We present the results of photometric observations of 1996 FG(3), 1998 PG, and (5407) 1992 AX. Each asteroid has a complex lightcurve that can be described as the coaddition of two independent components, one with a short synodic period P-1 of several hours, and another with a longer synodic period P-2. For 1996 FG(3), the shape of the long-period component strongly suggests a system of two bodies in bound orbits about their common center of mass, displaying both mutual eclipses and mutual occultations. We estimate the following parameters of the binary system: the primary's rotation period is P-1 = (3.5942 +/- 0.0002) h, the system's orbital period is P-2 = (16.135 +/- 0.005) h, the system's semimajor axis a = (1.7 +/- 0.3) d(p), the eccentricity is 0.05 +/- 0.05, and the secondary-to-primary diameter ratio d(s)/d(p) = 0.31 +/- 0.02. The measured color indices suggest that 1996 FG(3) belongs to the C taxonomic class; assuming the geometric albedo p = 0.06 typical for the class, we estimate the diameter of the primary d(p) = 1.4 km. For 1998 PG and (5407), the evidence for binary systems is less conclusive. However, assuming a binary model, we estimate that both systems have a secondary-to-primary diameter ratio d(s)/d(p) greater than or equal to 0.3. For 1998 PG, the primary and secondary rotation periods are P-1 = (2.51620 +/- 0.00003) h and 2P(2) = (14.007 +/- 0.0014) h, respectively. (If the secondary's rotation is tidally coupled to the orbital motion, the latter is also the system's orbital period.) For (5407), the primary's rotation period is P-1 = (2.54878 +/- 0.00007) h, and the orbital period is 2P(2) = (13.5196 +/- 0.0016) h. The color indices of 1998 PG are consistent with an S classification. Assuming p = 0.16, the primary's diameters are d(p) = 0.9 and 4.0 km for 1998 PG and (5407), respectively. The finding of the three objects doubles the known sample of probable/possible binary asteroids. The six known objects are so similar in some of their characteristics that we expect that most or all of them have been formed by the same mechanism, such as the tidal disruptions during close encounters with Earth proposed by Bottke and Melosh (Nature 281, 51, 1996), The population of binary asteroids among small, especially near-Earth, asteroids seems to be significant. Our new observations support an earlier estimate that 17% of NEAs are binary (uncertainty factor of 2). (C) 2000 Academic Press. C1 Acad Sci Czech Republ, Inst Astron, CZ-25165 Ondrejov, Czech Republic. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Charles Univ Prague, Astron Inst, CZ-18000 Prague, Czech Republic. Astron Observ, UA-310022 Kharkiv, Ukraine. Crimean Astrophys Observ, UA-334242 Crimea, Ukraine. Pasadena City Coll, Pasadena, CA 91106 USA. RP Pravec, P (reprint author), Acad Sci Czech Republ, Inst Astron, CZ-25165 Ondrejov, Czech Republic. RI Pravec, Petr/G-9037-2014; Shevchenko, Vasilij/H-1366-2011 OI Shevchenko, Vasilij/0000-0003-1000-223X NR 26 TC 43 Z9 43 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 2000 VL 146 IS 1 BP 190 EP 203 DI 10.1006/icar.2000.6375 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 329UU UT WOS:000087927500015 ER PT J AU Sromovsky, LA Spencer, JR Baines, KH Fry, PM AF Sromovsky, LA Spencer, JR Baines, KH Fry, PM TI Ground-based observations of cloud features on Uranus SO ICARUS LA English DT Article DE Uranus; Uranus atmosphere; infrared observations; data reduction techniques ID NEPTUNE AB NSFCAM observations at 1.7 mu m in 1998 and 1999 recorded the first discrete cloud features to appear in ground-based digital images of Uranus and the brightest such feature ever observed. The differential contributions of these northern hemisphere features to Uranus' disk-integrated brightness range from 0.8 +/- 0.2% and 0.11 +/- 0.3% for two 1998 features, to 4.9 +/- 0.7% for one 1999 feature, which is four times the value measured in 1998 NICMOS images at similar wavelengths. (C) 2000 Academic Press. C1 Univ Wisconsin, Ctr Space Sci & Engn, Madison, WI 53706 USA. Lowell Observ, Flagstaff, AZ 86001 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sromovsky, LA (reprint author), Univ Wisconsin, Ctr Space Sci & Engn, 1225 W Dayton St, Madison, WI 53706 USA. NR 16 TC 17 Z9 17 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 2000 VL 146 IS 1 BP 307 EP 311 DI 10.1006/icar.2000.6434 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 329UU UT WOS:000087927500026 ER PT J AU Ambrose, RO Aldridge, H Askew, RS Burridge, RR Bluethmann, W Diftler, M Lovchik, C Magruder, D Rehnmark, F AF Ambrose, RO Aldridge, H Askew, RS Burridge, RR Bluethmann, W Diftler, M Lovchik, C Magruder, D Rehnmark, F TI Robonaut: NASA's space humanoid SO IEEE INTELLIGENT SYSTEMS & THEIR APPLICATIONS LA English DT Article ID ROBOT C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. EM rambrose@ems.jsc.nasa.gov; hal.a.aldridge@jsc.nasa.gov; scott.askew@jsc.nasa.gov; bur-ridge@ieee.org; bluethmann@jsc.nasa.gov; diftler@jsc.nasa.gov; lovchik@jsc.nasa.gov; darby.f.magruder@jsc.nasa.gov; fredrik.rehnmark@jsc.nasa.gov NR 8 TC 132 Z9 137 U1 3 U2 12 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1094-7167 J9 IEEE INTELL SYST APP JI IEEE Intell. Syst. Appl. PD JUL-AUG PY 2000 VL 15 IS 4 BP 57 EP 62 DI 10.1109/5254.867913 PG 6 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 343AR UT WOS:000088680000011 ER PT J AU Saini, SS Hu, Y Johnson, FG Stone, DR Shen, H Zhou, W Pamulapati, J Ott, MN Shaw, HC Dagenais, M AF Saini, SS Hu, Y Johnson, FG Stone, DR Shen, H Zhou, W Pamulapati, J Ott, MN Shaw, HC Dagenais, M TI Lossless 1x2 optical switch monolithically integrated on a passive active resonant coupler (PARC) platform SO IEEE PHOTONICS TECHNOLOGY LETTERS LA English DT Article DE lossless splitters; monolithic integration; optical switch; photonic integrated circuits; resonant couplers; semiconductor optical amplifiers; splitters; twin waveguides ID WAVE-GUIDES; CIRCUITS; LASERS AB In this letter, we demonstrate a lossless 1 x 2 optical switch utilizing resonant vertical coupling between an active and a passive waveguide, Optical power is coupled into the passive waveguide and split into two ports using a 3-dB Y-junction splitter. The mode is then coupled up to a 1-mm-long active waveguide where gain is provided. A 100-mu m-long taper is utilized in each arm for coupling the mode from the passive to the active waveguide, Internal gain greater than 22 dB is obtained in each arm of the integrated splitter. High yield and good uniformity of devices are obtained over multiple processing runs. C1 Univ Maryland, Dept Elect & Comp Engn, College Pk, MD 20742 USA. Lab Phys Sci, College Pk, MD 20740 USA. USA, Res Lab, Adelphi, MD USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Saini, SS (reprint author), Univ Maryland, Dept Elect & Comp Engn, College Pk, MD 20742 USA. NR 8 TC 3 Z9 4 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 1041-1135 J9 IEEE PHOTONIC TECH L JI IEEE Photonics Technol. Lett. PD JUL PY 2000 VL 12 IS 7 BP 840 EP 842 DI 10.1109/68.853518 PG 3 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA 339YQ UT WOS:000088505800028 ER PT J AU Johnson, L AF Johnson, L TI The tether solution SO IEEE SPECTRUM LA English DT Article C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Johnson, L (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 2 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9235 J9 IEEE SPECTRUM JI IEEE Spectr. PD JUL PY 2000 VL 37 IS 7 BP 38 EP 43 DI 10.1109/6.852050 PG 6 WC Engineering, Electrical & Electronic SC Engineering GA 332FN UT WOS:000088063700010 ER PT J AU Clouse, DS AF Clouse, DS TI Small field-of-view star identification using Bayesian decision theory SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article ID ALGORITHM AB We describe a simple autonomous star identification algorithm which is effective using a narrow field of view (FOV) (2 deg), making the use of a science camera for star identification feasible. This work extends that of Padgett and Kreutz-Delgado [8] by setting decision thresholds using Bayesian decision theory. Our simulations show that when positional accuracy of imaged stars is 0.5 pixel (standard deviation) and the apparent brightness deviates by 0.8 unit stellar magnitude, the algorithm correctly identifies 96.0% of the sensor orientations, with less than a 0.3% rate of false positives. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif San Diego, La Jolla, CA 92093 USA. RP Clouse, DS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 21 Z9 24 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD JUL PY 2000 VL 36 IS 3 BP 773 EP 783 DI 10.1109/7.869495 PG 11 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 350TR UT WOS:000089117700004 ER PT J AU Drinkwater, M Lin, CC AF Drinkwater, M Lin, CC TI Introduction to the special section on emerging scatterometer applications SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Editorial Material C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. European Space Agcy, Earth Observat Future Programmes, NL-2200 AG Noordwijk, Netherlands. RP Drinkwater, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 4 Z9 4 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 2000 VL 38 IS 4 BP 1763 EP 1764 PN 2 PG 2 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 337TM UT WOS:000088377800001 ER PT J AU Bingham, AW Drinkwater, MR AF Bingham, AW Drinkwater, MR TI Recent changes in the microwave scattering properties of the Antarctic ice sheet SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE Antarctica; azimuthal anisotropy; backscatter climate change; emission; ice sheet; interannual change; radar; radiometer; scatterometer; seasonal change ID SAR BACKSCATTER SIGNATURES; APERTURE RADAR DATA; PENINSULA; SNOW; EMISSION; SHELVES AB Time series, satellite microwave data are used to monitor and quantify changes in the scattering properties of the Antarctic ice sheet. Daily ERS scatterometer (EScat) and Special Sensor Microwave/Imager (SSM/I) image data, acquired since 1992, are analyzed to understand the seasonal and interannual changes over the ice sheet. For regions of the ice sheet where azimuthal modulation is negligible, seasonal cycles are observed in both the EScat (amplitude similar to 0.5 dB) and SSM/I data (amplitude similar to 10 K) These cycles are attributed to seasonal changes in surface temperature. Interannual variability in the time series signatures appears to be associated with accumulation, There is also evidence to suggest that shifts in the wind direction can alter the backscatter through azimuthal modulation. Over the period 1992-97, large trends are observed in the EScat(< -0.3 dB yr(-1)) and SSM/I (>1 K yr(-1)) signatures over several regions in Antarctica. These changes typically occur over ice shelves and at the margins of the ice sheet where previous melt events have occurred, and where accumulation is relatively high (>300 mm yr(-1)). It is likely the large changes result from the successive burial of an efficient scattering layer formed by refreezing after a melt event prior to 1992, There is also evidence to suggest that similarly large changes can be observed in the interior of the ice sheet due to the burial of depth hear layers. In order to monitor long term change in the properties of the Antarctic ice sheet, it is necessary to remove the seasonal cycle from time series microwave data. Such anomaly data can then be used to understand the link between EScat and SSM/I with accumulation and wind shifts. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bingham, AW (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Drinkwater, Mark/C-2478-2011 OI Drinkwater, Mark/0000-0002-9250-3806 NR 40 TC 42 Z9 42 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 JUL PY 2000 VL 38 IS 4 BP 1810 EP 1820 DI 10.1109/36.851765 PN 2 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 337TM UT WOS:000088377800007 ER PT J AU Drinkwater, MR Liu, X AF Drinkwater, MR Liu, X TI Seasonal to interannual variability in Antarctic sea-ice surface melt SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE Antarctic sea ice; austral summer; ERS; interannual variability; melt onset; melt pond; microwave; NSCAT; radar; radiometer; SSM/I; SAR; scatterometer; seasonal variability ID WINTER SNOW COVER; WEDDELL SEA; RADAR AB Satellite remote sensing time series images are used to illustrate the spatial and temporal variability in Antarctic-wide sea-ice surface melting during the austral summer. Combinations of collocated data from the Active Microwave Instrument onboard the ERS-1/2 spacecraft, RadarSat synthetic aperture radar (SAR), and special sensor microwave/imager (SSM/I) passive microwave radiometer are used in characterizing the effects of surface melting on measured values of the normalized backscatter cross-section and brightness temperature, respectively. An algorithm is developed from observed signatures to map interannual variations in the summer season melt onset and the cumulative number of melt days throughout each austral summer from 1992 to 1998, Results indicate that Antarctic sea-ice surface melting is sparse and relatively short-lived, in contrast to the protracted Arctic summer melt season. Regions consistently experiencing melt periods of 15 days or longer duration are focused around the Antarctic Peninsula, primarily in the northwest Weddell and Bellingshausen Seas. C1 European Space Agcy, European Space Res & Technol Ctr, NL-2200 AG Noordwijk, Netherlands. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Drinkwater, MR (reprint author), European Space Agcy, European Space Res & Technol Ctr, NL-2200 AG Noordwijk, Netherlands. OI Drinkwater, Mark/0000-0002-9250-3806 NR 42 TC 23 Z9 25 U1 3 U2 6 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 JUL PY 2000 VL 38 IS 4 BP 1827 EP 1842 DI 10.1109/36.851767 PN 2 PG 16 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 337TM UT WOS:000088377800009 ER PT J AU Remund, QP Long, DG Drinkwater, MR AF Remund, QP Long, DG Drinkwater, MR TI An iterative approach to multisensor sea ice classification SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE maximum a posteriori classification; maximum likelihood classification; radiometer; sea ice; sea ice classification; scatterometer ID APERTURE RADAR DATA; RESOLUTION ENHANCEMENT; SCATTEROMETER DATA; EXTENT; OCEAN; SNOW AB Characterizing the variability in sea ice in the polar regions is fundamental to an understanding of global climate and the geophysical processes governing climate changes. Sea ice can be grouped into a number of general classes with different characteristics. Multisensor data from NSCAT, ERS-2 and SSM/I are reconstructed into enhanced resolution imagery for use in ice-type classification. The resulting twelve dimensional data set is linearly transformed through principal component analysis to reduce data dimensionality and noise levels. An iterative statistical data segmentation algorithm is developed using maximum likelihood (ML) and maximum a posteriori (MAP) techniques. For a given ice type, the conditional probability distributions of observed vectors are assumed to be Gaussian. The cluster centroids, covariance matrices, and a priori distributions are estimated from the classification of a previous temporal image set. An initial classification is produced using centroid training data and a weighted nearest-neighbor classifier. Though validation is limited, the algorithm results in an ice classification that is judged to be superior to a conventional k-means approach. C1 Brigham Young Univ, Microwave Earth Remote Sensing Lab, Provo, UT 84602 USA. CALTECH, Jet Prop Lab, Polar Oceanog Grp, Pasadena, CA 91125 USA. RP Remund, QP (reprint author), Brigham Young Univ, Microwave Earth Remote Sensing Lab, Provo, UT 84602 USA. RI Drinkwater, Mark/C-2478-2011; Long, David/K-4908-2015 OI Drinkwater, Mark/0000-0002-9250-3806; Long, David/0000-0002-1852-3972 NR 28 TC 18 Z9 20 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 JUL PY 2000 VL 38 IS 4 BP 1843 EP 1856 DI 10.1109/36.851768 PN 2 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 337TM UT WOS:000088377800010 ER PT J AU Long, DG Drinkwater, MR AF Long, DG Drinkwater, MR TI Azimuth variation in microwave scatterometer and radiometer data over Antarctica SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE azimuthal anisotropy; backscattering; emissitivity; ice sheet; radar; radiometer; sastrugi; scatterometer; surface roughness ID KATABATIC-WIND INTENSITY; GREENLAND ICE-SHEET; OCEAN SEA-ICE; RESOLUTION ENHANCEMENT; SSM/I INSTRUMENT; CALIBRATION; SATELLITE; DIRECTION; RADAR AB While designed for ocean observation, scatterometer and radiometer data have proven very useful in a variety of cryosphere studies. Over large regions of Antarctica, ice sheet and bedrock topography and the snow deposition, drift, and erosional environment combine to produce roughness on various scales, Roughness ranges from broad, basin-scale ice-sheet topography at similar to 100 km wavelengths to large, spatially coherent dune fields at similar to 10 km wavelength to erosional features on the meter scale known as sastrugi, These roughness scales influence the microwave backscattering and emission properties of the surface, combining to introduce azimuth-angle dependencies in the satellite observation data. In this paper, we explore the use of NASA scatterometer (NSCAT) data, European remote sensing (ERS) advanced microwave instrument (AMI) scatterometer mode data, and special sensor microwave/imager (SSM/I) data to study surface roughness effects in Antarctica. All three sensors provide strong evidence of azimuth modulation, which is correlated with the surface slope environment and results in a katabatic wind flow regime. Due to its broad azimuth coverage, NSCAT data appears to be the best suited for azimuth-angle observations. A simple empirical model for the azimuth variation in the radar backscatter is developed, and an algorithm for computing the parameters of the model from NSCAT data at a fine scale is presented, Results indicate relationships exist between the azimuthal variation of the data and the orientation of the surface slope and small-scale roughness relative to the sensor-look direction. C1 Brigham Young Univ, Dept Elect & Comp Engn, Provo, UT 84602 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Long, DG (reprint author), Brigham Young Univ, Dept Elect & Comp Engn, Provo, UT 84602 USA. RI Drinkwater, Mark/C-2478-2011; Long, David/K-4908-2015 OI Drinkwater, Mark/0000-0002-9250-3806; Long, David/0000-0002-1852-3972 NR 44 TC 56 Z9 57 U1 0 U2 9 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 2000 VL 38 IS 4 BP 1857 EP 1870 DI 10.1109/36.851769 PN 2 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 337TM UT WOS:000088377800011 ER PT J AU Tsai, WY Nghiem, SV Huddleston, JN Spencer, MW Stiles, BW West, RD AF Tsai, WY Nghiem, SV Huddleston, JN Spencer, MW Stiles, BW West, RD TI Polarimetric scatterometry: A promising technique for improving ocean surface wind measurements from space SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE polarimetric; ocean winds; SeaWinds; spaceborne scatterometer ID A SATELLITE SCATTEROMETER; RADAR CROSS-SECTION; MODEL FUNCTION; BACKSCATTER; SEASAT; NSCAT; SCATTERING; SYMMETRY; WAVES; BAND AB Spaceborne wind scatterometers provide useful measurements of ocean surface winds and are important to climatological studies and operational weather forecasting. Past and currently planned scatterometers use measurements of the copolarized backscatter cross-section at different azimuth angles to infer ocean surface wind speed and direction. Although successful, current scatterometer designs have limitations such as degraded wind performance in the near-nadir and outer regions of the measurement swath and a reliance on external wind information for vector ambiguity, removal, Theoretical studies of scattering from the mind-induced ocean surface indicate that polarimetric measurements provide orthogonal and complementary directional information to aid the wind retrieval process. In this paper, potential benefits of making polarimetric backscatter measurements to improve wind retrieval performance are addressed, To investigate the performance of a polarimetric scatterometer, a modified version of the SeaWinds end-to-end simulator at the Jet Propulsion Laboratory (JPL), Pasadena, CA, is employed, To model the effect of realistic measurement errors, expressions for polarimetric measurement variance and bias are derived. It is shown that a polarimetric scatterometer can be realized with straightforward and inexpensive modifications to a current scanning pencil-beam scatterometer system such as SeaWinds, Simulation results show that such a system can improve wind performance in the nadir region and eliminate the reliance on external wind information. The mechanism by which the addition of polarimetric measurements improves wind vector retrieval is discussed in detail. Field experiments are suggested to better characterize the polarimetric scattering properties of the wind-modulated ocean surface for future applications to wind scatterometry. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Tsai, WY (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 35 TC 38 Z9 42 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 2000 VL 38 IS 4 BP 1903 EP 1921 DI 10.1109/36.851773 PN 2 PG 19 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 337TM UT WOS:000088377800015 ER PT J AU Gamba, P Houshmand, B AF Gamba, P Houshmand, B TI Digital surface models and building extraction: A comparison of IFSAR and LIDAR data SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article AB In this paper, the task of extracting significant built structure in digital surface models (DSM) is analyzed. The original data are obtained by means of interferometric SAR or LIDAR techniques and have different resolution and noise characteristics. This work aims to make a comparison of what (and how precisely) it is possible to detect and extract starting from these models, taking into account their differences but applying to them the same planar approximation approach. To this aim, data over Los Angeles and Denver is considered and evaluated, The results show that LIDAR data provide a better shape characterization of each building, and not simply because of their higher resolution. Indeed, less accurate results obtained starting from radar data are mainly due to shadowing/layover effects, which can be only partially corrected by means of the segmentation procedures. However, better results than those already presented in the literature could be achieved by using the IFSAR data correlation map. C1 Univ Pavia, Dipartimento Elettr, I-27100 Pavia, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gamba, P (reprint author), Univ Pavia, Dipartimento Elettr, I-27100 Pavia, Italy. RI Gamba, Paolo/G-1959-2010 OI Gamba, Paolo/0000-0002-9576-6337 NR 25 TC 50 Z9 54 U1 1 U2 13 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 JUL PY 2000 VL 38 IS 4 BP 1959 EP 1968 DI 10.1109/36.851777 PN 2 PG 10 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 337TM UT WOS:000088377800019 ER PT J AU Hofton, MA Minster, JB Blair, JB AF Hofton, MA Minster, JB Blair, JB TI Decomposition of laser altimeter waveforms SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE data processing; Gaussian decomposition; laser altimetry; surface-finding ID TOPOGRAPHY AB We develop a method to decompose a laser altimeter return waveform into a series of components assuming that the position of each component within the waveform can be used to calculate the mean elevation of a specific reflecting surface within the laser footprint. For simplicity, we assume each component is Gaussian in nature. We estimate the number of Gaussian components from the number of inflection points of a smoothed copy of the laser waveform and obtain initial estimates of the Gaussian half-widths and positions from the positions of its consecutive inflection points, Initial amplitude estimates are obtained using a nonnegative least-squares method (LSM), To reduce the likelihood of fitting the background noise within the waveform and to minimize the number of Gaussians needed in the approximation, we rank the "importance" of each Gaussian in the decomposition using its initial half-width and amplitude estimates. The initial parameter estimates of all Gaussians ranked "important" are optimized using the Levenburg-Marquardt method, If the sum of the Gaussians does not approximate the return waveform to a prescribed accuracy, then additional Gaussians can be included in the optimization procedure or initial parameters can be recalculated. The Gaussian decomposition method is demonstrated on data collected by the airborne laser vegetation imaging sensor (LVIS) in October 1997 over the Sequoia National Forest, California. C1 Univ Maryland, Dept Geog, College Pk, MD 20742 USA. Univ Calif San Diego, Scripps Inst Oceanog, Inst Geophys & Planetary Phys, La Jolla, CA 92093 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Hofton, MA (reprint author), Univ Maryland, Dept Geog, College Pk, MD 20742 USA. RI Blair, James/D-3881-2013; Beckley, Matthew/D-4547-2013; OI Minster, Jean Bernard/0000-0003-1268-5177 NR 12 TC 133 Z9 155 U1 4 U2 17 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 JUL PY 2000 VL 38 IS 4 BP 1989 EP 1996 DI 10.1109/36.851780 PN 2 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 337TM UT WOS:000088377800022 ER PT J AU Roy, DP AF Roy, DP TI The impact of misregistration upon composited wide field of view satellite data and implications for change detection SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE change detection; compositing; misregistration ID HIGH-RESOLUTION RADIOMETER; AVHRR DATA; NOAA AVHRR; DATA SET; GEOMETRIC CORRECTION; SPATIAL-RESOLUTION; LAND; COVER; REFLECTANCE; IMAGERY AB Composited wide field of view satellite data are used for many applications and increasingly for studies of global change, Although several compositing schemes have been suggested, all assume perfect geometric registration, which is not operationally feasible. In this study, models of the satellite imaging, geometric registration, and compositing processes are used to investigate the impact of misregistration upon the position of high contrast edges found in composited satellite data. Simulations are performed with respect to the compositing of advanced very high resolution radiometer (AVHRR) and moderate resolution imaging spectroradiometer (MODIS) data. Contrast edges are found to be systematically shifted in maximum and minimum value composites. The degree of shifting increases with the number of orbits that are composited, the degree of misregistration and the view zenith angle. The implications of these findings upon the utility of composited satellite data for change detection are discussed. The shifts may systematically bias estimates of location and area when composited data are used. They may also cause small and/or fragmented features, which are evident in individual orbits to disappear in composited data, precluding the ability to map such features or to detect their occurrence: under a change detection scheme. C1 Univ Maryland, Dept Geog, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Roy, DP (reprint author), Univ Maryland, Dept Geog, College Pk, MD 20742 USA. NR 52 TC 87 Z9 89 U1 3 U2 10 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 2000 VL 38 IS 4 BP 2017 EP 2032 DI 10.1109/36.851783 PN 2 PG 16 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 337TM UT WOS:000088377800025 ER PT J AU Mansour, RR Ye, S Jolley, B Thomson, G Peik, SF Romano, T Tang, WC Kudsia, CM Nast, T Williams, B Frank, D Enlow, D Silverman, G Soroga, J Wilker, C Warner, J Khanna, S Seguin, G Brassard, G AF Mansour, RR Ye, S Jolley, B Thomson, G Peik, SF Romano, T Tang, WC Kudsia, CM Nast, T Williams, B Frank, D Enlow, D Silverman, G Soroga, J Wilker, C Warner, J Khanna, S Seguin, G Brassard, G TI A 60-channel superconductive input multiplexer integrated with pulse-tube cryocoolers SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article DE channel bank filters; cryogenics; high-temperature superconductors; satellite applications; superconductive filters AB This paper presents the measured results of a C-band 60-channel superconductive input multiplexer integrated with pulse-tube space-qualified cryocoolers. The multiplexer is developed to duplicate the requirements of the INTELSAT 8 program. The channel filters are self-equalized ten-pole high-temperature superconductor (HTS) planar structures designed with drop-in cryogenic ferrite circulators and isolators. This paper presents details on RF design, packaging, and cryocooler integration, as well as an assessment of overall reliability of using HTS equipment in a space environment. This paper demonstrates that at least 50% reduction in mass and 65% reduction in size can be achieved by replacing the INTELSAT 8 C-band dielectric-resonator input multiplexer with a superconductive multiplexer. C1 COM DEV Ltd, Corp Res & Dev Dept, Cambridge, ON N1R 7H6, Canada. Lockheed Martin Corp, Palo Alto, CA 94304 USA. DuPont, Wilmington, DE 19880 USA. NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. Canadian Dept Natl Def, Ottawa, ON K1A 0K2, Canada. Canadian Space Agcy, St Hubert, PQ J3Y 8Y9, Canada. RP Mansour, RR (reprint author), Univ Waterloo, Elect Comp Engn Dept, Waterloo, ON N2L 3G1, Canada. NR 9 TC 15 Z9 18 U1 0 U2 6 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 JUL PY 2000 VL 48 IS 7 BP 1171 EP 1180 DI 10.1109/22.853457 PN 2 PG 10 WC Engineering, Electrical & Electronic SC Engineering GA 334WR UT WOS:000088209100002 ER PT J AU Miranda, FA Subramanyam, G Van Keuls, FW Romanofsky, RR Warner, JD Mueller, CH AF Miranda, FA Subramanyam, G Van Keuls, FW Romanofsky, RR Warner, JD Mueller, CH TI Design and development of ferroelectric tunable microwave components for Ku- and K-band satellite communication systems SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article DE ferroelectric; high-temperature superconducting; K-band; Ku-band; microwave; tunable ID THIN-FILM; RESONATORS AB Integration of a high-temperature superconductor with a nonlinear dielectric ferroelectric such as strontium titanate, i.e., SrTiO3 (STO), has created a new class of electrically tunable low-loss microwave components. We have designed and fabricated frequency and phase agile components using a conductor/ferroelectric/dielectric two-layered microstrip configuration. Some examples of these components are: microstrip ring resonators, local oscillators, edge coupled filters, and phase-shifter circuits. These structures have been fabricated using YBa2Cu3O7-delta or gold conductor-based microstrip lines fabricated on lanthanum aluminate (LaAlO3) or magnesium oxide (MgO) substrates coated with an STO thin film. Frequency and phase agility are achieved using the nonlinear de electric-field dependence of the relative dielectric constant of STO ferroelectric thin film (is an element of(rSTO)) In this paper, we will present an assessment of the progress that our group has achieved thus far toward integration of this technology into wireless and satellite communication systems. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Univ Dayton, Dept Elect & Comp Engn, Dayton, OH 45469 USA. RP Miranda, FA (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 25 TC 99 Z9 100 U1 1 U2 12 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 JUL PY 2000 VL 48 IS 7 BP 1181 EP 1189 DI 10.1109/22.853458 PN 2 PG 9 WC Engineering, Electrical & Electronic SC Engineering GA 334WR UT WOS:000088209100003 ER PT J AU Romanofsky, RR Warner, JD Alterovitz, SA Covey, L Smith, A Newman, P Duh, KG AF Romanofsky, RR Warner, JD Alterovitz, SA Covey, L Smith, A Newman, P Duh, KG TI A cryogenic K-band ground terminal for NASA'S direct-data-distribution space experiment SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article DE cryogenic electronics; receiving antennas; superconducting filters; MMIC amplifiers ID RECEIVER AB A K-band receiver terminal has been designed for approximate to 77-K operation to support the NASA Glenn Research Center's direct-data-distribution (D-3) space experiment. The D-3 experiment involves a 256-element phased-array antenna, aboard the space shuttle, transmitting dual 622-Mb/s beams to the ground terminal. The beams are left- and right-hand-side circularly polarized for isolation. The terminal consists of a Cassegrain reflector antenna with a corrugated feed horn, a six-pole YBa2Cu3O7-delta microstrip bandpass filter, a three-stage InP high electron-mobility transistor monolithic-microwave integrated-circuit amplifier, and a 1-W at 80-K Stirling cycle cryocooler. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Cleveland State Univ, Dept Elect & Comp Engn, Cleveland, OH 44101 USA. Zin Technol, Cleveland, OH 44192 USA. Sanders, Adv Microwave Elect Dept, Nashua, NH 03061 USA. RP Romanofsky, RR (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 8 TC 11 Z9 11 U1 1 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUL PY 2000 VL 48 IS 7 BP 1216 EP 1220 DI 10.1109/22.853464 PN 2 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA 334WR UT WOS:000088209100007 ER PT J AU Young, RB Bridge, KY Vaughn, JR AF Young, RB Bridge, KY Vaughn, JR TI beta-adrenergic receptor population is up-regulated by increased cyclic adenosine monophosphate concentration in chicken skeletal muscle cells in culture SO IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY-ANIMAL LA English DT Article DE adrenergic receptor; cyclic AMP; myoblast; cell culture ID RAT VENTRICULAR MYOCYTES; DEPENDENT PROTEIN-KINASE; MESSENGER-RNA; BETA(1)-ADRENERGIC RECEPTOR; ADENYLATE-CYCLASE; C-FOS; AGONISTS; EXPRESSION; DIFFERENTIATION; PHOSPHORYLATION AB Skeletal muscle hypertrophy is promoted in vivo by administration of beta-adrenergic receptor (beta AR) agonists. Chicken skeletal muscle cells were treated with 1 mu M isoproterenol, a strong beta AR agonist, between days 7 and 10 in culture. beta AR population increased by approximately 40% during this treatment; however, the ability of the cells to synthesize cyclic adenosine monophosphate (cAMP) was diminished by twofold. Neither the basal concentration of cAMP nor the quantity of myosin heavy chain (MHC) was affected by the 3-d exposure to isoproterenol. To understand further the relationship between intracellular cAMP levels, beta AR population, and muscle protein accumulation, intracellular cAMP levels were artificially elevated by treatment with 0-10 mu M forskolin for 3 d. The basal concentration of cAMP in forskolin-treated cells increased up to sevenfold in a dose-dependent manner. increasing concentrations of forskolin also led to an increase in beta AR population, with a maximum increase of approximately 40-60% at 10 mu M forskolin. A maximum increase of 40-50% in the quantity of MHC was observed at 0.2 mu M forskolin, but higher concentrations of forskolin reduced the quantity of MHC back to control levels. At 0.2 mu M forskolin, intracellular levels of cAMP were higher by approximately 35%, and the beta AR population was higher by approximately 30%. Neither the number of muscle nuclei fused into myotubes nor the percentage of nuclei in myotubes was affected by forskolin at any of the concentrations studied. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Young, RB (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 43 TC 2 Z9 2 U1 0 U2 0 PU SOC IN VITRO BIOLOGY PI LARGO PA 9315 LARGO DR WEST, STE 25, LARGO, MD 20774 USA SN 1071-2690 J9 IN VITRO CELL DEV-AN JI In Vitro Cell. Dev. Biol.-Anim. PD JUL-AUG PY 2000 VL 36 IS 7 BP 485 EP 492 PG 8 WC Cell Biology; Developmental Biology SC Cell Biology; Developmental Biology GA 362UD UT WOS:000089795900007 ER PT J AU Kawata, T Gotoh, E Durante, M Wu, H George, K Furusawa, Y Cucinotta, FA AF Kawata, T Gotoh, E Durante, M Wu, H George, K Furusawa, Y Cucinotta, FA TI High-LET radiation-induced aberrations in prematurely condensed G2 chromosomes of human fibroblasts SO INTERNATIONAL JOURNAL OF RADIATION BIOLOGY LA English DT Article ID DOUBLE-STRAND BREAKS; HUMAN INTERPHASE CHROMOSOMES; IN-SITU HYBRIDIZATION; INDUCED CHROMATIN BREAKS; PU-238 ALPHA-PARTICLES; MAMMALIAN-CELLS; HEAVY-IONS; HYPERTONIC TREATMENT; GAMMA-IRRADIATION; 10T1/2 CELLS AB Purpose: To determine the number of initial chromatid breaks induced by low- or high-LET irradiations, and to compare the kinetics of chromatid break rejoining for radiations of different quality. Material and methods: Exponentially growing human fibroblast cells AG1522 were radiated with gamma-rays, energetic carbon (290 MeV/u), silicon (490 MeV/u) and iron (200 and 600 MeV/u). Chromosomes were prematurely condensed using calyculin A. Chromatid breaks and exchanges in G2 cells were scored. PCC were collected after several post-irradiation incubation times, ranging from 5 to 600 min. Results: The kinetics of chromatid break rejoining following low- or high-LET irradiation consisted of two exponential components representing a rapid and a slow time constant. Chromatid breaks decreased rapidly during the first 10 min after exposure, then continued to decrease at a slower rate. The rejoining kinetics were similar for exposure to each type of radiation. Chromatid exchanges were also formed quickly. Compared to low-LET radiation, isochromatid breaks were produced more frequently and the proportion of unrejoined breaks was higher for high-LET radiation. Conclusions: Compared with gamma-rays, isochromatid breaks were observed more frequently in high-LET irradiated samples, suggesting that an increase in isochromatid breaks is a signature of high-LET radiation exposure. C1 NASA, Lyndon B Johnson Space Ctr, Radiat Biophys, Houston, TX 77058 USA. Natl Inst Infect Dis, Div Genet Resources, Tokyo, Japan. Univ Naples Federico II, Dept Phys, Naples, Italy. NASA, Lyndon B Johnson Space Ctr, Kelsey Selbold Clin, Houston, TX 77058 USA. Wyle Labs, Houston, TX USA. Natl Inst Radiol Sci, Inst Space Radiat Lab, Chiba 260, Japan. RP Kawata, T (reprint author), NASA, Lyndon B Johnson Space Ctr, Radiat Biophys, Mail Code SN, Houston, TX 77058 USA. RI Durante, Marco/K-1315-2014; OI Durante, Marco/0000-0002-4615-553X NR 44 TC 34 Z9 43 U1 0 U2 3 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0955-3002 J9 INT J RADIAT BIOL JI Int. J. Radiat. Biol. PD JUL PY 2000 VL 76 IS 7 BP 929 EP 937 PG 9 WC Biology; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging GA 335PG UT WOS:000088251400006 PM 10923617 ER PT J AU Barut, A Madenci, E Tessler, A AF Barut, A Madenci, E Tessler, A TI Nonlinear thermoelastic analysis of composite panels under non-uniform temperature distribution SO INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES LA English DT Article ID THERMAL POSTBUCKLING ANALYSIS; CURVED PANELS; EDGE SHEAR; PLATES; ELEMENT; FLAT AB The response of moderately thick laminated panels experiencing large displacements and rotations under nonuniform thermal loading is investigated through a nonlinear finite element analysis. The present nonlinear thermoelastic analysis incorporates an anisoparametric, doubly curved, shallow shell element that is free of the 'locking' phenomenon. The effects of large displacements and rotations, transverse shear deformations, the coupling between stretching and bending due to shallow geometry, and Duhamel-Neumann-type thermoelastic material anisotropy are included in the element formulation. The equations of equilibrium are derived from the virtual work principle, along with the co-rotational form of the total Lagrangian formulation. A non-uniform temperature field across the shell surface is approximated by piecewise-uniform temperature distributions over individual elements. In the thickness direction, the temperature distribution is approximated linearly. Accuracy of the present analysis is established by comparison with benchmark solutions. The numerical results are presented for various configurations, including cutouts under uniform and non-uniform temperatures. The numerical results demonstrate that the present finite element analysis is computationally robust and efficient. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Arizona, Dept Aerosp & Mech Engn, Tucson, AZ 85721 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Univ Arizona, Dept Aerosp & Mech Engn, Aero Bldg 16, Tucson, AZ 85721 USA. EM madenci@aue.arizona.edu RI Tessler, Alexander/A-4729-2009 NR 50 TC 21 Z9 21 U1 1 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0020-7683 EI 1879-2146 J9 INT J SOLIDS STRUCT JI Int. J. Solids Struct. PD JUL PY 2000 VL 37 IS 27 BP 3681 EP 3713 DI 10.1016/S0020-7683(99)00119-5 PG 33 WC Mechanics SC Mechanics GA 307CU UT WOS:000086636500003 ER PT J AU Hu, BL Phillip, NG AF Hu, BL Phillip, NG TI Fluctuations of energy density and validity of semiclassical gravity SO INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS LA English DT Article ID WEAKLY INHOMOGENEOUS COSMOLOGIES; EINSTEIN-LANGEVIN EQUATION; EARLY UNIVERSE; QUANTUM-FIELDS; BACK-REACTION; PARTICLE-PRODUCTION; EXPECTATION VALUE; CURVED SPACETIME; POINT-SEPARATION; TRACE ANOMALIES AB From calculations of the variance, or the fluctuations, and the mean energy density of a massless scalar field in the Minkowski vacuum as a function of an intrinsic scale defined by the world function between two nearby points (as used in point separation regularization), we show that, contrary to prior claims, the ratio of variance to its mean squared being of the order unity does nor imply a failure of semiclassical gravity. It is more a consequence of the quantum nature of the stale of the matter field than any inadequacy of the theory of spacetime with quantum matter as source. C1 Univ Maryland, Dept Phys, College Pk, MD 20742 USA. Raytheon ITSS, Astron & Solar Phys Lab, NASA, GSFC, Greenbelt, MD 20771 USA. RP Hu, BL (reprint author), Univ Maryland, Dept Phys, College Pk, MD 20742 USA. NR 60 TC 25 Z9 25 U1 0 U2 0 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0020-7748 J9 INT J THEOR PHYS JI Int. J. Theor. Phys. PD JUL PY 2000 VL 39 IS 7 BP 1817 EP 1830 DI 10.1023/A:1003689630751 PG 14 WC Physics, Multidisciplinary SC Physics GA 367BX UT WOS:000090042700007 ER PT J AU Jiang, S Horn, TJ Dhir, VK AF Jiang, S Horn, TJ Dhir, VK TI Numerical analysis of a radiant heat flux calibration system SO INTERNATIONAL JOURNAL OF THERMOPHYSICS LA English DT Article DE calibration; copper substrate; foil gauge; graphite plate; heat flux gauge AB Heat flux gauges are one of the devices that are used to determine the heat loads to which high-speed aerospace structures are subjected during flight. Prior to installation, these gauges are calibrated. The calibration system must be well understood if the heat flux gauges are to provide useful data during night tests. A pseudo three-dimensional model of the radiant heal flux gauge calibration system was developed. The radiant heat nux gauge calibration system consists of a graphite plate heater and a circular foil heat flux gauge. The numerical model simulates the combined convection, radiation, and mass loss by chemical reaction on the graphite plate surface. It can be used to identify errors due to heater element erosion, and the deviations in the predicted heat fluxes due to uncertainties in various physical parameters of the system. A fourth-order finite difference scheme is used to solve the steady-state governing equations and to determine the temperature distribution in the gauge and the graphite plate, the incident heat flux on the gauge face, and the fiat plate erosion. Initial gauge heal nux predictions from the model are found to be within +/-5% of experimental results. C1 Univ Calif Los Angeles, Dept Mech & Aerosp Engn, Los Angeles, CA 90095 USA. NASA, Dryden Flight Res Ctr, Edwards, CA 93523 USA. RP Dhir, VK (reprint author), Univ Calif Los Angeles, Dept Mech & Aerosp Engn, Los Angeles, CA 90095 USA. NR 7 TC 1 Z9 1 U1 1 U2 2 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0195-928X J9 INT J THERMOPHYS JI Int. J. Thermophys. PD JUL PY 2000 VL 21 IS 4 BP 941 EP 963 DI 10.1023/A:1006622526578 PG 23 WC Thermodynamics; Chemistry, Physical; Mechanics; Physics, Applied SC Thermodynamics; Chemistry; Mechanics; Physics GA 362EP UT WOS:000089765900010 ER PT J AU Hartley, FT AF Hartley, FT TI Miniature peristaltic pump technology and applications SO JOURNAL OF ADVANCED MATERIALS LA English DT Article AB The Jet Propulsion Laboratory, (JPL) is a NASA Ferderally Funded Research and Development Center (FFRDC). It is endowed with NASA equipment that is managed and staffed by California Institute of Technology with a highly educated and world-class community of six thousand engineers and scientists. JPL's principal NASA responsibility, is to design, build, test and operate robotic spacecraft for the exploration of the solar system and to observe our universe across the whole EMR spectrum. Essentially: to go where no one has gone before and in doing so, determine the origins of our solar system and the universe. The days of large, multi-instrumented, billion-dollar robotic spacecraft are over. The emphasis is now on miniaturizing instruments and spacecraft and reducing the costs of fabrication, test, launch and operation. The ramifications of miniaturization are global, encompassing every element of a spacecraft, instrument, lander or penetrator Micro pumps, valves and flow meters were conceived to address the variety of fluid flow control elements. This paper discusses the evolution of this technology,from other MEMS programs and presents a variety of 'space' applications. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hartley, FT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 3 Z9 4 U1 1 U2 8 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 USA SN 1070-9789 J9 J ADV MATER JI J. Adv. Mater. PD JUL PY 2000 VL 32 IS 3 BP 16 EP 22 PG 7 WC Materials Science, Multidisciplinary SC Materials Science GA 333TX UT WOS:000088147800003 ER PT J AU Borrmann, S Luo, BP Mishchenko, M AF Borrmann, S Luo, BP Mishchenko, M TI Application of the T-matrix method to the measurement of aspherical (ellipsoidal) particles with forward scattering optical particle counters SO JOURNAL OF AEROSOL SCIENCE LA English DT Article ID IN-SITU OBSERVATIONS; MICROPHYSICAL PROPERTIES; LIGHT-SCATTERING; CIRRUS CLOUDS; AEROSOLS AB The response of the FSSP-300 and MASP optical particle counters with forward scattering geometries has been numerically simulated adopting the T-matrix method in order to assess the instrumental properties when exposed to clouds of aspherical particles (here: rotationally symmetric ellipsoids). The resulting scattering cross sections as function of particle size are compared to Mie theory calculations for spherical particles of the same refractive index, scattering geometry, and light wavelength. Based on these T-matrix calculations the FSSP-300 instrument is found suitable for use in populations of aspherical particles with aspect ratios larger than 0.5, if various caveats are taken into consideration. From the T-matrix method new tables result, which relate the instrument's size bin limits to actual particle sizes for a given refractive index. Two data sets of measurements in a cirrus cloud and an aircraft contrail are reduced by means of these new assignment tables in order to demonstrate the applicability of the method to atmospheric clouds. This paper also discusses in detail the limitations inherent in the use of the T-matix method as replacement for the Mie theory calculations commonly adopted for the FSSP-300 type of instruments. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Forschungszentrum Julich, Inst Chem & Dynam Geosphare ICG1, Julich, Germany. Max Planck Inst Chem, D-55128 Mainz, Germany. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Borrmann, S (reprint author), Forschungszentrum Julich, Inst Chem & Dynam Geosphare ICG1, Postfach 1913, Julich, Germany. RI Borrmann, Stephan/E-3868-2010; Mishchenko, Michael/D-4426-2012 NR 19 TC 46 Z9 46 U1 0 U2 10 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0021-8502 J9 J AEROSOL SCI JI J. Aerosol. Sci. PD JUL PY 2000 VL 31 IS 7 BP 789 EP 799 DI 10.1016/S0021-8502(99)00563-7 PG 11 WC Engineering, Chemical; Engineering, Mechanical; Environmental Sciences; Meteorology & Atmospheric Sciences SC Engineering; Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA 317RP UT WOS:000087241000003 ER PT J AU Pendleton, EW Bessette, D Field, PB Miller, GD Griffin, KE AF Pendleton, EW Bessette, D Field, PB Miller, GD Griffin, KE TI Active aeroelastic wing flight research program: Technical program and model analytical development SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA/ASME/ASCE/AHS/ASC 39th Structures, Structural Dynamics, and Materials Conference CY APR 20-23, 1998 CL LONG BEACH, CALIFORNIA SP Amer Inst Aeronaut & Astronaut, ASME, ASCE, AHS, ASC AB The Active Aeroelastic Wing (AAW) Flight Research Program's (Pendleton, E., Griffin, K., Kehoe, RI., and Ferry, B., "A Flight Research Program for Active Aeroelastic Wing Technology," AIAA Paper 96-1574, April 1996 and Pendleton, E., Bessette, D., Field, P., Miller, G., and Griffin, K., "The Active Aeroelastic Wing Flight Research Program," AIAA Paper 98-1972, April 1998) technical content is presented and analytical model development is summarized. Goals of the AAW flight research program are to demonstrate, in full scale, key AAW parameters and to measure the aerodynamic, structural, and flight control characteristics associated with AAW. Design guidance, derived from the results of this benchmark flight program, will be provided for implementation on future aircraft designs. C1 USAF, Res Lab, Air Vehicles Directorate, Wright Patterson AFB, OH 45433 USA. NASA, Dryden Flight Res Ctr, Edwards, CA 93523 USA. SW Res Inst, San Antonio, TX 78238 USA. RP Pendleton, EW (reprint author), USAF, Res Lab, Air Vehicles Directorate, Wright Patterson AFB, OH 45433 USA. NR 10 TC 86 Z9 91 U1 1 U2 9 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 JUL-AUG PY 2000 VL 37 IS 4 BP 554 EP 561 DI 10.2514/2.2654 PG 8 WC Engineering, Aerospace SC Engineering GA 341LC UT WOS:000088591000002 ER PT J AU Schroeder, JA Chung, WWY Hess, RA AF Schroeder, JA Chung, WWY Hess, RA TI Evaluation of a motion fidelity criterion with visual scene changes SO JOURNAL OF AIRCRAFT LA English DT Article ID PERCEIVED VELOCITY; PERCEPTION; SPEED AB An experiment examined how visual scene and platform motion variations affected a pilot's ability to perform altitude changes. pilots controlled a helicopter model in the vertical asis and moved between two points 32-ft apart in a specified time. Four hf tors were varied: visual-scene spatial frequency, visual-scene background, motion-filter gain, and motion-filter natural frequency. Drawing alternating black and white stripes of varying widths between the two extreme altitude points varied visual-scene spatial frequency. The visual-scene background varied by either drawing the stripes to fill the entire field of view or by placing the stripes on a narrow pole with a natural sky and ground plane behind the pole. Both the motion-filter gain and natural frequency were varied in the motion platform command software. Five pilots evaluated all combinations of the visual and motion variations. The results showed that only the motion-filter natural frequency and visual-scene background affected pilot performance and their subjective ratings. No significant effects of spatial frequency or motion system gain were found For the values examined in this tracking task. A previous motion fidelity criterion was found to still be a reasonable predictor of motion fidelity. C1 NASA, Ames Res Ctr, Flight Control & Cockpit Integrat Branch, Rotorcraft Div,USA, Moffett Field, CA 94035 USA. Logicon Informat Syst & Serv, Moffett Field, CA 94035 USA. Univ Calif Davis, Dept Mech & Aeronaut Engn, Davis, CA 95616 USA. RP Schroeder, JA (reprint author), NASA, Ames Res Ctr, Flight Control & Cockpit Integrat Branch, Rotorcraft Div,USA, M-S 210-5, Moffett Field, CA 94035 USA. NR 26 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 2000 VL 37 IS 4 BP 580 EP 587 DI 10.2514/2.2669 PG 8 WC Engineering, Aerospace SC Engineering GA 341LC UT WOS:000088591000005 PM 11543542 ER PT J AU Greer, D Hamory, P Krake, K Drela, M AF Greer, D Hamory, P Krake, K Drela, M TI Design and predictions for high-altitude (low Reynolds number) aerodynamic flight experiment SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA 17th Applied Aerodynamics Conference CY JUN 28-JUL 01, 1999 CL NORFOLK, VIRGINIA SP AIAA ID SEPARATION AB A sailplane being developed at NASA Dryden Flight Research Center will support a high-altitude flight experiment. The experiment will measure the performance parameters of an airfoil at high altitudes (70,000-100,000 ft), low Reynolds numbers (2 x 10(5)-7 x 10(5)), and high subsonic Mach numbers (0.5 and 0.65). The airfoil section lift and drag are determined from pitot and static pressure measurements. The locations of the separation bubble, Tollmien-Schlichting boundary-layer instability frequencies, and vortex shedding are measured from a hot-film strip. The details of the planned flight experiment are presented as well as several predictions of the airfoil performance. C1 NASA, Dryden Flight Res Ctr, Edwards, CA 93523 USA. Sparta Inc, Edwards, CA 93523 USA. MIT, Dept Aerosp Engn, Cambridge, MA 02139 USA. RP Greer, D (reprint author), NASA, Dryden Flight Res Ctr, POB 273,MS D2024, Edwards, CA 93523 USA. NR 20 TC 2 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 2000 VL 37 IS 4 BP 684 EP 689 DI 10.2514/2.2652 PG 6 WC Engineering, Aerospace SC Engineering GA 341LC UT WOS:000088591000018 ER PT J AU Hong, Y Haferman, JL Olson, WS Kummerow, CD AF Hong, Y Haferman, JL Olson, WS Kummerow, CD TI Microwave brightness temperatures from tilted convective systems SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID VERTICAL STRUCTURE INFORMATION; PASSIVE MICROWAVE; RADIATIVE-TRANSFER; ESTIMATING RAINFALL; PRECIPITATION; MESOSCALE; CLOUD; RETRIEVALS; PROFILES; MODEL AB Aircraft and ground-based radar data from the Tropical Ocean and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment show that convective systems are not always vertical. Instead, many are tilted from vertical. Satellite passive microwave radiometers observe the atmosphere at an oblique angle. For example, the Special Sensor Microwave Imager on Defense Meteorological Satellite Program satellites and the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI) on the TRMM satellite view at an incident angle of about 50 degrees. Thus, the brightness temperature measured from one direction of till may be different than that viewed from the opposite direction because of the different optical path. This paper presents an investigation of passive microwave brightness temperatures upwelling from lilted convective systems. To account for the effect of tilt, a 3D backward Monte Carlo radiative transfer model has been applied to a simple tilted cloud model and a dynamically evolving cloud model to derive the brightness temperature. The radiative transfer results indicate that brightness temperature varies when the viewing angle changes because of the different optical path. The tilt increases the displacements between the high 19-GHz brightness temperature (Tb-19) due to liquid emission from the lower level of cloud and the low 85-GHz brightness temperature (Tb-85) due to ice scattering from the upper level of cloud. As the resolution degrades, the difference of brightness temperature due to the change of viewing angle decrease dramatically. The displacement between Tb-19 and Tb-85, however, remains prominent. The successful launch and operation of the TRMM satellite provide an opportunity to examine tilted convective systems using collocated radar and radiometer data. TMI observations of tilted systems indicate that displacement between Tb,, and Tb,, can be as far as 100 km. Such displacement not only poses a problem to rainfall retrieval algorithms that use only scattering information but also causes large uncertainty in rainfall retrieval from multichannel retrieval algorithms. This study suggests that combined radar and radiometer data are needed to reduce the effect of tilt and to improve surface rainfall retrieval. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. Fleet Numer Meteorol & Oceanog Ctr, Monterey, CA USA. Caelum Res Corp, Rockville, MD USA. RP Hong, Y (reprint author), NASA, Goddard Space Flight Ctr, Code 912, Greenbelt, MD 20771 USA. NR 33 TC 17 Z9 18 U1 0 U2 1 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 JUL PY 2000 VL 39 IS 7 BP 983 EP 998 DI 10.1175/1520-0450(2000)039<0983:MBTFTC>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 342CE UT WOS:000088627000003 ER PT J AU Lin, B Minnis, P AF Lin, B Minnis, P TI Temporal variations of land surface microwave emissivities over the atmospheric radiation measurement program southern great plains site SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID WATER CLOUD PROPERTIES; VISIBLE MEASUREMENTS; SATELLITE MICROWAVE; HIGH-FREQUENCIES; SOIL-MOISTURE; 37 GHZ; VEGETATION; RETRIEVAL; SMMR; PRECIPITATION AB Land surface microwave emissivities are important geophysical parameters for atmospheric, hydrological, and biospheric studies. This study estimates land surface microwave emissivity using an atmospheric microwave radiative transfer model and a combination of the Special Sensor Microwave Imager (SSM/I) satellite observations and data from the Atmospheric Radiation Measurement Program southern Great Plains (SGP) site during October of 1995. Emissivities are retrieved for both clear and cloudy conditions. Emissivity standard deviations of similar to 0.035 were found at the SGP site. Much of the variability is produced by a distinct diurnal cycle. The emissivity variability at each SSM/I overpass time (0630, 1100, 1730, and 1000 local time) is about half that for ail four times combined. Early morning emissivities are similar to 0.06 less than those at other times, and the polarization differences at the four times are similar. This behavior is likely the result of dew and surface rewetting effects. Ground observations of dewpoint and temperature difference between air and skin support this theory. The surface emissivities have a significant negative correlation with soil moisture, which can explain about 60%-80% of the emissivity variance when pentad running means are used. Strong correlations among all seven SSM/I channels indicate that the emissivities need to be determined directly for only two or three channels. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Hampton Univ, Ctr Atmospher Sci, Hampton, VA 23668 USA. RP Lin, B (reprint author), NASA, Langley Res Ctr, MS 420, Hampton, VA 23681 USA. RI Minnis, Patrick/G-1902-2010 OI Minnis, Patrick/0000-0002-4733-6148 NR 29 TC 28 Z9 30 U1 0 U2 1 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 JUL PY 2000 VL 39 IS 7 BP 1103 EP 1116 DI 10.1175/1520-0450(2000)039<1103:TVOLSM>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 342CE UT WOS:000088627000011 ER PT J AU Minnis, P Khaiyer, MM AF Minnis, P Khaiyer, MM TI Anisotropy of land surface skin temperature derived from satellite data SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID CLOUD AB The land skin temperature, an important feature for agricultural monitoring, convective processes, and the earth's radiation budget, is monitored from limited-view satellite imagers. The angular dependence of this parameter is examined using simultaneous views of clear areas from up to three geostationary satellites. Daytime temperatures from different satellites differed by up to 6 K and varied as a function of the time of day. Larger differences are expected to occur but were not measured because of limited viewing angles. These differences suggest that biases may occur in both the magnitude and phase of the diurnal cycle of skin temperature and its mean value whenever geostationary satellite data are used to determine skin temperature. The temperature differences were found over both flat and mountainous regions with some slight dependence on vegetation. The timing and magnitude of the temperature differences provide some initial validation for relatively complex model calculations of skin temperature variability. The temperature differences are strongly correlated with terrain and the anisotropy of reflected solar radiation for typical land surfaces. These strong dependencies suggest the possibility for the development of a simple empirical approach for characterizing the temperature anisotropy. Additional research using a much greater range of viewing angles is required to confirm the potential of the suggested empirical approach. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Analyt Serv & Mat Inc, Hampton, VA 23666 USA. RP Minnis, P (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. RI Minnis, Patrick/G-1902-2010 OI Minnis, Patrick/0000-0002-4733-6148 NR 14 TC 39 Z9 40 U1 2 U2 3 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 JUL PY 2000 VL 39 IS 7 BP 1117 EP 1129 DI 10.1175/1520-0450(2000)039<1117:AOLSST>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 342CE UT WOS:000088627000012 ER PT J AU Joshi, RP Neudeck, PG Fazi, C AF Joshi, RP Neudeck, PG Fazi, C TI Analysis of the temperature dependent thermal conductivity of silicon carbide for high temperature applications SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID TECHNOLOGY; MICROPIPE; DEVICES; DEFECTS; DIODES AB The temperature dependent thermal conductivity of silicon carbide has been calculated taking into account the various phonon scattering mechanisms. The results compared very well with available experimental data. The inclusion of four-phonon processes is shown to be necessary for obtaining a good match. Several important phonon scattering parameters have been extracted in this study. Dislocations are shown to have a strong effect at 300 K, but not as much at the higher temperatures. (C) 2000 American Institute of Physics. [S0021-8979(00)08513-3]. C1 Old Dominion Univ, Dept Elect & Comp Engn, Norfolk, VA 23529 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. USA, Res Lab, Adelphi, MD 20783 USA. RP Joshi, RP (reprint author), Old Dominion Univ, Dept Elect & Comp Engn, Norfolk, VA 23529 USA. NR 44 TC 33 Z9 34 U1 4 U2 10 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUL 1 PY 2000 VL 88 IS 1 BP 265 EP 269 DI 10.1063/1.373651 PG 5 WC Physics, Applied SC Physics GA 325YE UT WOS:000087704000040 ER PT J AU Ortiz, RM Wade, CE AF Ortiz, RM Wade, CE TI Water balance in rats exposed to chronic centrifugation SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE deuterium oxide; hypergravity; lean body mass; total body water ID FLUID SHIFTS; HUMANS; PLASMA; URINE AB Changes in gravitational load have been shown to alter renal function, which could potentially affect water balance. Therefore, the present study was conducted to determine the effects of chronic centrifugation on water balance. Eight Sprague-Dawley rats were centrifuged (12 days at 2 G), and eight rats were used as a control group. Water balance over the course of the study was determined by quantifying the percentage (%) of total body water [TBW; (TBW/body mass)] and water flux (water consumption urine volume). TBW was estimated, by means of deuterium oxide dilution, before the study and after 3 days of centrifugation and by means of desiccation after 12 days of centrifugation. %TBW did not change in the centrifuged rats from initial levels or relative to controls over the course of the study. Differences between the sum of water consumption and sum of urine volume for the 12-day period were the same in both groups. Although an initial period of negative water balance was observed, the lack of a change in %TBW among the three measurement periods or in water flux over the 12 days of centrifugation suggests that water balance is not negatively affected as a result of centrifugation at 2 G. C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. RP Wade, CE (reprint author), NASA, Ames Res Ctr, Div Life Sci, MS 239-11, Moffett Field, CA 94035 USA. NR 25 TC 6 Z9 6 U1 0 U2 0 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 JUL PY 2000 VL 89 IS 1 BP 56 EP 60 PG 5 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 335EK UT WOS:000088230400008 PM 10904035 ER PT J AU Watenpaugh, DE Ballard, RE Schneider, SM Lee, SMC Ertl, AC William, JM Boda, WL Hutchinson, KJ Hargens, AR AF Watenpaugh, DE Ballard, RE Schneider, SM Lee, SMC Ertl, AC William, JM Boda, WL Hutchinson, KJ Hargens, AR TI Supine lower body negative pressure exercise during bed rest maintains upright exercise capacity SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE human; male; treadmill; microgravity; spaceflight; countermeasure ID RESISTANCE EXERCISE; MAXIMAL EXERCISE; METABOLIC COST; WEIGHTLESSNESS; SPACEFLIGHT; MICROGRAVITY; PERFORMANCE; RESPONSES; TOLERANCE; WALKING AB Bed rest and spaceflight reduce exercise fitness. Supine lower body negative pressure (LBNP) treadmill exercise provides integrated cardiovascular and musculoskeletal stimulation similar to that imposed by upright exercise in Earth gravity. We hypothesized that 40 min of supine exercise per day in a LBNP chamber at 1.0-1.2 body wt (58 +/- 2 mmHg LBNP) maintains aerobic fitness and sprint speed during 15 days of 6 degrees head-down bed rest (simulated microgravity). Seven male subjects underwent two such bed-rest studies in random order: one as a control study (no exercise! and one with daily supine LBNP treadmill exercise. After controlled bed-rest, time to exhaustion during an upright treadmill exercise test decreased 10%, peak oxygen consumption during the test decreased 14%, and sprint speed decreased 16% (all P < 0.05). Supine LBNP exercise during bed rest maintained all the above variables at pre-bed-rest levels. Our findings support further evaluation of LBNP exercise as a countermeasure against long-term microgravity-induced deconditioning. C1 NASA, Ames Res Ctr, Gravitat Res Branch, Moffett Field, CA 94035 USA. NASA, Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. RP Watenpaugh, DE (reprint author), Univ N Texas, Hlth Sci Ctr, Dept Integrat Physiol, 3500 Camp Bowie Blvd, Ft Worth, TX 76107 USA. NR 39 TC 73 Z9 75 U1 0 U2 5 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 JUL PY 2000 VL 89 IS 1 BP 218 EP 227 PG 10 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 335EK UT WOS:000088230400028 PM 10904055 ER PT J AU Koshak, WJ Stewart, MF Christian, HJ Bergstrom, JW Hall, JM Solakiewicz, RJ AF Koshak, WJ Stewart, MF Christian, HJ Bergstrom, JW Hall, JM Solakiewicz, RJ TI Laboratory calibration of the optical transient detector and the lightning imaging sensor SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article AB The authors present in detail the laboratory apparatus and techniques that were used to complete a full radiometric calibration of two space-based lightning detectors: the optical transient detector (OTD) and the lightning imaging sensor (LIS) that were developed at the National Aeronautics and Space Administration Marshall Space Flight Center These instruments are nadir-staring imagers that are optimized to detect and locate lightning from low Earth orbit during day and night conditions. The radiometric calibration consisted of characterizing the pixel response to steady and transient optical sources, sensor field of view, and sensor spectral response. The transient optical signals produced in the calibration laboratory were used to derive estimates of sensor lightning detection efficiency. C1 NASA, Global Hydrol & Climate Ctr, MSFC, Huntsville, AL 35806 USA. Univ Alabama, Ctr Earth Syst Sci, Huntsville, AL 35899 USA. Ball Aerosp & Technol Corp, Boulder, CO USA. Comp Sci Corp, Huntsville, AL USA. Chicago State Univ, Dept Math & Comp Sci, Chicago, IL USA. RP Koshak, WJ (reprint author), NASA, Global Hydrol & Climate Ctr, MSFC, SD60,977 Explorer Blvd, Huntsville, AL 35806 USA. NR 9 TC 26 Z9 30 U1 0 U2 6 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 JUL PY 2000 VL 17 IS 7 BP 905 EP 915 DI 10.1175/1520-0426(2000)017<0905:LCOTOT>2.0.CO;2 PG 11 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 336RC UT WOS:000088315900002 ER PT J AU Chu, PC Fan, CW Liu, WT AF Chu, PC Fan, CW Liu, WT TI Determination of vertical thermal structure from sea surface temperature SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID SOUTH-CHINA SEA; MODEL AB A recently developed parametric model by P. C. Chu et al. is used in this paper for determining subsurface thermal structure from satellite sea surface temperature observations. Based on a layered structure of temperature fields (mixed layer, thermocline, and lower layers), the parametric model transforms a vertical profile into several parameters: sea surface temperature (SST), mixed layer depth (MLD), thermocline bottom depth (TBD), thermocline temperature gradient (TTG), and deep layer stratification (DLS). These parameters vary on different timescales: SST and MLD on scales of minutes to hours, TBD and TTG on months to seasons, and DLS on an even longer timescale. if the long timescale parameters such as TBD, TTD, and DLS are known (or given by climatological values), the degree of freedom of a vertical profile fitted by the model reduces to one: SST. When SST is observed, one may invert MLD, and, in turn, the vertical temperature profile with the known long timescale parameters: TBD, TTG, and DLS. The U.S. Navy's Master Oceanographic Observation Data Set (MOODS) for the South China Sea in May 1932-94 (10153 profiles) was used for the study. Among them, there are 40 data points collocating and coappearing (same week) with the weekly daytime NASA multichannel SST data in 1986-94. The 40 MOODS profiles were treated as a test dataset. The MOODS dataset excluding the test data is the training dataset, consisting of 10 113 profiles. The training dataset was processed into a dataset consisting of SST, MLD, TBD, TTG, and DLS using the parametric model. SST from the test dataset was used for the inversion based on the known information on TBD, TTG, and DLS. The 40 inverted profiles agreed quite well with the corresponding observed profiles. The rms error is 0.72 degrees C, and the correlation between the inverted and observed profiles is 0.79. This is much better than the simple method of estimating subsurface temperature anomaly from SST anomaly by correlating the two in the training dataset. The possibility of using this method globally is also discussed. C1 USN, Dept Oceanog, Postgrad Sch, Monterey, CA 93943 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Chu, PC (reprint author), USN, Dept Oceanog, Postgrad Sch, Monterey, CA 93943 USA. NR 9 TC 23 Z9 31 U1 0 U2 2 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 JUL PY 2000 VL 17 IS 7 BP 971 EP 979 DI 10.1175/1520-0426(2000)017<0971:DOVTSF>2.0.CO;2 PG 9 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 336RC UT WOS:000088315900008 ER PT J AU Raeder, J Vaisberg, O Smirnov, V Avanov, L AF Raeder, J Vaisberg, O Smirnov, V Avanov, L TI Reconnection driven lobe convection: Interball tail probe observations and global simulations SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT 6th Annual Huntsville Modeling Workshop CY OCT 26-30, 1998 CL GUNTERSVILLE, ALABAMA ID INTERPLANETARY MAGNETIC-FIELD; HIGH-LATITUDE MAGNETOPAUSE; POLAR-CAP CONVECTION; IONOSPHERIC CONVECTION; BOUNDARY-LAYER; MAGNETOTAIL BOUNDARY; ELECTRIC-FIELDS; GRAND CHALLENGE; MHD MODEL; NORTHWARD AB We present Interball Tail Probe observations from the high latitude mid-tail magnetopause which provide evidence of reconnection between the interplanetary magnetic field (IMF) and lobe field lines during a 6 h interval of stable northward and dawnward IMF on October 19, 1995. Results from a global magnetohydrodynamic simulation for this interval compare well with the Interball observations. With the simulations, we provide an extended global view of this event which gives us insight into the reconnection and convection dynamics of the magnetosphere. We find that reconnection occurs in a region of limited spatial extent near the terminator and where the IMF and the lobe field are anti-parallel. Reconnected IMF field lines drape over the dayside magnetosphere, convect along the flanks into the nightside, and enter the magnetotail through a small entry window that is located in the flank opposite to the reconnection site. Ionospheric convection is consistent with previous observations under similar IMF conditions and exhibits a two cell pattern with a dominant lobe cell over the pole. The magnetic mapping between the ionosphere and the lobe boundary is characterized by two singularities: the narrow entry window in the tail maps to a 6 h wide section of the ionospheric lobe cell. A singular mapping line cuts the lobe cell open and maps to almost the entire tail magnetopause. By this singularity the magnetosphere avoids having a stagnation point, i.e., the lobe cell center maps to a tailward convecting field line. The existence of singularities in the magnetic mapping between the ionosphere and the tail has important implications for the study of tail-ionosphere coupling via empirical magnetic field models. Because the lobe-IMF reconnection cuts away old lobe flux and replaces it with flux tubes of magnetosheath origin, solar wind plasma enters the lobes in a process that is similar to the one that operates during southward IMF. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. Russian Acad Sci, Inst Space Res, Moscow V71, Russia. NASA, Marshall Space Flight Ctr, Huntsville, AL USA. RP Raeder, J (reprint author), Univ Calif Los Angeles, Inst Geophys & Planetary Phys, 405 Hilgard Ave, Los Angeles, CA 90095 USA. NR 57 TC 12 Z9 15 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 JUL PY 2000 VL 62 IS 10 BP 833 EP 849 DI 10.1016/S1364-6826(00)00041-9 PG 17 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 350RB UT WOS:000089114000004 ER PT J AU Ostgaard, N Stadsnes, J Bjordal, J Vondrak, RR Cummer, SA Chenette, DL Schulz, M Parks, GK Brittnacher, MJ McKenzie, DL Pronko, JG AF Ostgaard, N Stadsnes, J Bjordal, J Vondrak, RR Cummer, SA Chenette, DL Schulz, M Parks, GK Brittnacher, MJ McKenzie, DL Pronko, JG TI Global X-ray emission during an isolated substorm - a case study SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT 6th Annual Huntsville Modeling Workshop CY OCT 26-30, 1998 CL GUNTERSVILLE, ALABAMA ID ELECTRON-PRECIPITATION; AURORAL-ZONE; SECTOR AB The polar ionospheric X-ray imaging experiment (PIXIE) and the UV imager (UVI) onboard the Polar satellite have provided the first simultaneous global scale views of the patterns of electron precipitation through imaging of the atmospheric X-ray bremsstrahlung and the auroral UV emissions. While the UV images in the Lyman-Birge-Hopfield-long band used in this study respond to the total electron energy flux which is usually dominated by low-energy electrons (<10 keV), the PIXIE images of X-ray bremsstrahlung above similar to 2.7 keV respond to electrons of energy above similar to 3 keV. Comparison of precipitation features seen by UVI and PIXIE provides information on essentially complementary energy ranges of the precipitating electrons. In this study an isolated substorm is examined using data from PIXIE, UVI, ground-based measurements, and in situ measurements from high- and low-altitude satellites to obtain information about the global characteristics during the event. Results from a statistical study of isolated substorms, which has reported a significant difference in the patterns of energetic electron precipitation compared to the less energetic precipitation are confirmed. A localized maximum of electron precipitation in the morning sector delayed with respect to substorm onset is clearly seen in the X-ray aurora, and the time delay of this morning precipitation relative to substorm onset strongly indicates that this intensification is caused by electrons injected in the midnight sector drifting into a region in the dawnside magnetosphere where some mechanism effectively scatter the electrons into the loss cone. In this study, we also present the results from two low-altitude satellite passes through the region of the localized maximum of X-ray emission in the morning sector. Measured X rays are compared with X-ray fluxes calculated from the electron spectral measurements. By fitting the electron spectra by a sum of two exponentials we obtain fairly good agreement between calculated and directly measured X-ray flux profiles. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Bergen, Dept Phys, Bergen, Norway. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Lockheed Martin Adv Technol Ctr, Palo Alto, CA USA. Univ Washington, Geophys Program, Seattle, WA 98195 USA. Aerospace Corp, Los Angeles, CA 90009 USA. Univ Nevada, Dept Phys, Reno, NV 89557 USA. RP Ostgaard, N (reprint author), Univ Bergen, Dept Phys, Bergen, Norway. RI Cummer, Steven/A-6118-2008 OI Cummer, Steven/0000-0002-0002-0613 NR 30 TC 5 Z9 5 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD JUL PY 2000 VL 62 IS 10 BP 889 EP 900 DI 10.1016/S1364-6826(00)00034-1 PG 12 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 350RB UT WOS:000089114000008 ER PT J AU Perez, JD Fok, MC Moore, TE AF Perez, JD Fok, MC Moore, TE TI Imaging a geomagnetic storm with energetic neutral atoms SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT 6th Annual Huntsville Modeling Workshop CY OCT 26-30, 1998 CL GUNTERSVILLE, ALABAMA ID RING CURRENT; MODEL; DECAY AB The ring current during a geomagnetic storm on May 2, 1986 has been modeled using a bounce averaged kinetic equations for the phase space density of hydrogen ions, considering charge exchange and Coulomb losses along the drift path. The resulting equatorial pitch angle distribution is used to generate data simulating the medium and high energy neutral atom imagers to be flown on IMAGE. A method for deconvolving these images is described and applied to the simulated data. The results show that, when there are sufficient counts, the deconvolved distribution contains the main features of the original source and that the energy spectrum at a specific time as well as the total energy of the ring current as a function of time can be extracted from the energetic neutral atom images. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Auburn Univ, Dept Phys, Coll Sci & Math, Allison Lab 206, Auburn, AL 36849 USA. NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Perez, JD (reprint author), Auburn Univ, Dept Phys, Coll Sci & Math, Allison Lab 206, Auburn, AL 36849 USA. RI Moore, Thomas/D-4675-2012; Fok, Mei-Ching/D-1626-2012 OI Moore, Thomas/0000-0002-3150-1137; NR 26 TC 1 Z9 1 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 JUL PY 2000 VL 62 IS 10 BP 911 EP 917 DI 10.1016/S1364-6826(00)00037-7 PG 7 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 350RB UT WOS:000089114000010 ER PT J AU Khazanov, GV Liemohn, MW Kozyra, JU Gallagher, DL AF Khazanov, GV Liemohn, MW Kozyra, JU Gallagher, DL TI Global energy deposition to the topside ionosphere from superthermal electrons SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT 6th Annual Huntsville Modeling Workshop CY OCT 26-30, 1998 CL GUNTERSVILLE, ALABAMA DE topside ionosphere; superthermal electrons; heating ID ION-CYCLOTRON WAVES; OUTER PLASMASPHERE; THERMAL ELECTRONS; RED ARCS; MODEL; MAGNETOSPHERE; INSTABILITY; ATMOSPHERE; TURBULENCE; TRANSPORT AB The subauroral heat input to the topside ionosphere from two superthermal electron sources, photoelectrons and plasma sheet electrons, are calculated using a global kinetic model of electron transport in the inner magnetosphere. Peak rates above 10(10) eV cm(-2) s(-1) are found for photoelectrons in the midlatitude afternoon region, while the peak deposition rate for plasma sheet electrons only occasionally approaches 10(9) eV cm(-2) s(-1), and is typically confined to the morningside. Trapped clouds of plasma sheet electrons, however, are shown to have lasting effects on the structure of topside heat input, as the energetic electrons corotate and slowly transfer their energy to the thermal plasma over a course of days. These energy inputs are compared with other heat sources in the inner magnetosphere. It is concluded that, while other processes can inject large amounts of energy into the ionosphere in spatially and temporally localized regions, photoelectrons are the strongest and steadiest heat source into the topside ionosphere. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Michigan, Space Phys Res Lab, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. Univ Alaska, Inst Geophys, Fairbanks, AK 99775 USA. Univ Alaska, Dept Phys, Fairbanks, AK 99775 USA. NASA, Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Liemohn, MW (reprint author), Univ Michigan, Space Phys Res Lab, Dept Atmospher Ocean & Space Sci, 2455 Hayward St, Ann Arbor, MI 48109 USA. RI Liemohn, Michael/H-8703-2012 OI Liemohn, Michael/0000-0002-7039-2631 NR 31 TC 8 Z9 8 U1 1 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 JUL PY 2000 VL 62 IS 10 BP 947 EP 954 DI 10.1016/S1364-6826(00)00033-X PG 8 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 350RB UT WOS:000089114000014 ER PT J AU Arnoldussen, ME Cohen, D Bearman, GH Grundfest, WS AF Arnoldussen, ME Cohen, D Bearman, GH Grundfest, WS TI Consequences of scattering for spectral imaging of turbid biologic tissue SO JOURNAL OF BIOMEDICAL OPTICS LA English DT Article DE hyperspectral imaging; reflection spectroscopy; Monte Carlo model; retina ID PHOTON MIGRATION; SPECTROSCOPY; MEDIA; TIME AB Spectral imaging permits two-dimensional mapping of the backscattering properties of biological systems. Such mapping requires broadband illumination of the entire area of interest. However, imaging of turbid biological media under these conditions often involves mean photon path lengths that exceed the pixel size. Using a numerical Monte Carlo model, we have studied the effects of photon scattering in a hemoglobin-bearing model system. We find that photon migration and the resulting wavelength-dependent optical coupling between pixels can complicate the analysis of imaging spectroscopy data. in fact, the wavelength dependence of photon trajectories also alters the distribution of photon exit angles at the tissue surface. We therefore find that the finite optical field of view of an imaging spectrometer can affect the measured spectra in the absence of chromatic aberrations, (C) 2000 Society of Photo-Optical Instrumentation Engineers. [S1083-3668(00)00103-7]. C1 Cedars Sinai Med Ctr, Laser Res & Technol Dev Lab, Los Angeles, CA 90048 USA. Univ So Calif, Dept Biomed Engn, Los Angeles, CA 90089 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Cohen, D (reprint author), Cedars Sinai Med Ctr, Laser Res & Technol Dev Lab, 650 S San Vicente Blvd, Los Angeles, CA 90048 USA. NR 14 TC 13 Z9 13 U1 0 U2 2 PU SPIE-INT SOCIETY OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98225 USA SN 1083-3668 J9 J BIOMED OPT JI J. Biomed. Opt. PD JUL PY 2000 VL 5 IS 3 BP 300 EP 306 DI 10.1117/1.430000 PG 7 WC Biochemical Research Methods; Optics; Radiology, Nuclear Medicine & Medical Imaging SC Biochemistry & Molecular Biology; Optics; Radiology, Nuclear Medicine & Medical Imaging GA 343NE UT WOS:000088707800008 PM 10958616 ER PT J AU Parthiban, S Lee, TJ AF Parthiban, S Lee, TJ TI Theoretical study of XONO2 (X=Br, OBr, O2Br): Implications for stratospheric bromine chemistry SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID AB-INITIO CHARACTERIZATION; GAUSSIAN-BASIS SETS; COUPLED-CLUSTER; MOLECULAR CALCULATIONS; VIBRATIONAL-SPECTRUM; ATMOSPHERIC BROMINE; CHLORINE NITRATE; BRONO2; CL; ISOMERS AB The equilibrium structure, dipole moment, harmonic vibrational frequencies, and infrared intensities of XONO2 (X=Br, OBr, O2Br) are determined using density functional theory in conjunction with a TZ2P (triple zeta double polarized) basis set. The B3LYP functional was used since this has previously been shown to perform well for similar bromine compounds. The equilibrium geometry and vibrational spectra of BrONO2 are shown to be in good agreement with the experimental data and also with high-level coupled-cluster calculations. The vibrational spectrum of O2BrONO2 has been compared with that of the chlorine analog, O2ClONO2, for which some experimental data exist. The bonding in OBrONO2 is shown to be more similar to that in BrONO2. Using large atomic natural orbital basis sets, the singles and doubles coupled-cluster method that includes a perturbative correction for triple excitations, denoted CCSD(T), was employed to compute energies for three isodesmic reactions in order to determine heats of formation for OBrONO2 and O2BrONO2. Our best estimates are 36.7 and 38.7 kcal/mol, respectively. Finally, the possible formation of O2BrONO2 in the stratosphere by adduct formation and oxidation of OBrONO2 and the implications for stratospheric bromine chemistry are discussed. (C) 2000 American Institute of Physics. [S0021-9606(00)30125-8]. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Parthiban, S (reprint author), NASA, Ames Res Ctr, MS230-3, Moffett Field, CA 94035 USA. RI Lee, Timothy/K-2838-2012 NR 56 TC 15 Z9 16 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUL 1 PY 2000 VL 113 IS 1 BP 145 EP 152 DI 10.1063/1.481781 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 326TE UT WOS:000087750800018 ER PT J AU Bounoua, L Collatz, GJ Los, SO Sellers, PJ Dazlich, DA Tucker, CJ Randall, DA AF Bounoua, L Collatz, GJ Los, SO Sellers, PJ Dazlich, DA Tucker, CJ Randall, DA TI Sensitivity of climate to changes in NDVI SO JOURNAL OF CLIMATE LA English DT Article ID GENERAL-CIRCULATION MODEL; SURFACE PARAMETERIZATION SIB2; ICE-CLOUD MICROPHYSICS; DOUBLED ATMOSPHERIC CO2; SEMI-ARID REGIONS; SOIL-MOISTURE; CANOPY REFLECTANCE; GLOBAL CLIMATE; STOMATAL CONDUCTANCE; DAILY TEMPERATURE AB The sensitivity of global and regional climate to changes in vegetation density is investigated using a coupled biosphere-atmosphere model. The magnitude of the vegetation changes and their spatial distribution are based on natural decadal variability of the normalized difference vegetation index (NDVI). Different scenarios using maximum and minimum vegetation cover were derived from satellite records spanning the period 1982-90. Albedo decreased in the northern latitudes and increased in the Tropics with increased NDVI. The increase in vegetation density revealed that the vegetation's physiological response was constrained by the limits of the available water resources. The difference between the maximum and minimum vegetation scenarios resulted in a 46% increase in absorbed visible solar radiation and a similar increase in gross photosynthetic CO, uptake on a global annual basis. This increase caused the canopy transpiration and interception fluxes to increase and reduced those from the soil. The redistribution of the surface energy fluxes substantially reduced the Bowen ratio during the growing season, resulting in cooler and moister near-surface climate, except when soil moisture was limiting. Important effects of increased vegetation on climate are a cooling of about 1.8 K in the northern latitudes during the growing season and a slight warming during the winter, which is primarily due to the masking of high albedo of snow by a denser canopy; and a year-round cooling of 0.8 K in the Tropics. These results suggest that increases in vegetation density could partially compensate for parallel increases in greenhouse warming. Increasing vegetation density globally caused both evapotranspiration and precipitation to increase. Evapotranspiration, however, increased more than precipitation, resulting in a global soil-water deficit of about 15%. A spectral analysis on the simulated results showed that changes in the state of vegetation could affect the low-frequency modes of the precipitation distribution and might reduce its low-frequency variability in the Tropics while increasing it in northern latitudes. C1 NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. Sci Syst & Applicat Inc, Greenbelt, MD USA. Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. RP Bounoua, L (reprint author), NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Code 923, Greenbelt, MD 20771 USA. EM bounoua@dounia.gsfc.nasa.gov RI Randall, David/E-6113-2011; collatz, george/D-5381-2012; Los, Sietse/G-8985-2012; OI Randall, David/0000-0001-6935-4112; Los, Sietse/0000-0002-1325-3555 NR 61 TC 131 Z9 147 U1 3 U2 39 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 JUL 1 PY 2000 VL 13 IS 13 BP 2277 EP 2292 DI 10.1175/1520-0442(2000)013<2277:SOCTCI>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 339QR UT WOS:000088489900009 ER PT J AU Mei, R Shyy, W Yu, D Luo, LS AF Mei, R Shyy, W Yu, D Luo, LS TI Lattice Boltzmann method for 3-D flows with curved boundary SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE lattice Boltzmann equation; boundary condition for curved geometries; accuracy; 3-D flows ID ANALYTIC SOLUTIONS; BGK MODELS; EQUATION; SIMULATIONS AB In this work, we investigate two issues that are important to computational efficiency and reliability in fluid dynamic applications of the lattice Boltzmann equation (LBE): (1) Computational stability and accuracy of different lattice Boltzmann models and (2) the treatment of the boundary conditions on curved solid boundaries and their 3-D implementations. Three athermal 3-D LEE models (Q15D3, Q19D3, and 427D3) are studied and compared in terms of efficiency, accuracy and robustness. The boundary treatment recently developed by Filippova and Hanel (1998, J. Comp. Phys. 1.47, 219) and Mei et al. (1999, J. Comp. Phys. 155, 307) in 2-D is extended to and implemented for 3-D. The convergence, stability, and computational efficiency of the 3-D LEE models with the boundary treatment for curved boundaries were tested in simulations of four 3-D flows: (1) Fully developed flows in a square duct, (2) flow in a 3-D lid-driven cavity, (3) fully developed flows in a circular pipe, and (4) a uniform flow over a sphere. We found that while the 15-velocity 3-D (Q15D3) model is more prone to numerical instability and the Q27D3 is more computationally intensive, the Q19D3 model provides a balance between computational reliability and efficiency. Through numerical simulations, we demonstrated that the boundary treatment for 3-D arbitrary curved geometry has second-order accuracy and possesses satisfactory stability characteristics. (C) 2000 Academic Press. C1 Univ Florida, Dept Aerosp Engn Mech & Engn Sci, Gainesville, FL 32611 USA. NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. RP Mei, R (reprint author), Univ Florida, Dept Aerosp Engn Mech & Engn Sci, Gainesville, FL 32611 USA. RI Luo, Li-Shi/A-4561-2011 OI Luo, Li-Shi/0000-0003-1215-7892 NR 31 TC 172 Z9 181 U1 4 U2 27 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD JUL 1 PY 2000 VL 161 IS 2 BP 680 EP 699 DI 10.1006/jcph.2000.6522 PG 20 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 329JD UT WOS:000087903100014 ER PT J AU Su, CH Sha, YG Volz, MP Carpenter, P Lehoczky, SL AF Su, CH Sha, YG Volz, MP Carpenter, P Lehoczky, SL TI Vapor growth and characterization of ZnSeTe solid solutions SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE physical vapor transport; zinc selenide telluride ID MOLECULAR-BEAM EPITAXY; TRANSPORT; CRYSTALS AB Six ZnSe1-xTex crystals were grown by the physical vapor transport technique. For each of the source material compositions, x = 0.10, 0.20 and 0.30, two crystals were grown - one under horizontal and the other under vertical stabilized configurations. The axial and radial compositional uniformity were determined by precision density measurements, wavelength dispersive X-ray spectroscopy (WDS) and optical transmission mappings. The measured radial ZnTe content was quite uniform for all grown crystals except the horizontally grown crystal for x = 0.30. WDS results on this crystal indicated a core with uniform ZnTe content, about 0.38, surrounded by a thin region of high ZnTe content with x = 0.8. This feature was confirmed by the SEM back scattering electron images. For the three source compositions the axial compositional variations for the vertically grown crystals were more uniform than those for the horizontally grown crystals. The measured compositions in the crystals grown from source composition of x = 0.10 suggest that the transport mechanism in the system cannot be interpreted by a simple one-dimensional diffusion limited model. (C) 2000 Published by Elsevier Science B.V. C1 NASA, Marshall Space Flight Ctr, Sci Directorate, Micrograv Sci & Applicat Dept, Huntsville, AL 35812 USA. RP Su, CH (reprint author), NASA, Marshall Space Flight Ctr, Sci Directorate, Micrograv Sci & Applicat Dept, Huntsville, AL 35812 USA. NR 11 TC 4 Z9 5 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD JUL PY 2000 VL 216 IS 1-4 BP 104 EP + DI 10.1016/S0022-0248(00)00420-6 PG 10 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 336DE UT WOS:000088286000016 ER PT J AU Palosz, W AF Palosz, W TI Physical vapor transport of lead telluride SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE PbTe; PVT; residual gas ID HETEROSTRUCTURE DIODE-LASERS; QUANTUM-WELL STRUCTURES; MOLECULAR-BEAM EPITAXY; THERMOELECTRIC FIGURE; GROWTH; SUPERLATTICES; PB1-XSNXTE; CRYSTALS; PHASE; MERIT AB Mass transport properties of physical vapor transport of PbTe are investigated. Thermochemical analysis of the system and its implications for the growth conditions are discussed. The effect of the material preparation and pre-processing on the stoichiometry and residual gas pressure and composition, and on related mass Aux is shown. A procedure leading to high mass transport rates is presented. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Palosz, W (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 36 TC 7 Z9 7 U1 2 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD JUL PY 2000 VL 216 IS 1-4 BP 273 EP 282 DI 10.1016/S0022-0248(00)00400-0 PG 10 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 336DE UT WOS:000088286000036 ER PT J AU Palosz, W Alexander, HA Grasza, K AF Palosz, W Alexander, HA Grasza, K TI Thermochemical model and experimental studies on physical vapor transport of lead telluride-selenide SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE PbSeTe; vapor growth; IV-VT; PVT; residual gas ID CADMIUM-ZINC TELLURIDE; SINGLE-CRYSTALS; GROWTH; SUBLIMATION; PB1-XSNXTE; PHASE AB Mass transport rate and composition of the transported material as a function of different process parameters like temperature, undercooling, inert gas pressure, and the source compactness for different PbTe1-xSex compositions were studied. With proper preparation procedures mass transport rates suitable for growth at the rate of 0.5-1 mm/h were obtained. Different composition non-uniformities in the deposited material were observed. Due to deviation of the PbTe-PbSe solid solution from ideality, congruent mass transport of the material takes place around X = 0.3. For other compositions an improved and even good uniformity can be achieved when a solid, pre-melted source material is used. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. Polish Acad Sci, Inst Phys, Warsaw, Poland. RP Palosz, W (reprint author), NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. NR 21 TC 2 Z9 2 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD JUL PY 2000 VL 216 IS 1-4 BP 283 EP 292 DI 10.1016/S0022-0248(00)00443-7 PG 10 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 336DE UT WOS:000088286000037 ER PT J AU Cabral-Cano, E Draper, G Lang, HR Harrison, CGA AF Cabral-Cano, E Draper, G Lang, HR Harrison, CGA TI Constraining the Late Mesozoic and early tertiary tectonic evolution of southern Mexico: Structure and deformation history of the Tierra Caliente region SO JOURNAL OF GEOLOGY LA English DT Article ID TERRANES; AMERICA; GRABEN; BASIN; GULF AB We analyze the structure and assess the deformation history of the Tierra Caliente Metamorphic Complex (TCMC) of southern Mexico, where Laramide accretion of exotic terranes is in debate. The TCMC consists of a south-plunging antiform fault that is bounded on both its eastern and western flanks. Tierra Caliente Metamorphic Complex rocks show at least two phases of compressional deformation. The first and most prominent records a mean tectonic transport direction of 068 degrees. This phase is responsible for east-verging asymmetrical folding and thrusting of both metamorphic and superjacent sedimentary rocks. The second phase has an average transport direction of 232 degrees and is restricted to the western portion of the TCMC. A third phase is responsible for normal faulting. Lack of discernible deformation before Late Cretaceous time indicates that the main deformation phase is coincident with Laramide orogenesis elsewhere in the North American Cordillera. The stratigraphy, structure, and deformational history of the TCMC do not require accretion of exotic terranes. We explain the Mesozoic tectonostratigraphic evolution of the TCMC in terms of deposition and deformation of Mesozoic volcanic and sedimentary strata over the attenuated continental crust of the North American plate. C1 Natl Autonomous Univ Mexico, Inst Geofis, Mexico City 04510, DF, Mexico. Florida Int Univ, Miami, FL 33199 USA. Jet Propulsion Lab, CALTECH, Pasadena, CA 91109 USA. Univ Miami, RSMAS Marine Geology Geophysics, Miami, FL 33149 USA. RP Cabral-Cano, E (reprint author), Natl Autonomous Univ Mexico, Inst Geofis, Ciudad Univ, Mexico City 04510, DF, Mexico. RI Harrison, Christopher/A-7726-2009; OI harrison, christopher/0000-0003-4088-7630 NR 49 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0022-1376 J9 J GEOL JI J. Geol. PD JUL PY 2000 VL 108 IS 4 BP 427 EP 446 DI 10.1086/314414 PG 20 WC Geology SC Geology GA 334NK UT WOS:000088192400004 ER PT J AU Khazanov, GV Stone, NH Krivorutsky, EN Liemohn, MW AF Khazanov, GV Stone, NH Krivorutsky, EN Liemohn, MW TI Current-produced magnetic field effects on current collection SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID COLLISIONLESS MAGNETOPLASMA; CYLINDRICAL PROBE AB Current collection by an infinitely long, conducting cylinder in a magnetized plasma, taking into account the magnetic field of the collected current, is discussed. A region of closed magnetic surfaces disconnects the cylinder from infinity. Owing to this, the collected current depends on the ratio between this region and the plasma sheath region and, under some conditions, current reduction arises. It is found that the upper bound limit of current collection is reduced due to this change of magnetic field topology. The effect can be substantial even if the orbit-limited model of current collection is valid. This model is used to find the reduction of the total current collected by a cylinder (e.g., a bare tether). It is shown that this effect strongly depends on plasma density. The results are applied to a tether system in the ionosphere, and it is found that current reduction can be significant for long tethers in typical dayside ionospheric conditions. C1 Univ Alaska, Inst Geophys, Fairbanks, AK 99775 USA. Univ Michigan, Space Phys Res Lab, Ann Arbor, MI 48109 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Khazanov, GV (reprint author), Univ Alaska, Inst Geophys, 903 Koykuk Dr, Fairbanks, AK 99775 USA. RI Liemohn, Michael/H-8703-2012 OI Liemohn, Michael/0000-0002-7039-2631 NR 22 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD JUL 1 PY 2000 VL 105 IS A7 BP 15835 EP 15842 DI 10.1029/2000JA000039 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 330KW UT WOS:000087962100011 ER PT J AU Ness, NF Acuna, MH Connerney, JEP Kliore, AJ Breus, TK Krymskii, AM Cloutier, P Bauer, SJ AF Ness, NF Acuna, MH Connerney, JEP Kliore, AJ Breus, TK Krymskii, AM Cloutier, P Bauer, SJ TI Effects of magnetic anomalies discovered at Mars on the structure of the Martian ionosphere and solar wind interaction as follows from radio occultation experiments SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PHOBOS OBSERVATIONS; RAM PRESSURE; BOW SHOCK; FIELD; VENUS; MODEL; ATMOSPHERE; MAGNETOPAUSE; TEMPERATURE AB The slopes of the electron density profiles obtained by radio occultation experiments at Mars revealed different variations with solar zenith angle in comparison with behavior of the electron density profiles in the magnetic field free ionosphere of Venus. The results obtained by the Mars-Global-Surveyor (MGS) spacecraft show the existence of highly variable and very localized magnetic fields of crustal origin at Mars. Addressing the difference between the ionosphere at Venus and Mars, the scale heights of electron density profiles obtained by radio occultation methods onboard Mariner 9 and Viking 1 are analyzed at altitudes higher than the topside boundary of the photoequlibrium region in the magnetic field-free ionosphere. The local increase of the mean scale height in the altitude region 180-250 km is assumed to be either an effect of a nonhorizontal magnetic field associated with the magnetic anomalies or diffusive equilibrium in the magnetic field free ionosphere. The areas where the scale height of electron density profile,is increased in comparison with average one have been selected. The angle between the magnetic field measured by MGS MAG/ER at altitudes 120-250 km and local zenith direction is investigated throughout these selected areas. C1 Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Rice Univ, Dept Space Phys & Astron, Houston, TX 77098 USA. Russian Acad Sci, Space Res Inst, Moscow 117810, Russia. Graz Univ, Inst Meteorol & Geophys, A-8010 Graz, Austria. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ness, NF (reprint author), Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. RI connerney, john/I-5127-2013; OI Bauer, Siegfried/0000-0003-4213-2047 NR 38 TC 62 Z9 65 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD JUL 1 PY 2000 VL 105 IS A7 BP 15991 EP 16004 DI 10.1029/1999JA000212 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 330KW UT WOS:000087962100023 ER PT J AU Kaiser, ML Zarka, P Kurth, WS Hospodarsky, GB Gurnett, DA AF Kaiser, ML Zarka, P Kurth, WS Hospodarsky, GB Gurnett, DA TI Cassini and Wind stereoscopic observations of Jovian nonthermal radio emissions: Measurement of beam widths SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ASTRONOMY OBSERVATIONS; HECTOMETRIC RADIATION; DECAMETRIC ARCS; JUPITER; GALILEO; BAND AB During two intervals in 1999, simultaneous observations of Jupiter's decametric and hectometric radio emissions were made with the Cassini radio and plasma wave instrument (RPWS) and the radio and plasma wave instrument (WAVES) on the Wind spacecraft in Earth orbit. During January the Jovian longitude difference between the two spacecraft was about 5 degrees, whereas for the August-September Earth flyby of Cassini, the angle ranged from 0 degrees to about 2.5 degrees (the Jovicentric latitudinal difference was <0.3 degrees during both intervals). With these separations the instantaneous widths of the walls of the hollow conical radiation beams of some of the decametric area were measured by cross correlating dynamic spectra. The results suggest that the typical width is approximately 1.5 degrees +/- 0.5 degrees. The conical beams seem to move at Io's revolution rate for Io-controlled arcs. Additionally, some of the nonarc hectometric wavelength emissions show some properties of both wide and very narrow beam widths. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Observ Paris, DESPA, F-92195 Meudon, France. Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. RP Kaiser, ML (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. OI Hospodarsky, George/0000-0001-9200-9878; Kurth, William/0000-0002-5471-6202 NR 28 TC 25 Z9 25 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD JUL 1 PY 2000 VL 105 IS A7 BP 16053 EP 16062 DI 10.1029/1999JA000414 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 330KW UT WOS:000087962100027 ER PT J AU Tu, KY Munir, MS Mease, KD Bayard, DS AF Tu, KY Munir, MS Mease, KD Bayard, DS TI Drag-based predictive tracking guidance for Mars precision landing SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID SHUTTLE ENTRY GUIDANCE AB An atmospheric entry guidance law is developed for a range of low-lift landers consistent with those expected to be flown in NASA's upcoming series of Mars exploration missions. The lander flight path is controlled by bank angle adjustments. The guidance law is a drag-based predictive tracking guidance law similar to that used by NASA's Space Shuttle. Modifications to the Shuttle law are introduced to accommodate the very low-lift capability of the expected landers, as well as additional constraints due to using a fixed trim angle and a low bandwidth attitude control system. Applying the modified guidance law to a representative entry scenario taken from the NASA Mars Surveyor 2001 mission, Monte Carlo simulation results indicate that a lander with a maximum lift to-drag ratio of only 0.12 can be guided to within 10 km of a specified parachute deployment latitude/longitude point with approximately 99% certainty. Additional dynamic pressure and Mach number constraints required for successful parachute deployment are also shown to be satisfied with approximately 99% certainty. Results for landers with maximum lift-to-drag ratios of 0.18 and 0.06 are included for comparison. C1 Univ Calif Irvine, Dept Mech & Aerosp Engn, Irvine, CA 92697 USA. CALTECH, Jet Prop Lab, Auton & Control Sect, Pasadena, CA 91109 USA. RP Tu, KY (reprint author), Univ Calif Irvine, Dept Mech & Aerosp Engn, Irvine, CA 92697 USA. OI Mease, Kenneth D/0000-0002-5625-8233 NR 14 TC 42 Z9 49 U1 3 U2 8 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 JUL-AUG PY 2000 VL 23 IS 4 BP 620 EP 628 DI 10.2514/2.4607 PG 9 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 335TH UT WOS:000088260500006 ER PT J AU Shieh, LS Wang, WM Bain, J Sunkel, JW AF Shieh, LS Wang, WM Bain, J Sunkel, JW TI Design of lifted dual-rate digital controllers for X-38 vehicle SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID CONTROL SYSTEMS; LINEAR-SYSTEMS; REDESIGN AB A new state-matching digital redesign method to find the lifted dual-rate pulse-amplitude-modulated (PAM) and pulse-width modulated (PWM) digital controllers from a predesigned, state-feedback, continuous-time controller is presented. The proposed method provides close matching of the states of the continuous-time controlled analog system with those of the digitally redesigned system (including intersample behavior). The redesigned lifted dual-rate controller enables the digitally controlled X-38 vehicle to track the desired trajectory while remaining insensitive to modeling parameters, initial conditions, and exogenous disturbances for larger sample times than existing methods. The X-38 will require a PAM controller for commanding the electromechanical actuators that operate its aerodynamic surfaces far Eight in the atmosphere, PWM control will be used to command the reaction control jets during orbital operations. The proposed method provides a new alternative for indirect digital design of state-feedback multivariable continuous-time systems. C1 Univ Houston, Dept Elect & Comp Engn, Houston, TX 77204 USA. NASA, Lyndon B Johnson Space Ctr, Natl Res Council Associate, Houston, TX 77058 USA. Univ Colorado, Dept Aerosp Engn, Boulder, CO 80309 USA. RP Shieh, LS (reprint author), Univ Houston, Dept Elect & Comp Engn, Houston, TX 77204 USA. NR 24 TC 22 Z9 22 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 JUL-AUG PY 2000 VL 23 IS 4 BP 629 EP 639 DI 10.2514/2.4608 PG 11 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 335TH UT WOS:000088260500007 ER PT J AU Maghami, PG AF Maghami, PG TI Model refinement using eigensystem assignment SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB A novel approach for the refinement of finite-element-based analytical models elf flexible structures is presented. The proposed approach models the possible refinements in the mass, damping, and stiffness matrices of the finite element model in the form of a constant gain feedback with acceleration, velocity, and displacement measurements, respectively. Once the free elements of the structural matrices have been defined, the problem of model refinement reduces to obtaining position, velocity, and acceleration gain matrices with appropriate sparsity that reassign a desired subset of the eigenvalues of the model, along with partial mode shapes, from their baseline values to those obtained from system identification test data. A sequential procedure is used to assign one conjugate pair of eigenvalues at each step using symmetric output feedback gain matrices, and the eigenvectors are partially assigned, while ensuring that the eigenvalues assigned in the previous steps are not disturbed. The procedure can also impose that gain matrices be dissipative to guarantee the stability of the refined model. A numerical example, involving finite element model refinement for a structural testbed at NASA Langley Research Center (Controls-Structures-Interaction Evolutionary model) is presented to demonstrate the feasibility of the proposed approach. C1 NASA, Langley Res Ctr, Guidance & Control Branch, Hampton, VA 23681 USA. RP Maghami, PG (reprint author), NASA, Langley Res Ctr, Guidance & Control Branch, Hampton, VA 23681 USA. NR 6 TC 5 Z9 11 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 2000 VL 23 IS 4 BP 683 EP 692 DI 10.2514/2.4584 PG 10 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 335TH UT WOS:000088260500013 ER PT J AU Lorenzo, CF Holmes, MS Ray, S AF Lorenzo, CF Holmes, MS Ray, S TI Nonlinear life-extending control of a rocket engine SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID DAMAGE-MITIGATING CONTROL; MECHANICAL SYSTEMS C1 NASA, John Glenn Res Ctr Lewis Field, Instrumentat & Control Technol Div, Cleveland, OH 44135 USA. Penn State Univ, Dept Engn Mech, University Pk, PA 16802 USA. RP Lorenzo, CF (reprint author), NASA, John Glenn Res Ctr Lewis Field, Instrumentat & Control Technol Div, 21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 14 TC 2 Z9 4 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 2000 VL 23 IS 4 BP 759 EP 762 DI 10.2514/2.4599 PG 4 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 335TH UT WOS:000088260500027 ER PT J AU Maiwald, F Lewen, F Ahrens, V Beaky, M Gendriesch, R Koroliev, AN Negirev, AA Paveljev, DG Vowinkel, B Winnewisser, G AF Maiwald, F Lewen, F Ahrens, V Beaky, M Gendriesch, R Koroliev, AN Negirev, AA Paveljev, DG Vowinkel, B Winnewisser, G TI Pure rotational spectrum of HCN in the terahertz region: Use of a new planar Schottky diode multiplier SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Letter ID SPECTROSCOPY; LASER; THZ C1 Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany. RP Maiwald, F (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 35 Z9 35 U1 0 U2 2 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD JUL PY 2000 VL 202 IS 1 BP 166 EP 168 DI 10.1006/jmsp.2000.8118 PG 3 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 327JN UT WOS:000087790900018 ER PT J AU Raffaelle, RP Harris, JD Hehemann, D Scheiman, D Rybicki, G Hepp, AF AF Raffaelle, RP Harris, JD Hehemann, D Scheiman, D Rybicki, G Hepp, AF TI A facile route to thin-film solid state lithium microelectronic batteries SO JOURNAL OF POWER SOURCES LA English DT Article DE lithium; secondary batteries; polymers; thin films; MCM ID POLYMER ELECTROLYTES AB We describe the synthesis and characterization of a thin-film solid state lithium rechargeable battery, This battery was designed for integration into a multi-chip module (MCM). The battery consists of a spin-on Ag2WO4 - polymer cathode, a lithium hexaflurophosphate - polymer-impregnated microporous nylon membrane electrolytic separator, and a lithium foil anode. Kapton(TM) was used as the substrate and encapsulating top layer of the battery. The battery had a total area of approximately 4.0 cm(2) thickness of 0.6 mm, and weighed 0.4 g. The battery had an open circuit voltage of 3.5 V and was able to deliver a current density of 0.05 mA/cm(2) for 1.5 h while maintaining a voltage above 2.0 V. The battery was cycled over 12,000 times between 3.5 and 2.0 V using a constant discharging current density of 0.1 mA/cm(2) and charging current density of 0.05 mA/cm(2). The battery was designed for integration into a standard 96 pin Kovar/Glass Bead quad-flatpack programmable MCM (1.42 x 1.42 x 0.16 in.). The charging and discharging characteristics of this battery are presented and discussed in terms of its intended application. (C) 2000 Elsevier Science S.A. All rights reserved. C1 Rochester Inst Technol, Coll Sci, Dept Phys, Rochester, NY 14623 USA. Kent State Univ, Sch Technol, Kent, OH 44242 USA. Ohio Aerosp Inst, Brook Pk, OH 44142 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Raffaelle, RP (reprint author), Rochester Inst Technol, Coll Sci, Dept Phys, 85 Lomb Mem Dr, Rochester, NY 14623 USA. NR 15 TC 8 Z9 13 U1 1 U2 9 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0378-7753 J9 J POWER SOURCES JI J. Power Sources PD JUL PY 2000 VL 89 IS 1 BP 52 EP 55 DI 10.1016/S0378-7753(00)00392-X PG 4 WC Chemistry, Physical; Electrochemistry; Energy & Fuels; Materials Science, Multidisciplinary SC Chemistry; Electrochemistry; Energy & Fuels; Materials Science GA 328XM UT WOS:000087877100007 ER PT J AU Hall, CA Kerslake, TW AF Hall, CA Kerslake, TW TI Thermal state-of-charge of space solar dynamic heat receivers SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT 2nd International Conference on Advanced Energy Conversion Systems and Related Technologies (RAN98) CY DEC 01-03, 1998 CL NAGOYA UNIV, NAGOYA, JAPAN HO NAGOYA UNIV ID ENERGY-STORAGE; PHASE-CHANGE AB A theoretical framework is developed to determine the so-called thermal state-of-charge in solar heat receivers employing encapsulated phase change materials that undergo cyclic melting and freezing, and results are presented for the solar heat receiver component of NASA John II. Glenn Research Center at Lewis Field's Ground Test Demonstration System. The concepts of available power, virtual source temperature, and minimum gas available power are used as the bases for determining the state-of-charge. The state-of-charge is characterized in the subcooled, two-phase, and superheat regimes as well as startup, transition, and balanced-orbit modes. Baseline conjugate and primary state-of-charge curves are generated based on a priori known baseline system operating conditions through measurable parameters. Results indicate that for the baseline primary state-of-charge curve in balanced-orbit mode, there is a 33% energy margin (from the minimum state-of-charge line) at sunrise that indicates safe operation of the solar dynamic system; at sunset, the primary state-of-charge reaches 76%. Results for parametric changes indicate that the state-of-charge in the sensible regimes is completely reversed in the latent regime. C1 Univ New Orleans, Dept Mech Engn, New Orleans, LA 70148 USA. Howard Univ, Coll Engn Architecture & Comp Sci, Washington, DC 20059 USA. NASA, John H Glenn Res Ctr Lewis Field, Power & Prop Off, Anal & Management Branch, Cleveland, OH 44135 USA. RP Hall, CA (reprint author), Univ New Orleans, Dept Mech Engn, New Orleans, LA 70148 USA. NR 11 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 2000 VL 16 IS 4 BP 666 EP 675 DI 10.2514/2.5626 PG 10 WC Engineering, Aerospace SC Engineering GA 336NJ UT WOS:000088308900024 ER PT J AU Ustinov, EA AF Ustinov, EA TI Weighting functions with separated maxima and kernels of inverse problems for ground-based passive remote sensing SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article AB An approach is presented for the construction of weighting functions for temperature and mixing ratio retrievals for ground-based passive remote sensing that have maxima separated from the ground. The necessary mathematical and physical framework is also presented. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. RP Ustinov, EA (reprint author), CALTECH, Jet Prop Lab, Div Earth & Space Sci, 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 17 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 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD JUL 1 PY 2000 VL 66 IS 1 BP 55 EP 67 DI 10.1016/S0022-4073(99)00220-4 PG 13 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 298RR UT WOS:000086153400005 ER PT J AU Giver, LP Chackerian, C Varanasi, P AF Giver, LP Chackerian, C Varanasi, P TI Visible and near-infrared (H2O)-O-16 line intensity corrections for HITRAN-96 SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID INTERACTING VIBRATIONAL-STATES; HIGH-RESOLUTION SPECTRUM; WATER-VAPOR; CM-1; POSITIONS; ABSORPTION; CLOUDS AB Systematic differences are apparent between the absolute intensities of water vapor lines in the 8036-22,657 cm(-1) region listed in the HITRAN-96 database and those reported in the five original articles which constitute the sources for the database. This note suggests corrections which should be made to the HITRAN line intensities of various water bands in this region to achieve compliance with the measured intensities. A correction which increases the intensities by 8-14% should be applied in the 9500-12,861 cm(-1) region. The correction decreases the line intensities in the 8036-9482 and 13,200-22,657 cm(-1) intervals. The correction factor is exp[ - E"(2hc/k)(1/T - 1/T')] in these regions, where T = 296 K and T' is the measurement temperature. This correction becomes significant at higher values of E", it decreases the line intensities in HITRAN by about 19% at E" = 1400 cm(-1). (C) 2000 Published by Elsevier Science Ltd. All rights reserved. C1 SUNY Stony Brook, Inst Terr & Planetary Atmospheres, Stony Brook, NY 11794 USA. NASA, Ames Res Ctr, Atmospher Phys Branch, Moffett Field, CA 94035 USA. RP Varanasi, P (reprint author), SUNY Stony Brook, Inst Terr & Planetary Atmospheres, Stony Brook, NY 11794 USA. NR 11 TC 96 Z9 97 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD JUL 1 PY 2000 VL 66 IS 1 BP 101 EP 105 DI 10.1016/S0022-4073(99)00223-X PG 5 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 298RR UT WOS:000086153400008 ER PT J AU Gupta, RN AF Gupta, RN TI Aerothermodynamic analysis of Stardust Sample Return Capsule with coupled radiation and ablation SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT AIAA 37th Aerospace Sciences Meeting and Exhibit CY JAN 11-14, 1999 CL RENO, NEVADA SP Amer Inst Aeronaut & Astronaut ID NONEQUILIBRIUM AB An aerothermodynamic analysis of the forebody aeroshell of the Stardust Sample Return Capsule is carried out by using the axisymmetric viscous shock-layer equations with and without fully coupled radiation and ablation, Formulation of the viscous shock-layer equations with shoulder radius as the length scale and implementation of the Vigneron pressure condition allow resolution of the flowfield over the shoulder. With a predominantly supersonic outflow over the shoulder, a globally iterated solution of viscous shock-layer equations can be obtained. The stagnation-point results are obtained along a specified trajectory, whereas detailed calculations along the body are provided at the peak-heating point. The equilibrium calculations with ablation injection are the focus of the present study because of the lack of a general chemical nonequilibrium analysis that accounts for both surface and flowfield effect. The equilibrium calculations also provide a simple way to conserve surface land flowfield) elemental composition for the current small ablation injection rates, where the surface elemental composition is a mixture of freestream and ablator elements. Therefore, the coupled laminar and turbulent flow solutions with radiation and ablation are obtained by using the equilibrium flow chemistry, whereas a nonequilibrium chemistry model is used for solutions without ablation and turbulence. Various computed results are compared with those obtained by the other researchers. C1 NASA, Langley Res Ctr, Aero & Gas Dynam Div, Hampton, VA 23681 USA. RP Gupta, RN (reprint author), NASA, Langley Res Ctr, Aero & Gas Dynam Div, Hampton, VA 23681 USA. NR 26 TC 14 Z9 14 U1 0 U2 2 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 JUL-AUG PY 2000 VL 37 IS 4 BP 507 EP 514 DI 10.2514/2.3592 PG 8 WC Engineering, Aerospace SC Engineering GA 341HD UT WOS:000088584200014 ER PT J AU Brown, AM AF Brown, AM TI Combining loads from random and harmonic excitation using the Monte Carlo technique SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article C1 NASA, George C Marshall Space Flight Ctr, Struct Dynam & Loads Grp, Huntsville, AL 35812 USA. RP Brown, AM (reprint author), Univ N Carolina, Dept Mech Engn, Charlotte, NC 28223 USA. NR 9 TC 0 Z9 0 U1 2 U2 2 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 JUL-AUG PY 2000 VL 37 IS 4 BP 541 EP 543 DI 10.2514/2.3599 PG 3 WC Engineering, Aerospace SC Engineering GA 341HD UT WOS:000088584200020 ER PT J AU Fox, DS Opila, EJ Hann, RE AF Fox, DS Opila, EJ Hann, RE TI Paralinear oxidation of CVD SiC in simulated fuel-rich combustion SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID DEPOSITED SILICON-CARBIDE; SIO2 SCALE VOLATILITY; WATER-VAPOR; WET OXYGEN; THERMOCHEMISTRY; MOLECULES; KINETICS; NITRIDE; MODEL AB The oxidation kinetics of CVD SiC were measured by thermogravimetric analysis (TGA) in a 4H(2). 12H(2)O . 10CO . 7CO(2). 67N(2) gas mixture flowing at 0.44 cm/s at temperatures between 1300 degrees and 1450 degrees C in fused quartz furnace tubes at 1 atm total pressure. The SiC was oxidized to form solid SiO2. At greater than or equal to 1350 degrees C, the SiO2 was in turn volatilized, Volatilization kinetics were consistent with the thermodynamic predictions based on SiO formation. These two simultaneous reactions resulted in overall paralinear kinetics. A curve fitting technique was used to determine the linear and parabolic rate constants from the paralinear kinetic data, Volatilization of the protective SiO2 scale resulted in accelerated consumption of SIG. Recession rates under conditions more representative of actual combustors were estimated from the furnace data. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Cleveland State Univ, Dept Chem Engn, Cleveland, OH 44115 USA. RP Fox, DS (reprint author), NASA, Glenn Res Ctr, Lewis Field, Cleveland, OH 44135 USA. NR 32 TC 13 Z9 13 U1 1 U2 4 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 USA SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD JUL PY 2000 VL 83 IS 7 BP 1761 EP 1767 PG 7 WC Materials Science, Ceramics SC Materials Science GA 333HF UT WOS:000088124300030 ER PT J AU Kitaplioglu, C Acree, CW Light, JS AF Kitaplioglu, C Acree, CW Light, JS TI XV-15 aeroacoustic testing at NASA Ames SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article; Proceedings Paper CT 23rd European Rotorcraft Forum CY SEP 16-18, 1997 CL DRESDEN, GERMANY AB Two tests were completed by NASA Ames Research Center to measure the acoustics and performance of an XV-15 rotor. These tests were a flight test of the XV-15 aircraft and a wind tunnel test of a single, full-scale XV-15 rotor. Acoustics and performance measurements were obtained for helicopter-mode forward flight and descent conditions. This paper summarizes the data obtained from these tests. Comparisons are made of blade loads and acoustics data obtained from the two tests. These comparisons indicate that, for the single test condition examined, pitch-link, flap bending, and chord bending loads agree reasonably well. No discernible effect was observed on blade bending loads by the presence of the wind tunnel test model or aircraft wing/fuselage. Several alternative methods of correlating flight and wind tunnel test data are discussed. These comparisons provide insight into both wind tunnel and flight test experimental techniques and capabilities. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kitaplioglu, C (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 14 TC 0 Z9 0 U1 0 U2 1 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD JUL PY 2000 VL 45 IS 3 BP 191 EP 198 PG 8 WC Engineering, Aerospace SC Engineering GA 465QV UT WOS:000170602200005 ER PT J AU Kottapalli, S AF Kottapalli, S TI Neural network research on validating experimental tilt-rotor performance SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article; Proceedings Paper CT AIAA 16th Applied Aerodynamics Conference CY JUN 15-18, 1998 CL ALBUQUERQUE, NEW MEXICO SP Amer Inst Aeronaut & Astronaut AB Results from a neural network study to validate full-scale XV-15 tilt-rotor experimental hover and forward flight data are presented. In the context of the present study, neural-network-based test data validation includes the following: test data representation, test data quality assessment (e.g., isolating "bad" test points), and finally, for outdoor hover measurements, wind correction procedure development. Two test databases, acquired during separate tests conducted at NASA Ames, were used. These two isolated XV-15 rotor test databases were obtained from tests in the 80- by 120-Foot Wind Tunnel and an outdoor hover test facility. Neural networks were successfully used to represent and assess the quality of full-scale tilt-rotor hover and forward flight performance test data. The neural networks accurately captured tilt-rotor performance at steady operating conditions and it was shown that the wind tunnel forward flight performance test data were generally of very high quality. Compared to existing momentum-theory based wind corrections to outdoor hover performance, the present neural-network-procedure-based corrections were better. The present wind corrections procedure, based on a well-trained neural network, captured physical trends present in the outdoor hover test data that had been missed by the existing momentum-theory method. C1 NASA, Ames Res Ctr, Aeromech Branch, USA,NASA Rotorcraft Div, Moffett Field, CA 94035 USA. RP Kottapalli, S (reprint author), NASA, Ames Res Ctr, Aeromech Branch, USA,NASA Rotorcraft Div, Moffett Field, CA 94035 USA. NR 11 TC 2 Z9 2 U1 0 U2 1 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD JUL PY 2000 VL 45 IS 3 BP 199 EP 206 PG 8 WC Engineering, Aerospace SC Engineering GA 465QV UT WOS:000170602200006 ER PT J AU Corso, LM Popelka, DA Nixon, MW AF Corso, LM Popelka, DA Nixon, MW TI Design, analysis, and test of a composite tailored tiltrotor wing SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article; Proceedings Paper CT 53rd Annual Forum of the American-Helicopter-Society CY APR 29-MAY 01, 1997 CL VIRGINIA BEACH, VIRGINIA SP Amer Helicopter Soc AB A composite tailored tiltrotor wing was designed and tested on a 1/5-scale semispan aeroelastic model to demonstrate that composite tailoring techniques can be used to improve proprotor stability. Structural tailoring of the model-scale wing torque box is accomplished by using unbalanced composite laminates to modify wing bending torsion coupling, which is shown analytically to improve proprotor stability in high-speed airplane mode flight. The analytical methodologies used to develop the math models and predict the improved aeroelastic stability characteristics of the composite tailored wing are discussed. The frequency and damping characteristics of the critical wing beam and wing chord modes were measured during wind tunnel tests performed in airplane mode. The structural modes were excited at their natural frequencies and the damping values were measured from the time history decays following the excitations. The composite tailored wing aeroelastic stability boundary is compared to the stability boundary of a baseline untailored wing configuration. Finally, the modal damping and measured instabilities are then compared to analytical predictions for both the baseline and tailored wing configurations. C1 Bell Helicopter Textron Inc, Rotor Dynam, Ft Worth, TX USA. NASA, Langley Res Ctr, USA Vehicle Struct Directorate, Hampton, VA 23665 USA. RP Corso, LM (reprint author), Bell Helicopter Textron Inc, Rotor Dynam, Ft Worth, TX USA. NR 10 TC 4 Z9 5 U1 1 U2 2 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD JUL PY 2000 VL 45 IS 3 BP 207 EP 215 PG 9 WC Engineering, Aerospace SC Engineering GA 465QV UT WOS:000170602200007 ER PT J AU Ovryn, B Izen, SH AF Ovryn, B Izen, SH TI Imaging of transparent spheres through a planar interface using a high-numerical-aperture optical microscope SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID VECTOR DIFFRACTION; SCATTERING; SYSTEMS; LIGHT; POINT; MIE AB The details of a model used to predict the scattering of a plane polarized wave by a spherical particle as observed with a microscope are presented. The model accounts for the effect of a refractive interface on the outgoing scattered field and determines the image produced by a lens with high numerical aperture. The predictions of the model are verified by direct comparison with the experimentally observed scattering from polystyrene spheres in a fluid. (C) 2000 Optical Society of America [S0740-3232(00)02207-9] OCIS codes: 120.5820, 290.4020, 180.6900, 110.4100. C1 NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, Cleveland, OH 44135 USA. Case Western Reserve Univ, Dept Mech & Aerosp Engn, Cleveland, OH 44106 USA. Case Western Reserve Univ, Dept Math, Cleveland, OH 44106 USA. RP Ovryn, B (reprint author), NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, MS 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 28 TC 33 Z9 33 U1 1 U2 9 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 JUL PY 2000 VL 17 IS 7 BP 1202 EP 1213 DI 10.1364/JOSAA.17.001202 PG 12 WC Optics SC Optics GA 329FE UT WOS:000087895600007 ER PT J AU Hanuska, AR Scott, EP Daryabeigi, K AF Hanuska, AR Scott, EP Daryabeigi, K TI Thermal characterization of aerospace structures SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID CARBON-CARBON COMPOSITE; PROPERTY ESTIMATION; GENETIC ALGORITHMS; OPTIMIZATION AB Predicting the thermal performance of complex aerospace structures requires accurate knowledge of the thermal properties associated with the structure. It is desired, in this case, to measure the in situ properties of a complex as-built structure, not only to capture the thermal properties of each component hut also to capture interaction of components in the as-built structure. The overall goal of this study was, therefore, to develop and implement a nondestructive methodology to estimate the thermal properties associated with a complex aerospace structure. The structure considered was an outer wing subcomponent design fur the high-speed civil transport made from four different materials, including a honeycomb blanket. The thermal properties sought included both effective and individual material through-the-thickness thermal conductivities and volumetric heat capacities (product of density and specific heat) and the in-plane thermal conductivities of each material in the structure. In the estimation procedure an objective function containing both theoretical and experimental temperature histories was minimized using a genetic algorithm. One-dimensional experiments were implemented to estimate the through-the-thickness thermal conductivities and volumetric heat capacities, and two-dimensional experiments sere conducted to estimate the in-plane conductivities. These properties were successfully estimated despite the high degree of correlation and low sensitivity evident for many of the properties. C1 EI DuPont Inc, Cent Res & Dev, Chem Sci & Engn, Wilmington, DE 19880 USA. Univ Utah, Dept Mech Engn, Salt Lake City, UT 84112 USA. NASA, Langley Res Ctr, Thermal Struct Branch, Hampton, VA 23681 USA. RP Hanuska, AR (reprint author), EI DuPont Inc, Cent Res & Dev, Chem Sci & Engn, Wilmington, DE 19880 USA. NR 15 TC 3 Z9 3 U1 0 U2 2 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 JUL-SEP PY 2000 VL 14 IS 3 BP 322 EP 329 DI 10.2514/2.6548 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA 337DU UT WOS:000088342800005 ER PT J AU Probasco, DP Leger, TJ Wolff, JM Copenhaver, WW Chriss, RM AF Probasco, DP Leger, TJ Wolff, JM Copenhaver, WW Chriss, RM TI Variations in upstream vane loading with changes in back pressure in a transonic compressor SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT International Gas Turbine and Aeroengine Congress and Exhibition CY JUN 07-10, 1999 CL INDIANAPOLIS, INDIANA AB Dynamic loading of an inlet guide vane (IGV) in a transonic compressor is characterized by unsteady IGV surface pressures. These pressure data were acquired for two spanwise locations at a 105 percent speed operating condition, which produces supersonic relative Mach numbers over the majority of the rotor blade span. The back pressure of the compressor was varied to determine the effects from such changes. Strong bow shock interaction was evident in both experimental and computational results. Variations in the back pressure have significant influence on the magnitude and phase of the upstream pressure fluctuations. The largest unsteady surface pressure magnitude, 40 kPa, was obtained for the near-stall mass flow condition at 75 percent span and 95 percent chord Radial variation effects caused by the spanwise variation in relative Mach number were measured. Comparisons to a two-dimensional nonlinear unsteady blade/vane Navier-Stokes analysis show good agreement for the 50 percent span results in terms of IGV unsteady surface pressure. The results of the the study indicate that significant nonlinear bow shock influences exist on the IGV trailing edge due to the downstream rotor shock system. [S0889-504X(00)00303-2]. C1 Wright State Univ, Dept Mech & Mat Engn, Dayton, OH 45435 USA. USAF, Res Lab, Wright Patterson AFB, OH 44135 USA. NASA, Glenn Res Ctr, Cleveland, OH 43210 USA. RP Probasco, DP (reprint author), Wright State Univ, Dept Mech & Mat Engn, Dayton, OH 45435 USA. NR 12 TC 4 Z9 4 U1 0 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD JUL PY 2000 VL 122 IS 3 BP 433 EP 441 DI 10.1115/1.1303074 PG 9 WC Engineering, Mechanical SC Engineering GA 404NK UT WOS:000167106500009 ER PT J AU Halicioglu, T AF Halicioglu, T TI Chlorination of Si surfaces under strain conditions SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article ID SILICON; SI(100); MECHANISM AB Energetics for the chlorination process of Si(100)-(2x1) surfaces with an A-type single step edge were investigated under strain conditions. Strains applied uniaxially in the direction parallel to the exposed surfaces produced little or no effect on the energetics of the first chlorination step leading to fully Cl-covered terraces (one Cl attached to every exposed Si atom). The energy of the second chlorination step (leading to the formation of attached -SiCl2 units) taking place near a step-edge site. however, is affected considerably by the applied strain. The effect was found to be largest for strains applied in the direction perpendicular to the step edge. (C) 2000 American Vacuum Society. [S0734-211X(00)05404-4]. C1 NASA, Ames Res Ctr, Thermosci Inst, Moffett Field, CA 94035 USA. RP Halicioglu, T (reprint author), Dept Mat Sci & Engn, Stanford, CA 94305 USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 1071-1023 J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD JUL-AUG PY 2000 VL 18 IS 4 BP 2005 EP 2007 DI 10.1116/1.1305811 PG 3 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA 345UW UT WOS:000088834400033 ER PT J AU Fang, A Pierson, DL Mishra, SK Demain, AL AF Fang, A Pierson, DL Mishra, SK Demain, AL TI Relief from glucose interference in microcin B17 biosynthesis by growth in a rotating-wall bioreactor SO LETTERS IN APPLIED MICROBIOLOGY LA English DT Article ID SIMULATED MICROGRAVITY; ESCHERICHIA-COLI; SHEAR-STRESS; METABOLISM AB Glucose interference in production of microcin B17 by Escherichia coli ZK650 was decreased sevenfold by growth in a ground-based rotating-wall bioreactor operated in the simulated microgravity mode as compared with growth in flasks. When cells were grown in the bioreactor in the normal gravity mode, relief from glucose interference was even more dramatic, amounting to a decrease in glucose interference of over 100-fold. C1 MIT, Dept Biol, Fermentat Microbiol Lab, Cambridge, MA 02139 USA. NASA, Houston, TX 77058 USA. Univ Space Res Assoc, Lyndon B Johnson Space Ctr, Houston, TX USA. RP Demain, AL (reprint author), MIT, Dept Biol, Fermentat Microbiol Lab, 77 Massachusetts Ave, Cambridge, MA 02139 USA. NR 8 TC 13 Z9 13 U1 0 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0266-8254 J9 LETT APPL MICROBIOL JI Lett. Appl. Microbiol. PD JUL PY 2000 VL 31 IS 1 BP 39 EP 41 PG 3 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA 329WQ UT WOS:000087931800008 PM 10886612 ER PT J AU Lowe, TE Brill, RW Cousins, KL AF Lowe, TE Brill, RW Cousins, KL TI Blood oxygen-binding characteristics of bigeye tuna (Thunnus obesus), a high-energy-demand teleost that is tolerant of low ambient oxygen SO MARINE BIOLOGY LA English DT Review ID ACUTE TEMPERATURE-CHANGE; YELLOWFIN TUNA; KATSUWONUS-PELAMIS; SKIPJACK TUNA; RAINBOW-TROUT; PHYLOGENETIC-RELATIONSHIPS; CARDIOVASCULAR-RESPONSES; METABOLIC RATES; CARBON-DIOXIDE; BLUEFIN TUNA AB We found blood from bigeye tuna (Thunnus obesus) to have a significantly higher O-2 affinity than blood from other tunas. Its P-50 (partial pressure of oxygen, Po-2 required to roach 50% saturation) was 1.6 to 2.0 kPa (13 to 15 mmHg) when equilibrated with 0.5% CO2. Previous studies employing similar methodologies found blood from yellowfin tuna (T. albacares), skipjack tuna (Katsuwonus pelamis), and kawakawa (Euthynnus affinis) to have a P-50 of 2.8 to 3.1 kPa (21 to 23 mmHg). These observations suggest that bigeye tuna are more tolerant of low ambient oxygen than other tuna species, and support similar conclusions derived from laboratory whole-animal studies, depth-of-capture data, and directly-recorded vertical movements of fish in the open ocean. We also found the O-2 affinity of bigeye tuna blood to be essentially unaffected by a 10 C degrees open-system temperature change (as is the blood of all tuna species studied to date). The O-2 affinity of bigeye tuna blood was, however, more affected by a 10 C degrees closed-system temperature change than the blood of any tuna species yet examined. In other words, bigeye tuna blood displayed a significantly enhanced Bohr effect (change in log P-50 per unit change in plasma pH at P-50) when subjected to the inevitable changes in partial pressure of carbon dioxide (P-CO2) and plasma pH that accompany closed-system temperature shifts, than when subjected to changes in plasma pH accomplished by changing P-CO2 alone. In vivo, the resultant large decrease in O-2 affinity (i.e. the increase in P-50) that occurs as the blood of bigeye tuna is warmed during its passage through the vascular counter-current heat exchangers ensures adequate rates of O-2 off-loading in the swimming muscles of this high-energy-demand teleost. C1 Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Joint Inst Marine & Atmospher Res, Pelag Fisheries Res Program, Honolulu, HI 96822 USA. RP Brill, RW (reprint author), NOAA, Natl Marine Fisheries Serv, 2570 Dole St, Honolulu, HI 96822 USA. EM rbrill@honlab.nmfs.hawaii.edu NR 102 TC 50 Z9 51 U1 0 U2 22 PU SPRINGER HEIDELBERG PI HEIDELBERG PA TIERGARTENSTRASSE 17, D-69121 HEIDELBERG, GERMANY SN 0025-3162 EI 1432-1793 J9 MAR BIOL JI Mar. Biol. PD JUL PY 2000 VL 136 IS 6 BP 1087 EP 1098 DI 10.1007/s002270000255 PG 12 WC Marine & Freshwater Biology SC Marine & Freshwater Biology GA 338ZH UT WOS:000088452800014 ER PT J AU Wernet, MP AF Wernet, MP TI A flow field investigation in the diffuser of a high-speed centrifugal compressor using digital particle imaging velocimetry SO MEASUREMENT SCIENCE AND TECHNOLOGY LA English DT Article DE particle image velocimetry; particle tracking velocimetry; turbomachinery; compressors; compressor stall/surge ID ROTOR; PIV AB Digital particle imaging velocimetry (DPIV) has become a widely used optical diagnostic technique for the study of both transient and steady state hows. The DPIV technique provides instantaneous planar maps of the flow velocity. The challenges remaining are in implementing the PIV technique in real world test facilities, where the instantaneous, planar velocity measurements provide researchers with information in less time than traditional point-based measurement techniques. The instantaneous planar velocity measurements obtained using PIV make it an attractive technique for use in the study of the complex flow fields encountered in turbomachinery. This paper discusses techniques for optical access, light sheet delivery, CCD camera technology and particulate seeding requirements for the successful application of PIV to turbomachinery. Time-averaged results obtained in the diffuser region of a high-speed centrifugal compressor are presented and discussed. In addition, combined correlation/particle-tracking results yielding super-resolution velocity measurements are presented. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 33 TC 13 Z9 13 U1 1 U2 5 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0957-0233 EI 1361-6501 J9 MEAS SCI TECHNOL JI Meas. Sci. Technol. PD JUL PY 2000 VL 11 IS 7 BP 1007 EP 1022 DI 10.1088/0957-0233/11/7/316 PG 16 WC Engineering, Multidisciplinary; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 339FT UT WOS:000088467500017 ER PT J AU Gilmore, MS Head, JW AF Gilmore, MS Head, JW TI Sequential deformation of plains at the margins of Alpha Regio, Venus: Implications for tessera formation SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID GLOBAL DISTRIBUTION; MAGELLAN DATA; LADA-TERRA; VOLCANIC PLAINS; HISTORY; TECTONICS; EVOLUTION; PATTERNS; FEATURES; CORONAE AB The boundaries between the highly deformed tessera terrain and adjacent volcanic plains are primarily those of embayment, where the tessera are stratigraphically older than the plains. Previous studies show that <3% of these boundaries display evidence of tectonic tilting after the emplacement of the plains. One of these unusual boundaries is the western margin of Alpha Regio tessera, a zone similar to 100 km in width that separates the plains from the interior structures of Alpha. This zone is characterized by margin parallel, fine-scale (1-5 km) fractures, graben, and ridges that truncate and postdate the broad-scale (10-30 km) ridges and troughs of the interior of Alpha. The western margin is embayed by several volcanic plains units that are progressively tilted and deformed by graben with closer proximity to Alpha Regio. The earliest deformation of the plains consists of northeast-trending graben similar to 1 km in width that are similar in morphology and spacing to graben that deform intratessera plains and plains at the eastern boundary of Alpha. Northwest-trending graben then formed over an interval marked by the emplacement of two additional plains units; their similarity to northwest-trending structures emanating from Eve corona and the Lada Terra rift suggests a possible genetic relationship. The tilting of the plains adjacent to western Alpha implies relative vertical movement of the margin, either uplift of tessera or downwarping of plains subsequent to the formation and relaxation of the interior of Alpha Regio. Subsidence of plains at this locale is supported by the presence of a basin to the west of Alpha surrounded by a fracture belt contiguous with western Alpha. Thus, the fractures and deformation at the western boundary of Alpha may be related to the formation of a basin to the west of Alpha with some influence from the northernmost extension of the Lada Terra rift. Such a basin is not present at a section along the eastern boundary of Alpha Regio, where the origin of tilted plains remains equivocal. We conclude that the deformation along the western margin of Alpha Regio is not directly related to the process of tessera formation but is an example of tessera modification and is consistent with the stratigraphic position of tessera as the oldest unit observed on Venus. C1 Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. RP Gilmore, MS (reprint author), CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. RI Gilmore, Martha/G-5856-2011 NR 65 TC 12 Z9 12 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD JUL PY 2000 VL 35 IS 4 BP 667 EP 687 PG 21 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 341YC UT WOS:000088617700006 ER PT J AU Chabot, NL Drake, MJ AF Chabot, NL Drake, MJ TI Crystallization of magmatic iron meteorites: The effects of phosphorus and liquid immiscibility SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID TRACE-ELEMENT FRACTIONATION; FE-NI-S; CHEMICAL CLASSIFICATION; ISOTOPIC COMPOSITION; GROUP-IIIAB; SILVER; RE; OS; SYSTEMATICS; METAL AB Magmatic iron meteorites are commonly thought to have formed by fractional crystallization of the metallic cores of asteroid-sized bodies. As fractional crystallization proceeds, light elements such as P and S become enriched in the molten portion of the core. The light element content of the metallic liquid influences the partitioning behavior of trace elements and may cause liquid immiscibility to occur. The elemental trends observed in magmatic iron meteorites may have been affected by both of these processes. We have examined experimentally the effect of P on the solid-metal-liquid-metal partitioning behavior of Ag and Pd, Re and Os, two element pairs used to date iron meteorite processes. Phosphorus has no effect on the partition coefficient of either Ag or Pd, which are incompatible and identical within experimental error. Compatible Re and Os also have identical partitioning behavior, within experimental error, and show increasing compatibility in the solid metal with increasing P content of the metallic liquid. Including the effects of both S and P on the partitioning behavior of Re and Os, simple fractional crystallization calculations can reproduce the large variation of Re and Os concentrations observed in four magmatic iron meteorite groups but have difficulty matching the later crystallizing portions of the trends. We have also conducted experiments with three phases-solid metal and two immiscible metallic liquids-to determine the location of the liquid immiscibility field near conditions thought to be relevant to magmatic iron meteorites. Our results show a significantly smaller liquid immiscibility field as compared to the previously published Fe-P-S phase diagram. Our revised phase diagram suggests that liquid immiscibility was encountered during the crystallization of asteroidal cores, but much later during the crystallization process than predicted by the previously published diagram. C1 Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. RP Chabot, NL (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code SN2, Houston, TX 77058 USA. RI Chabot, Nancy/F-5384-2015 OI Chabot, Nancy/0000-0001-8628-3176 NR 30 TC 27 Z9 28 U1 1 U2 8 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD JUL PY 2000 VL 35 IS 4 BP 807 EP 816 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 341YC UT WOS:000088617700019 ER PT J AU Schnetzler, CC French, BM AF Schnetzler, CC French, BM TI Louis W. Walter (1933-2000) - Memorial SO METEORITICS & PLANETARY SCIENCE LA English DT Biographical-Item C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Smithsonian Inst, Natl Museum Nat Hist, Dept Mineral Sci, Washington, DC 20560 USA. RP Schnetzler, CC (reprint author), NASA, Goddard Space Flight Ctr, Mail Code 923, Greenbelt, MD 20771 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD JUL PY 2000 VL 35 IS 4 BP 881 EP 881 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 341YC UT WOS:000088617700027 ER PT J AU Evans, JW Evans, JY Ghaffarian, R Mawer, A Lee, KT Shin, CH AF Evans, JW Evans, JY Ghaffarian, R Mawer, A Lee, KT Shin, CH TI Simulation of fatigue distributions for ball grid arrays by the Monte Carlo method SO MICROELECTRONICS RELIABILITY LA English DT Article; Proceedings Paper CT ASME Interpack Conference CY 1999 CL LAHAINA, HAWAII SP ASME AB Any approach to qualification of advanced technologies during product development must include an assessment of variation expected in product life over the life cycle. However, testing product design options in development, to approach an optimal design is costly and time consuming. Hence, simulation of product life distributions for virtual qualification can be a valuable tool to evaluate and qualify design options. This paper presents a physics of failure-based approach to virtual qualification of advanced area array assemblies against solder fatigue failure. The approach applies Monte Carlo simulation to evaluate solder joint fatigue life distributions, given material property Variations and manufacturing capabilities, Preliminary results using the simple Engelmaier model as the basis of simulations are presented. Simulation results are compared to data accumulated from two test environments and two ball grid array product types. The results reveal some of the limitations of the Engelmaier model as a basis for simulation. They also show the potential of this approach to virtual qualification for design and manufacturing capability assessment in development. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Ajou Univ, Inst Adv Engn, Dept Syst Engn, Kyonggi Do 449860, South Korea. Daewoo Elect Ltd, Seoul, South Korea. CALTECH, Jet Prop Lab, Pasadena, CA USA. Motorola Corp, Austin, TX USA. Inst Adv Engn, Mfg Technol Lab, Seoul, South Korea. RP Evans, JW (reprint author), Ajou Univ, Inst Adv Engn, Dept Syst Engn, Ying In Res Complex,POB 25, Kyonggi Do 449860, South Korea. NR 16 TC 15 Z9 15 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0026-2714 J9 MICROELECTRON RELIAB JI Microelectron. Reliab. PD JUL PY 2000 VL 40 IS 7 BP 1147 EP 1155 DI 10.1016/S0026-2714(00)00042-1 PG 9 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA 349KN UT WOS:000089044400009 ER PT J AU Ghaffarian, R AF Ghaffarian, R TI Chip scale package issues SO MICROELECTRONICS RELIABILITY LA English DT Article AB Availability of board solder joint reliability information is critical to the wider implementation of chip scale packages (CSPs). The JPL-led CSP consortia of enterprises representing government agencies and private companies have joined together to pool in-kind resources for developing the quality and reliability of CSPs for variety of projects. In the process of building the consortia test vehicles, many challenges were identified regarding various aspects of technology implementation. This paper will present our experience in the areas of technology implementation challenges, including design and building both standard and microvia boards, and assembly of two types of CSP test vehicles. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ghaffarian, R (reprint author), CALTECH, Jet Prop Lab, MS 125-152,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 3 TC 3 Z9 3 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0026-2714 J9 MICROELECTRON RELIAB JI Microelectron. Reliab. PD JUL PY 2000 VL 40 IS 7 BP 1157 EP 1161 DI 10.1016/S0026-2714(00)00041-X PG 5 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA 349KN UT WOS:000089044400010 ER PT J AU Keenan, FP O'Shea, E Thomas, RJ Brosius, JW Katsiyannis, A Ryans, RSI Reid, RHG Pradhan, AK Zhang, HL AF Keenan, FP O'Shea, E Thomas, RJ Brosius, JW Katsiyannis, A Ryans, RSI Reid, RHG Pradhan, AK Zhang, HL TI Si x emission lines in spectra obtained with the Solar EUV Rocket Telescope and Spectrograph (SERTS) SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE atomic data; Sun : activity; Sun : flares; ultraviolet : general ID B-LIKE IONS; HIGH-RESOLUTION OBSERVATIONS; ELECTRON-IMPACT EXCITATION; BORON-LIKE IONS; ATOMIC DATA; IRON PROJECT; ISOELECTRONIC SEQUENCE; RATE COEFFICIENTS; CROSS-SECTIONS; DIAGNOSTICS AB New R-matrix calculations of electron impact excitation rates for transitions among the 2s(2)2p, 2s2p(2) and 2p(3) levels of SI X are presented. These data are subsequently used, in conjunction with recent estimates for proton excitation rates, to derive theoretical electron density sensitive emission-line ratios involving transitions in the similar to 253-356 Angstrom wavelength range. A comparision of these with observations of a solar active region and subflare, obtained during the 1989 flight of the Solar EUV Rocket Telescope and Spectrograph (SERTS), reveals that the electron densities determined from most of the SI X line ratios are consistent with one another for both solar features. In addition, the derived densities are also in good agreement with the values of N-e estimated from diagnostic lines in other species formed at similar electron temperatures to SI X, such as Fe XII and Fe XIII. These results provide observational support for the general accuracy of the adopted atomic data, and hence line ratio calculations, employed in the present analysis. However, we find that the SI X 256.32-Angstrom line is blended with the He ii transition at the same wavelength, while the feature at 292.25 Angstrom is not due to SI X, but currently remains unidentified. The intensity of the 253.81-Angstrom line in the SERTS active region spectrum is about a factor of 3 larger than expected from theory, but the reason for this is unclear, and requires additional observations to explain the discrepancy. C1 Queens Univ Belfast, Dept Pure & Appl Phys, Belfast BT7 1NN, Antrim, North Ireland. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Raytheon ITSS, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Queens Univ Belfast, Dept Appl Math & Theoret Phys, Belfast BT7 1NN, Antrim, North Ireland. Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. Univ Calif Los Alamos Natl Lab, Appl Theoret & Computat Phys Div, Los Alamos, NM 87545 USA. RP Keenan, FP (reprint author), Queens Univ Belfast, Dept Pure & Appl Phys, Belfast BT7 1NN, Antrim, North Ireland. RI Katsiyannis, Thanassis/L-8496-2013 NR 31 TC 16 Z9 16 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUL 1 PY 2000 VL 315 IS 3 BP 450 EP 456 DI 10.1046/j.1365-8711.2000.03599.x PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 331JR UT WOS:000088016100006 ER PT J AU Song, YT AF Song, YT TI A general pressure gradient formulation for ocean models. Part I: Scheme design and diagnostic analysis (vol 126, pg 3213, 1999) SO MONTHLY WEATHER REVIEW LA English DT Correction C1 CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. RP Song, YT (reprint author), CALTECH, Jet Prop Lab, Div Earth & Space Sci, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 1 Z9 1 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 JUL PY 2000 VL 128 IS 7 BP 2608 EP 2609 DI 10.1175/1520-0493(2000)128<2608:C>2.0.CO;2 PN 2 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386JV UT WOS:000166058500015 ER PT J AU Zhu, DM Miller, RA AF Zhu, DM Miller, RA TI Thermal-barrier coatings for advanced gas-turbine engines SO MRS BULLETIN LA English DT Article C1 NASA, Glenn Res Ctr, Ohio Aerosp Inst, Cleveland, OH 44135 USA. RP Zhu, DM (reprint author), NASA, Glenn Res Ctr, Ohio Aerosp Inst, MS 24-1, Cleveland, OH 44135 USA. NR 13 TC 33 Z9 34 U1 1 U2 14 PU MATERIALS RESEARCH SOCIETY PI WARRENDALE PA 506 KEYSTONE DR, WARRENDALE, PA 15086 USA SN 0883-7694 J9 MRS BULL JI MRS Bull. PD JUL PY 2000 VL 25 IS 7 BP 43 EP 47 DI 10.1557/mrs2000.123 PG 5 WC Materials Science, Multidisciplinary; Physics, Applied SC Materials Science; Physics GA 333UH UT WOS:000088148800020 ER PT J AU Chai, JC Moder, JP AF Chai, JC Moder, JP TI Radiation heat transfer calculation using an angular-multiblock procedure SO NUMERICAL HEAT TRANSFER PART B-FUNDAMENTALS LA English DT Article ID FINITE-VOLUME METHOD; DISCRETE-ORDINATES METHOD; CYLINDRICAL ENCLOSURES; IRREGULAR GEOMETRIES; PREDICTION AB An angular-multiblock procedure for radiation heat transfer is presented in this article. With this procedure, finer angular grids can be used in optically thinner regions to minimize "ray effects." The proposed procedure ensures the conservation of radiant energy between angular blocks. The finite-volume method is used for demonstrative purposes in this article. The utilities of the procedure ave shown using three two-dimensional sample problems. C1 Tennessee Technol Univ, Dept Mech Engn, Cookeville, TN 38505 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Chai, JC (reprint author), Nanyang Technol Univ, Sch Mech & Prod Engn, 50 Nanyang Ave, Singapore 639798, Singapore. RI Chai, John/A-3764-2010 NR 19 TC 9 Z9 9 U1 0 U2 1 PU HEMISPHERE PUBL CORP PI BRISTOL PA 1900 FROST ROAD, SUITE 101, BRISTOL, PA 19007-1598 USA SN 1040-7790 J9 NUMER HEAT TR B-FUND JI Numer Heat Tranf. B-Fundam. PD JUL-AUG PY 2000 VL 38 IS 1 BP 1 EP 13 PG 13 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA 349YD UT WOS:000089072400001 ER PT J AU Titarchuk, L Osherovich, V AF Titarchuk, L Osherovich, V TI Timing spectroscopy of quasi-periodic oscillations in the low-mass X-ray neutron star binaries SO NUOVO CIMENTO DELLA SOCIETA ITALIANA DI FISICA B-GENERAL PHYSICS RELATIVITY ASTRONOMY AND MATHEMATICAL PHYSICS AND METHODS LA English DT Article; Proceedings Paper CT IIIrd ICRA Network Workshop/VIth Italo-Korean Meeting on Electrodynamics and Magnetohydrodynamics around Black Holes CY JUL 12-24, 1999 CL ROME, ITALY ID BRIGHTNESS OSCILLATIONS; KEPLERIAN OSCILLATIONS; GENERAL-RELATIVITY; ACCRETION DISKS; SCORPIUS X-1; SPECTRA; BURSTS; MODEL AB The problem of the determination of the physical parameters for celestial bodies has always been of fundamental importance in Astronomy. Study of accreting neutron stars and black holes can shed light on the physics of the strong gravity and dense matter. Millisecond variability related to high compactness of these objects naturally appears in the process of accretion of matter onto a stellar-mass compact object. So it is extremely important to learn how to extract information regarding the main physical parameters, particularly, strength and structure of magnetic field, inclination angle between the rotational and the magnetic axis of the star, masses, radii and distances, from millisecond oscillations, i.e. quasi-periodic oscillations (QPOs) frequencies and continuum S-ray spectra. Unfortunately very often the interpretation of the observational results of millisecond variations in Xray binaries depends on untested, or even unknown properties of spacetime, matter and resonance processes in the presence of strong gravity and magnetic fields. Our objective is to develop models for neutron star (NS) (and for black hole (BH)) and to apply such models to extract direct information regarding the physical parameters from QPOs power-frequencies characteristics. For the NSs we will complete the classification of the QPOs based on the recently developed Two-Oscillator (TO) model (Osherovich V. A. and Titarchuk L. G., Astrophys. J., 522 (1999) L113; Titarchuk L. G. and Osherovich V. A., Astrophys. J., 518 (1999) L95). The new model covers the range of frequencies from 1 Hz to 1200 Hz. It suggests the coexistence of viscous radial oscillations of the innermost part of the rotating disk with the diffusive process which involves also interaction with the normal disk mode (global mode of oscillations of the entire disk). In the outer (Keplerian) part of the disk the Two-Oscillator model interprets the twin peaks kHz QPOs as the Keplerian frequency and the upper hybrid frequency of the Keplerian oscillator under the influence of the Coriolis force in the differentially rotating NS magnetosphere. The developed TO model predicts that. a certain combination of the observed kHz QPO frequencies and Horizontal Branch frequencies (HBO) is constant for a particular source (see eq. (6)). The existence of the constant which is an inclination angle between the magnetic and rotational axes of the star is a central prediction of the TO model (Osherovich V. A. and Titarchuk L. G., Astrophys. J., 523 (1999) L73). There is no free parameters involved in the determination of this invariant. Furthermore the TO model allows us to determine the position of the outer radii of the Keplerian disk, the size of the transition layer between the inner edge of the disk and the Keplerian part of the dish, and find constraints for the NS mass-radius relation and the NS spin. We will offer, using this model, the global classification of QPO phenomena in NS systems. C1 NASA, Goddard Space Flight Ctr, RITTS, Greenbelt, MD 20771 USA. GMU, CSI, Fairfax, VA 22030 USA. RP Titarchuk, L (reprint author), NASA, Goddard Space Flight Ctr, RITTS, Code 661, Greenbelt, MD 20771 USA. NR 41 TC 1 Z9 1 U1 0 U2 0 PU EDITRICE COMPOSITORI BOLOGNA PI SIENA PA VIA SAN QUIRICO 13/2, I-53100 SIENA, ITALY SN 0369-3554 J9 NUOVO CIMENTO B JI Nouvo Cimento Soc. Ital. Fis. B-Gen. Phys. Relativ. Astron. Math. Phys. Methods PD JUL-SEP PY 2000 VL 115 IS 7-9 BP 869 EP 883 PG 15 WC Physics, Multidisciplinary SC Physics GA 381QC UT WOS:000165773600016 ER PT J AU Vodovotz, Y Smith, SM Lane, HW AF Vodovotz, Y Smith, SM Lane, HW TI Food and nutrition in space: Application to human health SO NUTRITION LA English DT Article ID ENERGY-EXPENDITURE; SPACEFLIGHT; METABOLISM; BALANCE; SHUTTLE; CALCIUM; FLIGHTS; MUSCLE C1 NASA, Lyndon B Johnson Space Ctr, Natl Space Biomed Res Inst, Houston, TX 77058 USA. RP Lane, HW (reprint author), NASA, Lyndon B Johnson Space Ctr, Natl Space Biomed Res Inst, Mail Code SA, Houston, TX 77058 USA. NR 40 TC 7 Z9 7 U1 0 U2 4 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0899-9007 J9 NUTRITION JI Nutrition PD JUL-AUG PY 2000 VL 16 IS 7-8 BP 534 EP 537 DI 10.1016/S0899-9007(00)00311-7 PG 4 WC Nutrition & Dietetics SC Nutrition & Dietetics GA 337RF UT WOS:000088374900024 PM 10906547 ER PT J AU Morisette, JT Khorram, S AF Morisette, JT Khorram, S TI Accuracy assessment curves for satellite-based change detection SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article ID LOGISTIC MULTIPLE-REGRESSION; REMOTELY-SENSED DATA; GIS AB The concept of "accuracy assessment curves" as they relate to image-based change detection is developed. These curves are a graphical representation of the relationship between typical accuracy assessment figures and a binary change detection threshold level. After an introduction to accuracy assessment curves, an example is presented. The relationship between typical accuracy assessment parameters and the location of the binary change threshold level is first shown with a series of error matrices. This relationship is then expanded across a range of thresholds and shown as accuracy assessment curves. These curves show how accuracy figures are dependent on the change metric's threshold level. This dependency indicates some limitations of binary change maps. These limitations provide the impetus for a continuous change product. We describe how a continuous Probability-of-change (poc) image, derived from statistical models, can be incorporated with the accuracy assessment curves to produce a more meaningful and informative change detection product. C1 Earth Satellite Corp, Rockville, MD 20852 USA. N Carolina State Univ, Ctr Earth Observat, Raleigh, NC 27695 USA. RP Morisette, JT (reprint author), Univ Maryland, NASA, Goddard Space Flight Ctr, Code 923, Greenbelt, MD 20771 USA. NR 31 TC 62 Z9 62 U1 1 U2 4 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 USA SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD JUL PY 2000 VL 66 IS 7 BP 875 EP 880 PG 6 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA 327ZH UT WOS:000087824000008 ER PT J AU Adriaans, MJ Lipa, JA AF Adriaans, MJ Lipa, JA TI Second sound measurements very near the lambda point SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE He-4 superfluid; lambda transition; second sound ID 2ND SOUND; VELOCITY AB High-resolution measurements of the second sound velocity near T-lambda in superfluid He-4 at the vapor pressure are reported. Experiments were performed using the resonant technique in cavities 13, 4 and 2 mm in height. A disc of paramagnetic salt, copper ammonium bromide, in direct contact with the helium sample and coupled to a SQUID magnetometer, was used as the sensor. The sound was generated by wire-wound heaters embedded in the end opposite the sensor in each cavity. The superfluid density was determined from second sound measurements and the critical exponent nu was obtained from fits to the data. The results for the exponent were found to be very sensitive to the treatment of systematic effects in the data. (C) 2000 Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Stanford Univ, Dept Phys, Stanford, CA 94305 USA. RP Adriaans, MJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 79-24, Pasadena, CA 91109 USA. NR 4 TC 1 Z9 1 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4526 J9 PHYSICA B JI Physica B PD JUL PY 2000 VL 284 BP 49 EP 50 DI 10.1016/S0921-4526(99)02012-8 PN 1 PG 2 WC Physics, Condensed Matter SC Physics GA 318YF UT WOS:000087311700026 ER PT J AU Nissen, JA Swanson, DR Geng, ZK Kim, K Day, P Lipa, JA AF Nissen, JA Swanson, DR Geng, ZK Kim, K Day, P Lipa, JA TI Superfluid density as a function of temperature and pressure near the lambda line SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE critical phenomena; He-4 liquid lambda transition; lambda transition; second sound; superfluid density AB We report new results for the superfluid density in the region close to the lambda line at pressures up to 25 bars. The data were obtained from second sound velocity measurements made to within 0.9 mu K of the transition by a resonance technique. A superconducting pressure gauge was used to allow the measurements to be performed along a constant pressure path. From these data the temperature and pressure dependence of the superfluid density can be derived to test for critical exponent universality. We also report the temperature and pressure dependence of the resonator quality factor. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Stanford Univ, Dept Phys, Stanford, CA 94305 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Nissen, JA (reprint author), Stanford Univ, Dept Phys, Stanford, CA 94305 USA. NR 2 TC 4 Z9 4 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 JUL PY 2000 VL 284 BP 51 EP 52 DI 10.1016/S0921-4526(99)02014-1 PN 1 PG 2 WC Physics, Condensed Matter SC Physics GA 318YF UT WOS:000087311700027 ER PT J AU Harter, AW Lee, RAM Chui, TCP Goodstein, DL AF Harter, AW Lee, RAM Chui, TCP Goodstein, DL TI Heat capacity measurements of He-4 at constant heat flux near T-lambda SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE heat capacity; He-4 liquid lambda transition; phase transition ID SUPERFLUID HE-4; ANOMALIES; FLOW AB The heat capacity, C-Q, of superfluid He-4 in the presence of a constant heat flux, Q, is expected to diverge at a depressed transition temperature, T-c(Q). We have taken preliminary measurements of C-Q at various heat flux values in the range 1 mu W/cm(2) less than or equal to Q less than or equal to 4 mu W/Cm-2. We observe that at sufficiently small reduced temperatures, C-Q is enhanced as a function of Q, and that the enhancement is larger than theoretical predictions by Chui et al. and Hausmann and Dohm (Phys. Rev. Lett 77 (1996) 980, 1793; preprint). (C) 2000 Elsevier Science B.V. All rights reserved. C1 CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Harter, AW (reprint author), CALTECH, Pasadena, CA 91125 USA. NR 6 TC 0 Z9 0 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4526 J9 PHYSICA B JI Physica B PD JUL PY 2000 VL 284 BP 53 EP 54 DI 10.1016/S0921-4526(99)02016-5 PN 1 PG 2 WC Physics, Condensed Matter SC Physics GA 318YF UT WOS:000087311700028 ER PT J AU Liu, YM Larson, M Israelsson, UE AF Liu, YM Larson, M Israelsson, UE TI T-lambda depression in He-4 by a heat current along the lambda-line SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE heat transport; He-4 superfluid; lambda transition ID SUPERFLUID TRANSITION AB We report measurements of the depression of the superfluid transition temperature by a heat current (1 less than or equal to Q less than or equal to 100 mu W/cm(2)) along the lambda-line (SVP less than or equal to P less than or equal to 21.6bar). Experimental data can be represented by Delta T-lambda/T-lambda = (Q/Q(0))(x). The exponent, x, is universal and pressure independent as expected, but its value (about 0.9) is higher than the theoretical prediction (0.745) and the earlier experimental value (0.813) at SVP. The amplitude, Q(0), shows a pressure dependence that is in qualitative agreement with the theoretical prediction, but its value is lower than the predicted and earlier experimental values at SVP. At P = 21.6 bar, measurements were also performed in a reduced effective gravity (0.2g), and these results show that the gravity effect in our measurements is small. Published by Elsevier Science B.V. C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Liu, YM (reprint author), Jet Prop Lab, MS 79-24,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 1 Z9 1 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 JUL PY 2000 VL 284 BP 55 EP 56 DI 10.1016/S0921-4526(99)02017-7 PN 1 PG 2 WC Physics, Condensed Matter SC Physics GA 318YF UT WOS:000087311700029 ER PT J AU Mukharsky, Y Sukhatme, K Pearson, D Chui, T AF Mukharsky, Y Sukhatme, K Pearson, D Chui, T TI Study of flow of superfluid He-II very near T-lambda SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE critical exponent; He-4 superfluid; hydrodynamics; superfluidity AB We report here preliminary data from an experiment studying flow of superfluid helium through a slit orifice (of sub-micron width) very close to T-lambda. Critical supercurrent (I-c) data are obtained from a step function drive to the diaphragm in a Helmholtz resonator cell. The superfluid density (rho(s)) data can be obtained from the resonant frequency of the Helmholtz oscillator, as determined by transfer function of the resonator or from the free ringing after the step function excitation. Preliminary data shows that I-c similar to rho(s)(1.27) and rho(s)(1.27) similar to t(0.73), where t is the reduced temperature. However, the magnitude of I-c is much larger than expected, indicating a possible parallel flow path. Further investigations are in progress. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Ctr Etud Saclay, Serv Phys Etat Condense, CEA, DRECAM, F-91191 Gif Sur Yvette, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Mukharsky, Y (reprint author), Ctr Etud Saclay, Serv Phys Etat Condense, CEA, DRECAM, F-91191 Gif Sur Yvette, France. RI Mukharsky, Yury/F-4920-2013 NR 5 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4526 J9 PHYSICA B JI Physica B PD JUL PY 2000 VL 284 BP 83 EP 84 DI 10.1016/S0921-4526(99)02049-9 PN 1 PG 2 WC Physics, Condensed Matter SC Physics GA 318YF UT WOS:000087311700043 ER PT J AU Barmatz, M Zhong, F Hahn, I AF Barmatz, M Zhong, F Hahn, I TI Susceptibility measurements near the He-3 liquid-gas critical point SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE critical phenomena; He-3 normal liquid; susceptibility AB A new electrostriction technique and the conventional pressure-density method were used to determine the susceptibility near the liquid-gas critical point of He-3. Measurements were made along the critical isochore over the reduced temperature range of 3 x 10(-5) < T/T-c - 1 < 7 x 10(-3). Preliminary results were compared with previous experiments chi(T)* = Gamma(0)(+)t(-y)(1 + Gamma(1)(+)t(-1)). Best fit parameters for the asymptotic amplitude Gamma(0)(+) and the first correction-to-scaling amilitude Gamma(1)(+) are presented. (C) 2000 Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Barmatz, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 1 Z9 1 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 JUL PY 2000 VL 284 BP 206 EP 207 DI 10.1016/S0921-4526(99)02403-5 PN 1 PG 2 WC Physics, Condensed Matter SC Physics GA 318YF UT WOS:000087311700103 ER PT J AU Mohazzab, M Mulders, N Larson, M Nash, A AF Mohazzab, M Mulders, N Larson, M Nash, A TI A nonlinear wave equation for second sound in He-3-He-4 mixtures SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE He-3-He-4 mixture; nonlinear acoustics; second sound ID 2ND SOUND AB In the vicinity of the tricritical point second sound propagation becomes very nonlinear, primarily as a result of the small superfluid fraction. Applying a reductive perturbation scheme to the full superfluid hydrodynamic equations we obtain a nonlinear wave equation of the Burgers type, and an explicit expression for the nonlinear coefficient. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Mulders, N (reprint author), Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA. NR 8 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4526 J9 PHYSICA B JI Physica B PD JUL PY 2000 VL 284 BP 327 EP 328 DI 10.1016/S0921-4526(99)02679-4 PN 1 PG 2 WC Physics, Condensed Matter SC Physics GA 318YF UT WOS:000087311700163 ER PT J AU Yeh, NC Wei, JYT Fu, CC Vasquez, RP AF Yeh, NC Wei, JYT Fu, CC Vasquez, RP TI Dynamic pair breaking in cuprate superconductors via injection of spin-polarized quasiparticles in perovskite F-I-S heterostructures SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE Cooper pair; cuprate superconductors ID FERROMAGNET AB We report experimental evidence of dynamic Cooper pair breaking induced by spin-polarized quasiparticles in cuprate superconductors by studying the critical current density and quasiparticle density of states of ferromagnet-insulator-superconductor (F-I-S) heterostructures. The spin diffusion length and relaxation time are also estimated. (C) 2000 Elsevier Science B.V. All rights reserved. C1 CALTECH, Dept Phys, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Yeh, NC (reprint author), CALTECH, Dept Phys, Pasadena, CA 91125 USA. NR 6 TC 4 Z9 4 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4526 J9 PHYSICA B JI Physica B PD JUL PY 2000 VL 284 BP 507 EP 508 DI 10.1016/S0921-4526(99)02098-0 PN 1 PG 2 WC Physics, Condensed Matter SC Physics GA 318YF UT WOS:000087311700253 ER PT J AU Yeh, NC Fu, CC Xie, X Vasquez, RP Samoilov, AV AF Yeh, NC Fu, CC Xie, X Vasquez, RP Samoilov, AV TI Magnetic percolation effect on the spontaneous Hall resistivity and magnetoresistance of La(1-x)A(x)CoO(3) (A = Ca, Sr; 0.1 <= x <= 0.5) SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE magnetic percolation effect; Hall resistivity; magnetoresistance AB The Hall resistivity and magnetoresistance of La(1-x)A(x)CoO(3) (A = Ca, Sr) are investigated. The spontaneous Hall coefficient reaches maximum near the Curie temperature for each doping level, and achieves the largest magnitude near the magnetic percolation threshold. The physical significance of these results are discussed. (C) 2000 Elsevier Science B.V. All rights reserved. C1 CALTECH, Dept Phys, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Yeh, NC (reprint author), CALTECH, Dept Phys, Pasadena, CA 91125 USA. NR 6 TC 2 Z9 2 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 JUL PY 2000 VL 284 BP 1446 EP 1447 DI 10.1016/S0921-4526(99)02685-X PN 2 PG 2 WC Physics, Condensed Matter SC Physics GA 320WD UT WOS:000087423100162 ER PT J AU Woodcraft, AL Sudiwala, RV Wakui, E Bhatia, RS Bock, JJ Turner, AD AF Woodcraft, AL Sudiwala, RV Wakui, E Bhatia, RS Bock, JJ Turner, AD TI Thermal conductance measurements of a silicon nitride membrane at low temperatures SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE cryogenic instrumentation; thermal conduction; thin films AB Silicon nitride membranes are used for thermal isolation in various devices, such as bolometric millimetre-wave detectors and lattice microrefrigerators. We have measured the thermal conductance of a 1.5 mu m thick silicon nitride membrane, between 0.1 and 0.3 K. At these temperatures, thermal transport in such thin films is believed to be dominated by phonon surface scattering, and not by bulk behaviour. We compare our results with theory, as well as experiments using films with different thicknesses. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ London Queen Mary & Westfield Coll, Dept Phys, London E1 4NS, England. CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Woodcraft, AL (reprint author), Univ London Queen Mary & Westfield Coll, Dept Phys, Mile End Rd, London E1 4NS, England. NR 6 TC 10 Z9 10 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4526 J9 PHYSICA B JI Physica B PD JUL PY 2000 VL 284 BP 1968 EP 1969 DI 10.1016/S0921-4526(99)02925-7 PN 2 PG 2 WC Physics, Condensed Matter SC Physics GA 320WD UT WOS:000087423100422 ER PT J AU Panek, JS Nash, AE Larson, M Mulders, N AF Panek, JS Nash, AE Larson, M Mulders, N TI A high-resolution thermometer for the range 0.75-1.0 K SO PHYSICA B LA English DT Article; Proceedings Paper CT 22nd International Conference on Low Temperature Physics CY AUG 04-11, 1999 CL HELSINKI UNIV TECHNOL, HELSINKI, FINLAND SP Commiss C5 low Temp Phys, Int Union Pure & Appl Phys, Acad Finland, Helsinki Univ Technol, Int Assoc Promot Sci, Oxford Instruments Ltd, FortumCorp, Nokia Grp, Finnair Ltd, Datex Engstrom Ltd, Finnish Phys Soc, Picker Nordstar Ltd, Neuromag ltd, SAP Finland Ltd, Espoo Elect Ltd, Outokumpu Ltd, City Espoo, Finnish Acad Sci & Letters, DCA-Instruments Ltd, Vaisala Ltd HO HELSINKI UNIV TECHNOL DE thermometer; He-3-He-4 mixture; tricritical point; gadolinium gallium garnet ID GADOLINIUM GALLIUM GARNET AB We report on a new high-resolution thermometer (HRT) for use near the tricritical point in He-3-He-4 mixtures. It is based on an existing HRT design that uses a DC-SQUID to detect the magnetization of a paramagnetic sensing element. We present the first test results of an HRT using a gadolinium gallium garnet (GGG) crystal. Sensitivity over the temperature range 0.4-3.5 K for applied fields from 0.41 to 20 G is presented, (C) 2000 Published by Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA. RP Panek, JS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 4 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4526 J9 PHYSICA B JI Physica B PD JUL PY 2000 VL 284 BP 2000 EP 2001 DI 10.1016/S0921-4526(99)02767-2 PN 2 PG 2 WC Physics, Condensed Matter SC Physics GA 320WD UT WOS:000087423100438 ER PT J AU Deines-Jones, P Cherry, ML Dabrowska, A Holynski, R Kudzia, D Nilsen, BS Olszewski, A Szarska, M Trzupek, A Waddington, CJ Wefel, JP Wilczynska, B Wilczynski, H Wolter, W Wosiek, B Wozniak, K AF Deines-Jones, P Cherry, ML Dabrowska, A Holynski, R Kudzia, D Nilsen, BS Olszewski, A Szarska, M Trzupek, A Waddington, CJ Wefel, JP Wilczynska, B Wilczynski, H Wolter, W Wosiek, B Wozniak, K TI Charged particle production in the Pb plus Pb system at 158 GeV/c per nucleon SO PHYSICAL REVIEW C LA English DT Article ID PB+PB COLLISIONS; 200 GEV/C; ENERGIES; DISTRIBUTIONS; GEV/NUCLEON; EMULSION; LEAD; MULTIPLICITIES; FRAGMENTATION; VENUS AB Charged particle multiplicities from high-multiplicity interactions of 158 GeV/nucleon Pb ions with Pb target nuclei have been measured using high-resolution nuclear emulsion chambers with sensitivity from the peak of the pseudorapidity distribution forward to eta>9 The characteristics of these interactions have been compared to those of central interactions of 200 GeV/nucleon proton, O, and S beams on silver or bromine targets and to results from simulations using the FRITIOF 7.02 and VENUS 4.12 Monte Carlo event generators. Multiplicities scale with the number of wounded nucleons, although the multiplicities for Pb+Pb interactions in the central region are significantly lower than predicted by either Monte Carlo model. We examine the shape of the pseudorapidity distribution and its dependence on centrality in detail, because in this symmetric system the participant projectile target masses are independent of centrality; so any dependence of the shape on centrality must therefore be a dynamical effect. No dependence of the produced particle pseudorapidity distribution on multiplicity or centrality is seen. VENUS, the only one of the two models which attempts to incorporate reinteraction phenomena, predicts a narrowing of the pseudorapidity distributions for the highest multiplicity events, which we do not observe. In general, FRITIOF produces better fits to the all-charged-particle (primarily pion) data than does VENUS. C1 Louisiana State Univ, Baton Rouge, LA 70803 USA. Inst Nucl Phys, Krakow, Poland. Univ Minnesota, Minneapolis, MN 55455 USA. RP Deines-Jones, P (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 55 TC 23 Z9 24 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2813 J9 PHYS REV C JI Phys. Rev. C PD JUL PY 2000 VL 62 IS 1 AR 014903 DI 10.1103/PhysRevC.62.014903 PG 11 WC Physics, Nuclear SC Physics GA 333PV UT WOS:000088139200042 ER PT J AU Baring, MG AF Baring, MG TI Magnetic photon splitting: The S-matrix formulation in the Landau representation SO PHYSICAL REVIEW D LA English DT Article ID QUANTUM ELECTRODYNAMICS; PAIR PRODUCTION; FIELDS; VACUUM; REPEATERS AB Calculations of reaction rates for the third-order QED process of photon splitting gamma --> gamma gamma in strong magnetic fields traditionally have employed either the effective Lagrangian method or variants of Schwinger's proper-time technique. Recently, Mentzel, Beg and Wunner presented an alternative derivation via an S-matrix formulation in the Landau representation. Advantages of such a formulation include the ability to compute rates near pair resonances above pair threshold. This paper presents new developments of the Landau representation formalism as applied to photon splitting, providing significant advances beyond the work of Mentzel, Berg, and Wunner by summing over the spin quantum numbers of the electron propagators, and analytically integrating over the component of momentum of the intermediate states that is parallel to the held. The ensuing tractable expressions for the scattering amplitudes are satisfyingly compact, and of an appearance familiar to S-matrix theory applications. Such developments can facilitate numerical computations of splitting considerably both below and above pair threshold. Specializations to two regimes of interest are obtained, namely the limit of highly supercritical fields and the domain where photon energies are far inferior to that for the threshold of single-photon pair creation. In particular, for the first time the low-frequency amplitudes are simply expressed in terms of the Gamma function,its integral and its derivatives. In addition, the equivalence of the asymptotic forms in these two domains to extant results From effective Lagrangian or proper-time formulations is demonstrated. C1 NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Washington, DC USA. RP Baring, MG (reprint author), NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. EM baring@lheavx.gsfc.nasa.gov NR 42 TC 9 Z9 9 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 JUL 1 PY 2000 VL 62 IS 1 AR 016003 PG 16 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 330GH UT WOS:000087954100077 ER PT J AU Gurski, KF Pego, RL AF Gurski, KF Pego, RL TI Decay rates of internal waves in a fluid near the liquid-vapor critical point SO PHYSICAL REVIEW E LA English DT Article ID XENON AB We study the damping of internal waves in a viscous fluid near the liquid-vapor critical point. Such a fluid becomes strongly stratified by gravity due to its large compressibility. Using the variable-density incompressible Navier-Stokes equations, we model an infinite fluid layer with rigid horizontal boundaries and periodic side boundary conditions. We present operator-theoretic results that predict the existence of internal-wave modes with arbitrarily small damping rates. We also solve the eigenvalue problem numerically using a compound matrix shooting method and a second method based on a matched-asymptotic perturbation expansion for small viscosity. At temperatures far above the critical point, the damping of the internal waves is substantially influenced by both boundary layer and volumetric effects. The boundary layer effect is caused by horizontal shearing layers near the two fixed horizontal boundaries. As the temperature approaches the critical temperature, an additional internal shearing layer develops as the density stratification curve steepens on approach to the two-phase regime. Numerical calculations show that for some of the internal-wave modes this causes a dramatic increase in the damping rate that dominates the boundary layer effects. C1 NASA, Goddard Space Flight Ctr, Ctr Excellence Space Data & Informat Sci, USRA, Greenbelt, MD 20771 USA. Univ Maryland, Dept Math, College Pk, MD 20742 USA. Univ Maryland, Inst Phys Sci & Technol, College Pk, MD 20742 USA. RP Gurski, KF (reprint author), NASA, Goddard Space Flight Ctr, Ctr Excellence Space Data & Informat Sci, USRA, 930-5, Greenbelt, MD 20771 USA. RI Pego, Robert/A-7641-2017; OI Pego, Robert/0000-0001-8502-2820; Gurski, Katharine/0000-0002-4589-8307 NR 24 TC 2 Z9 2 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1063-651X J9 PHYS REV E JI Phys. Rev. E PD JUL PY 2000 VL 62 IS 1 BP 517 EP 524 DI 10.1103/PhysRevE.62.517 PN A PG 8 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA 335YG UT WOS:000088274100070 ER PT J AU Gleiser, M Sornborger, A AF Gleiser, M Sornborger, A TI Long-lived localized field configurations in small lattices: Application to oscillons SO PHYSICAL REVIEW E LA English DT Article ID OSCILLATED GRANULAR LAYERS; VIBRATED SAND; PATTERNS AB Long-lived localized field configurations such as breathers, oscillons, or more complex objects naturally arise in the context of a wide range of nonlinear models in different numbers of spatial dimensions. We present a numerical method, which we call the adiabatic damping method, designed to study such configurations in small lattices. Using three-dimensional oscillons in phi(4) models as an example, we show that the method accurately (to one part in 10(5) or better) reproduces results obtained with static or dynamically expanding lattices, dramatically cutting down in integration time. We further present results for two-dimensional oscillons, whose lifetimes would be prohibitively long to study with conventional methods. C1 Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA. NASA, Fermilab Astrophys Grp, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. RP Gleiser, M (reprint author), Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA. EM gleiser@dartmouth.edu; ats@camelot.mssm.edu NR 29 TC 34 Z9 34 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1539-3755 J9 PHYS REV E JI Phys. Rev. E PD JUL PY 2000 VL 62 IS 1 BP 1368 EP 1374 DI 10.1103/PhysRevE.62.1368 PN B PG 7 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA 335YH UT WOS:000088274200070 ER PT J AU Parhi, S Suess, ST AF Parhi, S Suess, ST TI Alfvenicity of fluctuations associated with the Kelvin-Helmholtz instability SO PHYSICS OF PLASMAS LA English DT Article ID RADIATIVELY COOLING JETS; STRATIFIED SHEAR-LAYER; RADIAL IMF COMPONENT; SOLAR-WIND; BOUNDARY-LAYER; SPATIAL STABILITY; MAGNETIC-FIELD; SLAB JET; MAGNETOSPHERIC BOUNDARY; LATITUDINAL DEPENDENCE AB The velocity shear which exists between three layers in an ideal plasma is studied. This configuration is modeled as a jet (or, strictly speaking, a wake) embedded in a uniform medium using a magnetohydrodynamics (MHD) code developed for astrophysical jet simulations. Weak and strong magnetic fields are considered both inside and outside the jet with a shear Mach number of 6. The shear can be Kelvin-Helmholtz (KH) unstable and evolve into a new less sheared pattern. There exists extensive literature on the KH instability which is extended by quantitatively describing the MHD properties of the fluctuations associated with the instability. To do so, a time series analysis of the fluctuations at various points inside and adjacent to the jet is performed. Specifically, points either in the center of the jet or just outside the transition layer-the initial location of the shear layer are considered. In the nonlinear stage, the perturbation is found to be a sum of the fast magnetosonic mode, slow magnetosonic mode, and the Alfven component. To quantitatively evaluate the fluctuations, the normalized cross-helicity and Elsasser ratios are calculated, which in turn measure the degree of Alfvenicity. Fully nonlinear fluctuations are found to be more Alfvenic than magnetosonic in the low beta case (beta approximate to 0.833) as compared with high beta case (beta approximate to 13.3). This is in contrast to linear modes generated by the KH instability, which are magnetosonic modes. (C) 2000 American Institute of Physics. [S1070-664X(00)04607-3]. C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Solar Phys Team SD50, Huntsville, AL 35812 USA. RP NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Solar Phys Team SD50, Huntsville, AL 35812 USA. EM shyam.parhi@msfc.nasa.gov; steve.suess@msfc.nasa.gov NR 58 TC 3 Z9 3 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 1070-664X EI 1089-7674 J9 PHYS PLASMAS JI Phys. Plasmas PD JUL PY 2000 VL 7 IS 7 BP 2995 EP 3003 AR PII [S1070-664X(00)04607-3] DI 10.1063/1.874151 PG 9 WC Physics, Fluids & Plasmas SC Physics GA 326TG UT WOS:000087751200028 ER PT J AU Chang, Y Schubert, SD Suarez, MJ AF Chang, Y Schubert, SD Suarez, MJ TI Boreal winter predictions with the GEOS-2 GCM: The role of boundary forcing and initial conditions SO QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY LA English DT Article DE ensemble predictions; ENSO response; seasonal forecasts; signal-to-noise ratio ID SEA-SURFACE TEMPERATURE; GENERAL-CIRCULATION MODELS; NORTHERN HEMISPHERE WINTER; NINO SOUTHERN OSCILLATION; EL-NINO; EXTRATROPICAL RESPONSE; NUMERICAL-MODEL; FORECAST SKILL; ANOMALIES; PREDICTABILITY AB Ensembles of atmospheric General Circulation Model (GCM) seasonal forecasts and long-term simulations are analysed to assess the controlling influences of boundary forcing and memory of the initial conditions. Both the forecasts and simulations are carried out with version 2 of the Goddard Earth Observing System (GEOS-2) GCM forced with observed sea surface temperatures (SSTs). While much of the focus is on the seasonal timescale (January-March; 1981-95) and the Pacific North American (PNA) region, we also present results for other regions, shorter time-scales, and other known modes of variability in the northern hemisphere extratropics. Forecasts of indices of some of the key large-scale modes of variability show that there is considerable variability in skill between different regions of the northern hemisphere. The eastern North Atlantic region has the poorest long-lead forecast skill, showing no skill beyond about 10 days. Skilful seasonal forecasts are primarily confined to the wave-like Fl Nino Southern Oscillation (ENSO) response emanating from the tropical Pacific. In the northern hemisphere, this is similar to the well-known PNA pattern. Memory of the initial conditions is the major factor leading to skilful extratropical forecasts of lead time less than one month, while boundary forcing is the dominant factor at the seasonal time-scale. Boundary forcing contributes to skilful forecasts at sub-seasonal time-scales only over the PNA region. The GEOS-2 GCM produces average signal-to-noise ratios which are less than 1.0 everywhere in the extratropics, except for the subtropical Pacific where they approach 1.5. An assessment of the sampling distribution of the forecasts suggests the model's ENSO response is very likely too weak. These results show some sensitivity to the uncertainties in the estimates of the SST forcing fields. In the North Pacific region, the sensitivity to SST forcing manifests itself primarily as changes in the variability of the PNA response, underscoring the need for an ensemble approach to the seasonal-prediction problem. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Schubert, SD (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. NR 70 TC 14 Z9 14 U1 0 U2 0 PU ROYAL METEOROLOGICAL SOC PI READING PA 104 OXFORD ROAD, READING RG1 7LJ, BERKS, ENGLAND SN 0035-9009 J9 Q J ROY METEOR SOC JI Q. J. R. Meteorol. Soc. PD JUL PY 2000 VL 126 IS 567 BP 2293 EP 2321 DI 10.1256/smsqj.56714 PN B PG 29 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 350HG UT WOS:000089094500015 ER PT J AU Scaife, AA Austin, J Butchart, N Pawson, S Keil, M Nash, J James, IN AF Scaife, AA Austin, J Butchart, N Pawson, S Keil, M Nash, J James, IN TI Seasonal and interannual variability of the stratosphere diagnosed from UKMO TOVS analyses SO QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY LA English DT Article DE interannual variability; interhemispheric differences; quasi-biennial oscillation; satellite observations; seasonal cycle ID QUASI-BIENNIAL OSCILLATION; SOUTHERN-HEMISPHERE STRATOSPHERE; SEMIANNUAL OSCILLATION; ZONAL WIND; METEOROLOGICAL-OFFICE; UNIFIED MODEL; ANNUAL CYCLE; TROPOSPHERE; CIRCULATION; TEMPERATURE AB UK Meteorological Office (UKMO) TOVS analyses are used to show that the record of satellite radiance measurements is now long enough to capture the vast majority of year-to-year variability in the stratosphere. Given this, a climatology of the stratosphere is constructed and used to identify robust hut detailed features of the seasonal evolution in the northern and southern hemispheres. Interannual variability is also investigated. In the northern winter stratosphere, the interannual variability in geopotential height increases monotonically towards the pole. In contrast, in the southern hemisphere the largest interannual variability occurs in a collar of high values surrounding a low-variability region over the pole. For the Tropics, we show that quasi-biennial and semiannual oscillations in the tropical zonal wind can be derived from the geopotential-height analyses. However, comparisons of tropical winds from three different methods of analysis show that the current meridional resolution of the analysis limits the accuracy of the stratospheric winds over the equator. Finally, the satellite radiance data are used to derive updated temperature trends for the stratosphere. These show a cooling trend throughout most of the stratosphere that increases with height above the tropopause and exceeds 2 K per decade at the stratopause. C1 Met Off, Bracknell RG12 2SZ, Berks, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Reading, Reading RG6 2AH, Berks, England. RP Scaife, AA (reprint author), Met Off, London Rd, Bracknell RG12 2SZ, Berks, England. RI Pawson, Steven/I-1865-2014 OI Pawson, Steven/0000-0003-0200-717X NR 40 TC 49 Z9 49 U1 2 U2 6 PU ROYAL METEOROLOGICAL SOC PI READING PA 104 OXFORD ROAD, READING RG1 7LJ, BERKS, ENGLAND SN 0035-9009 J9 Q J ROY METEOR SOC JI Q. J. R. Meteorol. Soc. PD JUL PY 2000 VL 126 IS 568 BP 2585 EP 2604 DI 10.1256/smsqj.56811 PN C PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 351YH UT WOS:000089187300011 ER PT J AU West, RD AF West, RD TI Potential applications of 1-5 GHz radar backscatter measurements of seasonal land snow cover SO RADIO SCIENCE LA English DT Article ID TIME-DOMAIN REFLECTOMETRY; MONTE-CARLO SIMULATIONS; DENSE MEDIA; WATER-CONTENT; SAR DATA; SCATTERING; APPROXIMATION; SOILS; TEMPERATURE; RESOLUTION AB Lower frequency microwave radar observations can help to measure the properties of snow cover on land by providing information about the soil-snow boundary condition. In this theoretical study, we examine the sensitivities of microwave radar measurements to soil and snow characteristics, and we compare a simple model with previously published data. Depending on the surface roughness, copolarized ratios or single polarization time ratios of radar backscattering may be affected only by the incidence angle and the dielectric contrast at the soil-snow boundary. These measurements can reduce the number of unknowns in any corresponding higher-frequency observations that are also affected by the lower boundary condition. The copolarized ratio is sensitive, first of all, to the snow density, which offers the possibility of measuring this parameter directly if a separate measurement of the soil temperature from a passive microwave system is also available. The thermal insulation provided by snow cover can have a powerful effect on the soil-snow boundary by altering the soil temperature and therefore changing the dielectric contrast. Because the microwave response of snow cover is so sensitive to the conditions of the underlying frozen soil, it is important for future ground truth campaigns that measure snow conditions to also collect data on the temperature, water content, and texture of the soil. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP West, RD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 300-235, Pasadena, CA 91109 USA. NR 32 TC 4 Z9 5 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD JUL-AUG PY 2000 VL 35 IS 4 BP 967 EP 981 DI 10.1029/1999RS002257 PG 15 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA 338CE UT WOS:000088399900005 ER PT J AU Armstrong, EM AF Armstrong, EM TI Satellite derived sea surface temperature variability off California during the upwelling season SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID VANCOUVER-ISLAND; COLD FILAMENTS; POINT ARENA; SUMMER; OCEAN; DYNAMICS; PATTERNS; COAST; SHELF AB An empirical orthogonal function analysis of an advanced very high resolution radiometer sea surface temperature data set encompassing the spring-summer period during 1991-1993 was used to examine patterns of temperature variability off northern and central California. This analysis decomposed the spatial variability of remotely sensed sea surface temperature in 124 images that covered an offshore distance of 200 km and an alongshore distance of 500 km. The first mode empirical orthogonal function described 65% of the spatial variability in the data set. The spatial amplitude patter of the first mode, which closely resembled the mean of all the images, revealed a strong cross-shore gradient with much cooler water nearshore and warmer water offshore. These areas of cool waters were associated with known upwelling locales, and the large-scale temperature structure compared favorably to that derived from historical California Cooperative Oceanographic Fisheries Investigation (CalCOFI) climatology. The mode 1 temporal amplitude function, representing the temporal modulation of this spatial patter, was coupled with changes in the alongshore component of the coastal wind field. Interannual variations in the timing of the spring transition were reflected in this temporal amplitude time series. The second mode empirical orthogonal function described 11% of the variability in the data set. The spatial pattern revealed a north-south structure that appeared to be related to regional spatial variations in the strength of upwelling-favorable wind. The third empirical orthogonal function described only 3% of the data variability and the spatial structure suggested a meandering of the coastal surface flow. The results of this investigation indicate that the empirical orthogonal function method was effective at characterizing front the satellite data the dominant nearshore surface properties of die California Current System related to upwelling and rc;ind and by extension suggest that it is a suitable approach for remotely investigating other less well known easter boundary current systems. (C) Elsevier Science Inc., 2000. C1 Technol Planning & Management Corp, Charleston, SC USA. RP Armstrong, EM (reprint author), NASA, Jet Prop Lab, Phys Oceanog DAAC, 4800 Oak Grove Dr,MS 300-320, Pasadena, CA 91109 USA. NR 34 TC 16 Z9 16 U1 2 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD JUL PY 2000 VL 73 IS 1 BP 1 EP 17 DI 10.1016/S0034-4257(99)00072-3 PG 17 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 330FL UT WOS:000087952100001 ER PT J AU Clark-Ingram, M Finckenor, M AF Clark-Ingram, M Finckenor, M TI EPA/NASA/USAF depainting effort concludes SO SAMPE JOURNAL LA English DT Article C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Clark-Ingram, M (reprint author), NASA, George C Marshall Space Flight Ctr, Mail Code ED36, Huntsville, AL 35812 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 USA SN 0091-1062 J9 SAMPE J JI Sampe J. PD JUL-AUG PY 2000 VL 36 IS 4 BP 56 EP 58 PG 3 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 335NH UT WOS:000088249200011 ER PT J AU Harris, G Lennhoff, J Nassif, J Vinciguerra, M Rose, P Jaworski, D Gaier, J AF Harris, G Lennhoff, J Nassif, J Vinciguerra, M Rose, P Jaworski, D Gaier, J TI Lightweight highly conductive composites for EMI shielding SO SAMPE JOURNAL LA English DT Article AB Triton Systems, Inc., in cooperation with NASA/Glenn Research Center, has successfully addressed the problem of shielding electronic devices in space from EMI (electromagnetic interference) - with lower weight composite shields compared to presently used aluminum or tantalum shields. Triton has developed a new unique low-density composite EMI shield using NASA-developed bromine-intercalatedgGraphite paired to Triton's electrically conductive epoxy matrix. Both 1- and 2-ply composites have been prepared (only 0.36 and .72 mm thick) that have been shown to have EMI shielding equal to that of an aluminum control [for Q-band microwave radiation]. Because present aluminum EMI shields must be about 2 mm in thickness for strength arf a the new Triton/NASA shield can be as thin as 0.36 mm for equal strength and shielding, we have developed a potential weight savings of 88% compared to aluminum. Composites of bromine-intercalated graphite in epoxy were developed by NASA for EMI and have been improved upon by addition of Triton's unique conductive epoxy resin for the composite matrix. Triton's 100% polymeric conductive epoxy increases shielding effectiveness through enhanced surface and internal conductivity of the entire composite. Typical 2-ply composites have provided Q-band EMI shielding greater than 85dB. Furthermore, lightweight composites with high strength and stiffness can be made by conventional composite processing techniques. Data are presented on the EMI shielding performance of the Triton/NASA composite system. C1 Triton Syst Inc, Long Beach, MS 39560 USA. NASA, Glenn Res Ctr, Washington, DC 20546 USA. RP Harris, G (reprint author), Triton Syst Inc, Long Beach, MS 39560 USA. NR 8 TC 3 Z9 4 U1 0 U2 3 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 USA SN 0091-1062 J9 SAMPE J JI Sampe J. PD JUL-AUG PY 2000 VL 36 IS 4 BP 59 EP 63 PG 5 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 335NH UT WOS:000088249200012 ER PT J AU Thompson, WT Brekke, P AF Thompson, WT Brekke, P TI EUV full-Sun imaged spectral atlas using the SOHO coronal diagnostic spectrometer SO SOLAR PHYSICS LA English DT Article ID ULTRAVIOLET EMISSION-LINES; SOLAR TRANSITION REGION; QUIET-SUN; DOPPLER-SHIFT; DIFFRACTION GRATINGS; OBSERVED REDSHIFTS; FLOWS; SUMER; UV; SPECTROGRAPH AB The Coronal Diagnostic Spectrometer (CDS) aboard the Solar and Heliospheric Observatory (SOHO) carries out a regular program of measuring the full-disk irradiance using the Normal Incidence Spectrograph (NIS). The full-disk solar spectrum is returned in the wavelength bands 308-379 Angstrom and 513-633 Angstrom, with a spectral resolution between 0.3 and 0.6 Angstrom. A recent modification to the CDS on-board software allows simultaneous moderate resolution monochromatic images to be made of the stronger lines in these wavelength ranges. We report on observations made 23 April 1998, 21 May 1998, and 22 June 1998. A total of 69 monochromatic full-Sun images are extracted from the spectral line data. For the first time, spectrally resolved images of the full Sun in He II 303.8 Angstrom and Si xi 303.3 Angstrom are presented and compared. Velocity maps of the Sun in singly ionized helium are presented. Correlations of intensity to velocity over a wide range of transition region and coronal temperatures are shown. Lines from He I to Fe XIV show statistical red shifts of 1-7 km s(-1) between active regions and quiet Sun areas. Velocity maps of Mg IX and X are presented, showing strong upflow and downflow regions associated with active regions, but not correlated with the brightest emission. Changes in line width are also presented in He I, with discussion of similar features in other lines of comparable temperature. Corrections which need to be applied to CDS/NIS data to extract meaningful velocities and line widths are presented and discussed. The identifications of the lines in the CDS spectrum are examined. The spatial and spectral variation of the background component of the CDS spectrum is examined. C1 SM&A Corp, Div Space Sci, Largo, MD 20774 USA. NASA, Goddard Space Flight Ctr, ESA, Dept Space Sci, Greenbelt, MD 20771 USA. RP Thompson, WT (reprint author), SM&A Corp, Div Space Sci, 9315 Largo Dr W, Largo, MD 20774 USA. RI Thompson, William/D-7376-2012 NR 41 TC 20 Z9 20 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD JUL PY 2000 VL 195 IS 1 BP 45 EP 74 DI 10.1023/A:1005203001242 PG 30 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 362WJ UT WOS:000089801000003 ER PT J AU Reginald, NL Davila, JM AF Reginald, NL Davila, JM TI MACS for global measurement of the solar wind velocity and the thermal electron temperature during the total solar eclipse on 11 August 1999 SO SOLAR PHYSICS LA English DT Article AB MACS for Multi-Aperture Coronal Spectrometer is a fiber-optic-based spectrograph designed and used to perform global measurement of the solar wind velocity and the thermal electron temperature of the solar corona during the total solar eclipse on 11 August 1999. The motivation for the construction of MACS was provided by the theory formulated by Cram (1976) for the formation of the K-coronal spectrum and a method for determining the radial profile of the thermal electron temperature of the solar corona. Based on this theory a subsequent application was carried out by Ichimoto et al. (1996) using a slit-based spectroscopic study during the total solar eclipse on 3 November 1994. We have modified Cram's theory to incorporate the role of the solar wind velocity in the formation of the K-corona and have identified wind and temperature sensitive intensity ratios. Instead of a slit-based spectrograph MACS consists of twenty fiber optic tips placed at the focal plane of the telescope and positioned to see different radii and latitudes of the solar corona. Another fiber is placed at the center of the frame and uses the lunar shadow for a measure of the background signal. The other ends of the fibers are vertically aligned and placed at the primary focus of the collimating lens of the spectrograph thus providing simultaneous spectra from all of the fibers. In this first paper (Paper I) we describe our instrument and the obtained coronal spectra. The final and complete results will be presented in Paper II (Reginald and Davila, 2000). C1 Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Reginald, NL (reprint author), Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA. NR 5 TC 12 Z9 12 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD JUL PY 2000 VL 195 IS 1 BP 111 EP 122 DI 10.1023/A:1005251808764 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 362WJ UT WOS:000089801000006 ER PT J AU Spicer, D AF Spicer, D TI Eye in the Sky: The story of the CORONA spy satellites. SO TECHNOLOGY AND CULTURE LA English DT Book Review C1 NASA, Ames Res Ctr, Comp Museum, Hist Ctr, Moffett Field, CA 94035 USA. RP Spicer, D (reprint author), NASA, Ames Res Ctr, Comp Museum, Hist Ctr, Moffett Field, CA 94035 USA. NR 1 TC 0 Z9 0 U1 1 U2 3 PU JOHNS HOPKINS UNIV PRESS PI BALTIMORE PA JOURNALS PUBLISHING DIVISION, 2715 NORTH CHARLES ST, BALTIMORE, MD 21218-4319 USA SN 0040-165X J9 TECHNOL CULT JI Technol. Cult. PD JUL PY 2000 VL 41 IS 3 BP 633 EP 634 PG 2 WC History & Philosophy Of Science SC History & Philosophy of Science GA 339UB UT WOS:000088495300044 ER PT J AU Wertheimer, AC Heintz, RA Thedinga, JF Maselko, JM Rice, SD AF Wertheimer, AC Heintz, RA Thedinga, JF Maselko, JM Rice, SD TI Straying of adult pink salmon from their natal stream following embryonic exposure to weathered Exxon Valdez crude oil SO TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY LA English DT Article ID PRINCE-WILLIAM-SOUND; ALASKA; POPULATIONS AB Numbers of strays (adult salmon returning to a nonnatal stream:), straying rates, and distribution of strays were estimated for pink salmon incubated in oil-contaminated gravel and for an unexposed control group. The treatment groups were incubated in oiled gravel, which resulted in initial aqueous exposures for total polynuclear aromatic hydrocarbons (TPAHs) of 5 and 19 mu g/L for a low and high dose, respectively; the control group was incubated in gravel without oil. Fry from each treatment group were marked with coded wire tags (CWTs). The numbers of tagged fish released were 65,409 from the control; 69,441 from the low-dose group; and 70,414 from the high-dose group. A total of 288,492 pink salmon were sampled for CWTs when returning to spawn in the natal stream of the experimental fish, when returning to streams within 60 km of the natal stream, and when returning to two hatcheries within 100 km of the natal stream. The frequencies of observed strays were 0.023, 0.030, and 0.025 for the control, low-dose, and high-dose groups, respectively. Although the frequency of observed strays was 30% and 9% (respectively) higher than the controls for the low- and high-dose groups, the differences among treatments were not statistically significant, and the rates did not increase with TPAH dose. Estimates of the adult straying rates (with 95% confidence intervals) within a 35-km radius of the natal watershed were as follows: 5.3% (3.4-7.1%) for the control group; 9.2% (5.1-13.2%) for the low-dose group; and 5.7% (2.8-8.5%) for the high-dose group. Most (90%) strays were recovered within 10 km of the natal watershed. Exposed fish tended to be recovered at a greater distance from the natal stream than were control fish. The estimated percentage of strays recovered within 10 km was higher for the control group (95%) than for either the low-dose (81%) or high-dose (83%) groups, and only fish from oiled groups were recovered in distant fishing areas. However, these differences were also not statistically significant. Our results do not support the hypothesis that oil exposure of embryos in intertidal spawning grounds was responsible for the high rates of straying of wildstock pink salmon that were observed in Prince William Sound after the Exxon Valdez oil spill. C1 NOAA, Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Auke Bay Lab, Juneau, AK 99801 USA. RP Wertheimer, AC (reprint author), NOAA, Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Auke Bay Lab, 11305 Glacier Highway, Juneau, AK 99801 USA. NR 40 TC 10 Z9 11 U1 0 U2 10 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 USA SN 0002-8487 J9 T AM FISH SOC JI Trans. Am. Fish. Soc. PD JUL PY 2000 VL 129 IS 4 BP 989 EP 1004 DI 10.1577/1548-8659(2000)129<0989:SOAPSF>2.3.CO;2 PG 16 WC Fisheries SC Fisheries GA 342NW UT WOS:000088652700008 ER PT J AU Sulton, DL Boothe, M Ball, DW Morales, W AF Sulton, DL Boothe, M Ball, DW Morales, W TI Electron affinity calculations for thioethers SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT 53rd Annual Meeting of the Society-of-Tribologists-and-Lubrication-Engineers CY MAY 17-21, 1998 CL DETROIT, MICHIGAN SP Soc Tribologists & Lubricat Engineers DE high temperature tribology; vapor phase lubrication; chemistry ID VAPOR-PHASE LUBRICATION; TEMPERATURE AB Previous work indicated that polyphenyl thioethers possessed chemical properties, related to their electron affinities, which could allow them to function as vapor phase lubricants (VPL). Indeed preliminary tribological tests revealed that the thioethers could function as vapor phase lubricants but not over a wide temperature and Hertzian pressure range. Increasing the electron affinity of the thioethers may improve their VPL properties over this range. Adding a substituent group to the thioether will alter its electron affinity in many cases. Molecular orbital calculations were undertaken to determine the effect of five different substituent groups on the electron affinity of polyphenyl thioethers. It was Sound that the NO2, F, and I groups increased the thioethers electron affinity by the greatest amount. Future work will involve the addition of these groups to the thioethers followed by tribological resting to assess their VPL properties. C1 Cleveland State Univ, Cleveland, OH 44115 USA. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Sulton, DL (reprint author), Cleveland State Univ, Cleveland, OH 44115 USA. NR 17 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 1040-2004 J9 TRIBOL T JI Tribol. Trans. PD JUL PY 2000 VL 43 IS 3 BP 465 EP 468 DI 10.1080/10402000008982365 PG 4 WC Engineering, Mechanical SC Engineering GA 328CJ UT WOS:000087831000016 ER PT J AU Liang, SD Medich, D Czajkowsky, DM Sheng, ST Yuan, JY Shao, ZF AF Liang, SD Medich, D Czajkowsky, DM Sheng, ST Yuan, JY Shao, ZF TI Thermal noise reduction of mechanical oscillators by actively controlled external dissipative forces SO ULTRAMICROSCOPY LA English DT Article DE RMS noise; force; dissipation ID SQUEEZED STATES; MICROSCOPY; CANTILEVERS; OPERATION; LIGHT AB We show that the thermal fluctuations of very soft mechanical oscillators, such as the cantilever in an atomic force microscope (AFM), can be reduced without changing the stiffness of the spring or having to lower the environment temperature. We derive a theoretical relationship between the thermal fluctuations of an oscillator and an actively controlled external dissipative force. This relationship is verified by experiments with an AFM cantilever where the external active force is coupled through a magnetic field. With simple instrumentation, we have reduced the thermal noise amplitude of the cantilever by a factor of 3.4, achieving an apparent temperature of 25 K with the environment at 295 K. This active noise reduction approach can significantly improve the accuracy of static position or static force measurements in a number of practical applications. (C) 2000 Published by Elsevier Science B.V. All rights reserved. C1 Univ Virginia, Dept Mol Physiol & Biol Phys, Charlottesville, VA 22908 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Alberta Res Council, Edmonton, AB T6N 1E4, Canada. Univ Virginia, Dept Phys, Charlottesville, VA 22908 USA. RP Shao, ZF (reprint author), Univ Virginia, Dept Mol Physiol & Biol Phys, Box 449,Jordan Hall, Charlottesville, VA 22908 USA. RI Shao, Zhifeng/B-6075-2013; Medich, David/B-6006-2013 NR 27 TC 36 Z9 37 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0304-3991 J9 ULTRAMICROSCOPY JI Ultramicroscopy PD JUL PY 2000 VL 84 IS 1-2 BP 119 EP 125 DI 10.1016/S0304-3991(00)00039-5 PG 7 WC Microscopy SC Microscopy GA 328BA UT WOS:000087827900010 ER PT J AU Vander Wal, RL AF Vander Wal, RL TI Flame synthesis of substrate-supported metal-catalyzed carbon nanotubes SO CHEMICAL PHYSICS LETTERS LA English DT Article ID LARGE-SCALE; FULLERENES; GROWTH; HYDROCARBONS; PYROLYSIS; ACETYLENE; PARTICLES; ETHYLENE; COPPER AB The successful synthesis of carbon nanotubes within a flame environment using metal nanoparticles supported on TiO2. The nanotube structures reflect the metal catalyst particle shape. The name environment, furnishing molecular and atomic radical species allows stabilization of chevron, stack-of-cards and accordion basal layer plane arrangements. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, NCMR, Cleveland, OH 44135 USA. RP Vander Wal, RL (reprint author), NASA, NCMR, MS 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 27 TC 70 Z9 70 U1 1 U2 11 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JUN 30 PY 2000 VL 324 IS 1-3 BP 217 EP 223 DI 10.1016/S0009-2614(00)00492-9 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 330PF UT WOS:000087969900035 ER PT J AU Siegert, MJ Kwok, R AF Siegert, MJ Kwok, R TI Ice-sheet radar layering and the development of preferred crystal orientation fabrics between Lake Vostok and Ridge B, central East Antarctica SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Article DE Antarctica; ice; crystals; Vostok Station; ice cores AB Airborne radar data at 60 MHz are analysed to examine the flow of ice between the Ridge B ice divide and the Vostok Station subglacial lake in central East Antarctica. Interferometric SAR ice surface velocities show how three radar transects are aligned along the general direction of ice flow. Internal layering within the ice sheet is used to determine changes in the vertical component of ice flow along the transects. These data indicate ice sheet flow is related strongly to subglacial topography. In one transect, ice flows in a conventional base-parallel manner down a relatively uniform subglacial slope in the direction of ice flow. In the other two transects, internal layers show the flow of ice over a large subglacial hill upstream of Lake Vostok. Across the stoss face of this subglacial hill, analysis of the radar reflections from internal layers show that layers of ice with a preferred crystal orientation are likely to develop. This process results in layers of ice with a preferred crystal fabric across Lake Vostok at ice depths greater than similar to 2.8 km. Evidence to support our analysis comes from the Vostok ice core where layers of ice with noticeable crystal alignment are abundant at ice depths greater than 2.7 km. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Bristol, Sch Geog Sci, Bristol Glaciol Ctr, Bristol BS8 1SS, Avon, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Siegert, MJ (reprint author), Univ Bristol, Sch Geog Sci, Bristol Glaciol Ctr, Bristol BS8 1SS, Avon, England. RI Siegert, Martin/A-3826-2008; Kwok, Ron/A-9762-2008 OI Siegert, Martin/0000-0002-0090-4806; Kwok, Ron/0000-0003-4051-5896 NR 13 TC 20 Z9 22 U1 0 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-821X J9 EARTH PLANET SC LETT JI Earth Planet. Sci. Lett. PD JUN 30 PY 2000 VL 179 IS 2 BP 227 EP 235 DI 10.1016/S0012-821X(00)00121-7 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 330DJ UT WOS:000087947300002 ER PT J AU Anderson, SW Stofan, ER Smrekar, SE Guest, JE Wood, B AF Anderson, SW Stofan, ER Smrekar, SE Guest, JE Wood, B TI Reply to: Self et al. discussion of "Pulsed inflation of pahoehoe lava flows: implications for flood basalt emplacement" SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Editorial Material ID CRYSTALLIZATION C1 Black Hills State Univ, Spearfish, SD 57799 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ London Observ, London NW7 2QS, England. RP Anderson, SW (reprint author), Black Hills State Univ, Spearfish, SD 57799 USA. NR 14 TC 10 Z9 10 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-821X J9 EARTH PLANET SC LETT JI Earth Planet. Sci. Lett. PD JUN 30 PY 2000 VL 179 IS 2 BP 425 EP 428 DI 10.1016/S0012-821X(00)00124-2 PG 4 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 330DJ UT WOS:000087947300018 ER PT J AU Remer, DS Buchanan, HR AF Remer, DS Buchanan, HR TI Estimating the cost for doing a cost estimate SO INTERNATIONAL JOURNAL OF PRODUCTION ECONOMICS LA English DT Article DE cost estimate; model; construction industry AB This article provides a model for estimating the cost required to do a cost estimate. The cost of the cost estimate in thousands of dollars, C-E, is found to be approximatery given by C-E = KCP0.35, where C-P is the estimated cost of the project in millions of dollars and K is a constant depending on the desired accuracy of the estimate, the maturity of the technology, and the cost elements included in C-P and C-E. Our earlier work provided data for high-technology projects. This article adds data from the construction industry which validates the model over a wider range of technology. (C) 2000 Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Remer, DS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 2 Z9 2 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0925-5273 J9 INT J PROD ECON JI Int. J. Prod. Econ. PD JUN 30 PY 2000 VL 66 IS 2 BP 101 EP 104 DI 10.1016/S0925-5273(99)00117-6 PG 4 WC Engineering, Industrial; Engineering, Manufacturing; Operations Research & Management Science SC Engineering; Operations Research & Management Science GA 328HU UT WOS:000087845400001 ER PT J AU Bautista, MA AF Bautista, MA TI Photoionization of Fe XV from threshold to the K-shell SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID CROSS-SECTIONS; PHOTOABSORPTION; IONIZATION; IRON; EDGE; IONS AB The photoionization cross section of Mg-like Fe xv is calculated from the first ionization threshold to 700 Ryd using the R-matrix method. The detailed structure and resonances of the cross section across the L- and K-shell thresholds is described. These resonances are shown to enhance the photoionization rate of Fe xv by up to several factors, when illuminated by an x-ray flux. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Bautista, MA (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NR 20 TC 12 Z9 13 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD JUN 28 PY 2000 VL 33 IS 12 BP L419 EP L426 DI 10.1088/0953-4075/33/12/101 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 335FE UT WOS:000088232500001 ER PT J AU Becker, G Muller, R McKenna, DS Rex, M Carslaw, KS Oelhaf, H AF Becker, G Muller, R McKenna, DS Rex, M Carslaw, KS Oelhaf, H TI Ozone loss rates in the Arctic stratosphere in the winter 1994/1995: Model simulations underestimate results of the Match analysis SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID IN-SITU MEASUREMENTS; ANTARCTIC OZONE; NITRIC-ACID; FEBRUARY 1995; DEPLETION; AEROSOL; VORTEX; CHLORINE; CLOUDS; DENITRIFICATION AB We present box model simulations of ozone loss rates in the Arctic lower stratosphere for the winter 1994/1995, The ozone loss was simulated along each of the trajectories of the Match data set for 1994/1995 to conduct a quantitative comparison with the Match results, The simulated ozone loss rates reach their maximum value of approximate to 4 ppb per sunlit hour at the end of January, For this period and for potential temperatures below 475 K the model results are in good agreement with the Match results, but for potential temperatures above 475 K the model underestimates the ozone loss rate by up to a factor of 2. This difference cannot be explained by known uncertainties of the model. Enhanced ozone loss has also been observed in March 1995 for potential temperatures below 475 K. These loss rates are also substantially underestimated by the model, but are within the range of the model uncertainties, In particular, the ozone loss rates simulated for March 1995 strongly depend on the extent of denitrification. C1 Forschungszentrum Julich, Inst Stratosphar Chem IGC 1, D-52425 Julich, Germany. Forschungszentrum Karlsruhe, Inst Meteorol & Klimaforsch, D-76021 Karlsruhe, Germany. CALTECH, Jet Prop Lab, Pasadena, CA USA. Max Planck Inst Chem, Mainz, Germany. RP Forschungszentrum Julich, Inst Stratosphar Chem IGC 1, Postfach 1913, D-52425 Julich, Germany. EM ro.mueller@fz-juelich.de; mrex@awi-potsdam.de; carslaw@lec.leeds.ac.uk; oelhaf@imk.fzk.de RI Rex, Markus/A-6054-2009; Muller, Rolf/A-6669-2013; Oelhaf, Hermann/A-7895-2013; Carslaw, Ken/C-8514-2009; McKenna, Daniel/E-7806-2014 OI Rex, Markus/0000-0001-7847-8221; Muller, Rolf/0000-0002-5024-9977; Carslaw, Ken/0000-0002-6800-154X; McKenna, Daniel/0000-0002-4360-4782 NR 49 TC 37 Z9 37 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 27 PY 2000 VL 105 IS D12 BP 15175 EP 15184 DI 10.1029/2000JD900056 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 328HP UT WOS:000087844900005 ER PT J AU Pierson, JM Kawa, SR Salawitch, RJ Hanisco, TF Lauzendorf, EJ Perkins, KK Gao, RS AF Pierson, JM Kawa, SR Salawitch, RJ Hanisco, TF Lauzendorf, EJ Perkins, KK Gao, RS TI Influence of air mass histories on radical species during the Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) mission SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID IN-SITU MEASUREMENTS; LOWER STRATOSPHERE; MIDDLE STRATOSPHERE; REACTIVE NITROGEN; CHLORINE RADICALS; AIRCRAFT; TRANSPORT; SPECTROMETER; TROPOSPHERE; SATELLITE AB The Goddard trajectory chemistry model was used with ER-2 aircraft data to test our current knowledge of radical photochemistry during the Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) campaign. The results of the trajectory chemistry model with and without trajectories are used to identify cases where steady state does not accurately describe the measurements. Over the entire mission, using trajectory chemistry reduces the variability in the modeled NOx comparisons to data by 25% with respect to the same model simulating steady state. Although the variability is reduced, NOx/NOy trajectory model results were found to be systematically low relative to the observations by 20-30% as seen in previous studies, Using new rate constants for reactions important in NOy partitioning improves the agreement of NOx/NOy with the observations but a 5-10% bias still exists. OH and HO2 individually are underpredicted by 15% of the standard steady state model and worsen with the new rate constants. Trajectory chemistry model results of OH/HO2 were systematically low by 10-20% but improve using the new rates constants because of the explicit dependence on NO. This suggests that our understanding of NOx is accurate to the 20% level and HOx chemistry is accurate to the 30% level in the lower stratosphere or better for the POLARIS regime. The behavior of the NOx and HOx comparisons to data using steady state versus trajectory chemistry and with updated rate coefficients is discussed in terms of known chemical mechanisms and lifetimes. C1 Univ Space Res Assoc, Seabrook, MD 20706 USA. NOAA, Aeron Lab, Colorado Springs, CO 80903 USA. Harvard Univ, Dept Chem, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Atmospher Chem & Dynam Branch, Greenbelt, MD 20771 USA. CALTECH, Jet Prop Lab, NASA, Pasadena, CA 91125 USA. RP Univ Space Res Assoc, Seabrook, MD 20706 USA. EM pierson@polska.gsfc.nasa.gov RI Salawitch, Ross/B-4605-2009; Kawa, Stephan/E-9040-2012; Gao, Ru-Shan/H-7455-2013 OI Salawitch, Ross/0000-0001-8597-5832; NR 45 TC 4 Z9 4 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 27 PY 2000 VL 105 IS D12 BP 15185 EP 15199 DI 10.1029/2000JD900111 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 328HP UT WOS:000087844900006 ER PT J AU Burns, SP Khelif, D Friehe, CA Hignett, P Williams, AG Grant, ALM Hacker, JM Hagan, DE Serra, YL Rogers, DP Bradley, EF Weller, RA Fairall, CW Anderson, SP Paulson, CA Coppin, PA AF Burns, SP Khelif, D Friehe, CA Hignett, P Williams, AG Grant, ALM Hacker, JM Hagan, DE Serra, YL Rogers, DP Bradley, EF Weller, RA Fairall, CW Anderson, SP Paulson, CA Coppin, PA TI Comparisons of aircraft, ship, and buoy radiation and SST measurements from TOGA COARE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERE RESPONSE EXPERIMENT; PRECISION INFRARED RADIOMETERS; EQUATORIAL PACIFIC-OCEAN; SEA-SURFACE TEMPERATURE; POOL BOUNDARY-LAYER; WARM POOL; TRANSPORT PROCESSES; FLUXES; CALIBRATION; VARIABILITY AB Mean radiative fluxes and sea surface temperature measured by the five Tropical Ocean-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) boundary layer research aircraft were compared with each other and with surface measurements from moored buoys and ships. The basic data-processing techniques for radiative flux and sea surface temperature (SST) measurements from an aircraft were reviewed, and an empirical optimisation method to calibrate an Eppley pyrgeometer was introduced. On the basis of aircraft wingtip-to-wingtip comparison periods, the processed aircraft downwelling shortwave and longwave irradiance and SST measurements were found to agree to 28+/-18 W m(-2), 9+/-4 W m(-2), and 0.7+/-0.4 degrees C, respectively. By using the same comparison periods, empirical corrections that removed systematic errors in the aircraft data were determined. Application of these corrections improved the wingtip comparison accuracy to 3+/-16 W m(-2), 1+/-4 W m(-2), and 0.1+/-0.3 degrees C, respectively. Comparisons between the (fully corrected) aircraft and the surface platform measurements revealed the aircraft data to be slightly greater for all three parameters. The agreement was around 3+/-37 W m(-2), 3+/-6 W m(-2), and 0.3+/-0.5 degrees C for shortwave irradiance, longwave irradiance, and SST, respectively. (Detailed comparison results were provided for each individual ship and buoy.) After applying the aircraft Empirical corrections the level of accuracy was near the COARE objectives. C1 Univ Calif Irvine, Dept Mech & Aerosp Engn, Irvine, CA 92697 USA. Minist Def, Meteorol Suppport Grp DG R&T, London, England. Hadley Ctr Climate Predict & Res, Bracknell, Berks, England. Flinders Inst Atmospher & Marine Sci, Adelaide, SA, Australia. CALTECH, Jet Prop Lab, Pasadena, CA USA. Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA. Commonwealth Sci & Ind Res Org Land & Water, Canberra, ACT, Australia. Woods Hole Oceanog Inst, Woods Hole, MA 02543 USA. Environm Technol Lab, Boulder, CO USA. Oregon State Univ, Coll Ocean & Atmospher Sci, Corvallis, OR 97331 USA. RP Natl Ctr Atmospher Res, Mesoscale & Microscale Meteorol Div, POB 3000, Boulder, CO 80307 USA. EM sean@ucar.edu; dkhelif@uci.edu; cfriehe@uci.edu; phignett.msg.mod@gtnet.gov.uk; awilliams@meto.gov.uk; almgrant@meto.gov.uk; j.hacker@es.flinders.edu.au; Denise.E.Hagan@jpl.nasa.gov; serra@pmel.noaa.gov; drogers@ucsd.edu; frank.bradley@cbr.clw.csiro.au; rweller@whoi.edu; cfairall@etl.noaa.gov; sanderson@whoi.edu; paulson@oce.orst.edu; peter.coppin@cbr.clw.csiro.au RI Burns, Sean/A-9352-2008; Bradley, Frank/I-6574-2013; Williams, Alastair/P-6946-2014; Serra, Yolande/I-3457-2015 OI Burns, Sean/0000-0002-6258-1838; Williams, Alastair/0000-0002-0568-8487; Serra, Yolande/0000-0003-3542-1158 NR 40 TC 10 Z9 10 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 27 PY 2000 VL 105 IS D12 BP 15627 EP 15652 DI 10.1029/2000JD900090 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 328HP UT WOS:000087844900035 ER PT J AU Callis, LB AF Callis, LB TI Comment on "The diffuse aurora: A significant source of ionization in the middle atmosphere" by R. A. Frahm et al. SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Editorial Material ID REACTIVE NITROGEN; STRATOSPHERE; ELECTRONS; OZONE; NOY C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP NASA, Langley Res Ctr, Div Atmospher Sci, Mail Stop 401B, Hampton, VA 23681 USA. EM lbc@jaguar.larc.nasa.gov NR 18 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 27 PY 2000 VL 105 IS D12 BP 15681 EP 15684 DI 10.1029/2000JD900117 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 328HP UT WOS:000087844900039 ER PT J AU Young, JA Hinkley, JA Farmer, BL AF Young, JA Hinkley, JA Farmer, BL TI Molecular simulations of the imidization of adsorbed polyamic acid SO MACROMOLECULES LA English DT Article ID ULTRATHIN POLYMER-FILMS; DYNAMICS SIMULATIONS; AB-INITIO; COMPUTER-SIMULATION; SOLID-SURFACES; POLYIMIDE; SILICA; MELTS; SITES; HYDROCARBONS AB Computer simulations have been developed to investigate the intramolecular cyclization of polyimides (i.e., imidization, the conversion of the precursor polyamic acid into polyimide). Imidization was examined as a function of time, temperature, and presence or absence of a silica substrate. To do this, the essential results of quantum mechanical studies were incorporated into a molecular dynamics simulation. Molecular dynamics simulations were used to determine the conformational properties of the polymer chain and to simulate the imidization reaction when the conformational criteria established by quantum mechanical methods were met. In agreement with experiments, imidization occurred in two distinct stages, and increased temperatures were shown to produce higher extents of imidization. Finally, the interfacial chains exhibited more complete imidization than the isolated chains. These results not only support the proposed molecular rationale behind the kinetic models of imidization but also demonstrate that only local chain motions are necessary for imidization to occur. C1 Univ Virginia, Dept Mat Sci & Engn, Charlottesville, VA 22903 USA. NASA, Langley Res Ctr, Div Mat, Hampton, VA 23681 USA. RP Young, JA (reprint author), Univ Calif Lawrence Livermore Natl Lab, L 474, Livermore, CA 94550 USA. NR 41 TC 3 Z9 3 U1 0 U2 6 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0024-9297 J9 MACROMOLECULES JI Macromolecules PD JUN 27 PY 2000 VL 33 IS 13 BP 4936 EP 4944 DI 10.1021/ma991639u PG 9 WC Polymer Science SC Polymer Science GA 329HD UT WOS:000087900800048 ER PT J AU Segall, K Wilson, C Frunzio, L Li, L Friedrich, S Gaidis, MC Prober, DE Szymkowiak, AE Moseley, SH AF Segall, K Wilson, C Frunzio, L Li, L Friedrich, S Gaidis, MC Prober, DE Szymkowiak, AE Moseley, SH TI Noise mechanisms in superconducting tunnel-junction detectors SO APPLIED PHYSICS LETTERS LA English DT Article ID X-RAY AB We present a theory and measurements of noise mechanisms in superconducting tunnel-junction detectors used as single-photon spectrometers. These mechanisms result from incomplete cooling of the excited quasiparticles in the tunnel-junction electrode. Due to the incomplete cooling, only a fraction of the initially created charge is collected by tunneling. Additional effects include reduced dynamic resistance, voltage dependence of the integrated charge, and increased statistical broadening of the signal. We demonstrate these noise mechanisms in our device, and show that they explain the measured energy resolution of 25 eV at 5.9 keV. We also suggest ways to reduce their contribution in future devices. (C) 2000 American Institute of Physics. [S0003-6951(00)03526-9]. C1 Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Segall, K (reprint author), Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. RI Wilson, Christopher/A-9676-2008; Moseley, Harvey/D-5069-2012; Gaidis, Michael/D-3327-2013; OI Frunzio, Luigi/0000-0002-0272-5481 NR 13 TC 38 Z9 38 U1 1 U2 2 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUN 26 PY 2000 VL 76 IS 26 BP 3998 EP 4000 DI 10.1063/1.126796 PG 3 WC Physics, Applied SC Physics GA 326EM UT WOS:000087719800050 ER PT J AU Mills, FP Brown, ME AF Mills, FP Brown, ME TI Thermal infrared spectroscopy of Europa and Callisto SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID ICY GALILEAN SATELLITES; MU-M; REFLECTANCE SPECTRA; MAPPING SPECTROMETER; SURFACE; MINERALS; EMISSION; FROST; SNOW; SCATTERING AB The trailing hemispheres of Europa and Callisto were observed at 9 - 13 mu m, and a spectrum of Europa with better spectral resolution and a better signal-to-noise ratio than was previously possible has been derived. The ratio spectrum of the two satellites has a signal-to-noise ratio of approximately 30 for a spectral resolving power of approximately 50. The disk-integrated, effective color temperature ratio for the two satellites is consistent with broadband, thermal infrared photometry from previous ground-based studies and from the Galileo photopolarimeter radiometer. The ratio spectrum was combined with the average Voyager 1 spectrum of Callisto to obtain a 9 - 13 mu m spectrum of Europa with a signal-to-noise ratio that is a factor of 10 better than that in the average Voyager spectrum of Europa. After convolving the measured spectrum to the expected width of water ice emissivity features, similar to 1 mu m, no spectral features that could be attributed to water ice on the surface of Europa are apparent at the 0.6 - 0.7% level. The absence of spectral features attributable to water ice is consistent with the proposal that the equatorial region of Europa that was observed may be composed primarily of a heavily hydrated mineral. The absence of water ice features may also be the result of a large fractional abundance of fine particles, such as that found on the surface of the Moon. C1 CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. RP Mills, FP (reprint author), CALTECH, Jet Prop Lab, M-C 183-901,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 41 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JUN 25 PY 2000 VL 105 IS E6 BP 15051 EP 15059 DI 10.1029/1999JE001163 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 328MK UT WOS:000087854500003 ER PT J AU Mahaffy, PR Niemann, HB Alpert, A Atreya, SK Demick, J Donahue, TM Harpold, DN Owen, TC AF Mahaffy, PR Niemann, HB Alpert, A Atreya, SK Demick, J Donahue, TM Harpold, DN Owen, TC TI Noble gas abundance and isotope ratios in the atmosphere of Jupiter from the Galileo Probe Mass Spectrometer SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID GIANT PLANETS; SOLAR; ORIGIN AB The Galileo Probe Mass Spectrometer provided the first data on the noble gas mixing and isotope ratios in the Jovian atmosphere. These measurements and the comparison with solar values constrain models of Jupiter's formation. Significant refinements to the initially reported abundances of argon, krypton, and xenon have been enabled through post-encounter laboratory calibrations using a refurbished engineering unit mass spectrometer nearly identical to the flight unit. The abundances relative to hydrogen for argon, krypton, and xenon are respectively 2.5 +/- 0.5, 2.7 +/- 0.5, and 2.6 +/- 0.5 times the solar ratios. The mixing ratios of He and Ne found in these studies are consistent with previously reported values of 0.8 and 0.1 times solar respectively. The Jovian (36)Ar/(38)Ar ratio is 5.6 +/- 0.25 and the (20)Ne/(22)Ne ratio is 13 +/- 2, consistent with the solar values of 5.77 and 13.81, respectively, that are derived from lunar mineral grain analysis. The distribution of xenon isotopes at Jupiter also resembles the solar distribution. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Univ Arizona, Dept Planetary Sci, Tucson, AZ 85721 USA. Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. Auburn Univ, Dept Engn, Auburn, AL 36830 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. RP Mahaffy, PR (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Code 915, Greenbelt, MD 20771 USA. EM paul.r.mahaffy@gsfc.nasa.gov RI Mahaffy, Paul/E-4609-2012; Harpold, Dan/I-3345-2013 NR 17 TC 83 Z9 84 U1 0 U2 8 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 25 PY 2000 VL 105 IS E6 BP 15061 EP 15071 DI 10.1029/1999JE001224 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 328MK UT WOS:000087854500004 ER PT J AU Potter, AE Killen, RM Morgan, TH AF Potter, AE Killen, RM Morgan, TH TI Variation of lunar sodium during passage of the Moon through the Earth's magnetotail SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID LEONID METEOR-SHOWER; ATMOSPHERE; MERCURY; SURFACE; DESORPTION; EXOSPHERE; ORIGIN AB We measured sodium emission above the lunar equator over a range of lunar altitudes from 100 to 4000 km. The measurements were repeated approximately every 24 hours from June 7 to 16, 1998, covering the period during which the Moon passed through the Earth's magnetotail. Sodium temperatures derived from the altitude dependence of emission intensity ranged from 1200 to 2900 K. This result supports the view that photodesorption is a primary source of sodium in the exosphere since the most probable temperature of sodium from this source is in this range. Passage of the Moon through the Earth's magnetotail (where solar wind is essentially absent) affected the sodium density, such that it was higher before the Moon entered the Earth's magnetotail than after the Moon left it. This suggests that the solar wind plays a role in production of lunar sodium, We propose that its function is to mobilize sodium and bring it to the surface, where photodesorption can eject it into the exosphere. A two-step process such as this could help to explain the latitude dependence of sodium density, which varies as the second or higher power of cosine latitude. C1 Lunar & Planetary Inst, Houston, TX 77058 USA. SW Res Inst, San Antonio, TX 78228 USA. NASA, Res Program Management, Washington, DC 20546 USA. RP Potter, AE (reprint author), Lunar & Planetary Inst, 3600 Bay Area Blvd, Houston, TX 77058 USA. RI Morgan, Thomas/I-5943-2013 NR 32 TC 44 Z9 44 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 25 PY 2000 VL 105 IS E6 BP 15073 EP 15084 DI 10.1029/1999JE001213 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 328MK UT WOS:000087854500005 ER PT J AU Ricca, A AF Ricca, A TI Heats of formation for ClFn (n=1-3) SO CHEMICAL PHYSICS LETTERS LA English DT Article ID GAUSSIAN-BASIS SETS; CORRELATED MOLECULAR CALCULATIONS; COUPLED-CLUSTER THEORY; ATOMIZATION ENERGIES; ELECTRON CORRELATION; WAVE-FUNCTIONS; THERMOCHEMISTRY AB Accurate heats of formation have been computed for ClFn (n = 1-3). The accuracy of the results is strongly dependent on the basis set quality and it is crucial to add at least one tight d function to Cl. The atomization energies are corrected for scalar relativistic, core-valence, spin-orbit, thermal effects, and zero-point energy. Our heats of formations are in very good agreement with the experimental values reported by Gurvich therefore suggesting that the JANAF values are slightly underestimated. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Eloret Corp, Moffett Field, CA 94035 USA. RP Ricca, A (reprint author), NASA, Ames Res Ctr, Eloret Corp, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 31 TC 8 Z9 8 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 JUN 23 PY 2000 VL 323 IS 5-6 BP 498 EP 505 DI 10.1016/S0009-2614(00)00562-5 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 327XG UT WOS:000087819300018 ER PT J AU Goldin, DS AF Goldin, DS TI Contributions to the US space program SO SCIENCE LA English DT Letter C1 NASA, Washington, DC 20546 USA. RP Goldin, DS (reprint author), NASA, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD JUN 23 PY 2000 VL 288 IS 5474 BP 2131 EP 2131 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 327FH UT WOS:000087782900014 PM 10896580 ER PT J AU Llorente, IM Diskin, B Melson, ND AF Llorente, IM Diskin, B Melson, ND TI Alternating plane smoothers for multiblock grids SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE robust multigrid methods; multiblock grids; anisotropic discrete operators ID ANISOTROPIC COEFFICIENTS; MULTIGRID SOLVERS; FLOW AB Standard multigrid methods are not well suited for problems with anisotropic discrete operators, which can occur, for example, on grids that are stretched in order to resolve a boundary layer. One of the most efficient approaches to yield robust methods is the combination of standard coarsening with alternating-direction plane relaxation in the three dimensions. However, this approach may be difficult to implement in codes with multiblock structured grids because there may be no natural definition of global lines or planes. This inherent obstacle limits the range of an implicit smoother to only the portion of the computational domain in the current block. This report studies in detail, both numerically and analytically the behavior of blockwise plane smoothers in order to provide guidance to engineers who use block-structured grids. The results obtained so far show alternating-direction plane smoothers to be very robust, even on multiblock grids. In common computational fluid dynamics multiblock simulations, where the number of subdomains crossed by the line of a strong anisotropy is low (up to four), textbook multigrid convergence rates can be obtained with a small overlap of cells between neighboring blocks. C1 Univ Complutense, Dept Arquitectura Comp & Automat, E-28040 Madrid, Spain. NASA, Inst Comp Applicat Sci & Engn, Langley Res Ctr, Hampton, VA 23681 USA. NASA, Aerodynam & Aeroacoust Methods Branch, Langley Res Ctr, Hampton, VA 23681 USA. RP Llorente, IM (reprint author), Univ Complutense, Dept Arquitectura Comp & Automat, E-28040 Madrid, Spain. RI Martin Llorente, Ignacio/B-2093-2009 OI Martin Llorente, Ignacio/0000-0001-6230-8180 NR 25 TC 1 Z9 1 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 1064-8275 J9 SIAM J SCI COMPUT JI SIAM J. Sci. Comput. PD JUN 23 PY 2000 VL 22 IS 1 BP 218 EP 242 DI 10.1137/S106482759935736X PG 25 WC Mathematics, Applied SC Mathematics GA 334BP UT WOS:000088165500011 ER PT J AU Loh, CY Hui, WH AF Loh, CY Hui, WH TI A new Lagrangian method for time-dependent inviscid flow computation SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE Lagrangian description; TVD scheme; inviscid unsteady ow ID REAL-GAS FLOWS; GODUNOV SCHEME; RESOLUTION AB This paper presents a new Lagrangian approach for the two-dimensional (2- D) time-dependent Euler equations. It may be considered as a sequel to the authors previous Lagrangian approaches for steady supersonic flow computations [C. Y. Loh and W. H. Hui, J. Comput. Phys., 89 (1990), pp. 207-240; W. H. Hui and C. Y. Loh, J. Comput. Phys., 103 (1992), pp. 450-464; W. H. Hui and C. Y. Loh, J. Comput. Phys., 103 (1992), pp. 465-471; C. Y. Loh and M. S. Liou, J. Comput. Phys., 104 (1993), pp. 150-161; C. Y. Loh and M. S. Liou, SIAM J. Sci. Comput., 15 (1994), pp. 1038-1058; C. Y. Loh and M. S. Liou, J. Comput. Phys., 113 (1994), pp. 224-248]. The theoretical background and the intrinsic ow coordinates as well as the Lagrangian conservation form are introduced based on the concept of material functions ( or path functions). A TVD scheme of the Godunov type is chosen to describe the numerical procedure. Several examples are then given to justify the claimed advantages of the new methodology, namely, (a) any contact discontinuities are crisply solved and (b) grids are automatically and accurately generated following pathlines. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Taitech Inc, Cleveland, OH 44135 USA. Hong Kong Univ Sci & Technol, Dept Math, Clear Water Bay, Hong Kong, Peoples R China. RP NASA, Glenn Res Ctr, MS 5-11, Cleveland, OH 44135 USA. EM fsloh@turbot.grc.nasa.gov; whhui@uxmail.ust.hk NR 23 TC 1 Z9 1 U1 0 U2 2 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 1064-8275 EI 1095-7197 J9 SIAM J SCI COMPUT JI SIAM J. Sci. Comput. PD JUN 23 PY 2000 VL 22 IS 1 BP 330 EP 350 DI 10.1137/S1064827597330856 PG 21 WC Mathematics, Applied SC Mathematics GA 334BP UT WOS:000088165500016 ER PT J AU Bauschlicher, CW AF Bauschlicher, CW TI TaFn and TaCln atomization energies for n=1-5 SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID GAUSSIAN-BASIS SETS; CORRELATED MOLECULAR CALCULATIONS; RELATIVISTIC EFFECTIVE POTENTIALS; COUPLED-CLUSTER THEORY; SPIN-ORBIT OPERATORS; ELECTRON CORRELATION; WAVE-FUNCTIONS; EXCHANGE AB TaFn and TaCln atomization energies are computed for n = 1-5. The geometries, frequencies, and atomization energies are determined using density functional theory. Both the BP86 and B3LYP functionals are used. Our best atomization energies are obtained by scaling the DFT results on the basis of the experimental TaX5 atomization energies and including a correction for spin-orbit effects. For TaFn, our corrected values are in good agreement with experiment. For TaF, TaCl, and TaCl2 the atomization energies are also computed at the coupled cluster level of theory in conjunction with relativistic effective core potentials. The CCSD(T) complete basis set (CBS) limit is obtained by extrapolation. The scaled DFT values are in good agreement with these CCSD(T) CBS values. The TaF, results and the calibration calculations suggest that the scaled TaCln DFT atomization energies are accurate to 3-5 kcal/mol. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 29 TC 3 Z9 3 U1 1 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5639 J9 J PHYS CHEM A JI J. Phys. Chem. A PD JUN 22 PY 2000 VL 104 IS 24 BP 5843 EP 5849 DI 10.1021/jp994344r PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 327FG UT WOS:000087782800021 ER PT J AU Sanders, AJ Alexeev, AD Allison, SW Antonov, V Bronnikov, KA Campbell, JW Cates, MR Corcovilos, TA Earl, DD Gadfort, T Gillies, GT Harris, MJ Kolosnitsyn, NI Konstantinov, MY Melnikov, VN Newby, RJ Schunk, RG Smalley, LL AF Sanders, AJ Alexeev, AD Allison, SW Antonov, V Bronnikov, KA Campbell, JW Cates, MR Corcovilos, TA Earl, DD Gadfort, T Gillies, GT Harris, MJ Kolosnitsyn, NI Konstantinov, MY Melnikov, VN Newby, RJ Schunk, RG Smalley, LL TI Project SEE (Satellite Energy Exchange): an international effort to develop a space-based mission for precise measurements of gravitation SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article; Proceedings Paper CT International Symposium on Experimental Gravitation CY AUG 16-21, 1999 CL SAMARKAND, UZBEKISTAN ID INTERACTION PARAMETERS; PHYSICAL CONSTANTS; EARTH SATELLITE; PULSARS; TIME AB Project SEE (Satellite Energy Exchange) is an international effort to develop a space-based mission for precise measurements of gravitation. Gravity is the missing link in unification theory. Because of the unique paucity of knowledge about this, the weakest of all known forces, and because gravity must have a key role in any unification theory, many aspects of gravity need to be understood in greater depth. A SEE mission would extend our knowledge of a number of gravitational parameters and effects, which are needed to test unification theories and various modern theories of gravity. SEE is a comprehensive gravitation experiment. A SEE mission would test for violations of the equivalence principle (EP), both by inverse-square-law (ISL) violations and by composition dependence (CD), both at ranges of the order of metres and at ranges on the order of R-E. A SEE mission would also determine the gravitational constant G, test for time variation of G, and possibly test for post-Einsteinian orbital resonances. The potential finding of a nea-zero time variation of G is perhaps the most important aspect of SEE. A SEE mission will also involve a search for new particles with very low masses, since any evidence of violations of the EP would be analysed in terms of a putative new Yukawa-like particle. Thus, SEE does not merely test for violations of general relativity (GR); SEE is a next-generation gravity mission. C1 Univ Tennessee, Dept Phys & Astron, Knoxville, TN 37996 USA. VNIIIMS, Ctr Gravitat & Fundamental Metrol, Russian Gravitat Soc, Moscow 117313, Russia. Engn Technol Div, Oak Ridge, TN 37831 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Sch Engn & Appl Sci, Dept Mech & Aerosp Engn, Charlottesville, VA 22904 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. RP Sanders, AJ (reprint author), Univ Tennessee, Dept Phys & Astron, 401 Nielsen Bldg, Knoxville, TN 37996 USA. OI Corcovilos, Theodore/0000-0001-5716-1188; Newby, Robert/0000-0003-3571-1067; Allison, Stephen/0000-0002-5887-5403; Bronnikov, Kirill/0000-0001-9392-7558 NR 40 TC 17 Z9 17 U1 0 U2 4 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0264-9381 EI 1361-6382 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD JUN 21 PY 2000 VL 17 IS 12 BP 2331 EP 2346 DI 10.1088/0264-9381/17/12/305 PG 16 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 335QG UT WOS:000088255200006 ER EF